Showing papers on "Sputter deposition published in 1985"

Group III Impurity Doped Zinc Oxide Thin Films Prepared by RF Magnetron Sputtering

Abstract: The detailed study of electrical properties in group III impurity doped ZnO thin films prepared by rf magnetron sputtering is described. The resistivity is lowered by doping of B, Al, Ga and In into ZnO films. The characteristic features of ZnO films doped with group III elements except for B are their high carrier concentration and low mobility. Variation of the mobility with the impurity content is roughly governed by the ionized impurity scattering. It is shown that the doped ZnO films exhibit the resistivity dependence on film thickness below 300 nm.

Effects of oxygen content on the optical properties of tantalum oxide films deposited by ion-beam sputtering.

Abstract: Ion-beam sputter deposition of tantalum oxide films was investigated for possible optical coating applications. Optical properties of such films were found to be a sensitive function of oxygen-to-argon ratio in the ion beam. Refractive index and absorption coefficient were determined in the 250–2000-nm wavelength range by spectrophotometric transmissivity. The different bonding states of the tantalum atoms were revealed by x-ray photoelectron spectroscopy. The visible wavelength refractive index was found to be 2.18 and optical band gap 4.3 eV, so long as the films did not contain inclusions of metallic tantalum. Films with an admixture of oxygen deficient suboxide components had a low-energy tail of increasing magnitude in the absorption spectrum.

High efficiency indium tin oxide/indium phosphide solar cells

Abstract: Improvements in the performance of indium tin oxide (ITO)/indium phosphide solar cells have been realized by the dc magnetron sputter deposition of n-ITO onto an epitaxial p/p(+) structure grown on commercial p(+) bulk substrates. The highest efficiency cells were achieved when the surface of the epilayer was exposed to an Ar/H2 plasma before depositing the bulk of the ITO in a more typical Ar/O2 plasma. With H2 processing, global efficiencies of 18.9 percent were achieved. It is suggested that the excellent performance of these solar cells results from the optimization of the doping, thickness, transport, and surface properties of the p-type base, as well as from better control over the ITO deposition procedure.

Diamondlike amorphous carbon films prepared by magnetron sputtering of graphite

Abstract: Amorphous carbon films, a‐C, were prepared by employing dc magnetron sputtering of a graphite target in an argon plasma. A series of a‐C films were deposited as a function of sputtering power. The power was varied in the range 5–500 W and the target effective sputtering area was about 20 cm2. The physical and optical properties of the a‐C films show a dependence on the sputtering power. The films, although unhydrogenated, possess diamondlike properties such as high hardness, HV=1200–2400 kgf mm−2, and are transparent in the infrared (IR) region with optical gap Eopt =0.40–0.74 eV. We observe a systematic variation of film properties with increasing sputtering power which suggest a transition from fourfold (diamondlike) to threefold (graphitic) coordination of the carbon atoms. For films prepared at low sputtering power about 3/4 of the carbon atoms have tetrahedral coordination and 1/4 have trigonal coordination. At the highest sputtering power the a‐C films consist of equal mixtures of tetrahedrally and ...

Optical Properties of Aluminum Doped Zinc Oxide Thin Films Prepared by RF Magnetron Sputtering

Abstract: The detailed study of optical transmittance and reflectance in Al-doped ZnO thin films prepared by rf magnetron sputtering is described. Films obtained with Al2O3 content up to 10 wt% showed an average transmittance above 85% in the visible range. The absorption edge was blue-shifted with increasing carrier concentration. The shift was interpreted to be a result of competition between many body effects and the Burstein-Moss effect. It is shown that films obtained with an Al2O3 content of 1–2 wt% can achieve an excellent IR shielding.

The effects of hydrogenation on the properties of ion beam sputter deposited amorphous carbon

Abstract: The incorporation of hydrogen in ion beam sputtered carbon profoundly affects the physical properties of the amorphous film. Optical absorption, electrical conductivity, and ESR measurements suggest that incorporated hydrogen efficiently passifies the dangling bonds and saturates the graphitic bonding to some extent. By single ion beam sputter deposition, amorphous carbon films containing up to 35 at. % of hydrogen were obtained. This material acts as a narrow band gap (1.2 eV) semiconductor with a relatively low density of states but has an abundance of unsaturated sp2 bonding. In fact, 13C‐NMR measurements on this material show that the sp2/sp3 bonding ratio is about 1.5. High density and extreme hardness are properties of ion beam deposited carbon films which contain little or no hydrogen. However, the physical properties of such amorphous carbon which, due to its unique mechanical properties is sometimes referred to as amorphous diamond, are largely dominated by the unsaturated graphitic bonding.

