Investigation on Slurry Flow and Temperature in Polishing Process of Quartz Glass Substrate

Abstract

A fluorescent agent was used instead of slurry to visualize the flow of slurry, the polishing liquid solution supplied in Chemical Mechanical Polishing (CMP). Under ultraviolet irradiation, the fluorescent agent emits light, which performs the flow of the slurry under the quartz glass, which is applied as a photomask substrate in Flat-Panel Display (FPD) manufacturing. The emitted light was observed with a digital camera. Compared to a round shape of quartz glass substrate, a large amount of fluorescent agent supplied was taken away by the straight edges of the quadrilateral geometry of the substrate and moved to the outer edge of a polishing pad placed on a platen. The fluorescent agent that was taken away by the quadrilateral geometry also remained as several uneven spiral patterns on the polishing pad when the revolution speeds both of the quadrilateral substrate and the platen, which are practically set at same or almost revolution speed, were not sufficient. Next, when the quadrilateral substrate rotated at high revolution speed (60 min-1), the fluorescent agent flowed most evenly and spread throughout the entire substrate area in the shortest time. Finally, a combination of thermocouples and a wireless signal transmission system is introduced to investigate the temperature in glass substrate CMP process.