JP2018104248A - Quartz glass crucible for pulling silicon single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quartz glass crucible for pulling a silicon single crystal, capable of further promoting the crystallization of a quartz layer by adding a specific additive to the quartz layer (the outer layer) of a specific part to suppress the deformation of the crucible and suppress the contamination of the single crystal silicon caused by the additive.SOLUTION: In a quartz glass crucible 1 for pulling silicon single crystal, consisting of a transparent inner layer 2 consisting of a synthetic quartz layer without substantially including air bubbles, an opaque intermediate layer 3 including air bubbles and consisting of a natural quartz layer or a synthetic quartz layer and an opaque outer layer 4 including air bubbles and consisting of a natural quartz layer or a synthetic quartz layer, the opaque outer layer 4 is a natural quartz layer or synthetic quartz layer having added Al, Fe or Fe oxide.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a quartz glass crucible for pulling a silicon single crystal for pulling a single crystal by the Czochralski method (hereinafter referred to as “CZ method”).

  The CZ method is widely used for the growth of silicon single crystals. In this method, the seed crystal is brought into contact with the surface of the silicon melt contained in the quartz glass crucible, the crucible is rotated, and the seed crystal is pulled upward while rotating in the opposite direction. A single crystal is formed at the lower end.

By the way, the quartz glass crucible becomes larger year by year. However, the enlargement of the quartz glass crucible has an advantage that the amount of polycrystalline silicon loaded can be increased and the throughput is improved.
However, on the other hand, it must be used in a severe environment such as a longer melting time and a larger output of the heating carbon heater, which has a great adverse effect on the quartz glass crucible.

For example, a conventional quartz glass crucible has a low viscosity value in a high temperature range, and it has been difficult to maintain its shape for a long time in a thermal environment of 1400 ° C. or higher. For this reason, problems have arisen in the single crystal pulling process, such as fluctuations in the melt surface of the molten silicon due to deformation of the quartz glass crucible and reduction in the single crystallization rate.
In order to solve this problem, Patent Documents 1 and 2 propose a quartz glass crucible having a three-layer structure in which an outer layer is an Al-added quartz layer, an intermediate layer is a natural quartz layer, and an inner layer is a high-purity synthetic quartz layer.

  According to the crucibles proposed in Patent Documents 1 and 2, when the outer layer is heated at a constant temperature of 1200 ° C. or higher in the heating and heating process of the silicon single crystal pulling process, it crystallizes into cristobalite. In the cristobalite growth process, the viscosity is improved, and high durability can be obtained by crystallization, so that deformation and breakage of the crucible can be suppressed as described above.

JP 2000-247778 A JP 2008-81374 A

  As described above, the Al-added quartz layer crystallizes in a shorter time than the quartz layer to which Al is not added. However, even in this case, a predetermined time is required for crystallization, and the quartz glass crucible may be deformed before crystallization, and it is necessary to further shorten the time until crystallization. .

In order to shorten the crystallization time, it is conceivable to increase the Al concentration of the Al-added quartz layer or increase the use temperature of the quartz glass crucible.
However, when the Al concentration of the quartz layer is increased, the crystallization of the quartz layer proceeds excessively, and the quartz glass crucible may break during use, and there is a risk of hot water leakage.
On the other hand, since the use temperature of the quartz glass crucible depends on the use conditions of the crucible, limiting the use temperature of the crucible to a high one is not preferable because it limits the range in which the crucible can be used.

In order to solve the above-mentioned problems, the present inventors diligently studied a method for further shortening the crystallization of the quartz layer.
Then, by adding Fe or Fe oxide, which is originally an impurity and is not preferable to be mixed into the quartz layer of the crucible, crystallization proceeds faster than in the case of conventional Al addition alone, and silicon It was discovered that deformation of the crucible at the initial stage of dissolution can be suppressed.
In addition, Fe or an oxide of Fe becomes an impurity when it diffuses into the molten silicon melt in the quartz glass crucible, but by adding Fe or an oxide of Fe to a specific part of the quartz glass crucible, The present invention has been conceived by discovering that it does not diffuse to the inner layer of the glass crucible and does not contaminate the molten silicon melt.

  The present invention has been made under the above circumstances, and by adding a specific additive to a quartz layer (outer layer) at a specific site, the crystallization of the quartz layer is further promoted and the deformation of the crucible is suppressed. Another object of the present invention is to provide a quartz glass crucible for pulling a silicon single crystal in which contamination of the single crystal silicon by the additive is suppressed.

  A quartz glass crucible for pulling a silicon single crystal according to the present invention made to achieve the above object includes a transparent inner layer made of a synthetic quartz layer substantially free of bubbles, and a natural quartz layer or synthetic quartz containing bubbles. In a quartz glass crucible for pulling up a silicon single crystal comprising an opaque intermediate layer comprising layers and an opaque outer layer comprising bubbles, a natural quartz layer or a synthetic quartz layer, the opaque outer layer comprises Al and Fe or Fe oxide , Is a natural quartz layer or a synthetic quartz layer to which is added.

  Thus, since the opaque outer layer is a natural quartz layer or a synthetic quartz layer to which Al and Fe or Fe oxide are added, the opaque outer layer is colored with Fe or Fe oxide. Since this colored portion (Fe or Fe oxide) absorbs heat (temperature increases), the temperature of the colored portion rises, crystallization of the opaque outer layer by Al is further promoted, and the initial stage of silicon dissolution Deformation of the quartz glass crucible is suppressed. This crystallization speed is faster than the case of conventional Al addition alone, and the crystallization of the opaque outer layer proceeds. Therefore, the deformation of the quartz glass crucible at the initial stage of silicon dissolution can be further suppressed as compared with the case of conventional Al addition alone. .

Further, since Fe hardly diffuses in quartz glass, when Fe or Fe oxide is added to an opaque outer layer made of a natural quartz layer or a synthetic quartz layer, it hardly reaches the inner surface of the transparent inner layer made of a synthetic quartz layer.
As a result, the molten silicon melt inside the quartz glass crucible is not contaminated with Fe, and the contamination of Fe as an impurity is suppressed in the pulled single crystal silicon.

Here, the opaque outer layer is divided into an inner layer and an outermost layer, and the inner layer of the opaque outer layer is a natural quartz layer or a synthetic quartz layer to which Al and Fe or Fe oxide are added, It is desirable that the outermost layer of the opaque outer layer is the same natural quartz layer or synthetic quartz layer as the inner layer, to which Al is added and no Fe or Fe oxide is added.
As described above, the outermost layer of the opaque outer layer is made of an Fe-free quartz layer because the Fe added to the outermost layer is scattered during the production of the quartz glass crucible or during the use of the quartz glass crucible. This is to prevent Fe contamination or the molten silicon melt inside the crucible from being contaminated by Fe.

Moreover, it is desirable that the particle size of Fe or Fe oxide to be added is 100 mesh or less, and the addition amount of the Fe or Fe oxide is 0.05% by weight or more and 5% by weight or less.
The particle size of Fe or Fe oxide to be added is 100 mesh or less. When the particle size exceeds 100 mesh, the temperature difference between the region where Fe or Fe oxide particles are present and the region where Fe or Fe oxide particles are not present in the Fe-added quartz layer Becomes larger and crystallization varies, which is not preferable.
That is, it is preferable that Fe or Fe oxide of 100 mesh or less is dispersed microscopically and uniformly in the quartz layer as a region that absorbs heat (temperature increases).
The particle size of Fe or Fe oxide is preferably 200 mesh or more and 100 mesh or less (mesh opening of 75 μm or more and 149 μm or less). When the added Fe or Fe oxide has a particle size of less than 200 mesh, the particle size is smaller than that of the quartz powder.

Furthermore, it is desirable that the added amount of Fe or Fe oxide is 0.05 wt% or more and 5 wt% or less.
When the added amount of Fe or Fe oxide is less than 0.05% by weight, the endothermic action of the blackened quartz glass is poor, and more rapid crystallization cannot be achieved.
On the other hand, when the addition amount of Fe or Fe oxide exceeds 5% by weight, the quartz glass crucible is excessively blackened and the temperature rise rate of the silicon melt is decreased, which is not preferable.

Moreover, it is preferable that the addition amount of Al is 0.0025 weight% (25 weightppm)-0.0095 weight% (95 weightppm).
Since Al functions as a crystallization accelerator, crystallization of the additive layer is promoted by the mixture of Al. When the concentration of Al is higher than 95 ppm by weight, crystallization proceeds early due to the effect of Fe, and crystallization is promoted excessively. When the content is less than 25 ppm by weight, nucleation of crystallization is sufficiently slow even if Fe is mixed, and sufficient deformation resistance due to crystallization cannot be obtained.

Moreover, it is desirable that the concentration of Na, K, Li, Ca, Al, Ti, Fe, and Cu in the transparent inner layer is 0.1 ppm or less.
When impurities of Na, K, Li, Ca, Al, Ti, Fe, and Cu are mixed in the transparent inner layer, it is not preferable because the molten silicon melt inside the quartz glass crucible is contaminated.

  According to the present invention, by adding a specific additive to the quartz layer (outer layer) at a specific site, the crystallization of the quartz layer is further promoted, the deformation of the crucible is suppressed, and the single crystal by the additive is added. A quartz glass crucible for pulling up a silicon single crystal in which silicon contamination is suppressed can be obtained.

FIG. 1 is a conceptual diagram (sectional view) showing a first embodiment of the present invention. FIG. 2 is an enlarged view of a portion X in FIG. FIG. 3 is a conceptual diagram (sectional view) showing a second embodiment of the present invention. FIG. 4 is an enlarged view of a portion Y in FIG. FIG. 5 is a schematic configuration diagram showing an apparatus for producing a quartz crucible. FIG. 6 is a schematic configuration diagram showing a single crystal silicon pulling apparatus.

  Hereinafter, a first embodiment of a quartz glass crucible for pulling a silicon single crystal according to the present invention will be described with reference to FIGS.

As shown in FIGS. 1 and 2, a quartz glass crucible 1 according to the present invention has, for example, a transparent inner layer 2 made of a synthetic quartz layer having a diameter of 813 mm and substantially free of bubbles, and a natural quartz layer containing bubbles or It is composed of an opaque intermediate layer 3 made of a synthetic quartz layer and an opaque outer layer 4 made of a natural quartz layer or a synthetic quartz layer containing bubbles.
That is, the quartz glass crucible 1 includes a transparent inner layer 2 that comes into contact with a molten silicon melt when pulling a silicon single crystal, an opaque intermediate layer 3 adjacent to the transparent inner layer 2, and an opaque outer layer 4 adjacent to the opaque intermediate layer 3. It is comprised in 3 layer structure which has.

Here, “substantially free of bubbles” means a transparent layer in which bubbles having a diameter of 0.5 mm or more do not exist at a density of 1 pcs / mm ³ or more.
Further, the term “opaque” means a state in which a large number of bubbles (pores) are present in the quartz glass and apparently cloudy. The natural quartz layer means a silica glass layer produced by melting a natural raw material such as quartz, and the synthetic quartz layer is produced by melting a synthetic raw material synthesized, for example, by hydrolysis of silicon alkoxide. Means a silica glass layer.

As schematically shown in FIG. 2, the opaque outer layer 4 includes an outer layer inner layer 4A made of a natural quartz layer or a synthetic quartz layer containing bubbles to which Al and F, e, or Fe oxide are added, and Al. The outermost layer 4B is formed of a natural quartz layer or a synthetic quartz layer containing bubbles added with no Fe or Fe oxide added.
Specifically, the outer layer inner layer 4A of the opaque outer layer 4 is formed by melting natural quartz powder or synthetic quartz powder to which Al and Fe or Fe oxide are added, and has a thickness of 2 mm, for example. It is an Al and Fe-added quartz layer.
Note that the Fe oxide, for example, refers to _FeO, Fe 2 O, the _Fe 3 _{O 4.}

On the other hand, the outermost layer 4B of the opaque outer layer 4 is formed by melting natural quartz powder or synthetic quartz powder to which Al is added and Fe or Fe oxide is not added. This is an Fe-free quartz layer.
The outer inner layer 4A and the outermost layer 4B of the opaque outer layer 4 differ only in whether or not Fe or Fe oxide is added, and the same natural quartz powder or high-purity synthetic quartz powder is used. It is done.

  As described above, the outermost layer 4B of the opaque outer layer 4 is made of a Fe-free quartz layer because the Fe added to the outermost layer 4B is scattered during the production of the quartz glass crucible or during the use of the quartz glass crucible. This is to prevent the inside of the crucible from being contaminated with Fe or the molten silicon melt inside the crucible from being contaminated with Fe.

Further, since the opaque outer layer 4 (outer layer inner layer 4A) is a quartz layer to which Fe or Fe oxide is added, the outer layer of the crucible is colored with Fe or Fe oxide.
Since this colored portion (Fe or Fe oxide) absorbs heat (temperature increases), the temperature of the colored portion rises, and the crystallization of the quartz layer starting from Al around the colored portion is more likely. Promoted.
That is, crystallization proceeds faster than in the case of conventional Al addition alone, and deformation of the quartz glass crucible at the initial stage of silicon dissolution can be suppressed.

  Since Fe hardly diffuses in quartz glass, even when Fe or Fe oxide is added to the outer inner layer 4B of the opaque outer layer 4, it is difficult to diffuse through the opaque intermediate layer 3 to the transparent inner layer 2. Fe contamination of the molten silicon melt inside the quartz glass crucible can be suppressed, and contamination of Fe as an impurity in the pulled single crystal silicon can be suppressed.

Here, it is desirable that the added Fe or Fe oxide has a particle size of 100 mesh or less, and the added amount of the Fe or Fe oxide is 0.05 wt% or more and 5 wt% or less.
The particle size of Fe or Fe oxide added is 100 mesh or less. When the particle size exceeds 100 mesh, the temperature difference between the Fe-added quartz layer and the non-existing region is large in the Fe-added quartz layer. This is not preferable because crystallization varies. That is, it is preferable that Fe or Fe oxide of 100 mesh or less is scattered microscopically and uniformly in the quartz layer as a region that absorbs heat (temperature increases).
The particle size of Fe or Fe oxide is preferably 200 mesh or more and 100 mesh or less (mesh opening of 75 μm or more and 149 μm or less). When the added Fe or Fe oxide has a particle size of less than 200 mesh, the particle size is smaller than that of the quartz powder.

