JP7378966B2 - Quartz glass crucible and its manufacturing method - Google Patents

Description

The present invention relates to a quartz glass crucible and a method for manufacturing the same, and more particularly to a quartz glass crucible and a method for manufacturing the same in which the temperature distribution on the inner surface of the crucible is controlled more uniformly.

Regarding the growth of silicon single crystals, the CZ method (Czochralski method) is widely used. This method involves bringing a seed crystal into contact with the surface of a silicon melt housed in a silica glass crucible, rotating the crucible, and pulling the seed crystal upward while rotating it in the opposite direction. A silicon single crystal is formed at the bottom end.

Patent Document 1 (Japanese Unexamined Patent Publication No. 2018-104248) discloses a single crystal pulling device that pulls a silicon single crystal using the CZ method. FIG. 7 schematically shows a single crystal pulling apparatus disclosed in Patent Document 1.
This single crystal pulling device 20 includes a furnace body 21, a quartz glass crucible 30 provided in the furnace body 21, and a semiconductor raw material (raw material polysilicon) M loaded in the crucible 30. It has a cylindrical carbon heater 40 that melts and a pulling mechanism (not shown) that pulls up the silicon single crystal C to be grown using a wire 50. A seed crystal P is attached to the tip of the wire 50.

In the single crystal pulling apparatus 20 configured in this manner, the raw material polysilicon M in the quartz glass crucible 30 is melted by the radiant heat of the carbon heater 40.
Thereafter, the silica glass crucible 30 is rotated at a predetermined rotation speed at a predetermined height position, and the wire 50 with the seed crystal P attached to the tip is lowered.
Then, the seed crystal P attached to the tip of the wire 50 is brought into contact with the silicon melt M, and necking is performed to melt the tip of the seed crystal P, thereby forming the neck portion P1.

Once the neck portion P1 is formed, the pulling conditions are adjusted using parameters such as the power supplied to the heater 40 and the pulling speed (usually a speed of several millimeters per minute), and a crown portion forming step (diameter expansion step) is performed. A silicon single crystal pulling process such as a straight body part forming process and a bottom part forming process is performed in order.

JP2018-104248A

By the way, in the above-mentioned pulling process of the single crystal pulling device 20, the region closest to the center in the height direction of the heater 40, that is, the middle region to the lower region 30a1 of the straight body portion 30a of the silica glass crucible 30 becomes locally high temperature. There was a problem that variations occurred in the temperature distribution on the inner surface of the crucible.

In addition, when the inner surface of the crucible in the middle region to lower region 30a1 of the straight body portion 30a becomes excessively high temperature, the amount of the melted surface of the crucible in that region increases, and the degree of oxygen dissolution in the silicon melt M decreases. There was a problem in that the interstitial oxygen concentration of the pulled silicon single crystal increased and varied.

In order to solve this problem, the present inventors conducted extensive research on variations in temperature distribution on the inner surface of the crucible.
One method, as proposed in JP-A-10-59794, is to change the roughness of the outer surface of the container stepwise or gradually from the seed crystal side to the opposite side of the container. Conceivable.
However, this pyrolytic boron nitride container and the silica glass crucible according to the present invention are completely different in shape and method of use, and the roughness of the outer surface of the container is changed from the seed crystal side of the container to the opposite side. Even if the temperature was changed stepwise or gradually, the local high temperature on the inner surface of the crucible could not be suppressed.

Therefore, the present inventors focused on the surface roughness of the outer surface of the crucible and continued research to suppress variations in the temperature distribution on the inner surface of the crucible. The inventors discovered that variations in the temperature distribution on the inner surface of the crucible can be suppressed by making the surface rougher than other regions, and came up with the present invention.

Note that Japanese Patent Laid-Open No. 2009-84114 discloses a structure in which the outer surface of a quartz glass crucible used for pulling silicon single crystals is intentionally roughened as in the present invention. However, the purpose of this quartz glass crucible is to make it difficult to deform even under high temperatures during use without using a crystallization promoter, and to make it easy to manufacture. Moreover, it does not suppress variations in temperature distribution on the inner surface of the crucible.

