# US 2013/0252011 A1 · Multi-Crystalline Silicon Ingot And Directional Solidification Furnace

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- Number: US 2013/0252011 A1
- Document ID: US20130252011A1
- Status: Published application
- Kind: A1
- Application number: 13/613,768
- Filed: 2012-09-13
- Published: 2013-09-26
- Earliest claimed: 2011-09-14
- Assignees: Memc Singapore, Pte. Ltd (Uen200614797D)
- Inventors: Aditya Deshpande; Lee William Ferry; Benjamin Michael Meyer
- Web page: https://patentgrep.com/patent/US20130252011A1

## CPC

- F27B 14/08: Details specially adapted for crucible or pot furnaces
- C01B 33/02: Silicon (forming single crystals or homogeneous polycrystalline material with defined structure C30B)
- C01B 33/037: Purification (by zone-melting C30B13/00)
- C30B 11/003: {Heating or cooling of the melt or the crystallised material}
- C30B 28/06: by normal freezing or freezing under temperature gradient
- C30B 29/06: Silicon
- Y10T 428/12: All metal or with adjacent metals
- F27B: FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

An ingot having a mass of greater than about 1000 kg, a method of producing the ingot, and a directional solidification furnace for producing the ingot are disclosed.

## Claims

### Claim 1

A multi-crystalline silicon ingot having a mass of at least about 1000 kg, the ingot having a dislocation density of less than about 100,000 counts per square centimeter.

### Claim 2 (depends on 1)

The ingot of claim 1 wherein the ingot has a mass of at least about 1600 kg.

### Claim 3 (depends on 1)

The ingot of claim 1 wherein the ingot is produced in a directional solidification furnace.

### Claim 4 (depends on 1)

The ingot of claim 1 wherein the ingot has a length and a width, each of which is sized such that after the ingot is cut into pieces to form smaller bricks, the smaller bricks have a standard size that is substantially similar to ingots formed in known furnaces.

### Claim 5 (depends on 3)

The ingot of claim 3 wherein the length and the width of the ingot are about 1375 mm.

### Claim 6 (depends on 4)

The ingot of claim 4 wherein the ingot has a height of about 400 mm.

### Claim 7 (depends on 4)

The ingot of claim 4 wherein the ingot is cut into 64 smaller bricks with a length and a width of about 156 mm.

### Claim 8 (depends on 4)

The ingot of claim 4 wherein the ingot is cut into 36 smaller bricks with a length and a width of about 210 mm.

### Claim 9 (depends on 1)

The ingot of claim 1 wherein defects or dislocations in the ingot are concentrated in a portion of the ingot.

### Claim 10

A method for producing a multi-crystalline silicon ingot in a directional solidification furnace, the method comprising:
charging a crucible in the furnace with poly-crystalline silicon, the mass of the poly-crystalline silicon being at least about 1000 kg;
melting the poly-crystalline silicon; and
cooling the molten silicon to form a multi-crystalline silicon ingot having a mass of at least about 1000 kg, the ingot having a dislocation density of less than about 100,000 counts per square centimeter.

### Claim 11 (depends on 10)

The method of claim 10 further comprising controlling the rate of solidification of the ingot to form a directional solidification front in the ingot, the solidification front progressing vertically upwards away from a cooling plate positioned beneath a crucible of the directional solidification furnace.

### Claim 12 (depends on 11)

The method of claim 11 wherein the directional solidification front concentrates defects or dislocations in a portion of the ingot that is last to solidify.

### Claim 13 (depends on 10)

The method of claim 10 further comprising opening one or more doors formed in insulation disposed adjacent the crucible to control the rate of solidification of the ingot to form a directional solidification front in the ingot, the solidification front progressing vertically upwards away from a cooling plate positioned beneath a crucible of the directional solidification furnace.

### Claim 14 (depends on 10)

The method of claim 10 further comprising moving one or more insulating members disposed beneath the crucible between a first position where the members are disposed beneath a base of the crucible and a second position where the members are not disposed beneath the base of the crucible.

### Claim 15 (depends on 14)

The method of claim 14 wherein the insulating members are positioned in the first position while the poly-crystalline silicon is melted.

### Claim 16 (depends on 14)

The method of claim 14 wherein the insulating members are positioned in the second position while the molten silicon is cooled to form the multi-crystalline silicon ingot.

### Claim 17 (depends on 14)

The method of claim 14 wherein the insulating members are movable between the first position and the second position in a lateral direction.

### Claim 18

A directional solidification furnace for producing a multi-crystalline silicon ingot having a mass of at least about 1000 kg and a dislocation density of less than about 100,000 counts per square centimeter, the furnace comprising:
a crucible for containing a silicon charge;
insulation disposed adjacent the crucible, the insulation movable between a first position where the insulation restricts the flow of heat away from the crucible and a second position where the insulation does not restrict the flow of heat away from the crucible; and
one or more cooling plates positioned beneath the crucible.

### Claim 19 (depends on 18)

The furnace of claim 18 wherein the insulation comprises one or more doors disposed laterally adjacent vertical walls of the crucible.

### Claim 20 (depends on 19)

The furnace of claim 19 wherein in the first position the doors are substantially closed to prevent heat from flowing away from the crucible and wherein in the second position the doors are open to permit heat to flow away from the crucible.

### Claim 21 (depends on 19)

The furnace of claim 19 wherein the one or more doors are rotatable about an axis that is generally perpendicular to the walls of the crucible.

### Claim 22 (depends on 18)

The furnace of claim 18 wherein the insulation comprises one or more laterally movable members disposed beneath the crucible.

### Claim 23 (depends on 22)

The furnace of claim 22 wherein in the first position the members are positioned beneath a base of the crucible and wherein in the second position the members are not disposed beneath the base of the crucible.

### Claim 24 (depends on 23)

The furnace of claim 23 wherein the members are movable between the first position and the second position in a lateral direction.

### Claim 25 (depends on 23)

The furnace of claim 23 wherein the one or more cooling plates are movable between a first position where the cooling plates are free from contact with a block positioned adjacent a bottom of the crucible and a second position where the plates are in contact with the block.

### Claim 26 (depends on 25)

The furnace of claim 25 wherein when the cooling plates are in the first position the members are in the first position.

### Claim 27 (depends on 25)

The furnace of claim 25 wherein when the cooling plates are in the second position the members are in the second position.

### Claim 28

A directional solidification furnace for producing a multi-crystalline silicon ingot have of at least about 1000 kg and a dislocation density of less than about 100,000 counts per square centimeter, the furnace comprising:
a crucible for containing a silicon charge; and
one or more cooling plates positioned beneath the crucible, the plates movable between a first position where the cooling plates are free from contact with a block positioned adjacent a bottom of the crucible and a second position where the plates are in contact with the block.

### Claim 29 (depends on 28)

The furnace of claim 28 wherein four cooling plates are positioned beneath the crucible.

### Claim 30 (depends on 28)

The furnace of claim 28 wherein the cooling plates are movable between the first position and the second position in a substantially vertical direction.