JP4874888B2 - Silica glass crucible for pulling silicon single crystal and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a quartz glass crucible for pulling a silicon single crystal, with which the intake of air bubbles into a silicon single crystal being pulled can be inhibited and the generation of surface vibration of silicon melt can be suppressed when the silicon single crystal is pulled; and to provide a method for manufacturing the same. <P>SOLUTION: The quartz glass crucible 10 for pulling a silicon single crystal is characterized in that in the inner layer 20 of each of the R-part 16 and the bottom part 14, a layer from the inner surface to a depth of at least 1 mm is a layer 22 formed by melting a crystalline synthetic quartz powder, and in the inner layer 20 of the constant diameter part 12, a layer from the inner surface to a depth of at least 1 mm is a layer 24 formed by melting an amorphous synthetic quartz powder. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a quartz glass crucible for pulling a silicon single crystal and a method for producing the same.

  Conventionally, the production of silicon single crystals for semiconductor production is called the so-called Czochralski method (CZ method), in which silicon polycrystals are melted in a crucible made of quartz glass, and seed crystals are immersed in this silicon melt. A method of growing a silicon single crystal by gradually pulling up a seed crystal while rotating a crucible is widely adopted.

  Quartz glass crucibles used for the CZ method generally have a two-layer structure consisting of an outer layer portion containing a large number of bubbles and an inner layer portion that is free of bubbles.

  As the diameter of the single crystal increases, the pulling operation of the single crystal takes a long time, and thus the silica glass crucible is required to have higher purity, and the quartz glass crucible in contact with the silicon melt is required. It is indispensable to form the inner layer portion of synthetic quartz glass (suggested in Japanese Patent Laid-Open No. 1-275496).

  However, in recent years, with the further increase in the diameter of the single crystal, the pulling operation of the single crystal has become longer, so that even a small amount of bubbles exist near the inner surface of the synthetic silica glass inner layer of the silica glass crucible. When the silicon single crystal is pulled up, bubble expansion occurs in the inner layer portion, and bubbles are mixed into the silicon melt as the inner surface of the inner layer portion dissolves. This causes dislocations (crystal defects) due to dislocations and causes a problem of lowering the single crystallization rate.

As a method for preventing the inclusion of bubbles in the inner layer portion of such a quartz glass crucible, for example, as proposed in Japanese Patent No. 3717151, there is a method of grinding and removing fine bubbles near the inner surface of the inner layer portion. .
JP-A-1-27596 Japanese Patent No. 3717151

However, such a method of grinding and removing fine bubbles in the vicinity of the inner surface of the inner layer portion increases the number of steps, which inevitably increases the manufacturing cost.

  Therefore, as a result of earnest research on the bubble generation mechanism in the inner layer part, the synthetic quartz powder used as the raw material for the inner layer part is generally amorphous, so there is no clear melting point and gradually begins to melt. Therefore, it was found that bubbles are likely to remain. Based on this knowledge, when the inner layer of the quartz glass crucible was formed using crystalline synthetic quartz powder as a raw material, no bubbles were generated in the inner layer, but hot water was used during the pulling of the silicon single crystal using this quartz glass crucible. There was a problem that surface vibration would occur.

  The present invention relates to a quartz glass crucible for pulling a silicon single crystal, in which bubbles are not taken into the silicon single crystal to be pulled up and no molten metal surface vibration is caused when the silicon single crystal is pulled, and a method for producing the same The purpose is to provide.

The above object is achieved by a quartz glass crucible for pulling a silicon single crystal having the following constitutions (1) to (3) of the present invention and a method for producing the same.
(1) A straight body portion, an R portion, and a bottom portion are provided, and the straight body portion, the R portion, and the bottom portion each include an outer layer of a translucent natural quartz glass layer that includes a large number of bubbles, and an inner layer of a transparent synthetic quartz glass layer. In the quartz glass crucible for pulling silicon single crystal formed of at least two layers, the inner layer of at least the R portion of the R portion and the bottom portion has a depth of at least 1 mm from the inner surface. A transparent synthetic quartz glass layer formed by fusing amorphous synthetic quartz powder, wherein the inner layer of the straight body is at least 1 mm deep from the inner surface thereof. A quartz glass crucible for pulling a silicon single crystal.
(2) The quartz glass crucible for pulling a silicon single crystal according to the above (1), wherein the R portion has less open bubbles per unit area existing on the inner surface after pulling the single crystal than the straight body portion.
(3) A method for producing a quartz glass crucible for pulling a silicon single crystal as described in (1) or (2) above, wherein the outer layer is molded with natural quartz powder and then the inner layer A step of forming the inner portion with synthetic quartz powder, and the step of forming the inner layer portion with synthetic quartz powder becomes a transparent synthetic quartz glass layer of at least the inner portion of the R portion and the bottom portion. And forming a transparent synthetic quartz glass layer on the inner layer of the straight body with amorphous synthetic quartz powder, and melting the quartz glass crucible by a decompression method. A method for producing a silica glass crucible for pulling up a silicon single crystal.

