Silicon ingot, silicon block, silicon substrate, method for manufacturing silicon ingot, and solar cell

A silicon block including a first surface, a second surface positioned on an opposite side of the first surface, and a third surface positioned along a first direction in a state of connecting the first surface and the second surface, the silicon block comprising:

• a first pseudo single crystal region;
• a first intermediate region containing one or more pseudo single crystal regions;
• and
• a second pseudo single crystal region, wherein
• the first pseudo single crystal region, the first intermediate region, and the second pseudo single crystal region are positioned adjacent sequentially in a second direction perpendicular to the first direction,
• in the second direction, each of a first width of the first pseudo single crystal region and a second width of the second pseudo single crystal region is larger than a third width of the first intermediate region,
• each of a boundary between the first third pseudo single crystal region and the first intermediate region and a boundary between the second pseudo single crystal region and the first intermediate region includes a coincidence boundary, and
• a crystal orientation along the first direction in each of the first pseudo single crystal region, the second pseudo single crystal region, and the one or more pseudo single crystal regions is a <100> orientation in a Miller index.

A silicon substrate with a flat plate shape including a first surface, a second surface positioned on a back side of the first surface in a first direction, and an outer peripheral surface positioned in a state of connecting the first surface and the second surface, the silicon substrate comprising:

• a first pseudo single crystal region;
• a first intermediate region containing one or more pseudo single crystal regions;
• and
• a second pseudo single crystal region, wherein
• the first pseudo single crystal region, the first intermediate region, and the second pseudo single crystal region are positioned adjacent sequentially in a second direction perpendicular to the first direction,
• in the second direction, each of a first width of the first pseudo single crystal region and a second width of the second pseudo single crystal region is larger than a third width of the first intermediate region,
• each of a boundary between the first pseudo single crystal region and the first intermediate region and a boundary between the second pseudo single crystal region and the first intermediate region includes a coincidence boundary, and
• a crystal orientation along the first direction in each of the first pseudo single crystal region, the second pseudo single crystal region, and the one or more pseudo single crystal regions is a <100> orientation in a Miller index.

A method for manufacturing a silicon ingot, the method comprising:

• a first step of preparing a mold having an opening that opens in a first direction;
• a second step of arranging a first seed crystal portion of single crystal silicon, an intermediate seed crystal portion including one or more pieces of single crystal silicon and having a width in a second direction perpendicular to the first direction smaller than that of the first seed crystal portion, and a second seed crystal portion of single crystal silicon having a width in the second direction larger than that of the intermediate seed crystal portion so that the first seed crystal portion, the intermediate seed crystal portion, and the second seed crystal portion are adjacent sequentially in the second direction on a bottom surface portion in the mold;
• a third step of pouring silicon melt into the mold in a state where a temperature of the first seed crystal portion, the intermediate seed crystal portion, and the second seed crystal portion are raised to near a melting point of silicon;
• and
• a fourth step of causing the silicon melt to perform unidirectional solidification upward from the bottom surface portion side of the mold,
• wherein the second step includes arranging the first seed crystal portion, the intermediate seed crystal portion, and the second seed crystal portion so that each of a first rotation angle relationship about a virtual axis along the first direction of single crystal silicon between the first seed crystal portion and the intermediate seed crystal portion and a second rotation angle relationship about a virtual axis along the first direction of single crystal silicon between the second seed crystal portion and the intermediate seed crystal portion is a rotation angle relationship of single crystal silicon corresponding to a coincidence boundary, and
• the second step includes arranging the first seed crystal portion, the intermediate seed crystal portion, and the second seed crystal portion so that an upper surface of a silicon crystal having a plane orientation in a Miller index of (100) is positioned in a state of facing the first direction.