Patent ID: 9431251
Filing Date: 2016-08-30
CPC Classification: H01L

Claim Text:
1. A method of forming a semiconductor device, the method comprising: patterning a first mask over a substrate, wherein the patterned first mask has a first opening, and the substrate include a first dopant type; implanting ions having a second dopant type through the first opening into the substrate to form a first deep well; patterning a second mask over the substrate, wherein the patterned second mask has a second opening; implanting ions having the second dopant type through the second opening into the substrate to form a second deep well, wherein an energy for implanting ions to form the second deep well is lower than an energy for implanting ions to form the first deep well; implanting ions having the first dopant type into the substrate to form a first well, wherein the energy for implanting ions to form the second deep well is greater than an energy for implanting ions to form the first well; and forming a gate structure over the first well.