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Nov 1973

Volume 10, Issue 6, pp. 909-1153


On Electron Projection Systems

H. Koops

J. Vac. Sci. Technol. 10, 909 (1973); http://dx.doi.org/10.1116/1.1318513 (4 pages) | Cited 2 times

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Demagnifying EPS have the capacity to generate as much as 5000 line pairs per diameter at a resolution as small as 0.1 μ. The diameter of the recorded image and the maximum number of line pairs per diameter decrease with increasing values of the chromatic field aberrations of the lens system, and with increasing relative energy width of the electron beam. The optimum aperture yielding maximum probe current at a given resolution and image field diameter depends mainly on the value of the coefficients of image curvature and isotropic and anisotropic astigmatism of the lens system.
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41.85.-p Beam optics

X-Ray Lithography: A Complementary Technique to Electron Beam Lithography

Henry I. Smith, D. L. Spears, and S. E. Bernacki

J. Vac. Sci. Technol. 10, 913 (1973); http://dx.doi.org/10.1116/1.1318514 (5 pages) | Cited 11 times

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X-ray lithography provides a means of replicating, in a single large-area exposure, submicron linewidth patterns made by scanning electron beam lithography. The technique is complementary to existing electron beam technology, and provides a number of unique advantages: (i) it is simple and inexpensive; (ii) the penetrating character of x-rays makes it relatively insensitive to contamination; (iii) both positive and negative type resists can be used; and (iv) because of the absence of backscattering effects, both positive and negative type patterns can be made with equal facility. Exposure times of seven minutes have been achieved for 3 μ mask-sample gaps. This can be decreased to less than one minute by using a rotating anode, or by reducing the mask-sample gap. The most recent results in x-ray lithography are reported, including the fabrication of surface wave devices. The elements of a multiple-mask alignment system are described. This system should permit the rapid and automatic superposition on a substrate of patterns from several different masks, to a precision of 1∕10 μ.
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85.40.Hp Lithography, masks and pattern transfer

Influence of Source Parameters on the Properties of an Ion Beam

K. Wittmaack and F. Schulz

J. Vac. Sci. Technol. 10, 918 (1973); http://dx.doi.org/10.1116/1.1318515 (4 pages) | Cited 2 times

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Beam profile measurements have been carried out to study the influence of the length of the ion source outlet, the source pressure, and the source magnetic field on the properties of an ion beam. From a variation of the outlet length conditions can be deduced for optimum design with respect to gas efficiency and profile shape. The profile width is found to decrease with increasing source pressure and decreasing magnetic field. This effect is attributed to a corresponding change in the energy distribution of the ions. Profile distortions occurring at high source pressure are likely to be due to ion scattering in the extraction region.
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41.75.Ak Positive-ion beams
07.77.Ka Charged-particle beam sources and detectors

Design and Operation of an Intense Neutral Beam Source

K. W. Ehlers, W. R. Baker, K. H. Berkner, W. S. Cooper, W. B. Kunkel, R. V. Pyle, and J. W. Stearns

J. Vac. Sci. Technol. 10, 922 (1973); http://dx.doi.org/10.1116/1.1318516 (4 pages) | Cited 21 times

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We describe a neutral beam source capable of producing pulsed deuterium beams of up to 15 A equivalent current at 20 keV for heating and sustaining fusion plasmas. It consists of a large-area plasma source, multiple-aperture accel-decel extractor, and closely coupled charge-exchange cell. A larger source, to produce 80 A equivalent deuterium beams at 20 keV, is being constructed.
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07.77.Gx Atomic and molecular beam sources and detectors

Recent Advances in Electron Beam Recording

Patrick F. Grosso and Andrew A. Tarnowski

J. Vac. Sci. Technol. 10, 926 (1973); http://dx.doi.org/10.1116/1.1318517 (6 pages)

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This article describes recent advances in electron-beam recorders (EBR) which utilize the inherent flexibility of electron beams and computer control for a variety of applications such as remote sensor imagery, computer micrographics, microelectronics, and other high resolution digital and analog imagery. These advanced electron beam recorders can be used on-line with computers or remote sensors, or off-line with analog or digital magnetic tape inputs, in a variety of scanning modes using computer control.
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85.90.+h Other topics in electronic and magnetic devices and microelectronics (restricted to new topics in section 85)

Study of a Glow Discharge Ion Source

J. P. Flemming

J. Vac. Sci. Technol. 10, 932 (1973); http://dx.doi.org/10.1116/1.1318518 (4 pages)

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Some properties of a glow discharge source in which boron trifluoride was used as a source feed-gas are described. The source generated a beam with a multipeaked energy spread with width approximately equal to the voltage used to generate the discharge (up to several kilovolts). The energy distributions of different ion species extracted from the source were not all the same and, in particular, the section of the beam taken from an energy band situated a few hundred volts above cathode potential was found to consist essentially of boron ions. Beryllium ions were observed to be generated close to the cathode of the source from atoms sputtered from the extraction canal. The highest total output current of the source was 100 μA.
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07.77.Ka Charged-particle beam sources and detectors

Optical Waveguides Fabricated by Ion Implantation

S. Namba, H. Aritome, T. Nishimura, K. Masuda, and K. Toyoda

J. Vac. Sci. Technol. 10, 936 (1973); http://dx.doi.org/10.1116/1.1318519 (5 pages) | Cited 3 times

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Optical waveguides are formed by implantation of various ions (H+, H2+, He+, Li+, and B+) in fused quartz and the properties of mode propagation are investigated at 6328 Å. The origin of the refractive index change is discussed from the ESR measurement. The depth distribution of defects is measured by ESR measurements and the effective thickness of the high-refractive index region is estimated from the measured depth distribution of defects. In as-implanted samples, the propagation loss decreases with decreasing fluence, but a minimum fluence is required for a given implantation energy for the lowest mode to be propagated. The propagation loss is explained to be internal absorption due to color centers introduced by ion implantation. It is shown that the propagation losses are different for various implanted ions. Annealing behavior of the propagation loss and the refractive index change is also presented.
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42.82.Et Waveguides, couplers, and arrays

Modulation of the Optical Guided Wave by uv Light and Electron Beam Excitations

Koichi Toyoda, Susumu Namba, Toshiaki Matsui, and Yoshio Suge

J. Vac. Sci. Technol. 10, 941 (1973); http://dx.doi.org/10.1116/1.1318520 (3 pages) | Cited 1 time

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An effective modulation of a He–Ne laser beam at a wavelength of 6328 Å guided in a semiconductor ZnS thin film has been obtained when the guided wave travels transversely across the region irradiated by intense uv light. This seems to be caused by the absorption effect by means of the optically excited free carriers. The modulation ratio has shown monotonic increase with the excitation intensity. At maximum excitation, a modulation ratio of 35% was obtained. For normal transmission of a laser beam through the excited shallow region near the surface, measurements of reflectance change and phase retardation have been also carried out under uv light and pulsed electron excitations, are discussed in connection with the absorption effects by the free carriers generated by these excitations. In the case of excitation by an electron beam of 15 mA and 30 kV, the fractional increase of the absorption was 1×10−3.
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42.79.Gn Optical waveguides and couplers

Ion Implanted N-Type Resistors on High-Resistivity Substrates

J. W. Hanson, R. J. Huber, and J. N. Fordemwalt

J. Vac. Sci. Technol. 10, 944 (1973); http://dx.doi.org/10.1116/1.1318521 (4 pages) | Cited 1 time

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The method of fabrication and measured characteristics of phosphorous ion-implanted resistors made on high-resistivity 15–20 Ω cm p-type silicon substrates are presented. The process included a shallow boron-implanted layer at the surface to prevent surface inversion due to Qss. It is demonstrated that enhancement N-channel MOSFET devices can be processed together with the implanted resistors. The range of phosphorous doses studied was 1×1012–5×1014∕cm2 and the range of anneal temperatures considered was 500–950 °C. Results are given for measurements of sheet resistivity vs dose and anneal temperature, and for temperature coefficient of resistance. The advantages of using high-resistivity substrates for the implanted resistors are discussed.
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85.30.De Semiconductor-device characterization, design, and modeling
87.85.Ng Biological signal processing