In the quartz glass crucible of the present invention, the inner layer of at least the R portion of the R portion and the bottom portion where the raw material melt stays long is a layer having a depth of at least 1 mm from the inner surface of the crystalline synthetic quartz powder. Since it is a formed layer, it does not substantially contain bubbles, and therefore, bubbles are not introduced into the silicon melt during the pulling of the silicon single crystal. Air bubbles are not taken in.
On the other hand, since the inner layer of the straight body portion is a layer formed by melting amorphous synthetic quartz powder at a depth of at least 1 mm from the inner surface, the inner surface is not smooth. Surface vibration can be suppressed. In addition, since the inner layer of the straight body portion has a relatively small heat load and is short in the time of being exposed to the raw material melt, the above-described problem due to bubble expansion does not occur. As for the bottom part of the crucible, the inner layer is preferably formed by melting crystalline synthetic quartz powder as in the R part, but the bottom part is far from the heater and generally has a lower thermal load than the R part. For this reason, even if the bottom inner layer is formed of amorphous synthetic quartz powder, a problem hardly occurs.

  Hereinafter, a quartz glass crucible for pulling a silicon single crystal according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view of a quartz glass crucible 10 for pulling a silicon single crystal according to an embodiment of the present invention. As shown in FIG. A straight body portion 12, a bottom portion 14, and an R portion (curved portion) 16 therebetween are provided. The layer structure is composed of an outer layer 18 of a translucent natural quartz glass layer containing many bubbles and an inner layer 20 of a bubble-free transparent synthetic quartz glass layer formed on the inner surface of the outer layer 18. The inner layer 20 is formed of an inner layer first portion 22 formed by melting crystalline synthetic quartz powder at the bottom portion 14 and the R portion 16, and the straight body portion 12 is amorphous. It is made of an inner layer second portion 24 formed by melting synthetic quartz powder. The thickness of the inner layer first portion 22 and the inner layer second portion 24 may be at least 1 mm, and the upper limit is about 40% of the crucible thickness in terms of deformation resistance and cost.

  As shown in FIG. 2, the inner layer 20 is formed by applying the inner layer second portion 24 to the entire inner surface of the outer layer 18, and thereafter, the bottom portion 14 of the inner layer second portion 24 and at least the R portion of the R portion 16. The inner layer first portion 22 formed by melting the crystalline synthetic quartz powder may be provided thereon. In this case, the inner layer first portion 22 and the inner layer second portion 24 have a thickness of at least 1 mm. Conversely, the inner layer first portion 22 may be applied to the entire surface, and then the inner layer second portion 24 may be formed on the inner layer first portion 22 of the straight body portion 12, but this is not preferable from the viewpoint of cost and the like. .

  In the quartz glass crucible 10 for pulling up a silicon single crystal, the diameter is preferably 24 inches or more, particularly 32 inches or more, although not limited.

  Next, a method for manufacturing the silica glass crucible 10 for pulling up a silicon single crystal described above will be described.

