Evaluation of Machined Surface Texture for Single-crystal Si Wafer by Four-point Bending Tests

Abstract

　　　Chemical mechanical polishing (CMP) is one of the effective surface-finishing methods for machining Si wafers. However, the conventional CMP process using free abrasive slurry has apparent disadvantages, such as low efficiency, high environmental burden and cost. As a promising technology for the machining of large-sized Si wafer, chemo-mechanical grinding (CMG) integrates the advantages of fixed abrasive machining and CMP process, and hence can generate superior surface quality comparable to that by CMP while maintaining the high geometric accuracy. In this laboratory, we proposed the ultrasonic assisted chemo-mechanical grinding (UA-CMG) process using fixed abrasive to enhance the material removal rate, attain the work-surface with little damage or defects. Although UA-CMG is effective for the improvement of surface roughness and surface morphologies, machined surface characteristics need to be further investigated. In this paper, the evaluation of machined surface texture (Particularly, tool mark and machining defects) using material testing technique is reported. Four-point bending tests of the single-crystal Si wafer processed using UA-CMG are conducted and the influence of surface texture on mechanical properties has been evaluated.