Power MOSFETs and Methods for Forming the Same

摘要

Power Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) and methods of forming the same are provided. A power MOSFET may comprise a first drift region formed at a side of a gate electrode, and a second drift region beneath the gate electrode, adjacent to the first drift region, with a depth less than a depth of the first drift region so that the first drift region and the second drift region together form a stepwise shape. A sum of a depth of the second drift region, a depth of the gate dielectric, and a depth of the gate electrode may be of substantially a same value as a depth of the first drift region. The first drift region and the second drift region may be formed at the same time, using the gate electrode as a part of the implanting mask.

主权项

1. A method comprising:
forming a gate structure over a first region, the first region being of a first conductivity type and having a first impurity concentration, the gate structure comprising a gate dielectric and a gate electrode; implanting a second region of the first conductivity type into the first region, the second region having a second impurity concentration; implanting a first drift region of a second conductivity type into the first region, the second conductivity type being opposite to the first conductivity type, the first drift region having a third impurity concentration; implanting a second drift region of the second conductivity type into the first region through the gate structure, the second drift region having the third impurity concentration, the second drift region being entirely beneath the gate electrode, the second drift region abutting the first drift region, a depth of the second drift region being less than a depth of the first drift region; implanting a source region of the second conductivity type into the second region; and implanting a drain region of the second conductivity type into the first drift region.