Non-distort spacer profile during subsequent processing

Abstract

A method for fabricating a junction for a field effect transistor which does not cause distortion of the sidewall spacers during subsequent processing thereby reducing junction depletion and source to drain leakage. The process begins by providing a substrate structure having a gate thereon. Sidewall spacers are formed on the sidewalls of the gate. Impurity ions are implanted into the substrate structure adjacent to the gate to form source and drain regions. A resist protect oxide layer is formed over the substrate structure. The resist protect oxide is patterned by forming a mask over the resist protect oxide layer having an opening over the gate and the source and drain regions. The resist protect oxide layer is selectively etched; thereby removing the resist protect oxide over the source and drain regions without distorting the sidewall spacers. A silicide region is formed on the source and drain regions using a salicide process comprising a pre-amorphous implant and one or more rapid thermal anneal steps. The undistorted sidewall spacers reduce the distance that pre-amorphous implant damage extends under the gate during subsequent processing, which reduces the damage induced impurity ion diffusion under the gate. Because there is less impurity ion diffusion under the gate, junction depletion and source to drain leakage are reduced.