Circuit structure with enhanced electrostatic discharge protection
US4939616A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 13, 1989 |
| Grant date | Jul 3, 1990 |
| Priority date | — |
| Expiry date | Nov 13, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D62/108
Abstract
The described embodiments of the present invention provide an input protection device with a low trigger threshold. The structure is a silicon controlled rectifier (SCR) type of device wherein the triggering mechanism is avalanche conduction at the interface between the N-well surrounding a portion of the protection device and the P-type substrate. The embodiments provide a lowered threshold voltage by providing a highly doped region of the same conductivity type as the well at the interface between the well and the substrate. This highly doped region is connected to a resistor which is then connected to the protected node. The resistor and heavily doped region at the intersection between the N-well and substrate provides an additional source of current for avalanching at a lower voltage. Thus the trigger voltage of the protection system is substantially lowered. In other embodiments of the present invention an additional source of triggering current is provided by an N+ contact region in the N-well which is close to the interface between the N-well and the P substrate adjacent to the area closest to the N+ emitter of the silicon controlled device. Either of these highly doped char…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.