Patent ID: 8283222

Claim:
A method comprising: forming a first gate structure and a second gate structure over a substrate, the first gate structure including a first gate dielectric layer and the second gate structure including a second gate dielectric layer, wherein the forming the first gate structure and the second gate structure includes a gate replacement process where a dummy gate of the first gate structure and the second gate structure is replaced with a metal gate, and during the gate replacement process: after removing the dummy gate of the first gate structure and the second gate structure, implanting a portion of the substrate to increase an oxidation rate of the portion of the substrate, wherein a dummy gate dielectric layer is disposed over the portion of the substrate; and after removing the dummy gate dielectric layer, simultaneously forming the first gate dielectric layer and the second gate dielectric layer over the substrate, wherein the second gate dielectric layer is formed over the implanted portion of the substrate and the first gate dielectric layer is formed over a non-implanted portion of the substrate, wherein the first gate dielectric layer has a first thickness and the second gate dielectric layer has a second thickness that is greater than the first thickness.