bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on an electron-beam mask-defect inspection system
Authors: Wada Y. , Hisamoto Y. , Mizukami K. , Migitaka M.
Published: July 2002

Present optical defect inspection systems cannot detect submicron defects in photomasks used for VLSI chip fabrication because of their poor resolution. The higher resolution and the fast accurate positioning abilities of an electron beam permit submicron defect inspection. This paper describes an experimental electron beam mask defect inspection system. A new blanking beam dc restoring method was developed to remove detected signal drift. Registration errors between measured pattern data and designed data are eliminated by a pseudo-defect removal algorithm newly introduced here. The signal-to-noise ratio must be larger than 10 to obtain practical reliability on inspection results. The system operates at a scanning speed of 1 μs/step and detects 0.5 μm defects using a 0.2 μm square picture element.
Auger analysis of surface deposits formed by exposure to plasma discharges in Doublet III
Authors: Smith J. N. , Meyer C. H.
Published: July 2002

A new sample transfer and analysis station, incorporating modular design features, is utilized in an initial series of studies of surface deposits produced by tokamak discharges in Doublet III. A functional description of the new apparatus is given in addition to a summary of the results of semi-quantative Auger analysis of surface deposits formed over the course of a 350 discharge period of tokamak operation, during which time Ti gettering was first employed. Excluding Ti, the deposit density can be inferred to be ∠2.3×1014 atoms cm−2 per discharge and to consist primarily of C, Ni, and O, in order of decreasing percentage. This is more than a factor of 2 less than the amount of deposition observed prior to the advent of gettering. The dominant plasma impurity radiation is associated with O.
Effect of atmospheric oxygen on evaporated chromium films
Authors: Klaus N.
Published: July 2002

The composition of thin Cr films deposited under ultrahigh vacuum conditions onto plain and surface-treated Cu foils has been investigated by SIMS. It was found that the oxygen content in the Cr–Cu transition region is determined by the oxygen concentration pressure at the Cu substrated surface. Chromium deposited in ultrahigh vacuum on heat-treated but not surface-treated Cu foils shows that the high Cu-surface oxygen concentration extends about 100 monolayers deep into the chromium film. However, for ion sputtered Cu surfaces, the region of oxygen influence is reduced to about 50 monolayers. Exposing the chromium film sample on the plain copper foil to air reveals a constant value of the Cr+ and O2− signal throughout the entire chromium film, not counting the outermost top monolayers. From the Cr–Cu transition region extending into the Cu substrate, an O2− intensity increase is recorded which is due to the high oxygen concentration at the copper foil surface. Exposure to air of the Cu surface-treated sample leads to an O2− intensity which is not constant through the entire Cr film region, but decreases monotonically to a depth of about 70 Cr monolayers. This result is interpreted to mean that oxygen moves from the oxygen-rich top Cr layer through the oxygen-depleted transition region into the Cu substrate.
Uniform evaporated coatings on rotating conical workholders
Authors: Netterfield R. P.
Published: July 2002

The uniformity of thin films evaporated on small flat substrates mounted on a conically shaped workholder rotating about its axis has been calculated. For a typical system, the nonuniformity for different substrates on the workholder can change by more than 12% if the source distribution changes from that of a point to that of a directed surface. It is shown that films uniform in thickness to within 0.1% can be produced by a stationary shutter situated below the substrates and a rotating shutter mounted between the source and the workholder. This uniformity can be maintained for both types of source distribution by a change in the height of the rotating shutter.
Effects of argon pressure on the structure of dc cylindrical magnetron sputtered thin copper films
Authors: Craig S. , Harding G. L.
Published: July 2002

A detailed study of the evolution of coating morphology during the growth of planar magnetron deposited copper films produced results in agreement with the Thronton model. Conical hillocks were observed on the surface of zone I textured films which also exhibit significantly lower reflectance for wavelengths less than 2 μm as compared with films deposited at low argon pressures. (AIP)
Anaerobic polymers as high vacuum leak sealants
Authors: Kendall B. R. F.
Published: July 2002

The behavior and properties of anaerobic polymers are summarized. Their use as high-vacuum leak sealants at temperatures up to 300 °C is discussed.
Thermally enhanced Nd:YAG laser annealing of ion implanted silicon
Authors: Wilson S. R. , Gregory R. B.
Published: July 2002

A technique for producing uniform anneals over large areas is demonstrated using a Nd:YAG laser to anneal ion implanted Si at 25°C, 100°C, and 250°C. The substrate heating enhances the absorption coefficient.(AIP)
Dual-purpose low-noise preamplifier for use with charged particle detectors
Authors: Schlier A. R.
Published: July 2002

The design specifications of the ARS1 preamp are given.(AIP)
Magnetic anisotropies of single domain particles as determined by ferromagnetic resonance (FMR)
Authors: Göpel Wolfgang , Wiechmann Bodo
Published: July 2002

Magnetic structures of single domain particles are influenced sensitively by changes in magnetic anisotropies. FMR experiments enable a determination of both, bulk and surface (or interface) contributions, to anisotropies of thin ferromagnetic films (D?100 monolayers) before and after chemisorption. FMR can also be used to characterize effective magnetic anisotropies of ensembles of particles with statistical orientation of individual anisotropies.
Determination of the InAs–GaAs(100) heterojunction band discontinuities by x-ray photoelectron spectroscopy (XPS)
Authors: Kowalczyk S. P. , Schaffer W. J. , Kraut E. A. , Grant R. W.
Published: July 2002

