The elastic impact of polishing pad for sapphire polishing

Sapphire substrate´s application such as LED, cover glass will be expanded year by year. After lapping, polishing is needed to get smooth surface. In recent years, high throughput at polishing became to be required for expansion of demand. Polishing pads were classified to fiber type, urethane and suede one. Fiber type made from polyurethane, polyether fiber has been used and it performed moderate removal rate from contact area caused by fiber. On the other hand, polishing conditions such as down force, shear one became to be heavier recently to increase removal rate. In case of utilizing that environment by designing with dynamic pad´s feature, the pad should reveal higher removal rate. This study sought a new key factor which can achieve high removal rate under the environment. Firstly pad´s elastic feature was focused by using nylon fiber for new design and it was confirmed that there was correlation between the content and removal rate was. Then it was found out that Young´s modulus was the key factor and it seemed to increase contact area at dynamic environment. Finally, urethane type designed on low Young´s modulus was evaluated. As result, it was found out that this approach was efficient both for fiber type and urethane one to achieve high removal rate.