The present invention has been made under these circumstances, and an object of the present invention is to provide a silica glass crucible that can control the temperature distribution on the inner surface of the crucible more uniformly, and a method for manufacturing the same.

A quartz glass crucible according to the present invention, which has been made to achieve the above object, includes at least a transparent inner layer and an opaque outer layer, and includes a cylindrical straight body part and a radius curved inwardly in the radial direction from the lower end of the straight body part. and a bottom portion formed from the radially inner end of the R portion, the outer surface roughness of the opaque outer layer in the lower region of the straight body portion or the R portion is equal to that of the straight body portion. The outer surface roughness is larger than the outer surface roughness of the upper to middle region of the bottom part, and is also larger than the outer surface roughness of the bottom part.

According to the silica glass crucible configured in this manner, by maximizing the surface roughness in the crucible lower region or R portion on the outer surface of the crucible, it is possible to reduce the amount of light (infrared rays) transmitted in that region. I can do it.
As a result, excessive local heating on the crucible inner surface is suppressed, and variations in temperature distribution on the crucible inner surface in the crucible height direction can be suppressed.
Furthermore, since excessive local heating is suppressed in this way, the amount of local dissolution on the inner surface of the crucible can be suppressed, and the amount of oxygen dissolved in the silicon melt can be reduced. Furthermore, changes in interstitial oxygen concentration in the pulled silicon single crystal can be effectively suppressed.

Here, the outer surface roughness Ra of the opaque outer layer in the upper to middle region of the straight body portion is 5 μm or more and 50 μm or less, and the outer surface roughness Ra in the lower region of the straight body portion to the R portion is: It is desirable that the outer surface roughness Ra of the bottom portion be 30 μm or more and 100 μm or less, and the outer surface roughness Ra of the bottom portion be 5 μm or more and 20 μm or less.

Further, it is preferable that the lower region of the straight body portion of the opaque outer layer to the R portion be located at a distance of 0 mm or more and 150 mm or less from the bottom of the crucible inner surface along the crucible height direction.

In addition, the method for manufacturing a silica glass crucible according to the present invention, which has been made to achieve the above object, includes a straight body part comprising at least a transparent inner layer and an opaque outer layer and forming a cylindrical straight body part; In the method for manufacturing a silica glass crucible, the silica glass crucible includes an R section that curves radially inward from a lower end of the opaque outer layer, and a bottom section formed from a radially inner end of the R section. The present invention is characterized by including the step of forming the outer surface roughness of the R portion to be larger than the outer surface roughness of the upper to middle region of the straight body portion and larger than the outer surface roughness of the bottom portion.

In this way, the outer surface roughness of the lower region to the R portion of the straight body portion of the opaque outer layer is set to be larger than the outer surface roughness of the upper to middle region of the straight body portion, and the outer surface roughness of the bottom portion is made larger. The quartz glass crucible according to the present invention described above can be obtained by including the step of forming the crucible larger than the size of the crucible.

Further, the outer surface roughness of the opaque outer layer in the lower region to the R portion of the straight body portion is set to be larger than the outer surface roughness of the upper to middle region of the straight body portion, and greater than the outer surface roughness of the bottom portion. In the step of forming the opaque outer layer to a large size, the outer surface roughness Ra of the opaque outer layer in the upper to middle region of the straight body portion is 5 μm or more and 50 μm or less, and the outer surface roughness Ra of the lower region of the straight body portion to the R portion is , 30 μm or more and 100 μm or less, and the outer surface roughness Ra of the bottom portion is preferably 5 μm or more and 20 μm or less.

Further, it is preferable that the lower region of the straight body portion of the opaque outer layer to the R portion be located at a distance of 0 mm or more and 150 mm or less from the bottom of the crucible inner surface along the crucible height direction.

According to the present invention, it is possible to obtain a silica glass crucible in which the temperature distribution on the inner surface of the crucible is controlled more uniformly, and a method for manufacturing the same.

