JPH10297992A - Crucible for pulling crystal and part for pulling crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of a quartz crucible that causes no buckling deformation in a crucible for pulling a single crystal having a structure that the quartz crucible is fitted in the graphite crucible. SOLUTION: This crucible 10 for pulling a single crystal is composed of a graphite crucible 12 and a quartz crucible 14 fitted in the graphite crucible 12. The graphite crucible 12 has a plurality of through-holes 16 bored. These through-holes 16 are bored only at higher position than the liquid level of the initial silicon melt to be pulled up. These through-holes dissipate gases emitting by the reaction of the quartz crucible 14 and the graphite crucible 12 to prevent the quartz crucible from being deformed by the gas pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crucible for holding a raw material melt at the time of pulling a crystal and a part thereof, and more particularly to a quartz member used for pulling a semiconductor single crystal such as silicon by the Czochralski method. The present invention relates to a crucible made of graphite and a graphite member and a component for constituting the same.

[0002]

2. Description of the Related Art There are various crystal growth methods, one of which is a pulling method typified by the Czochralski method (CZ method). It is.

[0003] In the crystal pulling apparatus shown in FIG. 7, a crystal pulling crucible 70 for holding a raw material melt is disposed in the center of a chamber 78. The crystal pulling crucible 70 includes a quartz crucible 70a having a cylindrical side wall and a graphite crucible 70b having a cylindrical side wall surrounding the quartz crucible 70a. The quartz crucible 70a is fitted in the graphite crucible 70b. Outside the crystal pulling crucible 70, a resistance heating type heater 72 and a graphite heat retaining cylinder 74 are arranged concentrically. The crystal pulling crucible 70 accommodates a solution 73 of a raw material. The solution 73 is prepared by melting a predetermined weight of the raw material by the heater 72. On the central axis of the crystal pulling crucible 70, a pulling rod or wire 76 that can rotate at a predetermined speed in the direction indicated by the arrow in the figure is provided, and a seed crystal 75 is attached to the tip thereof. The crystal pulling crucible 70 is supported by a crucible support shaft 17 that can rotate in the same or opposite direction about the same axis as the pulling rod 76. The single crystal 71 can be grown by bringing the seed crystal 75 into contact with the surface of the prepared solution 73, rotating the crystal in accordance with the growth, and pulling the crystal upward.

When a single crystal of semiconductor silicon is manufactured by the pulling method, for example, the melting point of silicon is about 1420 ° C.
Therefore, it is necessary to first heat and dissolve the silicon raw material to reach the melting point. In that case, it is necessary to raise the temperature of the resistance heater to around 2000 ° C. This heating also heats the quartz crucible above the melting point of silicon. Quartz begins to soften and deform above about 1200 ° C., and the rate of deformation per hour increases exponentially with increasing temperature.

In the crystal pulling crucible shown in FIG.
The quartz crucible 70a is under the high temperature conditions described above, due to its own weight, or when a part of the semiconductor raw material adheres to the inner wall of the quartz crucible 70a, due to the vertical load due to the weight of the attached semiconductor raw material. Buckling deformation occurs as shown in FIG. 8 and FIG. 9, and as a result, a problem occurs in pulling a single crystal.

More specifically, when buckling deformation occurs, local changes occur in the flow and temperature distribution on the surface of the solution 73. This change causes crystal defects in the course of the crystal being pulled or limits the speed at which the crystal pulling crucible 70 can be lifted, thereby impairing crystal growth.
Further, the quartz crucible may be damaged from the buckled portion, and a serious accident such as overflow of the solution 73 into the apparatus may be caused.

In particular, in recent years, as the diameter of a single crystal to be pulled increases, the size of the crucible also increases, and the weight of the crucible also increases. And the weight of the raw material filled in the crystal pulling crucible also increases, and as the melting temperature and the melting time increase, breakage due to buckling tends to occur.

