Method of fabricating Schottky gate-type GaAs field effect transistor

Claim 1

A method of manufacturing a semiconductor device, comprising the steps of: forming a first impurity region of one conductive type in a compound semiconductor substrate; forming a metal film and a first insulating film made of silicon dioxide sequentially on a surface of said first impurity region; selectively etching said metal film and said first insulating film in the same pattern and forming at a substantially central portion of said first impurity region of first electrode consisting of a metal pattern, an upper surface of which is covered with a first insulating film pattern; forming a second insulating film made of silicon dioxide on an entire surface of said compound semiconductor substrate; forming a resist pattern having openings at two sides of said first electrode on said second insulating film; ion-implanting an impurity of one couductive type in said substrate through said second insulating film exposed in said openings by using as a mask said first electrode, a portion of said second insulating film formed on side walls of said first electrode and said resist pattern in order to form second and third impurity regions of higher impurity concentrations than that of said first impurity region, and leaving a portion of said first impurity region between said second and third impurity regions and immediately under said first electrode and portions of said second insulating film on the side walls of said first electrode; removing said second insulating film by performing anisotropic etching on said entire surface of said compound semiconductor substrate and leaving siad second insulating film on the side walls of said first electrode; forming an ohmic metal film on said entire surface of said compound semiconductor substrate; and removing said resist pattern together with a portion of said ohmic metal film thereon so as to form self-aligned second and third electrodes on said second and third impurity regions, respectively.

Claim 2

A method of manufacturing a semiconductor device, comprising the steps of: forming a first impurity region of one conductive type in a compound semiconductor substrate; forming a metal film and a first insulating film made of silicon dioxide sequentially on a surface of said first impurity region; selectively etching said metal film and said first insulating film in the same pattern and forming at a substantially central portion of said first impurity region of first electrode consisting of a metal pattern, an upper surface of which is covered with a first insulating film pattern; forming a second insulating film made of silicon dioxide on an entire surface of said compound semiconductor substrate; forming a resist pattern having openings at two sides of said first electrode on said second insulating film; ion-implanting an impurity of one couductive type in said substrate through said second insulating film exposed in said openings by using as a mask said first electrode, a portion of said second insulating film formed on side walls of said first electrode and said resist pattern in order to form second and third impurity regions of higher impurity concentrations than that of said first impurity region, and leaving a portion of said first impurity region between said second and third impurity regions and immediately under said first electrode and portions of said second insulating film on the side walls of said first electrode; removing said second insulating film by performing anisotropic etching on said entire surface of said compound semiconductor substrate and leaving siad second insulating film on the side walls of said first electrode; forming an ohmic metal film on said entire surface of said compound semiconductor substrate; and removing said resist pattern together with a portion of said ohmic metal film thereon so as to form self-aligned second and third electrodes on said second and third impurity regions, respectively.