Method of manufacturing a trench transistor having a heavy body region
First Claim
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1. A method of manufacturing a trench transistor comprising:
- providing a semiconductor substrate having dopants of a first conductivity type;
forming a plurality of trenches extending from a first surface of the substrate to a first depth into the semiconductor substrate;
lining each of the plurality of trenches with a gate dielectric material;
substantially filling each dielectric-lined trench with conductive material;
forming a doped well in the substrate to a second depth that is less than said first depth of the plurality of trenches, the doped well having dopants of a second conductivity type opposite to said first conductivity type;
forming a source region inside the doped well and extending to a third depth that is less than the second depth, the source region having dopants of the first conductivity type; and
forming a heavy body inside the doped well, the heavy body having dopants of the second conductivity type with a peak concentration occurring at a fourth depth below the third depth of the source region and above the second depth of the doped well.
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Abstract
A trenched field effect transistor is provided that includes (a) a semiconductor substrate, (b) a trench extending a predetermined depth into the semiconductor substrate, (c) a pair of doped source junctions, positioned on opposite sides of the trench, (d) a doped heavy body positioned adjacent each source junction on the opposite side of the source junction from the trench, the deepest portion of the heavy body extending less deeply into said semiconductor substrate than the predetermined depth of the trench, and (e) a doped well surrounding the heavy body beneath the heavy body.
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Citations
36 Claims
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1. A method of manufacturing a trench transistor comprising:
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providing a semiconductor substrate having dopants of a first conductivity type; forming a plurality of trenches extending from a first surface of the substrate to a first depth into the semiconductor substrate; lining each of the plurality of trenches with a gate dielectric material; substantially filling each dielectric-lined trench with conductive material; forming a doped well in the substrate to a second depth that is less than said first depth of the plurality of trenches, the doped well having dopants of a second conductivity type opposite to said first conductivity type; forming a source region inside the doped well and extending to a third depth that is less than the second depth, the source region having dopants of the first conductivity type; and forming a heavy body inside the doped well, the heavy body having dopants of the second conductivity type with a peak concentration occurring at a fourth depth below the third depth of the source region and above the second depth of the doped well. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of manufacturing a trench transistor comprising:
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providing a semiconductor substrate having dopants of a first conductivity type; forming a plurality of trenches extending from a first surface of the substrate to a first depth into the semiconductor substrate; lining each of the plurality of trenches with a gate dielectric material; substantially filling each dielectric-lined trench with conductive material; forming a doped well in the substrate to a second depth that is less than said first depth of the plurality of trenches, the doped well having dopants of a second conductivity type opposite to said first conductivity type; forming a source region inside the doped well to a third depth, the source region having dopants of the first conductivity type; and forming a heavy body inside the doped well to a fourth depth between the third depth of the source region and the second depth of the doped well, the heavy body having dopants of the second conductivity type with a dopant concentration that is higher near the interface with the doped well than near the first surface. - View Dependent Claims (24, 25, 26, 27, 28)
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29. A method of manufacturing a trench transistor comprising:
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providing a semiconductor substrate having dopants of a first conductivity type, the semiconductor substrate including a first highly doped drain layer and a second more lightly and substantially uniformly doped epitaxial layer atop and adjacent the first layer; forming a plurality of trenches extending to a first depth into the epitaxial layer, the plurality of trenches creating a respective plurality of epitaxial mesas; lining each of the plurality of trenches with a gate dielectric material; substantially filling each dielectric-lined trench with conductive material; forming a plurality of doped wells in the plurality of epitaxial mesas, respectively to a second depth that is less than said first depth of the plurality of trenches, the plurality of doped wells having dopants of a second conductivity type opposite to said first conductivity type; forming a plurality of source regions adjacent the plurality of trenches and inside the plurality of doped wells, the source regions having a third depth and dopants of the first conductivity type; forming a plurality of heavy body regions each inside a respective one of the plurality of doped wells, each heavy body region having a fourth depth between the third depth of the source region and the second depth of the doped well, and having dopants of the second conductivity type; and adjusting a dopant profile of the plurality of heavy body regions so that peak electric field is moved away from a nearby trench toward the heavy body resulting in avalanche current that is substantially uniformly distributed. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36)
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Specification