铜电致化学抛光抛光液的成分及其作用

Chemical Components and Its Functions of Polishing Solution Used in Electrogenerated Chemical Polishing of Copper

电致化学抛光是通过电化学反应生成刻蚀剂并利用扩散控制反应实现工件表面无应力抛光的新方法,抛光液的特性则是实现扩散控制反应和可控去除的关键因素。分析电致化学抛光的基本原理,并根据理论模型提出了抛光液所应具备的基本条件。针对铜的电致化学抛光,提出以FeSO_4为电活性中介体,H_2SO_4为p H调节剂,BTA为侧向电子传导抑制剂的抛光液。通过使用XRD以及XPS等表征手段对加工后的表面进行分析,研究了铜抛光液中的p H调节剂H_2SO_4以及侧向电子传导抑制剂BTA的作用机理。研究结果表明,pH调节剂H_2SO_4的主要功能为去除Cu表面的氧化层,从而促进刻蚀反应的进行,而BTA则通过吸附于铜工件表面,从而有效地抑制了加工过程中的侧向电子传导。

Electrogenerated chemical polishing（EGCP） is a new, stress-free polishing method. Stress free polishing of workpiece surface is realized by diffusion controlled chemical reaction and etchant is generated by electrochemical reaction on electrode surface. The components of polishing solution are the key factors to realize the diffusion controlled reaction and controllable material removal process. The basic principle of EGCP is analyzed, and the basic characteristics of polishing solution are proposed according to the theoretical analysis. For realizing EGCP of Cu, the FeSO_4（redox mediator）, H_2SO_4（p H adjusting agent） and BTA（lateral charge propagation inhibitor） are chosen as the polishing solution. Through analyzing the surface components of polished workpiece by XPS and XRD, the action mechanisms of H_2SO_4 and BTA are studied. The results show that the H_2SO_4 is benefit to promoting the etching reaction through removing the Cu oxide layer. BTA can be adsorbed on the Cu surface, and then suppresses surface lateral charge propagation.