Furthermore, it is desirable that the added amount of Fe or Fe oxide is 0.05 wt% or more and 5 wt% or less.
When the added amount of Fe or Fe oxide is less than 0.05% by weight, the endothermic action of the blackened quartz glass is poor, and more rapid crystallization cannot be achieved.
On the other hand, when the addition amount of Fe or Fe oxide exceeds 5% by weight, the quartz glass crucible is excessively blackened and the temperature rise rate of the silicon melt is decreased, which is not preferable.

The opaque intermediate layer 3 is a quartz layer formed by melting natural quartz powder or synthetic quartz powder, for example, having a thickness of at least 2 mm.
If the thickness of the opaque intermediate layer 3 is smaller than 2 mm, the effect of preventing the Fe scattering of the opaque intermediate layer 3 due to the irregular flow of the arc flame during the melting of the quartz powder is reduced, and the added Fe of the opaque outer layer 4 is reduced. It passes through the opaque intermediate layer 3 and is mixed into the transparent inner layer 2, and the Fe concentration of the high purity transparent inner layer 2 becomes high, which is not preferable. That is, when the Fe concentration on the transparent inner layer 2 side is high, Fe is mixed into the molten silicon melt due to melting of the inner surface of the transparent inner layer 2 due to the molten silicon melt, and the yield of the silicon single crystal is reduced. However, it is not preferable.

The transparent inner layer 2 is formed by melting synthetic quartz powder having a metal impurity content of Na, K, Li, Ca, Al, Ti, Fe, or Cu of 0.1 ppm or less, and has a thickness of at least 1 mm or more. A transparent layer substantially free of bubbles.
When the metal impurity contents of Na, K, Li, Ca, Al, Ti, Fe, and Cu each exceed 0.1 ppm, the molten silicon melt inside the quartz glass crucible is contaminated, which is not preferable.

Further, when the thickness of the transparent inner layer 2 is less than 1 mm, the added Fe diffuses, and when it reaches the transparent inner layer 2, there is a possibility that the molten silicon melt inside the quartz glass crucible is contaminated with Fe. This is not preferable.
Specifically, the total thickness of the opaque intermediate layer 3 and the transparent inner layer 2 is preferably 6.5 mm or more and 15 mm or less, and more preferably 11 mm or more and 15 mm or less.
Therefore, the total of the thickness of the opaque outer layer 4, the thickness of the opaque intermediate layer 3, and the thickness of the transparent inner layer 2 is preferably 13 mm or greater and 17 mm or less.

Furthermore, the amount of Al added is preferably 25 ppm to 95 ppm by weight.
Since Al functions as a crystallization accelerator, crystallization of the additive layer is promoted by the mixture of Al. When the concentration of Al is higher than 95 ppm by weight, crystallization proceeds early due to the effect of Fe, and crystallization is promoted excessively. When the content is less than 25 ppm by weight, nucleation of crystallization is sufficiently slow even if Fe is mixed, and sufficient deformation resistance due to crystallization cannot be obtained.

Thus, the opaque outer layer 4 is colored with Fe or Fe oxide, and this colored portion (Fe or Fe oxide) absorbs heat (temperature increases), so the temperature of the colored portion increases. . Therefore, as compared with the case where no Fe or Fe oxide is added, crystallization of the opaque outer layer 4 is further promoted, and deformation of the quartz glass crucible at the initial stage of silicon dissolution is suppressed.
This crystallization speed is faster than the case of conventional Al addition alone, and the crystallization of the opaque outer layer proceeds. Therefore, the deformation of the quartz glass crucible at the initial stage of silicon dissolution can be further suppressed as compared with the case of conventional Al addition alone. .
As a result, adhesion stability of the support by the carbon susceptor can be obtained while ensuring the heat distortion resistance of the crucible, and the single crystallization rate of the silicon single crystal can be improved.

Next, a second embodiment according to the present invention will be described with reference to FIGS.
The quartz glass crucible 10 according to the second embodiment has a three-layer structure on the side and a two-layer structure on the bottom, and Al and Fe or Fe are formed on the outer layer of the three-layer structure on the side. It is characterized in that an oxide is added.
That is, a natural stone to which Al and Fe or an Fe oxide are added from a crucible upper end 14 to a predetermined range on the basis of the curvature change point between the side portion 13 and the bottom portion 11 and the bottom corner 12. It has a three-layer structure formed by an opaque outer layer 15 made of an English layer or a synthetic quartz layer, an opaque intermediate layer 16 made of a natural quartz layer or a synthetic quartz layer, and a transparent inner layer 17 made of a synthetic quartz layer.
Further, the bottom portion 11 has a two-layer structure formed of a layer formed continuously from the opaque intermediate layer 16 and the transparent inner layer 17.

