| 摘要 |
PURPOSE:To provide a transistor having a high withstanding voltage and low saturated voltage, by making a section of a low concentration collector layer near the base region lower in concentration than the other section of the low concentration collector layer. CONSTITUTION:After a low concentration N<-> collector layer 6 is formed on an N<+> collector substrate 1 by epitaxial growth, etc., a section of the N<-> collector layer 6 is removed more deeply than a depth of the base region formed later by etching, etc. Thereafter, on the removed section, a low concentration N<--> collector layer 7 lower in concentration than the low concentration N<-> collector layer 6 is formed by epitaxial growth, and the base region 4 is formed by base diffusion so that the curved portions of the base region 4 are included in the N<--> collector layer 7. Thereafter, an emitter region 3 is formed in the base region 4. Thus, by forming the base curved portions in the N<--> collector layer 7, a depletion layer 8 can be extended easily in the vicinities of the curved portions and the strength of the electric field in the depletion layer 8 is reduced, being difficult to be yielded. |
