Study of STI CMP Process Control on High Aspect Ratio Gap-fill Topographies by Motor Current EPD

Motor current endpoint detection (MC EPD) has been applied to shallow trench isolation chemical mechanical polishing (STI CMP) on mass production for a long time. However, impact of high aspect ratio (AR) gap-fill solutions on EPD signals is observed at 70nm technology node and beyond. The correlation between overfill topography and friction response is the major cause. Hence, STI CMP Process Control is getting more and more challenging as device scaling down. In this paper, STI CMP Process Control on high AR gap-fill topographies was studied by MC EPD. Four kinds of overfill topographies were polished for EPD signal investigation on a direct STI CMP process. In addition, effects of slurry, conditioner and polishing parameter on MC EPD signal were discussed as well. According to those phenomena, the friction evolution in process of STI CMP has been proposed to be a reference of process control.