Quartz glass crucible

Abstract

To provide a stable self-standing quartz glass crucible when a cylindrical quartz glass crucible with a bottom for growing a single crystal silicon ingot by a CZ method is arranged in a cylindrical graphite crucible with a bottom.SOLUTION: In a quartz glass crucible for growing a single crystal silicon ingot by a CZ method, the quartz glass crucible is a cylindrical shape with a bottom, and has: a cylindrical straight body; a first curved part that continuously extends to a lower edge of the straight body and has a first curvature R1; a second curved part that continuously extends to the first curved part and has a second curvature R2; and a bottom that continuously extends to the second curved part. The first curvature R1 and the second curvature R2 have a relation of R1<R2. An outer surface of the bottom forms a flat surface orthogonal to a center axis of the quartz glass crucible or forms a concave surface recessed from the flat plane.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a quartz glass crucible for growing a single crystal silicon ingot by the Czochralski method (hereinafter referred to as the "CZ method"). [Background technology]

[0002] The CZ method is a well-known method for producing single crystals. In particular, the CZ method is widely used industrially for the production of single crystal silicon, which is used as a material for semiconductor electronic components. The CZ method involves melting polycrystalline silicon or the like filled in a quartz glass crucible using a heater, immersing a seed crystal in the surface of the silicon melt, and then rotating the seed crystal and the quartz glass crucible while pulling the seed crystal upward to grow a single crystal with the same crystal orientation as the seed crystal.

[0003] Fig. 4 is a conceptual diagram showing a typical pulling apparatus used to pull a single crystal by the CZ method. As shown in Fig. 4, the single crystal pulling apparatus 10 includes a pulling chamber 12, a crucible 13 provided in the pulling chamber 12, a heater 14 arranged around the crucible 13, a crucible holding shaft 15 for rotating and elevating the crucible 13 and its rotation / elevation mechanism (not shown), a seed chuck 17 for holding a silicon seed crystal 16, a wire 18 for pulling the seed chuck 17, and a winding mechanism (not shown) for rotating or winding the wire 18. A heat insulator 19 is disposed around the outside of the heater 14. Single crystal silicon 20 is pulled from the silicon melt 11 (raw material) by the wire 18.

[0004] The crucible 13 placed in the single crystal pulling apparatus 10 is composed of a cylindrical quartz glass crucible with a bottom that contains the raw material melt, and a cylindrical graphite crucible with a bottom (sometimes called a "carbon susceptor") that contains the quartz glass crucible inside (for example, Patent Documents 1 and 2, etc.). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-17245 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-139356 Summary of the Invention [Problem to be solved by the invention]

[0006] Although quartz glass crucibles are manufactured to dimensions that can be accommodated inside a graphite crucible, it is difficult to manufacture them so that their outer surface is in complete contact with the inner surface of the graphite crucible due to manufacturing errors and other factors. The inventors conducted extensive research and found that, although the outer surface of a quartz glass crucible is convexly curved to match the shape of the inner surface of the graphite crucible, individual differences in the shapes of the outer surface of the quartz glass crucible and the inner surface of the graphite crucible, such as manufacturing errors, can cause point contact between the bottom of the outer surface of the quartz glass crucible 13A and the inner surface of the graphite crucible 13B when the quartz glass crucible 13A is placed inside the graphite crucible 13B, making the quartz glass crucible 13A unstable, as shown in Figure 5. If the quartz glass crucible 13A shakes inside the graphite crucible 13B, the quartz glass crucible 13A may break inside the graphite crucible 13B. Furthermore, during single crystal production, the silicon melt shakes, causing vibrations on the melt surface that make it difficult to pull up the single crystal silicon. This not only causes the quartz glass crucible 13A to become eccentric when pulling up the single crystal silicon, but also makes it impossible to supply uniform heat to the silicon ingot, leading to a deterioration in the quality of the silicon ingot.

[0007] To address the above-mentioned problems, it is conceivable to select and combine a quartz glass crucible 13A and a graphite crucible 13B that are compatible with each other to produce a stable crucible 13. However, since there is no other way than to find a compatible combination of a quartz glass crucible 13A and a graphite crucible 13B by trial and error, not only is this extremely inefficient, but it is not always possible to obtain a desirable combination.

[0008] The present invention has been made to solve the above problems, and an object thereof is to provide a bottomed cylindrical quartz glass crucible that can stably stand on its own when the bottomed cylindrical quartz glass crucible for growing a single crystal silicon ingot by the CZ method is disposed inside a bottomed cylindrical graphite crucible.

Means for Solving the Problems

[0009] The present invention has been made to achieve the above object, and is a quartz glass crucible for growing a single crystal silicon ingot by the CZ method, wherein the quartz glass crucible includes a cylindrical straight body portion, and a first curvature radius R1 continuous with the lower end of the straight body portion and having a first curved portion, a second curvature radius R2 continuous with the first curved portion and having a second curved portion, and a bottomed cylindrical shape having a bottom continuous with the second curved portion, and the first curvature radius R1 and the second curvature radius R2 are in a relationship of R1 < R2, and the outer surface of the bottom forms a flat surface orthogonal to the central axis of the quartz glass crucible, or a concave surface recessed from the flat surface.

[0010] According to such a quartz glass crucible, when the quartz glass crucible is disposed inside the graphite crucible, it can stably stand on its own without depending on the individual differences between the quartz glass crucible and the graphite crucible. Further, with the quartz glass crucible of the present invention, even during normal storage, it can be stably stored with the bottom of the quartz glass crucible facing down in the same state as when it is disposed in the graphite crucible, so that the working efficiency and safety can also be improved. Furthermore, it is possible to suppress changes and disturbances in the convection state of the silicon melt during the growth of a single crystal silicon ingot by the CZ method.

[0011] At this time, the first curvature radius R1 is 120 mm ≦ R1 ≦ 240 mm, and the second curvature radius R2 can be a quartz glass crucible of 750 mm ≦ R2 ≦ 880 mm.

[0012] This makes it possible to further suppress changes and disturbances in the convection state of the silicon melt.

[0013] In this case, the width of the bottom portion of the quartz glass crucible as viewed from a cross section including the central axis of the quartz glass crucible may be 60 mm or more.

[0014] This makes it possible to more stably prevent point contact between the outer surface of the bottom of the quartz glass crucible and the inner surface of the bottom of the graphite crucible. [Effects of the Invention]

[0015] As described above, the quartz glass crucible of the present invention can stably stand on its own when placed inside a graphite crucible, regardless of individual differences between the quartz glass crucible and the graphite crucible. Furthermore, the quartz glass crucible can be stably stored with its bottom facing down, in the same state as when placed inside the graphite crucible, thereby improving work efficiency and safety. Furthermore, it can suppress changes and disturbances in the convection state of the silicon melt when growing a single-crystal silicon ingot by the CZ method. [Brief explanation of the drawings]

[0016] [Figure 1] 1 shows an example of a quartz glass crucible according to the present invention. [Figure 2] 1 shows a state in which a quartz glass crucible according to the present invention is placed in a graphite crucible. [Figure 3] 1 shows another example of a quartz glass crucible according to the present invention. [Figure 4] FIG. 1 shows a conceptual diagram illustrating a pulling device. [Figure 5] This shows the state when a quartz glass crucible is placed inside a graphite crucible (conventional example). DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in detail below, but the present invention is not limited thereto.

[0018] As described above, when a bottomed cylindrical quartz glass crucible for growing a single crystal silicon ingot by the CZ method is disposed inside a bottomed cylindrical graphite crucible, a quartz glass crucible that can stably stand on its own has been demanded.

[0019] As a result of intensive studies on the above problems, the present inventors have found a quartz glass crucible for growing a single crystal silicon ingot by the CZ method, wherein the quartz glass crucible has a cylindrical straight body portion, and a first curvature radius R1 continuous with the lower end of the straight body portion, a first curved portion having R1, a second curvature radius R2 continuous with the first curved portion, a second curved portion having R2, and a bottomed cylindrical shape having a bottom continuous with the second curved portion, and the first curvature radius R1 and the second curvature half diameter R2 are in the relationship of R1 < R2, and the outer surface of the bottom forms a flat surface orthogonal to the central axis of the quartz glass crucible, or a concave surface recessed from the flat surface. According to such a quartz glass crucible, when the quartz glass crucible is disposed inside the graphite crucible, it can stably stand on its own without depending on individual differences between the quartz glass crucible and the graphite crucible, and also the working efficiency and safety can be improved during normal storage. Furthermore, it has been found that the change and disturbance of the convection state of the silicon melt during the growth of the single crystal silicon ingot by the CZ method can be suppressed, and the present invention has been completed.

[0020] Hereinafter, the present invention will be described with reference to the drawings.

