JP2020023411A - Quartz glass crucible, and manufacturing method of quartz glass crucible - Google Patents

Abstract

To provide a quartz glass crucible that prevents falling of a trunk to the inside and deformation of a trunk in an enlarged quartz glass crucible and prevents peeling-off caused by density difference in the boundary where a plurality of layers having various characteristics contact each other directly, and to provide a manufacturing method of the quartz glass crucible.SOLUTION: A quartz glass crucible 8 for drawing up a silicon single crystal has a trunk of low density in the upper part of the trunk and a bottom of high density. The quartz glass crucible 8 for drawing up a silicon single crystal having a trunk and a bottom and composed of a plurality of layers has a density difference of 0.0014 g/cmor less between an outer layer and an inner layer in the boundary where both the layers contact each other.SELECTED DRAWING: Figure 2

Description

The present invention relates to a quartz glass crucible, particularly to a quartz glass crucible for pulling a silicon single crystal, and even if the quartz glass crucible has a large diameter and a large capacity, the quartz glass crucible is generated at a high temperature when pulling a silicon single crystal. TECHNICAL FIELD The present invention relates to a quartz glass crucible and a method for manufacturing a quartz glass crucible that suppress deformation such as falling down to the side and occurrence of separation at a boundary between an outer layer made of natural quartz glass and an inner layer made of synthetic quartz glass.
In the present specification, a heat treatment including an arc melting and a cooling treatment that is continuously performed thereafter is referred to as an “arc heat treatment”, and a new quartz glass crucible once manufactured or a single crystal grown by the CZ method is grown. The heat treatment performed to remove internal strain and homogenize the quartz glass crucible used in the above is called "annealing treatment".

  A silicon single crystal used for a semiconductor substrate or the like is usually manufactured by a Czochralski method (CZ method) using a quartz glass crucible. In the CZ method, a polycrystalline silicon raw material is introduced into a quartz glass crucible, heated and melted into a silicon melt, and then a seed crystal is brought into contact with the silicon melt from above, while rotating the quartz glass crucible, This is a method of obtaining a silicon single crystal by gradually pulling up the seed crystal.

For this quartz glass crucible for pulling a silicon single crystal, for example, as described in Patent Document 1, rotating arc melting method, that is, a quartz raw material powder is supplied into a rotating quartz glass crucible molding die, Forming a crucible-shaped molded body, applying pressure reduction from the inner surface to the outer surface direction for the crucible-shaped molded body, and performing arc melting while rotating the crucible-shaped molded body, the inner surface side is a transparent layer, the outer surface side is A quartz glass crucible serving as a bubble layer has been manufactured.
The transparent layer is a layer from which bubbles are removed by decompression during arc melting, and the bubble layer is a layer in which bubbles remain.
For the material of such a quartz glass crucible, the outer layer is a natural quartz glass layer (a layer formed by melting natural quartz powder) and the inner layer is synthesized according to the required characteristics. A quartz glass layer (a layer formed by melting synthetic silica powder) (Patent Document 2), an outer layer is a natural quartz powder layer, an intermediate layer is a natural quartz powder layer or a high-purity synthetic quartz powder layer, and an inner layer is a A multi-layer structure such as a three-layer structure of a high-purity synthetic quartz powder layer (Patent Documents 3 and 4) has been proposed.

Here, the difference between layers depending on the material, that is, the natural quartz glass layer and the synthetic quartz glass layer, and the difference between the layers due to the presence or absence of bubbles, that is, the bubble layer and the transparent layer are independently defined. Is done.
For example, a transparent layer and a bubble layer exist in a natural quartz glass layer, and a synthetic quartz glass layer and a natural quartz glass layer exist in a transparent layer.

JP 2010-105881A JP 2010-126423 A JP 2000-247778 A JP 2015-127287 A JP 2012-17242 A JP 2009-298652 A JP-A-5-58667 JP 2008-297154 A

Phys. Rev. B Vol.28 No.6, p.3266-3271, Sept., 1983

In recent years, further improvement in the yield of silicon single crystals has been studied, and large-diameter, large-capacity quartz glass crucibles have been used.As a result, the melting state of the silicon melt in the crucible has been prolonged, and quartz It has been pointed out that the heating load on the glass crucible is increasing, and when the glass crucible is exposed to a high temperature exceeding the glass softening point, the quartz glass crucible may fall down inside the straight body or may be thermally deformed.
That is, as described above, a quartz glass crucible for pulling a silicon single crystal is manufactured by, for example, a rotating arc melting method, but usually, after the arc melting, cooling proceeds from the upper portion of the crucible. The temperature is high, that is, the density is high, and the virtual temperature gradually decreases from the crucible straight body to the bottom. As a result, the density decreases toward the bottom. Therefore, conventionally, as described in Patent Document 5 and Patent Document 6, for example, a quartz glass crucible is supported in contact with a susceptor made of graphite or carbon, and a straight body of the quartz glass crucible is rotated while rotating the susceptor. By applying centrifugal force to the part, it was prevented from falling inward.

However, with the enlargement of the quartz glass crucible, the virtual temperature difference between the upper and lower parts of the crucible has increased, and the density difference has widened. Therefore, simply supporting the crucible with the conventional susceptor can cope with deformation such as falling down. Since it is not possible to do so and a fall occurs, a further solution is required.
In addition, as described above, the quartz glass crucible is usually composed of a plurality of layers of natural quartz glass and synthetic quartz glass, but at the boundary, the densities of the respective glass layers at the virtual temperature are different. It has also been pointed out that even if each glass layer has the same virtual temperature, a problem that abnormal expansion occurs due to a difference in density between the glass layers and peeling of the glass layer occurs, There is also a need for measures against peeling.

  Therefore, the present invention makes it possible to optimize the density distribution at the top and bottom of the quartz glass crucible by adjusting the virtual temperature at each position of the crucible, and to prevent the straight body from falling down and deforming, Furthermore, in a quartz glass crucible having a plurality of layers composed of different types of quartz glass, for example, a natural quartz glass and a synthetic quartz glass, each of the density distributions at a boundary portion between the natural quartz glass layer and the synthetic quartz glass layer. Provided is a quartz glass crucible capable of preventing a natural quartz glass layer from being separated from a synthetic quartz glass layer by adjusting the fictive temperature of the quartz glass so as to optimize the quartz glass crucible, and a method of manufacturing such a quartz glass crucible. It is intended to do so.

  The present inventors, in order to solve the above problems, regarding the quartz glass crucible, the density at the top and bottom of the quartz glass crucible, and the density at the boundary between the natural quartz glass layer and the synthetic quartz glass layer, the quartz glass crucible The following findings were obtained as a result of diligent research conducted while adjusting with the virtual temperature.

  That is, 1) usually produced by an arc melting method or the like, the density is high because the virtual temperature is high at the top, and the density is low because the virtual temperature is low at the bottom. The top, the straight body, and the bottom of the quartz glass crucible It has been found that a quartz glass crucible having a low fictive temperature at the top and a low density and a high fictive temperature at the bottom and a high density can be manufactured by performing an appropriate annealing treatment on each of them.

