Cleaning method, method for producing silicon single crystal, and cleaning device

Patent metadata

Field	Value
Publication number	US-11426775-B2
Application number	US-201816955455-A
Country	US
Kind code	B2
Filing date	Nov 16, 2018
Priority date	Dec 20, 2017
Publication date	Aug 30, 2022
Grant date	Aug 30, 2022

Abstract

A cleaning method includes a first removal step of causing an inert gas to which a pulsation is applied to flow into an exhaust pipe after a silicon single crystal doped with an n-type dopant is produced, to peel and remove a deposit; and a second removal step of causing an atmospheric air to which no pulsation is applied to flow into the exhaust pipe through a chamber to burn a part of the deposit with the atmospheric air, the part being not removable in the first removal step, and peel and remove a burned substance of the deposit.

First claim

The invention claimed is:

1. A cleaning method for removing a deposit containing an evaporated substance of a dopant deposited in an exhaust pipe in a single crystal pulling-up system comprising a chamber and the exhaust pipe that exhaust a gas in the chamber, the method comprising:
after a silicon single crystal doped with an n-type dopant is produced,
a burning process of causing atmospheric air to which no pulsation is applied to flow into the exhaust pipe through the chamber to burn a part of the deposit with atmospheric air;
after the burning process, a first removal process of causing an inert gas to which a pulsation is applied to flow into the exhaust pipe, to peel and remove a further part of the deposit; and
a second removal process of causing atmospheric air to which no pulsation is applied to flow into the exhaust pipe through the chamber to burn at least another part of the deposit with atmospheric air, the at least another part of the deposit being unremoved in the first removal process, and the second removal process peeling and removing a burned substance of the at least another part of the deposit.

2. The cleaning method according to claim 1 ,
wherein the single crystal pulling-up system is provided with a vacuum pump that regulates a pressure in the chamber during production of the silicon single crystal, and a blower that suctions the deposit in the exhaust pipe,
the first removal process peels the further part of the deposit and suctions the further part of the deposit with the blower by causing the inert gas to which the pulsation is applied to flow into the exhaust pipe in a state where a drive of the vacuum pump is stopped and the blower is driven, and
the second removal process peels the burned substance of the at least another part of the deposit and suctions the burned substance of the at least another part of the deposit with the blower.

3. The cleaning method according to claim 1 ,
wherein the single crystal pulling-up system is provided with a vacuum pump that regulates a pressure in the chamber during production of the silicon single crystal,
the first removal process peels the further part of the deposit and suctions the further part of the deposit with the vacuum pump by causing the inert gas to which the pulsation is applied to flow into the exhaust pipe in a state where the vacuum pump is driven, and
the second removal process peels the burned substance of the at least another part of the deposit and suctions the burned substance of the at least another part of the deposit with the vacuum pump.

4. The cleaning method according to claim 1 ,
wherein the chamber comprises a main chamber and a pull chamber,
in the first removal process, the pull chamber is removed from the main chamber and an exhaust hole valve is disposed in an exhaust hole in the main chamber which communicates with an inside of the exhaust pipe, a connection opening in the main chamber, which is connected to the pull chamber, is closed with a lid, the exhaust hole valve closes the exhaust hole to bring a pressure in the exhaust pipe to a negative pressure, the main chamber is filled with the inert gas through a supply pipe provided in the lid, and the exhaust hole valve opens and closes the exhaust hole to generate a pressure fluctuation in the exhaust pipe, which causes the pressure in the exhaust pipe to return to a pressure of the main chamber, so that the inert gas to which the pulsation is applied flows into the exhaust pipe, and
in the second removal process, the exhaust hole valve opens the exhaust hole, and the lid is moved away from the connection opening or a valve provided in the lid is opened, so that atmospheric air to which no pulsation is applied flows into the exhaust pipe.

5. The cleaning method according to claim 1 ,
wherein the chamber comprises a main chamber and a pull chamber,
the main chamber comprises a plurality of divisible chambers,
in the first removal process, the pull chamber is removed from the main chamber and an exhaust hole valve is disposed in an exhaust hole in the main chamber which communicates with an inside of the exhaust pipe, a connection opening in the main chamber, which is connected to the pull chamber, is closed with a lid, the exhaust hole valve closes the exhaust hole to bring a pressure in the exhaust pipe to a negative pressure, the main chamber is filled with the inert gas through a supply pipe provided in the lid, and the exhaust hole valve opens and closes the exhaust hole to generate a pressure fluctuation in the exhaust pipe, which causes the pressure in the exhaust pipe to return to a pressure of the main chamber, so that the inert gas to which the pulsation is applied flows into the exhaust pipe, and
in the second removal process, the exhaust hole valve opens the exhaust hole and one of the plurality of divisible chambers is moved to form a gap between another divisible chamber and the one, so that atmospheric air to which no pulsation is applied flows into the exhaust pipe.

6. The cleaning method according to claim 4 ,
wherein a main chamber side end portion in the exhaust pipe is divided into a plurality of branch portions,
the main chamber is provided with a plurality of the exhaust holes that communicate with insides of the branch portions of the exhaust pipe, and
in the first removal process, the exhaust hole valve is a plurality of valves disposed in the plurality of exhaust holes, and a process of opening and closing the exhaust holes with at least one of the plurality of exhaust hole valves except for at least another one of the plurality of exhaust hole valves to cause the inert gas to which the pulsation is applied to flow into the exhaust pipe, and a process of filling the main chamber with the inert gas through the supply pipe are repeated a plurality of times.

7. The cleaning method according to claim 4 ,
wherein in the first removal process, after a differential pressure between the main chamber and the exhaust pipe becomes 20 kPa or greater, the exhaust hole is opened and closed to apply the pulsation to the inert gas.

8. The cleaning method according to claim 1 ,
wherein the exhaust pipe is provided with a rising portion extending vertically,
a falling object trap is provided at a lower end of the rising portion, and
in the first removal process and the second removal process, the further part of the deposit and the at least another part of the deposit are trapped by the falling object trap, wherein the further part of the deposit and the at least another part of the deposit are not passable through the rising portion and fall due to a weight of the further part of the deposit and a weight of the at least another part of the deposit.

9. A method for producing a silicon single crystal, the method comprising:
producing a silicon single crystal doped with an n-type dopant using a single crystal pulling-up system in which a deposit is removed from an exhaust pipe by the cleaning method according to claim 1 .

10. The cleaning method according to claim 5 ,
wherein a main chamber side end portion in the exhaust pipe is divided into a plurality of branch portions,
the main chamber is provided with a plurality of the exhaust holes that communicate with insides of the branch portions of the exhaust pipe, and
in the first removal process, the exhaust hole valve is a plurality of valves disposed in the plurality of exhaust holes, and a process of opening and closing the exhaust holes with at least one of the plurality of exhaust hole valves except for at least another one of the plurality of exhaust hole valves to cause the inert gas to which the pulsation is applied to flow into the exhaust pipe, and a process of filling the m

Assignees

• Sumco Corp

Inventors

• Maegawa Koichi
• Yotsui Takuya
• Hamakawa Satoru

Classifications

• B08B7/0071

  by heating (B08B7/0035 takes precedence) · CPC title

• C30B29/06

  Silicon · CPC title

• C30B15/00 Primary

  Single-crystal growth by pulling from a melt, e.g. Czochralski method (under a protective fluid C30B27/00) · CPC title

• B08B5/04

  Cleaning by suction, with or without auxiliary action · CPC title

• C30B15/04

  adding doping materials, e.g. for n-p-junction · CPC title