Method for forming electrostatic discharge protection device having a graded junction
US6355508B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 12, 1999 |
| Grant date | Mar 12, 2002 |
| Priority date | — |
| Expiry date | Apr 12, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/14
Abstract
An electrostatic discharge protection device is formed in a substrate and contains a drain area of a first dopant concentration abutting an extended drain area having a dopant concentration lower than the first dopant concentration. Similarly, a highly doped source area abuts a lower doped source extension area. The source and drain are laterally bounded by oxide regions and covered by an insulation layer. The areas of lower doping prevent charge crowding during an electrostatic discharge event by resistively forcing current though the nearly planer bottom surface of the drain, rather than the curved drain extension. In addition, a highly doped buried layer can abut an area of a graded doping level. By adjusting the doping levels of the graded areas and the buried layers, the substrate breakdown voltage is pre-selected.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.