  2) In order to prevent separation between the natural quartz glass layer and the synthetic quartz glass layer, it is necessary to adjust the density of each quartz glass layer so that the density difference between the quartz glass layers at the boundary is eliminated. However, regarding the relationship between the virtual temperature and the density of natural quartz glass and synthetic quartz glass, from the melting temperature of quartz glass to the adjustable fictive temperature range of 1000 ° C. to 1400 ° C. to 1500 ° C. In the temperature range of, although each quartz glass increases in density in response to the increase in virtual temperature, the density when viewed at the same virtual temperature is always higher for natural silica glass and lower for synthetic silica glass, It has been found that by increasing the virtual temperature of synthetic quartz glass and lowering the virtual temperature of natural quartz glass, these density differences can be reduced.

  And 3) the quartz glass crucible having the characteristics obtained from the knowledge of the above 1) and / or 2) is a specific cooling that is performed continuously with the quartz glass crucible in a high temperature state immediately after being obtained by the rotating arc melting method. Although it is manufactured by processing, it is also possible to manufacture a new quartz glass crucible once manufactured by a normal method such as a rotating arc melting method by performing a reheating annealing process and then cooling. Further, it can be manufactured by performing an annealing treatment on a quartz glass crucible already used for growing a single crystal by the CZ method.

And the present invention has been made based on the above findings,
“(1) In a quartz glass crucible for pulling a silicon single crystal having a straight body and a bottom,
A quartz glass crucible for pulling a silicon single crystal, characterized in that the density is low at the top of the straight body and high at the bottom.
(2) It consists of a natural quartz glass layer or a synthetic quartz glass layer, (1)
4. A quartz glass crucible for pulling a silicon single crystal as described in 1. above.
(3) The quartz glass crucible for pulling a silicon single crystal according to (1), wherein the quartz glass crucible has a natural quartz glass layer as an outer layer and a synthetic quartz glass layer as an inner layer.
(4) The silicon single crystal according to (1) or (3), which has a natural quartz glass layer as an outer layer, a natural quartz glass layer or a synthetic quartz glass layer as an intermediate layer, and a synthetic quartz glass layer as an inner layer. Quartz glass crucible for crystal pulling.
(5) In a quartz glass crucible for pulling a silicon single crystal having a straight body and a bottom,
It has a natural quartz glass as the outer layer, a synthetic quartz glass layer as the inner layer, and a density difference between the respective layers at the boundary where the outer layer and the inner layer are in contact is 0.0014 g / cm ³ or less. Quartz glass crucible for pulling silicon single crystal.
(6) In a quartz glass crucible for pulling a silicon single crystal having a straight body and a bottom,
It has a natural quartz glass layer as an outer layer, a natural quartz glass layer or a synthetic quartz glass layer as an intermediate layer, a synthetic quartz glass layer as an inner layer, and at the boundary where layers made of different types of quartz glass are in direct contact. , The density difference at the boundary of each layer is 0.0
A quartz glass crucible for pulling a silicon single crystal, which is not more than 014 g / cm ³ .
(7) In a quartz glass crucible for pulling a silicon single crystal having a straight body and a bottom,
The quartz glass crucible for pulling a silicon single crystal as described in (5) or (6), wherein the density is low at the top of the straight body portion and high at the bottom.
(8) A method for producing a quartz glass crucible for pulling a silicon single crystal, comprising supplying a raw material quartz powder into a rotating quartz glass crucible molding die, depositing the raw material quartz powder to a predetermined thickness, and then mounting the inside of the molding die. After the entire inner surface of the deposited raw material quartz powder is arc-melted, quenching is started from the bottom of the quartz crucible, and cooling is sequentially performed up to the upper part of the straight body, and the fictive temperature is high at the bottom. By providing a virtual temperature gradient so that the virtual temperature gradually decreases from the bottom toward the top of the straight body, the density is high at the bottom, and the density gradually decreases from the bottom of the straight body to the top. A method for manufacturing a silicon single crystal pulling stone, a glass crucible.
(9) In the method of manufacturing a quartz glass crucible for pulling a silicon single crystal described in (8), means for starting quenching from the bottom of the quartz crucible and then sequentially cooling down to above the straight body. Moves the cooling gas that cools nitrogen gas etc. up and down after the arc melting process.Introduces the cooling gas into the quartz glass crucible using a movable cooling pipe, and cools from the crucible bottom inside the crucible to the top of the crucible body. A method for producing a quartz glass crucible for pulling a silicon single crystal, which is performed by sequentially moving a tube.
(10) In the method for producing a quartz glass crucible for pulling a silicon single crystal described in (8) or (9), quenching is started from the bottom of the quartz crucible, and thereafter, cooling is sequentially performed to a position above the straight body. The means to do this is to provide a number of cooling holes for cooling the quartz glass crucible from the outside in the mold for manufacturing quartz glass crucibles, and at each cooling position from the bottom of the crucible to the top of the crucible body, use strong cooling at the bottom of the crucible, Cool slowly in the upward direction of the straight body, or immediately start cooling at the bottom of the crucible for the cooling start time after the end of the arc, and then keep it warm for a certain period of time until it reaches above the straight body of the crucible. A method of manufacturing a quartz glass crucible for pulling a silicon single crystal, by sequentially starting cooling.
(11) A method for producing a quartz glass crucible for pulling a silicon single crystal, comprising the steps of: placing these layers in the order of an outer layer and an inner layer, or an outer layer, an intermediate layer, and an inner layer in a rotating quartz glass crucible mold. A raw material quartz powder for forming is supplied, deposited to a predetermined thickness, and then the entire inner surface of the deposited raw material quartz powder is arc-melted from the inside of a molding die, and then a different type of quartz glass is formed. In order to reduce the difference in density between the two quartz glass layers at the boundary where the layers are in contact, lower the virtual temperature for layers with natural quartz glass that is relatively dense relative to synthetic quartz glass at the same virtual temperature. Thus, the density at the boundary portion is adjusted to be low, and for the layer having synthetic quartz glass, the density at the boundary portion is adjusted to be high by increasing the virtual temperature. Two, characterized in that the density difference was 0.0014 g / cm ³ or less layers, a method of manufacturing a silicon single crystal quartz glass crucible for pulling in the field unit.
(12) A method for producing a quartz glass crucible for pulling a silicon single crystal, comprising the steps of forming an outer layer and an inner layer, or an outer layer, an intermediate layer, and an inner layer in a rotating quartz glass crucible forming mold in the order of these layers. Is supplied and deposited to a predetermined thickness, and then the entire inner surface of the deposited raw material quartz powder is arc-melted from the inside of the molding die, and then from the bottom of the quartz crucible. Rapid cooling is started, and then cooling is performed sequentially up to the upper part of the straight body.The temperature gradient of the virtual temperature is set so that the virtual temperature is higher at the bottom and lower gradually from the bottom toward the upper part of the straight body. By performing cooling such that the heat treatment is performed, the heat treatment is performed so that the density is high at the bottom and the density is gradually reduced from the lower part to the upper part of the straight body part, and at the same time, the different species are simultaneously formed in accordance with the arc heat treatment. In order to reduce the density difference between the two quartz glass layers at the boundary where the quartz glass layers contact each other, the layer with natural quartz glass, which has a relatively high density relative to synthetic quartz glass at the same virtual temperature, is assumed to be virtual. By lowering the temperature, the density at the boundary is adjusted to be low. On the other hand, for the layer having synthetic quartz glass, the density at the boundary is adjusted to be high by increasing the virtual temperature, and the two layers at the boundary are adjusted. A method for producing a quartz glass crucible for pulling a silicon single crystal, wherein the density difference is 0.0014 g / cm ³ or less. "
It is characterized by the following.

