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

Patent metadata

Field	Value
Publication number	US-11713515-B2
Application number	US-201917261175-A
Country	US
Kind code	B2
Filing date	Jul 5, 2019
Priority date	Jul 20, 2018
Publication date	Aug 1, 2023
Grant date	Aug 1, 2023

Abstract

An ingot includes a first surface, a second surface opposite to the first surface, and a third surface positioned along a first direction and connecting the first surface and the second surface. The ingot includes: a first pseudo single crystal region; an intermediate region containing one or more pseudo single crystal regions; and a second pseudo single crystal region. The first pseudo single crystal region, the 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, a width of each of the first and second pseudo single crystal regions is larger than a width of the first intermediate region. Each of a boundary between the first pseudo single crystal region and the intermediate region and a boundary between the second pseudo single crystal region and the intermediate region includes a coincidence boundary.

First claim

The invention claimed is:

1. A silicon ingot 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 ingot 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.

2. The silicon ingot according to claim 1 , wherein the coincidence boundary includes a coincidence boundary having a Σ value of 29.

3. The silicon ingot according to claim 1 , wherein the first width and the second width are different.

4. 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.

5. The silicon block according to claim 4 , wherein the coincidence boundary includes a coincidence boundary having a Σ value of 29.

6. The silicon block according to claim 4 , wherein the first width and the second width are different.

7. 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.

8. The silicon substrate according to claim 7 , wherein the coincidence boundary includes a coincidence boundary having a Σ value of 29.

9. 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.

10. The method according to claim 9 , wherein the second step includes arranging the first seed crystal portion, the intermediate seed crystal portion, and the second seed crystal portion so that the first rotation angle relationship and the second rotation angle relationship are a rotation angle relationship of single crystal silicon corresponding to a coincidence boundary with a Σ value of 29 with a virtual axis along a <100> orientation in a Miller index as a rotation axis.

11. The method according to claim 9 , wherein the second step includes making a first width of the first seed crystal portion and a second width of the second seed crystal portion in the second direction different.

12. A solar cell, comprising:
the silicon substrate according to claim 7 ; and
an electrode positioned on the silicon substrate.

Assignees

• Kyocera Corp

Inventors

• Tanabe Hideyoshi
• Matsuo Hitoshi

Classifications

• H10F71/1221

  comprising polycrystalline silicon · CPC title

• C30B29/64

  Flat crystals, e.g. plates, strips or discs · CPC title

• C30B13/34

  characterised by the seed, e.g. by its crystallographic orientation · CPC title

• H10F71/121

  The active layers comprising only Group IV materials · CPC title

• C30B29/06 Primary

  Silicon · CPC title