VDMOS transistor and manufacturing method therefor
First Claim
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1. A VDMOS transistor on a semiconductor substrate, comprising:
- a drain electrode region of a first conductivity type in said substrate, said drain electrode region having a drain electrode region doping density (D+);
an epitaxial layer of said first conductivity type formed on said drain electrode region, said epitaxial layer having an epitaxial layer doping density (D-), said epitaxial layer defining a first trench and a deeper and narrower second trench within said first trench, said epitaxial layer including a first implanted region of said first conductivity type adjoining said first trench and a second implanted region of said first conductivity type adjoining said second trench, said first and said second implanted regions having a first and a second implanted region doping density (D1), (D2), respectively;
a first gate oxide layer formed within said first trench adjacent to said first implanted region, said first gate oxide layer having a first gate oxide layer thickness (TOX,D1); and
a second gate oxide layer formed within said second trench adjacent to said second implanted region, said second gate oxide layer having a second gate oxide layer thickness (TOX,D2), wherein;
space="preserve" listing-type="equation">D-<
D.sub.1 <
D.sub.2 <
D+;
and
space="preserve" listing-type="equation">T.sub.OX,D1 <
T.sub.OX,D2.
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Abstract
A VDMOS transistor having a reduced drain/source resistance without a corresponding decrease in breakdown voltage and a manufacturing method therefor. Such a VDMOS transistor is created by gradually increasing the doping density of the transistor'"'"'s implanted regions, while simultaneously increasing the respective thicknesses of the gate oxide layers corresponding to the implanted regions along the current flow path.
155 Citations
5 Claims
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1. A VDMOS transistor on a semiconductor substrate, comprising:
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a drain electrode region of a first conductivity type in said substrate, said drain electrode region having a drain electrode region doping density (D+); an epitaxial layer of said first conductivity type formed on said drain electrode region, said epitaxial layer having an epitaxial layer doping density (D-), said epitaxial layer defining a first trench and a deeper and narrower second trench within said first trench, said epitaxial layer including a first implanted region of said first conductivity type adjoining said first trench and a second implanted region of said first conductivity type adjoining said second trench, said first and said second implanted regions having a first and a second implanted region doping density (D1), (D2), respectively; a first gate oxide layer formed within said first trench adjacent to said first implanted region, said first gate oxide layer having a first gate oxide layer thickness (TOX,D1); and a second gate oxide layer formed within said second trench adjacent to said second implanted region, said second gate oxide layer having a second gate oxide layer thickness (TOX,D2), wherein;
space="preserve" listing-type="equation">D-<
D.sub.1 <
D.sub.2 <
D+;and
space="preserve" listing-type="equation">T.sub.OX,D1 <
T.sub.OX,D2. - View Dependent Claims (2, 3, 4, 5)
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Specification