缓蚀剂1,2,4-三唑在铜CMP过程中的作用机理

基于静态腐蚀试验和Arrhenius公式,探讨了缓蚀剂1,2,4-三唑在铜晶圆表面的吸附机制,分析了其对铜晶圆表面化学反应活化能的影响;结合CMP试验,阐释了BTA和1,2,4-三唑两种缓蚀剂对CMP材料去除速率的影响.结果表明:在酸性抛光液中,缓蚀剂1,2,4-三唑主要存在两种缓蚀机制:一是在铜表面形成吸附膜Cu:(1,2,4-TAH)_(ads),二是形成聚合物膜Cu(1,2,4-TA)_2.CMP过程中化学反应活化能的降低量不随抛光液中1,2,4-三唑的含量而变化.但是相对于BTA,使用含有1,2,4-三唑的抛光液时CMP过程中晶圆表面的化学反应活化能降低量较大,表明机械促进化学作用较强.本研究结果为CMP过程中抛光液的优化提供了理论支撑.

Mechanism of 1,2,4-Triazole during Copper Chemical Mechanical Planarization

Based on the static corrosion tests and Arrhenius equation, the inhibition efficiency and adsorption mechanism of 1,2,4-triazole were studied. Besides, the effect of 1,2,4-triazole on the activation energy of wafer surface was analyzed. Combining with chemical mechanical planarization (CMP) experiments, the effect of BTA and 1,2,4-triazole on material removal rate during CMP process was investigated. It is found that the two inhibition mechanisms of 1,2,4-triazole involved, i.e. the formation of physisorption or chemisorption layer on the surface and the formation of a polymeric film of Cu(1,2,4-TA)₂. The reduction amount of activation energy during CMP was independent on the concentration of 1,2,4-triazole in slurry. The reduction amount of activation energy during CMP using slurry containing 1,2,4-triazole was larger than that using slurry with BTA, which indicated stronger mechanically induced chemical effect. The results are useful for optimizing component of the CMP slurry.