Method of forming a semiconductor device having sub-surface trench charge compensation regions
First Claim
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1. A method for forming a semiconductor device comprising the steps of:
- providing a region of semiconductor material having a first major surface;
forming a trench in the region of semiconductor material extending from the first major surface;
forming a plurality of semiconductor layers within the trench including at least two opposite conductivity type semiconductor layers, and at least one buffer layer separating the at least two opposite conductivity type semiconductor layers, wherein the buffer layer has a lower dopant concentration than the at least two opposite conductivity type semiconductor layers at formation;
removing portions of the plurality of semiconductor layers so that remaining portions of the plurality of semiconductor layers are recessed below the first major surface to form a sub-surface trench compensation region in a lower portion of the trench;
forming a control electrode in an upper portion of the trench overlying the sub-surface trench compensation region;
forming a body region within the region of semiconductor material, wherein the control electrode is configured to establish a channel in the body region when the device is in operation; and
forming a source region within the body region.
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Abstract
In one embodiment, a semiconductor device is formed having sub-surface charge compensation regions in proximity to channel regions of the device. The charge compensation trenches comprise at least two opposite conductivity type semiconductor layers. A channel connecting region electrically couples the channel region to one of the at least two opposite conductivity type semiconductor layers.
63 Citations
20 Claims
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1. A method for forming a semiconductor device comprising the steps of:
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providing a region of semiconductor material having a first major surface; forming a trench in the region of semiconductor material extending from the first major surface; forming a plurality of semiconductor layers within the trench including at least two opposite conductivity type semiconductor layers, and at least one buffer layer separating the at least two opposite conductivity type semiconductor layers, wherein the buffer layer has a lower dopant concentration than the at least two opposite conductivity type semiconductor layers at formation; removing portions of the plurality of semiconductor layers so that remaining portions of the plurality of semiconductor layers are recessed below the first major surface to form a sub-surface trench compensation region in a lower portion of the trench; forming a control electrode in an upper portion of the trench overlying the sub-surface trench compensation region; forming a body region within the region of semiconductor material, wherein the control electrode is configured to establish a channel in the body region when the device is in operation; and forming a source region within the body region. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for forming a semiconductor device comprising the steps of:
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providing a region of semiconductor material having a primary surface; forming a trench extending from the primary surface; forming a charge compensated structure in a lower portion of the trench and spaced apart from the primary surface, wherein the charge compensated structure comprises a plurality of opposite conductivity layers overlying surfaces of the trench, and wherein the charge compensated structure is formed without an intervening dielectric layer between the region of semiconductor material and the plurality of opposite conductivity type layers; forming a control structure in the trench and overlying the charge compensated structure, wherein the control structure includes a control electrode for forming a channel in a body region adjacent a sidewall of the trench; forming a source region in the body region; and forming a doped region in the region of semiconductor material to electrically couple the channel to the charge compensated structure, wherein the doped region and the source region comprise the same conductivity type, and wherein the doped region overlies at least a portion of the plurality of opposite conductivity type semiconductor layers. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method of forming a semiconductor device comprising the steps of:
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providing a region of semiconductor material having a first major surface; forming a body region in the region of semiconductor material; forming a source region in spaced relationship with the body region; forming a sub-surface trench compensated region within the region of semiconductor material, recessed below the first major surface, and comprising a plurality of opposite conductivity type semiconductor layers, wherein one of the plurality of opposite conductivity type semiconductor layers adjoins the region of semiconductor material without an intervening dielectric layer; forming a trench gate structure overlying the sub-surface trench compensated region including a gate conductive layer separated from sidewalls of the trench gate structure by a gate dielectric layer, wherein the body region and source region are in proximity to the trench gate structure, and wherein the trench gate structure is configured to control a channel in the body region when the semiconductor device is in operation; and forming a channel connecting region in the region of semiconductor material so that it is interposed between the body region and the sub-surface trench compensated region and configured to electrically couple the channel to at least one of the plurality of opposite conductivity type semiconductor layers, wherein the channel connecting region and the source region comprise a first conductivity type, and wherein the channel connecting region overlies at least a portion of the plurality of opposite conductivity type semiconductor layers. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification