Showing papers on "Chemical vapor deposition published in 1983"

Production of large‐area single‐crystal wafers of cubic SiC for semiconductor devices

Abstract: A reproducible process is described for growing a thick single-crystal layer of cubic SiC on a single-crystal Si wafer by chemical vapor deposition. A buffer layer, grown in situ, is used between the cubic SiC and the Si substrate to minimize the effect of lattice mismatch. Layers of up to 34 microns thick and several sq cm in area have been grown. Wafers are obtained by chemically removing the Si substrates from the grown layers. Excellent electron channeling patterns produced by these wafers indicate very good crystal quality. Preliminary electrical measurements have yielded electron mobilities up to 380 sq cm/Vs.

rf‐plasma deposited amorphous hydrogenated hard carbon thin films: Preparation, properties, and applications

Abstract: The deposition of amorphous hydrogenated hard carbon (a–C:H) thin films from benzene vapor in a rf plasma is described. a–C:H was deposited on glass, quartz, Si, Ge, and GaAs. Negative self‐bias VB and gas pressure P are shown to be the two significant parameters for an accurate control of the deposition process. The dependence of growth rate and deposition temperature on VB and P was determined; this gives an empirical relation for the average energy E of the ions forming the thin films. Refractive index (1.85–2.20 in the IR), optical gap (0.8–1.8 eV) and density (1.5–1.8 g/cm3) of a–C:H was measured. The optical gap varies linearly with the content of bonded hydrogen in the films. The density of a–C:H is proportional to the average ion energy E. We demonstrate the application of a–C:H as antireflective coating on Ge for 10.6 μm (reflection <0.2% at 10.6 μm) and as terminating layer of an optical multilayer stack.

Optical and crystallographic properties and impurity incorporation of GaxIn1−xAs (0.44<x<0.49) grown by liquid phase epitaxy, vapor phase epitaxy, and metal organic chemical vapor deposition

Abstract: Optical, crystallographic, and transport properties of nominally undoped n‐type and Zn doped p‐type Gax In1−xAs /InP (0.44

Low Temperature Chemical Vapor Deposition Method Utilizing an Electron Cyclotron Resonance Plasma

Abstract: The plasma deposition apparatus developed in this study can realize a deposition of dense and high quality thin films, such as Si3N4 and SiO2, without the need for substrate heating. It does this by enhancing the plasma excitation efficiency at low gas pressures (10-4 Torr) and by the acceleration effect of ions with moderate energies (10 to 20 eV), using a microwave ECR (Electron Cyclotron Resonance) excited plasma, and a plasma stream extraction onto the specimen table by a divergent magnetic field method. The Si3N4 and SiO2 films deposited are comparable to those prepared by high temperature CVD and thermal oxidation, respectively, in evaluations such as by buffered HF solution etch rate measurement.

Deposition of GaAs Epitaxial Layers by Organometallic CVD Temperature and Orientation Dependence

Abstract: Epitaxial layers of have been grown in an atmospheric organometallic CVD system, for a wide variety of gas phase reactant partial pressures and over a broad range of temperature (450°–1050°C). The growth rates for (100), , (110), (11l)Ga, and (11l)As substrates are reported as functions of temperature and gas composition. Three distinct temperature dependent regions of growth are identified, corresponding to a mid‐temperature mass transport limited range, a low‐temperature kinetic controlled regime, and a high‐temperature desorption limited region. The growth rate is studied as a function of the growth parameters and substrate orientation, and is related to the decomposition of the two reactants trimethylgallium and arsine. A model for the epitaxial growth of by the organometallic process is proposed, based on these findings.

Method of producing titanium nitride MOS device gate electrode

Abstract: An MOS device having a gate electrode and interconnect of titanium nitride and especially titanium nitride which is formed by low pressure chemical vapor deposition In a more specific embodiment the titanium nitride gate electrode and interconnect have a silicon layer thereover to improve oxidation protection

A technique for the determination of stress in thin films

Abstract: Intrinsic stress, elastic bulk modulus, and yield strength of thin films has been determined by measuring the deformation versus pressure of circular membranes of the materials. Low pressure chemical vapor deposited (LPCVD) silicon‐rich silicon nitride (SiNx) has been extensively characterized and found to have an intrinsic stress of ∼1×109 dyn/cm2 and a bulk modulus of ∼1.9×1012 dyn/cm2. A SiNx membrane 1.0 cm in diameter and 1.0 μm thick has been found to survive a differential pressure of 470 Torr with no measurable plastic deformation. Experimental data for several different types of silicon nitride membranes is given. It is shown that the stress measurement technique can be extended to measure accurately the intrinsic stress of thin films deposited onto SiNx membranes.

