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Nov 1995

Volume 13, Issue 6, pp. 2651-3003


Supersonic molecular beam scattering as a probe of thin film deposition processes

L.‐Q. Xia, M. E. Jones, N. Maity, and J. R. Engstrom

J. Vac. Sci. Technol. A 13, 2651 (1995); http://dx.doi.org/10.1116/1.579464 (14 pages) | Cited 29 times

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The reactions of silane, SiH4, disilane, Si2H6, and phosphine, PH3, on single crystalline Si(100) and Si(111) surfaces, and methylsilane, SiH3CH3, on a β‐SiC surface have been examined employing supersonic molecular beam scattering. The emphasis here is not on any one experimental result, but rather on the specific experimental approaches adopted and a selected set of results that serve to demonstrate the similarities and differences between these systems and the more extensively studied reactions occurring on transition metal surfaces. All reactions have been examined at substrate temperatures characteristic of steady‐state thin film growth. Translational activation is observed to be an efficient means to promote the reactivity of the group IV species: SiH4, Si2H6, and SiH3CH3. In all cases, the reactivity increases exponentially with scaled incident kinetic energy, where the scaling analysis specifically takes into account the microcorrugation of the gas‐surface potential in terms of how incident kinetic energy and angle of incidence couple to determine the probability of dissociative chemisorption. The reaction probability of SiH4 is described quantitatively over a wide range of reaction conditions by a recently published model that adapts Rice–Ramsperger–Kassel–Marcus theory to translationally activated dissociative chemisorption. In contrast, PH3, due to its coordinative unsaturation, is found to react almost exclusively via a trapping‐mediated precursor dissociation channel. By employing a novel analysis scheme, the dependence of PH3 dissociative chemisorption on the fractional coverage of both P(a) and H(a) has been deduced under conditions where the desorption of H2 and P2 are finite. The experimental techniques described here, and the associated conclusions made in this work, should be of tremendous value in future studies directed at examinations of the gas‐surface chemistry involved in epitaxial thin film growth. © 1995 American Vacuum Society
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis

Effect of surface excitations in determining the inelastic mean free path by elastic peak electron spectroscopy

Y. F. Chen

J. Vac. Sci. Technol. A 13, 2665 (1995); http://dx.doi.org/10.1116/1.579465 (6 pages) | Cited 5 times

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Elastic peak electron spectroscopy (EPES) has been widely used to determine the electron inelastic mean free paths (IMFPs) in solids. In this work the influence of surface excitations in determining the IMFP by EPES is investigated. An extended Drude dielectric function is employed to estimate the probability of surface excitations for incident and reflected electrons by including the recoil effect without the small scattering‐angle approximation. Elastic scattering differential cross sections are calculated using phase‐shift analysis and the finite difference method for solid atoms with the Hartree–Fock–Wigner–Seitz potential in the Dirac equation. Results of Monte Carlo simulations on the determination of IMFPs from experimental elastic reflection coefficients are presented for Ag and Cu. Our results show that the relative difference between the IMFPs obtained with and without surface excitation may reach 40% for low‐energy electrons (∼250 eV). The experimental results, with corrections for surface excitations, are in better agreement with the theoretical data. © 1995 American Vacuum Society
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79.20.Kz Other electron-impact emission phenomena

X‐ray photoelectron spectroscopy study of submonolayer native oxides on HF‐treated Si surfaces

Fumiko Yano, Akiko Hiraoka, Toshihiko Itoga, Hisao Kojima, Keiichi Kanehori, and Yasuhiro Mitsui

J. Vac. Sci. Technol. A 13, 2671 (1995); http://dx.doi.org/10.1116/1.579466 (5 pages) | Cited 7 times

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This article investigates, by a novel spectral analysis technique, the possibility of applying conventional x‐ray photoelectron spectroscopy to characterize the initial oxidation process. Quantitative analysis of submonolayer native oxides is made possible by spectral decomposition of Si 2p into Si4+, Six+, and Si0+ based on the O 1s binding energy, and by calculation of the SiO2 and SiOx thicknesses using the decomposition results. Here, the sensitivity for oxide‐thickness change is about 1/10 monolayer. Using this technique, the initial oxidation processes of HF‐treated Si(111) and Si(100) are precisely characterized. The influence of the dissolved‐oxygen concentration in the HF solution is also investigated. © 1995 American Vacuum Society
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81.65.-b Surface treatments
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

An x‐ray photoelectron spectroscopy study of the interaction and chemical passivation of chemically etched (100) oriented Hg1−xCdxTe (x=0.226) utilizing chromium and aluminum

J. P. Williams, S. P. Wilks, R. H. Williams, and H. A. Tarry

J. Vac. Sci. Technol. A 13, 2676 (1995); http://dx.doi.org/10.1116/1.579467 (8 pages)

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The growth and chemical interaction of both aluminum and chromium interfaces with chemically etched (100) oriented mercury cadmium telluride (MCT) has been studied using x‐ray photoelectron spectroscopy (XPS). It is shown that the MCT is chemically passivated with the deposition of Cr, and that there is no outdiffusion of Te and no loss of mercury, as has often been observed. It was found that Cr followed a laminar growth mode with an escape depth of 21 Å. In contrast, the deposition of aluminum onto the etched (100) MCT surface induced an increase in the Te and Cd XPS intensities of approximately 100% and 34%, respectively, of the zero coverage value. This coincided with a rapid loss of mercury from the interfacial region. At high coverage a reacted Te component was observed. A structural model is introduced and is used to account for the trends observed in the core level intensities of the postetched surface. Mathematical expressions derived from this model are utilized to fit the core level intensities as a function of overlayer thickness. We report the success of the model, with excellent fits obtained for both the Cr–MCT and Al–MCT systems and, as a result of this study, a method of chemically passivating the system. © 1995 American Vacuum Society
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68.35.Fx Diffusion; interface formation
81.65.-b Surface treatments
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Interface exciton luminescence: An indication of interface inhomogeneities in single GaAs/GaAlAs heterostructures

V. N. Bessolov, V. V. Evstropov, and M. V. Lebedev

J. Vac. Sci. Technol. A 13, 2684 (1995); http://dx.doi.org/10.1116/1.579468 (5 pages)

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A specific luminescence band originating from a heterointerface (H band) has been observed in the photoluminescence spectrum (at 1.7 K) of a single GaAs/GaAlAs heterostructure. Threshold effect of epitaxial temperature on interface luminescence has been found. A model has been proposed which attributes interface luminescence to annihilation of the interface heterodimensional exciton which is composed of a two‐dimensional (2D) electron (2D hole) in the notch at the interface and a three‐dimensional (3D) hole (3D electron) in the GaAs bulk region near the interface. The exciton binding energy decreases when the interface ruggedness increases. In the case of large inhomogeneities (ruggedness of chemically abrupt interface) such an exciton cannot form and the corresponding H band is not observed in the spectrum. Thus, the luminescence of the interface heterodimensional exciton can serve as an indication of the interface ruggedness. © 1995 American Vacuum Society
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71.35.-y Excitons and related phenomena
78.66.Fd III-V semiconductors

Application of high‐resolution electron energy loss spectroscopy to the adsorption and the photoreaction of CH2I2 and CD3OD on a MoOx thin film

Hong He, Junji Nakamura, Naoki Takehiro, and Ken‐ichi Tanaka

J. Vac. Sci. Technol. A 13, 2689 (1995); http://dx.doi.org/10.1116/1.579469 (9 pages)

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The adsorption and the photoreaction of CH2I2 and CD3OD on sublimated molybdenum oxide surfaces have been studied using high‐resolution electron energy loss spectroscopy combined with thermal and photoinduced desorption spectroscopy. The energy loss peaks for ν(C–H), ν(C–D), ν(C–O) and δ (CH2) are detected for CH2I2 and CD3OD adsorbed on the MoOx thin film, where the energy losses of the ν(C–H) stretch and ν(C–D) stretch are mainly caused by impact scattering. CD3OH adsorbed on the MoOx thin film surface photodesorbs as CD3OD and CD2O due to illumination by ultraviolet (UV) light. CH2I2 adsorbs on the MoOx thin film without dissociation at room temperature, but undergoes photodissociation upon illumination by UV light via the production of intermediate =CH2(a) species. © 1995 American Vacuum Society
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82.50.Bc Processes caused by infrared radiation
82.50.Hp Processes caused by visible and UV light
68.43.-h Chemisorption/physisorption: adsorbates on surfaces
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

In situ infrared spectroscopic study on the role of surface hydrides and fluorides in the silicon chemical vapor deposition process

Chan‐Hwa Chung, Sang Heup Moon, and Shi‐Woo Rhee

J. Vac. Sci. Technol. A 13, 2698 (1995); http://dx.doi.org/10.1116/1.579470 (5 pages)

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The role of surface hydrides and fluorides in the Si chemical vapor deposition (CVD) process was studied by in situ Fourier transform infrared spectroscopy using a porous silicon film as the substrate. Hydrides protect the silicon surface from oxidation until they are desorbed at 350–400 °C. However, the hydrides are replaced almost completely by surface fluorides when SiH2F2 is used as a reactant in the CVD process at temperatures above 400 °C. The surface is then etched due to a reaction between the fluorides and the surface silicon. When the process temperature is lowered to 250 °C, the surface is covered by both hydrides and fluorides, and a silicon film is deposited. © 1995 American Vacuum Society
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Characterization of molecular beam epitaxy grown CdF2 layers by x‐ray diffraction and CaF2:Sm photoluminescence probe

