超音波輔助應用於藍寶石研磨之研究

Application of the Ultrasonic Vibration in Lapping of Sapphire

張淑玲(Shu-Ling Chang)

指導教授 ： 廖運炫

國立臺灣大學/工學院/機械工程學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.01793

摘要

LED產品發展至今已廣泛應用於日常生活當中，藍寶石基板因與氮化鎵之晶格匹配性佳而做為LED磊晶承載板的主要材料，但因藍寶石的材料機械性質優異，使得基板平坦化製程效率低落、時間冗長。藍寶石長晶、修整成晶棒後，尚需經過切割、整平、拋光三個階段，整平階段除了快速取得藍寶石基板雙面平整度、降低表面粗糙度外，也要將切割階段造成的表面損傷去除。產業界現行作法採用大粒徑碳化硼游離磨料進行雙面研磨加工，再以小粒徑鑽石游離磨料進行單面研磨加工。雙面研磨階段採用大粒徑磨料雖能快速達到整平基板之目的，但也可能會在基板表面造成新的損傷，而此損傷也必須於單面研磨製程中移除。
為了改善上述現象，本研究改用鑽石磨料並降低磨料粒徑，減少硬磨料於藍寶石表面造成之損傷程度，再加入SiO2軟磨料並選用304不鏽鋼為研磨工具，利用機械化學研磨機制提高研磨效率，在前述鑽石以及SiO2軟磨料組成的混合磨料之基礎上，加入自行設計的超音波振動輔助研磨裝置搭配混合磨料進行實驗，探討利用混合磨料搭配超音波振動輔助提升研磨效率以及改善表面粗糙度之效果。實驗分為單一鑽石磨料、混合磨料、全程超音波振動輔助混合磨料等磨料系統，並依實驗結果提出階段式超音波振動輔助混合磨料研磨系統，研究不同磨料系統對材料移除深度以及表面粗糙度之影響。實驗結果顯示混合磨料系統雖能維持材料移除率不隨時間下降，但表面粗糙度較單一鑽石磨料系統差；全程超音波振動輔助混合磨料系統雖然能得到良好的研磨表面，但其材料移除率過低；階段式超音波振動輔助混合磨料系統則能得到最大的材料移除率以及最佳的表面粗糙度，其較單一鑽石磨料系統能提升75%之研磨效率及明顯改善表面粗糙度。

關鍵字

超音波 ； 混合磨料 ； 研磨 ； 藍寶石

並列摘要

LED products have been used widely in daily life. Sapphire is the main material of substrate of LED because of its well lattice matching with GaN. However, the planarization process of sapphire wafer takes lots of time due to its excellent mechanical and chemical properties. In the planarization process of sapphire, double-side lapping not only gets the flatness of sapphire substrate, reducing the surface roughness, but also remove the surface damage causing by slicing. In industrial process, although sapphire wafer can be flattened quickly by using large grain size Boron Carbide as the abrasive of double-side lapping, it might cause severe damage that need more time to remove in next processing.
To solve the problem, this study uses smaller diamond abrasive to reduce the damage caused by the hard abrasive on the surface of sapphire. This study also adds silicon dioxide as soft abrasive and uses 304 stainless steel as lapping tool to get better lapping efficiency by the mechanism of mechano-chemical lapping. Based on aforementioned abrasive mixed by diamond and silicon dioxide, this study applies a self-designed ultrasonic vibration assistant device to the lapping machine. This study also discusses the lapping efficiency and the surface roughness lapping with single diamond abrasive, mixed abrasive, and self-designed ultrasonic vibration assistant mixed abrasive. The result of study shows that although the mixed abrasive system can maintain the material removal rate during experiment, the performance on surface roughness is worse than single diamond system. Full-time ultrasonic vibration assistant mixed abrasive system can get better surface roughness after lapping, but the material removal rate is poor. Multiple steps ultrasonic vibration assistant mixed abrasive system can get the best material removal rate and surface roughness, and the material removal rate increases 75% compared with single diamond abrasive system.

並列關鍵字

ultrasonic ； mixed abrasive ； sapphire

參考文獻

[22] 黃昭維，超音波輔助應用於碳化矽的機械化學拋光，國立臺灣大學機械工程學研究所，碩士論文，2009。

[1] 邱晶晶，LED廠商之競爭策略分析:以Cree公司為例，國立政治大學科技管理研究所碩士論文，碩士論文，2007。

[21] W. P. Yang, J. W. Xu, and Y. B. Wu, "Experimental investigation of silicon wafer hybrid polishing by UEV-CMP," Journal of Sourtheast University (Natural Science Edition), vol. 38, pp. 912-917, 2008.

[5] S. Malkin and C. Guo, Grinding Technology: Theory and Application of Machining with Abrasives. New York: Industrial Press Inc., 2008.

[6] W. I. Clark, A. J. Shih, R. L. Lemaster, and S. B. McSpadden, "Fixed abrasive diamond wire machining—part II: experiment design and results," International Journal of Machine Tools and Manufacture, vol. 43, pp. 533-542, 2003.