JPH06271397A - Apparatus for pulling up single crystal - Google Patents

Abstract

PURPOSE:To efficiently improve quality by providing the bottom end of a water cooling cylinder of the prescribed apparatus with an inert gas blow-off port directed to a single crystal and providing the peripheral surface of the inside wall of this cooling cylinder near this blow-off port with a receiving rack. CONSTITUTION:A seed crystal S is immersed into a melt M in a crucible 4 in which this melt is formed by heating and melting with a heater 3 which is arranged on the inner side of a shield 2 of the apparatus 1 for pulling up the single crystal; thereafter, this seed crystal is pulled up to obtain the single crystal C. A purging tube 5 having a cylindrical shape is then arranged concentrically on the outer peripheral surface of the single crystal C and the bottom end of this tube 5 is provided with a gaseous Ar ejection port 6 directed to the single crystal C right above the melt M. Further, the inner peripheral surface right above this ejection port 6 is provided with a rack member 7. The gaseous Ar is blown from the ejection port 6 to the area where the crystal is grown while the single crystal C is pulled up, by which rotating branch flows are formed. The single crystal is produced by pulling up while the cooling capacity is improved by these branch flows, one of which flows on the melt surface and the other of which ascends the flanks of the crystal C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Czochralski (CZ) method for pulling a single crystal having an inert gas flow control means.

[0002]

2. Description of the Related Art As an apparatus for pulling Si single crystal by the Czochralski method, as disclosed in Japanese Patent Laid-Open No. 61-68389, a single crystal pulled from Si melt is concentrically spaced around the single crystal. It is known that a cylindrical water cooling cylinder is arranged in the inside of the cylinder and Ar gas is supplied into the cooling cylinder from above.

This purge tube shields the radiant heat in the furnace to the single crystal being pulled to cool the single crystal, increase the pulling rate of the single crystal, and ventilate Ar gas from above the melt to the outside of the system. , Has a function of preventing agglomerates of SiO and CO generated by the reaction between the Si melt and the quartz crucible from dropping into the melt.

Japanese Patent Laid-Open No. 2-97481 discloses that
An attempt is made to reduce the diameter of the lower end opening of the cooling cylinder from above to accelerate the flow rate of the gas ejected from the lower end opening of Ar gas to the single crystal pulling region to improve the cooling efficiency. However, in this case, Ar sprayed in the pulling area
Since the gas flows down along the side surface of the high temperature Si single crystal in the cooling cylinder and is then jetted in a heated state, the cooling capacity at the lower end of the pulled single crystal has an expected effect. I can't name it.

Further, in Japanese Unexamined Patent Publication No. 4-209789, a funnel-type gas supply member directly supplies an inert gas in the vicinity of the molten silicon solidification interface, whereby the oxygen concentration in the single crystal can be suppressed to a low level. It is disclosed. However, while passing through the inside of the funnel-shaped gas supply member,
Since the temperature of the inert gas rises and the crystal cannot be cooled effectively, a large increase in the temperature gradient of the single crystal cannot be expected.

[0006]

DISCLOSURE OF THE INVENTION According to the present invention, Ar gas is directly sprayed on the above-mentioned pulling region, and the Ar gas is separated into an ascending flow rising in a cylindrical heat shield member and a flow along the molten metal surface. The present invention relates to an improvement of a single crystal pulling apparatus for a single crystal pulling apparatus having a cylindrical heat shield member, in which impurities such as SiO agglomerates are blown to the pulling area without dropping onto the melt. It is to provide a means for further enhancing the cooling ability by the attached Ar gas.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a single crystal pulling apparatus having a cylindrical heat shield member concentrically surrounding a pulled single crystal, and is integrally attached to the lower end of the cylindrical heat shield member. And two upward and downward inert gas outlets directed directly above the solidification interface of the pulled single crystal are provided, and a receiving shelf is provided around the inner wall of the cylindrical heat shield member near the inert gas outlet. It is characterized by being provided.

Incidentally, the inert gas can be provided as a separate system from the blow-off from the usual upper part of the pulling device.

[0009]

[Function] The inert gas blown just above the solidification interface of the pulled single crystal has a large cooling capacity because it is not heated, and is blown upward and downward, so that it can be cooled over a wide area of the pulled single crystal surface. A large temperature gradient is formed in the pulled single crystal, which can increase the pulling rate of the single crystal.

After hitting the surface of the single crystal from the downward outlet, the gas becomes a flow along the melt surface and an upward reversal flow. Further, the flow along the liquid surface is normally supplied from the upper part and enhances the effect of the gas flow discharged from the lower part. As a result, it becomes possible to enhance the effect of discharging SiO and CO gas, prevent dislocation, and reduce the carbon concentration of the single crystal.

Further, since the receiving shelf is provided around the inner wall of the cylindrical heat shield member near the inert gas outlet, the gap between the cylindrical heat shield member and the single crystal is narrowed,
The flow rate of the inert gas is increased, and the cooling capacity by the inert gas is further increased. Further, the presence of this shelf receives the SiO agglomerates brought in with the forced ascending flow and the reversing ascending flow, prevents them from falling onto the melt surface, and prevents dislocation.

[0012]

FIG. 1 shows an embodiment of the present invention.

In the drawing, in the single crystal pulling apparatus 1 of the present invention, the seed crystal S is dipped in the melt M in the crucible 4 heated and melted by the heating apparatus 3 arranged inside the shield 2 and then pulled up. A cylindrical purge tube 5 is concentrically arranged on the outer peripheral surface of the single crystal C.

At the lower end of the purge tube 5, an Ar gas ejection port 6 is provided which directs the crystal directly above the melt, and a shelf member 7 is provided on the inner peripheral surface immediately above the ejection port 6. .

FIG. 2 is an explanatory view of the detailed structure of the purge tube 5 and its operation.

As shown in the figure, the jet port 6 formed at the lower end of the purge tube 5 is formed as a nozzle hole which is inclined inwardly at an angle of about 45 degrees, and a rim edge 8 extends at the lower end thereof. ing. Shelf member 7 immediately above the nozzle-shaped ejection port 6
The nozzle protrudes inward as it is, and the purge tube 5
Is formed in a receiving shape on the inner peripheral surface of the.

Ar gas from the jet port 6 indicated by an arrow hits the single crystal growth region directly above the melt and turns from there to form a branched flow. One forms a flow that flows on the melt surface and exits the system, and the other forms a branched flow that rises along the side surface of the single crystal C. Purge tube 5 and single crystal C
Since the space between and is narrowly formed by the shelf member 7, the upward branch flow becomes faster, but its amount is limited, and the amount of flow on the melt increases, so that harmful production components such as SiO and CO are discharged. Will help.

[0018]

The present invention has the following effects.

(1) Since the inert gas is directly blown to the crystal growth region, cooling of the crystal part directly above the melt proceeds.

(2) Si from the melt surface due to the branched flow of the inert gas after being directly sprayed on the crystal growth region
The ability to discharge harmful components such as O and CO increases due to the presence of the shelf member.

(3) The harmful components introduced into the purge tube by the upward flow are condensed and dropped and accumulated on the shelf,
It does not fall into the melt, and defects in the pulled single crystal are reduced.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a detailed structure of a purge tube according to the present invention and its operation.

[Explanation of symbols]

 1 Single crystal pulling device 2 Shield 3 Heating device 4 Crucible 5 Purge tube 6 Gas ejection port 7 Shelf member 8 Rim edge M Melt S Seed crystal C Single crystal

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masamichi Okubo 3434 Shimada, Hitsu-shi, Yamaguchi Prefecture, Nittetsu Denshi Co., Ltd. (72) Hirofumi Harada, 3434 Shimada, Hikari-shi, Yamaguchi Prefecture, Nittetsu Denshi Co., Ltd. ( 72) Inventor Kiyoshi Morita 3434 Shimada, Hikari City, Yamaguchi Prefecture, Nitetsu Denshi Co., Ltd. (72) Kazuto Kawakami, 3434 Shimada, Hikari City, Yamaguchi Prefecture, Shinko Nippon Steel Co., Ltd.

Claims (1)

[Claims] 1. A single crystal pulling apparatus having a water-cooled cylinder concentrically surrounding the pulled single crystal, wherein an inert gas blowout port directed to the single crystal immediately above the melt is provided at the lower end portion of the water-cooled cylinder, and A single crystal pulling device with a receiving shelf provided on the inner wall peripheral surface of the cooling cylinder near the active gas outlet.