The present invention relates to a quartz glass crucible used for pulling a silicon single crystal, and lowers the virtual temperature of the quartz glass at the top of the quartz glass crucible to reduce the density, and increases the virtual temperature of the quartz glass at the bottom to increase the density. By increasing the height, it is possible to prevent the straight body portion of the crucible from falling down or deforming, and to prevent the crucible from being damaged.
Furthermore, in a quartz glass crucible having a plurality of different kinds of quartz glass layers of natural quartz glass and synthetic quartz glass, the virtual temperature of each different kind of quartz glass is adjusted to reduce the density difference at the boundary between the layers. By doing so, separation at the boundary can be prevented.

Since the quartz glass crucible according to the present invention has excellent deformation resistance, and excellent peeling resistance and a long life, by using such a quartz glass crucible, it is possible to produce a high-quality silicon single crystal with high efficiency. Can be.
During the production of a silicon single crystal, the quartz glass crucible is accommodated in a susceptor, so that the production is further stabilized and the efficiency is improved, so that a high quality silicon single crystal can be stably obtained. it can.

Are natural quartz glass (■ (U), □ (He), ▲ (H), ● (JR), ○ (J)) and synthetic quartz glass (△ (SpH), □ (SpV), ○ (S 2) shows the relationship between the virtual temperature (horizontal axis) and the density (vertical axis). (Journal of Non-Crystalline solids 5 (1970) p137) In order to equalize the densities of natural quartz glass and synthetic quartz glass, the fictive temperature of synthetic quartz glass is 1450 ° C. or less, and the fictive temperature of natural quartz glass is 1200 ° C. And the density value in that case is about 2.2030 g / cm ³ or less. FIG. 1 is a schematic view showing an example of a manufacturing apparatus of a quartz glass crucible using a rotating arc melting method. FIG. 2 is a schematic diagram showing another example of a manufacturing apparatus for a quartz glass crucible using a rotating arc melting method. FIG. 2 is a schematic diagram showing an example of an annealing apparatus for performing an annealing process after manufacturing a quartz glass crucible. FIG. 2 is a schematic view showing another example of an annealing apparatus for performing an annealing process after manufacturing a quartz glass crucible.

  Hereinafter, in order to carry out the present invention, for a quartz glass crucible manufactured by an arc melting method, a fictive temperature of quartz glass is adjusted by arc heat treatment or the like, and a silicon single crystal pulling quartz glass having a predetermined density distribution is adjusted. A process of manufacturing a crucible, and a description of a specific embodiment of a quartz glass crucible for pulling a silicon single crystal and a manufacturing method including an annealing treatment method for manufacturing the quartz glass crucible, together with a specific Various embodiments will be described.

<Method of adjusting the density distribution at the top and bottom of a quartz glass crucible>
Normally, a quartz glass crucible for pulling a silicon single crystal is manufactured using a rotating arc melting method.Natural silica glass and synthetic silica glass are charged from the upper part of the crucible, arc-melted from the upper part, and naturally cooled. In the obtained natural silica glass layer and synthetic silica glass layer, the fictive temperature at the top of the crucible and the straight body is higher than that at the bottom of the crucible, the high density at the top and the straight body, and the low density at the bottom. Crucibles are manufactured.

As described above, with the recent increase in the size of quartz glass crucibles for silicon single crystals, increasing the density of the upper part of the quartz glass crucible has a problem of falling into the straight body portion and thermal deformation, To cope with this, the quartz glass crucible is manufactured by the arc melting method, and then the quartz glass crucible is annealed to raise the fictitious temperature at the bottom of the crucible and increase in density from the top to the bottom. It has been proposed to obtain
For example, in a method of manufacturing a quartz glass crucible by a rotating arc melting method, an arc discharge is performed from the inside of the mold to heat and melt the entire inner surface of the quartz powder, and then, when cooling, the bottom of the crucible is rapidly cooled, and then directly cooled. By performing control to reduce the cooling rate above the body, it is possible to obtain a quartz glass crucible having a high density at the bottom with respect to the top and the straight body.

FIG. 2 shows an example of an apparatus for manufacturing a crucible using the rotating arc melting method.
In FIG. 2, a cooling pipe having a cooling nozzle having a rotating mechanism capable of cooling from the bottom of the crucible to the straight body is inserted into the crucible immediately after the arc is melted by a remotely operated robot or the like, and at each position inside the crucible. Cooling is performed while controlling the cooling rate. Here, the rotation mechanism of the cooling pipe or the cooling nozzle for cooling the crucible bottom and the straight body is a mechanism for rotating the cooling nozzle to the bottom and the straight body side with respect to the horizontal axis. By using a mechanism that rotates the pipe around the pipe axis, the bottom of the crucible is rapidly cooled by remote control or the like, and cooling control is performed to lower the cooling rate over the straight body part, thereby controlling the upper and lower pipes. A high-density quartz glass crucible can be obtained at the bottom with respect to the trunk.
In addition, by providing cooling holes at necessary locations in the mold and adjusting the amount of cooling gas blown, finer cooling control can be performed from outside the crucible, and cooling from the cooling holes provided in the lower part of the mold can be performed. By cooling, a high-density quartz glass crucible can be obtained at the bottom.

FIG. 3 shows another example of a crucible manufacturing apparatus using the rotating arc melting method.
In FIG. 3, a cooling pipe having a shape along the inner surface of the top, the straight body, and the bottom of the crucible and having flow rate variable nozzles at a plurality of positions to be cooled is placed inside the crucible immediately after arc melting. By inserting and arranging, at each position of the crucible, the flow rate of the cooling gas from the variable flow rate nozzle is individually adjusted, and cooling is performed while controlling the cooling rate, so that the density is high at the bottom with respect to the top and the straight body. A quartz glass crucible can be obtained.

  The control of the cooling rate further comprises providing cooling holes at necessary portions of the mold and, if necessary, changing the density of cooling holes at each position of the crucible (the number of holes per unit area of the mold surface). By controlling the amount of cooling gas blown, or by providing a heating heater on the straight body of the crucible to alleviate supercooling, high-density Can be obtained.

In addition, a conventional quartz glass crucible manufactured by a conventional rotary arc melting method or the like is once heated to a temperature range from a temperature at which a virtual temperature changes (a temperature at which a glass structure changes) to a temperature range equal to or lower than a melting temperature. Quenching is performed, and a high-density vitreous silica crucible can be obtained at the bottom with respect to the top and the straight body by performing an annealing process for controlling the cooling rate to be lower above the straight body.
The melting temperature of quartz powder in the conventional rotary arc melting method is 1700 ° C. or higher, and the fictive temperature of the glass of a normal quartz glass crucible produced thereby is in the range of about 1000 ° C. to 1500 ° C., so that the maximum temperature is 1000 ° C. The fictive temperature can be controlled by the annealing process at about 1500C to about 1500C.

In this case, for example, a quartz glass crucible is heated to a maximum temperature of 1200 ° C. using an electric furnace shown in FIG. 4, and then an annealing process for controlling a cooling temperature is performed, so that the density at the crucible bottom is high. A quartz glass crucible with a low density at the upper part of the straight body can be manufactured.
That is, in the electric furnace, the quartz glass crucible was placed on the mounting table so that only the lowermost portion of the bottom was supported, and heated at a predetermined temperature by heaters placed on the crucible top and side portions. After that, the cooling gas spraying cooling pipe having the tip nozzle for cooling the inner surface of the crucible, and the cooling gas spraying cooling pipe having the tip nozzle for cooling the outer surface of the crucible are synchronized, and from the bottom of the crucible to the straight body part to the top in order. By moving while cooling and blowing the cooling gas, it is possible to obtain a quartz glass crucible having a high density at the bottom of the crucible and a relatively low density at the straight body portion and the upper portion of the crucible.

