硅通孔铜互连甲基磺酸铜电镀液中氯离子的作用

摘要

The effect of chloride ion on via filling by highspeed plating in a methanesulfonic acid (MSA) bath composed of Cu(CH3SO3)2 40 g/L, MSA 60 g/L, and Cl- 50 mg/L for TSV (through-silicon via) copper interconnection was studied. The influence of chloride ion under different forced convection conditions was discussed using rotating disk electrode. The reaction mechanism of chloride ion during copper electrodeposition and coordination field of copper(I) ion in presence of chloride ion were characterized by electrochemical impedance spectroscopy (EIS) and electron paramagnetic resonance (EPR) analysis, respectively. The results indicated that in the bottom of via where the copper electrodeposition is diffusion-controlled, chloride ion accelerates deposition; while at the top of via where the copper electro- deposition is non-diffusion-controlled, especially at high current density area, chloride ion inhibits deposition. The existence of chloride ion enhances the TSV filling effect and velocity.%研究了硅通孔(TSV)镀铜用甲基磺酸铜高速镀液(由Cu(CH3SO3)2 40 g/L、甲基磺酸60 g/L及Cl- 50 mg/L组成)中氯离子的作用机理.采用旋转圆盘电极研究了不同扩散条件下Cl-的作用效果,并采用电化学阻抗谱(EIS)和电子顺磁共振(EPR)探讨了Cl-在铜电化学沉积中的影响机制和对Cu+配位场的影响.结果表明:在深孔内扩散控制条件下,Cl-对铜沉积有明显的加速作用；在表面非扩散控制区域,尤其是高电流密度区,Cl-具有一定的抑制效果.因此,Cl-的存在有利于改善TSV深孔镀铜填充效果,提高填充速率.