US 12,249,642 B2
Vertical insulated gate power switch with isolated base contact regions
Paul M Moore, Hillsboro, OR (US); Richard A Blanchard, Los Altos Hills, CA (US); and Vladimir Rodov, Seattle, WA (US)
Assigned to Pakal Technologies, Inc., San Francisco, CA (US)
Filed by Pakal Technologies, LLC, San Francisco, CA (US)
Filed on May 18, 2022, as Appl. No. 17/747,739.
Claims priority of provisional application 63/226,562, filed on Jul. 28, 2021.
Prior Publication US 2023/0032610 A1, Feb. 2, 2023
Int. Cl. H01L 29/745 (2006.01); H01L 29/06 (2006.01); H01L 29/423 (2006.01); H01L 29/739 (2006.01); H01L 29/78 (2006.01)
CPC H01L 29/7397 (2013.01) [H01L 29/7813 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A vertical power device comprising:
trenches in a semiconductor material;
a gate oxide along sidewalls of the trenches;
a conductor at least partially filling the trenches, to form vertical gates;
a well layer of a first conductivity type, where the trenches extend at least into the well layer;
a source region layer of a second conductivity type formed in a top surface of the well layer between some opposing trenches, the source region layer being between the some opposing trenches being source regions of the second conductivity type,
wherein the source region layer is not formed in first areas of the top surface of the well layer between some other opposing trenches, such that the first areas remain of the first conductivity type;
a dielectric layer overlying the well layer and the source region layer, the dielectric layer having a plurality of openings that expose portions of the first areas in the top surface of the well layer and the source region layer, the portions of the first areas that are exposed being well contact regions of the first conductivity type; and
a top electrode overlying the dielectric layer that contacts the well contact regions and the source region layer through the openings,
wherein the well contact regions do not directly abut the source region layer and any source regions, and wherein the top electrode shorts the well layer to the source region layer,
wherein the well contact regions are more highly doped than the well layer,
wherein the well layer below the openings is deeper than the well layer below the source region layer, and
wherein the well layer directly below the trenches is more highly doped than the well region below the source region layer and is deeper than the well layer below the source region layer.