고경도 기판 연마공정용 금속-수지 정반에 관한 연구

Abstract

Single crystal sapphire has been widely used in wide range of applications such as LED, optics, electronics, and temperature sensing because of its excellent properties like thermal stability, chemical resistance and high hardness. Lapping and polishing of sapphire are necessary processes to manufacture the high quality wafers. The purpose of sapphire lapping is to remove the damaged surface, provide flatness and thickness control, and offer especially good basis for polishing. High materials removal rate (MRR) and good surface quality are required for the device performance. However, during a sapphire lapping process it is difficult to get a high removal rate and achieve good surface quality due to its extreme hardness. In the single side lapping process, the role of lapping plate is the supporting plate for abrasion between diamond and sapphire substrate. So, the lapping plate is very important part in lapping process, because the performance is mostly decided by the lapping plate. Metal lapping plate with diamond abrasives has been applied traditionally applied to lap and polish the sapphire wafers. A lapping process with metal plate does not satisfy MRR and roughness at the same time. Therefore, two different types of plates were used, first plate for high removal rate but low surface quality and second plate for low removal rate but good surface quality. Additionally, there are several problems with metal plate itself such as high CoO (Cost of Ownership) and low throughput. In this study, the performance of sapphire lapping process using Metal-resin plates in DMP (Diamond Mechanical Polishing) process has evaluated. Material removal rate (MRR) of sapphire increased linearly with the increase in rotation speed, pressure and lapping process time. MRR and roughness of sapphire wafers were correlated to the hardness of lapping plates with different metal compositions. Metal-resin plates could achieve a good surface quality and proper removal rate of sapphire wafer as compared to metal plates. In addition, the sapphire removal mechanism has discussed based on the experimental results.