JPH01148718A - Method of manufacturing quartz crucible - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a quartz crucible for pulling a single crystal, such as a silicon single crystal, and a quartz crucible manufactured by this method.

[Conventional technology]

Conventionally, silicon semiconductor single crystals are manufactured by melting polycrystalline silicon in a container and producing high-purity single crystal silicon (seed crystal).
The so-called Czochralski method, in which the tip is immersed and pulled up while rotating to grow a single crystal with the same orientation as the seed crystal, is widely used.

The containers used for this single crystal pulling are usually
A quartz crucible is used, but because of the difference in appearance due to the manufacturing method, it is different from a transparent quartz crucible, which has an opaque or translucent appearance due to the large amount of microbubbles contained within the fabric. There is a quartz crucible (hereinafter referred to as a translucent quartz crucible).

Translucent quartz crucibles can be manufactured with higher strength than transparent quartz crucibles by using powder as raw material.
In addition, large-diameter crucibles can be manufactured at relatively low cost, and the small bubbles contained in crucibles provide a more uniform heat distribution than transparent quartz crucibles, so they are widely used industrially.

However, when producing a single crystal using conventionally produced translucent quartz crucibles, there is a problem in that single crystallization becomes unstable and defects occur, reducing the yield of single crystals.

There are various factors that can cause unstable single crystallization during pulling, including the pulling equipment and conditions, and other factors include the reaction between silicon melt and quartz glass at high temperatures. , the inner surface is eroded and the surface becomes rough, or the erosion progresses further and the internal microbubbles are exposed, that is, the surface of the crucible in the part that comes into contact with the silicon melt surface is rough, resulting in a decrease in raw materials. The liquid level does not fall smoothly due to the vibration, and the slight hFd protrusions caused by the surface roughness of the quartz glass become the core of the crystallization reaction of the quartz glass, causing spots of cristobalite. A phenomenon occurs in which crystals are formed on the surface of the quartz crucible, and as the pulling process progresses, they detach from the quartz crucible and fall into the silicon melt, inhibiting crystal growth. Furthermore, near the inner surface of the quartz crucible, metal impurities are locally concentrated, for example, on the surface of microbubbles, and when pulled up, the high temperature heating promotes the crystallization of quartz glass into cristobalite, which is exposed on the inner surface of the quartz crucible. It becomes a spot of listoparite. Also, based on a similar argument, it is undesirable for the surface of a quartz crucible to have minute protrusions or scratches at the beginning.

Several inventions have been made regarding methods for manufacturing quartz crucibles. For example, in JP-A-59-213697, a part of the cylindrical part is made into a transparent tube by heating the crucible from the inside for a long time or by welding a transparent quartz tube, and at least the part in contact with the raw material melt is made into a single cylinder. A method for manufacturing a quartz crucible with a transparent quartz glass layer having the above thickness is described. Furthermore, US Pat. No. 4,528,163 discloses a quartz crucible in which the outside is formed of natural quartz particles, the inside is lined with synthetic quartz particles, and a smooth thin amorphous layer is formed on the surface of this lining layer. The manufacturing method is described.

Additionally, U.S. Pat. Nos. 4,416,680 and 4.632
, No. 686 describes a method for manufacturing a quartz crucible in which the outside is melted under reduced pressure as a method for reducing air bubbles in the crucible.

[The problem that the invention attempts to solve]

However, these prior documents describe a method for manufacturing a quartz crucible that simultaneously solves the technical problems of characteristics such as bubble-free property, smoothness, and uniformity required for the surface condition of the inner surface of the crucible, and a method that simultaneously provides those characteristics. There is no disclosure whatsoever regarding the quartz crucible.

Specifically, Japanese Patent Application Laid-Open No. 59-213697 discloses that, among the characteristics required for the surface condition of the inner surface of the crucible, the inner surface of the translucent quartz glass layer is further heated to prevent corrosion of the portion in contact with the raw material melt. It shows how to obtain it by melting a transparent tube and sandwiching a transparent ring-shaped part. However, the former method involves further melting the unmelted portion inside the quartz glass layer and, in some cases, causing residual gas that has formed as bubbles to rupture by heating and expanding, thereby opening the bubbles inside. However, this method does not completely remove air bubbles, and leaves traces of a large amount of air bubbles in the transparent quartz glass layer, which causes expansion again when exposed to reduced pressure during semiconductor pulling, leading to single crystal formation. It becomes unstable and causes defects, which reduces the yield. In addition, the latter method of melting a transparent tube is complicated, and the joints prevent the inner surface of the crucible from becoming a perfectly smooth surface, and annealing is required to remove distortion during melting, making the crucible Productivity deteriorates.

