Optimized gate implants for reducing dopant effects during gate etching

Abstract

A method and apparatus thereof for fabricating an integrated circuit on a laminate having a gate electrode layer over a silicon dioxide layer. Detection of the gate etch endpoint signal is improved by maximizing the use of a faster etching dopant material (e.g., n-type dopant) and minimizing the use of a slower etching dopant material (e.g., p-type dopant) in the gate electrode layer. In one embodiment, a first portion of the gate electrode layer, substantially corresponding only to the location at which a gate is to be formed, is doped with the slower etching dopant material. The remaining portion of the gate electrode layer is doped with the faster etching dopant material; thus, more of the gate electrode layer is doped with the faster etching dopant material than with the slower etching dopant material. A gate mask is aligned over the gate electrode layer, and the unmasked portions of the gate electrode layer are removed using an etchant. The n-doped portions of gate electrode layer will etch away faster, and because the gate electrode layer is predominantly n-type, a strong and detectable endpoint signal will be induced when the etchant reaches the silicon dioxide layer.