Influence of different polishing parameters on sapphire substrate CMP

Abstract:
Chemical mechanical polishing quality of sapphire substrate directly affects the yield and reliability of the device. The slurry and polishing technological parameters are the decisive factors of influencing CMP quality. In order to gain better utilization rate of slurry and better polishing effect, the effects of polishing parameters on removal rate and surface roughness for c-plane sapphire substrate were systematically studied, such as pH value, polishing pressure, rotational speed and slurry flow rate. From the results it can be indicated the removal rate increases first and then decreases with the increasing of pH value, polishing pressure, rotational speed and slurry flow rate. At the same time the surface roughness decreases first and then increases with the increasing of pH value, polishing pressure and rotational speed, and it slows down with the increasing of slurry flow rate. Under the condition of optimal parameters of pH 10.5, polishing pressure 4 ψ, polishing head speed 40 r/min, platen rotation speed 45 r/min and slurry flow rate 160 mL/min, the removal rate can be stable at 2.69 um/h and the surface roughness Sq is 0.184 nm. This rule is of great significance to guide industrial production. Keywords: Sapphire substrate, Chemical-mechanical polishing (CMP), Removal Rate, Surface roughness, Polishing parameters