Novel process window and product yield improvement by eliminating contact shorts

Severe and unexpected yield loss (similar to 26% in avg.) is found in the early development stage of the advanced flash memory. The major failure mode, array bridging contact, is revealed as the root cause and mainly induced by undercutting photo-resist (PR) profile. In this work, a novel scheme, anti-etch bottom anti-reflective coating (anti-etch BARC), is used instead of the conventional dual ARC (BARC/dielectric ARC, DARC) stacks on amorphous carbon layer (ACL) for contact hole patterning. Herein, we successfully demonstrate to eliminate the failure issue, greatly improve the yield and provide a promising solution with manufacturing feasibility.