Generation of Picosecond Pulse Electron Beams

K. Ura and N. Morimura

J. Vac. Sci. Technol. 10, 948 (1973); http://dx.doi.org/10.1116/1.1318522 (3 pages) | Cited 3 times

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Picosecond pulse electron beams were generated by means of a transverse-type gate and a buncher. The 20 keV beam was deflected by a 1 GHz symmetrical reentrant cavity and chopped by a slit into several tens picosecond pulses. These pulses were bunched by a 4 GHz reentrant cavity. The pulsed beam was then deflected by the other 1 GHz x–y deflectors and finally reached the screen, where the pulse width was measured by comparing the lengths of two chopped arcs with that of the unchopped full circle. A minimum pulse width of 6 psec was recorded. It was observed that as the deflecting voltage of the transverse gate increases, the pulse width decreases at first, reaches a minimum, and then increases. This can be explained by the longitudinal velocity modulation due to the fringing field of the deflector. When the beam chopped by the transverse gate was injected to the longitudinal gate, the maximum phase compression ratio was less than 5; this is also explained by the above-mentioned effect.
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41.75.Fr Electron and positron beams
07.77.Ka Charged-particle beam sources and detectors

Holographic Measurements of the Plasmas in a High-Current Field Emission Diode

L. P. Mix, J. G. Kelly, G. W. Kuswa, D. W. Swain, and J. N. Olsen

J. Vac. Sci. Technol. 10, 951 (1973); http://dx.doi.org/10.1116/1.1318523 (3 pages) | Cited 18 times

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Two-exposure holographic interferometry has been employed to obtain the first quantitative measurements of the plasma densities in an intense electron beam diode. Several diode configurations which produce an intense pinch of the electron beam at the anode plane have been investigated. Holograms indicating the temporal and spatial evolution of the plasmas in these diodes are presented. Two types of plasmas are observed in these diodes: a lower density plasma (< 1018∕cm2) with a velocity of 5–10 cm∕μsec and a higher density plasma (> 1018∕cm3) with a velocity of about 2 cm∕μsec. Preliminary analysis indicates that the lower density plasma plays a dominant role in determining the primary beam dynamics.
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85.45.Bz Vacuum microelectronic device characterization, design, and modeling
52.70.Kz Optical (ultraviolet, visible, infrared) measurements

Simulation of Relativistic Electron Beam Diodes

J. W. Poukey, J. R. Freeman, and G. Yonas

J. Vac. Sci. Technol. 10, 954 (1973); http://dx.doi.org/10.1116/1.1318524 (5 pages) | Cited 14 times

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Program DISIC, a new diode simulation code, has been developed to study the behavior of high ν∕γ diodes. The code is based on a two-dimensional finite-size particle simulation model, and is designed to provide good resolution of small anode-cathode gaps. Results are shown which (i) compare with earlier calculations, (ii) compute electron trajectories in strongly self-pinched diodes, and (iii) compute electron trajectories for a diode having a conical cross section.
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52.59.Mv High-voltage diodes

Compression and Stability Studies of High ν∕γ Beams

Charles Stallings, Richard Schneider, and James Benford

J. Vac. Sci. Technol. 10, 959 (1973); http://dx.doi.org/10.1116/1.1318525 (2 pages) | Cited 1 time

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Intense electron beams are of increasing interest in controlled fusion research. Such beams exhibit several phenomena which suggest strong coupling between the beam and the background plasma via beam-generated electromagnetic fields. Observations of beam compressibility and distortion in inhomogeneous fields are reported.
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41.75.Ht Relativistic electron and positron beams

The Gamble I Pulsed Electron Beam Generator

G. Cooperstein, J. J. Condon, and J. R. Boller

J. Vac. Sci. Technol. 10, 961 (1973); http://dx.doi.org/10.1116/1.1318526 (4 pages) | Cited 14 times

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The Gamble I pulsed electron beam generator at NRL recently has undergone several major modifications. The modified generator has a nominal output into a matched 1.5-Ω load of 500 kA at 750 keV, with an 70-nsec (FWHM) pulse length and a 20-nsec (10%–90%) voltage risetime. The distinguishing characteristics of low prepulse (< 1%) and high reproducibility in output voltage and current (± 3%) result primarily from conversion from operation with self-breakdown water switches to operation with triggered high-pressure gas switches. Fast pulse risetime was maintained by using a low-inductance multichannel triggered output switch in conjunction with a new low-inductance vacuum diode with a radial insulator.
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07.77.Ka Charged-particle beam sources and detectors

The Beam Optics Design of Pulsed, Large Area Electron-Beam Accelerators in the 150–300 kV Range

W. A. Frutiger, J. R. Uglum, B. S. Quintal, and S. V. Nablo

J. Vac. Sci. Technol. 10, 965 (1973); http://dx.doi.org/10.1116/1.1318527 (3 pages)

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We have modified the design of our commercial “Electrocurtain” electron-beam accelerators to provide for pulsed, medium current-density beams (10–30 mA∕cm2) with a total output beam-area in the range of 1000–1500 cm2. Two different approaches to the design of such systems are presented. In the first approach, a cylindrically symmetric geometry is employed, with the cathode extending along the symmetry axis (typically 1-m long). Beam expansion to the desired output area is dominated by the electric fields in the coaxial accelerating gap. For the second approach, several short cathodes span the short dimension of the output window and are evenly spaced along the long dimension of the window. Beam expansion is achieved in a field-free region. In both cases, the beam current is provided by cylindrically divergent Pierce-type diodes fitted with barium-dispenser cathodes. This design allows for grid control of the output current independent of the main accelerating voltage. Computer simulations of the beam flow will be discussed.
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07.77.Ka Charged-particle beam sources and detectors
41.75.Lx Other advanced accelerator concepts
41.85.-p Beam optics

Transformer Type Accelerator—Compact Sources of Energetic Electrons

G. K. Simcox and C. J. Schubert

J. Vac. Sci. Technol. 10, 968 (1973); http://dx.doi.org/10.1116/1.1318528 (4 pages)

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A family of electron accelerators is described which derives its relatively small dimensions from the dielectric strength advantages of a pulsed voltage mode and from advanced concepts of electron beam transport.
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07.77.Ka Charged-particle beam sources and detectors
41.75.Lx Other advanced accelerator concepts
41.85.-p Beam optics

Optimization of the Performance of High-Brightness Electron Guns

H. Ahmed and E. Munro

J. Vac. Sci. Technol. 10, 972 (1973); http://dx.doi.org/10.1116/1.1318529 (3 pages) | Cited 6 times

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The optimization of the performance of a high-brightness electron gun requires the correct choice of material, and LaB6 has been shown to have advantages over pure metal emitters. The finely pointed tip must be accurately positioned in the grid aperture to achieve maximum brightness and the electrode positions must be maintained if the benefits of improved stability are to be realized. The brightness is measured using two apertures to define the beam and a Faraday cage to collect the current. The increased brightness is confirmed by the improved performance of the scanning electron microscope. However emission peaks have been detected under certain conditions of operation and appear to depend strongly on the position of the tip with respect to the Wehnelt. The design of this electrode has been considerably modified to a conical shape to try and achieve high brightness while suppressing some of the emission peaks. For a range of gun geometries and electrode potentials, the potential distribution near the tip and Wehnelt aperture has been computed using the finite element method. This computes the potential at points on a two-dimensional mesh, whose shape can be varied at will, which permits analysis of complex electrode configurations. Very small tip radii can be allowed for with an accurate determination of the tip field. From the tip field the electron trajectory can be computed using a “model” field near the tip and solving the paraxial ray equation from there onwards. It is observed that under certain conditions of operation a virtual crossover is obtained with pointed tip electron guns. The conditions under which Schottky enhanced emission may be present are also obtained and the emitting area of the cathode can be estimated.
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07.77.Ka Charged-particle beam sources and detectors

Potential of Field Emission Cathodes for Microfabrication

G. A. Wardly

J. Vac. Sci. Technol. 10, 975 (1973); http://dx.doi.org/10.1116/1.1318530 (4 pages) | Cited 1 time

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For field-emitter tip currents in the range of 100 μA, field-emission guns can compete favorably with thermionic LaB6 guns for microfabrication with 2000 Å working beam diameters. The stable operation of tip currents between 10 and 1000 μA, for periods totalling hundreds of hours, requires an understanding of the steady-state and transient adsorbed gas layer on the emitter surface. This has been accomplished in a simple gun-lens. Furthermore, Boersch effect energy broadening appears to be significantly operative at emission intensities on the order of 10−2 A∕sr. The staircase-like current fluctuations indicate quantum events on the emitter surface. In fact, intense emission lobes have been spatially separated by spherical aberration in a large aperture configuration.
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85.45.Db Field emitters and arrays, cold electron emitters

