| 摘要 |
PURPOSE:To enable to alleviate wafer warps in a thyristor wherein glass films are formed in mesa grooves by utilizing that the diffusion of boron into one surface of a Si substrate at high concentration causes the substrate to warp with the diffused surface as its inside. CONSTITUTION:After P type isolation regions 9 and p type regions 2, 3 are formed in the n-substrate 1, a p<+> region 14 is formed by diffusing boron at high concentration into the surface opposed to the surface to form the mesa grooves by later processes. Thereafter, the formation of an n-region 4, the mesa grooves 8, and electrodes enables to obtain a thyristor structure. In this case, the warp due to the glass and that due to boron cancel each other because of the presence of a boron high concentration diffused layer on the surface opposed to the mesa grooves 8, and accordingly the warp of the entire wafer is largely alleviated. Such an effect is effective particularly in the case of the surface concentration of boron at 10<18>/cm<3> or more. |