Further, by heating the quartz glass crucible to a maximum temperature of 1200 ° C. using the electric furnace shown in FIG. 5, and then performing an annealing process for controlling the cooling temperature, the density at the bottom of the crucible is high, and A quartz glass crucible with a low density at the top can be manufactured.
That is, in the electric furnace, the quartz glass crucible is placed on the mounting table so that only the lowermost portion of the bottom is supported, and after being heated at a predetermined temperature by the heaters placed on the crucible top and side portions, The cooling gas spray cooling pipe having the tip nozzle for cooling the inner surface of the crucible and the cooling gas spray cooling pipe having the tip nozzle for cooling the outer surface of the crucible are synchronized, and the crucible is cooled sequentially from the bottom to the straight body and to the top. By blowing the gas, it is possible to obtain a quartz glass crucible having a high density at the crucible bottom and a relatively low density at the crucible straight body portion and the upper portion.

  The cooling pipe can be inserted into the crucible immediately after the arc melting by using a robot or the like.As a cooling method of the quartz glass crucible, the entire cooling pipe is sequentially arranged from the bottom to the straight body, then to the top. After performing cooling while moving or inserting it into the crucible, the maximum flow rate of the cooling medium in each cooling pipe is sequentially increased from the cooling pipe at the bottom to the straight body part, By changing to a cooling pipe, cooling control can also be performed.

<Method of adjusting the interlayer density difference at the boundary between quartz glass crucibles composed of multiple layers>
Quartz glass crucibles for pulling single crystals are usually composed of multiple layers of natural quartz glass and synthetic quartz glass, but at the boundary, even if the virtual temperature of each glass layer is the same, Since the density corresponding to the fictive temperature is different in the glass described above, there is a problem that the difference in the density causes abnormal expansion and the glass layer is separated.
Here, a method will be described in which the virtual temperature of each glass layer is adjusted to minimize the density difference between the respective glass layers to solve the problems such as separation.

FIG. 1 shows the relationship between the virtual temperature (horizontal axis) and the density (vertical axis) for each of natural quartz glass and synthetic quartz glass.
Regarding the relationship between the fictive temperature and the density of natural quartz glass and synthetic quartz glass, the temperature range from 1000 ° C. to 1400 ° C. to 1500 ° C., which is the fictive temperature range below the melting temperature of quartz glass and which can be adjusted. Although each quartz glass increases in density in response to the increase in virtual temperature, the density at the same virtual temperature is always higher for natural silica glass and lower for synthetic silica glass. By raising the virtual temperature of the natural quartz glass and lowering the virtual temperature of the natural quartz glass, it was found that these density differences can be reduced.
Then, in order to make the densities of the natural quartz glass and the synthetic quartz glass uniform, for example, by setting the virtual temperature of the synthetic quartz glass to 1450 ° C. and the virtual temperature of the natural quartz glass to 1200 ° C., The density value is about 2.2030 g / cm ³ , the difference in density can be almost 0, and a quartz glass crucible with excellent peeling resistance can be obtained.

By using such a method, even in a quartz glass crucible having a multilayer structure including a natural quartz glass layer and a synthetic quartz glass layer, the virtual temperature of each layer is adjusted to minimize the density difference between both adjacent layers. By doing so, a quartz glass crucible excellent in peel resistance can be manufactured.
Furthermore, in a quartz glass crucible composed of multiple quartz glass layers, by combining the above-described annealing treatments, the density of the bottom portion is increased with respect to the upper portion, the density difference between the layers is minimized, the exfoliation resistance is excellent, and the inward collapse occurs. And a quartz glass crucible that does not cause deformation can be manufactured.

  Hereinafter, after explaining 1st Embodiment-4th Embodiment, those Examples, Examples 1-6 and Examples 11-15, Comparative Examples 1-3, and The description will be made in comparison with Comparative Examples 11 to 13.

<First embodiment>
The quartz glass crucible according to the first embodiment has a cylindrical straight body and a bottom, and is composed of a single layer of a natural quartz glass layer or a synthetic quartz glass layer. Is a quartz glass crucible for pulling a silicon single crystal, which can be used by being supported by a carbon susceptor as needed. (Hereinafter, the quartz glass crucibles according to the second to fourth embodiments are also used by being supported by a carbon susceptor, if necessary.)

  This quartz glass crucible is manufactured by, for example, a rotating arc melting method.Specifically, natural quartz powder or synthetic quartz powder is supplied as a raw material to the inner surface of a rotating crucible-producing carbon mold, and a predetermined Deposit to the thickness, then perform arc discharge from the inside of the mold, heat and melt the entire inner surface of the quartz powder, start quenching from the bottom of the crucible, and thereafter, sequentially up to the top of the straight body By performing the cooling, a virtual temperature gradient is provided such that the virtual temperature is high at the bottom and the virtual temperature is low at the top of the straight body, and the density is high at the bottom, while the virtual temperature is high at the top of the straight body. And a quartz glass crucible having a relatively low density.

As a mold for manufacturing a quartz glass crucible, a water-cooled stainless steel mold or the like can be used other than the carbon mold.
Regarding the method of cooling the quartz glass crucible, a method of starting quenching from the bottom of the crucible and cooling sequentially from the bottom of the crucible to the upper part of the crucible straight body, for example, after arc cutting, cooling gas that has cooled nitrogen gas and the like is vertically Introduced into the quartz glass crucible by a movable cooling tube moving in the direction, it can be achieved by sequentially moving the cooling tube from the crucible bottom inside the crucible to the top of the crucible straight body, and from the bottom to the top of the straight body The desired virtual temperature gradient can be obtained up to this point.

Also, a large number of cooling holes for cooling the quartz glass crucible from the outside are provided in the mold for manufacturing the quartz glass crucible. At each cooling position from the bottom of the crucible to the top of the crucible straight body, the crucible bottom is strongly cooled. Slow cooling in order toward the upper part of the part, or about the cooling start time after the end of the arc, immediately start cooling at the bottom of the crucible, and thereafter, after maintaining the temperature for a certain period of time until reaching the upper part of the body of the crucible, sequentially By starting cooling or the like, a desired virtual temperature gradient can be obtained from the bottom to above the straight body even outside the crucible.
It can be manufactured by a crucible manufacturing apparatus by the rotating arc melting method shown in FIG. 2 or FIG.

  As described above, in the present invention, a conventional new quartz glass crucible without a virtual temperature gradient or a density gradient particularly in the vertical direction of a quartz glass crucible in a conventional rotary arc melting method or the like, or a single crystal already formed by a CZ method or the like. It can also be manufactured from the quartz glass crucible used for growing, for example, after heating those quartz glass crucibles once to a temperature range equal to or higher than the virtual temperature and equal to or lower than the melting temperature, according to the first embodiment described above. By applying the cooling method, a fictitious temperature gradient is formed, and a quartz glass crucible with a high density at the bottom of the crucible and a low density at the top of the crucible body can be obtained. This can be prevented.