A New High-Resolution Electron Probe

A. N. Broers

J. Vac. Sci. Technol. 10, 979 (1973); http://dx.doi.org/10.1116/1.1318531 (4 pages) | Cited 8 times

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A new high-resolution electron probe has been built for scanning microscopy studies. The probe has a final lens with a focal length of 0.8 mm, a spherical aberration coefficient; of 0.4 mm, and a chromatic aberration coefficient of 0.5 mm. A lanthanum hexaboride cathode is employed with a maximum brightness of 1.5×107 A∕cm2 sr at 75 kV. The cathode operates satisfactorily at a pressure of 10−6 mm Hg. The theoretical minimum beam size for the instrument is 5 Å. Transmission scanning electron micrographs with a beam current of 1×10−12–3×1012 A indicates that close to this value is obtained in practice.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)

Aberration Correction for Increased Lines per Field in Scanning Electron Beam Technology

G. Owen and W. C. Nixon

J. Vac. Sci. Technol. 10, 983 (1973); http://dx.doi.org/10.1116/1.1318532 (4 pages) | Cited 3 times

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The scanned field performance of probe forming systems has been investigated leading to various methods for increasing the current that may be delivered into an electron probe scanning a square field of 104 lines. Programs for evaluating the third-order aberrations of both lenses and single and double deflection systems have been developed. These have been used to evaluate the performance of a typical pre-lens double deflection probe forming system. It is shown that it is possible to produce much better performance using post-lens deflection coils. Distortion, field curvature and astigmatism can be eliminated, using suitable electronics for dynamic correction, and the remaining third-order aberrations may be reduced by careful design of the deflection coils.
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85.40.Hp Lithography, masks and pattern transfer
41.85.Gy Chromatic and geometrical aberrations

High Speed Beam Deflection and Blanking for Electron Lithography

L. H. Lin and H. L. Beauchamp

J. Vac. Sci. Technol. 10, 987 (1973); http://dx.doi.org/10.1116/1.1318533 (4 pages) | Cited 5 times

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A fast magnetic deflection system and beam blanking unit have been incorporated into the electron optical column of a commercial SEM for application to electron lithography. The achieved response-time of the deflection system is about 1 μsec. Double deflection coils are located outside of a glass tube enclosing the electron beam. A thin silver film deposited on the inside surface of the tube serves to conduct charge to ground but does not significantly impede high-frequency deflection fields. A ferrite magnetic shield is placed between the deflection coils and the surrounding iron pole-piece of the objective lens. The function of the shield is to minimize the undesirable eddy currents induced in the iron by the deflection field. The response time of the beam blanking unit is about 10 nsec. The unit employs a pair of electrostatic plates which blank the beam by deflecting the latter against an aperture-stop. The center of deflection of the plates coincides with the crossover point produced by the first condenser lens. Under this condition the beam can be deflected and blanked without affecting the position of the writing spot. The spot position is also insensitive to unequal charging of the contaminated plates by stray electrons. The writing spot position drift, caused by electron charging of other surfaces in the column, has also been minimized by properly restricting the beam width in the column and centering the beam on the final aperture.
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85.40.Hp Lithography, masks and pattern transfer
41.85.Ja Particle beam transport

Generation, Transport, and Compression of an Annular Intense Relativistic Electron Beam with Return Current Feedback through the Cathode

John G. Kelly

J. Vac. Sci. Technol. 10, 991 (1973); http://dx.doi.org/10.1116/1.1318534 (4 pages)

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The properties of an intense annular relativistic electron beam generated by a ring cathode and conical anode have been studied in detail. The beam is injected into a channel between concentric cones (containing a neutral gas for space charge and current neutralization) where it is transported and focused. Half of the return current is then fed back through the cathode to prevent radial pinching of the primary current sheet. On the Sandia Reba accelerator which generated a beam of about 120 kA at 1 MeV an area compression of 10 was achieved with 50% efficiency. The compressability of the beam was found to depend primarily on the azimuthal temperature of the beam as it emerged from the diode and on the diode plasma closure rate.
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41.75.Ht Relativistic electron and positron beams

Molecular Acceleration by Alternate Gradient Focusing

D. Kakati and A. Choudhury

J. Vac. Sci. Technol. 10, 995 (1973); http://dx.doi.org/10.1116/1.1318535 (5 pages)

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Some recent developments show that a neutral-particle accelerator (e.g., a molecular accelerator) can be an important tool not only to the chemical investigator but may also have potential use in an entirely new field namely solid-state device fabrication. Experimental evidence of alternate gradient focusing of neutral particles has already been reported by one of the authors elsewhere. This paper now presents a theoretical analysis and considers the possibilities of extending the work for construction of a neutral-particle accelerator. An ammonia molecular-beam is considered as an example. A particular advantage in this case is that the transported molecular beam can be analyzed in a conventional superheterodyne set up.
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07.77.Gx Atomic and molecular beam sources and detectors

Range and Energy Deposition Enhancement of a Fast Electron Beam by External Electric Fields

C. M. Bowden, J. F. Perkins, and R. A. Shatas

J. Vac. Sci. Technol. 10, 1000 (1973); http://dx.doi.org/10.1116/1.1318452 (5 pages) | Cited 1 time

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The electrode configuration in electron-beam preionized electrical discharge pumped molecular gas lasers can be arranged such that the drift field of the pump accelerates the fast electrons which are concurrently scattered. In designing lasers with output pulses beyond the kJ energy level, one uses the drift field to extend the range and to enhance the energy deposition of the fast electron beam. Although scattering and energy loss of electrons penetrating into matter without an external field is well known, electrical fields of the order of kV cm−1 at atmospheric pressures substantially affect both the range and the energy deposition of the primaries. We report numerical results in range and differential and integral energy deposition enhancement for 100 keV to 2 MeV electron beams in external fields up to 10−16 V cm2 electric field to number density (ϵ∕N) ratio, for Zeff=6 gas mixtures obtained by Monte Carlo calculations of transport of fast electrons in thick absorbers modified to include the effects of an external electrical field applied across the scatterer. Detailed results are given in the form of graphs directly usable by the designer.
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34.80.Gs Molecular excitation and ionization
42.55.Lt Gas lasers including excimer and metal-vapor lasers

Microfabrication using a Computer-Controlled Scanning Transmission

J. J. Kim, H. G. Sampson, and T. E. Everhart

J. Vac. Sci. Technol. 10, 1005 (1973); http://dx.doi.org/10.1116/1.1318453 (3 pages) | Cited 4 times

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Fabrication and inspection of two-dimensional lattice structures in thin polymer films have been carried out using a computer-controlled scanning electron microscope (CCSEM). Periods of 0.2 μ are quite regular, finer resolutions show some irregularities possibly due to film instabilities. Using the CCSEM permits great flexibility, and using thin films eliminates the problem of backscattered electrons from the substrate, which severely limits the resolution of periodic structures fabricated on a solid substrate. These structures should be useful in integrated optics, and may be used as x-ray lithography or evaporation masks.
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81.65.Cf Surface cleaning, etching, patterning
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.37.Ps Atomic force microscopy (AFM)
68.37.Rt Magnetic force microscopy (MFM)
68.37.Uv Near-field scanning microscopy and spectroscopy

Precision Electron Beam Microfabrication

F. S. Ozdemir, W. E. Perkins, R. Yim, and E. D. Wolf

J. Vac. Sci. Technol. 10, 1008 (1973); http://dx.doi.org/10.1116/1.1318454 (4 pages) | Cited 2 times

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A computer-controlled electron beam microfabrication system has been used to fabricate complex, high-frequency acoustic surface wave devices. System hardware and software, fabrication process, and results are described.
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81.65.Cf Surface cleaning, etching, patterning
43.35.-c Ultrasonics, quantum acoustics, and physical effects of sound

A High-Performance, Low-Cost Digitally Driven SEM System for Materials Studies and Microfabrication

John Pasiecznik and Jeffrey Frey

J. Vac. Sci. Technol. 10, 1012 (1973); http://dx.doi.org/10.1116/1.1318455 (4 pages) | Cited 2 times

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The design and construction of a low-cost but high-performance digitally driven scanning electron microscope (SEM) system is described. The low cost of the system is achieved by designing the digital drive mechanism around a programmable desk calculator with expanded cassette or disk memory. Precision of beam placement and deflection, uniformity of beam current, and reproducibility of beam location; are achieved by combining the best elements of previously developed analog and digital beam-drive systems. A hybrid analog∕digital technique is used to generate lines. Endpoint data for lines are specified digitally and a continuous line is generated between the endpoints at a constant writing speed. This technique results in the generation of lines free of steps, glitches, and transients, can be used for generation of rotated or skewed vectors, and is not limited to rectangular geometry. In order to facilitate high-speed operation, not limited by the relatively low-output cycle time of most small programmable calculators, and to conserve the limited memory capabilities of these machines, a dedicated hardware logic system is used to generate all endpoint data needed to fill in rectangular areas. Upon command, a special subprogram can be called to generate circles or other desired geometries. The system can be scaled in time and hence made compatible with most x–y plotters to allow checking of the exposure program. The interface to the HP9820 and the hardware logic system described can be applied easily to other calculators with similar capabilities. Since its capabilities can be achieved at relatively low cost, this system could be of great use in smaller research establishments in programs involving SEM diagnostics and scanning electron-beam exposure of resists for microfabrication, particularly in the semiconductor device field.
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07.78.+s Electron, positron, and ion microscopes; electron diffractometers

