Integration of GaN thin film and dissimilar substrate material by Au-Sn wafer bonding and CMP

GaN thin film grown on sapphire substrate of 50 mm*50 mm in size are successfully bonded and transferred onto Si substrate using Au-Sn wafer bonding followed by grinding, chemical mechanical polishing (CMP) and dry etching. The GaN/sapphire structures are integrated to receptor Si substrate by thermal pressure bonding process. The bonding medium comprises Au-Sn multilayer composite deposited directly on the object to be bonded. Sapphire substrate is detached from GaN epi-layer by combining mechanical grinding, CMP with dry etching process. The dissimilar Si substrate provides support to the GaN-based LED epitaxial layer during the CMP process, and takes the role of conducting and high heat-dissipating substrate. The CMP can remove or reduce most of the scratches produced by mechanical grinding, recovering both the mechanical strength and wafer warpage to their original status and resulting in a smoother surface. The results have been presented.