It can be manufactured by annealing in an electric furnace shown in FIG. 4 or FIG.
For the fictive temperature, for a quartz crucible manufactured under the same conditions, for example, a specimen is sampled from the middle position in the thickness direction of each layer, and confirmed by measuring using laser Raman spectroscopy. (See Patent Literature 7, Patent Literature 8, Non-Patent Literature 1).

  The density at each position of the quartz glass crucible can also be directly measured by the Archimedes method or the like. It is also possible to measure an accurate difference in density by directly measuring. In that case, the quartz glass crucible made of glass having a desired density can be manufactured at each position by feeding back the result of measuring the density of the sample cut out from each position by the Archimedes method to the manufacturing conditions of the quartz glass crucible. it can. In addition, if air bubbles are present in the sample, the density of the glass itself cannot be measured. Therefore, it is necessary to extract the sample from a portion where no air bubbles exist.

<Second embodiment>
The quartz glass crucible according to the second embodiment, similar to the quartz glass crucible according to the first embodiment, can solve problems such as inward fall of the straight body of the crucible, and can be used for pulling a silicon single crystal. It is a quartz glass crucible having a cylindrical straight body and a bottom, and composed of a plurality of layers including a two-layer structure or a three-layer structure.
Specifically, for example, a quartz glass crucible having a natural quartz glass layer made of natural quartz glass as an outer layer and a synthetic quartz glass layer made of synthetic quartz glass as an inner layer, or a natural quartz glass layer formed of an outer layer An intermediate layer includes a quartz glass crucible having a multilayer structure having a natural quartz glass layer or a synthetic quartz glass layer as an intermediate layer and a synthetic quartz glass layer as an inner layer.

  This quartz glass crucible is manufactured by, for example, a rotating arc melting method as in the first embodiment. Specifically, natural quartz powder is used as a raw material on the inner surface of a rotating crucible-producing carbon mold. And the synthetic quartz powder is supplied sequentially from the quartz powder for the outer layer, and while accumulating to a predetermined thickness, an arc discharge is performed from the inside of the mold, and the entire inner surface of the quartz powder is heated and melted, and then from the bottom of the crucible. By starting quenching and subsequently cooling down to the upper part of the straight body part, a virtual temperature gradient is provided, where the virtual temperature is high at the bottom and the virtual temperature is low at the top of the straight body. A quartz glass crucible having a high density at the bottom and a relatively low density at the top of the straight body is obtained.

In the second embodiment, since the quartz glass crucible has a plurality of layers, for the outer layer, for example, the cooling method from the outside shown in the first embodiment is also performed. The outer layer also has a high density at the bottom and a relatively low density at the upper part of the straight body, thereby making it possible to manufacture an excellent quartz glass crucible that does not easily fall down.
Similarly to the first embodiment, the crucible can be manufactured by using the crucible manufacturing apparatus shown in FIG. 2 or FIG. 3 by the rotating arc melting method.

Further, similarly to the first embodiment, the quartz glass crucible according to the present invention is a new quartz glass crucible having no virtual temperature gradient or density gradient particularly in the vertical direction of the quartz glass crucible, or a quartz glass crucible already formed by the CZ method or the like. It can also be manufactured from the quartz glass crucible used for growing the single crystal, and after those quartz glass crucibles are once heated to a temperature range equal to or higher than the virtual temperature and equal to or lower than the melting temperature, according to the first embodiment described above. By applying the cooling method, a fictitious temperature gradient is formed, and a quartz glass crucible with a high density at the bottom of the crucible and a low density at the top of the crucible body can be obtained. This can be prevented.
In this case, it can be manufactured by performing an annealing process using an electric furnace as shown in FIG. 4 or FIG.
Note that the measurement position and the confirmation method of the virtual temperature are the same as in the first embodiment.

<Third embodiment>
The quartz glass crucible according to the third embodiment is a quartz glass crucible having a cylindrical straight body portion and a bottom portion and having a plurality of layers including a two-layer structure or a three-layer structure. This is a quartz glass crucible for pulling a silicon single crystal, which can avoid the problem of peeling caused by a difference in the density of each layer at the boundary portion.
Specifically, for example, a quartz glass crucible having a natural quartz glass layer made of natural quartz glass as a raw material as an outer layer and in contact with the outer layer, a synthetic quartz glass layer made of synthetic quartz glass as a raw material as an intermediate layer or an inner layer. A multilayer quartz glass crucible having a natural quartz glass layer as an intermediate layer and a synthetic quartz glass layer in contact with the intermediate layer as a second intermediate layer or an inner layer.

And, as already shown as a matter to be found, in order to prevent the separation between the natural quartz glass layer and the synthetic quartz glass layer, the density between the quartz glass layers should be reduced so that the density difference between the quartz glass layers at the boundary part disappears. By adjusting the difference, the problem can be solved by reducing the fictive temperature by lowering the density at the boundary of natural quartz glass, which is relatively dense relative to synthetic quartz glass, at the same fictive temperature. On the other hand, the synthetic quartz glass can be adjusted higher by increasing the fictive temperature to reduce the density difference. For example, the density difference is set to 0.0014 g / cm ³ or less. Thereby, it is possible to manufacture an excellent quartz glass crucible capable of avoiding occurrence of defects such as peeling and cracking at the boundary.

  In general, a quartz glass crucible having a plurality of layers is generally provided with a natural quartz glass layer on the outer layer side and a synthetic quartz glass layer on the inner layer side. For example, the first embodiment and the second embodiment Using the cooling mechanism from the inside of the mold and the cooling mechanism from the outside of the mold shown in the embodiment, the inside part having the synthetic quartz glass layer is quenched to increase the fictive temperature and increase the density, while the natural quartz glass layer is removed. By slow cooling the outer portion of the layer, lowering the fictive temperature, and lowering the density, the density difference at the boundary between these two adjacent layers can be reduced, and separation at the boundary can be prevented.

Similar to the first and second embodiments, it can be manufactured using a crucible manufacturing apparatus by a rotating arc melting method shown in FIG. 2 or FIG.
In the case where a synthetic quartz glass layer is provided on the outer layer side and a natural quartz glass layer is provided on the inner layer side, the inner layer is gradually cooled and the outer layer is rapidly cooled to reduce the density difference at the boundary. In addition, separation at the boundary can be prevented.

In addition, the quartz glass crucible according to the present invention has been used for growing single crystals by a normal new quartz glass crucible having no virtual temperature gradient or density gradient, particularly in the vertical direction of the quartz glass crucible, or by the CZ method or the like. It can also be manufactured from quartz glass crucibles, and after heating these quartz glass crucibles once to a temperature range equal to or higher than the virtual temperature and equal to or lower than the melting temperature, as described above, so that the density difference of each quartz glass layer at the boundary is eliminated. By adjusting the virtual temperature at the boundary between the respective quartz glass layers, separation at the boundary can be prevented.
In this case, similarly to the second embodiment, it can be manufactured using the electric furnace shown in FIG. 4 or FIG.

The measurement of the fictive temperature can be confirmed by taking a test piece from the position of the boundary in the thickness direction of each layer with respect to the quartz crucible manufactured under the same conditions and performing measurement using laser Raman spectroscopy. .
Further, the density of each layer of the quartz glass crucible can be directly measured by an Archimedes method or the like. It is also possible to measure an accurate difference in density by directly measuring. In that case, a quartz glass crucible made of glass of a desired density can be manufactured in each layer by feeding back the result of measuring the density of the sample cut out from each layer by the Archimedes method to the manufacturing conditions of the quartz glass crucible. . In addition, if air bubbles are present in the sample, the density of the glass itself cannot be measured. Therefore, it is necessary to extract the sample from a portion where no air bubbles exist.

