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Nov 2003

Volume 21, Issue 6, pp. L23-2012

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Structural, electrical, and optical properties of diamondlike carbon films deposited by dc magnetron sputtering

E. Broitman, O. P. A. Lindquist, N. Hellgren, L. Hultman, and B. C. Holloway

J. Vac. Sci. Technol. A 21, L23 (2003); http://dx.doi.org/10.1116/1.1617277 (5 pages) | Cited 2 times

Online Publication Date: 29 October 2003

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The electrical and optical properties of diamondlike carbon films deposited by direct current magnetron sputtering on Si substrates at room temperature have been measured as a function of the ion energy (Eion) and ion-to-carbon flux (Jion/JC). The results show that, in the ranges of 5 eV⩽Eion⩽85 eV and 1.1⩽Jion/JC⩽6.8, the presence of defective graphite formed by subplanted C and Ar atoms, voids, and the surface roughness, are the dominant influences on the resistivity and optical absorption. © 2003 American Vacuum Society.
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68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
78.66.Jg Amorphous semiconductors; glasses
73.61.Jc Amorphous semiconductors; glasses
81.05.U- Carbon/carbon-based materials
81.15.Cd Deposition by sputtering
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
61.43.Dq Amorphous semiconductors, metals, and alloys
73.61.Cw Elemental semiconductors
78.66.Db Elemental semiconductors and insulators
81.05.Cy Elemental semiconductors
81.05.Gc Amorphous semiconductors
73.50.Dn Low-field transport and mobility; piezoresistance

Measurement of the plasma potential adjacent to the substrate in a midfrequency bipolar pulsed magnetron

S. K. Karkari, A. Vetushka, and J. W. Bradley

J. Vac. Sci. Technol. A 21, L28 (2003); http://dx.doi.org/10.1116/1.1622673 (5 pages) | Cited 20 times

Online Publication Date: 29 October 2003

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Using an emissive probe, the temporal evolution of plasma potential Vp in front of an electrically isolated substrate in an asymmetric pulsed dc magnetron has been determined. The discharge pulsing frequency was 100 kHz, with a 50% duty cycle. Through a scheme of externally biasing the emissive probe, it was found that the time response of the probe could be improved greatly, and a resolution of 20 ns was achieved. This good response revealed that Vp is highly modulated by the transient cathode potential, following it closely and varying from a value just above the ground potential in the pulse “on” phase, up to a value of +277 V during the positive overshoot in the “reverse” pulse phase. During the whole pulse cycle, Vp was found to remain above the most positive surface in the discharge. The results confirm our previous prediction for Vp, based on energy-resolved mass spectrometry [Bradley et al., Plasma Sources Sci. Technol. 11, 165 (2002)], which indicated that ions must be created at high positive plasma potentials. However, measurements here show that the substrate floating potential Vf is also strongly modulated and the difference Vp−Vf, which determines the ion bombarding energy, always remains below 40 V during steady phases of the discharge throughout the pulse cycle. © 2003 American Vacuum Society.
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52.77.Dq Plasma-based ion implantation and deposition
52.70.Nc Particle measurements
52.80.-s Electric discharges
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Effects of titanium content on sol-gel hard optical films prepared in an organic-inorganic hybrid system

Wenxiu Que and X. Hu

J. Vac. Sci. Technol. A 21, 1809 (2003); http://dx.doi.org/10.1116/1.1607351 (5 pages) | Cited 1 time

Online Publication Date: 16 September 2003

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The effects of titanium content on the optical and mechanical properties of silica–titania hard optical films by the sol-gel technique using γ-glycidoxypropyltrimethoxysilane, methyltrimethoxysilane, and tetrapropylorthotitanate as starting materials are studied. Thermal gravimetric analysis, ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, and Raman spectroscopy are used to investigate the optical and structural properties of the films. The results indicate that crack-free and high transparency silica–titania film with a thickness more than 0.6 μm can be obtained by a single spin-coating process after a heat treatment at 500 °C. The hardness and Young’s modulus of the films are characterized by a nanoindenter and they show a linear dependence on titanium content. Hardness as high as 6.60 GPa is obtained in a 0.5 M titanium content film and heat treated at 800 °C. It is proposed that the high hardness of the film may be related to the carbon and titanium content in the film. © 2003 American Vacuum Society.
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42.79.Wc Optical coatings
81.15.Rs Spray coating techniques
78.66.Nk Insulators
68.60.Bs Mechanical and acoustical properties
68.55.-a Thin film structure and morphology

Effects of indium surfactant on the crystalline and optical properties of GaN during initial growth stage

Hairong Yuan, Soo Jin Chua, Sudhiranjan Tripathy, and Peng Chen

J. Vac. Sci. Technol. A 21, 1814 (2003); http://dx.doi.org/10.1116/1.1611888 (6 pages) | Cited 7 times

Online Publication Date: 16 September 2003

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In this article, we report the effects of indium doping on crystalline and optical properties of GaN grown by metalorganic chemical vapor deposition during initial growth stage. Atomic force microscopy observations revealed that the In doping enhanced the lateral growth while the c-face growth rate was reduced. X-ray diffraction (XRD) and micro-Raman scattering measurements showed that the epilayers during this growth stage are nearly strain free. From XRD measurements, we found that In doping has increased the full width at half maximum values in both (0002) and (20math4) ω-scan. Room temperature photoluminescence measurements show that In doping has enhanced the band-edge related emission by an order of magnitude compared to that of undoped GaN. Raman spectra indicate that In doping suppressed the misorientation of crystallites. In addition, a Raman mode occurred near 710 cm−1 in the In-doped GaN and has been assigned as the Fröhlich vibration. © 2003 American Vacuum Society.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
78.66.Fd III-V semiconductors
82.70.Uv Surfactants, micellar solutions, vesicles, lamellae, amphiphilic systems, (hydrophilic and hydrophobic interactions)
78.55.Cr III-V semiconductors
81.05.Ea III-V semiconductors
61.72.uj III-V and II-VI semiconductors
78.30.Fs III-V and II-VI semiconductors

Effects of ion beam application on the deposition of low-resistivity titanium nitride films onto silicon

Katsuhiro Yokota, Kazuhiro Nakamura, Tomohiko Kasuya, Katsuhisa Mukai, and Masami Ohnishi

J. Vac. Sci. Technol. A 21, 1820 (2003); http://dx.doi.org/10.1116/1.1609458 (9 pages)

Online Publication Date: 16 September 2003

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Titanium nitride (TiN) films were deposited onto (111) silicon wafers using an ion beam assisted deposition technique employing an electron cyclotron resonance ion source as a means of ionizing the nitrogen gas. The deposited TiN films consisted predominantly of cubic TiN crystals preferentially oriented in the (200) lattice plane, in addition to a small amount of hexagonal TiN and Ti5Si3 crystals. The growth of the Ti5Si3 crystals, however, was restricted to the case where TiN films were deposited with a large fraction of nitrogen ions. The resistivities of the deposited TiN films, which significantly depended upon the fraction of nitrogen ions in the nitrogen beam, decreased with increasing substrate temperature and film thickness. Furthermore, the resistivities of the deposited TiN films were inversely proportional to the average radius of crystallites. © 2003 American Vacuum Society.
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81.15.Jj Ion and electron beam-assisted deposition; ion plating
73.61.Ng Insulators