[0021] First, in a crucible for growing a single crystal silicon ingot by the CZ method, when a bottomed cylindrical quartz glass crucible is disposed inside a bottomed cylindrical graphite crucible, the inventor studied a quartz glass crucible that can stably stand on its own. As a result, it was found that due to individual differences such as manufacturing errors in the outer surface shape of the bottom when manufacturing the quartz glass crucible, the outer surface of the bottom of the quartz glass crucible and the inner surface of the bottom of the graphite crucible are in point contact, making the quartz glass crucible unstable. And if the shape of the outer surface of the bottom of the quartz glass crucible forms a flat surface (hereinafter simply referred to as "flat surface") orthogonal to the central axis of the quartz glass crucible, or a concave surface (hereinafter simply referred to as "concave surface") recessed from this flat surface, point contact can be suppressed. As a result, it was found that the quartz glass crucible is stably placed inside the graphite crucible.

[0022] However, simply making the shape of the outer surface of the bottom of a conventional quartz glass crucible a flat surface or a concave surface may reduce the strength due to the reduced thickness of the bottom of the quartz glass crucible, or may change the heat transfer balance in the crucible during single crystal silicon growth and affect the convection state of the silicon melt. On the other hand, if an attempt is made to ensure the thickness of the bottom of the quartz glass crucible, it is necessary to change the inner surface shape of the quartz glass crucible. However, it was found that changing the inner surface shape of the quartz glass crucible affects the convection state of the silicon melt. Therefore, the shape of the quartz glass crucible is such that a first curved portion having a first curvature radius R1 is continuous with the lower end of the cylindrical straight body portion, and a second curved portion having a second curvature radius R2 is continuous with the first curved portion, and it has a bottomed cylindrical shape with a bottom continuous with the second curved portion, and by satisfying the relationship R1 < R2, it was found that a quartz glass crucible can be obtained that has a flat surface or a concave surface for the shape of the outer surface of the bottom and does not affect the convection state of the silicon melt, and the present invention was completed.

[0023] (First Embodiment) FIG. 1 shows an example of a quartz glass crucible according to the present invention. This quartz glass crucible 1A has a cylindrical straight body portion 2 and a first curvature radiusA first curved portion 3 having R1, and a second curvature continuous with the first curved portion 3 radius It is a bottomed cylindrical shape having a second curved portion 4 having R2 and a bottom portion 5 continuous with the second curved portion 4, and satisfies the relationship R1 < R2. The outer surface shape of the bottom portion 5 is a flat surface 5A orthogonal to the central axis 6 of the quartz glass crucible.

[0024] Fig. 2 shows the state when the quartz glass crucible 1A according to the present invention is installed in a graphite crucible. As shown in Fig. 1, since the bottom portion 5 of the quartz glass crucible 1A is a flat surface 5A orthogonal to the central axis 6 of the quartz glass crucible, as shown in Fig. 2, the outer surface of the bottom portion of the quartz glass crucible 1A and the inner surface of the bottom portion of the graphite crucible 13B are prevented from making point contact, and when the quartz glass crucible 1A is arranged inside the graphite crucible 13B, it can stand stably and independently. As shown in Fig. 2, although a gap is formed between the quartz glass crucible 1A and the graphite crucible 13B, since the outer edge of the bottom portion of the quartz glass crucible 1A and the inner surface of the graphite crucible 13B are in a surface contact state, problems such as rattling do not occur.

[0025] Moreover, this quartz glass crucible 1A is continuous with the lower end of the cylindrical straight body portion 2 and has a first curvature half diameter A first curved portion 3 having R1, and a second curvature continuous with the first curved portion 3 radius It has a second curved portion 4 having R2, and is configured to satisfy the relationship R1 < R2. Therefore, even in the case of forming the flat surface 5A, it hardly affects the shape of the inner surface of the quartz glass crucible. Therefore, it hardly affects the convection state of the silicon melt during the growth of the single crystal silicon ingot by the CZ method.

[0026] In addition, conventionally, when storing a quartz glass crucible, a jig is used to stably support the bottom of the quartz glass crucible, or the quartz glass crucible is placed with the bottom facing up and the opening facing down. However, since quartz glass crucibles used to grow large-diameter single-crystal silicon ingots are particularly large, turning the quartz glass crucible upside down requires a great deal of effort and involves the risk of it falling. On the other hand, the quartz glass crucible of the present invention can be stably stored with the bottom facing down, in the same position as when placed in a graphite crucible, even during normal storage, without using a special jig, etc., thereby improving work efficiency and safety.