In order to prevent such buckling deformation, for example, Japanese Patent Application Laid-Open No. 64-69699 proposes providing a reinforcing ring at the upper end of a quartz crucible. Japanese Utility Model Application No. 4-73196 discloses a single crystal pulling crucible comprising an inner layer holding container made of quartz and an outer layer holding container fitted to the inner layer holding container, wherein the upper end of the inner layer holding container made of quartz is bent. Then, the structure which supports this by the outer layer holding container is proposed.

[0009]

However, providing a reinforcing ring at the upper end of the quartz crucible is effective in suppressing the inward deformation of the upper end, but the weight of the upper end increases, so that the weight of the crucible increases due to its own weight. The buckling deformation shown in FIG.

The structure in which the upper end of the inner crucible made of quartz is bent and supported by the upper end of the outer crucible has an effect of preventing buckling deformation. However, when the heater temperature is increased, the deformation cannot be completely prevented. I understand.

An object of the present invention is to solve such a problem of the prior art, and to provide a crystal pulling crucible having a structure in which buckling deformation does not occur.

[0012]

SUMMARY OF THE INVENTION The present inventor has investigated the causes of buckling deformation in a crystal pulling crucible having a structure in which a quartz crucible is fitted in a graphite crucible, and as a result, has found that the buckling deformation has occurred. Was found to be caused not only by the load but also by the pressure of the gas generated by the reaction between the quartz and the graphite. That is,
Between the outer surface of the quartz crucible and the inner surface of the graphite crucible, CO gas is generated by the following reaction.

[0013]

Embedded image

Therefore, in the structure in which the upper end of the quartz crucible is bent outward, gas generated by the reaction between the graphite crucible and the quartz crucible cannot escape, so that the petal-like deformation protruding inward as shown in FIG. It was found to happen. In addition, even in a normal crucible whose upper end is not bent, the quartz crucible softens and deforms due to use at high temperature and adheres closely to the graphite crucible, so it is deformed under the influence of the generated gas pressure and further pulled up by its own weight. It was thought that the deformation increased during.

The present inventor has studied a structure capable of effectively preventing deformation due to gas, and has completed the present invention. That is, the present invention
A crystal pulling crucible in which an inner container made of quartz is fitted in an outer container made of graphite, and a plurality of through-holes are formed in the side wall of the outer container so as to communicate with the inner container from outside the outer container. In addition, the through hole is formed only above a position where a melt surface for pulling a crystal should be formed at an early stage of use.

Accordingly, the present invention provides an unprecedented graphite crystal pulling component which can effectively support a quartz container for holding a melt during crystal pulling from the outside. . The crystal pulling component made of graphite according to the present invention constitutes a container having an inner surface in which a crucible made of quartz can be fitted, and a plurality of through holes are formed in a side wall of the container. Is formed. Then, the through-hole is a predetermined height in the height direction of the container so that the crucible made of quartz fits inside and holds the melt for crystal pulling only at a position higher than the melt surface. It is provided only at a position higher than the height. If such a crystal pulling component made of graphite is combined with a crucible made of arbitrary quartz, a crystal pulling crucible in which an inner container made of quartz is fitted in the outer container made of graphite according to the present invention as described above. Can be provided.

As described above, the buckling deformation of the quartz container fitted in the graphite container is affected not only by the weight of the quartz container itself but also by the reaction gas at the contact surface between the graphite container and the quartz container. . In the present invention, by forming a through-hole in the graphite container, this gas is radiated to the outside, preventing the gas pressure from rising and preventing the quartz container from being deformed by the gas.

