Semiconductor single crystal pulling apparatus and method for remelting semiconductor single crystal using this

Patent metadata

Field	Value
Publication number	US-10113247-B2
Application number	US-201515507851-A
Country	US
Kind code	B2
Filing date	Sep 9, 2015
Priority date	Sep 29, 2014
Publication date	Oct 30, 2018
Grant date	Oct 30, 2018

Abstract

A single crystal pulling apparatus including: a remelting detection apparatus which detects that remelting of a lower end portion of the semiconductor single crystal is completed from a change in weight of the semiconductor single crystal when the lower end portion of the semiconductor single crystal is immersed in the melt to be remolten by using the wire; and a lowermost end detection apparatus which detects a lowermost end of the semiconductor single crystal from a position where no current flows between the semiconductor single crystal and the melt when the semiconductor single crystal is taken up with the use of the wire while applying a voltage between the semiconductor single crystal and the melt by applying a voltage between the crucible and the wire.

First claim

The invention claimed is:

1. A method for remelting a semiconductor single crystal which is a method for immersing a lower end portion of the semiconductor single crystal in a melt and remelting the same by using a single crystal pulling apparatus, the single crystal pulling apparatus comprising a heater for performing heating and thermal insulation to a crucible containing a melt and a wire for growing a semiconductor single crystal while pulling the same from the melt,
wherein the semiconductor single crystal pulling apparatus comprises:
a remelting detection apparatus which detects that remelting of a lower end portion of the semiconductor single crystal is completed from a change in weight of the semiconductor single crystal when the lower end portion of the semiconductor single crystal is immersed in the melt so as to be remolten by using the wire; and
a lowermost end detection apparatus which detects a lowermost end of the semiconductor single crystal from a position where no current flows between the semiconductor single crystal and the melt when the semiconductor single crystal is taken up with the use of the wire while applying a voltage between the semiconductor single crystal and the melt by applying a voltage between the crucible and the wire,
the method comprising:
a crystal immersion step of immersing the lower end portion of the semiconductor single crystal in the melt and remelting the lower end portion by lowering the wire of the single crystal pulling apparatus;
a remelting detection step of detecting that melting of the lower end portion of the semiconductor single crystal immersed in the melt is completed from a change in weight of the semiconductor single crystal by using the remelting detection apparatus;
a lowermost end detection step of taking up the semiconductor single crystal with the use of the wire while applying a voltage between the semiconductor single crystal and the melt, and detecting a lowermost end of the semiconductor single crystal from a position where no current flows between the semiconductor single crystal and the melt by using the lowermost end detection apparatus; and
a determination step of determining whether the crystal immersion step is to be restarted or whether the remelting is to be terminated after end of the lowermost end detection step.

2. The method for remelting a semiconductor single crystal according to claim 1 ,
wherein, in the remelting detection step,
when the change in weight of the semiconductor single crystal reaches a predetermined value or less, it is detected that the remelting of the immersed lower end portion of the semiconductor single crystal is completed.

3. The method for remelting a semiconductor single crystal according to claim 2 ,
wherein, in the determination step,
when the weight of the semiconductor single crystal reaches a predetermined weight or less, the remelting is determined to be terminated.

4. The method for remelting a semiconductor single crystal according to claim 3 ,
wherein the semiconductor single crystal is automatically remolten by automatically performing the crystal immersion step, the remelting detection step, the lowermost end detection step, and the determination step.

5. The method for remelting a semiconductor single crystal according to claim 2 ,
wherein, in the determination step, when the crystal immersion step is determined to be restarted,
a length of the lower end portion of the semiconductor single crystal to be immersed in the melt is set to be less than a depth of the melt in the crucible from the detected lowermost end of the semiconductor single crystal at the subsequent crystal immersion step.

6. The method for remelting a semiconductor single crystal according to claim 5 ,
wherein the semiconductor single crystal is automatically remolten by automatically performing the crystal immersion step, the remelting detection step, the lowermost end detection step, and the determination step.

7. The method for remelting a semiconductor single crystal according to claim 2 ,
wherein the semiconductor single crystal is automatically remolten by automatically performing the crystal immersion step, the remelting detection step, the lowermost end detection step, and the determination step.

8. The method for remelting a semiconductor single crystal according to claim 1 ,
wherein, in the determination step,
when the weight of the semiconductor single crystal reaches a predetermined weight or less, the remelting is determined to be terminated.

9. The method for remelting a semiconductor single crystal according to claim 8 ,
wherein the semiconductor single crystal is automatically remolten by automatically performing the crystal immersion step, the remelting detection step, the lowermost end detection step, and the determination step.

10. The method for remelting a semiconductor single crystal according to claim 1 ,
wherein, in the determination step, when the crystal immersion step is determined to be restarted,
a length of the lower end portion of the semiconductor single crystal to be immersed in the melt is set to be less than a depth of the melt in the crucible from the detected lowermost end of the semiconductor single crystal at the subsequent crystal immersion step.

11. The method for remelting a semiconductor single crystal according to claim 10 ,
wherein the semiconductor single crystal is automatically remolten by automatically performing the crystal immersion step, the remelting detection step, the lowermost end detection step, and the determination step.

12. The method for remelting a semiconductor single crystal according to claim 1 ,
wherein the semiconductor single crystal is automatically remolten by automatically performing the crystal immersion step, the remelting detection step, the lowermost end detection step, and the determination step.

Assignees

• Shinetsu Handotai Kk

Inventors

• Masuda Naoki
• Urano Masahiko

Classifications

• C30B15/14

  Heating of the melt or the crystallised materials · CPC title

• C30B15/28 Primary

  using weight changes of the crystal or the melt, e.g. flotation methods · CPC title

• C30B15/22 Primary

  Stabilisation or shape controlling of the molten zone near the pulled crystal; Controlling the section of the crystal · CPC title