Research on Ultra-Precision Polishing Process of Semiconductor Wafer Surface Based on Disc Hydrodynamic Polishing

Abstract

Nowadays, the fabrication of ultra-smooth surface play critical roles in, integrated circuits (IC) manufacturing, especially for semiconductor substrate materials of silicon, silicon dioxide and silicon carbide wafer. To efficiently production ultra-smooth semiconductor wafer surface, a novel Disc Hydrodynamic Polishing (DHDP) process is proposed. In DHDP process, the polishing slurry was injected from the center of polishing tool and a screw pressure groove was designed on the polishing pad. Then, the fluid film will be formed between the disc polishing pad and the wafer surface, under the high rotation speed and applied load of disc polishing tool. In the fluid film, the particles were droved by the hydrodynamic pressure and shear stress impact the wafer workpiece. The abrasive particles erode the workpiece under the hydrodynamic pressure in the fluid film. Then, the effect of tool speed and machining time on the quality of surface is studied, through a series of experiments. The rotational speed of polishing tool can improve the surface quality. The surface of fused quartz glass wafer surface roughness(Ra) could reach 0.7nm and the peak value(PV) is 8.9nm, which was polished by DHDP process. Moreover, DHDP process can efficiently reduce the surface roughness and acquire ultra-smooth surface for semiconductor wafer.