The buckling of the quartz container which directly holds the raw material melt in the crystal pulling crucible is remarkable above the liquid level of the melt prepared by dissolving the raw material during use. On the other hand, in a portion below the melt surface, the pressure of the melt suppresses the quartz container from being protruded and deformed inward. Further, when the raw material is dissolved, the temperature of the quartz container becomes the highest and buckling deformation is likely to occur. During the dissolution of the raw material,
When deformation occurs at a portion higher than the melt surface, since the holding at a high temperature continues when pulling a single crystal, the weight of the quartz container is applied to the deformed portion and the deformation increases. Therefore, it is most important that the quartz container is not deformed when the raw material is dissolved. From this point of view, the through-hole for letting out the reaction gas is located at the position where the melt surface should come at the beginning when using the crucible, that is, the maximum amount of the raw material that is usually prepared by dissolving the raw material for crystal pulling. It is particularly important that the melt is formed above the position of the melt surface when it is held in the crucible, in order to prevent deformation. As will be described in more detail below, the present inventor does not provide a through hole in a portion below the melt surface, that is, forms a through hole only in a portion above a position where the melt surface is to be formed. Is important.

Japanese Patent Application Laid-Open No. 58-140392 discloses a silicon single crystal pulling apparatus having a quartz crucible and a graphite crucible supporting the quartz crucible, by providing a plurality of grooves or through-holes along the outer periphery. Disclosed is a silicon single crystal pulling apparatus provided with the graphite crucible configured to radiate heat above the surface and absorb heat below the surface. In this apparatus, the diameter of the through hole is, for example, not more than 1/2 of the maximum thickness of the side wall of the graphite crucible, and the number density of the through holes along the circumferential direction is at least 1.5 times the number density of the holes along the axial direction. It is. As described above, the same publication discloses a configuration in which a through hole is formed in a graphite crucible in a crucible having a structure in which a quartz crucible is supported by a graphite crucible. Are different. In the crystal pulling crucible disclosed in the publication, the through-hole is formed for the purpose of radiating heat above the silicon melting surface and absorbing heat below the silicon melting surface. In the same publication, the through-hole is formed for the purpose of increasing the surface area of the crucible, and in the portion above the melt surface, the cooling is enhanced by increasing the heat radiation area by the through-hole, and in the lower portion, the heat transfer area is increased. The increase is intended to increase thermal efficiency. In order to obtain the effect of radiating heat above the melt surface and absorbing heat below the melt surface, it is necessary to form through holes both above and below the melt surface.

However, from the viewpoint of preventing buckling deformation, providing a through-hole in the entire wall of the crucible to increase the heat transfer area has a serious problem. Especially,
When the through-hole was provided in the entire crucible, it was found that the temperature was significantly increased in a portion below the melt surface, and the deformation of the quartz crucible became more conspicuous. In this case, along with the softening of the quartz crucible by heat, it was found that the quartz crucible was likely to be deformed by the liquid pressure of the melt in the portion where the through-hole was formed, that is, the portion not supported by the graphite crucible. In an extreme case, a crack may be generated from a deformed portion of the quartz crucible during melting of the raw material, pulling of the crystal, or cooling, and leakage of the melt may occur. The inventor has
From the viewpoint of preventing deformation of the quartz crucible, it was clarified that the graphite crucible supporting the quartz crucible should not be provided with through holes in the portion located below the melt surface. It has been found that the through hole in the portion located at can effectively prevent deformation of the quartz crucible. The feature of the present invention that the through-hole is provided only above the position where the melt surface should come at the beginning of use is established based on such knowledge, and in order to increase the heat conduction area This could not have been predicted from the conventional technology having the through holes.

In the present invention, the upper end of the inner container made of quartz may have a shape protruding outward so as to be supported by the upper end of the outer container made of graphite. In such a structure, the inner container is supported by the outer container, and buckling deformation due to the weight of the inner container is prevented. Such a structure makes it difficult for gas generated from the fitting surface between the quartz container and the graphite container to escape, but by providing a through hole according to the present invention, the gas can be sufficiently diffused, Deformation due to its own weight and deformation due to gas pressure can be suppressed at the same time, and buckling deformation can be more effectively prevented.

