LATERAL POWER MOSFET WITH NON-HORIZONTAL RESURF STRUCTURE

摘要

In one embodiment, a RESURF structure between a source and a drain in a lateral MOSFET is formed in a trench having a flat bottom surface and angled sidewalls toward the source. Alternating P and N-type layers are epitaxially grown in the trench, and their charges balanced to achieve a high breakdown voltage. In the area of the source, the ends of the P and N-layers angle upward to the surface under the lateral gate and contact the body region. Thus, for an N-channel MOSFET, a positive gate voltage above the threshold forms a channel between the source and the N-layers in the RESURF structure as well as creates an inversion of the ends of the P-layers near the surface for low on-resistance. In another embodiment, the RESURF structure is vertically corrugated by being formed around trenches, thus extending the length of the RESURF structure for a higher breakdown voltage.

主权项

1. A lateral insulated gate transistor formed in a semiconductor substrate comprising:
a first region of a first conductivity type; a second region of the first conductivity type; a body region of a second conductivity type; a lateral gate insulated from and overlying at least a portion of the body region; and a Reduced Surface Field (RESURF) structure comprising alternating layers of a first material of the first conductivity type and a second material of the second conductivity type, the alternating layers in a first portion of the RESURF structure running generally parallel to a top surface of the substrate toward the second region, and alternating layers in a second portion of the RESURF structure inclining upward toward the gate such that ends of the alternating layers face the gate, wherein the transistor is configured such that, upon a threshold voltage being applied to the gate, a conductive channel is formed in the body region by inversion of the body region under the gate, such that a current flows between the first region and the second region through the RESURF structure.