Removal rate and surface quality of the GLSI silicon substrate during the CMP process

Abstract

Silicon wafers have been widely used as substrate in the Giga large-scale integration (GLSI). Silicon chemical mechanical polishing (CMP) factors are very important for the polished silicon surface state, because they play an important role in the quality and yield of devices. The effect of CMP factors on silicon substrate removal rate and surface quality used for advanced technology nodes integrated circuit (IC) manufacturing was the focus of this study. In particular, the effect of pH, temperature, and abrasive concentration on silicon CMP were investigated. The alkaline slurry used in the experiments was a non-hydrogen peroxide based system containing a novel type chelating agent and a surfactant. The pH experiments showed that the silicon removal rate depends on the slurry pH, surface roughness and haze are decreasing with the increase of the slurry pH. The temperature and abrasive concentration experiments proved that the polishing temperature and the abrasive concentration have some effect on silicon removal rate, surface roughness, and haze. The silicon removal rate increases with the increase of the abrasive concentration, while the surface roughness and haze decrease; moreover, with the increase of the polishing temperature, the silicon removal rate, surface roughness, and haze increase. Silicon CMP is a combination of mechanical and chemical processes, which shows that the increase in both the mechanical and chemical effects can contribute to the increase in the silicon removal rate. Furthermore, the surface quality (roughness and haze) depends on the mechanical and chemical effects; the increase in the chemical effect is favorable but that in the mechanical effect is harmful to the surface quality. The results obtained facilitate the study of silicon CMP and other materials.