Development of Multi-wire Edm Slicing Method for Silicon Ingot

INSTRUCTIONS The diameter of silicon wafer becomes larger in order to increase the number of chips per one wafer. For such a larger diameter silicon ingot is mainly sliced by using multi-wire method, in which a long thin wire is used with slurry. In this method, several hundreds of wafers could be sliced at the same time. However there are still problems remained, such as large cracks, slurry treatment, contamination and so on. Therefore, we proposed a new slicing method of monocrystalline silicon ingot using wire electrical discharge machining (wire-EDM), and showed the possibility of wire EDM slicing for monocrystalline silicon ingot [1]. However, the efficiency of wafer slicing by the commerciallyavailable wire-EDM compared to multi-wire saw method is very low, because the number of sliced wafer was only one per one process in the conventional wire-EDM method. Therefore, a multi-wire EDM slicing equipment was newly developed with a single wire and a multi-EDM power supply unit in order to increase the efficiency of wafer slicing [2-4]. In this report, machining characteristics for mono-crystalline silicon ingot using this newly developed multiwire EDM slicing equipment was discussed. Besides, the possibility of applying this technique to silicon ingot for solar cell was also investigated.