More preferably, the through hole is formed in a range not exceeding 50 mm above the position where the melt surface is to be formed. The through holes are preferably formed at a density of 5 or more per circumference along the outer periphery of the outer container.

In the present invention, it is preferable that a groove having a depth of 0.5 mm or more is further formed on the inner wall of the outer container above a position where the melt surface is to be formed. This groove has an area of 20% per unit surface area in the area where the groove is formed.
It can be formed at the above ratio. The groove reduces the area of the portion where the quartz container and the graphite container are in close contact, and effectively suppresses gas generation. By combining the formation of the through hole and the formation of the groove, buckling deformation can be more effectively prevented.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the crystal pulling crucible of the present invention and components constituting the same will be described more specifically. FIG. 1 shows a specific example of a crystal pulling crucible and components according to the present invention. Crystal pulling crucible 10
Is a graphite crucible 12 having a cylindrical side wall and a round bottom,
A quartz crucible 14 having a cylindrical and round bottom has a side wall fitted therein. The outer surface of the quartz crucible 14 is in contact with the inner surface of the graphite crucible 12. The graphite crucible 12 may have a structure in which two members 12a and 12b are integrated by a receiving base 12c, for example, as shown in the drawing. As described above, by constituting the graphite crucible with two or more divided members, it is possible to effectively prevent the quartz crucible from being restrained by the graphite crucible and causing cracks during cooling after completion of crystal pulling. Can be.
As shown in the figure, a through hole 16 is formed in the graphite crucible 12. The through-hole 16 is provided above a position (indicated by an arrow in the drawing) where the melt surface should come at the beginning of use. The through-hole 16 allows gas generated at the fitting surface between the quartz crucible 14 and the graphite crucible 12 to be diffused to the outside. As described above, in order to prevent the quartz crucible 12 from being deformed, the through-hole 16 needs to be formed above a position where an initial melt surface is to be formed. On the other hand, in the portion below the melt surface, deformation of the quartz crucible is prevented by the static pressure of the melt, so that it is not necessary to provide a through hole for venting gas. Rather, as described above, if a through hole is provided in a portion below the melt surface, the quartz crucible is deformed in the portion where the through hole is provided, and in an extreme case, the quartz crucible is cracked and leakage of the melt occurs. Will get up. Graphite crucible 12 shown in the figure
In the side wall below the position where the melt surface should come,
It does not have a through hole and has a substantially constant thickness.

As shown in FIG. 2, the position where the through hole 16 'is formed is preferably within a range of 50 mm above the initial melt surface position (indicated by an arrow). By forming the through hole in this range, the deformation of the quartz crucible can be more effectively prevented. Above this range in the quartz crucible, the gas generated by the reaction between the quartz crucible and the graphite crucible is relatively easy to escape from the upper end, and the deformation due to the gas pressure becomes relatively small. Further, since the crucible does not receive much weight at the portion near the upper end, deformation due to its own weight is relatively small. Therefore, it is possible to prevent deformation more effectively if the through hole is formed in a range of 50 mm above and closer to the melt surface than a portion closer to the upper end.

The number of the through holes can be arbitrarily set in order to effectively diffuse the gas. For example, it is preferable that the number of the through holes is 5 or more per circumference on the outer periphery of the graphite crucible. As shown in FIG. 9, it is likely that about 5 to 10 places of protrusion deformation inward in the quartz crucible, for example, in the circumferential direction. Therefore, it is desirable to provide five or more through holes per circumference corresponding to the number of protrusions. It is considered that the number of through holes is 1-2 times the number of projecting deformations is sufficient, and therefore, it is preferable to provide 5 to 20 through holes per circumference. If the number of holes is increased more than necessary, the strength of the graphite crucible may be reduced, and at the same time, the temperature of the crucible may become non-uniform, which may adversely affect the convection of the melt. It is desirable to keep it. The through hole is, for example, as shown in FIG.
As shown in (a), a plurality of graphite crucibles can be provided at substantially equal intervals at the same height. Further, as shown in FIG. 3B, a plurality of graphite crucibles may be provided at different positions along the outer periphery of the graphite crucible. In the case where the through holes are provided at positions having different heights, for example, FIG.
As shown in FIG. 3, through holes may be provided at substantially the same position in the circumferential direction at substantially equal intervals, or as shown in FIG. 3C, through holes may be provided at different positions in the circumferential direction. The intervals in the circumferential direction of the through holes may be changed or the same depending on the height.

