Semiconductor device having localized charge balance structure and method
In one embodiment, a semiconductor device has a superjunction structure formed adjoining a low-doped n-type region. A low-doped p-type region is formed adjoining the superjunction structure above the low-doped n-type region and is configured to improve Eas characteristics. A body region is formed adjacent the low-doped p-type region and a control electrode structure is formed adjacent the body region for controlling a channel region within the body region.
1. A semiconductor device comprising:
a semiconductor substrate defining a major surface;
a first region comprising at least a first pillar of a first conductivity type, and a second pillar of a second conductivity type extending in a generally vertical orientation with respect to the major surface, wherein the first conductivity type is opposite to the second conductivity type, and wherein the first pillar is configured as a vertical current path;
a second region of the first conductivity type spaced apart from the major surface and adjoining a lower portion of the first region;
a third region of the second conductivity type adjoining the first region between the major surface and the second region;
a body region of the second conductivity type between a portion of the third region and the major surface;
a source region of the first conductivity type adjoining the body region; and
a control electrode adjoining the body region and the source region and configured to control a channel region within the body region but not within the third region.
2. The device of claim 1 further comprising a fourth region of the first conductivity type between the body region and the third region and configured to link a drain end of the channel region to the first region.
3. The device of claim 1 , wherein the third region has a dopant concentration in a range from about 1.0×10 15 atoms/cm 3 to about 4.0×10 15 atoms/cm 3 , and wherein the first region has a charge balance other than zero.
4. The device of claim 1 , wherein the third region has a dopant concentration in a range from about 1.0×10 15 atoms/cm 3 to about 3.0×10 15 atoms/cm 3 .
5. The device of claim 1 , wherein the first pillar of the first conductivity type adjoins the second and third regions.
6. The device of claim 1 , wherein the control electrode comprises a trench control electrode, and wherein the third region overlaps the trench control electrode and the trench control electrode terminates within the third region.
7. The device of claim 1 further comprising a conductive layer electrically connected to the source region and the third region.
8. A semiconductor device comprising:
a substrate;
a semiconductor layer overlying the substrate, wherein the semiconductor layer has a major surface spaced apart from the substrate;
a vertically-oriented charge balance region adjacent to the major surface and extending towards the substrate;
a body region of a first conductivity type adjacent to another portion of the major surface;
a first horizontally-oriented doped region of a second conductivity type spaced apart from the major surface and between the body region and the substrate, wherein the first horizontally-oriented doped region adjoins the vertically-oriented charge balance region;
a second horizontally-oriented doped region of the first conductivity type spaced apart from the major surface and between the first horizontally-oriented doped region and the substrate; and
a gate electrode electrically insulated from the body region and the first horizontally-oriented doped region,
wherein:
a transistor structure of the semiconductor device comprises the first horizontally-oriented doped region, the body region, and the gate electrode;
the second horizontally-oriented doped region is configured to shift avalanche regions away from the gate electrode and from upper portions of the vertically-oriented charge balance structure towards the semiconductor layer; and
the vertically-oriented charge balance structure electrically connects the transistor structure and the substrate to each other.
9. The structure of claim 8 , wherein the second horizontally-oriented doped region has a dopant concentration in range from about 1.0×10 15 atoms/cm 3 to about 4.0×10 15 atoms/cm 3 .
10. The structure of claim 8 , wherein the second horizontally-oriented doped region has a dopant concentration between about 1.0×10 15 atoms/cm 3 to about 3.0×10 15 atoms/cm 3 .
11. The structure of claim 8 , wherein the second horizontally-oriented doped region has a thickness from about five microns to about fifteen microns.
12. The structure of claim 8 , wherein the gate electrode comprises a trench gate electrode, and wherein the second horizontally-oriented doped region overlaps the gate electrode and the gate electrode terminates within the second horizontally-oriented doped region.
13. The structure of claim 8 , wherein the vertically-oriented charge balance region comprises a plurality of first conductivity type and second conductivity type pillars.
14. The structure of claim 8 further comprising a source region formed in the body region and a conductive layer electrically connected to the source region and the second horizontally-oriented doped region.
15. A semiconductor device comprising:
a semiconductor substrate defining a major surface;
a first region comprising at least a first pillar of a first conductivity type, wherein the first pillar is configured as a vertical current path;
a body region of a second conductivity type opposite to the first conductivity type adjacent the major surface;
a source region of the first conductivity type adjoining the body region;
a second region of the first conductivity type spaced apart from the major surface and adjoining a lower portion of the first region;
a third region of the second conductivity type adjoining the first region between the major surface and the second region;
a control electrode adjoining the body region and the source region and configured to control a channel region within the body region but not within the third region; and
a fourth region of the first conductivity type between the body region and the third region and configured to provide a generally horizontal current path between a drain end of the channel region and the first region.
16. The device of claim 15 , wherein:
the first region further comprises a second pillar of a second conductivity type extending in a generally vertical orientation with respect to the major surface; and
the third region is configured to enhance electrical field distribution during an avalanche condition.
17. The device of claim 16 , wherein the first region has a charge balance greater than zero percent and less than about ten percent, and wherein the third region has a thickness in range from about five microns to about fifteen microns.
18. The device of claim 16 , wherein the first region has charge balance greater than negative five percent and less than zero percent.
19. The device of claim 15 further comprising a conductive layer electrically connected to the source region and the third region.
20. The device of claim 15 , wherein the control electrode comprises a trench control electrode extending into the semiconductor substrate, and wherein the third region overlaps the control electrode such that the control electrode terminates within the third region, and wherein the device further comprises a buffer layer, wherein the second region is between the buffer layer and the third region.