Punch-through prevention in trenched DMOS with poly-silicon layer covering trench corners
First Claim
1. A transistor cell comprising:
- a substrate of a first conductivity type having a top surface including at least two intersecting trenches disposed therein;
an insulating layer lining said trenches;
a conductive material filling said trenches;
a source region of said first conductivity type extending from said top surface of said substrate adjacent to said trenches toward said substrate;
a body region of a second conductivity type of opposite polarity from said first conductivity type, said body region extends from said top surface adjacent from said trenches to said substrate and surrounding said source region; and
said conductive material filling said trenches and partially rising above said trenches only near corners defined by said intersecting trenches for covering said corners thus constituting trench-corner source implant blocking blocks for reducing a net dopant concentration of said source region underneath said blocking blocks immediately next to said corner defined by said intersecting trenches having a lower net concentration of impurities of said first conductivity type than remaining portion of said source region.
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0 Petitions
Accused Products
Abstract
The present invention includes a substrate of a first conductivity type having a top surface including at least two intersecting trenches disposed therein with an insulating layer lining the trenches and a conductive material filling the trenches. The transistor also includes a source region of the first conductivity type extending from the top surface of the substrate adjacent to the trenches toward the substrate. The transistor further has a body region of a second conductivity type of opposite polarity from the first conductivity type, the body region extends from the top surface adjacent from the trenches to the substrate and surrounding the source region. The conductive material filling the trenches including punch-through suppressing blocks covering corners of the cell defined by the intersecting trenches wherein the source region disposed underneath the corners immediately next to the trenches having a lower net concentration of impurities of the first conductivity type than remaining portion of the source region.
42 Citations
9 Claims
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1. A transistor cell comprising:
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a substrate of a first conductivity type having a top surface including at least two intersecting trenches disposed therein; an insulating layer lining said trenches; a conductive material filling said trenches; a source region of said first conductivity type extending from said top surface of said substrate adjacent to said trenches toward said substrate; a body region of a second conductivity type of opposite polarity from said first conductivity type, said body region extends from said top surface adjacent from said trenches to said substrate and surrounding said source region; and said conductive material filling said trenches and partially rising above said trenches only near corners defined by said intersecting trenches for covering said corners thus constituting trench-corner source implant blocking blocks for reducing a net dopant concentration of said source region underneath said blocking blocks immediately next to said corner defined by said intersecting trenches having a lower net concentration of impurities of said first conductivity type than remaining portion of said source region. - View Dependent Claims (2, 3, 5, 6, 7, 8)
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4. A transistor cell comprising:
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a substrate of a first conductivity type having a top surface including at least two intersecting trenches disposed therein; an insulating layer lining said trenches; a conductive material filling said trenches; a source region of said first conductivity type extending from said top surface of said substrate adjacent to said trenches toward said substrate; a body region of a second conductivity type of opposite polarity from said first conductivity type, said body region extends from said top surface adjacent from said trenches to said substrate and surrounding said source region; said conductive material filling said trenches and partially rising above said trenches only near corners defined by said intersecting trenches for covering said corners thus constituting trench-corner source implant blocking blocks for reducing a net dopant concentration of said source region underneath said blocking blocks immediately next to said corner defined by said intersecting trenches having a lower net concentration of impurities of said first conductivity type than remaining portion of said source region; and said body region adjacent to said source region underneath said trench-corner source implant blocking blocks having a higher rate of net-second-conductivity-impurity-concentration increase along a depth direction extending downwardly from said top surface than a remaining portion of said body region whereby a punch-through is suppressed in said trench near said corner.
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9. A transistor cell comprising:
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a substrate of a first conductivity type having a top surface including at least two intersecting trenches disposed therein; an insulating layer lining said trenches; a conductive material filling said trenches; a source region of said first conductivity type extending from said top surface of said substrate adjacent to said trenches toward said substrate; a body region of a second conductivity type of opposite polarity from said first conductivity type, said body region extends from said top surface adjacent from said trenches to said substrate and surrounding said source region; said conductive material filling said trenches and partially rising above said trenches only near corners defined by said intersecting trenches for covering said corners thus constituting trench-corner source implant blocking blocks for reducing a net dopant concentration of said source region underneath said blocking blocks immediately next to said corner defined by said intersecting trenches having a lower net concentration of impurities of said first conductivity type than remaining portion of said source region; said body region adjacent to said source region underneath said trench-corner source implant blocking blocks having a higher rate of net-second-conductivity-impurity-concentration increase along a depth direction extending downwardly from said top surface than a remaining portion of said body region whereby a punch-through is suppressed in said trench near said corner.
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Specification