The valence- and conduction-band discontinuities have been determined for the InAs–GaAs (100) heterojunction (HJ) by means of XPS measurements. The values are ΔEv = 0.17±0.07 eV and ΔEc = 0.90±0.07 eV, respectively. The InAs-GaAs HJ has a rather large lattice mismatch (7%) but high quality epitaxial heterojunctions may be grown by molecular beam epitaxy (MBE). We have carried out XPS measurements on MBE grown InAs (100) films and on the InAs-GaAs (100) HJ by using a recently developed arsenic cap transfer technique which permits XPS measurements on atomically clean and ordered heterojunctions. XPS is used to obtain the In4d and As3d to valence-band maximum binding-energy differences for bulk InAs by fitting the experimental XPS valence-band density of states (VBDOS) to an instrumentally broadened theoretical VBDOS. The values are (EInAsIn4d−EInAsv) = 17.43 ±0.02 eV and (EInAsAs3d−EInAsv) = 40.77±0.02 eV, respectively. The core-level separation ΔECL between the In4d and Ga3d core levels for a thin InAs–GaAs (100) HJ is experimentally determined to be 1.55±0.06 eV.
A fail-safe automatic vent control for Pfeiffer turbomolecular pumps
Authors: Stayt J. W.
Published: July 2002

An inexpensive and easily constructed circuit is described which provides fail-safe automatic venting of turbomolecular pumps regardless of the power shutdown mode. Using Pfeiffer TCF 101 vent control unit, shutdown of the turbomolecular pump will occur with automatic delayed pump venting initiated by a power failure, and with manual venting. This paper describes a circuit modification to add an additional mode, automatic delayed pump venting activated from the front panel on/off switch, to the vent control unit. The circuit requires no additional power supplies and mounts in existing space in the control unit.
Growth and surface properties of lanthanum hexaboride crystals
Authors: Inoue Toru , Nakada Mitsuru , Uozumi Takahiko , Sugata Eizi
Published: July 2002

Single crystal lanthanum hexaboride (LaB6) has been grown in a tammann furnace. In the furnace and at 1500 K, lanthanum (La) and boron (B) are melted in proportion to the stoichiometry mass ratio in 30–45 kg/cm2 argon atmosphere. When the diffusion time at 1500 K took less, the cubical crystal grew and when it took longer, the needlelike crystal grew. The crystal growing direction was 〈100〉 for both cases. From the etch-pit observation, this crystal growth has been shown to be stratified along the direction 〈100〉 and therefore the periodic crystal growth has been certified. The height of remolded microprotrusion, which was formed on LaB6 emitter apex, was about 30 Å and the curvature radius was between 10 and 20 Å. The brightness (B) of the electron beam emitted from this remolded tip was about 1×1011 A ⋅ cm−2 ⋅ sr. This was unstable, however, because of the random walk of La atoms on the tip. Variation of the work function of platelike LaB6 tip takes a constant value beyond monolayer formation of O2 and H2 on the surface, respectively. Therefore, the LaB6 emitter is stable even in low quality of vacuum (10−7–10−8 Torr). Pyramidlike etch pit has about 30° dip angle. The etching degree defined to be the ratio of x/h was between three and four.
Chemically polished stainless steel tubing for tritium service
Authors: Gill J. T. , Moddeman W. E. , Ellefson R. E.
Published: July 2002

The need for low carbon and protium inventory at the surfaces of tritium process vacuum components has previously been demonstrated: Radiolytic methane generation and hydrogen isotope exchange lead to contamination of the tritium gas. Significant lengths of small (less than 1/2 in.) stainless steel tubing have, however, been difficult to procure or prepare in an organic-free, low surface area state. Chemical flow polishing now appears to be an appropriate method for preparation of such tubing. Three types of stainless steel (316) tubing—commercial supply house (SH), chromatography grade (CG), and flow-polished (FP) samples—have been investigated by profilometry, SEM, and AES. Surface roughness of the SH, CG, and FP samples were 38, 22, and 7 μin. rms, respectively. Relative surface areas were approx. ≥10:10:1, as were relative total carbon inventories for the SH, CG, and FP surfaces, respectively. Some contamination of the surfaces by N, P, S, and Cl was noted. These elements were present at 1 to 3 at. % on the FP sample, but did not appear significantly concentrated along intergranular regions. Increased corrosion of FP tubing over SH or CG materials was considered unlikely. Growth data of protium and methane impurities into tritium gas from surfaces similar to those of SH and FP samples demonstrate the advantages of FP tubing in tritium service.
Biased magnetron sputtering of ICF target pusher layers
Authors: Glocker David
Published: July 2002

Stalk-mounted glass microballoons with negative dc biases of up to 100 V have been coated with Cu, Ni, and Al using dc magnetron sputtering. Considerable improvement is seen in the surface smoothness and microstructure of the coatings as a result of bias. Langmuir probe measurements indicate that the electron energy distribution is non-Maxwellian, and that the plasma density is of the order 1015/m3. Enhanced metal ion bombardment of the substrates due to the nonplanar geometry is proposed to explain the results.
A technique for thick polymer coating of inertial-confinement-fusion targets
Authors: Lee Mark C. , Feng I-an , Wang Taylor G. , Kim Hyo-gun
Published: July 2002

