Mechanism and performance optimization of diethylenetriamine in selectivity ratios for silicon and copper removal during TSV back-side CMP

This study aimed to optimize the backside chemical mechanical polishing (CMP) process of silicon through-hole (TSV) wafers by investigating diethylenetriamine (DETA). The study reveals DETA's synergistic mechanism through electrochemical analysis, characterization (FESEM/XPS), and density-functional theory (DFT) calculations. Under optimized conditions (1.5 wt% SiO 2 , 0.05 wt% SDBS and 0.25 wt% DETA), a high Si-to-Cu removal rate ratio of 16.7 is achieved, with a Si removal rate exceeding 1 μm/min. This ensures efficient Cu pillar exposure. Furthermore, surface roughness is significantly improved: Si Sq decreases from 1.790 nm to 0.825 nm and Cu Sq from 3.190 nm to 1.540 nm. The total thickness variation (TTV) meets industry standards. The findings provide a viable process optimization scheme and theoretical support for high-precision TSV polishing. • Reveals novel dual-function mechanism of diethylenetriamine (DETA) in TSV-CMP. • Following optimization of the conditions, great process performance was achieved. • The feasibility and industry applicability of this process have been demonstrated.