rf sputtering of highly Bi‐substituted garnet films on glass substrates for magneto‐optic memory

Abstract: Using glass substrates, we have prepared highly Bi‐substituted garnet [(Bi,Y,Fe,Al)8O12 and (Bi,Gd,Fe,Al)8O12] films by rf diode sputtering which was followed by annealing for crystallization. The films were polycrystalline garnet with no preferred orientation and no impurity crystalline phase detectable by x‐ray analysis, which contained 1.1–1.4 Bi ions per formula unit. The films crystallized directly during the sputter deposition when the substrate temperature Ts>440 °C. Film quality was best when Ts was just below 440 °C. The film had magnetic anisotropy perpendicular to the film plane, which is stress induced. In the (Bi,Gd,Fe,Al)8O12 film, the magnetization normal to the film plane exhibited strong coercivity, Hc=600 Oe, and a large remanence‐to‐saturation ratio, Mr/Ms=1, while in the (Bi,Y,Fe,Al)8O12 film, weak Hc (200 Oe) and small Mr/Ms (0.47). These films had large Faraday rotation, typically 1.5×104 deg/cm at λ=633 nm, owing to the high Bi substitution.

Properties of Hydrogenated Amorphous Si-N Prepared by Various Methods

Abstract: The results of optical absorption, infrared absorption, electron spin resonance and photoluminescence measurements are presented for hydrogenated amorphous Si-N films prepared by three different methods; magnetron sputtering of an Si target in an Ar+N2+H2 gas mixture, glow-discharge decomposition of SiH4+N2, and glow-discharge decomposition of SiH4+NH3 The improvement in the properties of films prepared by the third method, eg, the sharp band tail and low dangling-bond density, is explained mainly in terms of the structual softening due to the existence of N-H bonds The fatigue of the photoluminescence due to illumination is found to be more prominent and the recovery due to annealing less prominent in N-incorporated film than in a-Si:H

Layered and homogeneous films of aluminum and aluminum/silicon with titanium and tungsten for multilevel interconnects

Abstract: Layered structures and homogeneous alloy films synthesized by sputter deposition were investigated for use in a VLSI multilevel interconnect technology. Major areas studied include hillock formation, resistivity before and after annealing, film composition and structure, reproducibility, interlevel shorts, and dry etching. It has been demonstrated in this work that aluminum alloyed with silicon and titanium and layered with titanium offers advantages over current technological materials for interconnections in integrated circuits. Measurements of surface roughness and electrical shorts between two levels of metal showed that the hillock densities in the films are significantly reduced when small amounts (one to three atomic percent) of titanium and silicon are present. The resistivity of such homogeneous films, however, is 4.5 to 5.5 µΩ.cm, which is higher than standard metallization alloys. When Al/Si was layered with Ti, no hillocks were observed and the resistivity of the composite films was comparable to standard metallization alloys.

Growth of diamond at room temperature by an ion‐beam sputter deposition under hydrogen‐ion bombardment

Abstract: The structure and crystal phase of carbon films prepared by an ion‐beam sputter deposition were studied. The properties of the deposited carbon films were influenced by a hydrogen‐ion bombardment during the film growth. It is noted that the hydrogen‐ion bombardment activates the growth of diamond in the deposited carbon film. Diamond particles of 0.1∼1 μm in diameter, which showed well‐defined morphology of diamond, were successfully grown at room temperature on nondiamond substrates.

Hollow cathode enhanced magnetron sputter device

Abstract: A plasma sputter etching/deposition system comprising an electron-emitting hollow cathode arc-source combined with a conventional plasma sputter etching/deposition system such as a magnetron. The electrons emitted are coupled into the intrinsic high energy, e.g., magnetic field and are accelerated by the plasma potential and cause a significant increase plasma density. The resultant combination allows much greater sputtering/deposition efficiency than was possible with previous devices. According to a further aspect of the invention, switched operation is possible, whereby etching may vary from isotropic to anisotropic. A side discharge hollow cathode structure is also described for enhancing certain sputtering/deposition processes, wherein electrons may be emitted from one or more openings at the side of a hollow cathode chamber to achieve more uniform electron emission in a large process chamber.

