Fabrication method of field-effect transistor

Abstract

A fabrication method of a FET that enables to realize a shorter length between a source-side edge of a recess and an opposing edge of a gate electrode at a higher accuracy than the accuracy limit of the present lithography technique, i.e., about .+-.0.1 .mu.m. After channel, carrier-supply, and contact layers are epitaxially grown on a semiconductor substrate in this order, a patterned insulator layer is formed on the contact layer. Using the insulator layer as a mask, the contact layer is isotropically etched to form a symmetrical recess on the underlying carrier-supply layer. One of the ends of the contact layer facing the symmetrical recess is etched again to make it asymmetric. During the etching processes, the underlying carrier-supply layer is almost never etched due to large etch rate differences for the contact layer and the carrier-supply layer. A patterned conductor layer is formed on the patterned insulator layer to form the gate electrode in Schottky contact with the carrier-supply layer. After removing the insulator layer, and source and drain electrodes are formed on the contact layer. An etch-stop layer is additionally formed between the carrier-supply layer and the contact layer.