N. S. Sokolov, N. N. Faleev, S. V. Gastev, N. L. Yakovlev, A. Izumi, and K. Tsutsui

J. Vac. Sci. Technol. A 13, 2703 (1995); http://dx.doi.org/10.1116/1.579471 (6 pages) | Cited 6 times

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For studies of crystal quality and strain relaxation in heterostructures with epitaxial CdF2 and CaF2 layers on Si(111), differential double crystal x‐ray diffractometry and impurity photoluminescence techniques were used. The crystalline quality of molecular beam epitaxy grown CdF2 layers can be high and comparable with that of III–V compound pseudomorphic heterostructures. The best results were obtained for CdF2 layers grown on CaF2 buffer layers which were coherent with the Si substrate. © 1995 American Vacuum Society
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52.65.-y Plasma simulation
85.40.Bh Computer-aided design of microcircuits; layout and modeling

Thermal desorption spectroscopy study of HF/DF‐treated Si(100) surfaces

Keizo Kinoshita and Iwao Nishiyama

J. Vac. Sci. Technol. A 13, 2709 (1995); http://dx.doi.org/10.1116/1.579472 (6 pages) | Cited 1 time

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Hydrogen (H)‐ and deuterium (D)‐terminated Si (100) surfaces are investigated by thermal desorption spectroscopy (TDS). The H/D exchange reaction, using 1.6% DF, creates partially D‐terminated Si surfaces from passively H‐terminated Si by using 1.6% or 49% HF. The H/D exchange reaction rate, determined from TDS intensity changes, follows natural‐logarithmic equations. The half‐exchange time is 12.8 min. The 49% HF pretreated samples show rapid surface roughness changes in the initial stage of the 1.6% DF treatment; these changes are detected by rapid TDS H2 intensity decreases. SiFx and F2 peaks are detected by TDS. F/D exchange occurs on the 49% HF pretreated samples along with H/D exchange. The activation energy for deuterium termination is 8.7 kcal/mol. © 1995 American Vacuum Society
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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
81.65.-b Surface treatments

Modification of surface condition and irradiation effects of synchrotron radiation on photoexcited etching of SiC

Shingo Terakado, Masayoshi Ogura, Shigeo Suzuki, Masao Nakao, and Kenichiro Tanaka

J. Vac. Sci. Technol. A 13, 2715 (1995); http://dx.doi.org/10.1116/1.579473 (6 pages)

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Photoexcited etching of SiC film by synchrotron radiation excitation was investigated from both measurements of total electron yield (TEY) spectra and dependence of the etch rate on irradiated photon energy. We found from TEY spectra that the content of Si near the surface was decreased and that of C was increased upon exposing the SiC surface to reactive species. In the etching experiment with changing irradiated photon energy, we also found that the etch rate showed a photon energy dependence similar to that of photoabsorption of SiC. We concluded that photoexcited etching of SiC was realized based on the progress of the etching of the irradiated region being closely related to the photoabsorption of constituent elements of SiC, and by the slight etching of the nonirradiated region covered by the C‐rich fluorinated layer. © 1995 American Vacuum Society
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81.65.-b Surface treatments
82.50.Kx Processes caused by X-rays or γ-rays
85.40.Bh Computer-aided design of microcircuits; layout and modeling

Study of electron‐beam effects on trimethylsilane covered Si(100)

M. V. Ascherl, J. H. Campbell, J. Lozano, and J. H. Craig

J. Vac. Sci. Technol. A 13, 2721 (1995); http://dx.doi.org/10.1116/1.579474 (5 pages) | Cited 3 times

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Electron‐stimulated desorption (ESD) and temperature programmed desorption (TPD) studies were conducted on trimethylsilane dosed Si(100) surfaces. Experiments investigating the effects of electron‐beam irradiation on TPD spectra and ESD kinetic energy distributions of hydrogen from trimethylsilane covered Si(100) surfaces are reported. Electron‐beam irradiation strongly influences subsequent TPD spectra. Electron‐beam induced dissociation of physisorbed particles on the surface is demonstrated. It is concluded that electron irradiation of trimethylsilane covered Si(100) selectively enhances or induces specific hydrogen adsorbed states when physisorbed species are present on the surface. © 1995 American Vacuum Society
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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
82.50.Kx Processes caused by X-rays or γ-rays

Thermogravimetric analysis of selected condensed materials on a quartz crystal microbalance

Terry E. Phillips, C. Brent Bargeron, and Richard C. Benson

J. Vac. Sci. Technol. A 13, 2726 (1995); http://dx.doi.org/10.1116/1.579475 (6 pages)

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Employing a quartz crystal microbalance and a quadrupole mass spectrometer in a vacuum chamber, thermogravimetric analyses (TGA) and mass spectrometer analyses have been performed at low temperature (90–190 K) on depositions of ammonia, acetone, methanol, toluene, isopropyl alcohol, water, para‐xylene, and selected combinations of these materials. Deposition of a single species yielded a TGA curve characteristic of a pure substance. Homogeneous binary mixtures, like methanol and water, exhibited a desorption curve which contained structure in addition to that observed for the pure materials. Sequential layering of one material on top of another also altered the TGA response, suggesting substantial interlayer interactions, and the TGA curve shape was found to be a function of the top‐layer thickness for the water‐on‐methanol system. Backfilling the chamber with nitrogen or argon at a pressure of 1 Torr increased the apparent desorption temperature of water by about 20 K. © 1995 American Vacuum Society
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis

Microstructure and characterization of electron‐trapping stimulable phosphor SrS:(Eu,Sm) thin film on glass

T. J. Hsieh, R. Revay, D. Brower, P. H. Chi, D. S. Simons, D. E. Newbury, and S. W. Robey

J. Vac. Sci. Technol. A 13, 2732 (1995); http://dx.doi.org/10.1116/1.579696 (7 pages) | Cited 4 times

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Strontium sulfide doped with europium and samarium is an infrared stimulable phosphor that is being investigated as the active thin film layer of a photonic data storage disk. Lithium and fluorine can be added to the SrS:(Eu,Sm) to fully activate the photonic properties of the material, and care must be taken to ensure sufficient crystallite size, minimize structural defects within crystal grains, and maintain a uniform chemistry throughout the film thickness. In this article we present the initial stages of a study of the relationship of these properties to film performance. A number of techniques are employed including x‐ray diffraction, electron probe x‐ray microanalysis, transmission electron microscopy, and secondary ion mass spectrometry. Initial findings provide information on the effect of structural defects on film performance, and the importance of the mismatch in thermal coefficient of expansion between film and substrate. © 1995 American Vacuum Society  
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42.79.Vb Optical storage systems, optical disks
68.55.-a Thin film structure and morphology
78.66.Hf II-VI semiconductors

New method to predict corrosion characteristics of Zn‐metallized thin films for film capacitors

J. G. Na

J. Vac. Sci. Technol. A 13, 2739 (1995); http://dx.doi.org/10.1116/1.579697 (3 pages)

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The relationship between the microstructural parameters, e.g., grain size and preferred orientation, and the corrosion characteristics of Zn‐metallized thin films was investigated. The Zn‐metallized thin films with various grain sizes and preferred orientations were prepared by changing evaporation conditions, e.g., the temperature of the Zn source and the substrate temperature. By increasing the temperature of the Zn source and decreasing the substrate temperature, the grain size and the values of full width half‐maximum (FWHM) of the (002) x‐ray diffraction peaks of Zn decreased. From measurements of resistivity change in the thin films a function of time at the temperature of 40 °C and the relative humidity of 80%, it was found that the relative change in the value of Ω/sq decreased by decreasing the grain size and the FWHM values of the (002) peaks of Zn. It suggests that the FWHM measurement of the (002) peak of Zn is a simple method by which to predict the corrosion characteristics of Zn‐metallized thin films. © 1995 American Vacuum Society
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68.60.-p Physical properties of thin films, nonelectronic
73.61.At Metal and metallic alloys
81.05.Bx Metals, semimetals, and alloys

Origins of atmospheric contamination in amorphous silicon prepared by very high frequency (70 MHz) glow discharge

U. Kroll, J. Meier, H. Keppner, A. Shah, S. D. Littlewood, I. E. Kelly, and P. Giannoulès

J. Vac. Sci. Technol. A 13, 2742 (1995); http://dx.doi.org/10.1116/1.579698 (5 pages) | Cited 6 times

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The authors have studied the effect of plasma power, reactor outgassing rates, and of silane purity on the oxygen, carbon, and nitrogen contents of amorphous silicon material prepared by the very high frequency (70 MHz) glow discharge technique. The silane purity could be optionally enhanced by the application of a getter‐based silane gas purifier. It was found that oxygen incorporation was enhanced at lower deposition rates, whereas the nitrogen and carbon film contamination were unaffected. The deposition rate dependence of the incorporation is in excellent agreement with a proposed model. Apart from the effects of plasma power on the incorporation probability, the reactor outgassing rate and the purity of the silane gas itself were identified as the main contamination sources for the atmospheric contaminants in the deposited films. At the low outgassing rate, at least around one‐half of the oxygen detected in the a‐Si:H material originates from the silane gas. Due to the reduced outgassing rate and an enhanced purity of the silane gas used, the authors have deposited a‐Si:H‐material with the lowest concentrations of atmospheric contaminants reported to date. Furthermore, the present results exclude a contamination of the a‐Si:H‐material by a post‐ oxidation after air exposure. © 1995 American Vacuum Society
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52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

