Precision treatment of silicon wafer edge utilizing ultrasonically assisted polishing technique

In our previous works, a new polishing approach and apparatus for silicon wafer edge treatment with ultrasonically assisted polishing (UAP) was proposed. In this paper, a novel polishing apparatus and method were presented for more effectively performing the edge polishing based on our previous works. The fundamental polishing characteristics of the novel method were demonstrated through a few experimental investigations carried out on the new apparatus. Because of an elliptic ultrasonic vibration of the polishing pad, abrasive particles within the slurry held by the pad impact the work surface at an extremely high acceleration. It leads to the high material removal rate and the good surface quality even at low rotational speed of the wafer or small supplying flow of slurry. The novel method is suitable for the fragile wafer edge polishing. By setting proper parameters, the surface roughness of wafer edge polished by the presented method is improved over 31.7% compared to that without UAP. The polishing effect of the novel polishing method can be further improved by applying high AC voltage.