(Invited) Barrier Slurry Innovation for Cu-ULK Process

Abstract

With the application of Ultra low-k dielectric material in the advanced nodes, more and more challenges are elevated on barrier CMP. High removal rates of TEOS and barrier films are required to enable an effective removal, while tunable Cu RR and low ULK RR are needed to control the topography and stop in ULK layer. The k value shift of polished ULK also should be minimized. In this paper, we will report a barrier slurry for this application including slurry additives effect on removal rate selectivity, topography and k value. The corrosion control capability is also evaluated by soaking test. Through slurry formulation tuning, an optimal topography with good within wafer and within die non-uniformity are obtained. The control capability in removal rate and selectivity, k value shift of polished ULK, topography, and Cu corrosion were demonstrated.

Model-Based Optimization of CMP Process Parameters for Uniform Material Removal Selectivity in Cu/Barrier Planarization

“…Different slurry chemistries result in different MRR of Cu and barrier materials. 12,[14][15][16][17][18][19][20][21] Xu investigated the effect of H 2 O 2 on MRR and found that the MRR of Cu increases till 10 ml of H 2 O 2 per liter of the slurry while it decreases if the concentration of H 2 O 2 is increased beyond 10 ml. 22 Cao studied the MRR of TiN, NDC, and Cu and found an optimized slurry formulation that can meet the requirements of the new integration scheme.…”

“…Yao found the optimized H 2 O 2 concentration as well as the optimized speeds of head and platen and was able to obtain near 1:1 MRR selectivity of Cu and ULK. 15 Maryama compared the CMP performance of Ru and Ta and formulated a slurry resulting in dishing of copper less than 30 nm when Ru is used as barrier liner. 13 The dishing of Cu reported is less with Ru as compared to dishing of Cu when Ta is used as a barrier liner.…”