Also, in U.S. Patent No. 4,528,163, are there any improvements in the characteristics of the crucible inner surface by melting the inner and outer layers of the crucible at the same time and using synthetic quartz on the inner surface? , it is inevitable that voids remain, and during single crystal pulling, the melt is trapped in the bubbles and pores of the voids, significantly hindering the pulling operation.

Additionally, U.S. Pat. Nos. 4,416,680 and 4.632
．． No. 686 describes that air bubbles in a quartz crucible can be reduced by evacuation, but when the air bubbles pass through the outer quartz layer at a relatively low temperature, there is significant resistance, and the air bubbles reach the inner surface of the crucible. cannot be completely removed.

In addition, when pulling a single crystal, it is necessary to perform the pulling stably and to accurately control the amount of oxygen mixed into the single crystal. The quartz crucible surface becomes rough due to insufficient homogeneity and many bubbles, and the dissolution from the surface of the quartz crucible to the internal silicon melt is unstable.
It is difficult to satisfy such demands.

The present invention is advantageous in that the inner surface of the crystal is smooth and homogeneous with few irregularities, and more importantly, it is substantially bubble-free, so that the dissolution rate of the surface into the molten silicon is stable. A quartz crucible and a quartz crucible that do not cause the generation of cristobalite on the inner surface of the quartz crucible due to surface roughness or other reasons, and furthermore, the surface of the quartz crucible is kept smooth, so that single crystal pulling can be performed extremely stably. It is an object of the present invention to provide a method for manufacturing a quartz crucible that allows the quartz crucible to be manufactured extremely easily.

[Means for solving problems]

Therefore, in the present invention, a translucent quartz crucible formed by heat treating at least one kind of silicon dioxide powder among crystalline and non-crystalline silicon dioxide powder is fitted into a rotary mold, and the mold is rotated. Meanwhile, a heating source is inserted into the quartz crucible to create a high-temperature gas atmosphere in the quartz crucible, and a small amount of at least one kind of silicon dioxide powder among crystalline and amorphous silicon dioxide powder is added to the high-temperature gas atmosphere. at least a portion of the silicon dioxide powder is melted, and the molten powder is scattered and deposited on the inner surface of the quartz crucible to form a substantially bubble-free transparent quartz glass layer on the inner surface of the quartz crucible. Be sure to form it integrally to a predetermined thickness.

Further, while rotating a rotary mold, an unmelted quartz crucible preform made of at least one kind of silicon dioxide powder among crystalline and amorphous silicon dioxide powder is formed in the mold, A heating source is inserted into the preform to create a high-temperature gas atmosphere inside the preform, and the preform is heated from the inside to melt and vitrify. At least one type of silicon dioxide powder among the silicon dioxide powders is passed through the silicon dioxide powder little by little to melt at least a portion of the silicon dioxide powder, and the molten powder is scattered and deposited on the surface of the preform, so that it is substantially free of silicon dioxide powder. A transparent quartz glass layer of bubbles was integrally formed on the inner surface of the preform to a predetermined thickness.

[Effect]