On the Reaction Mechanism of GaAs MOCVD

Abstract: In this paper, the reaction mechanisms of metalorganic chemical vapor deposition (MOCVD) have been investigated using infrared absorption spectroscopy. The growth of from Ga and under gas atmosphere in a hot wall reactor was studied. The compositions of gases which are sampled through a quartz capillary are observed by infrared spectroscopy. Infrared spectra of , , and systems were measured in the range from room temperature to 930°C. In the system, a new absorption peak at 2080 cm−1 which exists in neither the nor the system is observed. In the system, when is added into the reacting gas, the concentration of decreases drastically. The decomposition of is affected strongly by the addition of .

Formation and Characterization of Transition-Metal Silicides

Abstract: Publisher Summary This chapter focuses on formation and characterization of transition-metal silicides. Many deposition techniques can be applied to form thin silicide layers on very large-scale integration (VLSI) structures. The common methods are vacuum evaporation with filament or e-gun, sputtering, and chemical vapor deposition. The silicon for the silicide may be drawn from the silicon substrate in a subsequent metal-silicon reaction, in which case a metal film only is deposited. Modern methods of analysis of thin films are mainly based on the detection of beams that are emitted from or scattered by the film as a result of irradiation by a primary incident beam. Several transition metal silicides have been identified as semiconductors. The relatively high resistivity of these silicides and the ability to vary the resistivity and the thermal coefficient of resistance makes these materials attractive for thin-film resistors.

Structural properties of titanium dioxide films deposited in an rf glow discharge

Abstract: An rf glow discharge has been used to promote the reaction between titanium tetrachloride and oxygen in order to deposit thin films of titanium dioxide at low temperatures. Structural properties of the films have been studied as functions of deposition temperature (25 to 700 °C) and of substrate material (Si, sapphire, glass, NaCl, and Ti). Films deposited onto glass substrates were amorphous at temperatures less than 300 °C, anatase at 300 and 400 °C, a mixture of anatase and rutile at 500 °C, and only rutile at 600 °C and above. Films deposited on the other substrates showed similar behavior but the temperatures for specific crystalline forms differed for each substrate material. Deposition at low power densities and 400 °C resulted in large (∼5 μm) anatase crystallites in 1–2 μm films.

Properties of low-pressure CVD tungsten silicide for MOS VLSI interconnections

Abstract: Low-pressure chemical vapor deposition of tungsten silicide has been done and the properties of the deposited films have been studied to determine the process compatibility and suitability to form gate electrodes and interconnections in MOS VLSI applications. The silicide was deposited on single-crystal silicon and on oxidized silicon with and without a coating of polycrystalline silicon film. Auger analysis of the As-deposited films showed absence of any contaminants in it. X-ray diffraction and transmission electron microscopy showed that As-deposited films were microcrystalline with grains smaller than 30 A and upon annealing became polycrystalline WSi 2 with hexagonal structure at 500°C and tetragonal structure at or above 600°C with a corresponding decrease in resistivity from 600-900 µΩ . cm to 35-60 µΩ . cm depending upon anneal temperature and time. No appreciable change in the thickness of the silicide was found during the high-temperature anneals. Silicon-rich silicide films remained stable, smooth, and free of cracks through high-temperature anneals and oxidations, and their adherence to the wafer remained excellent. On the other hand, metal-rich films had overall inferior properties. Thermal oxidation of WSi 2 on polysilicon in dry oxygen in the temperature range of 900 to 1100°C was found to be similar to that of silicon except the linear regime of oxidation was extremely rapid and the entire process could be modeled by a parabolic equation X^{2) = Bt with an activation energy of 1.7 eV. MOS capacitors were fabricated with silicide and polycide gate electrodes. Polysilicon thickness variation from 0 to 5000 A had no adverse effect on the electrical characteristics or mechanical integrity of the devices. In all cases, low values of N f (1 × 1010-7 × 1010cm-2) and N it ( \sime 8 MV/cm) were obtained.

Thermodynamic Calculations for the Chemical Vapor Deposition of Silicon Nitride

Abstract: The importance of silicon nitride (Si3N4) prepared by the chemical vapor deposition (C VD) technique is discussed briefly. A computer code was used to calculate CVD phase diagrams useful for the preparation of this material. Theoretical deposition efficiencies and gaseous phase compositions are also reported. The reactants include NH3/SiH4, NH3/SiH2Cl2, NH3/SiCl4, and NH3/SiF4. The effect of N2, H2, and Ar additions, as well as the system pressure, are evaluated. The results are compared with experimental data from the literature.