<Fourth embodiment>
The quartz glass crucible according to the fourth embodiment has a problem of deformation such as inward collapse occurring in a straight body portion of the quartz glass crucible which has been a problem to be solved in the second embodiment and a problem to be solved in the third embodiment. This is a quartz glass crucible for pulling a silicon single crystal, which can simultaneously solve the problem of delamination occurring in a quartz glass crucible having a plurality of layers made of quartz glass of different materials.
Specifically, for example, a natural quartz glass layer made of natural quartz glass as a raw material shown in the second and third embodiments is used as an outer layer, and a synthetic quartz glass is used as a raw material in contact with the outer layer. A quartz glass crucible having a synthetic quartz glass layer as an intermediate layer or an inner layer, or a multilayer structure having a natural quartz glass layer as an intermediate layer and a synthetic quartz glass layer as a second intermediate layer or an inner layer in contact with the intermediate layer It includes a quartz glass crucible.

  This quartz glass crucible is manufactured by, for example, a rotating arc melting method similarly to the second and third embodiments. Specifically, the raw material is placed on the inner surface of a rotating carbon mold for manufacturing a crucible. As natural quartz powder and synthetic quartz powder are sequentially supplied from the outer layer quartz powder to the inner layer quartz powder, and deposited to a predetermined thickness, arc discharge is performed from the inside of the mold, and the quartz powder is heated and melted. After that, by controlling the temperature of each layer from the inner layer side and the outer layer side and adjusting the virtual temperature at each part of each layer, the density of each layer of the quartz glass crucible is high at the bottom and at the top of the straight body part In addition, a quartz glass crucible having a low density and a small difference in density at each part from the top to the bottom of the straight body at the boundary between the layers is obtained.

After heating and melting the raw material quartz powder deposited in the mold, as described above, the rapid cooling was started from the bottom of the crucible on either or both the inner and outer layers of the crucible. By sequentially cooling toward the upper portion of the straight body, or performing cooling by providing a cooling gradient having a higher cooling capacity toward the lower portion of the crucible from the bottom of the crucible toward the upper portion of the straight body, cooling is performed at the bottom of the quartz glass crucible. In addition to raising the temperature and increasing the density, at the top of the straight body, the fictive temperature is lowered relatively to the bottom to lower the density, suppressing the inside of the straight body and the occurrence of thermal deformation, and At the boundary between the natural silica glass layer on the outer layer side and the synthetic silica glass layer on the inner layer side that are in direct contact with each other, the mold inside shown in the first and second embodiments is used. By using such a cooling mechanism or a cooling mechanism from the outside of the mold, by rapidly cooling the inner portion having the synthetic quartz glass layer, the fictive temperature is raised, and the synthetic quartz glass layer is relatively densified, The outer part having the natural quartz glass layer is cooled slowly or kept for a certain period of time to lower the fictive temperature, and the natural quartz glass layer is made relatively low in density, so that the density at the boundary between these two adjacent layers is reduced. By reducing the difference, preferably by setting the density difference to 0.0014 g / cm ³ or less, it is possible to avoid occurrence of defects such as peeling and cracking at the boundary.

Similar to the first and second embodiments, it can be manufactured using a crucible manufacturing apparatus by a rotating arc melting method shown in FIG. 2 or FIG.
In the case where a synthetic quartz glass layer is provided on the outer layer side and a natural quartz glass layer is provided on the inner layer side adjacent thereto, the cooling capacity of the outer layer is increased with respect to the inner layer so that the boundary between the two layers is improved. It is possible to reduce the density difference at the portion and prevent the occurrence of defects such as peeling and cracking at the boundary.

In addition, the quartz glass crucible according to the present invention has been used for growing single crystals by a normal new quartz glass crucible having no virtual temperature gradient or density gradient, particularly in the vertical direction of the quartz glass crucible, or by the CZ method or the like. It can also be manufactured from quartz glass crucibles, and after heating these quartz glass crucibles once to a temperature range equal to or higher than the virtual temperature and equal to or lower than the melting temperature, as described above, so that the density difference of each quartz glass layer at the boundary is eliminated. The virtual temperature at the boundary between the quartz glass layers is adjusted, and in each quartz glass layer, the virtual temperature is high at the bottom of the quartz glass crucible and low at the top of the straight body. The temperature is adjusted so that the quartz glass crucible has a high density at the bottom and a relatively low density at the top of the straight body. It allows suppressing the occurrence of tilting and thermal deformation of the inner cylindrical body portion, also can be combined, to prevent peeling at the boundary.
Similarly to the second embodiment, it can be manufactured using the electric furnace shown in FIG. 4 or FIG.

The measurement of the fictive temperature can be confirmed by taking a test piece from the position of the boundary in the thickness direction of each layer with respect to the quartz crucible manufactured under the same conditions and performing measurement using laser Raman spectroscopy. .
Further, the density of each layer of the quartz glass crucible can be directly measured by an Archimedes method or the like. It is also possible to measure an accurate difference in density by directly measuring. In that case, a quartz glass crucible made of glass of a desired density can be manufactured in each layer by feeding back the result of measuring the density of the sample cut out from each layer by the Archimedes method to the manufacturing conditions of the quartz glass crucible. . In addition, if air bubbles are present in the sample, the density of the glass itself cannot be measured. Therefore, it is necessary to extract the sample from a portion where no air bubbles exist.

Hereinafter, the present invention will be described by showing examples in comparison with comparative examples.
Note that the present invention is not limited to these examples.

In the embodiment, a quartz glass crucible according to the present invention having a diameter of 32 inches (diameter of 800 mm) and a height of 500 mm is directly manufactured using a rotating arc melting method, or a quartz glass crucible having the same shape is formed by a normal rotating arc. After being manufactured once by a melting method, it was manufactured by performing an annealing treatment.
Table 1 shows Examples 1 to 6, Table 2 shows Comparative Examples 1 to 3, Table 3 shows Examples 11 to 15, and Table 4 shows Comparative Examples 11 to 13.

Examples 1 to 4 are quartz glass crucibles according to the first embodiment, each of which is composed of a single quartz glass layer, and solves problems such as falling down of the crucible. Here, the single quartz glass layer of Example 1 and Example 2 is a natural quartz glass layer, and the single quartz glass layer of Example 3 and Example 4 is a synthetic quartz glass layer. A glass crucible has a bubble layer and a transparent layer.
In Example 1 and Example 3, when manufacturing the quartz glass crucible using the rotating arc melting method, the virtual temperature of the quartz glass layer was adjusted so that the density at the top of the straight body was low and the density at the bottom was high. A quartz glass crucible is directly manufactured.
The adjustment of the fictive temperature of the quartz glass layer was performed using a manufacturing apparatus based on the rotating arc melting method shown in FIG. Immediately after the arc melting, a cooling tube was inserted inside the crucible and moved from the bottom to the top while blowing a cooling gas (air) at a rate of 10 L / sec.

