Method for achieving sustained anisotropic crystal growth on the surface of a silicon melt

Patent metadata

Field	Value
Publication number	US-9970125-B2
Application number	US-201213398884-A
Country	US
Kind code	B2
Filing date	Feb 17, 2012
Priority date	Feb 17, 2012
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

An apparatus for growing a crystalline sheet from a melt includes a cold block assembly. The cold block assembly may include a cold block and a shield surrounding the cold block and being at an elevated temperature with respect to that of the cold block, the shield defining an opening disposed along a surface of the cold block proximate a melt surface that defines a cold area comprising a width along a first direction of the cold block, the cold area operable to provide localized cooling of a region of the melt surface proximate the cold block. The apparatus may further include a crystal puller arranged to draw a crystalline seed in a direction perpendicular to the first direction when the cold block assembly is disposed proximate the melt surface.

First claim

What is claimed is:

1. An apparatus for growing a crystalline sheet from a melt, comprising:
a first cold block assembly comprising:
a first cold block;
a holder coupled to the first cold block and operable to control a distance between the first cold block and a melt surface during operation;
an insulator surrounding a portion of the first cold block;
a first shield surrounding a portion of the insulator and the first cold block and being at an elevated temperature with respect to that of the first cold block, the first shield partially disposed on a first surface of the first cold block assembly proximate the melt surface and defining an opening disposed along the first surface such that a portion of the first cold block is exposed to the melt surface to define a first cold area having a first width in a first direction, the first cold area operable to provide localized cooling of a first region of the melt surface proximate the first cold block;
a crystal puller arranged to draw a crystalline seed in a second direction perpendicular to the first direction; and
a second cold block assembly comprising:
a second cold block spaced apart from the first cold block in the second direction;
a second holder coupled to the second cold block and operable to control a distance between the second cold block and the melt surface during operation; and
a second shield surrounding the second cold block and being at a second elevated temperature with respect to the second cold block, the second shield defining a second opening disposed along a second surface of the second cold block proximate a second region of the melt surface and defining a second cold area having a width that increases in the first direction from the first width to a second width, wherein a vertical distance between the melt surface and the second surface varies in the first direction to position outer regions of the second surface along the first direction at a greater vertical distance from the melt surface than inner regions of the second surface.

2. The apparatus of claim 1 , the first shield comprising a set of compensation heating elements arranged to provide, in regions surrounding the first cold block outside of the first cold area, a surface temperature of the first cold block assembly within ten degrees Celsius of a temperature of the melt surface.

3. The apparatus of claim 2 , the compensation heating elements operable to provide the surface temperature of the first cold block assembly of about 1412° C.

4. The apparatus of claim 1 , the first cold block defining a passage inside the first cold block that is connected to a cooling fluid source.

5. The apparatus of claim 1 , further comprising:
at least one light pipe disposed in the first cold block proximate the first cold area, the light pipe configured to conduct light to a pyrometer that generates a signal; and
a controller operable to receive the signal from the pyrometer and generate control signals to initiate a pulling of the crystalline seed along the melt surface when a radiation level proximate the melt reaches a predetermined threshold.

6. The apparatus of claim 1 , the second surface defining a recess in an innermost region of the second surface, the recess having a width about equal to the first width.

7. The apparatus of claim 1 , the second cold block assembly comprising two or more heating elements disposed along the second surface, the second cold block assembly operable to decrease power to at least one of the two or more heating elements so as to decrease the width of the second cold area from the second width to a third width in the first direction.

8. The apparatus of claim 7 , further comprising:
a third cold block assembly, the third cold block assembly comprising:
a third cold block; and
a third shield surrounding the third cold block, the third shield being at a third elevated temperature with respect to the third cold block, the third shield comprising a third opening disposed along a third surface of the third cold block proximate a third region of the melt surface and defining a third cold area, the third cold area having a fourth width about equal to the third width, and the third surface comprising a flat shape so as to provide uniform heat flux removal.

Assignees

• Mackintosh Brian H
• Kellerman Peter L
• Sun Dawei
• Varian Semiconductor Equipment Ass Inc

Inventors

• Mackintosh Brian H
• Kellerman Peter L
• Sun Dawei

Classifications

• Y10T117/1044

  including means forming a flat shape [e.g., ribbon] · CPC title

• Y10T117/1068

  including heating or cooling details [e.g., shield configuration] · CPC title

• C30B15/06

  Non-vertical pulling · CPC title

• C30B15/14 Primary

  Heating of the melt or the crystallised materials · CPC title

• C30B29/06

  Silicon · CPC title