bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion etching of thin windows in silicon
Authors: Spencer E. G. , Lenzo P. V. , Schmidt P. H.
Published: July 2002

Ion etching is used to fabricate thin windows, 5–10 μ thick and ∼ 1-cm diam, in silicon wafers. The method involves a simple variation of a widely used ion source, and provides etch rates of ∼20 μ/h over the 1-cm diam area. The surface of the window is flat and smooth, having a mirror-like finish. The edge of the window is sharp and is defined by the directionality of the ion beam. In this experimental arrangement, the material to be etched acts as a cathode; therefore the method is applicable to all electrically conductive materials.
Simplified Band Model of Ferromagnetic Thin Films
Authors: Szczeniowski S. , Wojtczak L. , Sukiennicki A.
Published: July 2002

The formulation of a simplified one-band model of ferromagnetism, convenient for analytical discussion of thin film properties, is given. Basing on this model the main effects experimentally observed in thin films, such as one electron excitations; spin waves and spin wave resonances, spontaneous magnetization, and the problem of dead layers are discussed. Some new effects following from our model, which are connected with the band nature of its origin, are presented.
Flat Cathode Ray Tubes
Authors: Goede Walter F.
Published: July 2002

The hope of achieving a flat screen television display has resulted in a substantial effort by a number of individuals and companies to develop such a display. However, the performance requirements of such a display present a significant challenge to any display technique attempting to displace the extremely versatile analog defection CRT. To date, no new display has demonstrated the ability to meet these stringent performance requirements, but some of these new devices indicate that with further development these goals may be achieved. This paper will review the performance characteristics of one of these new displays, called the Digisplay, a flat panel digitally addressed CRT. In addition to the principles of operation and special operating characteristics, the characteristics of a new 160×256 resolution element device (2.2 lines/ mm resolution), which has been used to present live—full gray scale—television will be briefly discussed.
The effects of nonconsumable melting on the quality of Ti 6Al/4V
Authors: Willette G. Douglas
Published: July 2002

A nonconsumable electrode-skull casting process designed to remove refractory inclusions by gravity separation is described. Examples of potential advantages are: (i) All forms of raw materials can be melted in any desired ratio; (ii) there is no vaporization find loss of volatile alloy elements, and thus no need for extensive chemical testing and adjustments before remelting; (iii) cast remelt electrodes are produced directly, without prior compacting, welding, and consumable melting. With this process, better chemical homogeneity was obtained, and nitride-type as well as high-density inclusions were removed.
Intrinsic stress of Co35Pd65 alloy films
Authors: Jen S. U. , Chung C. M.
Published: July 2002

Co 35 Pd 65 alloy films were made by the vapor deposition method in a vacuum with the base pressure, p, ranging from 3×10−7 to 9×10−5 Torr. The thickness, t, of these films was varied from 500 to 2500 Å. The substrate temperature, TS, was set equal to 50 or 180 °C. Some of the as-deposited films were annealed at an anneal temperature TA from 180 to 350 °C in vacuum. We employed a strain gauge to measure the deflection, Δy, of the free end of a cantilevered substrate. The stress, S, of the film was determined while removing the film from the substrate. In general, the stress S of the as-deposited Co35Pd65 film is tensile and of the order of 109–1010 dyn/cm2. In terms of t dependence, S has a maximum near t=1000 Å. The thermal stress has a small contribution, i.e., S is mainly due to the intrinsic stress formed during film growth. The stress data are found to be closely associated with the grain structure in these polycrystalline films. Following the same method, we analyzed how S is varied as a function of TA. Finally, the effect of the base pressure on S is studied briefly.
Laser damage studies on MgF2 thin films
Authors: Protopapa Maria Lucia , De Tomasi Ferdinando , Perrone Maria Rita , Piegari Angela , Masetti Enrico , Ristau Detlev , Quesnel Etienne , Duparré Angela
Published: July 2002

The results of laser damage studies performed at 248 nm (KrF excimer laser) on MgF2 thin films deposited by different techniques (electron-beam evaporation, thermal boat evaporation, and ion-beam sputtering) on fused silica and CaF2 substrates are presented. We find that the films deposited on CaF2 substrates by the electron-beam evaporation technique present the highest damage threshold fluence (9 J/cm2). The photoacoustic (PA) beam deflection technique was employed, in addition to microscopical inspection, to determine laser damage fluences. We confirm, by scanning electron microscopy analysis of the damaged spots, the capability of the PA technique to provide information on the mechanisms leading to damage. The dependence of both laser damage fluence and damage morphology on the film deposition technique, as well as on the film substrate, is discussed.
Use of radio frequency bias in the large area plasma processing system
Authors: Manheimer Wallace M. , Lampe Martin , Fernsler Richard F.
Published: July 2002

In the large-area plasma processing system (LAPPS) scheme, rf bias can be used for either of two purposes: to provide energetic ion bombardment of a substrate, or to controllably raise the electron temperature (which is intrinsically very cool) to a desired value. The physics of rf bias in the LAPPS differs from the situation in conventional processing reactors for several reasons: (1) The plasma density adjacent to the substrate can be so high that the ion plasma frequency exceeds the microwave frequency. (2) Plasma transport to the substrate is across a magnetic field. (3) Ionization occurs only in a thin, well-defined planar sheet, and thus the volume occupied by plasma is very broad in two dimensions but thin in the third dimension. (4) The surface area of the substrate is comparable to that of the containment vessel. We discuss the modifications to the theory of rf bias that are needed to account for these factors in a LAPPS plasma.
Stabilizing inductively coupled plasma source impedance and plasma uniformity using a Faraday shield
Authors: Khater Marwan H. , Overzet Lawrence J.
Published: July 2002

