Patent ID: 9450082
Filing Date: 2016-09-20
CPC Classification: H01L

Claim Text:
1. A semiconductor device, comprising: a substrate comprising a semiconductor; a vertical metal oxide semiconductor (MOS) transistor, comprising: a drain contact region disposed in the substrate; a vertical drain drift region disposed in the substrate over the drain contact region; drain trenches disposed in the vertical drift region, wherein the drain trenches are arranged parallel to each other separated by a substantially equal spacing, each of the drain trenches comprising a dielectric liner contacting the substrate and a field plate inside the dielectric liner, the vertical MOS transistor having at least one chamfered corner wherein each chamfered corner extends across at least five of the drain trenches so that the drain trenches at each chamfered corner are shorter than instances of the drain trenches located away from the chamfered corners; a body disposed in the substrate above the vertical drain drift region; a gate disposed above the body; and a source electrode disposed over the substrate; and a termination trench disposed in the substrate, the termination trench surrounding the drain trenches, the termination trench comprising a dielectric liner contacting the substrate and a field plate inside the dielectric liner; wherein the drain contact region extends under the termination trench, wherein: an interior edge of the termination trench is separated from outer instances of the drain trenches by a side space which is 80 percent to 120 percent of the substantially equal spacing between the drain trenches; the interior edge of the termination trench is separated from ends of instances of the drain trenches located away from the chamfered corners by an end space which is 50 percent to 90 percent of the spacing between the drain trenches; at each chamfered corner, the termination trench includes at least three external corners and at least two internal corners, wherein the external corners and internal corners alternate in series; each external corner extends around an end of an instance of the drain trenches which extends past an adjacent instance of the drain trenches, wherein every point on the interior edge of the termination trench is separated from an adjacent instance of the drain trenches by 50 percent to 120 percent of the substantially equal spacing between the drain trenches; and each internal corner extends past an end of an instance of the drain trenches which is recessed from an adjacent instance of the drain trenches, wherein every point on the interior edge of the termination trench is separated from sides and ends of the adjacent drain trenches by 50 percent to 120 percent of the substantially equal spacing between the drain trenches.