JPH04209789A - Apparatus for pulling up silicon single crystal - Google Patents

Abstract

PURPOSE:To suppress the oxygen concentration in a crystal to a low level and improve the charging amount by placing a funnel-shaped gas-feeding member in a chamber and directly supplying an inert gas to the liquid surface of molten silicon. CONSTITUTION:A crucible 2 composed of an inner quartz crucible 2a and an outer carbon crucible 2b is placed in a chamber 1 containing a funnel-shaped gas-feeding member 9. The upper end of the feeding member 9 is connected to the upper part of the inner wall of the chamber 1 and the other end of the member 9 is extended close to the boundary 8 between silicon 6 and molten silicon liquid 7 in the crucible 2. A number of feeding holes 10 are formed in the feeding member 9 and an inert gas such as Ar is directly supplied to the above boundary part 8. Since the inert gas flows in the direction of the arrow X, the oxygen concentration in the grown crystal can be suppressed to a low level.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a single-crystal silicon pulling apparatus, and in particular, a structure capable of supplying an inert gas for growing single-crystal silicon as well as an active gas directly to the liquid surface of molten silicon. Related to single crystal silicon pulling equipment with

[Conventional technology] Conventionally, single-crystal silicon has mainly been produced using the Tyzikoralski method (CZ
manufactured by the law). In this method, a polycrystalline silicon raw material is placed in a crucible, heated from the surroundings to melt the polycrystalline silicon, and the melt is pulled up while rotating a pulling shaft that has a seed crystal at the lower end.
It produces single crystal silicon. It is generally known that when pulling single crystal silicon, the specific resistance and oxygen concentration distribution characteristics within the cross section of the single crystal silicon can be improved by increasing the rotational speed of the pulling shaft.

By the way, in devices using such a CZ method, as the diameter of the single crystal increases, the size of the quartz crucible and hot zone members also increases. Under these circumstances, it is becoming difficult to keep crystal properties within specifications.

[Problems to be Solved by the Invention] However, in general, when the amount of polycrystalline silicon (charge amount) used in -times of pulling is increased, the oxygen concentration in the crystal increases. Further, as the diameter increases, the amount of charge must be increased, but if it is increased too much, the oxygen concentration will exceed the standard.

The present invention was made in view of the above circumstances, and it is possible to suppress the oxygen concentration in the crystal to a low level, thereby improving the charge amount of single-crystal silicon by creating a structure in which an inert gas can be directly supplied to the liquid surface of the molten silicon. The purpose is to provide a lifting device.

[Means for Solving the Problems] The present invention provides a pulling device consisting of a wire or a bead having a seed crystal at the lower end, in which a crucible is placed in a chamber, and molten silicon in the crucible is raised at the lower end. It is characterized by comprising a funnel-shaped gas supply member that reaches from the upper part of the chamber to near the molten silicon liquid level in the crucible and has an opening formed therein for supplying an inert gas directly to the molten silicon liquid level. This is a single-crystal silicon pulling device.

[Function] According to the present invention, the upper end of the chamber is connected to the upper inner wall of the chamber, the other end reaches near the boundary between the silicon in the crucible and the molten silicon liquid level, and an inert gas is introduced inside the boundary at the boundary. The structure includes a funnel-shaped gas supply member with numerous supply holes for direct supply of inert gas to the boundary between silicon and molten silicon during crystal growth. be able to. Therefore, compared to the conventional method, the oxygen concentration can be kept low, and productivity can be improved and costs can be reduced. Furthermore, according to this configuration,
The funnel-shaped gas supply member serves as a radiation shield and prevents SiO2 from entering the melt.

[Example code] An embodiment of the present invention will be described below with reference to FIG.

1 in the figure is a chamber with an open top and bottom.

In this chamber 1, a crucible 2 consisting of a quartz crucible 2a and a carbon crucible 2b outside the quartz crucible 2a is arranged. A rotatable support rod 3 inserted through the lower opening of the chamber 1 is connected to the bottom of the crucible 2. A heater 4 is arranged outside the crucible.

A heat insulating member 5 is arranged outside the heater 4. A funnel-shaped gas supply member 9 is disposed within the chamber 1, the upper end of which is connected to the upper inner wall of the chamber 1, and the other end of which reaches close to the boundary 8 between the silicon 6 and the molten silicon liquid 7 in the crucible. A large number of supply holes 10 are formed inside the supply member 9 for directly supplying an inert gas such as Ar gas to the boundary portion 8 . This supply hole 1
An Ar purification device (not shown) is connected to the upper part of 0, and Ar gas flows from this device in the direction of arrow X and is sent directly to the boundary 9 between the silicon 6 and the molten silicon liquid level 7. . Further, this Ar gas is discharged out of the chamber from the opening at the bottom of the chamber 1 along with the Ar gas as an atmospheric gas flowing as indicated by arrow Y.

According to the above embodiment, the upper end of the chamber 1 is connected to the upper inner wall of the chamber 1, and the other end reaches near the boundary 9 between the silicon 6 in the crucible and the molten silicon liquid level 7. A funnel-shaped gas supply member 9 in which a number of supply holes 10 are formed for directly supplying gas to the boundary portion 8.
Since the configuration is such that A" is placed during crystal growth,
Gas can be delivered directly to the interface 9 between the silicon 6 and the molten silicon liquid level 7. Therefore, the oxygen concentration can be kept lower than in the past.

FIG. 3 is a characteristic diagram showing the relationship between oxygen concentration and crystal length when a φ6 single crystal is grown with a charge of 40 kg, (a) shows the conventional crystal, and (b) shows the crystal of the present invention. show. In the case of the present invention, Ar gas of 50ff/1n was fed for growth. This confirmed that the oxygen concentration could be suppressed lower in the case of the present invention than in the conventional case.

In the above embodiment, a case was described in which Ar gas was used as the inert gas sent to the boundary between silicon and the molten silicon liquid level, but the present invention is not limited to this.

Further, in the above embodiment, a case has been described in which a large number of supply holes are provided inside the funnel-shaped gas supply member, but the present invention is not limited to this, and a structure in which the supply holes are connected inside may be used.

[Effects of the Invention] As detailed above, according to the present invention, by providing a structure in which an inert gas can be directly supplied to the molten silicon liquid surface, the oxygen concentration in the crystal can be kept low, thereby improving the charge amount. , it is possible to provide a single-crystal silicon pulling device that can improve productivity and reduce costs.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a single crystal silicon pulling apparatus according to an embodiment of the present invention, Fig. 2 is a perspective view of a funnel-shaped gas supply member of this apparatus, and Fig. 3 shows the relationship between oxygen concentration and crystal length. FIG. 1...Chamber, 2a...Quartz crucible, 2b...
・Carbon crucible, 3... Crucible, 4... Heater,
5... Heat insulation member, 6... Silicon, 7... Molten silicone liquid, 8... Boundary part, 9... Funnel-shaped gas supply member, 10... Supply hole. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] In a pulling device comprising a wire or a bead having a seed crystal at the lower end, a crucible is placed in a chamber, and molten silicon in the crucible is pulled into the chamber from the upper part of the chamber into the crucible. A single-crystal silicon pulling device comprising: a funnel-shaped gas supply member that reaches close to the molten silicon liquid level and has an opening formed inside for directly supplying an inert gas to the molten silicon liquid level. 3.