Quartz glass crucible and its manufacturing method

Abstract

To provide a quartz glass crucible and a production method thereof capable of improving a yield of a silicon single crystal while suppressing crucible deformation.SOLUTION: A quartz glass crucible to draw up a silicon single crystal includes a bottom part having a predetermined curvature, a lower corner having a predetermined curvature formed around the bottom part, and a straight body part 7 extending upward from the lower corner. The straight body part has a thickness t1 of 70% or less of the thickness t2 of the lower corner and the bottom part has a thickness t3 of 80% or more of the thickness t2 of the lower corner. A production method of a quartz glass crucible includes steps for: supplying raw material quartz powder to a crucible molding die to form a crucible molded body having at least one layer while rotating an inner member of the die around an axis and heating and fusing the inside of the crucible molded body to form the quartz glass crucible. In the step for supplying the raw material quartz powder to form the crucible molded body, a supply amount of the raw material quartz powder is adjusted.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a quartz glass crucible for pulling silicon single crystals by the Czochralski method (hereinafter referred to as the "CZ method"), and a method for manufacturing the same. [Background technology]

[0002] The CZ method is widely used for growing silicon single crystals. In this method, a seed crystal is brought into contact with the surface of molten silicon contained in a quartz glass crucible, and while the crucible is rotated, the seed crystal is pulled upward while rotating in the opposite direction, forming a single crystal at the bottom of the seed crystal. As the diameter of the silicon single crystals being pulled increases, quartz glass crucibles are becoming larger every year. These larger crucibles allow for a larger load of polycrystalline silicon, improving throughput. However, they are used in harsh environments, requiring longer melting times and higher output from carbon heaters.

[0003] As shown in Figure 6, a silica glass crucible 50 is composed of a cylindrical straight body portion 51 that is open at the top end, lower corners 52 formed around the bottom end of the straight body portion 51, and a bottom portion 53 formed inside the lower corners 52. As the silica glass crucible 50 becomes larger, the problem of deformation of the silica glass crucible 50 during single crystal production becomes more pronounced, and for this reason, methods have been adopted such as increasing the viscosity of the silica glass crucible 50 or increasing the thickness of the straight body portion to 20 mm or more to compensate for the viscosity of quartz.

[0004] Patent document 1 proposes a single crystal growth method that prevents deformation of the silica glass crucible 50 by specifying a certain relationship between the viscosity of the quartz that constitutes the straight body portion 51 of the silica glass crucible 50 and the thickness of the straight body portion 51. However, in the quartz glass crucible disclosed in Patent Document 1, the crucible shape is maintained as it was in the conventional form, but the viscosity of the quartz or the thickness of the straight body portion 51 is increased, which posed the following problems.

[0005] First, there is a physical limit to how much the viscosity of quartz can be increased, and so if one tries to forcefully increase the viscosity, the manufacturing process for the quartz glass crucible 50 itself becomes complicated, which is a problem. Furthermore, the method of increasing the thickness of the body portion 51 requires the lower corners 52 to be extremely thick in order to support the thick body portion 51, which makes the quartz crucible itself heavy, complicates the manufacturing process and handling, and leads to an increase in the amount of raw material required for the quartz glass crucible 50, resulting in increased costs.

[0006] To address this issue, Patent Document 2 discloses a quartz glass crucible 50 having a structure in which the thickness of the body portion 51 is 10 to 15 mm and is 70 to 80% of the thickness of the lower corners 52, making it thinner than the lower corners 52. In this way, the quartz glass crucible disclosed in Patent Document 2 can suppress deformation such as sinking of the straight body portion 51 or inward sagging of the straight body portion 51 even when pulling a large-diameter single crystal by minimizing the weight of the straight body portion 51 as much as possible to reduce its own weight and by reducing the load on the lower corners 52. Furthermore, it can be manufactured using a general manufacturing process for quartz glass crucibles, which can suppress increases in costs. In the quartz glass crucible disclosed in Patent Document 2, the thickness of the crucible bottom 53 is set to be equal to or less than the thickness of the lower corners 52 . [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-47092 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-041723 Summary of the Invention [Problem to be solved by the invention]

[0008] According to the quartz glass crucible disclosed in Patent Document 2, the thickness of the lower corners 52 is greater than the thickness of the body portion 51, so deformation of the crucible can be suppressed until the height of the silicon melt decreases to the position of the lower corners 52. Furthermore, at this time, pressure due to the load of the silicon melt is applied to the crucible bottom 53, so even if the crucible bottom 53 is relatively thin and has low durability, deformation of the crucible bottom 53 can be prevented.

