A New Slicing Method of Monocrystalline Silicon Ingot by Wire EDM

Abstract

Monocrystalline silicon is one of the most important materials in the semiconductor industry because of its many excellent properties as a semiconductor. In the manufacturing process of silicon wafers, inner diameter (ID) blade and multi wire saw have conventionally been used for slicing silicon ingots. However, some problems in efficiency, accuracy, slurry treatment and contamination are experienced when applying this method to largescale wafers of 12 or 16 inch diameter expected to be used in the near future. Thus, the improvement of conventional methods or a new slicing method is strongly required. In this study, the possibility of slicing a silicon ingot by wire EDM was discussed and the machining properties were experimentally investigated. A silicon wafer used as substratum for epitaxial film growth has low resistivity in the order of 0.01Ω·cm, which makes it possible to cut silicon ingots by wire EDM. It was clarified that the new wire EDM has potential for application as a new slicing method, and that the surface roughness using this method is as small as that using the conventional multi wire saw method. Moreover, it was pointed out that the contamination due to the adhesion and diffusion of wire electrode material into the machined surface can be reduced by wire EDM under the condition of low current and long discharge duration.