JPS6424466A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve GaAs MESFETs in reproducibility and uniformity of their electrical characteristics by a method wherein an FET-forming region on an S.I.GaAs substrate is protected from damage attributable to plasma-using dry etching in a GaAs MESFET manufacturing process. CONSTITUTION:On an AlN layer 5, an SiO2 layer 6 is formed as a spacer insulating film. Next, the SiO2 layer 6 is subjected to dry etching with a photoresist 21 serving as a mask, when a Schottky gate-forming region on the surface of an S.I.GaAs substrate 1 is protected from damage because it is covered by the AlN layer 5. A high-melting metal layer 7 is formed on a Schottky gate opening and SiO2 layer 6 and, for the elimination of abrupt steps, flattening photoresist is applied. A plasma-using dry etching process is accomplished for the removal of the high-melting metal layer 7 from above the SiO2 6, when the surface of the S.I.GaAs substrate 1 is protected from damage because it is covered by the AlN layer 5 and the high-melting metal layer 7. The remnant of the SiO2 layer 6 or of the AlN layer 5 is removed for the formation of a Schottky gate 8 in a prescribed region.