JPH01157427A - Manufacture of quartz glass crucible - Google Patents

Abstract

PURPOSE:To obtain the title crucible free from bubbles and having high granularity by introducing H2, He, or their gaseous mixture from at latest the start of melting of grains at the time of adding the grains into a hollow die. CONSTITUTION:The hollow die 6 is rotated around a vertical shaft in the direction as shown by arrow 3 by using a rotary driving device 1. Grains are continuously or discontinuously added to the hollow die 6 so that the grains are layered on the inner wall of the hollow die 6 and accumulated on the bottom, and a grain layer 7 in the form of a crucible is formed. The heat of a heating source 8 is applied from the inside toward the outside through the thickness of the grain layer 7. H2, He, or their gaseous mixture is introduced from an injection port 10 from at latest the start of melting of the grains. As a result, only a part of the grain layer 7 is melted, the thin layer part is sintered, and the remaining grain layer 7 is kept in a state of grains as it is. The obtained quartz glass crucible is cooled, and then taken out from the hollow die 6.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a quartz glass crucible, and particularly to a method for manufacturing a quartz glass crucible for pulling silicon single crystals.

[L to 1L Silicon single crystals used as substrates for semiconductor devices are mainly manufactured by the C7 method. In principle, this method involves loading a polycrystalline silicon raw material into a crucible, heating it from the surroundings to melt the polycrystalline silicon raw material, and then suspending a seed crystal from above and immersing it in the silicon melt. This is to pull up a silicon single crystal ingot. Practically, the crucible is made of quartz glass.

To manufacture this quartz glass crucible, pulverized and refined quartz powder or silica powder is fed into a rotatable hollow mold, and the hollow mold is rotated and shaped by the action of centrifugal force. It is known that it can be melted by

However, with this manufacturing method, many air bubbles are contained within the quartz glass body. Furthermore, the variation in bubble diameter is large and the viscosity at high temperatures is low.

When such a vitreous silica crucible is used to pull a silicon single crystal, the vitreous silica crucible tends to deform when it is charged with silicon and used repeatedly because the viscosity of the crucible at high temperatures is low. When the quartz glass crucible deforms, the height of the silicon melt level changes, and the carbon crucible, which is made up of divided bodies that support the quartz glass crucible, also deforms, making it impossible to achieve uniform heating and changing the temperature distribution. Therefore, dislocations occur in the silicon single crystal.
cation) is likely to occur, resulting in a decrease in yield.

In addition, if air bubbles exist in the quartz glass crucible, the side wall of the quartz glass crucible in contact with the silicon melt expands due to the expansion of the volume of the air bubbles during pulling of the silicon single crystal due to the decrease in viscosity at high temperatures, causing the silicon melt to expand. The height of the liquid level changes. Furthermore, the inner surface of the quartz glass crucible is eroded by the silicon melt, causing the bubbles to open, and impurity gases in the bubbles are mixed into the silicon melt, resulting in lower yields due to dislocations and the like. For this reason, a quartz glass crucible with fewer bubbles is desired.

For example, a method for manufacturing a quartz glass crucible with few bubbles is as follows.
It is disclosed in Japanese Patent Publication No. 59-34659. According to this manufacturing method, reduced pressure is maintained outside the hollow mold by a vacuum device during melting of the quartz glass crucible. However, in this manufacturing method, when melting starts, the molded body becomes vitrified from the inner side, and air flows from the inside to the outside of the hollow mold, so many air bubbles remain near the thickness of the quartz glass, forming a layer. . In addition, the hollow holes tended to become clogged, resulting in uneven distribution of air bubbles. Therefore, even if the number of bubbles in the silica glass crucible as a whole is reduced, the most important point is not improved.

Furthermore, a method of processing transparent glass in order to obtain a quartz glass crucible with few bubbles has been disclosed (see Japanese Patent Publication No. 52-26522), but it is difficult to obtain a thick-walled crucible with such a manufacturing method. , poor dimensional accuracy.

