Method for measuring distance between lower end surface of heat insulating member and surface of raw material melt and method for controlling thereof

Patent metadata

Field	Value
Publication number	US-9260796-B2
Application number	US-44884508-A
Country	US
Kind code	B2
Filing date	Jan 10, 2008
Priority date	Feb 8, 2007
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

Abstract

A method for measuring a distance between a lower end surface of a heat insulating member and a surface of a raw material melt with a reference reflector provided at a lower end of the heat insulating member which is located above the surface of the raw material melt when a silicon single crystal is pulled up by a Czochralski method while a magnetic field is applied to the raw material melt in a crucible is disclosed. The method comprises the steps of contacting a projection made of quartz, silicon or carbon with the surface of the raw material melt, the projection being longer that the reference reflector and having a length corresponding to an initial distance; electrically detecting the contact between the projection and the melt surface, and observing an initial location of a mirror image of the reference reflector by a camera when the distance between the lower end surface of the heat insulating member and the surface of the raw material melt has been adjusted so as to be the initial distance, the mirror image being reflected on the surface of the raw material melt; and while pulling the silicon single crystal, measuring a travel distance of the mirror image from the initial location by the camera and calculating the distance between the lower end surface of the heat insulating member and the surface of the raw material melt from the initial travel distance of the mirror image.

First claim

The invention claimed is:

1. A method for measuring a distance between a lower end surface of a heat insulating member and a surface of a raw material melt with a reference reflector provided at a lower end of the heat insulating member which is located above the surface of the raw material melt when a silicon single crystal is pulled up by a Czochralski method while a magnetic field is applied to the raw material melt in a crucible, the method comprising the steps of:
before pulling the silicon single crystal,
adjusting the distance between the lower end surface of the heat insulating member and the surface of the raw material melt so as to be an initial distance by (1) contacting a projection provided at the lower end of the heat insulating member with the surface of the raw material melt by raising the crucible, the projection being longer than the reference reflector and having a length corresponding to the initial distance, and (2) electrically detecting the contact between the projection and the raw material melt using a measurement apparatus that is electrically connected to the projection and the crucible, and
observing an initial location of a mirror image of the reference reflector by a camera when the distance between the lower end surface of the heat insulating member and the surface of the raw material melt has been adjusted so as to be the initial distance, the mirror image being reflected on the surface of the raw material melt; and

while pulling the silicon single crystal, measuring a travel distance of the mirror image from the initial location by the camera and calculating the distance between the lower end surface of the heat insulating member and the surface of the raw material melt from the initial distance and the travel distance of the mirror image.

2. The method for measuring a distance between a lower end surface of a heat insulating member and a surface of a raw material melt according to claim 1 , wherein any one of high-purity quartz, silicon and carbon is used as the reference reflector.

3. The method for measuring a distance between a lower end surface of a heat insulating member and a surface of a raw material melt according to claim 1 , wherein high-purity white quartz or high-purity transparent quartz having a whitened surface is used as the reference reflector.

4. A method for controlling a distance between a lower end surface of a heat insulating member and a surface of a raw material melt when a silicon single crystal is pulled up by a Czochralski method, comprising:
while pulling the silicon single crystal, measuring the distance between the lower end surface of the heat insulating member and the surface of the raw material melt by the method for measuring according to claim 3 ; and
moving the crucible or the heat insulating member on the basis of the measured distance such that the distance between the lower end surface of the heat insulating member and the surface of the raw material melt becomes a setting value.

5. The method for measuring a distance between a lower end surface of a heat insulating member and a surface of a raw material melt according to claim 1 , wherein any one of quartz, silicon and carbon is used as the projection.

6. A method for controlling a distance between a lower end surface of a heat insulating member and a surface of a raw material melt when a silicon single crystal is pulled up by a Czochralski method, comprising:
while pulling the silicon single crystal, measuring the distance between the lower end surface of the heat insulating member and the surface of the raw material melt by the method for measuring according to claim 5 ; and
moving the crucible or the heat insulating member on the basis of the measured distance such that the distance between the lower end surface of the heat insulating member and the surface of the raw material melt becomes a setting value.

7. The method for measuring a distance between a lower end surface of a heat insulating member and a surface of a raw material melt according to claim 1 , wherein a central magnetic field intensity of the applied magnetic field is a horizontal magnetic field of 300 G to 7000 G.

8. A method for controlling a distance between a lower end surface of a heat insulating member and a surface of a raw material melt when a silicon single crystal is pulled up by a Czochralski method, comprising:
while pulling the silicon single crystal, measuring the distance between the lower end surface of the heat insulating member and the surface of the raw material melt by the method for measuring according to claim 7 ; and
moving the crucible or the heat insulating member on the basis of the measured distance such that the distance between the lower end surface of the heat insulating member and the surface of the raw material melt becomes a setting value.

9. A method for controlling a distance between a lower end surface of a heat insulating member and a surface of a raw material melt when a silicon single crystal is pulled up by a Czochralski method, comprising:
while pulling the silicon single crystal, measuring the distance between the lower end surface of the heat insulating member and the surface of the raw material melt by the method for measuring according to claim 1 ; and
moving the crucible or the heat insulating member on the basis of the measured distance such that the distance between the lower end surface of the heat insulating member and the surface of the raw material melt becomes a setting value.

Assignees

• Hoshi Ryoji
• Urano Masahiko
• Sonokawa Susumu
• Shinetsu Handotai Kk

Inventors

• Hoshi Ryoji
• Urano Masahiko
• Sonokawa Susumu

Classifications

• C30B15/20

  Controlling or regulating (controlling or regulating in general G05) · CPC title

• C30B15/26 Primary

  using television detectors; using photo or X-ray detectors · CPC title

• C30B15/14

  Heating of the melt or the crystallised materials · CPC title

• C30B29/06

  Silicon · CPC title