As schematically shown in FIG. 4, the opaque outer layer 15 includes an outer layer inner layer 15A made of a natural quartz layer or a synthetic quartz layer containing bubbles to which Al and Fe or Fe oxide are added, and Al. And an outermost layer 15B made of a natural quartz layer or a synthetic quartz layer containing bubbles to which no Fe or Fe oxide is added.
Specifically, the outer outer layer 15A of the opaque outer layer 15 is formed by melting natural quartz powder or synthetic quartz powder to which Al and Fe or Fe oxide are added, and has a thickness of 2 mm, for example. This is an Fe-added quartz layer.
Further, the outermost layer 15B of the opaque outer layer 15 is formed by melting natural quartz powder or synthetic quartz powder to which Al is added and Fe or Fe oxide is not added. This is an Fe-free quartz layer.
The outer inner layer 15A and the outermost layer 15B of the opaque outer layer 15 differ only in whether or not Fe or Fe oxide is added. Natural quartz powder or high-purity synthetic quartz powder to which Al is added is different. The same thing is used.

Further, since the opaque outer layer 15 (outer layer inner layer 15A) is a quartz layer to which Fe or Fe oxide is added, the outer layer of the crucible is colored with Fe or Fe oxide.
Since this colored portion (Fe or Fe oxide) absorbs heat (temperature increases), crystallization of the quartz layer around the colored portion by Al is further promoted, compared to the case of conventional Al addition alone. Crystallization proceeds as soon as possible, and deformation of the crucible at the initial stage of silicon dissolution can be suppressed.

  Similarly to the first embodiment, the added Fe or Fe oxide has a particle size of 100 mesh or less, and the added amount of the Fe or Fe oxide is 0.05 wt% or more, 5 It is desirable that the amount is not more than% by weight.

By constructing the silica glass crucible as in the second embodiment, the bottom portion 11 in a predetermined range where the opaque outer layer 15 containing Fe or Fe oxide is not present is softened in the initial stage of starting the pulling of the silicon single crystal. And a carbon susceptor (not shown) that supports the crucible.
Thereafter, from the start to the completion of the pulling, the crystallization (cristobalite) of the opaque outer layer 15 such as the bottom corner and the side in a predetermined range proceeds by high-temperature heating, and the entire crucible and the carbon that supports the crucible. Adhesion stability with susceptor is improved. Further, the heat distortion resistance is improved by crystallization.

In particular, the opaque outer layer 15 is colored with Fe or Fe oxide, and this colored portion (Fe or Fe oxide) absorbs heat (temperature increases), so the temperature of the colored portion increases. Therefore, compared with the case where Fe or Fe oxide is not added, crystallization of the opaque outer layer 15 by Al is further promoted, and deformation of the quartz glass crucible at the initial stage of silicon dissolution is suppressed.
This crystallization speed is faster than the case of conventional Al addition alone, and the crystallization of the opaque outer layer proceeds. Therefore, the deformation of the quartz glass crucible at the initial stage of silicon dissolution can be further suppressed as compared with the case of conventional Al addition alone. .
As a result, adhesion stability of the support by the carbon susceptor can be obtained while ensuring the heat distortion resistance of the crucible, and the single crystallization rate of the silicon single crystal can be improved.

Next, the manufacturing method of the quartz glass crucible 1 concerning this invention is demonstrated.
The quartz glass crucible 1 is manufactured using the quartz glass crucible manufacturing apparatus 20 as shown in FIG.
The crucible forming die 21 of the quartz glass crucible manufacturing apparatus 20 includes an inner member 22 made of a gas permeable member such as a die having a plurality of through holes or a highly purified porous carbon die. The holding member 24 holds the inner member 22, and the ventilation portion 23 provided between the inner member 22 and the holding member 24.

  A rotating shaft 25 connected to a rotating means (not shown) is fixed to the lower portion of the holding body 24, and supports the crucible forming die 21 so as to be rotatable. The ventilation portion 23 is connected to an exhaust passage 27 provided in the center of the rotating shaft 25 through an opening 26 provided in the lower portion of the holding body 24, and the exhaust passage 27 is connected to the decompression mechanism 28. It is connected.

  An arc electrode 29 for arc discharge, an Al-added quartz powder supply nozzle 30, an Fe or Fe oxide and Al-added quartz powder supply nozzle 31, a natural quartz powder supply nozzle 32, and an upper portion facing the inner member 22; A synthetic quartz powder supply nozzle 33 is provided.

The Fe or Fe oxide and Al-added quartz powder used for the opaque outer layer 4 is manufactured, for example, by mixing Fe, Fe oxide powder and Al powder with a quartz raw material.
The Fe or Fe oxide used here has a particle size of 100 mesh or less. Further, the addition amount of Fe or Fe oxide is adjusted to 0.05 wt% or more and 5 wt% or less.
Moreover, the addition amount of Al is adjusted to 25 weight ppm or more and 95 weight ppm.

