新型碱性清洗液对铝栅CMP后硅溶胶的去除

Removal of the Silica Sol After the Al Gate CMP by the New Alkaline Cleaning Solution

针对铝栅化学机械抛光(CMP)后硅溶胶颗粒残留等问题,研制了新型FA/O碱性清洗液并进行CMP后清洗实验。清洗液主要成分是FA/OⅡ螯合剂和O-20非离子型活性剂,由金相显微镜和原子力显微镜检测结果得出:FA/OⅡ螯合剂可以有效去除硅溶胶颗粒,当不加入FA/OⅡ螯合剂时,残留颗粒较多;当螯合剂体积分数为0.05‰~0.2‰时,残留颗粒数量明显下降。通过电化学工作站可知:随着O-20非离子型活性剂体积分数的提升(0~2‰),铝栅自腐蚀电流逐渐降低,由5.195μA下降到1.024μA。通过改变清洗液中螯合剂和活性剂的体积配比做单因素实验,得到最佳清洗效果和最弱腐蚀。实验结果表明:当清洗液中FA/OⅡ体积分数为0.15‰,O-20活性剂体积分数为1.5‰时,pH>10,表面粗糙度为2.4 nm,硅溶胶颗粒去除效果比较好且非均匀腐蚀比较弱。

A new FA/O alkaline cleaning solution was prepared to solve the silica sol particle remain problem in the chemical mechanical polishing（CMP）of Al gate.The main components of the cleaning solution are FA/OⅡchelating agent and O-20 non-ionic active agent.The results tested by the metallographic microscope and atomic force microscope show that the FA/OⅡchelating agent can effectively remove the silica sol particles,while there still remain more particles without the FA/OⅡchelating agent.When the volume fraction of the FA/OⅡchelating agent is0.05‰-0.2‰,the number of residual particles decreases obviously.The comparison experiment carried out by the electrochemical workstation indicates that the self-corrosion current of the Al gate gradually decreases from5.195μA to 1.024μA with the increase of the O-20 non-ionic active agent volume fraction（0-2‰）.To achieve the best cleaning effect and weakest corrosion,a series of single-factor experiments were carried out by changing the volume ratio of the chelating agent and active agent.The experiment results show that when the volume fraction of the FA/OII chelating agent is 0.15‰and the volume fraction of the O-20 active agent is 1.5‰,pH10 and the surface roughness is 2.4 nm,the removing effect of the silica sol particles is better and the non-uniform corrosion is weaker.