The above-described quartz glass crucible 10 for pulling a silicon single crystal is manufactured using the crucible manufacturing apparatus 30 shown in FIG. First, natural quartz powder is supplied from a raw material supply means (not shown) to the rotating graphite mold 32 to form an outer layer molded body corresponding to the outer layer 18 by centrifugal force. The inner layer second partial molded body corresponding to the inner layer second portion 24 is formed by supplying it onto the inner surface of the straight body portion of the outer layer molded body, and finally the crystalline synthetic quartz powder is added to the R portion of the outer layer molded body. Supplying on the inner surface of a bottom part, the inner layer 1st partial molding corresponding to the said inner layer 1st part 22 is formed, and it shape | molds in a crucible shape. The molding order of the inner layer second partial molded body and the inner layer first partial molded body may be reversed. Thereafter, the arc electrode 34 is inserted therein, and discharge is started, and suction is started by the pump P. The mold 32 has air passages 36, 38, 40 opened on the inner surface of the mold, and manifolds 42, 44, 46 that communicate with the air passages 36, 38, 40 (the manifolds 42, 44 communicate with the manifold 46. And an outlet passage 50 connected to the pump P is provided, and suction is performed by the operation of the pump P until the inner layer 20 which is a transparent quartz glass layer is formed on the inner surface of the crucible. Done. After the inner layer 20 having a desired thickness is obtained, the suction by the pump is stopped or weakened, so that the outer layer 18 made of translucent glass is formed, and then cooled and quartz glass for pulling up a silicon single crystal. The crucible 10 is manufactured.
In the above manufacturing method, the predetermined thickness on the inner peripheral side of the molded body of natural quartz powder may be made transparent and form a part of the inner layer. Explained.

The quartz glass crucible 10 for pulling a silicon single crystal according to the embodiment of the present invention as described above is protected by a carbon susceptor 62 in a silicon single crystal manufacturing apparatus 60 as shown in FIG. A crucible drive mechanism (not shown) is supported by the support shaft 66 so as to be rotatable and movable up and down. Then, in the quartz glass crucible 10 for pulling up the silicon single crystal, the polycrystalline silicon raw material is melted by heating with the heater 68 and the seed crystal 74 held in the seed holder 72 is melted as the raw material melt 70. After contacting the liquid 70, the silicon single crystal S is grown by pulling it up while being rotated by the wire 76. The grown silicon single crystal S is accommodated in a pulling chamber 78 connected to the main chamber 64 and taken out.
As described above, a silicon single crystal is manufactured using the silicon single crystal manufacturing apparatus 60 provided with the quartz glass crucible 10 for pulling a silicon single crystal according to the embodiment of the present invention. Here, in the open bubbles existing on the inner surface of the silica glass crucible 10 for pulling up the silicon single crystal after pulling up the silicon single crystal, the R portion may be smaller than the number of open bubbles per unit area of the straight body portion. desirable.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these. In particular, the open bubbles after pulling up the single crystal largely depend on the operating conditions and are not limited to these values.

Example 1
Using the crucible manufacturing apparatus 30 of FIG. 3, purified high-purity natural quartz powder is supplied to a rotating graphite mold 32, and an outer layer molded body corresponding to the outer layer 18 (actually corresponding to the outer layer) by centrifugal force. The same applies hereinafter), and then a predetermined amount of amorphous synthetic quartz powder is supplied onto the inner surface of the outer body of the outer layer molded body to form a powder layer having a thickness of about 3 mm. The crystalline synthetic quartz powder was supplied onto the inner surface of the R portion and the bottom portion of the outer layer molded body to form a powder layer having a thickness of about 4 mm and molded into a crucible shape. Thereafter, the arc electrode 34 was inserted therein, and discharge was started, and suction was started by the pump P. After suction is performed by the operation of the pump P until the transparent quartz glass layer is formed on the inner surface of the crucible by about 4 mm, the suction by the pump is stopped, and the outer layer made of translucent natural quartz glass is further heated by the discharge of the arc electrode 34. 18 was formed. Thereafter, the manufactured crucible was taken out from the graphite mold and allowed to cool to obtain a quartz glass crucible 10 for pulling a silicon single crystal having the shape shown in FIG. The diameter of the crucible is 24 inches. From the analysis result of the quartz glass crucible prepared under the same conditions, the thickness of the inner layer 20 made of transparent synthetic quartz glass is about 1.8 mm, and the inner layer at the R part and the bottom part. The thickness of 20 is about 2.4 mm, and the remaining transparent layer is assumed to be made of natural quartz glass.

