蓝宝石衬底倒角长度均匀性研究

A Study on the Edge Chamfer Length Uniformity of Sapphire Substrate

本文通过对蓝宝石衬底倒角工艺的分析,探讨衬底边缘倒角长度均匀性的影响因素及其影响规律。测量衬底边缘5个位置点的倒角长度,计算倒角长度的均匀性(CU%)。通过开展倒角试验,分析了磨削速度、砂轮表面磨粒状态以及衬底面形精度对倒角长度均匀性的影响。试验结果表明:随着磨削速度的提高,倒角长度均匀性有所提高,但速度继续增大时,倒角长度均匀性会变差。随着倒角片数的增加,砂轮表面磨粒状态趋于稳定,倒角长度均匀性变好。但随着砂轮磨损到一定程度时,CU%的标准差逐步变大。衬底的TTV和Warp值对倒角长度均匀性也有着较为重要影响,TTV和Warp越小的衬底,倒角长度均匀性越好。最后分析了倒角长度对衬底后续光阻涂布良率的影响,发现倒角长度在80 μm以上,可获得较高的良率。

This study demonstrates the effect on edge chamfer uniformity by changing the chamfer grinding processing conditions of the sapphire substrate. We measured the champer lengths at the 5 points and calculated the chamfer length uniformity (CU%). The effects of diamond wheel grinding speed, abrasive grain state and substrate topography on the chamfer length uniformity were analyzed. The results show that a better CU% can be obtained as we increased the rotation speed of the grinding wheel. However, it can be found that the variation range of CU% becomes larger gradually as we increased the wheel speed and then tends to be stable. According to the analysis of substrate flatness and CU%, it can be found that the TTV and Warp values are important for CU% which means better flatness can get better CU%. In order to obtain better photoresist coating yield rates, it is recommended that the suitable chamfer length should be above 80 μm.