A Fast Turn Around Electron-Beam Pattern Generation System

B. P. Piwczyk and K. G. McQuhae

J. Vac. Sci. Technol. 10, 1016 (1973); http://dx.doi.org/10.1116/1.1318456 (4 pages)

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An electron-beam mask-generation system designed to demonstrate fast turn around and high resolution capability is described. The system has been developed using an Advanced Metals Research 900 SEM and a Nuclear Data 812 computer. Patterns are generated utilizing a matrix of 4096×4096 randomly addressable data points. Complex and∕or large patterns can be generated by mechanical repositioning of the substrate and scanning of adjacent fields. A complete stepped and repeated master plate is produced in several hours as compared with several days using conventional systems. The time saving has been primarily achieved by combining the artwork generation, reduction, and step and repeat operations into a single operation. Compatibiltiy with conventional computer aided design and graphics software has been maintained by translating ordinary artwork generation data into information acceptable by the electron-beam system. Extensive software allows virtually all geometries to be generated by the system.
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85.40.Hp Lithography, masks and pattern transfer

An Automated Electron-Beam Mask Generator

E. B. Friedmann, W. R. Livesay, and A. L. Rubiales

J. Vac. Sci. Technol. 10, 1020 (1973); http://dx.doi.org/10.1116/1.1318457 (5 pages)

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An over-all system approach has been undertaken to make electron-beam microfabrication practical in a production environment at throughput rates which make it economically attractive to semiconductor manufacturers. An electron-beam system designed for fabrication of IC masks at final size in one step is described. Novel features include an ultrahigh-speed 16-bit digital deflection system, high-vacuum compatible x–y table and a field-emission source. System features described are single operator performance, multiple methods to input mask designs, high-speed deflection system, and (intelligent) beam logic interface and CAD system. The system is capable of producing 1.0-μ lines with ± 0.2-μ precision over a 0.25×0.25-in. scan field with coverage of 3×3-in. masks using step and repeat techniques. The system also includes an automated load-lock, cryopumped vacuum system and a high-speed 16-bit minicomputer. System parameters such as throughout time, writing speed, and factors affecting these parameters will be discussed.
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85.40.Hp Lithography, masks and pattern transfer

LSI Pattern Generation and Replication by Electron Beams

P. R. Malmberg, T. W. O'Keeffe, M. M. Sopira, and M. W. Levi

J. Vac. Sci. Technol. 10, 1025 (1973); http://dx.doi.org/10.1116/1.1318458 (3 pages) | Cited 2 times

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The combined use of the digitally controlled single electron beam pattern generator to make micron-scale LSI patterns and the 1:1 electron image projection system to replicate these patterns on device substrates represents a practical means for realizing high-density integrated circuits in large volume production. After six years of research and development at Westinghouse, most of the obstacles to successful use of these methods have been removed. Among the problems solved are uniform exposure of points, lines, and areas in a device pattern, fabrication of high-resolution electromasks for the electron image projector, and registration of successive device patterns in both electron beams systems, used in combination. In the most recent work, a 1024-bit random access memory was used as a test vehicle. Eight mask levels were involved, including a buried diffusion. In both machines, alignment of a new pattern with a preexisting pattern on the substrate was obtained through electron beam probing of fiducial mark areas. An automatic alignment system developed for the electron image projection system made possible alignment within a few seconds and subsequent controlled exposure. Including alignment errors originating in the electron beam mask generator, over-all pattern registrations were within ±1.5μ.
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85.40.Hp Lithography, masks and pattern transfer

Integrated Circuit Production with Electron Beams

W. R. Livesay

J. Vac. Sci. Technol. 10, 1028 (1973); http://dx.doi.org/10.1116/1.1318459 (5 pages)

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The merits of two electron-beam systems are discussed, one for mask generation and the other for wafer alignment and exposure. The performance characteristics of both systems are described, including problems involved with IC fabrication. Results of resolution, distortion, and alignment studies are given on both systems. The single-beam mask generator employs a field-emission source, and the performance advantages and disadvantages of this source for microfabrication are detailed. The field-emission source is imaged by an electrostatic lens at a 10-cm working distance. The characteristics of the focusing and deflection system are given. Parameters such as writing speed, beam current, resolution, and area of coverage are compared to conventional electron sources and performance results are reported. The performance of both cold and thermal field-emitters is also discussed. The electron projection system which utilizes a noble-metal patterned photocathode electron source is described. Electron-optical characteristics of the projection system are discussed, including results of alignment and distortion tests. The research model as well as the fully automated electron-projection system designed to process up to 100 wafers per hour are described.
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85.40.Hp Lithography, masks and pattern transfer

Relativistic Electron-Beam Pumped uv Gas Lasers

R. W. Dreyfus and R. T. Hodgson

J. Vac. Sci. Technol. 10, 1033 (1973); http://dx.doi.org/10.1116/1.1318460 (4 pages) | Cited 2 times

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Stimulated emission occurs when (ortho- and para-) H2, HD, D2, CO, Ne, and N2 are excited by a 4-GW electron beam. The beam is generated by a Febetron, model 706, and propagates 2.3 m through the gases at 8–100-Torr pressures. Propagation is aided by an externally applied ∼ 10 kG magnetic field. Collisions involving primary, secondary, and cascade electrons transfer ≤ 0.1% of the energy from the electron beam to produce population inversions. The small-collision cross sections for relativistic electrons act as the primary limitation to the transfer of more energy to the gas molecules. Dependence of the laser energy on isotopes and temperature indicates that the spectral linewidth is due to Doppler broadening, and consequently higher power and optical gain are available by cooling the gases to ∼ 90 K or lower. The additional optical gain allows lasing to be observed at shorter wavelengths (1098 Å as compared to 1161 Å) and at higher powers near 1200 Å (∼ 5 kW∕ cm2 as compared to 0.5 kW∕cm2) than reported previously.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers

Laser Generated Thermoelastic Shock Waves in Liquid

Gangadaran Siva Bushanam and Frank S. Barnes

J. Vac. Sci. Technol. 10, 1037 (1973); http://dx.doi.org/10.1116/1.1318461 (2 pages)

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The interactions of lasers with matter are manyfold. Among the important interactions is the generation of pressure waves by laser heating in an optically absorbing dye. The conversion of energy from transient laser heating to an acoustic wave is considered in detail in this paper. As a laser pulse enters an absorbing dye, energy is absorbed and converted into heat. Part of it will appear as elastic energy in the form of a pressure wave, due to very small expansion in the dye during the laser pulse.
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62.50.-p High-pressure effects in solids and liquids

Lasers for the Cleaning of Statuary: Initial Results and Potentialities

L. Lazzarini, L. Marchesini, and J. F. Asmus

J. Vac. Sci. Technol. 10, 1039 (1973); http://dx.doi.org/10.1116/1.1318462 (5 pages) | Cited 1 time

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Cleaning is one of the most difficult operations encountered in the restoration of statuary. The fact that known cleaning methods are not entirely satisfactory has stimulated continuing research into new methods and processes. A novel method is proposed for cleaning superficial black scabs or patinas from works of art in marble or other stone by means of laser radiation. Surface cleaning results with a ruby laser are reported and compared with conventional techniques. Preliminary analyses of the laser process are quite favorable and indicate improved selectivity and graduation, self-limiting encrustation removal, and remarkably rapid surface coverage. Finally, the results of cleaning tests with various laser types are presented and discussed, and possible future developments and pratical applications of this new method of cleaning statuary are presented.
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42.62.-b Laser applications

Design and Analysis of a Laser Oriented, Automatic Dimensional Inspection System for High-Speed Process Control

