Papers by Keyword: Sputter Deposition

Abstract: Experiments are described towards optimizing tantalum silicide (TaSi₂) interconnect metal film sputter-deposition and annealing in a manner compatible with the NASA Glenn two-layer interconnect silicon carbide (SiC) JFET-R IC process flow. Films deposited on 100 mm diameter wafers were investigated over a range of film thickness, sputter deposition, and post-deposition anneal conditions. An optimized process that achieved TaSi₂ films free of cracking and morphological defects while nearly halving post-anneal stress was developed and will be used for completing the interconnect fabrication of prototype IC Gen. 12 SiC JFET-R ICs.

Abstract: As a promising third generation semiconductor material, gallium nitride (GaN) has become a research hotspot in optoelectronic field nowadays. In this paper, GaN thin films were grown by radio frequency (RF) planar magnetron sputtering of a powder GaN target in a pure nitrogen atmosphere at (0.2 – 2.0) Pa, (10 - 100) W onto various substrates such as GaAs (100), Si (100), Si (111), Al₂O₃(0001) and glass without any buffer layer. A clear phase transition from the metastable cubic zinc-blende (c - ZB) to the stable hexagonal wurtzite (h - WZ) dependence on substrates has been found in the GaN thin films. And the phase transition of GaN films were studied by X-ray diffraction (XRD), photoluminescence (PL) and Raman spectroscopy.

Abstract: In this paper, we report on the performance of Ti/4H-SiC Schottky junctions, whereas the contact material is either e-beam evaporated or magnetron sputter deposited. When applying the first technique, the Schottky barrier height is lowered at room temperature by about 80 meV or by about 160 meV extracted from current/voltage and capacitance/voltage measurements, respectively. Furthermore, e-beam evaporation of the Ti contact results in an ideality factor closer to 1 when comparing structures of the same design.

Abstract: Granular Co_100-xCu_x films with different compositions of x = 19, 40, 54, 65 and 76 were deposited on glass substrates using sputter deposition. Co (HCP) and Cu (FCC) phases were observed in all deposited Co-Cu films. Film thickness was increased with increasing Cu-composition. The minimum and maximum values of electrical resistance measured using a four-point probe were observed on the Co₂₄Cu₇₆ and Co₄₆Cu₅₄ films, respectively, which confirmed that the electrical property of the films is a function of the film thickness and composition. The morphological and magnetic properties of all deposited films were clearly dependent on film composition. The AFM result confirmed the dependence of surface morphology and magnetic properties on the film composition because of the difference in the deposition rate between Co and Cu atoms during the sputtering process. The VSM results showed that all films had a ferromagnetic phase when the magnetic field was applied perpendicular to the film plane. All results confirmed that the desired morphological, electrical and magnetic properties of Co-Cu granular film can be achieved by manipulating its chemical composition.

Abstract: Color glasses are fabricated with Titanium target by RF magnetron sputtering. The physical properties of the Ti thin films are investigated according to preparation conditions, such as argon and oxygen gas flow ratio, RF power and Working pressure. The results indicate that it is possible to deposits various Ti thin film’s of different colors on glass substrate, such as yellow, orange, brown, purple. The thickness according to the color was analyzed using Veeco's Stylus profiler (model: dektak 6M).

Abstract: In this study, polycrystalline aluminum nanoscale thin sheets are constructed by sputter deposition simulations with the molecular dynamics (MD) simulation. Subsequently, the penetration problem of a conical rigid projectile moving through the aluminum thin sheet is simulated by the MD technique. The MD simulations adopted the interatomic potential of a tight-binding type. During the deposition simulation, in order to include the ion-ion interactions, the pair-wise Moliere potential was adopted to model the interaction between working gas argon and deposited atoms. The as-deposited films did not show clear grain boundaries, but after thermal annealing, grains grow and form nanocrystalline structure with a grain size of 8 nm. The thin sheets consisted of the face-centered cubic phases of crystal unit cells, separated by grain boundaries. For the penetration simulations, four velocities were chosen 10², 10³, 10⁴ and 10⁵ m/s. The first two velocities are called high velocity case and the rest two velocities are the hypervelocity case. Our results show that, as the penetration rate increases, more stresses are required to move the projectile through the Al film due to temperature effects from the high velocity to hypervelocity case. In addition, defects, such as dislocations, increase during the projectile penetration. In the high velocity case, the penetrated hole in the film may be recovered, but not in the hypervelocity case. The temperature difference increased in the hypervelocity case is significantly than that in the high velocity case.