A novel technique has been developed to coat a thick layer (15–50 μm) of polymer materials on inertial-confinement-fusion (ICF) targets. In this technique, the target and the coating material are independently positioned and manipulated. The coating material is first dissolved in an appropriate solvent to form a polymer solution. The solution is then atomized, transported, and allowed to coalesce into a droplet in a stable acoustic levitating field. The ICF target mounted on a stalk is moved into the acoustic field by manipulating a three-dimensional (3-D) positioner to penetrate the surface membrane of the droplet and thus the target is immersed in the levitated coating solution. The 3-D coordinates of the target inside the droplet are obtained using two orthogonally placed television cameras. The target is positioned at the geometric center of the droplet and maintained at that location by continuously manipulating the 3-D device until the coating layer is dried. Tests of this technique using a polymer solution have been highly successful.
Thermal stability and pore sizes of microporous zirconia gels
Authors: Rahman A. A.
Published: July 2002

A series of hydrous zirconia gels was prepared under carefully controlled conditions of pH. Porosities of the gels were characterized by adsorption studies using nitrogen (volumetric) and water vapor (gravimetric) at 77 and 298 K, respectively. The amorphous gels were predominantly microporous (pore radius <2 nm). Increasing the pH of preparation enhances the pore volume and shifts the pore size distribution to higher microporous regions. These trends were observed under two different outgassing conditions (298 and 473 K), and also using two molecular probes (N2 and H2O). The thermal stabilities of the micropores were found to diminish with decreasing micropore sizes. The role of two precipitants (a) ammonia and (b) ammonium bicarbonate is discussed in this paper. Micropore volumes available to nitrogen [V(N)] and water [V(W)] were very similar in all the gels precipitated with ammonia. While ammonium bicarbonate product showed that V(W) was eight times greater than V(N). This has been attributed to a type of ‘‘zeolitic effect’’ in zirconia gels, preferentially permitting water with its lower molecular cross section to penetrate the micropore structure. Ligands, mainly H2O, help stabilize the micropore structure in zirconia gels and thermal removal of ligands destabilizes the pore system.
The effect of oxygen and substrate temperature on the growth of Ti thin films on stainless-steel substrates
Authors: Sundgren J.-E. , Hibbs M. K. , Helmersson U. , Jacobson B. E. , Hentzell H. T. G.
Published: July 2002

The use of Ti as a biocompatible implant material has been under investigation for several years. It seems that the Ti surface has some unique properties, in this respect not fully understood. Some questions are the role and importance of the Ti–O interface layer that develops with time between the Ti implant and the bone structure and the importance of the surface structure of the Ti implant. To approach these problems we have used electron beam evaporation to prepare Ti thin films with various structural and chemical characteristics. Our goal at this step was to study only the growth of thin films of Ti deposited on stainless-steel substrates held at temperatures between 100° and 550 °C, in high vacuum, and in the presence of oxygen. AES and SEM have been used to study the film characteristics. Low temperature deposits, less than 350 °C, prepared at 1.5×10−4 Pa (1×10−6 Torr) background pressure are dense and smooth, however, with poor adhesion. Above 350 °C, the film structure is first porous but transforms at still higher temperatures again to a dense columnar structure. At these temperatures, diffusion of Fe and Cr into the Ti film is observed. Above 500 °C, a well-defined intermediate layer is formed between the substrate and the Ti film. The incorporation of oxygen into the films is dependent on substrate temperature with high amounts at low temperatures. However, the effect of oxygen incorporation on the growth morphology is most pronounced at high temperatures.
Charge-exchange wall physical erosion rates for a proposed INTOR/FED limiter
Authors: Heifetz D. , Schmidt J. , Ulrickson M. , Post D.
Published: July 2002

We have analyzed power deposition and physical erosion rates on the first wall and limiter due to charge-exchange neutrals in a proposed pump limiter design for the INTOR/FED tokamak. Plasma conditions were modeled using the one-dimensional plasma transport code baldur. Neutral transport was modeled using a two-dimensional, multispecies Monte Carlo algorithm. No chemical erosion or wall redeposition processes were included. Two possible plasma discharges with different edge densities and temperatures were modeled, a regime with Te ∼300 eV and n∼5×1012 cm−3, and a hotter, less dense edge regime produced with pellet fueling. We found that the erosion of the stainless steel vacuum vessel wall was highly localized in each case to the two points just beyond the limiter tips, and to the point directly across from the neutralizer plate, with peak erosion rates ∼2 cm/yr, assuming a 40% duty cycle. The erosion of a carbon limiter, neglecting redeposition and chemical erosion, varied in the two cases from 1.6–4 cm/yr, for the same duty cycle. The hotter, less dense discharge produced less sputtering. However achieving truly tolerable physical sputtering rates may require a very low edge temperature, plasma.
Resistive thermoconductive humidity sensor with TaN thin film
Authors: Shioyama T.
Published: July 2002

TaN thin films prepared by reactive sputtering are applied to a resistive thermoconductive type of humidity sensor. The characteristics of the sensor are as follows: The humidity sensor with TaN thin films can measure up to the absolute humidity of about 70 g/m3 in the case of the sensor heated up to 150 °C. In its response, the rise time is 10 s and the fall time is 55 s.
Interatomic Auger transitions in maximal valent V and Cr compounds
Authors: Yin Lo I , Tsang Tung , Coyle George J. , Yin Way , Adler Isidore
Published: July 2002

