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

Abstract

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 2-hydroxyphosphonoacetic Acid (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 Å min−1, ∼ 350 Å min−1, ∼ 374 Å min−1, 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 Å, and the erosion was corrected by ∼ 1117 Å.