The removal rate of slurry is the key factor in chemical mechanical planarization (CMP) for through-silicon vias copper film. Currently, in the study of slurry, the synergistic effect of some additives can produce the effect of “1+1>2”. It is widely used in semiconductor and microelectronics industries to develop novel slurry. Here, ammonium citrates served as a crucial chemical additive in through silicon via Cu film slurries. Through electrochemical measurements, X-ray photoelectron spectroscopy, ultraviolet-visible, and LSCM tests, it was revealed that ammonium citrates could react with cupric ions to form a stable water-soluble Cu-ammonium citrates complex, which can accelerate the chemical dissolution of Cu surface during the CMP process, and it was also found that the complexing effect was weaker than glycine. Moreover, various tests on Cu wafers showed that a high Cu removal rate and ideal surface quality could be realized when ammonium citrates were used as an auxiliary complexing agent in glycine-based Cu film slurries. The purpose of the study is to find an auxiliary chemical additive that can improve the performance of slurry in the manufacturing process of Cu film and other materials used in integrated circuits.
Copper(Cu) has been an interconnect material widely used in giant-large scale integrated circuits (GLSI). Corrosion inhibition is a key factor to ensure global planarization of Cu in the chemical mechanical planarization slurry. Here, three selected inhibitors BTA(Benzotriazole), TAZ(1,2,4-triazole), and MBO( 2-Benzoxazolethione) were investigated for their inhibition behaviors and synergy on the Cu surface. The results show that they are all effective Cu inhibitors in alkaline solutions. MBO loses its inhibition ability in H2O2, but BTA and TAZ do not. The calculated synergistic parameters of BTA/TAZ is 0.1763, X-ray photoelectron spectroscopy, and UV-Via experiments show that the antagonism between them is caused by two competitive reactions due to the similar adsorption mechanism: one is the competition for the adsorption site on the surface, and the other is the competition of copper ions that affects the formation of Cu(I)-BTA. The calculated synergistic parameter of BTA/MBO is 1.7763, the synergy between them is obvious.
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