Mechanical and tribological properties of sub- and superstoichiometric Ti–C and Ti–Si–C films deposited by magnetron sputtering-pulsed laser deposition

J. E. Krzanowski, J. J. Nainaparampil, and A. R. Phani

J. Vac. Sci. Technol. A 21, 1829 (2003); http://dx.doi.org/10.1116/1.1609459 (8 pages) | Cited 3 times

Online Publication Date: 16 September 2003

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The magnetron sputtering–pulsed laser deposition (MSPLD) method has been used to deposit Ti–C and Ti–Si–C films with both sub- and superstoichiometric levels of carbon. The structure and composition of the films were analyzed by transmission electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. The mechanical properties were determined by nanoindentation and the tribological properties by pin-on-disk testing. Films deposited with sub- and near stoichiometric levels of carbon had good crystallinity and strong (111) texture. However, films deposited under similar conditions but with a substrate bias resulted in superstoichiometric carbon levels and nanocrystalline or near-amorphous structures. The hardness of these superstoichiometric films was generally lower than the substoichiometric films, but they also exhibited significantly better wear life. The laser power used in the MSPLD process was also found to influence hardness, where increased laser power led to higher hardness levels. Using these results, an effort was made to deposit a film with optimal mechanical and tribological properties by depositing a Ti4Si–C film with −150 V bias, maximum laser power (700 mJ/pulse) at a temperature of 400 °C. This film contained 55% carbon, had a hardness of 28 GPa, and ran for greater than 106 cycles on the pin-on-disk test. © 2003 American Vacuum Society.
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68.60.Bs Mechanical and acoustical properties
68.55.-a Thin film structure and morphology
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
81.40.Pq Friction, lubrication, and wear
62.20.Qp Friction, tribology, and hardness
68.55.Nq Composition and phase identification
81.15.Cd Deposition by sputtering
81.15.Fg Pulsed laser ablation deposition
68.37.Lp Transmission electron microscopy (TEM)

Etching characteristics and mechanism of Au thin films in inductively coupled Cl2/Ar plasma

A. M. Efremov, Dong-Pyo Kim, and Chang-Il Kim

J. Vac. Sci. Technol. A 21, 1837 (2003); http://dx.doi.org/10.1116/1.1609460 (6 pages) | Cited 3 times

Online Publication Date: 16 September 2003

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The etching characteristics and physical/chemical mechanisms of Au thin films in Cl2/Ar plasma were investigated. It was found that an increase of the Ar content in Cl2/Ar plasma under constant pressure and input power conditions leads to an increasing etch rate of Au, which reaches a maximum value at 80%Ar/20%Cl2. X-ray photoelectron spectroscopy of the etched surfaces indicated the accumulation of reaction products in a chlorine-rich plasma. A proposed zero-dimensional model of volume kinetics, which involved the Langmuir probe data for electron temperature and electron density, showed monotonic change of both densities and fluxes of active species such as chlorine atoms and positive ions. In contrast, analyses of surface kinetics showed the possibility of nonmonotonic etch rate behavior due to the concurrence of physical and chemical factors in ion-assisted chemical reaction. © 2003 American Vacuum Society.
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52.77.Bn Etching and cleaning
81.65.Cf Surface cleaning, etching, patterning
52.25.-b Plasma properties
52.70.Ds Electric and magnetic measurements
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Characterization of B–C–N hybrid prepared by ion implantation

Iwao Shimoyama, Yuji Baba, Sekiguchi Tetsuhiro, Krishana G. Nath, Masayoshi Sasaki, and Kenji Okuno

J. Vac. Sci. Technol. A 21, 1843 (2003); http://dx.doi.org/10.1116/1.1611887 (6 pages) | Cited 3 times

Online Publication Date: 1 October 2003

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Ion implantation method is applied to synthesize B–C–N hybrids and their electronic structures are characterized by x-ray photoelectron spectroscopy. A boron nitride film is deposited on a graphite target by borazine plasma implantation. At the interface between the BN film and the graphite, a variety of bonding combinations including B–N, B–C, and C–N are observed. This proved that B–C–N hybrids are formed by this method. © 2003 American Vacuum Society.
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61.72.uj III-V and II-VI semiconductors
68.35.Ct Interface structure and roughness
61.82.Fk Semiconductors
79.60.Jv Interfaces; heterostructures; nanostructures
61.80.Jh Ion radiation effects

Stable and unstable behavior of inductively coupled electronegative discharges

A. M. Marakhtanov, M. Tuszewski, M. A. Lieberman, A. J. Lichtenberg, and P. Chabert

J. Vac. Sci. Technol. A 21, 1849 (2003); http://dx.doi.org/10.1116/1.1613953 (16 pages) | Cited 19 times

Online Publication Date: 1 October 2003

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Plasma instabilities have been observed in low-pressure inductive discharges, in the transition between low density capacitively driven and high density inductively driven discharges when attaching gases such as SF6 and Ar/SF6 mixtures are used. Oscillations of charged particles, plasma potential, and light, with frequencies from a few hertz to tens of kilohertz, are seen for gas pressures between 1 and 100 mTorr and discharge powers in the range of 75–1200 W. The region of instability increases as the plasma becomes more electronegative and the frequency of plasma oscillations increases as the power, pressure, and gas flow rate increase. Time-resolved measurements of electron temperature, and time averaged ion energy distribution at the wall have been made. A volume-averaged (global) model of the instability has been developed, for a discharge containing time varying densities of electrons, positive ions, and negative ions, and time invariant excited states and neutral densities. The particle and energy balance equations are integrated to produce the dynamical behavior. The model agrees well with experimental observations, and also shows a significant influence of the matching network. Values of plasma parameters and of chemical composition are measured to set the values used in the model, as required to obtain the good agreement with experiment. Capacitive coupling plays a crucial role in the instability process. A variable electrostatic (Faraday) shield has been used to control the capacitive coupling from the excitation coil to the plasma. The plasma instability disappears when the shielded area exceeds 65% of the total area of the coil. The model gives a slightly higher value of 85% for instability suppression with the same discharge conditions (Ar/SF6 1:1, 5 mTorr). © 2003 American Vacuum Society.
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52.80.Tn Other gas discharges
52.35.Qz Microinstabilities (ion-acoustic, two-stream, loss-cone, beam-plasma, drift, ion- or electron-cyclotron, etc.)