Standing waves unavoidably develop on inductively coupled plasma sources because they are mismatched transmission line systems. In addition, the electrical properties of the induction coil (or plasma source) are coupled to those of the plasma, since the coil–plasma system behaves similarly to a transformer. As a result, the input impedance, output-to-input current ratio (OICR), and electromagnetic fields symmetry of the coil are affected by the plasma conditions, which in turn influence the uniformity of plasma generation and ion flux to the wafer surface. In this article we examine the effect of plasma loading on the coil’s impedance and OICR with and without a Faraday shield. Measurements of the coil’s electrical properties without a Faraday shield showed a significant increase in the OICR with plasma conditions. Similar measurements with a Faraday shield showed that coupling between the coil and the shield becomes dominant over coupling between the coil and the plasma. Langmuir probe measurements showed that the radial profiles of ion density and electron temperature remained azimuthally symmetric for different plasma conditions with the shield.
Characterization of the diffusion properties of chromium in stainless-steel oxides by photoemission spectroscopy
Authors: Cho Boklae , Moon Sangwoon , Chung Sukmin , Kim Kijeong , Kang Taihee , Koo Bongsoo
Published: July 2002

Characterization of diffusion properties of atoms in oxides is crucial for understanding oxidation mechanism of metals because the oxidation is mediated by diffusion. Employing in situ photoemission spectroscopy, we have observed diffusion-induced compositional variations of stainless-steel surfaces during oxidations at 450 and 550 °C in the oxygen partial pressure range 1×10−9–1×10−5 Torr. Initially, a significant amount of metallic chromium was present at the surface of stainless-steel oxide layers. During subsequent oxidation, thin oxide films grew on top of the oxide layer, but there existed critical pressures below which the oxide film formed was almost complete Cr2O3. From the critical pressures and growth rates of the oxide film, diffusion rates for chromium through the oxide layer have been determined and a mechanism for the diffusion of chromium in the stainless-steel oxide layer is proposed.
Two-step metalorganic chemical vapor deposition growth of piezoelectric ZnO thin film on SiO2/Si substrate
Authors: Muthukumar S. , Emanetoglu N. W. , Patounakis G. , Gorla C. R. , Liang S. , Lu Y.
Published: July 2002

Piezoelectric ZnO thin films deposited on semiconductor substrates are used for surface and bulk acoustic wave and devices, which offer advantages such as low power consumption, circuit miniaturization, and cost reduction by integration with microwave monolithic integrated circuit technology. Furthermore, temperature compensated surface acoustic wave (SAW) devices, which are attractive for both communication and sensor technologies, may be achieved in the ZnO/SiO2/Si system as ZnO and Si have positive temperature coefficients of delay, while SiO2 has a negative one. In the present work, ZnO thin films were grown on SiO2/Si substrates by metalorganic chemical vapor deposition. The structural properties of the films were investigated using x-ray diffraction, scanning electron microscopy, and scanning probe microscopy. A two-step growth process was developed to obtain ZnO films with both good crystalline quality and surface morphology. The SAW properties of the ZnO/SiO2/Si system were investigated through modeling and computer simulation based on the transfer matrix method. Acoustic velocity dispersion data obtained from measurement on testing structures agree well with the dispersion curves predicted by computer simulation. The results show that the ZnO/SiO2/Si system is promising for fabricating low-loss SAW devices.
Activation of group III combinations in silicon and modifications introduced by nitrogen
Authors: Aronowitz S. , Zubkov V. , Puchner H. , Kimball J.
Published: July 2002

A series of experiments were initiated after finding that a supersteep retrograde channel of an n-channel silicon-based field effect transistor would not have an acceptable threshold voltage if created with indium and sufficient nitrogen (4×1014/cm2) present to retard gate oxide growth. A set of combinations of indium, boron, and nitrogen and a set of combinations of gallium, boron, and nitrogen were examined. It was found that nitrogen caused minimal reduction in the electrical activity of boron, greater reduction with indium, and greatest reduction with indium plus boron. Similar results, though of lesser magnitude, were observed with the gallium set. The chemical profiles of the various dopants in combination with each other gave no indication of the active carrier profile associated with each combination. Theoretical criteria were formulated to attempt to correlate atomic level configurations with electrical activity. Ab initio pseudopotential calculations using the Vienna Ab initio Simulation Package followed; the theoretical criteria correlated very well with the observed electrical activity of the various combinations and, to a lesser degree, with the ordering of nitrogen retention as a function of those combinations. The calculations appear to demonstrate the presence of long range interactions.
Dissociation of As4 molecules during molecular beam epitaxy of GaAsP on (n11)A and (n11)B GaAs substrates
Authors: Tatsuoka Y. , Uemura M. , Kitada T. , Shimomura S. , Hiyamizu S.
Published: July 2002

We investigated substrate orientation and As species dependence of GaAsxP1−x layers grown on (100), (n11)A, and (n11)B GaAs substrates (n=3, 4, and 5) by molecular beam epitaxy at a substrate temperature of 535 °C. When GaAsP layers were grown using As2 and P2 molecular beams, the As content of the layers were almost independent of the substrate orientation and were 0.92–0.94. When As4 and P2 molecular beams were supplied, the As contents of (100) and (n11)B GaAsP layers were almost constant (x∼0.88), while (n11)A GaAsP layers had smaller As contents. The (411)A GaAsP layer had the smallest As content of 0.75. Based on the process in which As4 molecules dissociate into 2As2 or vaporize on the surface, the results indicate that dissociation and vaporization of As4 is strongly dependent on the substrate orientation, while the incorporation process of As2 is almost independent of the substrate orientation. The results also strongly suggest that the B-step edges provide the effective sites for the dissociation and the adsorption of As4 molecules.
Preparation of high-pressure phase boron nitride films by physical vapor deposition
Authors: Zhu P. W. , He Z. , Zhao Y. N. , Li D. M. , Liu H. W. , Zou G. T.
Published: July 2002

The high-pressure phases boron nitride films together with cubic, wurtzic, and explosive high-pressure phases, were successfully deposited on the metal alloy substrates by tuned substrate radio frequency magnetron sputtering. The percentage of cubic boron nitride phase in the film was about 50% as calculated by Fourier transform infrared measurements. Infrared peak position of cubic boron nitride at 1006.3 cm−1, which is close to the stressless state, indicates that the film has very low internal stress. Transition electron microscope micrograph shows that pure cubic boron nitride phase exits on the surface of the film. The growth mechanism of the BN films was also discussed.
A supersonic molecular beam for gas–surface interaction studies with synchrotron radiation
Authors: Baraldi A. , Rumiz L. , Moretuzzo M. , Barnaba M. , Comelli G. , Lizzit S. , Paolucci G. , Rosei R. , Buatier de Mongeot F. , Valbusa U.
Published: July 2002

The design and first tests of a new supersonic molecular beam are presented. The instrument is dedicated to study in a controlled way the interaction of atoms and molecules with solid surfaces in combination with high-resolution core level photoemission at the SuperESCA beamline of ELETTRA, the third-generation synchrotron radiation source in Trieste, Italy. The design of the instrument together with the characterization and optimization of the molecular flux and energy resolution are discussed. As a first example of application, we present the results of a time-resolved photoemission study (O2+H2→H2O reaction) on a PtRh single-crystal alloy. Time resolution of 100 ms/spectrum has been achieved by using a double-pass electron energy analyzer equipped with a novel 96 channel detector.
Ultrahigh Vacuum for Storage Rings for 28-GeV Protons
Authors: Fischer E.
Published: July 2002

The Study Group on New Accelerators at CERN has worked out a proposal to add a pair of intersecting storage rings to the existing 28-GeV proton synchrotron. Accelerated protons injected into both rings would circulate in opposite directions and could collide in eight regions where the rings intersect. The working principle, general layout, and expected performance figures of the proposed research facility are given. The average residual gas pressure in the system must be 10−9 torr in order to have a useful lifetime of about 12 h. In the colliding beam areas even a pressure of 10−10 to 10−11 Torr is very desirable in order to keep the back-ground from residual gas scattering low enough for the observation of p-p scattering. The basic concept of the ultrahigh-vacuum system for the intersecting storage rings is described. Experimental studies on the main vacuum problems have been started.
Desorption–Adsorption of Residual Gases in Operating Electron-Tube Components as Affected by Processing Techniques
Authors: Axler M. Friedman
Published: July 2002

In a phenomenological investigation to determine the contribution to the gas ambient of traveling-wave-tube components operating in an environment simulating that of the actual tube, it was found that components comprising the gun assembly are the chief gas sources. Production-type processing procedures for reducing the gas evolution from these operating components (vacuum firing and hydrogen firing before insertion into the final subassembly) were investigated, and correlation between the sorbed gas species and these processing techniques was obtained. It is shown that gas sorption characteristics of “the reversible methane cycle” during temperature cycling (reported in the literature) are due to the presence of nickel surfaces, but that this residual gas can be essentially eliminated by the prescribed processing procedure. All experiments were performed in an ultrahigh-vacuum system with an omegatron mass spectrometer to measure partial pressures.
Some Effects of Surface Layers on the Degassing Properties of Copper
Authors: Kirkendall T. D. , Váradi P. F. , Doolittle H. D.
Published: July 2002

The effects of pretreatment and surface layers on the degassing properties of OFHC copper were investigated. With the use of a radiofrequency mass spectrometer, the throughput method of analysis was employed to measure the evolution characteristics of H2, H2O, N2, CO, and CO2. Pretreatments such as hydrogen and vacuum firing, as well as surface layers on the metal, influence the quantity and rate of gas evolution at elevated temperatures. Surface layers of copper oxide, nickel, gold, and titanium accelerate degassing. A layer of vapor-deposited titanium on the copper greatly reduces the quantity of evolved gases.
Change in Coercive Force of Detached Ferromagnetic Thin Films
Authors: Wooten F. T. , Artley J. L. , Pilkington T. C.
Published: July 2002