Furthermore, a large crucible cannot be obtained, resulting in high costs.

The present invention was made to solve these problems, and it is an inexpensive way to manufacture a silica glass crucible that has a long life and has almost no adverse effect on the silicon single crystal being pulled. The purpose of the present invention is to provide a method for manufacturing a quartz glass crucible that can be manufactured using a quartz glass crucible.

Go to 11 1E The first invention of the present application is summarized as a method for manufacturing a quartz glass crucible according to claim 1. Also, the second part of this application
The gist of the invention is a quartz glass manufacturing method as set forth in claim 2.

to determine the interval 1. The first invention will be explained.

Finely ground particles of crystalline quartz or amorphous quartz glass are placed in a hollow mold of carbonaceous material rotatable about a vertical axis, as a layer on the inner wall of the mold.
Add continuously or discontinuously so that it accumulates at the bottom. By applying heat from the inside to the outside through the thickness of said layer, only a part of the layer is melted, resulting in thin partial layer semi-melting sintering and leaving the rest of the layer to remain in the granular state, resulting in quartz. After cooling the glass crucible, take it out from the hollow mold.

In the first invention, in such a manufacturing method, the hollow mold is covered with a highly airtight enclosure equipped with a gas inlet and an outlet, and the particles are placed in the enclosure at least 82 times from the start of melting.
)-1e or a mixture thereof.

The second invention will be explained. Finely ground particles of crystalline quartz or amorphous quartz glass are placed in a hollow mold of carbonaceous material rotatable around a vertical axis, as a layer on the inner wall of the mold and as a layer on the bottom. Add continuously or discontinuously so as to accumulate. By applying heat from the inside to the outside through the thickness of said layer, only a part of the layer is melted, resulting in thin partial layer semi-melting sintering and leaving the rest of the layer to remain in the granular state, resulting in quartz. After cooling the glass crucible, take it out from the hollow mold.

In the second invention, in such a manufacturing method, the hollow mold is covered with a highly airtight enclosure equipped with a gas inlet and an outlet, and N2. )-10 or a mixture thereof, the gas is then stopped, and other gases having a large molecular radius, such as Ar, N2, Ne, etc., are introduced until melting is completed for cooling.

JL According to the method for manufacturing a silica glass crucible of the first invention, at the start of melting, gases of N2, 1-(e, or a mixture thereof) flow into the apparatus, so that quartz particles are melted and incorporated into the resulting glass body. The bubbles are filled with gases such as N2, )le, or a mixture thereof. N2,
)le or a mixture thereof can diffuse in quartz glass, but other gases cannot diffuse because their molecular radius is too large. The gas generated in the gas pond during heating and melting disappears by diffusing from the quartz glass to the outside.

According to the method for manufacturing a quartz glass crucible of the second invention, since N2, 1-1e, or a mixture thereof flows into the apparatus at the start of melting, quartz particles are melted and incorporated into the resulting glass body. The bubbles are filled with gases such as N2, He, or a mixture thereof.

N2. Although He or a mixture thereof can diffuse in quartz glass, gases other than He cannot diffuse because their molecular radius is too large.

After that, a gas having a large molecular radius other than the girth is introduced, so that the gas in the bubbles diffuses from the quartz glass to the outside due to the partial pressure difference, and disappears.

Tsubasa Jl The first invention will be explained with reference to FIG.

FIG. 1 shows a quartz glass crucible manufacturing apparatus for carrying out the method of the first invention.

First, this manufacturing apparatus will be explained.

The rotary drive device 1 is provided with a rotary shaft 2, which supports an enclosure 4.

The enclosure 4 has a void 5 and a hollow mold 6 with good ventilation. Made of carbon material, there is a particle layer 7 inside the protruding mold 6.
is formed. An arc heating type heat source 8 using a carbon electrode and a spout 10 are located above the hollow mold 6.

The vacuum pump 11 is configured to draw air from the hollow mold 6 and the particle layer 7 through the gap 5.