[0009] However, as the pulling of the silicon single crystal progresses and the silicon molten liquid M reaches below the lower corner 52 as shown in Figure 7, the load of the molten liquid M becomes smaller, and the combined load of the straight body portion 51 and the lower corner 52 is applied heavily to the crucible bottom 53, resulting in the problem of the crucible bottom 53 deforming as shown in the figure.

[0010] The present invention has been made under the above circumstances, and aims to provide a quartz glass crucible used for pulling silicon single crystals, which can improve the yield of silicon single crystals while suppressing crucible deformation, and a method for manufacturing the same. [Means for solving the problem]

[0011] The quartz glass crucible of the present invention, which has been made to solve the above-mentioned problems, is a quartz glass crucible for pulling silicon single crystals, and is characterized in that it has a bottom portion having a predetermined curvature, a lower corner formed around the bottom portion and having a predetermined curvature, and a straight body portion extending upward from the lower corner, and the thickness dimension of the straight body portion is formed to be 70% or less of the thickness dimension of the lower corner, and the thickness dimension of the bottom portion is formed to be 80% or more of the thickness dimension of the lower corner. Furthermore, it is desirable that the position where the thickness dimension is greatest is located closer to the bottom than the lower corner, and is located within ±6% of the outer diameter of the quartz glass crucible from the radial point of contact between the ridge line of the bottom and the ridge line of the lower corner.

[0012] According to the present invention, the thickness of the body portion is set to 70% or less of the thickness of the lower corners. As a result, even if the silicon melt decreases to the vicinity of the lower corners during single crystal pulling, the lower corners have enough durability to bear the load of the body portion, thereby preventing the body portion from sinking or sagging inward. Furthermore, the thickness of the crucible bottom is set to 80% or more of the thickness of the lower corners, which allows the bottom to have enough durability to withstand the load of the straight body and the lower corners, even if the silicon melt decreases to a position lower than the lower corners during single crystal pulling, preventing deformation of the crucible bottom. As a result, it is possible to improve the yield of silicon single crystals while suppressing deformation of the crucible.

[0013] The method for manufacturing a quartz glass crucible of the present invention, which has been made to solve the above-mentioned problems, is a method for manufacturing a quartz glass crucible, and comprises the steps of rotating the inner member of the crucible forming mold around an axis while supplying raw quartz powder to form at least one layer of crucible formed body, and heating and melting the crucible formed body from the inside to form a quartz glass crucible, and is characterized in that in the step of supplying the raw quartz powder to form at least one layer of crucible formed body, the amount of raw quartz powder supplied is adjusted so that the thickness dimension of the straight body portion is 70% or less of the thickness dimension of the lower corner, and the thickness dimension of the bottom portion is 80% or more of the thickness dimension of the lower corner. Alternatively, in the step of heating and melting the crucible body from the inside to form a quartz glass crucible, further raw quartz powder may be supplied and the amount of raw quartz powder supplied may be adjusted to form the thickness dimension of the straight body portion to 70% or less of the thickness dimension of the lower corner, and the thickness dimension of the bottom portion to 80% or more of the thickness dimension of the lower corner. According to this method, the above-described quartz glass crucible according to the present invention can be obtained. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a quartz glass crucible used for pulling silicon single crystals, which can improve the yield of silicon single crystals while suppressing crucible deformation, and a method for manufacturing the same. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view of a quartz glass crucible according to the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a portion of the vitreous silica crucible of FIG. [Figure 3] FIG. 3 is a graph showing the change in thickness of each portion of the crucible in the present invention. [Figure 4] FIG. 4 is a graph showing the change in thickness of each portion of a modified crucible according to the present invention. [Figure 5] FIG. 5 is a schematic diagram of an apparatus for manufacturing the quartz glass crucible of FIG. [Figure 6] FIG. 6 is a cross-sectional view of a conventional quartz glass crucible. [Figure 7] FIG. 7 is a cross-sectional view for explaining the problem with the silica glass crucible of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of a quartz glass crucible and a method for manufacturing the same according to the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view of a silica glass crucible 1 according to the present invention. Fig. 2 is an enlarged cross-sectional view of a part of the silica glass crucible of Fig. 1. This quartz glass crucible 1 is used in, for example, a single crystal pulling apparatus (not shown), and is used in the apparatus while being held by a carbon susceptor (not shown). That is, in the single crystal pulling apparatus, raw silicon is melted in a silica glass crucible 1, and a silicon single crystal is pulled up from the melt.

