Effect of Ammonium Citrates as an Auxiliary Complexing Agent in TSV Copper Film CMP

Abstract

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.

The Role of Alanine in the Chemical Mechanical Polishing of Aluminum

“…In the absence of alanine in the polishing slurry, the aluminum surface exhibited significant roughness and distinct scratches due to the mechanical action of the abrasives. 23,24 However, the inclusion of alanine in the polishing slurry introduced a chelating agent that achieved equilibrium between the chemical and mechanical processes occurring on the aluminum surface, thereby enhancing the surface quality.…”

“…X-ray photoelectron spectroscopy.-XPS is used to investigate the chemical changes occurring on metal surfaces after various corresponded to 15.76% Al. 23 Figure 13b presents the fitted peaks for the surface of an aluminum foil immersed in a solution containing 1.5 wt% alanine. Two distinct peaks appeared, with binding energies of 75.0425 eV and 73.0469 eV, corresponding to 73.75% Al 2 O 3 and 26.25% Al, respectively.…”