Method and system for creating self-aligned twin wells with co-planar surfaces in a semiconductor device

A method for providing a twin well in a semiconductor device comprising:

• providing at least one blanket interference layer on the semiconductor device;
• providing at least one reflective layer on the at least one blanket interference layer;
• providing a BARC on the at least one reflective layer;
• providing a first photoresist layer on the BARC;
• forming a first mask from the first photoresist layer, the first mask covering a first portion of the semiconductor device and uncovering a second portion of the device;
• removing a portion of the BARC on the second portion of the semiconductor device;
• removing a portion of the at least one reflective layer on the second portion of the semiconductor device;
• implanting a first well, the first mask being configured such that the first well resides in the second portion of the semiconductor device;
• removing the first mask
• removing a remaining portion of the BARC on the first portion of the semiconductor device;
• providing a second photoresist layer;
• providing a blanket exposure of light on the semiconductor device, wherein the at least one blanket interference layer and a remaining portion of the at least one reflective layer are configured such that the light undergoes destructive interference in the portion of the second photoresist layer in the second portion of the semiconductor device but not in the portion of the second photoresist layer in the first portion of the semiconductor device;
• removing a remaining portion of the at least one reflective layer on the first portion of the semiconductor device;
• and implanting a second well in the first portion of the semiconductor device.

A method of forming a semiconductor device comprising:

• depositing one or more interference layers including a reflective layer on a substrate;
• forming a first mask using a first photoresist layer, the first mask covering a first portion of the semiconductor device and uncovering a second portion of the semiconductor device;
• removing the portion of the reflective layer disposed in the second portion of the semiconductor;
• implanting a first well in the second portion of the semiconductor device using the first mask;
• removing the first mask and exposing a reflective layer disposed below the first mask;
• providing blanket exposure of light on the semiconductor device;
• reflecting a portion of the exposed light using the reflective layer disposed in the first portion of the semiconductor device to form a second mask on the second portion of the semiconductor device, the second mask uncovering the first portion of the semiconductor device and covering the second portion of the semiconductor device;
• removing the reflective layer;
• and
• implanting a second well in the first portion of the semiconductor device after the second mask is formed, wherein the second well having a co-planar surface with the first-well.