Formation of subsurface cracks in silicon wafers by grinding

Abstract

Single-crystal silicon is an important material in the semiconductor and optical industries. However, being hard and brittle, a silicon wafer is vulnerable to subsurface cracks (SSCs) during grinding, which is detrimental to the performance and lifetime of a wafer product. Therefore, studying the formation of SSCs is important for optimizing SSC-removal processes and thus improving surface integrity. In this study, a statistical method is used to study the formation of SSCs induced during grinding of silicon wafers. The statistical results show that grinding-induced SSCs are not stochastic but anisotropic in their distributions. Generally, when grinding with coarse abrasive grains, SSCs form along the cleavage planes, primarily the {111} planes. However, when grinding with finer abrasive grains, SSCs tend to form along planes with a fracture-surface energy higher than that of the cleavage planes. These findings provide a guidance for the accurate detection of SSCs in ground silicon wafers.