In order to manufacture the quartz glass crucible 1 using the above-described quartz glass crucible manufacturing apparatus 20 with the Fe or Fe oxide and Al-added quartz powder obtained in this way, first, a rotary drive source (not shown) is operated to rotate the rotary shaft 25. Is rotated in the direction of the arrow to rotate the crucible forming die 11 at a high speed.
First, by supplying Al-added quartz powder from the Al-added quartz powder supply nozzle 30, the outermost layer 4B of the opaque outer layer 4 of the crucible molded body is formed by being pressed against the inner surface side of the inner member 22 by centrifugal force.
Subsequently, the Fe and Al-added quartz powder obtained as described above is supplied from the Fe or Fe oxide and Al-added quartz powder supply nozzle 31 into the crucible molding die 20. The supplied Fe or Fe oxide and Al-added quartz powder are pressed to the inner surface side of the outermost layer 4B by centrifugal force to form the opaque outer layer 4 of the crucible molded body.

Further, natural quartz powder or synthetic quartz powder such as natural quartz is formed so that an opaque intermediate layer 3 having a thickness of at least 2 mm is formed on the inner surface side of the opaque outer layer made of Fe or Fe oxide and Al-added quartz layer. Powder is supplied from a natural quartz powder supply nozzle 32.
The supplied natural quartz powder is pressed to the inner surface side of the outer layer 4 by centrifugal force, and is formed as a molded body of the opaque intermediate layer 3.

Next, a transparent inner layer having a thickness of at least 1 mm or more is formed on the inner surface side of the opaque intermediate layer 3. A high-purity synthetic quartz powder having a concentration of 0.1 ppm or less of Na, K, Li, Ca, Al, Ti, Fe, and Cu in the transparent inner layer is supplied from a synthetic quartz powder supply nozzle 33.
The supplied high-purity synthetic quartz powder is pressed against the inner surface side of the opaque intermediate layer 3 by centrifugal force, and is molded as a molded body of the inner layer 4.
In this way, a molded body of the opaque outer layer 4, the opaque intermediate layer 3, and the transparent inner layer 2 is obtained.

  Subsequently, the inside of the inner member 22 is depressurized by the operation of the decompression mechanism 28, the arc electrode 29 is energized and heated from the inside of the molded body, and the transparent inner layer 2, the opaque intermediate layer 3 and the opaque outer layer 2 of the molded body are melted. Thus, the quartz glass crucible 1 is manufactured.

  Since the molded body is melted while reducing the pressure, the transparent inner layer 2 becomes a substantially bubble-free transparent layer. Further, the presence of the opaque intermediate layer 3 can effectively prevent the Fe or Fe oxide from being scattered from the opaque outer layer 4 to the transparent inner layer 2 due to the disturbance of the arc flame during melting of the molded body.

Next, a silicon single crystal pulling method using the quartz glass crucible according to the present invention will be described.
As shown in FIG. 6, in order to pull up the single crystal silicon 40 using the quartz glass crucible 1, the raw material polysilicon is put into the quartz glass crucible 1, and the quartz glass crucible 1 is heated by the heater 41, and the motor (FIG. The quartz crucible 1 is rotated by rotating the rotating shaft 42 coupled to the not shown.
After a certain period of time has passed, the source polysilicon is heated to a silicon melting point of 1430 ° C. or higher and becomes a silicon melt 42. Then, the seed shaft 44 is lowered and the seed crystal 45 is brought into contact with the liquid surface of the silicon melt 43. The single crystal silicon single crystal 40 is pulled up.
In FIG. 6, reference numeral 46 denotes a support for the quartz glass crucible 1, and reference numeral 47 denotes a heat insulating cylinder.

In the heating temperature raising process of the silicon single crystal pulling process, the opaque outer layer 4 of the quartz glass crucible 1 is crystallized into cristobalite when heated for a certain time at 1200 ° C. or higher.
In particular, the outer layer of the crucible is colored with Fe or Fe oxide, and this colored portion (Fe or Fe oxide) absorbs heat (temperature increases), so that the temperature of the colored portion rises and the colored portion Crystallization of the quartz layer is promoted starting from the surrounding Al.
Due to the growth of the cristobalite, a remarkable effect of improving the viscosity is recognized, and by crystallization, deterioration of the quartz glass crucible 1 due to bubble expansion when the quartz glass crucible 1 is used can be suppressed.

