Method for forming p-type lightly doped drain region using germanium pre-amorphous treatment

Abstract

A method for forming a MOS device with an ultra shallow lightly doped diffusion region includes providing a gate dielectric layer overlying a substrate surface region, forming a gate structure overlying the gate dielectric layer, performing a first implant process using a germanium species to form an amorphous region within an LDD region using the gate structure as a mask, and performing a second implant process in the LDD region using a P-type impurity and a carbon species. A first thermal process activates the P-type impurity in the LDD region, forming side wall spacers overlying the gate structure, and performing a third implant process using a first impurity to form active source/drain regions in a vicinity of the surface region adjacent to the gate structure using the gate structure and the spacers as a mask. A second thermal process then activates the first impurity in the active source/drain regions.