Deposition Geometry Research Articles

A substrate temperature measurement system for use during rf diode sputtering

A substrate temperature measurement system is described, which has proved useful for measuring substrate temperature in situ in an rf diode sputtering system. This temperature measurement system mimics the true deposition materials, geometry, and thermal contact as much as possible. The measurement electronics are quite insensitive to rf interference and allow for cancellation of lead resistance and thermoelectric voltages.

Growth of CuInSe 2 by two magnetron sputtering techniques

The results of experiments characterizing CuInSe 2 deposition by reactive magnetron sputtering and by a hybrid sputtering and evaporation technique are presented. Both techniques produce films with chemical and structural properties comparable with those commonly used for polycrystalline CuInSe 2-based solar cells. The reactive sputtering technique produces films with compositions ranging from copper rich to indium rich with near-stoichiometric selenium contents at low temperatures. Indium-rich films cannot be produced at temperatures above about 400°C. The hybrid process produces films over a large composition range at growth temperatures up to 450°C. Film compositions are uniform across 25 mm substrates to within ±1 at.% and non-uniformities can be directly related to the deposition geometry. For hybrid films, the selenium flux is shown to play a major role in determining both the selenium and the indium contents of the films at elevated temperatures. A coupled In-Se desorption mechanism which is inhibited by the presence of large amounts of excess selenium is proposed to explain the latter data. The substrate material is shown to affect strongly the film chemistry. Films deposited on copper show a higher copper content due to diffusion of the substrate material into the film during growth. Layers deposited by the hybrid process on molybdenum exhibit lower indium and higher selenium contents than films on glass at all temperatures examined. Finally, copper, indium and selenium diffusion into molybdenum substrates was observed at all growth temperatures.

Studies on Ion Scattering and Sputtering Processes Relevant to Ion Beam Sputter Deposition of Multicomponent Thin Films

ABSTRACTResults from computer simulation and experiments on ion scattering and sputtering processes in ion beam sputter deposition of high Tc superconducting and ferroelectric thin films are presented. It is demonstrated that scattering of neutralized ions from the targets can result in undesirable erosion of, and inert gas incorporation in, the growing films, depending on the ion/target atom mass ratio and ion beam angle of incidence/target/substrate geometry. The studies indicate that sputtering by Kr+ or Xe+ ions is preferable to the most commonly used Ar+ ions, since the undesirable phenomena mentioned above are minimized for the first two ions. These results are used to determine optimum sputter deposition geometry and ion beam parameters for growing multicomponent oxide thin films by ion beam sputter-deposition.

Nucleation and epitaxial growth of Cr crystals on stepped W surfaces with low-index facets

The nucleation and epitaxial growth of Cr overlayers and crystals have been studied by vapor depositing chromium onto thermally annealed W field electron emitters, which provide highly stepped substrates with low-index facets of various atomic configurations. Temperature and substrate morphology effects were identified and Cr/W epitaxial relationships were determined. In addition to the common Stranski-Krastanov (SK) nucleation mechanism (nucleation on top of a Cr overlayer) observed generally above ∼ 500 K, low temperature Cr nucleation and growth (∼300 K) was observed on the W{110} planes. This process proceeded via either the SK or Volmer-Weber (VW) (nucleation directly on the substrate) mechanisms, depending upon the Cr deposition geometry. The influence of oxygen contamination is identified and comparisons to recent Cr/W(100) and Cr/W(110) work are made.

Stress and microstructure of sputter-deposited thin films: Molecular dynamics investigations

In magnetron sputter deposition the intrinsic mechanical stress of films of refractory metals passes a tensile stress maximum, decreases and then becomes compressive with decreasing working gas pressure. To elucidate the dependence of internal tensile stress on film growth and microstructure, a two-dimensional molecular dynamics simulation is employed. The evolving structure is determined at an atomic level and the stress is calculated as a function of the kinetic energy of adatoms and fast neutralized inert gas atoms which arrive at the film surface. These energies are dependent on the deposition geometry and the working gas pressure. The theoretical results are in qualitative agreement with experiment and reveal that the initial increase in tensile stress with increasing adatom and neutral incident kinetic energy is caused by a microstructural change from microcolumnar growth to a more densely packed atomic network with closed micropores. Interatomic attractive forces producing tensile stress can act most effectively in such a structure. The subsequent decrease in stress is attributed to a less defect-rich, better ordered absorbate structure formed at higher kinetic energies of arriving species. Stress is found to vary in a similar fashion as a function of incident kinetic energy for both sputtered atoms and fast neutrals. The compressive stress regime has not been investigated.