Fluorinated ethylene propylene copolymer coating for the stability enhancement of electroactive and photoactive systems

Luping Zhao, K. G. Neoh, Yan Zhang, and E. T. Kang

J. Vac. Sci. Technol. A 21, 1865 (2003); http://dx.doi.org/10.1116/1.1615970 (8 pages)

Online Publication Date: 1 October 2003

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The effectiveness of radio frequency sputtered fluorinated ethylene propylene copolymer (FEP) for the stability enhancement of electroactive and photoactive systems was investigated. Two kinds of electroactive polymer systems, polyaniline (PANI) coated low density polyethylene (LDPE) film and PANI-viologen assembly, were tested. In both cases, a sputtered FEP coating of <10 nm in thickness significantly enhanced the electrical stability of the films in water. The enhancement of the electrical stability of the PANI-LDPE film was also achieved in basic aqueous solution of pH up to 12 with a FEP coating of 40–50 nm in thickness. The deposition of a FEP coating on the photoactive viologen system (viologen grafted on LDPE film) prolonged its photochromic effect by inhibiting the diffusion of oxygen, and hence the reoxidation of the highly colored viologen radical cations to the dication state. © 2003 American Vacuum Society.
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73.61.Ph Polymers; organic compounds
81.15.Cd Deposition by sputtering
68.55.-a Thin film structure and morphology

Control of pressure rise in a vacuum chamber by boron nitride and copper composite coating

Tetsuo Oishi, Youko Konishi, Masahiro Goto, Akira Kasahara, Masahiro Tosa, and Kazuhiro Yoshihara

J. Vac. Sci. Technol. A 21, 1873 (2003); http://dx.doi.org/10.1116/1.1615971 (4 pages)

Online Publication Date: 1 October 2003

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In order to control pressure rise in a vacuum chamber, a radio-frequency magnetron cosputter deposition system has been developed and boron nitride and copper composite (BN/Cu) film was coated onto the inner surface of a vacuum chamber in the shape of a cylinder. Outgassing rate of the BN/Cu coated chamber was estimated with a pressure rise method to be about 5×10−12 Pa m s−1, which was two orders lower than that of the noncoated vacuum chamber in the same shape as the BN/Cu coated chamber. Mass spectra of the residual gas in the chamber indicated that the outgassing of various gas species, such as hydrogen gas, nitrogen gas, and oxygen gas, were reduced by the BN/Cu coating. These results concluded that the BN/Cu coating could control pressure rise in a vacuum chamber. © 2003 American Vacuum Society.
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials
07.30.Bx Degasification, residual gas
81.15.Cd Deposition by sputtering

Fe-doped photocatalytic TiO2 film prepared by pulsed dc reactive magnetron sputtering

Wenjie Zhang, Ying Li, Shenglong Zhu, and Fuhui Wang

J. Vac. Sci. Technol. A 21, 1877 (2003); http://dx.doi.org/10.1116/1.1615973 (6 pages) | Cited 5 times

Online Publication Date: 1 October 2003

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Fe-doped TiO2 films were prepared by means of the pulsed dc reactive magnetron cosputtering method using Ti and Fe mixed target. The deposition condition was optimized to produce uniform and transparent TiO2 films. The mixed target was more difficult to sputter out than the pure titanium target, whereas the threshold remained stable in spite of the variation of the fixed iron surface area, which controlled iron concentration in the Fe-doped TiO2 films. The sputtering rates of iron oxides were higher than that of titanium oxides. The surface morphologies of the Fe-doped films changed from uniform to rough when the iron concentration increased. The rutile phase took the place of the anatase phase after the iron concentration exceeded 15 at. %. Iron oxides phases appeared in the high iron concentration samples. The absorption edges of the Fe-doped TiO2 films shifted to visible region with the increasing concentration of iron oxides. The films with low iron concentrations showed better photocatalytic activity than the pure TiO2.. On the contrary, the photocatalytic degradation rates of methyl orange on the highly iron doped TiO2 films decreased abruptly. © 2003 American Vacuum Society.
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82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
68.55.-a Thin film structure and morphology
78.66.Li Other semiconductors
81.15.Cd Deposition by sputtering
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
68.35.B- Structure of clean surfaces (and surface reconstruction)
78.40.Ha Other nonmetallic inorganics

Antimony segregation in the oxidation of AlAsSb interlayers

A. M Andrews, K. L. van Horn, T. Mates, and J. S. Speck

J. Vac. Sci. Technol. A 21, 1883 (2003); http://dx.doi.org/10.1116/1.1613954 (9 pages)

Online Publication Date: 2 October 2003

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The lateral wet oxidation of strained AlAsSb was studied. AlAs0.80Sb0.20 interlayers were grown on a GaAs substrate and capped with a lattice-matched In0.25Ga0.75As layer. The AlAsSb was oxidized between 350 and 450 °C. Oxidation temperatures >400 °C resulted in poor surface morphology and delamination. Oxidation of thicker AlAsSb interlayers (h≈2000 Å) resulted in metallic Sb layers forming between the AlOx and the semiconductor interfaces. The remaining Sb metal at the oxide–semiconductor interface was ∼15% oxidized. Lateral wet oxidation of thinner AlAsSb interlayers (h⩽500 Å) resulted in Sb inclusions at the oxide–semiconductor interface. The Sb inclusions were 1.5–2.0 μm in diameter and the inclusion thickness was approximately equal to the AlAsSb layer thickness. Methanol (CH3OH) was added to the water mixture with the intent to stabilize the otherwise unstable stibine (SbH3) such that Sb could be removed from the oxidizing structure. However, methanol addition resulted in a decreased oxidation rate and a change in the Sb precipitate morphology. The Sb inclusions observed in pure water oxidation changed to a Sb finger-like morphology with increasing methanol concentration. The Sb fingers were 1.0–2.0 μm wide and as long as the oxidation depth. Oxidation of AlAsSb interlayers h⩽200 Å were limited by the incorporation of Ga from the substrate and capping layer into the oxidation layer. Doping the oxidation AlAsSb interlayer 1×1018 cm−3 n type (Si or Te) did not result in any improvement in Sb segregation. © 2003 American Vacuum Society.
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68.35.Dv Composition, segregation; defects and impurities
81.65.Mq Oxidation
68.65.-k Low-dimensional, mesoscopic, nanoscale and other related systems: structure and nonelectronic properties

Formation and annealing effect for close-packed Ge/Cu(111) layers

J. S. Tsay, L. W. Chang, and A. B. Yang

J. Vac. Sci. Technol. A 21, 1892 (2003); http://dx.doi.org/10.1116/1.1615972 (3 pages) | Cited 1 time

Online Publication Date: 2 October 2003

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Growth and annealing effects of Ge/Cu(111) ultrathin films as deposited at ambient temperature have been studied using Auger electron spectroscopy and low-energy electron diffraction techniques. Ge/Cu(111) system shows a 1×1 structure up to 5 monolayers as deposited at 300 K. The kinetic energy of Cu L3M45M45 Auger electrons shifts to a lower value upon deposition of Ge overlayers. This could be explained by the electric charge transfer between Ge and Cu atoms. From the intensity ratio change of Auger signals (IGe/ICu), significant interdiffusion of Ge/Cu(111) films occurs around 375 K. Owing to the formation of a Cu-rich surface layer, the Cu L3M45M45 peak restores to the initial kinetic energy of a clean Cu(111) surface at 500 K. © 2003 American Vacuum Society.
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68.55.A- Nucleation and growth
61.72.Cc Kinetics of defect formation and annealing
66.30.Ny Chemical interdiffusion; diffusion barriers
68.35.Fx Diffusion; interface formation
79.20.Fv Electron impact: Auger emission

