| 摘要 |
PURPOSE:To form an element region having a depth suitable to a required breakdown strength, by forming the shallow bottom of an island region to form a low dielectric strength element in a semiconductor device of D.I structure. CONSTITUTION:On a D.I substrate in which a polysilicon layer 4 is used as a substrate, island regions 1h, 1l are formed. On the island region 1h, a high breakdown strength NPN Tr H1 is formed. On the island region 1l, a low breakdown strength NPN Tr L1 is formed. The island region 1l forming the low breakdown strength Tr L1 is formed so as to have a shallow bottom where dielectric just under an emitter protrudes in the form of an inversed V. As a result, the collector resistance of an active region just under the emitter can be reduced, and the high breakdown strength Tr H1 and the low breakdown strength Tr L1 can be formed on the same substrate. On the bottom surfaces and the peripheral walls of the island regions 1h, 1l, are formed subcollector diffusion 3h, 3l in which high concentration impurity connecting with the substrate surface is introduced. |