Ramp-Style Deposition of Oligocene Marine Vedder Formation, San Joaquin Valley, California: ABSTRACT

The Oligocene Vedder formation consists of well-sorted medium to fine-grained marine sand and shale in the subsurface of the eastern San Joaquin Valley. Updip, this formation interfingers with nonmarine/lagoonal facies known as the Walker Formation. This relationship appears to be transgressive because the marine Vedder generally overlies the Walker Formation. Downdip, the Vedder sands interfinger with middle to lower bathyal shale in a progradational manner, forming upward-coarsening patterns in well logs. Depositional water depths for the shale were determined from benthic foraminifera assemblages. The Vedder formation is approximately 750 ft thick along its updip part, and gradually thickens to 1500 ft downdip. Overall deposition geometry, determined from well-log correlations and seismic data, is generally parallel and downlapping. A prominent shelf-slope break is not evident. Rather, depositional surfaces are tabular or broadly lobate, with a depositional slope of 5/sup 0/-10/sup 0/. This geometry of constant slope between nonmarine and deep marine water depth is termed a ramp. The depositional style and geometry are similar to that of the Oligocene upper Pleito Formation, which crops out in the San Emigdio Mountains on the southern margin of the San Joaquin Valley. The Vedder formation was deposited subsequent to a period of rapid subsidencemore » (about 50 cm/1000 years), as determined from geohistory analysis of well data on the Bakersfield arch. This rapid subsidence may have induced deposition in a ramp geometry, rather than a shelf-slope configuration.« less

Layers for ion beam energy conversion into black body radiation

The radiation hydrodynamics of material layers for energy conversion of intense ion beams into black body radiation is investigated, both analytically and numerically. Conversion efficiency and hydrodynamic losses are the main topics. The basic scaling relations are derived and compared with computer simulations. Although the analysis is done for slab geometry, a generalization to converters of arbitrary shape and deposition geometry is outlined. The code MINIRA is briefly described. The influence of varying layer density, optical thickness and beam power on radiation emission as well as the effect of Bragg peak deposition are discussed in detail. High conversion efficiencies of more than 50% can be obtained provided that the converter is operated in the radiative regime. For typical beam intensities, this requires low-density layers. Another essential feature is supersonic heat transport which occurs in the radiative regime.

Angular variation of the coercivity in magnetic recording thin films

Coercivity of vacuum-deposited magnetic thin films of CoCr and CoNi is dependent on deposition geometries and other deposition conditions. The angular variation of coercivity shows three types of behavior: bell-, M-, and shifted M-type curves. The displacement-controlled nucleation and growth of reverse domains dominates the coercivity mechanism. The shifted M-type angular-dependent coercivity in the oblique-deposited thin film is related to the out-of-plane magnetic anisotropy, and the shift angle is correlated to the angle of the easy axis, which is out of the film plane but not coincident with the axis of the canted columnar structure.

The soft X-ray detection efficiency of coated microchannel plates

An improved model of the soft X-ray quantum detection efficiency of microchannel plate electron multipliers is presented. The model takes account of the low-energy secondary component of the photoelectric yield and therefore can be used to study microchannel plates bearing high-yield deposition photocathodes such as CsI. Experimental data and theoretical calculations are presented for both front surface and open area contributions to the detection efficiency. The effects of vacuum deposition geometry on the uniformity of response of coated plates are discussed.