Metalorganic chemical vapor deposition of oriented ZnO films over large areas

Abstract: A metalorganic chemical vapor deposition process for preparing c‐axis‐oriented ZnO films in a simple system of the type commercially available for SiO2 deposition is described. The resulting layers are highly uniform in thickness and adhere to a variety of substrates. Film properties and structure are described briefly.

Properties of NbN thin films deposited on ambient temperature substrates

Abstract: The preparation of cubic NbN films by reactive dc magnetron sputtering is described. These superconductive films are deposited at a sufficiently low temperature (<90 °C) that photoresist liftoff techniques and can be used in fabricating Josephson junctions. The superconducting transition temperature has been measured as a function of gas composition and pressure. It reaches a maximum of 14.2 K at 15% N2–85% Ar and 1.06 Pa total pressure. The resistivity ratio of these films is close to unity. Structural studies by transmission electron microscopy and electron diffraction show that films 100‐nm thick or less are randomly oriented, and noncolumnar with a crystallite diameter of 5 nm and a lattice parameter of 4.46 A, which is significantly higher than the bulk value for cubic NbN. The films are dense with void diameters no larger than 0.7 nm. Films 300‐400 nm thick show a small degree of texturing in x‐ray studies with a Read camera. Auger analysis shows a monotonic increase in the N/Nb ratio with increase in the N2/Ar ratio in the sputtering ambient up to 30% N2. From 30% to 50% N2 in the sputtering mixture the N/Nb ratio is constant. Small amounts of carbon impurity are found in all films.

High quality polysilicon by amorphous low pressure chemical vapor deposition

Abstract: Undoped and in situ phosphorus‐doped low pressure chemical vapor deposited polysilicon films have been studied by various structural analysis and optical techniques as a function of deposition temperature. Polysilicon films of high quality can only be obtained by deposition in the amorphous phase and subsequent crystallization.

Efficient visible photoluminescence in the binary a‐Si:Hx alloy system

Abstract: We report the photoluminescence (PL) and structural properties of a new class of efficient visible‐light‐emitting semiconductors: low defect density a‐Si:Hx alloys. For films prepared by the (thermal) homogeneous chemical vapor deposition (HOMOCVD) method, new broadband PL develops for x>0.3, reaching a peak emission energy of 2.05 eV for a hydrogen content x=0.66 (40 at. % H). We attribute the wide gaps to the influence of Si–H bonding on the density of states near the valence band edge. We ascribe the new PL process to band‐to‐band recombination from within the alloy band tails. This emission persists at room temperature with an integrated intensity comparable to conventional light‐emitting diode (LED) materials. Qualitatively similar results are obtained for low‐temperature‐deposited rf plasma films prepared from Si2H6, but not from SiH4. We show that a low Si dangling bond concentration is the key factor, for all the different film types, to achieving efficient luminescence.

Photodeposition of aluminum oxide and aluminum thin films

Abstract: Uniform films of Al2O3 have been photodeposited using an excimer laser operating at 248 nm (KrF) or at 193 nm (ArF) and trimethylaluminum and N2O as the reactants. Deposition rates were typically 2000 A/min and the physical, chemical, and electrical properties of the photodeposited Al2O3 films are comparable to films deposited using conventional techniques. Properties of photodeposited aluminum films are also presented.

Properties and ion implantation of AlxGa1−xN epitaxial single crystal films prepared by low pressure metalorganic chemical vapor deposition

Abstract: High quality single crystal films of AlxGa1−xN have been grown on sapphire substrates using low pressure metalorganic chemical vapor deposition at 915 °C over the entire range of x. Electrical and optical properties of the layers were measured. Electrical compensation by Be+ and N+ implants in the layers was studied. Schottky barriers were fabricated and their current voltage characteristics were studied. We also report some initial results of a study of GaN growth kinetics.

Deposition and composition of silicon oxynitride films

Abstract: Silicon oxynitride (SiOxNy) films have been grown by a low‐pressure chemical vapor deposition (LPCVD) process from mixtures of SiH2Cl2, N2O, and NH3 at 820 °C. The overall layer composition can be varied by adjusting the N2O/NH3 gas flow ratio. Rutherford backscattering and Auger analysis of the films indicated a uniform composition throughout the layer, irrespective of the nature of the substrate. Both the thickness and the composition of these oxynitride films can conveniently be measured with ellipsometry; the oxygen to nitrogen ratio can be derived reliably from the value of the refractive index. It is inferred that LPCVD oxynitrides are homogeneous on an atomic scale, i.e., the silicon atoms are randomly surrounded by oxygen and nitrogen atoms, and are therefore not to be conceived of as a physical two phase mixture of silicon oxide and silicon nitride. Their stability in metal–oxynitride–oxide–silicon structures is found to improve with increasing oxygen content as regards flatband voltage shift upon temperature‐bias stress.

