Dense trench MOSFET with decreased etch sensitivity to deposition and etch processing
First Claim
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1. A power semiconductor device with trench gates comprising:
- a) a semiconductor substrate;
b) a source layer on one surface of said substrate and comprising a high concentration of a dopant of a first polarity;
c) a single drain region on the other surface of said substrate;
d) a well layer beneath said source layer doped with a dopant of a second polarity opposite to said first polarity;
e) a region lightly doped with said one polarity positioned above said drain region and below said well layer;
f) plurality of trenches penetrating said source layer and terminating in said region lightly doped with said one polarity, said trenches substantially filled with conductive material;
g) a highly conductive layer on the surface of said source layer comprising a material reacted from a metal and said substrate which forms a highly conductive path extending from a first of said plurality of trenches to a of said plurality of trenches;
h) an insulating layer on said highly conductive layer and on said conductive material in said trenches;
i) vias formed in said insulating layer and extending to said highly conductive layer; and
j) conductive material filling said vias for contacting said highly conductive layer.
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Abstract
A power MOSFET 100 has a source metal 112 that contacts silicided source regions 114 through vias 160 etched in an insulating layer 200. The silicide layer 225 provides for a relatively small but highly conductive contact and thus reduces RDSON. The insulating material may be any suitable material including and not limited to one or a combination of materials such as BPSG, PSG, silicon dioxide and silicon nitride. The insulating layer is relatively thin and does not extend deeply into the gate trench.
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Citations
7 Claims
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1. A power semiconductor device with trench gates comprising:
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a) a semiconductor substrate; b) a source layer on one surface of said substrate and comprising a high concentration of a dopant of a first polarity; c) a single drain region on the other surface of said substrate; d) a well layer beneath said source layer doped with a dopant of a second polarity opposite to said first polarity; e) a region lightly doped with said one polarity positioned above said drain region and below said well layer; f) plurality of trenches penetrating said source layer and terminating in said region lightly doped with said one polarity, said trenches substantially filled with conductive material; g) a highly conductive layer on the surface of said source layer comprising a material reacted from a metal and said substrate which forms a highly conductive path extending from a first of said plurality of trenches to a of said plurality of trenches; h) an insulating layer on said highly conductive layer and on said conductive material in said trenches; i) vias formed in said insulating layer and extending to said highly conductive layer; and j) conductive material filling said vias for contacting said highly conductive layer. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification