蓝宝石晶片加工中的技术关键和对策

Key Technology and Strategies in Sapphire Wafer Processing

传统的粗磨工艺在加工蓝宝石薄片过程中遇到很大挑战,易于产生崩边、隐裂和碎片等问题。双面金刚石研磨、单面金刚石磨削、双面金刚石研磨垫等新工艺可以解决上述这些问题。在蓝宝石精磨工艺中,细粒碳化硼和金刚石颗粒镶嵌的陶瓷研磨盘配合的双面研磨工艺,可以有效地降低粗磨过程中造成的表面损伤;使用细粒金刚石研磨液的单面铜盘工艺亦是一种有效的精磨工艺。本文对二者的优缺点进行了比较。蓝宝石的抛光速率较慢,一般不超过5-10μm/h。蓝宝石抛光的主流仍是使用二氧化硅抛光液。在二氧化硅抛光液中添加其它细粒磨料或采用氧化铝抛光液等其它方法,仍处于试验阶段。轻压抛光对提高蓝宝石的表面质量非常关键。兆声清洗工艺可以减少蓝宝石表面的微小缺陷,兆声单片清洗工艺尤为有效。

Great challenges have been encountered in traditional primary lapping process of thin sapphire wafers. They are prone to edge chipping,hidden cracks,breakage,etc. New Processes,such as double side lapping with a pair of diamond platens,single side diamond grinding,double side lapping with a pair of diamond pads,can probably solve all the above problems. In secondary lapping of sapphire wafers for removal of surface damages coming from primary lapping,double side lapping with fine B_4C particles plus ceramic platens embedded with diamond particulates is a very effective method. Another option is single side lapping with diamond paste plus resin bronze platen. The detailed comparison of the two processes is listed in this paper. Currently,colloidal silica based slurry is mainly used in sapphire polish,with a slow removal rate of no more than 5-10 μm / h. The other polishing slurries,such as fine particles addition into silica slurry,alumina slurry,etc. are still in the stage of testing. It is emphasized that buffing polish is a very crucial step for controlling sapphire surface quality. Wet cleaning of sapphire wafers with megasonic can be used for reduction of small surface defects. Meg Pie cleaning is a very effective one-wafer method for cleaning sapphire wafers.