Since the nucleation rate of cristobalite becomes maximum at about 1300 ° C. when Al is contained, the heating method at the time of using the quartz glass crucible 1 is 1200 ° C. or higher for a certain time, preferably 1250 to 1350 ° C. as described above. The temperature is maintained for 2 hours or more, and the temperature is raised to the silicon melting point of 1430 ° C. or more when the nucleation is sufficiently advanced.
Note that the outer layer of the crucible is colored with Fe or Fe oxide, and this colored portion (Fe or Fe oxide) absorbs heat (temperature increases), so 1250 in the case of conventional Al addition only. The holding time at 1350 ° C. can be shortened to 2 hours compared to 3 hours or more, which can be shortened.

  When the holding temperature is lower than 1200 ° C or when the holding time is shorter than a certain time, nucleation is not sufficiently performed, and when the temperature is raised to 1430 ° C or more when nucleation is insufficient, uniform cristobalite is generated. Does not occur, and the effect of suppressing the expansion of bubbles cannot be expected.

  As described above, after maintaining at 1200 ° C. or higher for a certain period of time, preferably at 1250 to 1350 ° C. for 2 hours or more, by raising the temperature to 1430 ° C. or higher, the viscosity of the opaque outer layer 4 is significantly improved and the crucible 1 is deteriorated It is greatly reduced and can be melted for a long time by pulling a large-diameter silicon single crystal or recharging polycrystalline silicon as a raw material.

  Moreover, since the transparent inner layer 2 is formed of high-purity synthetic quartz powder, there is no risk of impurity contamination of the single crystal even when the transparent inner layer 2 is dissolved in the silicon melt. Since manufacturing is performed while reducing the pressure from the member 22 side, it is a bubble-free layer, and it is possible to prevent a decrease in silicon single crystal yield due to glass peeling due to expansion of bubbles.

  Further, the presence of the opaque intermediate layer 3 effectively prevents the diffusion of Fe from the opaque outer layer 4 having a high Fe concentration to the transparent inner layer 2 when pulling up the single crystal, thereby ensuring Fe contamination in the silicon melt. Can be prevented.

Example 1
The quartz glass crucible 1 was manufactured using the quartz glass crucible manufacturing apparatus 20 shown in FIG.
As the Fe oxide (specifically, Fe ₃ O ₄ ) used for the opaque outer layer, the particle size was 100 mesh, and the addition amount was 4.5% by weight.
The amount of Al added to the opaque outer layer was 50 ppm by weight.
Then, while the inner member 22 was depressurized by the operation of the depressurization mechanism, it was supplied from the Al-added quartz powder supply nozzle 30 into the crucible molding die 20 to form an outermost layer having a thickness of 0.5 mm.
Subsequently, Fe oxide and Al-added quartz powder were supplied from the Fe or Fe oxide and Al-added quartz powder supply nozzle 31 to the inner side surface of the outermost layer to form an outer layer inner layer having a thickness of 2 mm. An opaque outer layer was formed by the outer layer inner layer and the outermost layer.

Furthermore, natural quartz powder was supplied from the natural quartz powder supply nozzle 32, and the intermediate layer 3 having a thickness of 12.1 mm was formed on the inner surface side of the opaque outer layer.
Subsequently, high-purity synthetic quartz powder having a concentration of 0.1 ppm or less of Na, K, Li, Ca, Al, Ti, Fe, and Cu is supplied from the synthetic quartz powder supply nozzle 33, and the inner surface of the intermediate layer 3. A transparent inner layer having a thickness of 2 mm was formed on the side.
The arc electrode was energized and heated from the inside of the molded body, and the transparent inner layer, opaque intermediate layer and opaque outer layer of the molded body were melted to produce a quartz glass crucible.
And the outer diameter in the position below 10 mm from the upper end part of the crucible was measured.

Further, as shown in FIG. 6, the silicon single crystal 40 was pulled up using the quartz glass crucible 1. As described above, the heating method at the time of using the quartz glass crucible 1 was maintained at 1250 ° C. for 2 hours as described above, and when the nucleation was sufficiently advanced, the temperature was raised to 1430 ° C. or higher of the silicon melting point.
And the outer diameter in the position below 10 mm from the upper end part of a crucible was measured, and it compared with the outer diameter before heat processing. The results are shown in Table 1.
Further, impurities of the pulled silicon single crystal were measured by a vapor phase sublimation method. The results are shown in Table 2.

(Example 2)
A quartz glass crucible was manufactured with the addition amount of Fe oxide (specifically, Fe ₃ O ₄ ) used for the opaque outer layer 4 being 5% by weight and the other conditions being the same as in Example 1.
Then, as in Example 1, the outer diameter before and after heat treatment was measured at a position 10 mm below the upper end of the crucible before and after pulling, and the results are shown in Table 1.
Further, as in Example 1, the impurities of the pulled silicon single crystal were measured by the vapor phase sublimation method. The results are shown in Table 2.