Steven M. Ward and Patrick H. Brew

J. Vac. Sci. Technol. 10, 1044 (1973); http://dx.doi.org/10.1116/1.1318463 (4 pages)

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Recent advances in the technology of high-speed manufacturing systems have introduced the need for a new approach in the design of process control systems. Computerized process control systems require automatic quality inspection stations which are capable of converting measures of product attributes into electronic information. In this study, a noncontact, electro-optic inspection system was developed which automatically measures product outer dimension at high speeds. Two approaches were taken in the system design. One approach required a photodetector as an analog measuring device, and the other utilized a photodiode matrix as a digital measuring device. The performance capability of each system was in the order of 100% detection of outer dimensions that were 0.01 in. out of specification to 97% for 0.001 in. variations. Both design approaches resulted in fast, accurate, and inexpensive inspection systems which could easily be adapted to most production environments.
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42.62.Cf Industrial applications

E-Beam Writing Techniques for Semiconductor Device Fabrication

G. L. Varnell, D. F. Spicer, and A. C. Rodger

J. Vac. Sci. Technol. 10, 1048 (1973); http://dx.doi.org/10.1116/1.1318464 (4 pages) | Cited 8 times

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Electron-beam writing instruments for microcircuit fabrication are currently limited by total cycle time, field coverage, automatic registration, and reliability. A fully computer-controlled electron-beam pattern generator will be described which has been developed to advance the economic feasibility of electron beam writing. The instrument incorporates a fully automated mechanical stage and pattern registration system, computer designed deflection coils and a dynamic focusing system for correction of deflection introduced aberrations. Field coverage at the short working distance is variable, up to 0.120×0.120 in. with 60 000×60 000 addressable points in the field. Resolution over the field is 3500 lines at 8 mrad. Pattern distortion is within 1.0 μ over a 0.1 in. square field. The mechanical stage employs stepping motors driving lead screws to provide 3×3 in. movement in 250 μ in.steps. Additional travel of 7 in. is available in one axis for loading the wafer. The automatic pattern registration system employs four silicon etched “L” shaped fiducial marks located in the corners of each field. The electron beam is used to measure the position of the fiducial marks before each field exposure and position the pattern correctly on the wafer. Pattern position, size, rotation, and orthogonality are all typically set up by the automatic registration system in 300 msec. A vernier test pattern has been used to test the alignment system and shows registration better than ± 0.2 μ.
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85.40.Hp Lithography, masks and pattern transfer

Computer Controlled Pattern Generating System for use with Electron-Beam Writing Instruments

D. F. Spicer, A. C. Rodger, and G. L. Varnell

J. Vac. Sci. Technol. 10, 1052 (1973); http://dx.doi.org/10.1116/1.1318465 (4 pages) | Cited 4 times

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Recent advances in electron sources and electron resists have resulted in a significant increase in potential exposure rate in electron-beam writing instruments. This in turn places stringent requirements on the pattern generating electronics which must be fast enough to avoid their limiting potential system throughout, yet flexible enough to be capable of creating all normally required geometries. A computer-controlled pattern generation system is described which is designed to meet these requirements. In this system, the speed limitation due to the calculation and data-transfer rate of modern minicomputers is avoided by the use of an auxiliary special-purpose logic processor. Patterns are built up from a basic trapezoid shape with two sides parallel to rectangular cartesian coordinate axes. The computer has only to specify the basic parameters defining a trapezoid and the auxiliary processor will then output coordinates representing the end points of lines defining the figure in a raster-scan format. These coordinates, which may be generated at rates up to 1 MHz are passed to a pair of precision ramp generators. The ramp generators, which are based on commercially available 16-bit digital-to-analog converters, then produce the analog deflection signals needed to define the line, at a sweep rate which may be varied under computer control over six orders-of-magnitude. Particular care has been taken to reduce the switching spikes, inherent in digital-to-analog converters, to negligible proportions on the output waveform.
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85.40.Hp Lithography, masks and pattern transfer

Model for Exposure of Electron-Sensitive Resists

J. S. Greeneich and T. Van Duzer

J. Vac. Sci. Technol. 10, 1056 (1973); http://dx.doi.org/10.1116/1.1318466 (4 pages) | Cited 6 times

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A mathematical model for the exposure of electron-sensitive resists on a structure coated with a thin layer of resist is presented. The calculations yield contours of equal absorbed energy density in the resist and these are interpreted as the contours which bound the resist after development. We calculate the exposure for an electron beam of vanishingly small cross-section, a beam of Gaussian current-density distribution, single lines, parallel lines, and areas.
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85.40.Hp Lithography, masks and pattern transfer

Electron Beam Testing of Circuit Interconnections using Collector Stabilized Conductor Charging

J. M. Sebeson

J. Vac. Sci. Technol. 10, 1060 (1973); http://dx.doi.org/10.1116/1.1318467 (4 pages) | Cited 1 time

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A noncontact procedure for sensing continuity and isolation faults in large, dense interconnection patterns by means of selective deposition of charge by an electron beam is proposed and discussed. When the accelerating potential is properly chosen, a marked variation in the secondary electron signal occurs during the charging of an electrically floating element to an equilibrium potential. This phenomenon forms the basis of the method. A laboratory system has been constructed to demonstrate the procedure. Results obtained indicate agreement with the basic theory and demonstrate the application of the technique to continuity and isolation testing of conductor films. Electron-beam testing has a clear advantage over mechanical-probe testing in terms of speed and flexibility. The less attractive features include the need for a vacuum system and the inability to detect continuity faults when the fault resistance is less than about one megohm.
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85.40.Qx Microcircuit quality, noise, performance, and failure analysis

Coates–Kikuchi Patterns and Electron-Spectroscopy from Single Crystals

E. D. Wolf and P. J. Coane

J. Vac. Sci. Technol. 10, 1064 (1973); http://dx.doi.org/10.1116/1.1318468 (4 pages) | Cited 1 time

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Experimental measurements are reported on the geometric and intensity variations of Coates–Kikuchi backscattered electron images from several single crystals as a function of the primary electron beam energy and angle of beam incidence to the crystal lattice. Total energy distribution measurements of the backscattered electrons were also made on a (001) GaAs wafer using a custom designed cylindrical mirror electron analyzer. The number of elastically backscattered primary electrons decreased by 80% when the beam was incident in the off-axis direction. The first plasmon loss peak was observed at −14.5 eV ± 1 eV, with a primary beam energy of 8 keV. The motivation for this work is a better characterization of the high-contrast Coates–Kikuchi patterns that we have observed using an energy sensitive solid-state detector, and better application of these patterns, which are highly detailed reciprocal lattice displays, to surface analysis. Generation of these displays in a scanning electron microscope allows practical and rapid measurement of crystal orientation, crystal type, and near-surface lattice disorder.
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61.05.J- Electron diffraction and scattering

Investigation of Soft X-Ray Absorption Edge Structure using an Energy Modulated Electron Beam

K. N. Ramachandran and C. D. Cox

J. Vac. Sci. Technol. 10, 1068 (1973); http://dx.doi.org/10.1116/1.1318469 (4 pages) | Cited 1 time

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The absorption edges of elements can be investigated using an energy-modulated electron beam by plotting the derivative of the total x-ray yield against electron energy, called the appearance potential spectrum. A simple apparatus was built, consisting of a tungsten-electron source and a large-area windowless x-ray detector, located in an ultrahigh-vacuum system. The soft x-ray absorption edge structure of the light elements from beryllium to oxygen and a few heavier elements was obtained. Electron currents in the range of 1 mA were normally needed for most of the experiments, though successful recordings were made at 15 μA. All of these spectra show complex structure which is presumably related to the density distribution of the empty states in the valence band. The L-edge structure of iron and nickel is presented in pure and alloyed forms to demonstrate spectral shifts. Some anomalous structure was also obtained from certain specimens. Because of the low-energy of the probing electrons, the technique is basically a tool for surface analysis, sensitive to light elements. The simplicity of the apparatus makes it possible to adapt it to existing systems for surface studies.
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78.70.Dm X-ray absorption spectra

Use of an Ion Microprobe in Semiconductor Failure Analysis

R. M. Gerber and J. W. Dzimianski

J. Vac. Sci. Technol. 10, 1072 (1973); http://dx.doi.org/10.1116/1.1318470 (2 pages)

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Causes of high-ohmic contact resistance were explored by analyzing several integrated circuit samples with an ion microprobe. Presence of oxide and dopant depletion at the interface were indicated. Mapping of oxygen vs depth through an oxide revealed that not only the elements present, but also the layered structure of the material could be observed. The possible production of artifacts due to electrostatic charges on the surfaces of a sample was noted.
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85.40.Qx Microcircuit quality, noise, performance, and failure analysis
81.70.Jb Chemical composition analysis, chemical depth and dopant profiling