Microstructure and properties of ultrathin amorphous silicon nitride protective coating

Bing K. Yen, Richard L. White, Robert J. Waltman, Qing Dai, Dolores C. Miller, Andrew J. Kellock, Bruno Marchon, Paul H. Kasai, Michael F. Toney, Brian R. York, Hong Deng, Qi-Fan Xiao, and Vedantham Raman

J. Vac. Sci. Technol. A 21, 1895 (2003); http://dx.doi.org/10.1116/1.1615974 (10 pages) | Cited 10 times

Online Publication Date: 3 October 2003

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The effect of N content on the structure and properties of rf reactively sputtered amorphous silicon nitride (a-SiNx) has been studied by Rutherford backscattering spectrometry, x-ray reflectivity, ellipsometry, and nano-indentation. The N content in the film increased with the N2 concentration in the sputtering gas until the Si3N4 stoichiometry was reached. The hardness of a-SiNx increased with density, which in turn increased with the N content. The maximum hardness of 25 GPa and density of 3.2 g/cm3 were attained at the stoichiometric Si3N4 composition. With the application of a protective overcoat for magnetic disks in mind, thin a-SiNx films were deposited on CoPtCr media to examine their coverage, pinhole density, and wear resistance. According to x-ray photoelectron spectroscopy, the minimum thickness of a-SiNx required to protect the CoPtCr alloy from oxidation was 10 Å, which was 10 Å thinner than that of the reference amorphous nitrogenated carbon (a-CNx). A statistic model showed this lower thickness required for a-SiNx can be attributed to its high density, which corresponds to 93% bulk density of Si3N4. Compared with 45 Å a-CNx coated disks, 15 Å a-SiNx coated disks had lower pinhole defect density and superior wear resistance. © 2003 American Vacuum Society.
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68.60.Bs Mechanical and acoustical properties
68.55.-a Thin film structure and morphology
81.40.Pq Friction, lubrication, and wear
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.Qp Friction, tribology, and hardness
82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis
79.60.Dp Adsorbed layers and thin films

Microstructure of Mg–Ni thin film prepared by direct current magnetron sputtering and its properties as a negative electrode

L. Z. Ouyang, C. Y. Chung, H. Wang, and M. Zhu

J. Vac. Sci. Technol. A 21, 1905 (2003); http://dx.doi.org/10.1116/1.1611886 (4 pages) | Cited 1 time

Online Publication Date: 7 October 2003

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Mg–Ni thin films for nickel–metal hydride batteries electrodes were prepared by direct current magnetron sputtering from a Mg–Ni alloy target on three substrates (glass, Ni foil, and foam Ni substrates) and characterized by differential scanning calorimetry, x-ray fluorescence measurement, energy dispersive spectroscopy, x-ray diffraction, and transmission electron microscopy. The microstructure of the Mg–Ni thin films was found to be composed of an amorphous Mg–Ni phase and Mg2Ni nanocrystalline, regardless the substrates. The amorphous phase is crystallized into Mg2Ni at about 360 °C. The maximal discharge capacity of Mg–Ni thin film being 557 mA h/g was achieved in an alkaline solution. © 2003 American Vacuum Society.
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68.55.-a Thin film structure and morphology
68.55.Nq Composition and phase identification
82.47.Cb Lead-acid, nickel-metal hydride and other batteries
64.75.-g Phase equilibria
68.37.Lp Transmission electron microscopy (TEM)

Influence of carbon content and average energy of deposited ions on mechanical and optical properties of Si–C–N films grown by plasma ion immersion processing

Ivan V. Afanasyev-Charkin and Michael Nastasi

J. Vac. Sci. Technol. A 21, 1909 (2003); http://dx.doi.org/10.1116/1.1615969 (6 pages)

Online Publication Date: 7 October 2003

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Amorphous silicon nitride and silicon carbonitride films were deposited by the plasma immersion ion processing technique. The SiCxNy films were obtained in the range of compositions 0⩽x/(x+y)⩽0.53. Gas pressure during the deposition was kept around 0.13 Pa (1 mTorr) and SiH4, N2, Ar, and C2H2 gas mixtures were used. The composition of the film grown without addition of C2H2 was close to that of Si3N4. With the addition of C2H2 the areal density of Si and N atoms remains almost constant, whereas the concentration of C increases. The addition of carbon to the films causes a decrease in hardness from 13.5 to 0.85 GPa, a reduction in the band gaps from about 5 to about 2 eV, and a decrease in the refractive index from about 1.63 to 1.5. The density of the films with the addition of carbon decreases from 2.37 to 0.46 g/cm3. The evolving physical properties in these films are shown to result from both the increasing fraction of C2H2 in the gas mixture and a reduction in the average energy imparted to the growing film during deposition. © 2003 American Vacuum Society.
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68.60.Bs Mechanical and acoustical properties
68.55.Nq Composition and phase identification
78.66.-w Optical properties of specific thin films
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
62.20.Qp Friction, tribology, and hardness

Plasma etching selectivity of ZrO2 to Si in BCl3/Cl2 plasmas

Lin Sha and Jane P. Chang

J. Vac. Sci. Technol. A 21, 1915 (2003); http://dx.doi.org/10.1116/1.1615975 (8 pages) | Cited 30 times

Online Publication Date: 7 October 2003

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To improve the etching selectivity of ZrO2, a promising high-k dielectric material on silicon, BCl3 was added to a Cl2 plasma to enhance the ZrO2 etch rate while suppressing the silicon etch rate. The electron temperature, ion density, and gas-phase composition in BCl3/Cl2 plasmas were characterized by Langmuir probe, optical emission spectroscopy, and quadrupole mass spectrometry. The maximum ZrO2 etch rate coincides with the highest ion density obtained at 40% of BCl3 in BCl3/Cl2 plasmas. In etching ZrO2, oxygen was removed as boron-oxygen-chlorine compounds, in contrast to its removal as ClO+ in a pure Cl2 plasma. Boron passivation of silicon forming B–Si bonds was confirmed by x-ray photoelectron spectroscopy. The threshold energies for etching ZrO2 and Si in pure BCl3 plasmas were determined to be 21 and 28 eV, respectively. At an ion energy of 75 eV, the etching selectivity between ZrO2 and Si was ∼0.01 in a pure Cl2 plasma to ∼1.5 in a pure BCl3 plasma. The etching selectivity was increased to be greater than 10 at ion energies near and above the ZrO2 etching threshold. © 2003 American Vacuum Society.
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77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
77.55.-g Dielectric thin films
52.77.Bn Etching and cleaning
81.65.Cf Surface cleaning, etching, patterning
52.25.-b Plasma properties
52.70.Ds Electric and magnetic measurements
52.70.Kz Optical (ultraviolet, visible, infrared) measurements
79.60.Dp Adsorbed layers and thin films