Planar Deposition of Aluminum by RF/DC Sputtering with RF Bias

Abstract: Planarization of multilevel interconnection is most effective for achieving a higher packing density. However, it is shown by computer simulation that degradation of metallization step coverage becomes serious as th via aspect ratio increases. Conventional deposition methods, in which emitted particles flow onto the substrate and usually do not migrate, are shown to be inadequate for maintaining sufficient step coverage. A new deposition technique, RF/dc sputtering with RF bias for metal, is developed and found to provide sufficient step coverage and, moreover, planarity. In an application of the technique to aluminum film deposition, the existence of a resputtering effect was confirmed. Aluminum particles were found to deposit primarily near the bottom of the depressions and to fill up th depressions completely, through sputtering at a high bias. Steep, deep grooves and vias with aspect ratios up to were found to be completely filled with the aluminum film by deposition at resputtering rates higher than 50%. It was also found that substrate biasing has a decisive effect on giving aluminum films an almost complete (111) crystallographic texture.

NbN tunnel junctions

Abstract: All-Niobium Nitride Josephson junctions have been prepared successfully using a new processing called SNOP : Selective Niobium (Nitride) Overlap Process. Such a process involves the "trilayer" deposition on the whole wafer before selective patterning of the electrodes by optically controlled Dry Reactive Ion Etching. Only two photomask levels are need to define an "overlap" or a "cross-type" junction with a good accuracy. The properties of the Niobium Nitride films deposited by DC-Magnetron sputtering and the surface oxide growth are analysed. The most critical point to obtain high quality and high gap value junctions resides in the early stage of the NbN counterelectrode growth. Some possibilities to overcome such a handicap exist even if the fabrication needs substrate temperatures below 250 °C.

Environmentally induced restructuring of polymer surfaces and its influence on their wetting characteristics in an aqueous environment

Abstract: In the conventional methods of estimating the wetting characteristics of solids from contact angle experiments, the surface energetic properties of the solid are assumed to be identical in the environments of both the surrounding medium and probe fluids. While this assumption is suitable for solids which possess rigid surface structures (such as glasses, ceramics, and metals for example), it is generally inapplicable to polymeric solids, since the surfaces of the latter are relatively mobile so as to be able to adopt considerably different configurations in different environments. Based on a recognition of this feature of polymeric surfaces, a sequence of contact angle experiments is suggested to estimate: (a) the instantaneous as well as equilibrium surface energetic properties of a polymeric solid in an aqueous environment and (b) the time required for the polymeric surface to attain its equilibrium wetting characteristics in the aqueous environment. In order to illustrate the applicability of the suggested contact angle procedure, it is necessary to prepare model polymeric surfaces, which are smooth in surface texture, nonporous, and also chemically homogeneous. Such model surfaces were prepared in this study, by radio frequency sputter deposition of thin solid films of oxidized fluorocarbon compounds (from a Teflon FEP target) onto the smooth surfaces of highly polished, single crystal silicon substrates. The estimation of the wetting characteristics of the sputtered polymer films in an aqueous environment was then carried out by the suggested contact angle procedure. The results of the contact angle experiments indicate that the solid-water interfacial free energy of the sputtered polymer film which was initially equilibrated in an octane environment, decreases from an instantaneous value of 50.88 dyn/cm to an equilibrium value of 26.59 dyn/cm, over a duration of about 24 h. Such a change in the solid-water interfacial free energy of these model polymeric surfaces can arise due to a time-dependent reorientation of the buried polar groups of the solid from its bulk to its surface, when it is placed in contact with a strongly polar liquid like water. This interpretation was found to be consistent with the results of ESCA characterization, which indicated that the outer surface layers of the sputtered polymeric specimen contained a fair amount of the polar oxygen atoms that are capable of reorienting themselves from either the interior of the solid to its surface or vice versa, depending on their surrounding environment.

Coating film and method and apparatus for producing the same

Abstract: A coating film comprises an amorphous carbon of a specified atomic ratio with respect to hydrogen and carbon and it is excellent in hardness, oxidation resistance, thermal resistance, electric resistance and thermal conductivity. The coating film is produced by sputtering a graphite target electrode in an atmosphere of hydrogen, fluorine or a mixture of hydrogen and fluorides having a gas pressure of 6.665 to 666.5 Pa (0.05 to 5.0 Torr) while maintaining the relative current density for the graphite target electrode and a power source between 11.3 and 14.7 ma/cm2 thereby limiting the H/C ratio in terms of an atomic ratio between 0.5 and 0.9. A sputtering apparatus used for producing such coating film includes a coating forming deposition substrate arranged at a position within a sputtering vacuum container which is not directly exposed to a plasma or a deposition substrate mounted on an electron drawing electrode within the container and a plasma adjusting electrode positioned in front of the substrate.