The quartz glass crucible for pulling up the silicon single crystal of Example 1 is incorporated into the silicon single crystal manufacturing apparatus shown in FIG. 4, and 150 kg of silicon polycrystalline material is charged into the crucible to pull up the silicon single crystal having a diameter of 200 mm. It was. During the operation, no surface vibration was observed, and the yield of the silicon single crystal was 100%.
When the number of open bubbles having a diameter of 0.1 mm or more opened on the inner surface of the R portion and the straight barrel portion of the crucible after pulling the silicon single crystal was visually counted, the open bubbles in the R portion were about 0.03 / cm ^2. The open foam in the straight body part was about 0.6 / cm ² .
Example 2
Using the crucible manufacturing apparatus 30 of FIG. 3, the purified high purity natural quartz powder is supplied to the rotating graphite mold 32 to form an outer layer portion molding corresponding to the outer layer portion 18 by centrifugal force, A predetermined amount of crystalline synthetic quartz powder is supplied to the entire inner surface of the outer layer molded body to form a powder layer having a thickness of about 3 mm. Finally, the crystalline synthetic quartz powder is added to the inner layer molded body. A powder layer having a thickness of about 2 mm was formed on the inner surface of the R part and molded into a crucible shape. Thereafter, the arc electrode 34 was inserted therein, and discharge was started, and suction was started by the pump P. After suction is performed by the operation of the pump P until the transparent quartz glass layer is formed on the inner surface of the crucible by about 4 mm, the suction by the pump is stopped, and the outer layer made of translucent natural quartz glass is further heated by the discharge of the arc electrode 34. Part 18 was formed. Thereafter, the produced crucible was taken out from the graphite mold and allowed to cool to obtain a quartz glass crucible (not shown) for pulling up a silicon single crystal. The diameter of the crucible is 24 inches. From the analysis result of the quartz glass crucible prepared under the same conditions, the thickness of the inner layer 20 made of transparent synthetic quartz glass at the straight body portion and the bottom portion is about 1.8 mm, and the inner layer at the R portion. The thickness of 20 is estimated to be about 3 mm (of which the layer thickness formed from crystalline synthetic quartz powder is about 1.2 mm).

The quartz glass crucible for pulling up the silicon single crystal of Example 2 is incorporated into the silicon single crystal manufacturing apparatus shown in FIG. 4, and 150 kg of silicon polycrystalline material is charged into the crucible to pull up the silicon single crystal having a diameter of 200 mm. It was. During the operation, no surface vibration was observed, and the yield of the silicon single crystal was 100%.
When the number of open bubbles with a diameter of 0.1 mm or more opened on the inner surface of the R portion, the straight barrel portion, and the bottom portion of the crucible after pulling up the silicon single crystal was visually counted, the open bubbles in the R portion were about 0.04 / cm ² , and the open bubbles in the straight body portion were about 0.5 / cm ² .

Comparative Example 1
Using the crucible manufacturing apparatus 30 of FIG. 3, the purified high purity natural quartz powder is supplied to the rotating graphite mold 32 to form an outer layer molded body corresponding to the outer layer 18 by centrifugal force, and then amorphous. Except for supplying a predetermined amount of synthetic quartz powder over the entire inner surface of the outer layer molded body, forming a powder layer of about 3 mm on the straight body part and about 4 mm on the R part and the bottom part, and molding it into a crucible shape. According to the method of Example 1, a quartz glass crucible for pulling a silicon single crystal of Comparative Example 1 was obtained. The diameter of the crucible is 24 inches, the transparent quartz glass layer is estimated to be about 4 mm, the thickness of the inner layer 20 made of transparent synthetic quartz glass is estimated to be about 1.8 mm at the straight body portion, and about 2.4 mm at the R portion and the bottom portion. The

The silica glass crucible for pulling up the silicon single crystal of Comparative Example 1 is incorporated into the silicon single crystal manufacturing apparatus shown in FIG. 4, and 150 kg of silicon polycrystalline material is charged into the crucible to pull up the silicon single crystal having a diameter of 200 mm. It was. During the operation, no molten metal surface vibration was observed, but the crystal was disturbed in the latter half of the pulling process, and the yield of the silicon single crystal was 82%. When the number of open bubbles having a diameter of 0.1 mm or more opened on the inner surface of the R portion and the straight barrel portion of the crucible after pulling up the silicon single crystal was visually counted, the open bubbles in the R portion were about 1.3 / cm ^2. The open foam in the straight body part was about 0.6 / cm ² .