The diameter of the through holes may be relatively small for the purpose of dissipating gas. However, if the diameter is excessively small, SiC is generated on the graphite surface due to repeated use of the graphite crucible and the quartz crucible, and the diameter of the hole becomes smaller.
mm, and preferably 2-5 mm. By making the diameter of the hole 1 mm or more, SiC is generated on the hole surface with repeated use,
The hole can be prevented from being closed by the volume expansion. On the other hand, if the holes are excessively large, the strength is reduced, the temperature distribution is not uniform, and the like.
The following is more desirable.

FIG. 4 shows another embodiment of the crystal pulling crucible according to the present invention. Crystal pulling crucible 20
A graphite crucible 22 having a cylindrical side wall and a round bottom;
The quartz crucible 24 has a cylindrical side wall and a round bottom. The quartz crucible 24 is fitted in the graphite crucible 22, and the outer surface of the quartz crucible 24 is in contact with the inner surface of the graphite crucible 22. As described above, the graphite crucible 22 has a structure in which the two members 22a and 22b are integrated by the pedestal 22c. The upper end portion of the quartz crucible 24 has a shape bent outward, and a portion 24 a protruding by this bending is in contact with the upper end of the graphite crucible 22. In this structure, the quartz crucible 24 is supported by the graphite crucible 22 via the protrusion 24a. Therefore, the weight of the side wall of the quartz crucible 24 is reduced. A through hole 26 is formed in the side wall of the graphite crucible 22 above a position (indicated by an arrow) where a melt surface is to be formed. As described above, the upper end of the quartz crucible 24 is bent outward to be supported by the upper end of the graphite crucible 22, and the through-hole is provided at a position above the melt surface, whereby the buckling deformation of the quartz crucible is performed. A greater effect on prevention can be obtained. This is because, by supporting the upper end of the quartz crucible with the graphite crucible, deformation due to its own weight can be prevented, and deformation due to gas pressure can be simultaneously prevented by releasing gas from the through holes.

By forming grooves in the inner surface of the graphite crucible in addition to forming the through holes, it is possible to prevent the quartz crucible from being in close contact with the graphite crucible, to dissipate gas more efficiently, and to prevent buckling deformation. it can. This groove is also formed above the initial melt surface for the same reason as the through hole. FIG.
Shows a crystal pulling crucible in which a groove is formed in a graphite crucible as an outer container. In the crystal pulling crucible 30, the graphite crucible 3 provided outside the quartz crucible 34.
2 has a through-hole 36 and a V-shaped cross section thereof.
A groove 38 is formed. The V-shaped groove 38 is formed along the inner circumference of the graphite crucible 32. The through hole 36 and the V-shaped groove 38 are provided above a position (indicated by an arrow) where an initial melt surface is to be formed. The depth, width, shape, and the like of the groove are not particularly limited, but for example, from the viewpoint of promoting gas emission, the depth of the groove is preferably 0.5 mm or more. Even a very narrow groove having a width of, for example, about 0.5 mm is sufficiently effective. In order to maintain the strength of the graphite crucible, the depth of the groove is preferably 1/5 or less of the thickness of the graphite crucible. Further, the density of the grooves can be set to, for example, 20% or more per unit area of the region where the grooves are formed, from the viewpoint of effectively suppressing the adhesion between the graphite crucible and the quartz crucible. That is,
20% or more of the region is occupied by the groove, and the remaining portion is occupied by the region where the groove is not formed. The shape, arrangement, number and the like of the grooves can be arbitrarily set as long as the adhesion between the graphite crucible and the quartz crucible can be reduced to some extent. For example, as shown in FIG.
A plurality of grooves along the inner periphery of the graphite crucible may be formed in the height direction, or as shown in FIG. 6B, a plurality of grooves extending in the height direction may be formed on the inner wall of the graphite crucible. . Further, as shown in FIG. 6C, the groove in the inner circumferential direction and the groove in the height direction may be combined.

