基于Arrhenius方程研究活性剂对铜CMP粗糙度的影响

Study on the Effect of the Surfactant on the Roughness for Cu CMP Based on Arrhenius Equation

选用非离子表面活性剂脂肪醇聚氧乙烯醚(AEO),通过自制的碱性铜抛光液,在E460E机台上研究不同体积分数活性剂对铜化学机械抛光(CMP)效果的影响。利用原子力显微镜(AFM)观察抛光后铜表面粗糙度,采用接触角测试仪测试不同的抛光液在铜表面的接触角。结果表明:铜抛光速率随着活性剂体积分数的增加呈缓慢降低趋势,加入活性剂可显著降低抛光后铜表面粗糙度。当加入体积分数3.0%的活性剂时,铜抛光速率从678.096 nm/min降低到625.638 nm/min,同时铜表面粗糙度从10.52 nm降低到1.784 nm,接触角从28.33°降低到12.25°。活性剂分子优先吸附在抛光后铜表面形成一层分子膜,表面粗糙度降低的根本原因是该分子膜增加了化学反应的活化能以及提高了抛光液的润湿性。基于Arrhenius方程,从活化能和温度两个参数阐述活性剂降低铜表面粗糙度的机制。

Using fatty alcohol polyoxyethylene ether（AEO）nonionic surfactant,the influences of the surfactants with different volume fractions on the effects of Cu chemical mechanical planarization（CMP）were investigated with the home-made alkaline copper slurries on the E460 E platform.The polished Cu surface roughness was observed by the atomic force microscopy（AFM）,and the contact angles between the Cu surface and different slurries were measured by the contact angle measuring device.The results show that the Cu polishing rate decreases slowly with the increase of the surfactant volume fraction,and the polished Cu surface roughness decreases significantly by adding the surfactant.When adding the surfactant with the volume fraction of 3.0%in the slurry,the Cu polishing rate decreases from678.096 nm/min to 625.638 nm/min,meanwhile the Cu surface roughness decreases from10.52 nm to 1.784 nm,and the contact angle decreases from^28.33°to 12.25°.A layer of the molecular film was formed through surfactants adsorbing preferentially on the polished Cu surface.The root cause of the decrease of the Cu surface roughness is that the molecular film layer increases the activation energy and improves the wettability of the slurry.Based on the Arrhenius equation,the mechanism of the surfactant reducing the Cu surface roughness was discussed from the parameters of the activation energy and temperature.