Abstract: A method for forming a self-aligned twin well region is provided. The method includes implanting a first well type doping species into the DHL such that its distribution remains stopped in the DHL above the silicon substrate, etching away a portion of the DHL using a photoresist mask, implanting a second well type doping species into the portions of the silicon substrate exposed by the etching, and moving a portion of the first well type doping species into the silicon substrate.

Abstract: A method and system for providing a twin well in a semiconductor device is described. The method and system include masking a first portion of the device such that a second portion of the device is exposed. A sacrificial layer has a first portion on the first portion of the device and a second portion on the second portion of the device. In one aspect, an oxidation stop layer may be below the sacrificial layer. The method and system include implanting a first well in the second portion of the device, exposing the first portion of the device after the first well is implanted, and oxidizing the second portion of sacrificial layer after the exposing. The method and system further include implanting the second well in the first portion of the device after the oxidizing and planarizing the device after the second well is implanted.