AGING EFFECTS OF PEG AND SPS ON FILLING CAPABILITY OF CU ELECTROCHEMICAL DEPOSITION

摘要

The degradation effects on PEG-containing baths are investigated in this study. The baths are analyzed by three methods: in-situ measured v-t curves of galvanostatic plating, AC-impedance scan, and i-E curve scan. The gap-filling capability for the baths was examined by cross-sectional SEM images. By modifying the mechanisms mat were presented in previous literatures, some possible models for the degradation are proposed. In the PEG-containing bath, an evident deterioration of the gap-filling yield and of the surface roughness of the deposited film are observed after ECD aging. Two mechanisms are proposed to explain this degradation: 1) crack of long-chain PEGs, and 2) complexing between PEGs and Cu ions. When some long-chain PEGs crack into shot-chain ones, the remained long-chain PEGs still dominate the value of cell voltage, while slight fluctuation in voltages is attributed to the formation of complexes that results from the continuously cleaved short-chain PEGs.