In Examples 2 and 4, a normal quartz glass crucible manufactured by the rotating arc melting method was reheated to a virtual temperature or higher and a melting temperature or lower, and then the virtual temperature of the quartz glass layer was adjusted by annealing. The purpose of the present invention is to produce a quartz glass crucible having a low density at the top of the straight body and a high density at the bottom.
The adjustment of the virtual temperature of the quartz glass layer was performed using the annealing apparatus shown in FIG. During cooling of the annealing treatment, a cooling tube was inserted inside the crucible, and moved from the bottom to the top while blowing a cooling gas (air) at a rate of 10 L / sec.
And, as shown in Table 1, the quartz glass crucibles obtained by these manufacturing methods did not cause inward collapse or thermal deformation when pulling up the single crystal, and the quality of the manufactured single crystal was good. .
On the other hand, in the quartz glass crucibles of Comparative Examples 1 and 2 obtained by the conventional rotary arc melting method, since the virtual temperature was not adjusted (the cooling pipe was not inserted) at the time of production, the single crystal was not used. An inward fall was observed during lifting.

Examples 5 and 6 solve problems such as the crucible falling down in the quartz glass crucible according to the second embodiment, which is composed of a plurality of quartz glass layers.
In the fifth embodiment, when a quartz glass crucible composed of a plurality of quartz glass layers is manufactured, similarly to the first and third embodiments, a quartz glass The fictitious temperature is adjusted to directly produce a quartz glass crucible having a low density at the top of the straight body and a high density at the bottom.
The adjustment of the fictive temperature of the quartz glass layer was performed using a manufacturing apparatus based on the rotating arc melting method shown in FIG. Immediately after the arc melting, a cooling tube is inserted inside the crucible and moved from the bottom to the top while blowing a cooling gas (air) at a rate of 10 L / sec. Cooling was performed while blowing a cooling gas (air) inward at a speed of 1 L / sec, at a speed of 1 L / sec at the corner portion, and at a speed of 10 L / sec at the straight body portion.

In Example 6, as in Examples 2 and 4, a normal quartz glass crucible was once manufactured by the rotating arc melting method, and then reheated to a temperature equal to or higher than the fictive temperature and lower than the melting temperature. The fictitious temperature of the layer is adjusted to produce a quartz glass crucible having a low density at the top of the straight body and a high density at the bottom.
The adjustment of the virtual temperature of the quartz glass layer was performed using the annealing apparatus shown in FIG. At the time of cooling in the annealing process, a cooling pipe is inserted inside the crucible, and a cooling gas (air) is moved from the bottom to the top while blowing a cooling gas (air) at a rate of 10 L / sec. The cooling was carried out while moving from the bottom to the top while blowing a cooling gas (air) to the outside of the crucible at a speed of / sec.
And, as shown in Table 1, the quartz glass crucibles obtained by these manufacturing methods did not cause inward collapse or thermal deformation when pulling up the single crystal, and the quality of the manufactured single crystal was good. .
On the other hand, in the quartz glass crucible of Comparative Example 3 obtained by the conventional rotary arc melting method, the virtual temperature was not adjusted at the time of manufacturing (the cooling pipe was not inserted), so that the crucible with respect to the bottom of the crucible was not used. The density of the upper portion was high, and inversion was observed when the single crystal was pulled.

The eleventh embodiment solves the problem of peeling caused by the difference in the density of each layer at the boundary between layers made of quartz glass having different characteristics in the quartz glass crucible having a plurality of layers according to the third embodiment.
In Example 11, when manufacturing a quartz glass crucible composed of a plurality of quartz glass layers having different characteristics, when manufacturing a quartz glass crucible using a rotating arc melting method, the density difference at the boundary between the plurality of layers is small. Direct production is performed by adjusting the fictive temperature of each quartz glass layer so that the density difference is, for example, 0.0014 g / cm ³ or less.

The adjustment of the fictive temperature of the quartz glass layer was performed using a manufacturing apparatus based on the rotating arc melting method shown in FIG. Immediately after the arc melting, a cooling tube is inserted inside the crucible and moved from the bottom to the top while blowing a cooling gas (air) at a rate of 10 L / sec. Cooling was performed while blowing a cooling gas (air) inward at a speed of 1 L / sec, at a speed of 1 L / sec at the corner portion, and at a speed of 10 L / sec at the straight body portion.
In the quartz glass crucible manufactured by such a method, as shown in Table 2, it was possible to avoid the occurrence of defects such as peeling and cracking at the boundary between quartz glass layers having different characteristics. .
On the other hand, the quartz glass crucibles of Comparative Examples 11 to 13 obtained by the conventional rotary arc melting method have different characteristics because the virtual temperature is not adjusted (the cooling pipe is not inserted) at the time of production. A density difference exceeding 0.0014 g / cm ³ occurred at the boundary between the quartz glass layers, and peeling was observed at the boundary between these layers.

In Examples 12 to 15, in the quartz glass crucible having a plurality of layers according to the fourth embodiment, a quartz glass crucible having different characteristics and a problem of deformation such as inward collapse which may occur in a straight body portion of the quartz glass crucible is used. An object of the present invention is to simultaneously solve the problem of peeling caused by the difference in the density of each layer at the boundary between the layers.
Then, in Examples 12 and 14, when producing a quartz glass crucible composed of a plurality of quartz glass layers having different characteristics, when producing a quartz glass crucible using a rotating arc melting method, in each quartz glass layer, Adjusting the fictive temperature, lowering the density at the top of the straight body and increasing the density at the bottom, and at the same time, adjusting the density difference between the respective quartz glass layers at the boundary between these quartz glass layers to be small By doing so, it is possible to prevent the straight body part from falling into the crucible inside and the occurrence of thermal deformation, and to avoid the occurrence of defects such as peeling and cracking at the boundary between these quartz glass layers. is there.
The adjustment of the fictive temperature of the quartz glass layer was performed using a manufacturing apparatus based on the rotating arc melting method shown in FIG. Immediately after the arc melting, a cooling tube is inserted inside the crucible and moved from the bottom to the top while blowing a cooling gas (air) at a rate of 10 L / sec. Cooling was performed while blowing a cooling gas (air) inward at a speed of 2 L / sec, at a speed of 1 L / sec at the corner portion, and at a speed of 5 L / sec at the straight body portion.

Further, in Examples 13 and 15, for a normal quartz glass crucible manufactured by the rotating arc melting method, after reheating to a virtual temperature or higher and a melting temperature or lower, the virtual temperature of the quartz glass layer was adjusted by annealing treatment, By increasing the density at the top of the straight body and increasing the density at the bottom, and at the same time, at the boundary between these quartz glass layers, adjustment is made so that the difference in density between the respective quartz glass layers is reduced. An object of the present invention is to prevent the body from falling into the crucible and the occurrence of thermal deformation, and also to avoid the occurrence of defects such as peeling and cracking at the boundary between these quartz glass layers.
The adjustment of the virtual temperature of the quartz glass layer was performed using the annealing apparatus shown in FIG. At the time of cooling in the annealing process, a cooling pipe is inserted inside the crucible, and a cooling gas (air) is moved from the bottom to the top while blowing a cooling gas (air) at a rate of 10 L / sec. The cooling was carried out while moving from the bottom to the top while blowing a cooling gas (air) to the outside of the crucible at a speed of / sec.