[0017] The quartz glass crucible 1 is formed, for example, to a diameter (caliber) of 32 inches and has a bottom 9 with a predetermined curvature (first curvature), a lower corner 8 formed around the bottom 9 and with a predetermined curvature (second curvature), and a straight body portion 7 extending upward from the lower corner 8. As shown in Fig. 1, an outer layer 2 is formed on the outermost side of the body portion 7, extending from the crucible upper end 6 to below the body portion 7. The outer layer 2 is formed of an Al-doped quartz glass layer to which, for example, Al is added as a crystallization promoter.

[0018] Specifically, before use (before high-temperature heating), the outer layer 2 (crystallization promoter-added layer) has, for example, a primary added raw material with an Al concentration of 100 ppm dispersed in glass, and the Al concentration in the outer layer 2 is 25 ppm. That is, the layer is formed in a state in which parts that will vitrify and parts that will crystallize are mixed. After use (after high-temperature heating), the outer layer 2 does not become a single crystalline layer, but the primary added raw material crystallizes, and glass parts and crystallized parts are mixed.

[0019] Returning to FIG. 1, an opaque intermediate layer 3 made of natural silica glass is formed inside the outer layer 2. Furthermore, inside this opaque intermediate layer 3, a transparent inner layer 4 is formed, which is made of high-purity synthetic raw material quartz glass (or natural raw material quartz glass) that comes into contact with molten silicon when pulling up the silicon single crystal.

[0020] Here, "opaque" means that the quartz glass contains many bubbles (pores) and appears cloudy. The natural quartz layer refers to a silica glass layer produced by melting natural raw materials such as quartz, and the synthetic quartz layer refers to a silica glass layer produced by melting synthetic raw materials synthesized by hydrolysis of silicon alkoxide, for example.

[0021] As described above, the outer layer 2 is not formed on the entire outside of the crucible. That is, the outer layer 2 is not formed on the lower corners 8 and the bottom 9, but is formed only on the body portion 7. That is, as shown in the figure, the lower corners 8 and bottom 9 have a two-layer structure formed by an opaque outer layer 5 made of natural raw quartz glass formed continuously from the opaque intermediate layer 3 of the straight body portion 7, and a transparent inner layer 4 made of synthetic raw quartz glass (or natural raw quartz glass). This is to soften the lower corners 8 and bottom 9 (opaque outer layer 5 ) and bring them into close contact with the carbon susceptor supporting the silica glass crucible 1 in the initial stage of the single crystal pulling.

[0022] 2 is set to be 70% or less of the thickness t2 of the lower corner 8. As a result, even if the silicon melt decreases to the vicinity of the lower corner 8 during single crystal pulling, the lower corner 8 has enough durability to bear the load of the straight body 7, thereby preventing the straight body 7 from sinking or deforming inwardly. If the thickness dimension t1 of the straight body portion 7 is greater than 70% of the thickness dimension t2 of the lower corner 8, when the silicon melt decreases to the vicinity of the lower corner 8 during single crystal pulling, the lower corner 8 does not have enough durability to withstand the load of the straight body portion 7, and deformation of the quartz glass crucible 1 cannot be prevented.

[0023] Furthermore, the thickness dimension t3 of the bottom 9 is formed to be 80% or more of the thickness dimension t2 of the lower corner 8. Here, Figure 3 is a graph showing the change in thickness at each part of the silica glass crucible 1. The vertical axis of this graph represents thickness, and the horizontal axis represents each part. As is clear from this graph, the bottom 9 has a thickness that is 80% or more of the thickest part, the lower corner 8, and the thickness of the silica glass crucible 1 is formed to be gradually thinner from the lower corner 8 toward the opening of the straight body part 7 (the graph also shows an example of a conventional lower corner with the thickest thickness). More specifically, the thickness of the bottom portion 9 is 150% or less, and preferably 110% or more and 130% or less, of the thickest lower corner 8. The thickness of the body portion 7 is 60% or less, and preferably 40% or more and 50% or less, of the thickest lower corner 8.

