| 摘要 |
PROBLEM TO BE SOLVED: To obtain a high breakdown strength semiconductor device in which an optimal quality of semi-insulating thin film is determined depending on the field strength which is determined by breakdown strength and element structure. SOLUTION: A semiinsulating thin film being applied to the high breakdown strength semiconductor device has such a film quality as the field strength E being applied thereto is 1.8×10<8>×εr (ϕt )<2> or below. For example, an n<+> region 2 and a p<+> region 3 are formed on a p-type substrate 1 with diffusion depth xj and other regions are subjected to selective oxidation to form a surface protective film 4 of SiO2 . Subsequently, Al is sputtered and machined to form electrodes 6, 7 which are then coated with a field plate, i.e., a semiinsulating amorphous SixNyHz film 11, by plasma CVD before a window is opened at the electrode part 6, 7. Film deposition conditions are RF power of 50 kHz, 1 kW, substrate temperature of 320 deg.C, gas composition of SiH4/(SiH4+NH 3)=0.77, deposition pressure of 53 Pa, and carrier gas flow rate of 1.5 SLM, and the film thickness is 1μm. According to the structure, field strength E being applied to the semiinsulating thin film can be set at 1.8×10<8>×εr (ϕt )<2> or below. |