FIG. 1(a) is a cross-sectional view of a vitreous silica crucible according to the present invention, and FIG. 1(b) is a cross-sectional view showing regions for dividing the outer surface roughness of the crucible. FIG. 2 is a cross-sectional view of a quartz glass crucible manufacturing apparatus to which the quartz glass crucible manufacturing method according to the present invention can be applied. FIG. 3 is a graph showing the change (%) in light transmittance with respect to the change in surface roughness Ra of the outer surface of the crucible for a sample of a quartz glass crucible. FIG. 4 is a cross-sectional view schematically showing the configuration of a single crystal pulling apparatus used in an example of the present invention. FIG. 5 is a graph showing the results of Examples 1 to 3 of the present invention. FIG. 6 is a graph showing the results of Comparative Examples 1 to 5. FIG. 7 is a cross-sectional view schematically showing a conventional single crystal pulling apparatus.

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the quartz glass crucible and its manufacturing method based on this invention is described based on FIG. 1, FIG. 2.
FIG. 1(a) is a sectional view of a quartz glass crucible according to the present invention. As shown in FIG. 1(a), the silica glass crucible 1 is formed to have an outer diameter of 810 mm and a thickness of 15 mm, for example, and includes a transparent inner layer 2 made of a synthetic quartz layer that does not substantially contain air bubbles, and a natural stone that contains air bubbles. It is composed of an opaque outer layer 3 made of a quartz layer or a synthetic quartz layer.

That is, the quartz glass crucible 1 has a two-layer structure including a transparent inner layer 2 that comes into contact with molten silicon during pulling of a silicon single crystal, and an opaque outer layer 3 adjacent to the transparent inner layer 2. The ratio of the transparent inner layer 2 and the opaque outer layer 3 in the thickness direction is, for example, 2:1.

Here, the term "substantially free of bubbles" refers to a transparent layer in which bubbles with a diameter of 0.5 mm or more are not present at a density of 1 pcs/mm ^{3 or} more.
In addition, opaque means that a large number of air bubbles (pores) are present in the quartz glass, making it appear cloudy. Furthermore, a natural quartz layer refers to a silica glass layer manufactured by melting natural raw materials such as quartz, and a synthetic quartz layer refers to a silica glass layer manufactured by melting synthetic raw materials synthesized by hydrolysis of silicon alkoxide, for example. silica glass layer.

Furthermore, as shown in FIG. 1(a), the silica glass crucible 1 has a cylindrical straight body part 1a extending downward from the upper opening without changing its diameter, and a small radius of curvature extending inward from the lower end of the straight body part 1a. and a bottom portion 1c that curves from the R portion 1b with a large radius of curvature to form a crucible bottom.
The transparent inner layer 2 and the opaque outer layer 3 together form the straight body portion 1a, the R portion 1b, and the bottom portion 1c.

Further, in this embodiment, the outer surface of the opaque outer layer 3 is divided into three regions, and the surface roughness is set as shown in FIG. 1(b). This surface roughness is processed to a predetermined surface roughness using, for example, a blasting device.
A specific area of the outer surface of the opaque outer layer 3 is made to have a predetermined surface roughness, and radiation from the heater to the inner surface of the crucible in the specific area is suppressed, thereby suppressing local excessive heating. be.
The inner surface of the transparent inner layer 2 is in a state where synthetic raw materials are melted and solidified, and unlike the outer surface of the opaque outer layer 3, it is not processed.

To explain in detail the relationship between this surface roughness and the temperature distribution on the inner surface of the crucible, the infrared light emitted by the heater is broad (wide wavelength range) with a peak around 2 μm wavelength (1500°C); The internal transmittance of glass is almost 100%, but the transmittance depends on the surface roughness.

As an example, FIG. 3 shows the relationship between the surface roughness of glass and the transmittance (visible light).
As this sample, we used a rectangular glass with a transparent layer made of a synthetic quartz layer and an opaque layer made of a synthetic quartz layer, with a transparent layer thickness of 10 mm, an opaque layer thickness of 5 mm, and a total thickness of 15 mm. Using.
Then, the transmittance at a wavelength of 500 nm was measured while varying the surface roughness of the opaque layer. Note that the transparent layer had a mirror surface like the inner surface of the crucible, and the surface roughness was not changed.

