TUNING THRESHOLD VOLTAGE THROUGH META STABLE PLASMA TREATMENT

摘要

The method includes forming a first high k dielectric layer over a first semiconductor region; forming a second high k dielectric layer over the second semiconductor region; forming a first metal layer comprising a first portion over the first high k dielectric layer and a second portion over the second high k dielectric layer; forming an etch mask over the second portion of the first metal layer; and etching the first portion of the first metal layer. The etch mask protects the second portion of the first metal layer. The etch mask is ashed using a metastable plasma. A second metal layer is then formed over the first high k dielectric layer.