Angular resolved x‐ray photoelectron spectroscopy study of reactively sputtered titanium nitride

Abstract: Moisture and O2 levels present during the reactive sputtering deposition of TiN have a marked impact on measured contact resistance Results of an angular resolved x‐ray photoelectron spectroscopy (XPS) study of sputter deposited TiN as well as Auger electron spectroscopy (AES) show that oxynitrides are the predominant surface species on TiN Two distinct oxynitride phases with different oxygen contents have been observed on TiN and the relative abundance of each phase appears to be a function of H2O and oxygen levels present during reactive sputtering

Superconducting and structure properties of niobium nitride prepared by rf magnetron sputtering

Abstract: The properties of rf‐magnetron‐sputtered NbN have been investigated for substrate temperatures from 200°C to 750°C as a function of the partial pressure of methane introduced into the Ar–N2 sputtering gas mixture The best films were prepared at elevated substrate temperatures with approximately 2% methane added to the sputter gas These films also had resistivities approximately 70 μΩ cm At lower substrate temperature, T∼200°C, the best attained Tc was approximately 133 K with a resistivity of 140 μΩ cm The crystal structure of these materials was investigated using x‐ray diffraction and Read x‐ray photographs Those films prepared with no added methane were found to be two‐phase δ and e NbN The addition of a small amount of methane produced single δ phase NbN with a predominant (200) preferrential orientation The δ phase lattice parameter was determined to vary approximately from 439 A to 445 A as the amount of methane was increased The effect of hydrogen doping on NbN was to produce multiphase

Plasma assisted physical vapor deposition processes: A review

Abstract: Increasing use has been made in thin film technology of physical and chemical phenomena occurring in low pressure plasmas which are convenient i n s i t usources of activated gas and energetic ions to be used as additional process parameters in film growth,structure, and properties. Energetic ions and/or activated species in the vapor phase are now employed in processes for surface treatment (ion nitriding and carburizing), deposition(sputtering, ion plating, activated reactive evaporation, and plasma polymerization) and also for etching (sputtering and plasma etching). In recent years, therefore, considerable efforts have been directed to the analysis of plasma conditions and their correlation with deposited film properties. In this paper, we present a review of plasma‐assisted physical vapor deposition processes (PAPVD) used for the deposition of refractory compounds for the two basic PAPVD processes, (i.e., activated reactive evaporation and reactive sputtering). The film growth mechanism and the role of plasmas in these processes will be compared in terms of three steps in deposition processes; synthesis of the deposition species, transport from source to substrate, and film growth.

Method and apparatus for microwave assisting sputtering

Abstract: Disclosed herein are apparatuses of several types for forming a film at an increased rate that is necessary for putting the microwave assisting sputtering into practice on an industrial scale. The feature resides in that a plasma is maintained uniformly on the whole surface of target composed of a material to be sputtered. This makes it possible to avoid the target from being thermally destroyed by the increased energy of sputtering. Further, in order to prevent damage on a substrate on which the film is to be sputtered by plasma for sputtering, consideration is given to the arrangement of magnetic devices in order to form the film by positively introducing the plasma onto the substrate on which the film is to be formed and, at the same time, effecting the sputtering. There are further disclosed an apparatus in which the plasma is generated by microwaves at a position close to the target to effectively utilize the energy of microwaves for the sputtering, and a cathode structure on which a conical target is placed by taking into consideration the fact that the sputtered particles emitted from the target travel in compliance with the cosine law.

Properties of high rate sputtered perpendicular recording media

Abstract: Double layered media for perpendicular magnetic recording were made by dc magnetron sputtering. The coercivity of the Co‐Cr layer was independent of deposition rate over the range from 0.006 to 1.2 μm/min, when the substrate temperature was kept constant during sputtering. Micro columnar structure of the Co‐Cr film was studied by chemical etching. Only the columns were dissolved leaving the column boundaries showing a microhoneycomb structure. From the composition analysis of the etchant, Cr segregated column boundaries were confirmed to exist even in the high rate sputtered films. The Permalloy back layer with coercivity below 1 Oe shows large noise pulses in the reproducing process. Increasing the coercivity to several Oersteds reduced the noise to the amplifier noise level without changing the signal level. Finally, a high recording performance was obtained for the media made by high rate sputtering.