Effect of an applied voltage during annealing on the resistivity and transparency of the amorphous tin oxide films

N. Parkansky, B. Alterkop, S. Goldsmith, and R. L. Boxman

J. Vac. Sci. Technol. A 21, 1923 (2003); http://dx.doi.org/10.1116/1.1619415 (4 pages) | Cited 3 times

Online Publication Date: 8 October 2003

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300 nm thick tin oxide thin films were deposited on glass by filtered vacuum arc deposition and annealed in air at 300 and 350 °C for up to 60 min. The resistivity of the coating before annealing was 3 mohm cm. During the annealing, an electric field E in the range of 0–200 V/cm was applied to the sample parallel to the film surface. As the sample was connected in series to a 5 kΩ resistor, the electric field on the sample was not constant during the annealing, depending on the variation of its resistance. The initial magnitude of the electric field on the sample was in the range of 0–17.4 V/cm. Film resistance decreased as function of short annealing times, reaching a minimum value after 1 to 3 min, and depended on the applied voltage U. At longer annealing times, the resistance continuously increased up to saturation after 8 min. The magnitude of the saturated resistance also depended on U, that is, on the field in the sample. The lowest electric resistivity (0.6 mohm cm) was obtained at 300 °C and U=100 V (initial field in sample of ∼9 V/cm). The minimum resistivity of annealed films without electric-field application was three times higher, 1.8 mohm cm. However, the minimal resistivity measured when U=200 V/cm (initial field 19.4 V/cm) was 2.1 mohm cm, i.e., larger by a factor of ∼1.2 than that obtained with no field. The visible transmittance, T, was measured before and after annealing, being 67% before annealing. The transmittance of annealed films depended on the annealing time and the applied field. The highest visible transmittance of films annealed with E=100 V/cm was 89%, and obtained after annealing for 5 min. The maximal visibility of films annealed with no field was 81%, and obtained after annealing for 8 min. The atomic ratio O/Sn on the film surface decreased linearly with time from ∼2 to ∼0.7 with U=100 V, but it remained greater than 1.3 at U=0 V. The O/Sn ratio remained approximately constant (∼2) at a depth larger than 20 nm. © 2003 American Vacuum Society.
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73.61.Jc Amorphous semiconductors; glasses
73.50.Dn Low-field transport and mobility; piezoresistance
78.66.Jg Amorphous semiconductors; glasses
61.72.Cc Kinetics of defect formation and annealing
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Investigation of the role of plasma conditions on the deposition rate and electrochromic performance of tungsten oxide thin films

Michael Seman and Colin A. Wolden

J. Vac. Sci. Technol. A 21, 1927 (2003); http://dx.doi.org/10.1116/1.1619416 (7 pages) | Cited 6 times

Online Publication Date: 8 October 2003

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Plasma-enhanced chemical vapor deposition has been used to form electrochromic tungsten oxide thin films from gas mixtures of WF6, O2, and H2. The chemistry of this system was investigated using optical emission spectroscopy. The plasma composition and deposition rate were examined as a function of operating conditions. Growth rates were maximized when the atomic fluorine density was attenuated and the atomic oxygen density was saturated. With the exception of hydrogen scavenging of fluorine radicals, the major reaction pathway was simply dissociation, as the densities of the atomic species were proportional to the initial reagent composition. An apparatus was built to evaluate electrochemical performance in direct registry with optical transmission. This characterization technique was used to demonstrate that ion bombardment has a dramatic impact on electrochromic performance. Ion bombardment was found to increase film density, as inferred from measurements of the refractive index. Efficient hydrogen intercalation was observed only in those films whose refractive index at 400 nm were less than 2.1. Finally, it was shown that a tungsten oxide thickness of ∼600 nm was optimal with respect to contrast ratio. © 2003 American Vacuum Society.
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78.66.Nk Insulators
78.20.Jq Electro-optical effects
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
78.40.Ha Other nonmetallic inorganics
52.77.Dq Plasma-based ion implantation and deposition
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.Nq Composition and phase identification

Temperature profile and crater formation induced in high-current pulsed electron beam processing

Ying Qin, Chuang Dong, Xiaogang Wang, Shengzhi Hao, Aimin Wu, Jianxin Zou, and Yue Liu

J. Vac. Sci. Technol. A 21, 1934 (2003); http://dx.doi.org/10.1116/1.1619417 (5 pages) | Cited 21 times

Online Publication Date: 8 October 2003

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We study in this article the formation mechanism of craters on a metal surface during the high current pulsed electron beam processing. Based on experimental investigations and a physical model, the melting process and their temperature profiles are simulated for substrates of aluminum and steels. Initial melting positions, crater depths, and melting layer thickness are computed, the results being in a good agreement with experimental data. It is also confirmed that the temperature rises faster at a subsurface layer instead of at the outermost surface due to the maximum energy deposition located at about 1/3 of the total penetration depth of the beam. Such a subsurface layer heating and melting mechanism causes eruptions of the subsurface layer liquid matters through the outermost surface and produces the typical surface crater morphology. © 2003 American Vacuum Society.
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61.80.Fe Electron and positron radiation effects
61.82.Bg Metals and alloys
68.35.Dv Composition, segregation; defects and impurities
68.47.De Metallic surfaces
68.35.Rh Phase transitions and critical phenomena
64.70.D- Solid-liquid transitions
61.85.+p Channeling phenomena (blocking, energy loss, etc.)

Effects of pretreatment on the performance of diamond-coated cemented carbide cutting tools

Qiang Wang, Qing Zhang, S. G. Wang, S. F. Yoon, J. Ahn, Biaoqin Zhao, W. Z. Tang, J. Q. Miao, and F. X. Lu

J. Vac. Sci. Technol. A 21, 1939 (2003); http://dx.doi.org/10.1116/1.1619419 (4 pages) | Cited 1 time

Online Publication Date: 10 October 2003

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We studied the cutting performance of diamond-coated cemented carbide cutting tools pretreated using acid etching, Murakami reagent etching, interlayer addition, and boronization techniques. The Rockwell indentation test indicates that the best adhesion is obtained from the diamond-coated cutting tool pretreated using boronization by forming a boronized cobalt compound layer composed of CoW2B2, CoWB, and CoB. The end-milling test shows that this sample exhibits the longest lifetime among diamond-coated cutting tools, 26-times longer than that of the uncoated cutting tool. The wearing mechanism of the cutting tools used is also discussed. During the milling period, the failure of the diamond-coated tool pretreated by boronization was dominated by how the diamond grains were gradually removed from the diamond coating by the workpiece scraps, instead of the peeling off of the diamond coating. This also reveals that the diamond coating exhibits good adhesion and cutting performance. © 2003 American Vacuum Society.
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81.05.U- Carbon/carbon-based materials
81.05.Mh Cermets, ceramic and refractory composites
81.40.Pq Friction, lubrication, and wear
62.20.Qp Friction, tribology, and hardness
81.65.Cf Surface cleaning, etching, patterning
68.35.Np Adhesion
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
68.35.Gy Mechanical properties; surface strains
62.20.M- Structural failure of materials