The Fabrication of IGFETS using Electron-Beam Technology

K. A. Pickar and L. R. Thibault

J. Vac. Sci. Technol. 10, 1074 (1973); http://dx.doi.org/10.1116/1.1318471 (4 pages)

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We study here the fabrication of p-channel MOS field effect transistors with 4 μ gate lengths, made with electron-beam lithography substituted for conventional photolithography. The remainder of the processing included tungsten metallization with self-aligned ion implanted source and drain regions as described by Moline et al., and by Boll and Lynch (IEDM, 1972). The resulting transistors were characterized by turn-on voltage, Vt of 1.3–1.6 V (〈0100〉 orientation) and 1.8–2.1 V 〈111〉. For the 〈100〉 devices, the distribution in Vt across each slice was very tight (2σ < 0.1 V). The experimental values for Vt could be predicted from independently measured values of substrate doping and flatband voltage. Transconductance per square of gate was typically ∼ 14 ± 1.4 μʊ(i.e., μΩ−1) (at VG–Vt=−3V) for devices with a gate oxide thickness of 1000 Å and a gate width of 200 μ. The value for mobility, μ, for the 〈100〉 devices was estimated to be 160 cm2 V−1 sec−1. The punch-through voltage was 23 ± 1.5V. The bias-temperature stability of the resulting devices was found to be strongly dependent on the crystal orientation. Slices with 〈100〉 faces were highly stable (<0.08 V shift after five minutes of positive or negative application of 106 V∕cm at 300 °C); slices with 〈111〉 orientation were considerably less stable (up to 0.7V shift under the same conditions). The results are in general accord with previous results using conventional photolithography projected to account for narrower gate lengths. They indicate that no additional complications were introduced by the substitution of electron-beam lithography.
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85.30.Tv Field effect devices
85.40.Hp Lithography, masks and pattern transfer

IGFET Inverter Circuits made with Electron Lithography

R. F. W. Pease, R. C. Henderson, and J. V. Dalton

J. Vac. Sci. Technol. 10, 1078 (1973); http://dx.doi.org/10.1116/1.1318472 (4 pages) | Cited 1 time

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In IGFET circuitry, it has been predicted that halving the lateral dimensions should bring about approximately a fourfold speed advantage; providing doping levels, vertical dimensions, and applied voltages are constant. We have used electron lithography to make p-channel IGFET inverter circuits with 9- and 4-μ gates and have demonstrated a sixfold improvement in the propagation delay for smaller circuits. The devices were made using a refractory metal and ion implantation as described by Moline et al., and by Boll and Lynch. (IEDM, Washington, 1972). The electron resist (used for all four lithographic stages) was much more sensitive than polymethylmethacrylate.
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85.40.Hp Lithography, masks and pattern transfer
85.30.Tv Field effect devices

Electron-Beam Fabrication of Ion Implanted High-Performance FET Circuits

F. Fang, M. Hatzakis, and C. H. Ting

J. Vac. Sci. Technol. 10, 1082 (1973); http://dx.doi.org/10.1116/1.1318473 (4 pages) | Cited 4 times

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This paper describes the design, fabrication and test results of a high-performance IGFET circuit made by combining electron-beam technology for all masking steps and ion implantation for the diffusion steps. The circuit consists of an eleven stage ring oscillator with two FET devices per stage. The enhancement mode device is the switching element and the depletion mode is used as load. The aluminum gate length of the devices is 1 μ and the width is 5 μ. The aluminum metallization, defined with electron-beam exposure of PMMA resist, also serves as a self-aligning mask for the ion implantation of source and drain in the gate region. The average delay per stage was determined by measuring the periodicity of the circuit oscillation and dividing by 22. Test results on several circuits indicate that the average delay per stage is approximately 295 psec.
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85.40.Hp Lithography, masks and pattern transfer

Fabrication of Integrated CMOS Transistors using Electron Lithography and Ion Implantation

M. M. Sopira, P. R. Malmberg, and Z. H. Meiksin

J. Vac. Sci. Technol. 10, 1086 (1973); http://dx.doi.org/10.1116/1.1318474 (4 pages)

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Electron lithography and ion implantation have been used in the fabrication of integrated complementary P-channel and N-channel transistors. A digitally controlled single electron beam system, the Electron Micropattern Generator, aligned and exposed the eight mask levels required. The cumulative alignment tolerance was 3 μ. Fabricated devices had channel lengths of 1, 2, and 6 μ, and drain-source breakdown voltages of − 22 and + 12 V for the P- and N-type, respectively. Ion implantation was used to produce self-aligned gate structures by extending the diffused source and drain contact regions to the gate edges. The implantation masks consisted of 3000 Å aluminum and 7700 Å PMM resist. Boron and phosphorus ions were implanted at 50 and 100 keV, respectively at dosages ranging from 1×1014 to 1×1015 ions∕cm2. Sintering and annealing operations were performed at 500 °C for 10 min in N2 atmosphere. Sheet resistances ranged from 2700 to 1000 Ω/□ for implanted boron and 700−240 Ω/□ for the phosphorus. Evolving high-density circuits require shallow P-well junctions (≈ 2.7μ) and contact regions (≈ 0.7μ) in N-type 〈100〉 oriented silicon of 0.35 Ω-cm resistivity. Evaluation of the transistors showed enhancement mode operation with VTP=−4.8 V and VTN=+1.4 V using a gate dielectric structure consisting of CVD sandwich layers of 125 Å SiO2 plus 750 Å Si3N4, yielding average surface state density of 6×1011 charges∕cm2. Evaluation of diffused and implanted transistors, as well as resistors, will be discussed.
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85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology

The Fabrication of Bipolar Transistors using Electron Lithography, Ion Implantation, and Nickel-Masked Gold Metallization

P. W. Shackle and R. S. Payne

J. Vac. Sci. Technol. 10, 1090 (1973); http://dx.doi.org/10.1116/1.1318475 (4 pages)

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Bipolar microwave transistors have been fabricated using ion implantation and electron lithography, with a sputter-etched nickel-masked gold metallization process as originally developed by Herb and Labuda. The resulting devices showed the fine definition associated with the latter two technologies, together with the uniformity of electrical properties associated with ion implantation. The electrical properties of the transistors were found to be comparable to similar devices also made with ion implantation but employing conventional photolithography and electroplated gold metallization. It is suggested that the combination of technologies illustrated in the work will be generally applicable to bipolar integrated circuits.
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85.30.Pq Bipolar transistors
85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology

Selective Area Metallization by Electron-Beam Controlled Direct Metallic Deposition

J. P. Ballantyne and W. C. Nixon

J. Vac. Sci. Technol. 10, 1094 (1973); http://dx.doi.org/10.1116/1.1318476 (4 pages) | Cited 1 time

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Direct metallic deposition exploits the advantages of electron-beam exposure for the production of fine structures and avoids the use of resists and chemical etching. The process involves the electron-induced decomposition of metallic compounds in areas precisely defined by an electron probe. In principle, the resistivity of the deposits formed by direct metallic deposition can be controlled by regulating the amount of molecular dissociation which takes place. To date, in experiments with silver chloride, deposits with submicron dimensions have been obtained. Typical sheet-resistance values of the deposits range from 10 to 1000 Ω∕square for exposures varied from 3×10−2 to 5×10−3 C∕cm2. A Monte Carlo simulation of electron scattering in thin films on a supporting substrate has shown that the minimum deposit dimensions which can be expected from the process vary directly with film thickness and inversely with accelerating voltage. Experimental evidence is in agreement with the theoretical predictions.
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85.40.Sz Deposition technology

Theory of Aberration Mixing in Electron-Optical Systems

K. J. Harte

J. Vac. Sci. Technol. 10, 1098 (1973); http://dx.doi.org/10.1116/1.1318477 (4 pages) | Cited 1 time

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In order to analyze the imaging properties of an electron-optical system, it is necessary to know how various sources of aberration combine to increase the size of the final image or spot. Either linear mixing, or else quadratic mixing (based on the assumption that the aberration produces a Gaussian distribution), have been commonly used. In this paper a theory of aberration mixing is developed, starting from the assumption of a circularly symmetric current-density distribution, each point on which is subjected to a circularly symmetric aberration. If the effective radius of the spot (and of each contribution) is defined as the square root of the normalized second moment of the current-density distribution, then the following theorem is shown to hold: when a spot with a circularly symmetric current-density distribution suffers any circularly symmetric aberration, the effective radius of the resultant spot is the square root of the sum of the squares of the effective radii of the original spot and the aberration disk. If several sources of aberration are present, it follows that the effective radii all add quadratically. For a Gaussian distribution, it is shown that the effective radius is just the 1∕e point on the current-density distribution. For a rectangular distribution (e.g., defocusing or, to first approximation, astigmatism) and the distribution resulting from the spherical aberration of a lens, numerical constants are derived which relate the effective radius to the more usual and often more convenient outer diameter of the aberration disk.
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41.85.Gy Chromatic and geometrical aberrations