Transparent or at least outer fil as a substrate in a rotary mold
A molded body of a quartz crucible having a translucent layer is fitted into a part of lj, or by using the centrifugal force and gravity of the rotating body, it is made of at least one of crystalline and amorphous silicon dioxide powder. A preform for an unmelted quartz crucible is formed, and a high-temperature gas atmosphere is created inside this by arc discharge between the electrodes, and the surface of the quartz crucible fitted in advance or the unmelted quartz is heated. The crystals are heated sufficiently to melt the inside of the crucible preform, and at the same time, the crystals are of an appropriate particle size so that they do not fly out of the system due to the flow of high-temperature gas, and so that they fall in the heated atmosphere and reach the crucible surface. Silicon dioxide powder consisting of at least one type of silicon dioxide powder and amorphous silicon dioxide powder is continuously fed in small amounts from the top, and is passed through a particularly high-temperature part of a high-temperature gas atmosphere to melt at least a part of the powder particles. , the molten powder is allowed to fly onto the molten surface of the substrate, the fused molten powder is welded to the surface of the substrate, and before a layer of the fused molten powder is further laminated thereon, conduction heat and The melt progresses due to the radiant energy of the high-temperature heat source, and is integrally fused with the substrate surface, forming a thin layer that is almost completely bubble-free. The base surface rotates with the rotating mold, and is melted by flying molten particles.
The added layers are laminated over at least a constant width in the thickness direction of the side surface of the substrate, and the additional fused layer on the surface of the substrate is grown to a constant thickness. Since the layer fused and added by the flying molten particles is sufficiently molten and thin, no minute air bubbles are allowed to remain when the molten layer is cooled and solidified. Since the substantially bubble-free transparent quartz glass layer is grown integrally with the substrate in this manner, the adhesion of such a fused layer to the substrate is extremely good. As can be understood from the above explanation, this molten additional layer is homogeneous and there are no bubbles, so impurities in the molten glass layer do not precipitate abnormally in some areas, and are removed internally during the actual single crystal pulling process. When holding a silicon melt, when the surface is eroded by the silicon melt, the eroded surface is smoother than that of the conventional translucent quartz crucible, and this significantly reduces the vibration of the silicon melt surface. , which is useful for improving the single crystallization rate, that is, improving productivity. In addition, since the fused transparent quartz glass layer is homogeneous, it stabilizes the dissolution rate of the quartz glass surface in the silicon melt, and when controlling the oxygen concentration in the pulled single crystal, it is possible to stabilize the dissolution rate of the quartz glass surface in the silicon melt. facilitate concentration control. An even greater advantage is that the formation of cristobalite on the silicon melt contact surface of the quartz crucible during the pulling process and the occurrence of single crystal disturbances due to exfoliation of the cristobalite accompanying its phase transition are significantly reduced.

The formation of such cristobalite is caused by the irregularities on the surface of the quartz crucible, impurities near the surface, and the part where the regularity of incompletely melted slick crystals remains, which becomes the nucleus for the formation of cristobalite, and the interface between the crucible surface and the silicon melt becomes the nucleus of cristobalite formation. It is thought that the high concentration silicon dioxide atmosphere causes cristobalite crystals to selectively grow toward the crucible surface. Cristobalite is exposed to high temperatures (
When the silicon molten surface lowers and is exposed to the gas atmosphere in the pulling chamber and is cooled, it becomes an α-type, which causes peeling.

〔Example〕

Examples of the present invention will be described below. In FIG. 1, a translucent quartz crucible molded body 3 which has been heated and formed in advance is fitted into a cavity of a rotary mold 1 having a support rotation shaft 2. As shown in FIG. While the mold 1 is rotating, the heating source 5 is inserted into the molded body 3. Further, a closing plate 71 is provided so as to leave the ring-shaped open lower portion 5 at the opening of the molded body 3, and thus the inside of the molded body 3 is brought into a semi-sealed state. At the same time, a hot gas atmosphere 8 is created by the heating source 5, and a certain amount of crystalline or amorphous high purity silicon dioxide powder 6 is passed through this hot gas atmosphere 8. The silicon dioxide powder 6 may be a mixture of crystalline and non-crystalline powders, and at least a part of it (7 g) is melted and adhered to the inner surface, so that the transparent quartz glass N4 is integrally fused. Layered.

The silicon dioxide powder 6 is normally discharged little by little from a supply tank 9 having a stirring propeller 91 into the high-temperature gas atmosphere 8 through a nozzle 93 while the supply amount is controlled by a quantitative feeder 92 .

The mold 1 may have a water cooling mechanism, and the shape and size of the cavity of the mold 1 are adapted to the shape and size of the quartz crucible to be manufactured.

The material of the mold 1 only needs to have heat resistance, mechanical strength, and workability, and may be metal, carbon, or the like.

In the illustrated example, a translucent quartz crucible molded body 3 formed by heating and molding silicon dioxide powder is fitted into the cavity of the mold 1, and the silicon dioxide powder is adhered to the inner surface of the molded body 3. Instead of using a heat-treated molded body 3, crystalline or non-crystalline silicon dioxide powder (a mixture of crystalline and non-crystalline powder) is added to the cavity while rotating the mold 1. A preformed body for a quartz crucible is formed on the inner wall surface of the cavity of the mold 1 by centrifugal force, and silicon dioxide powder 6 for the transparent layer is supplied.
The crucible may be formed by heating the preform while simultaneously supplying the preform. If the preform and the silicon dioxide powder are heated simultaneously in this way, it is advantageous that the formation of the opaque quartz glass layer and the application of the transparent quartz glass layer can be carried out in the same mold.

In addition, when forming a preform, if the rotation speed of the mold 1 is too high, the supplied silicon dioxide powder will move toward the side wall of the cavity, and the deposition of powder on the bottom may become too thin. Therefore, it is necessary to adjust the rotation speed.Furthermore, since the deposited thickness of the powder in the preform may be uneven depending on the location on the inner surface of the mold 1, a molding plate is used to make the deposited thickness uniform. By removing the excess from the upper part of the mold 1, a quartz crucible with a stable wall thickness can be manufactured.

Furthermore, the rotational speed of the mold 1 is determined in relation to the amount of heating energy supplied from the heating 'a5, within a range in which particles of the silicon dioxide powder 6, which are at least partially melted, do not fall from the inner surface of the compact 3. Usually 50 to 300 r, D,
It is about lIl.

Although the method for manufacturing a quartz crucible of the present invention can be sufficiently effective in a normal air atmosphere, it is preferable to use an atmosphere with a cleanliness level of, for example, class 1.000 to prevent contamination of foreign matter.

As the heating source 5, arc discharge, high frequency plasma discharge, etc. can be used, but two carbon electrodes 51.
52 is preferred. In this case, a DC or AC high voltage current is supplied from the external power supply 10 to the carbon quantities tif 151, 52 to generate arc discharge. The heating energy supplied by such arc discharge or high frequency plasma discharge is required to be sufficiently large.

When arc discharge using a carbon electrode is used, for example, heating is concentrated at the center of the bottom of the molded body 3 to first melt the surface of the hem. Next, a high temperature gas atmosphere generated by arc discharge 8
Silicon dioxide powder 6 is passed through it. After adjusting the supply amount so that the particles of silicon dioxide powder 6 adhere to the molded body 3 with a predetermined thickness, gradually move the tip discharge portions of the carbon electrodes 51 and 52 perpendicularly along the inner surface of the molded body 3. move in the direction.

Note that the amount of silicon dioxide powder 6 supplied and the carbon electrode 54
．． It is also possible to control the thickness of the transparent quartz glass layer 4 at a specific location on the molded body 3 by adjusting the moving speed of the transparent quartz glass layer 4 .

When the heat source 5 is brought close to a certain position on the inner wall of the crucible, does the silicon dioxide powder 6 that adheres to the inner surface of the molded body 3 in a molten state easily solidify immediately at a position away from the heat source? As mentioned above, the amount of heating energy supplied and the type 1
By adjusting the rotational speed of the quartz crucible, the next particles of silicon dioxide powder 6 can be attached while keeping the surface of the quartz crucible in a molten state.

In addition, the transparent quartz glass layer fused to the inner surface of the molded body is
If the rotation speed of mold 1 is too slow, the surface of the molded object will become locally high temperature, and as the inside of the molded object melts, the surface layer will become excessively fluid, causing it to flow down or deform. Therefore, it is natural that the amount of heat of the heating source 5 and the rotation of the mold 1 must be appropriately controlled as described above.

The transparent quartz glass layer may be formed to a predetermined thickness at once, but the carbon content &51.52 may be repeatedly moved in one direction from below to above or from above to below the inner surface of the molded body 3. Alternatively, the transparent quartz glass layer 4 of a predetermined thickness may be deposited by reciprocating between the upper and lower sides.

In addition, as mentioned above, when using a preformed body made of silicon dioxide powder instead of the heat-treated molded body 3,
The above operation is performed while the preform is almost completely melted by arc discharge.