An experimental study has been made of the change in coercive force in thin ferromagnetic films when they are removed from a substrate. Only small changes in coercive force were observed for the iron and Permalloy films when the films were detached from the substrate. However, changes of up to 20 Oe were observed in the coercive force of nickel films. The magnitude of the change in the coercive force of nickel upon detaching the film from the substrate increased with film thickness and decreased for higher rates of thin-film deposition. The change of coercive force for nickel deposited on a substrate which has a thermal coefficient of expansion close to that of bulk nickel was essentially zero. The experimental evidence indicates that the observed changes in coercive force are due to differential thermal expansion between the substrate and the thin film.
Ultrahigh Vacuum Gauge Calibration
Authors: Davis William D.
Published: July 2002

A study was made of the problems associated with the operation and calibration of vacuum gauges at pressures below 10−10 Torr, particularly the hot-cathode magnetron gauge developed by Lafferty. A liquid-He pumped metal vacuum system was used to attain base pressures of 1×10−13 Torr. Calibration pressures were generated by molecular flow through known conductances using a McLeod gauge as the pressure standard. Under proper operating conditions, the output of the hot-cathode magnetron showed no deviation from linearity down to the base pressure of the system. Calibration curves were also obtained for a General Electric cold-cathode gauge and a mass spectrometer.
Cleanness of Glass Surfaces Measured by Evolution of Hydrogen from Sodium–Ammonia Solutions
Authors: Naiditch Sam , Wreede John E.
Published: July 2002

After cleaning with solvents and baking under vacuum, glass surfaces still contain large amounts of chemically active contaminants which can evolve into gas, degrading the vacuum, or react chemically with materials in contact with the surfaces. Surface concentrations of residual reactive contaminants were determined by measuring the quantity of gas (noncondensible with liquid nitrogen) evolved on reaction with sodium-ammonia solutions at −78 °C and with hot sodium films. These techniques were used to measure the effectiveness of wet-cleaning procedures for removal of surface contaminants, and the effects of glass composition, alkylchlorosilane surface treatment, vacuum bakeout, and sealoff on surface reactivity.
Fractionation of Ni–Cr–Cu–Al Alloys during Vacuum Evaporation
Authors: Swift Robert A. , Noval Barry A. , Merz Kenneth M.
Published: July 2002

Several apparent anomalies were found between experimental and theoretical compositions of thin films when deposited from Ni–Cr–Cu–Al alloys. Films were obtained by condensation during successive intervals of evaporation and analyses were performed by emission-spectrographic techniques. Theoretical compositions were calculated by successive approximations using Langmuir’s equation and Raoult’s law. Theoretically, the initial major components should be Al and Cr with the concentration of Cu remaining fairly constant throughout the evaporation. Experimentally, there was more Ni and Cu and less Cr in the initial films than theory predicted. The rate of evaporation of Al was strongly dependent upon the source temperature and initial compositions. These anomalies are explained by the formation of intermetallic compounds in the source. A model for the evaporation mechanism is proposed.
Measurements on Insulator-Surface Breakdown in Vacuum Under dc Voltage
Authors: Beckman L. , Jansson R.
Published: July 2002

The breakdown voltage over insulator surfaces in vacuum between plane electrodes has been investigated for different insulator materials and geometries using dc voltage. The spark current as a function of time was measured showing a current rim of 1–2 A/nsec and a slower decay. The spark is followed within a millisecond by weak discharge pulses. The time delay of these pulses indicates that they originate at the cathode.
A Novel Diode Sputter-Ion Pump
Authors: Lamont Lawrence T.
Published: July 2002

A new diode sputter-ion pump employing cathode posts which protrude within the anode cell is described. For suitable post geometry and material, stable pumping of argon at equilibrium speeds in excess of 25% of the nitrogen speed of the pump has been demonstrated. Effects of post geometry and material are explored with respect to optimizing argon speed. Pumping of noble gases is analyzed in terms of the “high-energy neutrals” hypothesis. Memory effects are shown to be reduced due to the enhancement of permanent pumping mechanisms. Field emission from the post results in greatly enhanced starting at extreme high vacuum.
Method for Determining Getter Activity in Vacuum Devices
Authors: Maley J. J. , Moscony J. J.
Published: July 2002

A commonly accepted method for determining the activity of a barium getter film within vacuum devices requires the measurement of pressure over the film. The getter pumping speed may be calculated from this measurement when the gas inlet rate and manifold pressure are known. In this work an attempt is made to evaluate the utility of determining getter activity as a function of emission decay of an oxide cathode. Mass spectrometer and emission decay data obtained from experiments carried out using either new or operated color picture tubes indicate that decay to an arbitrary level of 80%, induced by slow oxygen-poisioning, occurs rapidly within a narrow pressure range. This indicates that determination of oxygen getter capacity based on oxide-cathode emission decay may serve as an alternate method for comparing relative getter film activities.
The Photometallic Process
Authors: Burgess J. F. , Schaefer D. L.
Published: July 2002

The photometallic process is a new method of producing images in thin films of metals, semiconductors, and dielectrics. The process depends on the photogeneration of reactive material in situ which reacts with the thin film to produce a pattern.

