| 摘要 |
PURPOSE:To improve the high frequency characteristics of the titled semiconductor device by a method wherein a ring-shaped graft base region is formed on the semiconductor substrate which will be turned to a collector region, a thick oxide film is generated thereon by performing a heat treatment, and an emitter region is provided at the vacant space located in the center of the ring-shaped part, thereby enabling to reduce the irregularity in size. CONSTITUTION:An SiO2 film 11a is coated on the N type Si substrate 10 which will be used as the collector region of an NPN transistor, and an Si3N4 film 12 is formed in the center of said film 11a aparting from an Si3N4 film 12a and surrounding the film 12a. Then, an ion is implanted using the films 12 and 12a, and after a ring-shaped P<+> type graft base region 13 has been formed in the substrate 10, a heat treatment is performed in an N2 atmosphere and an O2 atmosphere, and a pressing diffusion is performed on the region 13. On this region 13, a thick SiO2 film is generated, and an SiO2 film 11c is generated on the films 12 and 12a. Subsequently, a resist film 14 is provided while the inside of the ring-shaped base region 13 is being exposed, the film 12a is removed together with the film 11c located above the film 12a by performing an etching, an N type layer 15 is grown here, and an N type emitter region 15a is formed in the layer 15. |
