Semiconductor devices and methods for forming a semiconductor device
A method for forming a semiconductor device includes incorporating dopants of a first conductivity type into a nearby body region portion of a semiconductor substrate having a base doping of the first conductivity type. The incorporation of the dopants of the first conductivity type is masked by a mask structure at at least part of an edge region of the semiconductor substrate. The method further includes forming a body region of a transistor structure of a second conductivity type in the semiconductor substrate. The nearby body region portion of the semiconductor substrate is located adjacent to the body region of the transistor structure.
1. A method for forming a semiconductor device, the method comprising:
forming a laterally varying doping region comprising a second conductivity type in an edge region of a semiconductor substrate;
incorporating dopants of a first conductivity type into a nearby body region portion of the semiconductor substrate comprising a base doping of the first conductivity type and into at least a surface portion of the semiconductor substrate located between the laterally varying doping region and a surface of the semiconductor substrate during the same incorporation process before or after forming the laterally varying doping region, wherein a number of dopants of the first conductivity type in the surface portion is larger than a number of dopants of the second conductivity type in the surface portion; and
forming a body region of a transistor structure of a second conductivity type in the semiconductor substrate, wherein the nearby body region portion of the semiconductor substrate is located adjacent to the body region of the transistor structure.
2. The method of claim 1 , wherein the dopants of the first conductivity type are incorporated with an implantation dose of between 1*10 11 dopants per cm 2 and 1.5*10 12 dopants per cm 2 .
3. The method of claim 1 , wherein the base doping concentration of the semiconductor substrate is at least 1*10 12 dopants per cm 3 .
4. The method of claim 1 , wherein a doping concentration of the base doping at a depth equal to a maximal depth of the body region is lower than 80% of a maximal doping concentration of the base doping of the semiconductor substrate.
5. The method of claim 1 , wherein the incorporation of dopants of the first conductivity type increases the base doping of the semiconductor substrate by at least one order of magnitude within the nearby body region portion of the semiconductor substrate.
6. The method of claim 1 , wherein the incorporation of dopants of the first conductivity type increases the base doping of the semiconductor substrate within a depth of at least 1 μm from a p-n junction between the body region and the drift region of the transistor structure.
7. The method of claim 1 , further comprising forming a dielectric layer structure at the surface of the semiconductor substrate after forming the laterally varying doping region and before incorporating the dopants of the first conductivity type.
8. The method of claim 1 , further comprising one or more annealing processes for forming a p-n junction between the surface portion and the laterally varying doping region.
9. The method of claim 1 , wherein the laterally varying doping region is formed by incorporating gallium, aluminum or boron dopants into the edge region of the semiconductor substrate.