Further, since the arc discharge is formed so as to bulge in all directions from the tip discharge portion of the carbon electrodes 51 and 52, the particles of the silicon dioxide powder 6 that have passed through the high temperature gas atmosphere 8 due to the arc discharge are inside the molded body 3. Spreads over a wide area of the surface.

Furthermore, in the present invention, by providing the closing plate 71, the inside of the quartz crucible base 3 becomes a semi-sealed state, and the generated high-temperature gas is disturbed and rises along the inner surface of the crucible, and the ring-shaped open lower 5 through the quartz crucible (
(arrow in Figure 1). Therefore, the particles of silicon dioxide powder 6 that have passed through the high-temperature gas atmosphere 8 are uniformly dispersed in the lateral direction of the crucible due to this upward turbulent airflow, and together with the above-mentioned scattering effect of the arc discharge, the particles of silicon dioxide powder 6 are distributed on the inner surface of the compact 3. Adheres extremely evenly. Furthermore, if the molded body is semi-sealed and arc discharged, instantaneous expansion will occur and the internal temperature will easily increase, and the temperature will become more uniform over the entire surface of the quartz crucible, resulting in a molten or semi-molten state. The silicon dioxide particles in the molten state adhere to the surface of the molded body, which has a great effect on making the transparent layer substantially bubble-free, and also increases the integral fusion of the molded body and the silicon dioxide particles and their homogenization. This makes it possible to save energy and helps reduce costs.

Note that the ratio at which the closing plate 71 closes the upper opening of the molded body 3 may be determined based on the conditions of the heating source 5, the size of the molded body 3, etc., but is usually 20 to 95% of the upper opening. It is preferable to occlude the

Further, the ring-shaped opening lower 5 may be formed by installing the closing plate 71, which is larger in size than the upper opening of the molded body 3, with a gap above the upper opening of the molded body 3. .

Further, in the present invention, as shown in FIG. 2, the tip of the carbon electrode may be inclined toward the side surface of the molded body 3 with respect to the axial direction of the support rotation shaft 2.

By tilting in this way, it is possible to accurately control the melted area on the inner surface of mold #3 to a predetermined width. In this case, the nozzle 93 that discharges the silicon dioxide powder 6 is also tilted in the same direction at the same time, so that the main direction in which the particles of the silicon dioxide powder 6 that have passed through the high-temperature gas atmosphere 8 are discharged is accurately aligned with the above-mentioned melting region. This results in more complete fusion of the particles of silicon dioxide powder 6 with the inner surface of the molded body 3, resulting in a more uniform transparent quartz glass layer.

In the present invention, the size of the silicon dioxide powder 6 is usually 30~
It is preferably about 1,000 μm. If the size is less than 30 μm, there will be a problem that the particles will be scattered due to upward turbulence of the high-temperature gas atmosphere 8 without being sufficiently heated. On the other hand, if the size is larger than 1,000 μm, the transparent quartz glass layer will adhere to the inner surface of the molded body 3 before the heating energy is sufficiently transmitted to its center, and will not melt even after further heating. This may cause the inconvenience of unevenness.

In addition, the supply amount of silicon dioxide powder 6 is as described above.
It is determined by the heating energy emitted by the heating source 5, the moving speed of the heating source 5, the rotational speed of the mold 1, etc., but usually 5.
~300 t/min is preferable.

Note that even if the size and supply amount of the silicon dioxide powder 6 are within the above-mentioned preferred range, as mentioned above, it is necessary that the heating energy of the arc discharge or high-frequency plasma discharge as a heating source is sufficiently large. It is.

The silicon dioxide powder 6 may be either crystalline or amorphous, and is required to be a highly pure material in order to reduce the presence of impurities in the transparent quartz glass layer to be formed. In this way, high purity transparent inner 1ITII
If a layer is formed, silicon dioxide powder, which is the material for the quartz glass heat-treated molded body or preformed body,
There is no need to require it to be highly pure, which makes it possible to reduce the manufacturing cost of quartz crucibles.

In the present invention, the transparent quartz glass layer is formed by melting and adhering silicon dioxide powder particles little by little through the above-described operation, so there is almost no chance of air bubbles being incorporated between individual silicon dioxide powder particles. Also, impurities are extremely reduced.

Furthermore, the number of hydroxyl groups can be reduced, and if# thermal properties are increased.

