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|1. (WO2018164817) VERTICAL POWER MOS-GATED DEVICE WITH HIGH DOPANT CONCENTRATION N-WELL BELOW P-WELL AND WITH FLOATING P-ISLANDS|
|Applicants:||MAXPOWER SEMICONDUCTOR INC.
DARWISH, Mohamed N.
BLANCHARD, Richard A.
|Title:||VERTICAL POWER MOS-GATED DEVICE WITH HIGH DOPANT CONCENTRATION N-WELL BELOW P-WELL AND WITH FLOATING P-ISLANDS|
In one embodiment, a power MOSFET or IGBT cell includes an N-type drift region grown over the substrate. An N-type layer, having a higher dopant concentration than the drift region, is then formed over the drift region. A P-well is formed over the N-type layer, and an N+ source/emitter region is formed in the P-well. A gate is formed over the P-well's lateral channel and has a vertical extension into a trench. A positive gate voltage inverts the lateral channel and increases the vertical conduction in the N-type layer along the sidewalls of the trench to reduce on-resistance. A vertical shield field plate is also in the trench and may be connected to the gate. The field plate laterally depletes the N-type layer when the device is off to increase the breakdown voltage. Floating P-islands in the N-type drift region increase breakdown voltage and reduce the saturation current.