The results of this experiment revealed that the greater the surface roughness, the more light is scattered and the transmittance is lower. In particular, it has been found that when the outer surface roughness Ra is 5 μm or more, the transmittance decreases by 25%.

Furthermore, as a result of experiments and simulations using crucibles, when a crucible with an outer surface roughness Ra of 5 to 100 μm is heated to a temperature of 1433°C on the melt surface, by partially changing the outer surface roughness, It has been found that the variation in the distribution of inner surface temperature is reduced, and the degree of oxygen solubility at the portion where the inner surface temperature is maximum is reduced by 5% or more.
It has also been found that when the outer surface roughness Ra exceeds 100 μm, temperature variations occur due to non-uniform scattering of light, which is not preferable.

Here, to specifically explain the outer surface roughness Ra of the crucible, the upper to middle region of the straight body part 1a (area Ar1 surrounded by a broken line), the lower region of the straight body part 1a to the R part 1b (the area surrounded by a broken line) The outer surface roughness Ra is set for each area of the bottom portion 1c (area Ar2) and the bottom portion 1c (area Ar3 surrounded by a broken line).
The upper to middle region of the straight body part 1a means the 2/5 part from the opening with respect to the height of the crucible, and the lower part of the straight body part 1a to the R part 1b are 3/5 to 4 from the opening. /5 part, and the bottom part 1c means 1/5 part from the bottom part.

For example, the surface roughness Ra (arithmetic mean roughness) of the upper to middle region (area Ar1) of the straight body portion 1a is set to a predetermined value of 5 to 50 μm. The surface roughness Ra in the lower region of the straight body portion 1a to the R portion 1b (region Ar2) is set to a predetermined value of 30 to 100 μm. Further, the surface roughness Ra at the bottom portion 1c (area Ar3) is set to a predetermined value of 5 to 20 μm.

However, in any combination of surface roughness Ra, the surface roughness Ra in the lower region of the straight body part 1a to the R part 1b is larger than in other parts (the upper to middle region of the straight body part 1a, the bottom part 1c). be taken as a thing.
This is to suppress radiant heat by reducing the amount of transmission in the lower region of the straight body portion 1a to the R portion 1b, and to make the temperature distribution on the inner surface of the crucible nearly uniform.

In this way, on the outer surface of the crucible, by maximizing the surface roughness Ra in the lower region of the straight body section 1a or the R section 1b, the amount of light (infrared rays) transmitted through the lower region of the straight body section 1a or the R section 1b can be increased. Decrease.
As a result, excessive local heating on the crucible inner surface due to the crucible shape etc. is suppressed, and variations in temperature distribution on the crucible inner surface in the crucible height direction can be reduced. Furthermore, excessive local dissolution on the inner surface of the crucible can be suppressed, and the amount of oxygen dissolved in the silicon melt can be reduced. Furthermore, changes in the interstitial oxygen concentration in the silicon single crystal to be pulled can be effectively suppressed.

In addition, the reason why the surface roughness Ra (arithmetic mean roughness) of the upper to middle region (area Ar1) of the straight body portion 1a is set to a predetermined value of 5 to 50 μm is because the influence of surface roughness on temperature is less than 5 μm. This is because it is undesirable because it is small, and if it exceeds 50 μm, the temperature will vary greatly due to the influence of variations in surface roughness, which is undesirable.
In addition, the reason why the surface roughness Ra in the lower region of the straight body part 1a to the R part 1b (region Ar2) is set to a predetermined value of 30 to 100 μm is because when the surface roughness is less than 30 μm, the temperature increases due to the influence of the adjacent regions Ar1 and Ar3. This is not preferable because it is difficult to make a difference, and if it exceeds 100 μm, the temperature will vary greatly due to the influence of variations in surface roughness, which is not preferable.
Furthermore, the reason why the surface roughness Ra at the bottom part 1c (area Ar3) is set to a predetermined value of 5 to 20 μm is that it is not preferable to set the surface roughness Ra to a predetermined value of 5 to 20 μm because the influence of surface roughness on temperature is small when it is less than 5 μm, and when it exceeds 20 μm, This is because the temperature varies greatly due to variations in surface roughness, which is not desirable.

