At&t Bell Laboratories

At+t Corp.

American Telephone & Telegraph Co., At&t Bell Laboratories

Stephen J Pearton

Fan Ren

Cammy R Abernathy

Thomas R Fullowan

Pierre M Petroff

Arthur C Gossard

Joel B Cibert

In accordance with the invention, aluminum-containing layers are grown by molecular beam processes using as an arsenic precursor phenylarsine (PhAs). Because PhAs is more reactive than arsine and less reactive than arsenic, it decomposes selectively on III-V surfaces but not on mask materials. Thus in contrast to conventional processes, growth using PhAs permits selective growth on unmasked gallium arsenide surfaces but inhibits growth on typical mask materials such as silicon nitride.

Method for selectively growing aluminum-containing layers

In accordance with the invention, gallium-containing layers are grown by molecular beam processes using as an arsenic precursor a compound of the dialkylaminoarsenic family (DAAAs) such as tris-dimethylamino arsenic (DMAAs). In contrast to conventional arsenic sources, DAAAs act as carbon 'getters'. When DAAAs are used as an arsenic source, the DAAAs getter carbon impurities from the gallium source. Thus, for example, DAAAs can be used as an arsenic source in combination with TMG as a gallium source to selectively grow high purity or n-type layers of gallium arsenide at low temperatures below 600.degree. C. In addition DMAAs has been found to be an excellent cleaning agent for gallium arsenide materials.

Method for selectively growing gallium-containing layers

The present applicants have discovered that a layer predominantly comprising tungsten can be formed into precise patterns having substantially vertical walls by using titanium as a mask and plasma etching in a fluorine-containing plasma such as CF.sub.4 or SF.sub.6. The success of the process is believed attributable to the occurrence of an etch stop reaction on the sidewalls of the tungsten. The products of the reaction inhibit horizontal etching. After the tungsten is etched, the titanium mask can be selectively removed, as by etching in dilute HF. Each step in the process can be effected without subjecting the workpiece to voltage magnitudes in excess of 200 volts or temperatures outside the range between room temperature and 200.degree. C.

Method for forming patterned tungsten layers

Disclosed is a method of making semiconductor devices that comprises etching of a semiconductor layer, with a patterned metal layer acting as the etch mask. The patterned metal layer comprises a mask metal layer (exemplarily Ti) overlying a contact metal layer (exemplarily a Au-containing layer). In an exemplary embodiment the inventive method is used to manufacture InP-based heterojunction bipolar transistors.

Method of making semiconductor devices

A method of fabricating quantum well wires and boxes is described in which interdiffusion in a semiconductor having a compositional profile is enhanced by the presence of defects created by ion implantation in localized regions.

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Summit, NJ, United States of America

Stephen J Pearton