High Tc superconducting NbN films deposited at room temperature

Abstract: The dc reactive magnetron sputtering process yields stoichiometric NbN films with superconducting transition temperature T(c) as high as 15.7 K on substrates as varied as glass, glazed ceramic, fused quartz, and sapphire. These films posses fcc (B1) structure and (111) texture. The most dominant factors governing the formation of the transition metal nitrides are the relative metal and nitrogen fluxes incident on the substrate and the background argon pressure (which dictates the overall reactive sites and residence times for nitrogen).

Layered and Homogeneous Films of Aluminum and Aluminum/Silicon with Titanium and Tungsten for Multilevel Interconnects

Abstract: Layered structures and homogeneous alloy films synthesized by sputter deposition were investigated for use in a VLSI multilevel interconnect technology. Major areas studied include hillock formation, resistivity before and after annealing, film composition and structure, reproducibility, interlevel shorts, and dry etching. It has been demonstrated in this work that aluminum alloyed with silicon and titanium and layered with titanium offers advantages over current technological materials for interconnections in integrated circuits. Measurements of surface roughness and electrical shorts between two levels of metal showed that the hillock densities in the films are significantly reduced when small amounts (one to three atomic percent) of titanium and silicon are present. The resistivity of such homogeneous films, however, is 4.5 to 5.5 /spl mu//spl Omega//spl dot/cm, which is higher than standard metallization alloys. When Al/Si was layered with Ti, no hillocks were observed and the resistivity of the composite films was comparable to standard metallization alloys.

In-situ cleaned ohmic contacts

Abstract: A process of forming improved ohmic contacts is disclosed. Substrates having contact openings formed in a dielectric layer thereon are cleaned under vacuum with HF/H2 O vapor wherein the temperature of the vapor is at least about 5° C. lower than that of the substrate. The cleaned substrates are then metallized in-situ in a closed system, e.g. by magnetron sputtering, thus preventing air from contacting the substrate. The cleaning and metallization each require about one minute, thus making the process suitable for efficient, large-scale operation.

Application of NbN films to the development of very high field superconducting magnets

Abstract: We report the preliminary results of a program recently begun at Argonne National Laboratory to demonstrate the feasibility of using niobium nitride (NbN) films as practical high field superconductors. Films of varying thicknesses (2-9 μm) have been deposited on sapphire and Hastelloy substrates, using d.c. magnetron sputtering. The superconducting transition temperatures T c of these films range from 12-15 K. Using the WHH extrapolation, upper critical fields H c2 (O) up to 36 T in the parallel direction and 43T in the perpendicular direction were obtained. Critical current densities J c (H,4.2 K) were \approx 1\times10^{4} A/cm2at 20 T in both the parallel and perpendicular directions. The preliminary results from novel sample preparation technique for TEM studies of film cross-sections is briefly described. This technique shows the variation in film structure as a function of distance from the substrate.

Low temperature reactive sputter deposition of vanadium oxide

Abstract: In the present study, vanadium oxide films were grown on water‐cooled sapphire, silicon, and glass substrates by reactive sputter deposition using a vanadium target and rf‐excited argon discharges containing 0%–25% oxygen. Optical emission spectroscopy was used for in situ discharge diagnostics. Films were characterized by x‐ray diffraction to determine crystallography and by double‐beam spectrophotometry to determine optical absorption behavior in the 200–1200 nm spectral region. The results show that film crystallography evolves from single (110) orientation body‐centered cubic vanadium to single (001) orientation orthorhombic vanadium pentoxide to a material in which there is no long range atomic order detectable by x‐ray diffraction as the sputtering gas oxygen content is increased. Changes in optical absorption behavior which accompany the decrease in atomic order are presented and discussed.

Bismuth iron garnet films prepared by rf magnetron sputtering

Abstract: We report on the growth of highly bismuth‐substituted iron garnet films by rf magnetron sputtering in a pure argon plasma. Under special conditions the target composition is fully reproduced in the films. Film homogeneity in the noncrystalline state is excellent. Crystallization on lattice‐matched garnet substrates occurring during growth above 520 °C substrate temperature and by post‐annealing above 650 °C yields the garnet phase, as inferred from the optical and magneto‐optic spectra and the saturation magnetization. Residual imperfections appearing after crystallization need further elucidation. We cope with the extreme disparity in the elemental sputter yields of the mixture Gd‐Bi‐Fe‐Al‐Ga‐O by (i) protecting the growing film from ion bombardment in using a magnetron source and (ii) binding Bi to a more slowly sputtering species, such as in BiFeO3.