The design concept and implementation of ultra-precision thinning grinder for SiC wafers

Abstract

With the rapid development of mobile communications, intelligent driving, aerospace, and other high-tech fields, the performance requirements for power semiconductor devices continue to improve. Silicon carbide (SiC), a third-generation semiconductor, has gradually replaced monocrystalline silicon (Si) due to its superior material properties. Constrained by the high hardness of the SiC, it is hard to guarantee the grinding accuracy and quality of SiC wafers using a traditional grinder with a cantilever structure. Herein, this paper elaborated the design concept of the ultra-precision thinning grinder from two aspects of material characteristics and processing requirements, and developed an ultra-precision thinning grinder for SiC wafers with an embedded gantry structure, and configured an inclination automatic adjustment mechanism, which is capable of quantitatively adjusting the relative tilting angle between the turntable and the grinding wheel spindle to realize the regulation of the total thickness deviation (TTV) of SiC wafers. The simulation and grinding comparison experiments show that the designed grinder has superior dynamic characteristics and machining quality compared to the traditional cantilever structure grinder. The grinder successfully processed 6-inch SiC wafers with a TTV of 2.26 μm and a roughness (Sa) of less than 3.8 nm, verifying that the design concept and structural design can ensure excellent machining performance.