自遠古時期的銅鏡、玉石、珠寶的研磨拋光到目前次奈米等級的半導體晶圓鏡面拋光，機械式拋光有其一定程度之極限，因此化學機械平坦化(Chemical Mechanical Planarization)是目前可同時進行大面積平坦化且兼顧次奈米表面粗糙度的重要關鍵性技術。其中拋光墊(Polishing Pad)與拋光液(Slurry)在化學機械平坦化製程中佔了重要的地位，但目前僅能從平坦化後的晶圓品質或是製程時間來評估拋光墊的更換時機，因此本研究利用雷射共焦儀(Confocal Laser)以承壓比(Bearing Area Ratio)分析拋光墊承壓區，並定義為有效使用壽命，以長時間的拋光製程觀察SUBA800之溝槽深度對於藍寶石(Sapphire)及矽(Silicon)晶圓在平坦化製程中的影響。實驗結果發現到溝槽深度降至約220 μm時拋光墊對於晶圓的材料移除率僅剩不到50%。本實驗定義拋光墊初始溝槽深度與剩餘之溝槽深度比值為PELI(Pad Effective Lifetime Index)，降至0.5後即需更換拋光墊，可作為使用者評估更換時機之有效參考指標。

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.

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