[0027] In addition, the first curvature radius R1 and second curvature radius Although R2 is not particularly limited, it is preferable that R2 is 120 mm≦R1≦240 mm and 750 mm≦R2≦880 mm, which makes it possible to more stably suppress changes and disturbances in the convection state of the silicon melt.

[0028] Although there are no particular limitations on the diameter of the quartz glass crucible 1A, in the present invention, it is preferable to use a crucible with a particularly large diameter, for example, 32 inches (approximately 800 mm) or more.

[0029] The size of the bottom 5 is the width W (hereinafter referred to as "W") of the quartz glass crucible 1A as viewed from a cross section including the central axis 6 thereof. bottom of section It is preferable that the width W) is 60 mm or more. If it is in this range, point contact between the outer surface of the bottom of the quartz glass crucible and the inner surface of the bottom of the graphite crucible can be more stably suppressed.

[0030] The graphite crucible for placing the quartz glass crucible has an inner surface that is continuous with the cylindrical inner surface of the straight body and the lower end of the straight body, and has a first curvature radius a first curved portion having R3 and a second curvature continuous with the first curved portion; radius The crucible has a cylindrical shape with a bottom and a second curved portion having a curvature R4. In the relationship between the quartz glass crucible and the graphite crucible, the first curvature of the quartz glass crucible is radius R1 is R1=R3±50mm, the second curvature of the quartz glass crucible radius It is preferable that R2 satisfies R2 = R4 ± 50 mm. A combination of a quartz glass crucible and a graphite crucible that satisfies this relationship can further suppress changes and disturbances in the convection state of the silicon melt.

[0031] (Second embodiment) FIG. 3 shows another example of a quartz glass crucible according to the present invention. Note that a description of the same configuration as in FIG. 1 will be omitted where appropriate. In the quartz glass crucible 1B according to this embodiment, the outer surface of the bottom 5 has a concave surface 5B recessed from a flat surface perpendicular to the central axis 6 of the quartz glass crucible. Even with this shape, the same effects as in the first embodiment can be achieved. Note that the concave surface 5B is not particularly limited as long as it has a shape recessed from a flat surface perpendicular to the central axis 6 of the quartz glass crucible 1B. However, from the viewpoint of stability, it is preferable for the shape to be symmetrical with respect to the central axis 6, in other words, for the edge of the recess to be circular with the center at the central axis 6 when the quartz glass crucible 1B is viewed from the outer surface side of the bottom in the direction of the central axis 6. [Example]

[0032] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0033] As shown below, 32-inch (approximately 800 mm) diameter quartz glass crucibles, each with a different shape except for the straight body, were placed inside a graphite crucible and evaluated. The evaluation began by checking whether there was any rattle when the quartz glass crucible was placed inside the graphite crucible. The rattle was evaluated by placing the quartz glass crucible on a horizontal stand, and applying a force gauge from 200 mm from the side at a height of 30 cm from the stand. 2 When a force of 8 N was applied to the area, if the pressed side of the quartz glass crucible was lifted and tilted by 10 degrees or more, it was judged to have wobble (×). Note that the perpendicular direction to the ground was set as 0 degrees, and if it was tilted before the force was applied, that angle was also added.

[0034] Thereafter, a single crystal silicon ingot was grown by the CZ method. The change and disturbance of the silicon melt convection during the growth of the single crystal silicon ingot were evaluated based on the presence or absence of dislocations in the grown single crystal silicon ingot. At this time, the graphite crucible for placing the quartz glass crucible had an inner surface with a cylindrical straight body portion and a first curvature, which was continuous with the lower end of the straight body portion. radius A first curved portion having R3=180 mm and a second curvature continuous with the first curved portion radius It has a second curved portion with R4=815 mm.

[0035] (Comparative Example 1) Cylindrical straight body, first curvature radius R1=180mm first curvature, second curvature radius A silica glass crucible having a second curved portion with R2=815 mm was used. In this case, the outer surface of the bottom of the silica glass crucible according to Comparative Example 1 had a convex shape.

[0036] (Comparative Example 2) Cylindrical straight body, first curvature radius A quartz glass crucible was used, which had a first curved portion with R1=180 mm and a flat surface with a cross-sectional bottom width W of 570 mm.

[0037] Example 1 Cylindrical straight body, first curvature radius R1=180mm first curvature, second curvature radius A quartz glass crucible was used, which had a second curved portion with R2=815 mm and a bottom portion with a concave surface with a cross-sectional bottom width W of 60 mm.

