鑽石修整器在化學機械拋光溶液中之腐蝕研究

Corrosion Investigation of Diamond Disk Conditioner in the Slurry of Chemical Mechanical Polishing

鑽石修整器應用於化學機械拋光中拋光墊的修整，已有很長的一段時間。當半導體的線寬逐年下降，相對地，在晶圓表面平整性以及拋光效率的要求更是嚴苛。然而，在化學機械拋光的過程當中，鑽石修整器扮演一個維持拋光墊工作效率的重要角色，在充滿研磨漿的環境下，鑽石修整器必須要有優良的抗腐蝕能力，以確保不因腐蝕而產生表面剝離，進而影響受拋光晶圓的平整性。
由於類鑽薄膜良好的化學鈍性及高硬度特性，因此廣泛用於保護底材的用途。在本文中，我們採用物理氣相沉積法在修整器上沉積一層類鑽薄膜並且與沒有類鑽薄膜的修整器，進行動態極化測試、交流阻抗分析以及掃描式電子顯微鏡觀察腐蝕後的表面型態。結果指出，經過動態極化測試，鍍上類鑽薄膜的鑽石修整器可得到較優良的抗蝕能力；交流阻抗分析中，可得到較大的阻抗值，腐蝕後鍍層表面型態也較完整並無明顯遭受孔蝕與鍍層剝落的跡象。

Diamond disk conditioners have long served the semiconductor chemical mechanical polishing (CMP) process for polish pad dressing. While the diameter of wafers has steadily increased and the lower line gap distance is developing in order to improve its efficiency, a better polish performance is our pursuing target. However, the slurry in polishing processes, which can lead not only to uniform corrosion but also to crevice attack and pitting for pad conditioners. To further improve the performance and quality of diamond disk conditioners, the corrosion resistance is the first consideration of dressing in the CMP corrosive slurry.
Diamond like carbon (DLC) for protecting applications were of great interest to researchers in recent years because of their excellent properties such as dielectric insulation, low friction, high wear resistance, high hardness and corrosion resistance. Improving the corrosion resistance and keeping the diamond powder working well become very challengeing when pad conditioners are immersed in a corrosive environment. In this study, DLC were deposited on the mixed surface layer of diamond powder and Ni/Cr alloy for a protective layer by physical vapor deposition. This study investigated the corrosion behavior of DLC protective layers in the slurry by electrochemical techniques, including the potentio-dynamic polarization test and electrochemical impedance spectroscopy (EIS). SEM was used to analyze the surface morphology of the conditioner after corrosion.