200mm超薄硅片边缘抛光技术

Edge Polishing Technology for 200 mm Ultra-Thin Silicon Wafer

在大尺寸硅片外延加工过程中,边缘损伤极易导致外延层位错的产生。厚度为450μm的超薄硅片因其机械强度较低,在边缘抛光过程中极易导致碎片产生。为此采用化学机械抛光(CMP)对8英寸(1英寸=2.54 cm)超薄硅片进行边缘抛光,通过优化工艺参数改善硅片边缘粗糙度及过抛量,并讨论了边缘抛光前后硅片倒角角度及边缘残余应力的变化。结果表明边缘抛光工序对硅片边缘去除量较小,且仅对边缘损伤层起到去除作用,因此可以有效降低硅片边缘残余应力,而对倒角角度影响较小,有助于获得边缘质量较好的硅片,为后续外延加工打下良好基础。

During the epitaxial processing of large-size silicon wafers,the edge damage can easily lead to the generation of epitaxial layer dislocations.The ultra-thin silicon wafer with a thickness of 450μm is very easy to cause debris during the edge polishing process due to its low mechanical strength.Therefore,the edge polishing of 8 inch(1 inch=2.54 cm)ultra-thin silicon wafers was carried out by chemical mechanical polishing(CMP),and the edge roughness and over-polishing amount of silicon wafers were reduced by optimizing process parameters.The changes of the chamfering angle and edge residual stress of silicon wafers before and after edge polishing were discussed.The results show that the edge polishing process has a smaller removal amount on the edge of the silicon wafer,and only removes the edge damage layer.It can effectively reduce the residual stress on the edge of silicon wafers,and has little effect on the chamfering angle,which can help to obtain silicon wafers with better edge quality and lay a good foundation for subsequent epitaxial processing.