Next, a method for manufacturing the silica glass crucible 1 will be explained.
FIG. 2 is a cross-sectional view of a quartz glass crucible manufacturing apparatus to which the quartz glass crucible manufacturing method according to the present invention can be applied.
The crucible molding mold 11 of the quartz glass crucible manufacturing apparatus 10 shown in FIG. It consists of a ventilation section 14 provided between the outer peripheral surface of the member 12 and the inner peripheral surface of the holder 13.

A rotating shaft 15 connected to a rotating means (not shown) is fixed to the lower part of the holder 13, and rotatably supports the crucible molding die 11. The ventilation portion 14 is connected to an exhaust port 17 provided at the center of the rotating shaft 15 via an opening 16 provided at the bottom of the holder 13 . This exhaust port 17 is connected to a pressure reducing mechanism 18 .

Further, above the crucible molding mold 11, a raw material supply nozzle 19 for supplying natural quartz raw material powder and a raw material supply nozzle 20 for supplying synthetic quartz raw material powder are arranged.
Further, at the upper portion facing the inner member 12, for example, three carbon electrodes 21a, 21b, and 21c are provided for heating and melting by arc discharge.

The carbon electrodes 21a, 21b, and 21c are made entirely of carbonized particles of raw material such as coke, e.g., coal-based pitch coke, and a binder such as coal-tar pitch, e.g., carbonized carbonized coal-based coal tar pitch. It has a cylindrical shape with a tapered tip.

In the silica glass crucible manufacturing apparatus 10 configured as described above, while reducing the pressure inside the inner member 12 by operating the pressure reducing mechanism 18, the rotary drive source (not shown) is operated to rotate the rotating shaft 15, and the crucible molding mold is rotated. Rotate 11.
Next, natural quartz raw material powder is supplied into the crucible mold 11 from the raw material supply nozzle 19 . The supplied natural quartz raw material powder is pressed against the inner member 12 of the crucible mold 11 by centrifugal force, and a natural quartz powder layer 3A is formed.

Next, synthetic quartz raw material powder is supplied from the raw material supply nozzle 20 onto the natural quartz powder layer 3A. The supplied synthetic quartz raw material powder is pressed against the natural quartz powder layer 3A to form a synthetic quartz powder layer 2A.
In this way, a crucible molded body 1A is obtained in which the synthetic quartz powder layer 2A is formed on the inner layer side and the natural quartz powder layer 3A is formed on the outer layer side.

Subsequently, the three carbon electrodes 21a, 21b, and 21c are set in the silica glass crucible manufacturing apparatus 10 shown in FIG. is heated to melt the crucible molded body 1A from the inner surface to the outer surface.
Thereafter, by cooling, a transparent quartz glass layer 2 with substantially no bubbles and suppressed oxygen-excess defects is formed on the inner surface, and an opaque quartz glass layer 3 containing many bubbles is formed on the outer surface. A quartz glass crucible is obtained.

Further, the outer surface of the obtained quartz glass crucible is partially or entirely polished, and a polishing treatment is performed to bring the outer surface to a predetermined surface roughness.
Specifically, the outer surface roughness Ra of the opaque outer layer in the upper to middle region of the straight body portion is 5 μm or more and 50 μm or less, and the outer surface roughness Ra in the lower region of the straight body portion to the R portion is is 30 μm or more and 100 μm or less, and the surface is roughened by sandblasting or etching with a hydrofluoric acid solution so that the outer surface roughness Ra at the bottom portion is 5 μm or more and 20 μm or less.
As described above, in any combination of surface roughness Ra, the surface roughness Ra at the lower region of the straight body portion 1a to the R portion 1b is different from that of other portions (the upper to middle region of the straight body portion 1a, the bottom region). 1c).