The Auger and x-ray photoelectron spectra of V and Cr compounds, where V and Cr exist in their maximal valence state with nominal 3d 0 electron configuration, have been studied. In these compounds, the mere presence of Auger peaks involving the 3d electrons unequivocally identifies their interatomic character. Furthermore, using ion bombardment to induce valence state reductions of transition metal ions, we are able to observe dynamically, and in situ, the interatomic to intra-atomic transitions of the Auger spectra. In particular, the intensity of the cation L3M23M45 transitions has been observed to increase dramatically with ion bombardment. The correlation between the interatomic Auger transition and covalency as well as the movements of the 3d electrons are also discussed.
Paramagnetic centers at vacuum crushed annealed silicon on exposure to oxygen and parabenzoquinone
Authors: Chung M. F. , Haneman D.
Published: July 2002

When silicon is crushed in ultrahigh vacuum (UHV) the well known electron paramagnetic resonances signal called A, at g=2.0055, and width 5–7 G is produced. Upon annealing to above the 700 °C regions, A is gradually replaced by A1, a new signal at g=2.0020 with width about 10 G and height about 1% of A. Heating above 900 °C destroys A1 and all subsequent gas effects. Exposure of silicon with A1 to oxygen or parabenzoquinone (PBQ), causes A1 to increase and the appearance of a new sharp signal C at g=2.0024 and width about 2 G. However in the case of oxygen only, another new signal called E, at g=2.0000, and width about 1 G, appears on pumping out the oxygen. This is reversible. The behavior under variations of gas exposure and of microwave power indicated that the signals are all associated with cracks and fissures, and that C is probably due to ‘‘free’’ electrons along lines of O2 or PBQ at fissure ends. The similarity of A with the EPR signal from amorphous hydrogenated silicon is now ascribed to A resulting from classical dangling bonds at the ends of fissures where the strain prevents surface reconstructions on the crack surfaces.
A low-cost cryogenic temperature controller for a VG ESCALAB V system
Authors: Shuttleworth D. , Simmonds F. L.
Published: July 2002

A modification to a VG temperature controller is described which allows for the control of subambient temperatures of sample manipulators used in ESCALAB instruments. The system developed provides stable temperature control over several hours.
A new helium sniffing device for locating very fine leaks
Authors: Murakami Y. , Shimomura Y. , Abe T. , Obara K.
Published: July 2002

A new helium sniffing method for leak checking large vacuum vessels is described. The low sensitivity problem of the conventional helium sniffing method has been overcome by increasing the gas draw rate from around leaks into the detector up to about 0.1 Pa m3/s. The devised system consists of a flexible stainless steel capillary tube 0.6 mm i.d. and 10 m long, a sorption pump using molecular sieve, and a helium leak detector in series. This method is particularly useful for locating very fine leaks down to 10−11 Pa m3/s. Relevant theoretical considerations and experimental results are presented.
Inelastic helium scattering from Ag(001) and Ag(001)c(2×2)Cl
Authors: Lambert W. R. , Trevor P. L. , Doak R. B. , Cardillo M. J.
Published: July 2002

Inelastic helium atom scattering has been used to investigate Ag(001) surface phonon modes and the influence of an adsorbed chlorine monolayer. For the Ag(001) surface we observe the preferential interaction of the He beam with shear-vertically (SV) polarized surface phonons. The scattered intensity per steradian from the Ag(001)c(2×2)Cl surface is reduced approximately two orders of magnitude compared to that for the clean surface. Our results for the chlorinated surface indicate that a SV polarized surface mode does not appear significantly below the lower bulk band edge in contrast to oxygen adsorbed on Ni(001). Although we did not observe high energy surface vibrations, based on these experiments and recent theoretical developments, we indicate conditions which would improve the observability of high energy surface vibrations by means of inelastic He scattering.
Air mass spectrometer leak detection using the special air leak test (SALT) cart
Authors: Solomon G. M.
Published: July 2002

Air mass spectrometer leak detection is being utilized in the Gas Centrifuge Enrichment Plant as a method of rapidly localizing leaks in this extremely large and complicated maze of process piping. A SALT cart has been developed to minimize the time and problems such as long time constants, helium permeation, low pumping speeds, and large helium hoods associated with helium mass spectrometer leak detection. By using the SALT cart to positively indicate the presence of air, in conjunction with process valve manipulations, leaks can be quickly localized to specific sections of piping. This process saves time and effort which would otherwise be spent helium probing nonleaky sections. Once a leak has been localized, the SALT cart can aid in pinpointing the leak using various tracer gases. A helium mass spectrometer leak detector may also be placed in series with the SALT cart taking full advantage of the SALT’s high speed and the leak detector’s high sensitivity. Cart design will be discussed in addition to testing methods and sample results.
Design considerations for achieving high vacuum integrity in fusion devices
Authors: Fuller George M. , Haines John R.
Published: July 2002

