Power semiconductor device having improved performance and method
View Patent ↗In one embodiment, a semiconductor device is formed in a body of semiconductor material. The semiconductor device includes a counter-doped drain region spaced apart from a channel region.
1. A semiconductor device, comprising:
a substrate having a major surface, wherein the substrate comprises a first conductivity type;
a pedestal structure formed overlying a portion of the major surface;
a conductive material disposed along a side surface of the pedestal structure to form a first conduction electrode of the semiconductor device;
a body region of a second conductivity type formed in the substrate adjacent the major surface and the first conduction electrode, wherein a portion of the body region forms a channel region when the semiconductor device is in operation;
a current carrying region of the first conductivity type formed in the body region;
a first doped region of the second conductivity type formed in the substrate in proximity to a drain edge of the channel region so that the first doped region enhances breakdown voltage of the semiconductor device when in operation, wherein the first doped region is spaced apart from the body region so that a portion of the substrate is between the body region and the first doped region in proximity to the first major surface; and
a first conductive layer in contact with the first doped region.
2. The semiconductor device of claim 1 , wherein the substrate includes a semiconductor layer of the first conductivity type formed overlying the substrate, wherein the semiconductor layer has a lower doping concentration than the substrate.
3. The semiconductor device of claim 2 further comprising a second doped region of the first conductivity type formed adjacent the major surface between the body region and the first doped region, wherein the second doped region has a greater doping concentration than the semiconductor layer, and wherein the second doped region is configured to provide a low resistance current path for the semiconductor device when in operation.
4. The semiconductor device of claim 1 wherein a second surface of the substrate forms a second conduction electrode.
5. The semiconductor device of claim 1 , further comprising a second conductive layer electrically coupled to the current carrying region, and wherein the first conductive layer is electrically coupled to the second conductive layer.
6. The semiconductor device of claim 1 wherein the first conductive layer comprises polycrystalline silicon.
7. The semiconductor device of claim 1 wherein the first doped region is spaced a distance in a range from about 0.5 microns to about 3.0 microns from the body region.
8. The semiconductor device of claim 1 , wherein the pedestal structure includes:
a first dielectric layer formed overlying the major surface of the substrate;
a second dielectric layer formed overlying the first dielectric layer; and
a second conductive layer formed overlying the second dielectric layer, wherein the second conductive layer is coupled to the first conduction electrode.
9. The semiconductor device of claim 8 , wherein the second conductive layer includes polycrystalline silicon.
10. A method for forming a semiconductor device, comprising the steps of:
providing a substrate having a major surface, wherein the substrate comprises a first conductivity type;
forming a pedestal structure on a portion of the major surface;
forming a conductive material along a side surface of the pedestal structure configured as a first conduction electrode of the semiconductor device;
forming a body region of a second conductivity type in the substrate adjacent the major surface and the first conduction electrode, wherein a portion of the body region forms a channel region when the semiconductor device is in operation;
forming a current carrying region of the first conductivity type in the body region;
forming a first doped region of the second conductivity type in the substrate in proximity to a drain edge of the channel region so that the first doped region enhances breakdown voltage of the semiconductor device when in operation, wherein the first doped region is spaced apart from the body region so that a portion of the substrate is between the body region and the first doped region in proximity to the first major surface; and
forming a first conductive layer in contact with the first doped region.
11. The method of claim 10 , wherein the step of providing substrate includes providing a substrate having a semiconductor layer of the first conductivity type formed overlying the substrate, wherein the semiconductor layer has a lower doping concentration than the substrate.
12. The method of claim 11 wherein the step of providing the substrate includes providing a substrate comprising a second doped region of the first conductivity type formed adjacent the major surface between the body region and the first doped region, wherein the second doped region has a greater doping concentration than the semiconductor layer, and wherein the second doped region is configured to provide a low resistance current path for the semiconductor device when in operation.
13. The method of claim 10 , further comprising the step of forming a second conductive layer electrically coupled to the currently carrying region; and electrically coupling the second conductive layer to the first conductive layer.
14. The method of claim 10 wherein the step of forming the first conductive layer comprises forming a polycrystalline silicon layer.