A polymer layer containing a photodecomposable material is coated on a thin film. A pattern of light on the surface causes preferential photodecomposition and these products react with the thin film, removing it where exposed to light. The coating and reaction products are removed in a solvent rinse. A positive copy of the light image is thus obtained in the thin film. Since very close control of the photodecomposition is possible, images with continuous grey scale or various depths of reaction are possible. The process is exemplified by a description of the photoetching of gold, nichrome, and silicon dioxide. Other materials for which the process has been demonstrated are listed. A discussion of thin-film parameters, coating parameters, and proposed reaction mechanisms is presented. Among other applications, the process has potential use in microelectronic circuit fabrication.
High Current Vacuum System For Multilayer Filter Deposition
Authors: Cornelius W. L. , Martner J. G.
Published: July 2002

The development of a high-current vacuum system suitable for deposition of multilayer acoustical and optical filters is described. Eight interchangeable sources using either a “wick” heater, a double coil, or a basket-type heater are arranged for sequential deposition of low- and high-temperature metals and dielectrics. Electrical contacts to the sources are externally operated to change sources. A liquid N2 cold can is situated on top of the evaporating source and it serves to funnel the vapor stream toward the target. This arrangement saves time and unrecoverable material since it considerably reduces spillage of vapor on the interior.
High Vacuum Pump for Removing Water During Industrial Processes
Authors: Strong R. V. D. , Francksen Charles
Published: July 2002

Industrial processes frequently require the use of vacuum to remove water from products at reduced temperatures and pressures. Rotary oil-sealed pumps are often used for this duty, but unless auxiliary equipment is utilized the pumps load up with water and cannot reach required final low pressures. A new modification of the rotary oil-sealed pump incorporating special construction details, insulation to prevent undue heat loss, special lubricating and sealing fluid, and a packaged oil-temperature heating and chilling unit with oil-circulating pump and automatic oil-temperature control, now provides a unit capable of removing water from a process at any pressure level. This pump is capable of reaching final pressures well below 100μ without the use of auxiliary equipment, and can handle any water load within pump capability at all pressure levels up to 1 atm.
Solar energy—An overview
Authors: Cherne Jack M.
Published: July 2002

A survey of the potential of solar energy as a viable alternative for fossil fuels is presented. The present status of the six classes of solar energy conversion systems— (1) heating and cooling of buildings, (2) solar-thermal electric power, (3) photovoltaic power, (4) ocean thermal-gradient power, (5) bioconversion, and (6) wind energy conversion—is discussed and projections of energy costs are presented for each of these areas of development. (AIP)
Progress in computer simulation of electron guns for machining
Authors: Schuler A. , Lorenz W. , Kneidinger M.
Published: July 2002

In order to increase the power density in the spot of an electron beam by optimum designing of electrodes and lenses in the electron-optical system for electron-beam machining, a digital computer program was written. Parts of the various numerical techniques in this program, carried out on a CDC CYBER 70 Computer, are described: (1) The potential distribution was calculated with the help of the ’’extrapolated-line Liebmann method,’’ which, compared with the usual SOR method, shortened the calculation time down to a fifth and proved to be more accurate. (2) In order to examine the influence of insulators a method was developed which, with the aid of the polarization charge on the dielectric surface, was used to calculate the resulting potential distribution. (3) To calculate the electron trajectories in an electric field, a semianalytical method was devised, which, compared to the usual method (evaluating the terms in the Lorentz equation with the aid of Taylor series) produces a higher level of accuracy. (4) The calculation of the beam current density, based on the varying distances of the electron trajectories along the beam, was extended to nonlaminar beams, which made it possible to evaluate the radial current density distribution even in a spot of some micrometers diameter. Tested simple cases showed that errors are below 1%.
Abstract: Pattern generation on wafers using the electron-beam exposure system (EBES)
Authors: Henderson R. C. , Voshchenkov A. M. , Mahoney G. E.
Published: July 2002

Using the electron-beam exposure system (EBES) for direct pattern generation on wafers offers the means to make circuits with feature dimensions of only a few micrometers and alignment tolerances less than 1 μm. For such a program to be successful, techniques had to be developed to (a) rapidly register the pattern, (b) minimize the writing time, and (c) pattern the various thin films used in circuit fabrication.

For pattern registration, EBES need only determine the positions of three nonlinear fiducial marks which form a triangle spanning most of the wafer area. The position data are used to calculate the translation, rotation, skew, and magnification required to get the best fit of the old pattern to the new. The corrections are applied to the electron-beam writing operation. It takes less than two minutes to register an entire 2-in. (5.08-cm) wafer to within a ±1/2-μm accuracy.

The writing time is usually less than 20 min to expose all the chips fully covering a 2-in. (5.08-cm) Si wafer, even when there are three or four different types of circuit on the wafer. This can be achieved by laying out the chips to specifically match the EBES writing characteristics.

The resist used has been poly (glycidyl methacrylate-co-ethyl acrylate), a sensitive negative electron resist. Techniques were devised to etch patterns on many different substrates following resist development.

For pattern generation on Si wafers, the substrates included thin films of SiO2 (thermally grown as well as CVD), Si3N4, W, polysilicon, Al, and Ti–Pd–Au (see Table I). Subsequently, MOS circuits were made with combinations of the above techniques. These circuits2 include 1024-bit RAM’s, some with 5.5-μm gates, 3.0-μm contact holes, and 4.5-μm interconnecting metallization. Also, inverters, as well as discrete IGFET’s with gate lengths varying from 2 to 12 μm, were made.

