Effect of under-layer treatment of Ta/TaN barrier film on corrosion between Cu seed and Ta in chemical-mechanical-polishing slurry.
Tantalum/tantalum nitride (Ta/TaNx) composite film is widely used as a copper (Cu) diffusion barrier layer. In order to reduce via-resistance, an additional argon (Ar) re-sputtering process is used to thin the barrier thickness at the feature bottom. In this study, the effect of Ar re-sputtering of the under-layer of TaNx barrier films on the corrosion between Cu seeds and upper Ta films in chemical-mechanical-polishing (CMP) slurries was investigated. The results show that Ar re-sputtering of the under-layer of the TaNx barrier has a strong influence on the corrosion of Cu seeds and Ta films. The equivalent circuit, simulated using data from electrochemical analysis, reveals changes in resistance and capacitance elements of the Cu-Ta electrochemical system, proving that the phase transformation of upper Ta films under different TaNx conditions leads to different degrees corrosion of Cu seeds and the Ta films.
Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan, Republic of China.
Wen-Hsi
WH
Lee
Chi-Cheng
CC
Hung
Yu-Sheng
YS
Wang
Shih-Chieh
SC
Chang
Ying-Lang
YL
Wang