An actinometric study of C2H2 plasma polymerization and film properties

Rogério Pinto Mota, Tadashi Shiosawa, Steven Frederick Durrant, and Mário Antônio Bica de Moraes

J. Vac. Sci. Technol. A 13, 2747 (1995); http://dx.doi.org/10.1116/1.579699 (6 pages) | Cited 2 times

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Thin polymer films were grown in radio frequency discharges containing C2H2. Actinometry revealed the trend in the plasma concentration of the CH species as a function of the operating pressure. The C–H bond density in the films, revealed by infrared analysis, was found to increase with the pressure of C2H2 in a similar way to that of the concentration of the CH species in the discharge. From transmission ultraviolet‐visible spectroscopy data, optical parameters of the polymers, namely, the refractive index and the optical gap, were calculated. For the range of pressure studied, the refractive index decreased from 1.73 to 1.63 and the optical gap increased from 2.4 to 3.3 eV. Finally, measurements of the residual stress of the polymer films were carried out by the bending beam method, using a He–Ne laser, yielding values from 0.05 to 0.3 GPa. © 1995 American Vacuum Society
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
68.60.Bs Mechanical and acoustical properties
78.66.Qn Polymers; organic compounds
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

In situ measurements of the recombination at the crystalline silicon/amorphous silicon heterointerface by time resolved microwave conductivity measurements during low temperature annealing and silane plasma exposure

H. C. Neitzert and M. Kunst

J. Vac. Sci. Technol. A 13, 2753 (1995); http://dx.doi.org/10.1116/1.579700 (5 pages)

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The decay of optically generated excess charge carriers at the heterointerface between crystalline silicon and amorphous silicon has been monitored in situ during plasma deposition of the amorphous layer. A dramatic increase in the interface recombination rate is seen instantly when the silane plasma is ignited. In a later stage of amorphous layer deposition, the recombination rate decreases. This interface passivation depends strongly on the substrate temperature and is more efficient at higher temperature and in the presence of silane plasma. The effect is not due to a change in the band bending at the heterointerface. © 1995 American Vacuum Society
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Change in refractive index and in chemical state of electron beam irradiated fluorinated polyimide films

Yasuko Yamada Maruo, Shigekuni Sasaki, and Toshiaki Tamamura

J. Vac. Sci. Technol. A 13, 2758 (1995); http://dx.doi.org/10.1116/1.579701 (6 pages) | Cited 5 times

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The refractive index of fluorinated polyimide is increased by electron beam irradiation. The degree of refractive index change can be controlled by adjusting the dose of the electron beam. The depth of the refractive index change depends on the energy of the beam. X‐ray photoelectron spectroscopy (XPS), secondary ion mass spectroscopy (SIMS), and surface profile measurement of electron beam irradiated fluorinated polyimide film were carried out to investigate the causes of the refractive index increase. The surface profile measurement indicated that the polyimide volume was decreased by an electron beam irradiation. The XPS and SIMS showed that electron beam irradiation decreases the fluorine content. The main cause of the refractive index increase is thought to be this decrease in fluorine content and volume. © 1995 American Vacuum Society
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42.70.Jk Polymers and organics
61.80.Fe Electron and positron radiation effects
78.66.Qn Polymers; organic compounds

Structural investigation of monolayer Sb on Si(100)‐2×1 utilizing a Monte Carlo simulation of channeling and channeled ion energy loss

M. A. Boshart, A. A. Bailes, A. Dygo, and L. E. Seiberling

J. Vac. Sci. Technol. A 13, 2764 (1995); http://dx.doi.org/10.1116/1.579702 (8 pages) | Cited 3 times

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The preferred bonding site of Sb on Si(100) is investigated using transmission ion channeling. A Monte Carlo simulation that includes a model for channeled ion energy loss has been used to calculate scattering yields and energy distributions for trial adatom sites. A method of data collection and analysis was developed to use the calculated scattering yields and energy distributions for quantitative site determination. The Sb site thus found agrees well with previous experiments on this system, namely, the Sb is in a modified bridge site with a bond length of 2.80±0.10 Å and a distance above the bulk‐extrapolated silicon surface of 1.63±0.10 Å. However, the vibrational amplitude necessary for the simulated energy distributions to match experiment is anisotropic, apparently in contradiction with other results. A possible resolution is proposed. © 1995 American Vacuum Society
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68.37.Vj Field emission and field-ion microscopy
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Chemical reactions of triethylantimony on GaAs(100)

John M. Heitzinger and J. G. Ekerdt

J. Vac. Sci. Technol. A 13, 2772 (1995); http://dx.doi.org/10.1116/1.579703 (9 pages)

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The surface chemistry of triethylantimony was studied on GaAs(100) using thermal desorption spectroscopy, static secondary ion mass spectroscopy, and x‐ray photoelectron spectroscopy. Triethylantimony is reversibly adsorbed following exposures at 160 K. The saturation coverage at 160 K is approximately 0.3 monolayers. Following triethylantimony exposure at 330 K, ethylene, the major hydrocarbon reaction product, desorbs from the GaAs(100) surface during thermal desorption spectroscopy experiments with a peak temperature of 569 K. This indicates a β‐hydride elimination reaction is responsible for the elimination of ethyl groups from the surface. Additionally, a small amount of ethyl radicals desorb from the surface. Our results indicate that ethyl groups migrate to Ga sites and then undergo a β‐hydride elimination reaction at these sites. For saturation coverage (0.3 monolayers), 90% of the triethylantimony is irreversibly adsorbed. Exposures at 675 K led to adsorbed Sb atoms as well as GaSb formation. The reactive sticking coefficient of triethylantimony is low, 4×10−4, and decreases as the surface becomes Sb rich. Eventually, adsorption of triethylantimony ceases at 675 K, indicating self‐limiting adsorption. © 1995 American Vacuum Society
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.43.-h Chemisorption/physisorption: adsorbates on surfaces

Methane adsorption and hydrogen isothermal desorption kinetics on a C(001)–(1×1) surface

Toshihiko Nishimori, Hitoshi Sakamoto, Yuji Takakuwa, and Shozo Kono

J. Vac. Sci. Technol. A 13, 2781 (1995); http://dx.doi.org/10.1116/1.579704 (6 pages) | Cited 5 times

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Methane (CH4) adsorption and isothermal hydrogen (H2) desorption kinetics on a C(001)–(1×1) surface have been investigated by observing the surface hydrogen coverage θH which is estimated from the electron‐stimulated desorption yield of H+ ions. The time evolution of θH under CH4 exposure, in pressure and temperature ranges of 1×10−8–5×10−7 Torr and 600–800 °C, reveals that the CH4 adsorption is a first‐order reaction. The isothermal H2 desorption is conducted in a temperature range of 1095–1270 °C. The time evolution of θH shows that the isothermal H2 desorption is also a first‐order reaction. From Arrhenius plots of the reaction coefficients, the activation energies of CH4 adsorption and H2 desorption are evaluated to be 7.3±1.7 and 21±4.9 kcal/mol, respectively. Atomistic kinetics model for CH4 adsorption and H2 desorption are discussed, especially in connection with a recent finding of gas source molecular beam epitaxy of diamond (001) with pure CH4 without any hydrogen or oxygen radicals. © 1995 American Vacuum Society
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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy

Laterally resolved measurements of cesium iodide quantum yield

Tiziana dell’Orto, J. Almeida, C. Coluzza, E. Conforto, Gelsomina De Stasio, G. Margaritondo, G. Paic, A. Braem, F. Piuz, and B. P. Tonner

J. Vac. Sci. Technol. A 13, 2787 (1995); http://dx.doi.org/10.1116/1.579705 (4 pages)

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Spatially resolved x‐ray secondary electron photoemission spectra revealed lateral changes in quantum efficiency and chemical composition of polycrystalline cesium iodide photodetectors. Such changes depend on the substrate (stainless steel or aluminum). These results emphasize the limitations of conventional, spatially integrated quantum efficiency measurements, and shed new light on the chemical properties of inhomogeneous polycrystalline cesium iodide. © 1995 American Vacuum Society
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79.60.Dp Adsorbed layers and thin films
85.60.Gz Photodetectors (including infrared and CCD detectors)