EBES has also been used to delineate the thin film patterns required for GaAs MES FET fabrication (see Table II). Some devices have up to fourteen 2.5-μm gates with 2.5-μm gate-to-source spacings while others have single 2.0×500-μm gates with 2.0-μm spacings. These devices require alignment better than ±0.25 μm and metal conductors with thickness-to-width ratios as high as 1/2. Single gate MES FET’s made in this way have values of transconductance of up to 25 mmhos.
Electron-beam-delineated X-band silicon transistor
Authors: Kruger James B. , Wu You-Sun , Yuan Han-Tzong
Published: July 2002

An X-band silicon power transistor has been used to develop and demonstrate electron-beam lithography in a multilevel device with submicron geometries. The importance of an automatic registration system capable of submicron precision will be discussed. The difficulties of processing submicron geometries once they have been defined in resist and the means of addressing these problems will be reported. Dry etch processes such as plasma etch and ion milling have definite advantages. The benefits in resolution and registration of direct slice writing with an electron beam are, of course, offset in some degree by the reduced throughput caused by serial patterning. Therefore, a hybrid approach was taken, using the e beam only for the three levels in which its superior resolution and registration are critical. Photomasks are used for three noncritical levels. Comparison with a completely photolithography-defined device will be made to show the advantages in performance and yield of the e-beam device. A single-cell e-beam-generated transistor with 1/2-μm emitters has demonstrated a significant advancement in the state of the art: 230 mW cw amplifier output power with 6.7 dB gain and 25% collector efficiency (20% power added efficiency) at 10 GHz.
Mini magnetic lenses for microfocus x-ray applications
Authors: Fontijn L. A.
Published: July 2002

The mini magnetic lens is used to obtain a high-definition x-ray source positioned at the end of a long thin rod. This rod is the magnetic-lens holder which has a useful length of 315 mm and an outer diameter of 10 mm. The x-ray point source has a diameter of 0.1 mm providing a panoramic x-ray pattern with an emergent beam angle of 45° in several elevation angles dependent on the x-ray target configuration selected. Several 80- and 150-kV microfocus x-ray systems based on the mini-magnetic-lens construction are used for high-definition nondestructive x-ray inspection of small-bore large-depth welds as are found in heat exchangers for nuclear power stations.
Influence of S on the properties of electrodeposited Ni
Authors: Dini J. W. , Johnson H. R. , Saxton H. J.
Published: July 2002

The influence of sulfur content on notch sensitivity and hardness of electrodeposited nickel was determined. Charpy impact tests showed that deposits containing greater than 170 ppm of S were highly notch sensitive. Hardness was shown to be a direct function of S content; therefore, a rough approximation of S in deposits can be obtained from hardness measurements. Other techniques for identification of S (namely, wet chemistry, azide-iodine spot test, sodium-nitrate etch, and heating at 980 °C for 30 min) are discussed.
Bell-jar rf sputtering system
Authors: Rock F. C. , Smith C. W.
Published: July 2002

The general design criteria of rf sputtering systems are considered in an attempt to overcome past difficulties encountered with large, matching network-to-target distances and the use of small-diameter targets. The interest here is flexibility and high deposition rate for relatively low rf power. The design of a matching network and target assembly suitable for use in a conventional bell-jar vacuum system is presented. Results for niobium show that a deposition rate of 1100 Å/min could be realized using only 440 W of rf power.
Measurement of sorption rate for nitrogen by zirconium at elevated temperature
Authors: Nagasaka Michio
Published: July 2002

A study has been made of sorption rate for nitrogen by zirconium in the range of 10−2–10 Pa and 600°–850°C by means of the constant-volume method. Depending on nitrogen pressure, two types of rate law were observed; i.e., the linear and parabolic rate laws in the range of lower and higher pressure, respectively. The properties of nitrogen sorption under the constant-volume condition are discussed by use of Wagner’s model involving simultaneous formation of compact scale and the dissolution of nitrogen atoms into the metal bulk.
Enhancement of the dielectric constant of lead oxide by silver particles
Authors: Tokarsky R. W. , Marton J. P.
Published: July 2002

The spectral reflectivity of lead oxide on a lead substrate differs substantially from that containing fine silver particles. The latter shows interference patterns in the visible and near-infrared region. This implies that the presence of metal particles increases the dielectric constant of lead oxide markedly. The results are analyzed by the Maxwell-Garnett theory and a reasonable agreement is found. Possible applications for such composite oxides are discussed.
Features of a high-current implanter and a medium-current implanter
Authors: Ryding G. , Wittkower A. B. , Rose P. H.
Published: July 2002

In contrast to the majority of MOS circuit applications, the use of ion implantation for bipolar devices involves doping levels from 5×1013–1016 ions cm−2. This requires implantation systems with milliampere beam current capability. Some problems associated with high power beams are discussed and two contrasting systems are described. The first uses conventional electrostatic scanning techniques for beam currents up to 0.5 mA. The second operates at beam currents up to 3 mA and incorporates a fully mechanical scanning technique. In this way the high beam powers are distributed over a large effective area corresponding to 26 3-in.-diam wafers per batch.
Flowmeter for measuring gas throughput in vacuum system
Authors: Sharma J. K. N. , Sharma D. R.
Published: July 2002