From the ejection port 10, gas of H2, 1-1e, or a mixture thereof can be introduced.

The particle layer 7 is finely ground particles of crystalline quartz or amorphous quartz glass.

In the manufacturing method of the first invention, the hollow mold 6 is rotated around a vertical axis in the direction of the arrow 3 using the rotary drive device 1, and the particles are formed as a layer on the inner wall of the hollow mold 6 and accumulated at the bottom. is added to the hollow mold 6 continuously or discontinuously. A particle layer 7 having a pot shape is formed. Then, heat from the heating source 8 is applied from the inside to the outside through the layer thickness of the particle layer 7.

At the latest from the start of melting of these particles, H2, He, or a mixture thereof flows in through the outlet 10.

As a result, only a portion of the particle layer 7 is melted, the thin partial layer is semi-melted and sintered, and the remainder of the particle layer 7 remains in the particle state.

The obtained quartz glass crucible is cooled and then taken out from the hollow mold 6.

Actually, for example, the opening diameter is 356 mm and the height is 254 m.
A quartz glass crucible of m was manufactured. During melting, He gas was introduced 5 minutes before the start of melting. Gas pressure is 0.5k
g/cm2, and the flow rate was 25Q/min.

The apparent porosity of the resulting quartz glass crucible was 0.1% or less. The blistering rate of this crucible under reduced pressure was measured. Measurement was carried out by sampling from the crucible at a pressure of 1 torr.
, heat treatment was performed at a temperature of 1600° C. and a holding time of 3 hours.

The apparent increase in porosity after heat treatment compared to before heat treatment was defined as a sag rate (%) of 7.

Here, this blistering rate is determined by measuring the apparent specific gravity before and after heat treatment by a water immersion method, and represents the rate of change thereof, and is expressed by the following formula.

Blistering rate (%) = If the apparent specific gravity blistering rate before heat treatment is low, air bubbles will hardly bulge when pulling a silicon single crystal, and the crucible will not be deformed due to its high viscosity.

The results are shown in Table-1. Here, Comparative Example 1 was manufactured by a conventional method using an arc as a heat source. Comparative Example 2 was manufactured based on Japanese Patent Publication No. 59-34659 using a hollow mold under reduced pressure and using an arc as a heat source. (The number of samples n in each Example and Comparative Examples 1 and 2 was 5.) Next, a silicon single crystal was actually pulled in this quartz glass crucible. 35k heavily doped with sb
g of high-purity silicon was pulled into a silicon single crystal with a crystal orientation (100) and a diameter of 5 inches under conditions of approximately 1 mm/win.

These silicon single crystal glues, F, (dislO
When the CatiOn free) rate was investigated, the results were as shown in Table 2. (The number of samples n is 5 for each sample.) As is clear from Table 2, the silicon single crystal using the crucible of the example has a higher F rate than that using the crucible of the comparative example.

Furthermore, using the crucibles of Examples and Comparative Examples, approximately 35 kCI
After melting high-purity silicon and pulling a 5-inch diameter silicon single crystal with crystal orientation (100) under conditions of approximately 111 Ill/nin, re-inject high-purity silicon in the same amount as the pulled weight (recharge). Then, the quartz glass crucible was subjected to a durability test. Table 3 shows the service life and service life of the quartz glass crucible.

(The number of samples n is 5 for each sample.) As is clear from Table 3, according to the embodiment of the first invention,
The number of recharges has been significantly increased compared to before.

On the other hand, when the quartz glass crucible according to the first invention is used, there are almost no bubbles, so no open bubbles are generated due to Si erosion, and there is little deformation during use, so there is almost no fluctuation in the melt surface.

Furthermore, since no open bubbles are generated, the inner surface of the silica glass crucible is smooth, and it is possible to prevent foreign matter and polycrystals 3i from adhering to and growing on the inner surface during pulling.

Therefore, it was possible to suppress the occurrence of crystal defects during pulling of silicon single crystals, and the yield was significantly improved.