Abstract: In microelectromechanical systems, piezoelectric aluminum nitride (AlN) thin films are commonly used as functional material for sensing and actuating purposes. This is due to excellent dielectric properties as well as a high chemical and thermal stability of AlN. In this work, we investigate the leakage current behavior (i.e. IV characteristic and charging behavior) of AlN thin films sputter deposited at varying plasma powers (300 W – 800 W) and deposition pressures (4 µbar – 8 µbar) up to an electric field of 0.5 MV/cm. First results show a Poole-Frenkel behavior for all samples with an increase in leakage current by orders of magnitude as the degree of c-axis orientation decreases. In addition, the discharging curves (i.e. meaning the current discharge after an applied constant electric field) agree well with the empirical Curie - von Schweidler Law (I(t) = I₀ + I₁t^-n) and an increase of the parameter I₁ with temperature is observed. I₁ shows qualitatively the same behavior as the overall stored charge. Furthermore, the results show a strong negative correlation between the parameters n and the time constant τ_1/2 (i.e. defined as the time after which half the stored charge has decayed), proofing that n is a good indicator for the decay time of the stored charge.

Abstract: The oxidation resistance of ferritic-martensitic 9% chromium steels in water vapour containing atmospheres is not yet satisfactory. The chromia layer provides little protection because water vapour in the atmosphere is known to promote the formation of the volatile chromium species CrO₂(OH)₂. If a chromium manganese spinel is formed instead, the vapour pressure of the oxy-hydroxide is greatly reduced and evaporation can largely be avoided. Enrichment of the substrate with manganese was achieved using three different processes: using (i) a sputtering technique, (ii) electrochemical deposition both followed by a diffusion heat treatment, (iii) the pack cementation method. Uniform diffusion of manganese was obtained with all of the investigated processes. The improved oxidation behaviour of the coated samples in synthetic air with 10% water vapour at 650°C was demonstrated.

Abstract: Thin films of Au were made by sputter deposition onto glass substrates with and without transparent and electrically conducting layers of SnO2:In. The Au films were up to ~11 nm in thickness and covered the range for thin film growth from discrete islands, via large scale coalescence and formation of a meandering conducting network, to the formation of a more or less “holey” film. Scanning electron microscopy and atomic force microscopy showed that the SnO2:In films were considerably rougher than the glass itself. This roughness influenced the Au film formation so that large scale coalescence set in at a somewhat larger thickness for films on SnO2:In than on glass. Measurements of spectral optical transmittance and electrical resistance could be reconciled with impeded Au film formation on the SnO2:In layer, leading to pronounced “plateaus” in the near infrared optical properties for Au films on SnO2:In and an accompanying change from such two-layer films having a lower resistance than the single gold film at thicknesses below large scale coalescence to the opposite behavior for larger film thicknesses.

Abstract: Sputter deposited Fe0.7Co0.3 nitride thin film had zinc blende structure. It was thermally decomposed completely back to the ferromagnetic Fe0.7Co0.3 alloy above 400°C. As-deposited nitride thin films obtained in cosputtering of (Fe0.7Co0.3)1-xAlx composite target with nitrogen sputter gas were solid solutions with zinc blende (x≤0.44) and wurtzite (x>0.5) type structure, respectively. The largest magneto resistance ratio of 0.24% was observed on the Fe0.7Co0.3 alloy particles dispersed in AlN thin film obtained by thermal decomposition of the nitride solid solution with x=0.66 at 500°C.