(Comparative Example 1)
As the Fe oxide (specifically, Fe ₃ O ₄ ) used for the opaque outer layer 4, the particle size is 100 mesh, the addition amount is 6.0 wt%, the other conditions are the same as in Example 1, and quartz glass A crucible was manufactured.
And similarly to Example 1, the outer diameter before and after heat treatment was measured at a position 10 mm below the upper end of the crucible. The results are shown in Table 1.
Further, as in Example 1, the impurities of the pulled silicon single crystal were measured by the vapor phase sublimation method. The results are shown in Table 2.

(Comparative Example 2)
As the Fe oxide (specifically, Fe ₃ O ₄ ) used for the opaque outer layer 4, the particle size is 100 mesh, the addition amount is 0.03% by weight, and other conditions are the same as those in Example 1, and quartz glass A crucible was manufactured.
And similarly to Example 1, the outer diameter before and after heat treatment was measured at a position 10 mm below the upper end of the crucible. The results are shown in Table 1.
Further, as in Example 1, the impurities of the pulled silicon single crystal were measured by the vapor phase sublimation method. The results are shown in Table 2.

(Comparative Example 3)
The Fe oxide (specifically, Fe ₃ O ₄ ) used for the opaque outer layer 4 has a particle size of 60 mesh, an addition amount of 5% by weight, the other conditions are the same as in Example 1, and a quartz glass crucible is used. Manufactured.
And similarly to Example 1, the outer diameter before and after heat treatment was measured at a position 10 mm below the upper end of the crucible. The results are shown in Table 1.
Further, as in Example 1, the impurities of the pulled silicon single crystal were measured by the vapor phase sublimation method. The results are shown in Table 2.

(Comparative Example 4)
As the Fe oxide (specifically, Fe ₃ O ₄ ) used for the opaque outer layer 4, the particle size is 300 mesh, the addition amount is 4.5 wt%, the other conditions are the same as in Example 1, and quartz glass A crucible was manufactured.
And similarly to Example 1, the outer diameter before and after heat treatment was measured at a position 10 mm below the upper end of the crucible. The results are shown in Table 1.
Further, as in Example 1, the impurities of the pulled silicon single crystal were measured by the vapor phase sublimation method. The results are shown in Table 2.

(Comparative Example 5)
A quartz glass crucible was manufactured by adding no Fe oxide to the opaque outer layer 4 and making the other conditions the same as in Example 1.
And similarly to Example 1, the outer diameter before and after heat treatment was measured at a position 10 mm below the upper end of the crucible. The results are shown in Table 1.
Further, as in Example 1, the impurities of the pulled silicon single crystal were measured by the vapor phase sublimation method. The results are shown in Table 2.

Thus, when the opaque outer layer is a natural quartz layer or synthetic quartz layer to which Fe or Fe oxide is added, there is little difference in the outer diameter before and after heat treatment at a position 10 mm below the upper end of the crucible, and Si dissolution It was confirmed that the initial crucible deformation can be suppressed.
In addition, it was confirmed that the silicon melt inside the crucible was not contaminated with Fe, and mixing of the Fe into the pulled single crystal silicon was prevented.

DESCRIPTION OF SYMBOLS 1 Quartz glass crucible 2 Transparent inner layer 3 Opaque intermediate layer 4 Opaque outer layer 4A Outer layer inner layer 4B Outermost layer 10 Quartz glass crucible 11 Bottom 12 Bottom corner 13 Side 14 Crucible upper end 15 Opaque outer layer 15A Outer inner layer 15B Outermost layer 16 Opaque intermediate layer 17 Transparent inner layer

Claims (4)

A transparent inner layer made of a synthetic quartz layer substantially free of bubbles,
An opaque intermediate layer made of natural quartz or synthetic quartz containing bubbles,
In a quartz glass crucible for pulling a silicon single crystal composed of an opaque outer layer made of a natural quartz layer or a synthetic quartz layer containing bubbles,
A quartz glass crucible for pulling a silicon single crystal, wherein the opaque outer layer is a natural quartz layer or a synthetic quartz layer to which Al and Fe or Fe oxide are added. The opaque outer layer is divided into two layers, an inner layer and an outermost layer,
An inner layer of the opaque outer layer is a natural quartz layer or a synthetic quartz layer to which Al and Fe or Fe oxide are added;
The quartz glass crucible for pulling up a silicon single crystal according to claim 1, wherein the outermost layer of the opaque outer layer is a natural quartz layer or a synthetic quartz layer to which Al is added, and is the same as the inner layer. The particle size of Fe or Fe oxide added is 100 mesh or less,
3. The quartz glass crucible for pulling a silicon single crystal according to claim 1, wherein the addition amount of Fe or Fe oxide is 0.05 wt% or more and 5 wt% or less.   4. The silicon single unit according to claim 1, wherein the concentration of Na, K, Li, Ca, Al, Ti, Fe, and Cu in the transparent inner layer is 0.1 ppm or less. 5. Quartz glass crucible for crystal pulling.

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