And, as shown in Table 2, the quartz glass crucible obtained by such a manufacturing method does not cause inward collapse or thermal deformation when the single crystal is pulled, and the quality of the manufactured single crystal is good. In addition, no separation occurred between a plurality of different quartz glass layers.
On the other hand, in the quartz glass crucibles of Comparative Examples 11 to 13 obtained by the conventional rotating arc melting method, since the virtual temperature was not adjusted at the time of manufacturing (the cooling pipe was not inserted), the inner fall was caused. At the same time, a density difference exceeding 0.0014 g / cm ³ occurred at the boundary between the quartz glass layers having different characteristics, and peeling was observed.

  As described above, the present invention relates to a quartz glass crucible, in particular, to a quartz glass crucible for pulling a silicon single crystal. The present invention provides a quartz glass crucible and a method for producing the same, which suppresses deformation such as inward collapse occurring in the above and occurrence of separation at a boundary portion between an outer layer made of natural quartz glass and an inner layer made of synthetic quartz glass. Therefore, it is very useful in the field of manufacturing various quartz glass crucibles including for pulling a silicon single crystal.

DESCRIPTION OF SYMBOLS 1 Mold 2 Arc electrode 3 Cooling pipe 4 Adjustment valve 5 Mold rotation mechanism 6 Mold cooling hole 7 Nozzle rotation mechanism 8 Crucible 9 Electric furnace 10 Heater 11

Claims (12)

In a quartz glass crucible for pulling a silicon single crystal having a straight body and a bottom,
A quartz glass crucible for pulling a silicon single crystal, characterized in that the density is low at the top of the straight body part and high at the bottom.   The quartz glass crucible for pulling a silicon single crystal according to claim 1, wherein the crucible is made of a natural quartz glass layer or a synthetic quartz glass layer.   2. The quartz glass crucible for pulling a silicon single crystal according to claim 1, wherein the quartz glass crucible has a natural quartz glass layer as an outer layer and a synthetic quartz glass layer as an inner layer.   4. The silicon single crystal pulling device according to claim 1, wherein the outer layer has a natural quartz glass layer, the intermediate layer has a natural quartz glass layer or a synthetic quartz glass layer, and the inner layer has a synthetic quartz glass layer. For quartz glass crucible. In a quartz glass crucible for pulling a silicon single crystal having a straight body and a bottom,
Silicon having a natural quartz glass as an outer layer, a synthetic quartz glass layer as an inner layer, and a boundary portion where the outer layer and the inner layer are in contact with each other, wherein a density difference between the respective layers is 0.0014 g / cm ³ or less. Quartz glass crucible for single crystal pulling. In a quartz glass crucible for pulling a silicon single crystal having a straight body and a bottom,
It has a natural quartz glass layer as an outer layer, has a natural quartz glass layer or a synthetic quartz glass layer as an intermediate layer, has a synthetic quartz glass layer as an inner layer, and at a boundary where layers made of different types of quartz glass are in direct contact. A quartz glass crucible for pulling a silicon single crystal, wherein a density difference at a boundary portion of each layer is 0.0014 g / cm ³ or less. In a quartz glass crucible for pulling a silicon single crystal having a straight body and a bottom,
The quartz glass crucible for pulling a silicon single crystal according to claim 5, wherein the density is low at an upper portion of the straight body portion and high at a bottom portion.   A method for producing a quartz glass crucible for pulling a silicon single crystal, comprising feeding a raw quartz powder into a rotating quartz glass crucible mold, depositing the raw quartz powder to a predetermined thickness, and then depositing the quartz powder from the inside of the mold. After the entire inner surface of the raw material quartz powder was melted by an arc, quenching was started from the bottom of the quartz crucible, and then cooling was performed sequentially up to the top of the straight body. By providing a temperature gradient of the virtual temperature so that the virtual temperature gradually decreases toward the upper part of the body, the density is high at the bottom, and the density is sequentially reduced from the lower part of the straight body toward the upper part. Of manufacturing a quartz glass crucible for pulling a silicon single crystal.   9. The method for manufacturing a quartz glass crucible for pulling up a silicon single crystal according to claim 8, wherein the means for starting quenching from the bottom of the quartz crucible and then sequentially cooling down to above the straight body portion comprises an arc melting process. After that, a cooling gas that has cooled nitrogen gas or the like is introduced into the quartz glass crucible by a movable cooling tube that moves vertically, and the cooling tube is sequentially moved from the crucible bottom inside the crucible to the top of the crucible straight body. A method for producing a quartz glass crucible for pulling a silicon single crystal.   In the method for manufacturing a quartz glass crucible for pulling a silicon single crystal according to claim 8 or claim 9, the means for starting quenching from the bottom of the quartz crucible, and then sequentially cooling down to above the straight body portion, A number of cooling holes for cooling the quartz glass crucible from the outside are provided in the mold for manufacturing the quartz glass crucible, and at each cooling position from the bottom of the crucible to the top of the crucible straight body, the crucible bottom is strongly cooled, and the crucible straight body is provided. Slow cooling gradually upwards, or about the cooling start time after the end of the arc, immediately start cooling at the bottom of the crucible, then keep the temperature for a certain period of time until it reaches above the crucible straight body, then cool down sequentially A method for producing a quartz glass crucible for pulling a silicon single crystal. A method for producing a quartz glass crucible for pulling a silicon single crystal, comprising the steps of forming an outer layer and an inner layer, or an outer layer, an intermediate layer, and an inner layer in a rotating quartz glass crucible forming mold in the order of these layers. The raw material quartz powder is supplied and deposited to a predetermined thickness, and then the entire inner surface of the deposited raw material quartz powder is arc-melted from the inside of the molding die. In the part, in order to reduce the density difference between the two quartz glass layers, at the same virtual temperature, for a layer having a natural silica glass having a high density relative to the synthetic quartz glass, the virtual temperature is lowered by lowering the virtual temperature. The density is adjusted to be low, while for the layer having synthetic quartz glass, the density at the boundary is adjusted to be high by increasing the virtual temperature, One of wherein the density difference was 0.0014 g / cm ³ or less layers, a method of manufacturing a silicon single crystal quartz glass crucible for pulling. A method for producing a quartz glass crucible for pulling a silicon single crystal, comprising the steps of forming an outer layer and an inner layer, or an outer layer, an intermediate layer, and an inner layer in a rotating quartz glass crucible forming mold in the order of these layers. The raw material quartz powder is supplied, deposited to a predetermined thickness, and then the entire inner surface of the deposited material quartz powder is arc-melted from the inside of the molding die, and then quenched from the bottom of the quartz crucible, Thereafter, cooling is performed sequentially up to the upper portion of the straight body portion, and cooling is performed so as to provide a temperature gradient of a virtual temperature such that the virtual temperature is higher at the bottom portion and gradually lower from the bottom toward the upper portion of the straight body portion. By performing an arc heat treatment in which the density is high at the bottom and sequentially decreasing the density from the lower part of the straight body part toward the upper part, simultaneously with the arc heat treatment, simultaneously, the different types of quartz glass are used. At the boundary where the two are in contact, to reduce the density difference between the two quartz glass layers, the layer with natural silica glass, which is relatively dense relative to synthetic quartz glass at the same virtual temperature, is reduced by lowering the virtual temperature. The density at the boundary is adjusted to be low, and for the layer having synthetic quartz glass, the virtual temperature is increased to increase the density at the boundary, and the density difference between the two layers at the boundary is set to 0.1. A method for producing a quartz glass crucible for pulling a silicon single crystal, wherein the crucible is 0014 g / cm ³ or less.

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