[0024] This allows the bottom 9 to have enough durability to withstand the load of the body 7 and the lower corner 8, even if the silicon melt decreases to a position lower than the lower corner 8 during single crystal pulling, thereby preventing deformation of the bottom 9. If the thickness dimension t3 of the bottom 9 is less than 80% of the thickness dimension t2 of the lower corner 8, when the silicon melt decreases to a position lower than the lower corner 8 during single crystal pulling, the bottom 9 will not be durable enough to withstand the load of the straight body 7 and the lower corner 8, and deformation of the bottom 9 may occur.

[0025] Furthermore, the position where the thickness of the silica glass crucible 1 is at its maximum is located on the bottom side of the lower corner 8 as shown in Fig. 2, and it is particularly desirable that the maximum position is located within a range of ±6% of the outer diameter of the silica glass crucible from the contact point P between the ridgeline of the bottom 9 and the ridgeline of the lower corner 8 in the radial direction. In this case, the position of the thickest part will move from the lower corner 8 toward the bottom 9 as shown in the graph of Fig. 4 (present invention 2). This makes it possible to maximize the effect of suppressing deformation of the bottom portion 9 when the silicon melt decreases to a position lower than the lower corner 8.

[0026] The Al concentration of the Al-doped silica glass of the outer layer 2 is in the range of 10 to 300 ppm, and the grain size distribution of each crystal grain is such that 90% of all crystal grains fall within the range of 50 to 400 μm. In this way, by distributing crystal grains in the glass layer of the outer layer 2, the tensile stress that occurs between the glass layer and the opaque intermediate layer 3 is dispersed into small forces per crystal grain, preventing the occurrence of cracks.

[0027] Next, a method for manufacturing the vitreous silica crucible 1 having the above structure will be described. First, a quartz glass crucible before high-purity treatment is manufactured using a quartz glass crucible manufacturing apparatus 10 as shown in Fig. 5. The crucible forming mold 11 of the quartz glass crucible manufacturing apparatus 10 is composed of an inner member 12 made of a gas-permeable material, for example, a metal mold with a plurality of through holes or a porous carbon mold that has been highly purified, and a holder 14 that holds the inner member 12 and has a ventilation section 13 on its outer periphery.

[0028] A rotating shaft 15 connected to a rotating means (not shown) is fixed to the lower part of the holder 14, and rotatably supports the crucible forming mold 11. The ventilation part 13 is connected to an exhaust path 17 provided in the center of the rotating shaft 15 via an opening 16 provided in the lower part of the holder 14, and this exhaust path 17 is connected to a pressure reducing mechanism 18. At the upper part facing the inner member 12, an arc electrode 19 for arc discharge, an Al-added raw material supply nozzle 20, a natural silica powder supply nozzle 22, and a high-purity synthetic silica powder supply nozzle 23 are provided.

[0029] The Al-doped quartz powder used in the outer layer 2 can be obtained as follows. For example, an aqueous solution of Al nitrate, made by dissolving Al nitrate (Al(NO3)3) in water in an amount such that the Al concentration in the quartz powder is, for example, 100 ppm, is added to the quartz powder and stirred. After stirring, the mixture is heat-treated at 800 to 1100°C for the purposes of dehydration and acid removal. This produces a primary additive material with a high Al concentration. Next, the primary additive material is mixed with an equal amount of quartz powder to obtain a secondary additive material in which the primary additive material is uniformly dispersed and the Al concentration is, for example, 25 ppm. This is the Al-added quartz powder to be supplied to the outer layer 2.

[0030] In addition, 90% or more of the primary additive raw material C1 is contained within the range of ±25% of the overall average particle size of the Al-doped quartz powder, which prevents the primary additive raw material from segregating due to vibration during transportation or stirring when molding the Al-doped quartz powder into a crucible shape. In addition, in the above example, the primary additive raw material is mixed with an equal amount of quartz powder to form Al-doped quartz powder, but it is desirable that the content of the primary additive raw material in the Al-doped quartz powder be in the range of 1 to 50%, which makes it possible to create a state in which unadded quartz powder is interposed between the primary additive raw materials.