Modeling the pump‐down of a reversibly adsorbed phase. II. Multilayer coverage

P. A. Redhead

J. Vac. Sci. Technol. A 13, 2791 (1995); http://dx.doi.org/10.1116/1.579706 (6 pages) | Cited 3 times

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In Part I [J. Vac. Sci. Technol. A 13, 467 (1995)] of this article pressure versus time was calculated for the evacuation of a vacuum system with a reversibly adsorbed phase at coverages less than one monolayer; in Part II this analysis is extended to the multilayer region, i.e., from the saturated vapor pressure (ps) to the pressure corresponding to one monolayer (pm) the gas flow is viscous in this range. In this pressure range the ratio of adsorbed to gas phase molecules is small (less than a few percent). As a practical example, the adsorbed phase is taken to be water at about 300 K. A recently proposed empirical adsorption isotherm is used that is a good fit to experiment from ps to pm, unlike existing isotherms that only cover parts of this range. Using this isotherm, the pressure and coverage as a function of time in the pressure range from ps to pm are calculated. It is shown that, for the reference system chosen (vol 17 l, surface area 4.5×103 cm2), as the system is pumped down, the pressure remains constant for a few seconds at a pressure slightly less than ps and then falls to pm in essentially the same way as in the absence of an adsorbed phase; this occurs because the number of molecules in the adsorbed phase is much less than in the gas phase. For systems with the pumping parameter S/A<5×10−3 (S=pumping speed, l s−1, A=area of adsorbing surface, cm2) the decrease in temperature caused by the desorption of multilayers of water is too small to have any significant effect on the desorption rate; for systems with higher values of S/A the temperature drop may be significant. © 1995 American Vacuum Society
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07.30.Bx Degasification, residual gas
47.45.-n Rarefied gas dynamics
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics

Phosphorus impurities in MgxZn1−xTe alloys

F. El Akkad, M. Abdel Naby, and M. Ali Omar

J. Vac. Sci. Technol. A 13, 2797 (1995); http://dx.doi.org/10.1116/1.579707 (6 pages) | Cited 1 time

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P‐doped MgxZn1−xTe alloys (0≤x≤0.28) are characterized using room‐temperature electrical, optical, and photoelectric measurements. The electrical properties (hole concentration and mobility) indicate an increasing compensation with the increase of Mg content. The donor impurities are attributed to P. The optical absorption spectrum exhibits a peak situated at 1.06 eV, independent of composition. Supportive evidence is obtained for the assignment of this peak to electronic transitions in the shallow P acceptor level originating from the spin‐orbit band. The perturbations in the local potential lead to a broadening of the absorption peak and to the appearance of density‐of‐states tails at the edges of the principal bands. The spectral response of indium surface barriers on undoped and P‐doped crystals is investigated. It is found that P doping leads to a lowering of the barrier height and to a shift in the high‐energy edge of the spectral response toward lower energies. The latter is attributed to the presence of a thin insulating interfacial layer and a high density of interface states in the P‐doped contacts. It is suggested that P has a role in determining the characteristics of the interface. © 1995 American Vacuum Society
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61.72.uj III-V and II-VI semiconductors
71.55.Gs II-VI semiconductors
72.80.Ey III-V and II-VI semiconductors
78.30.Fs III-V and II-VI semiconductors

Effect of the composition and anion vacancies in the band gap and band levels of Cu–In–Se–Te thin films

R. Díaz and M. León

J. Vac. Sci. Technol. A 13, 2803 (1995); http://dx.doi.org/10.1116/1.579708 (5 pages) | Cited 1 time

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Cu–In–Se–Te thin films grown by ‘‘flash’’ evaporation present stoichiometric deviations with anion vacancies and Cu excess. These changes in composition produce a different band structure. The effect of composition variations and anion vacancies in the energy gap is analyzed and a schematic band level is drawn. Samples with lower numbers of anions present conduction band minima (CBM) and valence band maxima (VBM) lower than samples with higher numbers of anions. The variation in VBM is greater than in CBM. © 1995 American Vacuum Society
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68.55.Nq Composition and phase identification
73.21.-b Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems

Effects of nitrogen pressure and ion flux on the properties of direct current reactive magnetron sputtered Zr–N films

Shozo Inoue, Kikuo Tominaga, Ronald P. Howson, and Kazuya Kusaka

J. Vac. Sci. Technol. A 13, 2808 (1995); http://dx.doi.org/10.1116/1.579709 (6 pages) | Cited 6 times

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Zr–N films have been deposited by direct current reactive magnetron sputtering using a plasma emission monitoring (PEM) control system, where a signal proportional to the light emitted by the sputtered Zr in the plasma created by the electrical discharge was used to control the admission of the reactive nitrogen into the system. The Zr line set point for PEM control, ϕ, was used as a parameter; as the partial pressure of nitrogen rises the Zr line emission falls due to target poisoning. The influence of the nitrogen partial pressure on the Zr–N film structure, reflectivity, resistivity, and internal stress was investigated. The effect of ion flux during film deposition on the film properties was also investigated. The Zr–N films deposited at the Zr line set point ϕ=60%–70% revealed the minimum resistivity and goldlike reflectivity spectra. These films showed a ZrN single phase. The internal stress of the films showed a maximum at ϕ=60%–70%, which corresponds to the condition for depositing minimum resistivity films. The external magnetic field scarcely affected the optical and the electrical properties of the deposited Zr–N films. The internal stress of the films deposited at the lower ϕ (higher nitrogen partial pressure) was only dependent on the ion flux. © 1995 American Vacuum Society
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52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
68.55.-a Thin film structure and morphology
73.61.Ng Insulators
81.15.Cd Deposition by sputtering

Effect of N+2 ion bombardment on the compositional change and residual stress of AlN film synthesized by ion beam assisted deposition

Ig‐Hyeon Kim and Seon‐Hyo Kim

J. Vac. Sci. Technol. A 13, 2814 (1995); http://dx.doi.org/10.1116/1.579710 (5 pages) | Cited 5 times

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The compositional change and residual stress of aluminum nitride film synthesized by ion‐assisted evaporation and sputtering are discussed in terms of ion bombardment. In the growth of AlN film, N+2 ion bombardment could increase the N incorporation probability and reduce oxygen impurities. The stoichiometric nitride was obtained at an arrival ratio of N/Al higher than 1.5. With increasing ion flux and energy the residual stress shows a tendency to shift from tensile to compressive stress. Except for the low region of ion flux and energy, the compressive stress shows a linear proportionality to the momentum parameter of incident ions defined as the product of ion flux and (ion energy)1/2 in the ion beam assisted deposition process. The temperature dependence of residual stress is also discussed. © 1995 American Vacuum Society
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79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
81.15.Jj Ion and electron beam-assisted deposition; ion plating

X‐ray photoelectron spectroscopy study of the difference between reactively evaporated and direct sputter‐deposited TiN films and their oxidation properties

P. Prieto and R. E. Kirby

J. Vac. Sci. Technol. A 13, 2819 (1995); http://dx.doi.org/10.1116/1.579711 (8 pages) | Cited 14 times

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X‐ray photoelectron spectroscopy (XPS) is used to study carefully prepared oxide‐free titanium nitride (TiN) films of nearly identical stoichiometry, grown by direct sputtering and reactive evaporation. The line shapes and peak positions of the Ti 2p and N 1s transitions are dependent upon the deposition method. The XPS results showed that oxynitrides are present following exposure of either type of film to dry oxygen; however, reactively evaporated films have a considerably higher oxidation rate. Differences in valence band and electron energy loss spectroscopy (EELS) spectra are correlated with the changes observed in the core levels. The EELS spectra detected the presence of a low energy loss, which is correlated with the TiN electron density of states closest to the Fermi level. The secondary electron emission yields for reactively evaporated TiN were also measured before and after dry oxygen and air exposure, and after heating. The maximum yields are about 10% lower for reactively evaporated films than for similarly treated previously measured sputter‐deposited layers. © 1995 American Vacuum Society
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79.60.Dp Adsorbed layers and thin films
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.65.-b Surface treatments

Ion beam assisted deposition of Al films on Si

A. Terrasi, S. Ravesi, C. Marcellino, C. Spinella, and S. Pannitteri

J. Vac. Sci. Technol. A 13, 2827 (1995); http://dx.doi.org/10.1116/1.579712 (5 pages) | Cited 1 time

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Ion beam assisted deposition (IBAD) was used to grow thin Al films (∼100 nm thick) onto Si substrates at room temperature. Al was deposited by electron gun evaporation, while an Ar+ ion beam bombarded the film during the growth. Ion beam energies of 300, 500, and 650 eV were used, with current densities ranging between 4 and 20 μA/cm2. Polycrystalline Al films have been obtained, whose structural properties were strictly related to the IBAD parameters (ion current and energy). Samples were analyzed by transmission electron microscopy and Rutherford backscattering spectrometry, pointing out the following effects: (1) IBAD produces smaller polycrystalline Al grains with respect to a film evaporated in standard high vacuum conditions; (2) the Al grain size decreases by increasing the ion current or decreasing the ion energy; (3) sputtering yields during IBAD are higher with respect to a postdeposition bombardment process, and show an inverse trend with the ion beam energy. Results have been explained in terms of modification of kinetics of growth induced by IBAD. A simple model is also proposed to take into account the unexpected result about the sputtering yield. Finally, the IBAD capability to modify the microstructure of the Al films was used to improve the coverage of artificially stepped substrates. © 1995 American Vacuum Society
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68.55.-a Thin film structure and morphology
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Origin of intrinsic stress in Y2O3 films deposited by reactive sputtering

