Methods of forming power switching semiconductor devices including rectifying junction-shunts
View Patent ↗A semiconductor device includes a drift layer having a first conductivity type and a body region adjacent the drift layer. The body region has a second conductivity type opposite the first conductivity type and forms a p-n junction with the drift layer. The device further includes a contactor region in the body region and having the first conductivity type, and a shunt channel region extending through the body region from the contactor region to the drift layer. The shunt channel region has the first conductivity type. The device further includes a first terminal in electrical contact with the body region and the contactor region, and a second terminal in electrical contact with the drift layer. The shunt channel region has a length, thickness and doping concentration selected such that: 1) the shunt channel region is fully depleted when zero voltage is applied across the first and second terminals, 2) the shunt channel becomes conductive at a voltages less than the built-in potential of the drift layer to body region p-n junction, and/or 3) the shunt channel is not conductive for voltages that reverse biase the p-n junction between the drift region and the body region.
1. A method of forming an electronic device, comprising:
forming a drift layer having a first conductivity type;
forming a first body region in the drift layer, the first body region having a second conductivity type opposite the first conductivity type and forming a p-n junction with the drift layer;
forming a second body region having the second conductivity type on the first body region;
forming a shunt channel layer between the first and second body regions, the shunt channel region having the first conductivity type and extending between the first and second body regions to the drift layer, wherein the shunt channel region has a length, thickness and doping concentration selected such that the shunt channel region is fully depleted when zero voltage is applied thereto; and
forming a contactor region in the second body region, the contactor region contacting the shunt channel layer and having the first conductivity type.
2. The method of claim 1 , wherein the contactor region comprises a first contactor region, the method further comprising:
forming a second contactor region having the second conductivity type and extending through the first contactor region and into the first body region.
3. The method of claim 1 , wherein forming the shunt channel layer comprises forming a shunt channel epitaxial layer on the drift layer and the first body region; and wherein forming the second body region comprises forming a body epitaxial layer on the channel epitaxial layer.
4. The method of claim 3 , wherein forming the shunt channel layer comprises implanting a buried channel layer in the first body region.
5. The method of claim 1 , further comprising forming a first terminal in electrical contact with the second body region and the contactor region; and
forming a second terminal in electrical contact with the drift layer.
6. The method of claim 1 , wherein forming the first body region comprises selectively implanting second conductivity type impurities into the drift layer.
7. The method of claim 1 , further comprising:
forming a gate insulator layer on the second body region between the contactor region and the drift layer; and
forming a gate contact on the gate insulator layer.
8. The method of claim 7 , further comprising:
forming a threshold adjustment layer on the second body region.
9. The method of claim 8 , wherein forming the threshold adjustment layer comprises forming a threshold adjustment epitaxial layer on the second body region, and wherein forming the contactor region comprises selectively implanting first conductivity type impurities through the threshold adjustment epitaxial layer and into the first body region.
10. The method of claim 1 , further comprising forming a neck implant region adjacent the first and/or second body region, wherein the shunt channel layer extends from the contactor region between the first and second body regions and to the neck implant region, wherein the neck implant region has the first conductivity type.