Achieving high vacuum integrity in fusion devices requires close attention to both the overall system configuration and the design details of joints and seals. This paper describes the factors in selecting the system configuration, from a vacuum standpoint, for the Princeton Plasma Physics Laboratory (PPPL) TFCX-S (toroidal fusion core experiment with all-superconducting toroidal field coils) tokamak device. The TFCX-S driven current tokamak is the eighth design in a series of tokamak concepts defined to cover the magnetic confinement and development gap between the Tokamak Fusion Test Reactor (TFTR) and the Engineering Test Reactor (ETR). The definition of a configuration that minimizes the consequences of leaks is considered a vital activity, as well as the development of leak detection concepts. A major part of the vacuum boundaries of the magnet system and the plasma system is common. For the major penetrations, primary and secondary seals are provided with vacuum control over the region between seals. The intent is to instrument these activities and provide automated recordings of these measurements for leak maintenance.
Getter pumping speed measurements in the range 10−2 to 10−7 l per s
Authors: Mehrhoff T. K. , Barnes L. W.
Published: July 2002

A procedure for measurement of getter pumping speeds several orders of magnitude below the lowest reported rates in the literature is described. The method used was found to be useful in evaluating ambient hydrogen pumping characteristics for small getters in the presence of trace contaminant gases (less than 0.13 μmol). Poisoning effects are described for the action of carbon monoxide and carbon dioxide on a zirconium–titanium nickel alloy bulk getter. Results obtained indicated that the poisoning effect is much less severe in the case of barium flash getters.
Advanced turbomolecular pumps used to pump reactive and abrasive media
Authors: Gotz D. G. , Henning H.-H. , Augustine C. M.
Published: July 2002

This paper will give a review on problems encountered when using standard turbomolecular pumps for pumping corrosive or abrasive media. It is shown how turbomolecular pumps have been modified in order to meet the specific requirements of applications such as CVD and metallizing processes. The critical parts within the pump with respect to corrosive attack are described in detail. In some cases special fluids such as polyfluorinated polyethers have been used as lubricant for the turbomolecular pump with only little improvement in performance compared with unmodified pumps. The introduction of the purge gas method into the pump design has improved the reliability of the pump considerably. Corrosive gases can no more attack the ball bearings of this special turbomolecular pump while unmodified pumps are failing already after a few days operation. Reactive ion etching processes require an increasingly high throughput of the turbomolecular pump for extended periods. It is described how a turbomolecular pump has to be modified in order to provide optimum performance in the interesting pressure range of Knudsen flow and laminar flow. By modification of the geometry of the rotor/stator configuration the throughput of the pump in that pressure range is increased considerably. It is not necessary to use larger backing pumps compared with other applications. Performance data for several turbomolecular pumps in the pressure range between 10−4 and 10 mbar are given.
Optimized process parameters for high volume wafer metallization
Authors: Reineck Stefan , Lenz Werner
Published: July 2002

In a multiwafer pallet coating process film characteristics have been evaluated using three magnetron cathodes sputtering simultaneously in an in-line production machine. Variations of discharge pressure and bias and nonbias sputtering have shown deviations in reflectivity and microstructure. The coating process has been optimized for high throughput and a high degree of reproducibility. Therefore, special attention has been paid to the use of a magnet lift system which allows process parameters to be kept constant over long time periods, even when the target becomes eroded. The background vacuum situation in the process chamber has been evaluated under the extreme conditions of loading up to 20 4 in. wafers or 12 5 in. wafers per 4.5 min into the process chamber. The initial residual gas pressure of 9×10−8 mbar can be kept at a tolerable level below 3×10−7 mbar at all times, where it turns out that the pressure increase while loading the pallet is caused mainly by degassing of water vapor. In this paper the process parameters for an in-line high production of 1 μ AlSi metallization are described. The film characteristics for a high volume production process of 265 4 in. wafers are shown.
X-ray photoelectron spectroscopy of ion beam sputter deposited SiO2, TiO2, and Ta2O5
Authors: Rossnagel S. M. , Sites J. R.
Published: July 2002

X-ray photoelectron spectroscopy (XPS) was used to examine the atomic bonding in thin oxide films used in reflection enhancing optical coatings. SiO2 was deposited by ion beam sputtering of quartz; TiO2 and Ta2O5 were deposited by ion beam sputtering of metal targets. In each case, an increased oxygen background pressure was used to achieve the desired stoichiometry. All three types of films are amorphous as measured by TEM and by x-ray diffraction and have an optical absorption below 100 parts per million for half-wave thicknesses at 1.06 μm. Depth profiles have been performed on each of the films and some layered structures. The XPS data for each film as deposited shows a single bonding state and no evidence of suboxides above approximately a 5% level. The O 1s line in SiO2 is broader (2.5 eV) than in evaporated SiO2, and is not altered by the ion bombardment of the depth profiling process. The O ls line broadens, however, by up to 50% at a SiO2/TiO2 interface. Sputter-deposited TiO2 and Ta2O5 show a relatively narrow (1.7 eV) O 1s line. Neither the composition nor the bonding in SiO2 is affected by sputter etching with Ar+ at 3 keV. In TiO2, however, oxygen is preferentially sputtered and suboxides observed in the XPS spectrum. With Ta2O5, oxygen is also diminished, but only Ta2O5 and metallic Ta are seen in the XPS spectra.
Characterization of plasma deposited halocarbon polymer films containing small gold particles
Authors: Martinů L. , Biederman H.
Published: July 2002

