CVD Apparatus Research Articles

Deposition of Amorphous Silicon by an Electron Cyclotron Resonance Plasma

A mixture of silane and hydrogen was decomposed in an electron cyclotron resonance (ECR) plasma CVD apparatus in which the microwave (TE mode) was arranged to propagate to a direction perpendicular to the magnetic flux. Amorphous silicon (a‐Si) films were deposited on a Si substrate located on a place where a magnetic flux density was lower than 90 Gauss.

低温プラズマＣＶＤによる窒化シリコンコーティング膜

Silicon nitride films (SiN films) were prepared by low pressure grow discharges of silane nitrogen mixtures in a capacitively coupled plasma CVD apparatus. The substrate was placed on the cathode of the apparatus. The process of film formation and film characteristics depending upon the effect of the experimental parameters, such as silane gas flow rate, cathode bias voltage and gas pressure, were investigated. In the case of the cathode bias voltage higher than 700 V, SiN films are not formed at the silane gas flow rate lower than the critical one. Atomic concentration ratio Nsi/NN varies extensively by changing the cathode bias voltage and the flow rate of silane gas. SiN films in which atomic concentration ratio is close to 0.75 are transparent. The surface of the films deposited on polished silicon wafers is flat, fine and bright. The experimental results show that ion bombardment at the stage of film formation considerably affects the process of film formation and the characteristics of the films.

Properties of carbon films produced by plasma CVD.

Physical properties of carbon films, prepared by using a plasma CVD apparatus, have been studied in terms of crystal structure, chemical bond, hardness, depth composition profile, and hydrogen concentration. The relation between the film properties and the plasma parameters was also studied. The structure of carbon films became amorphous carbon at a total pressure of 1.3 Pa, while the graphite like structure was grown at a lower total pressure and higher plasma space potential. When the structure became graphite type, the hydrogen concentration decreased from 40 to 5%, leading to an increase in the Knoop hardness from 80 to 500 kg/mm2. These results are discussed in comparison to the properties of the carbon films prepared by using different deposition techniques.

A small Nb<inf>3</inf>Ge test solenoid

Behaviour and properties of a small test solenoid made from a long piece of stabilized Nb 3 Ge superconductor prepared by the CVD method are described. The used CVD apparatus allows to prepare continuously pieces of more than 200 m in length. A total length of 43.5 m of the 61 m long Nb 3 Ge tape has been used for a construction of a test solenoid. The solenoid properties were measured in an outside magnetic field produced by 40 mm bore superconducting magnet. The contribution of the test solenoid was 0.84 T in the total magnetic field of 4.35 T and 0.42 T in the total field of 9.25 T.

Direct Writing of Silicon Lines by Pyrolytic Argon Laser CVD

A novel laser-induced CVD apparatus with a direct pattern writing ability by a pyrolytic decomposition of SiH4 has been developed. With this equipment, a CW argon laser with an output power of 20 W was used. The argon laser beam, which provides localized heating of the substrate, was utilized to decompose gas-phase molecules, resulting in film deposition. By using this equipment, direct pattern writing of polycrystalline silicon with a smooth surface on silicon substrate covered with SiO2 layer has been realized with a high deposition rate as well as good controllability and crystallinity.

ChemInform Abstract: Film Thickness Dependence of Silicon Reduced LPCVD Tungsten on Native Oxide Thickness.

AbstractTungsten was deposited on silicon wafers via the silicon reduction of WF6 in a low pressure CVD apparatus using WF6/Ar gases.

対向陰極型直流マグネトロン放電プラズマＣＶＤ装置

A new type of DC magnetron-discharge CVD apparatus with facing-cathodes structure has been developed. The radiation damage by high-energy chaged particles, which is often encountered in a plasma process, can be reduced using the new plasma CVD. Discharge characteristics of the apparatus have been examined and hydrogenated amorphous silicon films have been deposited using the new apparatus. It is shown that, when the deposition rate is less than 50A/min, the photo-conductivity of a-Si films can be about 3 times as large as that of films prepared by a conventional plasma CVD, probably due to the effect of reduced radiation damage.

Growth of Epitaxial GaAs Structures for High Efficiency IMPATT's

The development of the modified Read Lo‐Hi‐Lo high efficiency IMPATT requires special growth techniques permitting controlled growth of thin (100–1000Å) layers containing specified amounts of n‐type impurities with high accuracy. To meet this need a gas dopant injection system compatible with standard CVD apparatus was constructed. An accurately measured total amount of for doping the n+ layer is instantaneously released into the gas stream passing over the growing epitaxial layer and is partially incorporated in that layer. The control exercised over parameters of the n+ layers was: the width, ±8%; the position, ±10%; and the impurity content, ±18%. It is shown that the width of a sulfur‐doped layer is determined by (i) the experimental geometry, (ii) gas flow rates, (iii) gaseous diffusion, and (iv) growth rate. The incorporation of sulfur is shown to be proportional to the number of moles of injected and varies as the (growth rate)1.6. Studies of postgrowth diffusion in the solid indicate that the widths of the high‐doped layers broaden by amounts consistent with a value for the diffusion coefficient of sulfur in ofThe doping technique has yielded the first experimental measurement of a distribution coefficient of sulfur between the gas and the solid phases. This distribution coefficient is defined asand has a value ranging between 13 and 26 for our experimental conditions. This study has shown that the injection doping system allows control of the concentration of impurities via the ideal gas law in layers as thin as 150Å. It has furthermore been demonstrated that growth rate control is of primary importance for doping control and that future studies to improve doping control should focus on the variables affecting growth rates.