For example, the surface roughness Ra of the upper to middle region of the straight body portion 1a is 50 μm, the surface roughness Ra of the lower region of the straight body portion 1a to the R portion 1b is 100 μm, and the surface roughness Ra of the bottom portion 1c is 20 μm. Polished to

As described above, according to the embodiment of the present invention, by providing variation in the amount of light (infrared wavelength) transmitted in the crucible height direction, the temperature distribution on the inner surface of the crucible can be made uniform.
That is, local excessive heating on the crucible inner surface is suppressed, the amount of dissolution from the crucible inner surface accompanying pulling of the silicon single crystal can be suppressed, and the amount of oxygen dissolved in the silicon melt can be reduced. Furthermore, changes in interstitial oxygen concentration in the pulled silicon single crystal can be effectively suppressed.

The silica glass crucible and the manufacturing method thereof according to the present invention will be further explained based on Examples.

In this example, in the configuration of the single crystal pulling apparatus schematically shown in FIG. The surface temperature was measured.
In Example 1, the crucible has an outer diameter of 810 mm, a height of 450 mm, a wall thickness of 15 mm, a ratio of transparent layer (inner layer) to opaque layer (outer layer) in the thickness direction of 2:1, and a bulk density of 2. A quartz glass crucible 1 of .2 g/cm ³ was used.

In addition, among the range in the height direction of the crucible (0 mm to 300 mm) shown in Fig. 4, the range from 150 mm to 300 mm is the upper to middle region of the straight body, and the range from 0 mm (bottom of the inner surface of the crucible) to 150 mm is the straight range. It was defined as the lower region of the trunk or the R section. Further, a circular region whose radius is from the center of the outer surface of the crucible bottom to the R section was defined as the bottom (region).

In this Example 1, the surface roughness Ra of the upper to middle region of the straight body part was 5 μm, the surface roughness Ra of the lower region to the R part of the straight body part was 30 μm, and the surface roughness Ra of the bottom part was 5 μm. .
Then, the temperature of the melt surface Ma was maintained at 1433° C. by heater heating, and the crucible inner surface temperature was measured at a height of 0 mm to 300 mm from the crucible bottom.
Furthermore, the degree of oxygen solubility in the silicon melt was determined using the following formula (1).
Oxygen solubility in silicon melt Cs=4×10 ²³ exp (-2×10 ⁴ /T)...(1)

In Example 2, the surface roughness Ra of the upper to middle region of the straight body part on the outer surface is 20 μm, the surface roughness Ra of the lower region to the R part of the straight body part is 50 μm, and the surface roughness Ra of the bottom part is 10 μm. did.
Other conditions are the same as in Example 1.

In Example 3, the surface roughness Ra of the upper to middle region of the straight body part on the outer surface is 50 μm, the surface roughness Ra of the lower region to the R part of the straight body part is 100 μm, and the surface roughness Ra of the bottom part is 20 μm. did.
Other conditions are the same as in Example 1.

In Comparative Example 1, the surface roughness Ra of all the outer surfaces (straight body part, R part, and bottom part) was 5 μm, in Comparative Example 2, the surface roughness Ra of all outer surfaces was 50 μm, and in Comparative Example 3, the outer surface roughness Ra was 5 μm. The surface roughness Ra of all surfaces was 100 μm.
Other conditions are the same as in Example 1.

The results of Examples 1 to 3 and Comparative Examples 1 to 5 are shown in Table 1 and the graphs of FIGS. 5 and 6.
In Table 1, the amount of change (%) in oxygen solubility is the ratio of the amount of change with respect to Comparative Example 1.
Further, FIG. 5 is a graph showing the results of Examples 1 to 3, and FIG. 6 is a graph showing the results of Comparative Examples 1 to 5. In the graphs of FIGS. 5 and 6, the vertical axis is the crucible height (mm), and the horizontal axis is the crucible inner surface temperature (° C.).

As shown in Table 1, in Examples 1 to 3, the value of the outer surface roughness Ra in the lower region of the straight body part or the R part was set to 2. Although it was set to be more than twice as large, the degree of oxygen dissolution in the silicon melt could be kept low compared to Comparative Examples 1 to 3, where the value of the outer surface roughness Ra did not change. The amount of change in oxygen solubility was -6% to -8%, and the oxygen solubility could be significantly reduced.

