Chemical mechanical planarization studies on gallium nitride for improved performance

In this study, a systematic experimental approach has been followed to determine the conditions to promote material removal rate while controlling surface defectivity for GaN CMP. Silica based slurries were used to optimize the CMP conditions for a commercial GaN sample as a function of pH, and type of polishing pad and conditioning. In addition, CMP responses of Face A and Face B type crystallographic GaN surfaces were evaluated and compared to the 2" GaN wafer with unknown surface crystallographic structure. It is observed that the contact angle responses of the different crystallographic surfaces can help identify the type of GaN surface and support predicting the CMP performance simultaneously.