Comparative Example 2
Using the crucible manufacturing apparatus 30 shown in FIG. 3, purified high-purity natural quartz powder is supplied to a rotating graphite mold 32 to form an outer layer molded body corresponding to the outer layer 18 by centrifugal force, and then crystalline synthesis Except for supplying a predetermined amount of quartz powder over the entire inner surface of the outer layer molded body, forming a powder layer of about 3 mm on the straight body part and about 4 mm on the R part and the bottom part, and molding it into a crucible shape. According to the method of Example 1, a quartz glass crucible for pulling silicon single crystal of Comparative Example 2 was obtained. The diameter of the crucible is 24 inches, the transparent quartz glass layer is estimated to be about 4 mm, the thickness of the inner layer 20 made of transparent synthetic quartz glass is estimated to be about 1.8 mm at the straight body portion, and about 2.4 mm at the R portion and the bottom portion. The

The silica glass crucible for pulling up the silicon single crystal of Comparative Example 2 is incorporated into the silicon single crystal manufacturing apparatus shown in FIG. 4, and 150 kg of silicon polycrystalline material is charged into the crucible to pull up the silicon single crystal having a diameter of 200 mm. It was. Since the hot water surface vibration occurred in the first half of the process and it was necessary to repeat the seeding process and shoulder formation process many times, the operation time was about 1.5 times the normal, and as a result, the yield of silicon single crystals was as low as 75%. became. When the number of open bubbles with a diameter of 0.1 mm or more opened to the inner surface of the R portion and the straight body portion of the crucible after pulling the silicon single crystal was counted visually, the open bubbles in the R portion were about 0.05 / cm ^2. However, it was speculated that the surface condition deteriorated as the operation time became longer, which caused the yield to decrease. Moreover, the open bubbles in the straight body part were about 0.01 / cm ² .
From the above, the effect of the present invention is clear.

It is a schematic sectional drawing of the quartz glass crucible for silicon single crystal pulling by embodiment of this invention. It is a schematic sectional drawing of the quartz glass crucible for silicon single crystal pulling by other embodiment of this invention. It is a schematic sectional drawing of the apparatus for manufacturing the quartz glass crucible for silicon single crystal pulling shown in FIG. It is the schematic of the silicon single crystal manufacturing apparatus incorporating the quartz glass crucible for silicon single crystal pulling shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Silica glass crucible for silicon single crystal pulling 12 Straight body part 14 Bottom part 16 R part 18 Outer layer 20 Inner layer 22 Inner layer 1st part 24 Inner layer 2nd part 30 Crucible manufacturing apparatus 32 Graphite mold 34 Arc electrode 36 Air path 38 Air path 40 Air passage 42 Manifold 44 Manifold 46 Manifold 48 Rotating shaft 50 Outlet passage P Pump 60 Silicon single crystal production device 62 Carbon susceptor 64 Main chamber 66 Support shaft 68 Heater 70 Raw material melt 72 Seed holder 74 Seed crystal 76 Wire 78 Pulling chamber

Claims (3)

  A straight body portion, an R portion, and a bottom portion, and the straight body portion, the R portion, and the bottom portion are at least two of an outer layer of a translucent natural quartz glass layer and a layer of a transparent synthetic quartz glass layer each containing a large number of bubbles. In the quartz glass crucible for pulling up a silicon single crystal formed of layers, the inner layer of at least the R portion of the R portion and the bottom portion has a depth of at least 1 mm from the inner surface and melts the crystalline synthetic quartz powder. A transparent synthetic quartz glass layer formed, and the inner layer of the straight body portion is a transparent synthetic quartz glass layer formed by melting amorphous synthetic quartz powder at a depth of at least 1 mm from the inner surface thereof A quartz glass crucible for pulling silicon single crystals.   The quartz glass crucible for pulling a silicon single crystal according to claim 1, wherein the R portion has less open bubbles per unit area existing on the inner surface after pulling the single crystal than the straight barrel portion.   3. The method for producing a quartz glass crucible for pulling up a silicon single crystal according to claim 1 or 2, wherein the outer layer portion is molded with natural quartz powder, and the inner layer portion is formed inside the synthetic quartz crucible. A step of molding with powder, and the step of molding the inner layer with synthetic quartz powder comprises forming the crystalline synthetic quartz powder into the transparent synthetic quartz glass layer of at least the R portion of the R portion and the bottom portion. And a step of molding the inner synthetic layer of the straight body portion with the amorphous synthetic quartz powder, and the quartz glass crucible is manufactured by melting the quartz glass crucible by a decompression method. A method for producing a silica glass crucible for pulling a silicon single crystal.

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