Composite thin films were prepared by simultaneous plasma polymerization of chlorotrifluoroethylene and sputtering of gold in an rf glow discharge (20 MHz) excited by a planar magnetron. The concentration depth profile analyses including AES and ESCA have disclosed that the amount of fluorine and chlorine decreases with increasing gold concentration and that the film surface is not representative for the bulk of the layer. Structural examination using TEM observations evidenced that gold is incorporated in an amorphous polymer matrix in the form of polycrystalline grains 10–20 nm in diameter in the case of low film filling factors ( f ≲0.1). Two particle size systems have been found at higher filling factors when the grain diameters reached about 130 nm ( f ∼0.5). Spectral dependence of the absorption coefficient is described in terms of optical resonance. A hypothesis of energetic particle bombardment of the growing layer was suggested to explain the film structure and composition.
An Auger and depth profiling study of the sulfidation of iron and Fe-25 wt. % Cr alloy in H2S
Authors: Narayan P. B. V. , Bevolo A. J. , Chen C. W. , Carlson O. N.
Published: July 2002

Polycrystalline iron and an Fe-25 wt. % Cr alloy were exposed from 200 to 300 °C in an H2S–argon mixture at one atmosphere pressure. Depth profiling was conducted on the sulfidized specimen in an Auger spectrometer. For both Fe and the Fe–Cr alloy temperature had a much stronger effect than exposure time on the growth rate of the sulfide layer. The sulfidation rate of the Fe–Cr alloy was much lower than that for pure iron. Evidence from the depth profile indicates that the growth of the sulfide layer below 250 °C proceeds primarily by the difffusion of iron rather than sulfur ions through the scale.
Fabrication of coils with high aspect ratios for thin-film magnetic heads
Authors: Shiiki Kazuo , Yuitoo Isamu , Shiroishi Yoshihiro
Published: July 2002

A new method of fabricating densely wound thin-film coils with high aspect ratios has been developed for thin-film magnetic heads. The processing steps are (1) thick polyimide resin spin coated on a substrate is patterned by reactive sputter etching using a finely patterned Mo mask; (2) conducting material of almost the same thickness as the polyimide resin is evaporated on to the patterned layer; (3) the Mo mask and conducting material formed on the Mo mask are selectively removed by electrochemical etching; and (4) polyimide resin is spin coated to smooth the surface of the coil layer. The Mo mask and polyimide resin can be patterned with an accuracy of better than 0.1 μm by selecting the appropriate etching conditions. A thick coil with 4 μm linewidth, 2 μm height, and 2 μm space between conductors can be produced and embedded in polyimide resin. The surface roughness of the resin over the coil is less than 0.2 μm.
Stability improvement of TaN thin films used as resistive thermoconductive vacuum gauges
Authors: Shioyama Tadayoshi
Published: July 2002

TaN thin films used as resistive thermoconductive vacuum gauges are prepared by reactive ion beam sputtering. We examine the stability of TaN thin films deposited at the substrate temperature up to 800 °C. Moreover, we consider the relation between the stability and the accuracy of the vacuum gauge. As a result, we obtain the TaN thin films with high stability such that the resistance change after aging for 1000 h in air at 150 °C is only 0.08%. This resistance change corresponds to the pressure error of 2×10−3 Torr for the vacuum gauge.
Electrical properties of D–T gas and liquid
Authors: Souers P. C. , Fearon E. M. , Tsugawa R. T.
Published: July 2002

New electrical conductivity and dielectric data for D–T gas at room temperature and densities of 10 to 120 mol/m3 at 1592 Hz are reported. These plus earlier cryogenic gas and liquid data are reinterpreted in terms of space charging, which is present in almost all samples. This effect concentrates electric charge near the plates to cause an excess dielectric constant, and it also diminishes electrical conductivity by cancelling much of the external electric field. The mobilities of electrons and ions, plus their recombination coefficients, are included in the model. The effect of the 1592 Hz signal is also considered. Gas phase results are consistent with the presence of electrons, but the liquid may contain both electrons and negative ions.
Structural and electrical characterization of thin polyoxides for nonvolatile memory applications
Authors: Shih W. , Wang C. , Chiao S. , Chen L. , Wu N. , Batra T. , Kao J. C. , Wu O. K.
Published: July 2002

The quality of oxide grown from polysilicon is strongly dependent on phosphorus doping and polyoxide growth conditions. For dry polyoxide, when the poly oxidation temperature is below 1100 °C, the thin second polyoxide (the polyoxide regrown after the first polyoxide was removed) grown on phosphorus-doped polysilicon has a lower breakdown field than the thin first polyoxide. Direct evidence from SEM micrographs shows the asperities on polysilicon surface after removing the first polyoxide and second polyoxide were quite different. Although the grain size is larger after the second poly oxidation, the height of the asperities seems to increase more rapidly. This is consistent with our electrical data. The tradeoff and optimization of the process parameters to obtain a high integrity thin polyoxide for nonvolatile memory devices are discussed.
Process integration issues for a 0.25 μm n-channel metal-oxide-semiconductor technology
Authors: Mele T. C. , Scarpulla J. , Nulman J. , Krusius J. P.
Published: July 2002

Process integration issues for the gate structure and channel region of the enhancement mode device within a fully self-aligned 0.25 μm NMOS technology are discussed. The optimized process gives a polysilicon (poly) gate electrode with a resistivity of 0.02 Ω-cm, a midgap interface trap density of 2×1011 eV−1 cm−2, and a catastrophic breakdown field greater than 10 MV/cm for the 11.5 nm gate oxide. The annealing conditions that provide an n+ poly gate with the correct work function and low resistivity compatible with a thin gate oxide are described. Shallow channel implant broadening effects on device characteristics have been studied with simulations and fabricated devices.
Low temperature epitaxy by ionized-cluster beam
Authors: Yamada I. , Takaoka H. , Usui H. , Takagi T.
Published: July 2002

