Trench-gate semiconductor devices and their manufacture
First Claim
1. A trench-gate field-effect semiconductor device comprising a semiconductor body into which the trench-gate extends from a surface-adjacent source region of a first conductivity type through a channel-accommodating region of a second conductivity type and into an underlying drain drift region of the first conductivity type, wherein the gate trench has a width that is smaller than its depth in the semiconductor body and that tapers increasingly towards the bottom of the gate trench to reduce the width of the trench-gate at a greater rate in the drain drift region than in the channel-accommodating region.
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Accused Products
Abstract
Trench-gate field-effect semiconductor devices, for example cellular power MOSFETs with compact geometries, comprise a semiconductor body (10) into which the trench-gate (11) extends from a surface-adjacent source region (13) through a channel-accommodating region (15) of opposite conductivity type (p) and into an underlying drain drift region (14). This invention provides the gate trench (20) with a width (w) that is smaller than its depth (d) and that tapers increasingly towards the bottom of the gate trench (20) to reduce the width (w) of the trench-gate (11) at a greater rate in the drain drift region (14) than in the channel-accommodating region (15).
12 Citations
13 Claims
- 1. A trench-gate field-effect semiconductor device comprising a semiconductor body into which the trench-gate extends from a surface-adjacent source region of a first conductivity type through a channel-accommodating region of a second conductivity type and into an underlying drain drift region of the first conductivity type, wherein the gate trench has a width that is smaller than its depth in the semiconductor body and that tapers increasingly towards the bottom of the gate trench to reduce the width of the trench-gate at a greater rate in the drain drift region than in the channel-accommodating region.
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8. A method of manufacturing a trench-gate field-effect semiconductor device, in which the trench-gate extends from a surface-adjacent source region of a first conductivity type through a channel-accommodating region of a second conductivity type and into an underlying drain drift region of the first conductivity type, and wherein the method includes the following sequence of steps:
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(a) providing a semiconductor body having an upper first portion where the channel-accommodating region is present or is to be provided and having a lower second portion that is to provide the drain drift region, (b) forming on the semiconductor body a mask having a window defining the location and width of a trench to be etched into the semiconductor body for accommodating the trench-gate, (c) etching the trench to a depth that is greater than its width and that extends so deeply into the semiconductor body that the width of the trench reduces in size towards the bottom of the trench, with the rate of the width reduction of the trench being greater in the lower second portion of the semiconductor body than in the upper first portion of the semiconductor body, and (d) providing the trench-gate in the trench. - View Dependent Claims (9, 10, 11, 12)
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Specification