機械化學磨削加工單晶碳化矽之研究

單晶碳化矽晶圓(Silicon Carbide,SiC)擁有寬能隙、高崩潰電壓及高熱傳導率之材料特性，且具有極高的硬度與抗化學之材料性質，隨著近年市場對於高功率元件之需求大幅提升，對能經濟有效量產高精度SiC晶圓的期望也日益殷切。但因SiC為超硬材料，必須克服加工後表面殘留之表面與次表面破壞，加工難度高，所花費之時間冗長導致成本增加。故本研究使用機械化學磨削(MCG)對其進行平面磨削，以添加氧化鈰、氧化石墨烯與不同粒徑鑽石之自製砂輪用不同加工參數分別對4H-單晶碳化矽之矽面與碳面進行加工，並探討其對材料移除率、磨削比、表面微結構及粗糙度(Ra)之影響。研究結果顯示在一般精密平磨機床上使用鑽石粒徑3-6μm以及0-1μm砂輪便可將4H單晶碳化矽的矽面加工到2nm和1nm之Ra；而碳面最則為3nm和2nm之Ra。

關鍵字

4H單晶碳化矽；機械化學磨削；表面粗糙度；氧化石墨烯

並列摘要

Single crystal silicon carbide (SiC) has the material characteristics of wide energy gap, high breakdown voltage, high thermal conductivity, high hardness and good chemical resistance. As the market demands for high power devices continuously picking up, the expectation for cost-effective way of mass production precision SiC wafers is also growing sharply. However, SiC is normally categorized as difficult to machine material for its extreme hardness and brittleness. Scattered surface micro-cracks/micro-chipping together with deep-penetrated sub-surface cracks are often the consequence if the machining process of SiC is not properly handled. As a result, the precision machining of SiC is typically lengthy and costly. A mechanical chemical grinding (MCG) process was used in this study to suppress the mechanical damage might be introduced during grinding operation. Grinding wheels with various additives such as cerium oxide, graphene oxide and diamond powder of different grit sizes were designed and produced to grind 4H-SiC under different machining conditions. The machined surface was examined by optical microscope, scanning electron microscope and confocal microscope and the obtained surface microstructure and surface roughness (Ra) were correlated to the wheel composition, machining parameters, material removal rate and grinding ratio. The results show that surface roughness (Ra) of 1 nm on Si-face and 2 nm on C-face of 4H-SiC can be achieved using the MCG wheel developed in this research on a typical precision surface grinding machine.

並列關鍵字

4H-Single Crystal Silicon Carbide ； Mechanical Chemical Grinding ； Surface- Roughness ； Graphene Oxide

參考文獻

【1】 L.S. Ramsdell, "Studies on Silicon Carbide" ,America.Mineralogist,. Vol.32, p.64-82, 1945

Google Scholar

【2】 F.W. Huo, D.M. Guo, R.K. Kang, G. Feng, “Nanogrinding of SiCwafers with high flatness and low subsurface damage” ,Trans.Nonferrous Met. Soc. China, Vol.22, pp.3027−3033, 2012.