When the transparent quartz glass layer is made from silicon dioxide or natural quartz crystal powder, the number of hydroxyl groups is originally small. Passing through a gas atmosphere, the powder is exposed to extremely high temperatures in the form of fine particles, so that hydroxyl groups are reduced by elimination or other impurities are removed by volatilization.

Furthermore, the thickness of the transparent quartz glass layer can be easily and accurately controlled by adjusting the supply amount of silicon dioxide powder and the rotation speed of the mold, and a sufficiently thick transparent layer can also be formed.

Furthermore, in the present invention, in addition to the combination of two carbon electrodes as shown in FIGS. 1 and 2, it is also possible to combine three or more carbon electrodes. It is also possible to move these electrodes appropriately.

In addition, as a heating source, an oxyhydrogen flame may be considered in this pond, or in this case, the heat source temperature is lower than that of high-frequency discharge or arc discharge, so the particle size and supply rate of silicon dioxide powder 6 described below may be reduced. In addition, it is necessary to suppress the moving speed of the heating source 5 to a low level. As a result, hydroxyl groups of 500 p, p, ff1. This is not preferable since the heat resistance deteriorates.

In addition, in the present invention, as shown in FIG.
Then, the nozzle 93 may be inserted into the molded body 3 and the same operation as described above may be performed to form the transparent quartz glass layer 4. In this case, the molded body 3 is fitted into the cavity of the mold, and
The molded body 3 may be supported by a support member 11 which can be freely removed from the mold, and the mold 1 may be rotated by a driving roller 12 via the support member 11.

As described above, the present invention allows particles of silicon dioxide powder that have passed through a high-temperature gas atmosphere to adhere little by little to the inner surface of a molded body, thereby forming extremely uniform transparent quartz without incorporating air bubbles between the particles. A glass layer can be applied.

This transparent quartz glass layer has the property of being uniform and is substantially free of bubbles, so that when a single crystal is pulled, there is almost no rupture due to the expansion of bubbles, which is observed in conventional quartz crucibles. Therefore, the amount of quartz eluted from the surface layer of the quartz crucible, that is, the amount of oxygen supplied into the silicon melt can be accurately controlled. in general,
The surface of the crucible comes into contact with silicon, which is a molten body, and a part of it melts due to chemical action with the silicon, supplying silicon and oxygen as solutes into the silicon.

At this time, the surface of the crucible according to the method of the present invention is of high purity and there are no bubbles in the IJ, so the silicon melt 1iiLffl is stable, and it is easy to control the oxygen concentration mixed into the melt in the single crystal pulling process, and the integrated circuit element By increasing the oxygen concentration in the silicon substrate used as the substrate, it is possible to increase the mechanical strength or improve the precision of control aimed at the intrinsic getter effect. Furthermore, if the inner layer of the crucible contains air bubbles, the air bubbles usually lack uniformity in size and distribution, and the areas where the air bubbles are concentrated tend to elute from the inner surface of the crucible. The pulling up of vibrations greatly affects the disorder of the single crystal, but according to the present invention, there is no such effect.

Furthermore, if air bubbles are present on the inner surface of the crucible, the metal impurities in the quartz glass may be concentrated on the surface of the air bubbles, or when undesirable irregularities in the solution are exposed due to the air bubbles or the melting of the quartz crucible surface, the cristobalite may be formed at high temperatures. Although there is a possibility that it may become a crystal nucleus, there is no such possibility according to the present invention.

The formation of this cristobalite is thought to be caused by metal contamination on the surface, but this cristobalite is first formed by β
Formed in the mold, then when the crucible cools, it converts to the α form and peels off from the surface, disrupting silicon single crystallization.
It is easy to understand that according to the present invention, the generation of cristobalite can be effectively prevented due to the formation of such a highly pure transparent quartz glass layer.

The criterion for the transparent quartz glass layer 4 to be substantially bubble-free is that it contains extremely few bubbles compared to ordinary transparent quartz glass for semiconductors manufactured by conventional quartz crucible manufacturing methods. Quartz glass for semiconductors has a size of 100 μm or more that can be observed with the naked eye.
It contains a large amount of bubbles of about 1 rnrn and minute bubbles that can be observed by light scattering by the bubbles.

