Heat-assisted μ-electrical discharge machining of silicon

Abstract

Micro-electrical discharge machining (µEDM) is an unconventional machining method that is suitable for machining of conductive materials including highly doped silicon (Si) wafers. This paper reports a novel method of heat-assisted µEDM machining of Si wafers by varying the temperature to increase the electrical conductivity of Si. In order to achieve this condition, a ceramic heater is used to heat the Si wafers within the temperature range of 30–250 °C. In this study, the machining performances in terms of the material removal rate, tool wear rate, surface quality, and materials characterization have been investigated accordingly. The machining performance of p-type (1–10 O cm) Si wafers was investigated to machine a cavity based on different temperatures with a constant discharge energy of 50 µJ and a feed rate of 50 µm/min. The results indicated that increasing the machining temperature allowed achieving a higher material removal rate, lower tool wear rate, and lower surface roughness. The highest material removal rate of 1.43 × 10-5 mm3/s and a surface roughness of 1.487 µm were achieved at 250 °C. In addition, the material removal rate increased by a factor of ~16 times compared to the results obtained at the lowest temperature, 30 °C, and the Raman spectroscopy analysis revealed that no significant changes occurred in the Si structure before and after machining.