In situ plasma pin-up clean process for backside bevel polymer removal, defect reduction, and queue time relaxation

Abstract

Polymeric residues and films of various thicknesses on the wafer backside and the edge frontside bevel and backside are known to cause substantial yield losses. An additional ex situ bevel etch step can clear away these buildups from the edge bevel area but not from the wafer backside. In this paper, we demonstrate a novel and innovative in situ pin-up plasma clean step that can effectively remove polymers from both the wafer backside and the edge bevel areas, eliminating the need for the bevel etch step. A physical analysis of blanket test wafers and patterned product wafers that have underwent the pin-up clean step in inductively coupled plasma and capacitively coupled plasma etch systems reveals that the pin-up clean step can reduce defect counts on product wafers and improve manufacturing cycle time and throughput by relaxing the queue time constraint.