High mobility power metal-oxide semiconductor field-effect transistors
View Patent ↗High mobility P-channel power metal oxide semiconductor field effect transistors. In accordance with an embodiment of the present invention, a power MOSFET is fabricated such that the holes flow in an inversion/accumulation channel, which is along the (110) crystalline plane, or equivalents, and the current flow is in the [110] direction, or equivalents, when a negative potential is applied to the gate with respect to the source. The enhanced channel mobility of holes leads to a reduction of the channel portion of the on-state resistance, thereby advantageously reducing total “on”resistance of the device.
1. A method comprising:
utilizing a silicon wafer having a surface orientation in a direction;
etching a trench in a (110) plane of said wafer, wherein said etching comprises etching a plurality of perpendicular trenches bounded by (100) planes;
forming first and second source regions adjacent to and parallel to each long edge of said trench; and
forming a gate structure in said trench between said first and second source regions.
2. The method of claim 1 wherein said plurality of perpendicular trenches form closed cells.
3. A trench MOSFET comprising:
a silicon wafer including a surface orientation in a direction;
a trench formed in said silicon wafer in a (110) plane;
a plurality of perpendicular trenches bounded by (110) planes;
first and second source regions adjacent to and parallel to each long edge of said trench; and
a gate structure in said trench between said first and second source regions.
4. The trench MOSFET of claim 3 wherein said plurality of perpendicular trenches form closed cells.