JPS6453547A - Plasma etching - Google Patents

Abstract

PURPOSE:To prevent the occurrence of an undercut, a constricted part and a cross-sectional shape of an inverted trapezoid and to obtain an etching pattern of a desired cross-sectional shape by a method wherein a chlorine-based gas and nitrogen gas are contained as etching gases. CONSTITUTION:When a specimen S inside a specimen chamber 3 is etched, a chlorine-based gas and also nitrogen gas as etching gases are supplied into a plasma generation chamber 1 from a supply tube 1a. As a result, because the nitrogen gas exists, an Si-N-based protective film 15 is formed effectively on a surface layer of a silicon layer 13 inside the specimen S which has been etched at a prescribed amount; after the protective film 15 has been formed, an etching operation in a direction perpendicular to a thickness of the silicon layer 13 is prevented by the protective film 15. An etching amount depends on the concentration of the nitrogen gas to be supplied and on an etching duration.