[0030]

EXAMPLES Examples and comparative examples of a crucible for pulling a single crystal according to the present invention will be described below.

[Preparation of Single Crystal Pulling Crucible] A single crystal pulling crucible having a structure combining a quartz crucible having a cylindrical side wall and a graphite crucible having a cylindrical side wall as shown in FIG. 1 was prepared. The outer diameter of the quartz crucible and the inner diameter of the graphite crucible were about 400 mm. The thickness of the quartz crucible was about 8 mm, and the bottom was constituted by a curved surface as shown in FIG. The depth of the quartz crucible was about 300 mm. The thickness of the graphite crucible was about 15 mm, and the inner surface was almost the same shape as the quartz crucible. The upper end of the graphite crucible was about 20 mm lower than the upper end of the quartz crucible. In addition, the graphite crucible has a structure in which a side wall is cylindrical and a round bottom portion is integrated with a receiving base by dividing a member into two. The crucible to be manufactured was to use polycrystalline silicon as a raw material, dissolve it, and hold a melt. This crucible was used such that the liquid level was 150 mm below the upper end of the quartz crucible in a state where the silicon was dissolved.

First, five types of crucibles having different positions and numbers of through holes were prepared. The diameters of the through holes were all 3 mm. The plurality of through-holes were provided at positions where the circumference was substantially equally divided. As shown in Table 1, Example No. In one crucible, six through-holes were provided at substantially equal intervals at a position 20 mm above the position where the melt surface should come. Example No. In two crucibles,
Six through-holes were provided at substantially equal intervals at a position 45 mm above the position where the melt surface should be formed. Example No. In the crucible No. 3, forty through-holes were provided at substantially equal intervals in a portion 20 mm above the position where the melt surface should come. Example N
o. In the crucible 4, each of the crucibles was placed 20 mm, 60 mm, and 90 mm above the position where the melt surface should come.
Through holes were formed individually at equal intervals. Example No. In the crucible No. 5, six through-holes were formed at substantially equal intervals 60 mm above the position where the melt surface should come.

Further, a single crystal pulling crucible having a structure as shown in FIG. 4 was prepared. The dimensions and the like of each part were the same as those of the crucible shown in FIG. 1, but the upper end of the quartz crucible was formed to protrude outward so as to be in contact with the upper end of the graphite crucible. In the crucible having the structure shown in FIG. In the crucible No. 6, six through holes were formed at substantially equal intervals at a position 20 mm above the position where the melt surface should come. Example No. In the crucible No. 7, six through holes were formed at substantially equal intervals at positions 20 mm, 80 mm, and 140 mm above the position where the melt surface should come.

A single crystal pulling crucible having a groove formed on the inner surface of the graphite crucible was also manufactured. Example No. In the same crystal pulling crucible as in No. 1, a depth of 1 mm and a width of 1
A V-shaped groove of mm was formed along the inner circumference. An annular V 1 mm deep and 1 mm wide from the position where the melt surface should be
A plurality of U-shaped grooves were formed such that the distance between the groove centers was 3 mm. Therefore, the density of the groove was 50% per unit surface area above the position where the melt surface should come. In the crucible having such a groove, in Example No. In the crucible No. 8, six through-holes were formed at substantially equal intervals at a position 20 mm above the position where the melt surface should come. Further, in Example No. In the structure of the crucible shown in FIG. A groove was formed on the inner surface of the graphite crucible in the same manner as in No. 8. Example No. 1 obtained in this manner was used. In the crucible No. 9, six through-holes were formed at substantially equal intervals at a position 20 mm above the position where the melt surface should come. V at a density of 50% on the inner surface of graphite crucible
A groove was formed.

