Method of manufacturing semiconductor device
US5219776A · kind A · utility
1Cited by
10References
16Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Jul 29, 1991 |
| Grant date | Jun 15, 1993 |
| Priority date | — |
| Expiry date | Jul 29, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10B20/383
Abstract
A method of manufacturing a semiconductor device is manufactured as a MOS-type mask ROM in which the threshold voltage in a transistor used as a memory cell varies from stage to stage by ion implantation. As a result, a period for storing data can be shortened by writing data in the late stage of the manufacturing process, and specified ions are implanted with multi-stage energy with a gate electrode of the transistor covered with an insulating film of a layer insulating film or of a layer insulting film and a protective film to vary the threshold voltage stably.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.