Manufacture of semiconductor device

Abstract

Abstract PURPOSE:To obtain a semiconductor device high in a cut-off frequency with a small emitter, which is operational at high speed, by a method wherein a first and a second poly-silicon film are formed on a silicon nitride film provided to the side face of an opening and an under oxide film is removed through the first and the second poly-silicon film utilized as a mask. CONSTITUTION:A fourth Si3N4 film 16 on the base of an opening 19 is removed by means of an anisotropic etching through a first poly-silicon layer 18 used as a mask. Then, a second poly-silicon layer 20 is made to grow on the whole face which includes the opening 19 through a CVD method. Next, the second poly-silicon layer 20 is removed through an anisotropic etchinng so as to leave it unremoved on the sidewall of the opening 19. And, an under oxide film 10 is made to be removed through the first and the second poly-silicon layers, 18 and 10, employed as a mask. A size of an emitter is made to be determined depending on a dimension of an opening 19A formed in this process, on which the property of a transistor depends. After a SiO2 film 26 is formed, a base contact 23, an emitter contact 24, and a collector contact 25 are formed, and then electrodes are built so as to complete an NPN transistor.

Inventors

• 👤 Takeo Yoshikawa

Bibliographic Details