Fundamental study on electrical discharge machining of single crystalline silicon

Single crystalline silicon is one of the most important materials in semiconductor industry because of its superior properties as semiconductor. However, single crystalline silicon is difficult to machine precisely by conventional method because of its fragility. More complex, minute and three-dimensional shape will be required in the near future. From these points of view, electrical discharge machining (EDM) might be used for machining of single crystalline silicon because of very small machining force. In this study, the possibility of EDM for single crystalline silicon is experimentally investigated. The experimental results pointed it out that EDM for single crystalline silicon could be carried out when its resistivity was less than 10^-2Ω · cm. The removal volume of crater of silicon in a single pulse discharge was much larger than that of steel because of its low boiling point and the important role of Joule's heat generation in material removal. Therefore, the removal rate of single crystalline silicon was much higher than that of SK3. Furthermore, the electrode wear in EDM of single crystalline silicon was lower than that of SK3 and no electrode wear EDM was possible under the appropriate condition with kerosine type fluid.