Semiconductor device and method of forming the same

A semiconductor device, comprising:

• a semiconductor substrate;
• a first conductive type body region in the semiconductor substrate;
• a second conductive type first source/drain region in the semiconductor substrate, the first source/drain region being spaced apart from the body region;
• a second conductive type second source/drain region in the body region;
• a shallow trench isolation between the body region and the first source/drain region, the shallow trench isolation being spaced apart from the body region;
• a second conductive type drift region surrounding the first source/drain region and the shallow trench isolation, the drift region including first and second drift inner regions adjacent to the shallow trench isolation, wherein the second drift inner region is below the shallow trench isolation, and the first drift inner region is between the body region and the second drift inner region;
• a first conductive type well in contact with a bottom of the body region and a bottom of the drift region, the well vertically overlapping the first and second drift inner regions;
• and
• a gate pattern on the semiconductor substrate, the gate pattern being between the first source/drain region and the second source/drain region,
• wherein:
• the first drift inner region includes a first conductive type dopant and a second conductive type dopant,
• the second drift inner region includes the first conductive type dopant and the second conductive type dopant, and
• a difference between an average density of the first conductive type dopant and an average density of the second conductive type dopant in the first drift inner region is greater than a difference between an average density of the first conductive type dopant and an average density of the second conductive type dopant in the second drift inner region.

A semiconductor device, comprising:

• a semiconductor substrate;
• a first conductive type body region in the semiconductor substrate;
• a second conductive type first source/drain region in the semiconductor substrate, the first source/drain region being spaced apart from the body region;
• a second conductive type second source/drain region in the body region;
• a shallow trench isolation between the body region and the first source/drain region, the shallow trench isolation being spaced apart from the body region;
• and
• a second conductive type drift region surrounding the first source/drain region and the shallow trench isolation, the drift region including a lower drift region, and an upper drift region,
• wherein the lower drift region is between the body region and the upper drift region and extends below the upper drift regions, the upper drift region includes a first upper drift region and a second upper drift region, the first upper drift region is between the body region and the second upper drift region, the second upper drift region is between the first upper drift region and the first source/drain region, the lower drift region and the upper drift regions each include a first conductive type dopant and a second conductive type dopant, an average density of the first conductive type dopant in the second upper drift region is greater than an average density of the first conductive type dopant in the first upper drift region.