Integrated zener diode overvoltage protection structures in power DMOS device applications
US5767550A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 16, 1996 |
| Grant date | Jun 16, 1998 |
| Priority date | — |
| Expiry date | Oct 16, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S438/983
Abstract
In one embodiment, modifications to the polysilicon gate, body, source, and contact masks of a DMOS process add a source-body monocrystalline gate protection diode under the gate pad by implanting an anode region beneath the gate. The anode is connected to the gate through the gate metal in the pad. In addition to the gate-source diode, there is also a connection from the drain to the gate through the anode formed by the body region beneath the gate. This embodiment includes a junction terminating field plate. The presence of the field plate creates a special protection device similar to a zener diode, but which exhibits a current/voltage characteristic similar to a thyristor. A significant feature of this embodiment is that the zener breakdown voltage is easily adjusted by a simple modification to the fabrication process. The field plate creates two opposing junctions with the spacing determined by the length of the field plate. The concentration gradients under the field plate, and hence the breakdown voltage, is controlled by suitable length of the field plate and other processing conditions. A zener breakdown programmability option is implemented so that the zener breakdown vol…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.