Semiconductor device including inversion preventing layers having a plurality of impurity concentration peaks in direction of depth
US5218224A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 13, 1991 |
| Grant date | Jun 8, 1993 |
| Priority date | — |
| Expiry date | Aug 13, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/76218
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
Buried layers of a second conductivity type are formed in a plurality of portions of a surface region of a semiconductor substrate of a first conductivity type, and an epitaxial layer of the first conductivity type is formed on the buried layers and the semiconductor substrate. A plurality of well regions of the second conductivity type are formed in the epitaxial layer in contact with the buried layers, and a region of the second conductivity type with a high impurity concentration is formed in one of the well regions in contact with the buried layers. A field insulating layer is formed on a surface region of the semiconductor substrate between the well regions. An impurity is ion-implanted in a portion substantially immediately below the field insulating film a plurality of times to form inversion preventing layers of the first conductivity type having a plurality of impurity concentration peaks. Active elements are formed in the epitaxial layer of the first conductivity type and the well regions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.