Process and apparatus for producing polycrystalline semiconductor ingot

A silicon semiconductor material (15) is charged in a double-structured crucible of an outer crucible (1) and an inner crucible (2). The crucible is heated from the upper side thereof by the heat radiated from a heating member (8) energized by an induction heating coil (7), so that the silicon raw semiconductor material is melted. The bottom of the crucible (1) is mounted on a supporting bed (4) cooled by cooling water supplied from a cooling medium tank (13). The silicon semiconductor material (15) is melted in the inner crucible (2) and starts solidifying from the bottom portion thereof. The silicon semiconductor material (15) expands in volume at the time of solidification. Since a gap is formed between the inner crucible (2) and the outer crucible (1), however, the outward extension of the inner crucible (1) with the silicon semiconductor material (15) alleviates a strain generated at the time of solidification, thereby producing an excellent polycrystalline semiconductor ingot. As a result, the strain in the polycrystalline semiconductor ingot produced by the unidirectional solidification process is reduced to improve the quality.