The Effect of 2-hydroxyphosphonoacetic Acid on the Removal Rate Selectivity of Cu/Co/TEOS in H2O2 Based Alkaline Slurries

As the technology node shrinks to 14 nm, Co has been widely used as a liner in semiconductor devices. However, the dishing and erosion produced after fine polishing seriously affect the RC delay of the device, so achieving a reasonable Cu/Co/TEOS removal rate (RR) selectivity is the key to correct the dishing and erosion. In this paper, the effect of HPAA as a complexing agent on Cu/Co/TEOS RR selectivity in H2O2 based alkaline slurries was well investigated. In addition, the complexation mechanism between Co and HPAA was analyzed through electrochemical experiments, UV/vis, XPS tests, etc. The results showed that the RRs of Cu/Co/TEOS in the optimized slurry containing 5 wt% SiO2, 0.15 wt% H2O2, 0.05 wt% HPAA, 500 ppm TT-LYK at pH=10 are ~ 163 A/min, ~ 350 A/min, ~ 374 A/min, respectively. The RR selectivity of Co to Cu (VCo / VCu) and TEOS to Cu (VTEOS / VCu) were ~ 2.15 and ~ 2.3. At this time, the surface quality of the polished wafer was good, the dishing was corrected by ~ 910 A, and the erosion was corrected by ~ 1117 A.