Method for forming a well under isolation and structure thereof
US6500723B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 5, 2001 |
| Grant date | Dec 31, 2002 |
| Priority date | — |
| Expiry date | Oct 5, 2021 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S438/947
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A number of small wells under the isolation layer are formed using the same mask made of photoresist and implant step that is used for the regular wells. The small wells are formed close enough together so that they merge during normal subsequent semiconductor processing to form a merged well. The normal wells and the small wells have a concentration that is greater than that of the merged well. The desired merging of the small wells is ensured by making sure that the small wells are sufficiently close together that the normal diffusion of well implants, which occurs from the particular semiconductor process that is being used, results in the merging. One desirable use of the merged well, with its lower doping concentration, is as a resistor that has more resistance than that of the regular well without requiring an additional implant.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.