Furthermore, as shown in the graph of FIG. 5, in Examples 1 to 3, the crucible inner surface temperature, which varies depending on the crucible height, could be suppressed to a small value. On the other hand, as shown in the graph of FIG. 6, in Comparative Examples 1 to 5, the crucible inner surface temperature varied greatly depending on the crucible height. In particular, in Comparative Examples 1 to 3, the inner surface temperature was high with a peak of 200 mm in height, and as in Examples 1 to 3, the surface roughness Ra of the lower region to the R part of the straight body was made roughest. , it was possible to effectively reduce the local internal surface temperature of the crucible, which peaked at the height of 200 mm.

As a result of the above examples, the outer surface roughness Ra in the upper to middle region of the straight body portion of the opaque outer layer is 5 μm or more and 50 μm or less, and the outer surface roughness Ra in the lower region or R portion of the straight body portion is: The effect of the present invention was confirmed under the conditions that the outer surface roughness Ra at the bottom was 5 μm or more and 20 μm or less.

1 Silica glass crucible 1a Straight body part 1b R part 1c Bottom part 2 Transparent inner layer 3 Opaque outer layer 10 Quartz glass crucible manufacturing device 11 Crucible molding mold 12 Inner member 13 Holder 14 Ventilation part 15 Rotating shaft 16 Opening part 17 Exhaust port 18 Depressurization Mechanism 19 Raw material supply nozzle 20 Raw material supply nozzle 21a Carbon electrode 21b Carbon electrode 21c Carbon electrode

Claims (4)

It consists of at least a transparent inner layer and an opaque outer layer, and includes a cylindrical straight body part, an R part that curves radially inward from the lower end of the straight body part, and a bottom part formed from the radially inner end of the R part. In the quartz glass crucible equipped with
The outer surface roughness of the opaque outer layer in the lower region to the R portion of the straight body portion is greater than the outer surface roughness of the upper to middle region of the straight body portion, and greater than the outer surface roughness of the bottom portion. ,
The outer surface roughness Ra of the upper to middle region of the straight body portion of the opaque outer layer is 5 μm or more and 50 μm or less,
The outer surface roughness Ra in the lower region of the straight body part or the R part is 30 μm or more and 100 μm or less,
A quartz glass crucible , wherein the bottom portion has an outer surface roughness Ra of 5 μm or more and 20 μm or less . The lower region of the straight body portion of the opaque outer layer to the R portion are:
The quartz glass crucible according to claim 1 , wherein the quartz glass crucible is located at a distance of 0 mm or more and 150 mm or less from the bottom of the crucible inner surface along the crucible height direction. A straight body part comprising at least a transparent inner layer and an opaque outer layer and forming a cylindrical straight body part, an R part that curves radially inward from the lower end of the straight body part, and a radially inner end of the R part. In a method of manufacturing a quartz glass crucible, the bottom portion is formed.
Forming the outer surface roughness of the lower region of the straight body portion of the opaque outer layer to the R portion to be larger than the outer surface roughness of the upper to middle region of the straight body portion and greater than the outer surface roughness of the bottom portion. and a step of
Forming the outer surface roughness of the lower region of the straight body portion of the opaque outer layer to the R portion to be larger than the outer surface roughness of the upper to middle region of the straight body portion and greater than the outer surface roughness of the bottom portion. In the process of
The outer surface roughness Ra of the upper to middle region of the straight body portion of the opaque outer layer is 5 μm or more and 50 μm or less,
The outer surface roughness Ra in the lower region of the straight body part or the R part is 30 μm or more and 100 μm or less,
A method for manufacturing a quartz glass crucible, characterized in that the outer surface roughness Ra of the bottom portion is set to 5 μm or more and 20 μm or less . The lower region of the straight body portion of the opaque outer layer to the R portion are:
4. The method for manufacturing a silica glass crucible according to claim 3 , wherein the quartz glass crucible is located at a distance of 0 mm or more and 150 mm or less from the bottom of the crucible inner surface along the crucible height direction.

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