| 摘要 |
PURPOSE:To form small size protection element for protecting internal circuits by forming an MOS transistor and a diode on a semiconductor through an insulated isolation region and protecting the element from abnormal negative voltage with diode or from abnormal positive voltage with transistor. CONSTITUTION:A protection element for protecting internal circuits is formed as described below. Namely, an N<+> type buried region 12 is formed by diffusion on a P type Si substrate 1, an N type layer 2 is formed by the epitaxial growth method on the entire part including such region 12, the layer 2 is separated into the island region 4 and the epitaxial layer 2 by the P type isolation region 3 which reaches the substrate 1, and the one is mainly used for MOS transistor while the other for diode. The P<+> type drain region 5 and the N<+> type contact region 6 are formed by diffusion within the island region 4 and a drain electrode 10 is attached to the region 5. A P<+> type source region 7 is provided into the other layer 2, a source electrode 11 is attached to said P<+> type source region 7 and a gate electrode 9 is deposited between the regions 4 and 7 through an insulation film 8. |