A modified Stevenson-type flowmeter for measuring the throuhput of gas into a vacuum system is described.
Mass and energy analysis of incident ions to substrate during deposition by hollow cathode discharge
Authors: Komiya Souji , Yoshikawa Kideshi , Ono Shinichi
Published: July 2002

Direct measurement of mass and energy of incident ions by using an ion detector equipped with a cylindrical-mirror-type ion energy analyzer and a quadrupole mass spectrometer are carried out to reveal that physical vapor deposition by the HCD process produces a great deal of metal ions. Chromium is evaporated by an electron beam of 50 V×70 A and in argon at 0.1 Pa. Relative intensity ratio of Cr+: Ar+: Cr++ is typically 80: 16: 4, and the average ion energy of Cr+ is several to ten eV with the substrate voltage the same as that of the chamber. Analysis of incident ions during the HCD reactive evaporation of chromium by introducing acetylene or nitrogen is also carried out. For both cases, Cr+ occupies over 90% or higher; the rest is Ar+ and C2H2+ for backfilled Ar plus acetylene or Ar+ and N2+ for backfilled Ar plus nitrogen. Gas analysis during chromium evaporation reveals a marked decrease in gases including backfilled argon, acetylene, or nitrogen due to an evaporation gettering in the presence of the electron beam from the HCD gun.
Rate equation for desorbing particles
Authors: Halicioglu Timur
Published: July 2002

A rate equation describing the desorption of particles from substrates has been formulated using a simple classical model in terms of the particulate escape probabilities and escape velocities. Numerical results for desorption rates as a function of temperature using simple two-body potentials are calculated for various metallic systems. These results were obtained for the low coverage limits and are found to be in good agreement with experimental findings. The present formulation also provides an improved picture of the physical nature of the commonly discussed parameters, such as the frequency factor, desorption energy, and desorption temperature in relation to observed desorption phenomena.
Cold formed wire connector
Authors: Edwards D.
Published: July 2002

A method is described for cold forming of tungsten wire connectors by direct pressing of the tungsten wire into softer materials such as copper or aluminum. (AIP)
Vacuum-deposited thin films studied by Auger spectroscopy
Authors: Luzzi G. , Papagno L.
Published: July 2002

Crystal growth modalities during thin film deposition under vacuum are normally studied by using electronic microscopy. The scanning electron microscope, usually used for these studies, has a resolution of 50–100 Å; it is not possible to determine the dimensions of the islands or of the holes in the film structure when they are smaller than those values. Auger techniques permit one to reveal the percentage of the sample area covered by the deposition material. Some experimental results, obtained with materials largely used in thin film technology (gold and copper), are reported.
Depth selective CEMS applied to the examination of the conditions in vacuum systems
Authors: Bodlung-Ringström B. , Bäverstam U. , Bohm C.
Published: July 2002

Depth selective CEMS is used to study surface contaminations on iron in vacuum systems. In an oil-diffusion-pumped system iron carbonate was found after iron was annealed at 750°C for several hours. In a turbopumped system austenite was formed after annealing, following a long pumping period and repeated successful reduction–oxidation cycles. The depth distributions could be determined with rather good accuracy.
Studies on the thermal release of krypton from rf sputter-deposited amorphous Gd–Co films by a UHV mass spectrometric technique
Authors: Frisch M. A. , Reuter W.
Published: July 2002

High temperature mass spectrometric (HTMS) studies were made on the gas evolution caused by reordering and crystallization during the heat treatment of rf-sputter-deposited amorphous Gd0.27Co0.64Kr0.09 films. A detailed description of this HTMS system is given. Hydrogen and krypton were found to be released during the annealing process. Hydrogen precedes the krypton evolution and coincides with the partial crystallization of the film into the GdCo2 structure. After a temperature-dependent incubation period, the desorption rate for krypton rises discontinuously and then gradually decreases. During the annealing process, gadolinium diffuses to the surface, resulting in a compositional change towards GdCo2. While hydrogen exhibits only one release peak, corresponding to a single desorption mechanism, prolonged isothermal heat treatments produced at least two release mechanisms for krypton. We speculate that the initial krypton release occurs when the first continuous grain boundary to the surface is formed, allowing diffusion to proceed at a faster rate. The second, which is observed only after several hours of heating, is probably due to a reaction with the silicon substrate, forming a silicide.
Properties of thin films of Kanthal
Authors: Rawat S. D. , Shah A. S.
Published: July 2002

Vacuum deposited thin films of a Fe-Cr-Al alloy known as Kanthal have been investigated for their evaporation characteristics, composition, structure and electrical properties like electrical resistivity, temperature coefficient of resistance (TCR), thermo-emf and Hall effect. Some of the results and observations have been compared with those for the films of a Ni–Cr alloy known as Nichrome which is widely used for making commercial thin film resistors. It is shown that for making thin film resistors, Kanthal is more advantageous than Nichrome in some respects. The main advantages offered by Kanthal over Nichrome are (i) longer filament source life, (ii) higher resistivity and (iii) better evaporation characteristics yielding Kanthal films with compositions close to that of the initial charge. Other electrical characteristics like TCR and thermopwer are similar for the films of both Kanthal and Nichrome. The films showed small thermo-emf. against Al contacts below 300°C. The sign of the Hall effect was positive.
McLeod gauge: Investigations of capillary depression phenomena and mercury vapor drag effect
Authors: Sharma J. K. N. , Dwivedi H. K. , Sharma D. R.
Published: July 2002

