GLSI铜布线碱性抛光液中磨料的稳定性

Stability of the Abrasive in the Alkaline Slurry for the GLSI Copper Wiring

在铜化学机械抛光中硅溶胶作为磨料起到重要的机械作用。但硅溶胶本身存在热力学上的不稳定性和动力学上的稳定性。研究了pH值、甘氨酸质量分数以及硅溶胶质量分数对抛光液中硅溶胶的粒径和Zeta电位的影响。结果表明,硅溶胶稳定性影响主要表现在pH为10.5时,体系具有最大的Zeta电位。甘氨酸质量分数在小于2%和硅溶胶质量分数小于5%时,有利于胶体的稳定性。利用DLVO理论和空位稳定理论对实验现象进行分析,研究了硅溶胶稳定机理。根据稳定性结论,优化抛光液组分,得到抛光速率稳定的碱性铜布线抛光液,稳定时间超过14天。

In the copper chemical mechanical polishing process, silica sol plays an important role as the abrasive for mechanical abrasion action. But the silica sol is thermodynamically unstable and kinetically stable, The effects of the pH value, glycine mass fraction and silica sol mass frac- tion on the particle site and Zeta potential for the silica sol in the slurry were studied. The results show that the silica sol is stable when the pH value is 10.5 and the system has the maximum Zeta potential. It is conducive to the stability of the silica sol with the glycine mass fraction less than 2% and the silica sol mass fraction less than 5%. By DLVO theory and steric stabilization theo- ry, the experimental phenomenon was analyzed and the silica sol stabilization mechanism was studied. Based on the stability conclusion, the slurry component was optimized to obtain the al- kaline copper wiring slurry with the stable copper polishing rate, and the settling time of the slur- ry exceeded 14 days.