Electron Optics of an Off-Axis Solid-State Light Valve

D. Casasent and F. Caimi

J. Vac. Sci. Technol. 10, 1102 (1973); http://dx.doi.org/10.1116/1.1318478 (4 pages) | Cited 2 times

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The solid-state light valve, consisting of an off-axis electron gun and an electro-optic target crystal, is used as a two-dimensional spatial light modulator for a collimated laser beam. With a 1 mil electron beam spot and 50 μA beam current, 1000 line resolution and real time operation at TV frame rates have been achieved. The electron optics and three error function figures of merit for a generalized off-axis electron beam system are presented. The component selection procedure and an analog correction preprocessor design on a precalculated basis are discussed.
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42.79.Hp Optical processors, correlators, and modulators
41.85.-p Beam optics

The Design of Double Focusing Wien Filters

R. E. Collins

J. Vac. Sci. Technol. 10, 1106 (1973); http://dx.doi.org/10.1116/1.1318479 (4 pages) | Cited 3 times

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Conditions for stigmatic focusing in the Wien filter velocity selector are described. Two analyzers, designed according to these principles, have been built; preliminary results are presented. The application of this type of device as an electron spin rotator is discussed.
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07.81.+a Electron and ion spectrometers
41.85.-p Beam optics

Computer-Aided Design and Experimental Investigation of an Electron–Optical Collimating Lens

C. C. T. Wang, K. J. Harte, N. Curland, R. K. Likuski, and E. C. Dougherty

J. Vac. Sci. Technol. 10, 1110 (1973); http://dx.doi.org/10.1116/1.1318480 (4 pages)

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An electron–optical system capable of producing a highly collimated, large-diameter beam was designed, built and tested. The system consisted of a strong, decelerating condenser lens followed by an accelerating, collimating, “Kan” lens. The lenses were designed with the help of a large digital computer, using a combination of relaxation and analytical techniques. The Kan lens, which was the critical component, had a parabolic potential on a cylindrical boundary and terminated in an endplate containing an array of small exit holes. System performance was investigated by ray-tracing techniques; over-all angular accuracy was 0.005 mrad. Several systems were built, with an insulated-ring construction method, and tested by both a Moiré pattern technique and an extended column method, the latter accurate to 0.05 mrad. It was found that by recessing the endplate, thereby creating a weak divergent lens the spherical aberration of the system could be nearly cancelled, resulting in a final miscollimation of 0.06 mrad over a 2- in. diam. When the collimated beam was focused by a lens, an off-axis radial ellipticity was discovered, the origin of which was found to be chromatic aberration resulting from the Boersch effect.
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41.85.Ne Electrostatic lenses, septa

Representation of Focal Properties of the Equal-Diameter Two-Tube Electrostatic Lens for Computer Calculations

A. Galejs and C. E. Kuyatt

J. Vac. Sci. Technol. 10, 1114 (1973); http://dx.doi.org/10.1116/1.1318481 (4 pages) | Cited 2 times

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Previous calculations have given accurate first-order focal properties for the two-tube electrostatic lens at discrete voltage ratios. For computer optimization, calculations involving systems of two-tube lenses, one must be able to calculate the focal properties continuously over some arbitrary range of voltage ratios. Hence the data must be displayed in a continuous manner, and a method of interpolation is needed which yields functions having a high degree of smoothness. Special care must be taken to describe the lens behavior correctly near zero strength or for the voltage ratio approaching unity. A satisfactory solution to this problem has been achieved using cubic splines. The resulting functions of the focal properties are continuous and have continuous first and second derivatives. The total beam behavior, and hence the system design, is determined by the transfer matrix which is obtained from the focal properties. To achieve sufficient accuracy in the lens calculations over the entire range of required focal properties, the region near zero lens strength had to be treated separately.
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41.85.Ne Electrostatic lenses, septa

Focal Properties of the Two-Tube Electrostatic Lens for Large Voltage Ratios

C. E. Kuyatt, D. DiChio, and S. V. Natali

J. Vac. Sci. Technol. 10, 1118 (1973); http://dx.doi.org/10.1116/1.1318482 (2 pages) | Cited 5 times

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Previous calculations of electron trajectories and first-order focal properties of the two-tube electrostatic lens have been extended to a voltage ratio of 1000. Considerable ultrafocal refraction occurs in these strong lenses, with the result that near the highest voltage ratio studied the two focal points are both on the low-voltage side of the lens and nearly coincident. The results are presented in the form of a table and P-Q (image-object) curves.
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41.85.Ne Electrostatic lenses, septa

Digital Computer Simulation of Charged Particle Beams and Electrostatic Lenses

J. E. Boers

J. Vac. Sci. Technol. 10, 1120 (1973); http://dx.doi.org/10.1116/1.1318483 (4 pages) | Cited 2 times

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A digital computer program for the simulation of charged particle beams in complex electrostatic lens systems is described. A large matrix is employed to simulate the potentials in rectangular or axisymmetric configurations, and relativistic trajectory computations are employed to simulate beams or charged particles of any energy. The beam may be injected with any energy or spatial distribution, including point sources. The program is intended to be an engineering tool which will produce results with an accuracy of one or two percent with modest effort in setting up the problem. Simulations of a CDC 6600 typically require 2 min or less, and complete solutions including plots of trajectories and equipotentials are frequently obtained in less than 30 sec. Results for some specific cases are shown to be within 2% of experimental or exact analytical results.
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41.85.Ne Electrostatic lenses, septa

Third-Order Aberration Coefficients of Electron Lenses. II

C. E. Kuyatt, D. DiChio, and S. V. Natali

J. Vac. Sci. Technol. 10, 1124 (1973); http://dx.doi.org/10.1116/1.1318484 (3 pages) | Cited 3 times

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In the standard treatments of aberration coefficients of electron lenses, deviations from perfect imagery are expressed as power series of the ray coordinates in the object and aperture planes. The resulting aberration coefficients depend on the object and aperture positions, and a complete description of the aberrations of an electron lens would require a doubly infinite set of aberration coefficients for each voltage ratio of the lens. Hawkes has carried out a general treatment of the third-order aberrations of electron lenses which is independent of object and aperture positions. Six quantities are sufficient to specify the third-order aberration properties of an electron lens. We have derived equations for these six quantities in the form of integrals, involving derivatives of the axial potential no higher than the second, and using our previously calculated potentials have computed aberration coefficients for the two-tube electrostatic lens.
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41.85.Gy Chromatic and geometrical aberrations

Abstracts from the Symposium Proceedings

J. Vac. Sci. Technol. 10, 1127 (1973); http://dx.doi.org/10.1116/1.1318485 (6 pages) | Cited 1 time

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85.40.Hp Lithography, masks and pattern transfer
41.85.Ne Electrostatic lenses, septa

Abstract: Focused Ion Beams in Microfabrication

R. L. Seliger and W. P. Fleming

J. Vac. Sci. Technol. 10, 1127 (1973); http://dx.doi.org/10.1116/1.1318486 (1 page) | Cited 3 times

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85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology

Abstract: Ion Beam Etching of Surface Gratings

Henry I. Smith, J. Melngailis, R. C. Williamson, and W. T. Brogan

J. Vac. Sci. Technol. 10, 1127 (1973); http://dx.doi.org/10.1116/1.1318487 (1 page)

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81.65.Cf Surface cleaning, etching, patterning
85.50.-n Dielectric, ferroelectric, and piezoelectric devices

Abstract: Ion-Beam Milling of Insulators using Broad Neutralized Beams

G. W. Monk

J. Vac. Sci. Technol. 10, 1128 (1973); http://dx.doi.org/10.1116/1.1318488 (1 page)

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79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Abstract: Resumé of the U.S.-Japan Seminar on the Fundamentals of Scanning Electron Microscopy

T. E. Everhart

J. Vac. Sci. Technol. 10, 1128 (1973); http://dx.doi.org/10.1116/1.1318489 (1 page)

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68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
01.10.Fv Conferences, lectures, and institutes

Abstract: Electron-Beam Spreading and its Effect on Sustainer Current and Field Distribution

J. H. Jacob, J. P. Reilly, and E. R. Pugh

J. Vac. Sci. Technol. 10, 1128 (1973); http://dx.doi.org/10.1116/1.1318490 (1 page)

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52.80.-s Electric discharges

Abstract: Emission Characteristics of a LaB6 Electron Gun

W. Stickel and H. C. Pfeiffer

J. Vac. Sci. Technol. 10, 1128 (1973); http://dx.doi.org/10.1116/1.1318491 (1 page)

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07.77.Ka Charged-particle beam sources and detectors

Abstract: Laboratory Measurements of the Effectiveness of a Magnetic Shield

Herbert A. Cohen and Paul S. Wilson

J. Vac. Sci. Technol. 10, 1128 (1973); http://dx.doi.org/10.1116/1.1318492 (1 page)

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41.85.-p Beam optics

Abstract: Generation of Self Focusing MA∕ cm2 Electron Beams

D. G. Pellinen and S. E. Heurlin

J. Vac. Sci. Technol. 10, 1128 (1973); http://dx.doi.org/10.1116/1.1318493 (2 pages)

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07.77.Ka Charged-particle beam sources and detectors
41.85.Lc Particle beam focusing and bending magnets, wiggler magnets, and quadrupoles

Abstract: Electron Beam Utilization for the Dissociation of Fluorine

Roger Little and Robert Lowell

J. Vac. Sci. Technol. 10, 1129 (1973); http://dx.doi.org/10.1116/1.1318494 (1 page)

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82.50.Kx Processes caused by X-rays or γ-rays

Abstract: An Electron Detection System for Microfabrication Registration

T. H. P. Chang

J. Vac. Sci. Technol. 10, 1129 (1973); http://dx.doi.org/10.1116/1.1318495 (1 page)

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85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology

Abstract: The Relationship Between Self-Focusing and Optical Bulk Damage and the Measurement of Self-Focusing Parameters

D. W. Fradin

J. Vac. Sci. Technol. 10, 1129 (1973); http://dx.doi.org/10.1116/1.1318496 (1 page)

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42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation

Abstract: Effects of Crystallinity and Lattice Disorder on the Intrinsic Optical Breakdown Strength of Transparent Solids

D. W. Fradin and M. Bass

J. Vac. Sci. Technol. 10, 1130 (1973); http://dx.doi.org/10.1116/1.1318497 (1 page)

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42.65.-k Nonlinear optics
77.22.Jp Dielectric breakdown and space-charge effects

Abstract: Dependence of Laser Induced Breakdown Field Strength on Pulse Duration

D. W. Fradin, N. Bloembergen, and J. P. Letellier

J. Vac. Sci. Technol. 10, 1130 (1973); http://dx.doi.org/10.1116/1.1318498 (1 page)

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42.65.-k Nonlinear optics
77.22.Jp Dielectric breakdown and space-charge effects

Abstract: Transient Thermal Profile in Optically Pumped Laser Rods

W. Koechner

J. Vac. Sci. Technol. 10, 1130 (1973); http://dx.doi.org/10.1116/1.1318499 (1 page)

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42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Abstract: Paper-Tape Controlled Electron Probe Exposure of Resist for Microelectronic Applications

C. Dix and W. C. Nixon

J. Vac. Sci. Technol. 10, 1131 (1973); http://dx.doi.org/10.1116/1.1318500 (1 page)

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85.40.Hp Lithography, masks and pattern transfer

Abstract: A Phenomenological Optimization of Negative-Electron Resist Exposure Conditions

J. L. Bartelt and J. P. Ballantyne

J. Vac. Sci. Technol. 10, 1131 (1973); http://dx.doi.org/10.1116/1.1318501 (1 page)

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85.40.Hp Lithography, masks and pattern transfer

Abstract: Electron Sensitive Resists—Present and Future

M. Hatzakis

J. Vac. Sci. Technol. 10, 1131 (1973); http://dx.doi.org/10.1116/1.1318502 (1 page)

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85.40.Hp Lithography, masks and pattern transfer

Abstract: Image Tube Operation of the Scanning Electron Microscope using Insulating Specimens as Floating Targets

H. Ahmed and W. C. Nixon

J. Vac. Sci. Technol. 10, 1131 (1973); http://dx.doi.org/10.1116/1.1318503 (1 page)

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85.40.Qx Microcircuit quality, noise, performance, and failure analysis
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)

Abstract: A Practical Approach to Automated Image Analysis

Jack D. Hutchison

J. Vac. Sci. Technol. 10, 1131 (1973); http://dx.doi.org/10.1116/1.1318504 (1 page)

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07.05.Pj Image processing

Abstract: Nanoelectronic Project and Astec Logic

J. E. Picquendar

J. Vac. Sci. Technol. 10, 1132 (1973); http://dx.doi.org/10.1116/1.1318505 (1 page)

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81.07.-b Nanoscale materials and structures: fabrication and characterization
81.16.-c Methods of micro- and nanofabrication and processing
85.35.-p Nanoelectronic devices

Abstract: Electron-Beam Microfabrication: The Prospects for a Practical System

Peter A. Charman

J. Vac. Sci. Technol. 10, 1132 (1973); http://dx.doi.org/10.1116/1.1318506 (1 page)

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85.40.-e Microelectronics: LSI, VLSI, ULSI; integrated circuit fabrication technology

Abstract: Dense Space-Charge Beams Analyzed on a Deformable Relaxation Mesh

Richard True

J. Vac. Sci. Technol. 10, 1132 (1973); http://dx.doi.org/10.1116/1.1318507 (1 page)

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41.75.Fr Electron and positron beams
41.85.-p Beam optics
07.77.Ka Charged-particle beam sources and detectors

Investigation of the Sensitivity of Ionization-Type Vacuum Gauges

Raymond Holanda

J. Vac. Sci. Technol. 10, 1133 (1973); http://dx.doi.org/10.1116/1.1318508 (7 pages) | Cited 7 times

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A quantitative analysis of a large and representative sample of available data has been made to determine the best criteria for predicting the relative sensitivities of ionization-type vacuum gauges to different gases. The molecular property of the gas that correlates best with relative sensitivity is the ionization cross section σ (eV). The best σ value to choose according to gauge type is as follows: 1. For high-pressure ionization gauges, a σ evaluated at ⅔ of the accelerating potential of the gauge is the best choice. 2. For Bayard-Alpert and triode gauges, any of three choices are of approximately equal value. These are 100 eV σ values, maximum σ value for each gas, and a σ evaluated at ⅔ of the accelerating potential for each gauge. 3. For the Alphatron gauge, σ values in the range 5000–10 000 eV provide the best correlation. 4. For cold cathode ionization gauges, insufficient data were available to come to any conclusions.
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07.30.Dz Vacuum gauges

A Simple Method of Calculating the Effectiveness of High Temperature Radiation Heat Shields

Kimo M. Welch

J. Vac. Sci. Technol. 10, 1140 (1973); http://dx.doi.org/10.1116/1.1318509 (4 pages)

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A method is given whereby one may graphically determine the radiation heat transfer properties of a number of closely packed radiation shields. The method uses the gray body formula, taking into account variations in total thermal emissivity of the adjacent shields as a function of temperature. Results were used in the construction of a high temperature vacuum furnace. Excellent correlation was found between graphically predicted and calorimetrically measured results.
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44.40.+a Thermal radiation

Glow Discharge Optical Spectroscopy for Monitoring Sputter Deposited Film Thickness

J. E. Greene and F. Sequeda-Osorio

J. Vac. Sci. Technol. 10, 1144 (1973); http://dx.doi.org/10.1116/1.1318510 (6 pages) | Cited 10 times

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Glow discharge optical spectroscopy was used as a technique for monitoring the rate of sputtering and the rate of film deposition. It was determined that within the pressure and voltage range of these experiments the product of the electroluminescent emission intensity of a given sputtered target species in the discharge and the time of sputtering is linearly proportional to both the change in mass of the target and the final thickness of the deposited film. In the case of compound targets, the emission intensity from either constituent can be monitored. The emission signal was shown to be generated primarily in a narrow region directly in front of the target.
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81.70.Fy Nondestructive testing: optical methods
81.15.Cd Deposition by sputtering

Analysis of Gas Mixtures Using Data from Pulsed Vacuum Networks

Robert Pulfrey and B. R. F. Kendall

J. Vac. Sci. Technol. 10, 1150 (1973); http://dx.doi.org/10.1116/1.1318511 (3 pages)

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A numerical method for extracting gas mixture compositions from pulsed vacuum network data is discussed. The problem of imposing boundary conditions is considered. Results of the analysis of several artificial gas mixtures are presented.
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82.80.Yc Rutherford backscattering (RBS), and other methods of chemical analysis

The Deposition of Single Crystal CaF2 Films on Rocksalt Substrates in Various Orientations

K. Reichelt and M. Rey

J. Vac. Sci. Technol. 10, 1153 (1973); http://dx.doi.org/10.1116/1.1318512 (1 page)

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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.-a Thin film structure and morphology
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