Power semiconductor devices with shield and gate contacts and methods of manufacture
A semiconductor power device includes active trenches that define an active area and an edge area that is located outside of the active area. The active trenches include a lower shield poly, an upper gate poly, a first oxide layer and a second oxide layer wherein the first oxide layer separates the lower shield poly from the upper gate poly and the second oxide layer covers the upper gate poly. The lower shield poly, upper gate poly, first oxide layer and second oxide layer conform to the shapo of the active trench and extend from the active trench to a surface of the edge area. The edge area includes a first opening that extends through the first oxide layer to the lower shield poly and a second opening that extends through the second oxide layer to the upper gate poly.
1. A semiconductor device comprising: a plurality of active trenches that define an active area; an edge area that is located on one side of the active area; the plurality of active trenches comprising a lower shield poly, an upper gate poly, a first oxide layer and a second oxide layer wherein the first oxide layer separates the lower shield poly from the upper gate poly and the second oxide layer covers the upper gate poly; wherein the lower shield poly, upper gate poly, first oxide layer and second oxide layer conform to the shape of the active trench and extend from the active trench to a surface of the edge area; wherein, the edge area comprises a first opening that extends through the first oxide layer to the lower shield poly and a second opening that extends through the second oxide layer to the upper gate poly.
2. The semiconductor device of claim 1 wherein the second oxide layer is directly over the upper gate poly, the upper gate poly is directly over the first oxide layer, and the first oxide layer is directly over the lower shield poly.
3. The semiconductor device of claim 1 wherein the first opening is lower than the second opening.
4. The semiconductor device of claim 1 wherein the plurality of active trenches extend in parallel in a longitudinal direction, and wherein the semiconductor device further comprises a perimeter trench with extensions in the longitudinal direction that are staggered with respect to the active trenches so that there is an offset between the extensions of the perimeter trench and the active trenches.
5. The semiconductor device of claim 1 wherein the plurality of active trenches extend in parallel in a longitudinal direction, and wherein the semiconductor device further comprises a perimeter trench with extensions in the longitudinal direction that are aligned with respect to the active trenches so that there is substantially no offset between the perimeter trenches and the active trenches.
6. The semiconductor device of claim 1 wherein in each of the plurality of active trenches the second oxide layer caps a top portion of the trench, wherein the top portion of the trench is substantially wider than the lower portion of the trench.
7. The semiconductor device of claim 1 further comprising a body region formed between the plurality of trenches, the body region having a contact etch region on a top surface of the body region, wherein a metal layer extends over the second oxide layer and makes electrical contact to the body region via the contact etch region.
8. A semiconductor device comprising:
a plurality of active trenches that define an active area;
an edge area that is located outside of the active area;
the plurality of active trenches comprising a lower shield poly, an upper gate poly, a first oxide layer and a second oxide layer wherein the first oxide layer separates the lower shield poly from the upper gate poly and the second oxide layer covers the upper gate poly;
wherein the lower shield poly, upper gate poly, first oxide layer and second oxide layer conform to the shape of the active trench and extend from the active trench to a surface of the edge area;
wherein, the edge area comprises a first opening that extends through the first oxide layer to the lower shield poly and a second opening that extends through the second oxide layer to the upper gate poly;
the first opening is filled with a conductive material that makes electrical contact with the lower shield poly and the second opening is filled with conductive material that makes electrical contact with the upper gate poly;
wherein the lower shield poly is electrically insulated from the substrate;
wherein the second oxide layer is directly over the upper gate poly, the upper gate poly is directly over the first oxide layer, and the first oxide layer is directly over the lower shield poly; and
wherein the first opening is lower than the second opening.
9. The semiconductor device of claim 8 wherein the plurality of active trenches extend in parallel in a longitudinal direction, and wherein the semiconductor device further comprises a perimeter trench with extensions in the longitudinal direction that are staggered with respect to the active trenches so that there is an offset between the extensions of the perimeter trench and the active trenches.
10. The semiconductor device of claim 8 wherein the plurality of active trenches extend in parallel in a longitudinal direction, and wherein the semiconductor device further comprises a perimeter trench with extensions in the longitudinal direction that are aligned with respect to the active trenches so that there is substantially no offset between the perimeter trenches and the active trenches.
11. The semiconductor device of claim 8 wherein in each of the plurality of active trenches the second oxide layer caps a top portion of the trench, wherein the top portion of the trench is substantially wider than the lower portion of the trench.
12. The semiconductor device of claim 8 further comprising a body region formed between the plurality of trenches, the body region having a contact etch region on a top surface of the body region, wherein a metal layer extends over the second oxide layer and makes electrical contact to the body region via the contact etch region.
13. A semiconductor device as in claim 1 wherein the first opening is filled with a conductive material that makes electrical contact with the lower shield poly and the second opening is filled with conductive material that makes electrical contact with the upper gate poly; and wherein the lower shield poly is electrically insulated from the substrate.