Effects of pad features on motor current EPD signals and the performance of STI CMP process

摘要

In general, the performance of the shallow trench isolation chemical mechanical polishing (STI CMP) is crucial to the factor of hardware, parts, consumables, device layout, wafer surface topography and process recipe etc. Furthermore, the endpoint detection (EPD) is very sensitive to these factors, wafer topography and consumables especially. Therefore, applying these phenomena and behaviors to analyze and evaluate consumables is a workable assumption. In this paper, three kinds of polishing pads have been studied on motor current (MC) EPD signals, planarization efficiency (PE) and scratch reduction during a direct STI CMP process. According to the correlation between MC EPD signals and wafer topographies, novel analyzable method of the STI CMP PE has been proposed to simplify the pad evaluation. The results indicated that concentric circles groove pad showed better PE than perforated one, and the PE was proportional to the hardness of the polishing pad. On the other hand, effects of the grooved pattern and material/property on the scratch reduction were 50% and 75%, respectively. Perforated groove and polymer pad were good at the scratch reduction.