Comprehensive perspective on the mechanism of preferred orientation in reactive-sputter-deposited nitrides

Yuya Kajikawa, Suguru Noda, and Hiroshi Komiyama

J. Vac. Sci. Technol. A 21, 1943 (2003); http://dx.doi.org/10.1116/1.1619414 (12 pages) | Cited 28 times

Online Publication Date: 14 October 2003

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Texture control of sputter-deposited nitride films has provoked a great deal of interest due to its technological importance. Despite extensive research, however, the reported results are scattered and discussions about the origin of preferred orientation (PO) are sometimes conflicting, and therefore controversial. The aim of this study is to acquire a clear perspective in order to discuss the origin of PO of sputter-deposited nitrides. Among nitrides, we focus on titanium nitride (TiN), aluminum nitride (AlN), and tantalum nitride (TaN), which are three commonly used nitrides. First, we collected reported experimental results about the relation between operating conditions and PO, because PO is considered to be determined by film formation processes, such as surface diffusion or grain growth, which is affected by operating conditions. We also collected reported results about such PO-determining processes. Then, we categorized the PO-determining processes into an initial stage and a growth stage of film deposition, and further categorized each stage into a vapor–solid interface and a solid–solid interface. Then, we related each stage and interface to film morphology and to PO-determining processes. Finally, based on existing results, previous models, and proposed schema, we discuss the origin of PO. Based on previous experimental results on film morphology, PO of nitride films occurred in the growth stage at the vapor–solid interface, where the sticking process of the precursor and the surface diffusion process determine PO, rather than in the initial stage and in the growth stage at the solid–solid interface. TiN (002) PO, however, seems to be caused in the initial stage at the solid–solid interface. © 2003 American Vacuum Society.
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68.55.-a Thin film structure and morphology
81.15.Cd Deposition by sputtering
68.35.Fx Diffusion; interface formation
68.35.B- Structure of clean surfaces (and surface reconstruction)

Characteristics of C4F8 plasmas with Ar, Ne, and He additives for SiO2 etching in an inductively coupled plasma (ICP) reactor

Xi Li, Li Ling, Xuefeng Hua, Gottlieb S. Oehrlein, Yicheng Wang, and H. M. Anderson

J. Vac. Sci. Technol. A 21, 1955 (2003); http://dx.doi.org/10.1116/1.1619420 (9 pages) | Cited 14 times

Online Publication Date: 14 October 2003

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We have characterized the effect of adding Ar, Ne, and He noble gases to C4F8 inductively coupled plasmas for SiO2 etching. The systematic variation of their ionization potentials, metastable energy levels, and mass of the dominant ion in C4F8/X% discharges (X=He, Ne, or Ar) containing a high percentage of the noble gas provides a means to evaluate the relative importance of gas phase and surface processes in the etching of SiO2. The total ion flux, ion composition, FC deposition and etching rates, and composition of the surface reaction layer formed on Si or SiO2 in these discharges show systematic differences as a function of process parameters because of the different electron impact ionization thresholds for Ar, Ne, and He gases, and differences in the mass of the dominant ion for discharges containing a large proportion of the noble gas. For given experimental conditions (600 W and 20 mTorr for most of this work), Ar addition gives rise to the largest ion current density, and He to the smallest ion current density. When the noble gases are added to C4F8, the Ar+ ion flux contributes the largest percentage and He+ the smallest percentage of the total ion flux for the same dilution of C4F8 with the noble gases. Ion compositional analysis shows that CF+, CF3+, and CF2+ are the dominant ionic fluorocarbon (FC) species (in order of importance), and that they show similar trends as a function of added Ar, Ne, and He percentage. The fluxes of the more highly dissociated C+, F+, and SiFx+/COFx+ ions are greater when Ne and He are added to C4F8 than for Ar addition. Ion energy distributions of all ions are displaced to lower energies for C4F8/Ar discharges as compared with C4F8/Ne or C4F8/He plasmas. Infrared laser absorption spectroscopy was used to determine absolute densities of neutral CF, CF2, and COF2 radical species as a function of gas composition. The densities of CF2 and COF2 radical species were enhanced when Ne and He were added to C4F8 in comparison to Ar addition. Fluorocarbon deposition rates on unbiased Si substrates were measured and greater for C4F8 discharges with Ne or He additives than when Ar was added. Upon rf biasing of the substrates, the ion energies required for etching to take place are lowest for C4F8/Ar discharges, followed by C4F8/He and C4F8/Ne discharges. A comparison of x-ray photoelectron spectra of SiO2 surfaces exposed to C4F8/X% discharges at −10 V self-bias voltage shows pronounced differences in the chemical bond distribution of fluorocarbon films which can be explained by differences in momentum transfer to the surface and the associated bond breaking of deposited fluorocarbon layers on the surface. A comparison of SiO2 and Si etching rates in C4F8/X% discharges shows that for C4F8/Ne discharges containing more than 70%Ne the highest SiO2/Si but lowest SiO2/resist etching rate ratio is obtained. © 2003 American Vacuum Society.
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52.77.Bn Etching and cleaning
81.65.Cf Surface cleaning, etching, patterning
68.35.Dv Composition, segregation; defects and impurities
68.47.Gh Oxide surfaces
34.80.Gs Molecular excitation and ionization
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)

Fluorinated amorphous carbon thin films: Analysis of the role of the plasma excitation mode on the structural and mechanical properties

L. Valentini, M. C. Bellachioma, S. I.-U. Ahmed, G. Bregliozzi, Y. Gerbig, H. Haefke, L. Lozzi, S. Santucci, and J. M. Kenny

J. Vac. Sci. Technol. A 21, 1964 (2003); http://dx.doi.org/10.1116/1.1621402 (7 pages) | Cited 3 times

Online Publication Date: 14 October 2003

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The effects of pulsed plasma enhanced chemical vapor deposition on the thermally induced gas effusion characteristics of fluorinated amorphous carbon thin films are investigated. The main contributions to the effusion spectra are found to come from hydrogen, hydrocarbons, and CF4. With a plasma excitation frequency of 10−3 s, the film produced is relatively compact and the effusion of hydrogen-related species dominate. A strong change in the effusion characteristics for the highest on-time plasma excitation (10−1 s) indicates that an interconnected network of voids is present. Strong effusion of CF4 related species is in fact found to be consistent with a surface desorption process and can only be observed when the void network dimensions are large enough. Nanoindentation measurements showed increased elasticity of the film, as well as increased hardness upon reduction of the plasma excitation period. Raman spectroscopy was applied to corroborate the effusion results, indicating a structural transition from diamond-like to polymer-like film with an increase in the plasma excitation period. Finally the microtribological properties of such types of films are presented and discussed. © 2003 American Vacuum Society.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.05.U- Carbon/carbon-based materials
68.55.-a Thin film structure and morphology
68.60.Bs Mechanical and acoustical properties
52.77.Dq Plasma-based ion implantation and deposition
64.70.K- Solid-solid transitions
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
68.43.Mn Adsorption kinetics
78.35.+c Brillouin and Rayleigh scattering; other light scattering
61.43.-j Disordered solids
61.72.Qq Microscopic defects (voids, inclusions, etc.)
62.20.M- Structural failure of materials
62.20.Qp Friction, tribology, and hardness
68.35.Gy Mechanical properties; surface strains
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.D- Elasticity
81.40.Jj Elasticity and anelasticity, stress-strain relations
81.40.Pq Friction, lubrication, and wear

