Novel strategy for AlN crystal processing: High - efficiency two step CMP technology

Aluminum nitride (AlN) possesses outstanding physical and chemical properties, rendering it with promising prospects for application in various devices. However, the traditional processing technology cannot reach the atomic surface and the efficiency is low, which limits the performance of AlN-based devices. This work proposes a novel and efficient two step chemical mechanical polishing (CMP) method for AlN single crystals. The first-step CMP is the acid alumina slurry polishing, quickly remove surface damage. In the second step CMP, alkaline silicon oxide polishing is used to remove residual subsurface damage, reduce surface roughness, and achieve high-quality and efficient processing of single crystal AlN. Comparing the two step CMP with traditional mechanical polishing and the composite processing method of CMP, the research results show that the polishing efficiency of the two-step chemical mechanical polishing processing method is about 30 % higher than that of the traditional composite polishing method. Two step AlN compound polishing method was revealed from the perspective of material removal mechanism. Finally, the effects of mechanical polishing (MP) and two step CMP processes on the properties and quality of AlN substrates were studied. The proposed two step CMP method could rapidly transform the ground AlN wafer into an atomically smooth surface, which is expected to reduce the cost and manpower required for AlN wafer manufacturing.