[0038] Example 2 A quartz glass crucible similar to that used in Example 1 was used, except that the cross-sectional bottom width W was set to 50 mm.

[0039] Example 3 Cylindrical straight body, first curvature radius R1=130mm first curvature, second curvature radiusA quartz glass crucible was used, which had a second curved portion with R2=765 mm and a flat bottom with a cross-sectional bottom width W of 255 mm.

[0040] Example 4 First curvature radius R1=230mm, second curvature radius The same quartz glass crucible as in Example 3 was used, except that R2=865 mm and the cross-sectional bottom width W was 140 mm.

[0041] Example 5 First radius of curvature R1 = 110 mm, second radius of curvature R2 = 815 mm m and The same quartz glass crucible as in Example 4 was used, except that the above-mentioned

[0042] Example 6 First curvature radius The same quartz glass crucible as in Example 5 was used, except that R1=250 mm.

[0043] Example 7 First curvature radius R1=180mm, second curvature radius The same quartz glass crucible as in Examples 5 and 6 was used, except that R2=740 mm.

[0044] Example 8 Second curvature radius The same quartz glass crucible as in Example 7 was used, except that R2=890 mm.

[0045] Table 1 shows the shape data and evaluation results of the quartz glass crucibles of Comparative Examples 1 and 2 and Examples 1 to 8.

[0046] [Table 1]

[0047] As shown in Table 1, it can be seen that, as in Examples 1 - 8 and Comparative Example 2, by making the outer surface shape of the bottom of the quartz glass crucible a flat surface or a concave surface, the quartz glass crucible can be stably self - standing inside the graphite crucible. However, in Comparative Example 2 without the second curved portion, changes and disturbances occurred in the convection of the silicon melt. On the other hand, as in Examples 1 - 8, a first curvature radius radius R1 having a first curved portion, and a second curvature radius radius By using a quartz glass crucible provided with a second curved portion having R2, it can also be seen that changes and disturbances in the convection of the silicon melt during the growth of the single - crystal silicon ingot can be suppressed. Further, the quartz glass crucibles of Examples 1 - 8 can be stably stored with the bottom of the quartz glass crucible facing down in the same state as when placed in the graphite crucible without using special fixtures or the like even during normal storage, and the working efficiency and safety can also be improved.

[0048] Note that the present invention is not limited to the above - described embodiments. The above - described embodiments are examples, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same operational effects is included in the technical scope of the present invention.

Explanation of Signs

[0049] 1A, 1B... Quartz glass crucible, 2... Straight body portion, 3... First curved portion, 4... Second curved portion, 5... Bottom, 5A... Flat surface, 5B... Concave surface, 6... Central axis, 10... Single - crystal pulling device, 11... Silicon melt, 12... Pulling chamber, 13... Crucible, 13A... Quartz glass crucible, 13B... Graphite crucible, 14... Heater, 15... Crucible holding shaft, 16... Seed crystal, 17... Seed chuck, 18... Wire, 19... Heat insulator, 20... Single - crystal silicon. W... bottom of section [[ID= 29]]Width.

Claims

1. A quartz glass crucible for growing a single crystal silicon ingot by the CZ method, comprising: the quartz glass crucible is a bottomed cylindrical crucible having a cylindrical body portion, a first curved portion continuing from the lower end of the body portion and having a first radius of curvature R1, a second curved portion continuing from the first curved portion and having a second radius of curvature R2, and a bottom portion continuing from the second curved portion; the first curvature radius R1 and the second curvature radius R2 have a relationship of R1<R2, The outer surface of the bottom portion forms a concave surface that is recessed toward the inner surface of the bottom portion with respect to a flat surface perpendicular to the central axis of the quartz glass crucible, The quartz glass crucible is characterized in that the shape of the inner surface thereof is a concave shape having the straight body portion, the first curved portion continuing from the lower end of the straight body portion and having the first radius of curvature R1, the second curved portion continuing from the first curved portion and having the second radius of curvature R2, and the bottom portion continuing from the second curved portion.

2. the first radius of curvature R1 is 120 mm≦R1≦240 mm, 2. The quartz glass crucible according to claim 1, wherein the second radius of curvature R2 satisfies the relationship 750 mm≦R2≦880 mm.

3. 3. The quartz glass crucible according to claim 1, wherein the width of the bottom portion as viewed from a cross section including the central axis of the quartz glass crucible is 60 mm or more.

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