H. M. Choi and S. K. Choi

J. Vac. Sci. Technol. A 13, 2832 (1995); http://dx.doi.org/10.1116/1.579713 (4 pages) | Cited 6 times

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Y2O3 thin films were deposited by reactive sputtering of an Y target in an Ar and O2 gas mixture. Intrinsic stresses and the Ar content in the films were measured by the sine square psi method of x‐ray diffraction and wavelength dispersive spectrometer, respectively. At low working pressures the films had high compressive stresses. As working pressure increased, compressive stress was relaxed. Ar content was high in the film that had high compressive stress. After annealing of the films at 700 °C, the compressive stress was largely relaxed but the Ar content remained unchanged. These results clearly showed that compressive stress in Y2O3 films was not caused by Ar entrapment as an impurity but by Ar bombardment. Intrinsic stress was almost independent of the O2/Ar flow ratio, showing that O bombardment was equal to Ar bombardment in affecting the intrinsic stress in Y2O3 films. The independence of intrinsic stress with the O2/Ar flow ratio was explained by the concept of M1/2i{[Micosθ±(M2t−M2isin2 θ)1/2]/(Mi+Mt)} instead of the Mt/Mi ratio, where Mt is the atomic mass of the target material, Mi is the atomic mass of the sputtering gas, and θ is the scattering angle. © 1995 American Vacuum Society
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68.60.Bs Mechanical and acoustical properties
81.15.Cd Deposition by sputtering

Low‐energy (5<Ei<100 eV), high‐brightness, ultrahigh vacuum ion source for primary ion beam deposition: Applications for Al and Ge

Y.‐W. Kim, I. Petrov, H. Ito, and J. E. Greene

J. Vac. Sci. Technol. A 13, 2836 (1995); http://dx.doi.org/10.1116/1.579714 (7 pages) | Cited 6 times

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The design, operation, and use of a double‐grid, electron‐impact, ultrahigh‐vacuum compatible, low‐energy ion source capable of operating with relatively low‐vapor‐pressure solid source materials such as Al and Ge are described. The source can run at cell temperatures up to 1450 °C and deliver ion current densities Ji≳30 mA cm−2 (corresponding to 1.9×1017 cm−2 s−1) at source‐to‐substrate separations d of 2 cm, and Ji≳100 μA cm−2 (6.3×1014 cm−2 s−1) at d=40 cm with beam energies which can be varied from 5 to 100 eV. The uniformity in the ion current density from a 2.6‐cm‐diam source over 6‐cm‐diam substrates is better than 97%. A postextraction magnetic filter was used to separate the ion and neutral components and provide a pure ion beam. Initial nucleation and growth experiments on amorphous carbon substrates at 30 °C using thermal and accelerated (EAl+=35 and 75 eV) Al+ beams show that the average island size in layers with thicknesses between 2 and 6 nm increases by factors ranging from 3 to 14 with increasing ion energy. Layers deposited with thermal Al have an island size distribution which is near‐Gaussian while Al islands formed from ion beams exhibit a bimodal size distribution. © 1995 American Vacuum Society
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29.25.Ni Ion sources: positive and negative
81.15.Jj Ion and electron beam-assisted deposition; ion plating

Preparation of cubic boron nitride films by radio frequency bias sputtering

Osamu Tsuda, Yukiko Yamada, Tsuyoshi Fujii, and Toyonobu Yoshida

J. Vac. Sci. Technol. A 13, 2843 (1995); http://dx.doi.org/10.1116/1.579715 (5 pages) | Cited 15 times

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Cubic boron nitride films were successfully prepared on Si(100) substrates by radio frequency (rf) bias sputtering of a hexagonal boron nitride target in pure Ar discharge with the aid of a magnetic field and with the phase regulation of the rf voltages applied to the target and substrate electrodes. Above the threshold of the negative substrate bias voltage (VS), the infrared (IR) absorbance corresponding to the cBN TO mode showed a linear increase proportional to deposition time, while that of the sp2 phase kept a nearly constant value. The resulting dependency indicated that the cBN films consisted of a double‐layered structure caused by an initial deposition of the sp2 phase and the subsequent growth of a cBN single phase, and did not consist of a two‐phase mixed layer. The layered structure was also confirmed by observing the depth dependence of the IR spectra. The growth rate of the cubic phase and the thickness of the initial sp2 bonded layer were estimated to be approximately 1 nm/s and 40 nm, respectively, for cases where VS ranged from 250 to 300 V at p=16 m Torr. This rate was relatively high compared with those of other techniques used for cBN deposition. © 1995 American Vacuum Society
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52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
68.55.-a Thin film structure and morphology
81.15.Cd Deposition by sputtering

Mass and energy selected ion beam for deposition and ion induced surface modifications

O. M. Küttel, P. Groening, R. G. Agostino, and L. Schlapbach

J. Vac. Sci. Technol. A 13, 2848 (1995); http://dx.doi.org/10.1116/1.579610 (8 pages) | Cited 5 times

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A mass and energy selected ion beam source, differentially pumped for ultrahigh vacuum (UHV) applications, was constructed and successfully tested. Ions with a mass up to 2048 amu and with energies of 5–500 eV can be selected from a Penning discharge chamber by a quadrupole massfilter and an electrostatic lens system. The ion gun is operated in combination with a VG ESCALAB spectrometer for x‐ray photoelectron spectroscopy and diffraction working at a base pressure in the 10−11 mbar range. Two applications of low energy ion bombardment are discussed in this article: etching of PMMA with 5 eV Ar+ ions, and deposition of a‐C:H films on silicon. Ar+ ions at very low energies can react with a PMMA surface by a charge exchange reaction leading to a breakup of chemical bonds and to the preferential etching of oxygen. By depositing CHx ions (x=3,4) on a silicon surface under UHV conditions an oriented SiC layer is formed upon annealing at 800 °C. The ion beam was characterized with respect to mass and energy resolution and beam spreading for different ion energies. © 1995 American Vacuum Society
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07.77.Ka Charged-particle beam sources and detectors
41.75.Ak Positive-ion beams
81.15.Jj Ion and electron beam-assisted deposition; ion plating
81.65.-b Surface treatments

Effect of substrate bias on the properties of diamondlike carbon films deposited using unbalanced magnetron sputtering

Soon‐Cheon Seo, David C. Ingram, and Hugh H. Richardson

J. Vac. Sci. Technol. A 13, 2856 (1995); http://dx.doi.org/10.1116/1.579604 (7 pages) | Cited 11 times

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Diamondlike carbon (DLC) films were deposited using unbalanced planar circular magnetron sputtering of a graphite target with argon as the support gas. The properties of the DLC films were studied as functions of the applied negative substrate bias voltage, 50–200 V, and argon gas pressure, 2–6 mTorr. The hydrogen content was measured by elastic recoil spectroscopy and impurity content was measured by Rutherford backscattering spectroscopy; the physical thickness was measured by mechanical profilometry. For the first time films with densities as high at 3 g/cm3 have been made by this technique. The hydrogen content in the films is 12–16 at. % and 20–32 at. % for an argon gas pressure of 2 and 6 mTorr, respectively. As the bias voltage increases, the hydrogen content decreases. The transmission electron diffraction of the films indicated that they are amorphous. The bonding structure, optical property, and optical band gap were determined by Fourier transform infrared (FTIR) spectroscopy, and ultraviolet‐visible spectroscopy. FTIR spectra from DLC films deposited at 6 mTorr display the C–H stretching absorptions centered around 2900 cm−1 with a bonding configuration of sp3/sp2‐C:H at 2920, 2860, and 3012 cm−1, as well as the deformation peaks of sp3C–CH3 at 1450 and 1370 cm−1. The decreasing ratio of sp3CH2 to sp3CH1 in the C–H stretching region indicates a decrease in hydrogen content with bias voltage. © 1995 American Vacuum Society
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68.55.-a Thin film structure and morphology
78.66.Nk Insulators
81.15.Cd Deposition by sputtering

Chemical vapor deposition of aluminum from dimethylaluminumhydride (DMAH): Characteristics of DMAH vaporization and Al growth kinetics

Eiichi Kondoh and Tomohiro Ohta

J. Vac. Sci. Technol. A 13, 2863 (1995); http://dx.doi.org/10.1116/1.579605 (9 pages) | Cited 5 times

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The metallization process for the chemical vapor deposition of aluminum from dimethylaluminumhydride [(Al(CH3)2H, DMAH)] has received considerable attention. In this article, the authors discuss the vaporization of DMAH, Al deposition kinetics, selective growth, and film properties. Although DMAH has extremely high viscosity (about 4000 cP), it was found by metering the DMAH flow rate that DMAH can be vaporized while maintaining a high efficiency of 80%–100 % of the theoretical flow rate, even with the conventional bubbling method. The film growth rate followed the Arrhenius law at lower temperatures (<250–270 °C, depending on the partial pressure of DMAH). The maximum growth rate attained was about 1160 nm/min at 350 °C. In the surface‐reaction‐controlled region, Al was deposited selectively on metal substrates. The origin of selectivity is discussed from the viewpoint of surface chemical conditions. The Al deposition rate was independent of the deposition area, which is discussed in terms of the supply and consumption balance of Al. © 1995 American Vacuum Society
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
85.40.Bh Computer-aided design of microcircuits; layout and modeling