Low pressure metalorganic chemical vapor deposition of InP and related compounds

Abstract: The low pressure metalorganic chemical vapor deposition epitaxial growth and characterization of InP, Ga0.47In0.53 As and GaxIn1-xAsyP1-y, lattice-matched to InP substrate are described. The layers were found to have the same etch pit density (EPD) as the substrate. The best mobility obtained for InP was 5300 cm2 V−1S−1 at 300 K and 58 900 cm2 V−1 S−1 at 772K, and for GaInAs was 11900 cm2 V−1 S−1 at 300 K, 54 600 cm2 V−1 S−1 at 77 K and 90 000 cm V−1S−1 at 2°K. We report the first successful growth of a GaInAs-InP superlattice and the enhanced mobility of a two dimensional electron gas at a GaInAs -InP heterojunction grown by LP-MO CVD. LP MO CVD material has been used for GaInAsPInP, DH lasers emitting at 1.3 um and 1.5 um. These devices exhibit a low threshold current, a slightly higher than liquid phase epitaxy devices and a high differential quantum efficiency of 60%. Fundamental transverse mode oscillation has been achieved up to a power outpout of 10 mW. Threshold currents as low as 200 mA dc have been measured for devices with a stripe width of 9 um and a cavity length of 300 um for emission at 1.5 um. Values of T in the range 64–80 C have been obtained. Preliminary life testing has been carried out at room temperature on a few laser diodes (λ = 1.5μm). Operation at constant current for severalthousand hours has been achieved with no change in the threshold current.

Process for forming thin film

Abstract: A thin film of a-Si, SiO2 or Si3 N4 can be formed on a substrate using a starting material gas containing at least a polysilane of the formula Sin H2n+2 (n=2, 3 or 4) by a chemical vapor deposition method with irradiation with light with high film forming rate at lower temperatures.

Observation of HSiCl in a chemical vapor deposition reactor by laser‐excited fluorescence

Abstract: Using laser‐excited fluorescence, free‐radical HSiCl has been detected in the gas phase during the chemical vapor deposition of silicon from dichlorosilane. Profiles of the relative HSiCl density were measured at atmospheric and low total pressures. Previous studies of chlorosilane deposition have not considered HSiCl as a possible intermediate species. Therefore, its role in the deposition process must be investigated.

Chemical vapor deposition of titanium nitride and like films.

Abstract: A novel process for placing a thin film of a metal nitride, e.g. titanium nitride, on a glass substrate (10) by mixing a metal halide with a reducing gas like ammonia, preferably within a range of from about 250oC to 320oC, and then reacting the gases at (18) the surface of a glass substrate heated to, e.g., about 400oC to about 700oC to form the film on the glass.

Growth and defect chemistry of amorphous hydrogenated silicon

Abstract: Magnetic resonance (NMR,EPR) and infrared studies are presented of amorphous hydrogenated silicon (a‐Si:H) films prepared by homogeneous chemical vapor deposition (HOMOCVD) and rf plasma decomposition using silane and disilane. Hydrogen incorporation occurs with a small activation energy (∼0.06 eV) for all films, while the barrier for changes in spin defect density is almost an order of magnitude larger and comparable to that measured in defect annealing studies. Films deposited by rf(Si2H6) plasma exhibit the greatest hydrogen contents, followed by HOMOCVD and rf(SiH4) plasma material. NMR measurements suggest that HOMOCVD films are less disordered than plasma‐deposited a‐Si:H. Previous work and recent kinetic studies of plasma and thermal environments are extensively analyzed, along with thermodynamic and kinetic data, to determine a a‐Si:H growth mechanisms most consistent with the experimental results. The model presented to explain compositional and defect changes with substrate temperature emphasizes plasma deposition by monoradical precursors and HOMOCVD growth by diradicals, resulting initially in a similar surface‐bound intermediate in all cases. Plasma growth from Si2H6 involves the surface attachment of longer radical chains, compared to SiH4, while oligomeric diradicals could be present in HOMOCVD. The possibility that reactions at the hot reactor wall, as well as in the gas, create monoradicals in HOMOCVD is also explored in detail. Finally, film dehydrogenation and crosslinking reactions are examined, and experiments proposed to determine the channels most relevant for each deposition environment.