Laser Photolytic Deposition of Thin Films

ABSTRACTAn excimer laser is used to photochemically deposit thin films of silicon dioxide, silicon nitride, aluminum oxide, and zinc oxide at low temperatures (100–350deg;C). Deposition rates in excess of 3000 Å/min and conformal coverage over vertical walled steps were demonstrated. The films exhibit low defect density and high breakdown voltage and have been characterized using IR spectrophotometry, AES, and C-V analysis. Device compatibility has been studied by using photodeposited films as interlayer dielectrics, diffusion masks, and passivation layers in production CMOS devices.Additionally, we have deposited metallic films of Al, Mo, W, and Cr over large (>5 cm2) areas using UV photodissociation of trimethylaluminum and the refractory metal hexacarbonyls. Both shiny metallic films as well as black particulate films were obtained depending on the deposition geometry. The black films are shown to grow in columnar grains. The depositions were made at room temperature over pyrex and quartz plates as well as silicon wafers. We have examined the resistivity, adhesion, stress and step coverage of these films. The films exhibited resistivities at most ∼20 times that of the bulk materials and tensile stress no higher than 7 × 109 dynes/cm2

Influence of Evaporation‐Deposition Geometry on Conductive Thin Films

There is a striking dependence of the evaporation deposition geometry (i.e. angular distribution of the incident vapor beam) on the properties of deposited conductive films. This paper discusses solderability, adhesion and long‐term stability of adhesion of Ti‐Pd‐Au, Ti‐Au and Ti‐Cu films. In all cases the above properties were improved by an evaporation deposition geometry with steep angles of the incident vapor beam.

A versatile system for controlled electron-beam deposition of thin films

A versatile system for vacuum deposition of thin films employing one or two linear self-accelerated electron-beam guns was designed and constructed. Commercially available components, modified when necessary, were used possible. An original design was employed for the overall deposition geometry including an 8-stage rotatable water-cooled vapour-source holder and an 8-stage rotatable temperature-controlled substrate-holder. Provision was made for differential pumping on the electron-beam column and automatic pressure control of various blead-in gases in the working chamber.

New methods for the determination of roller wear. (in Polish) : Inz. J. Spyra. Wiadomosci Hutnicze, 16 (1960) 110–116

The deposition of high wear- and corrosion-resistant alloys through Plasma Transferred Arc (PTA) is an easily automated process combining the possibility to obtain very thick coatings with high deposition speeds, low thermal distortion of the part and negligible dilution levels, thanks to a very high energy-concentration [S. Kalpakjian, S.R. Schmid, Manufacturing Engineering and Technology—4th edition, Addison-Wesley Publishing, 2001, p. 789–790, Scripta Materialia 37 (1997) 721, Applied Surface Science 201 (2002) 154, Surface and Coatings Technology 71 (1995) 196, Journal of Materials Processing Technology 128 (2002) 169, M. Bonacini, Plasma ad arco trasferito per riporti saldati con superleghe in polvere, “Saldatura e taglio termico verso il 2000” IIS Meeting, October 3rd 1998, Milan-Italy, Wear 250 (2001) 611, Wear 249 (2002) 846, Composites Science and Technology 58 (1998) 299]. Literature studies regard mostly wear or high temperature behaviour of the deposited alloys and plasma hardening treatment without powder [Applied Surface Science 201 (2002) 154, Surface and Coatings Technology 71 (1995) 196, Journal of Materials Processing Technology 128 (2002) 169, M. Bonacini, Plasma ad arco trasferito per riporti saldati con superleghe in polvere, “Saldatura e taglio termico verso il 2000” IIS Meeting, October 3rd 1998, Milan-Italy, Wear 250 (2001) 611, Surface and Coatings Technology 106 (1998) 156, Wear 249 (2002) 846, Surface and Coatings Technology 92 (1997) 157, Wear 181–183 (1995) 810, Wear 225–229 (1999) 1114], rather than an optimisation of process parameters, also in critical geometric configurations. An experimental campaign has been carried out on the deposition of two nickel- and a cobalt-base superalloys: Hastelloy 276, Inconel 625 and Stellite 6. Benchmarks of C-Mn steel have been chosen to test geometrical configurations that are critical for the application (corners and grooves). Specimen characterisation through liquid penetration inspection, optical- and scanning electron microscopy and microhardness tests proved that process parameters optimisation depends only on the geometrical configuration and not on the deposited alloy. This result suggests the importance of an accurate design of the reciprocal positioning and movement between the torch and the part to be coated, as a function of the deposition geometry.