Thermal load leveling during silicon crystal growth from a melt using anisotropic materials

Patent metadata

Field	Value
Publication number	US-9464364-B2
Application number	US-201113292410-A
Country	US
Kind code	B2
Filing date	Nov 9, 2011
Priority date	Nov 9, 2011
Publication date	Oct 11, 2016
Grant date	Oct 11, 2016

Abstract

An apparatus for growing a silicon crystal substrate comprising a heat source, an anisotropic thermal load leveling component, a crucible, and a cold plate component is disclosed. The anisotropic thermal load leveling component possesses a high thermal conductivity and may be positioned atop the heat source to be operative to even-out temperature and heat flux variations emanating from the heat source. The crucible may be operative to contain molten silicon in which the top surface of the molten silicon may be defined as a growth interface. The crucible may be substantially surrounded by the anisotropic thermal load leveling component. The cold plate component may be positioned above the crucible to be operative with the anisotropic thermal load leveling component and heat source to maintain a uniform heat flux at the growth surface of the molten silicon.

First claim

What is claimed is:

1. An apparatus comprising:
a heat source;
a crucible disposed above the heat source and operative to contain molten silicon in which a top surface of the molten silicon is defined as a growth interface;
an anisotropic thermal load leveling component disposed between the heat source and the crucible operative to even-out temperature and heat flux variations emanating from the heat source;
a baffle structure extending from an interior wall of the crucible, the baffle structure having a top surface configured to be entirely submerged within the molten silicon and having a bottom surface disposed above a floor of the crucible; and
a pump disposed within the crucible and oriented to direct a flow of the molten silicon over and along the top surface of the baffle structure in a first direction and under and along the bottom surface of the baffle structure in a second direction opposite the first direction.

2. The apparatus of claim 1 wherein the anisotropic thermal load leveling component has a first thermal conductivity in a first direction toward said crucible and a second thermal conductivity in a second direction toward said heat source, the first thermal conductivity is greater than the second thermal conductivity.

3. The apparatus of claim 1 wherein the silicon crystal substrate grows in a direction that is vertically downward from the growth interface.

4. The apparatus of claim 1 wherein the crucible is substantially surrounded by the anisotropic thermal load leveling component.

5. The apparatus of claim 1 wherein the anisotropic thermal load leveling component is a passive component comprised of pyrolytic graphite.

6. The apparatus of claim 5 wherein the pyrolytic graphite is approximately 10 mm thick.

7. The apparatus of claim 1 wherein the crucible is comprised of quartz.

8. The apparatus of claim 7 wherein the quartz is approximately 5 mm thick.

9. The apparatus of claim 1 further comprising a table disposed near an end of the crucible configured to support the silicon crystal substrate as it is pulled from the crucible.

Assignees

• Carlson Frederick M
• Helenbrook Brian T
• Varian Semiconductor Equipment Ass Inc

Inventors

• Carlson Frederick M
• Helenbrook Brian T

Classifications

• C30B15/206

  the thermal history of growing the ingot · CPC title

• C30B29/06 Primary

  Silicon · CPC title

• C30B15/06 Primary

  Non-vertical pulling · CPC title

• C30B15/305

  Stirring of the melt · CPC title

• C30B15/30

  Mechanisms for rotating or moving either the melt or the crystal (flotation methods C30B15/28) · CPC title