Development of New Diamond Slurry, Diamond Disk and Catalyst Etching Mechanical Polishing Method for Polishing Single-Crystal Silicon Carbide

單晶碳化矽之拋光液、鑽石碟及催化蝕刻拋光製程之研究

蔡明義(Ming-Yi Tsai) ； 蔡哲誠(Che-Cheng Tsai)

《中國機械工程學刊》 36卷6期 (2015/12) Pp. 499-509

摘要

由於單晶碳化矽(SiC)擁有優良熱傳導性、導電性、高飽和電子漂移速度、高擊穿電場強度、化學穩定性及能隙寬度，使得它有機會成為下一代高溫和高功率半導體元件、發光元件、軍用收發模組及電動車、LED燈等高價值的產品材料。然而由於SiC的硬度、脆性和化學惰性，致使它成為一個難以加工的材料且存有移除率偏低的趨勢。一般而言，研磨拋光製程仍然是SiC加工中不可或缺的關鍵技術。如何提升材料移除率且獲得超平滑及近無損傷的表面已成為其應用所必須解決的重要課題。由於研磨拋光機之設備昂貴，因此本研究自行開發SiC之複合式研磨拋光機，具有同步拋光及修整功能及線上量測工件移除率與拋光墊修整率。另外建立一套完整單晶碳化矽拋光製程以及探討不同鑽石顆粒數的新型組合式鑽石碟與傳統硬焊鑽石碟對於修整拋光特性之實驗；在拋光製程之實驗流程分成兩部分機械拋光(MP)以及提出一種催化蝕刻機械拋光(CEMP)。在機械拋光方面：本研究自行設計及製作鑽石拋光液並且與商用鑽石拋光液作比較，實驗結果發現自製鑽石拋光液之移除率高於商用鑽石拋光液4-5倍，具有商品化的潛力。在催化蝕刻機械拋光方面：本研究自製拋光液(鐵+過氧化氫+鹽酸+奈米鑽石)搭配自製含有微米鐵粒子鸚鵡螺形拋光墊，其表面粗糙度Ra值為1.37Å，非常接近產業之標準1 Å，此製程將有助於提升碳化矽拋光製程效能及減少成本及時間。另外自製新型鑽石碟之拋光墊的修整率比硬焊鑽石碟拋光墊修整率提升約2.8倍。

並列摘要

In this study, a novel diamond slurry for mechanical polishing is developed, in which the diamond is heated at different temperatures in a furnace to allow for diamond oxidation to occur; this results in improved diamond surface roughness and sharpness. In addition, a novel catalyst etching mechanical polishing (CEMP) technique is presented, which combines chemical, loose, and fixed polishing methods to improve the polishing process. The surface characteristics, surface damage, and removal rate of silicon carbide (SiC) samples polished with the developed slurry and CEMP are examined and compared with the corresponding attributes yielded by both a conventional diamond slurry and conventional chemical mechanical polishing (CMP). A novel Fe-impregnated polishing pad with a nautilus groove pattern is also developed and used in this study. In addition, we evaluate diamond disks manufactured using polymer-bonded diamond grits, known as polyepoxide combined organic diamond disks (PCDDs). Three kinds of diamond disks are fabricated, containing 600, 1200, and 3000 diamond grits with regular grit distributions, and their performances are compared with that of a traditional 25000-grit diamond disk. The experimental results reveal that the new diamond slurry can yield 4  5 times the material removal rate compared with commercial diamond slurry. Consequently, a mechanical polishing time reduction of more than half is expected. Further, the experimental results also show that the SiC removal rate for CEMP combined with the Fe-impregnated polishing pad is approximately three times higher than that provided by traditional CMP. The surface roughness obtained via CEMP is approximately 1.37 Å, which is close to the standard commercial value (1 Å). It is found that the PCDD dressing rate is approximately three times that of the traditional diamond disk, whereas the PCDD manufacturing cost is approximately 300% lower. When the proposed process is applied to single-crystal SiC polishing, both the polishing time and the cost are reduced. Therefore, this novel design can facilitate extensive use of well-polished single-crystal SiC wafers in the future.

並列關鍵字

chemical mechanical polishing ； single-crystal silicon carbide ； polishing pad ； diamond disk