This paper describes the accurate determination of pressure in the range 10−3–10−6 Torr (∠10−1–10−4 Pa) by a bakeable McLeod gauge using variable compression technique. A thorough investigation of two major aspects of pressure determination by a McLeod gauge, i.e., capillary depression phenomena and mercury vapor stream effect, has been made. The capillary depression phenomena in the wide bore reference arm tube has also been taken into account in determining the capillary depression correction in the compression capillary. The minimization of the error due to the vapor stream effect of mercury has been studied by cooling the cutoff point in the McLeod gauge at different temperatures, i.e., 0°, −15°, and −78 °C. The pressures thus determined are found to be accurate to ±2% or better.
UHV vacuum deposition of thin solid films
Authors: Erlings J. G. , Weerheijm H.
Published: July 2002

An apparatus for vacuum evaporation of metals at pressures in the 10−8 Pa range is described, the essential part of which consists of a liquid nitrogen cooled furnace. This device enables evaporation of metals at a residual pressure of 2×10−8 Pa.
Transition metal compound surfaces II: The tungsten trioxide single crystal surface
Authors: Langell M. A. , Bernasek S. L.
Published: July 2002

The surface properties of macroscopic single crystals of tungsten trioxide have been investigated using low energy electron diffraction and Auger electron spectroscopy. The stoichiometric (100) surface shows evidence of distortion to triclinic symmetry, indicated by a doubled feature diffraction pattern. A WO3 crystal surface grown several degrees away from the (100) plane exhibits a diffraction pattern which may be understood in terms of the formation of a [103] shear plane in the nonstoichiometric surface region. This surface is discussed in relation to the mechanism of oxidation of tungsten. Auger spectra provide support for a covalent bonding network in the WO3 surface region, similar to that observed for sodium tungsten bronzes.
Energy-selective SESD imaging utilizing a CMA
Authors: Larson L. A. , Soria F. , Poppa H.
Published: July 2002

A particularly simple conversion of a scanning Auger system for ESD ion energy distributions and scanning ESD has been developed. This approach combines the advantages of the small spot-size electron guns and mapping systems developed for SAM with the capability of ESD for the detection of hydrogen. Our intended use for the device is detection and mapping of surface concentrations of hydrogen on metals. The characteristics of SESD are illustrated with the preliminary results of an investigation into the ESD properties of hydrogenic adsorbates on Nb. It is shown that the ESDIED exhibit distinct differences indicative of the surface preparation, and that the ESD ion angular distributions have an effect on the observed contrast relationships in SESD.
Removal of volatile materials from forepump oil
Authors: Nicole Paul P.
Published: July 2002

A method of clearing condensable vapors from forepump oil is described. Air is bubbled though the oil reservoir removing volatile material from the oil and allowing continuous pumping of materials by non-vented pumps.
Anti-reflection coatings for thin-film polycrystalline CdS/Cu2S solar cells
Authors: Bragagnolo J. A. , DiNetta L.C.
Published: July 2002

Single and double-layer thin-film anti-reflection (AR) coatings have been designed and applied to CdS/Cu2S solar cells. A variety of materials, such as SiOx, Ta2O5, TiOx, ZnS, MgF2, and SiO2 have been deposited by sputtering and vacuum deposition, both reactive and nonreactive. The absorptance of the resulting AR films was found to be less than 0.01 for practical film thicknesses. Total cell reflectance, measured with a Gier–Dunkle SP 220 integrating sphere, as well as light-generated current data were used to optimize the AR coating design and deposition. Optical losses were found to be weakly dependent on the AR material or design and strongly dependent on Cu2S texture. The results are analyzed in terms of a simple planar multilayer model.
Bremsstrahlung excited Auger spectroscopy
Authors: Sundaram V. S. , Rogers J. D. , Landers R.
Published: July 2002

X-ray excited Auger spectroscopy is valuable for line shape analysis because of its high energy resolution and low background. High energy (≳1500 eV) Auger spectra are often inaccessible to photo excitation by characteristic radiation as opposed to white radiation or bremsstrahlung. We show that the bremsstrahlung and Al–Kα excited L3M45M45 Auger spectra of copper are the same. We demonstrate the utility of using bremsstrahlung by discussing the fine structure of bremsstrahlung excited M5N67N67 and M45N45N66 Auger spectra of gold.
A gap reduction technique for obtaining submicron geometries utilizing redeposition effect
Authors: Gokan H. , Esho S.
Published: July 2002

A simple technique for obtaining submicron gap patterns is described. The technique utilizes the redeposition effect in ion-beam etching. Gap widths are controlled by the thickness of the sublayer deposited on the target layer. A 0.3 μm gap width is obtained from a 0.8 μm initial photoresist gap pattern using a 0.7 μm thick sublayer. This technique is applied to the fabrications of photomasks and permalloy patterns for bubble memory. It has been confirmed that a 0.5 μm gap structure is easily obtained by this technique using conventional photolithography with 1 μm minimum feature size.