| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem, wherein since the protective film for through ions which is required between the emitter and base diffusion sources of a high-frequency semiconductor device is thin film, the breakdown voltage required between its emitter and its base has conventionally been deteriorated, and although an NSG film is provided in order to earn the film thickness of this insulating film, when etching thereafter this insulating film in the process for forming its emitter contact, the NSG film has been so over-etched as to generate short circuiting between its emitter and base diffusion sources. SOLUTION: An HTO film is formed on the protective film for through ions, in order to earn the film thickness of the protective film. Thereby, the breakdown voltage required between the base and emitter of a high-frequency semiconductor device can be secured. Also, since the etching rate of the HTO film is slower than the one of an NSG film, any over-etching can be prevented in the etching process for forming its emitter-contact portion. Although a thermal oxidation film is minute, the additional formation thereof is suitable, and a nitride film increases the capacitance between its base and its emitter also. When the HTO film is used, the characteristics of its intrinsic base region is remains unchanged and the increase in the capacitance between its base and its emitter is so suppressed also as to be able to secure the breakdown voltage required between its base and its emitter. COPYRIGHT: (C)2005,JPO&NCIPI
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