Abstract: A method of manufacturing a trench-gate semiconductor device (1), the method including forming trenches (20) in a semiconductor body (10) in an active transistor cell area of the device, the trenches (20) each having a trench bottom and trench sidewalls, and providing silicon oxide gate insulation (21) in the trenches such that the gate insulation (33) at the trench bottoms is thicker than the gate insulation (21) at the trench sidewalls in order to reduce the gate-drain capacitance of the device.

Abstract: A trench-gate semiconductor device (100) has a trench network (STR1), ITR1) surrounding a plurality of closed transistor cells (TCS). The trench network comprises segment trench regions (STR1) adjacent sides of the transistor cells (TCS) and intersection trench regions (ITR1) adjacent corners of the transistor cells. As shown in FIG. 16 which is a section view along the line II-II of FIG. 11, the intersection trench regions (ITR1) each include insulating material (21D) which extends from the bottom of the intersection trench region with a thickness which is greater than the thickness of the insulating material (21B1) at the bottom of the segment trench regions (STR1). The greater thickness of the insulating material (21D) extending from the bottom of the intersection trench regions (ITR1) is effective to increase the drain-source reverse breakdown voltage of the device (100).

Abstract: A vertical insulated gate transistor is manufactured by providing a trench (26) extending through a source layer (8) and a channel layer (6) towards a drain layer (2). A spacer etch is used to form gate portions (20) along the trench side walls, a dielectric material (30) is filled into the trench between the sidewalls gate portions (20), and a gate electrical connection layer (30) is formed at the top of the trench electrically connecting the gate portions (20) across the trench.

Abstract: A method of making a trench MOSFET includes forming a nitride liner 50 on the sidewalls 28 of a trench and a plug of doped polysilicon 26 at the bottom of a trench. The plug of polysilicon 26 may then be oxidised to form a thick oxide plug 30 at the bottom of the trench whilst the nitride liner 50 protects the sidewalls 28 from oxidation. This forms a thick oxide plug at the bottom of the trench thereby reducing capacitance between gate and drain.

Abstract: A RESURF trench gate MOSFET has a sufficiently small pitch (close spacing of neighbouring trenches) that intermediate areas of the drain drift region are depleted in the blocking condition of the MOSFET. However, premature breakdown can still occur in this known device structure at the perimeter/edge of the active device area and/or adjacent the gate bondpad. To counter premature breakdown, the invention adopts two principles: the gate bondpad is either connected to an underlying stripe trench network surrounded by active cells, or is directly on top of the active cells, and a compatible 2D edge termination scheme is provided around the RESURF active device area. These principles can be implemented in various cellular layouts e.g.