Ionized cluster beam deposition offers the capability of introducing useful kinetic energy and chemical activity during film formation processes. This allows high quality epitaxy of materials at low temperature onto a wide variety of substrate surfaces and even permits the formation of thin film materials not previously possible. Capabilities are demonstrated by epitaxial Al films on various kinds of substrates, very large area deposition of GaAs, composition controlled Cd1−xMnxTe films, and CdTe/PbTe multilayer epitaxial films.
Evolution of the glow discharge, deposition rate, and film conductivity with target erosion using direct current reactive sputtering
Authors: Fortier N. , Parsons R. R.
Published: July 2002

Films of nonstoichiometric aluminum nitride have been prepared using ‘‘voltage-control’’ reactive sputtering. The influence of the target erosion on the glow discharge, deposition rate, and film conductivity is examined. The use of a reactive gas baffle is shown to improve reproducibility of film properties.
A high performance molecular beam epitaxy system equipped with the automatic substrate transport mechanism
Authors: Ueda S. , Kamohara H. , Ishikawa Y. , Tamura N. , Katoo S. , Shiraki Y.
Published: July 2002

A novel molecular beam epitaxy (MBE) is designed not only for laboratory use but also for the study of its anticipated performance in commercial production of compound semiconductor devices. The system is composed of five chambers, where the operations of deposition, preparation/analysis, transfer, loading, and unloading are carried out. The deposition and the preparation chambers can be evacuated to the level of <6.7×10−9 Pa, and transfer chamber less than 6.7×10−8 Pa. These high levels of vacuum could be reached by the development of a high performance turbomolecular pump (TMP), the use of high quality stainless steel as the structural material of the chambers, and the preparatory practice which reduced the outgassing rate to less than 1.3×10−10 Pa m3 s−1 m−2. The system can handle a substrate of up to 3 in. in diameter. The whole operation of the substrate transfer is controlled by a personal computer. The heating temperature of the substrate can be raised to 800 °C, and the maximum rotational speed of the substrate holder is 120 rpm. Many high quality thin films can be grown in this system. For example, on a GaAs and an AlGaAs epitaxial growth, the following figures were obtained; the Hall mobility 8150 cm2 V−1 s−1, the carrier concentration 1×1014–2×1018 cm−3, the film thickness and mole fraction uniformity for 3 in. substrate ±5%. These figures demonstrate the capability of the present system in fabrication of most GaAs devices.
Ion scattering spectroscopy and Auger electron spectroscopy depth profiles of silver–copper thin film interdiffusion
Authors: Pitts J. R. , Czanderna A. W. , Thomas T. M.
Published: July 2002

Bilayers of Ag/Cu or Cu/Ag have been vacuum deposited in situ onto cleaned quartz, Si(100), and copper substrates at thicknesses from 20 to 50 nm, as measured with a quartz crystal oscillator. Depth profiles on the same samples were obtained using neon bombardment and either ion scattering spectroscopy (ISS) or Auger electron spectroscopy (AES) for compositional analysis. Profiles were taken after deposition at 30 °C and then after heating up to 300 °C, all in situ at about 20 nPa. Interdiffusion was detectable at 100 °C for both Ag/Cu and Cu/Ag bilayers, but differences were found in the extent of the diffusion. Dramatic differences were found in ISS and AES profiles of bilayers on silica and copper substrates. The differences are attributed to electron beam effects that result in profiles similar to those induced by thermal treatments at much higher temperatures. Reasons why the ISS profiles better represent the true in-depth composition are given.
Transparent carbon films: Comparison of properties between ion- and plasma-deposition processes
Authors: Pellicori S. F. , Peterson C. M. , Henson T. P.
Published: July 2002

Optical, electrical, and mechanical measurements were made on transparent carbon films prepared by two different techniques: Ion sputtering of graphite with argon ion co-bombardment and rf plasma decomposition of hydrocarbon compounds. A comparison between the properties of films deposited by each technique is presented. The films deposited by the plasma process were more transparent, had a lower refractive index, and showed less mechanical stress than the sputtered films. They were softer and electrically less stable than the ion-sputtered films. Both processes produced films having very low charge density and high resistivity. The simplicity of the plasma process and the ability to cover larger areas makes it the preferred process for the protective coating of optical surfaces on a production basis.
Rheotaxial growth of CuInSe2 thin films
Authors: Varela M. , Bertran E. , Lousa A. , Esteve J. , Morenza J. L.
Published: July 2002

CuInSe2 thin films were deposited onto glass and liquid-indium-coated glass substrates by coevaporation of copper, indium, and selenium. The morphology, composition, and crystalline properties have been studied in relation to the deposition process parameters. The deposition rate and the grain size are higher in films grown on liquid indium than on glass and depend on the indium film thickness. Films grown on indium do not show the same crystalline phases of films grown on glass, and in order to obtain films free of spurious phases the Cu fluxes must be increased.
Fragmentation spectra and appearance potentials of vacuum pump fluids determined by electron impact mass spectrometry
Authors: D’Anna E. , Leggieri G. , Luches A. , Perrone A.
Published: July 2002

