Multi-wire EDM slicing of semiconductors with group power supplying method

Multi-wire EDM slicing method have been developed to overcome problems of multi-wire saw method, and high-efficient and high-accurate slicing could be expected compared with a single-wire EDM technologies. However, a multi-wire EDM slicing equipment becomes very complex in the case of an individual power supplying method with multiple power units and conductivity piece sets. This traditional method leads to difficulties in the preparation and a heavy load on the maintenance for a multi-wire EDM slicing equipment. Therefore, a group power supplying method was newly proposed to satisfy both processing efficiency and simplification of slicing equipment, since it can supply sufficient energy to multiple processing wire electrodes only using one conductivity piece set with one EDM power unit. When monocrystalline silicon ingot was sliced by using steel wire electrode of 120 μm with the group power supplying method, discharge current per wire ideally changed with number of processing wire electrodes. However, kerf width was approximately constant at almost constant cutting speed regardless of number of processing wire electrodes. In addition, diameter of crater caused by electrical discharge pulse was dependent on the peak discharge current per wire rather than the total peak discharge current. These results indicate that input energies were almost constant at each processing wire electrode, and electrical discharge pulses could be homogeneously distributed to each processing wire electrode without the breakage even by using only one conductivity piece set in the group power supplying method.