Abstract:

A LDMOS structure with the Gaussshape surface in the drift region is proposed here. Pwell, channel, source region, polysilicon gate are set on one side of the Gauss center, and the drain region is put on the other side of the Gauss center. This LDMOS structure has high breakdown voltage of the LDMOS with a gradient surface in the drift region, but also has high onstate breakdown voltage and safe operating area. By changing the height factor of the Gauss shape of the drift region, the drift region with the Gaussshape surface is studied. The results indicate that high temperature drivein of pwell changes the net doping of the drift region with different Gaussshape surfaces. The device breakdown voltage and the surface electric field profile of the LDMOS structures with different Gaussshape surfaces are investigated by changing the height factor of the Gauss shape. There has an optimized onstate breakdown voltage and a smooth surface electric profile when the height factor is around 0.5. Meanwhile, when the height factor increases from 0.5 to 1.0, the onstate breakdown voltage is saturated.

Key words: LDMOS;Gaussshape surface;drift region;onstate breakdown voltage;surface electric field