40Nm contact related process optimization for defect reduction

Ni (Nickel) piping, Contact openness, and W (Tungsten) recess are three major defects encountered in 40nm Contact related process development. In this paper, PAI (Pre- Amorphous Implantation) and Ni capping layer were optimized for Ni piping reduction. Contact etch process window was enlarged to eliminate Contact openness. The specific PMOS-localized defect phenomenon was studied. High ILD (Interlayer Dielectric) CMP oxide loss was found responsible to cause poor post-CMP uniformity, which was the main contributor to W recess defect thereafter. Finally, we had obtained an effective ILD thickness and uniformity control in CMP and thus, solving W recess defect.