Bell Telephone Laboratories

At&t Bell Laboratories

Robert P Chang

Ashok K Sinha

Chuan C Chang

Tan T Sheng

James J Coleman

The low temperature method for depositing multiconstituent material on a substrate uses at least two ballistic particle streams that are caused to intersect in a volume of space proximate to the substrate. One particle stream, the 'gas' stream, comprises excited neutral particles, and the other particle stream, the 'metal' stream, consists substantially of a particle species capable of chemically reacting with the excited neutrals. The excited neutrals are typically produced in a RF-generated plasma or by means of photon excitation, the source of the metal stream is typically an evaporator or a Knudsen cell. Charged particles can be removed from the gas stream by means of magnetic and/or electric fields, and their removal typically advantageously affects the electrical properties of the deposits. The method has broad applicability, and can be used, for instance, to deposit high quality stoichiometric oxide or nitride films on silicon, germanium, III-V or II-VI semiconductors, metals, or insulators, as well as to deposit doped or layered multiconstituent films. Because deposition can take place at very low substrate temperatures, generally between about 30.degree. C. and 250.degree. C., a patterned deposit can be produced by deposition onto a resist-masked substrate, followed by, removal of the resist by, e.g., lift-off.

Reactive vapor deposition of multiconstituent material

Atomic hydrogen, typically produced in a plasma, etches a wide range of materials, including III-V materials and their oxides. GaAs oxide is etched at a faster rate than GaAs, for example, providing significant possibilities for processing integrated circuits and other devices. Silicon is etched preferentially as compared to silicon dioxide or silicon nitride. Native oxides are also conveniently removed by this method prior to other processing steps.

Hydrogen etching of semiconductors and oxides

The plasma growth rate of native layers, such as oxide and nitride, on silicon is enhanced by the addition of fluorine. An increase in growth rate is obtained, and the oxide growth rates on doped and undoped portions of the silicon substrate are substantially the same. The fluorine is typically added by means of a fluorinated compound, typically CF.sub.4, comprising 0.01 to 5 molecular percent of the plasma. Lower substrate temperatures, typically less than 600 degrees C., may be used, resulting in less warpage of the wafer and less diffusion of dopants.

Fluorine enhanced plasma growth of native layers on silicon

An improved technique for growing native films on compound semiconductors is disclosed. In this technique, additional preferential chemistry is used in conjunction with prior art growth processes to eliminate what would otherwise be unreacted constituents in the native film. Films grown using this technique display improved electrical properties.

Controlling the properties of native films using selective growth

A method of fabricating gallium arsenide MOS devices with improved stoichiometric and electrical properties is disclosed. The device includes a gallium arsenide substrate overlaid with a native oxide and an aluminum oxide layer. The device is fabricated using a plasma oxidizing process.

Fabrication of gallium arsenide MOS devices

An amorphous, stoichiometric, native, semiconductor oxide layer, with a sharp interface between the oxide layer and the substrate, is grown by directing electrons toward a semiconductor substrate in the presence of oxygen. The source of electrons may be a simple filament. This invention may be implemented with standard plasma growth techniques by extracting the electrons from the plasma production region and directing them to the substrate.

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Warren, NJ, United States of America

Robert P Chang