Experimental Analysis on Surface Profile of Sapphire Wafer after Polishing by Chemical Mechanical Polishing

Abstract

The study mainly explores the surface profile of sapphire wafer after polishing by the method of chemical mechanical polishing (CMP). Pattern-free polishing slurry with SiO2 abrasive particle is used to polish the sapphire wafer. This paper observes the phenomena of surface profile and surface scratches of sapphire wafer under different pressures and different rotational velocities during CMP. The study uses atomic force microscope (AFM) to scan the surface of sapphire wafer focusing on three axial lines of 0∘, 45∘and 90∘from the position of near edge passing the center of sapphire wafer. The study also selects five positions on a specific area to draw the surface profiles on the axial lines of 0∘, 45∘and 90∘. It can be observed that the central area of sapphire wafer has lower depression than other areas because the central area is polished more polishing times. Besides, the depression on the central area of sapphire wafer has a greater depression value and it has more and larger surface scratches when it is polished under a greater down force and at a faster rotational velocity.

A review: green chemical mechanical polishing for metals and brittle wafers

“…In recent years, many studies have been focused on preparing novel abrasives [27,29,143], improving processing methods [144][145][146][147] and changing the composition of CMP slurries. Although these physical methods certainly improve the MRR and surface quality of sapphire, the preparation process of the new abrasives is complicated.…”