Three different vacuum pump fluid (Fomblin Y-VAC 18/8, Santovac 5, and DC 704) vapors were subjected to electron bombardment at energies from 10 to 90 eV. The fragmentation spectra were recorded with a quadrupole mass spectrometer. The appearance potentials of the most abundant fragments were determined. The experimental results show very good stability of the Fomblin vapors under electron bombardment.
Auger electron spectroscopy–electron energy-loss spectroscopy–low-energy electron diffraction study of a V6C5(100) surface
Authors: Usami S. , Nakai H. , Yaguchi T. , Kumashiro Y. , Fujimori A.
Published: July 2002

The surface properties of (100) oriented substoichiometric vanadium carbide V6C5 was examined by electron spectroscopy and low-energy electron diffraction (LEED) observation. The electron energy-loss spectroscopy (EELS) spectra for a clean surface of the crystal showed similar features to those of a TiC(100) except for the loss region of less than 10 eV. In the LEED experiment, however, rather complicated patterns appeared contrary to the case of TiC(100), which indicated only fundamental lattice structure. The displacement of LEED spots with the energy variation of primary electron suggested that the surface was formed with two different kinds of facet planes. The carbides in general are inactive against common gases, while reactive particles such as oxygen interact with these materials. The irradiation of atomic hydrogen onto the specimen, however, causes no significant changes either in the compositional ratio of vanadium versus carbon or in LEED patterns. In the EELS spectra, by atomic hydrogen irradiation, the 3-eV loss peak disappeared, while a new peak near the 10-eV loss peak appeared, suggesting that atomic hydrogen could interact with this surface.
Adsorption site identification in surface extended x-ray absorption fine structure
Authors: Crapper M. D. , Woodruff D. P.
Published: July 2002

Adsorption sites and adsorbate–substrate bondlengths are usually deduced from surface extended x-ray absorption fine structure (EXAFS) by a Fourier filtering approach. We discuss here the merits and problems of an alternative method involving simulations of the EXAFS which include the role of several scattering shells. With the aid of specific examples we show that even in simple cases this approach can add to or reinforce the normal structural conclusions but in the case of overlapping contributions from two or more bondlengths the simulation approach is the only one which is truly satisfactory. Molecular adsorbates, such as formate (HCOO), will invariably suffer from this difficulty due to the mismatch of intramolecular and intrasubstrate bondlengths, forcing individual atoms in the molecule to adopt low-symmetry adsorption sites.
Preparation of Ge–Pb–O thin films by radio frequency reactive sputtering
Authors: Umezawa T. , Sasaki K.
Published: July 2002

Dielectric properties of germanium oxide have not been investigated in detail. We have examined preliminary investigations on Ge–O films deposited by rf reactive sputtering. The dissipation factor of Ge–O films prepared ranges from 0.005 to 0.003, which is satisfactory as a low-loss dielectric material. Ge–O film corresponding to the lowest tan δ has the nearest composition to stoichiometric GeO2. Aiming at obtaining the higher value of the dielectric constant, we have attempted to fabricate Ge–Pb–O films. The value of the dielectric constant of Ge–Pb–O film can be varied from 7 to 20 by varying Pb content in films, in spite of nearly constant value of tan δ (0.0035). By x-ray diffraction study, it is revealed that Pb atoms in Ge–Pb–O films are taken into lattice sites as a phase of Pb2GeO4 or PbO2. We consider that the Pb2GeO4 phase formed in Ge–Pb–O films behaves as a mixture of GeO2 and 2PbO. It can be pointed out that the origin of the increase of the dielectric constant observed with increasing Pb content in films is due to the existence of a PbO or PbO2 phase.
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u transmission electron microscopy annealing of NiCr thin films with simultaneous Hall-voltage measurement
Authors: Tóth L. , Barna Á. , Sáfrán G.
Published: July 2002

Flash-evaporated NiCr thin films of 50/50 composition have been annealed in situ in a transmission electron microscope (TEM). The design of the sample holder and specimen geometry allowed the TEM observation of the resistor film and the simultaneous measurement of the resistance as well as of the Hall voltage on the same sample. Isothermal annealing cycles performed subsequently at 670, 760, and 830 K resulted in characteristic changes of the structure and electrical transport properties of the films. In NiCr films annealed in oxidizing atmosphere selective surface oxidation of Cr has been detected leading to the enrichment of Ni in the conducting phase. In samples annealed under a protecting SiOx layer, however, equilibrium phase transformation of the Ni–Cr system was observed. The measured Hall coefficients are interpreted in terms of the chemical composition of the phases formed due to the above treatments.
Studies of layered thin films of Prussian-blue-type compounds
Authors: Siperko Lorraine M. , Kuwana Theodore
Published: July 2002

Electrochemical and spectroscopic studies of layered Prussian blue (PB) and analogous cupric hexacyanoferrate (CuHCF) films indicate that charge transfer occurs across the film/film interface but the electrochemical response generated by a slowly ramped potential perturbation is dependent upon the placement of the films. When a PB film is deposited upon a CuHCF film, cracks appear at the outermost surface; however, the resulting response to the perturbation is merely a superposition of the two i–E waves. No cracking occurs when the layers are reversed (CuHCF on PB) but the resulting i–E wave is distorted. Possible causes for the distortion are proposed and discussed with respect to scanning electron microscopy/energy dispersive x-ray analysis results.