| 摘要 |
PURPOSE:To facilitate the increase in strength to soft error alpha rays of the semiconductor memory and its improvement in latch-up resistance by a method wherein a reverse conductivity type region of higher concentration than that of a reverse conductivity epitaxial layer is provided between a one-conductivity type semiconductor substrate and that epitaxial layer. CONSTITUTION:The reverse type epitaxial substrate is provided with a P<+> type region 12 of high impurity concentration on the N<+> type Si substrate 11 surface, and a P<-> type Si epitaxial layer 13 of lower concentration than that of the substrate is deposited thereon. Since a substrate 11 side junction J1 is formed between the substrate 11 and the region 12 when a Vcc potential is impressed on a drain region 6, a depletion layer DEP1 does not reach the inside of the epitaxial layer 13. Besides, a depletion layer DPE2 spreading out of a junction J2 is inhibited from spreading because of the region 12. Therefore, the epitaxial layer 13 can be largely laminated. |
