Transistor with buried P+ and source contact

1. A transistor comprising:

an n-well region implanted into a surface of a substrate;

a gate region;

a source region on a first side of the gate region, the source region comprising a p-body region in the n-well region wherein an n+ region and a p+ region are implanted in the p-body region such that the n+ region is stacked on the p+ region in a depthwise direction, the p+ region extending deeper into the p-body region than the n+ region; and

a drain region on a second side of the gate region, the drain region comprising (a) an n-doped shallow drain extending from the surface of the substrate into the n-well region and (b) an n+ region embedded within the n-doped shallow drain and extending from the top surface of the substrate into the n-doped shallow drain, the n-doped shallow drain extending deeper into the n-well region than the n+ region of the drain region.

2. The transistor of claim 1 , comprising a first source electrode in contact with the p+ region of the source region and a second source electrode in contact with the n+ region of the source region.

3. The transistor of claim 2 , wherein the first and second source electrodes are spaced apart along an axis substantially perpendicular to a cell pitch associated with the transistor.

4. The transistor of claim 1 , wherein the gate region comprises:

a trench in the n-well region extending from a surface of the n-well region to a first depth, the trench comprising:

a gate of conductive material in the trench, and

dielectric material filling a volume of the trench not filled by the conductive material.

5. The transistor of claim 4 , wherein the p-body region comprises a p-type material extending from a surface of the n-well region to a second depth.

6. The transistor of claim 4 , wherein at least a portion of the p-body is beneath the trench and extends from a second depth to a third depth, wherein each of the second depth and the third depth is greater than the first depth.

7. The transistor of claim 4 , wherein the conductive material comprises polysilicon.

8. The transistor of claim 4 , wherein the dielectric material comprises an oxide.

9. The transistor of claim 1 , the p-body region comprising a deep p-body region and a shallow p-body region, the shallow p-body region being closer to the surface and having a higher concentration of p-type material than the deep p-body region.

10. The transistor of claim 6 , wherein the portion of the p-body beneath the trench is a portion of an epitaxial layer.

11. The transistor of claim 6 , wherein the portion of the p-body beneath the trench is a portion of a reduced surface field (RESURF) layer.

12. The transistor of claim 1 , wherein a region below the gate region between the drain region and the source region provides a channel.

13. The transistor of claim 12 , comprising a first plurality of source electrodes in contact with the p+ region of the source region and a second plurality of source electrodes in contact with the n+ region of the source region.

14. The transistor of claim 13 , wherein first and second plurality of source electrodes are arranged on a line.

15. The transistor of claim 14 , wherein the line is substantially perpendicular to a direction of current flow through the channel.

16. The transistor of claim 14 , wherein the first plurality of source electrodes and the second plurality of source electrodes are arranged in an alternating pattern along the line.

17. The transistor of claim 1 , wherein there is no p-type region disposed between the n+ region of the drain region and the n-doped shallow drain.

18. The transistor of claim 1 , wherein an entire bottom surface of the n+ region of the drain region contacts the n-doped shallow drain.