[0031] When the Al-doped quartz powder thus obtained is used to manufacture a quartz glass crucible using the quartz glass crucible manufacturing apparatus 10, a rotary drive source (not shown) is operated to rotate the rotating shaft 18 in the direction of the arrow, thereby rotating the crucible molding die 11 at high speed. Next, Al-doped quartz powder (Al concentration 25 ppm) is supplied from the Al-doped raw material supply nozzle 20 into the crucible forming mold 11. The supplied Al-doped quartz powder is pressed against the inner surface of the inner member 12 by centrifugal force and formed as the outer layer 2. At this time, the primary additive raw material in the outer layer 2 is in a dispersed state in the quartz powder.

[0032] Here, the position of the lower end of the outer layer 2 is determined as described with reference to Figure 2, and the lower corners 8 and bottom 9 are removed. That is, the outer layer 2 is removed from the lower corners 8 to the bottom 9 of the quartz glass crucible 1 to be manufactured.

[0033] Next, natural silica powder is supplied from the natural silica powder supply nozzle 22 so as to form an opaque intermediate layer 3 having a thickness of 3 mm or more on the inner surface side of the outer layer 2, and an opaque outer layer 5 having a thickness of 6 mm or more at the lower corners 8 and bottom 9. The supplied natural silica powder is pressed by centrifugal force against the inner surface side of the outer layer 2 and the bottom of the inner member 12, and is formed into a compact of the opaque intermediate layer 3 and opaque outer layer 5.

[0034] Next, high-purity synthetic quartz powder containing metal impurities of Na, K, and Al each at 1 ppm or less is supplied from the high-purity synthetic quartz powder supply nozzle 23 so that a transparent layer having a thickness of at least 3 mm is formed on the inner surface side of the opaque intermediate layer 3 and the opaque outer layer 5. The supplied high-purity synthetic silica powder is pressed against the inner surfaces of the opaque intermediate layer 3 and the opaque outer layer 5 by centrifugal force, and is molded into a green body of the transparent inner layer 4.

[0035] In this way, a crucible molded body is obtained, which comprises the outer layer 2 in which the Al-added raw material is dispersed, the opaque intermediate layer 3, the opaque outer layer 5, and the transparent inner layer 4. Furthermore, the pressure inside the inner member 12 is reduced by operating the pressure reduction mechanism 18, and electricity is passed through the arc electrode 19 to heat the crucible formed body from the inside, and the transparent inner layer 4, opaque intermediate layer 3, opaque outer layer 5 and outer layer 2 of the crucible formed body are arc-melted to produce the quartz glass crucible 1.

[0036] Here, during the arc melting, high-purity synthetic quartz powder, which is the raw material for the transparent inner layer 4, is supplied to the bottom 9 from a high-purity synthetic quartz powder supply nozzle 23, thereby making the thickness of the bottom 9 thicker, and the thickness dimension t3 of the bottom is made to be 80% or more of the thickness dimension t2 of the lower corner 8. In addition, it is desirable that the position where the thickness is greatest is located closer to the bottom than the lower corner 8, and in particular that the position where the thickness is greatest is located within ±6% of the outer diameter of the quartz glass crucible from the contact point P between the ridge line of the bottom and the ridge line of the lower corner. Alternatively, when forming the above-mentioned crucible molding, the supply amount of raw quartz powder for forming the outer layer 2, the opaque intermediate layer 3, the opaque outer layer 5 and the transparent inner layer 4 may be adjusted so that the thickness dimension t1 of the straight body portion 7 is 70% or less of the thickness dimension t2 of the lower corner 8, and the thickness dimension t3 of the bottom portion 9 is 80% or more of the thickness dimension t2 of the lower corner 8.

[0037] As described above, according to this embodiment, the thickness t1 of the body portion 7 is set to 70% or less of the thickness t2 of the lower corner 8. As a result, even if the silicon melt decreases to the vicinity of the lower corner 8 during single crystal pulling, the lower corner 8 has enough durability to bear the load of the body portion 7, thereby preventing the body portion 7 from sinking or deforming inwardly. Furthermore, the thickness t3 of the bottom 9 is set to be 80% or more of the thickness t2 of the lower corner 8. This allows the bottom 9 to have enough durability to withstand the load of the body 7 and the lower corner 8, even if the silicon melt decreases to a position lower than the lower corner 8 during single crystal pulling, and deformation of the bottom 9 can be prevented. As a result, deformation of the silica glass crucible 1 can be suppressed, and the yield of silicon single crystals can be improved.

