Patent ID: 8716097

Claim:
A method of forming a Metal-Oxide Semiconductor (MOS) transistor, comprising: forming a well doped with a second doping type in a semiconductor surface doped with a first dopant type having a baseline doping level, said well forming a well-substrate junction having a well depletion region; ion implantation with said first dopant type at a dose and energy to form a retrograde doped region below said well-substrate junction having a peak first dopant concentration of between five (5) and one hundred (100) times above said baseline doping level at a location of said peak first dopant concentration, wherein with zero bias across said well-substrate junction at least (>) ninety (90) % of a total dose of said retrograde doped region is below a bottom of said well depletion region; forming a gate structure on said well, and forming source and drain regions on opposing sides of said gate structure.