深硅刻蚀晶圆位置偏移分析与研究

Analysis and Research of Deep Silicon Etching Wafer Position Deviation

晶圆位置偏移过大是导致深硅刻蚀设备发生传片报警问题的主要原因之一,尤其是在采用静电卡盘的设备中。阐述了晶圆位置发生偏移原因,重点研究了解吸附配方、顶针驱动和片间清洗方案。研究表明,静电吸盘的表面聚合物残留是导致静电释放不充分的主要因素,表面聚合物的清除有助于优化晶圆位置偏移。电动三针在固有残留静电力的情况下,通过缓慢连续升针方案缓解了跳片现象。优化片间清洗方案大幅减小表面聚合物残留。实验结果表明:优化后的解吸附配方为工艺时长90 s、电极功率1000 W、气压20 mTorr(1 mTorr≈0.133 Pa)、氩气体积流量250 mL/min,电动三针接触晶圆前、接触中、脱离静电吸盘后的升针速度分别为3、2和6 mm/s,在上述工艺条件下,通过进一步优化片间清洗方案,使得晶圆位置偏移量从初始的2~6 mm降至0.2 mm以内。

Excessive wafer position deviation is one of the main reasons for the wafer transmission alarm problem in deep silicon etching equipment,especially in the equipment with electrostatic chuck.The reason for wafer position deviation was explained.Recipe of dechuck,top needle drive and wafer to wafer clean scheme were focused on research.The research results show that the residual polymer on the surface of electrostatic chuck is the major factor that leads to insufficient electrostatic discharge.Thoroughly removing it is the appropriate method to optimize the wafer position deviation.Under condition of inherent residual electrostatic force,the phenomenon of wafer slip-off is alleviated by slowly and continuously lifting the motor-driven three needles.The optimized wafer to wafer cleaning scheme greatly reduces the surface polymer residue.The results show that the optimized recipe of dechuck is a process time of 90 s,an electrode power of 1000 W,a gas pressure of 20 mTorr(1 mTorr≈0.133 Pa)and an argon gas volume flow of 250 mL/min.The needle lifting speeds of the motor-driven three needles before contact with the wafer,during contact and after removing the electrostatic sucker are 3,2 and 6 mm/s,respectively.Under the above process conditions,by further optimizing the wafer to wafer cleaning scheme,the wafer position deviation reduces from the initial 2~6 mm to within 0.2 mm.