Analysis on Effective Lifetime Index of Polishing Pad for CMP Process of Monocrystalline Silicon Wafers and Sapphire

• Main Authors: Chan-Ju Wen, 溫禪儒
• Other Authors: Chao-Chang Chen
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/32497829840515040968

碩士 === 國立臺灣科技大學 === 機械工程系 === 102 === Since ancient times, polishing has been a process critical to bronze mirrors, jade and jewelry grinding until modern wafer planarization in semiconductor industry’s. However, mechanical polishing has certain limitation, the chemical mechanical planarization (CMP) is a key technology available to achieve global flatness and local sub-nanometer surface roughness. Polishing pad and slurry are major accessories in CMP process. Currently, the quality of wafer or process time is cred to assess the replacement time of polishing pad. In this study, a confocal laser measuring machine of bearing area ratio (BAR) is used to measure the major work layer of polishing pad and an pad effective lifetime can be obtained by observing the influence of depth of pad groove in wafer planarization process by long time polishing of sapphire and silicon wafers. When the groove depth of pad is down to about 220 μm, the removal rate is less than 50% for both wafers. In this study, the initial groove depth and the remaining groove depth ratio on polishing pad is defined as an index of pad effective lifetime index (PELI). Thus the pad needs to be replaced when the PELI value is down to 0.5. The PELI can be used as a reference index for users to assess the timing of replacing polishing pad.