In the example of the apparatus shown in FIG. 1, the heat source of the manufacturing apparatus was arc heating using a carbon electrode. In the example of the apparatus shown in FIG. 2, the inside of the apparatus is sealed with an enclosure 30, the heat source 28 is a resistance heating heater, and by melting under pressure, a silica glass crucible with fewer bubbles can be obtained.

Furthermore, compared to arc heating, there is almost no wear and tear on the heater, so there is no contamination of the inner surface of the silica glass crucible with impurities, and the inner surface of the crucible is not roughened due to shedding of carbon particles.

In FIG. 2, 21 is a rotary drive device, 22 is a rotating shaft, 23 is an arrow indicating the direction of rotation, 24 is a rotatable enclosure, 25 is a gap, 2
6 is a hollow mold with good air permeability, 27' is a particle layer, and 29 is an electrode.

The intake port 15 is connected to the enclosure 30, and there is an intake pump 12 in the middle. Then, gas of N2, He, or a mixture thereof is introduced from the intake port 15 by the intake pump 12, pressurized, and exhausted from the exhaust port 13.

Next, the manufacturing method of the second invention will be explained using the example of the apparatus shown in FIG. 1 mentioned above.

In the manufacturing method of the second invention, the hollow mold 6 is rotated around a vertical axis in the direction of the arrow 3 using the rotary drive device 1, and the particles are formed as a layer on the inner wall of the hollow mold 6 and accumulated at the bottom. is added to the hollow mold 6 continuously or discontinuously. Particles 17 in the shape of a pot are formed. Then, heat from the heating source 8 is applied from the inside to the outside through the layer thickness of the particle layer 7.

82.8 hours at the latest from the start of melting of the particles. He or a mixed gas thereof flows in from the jet port 10. Thereafter, the inflow of this gas is stopped, and a gas other than this gas having a large molecular radius, such as Ar, N2, l'Je, etc., is allowed to flow in through the jet port 10 until melting is completed.

As a result, only a portion of the particle layer 7 is melted, the thin partial layer is semi-melted and sintered, and the remainder of the particle layer 7 remains in the particle state.

The obtained quartz glass crucible is cooled and then taken out from the hollow mold 6.

Actually, a quartz glass crucible with a mouth diameter of 356 cm and a height of 2541111 Il was manufactured. During melting, He gas was introduced 5 minutes before the start of melting, e gas was stopped 10 minutes after the start of melting, and Ar gas was immediately switched to Ar gas. Ar gas continued to flow until the end of melting. Gas pressure is H
Both e and Ar are 0,5 ko/c m2, flow ff125
Q/min.

The apparent porosity of the resulting quartz glass crucible was 0.1% or less. The blistering rate of this crucible under reduced pressure was measured. Measurement was carried out by sampling from the crucible at a pressure of 1 torr.
, heat treatment was performed at a temperature of 1600° C. and a holding time of 3 hours.

The results are shown in Table 4. (The number n of each sample is 5.) Comparative Example 1 was manufactured by a conventional method using an arc as a heat source.

Comparative Example 2 was manufactured based on Japanese Patent Publication No. 59-34659 using a hollow mold under reduced pressure and using an arc as a heat source.

Next, silicon single crystals were actually pulled using this quartz glass crucible. 35k heavily doped with Sb
The high-purity silicon of A was pulled into a 5-inch diameter silicon single crystal with a crystal orientation <100) at a rate of about imm/min.

These silicon single crystal glues, F, (dislo
When the cation free rate was investigated, the results were as shown in Table 5. (The number n of each sample is 5.) As is clear from Table 5, the silicon single crystal using the crucible of the example has an improved F rate than that using the crucible of the comparative example.

Furthermore, using the crucibles of Examples and Comparative Examples, approximately 35 kg of high-purity silicon was melted, and a silicon single crystal with a diameter of 5 inches with crystal orientation (100) was pulled at a rate of approximately in+m/min. The quartz glass crucible was tested for durability by recharging the same amount of high-purity silicon and continuing to pull it up. Table 6 shows the service life and service life of the quartz glass crucible.

