Patent ID: 6924201
Filing Date: 2005-08-02
Classification: H01L

Abstract:
1. A method of producing a heterojunction bipolar transistor (HBT) from a wafer consisting of a substrate and a collector layer of a first conductivity type, a base layer of a second conductivity type and an emitter layer of said first conductivity type sequentially laminated on said substrate in this order, said method comprising: a first etching step of etching said wafer up to a preselected depth of said collector layer by using a first photoresist, which is formed at a preselected position on said emitter layer, as a mask; and a second etching step of etching said collector layer by using a second photoresist covering at least a sidewall of said base layer and a sidewall of said collector layer exposed by said first etching step and a part of a surface of said collector layer contiguous with the sidewalls as a mask; a step of removing, before forming said second photoresist, said first photoresist and then forming an SiN film on said substrate; and a step of removing, after forming said second photoresist, said SiN film exposed.