Deposition and properties of Mo–N films

Kwang‐Lung Lin and Yu‐Jin Ho

J. Vac. Sci. Technol. A 13, 2872 (1995); http://dx.doi.org/10.1116/1.579606 (5 pages) | Cited 3 times

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Mo–N films were deposited on glass or silicon wafers by reactive sputtering. The growth rate, composition, microstructure, and sheet resistance of the films were analyzed and determined to be controlled by deposition power as well as by N2 partial pressure. Grain refining, which increases the sheet resistivity of Mo–N films, was observed at higher N2 partial pressure as well as at lower deposition power input. τ‐Mo2N was achieved at suitable conditions. We propose that the films formed by the reaction of nitrogen and Mo atoms on the substrate surface. © 1995 American Vacuum Society
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68.55.-a Thin film structure and morphology
73.61.Ng Insulators
81.15.Cd Deposition by sputtering

Investigation of polycrystalline CdTe thin films deposited by physical vapor deposition, close‐spaced sublimation, and sputtering

H. R. Moutinho, F. S. Hasoon, F. Abulfotuh, and L. L. Kazmerski

J. Vac. Sci. Technol. A 13, 2877 (1995); http://dx.doi.org/10.1116/1.579607 (7 pages) | Cited 11 times

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CdTe thin films, deposited on different substrate structures by physical vapor deposition, sputtering, and close‐spaced sublimation, have been treated with CdCl2 at several temperatures. The morphology of the films has been studied by atomic force microscopy, and the observations were correlated to results obtained from x‐ray diffraction, cathodoluminescence, and minority‐carrier lifetime measurements. The samples treated at 400 °C resulted in the best device‐quality films, independent of deposition method and underlying substrate structure. For the first time, a nanograin structure was observed in CdTe sputtered samples. © 1995 American Vacuum Society
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68.60.Dv Thermal stability; thermal effects
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.65.-b Surface treatments
84.60.Jt Photoelectric conversion

Effects of atomic chlorine wall recombination: Comparison of a plasma chemistry model with experiment

E. Meeks, J. W. Shon, Y. Ra, and P. Jones

J. Vac. Sci. Technol. A 13, 2884 (1995); http://dx.doi.org/10.1116/1.579608 (6 pages) | Cited 23 times

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Results from a plasma chemistry model provide predictions of spatially and temporally averaged plasma properties. Application of the model to chlorine‐etch process conditions, typical of a high plasma‐density transformer coupled plasma reactor, provides plasma composition dependence on reactor operating parameter such as power and pressure. Model results also show the dependence of species concentrations on the atomic‐chlorine recombination rate at reactor walls. Comparison of model predictions to measured composition trends as determined by Langmuir probe, actinometry, and ion‐energy analysis reveals a critical wall‐recombination probability of about 0.1 for chlorine atoms on a chlorinated anodized‐aluminum surface. At or above this critical value, the model reproduces the experimentally observed trends, while employing a recombination probability below this value results in predictions that are inconsistent with the data. The model determines gas‐phase and surface‐species compositions in plasma‐etch reactors through the solution of species, mass, electron‐energy, and surface‐site conservation equations. The use of well mixed reactor approximations reduces the computational expense of detailed kinetics calculations and allows investigation into the dependence of plasma chemistry on uncertain kinetic parameters. The dominance of surface reaction rates in determining plasma properties is expected to be equally important in more complex two‐dimensional inductively coupled plasma models due to the highly diffuse nature of these low‐pressure reactors. © 1995 American Vacuum Society
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52.40.Hf Plasma-material interactions; boundary layer effects
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)

Power required to maintain an electron in a discharge: Its use as a reference parameter in magnetized high frequency plasmas

J. Margot, M. Moisan, and M. Fortin

J. Vac. Sci. Technol. A 13, 2890 (1995); http://dx.doi.org/10.1116/1.579611 (10 pages) | Cited 10 times

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Earlier works on discharges sustained by electromagnetic surface waves in absence of a magnetic field have revealed the central role played by the power balance per electron. This balance relation stated that, provided energy transport is negligible, the power θL lost by the electron on the average in collisions with heavy particles is exactly compensated under steady‐state conditions by the power θA taken by the electron on the average from the high frequency (hf) field, their common value being the parameter θ. Then, because θL is to a first approximation the same in all hf discharges under given discharge conditions and power density, a simple discharge model valid for all hf plasmas was used. The present article is an extension of this approach to hf magnetized plasmas, using surface‐wave plasma columns placed in an axially directed static magnetic field as a means of investigation. We observe that θ decreases monotonously when increasing the magnetic field intensity B0, showing no extremum at or close to the electron cyclotron resonance frequency match over the gas pressure range (5–100 mTorr) investigated. We show that θ is controlled either by classical ambipolar diffusion or anomalous diffusion, the actual diffusion regime depending on whether the novel parameter B0p (p is gas pressure) is small or large. Our measured θ values are further used to estimate the average electron density in helicon sources given the power density, showing fair agreement with the reported values. © 1995 American Vacuum Society
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52.55.Dy General theory and basic studies of plasma lifetime, particle and heat loss, energy balance, field structure, etc.
52.80.Pi High-frequency and RF discharges

Low temperature deposition of silicon nitride films by distributed electron cyclotron resonance plasma‐enhanced chemical vapor deposition

S. Sitbon, M. C. Hugon, B. Agius, F. Abel, J. L. Courant, and M. Puech

J. Vac. Sci. Technol. A 13, 2900 (1995); http://dx.doi.org/10.1116/1.579609 (8 pages) | Cited 21 times

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Silicon nitride thin films have been deposited via distributed electron cyclotron resonance plasma‐enhanced chemical vapor deposition, without intentional substrate heating, using SiH4 and N2 gas mixtures. The effects of N2/SiH4 gas flow (1.5–19) and microwave power (800–1500 W) on deposition rate, refractive index, composition, chemical bonds, and etch rate were studied by ellipsometry, MeV ion beam analysis techniques, and Fourier transform infrared spectroscopy. All parameters examined indicate that a highly diluted SiH4 gas phase and a microwave power of 1500 W help to prepare quasistoichiometric films with a high density (2.9 g/cm3) and a refractive index of 1.98. The effects of film density and film stoichiometry (N/Si) on refractive index are discussed through the Lorentz–Lorenz relation. The first electric results show that, under the optimized deposition parameters, a critical field of 2.3 MV/cm and an interface state density of 5×1010 eV−1 cm−2 can be achieved. © 1995 American Vacuum Society  
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52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
78.66.Li Other semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Heating uniformity of a microwave discharge plasma to redistribute a solid fuel layer inside a cryogenic target for inertial confinement fusion

C. M. Chen, T. Norimatsu, Y. Izawa, T. Yamanaka, and S. Nakai

J. Vac. Sci. Technol. A 13, 2908 (1995); http://dx.doi.org/10.1116/1.579612 (6 pages) | Cited 2 times

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In the plasma layering technique, a microwave discharge plasma is turned on in the void of a nonuniform solid fuel layer inside a cryogenic laser fusion target to redistribute the nonuniform layer into a uniform one. The heating uniformity of the plasma initiated by a one‐dimensional electric field was examined experimentally and theoretically by making a glow discharge in a quartz shell located in a strong microwave field at room temperature. The heating uniformity on the inner surface of the shell was estimated by measuring the surface temperature of the shell. When the frequency of the external electric field was 2.45 GHz, the resultant measured heating uniformity at the gas density of <0.7 g/m3 should be sufficient to obtain a uniform solid fuel layer for laser implosion experiments. At higher gas densities, the heating uniformity was insufficient because of the nonuniform distribution of the plasma. Countermeasures to improve the uniformity are discussed. © 1995 American Vacuum Society
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28.52.Cx Fueling, heating and ignition
52.50.Gj Plasma heating by particle beams
52.80.Pi High-frequency and RF discharges

Plasma chemical vapor deposition and properties of hard C3N4 thin films

S. Vepr̆ek, J. Weidmann, and F. Glatz

J. Vac. Sci. Technol. A 13, 2914 (1995); http://dx.doi.org/10.1116/1.579613 (6 pages) | Cited 23 times

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Compact thin films of stoichiometric, amorphous C3N4 have been prepared by means of chemical transport of carbon in intense nitrogen glow discharge at relatively high deposition temperature of about 800 °C. Their hardness reached 2500 Vickers (kg/mm2). © 1995 American Vacuum Society
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68.60.Bs Mechanical and acoustical properties
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Automated Langmuir probe characterization of methane/hydrogen low‐pressure radio frequency discharges in a production reactor