On the other hand, as a comparative example, a crystal pulling crucible in which a through hole was not formed in a graphite crucible was manufactured. As shown in Table 1, Comparative Example No. The crucible 1 has a structure in which a graphite crucible and a quartz crucible are combined as shown in FIG.
No through hole was provided. Comparative Example No. The second crucible has a structure in which a graphite crucible and a quartz crucible are combined as shown in FIG. Further, a comparative example in which a through-hole was formed below the position where the melt surface should come was also prepared. As shown in Table 1, Comparative Example N
o. The crucible No. 3 has a structure in which a graphite crucible and a quartz crucible are combined as shown in FIG. 1 and six through holes are provided at substantially equal intervals at a position 20 mm below a position where a melt surface is to be formed. is there.

[Bucking Resistance Test] In a single crystal pulling apparatus as shown in FIG. 7, the crystal pulling crucibles of the above-mentioned Example and Comparative Example were respectively installed, and a buckling resistance test was performed.
In the placed crystal pulling crucible, a lump of polycrystalline silicon was put in the quartz crucible and heated to dissolve the silicon, thereby preparing a melt. The amount of silicon mass to be charged was set so that the surface of the prepared melt was 150 mm below the upper end of the quartz crucible. In the buckling resistance test, the single crystal was not pulled, but the melt was held in the crucible for substantially the same time as the time required for pulling the single crystal. The temperature of the silicon melt is the melting point of silicon single crystal (1420
C.), which is approximately 1470 ° C., which is approximately 50 ° C. By maintaining the melt at such a high temperature, the buckling deformation of the quartz crucible is accelerated. After holding the melt for a predetermined time, the state of the quartz crucible was observed, and the maximum protrusion dimension in the inward deformation as shown in FIGS. 8 and 9 was measured. The results are summarized in Table 1.

[0037]

[Table 1]

As shown in the table, in Example No. 1 in which the through hole was formed within a range of 50 mm above the position where the melt should come.
It can be seen that in the crucibles Nos. 1 to 4, buckling deformation was suppressed even when the melt was held at a higher temperature than usual due to the gas diffusion effect of the through holes. In addition, in Example No. As shown in FIG. 5, when the position of the through-hole exceeds 50 mm above the melt surface, the effect of suppressing the buckling deformation slightly decreases. From this, it can be seen that the position of the through hole is more effective for preventing buckling if the position is within 50 mm above the position where the melt surface should be formed. Also, in Example No. As is clear from comparison of Nos. 1 to 4, it was found that even if the number of through holes was so large, the effect of preventing buckling was not significantly improved.

Further, in Example No. As shown by 6 and 7, in a single crystal pulling crucible combining a quartz crucible having a top end protruding outward and a graphite crucible having a through hole,
The effect of preventing buckling deformation is greater. Also, in Example No. As shown in FIG. 8, the crucible on which the groove processing was performed was the same as that of Example No. It can be seen that there is less buckling deformation than the crucible No. 1.

On the other hand, in Comparative Example No. having no through hole. In the crucibles 1 and 2, the buckling deformation was large. In a crucible (Comparative Example No. 2) in which the upper end portion of the quartz crucible was simply bent without forming a through hole, Comparative Example N
o. Although the value of the maximum protrusion dimension is smaller than that of 1, the effect of preventing buckling deformation is insufficient. Also, in Comparative Example No. in which a through hole was provided below the melt surface. In the crucible No. 3, when the melt was held at a high temperature, a deformation in which the quartz crucible entered the through-hole occurred, and the strength of this portion was reduced. For this reason, when cooling and solidifying with the silicon filled, cracks starting from the through-holes occurred at the beginning of cooling when the melt did not solidify, and the melt leaked. On the other hand, in the crucible of the example according to the present invention, such a situation did not occur, the quartz crucible did not crack until the melt was sufficiently hardened, and no leak of the melt occurred.

