Novel insights into hole characteristics and fracture toughness in polycrystalline diamond micro-drilling of single-crystal silicon

Abstract

The high purity and perfect crystalline structure of single-crystal silicon makes it a critical material for semiconductors, photovoltaics, micro-electro-mechanical systems, and optical devices. In particular, the electrodes used in semiconductor etching, a key process in semiconductor manufacturing, require the drilling of thousands of micro-holes. However, single-crystal silicon is extremely hard and brittle, making it susceptible to surface defects such as cracking, chipping, and fracture during drilling. This study investigated the drilling characteristics of single-crystal silicon using polycrystalline diamond micro-drills. With the exception of a few cases, no significant trends were observed, providing a theoretical basis for predicting cutting force, entrance hole chipping, diameter error, and surface roughness under various drilling conditions. However, all results were found to be directly related to the drilling distance. Diameter error and cutting force exhibited similar patterns with respect to drilling distance, and chipping was identified as a discernible trend when expressed as a function of cutting force and drilling distance. Thus, taken together, our results suggest that considering drilling distance allows for better predictability of the drilling outcomes of single-crystal silicon, contributing to improved manufacturing efficiency and product quality by addressing chipping and other defects.