乙醇对低磨料CMP过程中铜膜凹凸处去除速率选择性的影响

Effect of Ethanol on the Rate Selectivity of Copper Film Concave Position and Convex Position in the CMP Process with Low Abrasive Concentration

根据相似相容原理,在低磨料浓度CMP过程中,利用乙醇对多羟多胺螯合剂的降黏特性来提高铜膜表面凹凸处抛光速率的选择性。根据抛光液中各组分浓度对动态和静态条件下铜膜去除速率的影响获得乙醇加入量的最大值;通过螯合剂、氧化剂与乙醇对动静态条件下铜膜去除速率的相互作用关系来确定各组分的最佳浓度。最终得出当各组的体积分数为:磨料0.5%,螯合剂10%,H2O20.5%,乙醇1%时,铜膜表面拥有最大的凸处和凹处速率比。在MIT 854铜布线片上进行平坦化试验,结果表明:该抛光液能够很大程度的减小布线表面的高低差,拥有较强的平坦化能力。红外光谱检测结果表明:在CMP过程中,铜膜表面不会生成副产物乙酸乙酯。上述结果进一步证实了该抛光液的实用性。

According to the similarity law, in the chemical mechanical polishing（CMP） process with low abrasive concentration, the rate selectivity of copper film concave position and convex position can be sharply improved using the reducing viscosity properties of ethanol on the chelating agent with polyhydric and polyamine. According to the influence of slurry components concentration on removal rate of Cu film under CMP and static conditions, the maximum amount of ethanol was obtained. Through the interaction of chelating agent, oxidizing agent and ethanol on the copper film removal rate under CMP and static conditions, the best concentration of each component was acquired. When the abrasive concentration（volume fraction） is 0.5%, agent concentration is 10%, the H2O2 concentration is 0.5%, and the ethanol concentration is 1%, the largest rate selectivity of concave position and convex position is acquired on the copper surface. The planarization experiment was conducted on MIT 854 wafer surface. The results show that： the slurry with strong planarization ability can significantly reduce the wiring surface step height. In the CMP process, the ethyl acetate as the byproduct will not be generated, which further confirms the usefulness of the slurry.