Method for manufacturing silicon single crystal
A method for manufacturing a silicon single crystal is provided including producing a silicon melt in a chamber by melting a silicon raw material loaded into a silica glass crucible under a reduced pressure and high temperature, removing gas bubbles from within the silicon melt by rapidly changing at least the pressure or temperature within the chamber, and pulling up the silicon single crystal from the silicon melt after the gas bubbles are removed. When the pressure is rapidly changed, the pressure within the chamber is rapidly changed at a predetermined change ratio. In addition, when the temperature is rapidly changed, the temperature within the chamber is rapidly changed at a predetermined change ratio. In this way, Ar gas attached to an inner surface of the crucible and h is the cause of the generation of SiO gas is removed.
1. A method for manufacturing a silicon single crystal comprising:
producing a silicon melt in a chamber by melting a silicon raw material loaded into a silica glass crucible under a reduced pressure and a temperature;
removing gas bubbles from within the silicon melt by changing at least the pressure or temperature within the chamber; and
pulling up the silicon single crystal from the silicon melt after the gas bubbles are removed, wherein:
a pressure change ratio within the chamber when removing the gas bubbles within the silicon melt is 5 times or more and 1000 times or less than a pressure change ratio when reducing the pressure inside the chamber in order to melt the silicon raw material, and
a temperature change ratio within the chamber when removing the gas bubbles within the silicon melt is 5 times or more and 100 times or less than a temperature change ratio when increasing the temperature inside the chamber in order to melt the silicon raw material.
2. The method for manufacturing a silicon single crystal as claimed in claim 1 , wherein a pressure decrease rate inside the chamber when removing the gas bubbles from the silicon melt is 1.5 hPa/sec or more and 20 hPa/sec or less.
3. The method for manufacturing a silicon single crystal as claimed in claim 1 , wherein a temperature increase rate inside the chamber when removing the gas bubbles from the silicon melt is 0.5° C./sec or more and 5° C./sec or less.
4. The method for manufacturing a silicon single crystal as claimed in claim 1 , wherein pulling up the silicon single crystal is started after removing the gas bubbles from the silicon melt by rapidly changing at least the pressure or temperature within the chamber is repeated a plurality of times.
5. The method for manufacturing a silicon single crystal as claimed in claim 1 , wherein after producing the silicon melt and before removing the gas bubbles from the silicon melt by changing at least the pressure or temperature within the chamber, the silicon melt is left as the temperature and pressure within the chamber are maintained at a constant rate and the gas within the silicon melt is discharged.
6. The method for manufacturing a silicon single crystal as claimed in claim 1 , wherein after the gas bubbles are removed, the temperature is adjusted until the temperature of the silicon melt is stable before pulling up the silicon single crystal from the silicon melt.