[0041]

As described above, the present invention employs a graphite crucible having a plurality of through holes formed only above a position where an initial melt surface is to be formed, and a quartz crucible in the graphite crucible. The gas generated from the fitting surface between the quartz crucible and the graphite crucible is diffused through the through-hole, and buckling deformation of the quartz crucible due to gas pressure can be effectively prevented. Furthermore, if a structure is employed in which the upper end of the quartz crucible is supported by the upper end of the graphite crucible having a through hole, it is possible to prevent deformation due to gas pressure and at the same time prevent deformation due to its own weight. Flexural deformation can be more reliably prevented. The single crystal pulling crucible of the present invention is capable of holding the melt in a good state from the preparation of the raw material melt to the end of the pulling without causing an extreme change in the flow and temperature distribution on the surface of the melt. It can significantly contribute to improvement in productivity.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a specific example of a crystal pulling crucible according to the present invention.

FIG. 2 is a schematic view showing a preferred range of a portion where a through hole is to be formed in the crystal pulling crucible according to the present invention.

FIG. 3 is a perspective view schematically showing an example of arrangement of through holes formed in a graphite crucible according to the present invention.

FIG. 4 is a cross-sectional view schematically showing another specific example of the single crystal pulling crucible according to the present invention.

FIG. 5 is a cross-sectional view schematically showing a further example of a single crystal pulling crucible according to the present invention.

FIG. 6 is a schematic view showing a state where a groove is formed in a graphite crucible according to the present invention.

FIG. 7 is a cross-sectional view schematically showing an example of a single crystal pulling apparatus used for the Czochralski method.

FIG. 8 is a cross-sectional view schematically illustrating a buckling deformation state of a quartz crucible in a single crystal pulling crucible in which a graphite crucible and a quartz crucible are combined.

FIG. 9 is a cross-sectional view taken along the line AA ′ of FIG. 8, schematically showing the state of the buckling deformation of the quartz crucible with emphasis.

[Explanation of symbols]

 10, 20, 30 Crystal pulling crucible 12, 22, 32 Graphite crucible 14, 24, 34 Quartz crucible 16, 26, 36 Through hole 38 V-shaped groove

Claims (5)

[Claims] 1. A crystal pulling crucible in which an inner container made of quartz is fitted in an outer container made of graphite, wherein a side wall of the outer container has a through hole communicating with the inner container from outside the outer container. A plurality of through holes are formed, and the through-hole is formed only above a position where a melt surface for pulling a crystal should be formed in an early stage of use, a crucible for pulling a crystal. 2. The crucible according to claim 1, wherein an upper end of the inner container has a shape protruding outward so as to be supported by an upper end of the outer container. 3. The through-hole is formed in a range not exceeding 50 mm above a position where the melt surface is to be formed, and the through-hole is formed along the outer periphery of the outer container at 5 mm per circumference. The crystal pulling crucible according to claim 1, wherein the crucible is formed at a density of not less than one. 4. A groove having a depth of 0.5 mm or more is further formed in a portion of the inner wall of the outer container above a position where the melt surface is to be formed. 4. The crucible for pulling a crystal according to any one of items 1 to 3. 5. A crystal pulling part made of graphite for supporting a crucible made of quartz from outside in crystal pulling, comprising a container having an inner surface capable of fitting the crucible made of quartz therein. A plurality of through-holes are formed in a side wall of the container, and the through-holes are used to fit a crucible made of quartz into the crucible and hold the melt for crystal pulling. A crystal pulling component, which is provided only at a position higher than a predetermined height in the height direction of the container so as to be located only above a surface.