F. A. Cali, P. A. F. Herbert, and W. M. Kelly

J. Vac. Sci. Technol. A 13, 2920 (1995); http://dx.doi.org/10.1116/1.579614 (4 pages) | Cited 4 times

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An automated, tuned Langmuir probe has been applied to a commercial, multiply used reactive ion etcher operated by radio frequency‐generated 13.56 MHz low‐pressure discharges. The probe was used to measure the plasma parameters and electron energy distribution function in a methane/hydrogen plasma, an important etchant of optoelectronic semiconductors. Results have revealed a typical electron temperature of approximately 1.5 eV, an electron density of 6×109 cm−3, and a plasma potential of 28 V. The electron energy distribution function is bi‐Maxwellian with a dip appearing at 6 eV, which corresponds to the vibrational state of the methane radical and supports a hypothesis of electron absorption by the radical at this energy. The precautions required to condition both probe and chamber to obtain reliable data are given, and it is shown that the automated Langmuir probe can operate as an in situ diagnostic in polymer producing processing plasmas in operational reactors providing stringent routines are implemented. © 1995 American Vacuum Society
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52.70.Ds Electric and magnetic measurements
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
81.65.-b Surface treatments

High rate–low temperature deposition of silicon dioxide films by remote plasma enhanced chemical vapor deposition using silicon tetrachloride

J. C. Alonso, S. J. Ramírez, M. García, and A. Ortiz

J. Vac. Sci. Technol. A 13, 2924 (1995); http://dx.doi.org/10.1116/1.579615 (6 pages) | Cited 4 times

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Silicon dioxide films have been deposited at rates as high as 1100 Å/min and substrate temperatures as low as 200 °C by a remote plasma enhanced chemical vapor deposition (RPECVD) process using mixtures of silicon tetrachloride, oxygen, hydrogen, and argon. The films were characterized by ellipsometry, chemical etch rate, infrared transmittance, and electrical measurements. Infrared transmittance, refractive index, and etch rate measurements reveal that these oxides are free of Si–OH and Si–H bonds, and their structural quality is close to that of thermal CVD oxides. The electrical quality of the as‐deposited oxides, incorporated in metal–oxide–semiconductor structures, is equivalent to that reported previously for RPECVD oxides deposited from the same mixture at significantly lower deposition rates. The application of these oxides in the fabrication of some multilayer devices such as alternating current electroluminescent devices is briefly described. © 1995 American Vacuum Society
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68.55.-a Thin film structure and morphology
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
78.66.Nk Insulators
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Measurement of the amount of oxygen generated by quartz source walls in a SF6 dense plasma: Application to a helicon reactor

R. Petri, N. Sadeghi, and D. Henry

J. Vac. Sci. Technol. A 13, 2930 (1995); http://dx.doi.org/10.1116/1.579616 (5 pages) | Cited 6 times

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The amount of oxygen generated in a SF6 dense plasma by the etching of the quartz tube walls surrounding the plasma source of the helicon reactor has been measured. Two complementary techniques have been used to identify the wall etch products and the measurement of their equivalent flux: plasma induced emission spectroscopy of oxygen atoms (actinometry) and mass spectrometry by comparison with the amount of the isotopic oxygen (18O2) introduced into the plasma. It appears that, with a 5 mm air gap between the antenna and quartz walls of the reactor, the equivalent oxygen outgassing flux ranges from 2 to 4 sccm, depending on the SF6 pressure and the radio frequency power applied. This corresponds to an oxygen concentration in the gas phase between 15% and 40%, depending on the operating conditions. This result should be considered for the development of future dense plasma reactors using quartz walls and for improvement of the performance of the present generation of inductively coupled and electron cyclotron resonance plasma reactors. © 1995 American Vacuum Society
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52.40.Hf Plasma-material interactions; boundary layer effects
52.70.-m Plasma diagnostic techniques and instrumentation
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition

Thermal desorption spectroscopic analysis for residual chlorine on Al–Si–Cu after Cl2 electron cyclotron resonance plasma etching

Yuden Teraoka, Hidemitsu Aoki, Iwao Nishiyama, Eiji Ikawa, and Takamaro Kikkawa

J. Vac. Sci. Technol. A 13, 2935 (1995); http://dx.doi.org/10.1116/1.579617 (4 pages) | Cited 2 times

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Thermal desorption spectroscopy is used to measure the amount of residual chlorine on Al–Si–Cu. The Al–Si–Cu surface is etched by Cl2 electron cyclotron resonance (ECR) plasma at substrate temperatures of 30 and −60 °C. The surfaces are then cleaned by one of the following methods: de‐ionized water rinsing, H2 ECR plasma irradiation, or annealing in H2/N2 mixed gas. AlCl molecules, which may be responsible for aftercorrosion, are detected. Chlorine compounds, however, cannot be detected by conventional x‐ray photoelectron spectroscopy or Auger electron spectroscopy. The low substrate temperature etching reduces the amount of residual chlorine. Moreover, the cleaning ability of the H2 ECR plasma treatment is no less than that of the de‐ionized water rinse, and is superior to that of annealing in H2/N2 mixed gas. © 1995 American Vacuum Society
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81.05.Bx Metals, semimetals, and alloys
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis

Fluid simulations of particle contamination in postplasma processes

M. P. Garrity, T. W. Peterson, L. M. Garrett, and J. F. O’Hanlon

J. Vac. Sci. Technol. A 13, 2939 (1995); http://dx.doi.org/10.1116/1.579618 (6 pages) | Cited 1 time

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Fluid flow and particle trajectories in postplasma processes are simulated using a commercially available computational fluid dynamics code. Two parallel plate geometries are modeled. Recirculation eddies are observed and particles of 0.01 μm diameter can be trapped in these zones. Gravity can be a dominant mechanism, resulting in particle deposition onto wafer and chamber surfaces. The collection efficiency of particles on the wafer is near unity for particles 0.1 μm or greater in diameter, and efficiency increases with pressure and flow rate. For example, for gas conditions of 20 sccm and 15 mTorr (2 Pa) 35% of 0.01‐μm‐diam particles are collected on the wafer when released 2 cm above the wafer, while at 20 sccm and 100 mTorr (13.3 Pa), collection increases to 95%. Particle deposition as a function of initial particle position depends on chamber configuration. © 1995 American Vacuum Society
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52.65.-y Plasma simulation
85.40.Bh Computer-aided design of microcircuits; layout and modeling

Time‐resolved Fourier transform infrared emission as a plasma diagnostic

G. Hancock and J. P. Sucksmith

J. Vac. Sci. Technol. A 13, 2945 (1995); http://dx.doi.org/10.1116/1.579619 (5 pages) | Cited 2 times

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Time‐resolved infrared emission has been observed by means of a Fourier transform technique from plasmas of fluorinated hydrocarbons under conditions similar to those used in semiconductor surface processing. Emission has been detected from vibrationally excited precursors and reaction products, and examples are shown of emission from HF, CF4, CO2, and CF2O. The time dependences of the signals on plasma extinction give information on the production and relaxation mechanisms taking place. Equilibrated rotational and translational temperatures in the plasma are derived from quantum state distributions in HF. Blackbody emission is observed from both chamber surfaces and from a Si wafer placed in the plasma, and the time‐resolved emission technique is used to measure the surface temperature under conditions in which strong molecular emissions are present. © 1995 American Vacuum Society
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)

Postplasma particle dynamics in a Gaseous Electronics Conference RF Reference Cell

S. M. Collins, D. A. Brown, J. F. O’Hanlon, and R. N. Carlile

J. Vac. Sci. Technol. A 13, 2950 (1995); http://dx.doi.org/10.1116/1.579620 (4 pages) | Cited 1 time

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Particle contamination in plasma tools used for the manufacture of very large scale integrated semiconductor devices on silicon wafers is a major cause of yield loss. Understanding the dynamics of particle movement in the postplasma regime is important to explain the process of their transport to the wafer. The movement of particle contamination in a Gaseous Electronics Conference RF Reference Cell in the postplasma regime was investigated using a novel technique. Particle clouds were observed using laser light scattering together with an image intensifier and a monochromator. This technique allowed particle clouds of low density, that could not otherwise be detected, to be seen. Video analysis of the particles showed movement of the cloud front during the first second after the plasma was extinguished. Using the particle terminal velocity to estimate particle size, we estimate diameters of 0.11 μm in argon and 0.05 μm in krypton. The role of the thermophoretic force on particles during the postplasma was shown to be larger than gravitational forces and to dominate particle transport for small particles under the conditions investigated. A temperature gradient of 12 °C/cm was observed to move these particles away from a warm electrode as the plasma was extinguished and the particles were released from the electrostatic confinement forces generated by the plasma. © 1995 American Vacuum Society
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52.25.Vy Impurities in plasmas
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition

General geometry calculations of one‐stage molecular flow transmission probabilities for turbomolecular pumps

S. Katsimichas, A. J. H. Goddard, R. Lewington, and C. R. E. de Oliveira

J. Vac. Sci. Technol. A 13, 2954 (1995); http://dx.doi.org/10.1116/1.579621 (8 pages) | Cited 4 times

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In this paper the pumping mechanism of a single stage of a turbomolecular pump (TMP) is addressed. A collisionless gas, a Maxwellian distribution of particles at the inlet and outlet surfaces of the passage, and diffuse reflection for the particles that collide with the walls of the passage are assumed. Models of this type have, until now, only been applied to the two‐dimensional (2D) case, i.e., the TMP stage was approximated by an infinite row of blades. This approximation can only be valid for very narrow passages, far from the axis of rotation. In the present work the 2D case has been assessed in detail as a basis for confidence in three‐dimensional (3D) modeling. The main difficulties in modeling the 3D case arise from the geometric complexity and the rotating frame of reference. As a result of the latter, particle orbits are no longer straight lines, and their intersection with the walls has to be calculated iteratively. The Monte Carlo method was chosen to model the 3D case as it appears to have significant advantages. The passage is divided into layers normal to the axis of rotation, and a particle proceeds at every time step to the next or previous layer. This technique of tracking saves computer time as it takes advantage of certain characteristics of the rotational system. Results for different types of blade passages are presented. © 1995 American Vacuum Society
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07.30.Cy Vacuum pumps
47.45.Dt Free molecular flows