Spatially resolved mass spectrometric sampling of inductively coupled plasmas using a movable sampling orifice

Xi Li, Gottlieb S. Oehrlein, Marc Schaepkens, Robert E. Ellefson, and Louis C. Frees

J. Vac. Sci. Technol. A 21, 1971 (2003); http://dx.doi.org/10.1116/1.1619413 (7 pages) | Cited 7 times

Online Publication Date: 15 October 2003

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A quadrupole mass spectrometer equipped with a special sampling tube and positioned on a linear-motion table is shown to be capable of obtaining important information on the variation of the discharge properties with position. We measured signals obtained by post-ionization of species sampled from Ar and C2F6 high-density plasmas using electron ionization energies of 30 and 16 eV. The variation of the ion signal with position of the sampling orifice inside the reactor provides evidence of the spatial nonuniformity of the discharge and the processes that control these variations. For Ar discharges we show evidence of gas heating which produces a nonuniform radial distribution of the neutral species. The neutral species are depleted in the center of the discharge due to plasma heating. The neutral gas temperature that can be extracted from the variation in density is consistent with temperature measurements using spectroscopic probes. We also monitored the intensity of different fluorocarbon ions as a function of sampling position. We find that the fluorocarbon mass spectrometer signals show qualitatively different dependencies on sampling position. For instance, the CF2+ signal increases towards the center of the discharge and decreases towards the wall of the chamber, whereas the CF3+ signal shows a maximum near the reactor wall. The CF3+ signal also grows as the wall temperature increases, indicating production at the wall. The application of this setup to spatially resolved monitoring of etching and deposition processes is also described. © 2003 American Vacuum Society.
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52.70.Nc Particle measurements
07.75.+h Mass spectrometers
52.25.-b Plasma properties

Radical detection in a methane plasma

H. D. Kang and V. Dose

J. Vac. Sci. Technol. A 21, 1978 (2003); http://dx.doi.org/10.1116/1.1621405 (3 pages) | Cited 3 times

Online Publication Date: 15 October 2003

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We present a method for detecting and quantifying the concentration of free radicals produced in a low temperature methane process plasma employing quadrupole mass spectrometry and Bayesian analysis. The latter includes a model comparison to determine species expected in the plasma and a parameter estimation of their concentrations and cracking coefficients. We find that the neutral mass spectra are best explained by incorporating the neutral molecules H2, CH4, C2H2, C2H4, and C2H6 as well as the radicals H, CH3, and C2H5 into the model. © 2003 American Vacuum Society.
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52.70.-m Plasma diagnostic techniques and instrumentation
82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

Experimental and computer simulation studies of the “baffled target” reactive sputtering process

F. Engelmark, J. Westlinder, T. Nyberg, and S. Berg

J. Vac. Sci. Technol. A 21, 1981 (2003); http://dx.doi.org/10.1116/1.1619418 (7 pages) | Cited 2 times

Online Publication Date: 23 October 2003

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Reactive sputtering is a technique widely employed for deposition of compound materials. One drawback encountered with this technique is that the target normally ends up in poisoned mode at reactive gas flow levels necessary for depositing a stoichiometric film, causing a severe drop of the deposition rate. To decrease the target poisoning a reactive sputter deposition technique based on the so-called baffled target has been suggested. In this configuration a target is confined in a box having a front aperture allowing sputtered material to be deposited through the aperture onto the substrate located in the main chamber. The purpose of this box is to separate the reactive gas in the chamber from the target thereby decreasing the target poisoning. We have carried out computer simulations as well as experimental studies on the baffled target technique. The computer simulations serve to explain the reactive gas gettering and the corresponding process behavior in the box and in the chamber, respectively. The calculations also assist in finding optimum operating conditions for this novel technique. It was found that it is possible to find operating conditions where compound film formation is achieved with the target in high rate metal mode at a supply level of reactive gas far below the level required to reach the hysteresis region. This is a unique property of the baffled target technique that may not be obtained in traditional reactive sputtering system configurations. © 2003 American Vacuum Society.
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81.15.Cd Deposition by sputtering
85.40.Sz Deposition technology

Ion energy distributions and the density of CH3 radicals in a low pressure inductively coupled CH4/H2 plasma used for nanocrystalline diamond deposition

Katsuyuki Okada, Shojiro Komatsu, and Seiichiro Matsumoto

J. Vac. Sci. Technol. A 21, 1988 (2003); http://dx.doi.org/10.1116/1.1621404 (5 pages) | Cited 6 times

Online Publication Date: 23 October 2003

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Ion energy distributions (IEDs) and the density of CH3 radicals (n) in a 13.56 MHz radio frequency (rf) low pressure inductively coupled CH4/H2 plasma used for nanocrystalline diamond deposition have been investigated with a quadrupole mass spectrometer. The energy distributions of positive ions were measured in a CH4/H2 plasma with 50 mTorr of the gas pressure at 500 W of the plasma input power, and were compared with those of an Ar plasma. We have found that the IEDs of Ar+, CH4+, and C2H5+ have a nearly monoenergetic peak, and a hump due to a small degree of capacitive coupling. The plasma potentials obtained from the peaks are consistent with the previously reported values measured with a Langmuir probe. On the other hand, the IEDs of H+, H2+, and H3+ have a clear asymmetric double peak due to the modulation of rf driven glow discharge. The n monotonously increases with increasing pressure. The n indicates that CH3 radicals are main precursors for the growth of nanocrystalline diamond. The estimated sticking coefficient of the CH3 radical is comparable with the reported value. © 2003 American Vacuum Society.
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52.77.Dq Plasma-based ion implantation and deposition
52.70.Nc Particle measurements
52.80.Hc Glow; corona

Effects of CF4 addition on oxygen contamination of SiC films in hot filament chemical vapor deposition using CH4+SiH4+H2