As is clear from Table 6, according to the embodiment of the second invention,
The number of recharges has been significantly increased compared to before.

On the other hand, when the quartz glass crucible according to the second invention is used, there are almost no bubbles, so no open bubbles are generated due to Si erosion, and there is little deformation during use, so there is almost no fluctuation in the melt surface.

Furthermore, since no open bubbles are generated, the inner surface of the quartz glass crucible is smooth, and it is possible to prevent foreign matter and polycrystal S1 from adhering to and growing on the inner surface during pulling.

Therefore, it was possible to suppress the occurrence of crystal defects during pulling of silicon single crystals, and the yield was significantly improved. Furthermore, the manufacturing method of the second invention can also be carried out in the apparatus shown in FIG. In other words, gases such as H2°He, a mixture thereof, and gases other than these gases having a large molecular radius can be flowed in through the intake port 11.

11 standing i! As detailed above, according to the manufacturing method of the present invention, a crucible with almost no bubbles can be obtained, and the viscosity is also high, so it has remarkable effects such as greatly improving the yield when pulling silicon single crystals. It is something that plays.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a manufacturing apparatus for carrying out the manufacturing method of the present invention, and FIG. 2 is a diagram showing another manufacturing apparatus. 1... Rotation drive device 2... Rotating shaft 4... Rotatable enclosure 5... Gap 6... Hollow with good ventilation Mold 7...Particle layer 8...Heating source 9...Enclosure 10...Spout port 11...Vacuum pump Table-1 Blistering rate (%) Example 4.3 Comparative example 1 21.9 Comparative example 2 7.0 Table-2 D, F, rate (%) Example 79 Comparative example 1 69 Comparative example 2 73 Table-3 Number of service life Service time [h] Example 2 ,6 72.6 Comparative Example 1
1.0 30.4 Comparative Example 2 2.0
61.4 Table-4 Blistering rate (%) Example 3.6 Comparative example 1 21.9 Comparative example 2 7.0 Table-5 D, F, rate (%) Example 81 Comparative example 1 69 Comparative example 2 73 Table-6 Number of service life Service time [h] Example 2.8 85.2 Comparative example 1 N,0 30.4 Comparative example 2 2,0 61.4 Fig. 1 Fig. 2

Claims (2)

[Claims] (1) Finely ground particles made of crystalline quartz or amorphous quartz glass are placed in a hollow mold made of a carbonaceous material that is rotatable about a vertical axis, and are placed as a layer on the inner wall of the mold. , continuously or discontinuously so as to accumulate at the bottom, and by applying heat from the inside to the outside through the thickness of said layer, only a part of the layer is melted, and the thin partial layer is partially melted. In a method for producing a quartz glass crucible, which comprises sintering, allowing the remainder of the layer to remain in a particle state, and removing the obtained quartz glass crucible from the hollow mold after cooling, the process is performed at the latest from the start of melting of the particles. H_2, H
1. A method for producing a quartz glass crucible, which comprises introducing gases such as e.e. or a mixture thereof. (2) Finely ground particles made of crystalline quartz or amorphous quartz glass are placed in a hollow mold made of a carbonaceous material that can be rotated about a vertical axis, and a layer is formed on the inner wall of the mold. It is added continuously or discontinuously so that it accumulates at the bottom, and by applying heat from the inside to the outside through the thickness of the layer, only a part of the layer is melted, and the thin partial layer is half-melted. In a method for producing a quartz glass crucible, which comprises sintering, allowing the remainder of the layer to remain in a particle state, and removing the obtained quartz glass crucible from the hollow mold after cooling, the process is performed at least 5 days after the start of melting of the particles. Injecting H_2, He, or a mixture thereof for more than a minute,
A method for manufacturing a quartz glass crucible, which comprises: thereafter stopping the gas, and flowing a gas other than the gas having a large molecular radius until melting is completed.