N-well and N+ buried layer isolation by auto doping to reduce chip size
US7436043B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 21, 2004 |
| Grant date | Oct 14, 2008 |
| Priority date | — |
| Expiry date | Apr 29, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D84/859
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A semiconductor device includes multiple low voltage N-well (LVNW) areas biased at different potentials and isolated from a substrate by a common N+ buried layer (NBL) and at least one high voltage N-well (HVNW) area. The LVNW areas are coupled to the common, subjacent NBL through a common P+ buried layer (PBL). The method for forming the substrate usable in a semiconductor device includes forming the NBL in a designated low voltage area of a negatively biased P-type semiconductor substrate, forming the PBL in a section of the NBL area by implanting P-type impurity ions such as indium into the PBL, and growing a P-type epitaxial layer over the PBL using conditions that cause the P-type impurity ions to diffuse into the P-type epitaxial layer such that the PBL extends into the NBL. Low-voltage P-well areas are also formed in the P-type epitaxial layer and contact the PBL.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.