Multicomponent vapor transport model for viscous, transitional, and molecular flow

Michael J. Ernst and Harold F. Hemond

J. Vac. Sci. Technol. A 13, 2962 (1995); http://dx.doi.org/10.1116/1.579622 (10 pages)

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A multicomponent vacuum flow and vapor transport model for a long outgassing tube has been developed and verified experimentally. The model includes advective and diffusive vapor transport processes for a wide range of gas flow, from viscous to molecular. Existing single component approaches to the separation of vacuum flow into molecular and viscous fractions have been extended to include multicomponent transport with partial advection and interdiffusion. A set of nonlinear partial differential equations describing vacuum flow and transport in a tube are derived and solved with an iterative numerical scheme. Comparison of model simulations with laboratory measurements of vapor transport in a long vacuum sampling tube showed that the model accurately represents the process of interdiffusion in all flow regimes. Advection was accurately simulated by the model for all vapor components in fully viscous flow. Partial advection and tube limited diffusion in the transition flow range were also well simulated by the model for an argon–air mixture, while benzene–air and 1,1,1‐trichloroethane–air mixtures showed slightly less than predicted partial advection. Reduced advection with these latter compounds may be due to the many energy storage modes available to the multiatomic molecules, which result in less momentum transfer than would be predicted by methods that assume fully elastic collisions between molecules. © 1995 American Vacuum Society
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07.30.Bx Degasification, residual gas
47.45.Dt Free molecular flows

High performance Pirani vacuum gauge

Jin‐Shown Shie, Bruce C. S. Chou, and Yeong‐Maw Chen

J. Vac. Sci. Technol. A 13, 2972 (1995); http://dx.doi.org/10.1116/1.579623 (8 pages) | Cited 10 times

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As an extension of previous work in our laboratory, a wide‐range Pirani gauge that is capable of measuring vacuum pressure down to 10−7 Torr reproducibly has been built. The micromachined Pirani sensor used in the experiments has a suspended membrane that is supported by the nearly radiation‐limited, thermally insulating beam leads crossing over a V‐groove cavity. A method of partial dummy compensation, as proposed previously by Weng and Shie for eliminating the ambient drift, is proved here to be very effective with a thermal drift as small as only 5.7 μV/°C. It has also been found that a thermal‐stress‐induced piezoresistive effect, which has a profound influence on the limitation of measurement, appears in the constant‐bias operation wherein the sensor temperature rises with the reduction of gas pressure and therefore thermal conduction. This effect causes the irreproducibility of pressure measurements by the device below 10−5 Torr. In addition to its inherently higher sensitivity, a constant‐temperature circuit together with a thermoelectric stabilization of the sensor substrate temperature can eliminate the induced piezoresistive error. The constant‐temperature circuit operating on the micro‐Pirani sensor together with the above‐mentioned temperature compensation and the stabilization methods have extended gauge capability down to 10−7 Torr, which is only limited by the signal readout resolution (∼1 μV). This is three orders of magnitude more sensitive than the conventional vacuum gauges of the thermal conductivity type. © 1995 American Vacuum Society
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07.30.Dz Vacuum gauges

Miniaturized thin film thermal vacuum sensor

W. J. Alvesteffer, D. C. Jacobs, and D. H. Baker

J. Vac. Sci. Technol. A 13, 2980 (1995); http://dx.doi.org/10.1116/1.579624 (6 pages) | Cited 8 times

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A new miniaturized thin film Pirani type vacuum sensor that detects pressure from 1×10−5 to 760 Torr was developed. The compact instrument is attitude insensitive, rugged, and has rapid response to pressure variations. The very small dimension between the heating element and the heat sink prevents the flow from entering into the viscous regime thus resulting in a predominately conductive heat transfer over the entire pressure range. This removes the complexities introduced into the pressure versus output curve by convective heat transfer. The output is linear from 1×10−4 to 1 Torr, and then monotonically increases beyond 760 Torr. A unique feature of this instrument is the use of a microprocessor to compute the sensor power from the analog voltage and current. In the molecular flow regime, the absolute pressure is directly proportional to the power dissipated by the surrounding gas. By measuring the power, the sensor rejects most of the errors introduced by ambient temperature variations. The analog‐to‐digital converters for both the current and the voltage signals use the ∑–Δ conversion method to reject electrical noise by the averaging technique. This results in the stable signal detection of pressure down to 1×10−5 Torr. The instrument is thermally stable over an ambient temperature range of 0–50 °C when the pressure is between 1×10−4 and 760 Torr. © 1995 American Vacuum Society
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07.30.Dz Vacuum gauges

Plasma source ion nitriding: A new low temperature, low‐pressure nitriding approach

M. K. Lei and Z. L. Zhang

J. Vac. Sci. Technol. A 13, 2986 (1995); http://dx.doi.org/10.1116/1.579625 (5 pages) | Cited 11 times

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Plasma source ion nitriding is a new approach for surface modification of steel with certain advantages over conventional plasma nitriding and plasma‐based nitrogen ion implantation. A nitriding apparatus based on an electron cyclotron resonance (ECR) microwave plasma source has been developed. Nitrogen ions are accelerated from the ECR microwave plasma by a low‐pulsed negative bias (typically −2 kV) which is applied directly to the workpiece, implanted, and finally diffused into the steel at elevated temperatures that are regulated up to 550 °C by an auxiliary heater. An application of plasma source ion nitriding into 1Cr18Ni9Ti austenitic stainless steel is described. The nitriding layer thicknesses are varied continuously from 0.8 to 10 μm at various process temperatures from 230 to 480 °C for a nitriding time of 4 h. A dramatic increase in microhardness has been observed. Glancing angle x‐ray diffraction has been used to determine the structural changes that occur in the nitrided surface layer. © 1995 American Vacuum Society
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52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
81.65.-b Surface treatments

First thin film realization of a helicoidal bianisotropic medium

Kevin Robbie, Michael J. Brett, and Akhlesh Lakhtakia

J. Vac. Sci. Technol. A 13, 2991 (1995); http://dx.doi.org/10.1116/1.579626 (3 pages) | Cited 53 times

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Abstract Unavailable
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61.30.Gd Orientational order of liquid crystals; electric and magnetic field effects on order
68.55.-a Thin film structure and morphology
81.15.Jj Ion and electron beam-assisted deposition; ion plating

Large grain size CdTe films grown on glass substrates at low temperature

M. Zapata‐Torres, R. Castro‐Rodríguez, A. Zapata‐Navarro, John L. Wallace, Ramón Pomes, J. L. Peña, and M. H. Farías

J. Vac. Sci. Technol. A 13, 2994 (1995); http://dx.doi.org/10.1116/1.579627 (3 pages) | Cited 1 time

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Polycrystalline films of CdTe were prepared by the hot wall‐close‐spaced vapor transport technique on Corning glass substrates at substrate temperatures below 450 °C. The thickness of the films was constant at 25 μm for all samples grown at different substrate temperatures and different gas pressures. The film thickness was found to be a function of deposition time only (5 μm per min), and virtually independent of substrate temperature and control gas pressure. The grain size was a monotonic function of film thickness, reaching 40 μm for a film thickness of 50 μm. © 1995 American Vacuum Society
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68.55.-a Thin film structure and morphology
81.15.Jj Ion and electron beam-assisted deposition; ion plating

Effect of substrate heating and high energy heavy ion irradiation on the performance of Cr films

Sangeeta Srivastav and Amitabh Jain

J. Vac. Sci. Technol. A 13, 2997 (1995); http://dx.doi.org/10.1116/1.579628 (3 pages)

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Abstract Unavailable
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61.80.Jh Ion radiation effects
68.60.Bs Mechanical and acoustical properties
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Al–Mg alloy from a beer can as a simple source of Mg metal for evaporators in ultrahigh vacuum applications

F. J. Esposto, C. Cory, K. Griffiths, P. R. Norton, and R. S. Timsit

J. Vac. Sci. Technol. A 13, 3000 (1995); http://dx.doi.org/10.1116/1.579629 (3 pages)

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Abstract Unavailable
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Use of an inexpensive solid state differential sensor as a 0–35 mbar pressure gauge

Marc Fleury and Louis D. Smullin

J. Vac. Sci. Technol. A 13, 3003 (1995); http://dx.doi.org/10.1116/1.579630 (1 page)

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We describe a simple setup that enables a solid state differential pressure sensor, normally designed to operate around 1 atm with a range of 70 mbar (−35/+35 mbar), to operate in high vacuum and act as a 0–35 mbar pressure gauge. © 1995 American Vacuum Society  
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07.30.Dz Vacuum gauges
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