| 摘要 |
PURPOSE:To reduce soft errors due to the influence of charged particles such as alpha-ray, to access at a high speed and to easily manufacture by associating a bipolar element provided with a P<+> type high concentration layer at the lower part of an N<+> type high concentration buried layer. CONSTITUTION:In a bipolar element having an SOI structure, an N<+> type layer 22 having 3-4mum thickness and 10<21>cm<-3> impurity concentration are formed on a P<+> type layer 23 having 0.4mum thickness and 10<18>cm<-3> impurity concentration. An N<-> type layer 8 has 1mum thickness and 10<16>cm<-3> of impurity concentration, a P<+> type base region 4a has 0.3mum thickness and 10<18>cm<-3> impurity concentration, and an emitter region 5 has 10<20>cm<-3> impurity concentration. P-type impurity is diffused in an N-type or P-type wafer in depth of 0.4mum or deeper. Another wafer is oxidized 1mum. The diffused surface and the another wafer are superposed, and heat treated at 1100 deg.C or higher. The wafer in which the impurity is diffused is polished, silicon is reduced in thickness to predetermined value on the oxide film, and high concentration N-type impurity is diffused thereon. Thus, a thickness accuracy is not required, and its manufacturing cost is reduce. |