Guoju Wang, Bo Wang, Anping Huang, Mankang Zhu, Biben Wang, and Hui Yan

J. Vac. Sci. Technol. A 21, 1993 (2003); http://dx.doi.org/10.1116/1.1622674 (3 pages) | Cited 2 times

Online Publication Date: 23 October 2003

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The contamination of unwanted atoms such as oxygen that may originate from residual gas in reactant chambers is common in the deposition of SiC films. In this study, CF4 was introduced into a chamber while preparing SiC films by hot filament chemical vapor deposition using CH4, SiH4, and H2, and then the films were characterized by Fourier transform infrared (FTIR) spectrometer and x-ray photoelectron spectrometry (XPS). The FTIR and XPS results showed that the CF4 addition could reduce the oxygen content in the films. It is concluded that the reduction of oxygen is due to the reaction of active F∗ (or CFn∗), O∗, Si∗ (or SiHn∗), and C∗ (or CHn∗) in the process. Simultaneously, the results indicate also that the addition of CF4 could improve the degree of ordering of the Si–C bonds and lead to a decrease in the growth rate. The influence of CF4 addition on the ordering of the Si–C bonds and the growth rate of the films is discussed. © 2003 American Vacuum Society.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.-a Thin film structure and morphology
68.35.Dv Composition, segregation; defects and impurities
81.05.Hd Other semiconductors
78.30.Hv Other nonmetallic inorganics
78.66.Li Other semiconductors
79.60.Dp Adsorbed layers and thin films

Characterization of nonstoichiometric TiO2 and ZrO2 thin films stabilized by Al2O3 and SiO2 additions

Dong-Hau Kuo, Kuo-Hwa Tzeng, and Chi-Hung Chien

J. Vac. Sci. Technol. A 21, 1996 (2003); http://dx.doi.org/10.1116/1.1622675 (7 pages) | Cited 3 times

Online Publication Date: 24 October 2003

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Thin films of nonstoichiometric titanium dioxide (TiO2) and zirconium oxide (ZrO2) chemically stabilized by incorporating stoichiometric oxides of Al2O3 and SiO2, respectively, were fabricated by rf magnetron sputtering. These films deposited from ceramic targets of TiO2, TiO2–10 vol %Al2O3, ZrO2, and ZrO2–10 vol %SiO2 were designated as TiO2, TiO2–10Al2O3, ZrO2, and ZrO2–10SiO2. The dielectric and electrical properties of as-deposited and annealed TiO2 and ZrO2 films varied with the processing conditions. The addition of Al2O3 to TiO2 and SiO2 to ZrO2 films had not only reduced the dielectric loss tangent (tan δ) and increased resistivity, but also retained the competitive dielectric constant (k). The dielectric properties of the TiO2–10Al2O3 and ZrO2–10SiO2 films became stable under different deposition temperatures and annealing temperatures. The TiO2–10Al2O3 films with k=62, tan δ=0.012, resistivity of 2.5×108 Ω cm, and breakdown field of 2.2 MV/cm were obtained. ZrO2–10SiO2 films with good k values of 20–25 and low tan δ values of 0.011–0.014 can be obtained under rf power of 150 W, while k=14.5–16.4 and tan δ=0.012–0.019 under 100 W can be obtained. The advantage of adding the stoichiometric oxides of Al2O3 and SiO2 is the reduction of oxygen vacancies through the strong affinity of Al3+ and Si4+ to capture more oxygen for nonstoichiometric oxides of TiO2 and ZrO2. © 2003 American Vacuum Society.
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68.55.Nq Composition and phase identification
77.55.-g Dielectric thin films
81.15.Cd Deposition by sputtering
73.61.Ng Insulators
61.72.Cc Kinetics of defect formation and annealing
77.22.Ch Permittivity (dielectric function)
77.22.Gm Dielectric loss and relaxation
77.22.Jp Dielectric breakdown and space-charge effects
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.

Formation and clustering of individual point defects in pure tungsten and its slightly dilute alloys at ion irradiation

A. L. Suvorov, A. G. Zaluzhnyi, V. P. Babaev, and A. A. Zaluzhnyi

J. Vac. Sci. Technol. A 21, 2003 (2003); http://dx.doi.org/10.1116/1.1614273 (4 pages)

Online Publication Date: 27 October 2003

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Results of field-ion microscopy investigations of formation and clustering of vacancies among themselves and intrinsic interstitial atoms with impurity atoms in tungsten and its slightly diluted alloys at irradiation by In+ or Yb+ ions of 25 keV energy and Ar+, Ni+, or Cr+ ions of 35 keV energy are presented. Distributions of vacancies complexes in irradiated samples over the number of individual vacancies associated in them have been obtained and analyzed. The noticeable difference of such distributions in areas of development of atomic displacement cascades (in depleted zones) and outside these areas has been revealed. Specific features of the distribution of identified complexes “intrinsic interstitial atom—impurity atom” (in the dumbbell configuration) over the volume of irradiated samples have been studied. The correlation between the type and concentration of components in alloys and concentration of these complexes (dumbbells) as well as dimensions and parameters of depleted zones has been established. The theoretical analysis of experimentally obtained regularities from the positions of the concept of the rupture of chains of focused replacing collisions on impurities has been carried out. Average values of chain lengths in samples with different levels and types of impurities have been measured indirectly. Effectiveness of capture of intrinsic interstitial atoms by various impurities in tungsten has been evaluated from these results. © 2003 American Vacuum Society.
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61.72.Yx Interaction between different crystal defects; gettering effect
61.82.Bg Metals and alloys
61.80.Jh Ion radiation effects
61.72.J- Point defects and defect clusters

Effects of air exposure on ion beam assisted TiN:O coatings to prevent multipactor

S. I. Castañeda, N. Díaz, D. Raboso, I. Montero, L. Galán, and F. Rueda

J. Vac. Sci. Technol. A 21, 2007 (2003); http://dx.doi.org/10.1116/1.1621403 (6 pages) | Cited 1 time

Online Publication Date: 27 October 2003

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Titanium nitride films are used to prevent “multipactor” plasma in rf devices due to their low secondary electron emission coefficient (σ) in ultrahigh vacuum. This work refers to the increase of this coefficient on exposure to air and the effect of ion beam assisted deposition (IBAD) on its recovery, relevant in components for space applications. Two modes of deposition were compared: a simple sublimation of titanium in nitrogen atmosphere and a low energy (200 eV-Ar+) IBAD. The sample characterization included σ, bulk and surface compositions, by energy dispersive analysis of x rays and x-ray photoelectron spectroscopy, structure, and resistivity. When the coatings were clean they presented a low value of σ, which increases after exposure to air and recovers part of its low value by electron irradiation in ultrahigh vacuum. In IBAD samples recovery in σ, surface nitrogen content and stability were higher than in simple sublimation ones, leading to values of σ closer to one. After weeks in air, the aluminum microwave guide elements coated with IBAD TiN:O showed a “multipactor” threshold power three times higher than those coated with non-IBAD TiN:O. The coatings’ resistivities lay in the 1–7 μΩ m range. © 2003 American Vacuum Society.
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68.55.-a Thin film structure and morphology
68.55.Nq Composition and phase identification
81.15.Jj Ion and electron beam-assisted deposition; ion plating
79.60.Dp Adsorbed layers and thin films
68.35.Dv Composition, segregation; defects and impurities
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