Eliminating backgrind defects with wet chemical etching

摘要

Back-grinding and wet etching are necessary processes at the end of many IC fabrication sequences. Properly tuning a wet-etch process helps to maximize relief of stress and damage in wafers and dies. With a tightly controlled wet-etch process,tests reveal that removing a minimal 8μm of backside silicon after back-grinding can eliminate 80 of warp and stress. Total thickness variation of tested wafers remained very low after removing between 8 and 20μm. The greatest wafer and die strengthimprovement occurred after removing 30μm of damaged backside silicon.