[0038] In the above embodiment, a crucible having a three-layer structure on the crucible side has been described as an example, but the present invention is not limited to this, and the number of layers is not limited. For example, the present invention can be applied to a single-layer quartz glass crucible having only a transparent inner layer, or a two-layer quartz glass crucible having a transparent inner layer and an opaque outer layer. [Example]

[0039] The quartz glass crucible and the method for manufacturing the same according to the present invention will be further described based on examples. In this example, single crystals were grown using quartz glass crucibles with different conditions, and the single crystals were pulled up when the remaining molten liquid level reached a height below the apex of the corner R. Then, the extent to which the inner surface of the recovered quartz glass crucible between the bottom and corner was raised relative to the original ridge was observed.

[0040] Table 1 shows the conditions and results of Examples 1 to 6 and Comparative Examples 1 to 3. As shown in Table 1, the conditions of the quartz glass crucible were changed by changing the ratio (%) of the thickness of the straight body to the thickness of the lower corners and the ratio (%) of the bottom thickness to the thickness of the lower corners. The evaluation method was as follows: if the inner surface of the quartz glass crucible between the bottom and corners was raised by 5 mm or more from the original ridge line, it was rated as NG (×), and if it was raised by less than 5 mm, it was rated as OK (○). In addition, if no raised portion was observed, it was rated as the most preferable (◎).

[0041] [Table 1]

[0042] As shown in Table 1, it is preferable that the thickness dimension of the straight body portion is formed to be 70% or less of the thickness dimension of the lower corner, and that the thickness dimension of the bottom portion is formed to be 80% or more (upper limit 150%) of the thickness dimension of the lower corner. It was confirmed that it is preferable to form the thickness of the body portion to 40 to 50% of the thickness of the lower corner, and the thickness of the bottom portion to 110 to 130% of the thickness of the lower corner. [Explanation of symbols]

[0043] 1. Quartz glass crucible 2 Outer layer 3 Opaque interlayer 4 transparent inner layer 5 Opaque outer layer 7 Straight body part 8 bottom corner 9 Bottom 10. Quartz glass crucible manufacturing equipment 30 High-purification treatment equipment

Claims

1. In a quartz glass crucible for pulling silicon single crystals, a bottom portion having a predetermined curvature, a lower corner formed around the bottom portion and having a predetermined curvature, and a straight body portion extending upward from the lower corner, The thickness of the straight body portion is formed to be 70% or less of the thickness of the lower corner, A quartz glass crucible characterized in that the thickness dimension of the bottom portion is formed to be 80% or more and 150% or less of the thickness dimension of the lower corner.

2. A quartz glass crucible as described in claim 1, characterized in that the position where the thickness dimension is maximum is located closer to the bottom than the lower corner, and is located within ±6% of the outer diameter of the quartz glass crucible from the radial point of contact between the ridge line of the bottom and the ridge line of the lower corner.

3. The method for manufacturing the quartz glass crucible according to claim 1 or 2, rotating the inner member of the crucible forming mold around an axis and supplying raw quartz powder to form at least one layer of a crucible molded body; and a step of heating and melting the crucible molded body from the inside to form a quartz glass crucible, A method for manufacturing a quartz glass crucible, characterized in that in the step of supplying the raw quartz powder and forming at least one layer of crucible molding, the amount of raw quartz powder supplied is adjusted to form the thickness dimension of the straight body portion to 70% or less of the thickness dimension of the lower corner, and to form the thickness dimension of the bottom portion to 80% or more and 150% or less of the thickness dimension of the lower corner.

4. The method for manufacturing the quartz glass crucible according to claim 1 or 2, rotating the inner member of the crucible forming mold around an axis and supplying raw quartz powder to form at least one layer of a crucible molded body; and a step of heating and melting the crucible molded body from the inside to form a quartz glass crucible, A method for manufacturing a quartz glass crucible, characterized in that in the step of heating and melting the crucible molded body from the inside to form a quartz glass crucible, further raw quartz powder is supplied and the amount of raw quartz powder supplied is adjusted so that the thickness dimension of the straight body portion is formed to 70% or less of the thickness dimension of the lower corner, and the thickness dimension of the bottom portion is formed to 80% or more and 150% or less of the thickness dimension of the lower corner.

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