As a specific example of bubble-free conditions in the present invention, six unused quartz crucibles were placed under a microscope at a magnification of 30 times ("rk, with a mirror field of view of 8++ J, and four locations on the inner wall of each crucible were observed.
We observed a total of 30 locations, including 5 locations, including 1 location on the bottom.
Each bubble with a diameter of 20 μm or more was only slightly visible in 2 to 3 locations. As an example, out of the 30 measurement points mentioned above, there was only one spot where two bubbles with a diameter of 20 μm or more were observed.
There were two locations where one bubble was seen, and the density of bubbles was 0.
13 pieces/8ml1I (approximately 1.6 pieces/in terms of Icd)
, ff1), which makes it possible to create a layer with high homogeneity.

Therefore, in conventional quartz crucibles, when pulling a silicon single crystal under reduced pressure, the inner surface of the crucible becomes uneven due to the expansion and bursting of bubbles, and the vibrations on the surface of the silicon melt due to these unevenness have a large effect on the disorder of the pulled single crystal. However, according to the present invention, there is no such influence.

Usually, the thickness of such a transparent quartz glass layer is preferably at least 0.3 n+m, and in fact preferably 0.8 to 1 nun or more.

(Experiment example) Next, an experimental example of the present invention will be explained.

Experimental Example 1 A quartz crucible with a diameter of 1.4 inches (
A sample of the present invention) was prepared.

In addition, a 14-inch diameter quartz crucible (comparative sample) was prepared using a conventional method.

Regarding the above sample, in order to examine the effect of the transparent quartz glass layer according to the present invention, changes in the surface thickness of the inner surface of the crucible due to single crystal pulling were measured. That is, the roughness of the inner surface of the crucible was measured after 110 hours of single crystal growth using the inventive sample and the comparative sample.

The measurement was performed using a stylus type surface roughness meter (manufactured by Koita Research Institute).

FIG. 4 shows the measurement results of the surface roughness of the sample of the present invention after single crystal growth, and FIG. 5 shows the measurement results of the surface roughness of the comparative sample after single crystal growth.

As is clear from each figure, the quartz crucible of the present invention maintains a fairly smooth inner surface with a maximum roughness of 33.7 μm even after use, whereas the roughness of the conventional crucible is approximately that of the sample of the present invention. It becomes 2.5 times as large, which means that in the crucible of the present invention, the molten surface of silicon is less likely to be disturbed.

Further, FIGS. 6A and 6B show the state of ignition on the inner surface of the crucible after the completion of crystal growth.

FIG. 6A shows the inner surface of the sample of the present invention, and FIG. 6B shows the inner surface of the comparative sample. According to this, it can be seen that the occurrence of cristobalite on the inner surface of the crucible of the present invention is significantly less than that of the conventional crucible.

That is, the inner surface of the quartz crucible of the present invention is extremely homogeneous and has few protrusions that serve as nuclei for crystallization reactions, so that point devitrification due to cristobalite is less likely to occur.

Experimental Example 2 The results of silicon single crystal production when using the present invention sample and comparative sample produced in the same manner as Experimental Example 1 are shown.

The manufacturing conditions were under reduced pressure (10 mb) under an argon atmosphere,
Pulling speed is approximately 0.5IiIn/min, crucible rotation is 1
Or, Lm, (reverse rotation with seed crystal) with a diameter of 100 mm,
A single crystal with a length of 90 c11] was produced (the operating time for one batch was about 40 hours).

The single crystal growth success rate of the manufactured single crystal ingot was determined. The results are shown in Table 1.

Here, (li-crystal growth success rate is the total number of pulling up ty of single crystal ingots (indicated as "number of repetitions" in the table), failure rate of single crystal growth (li-crystal growth success rate)
・Part! It is expressed as a percentage of the number of ingots excluding those containing non-crystallized portions.

Table 1 Single crystal growth success rate From Table 1, it is clear that the quartz crucible according to the present invention does not always produce stable single crystals.

On the other hand, the success rate of single crystal growth in the comparative samples is low.
This is thought to be caused by the unevenness of the surface of the quartz crucible and the peeling of the generated cristobalite.

Next, a diameter of 20 μm in the transparent quartz glass layer of the quartz crucible manufactured according to the present invention and the quartz crucible manufactured by the conventional method used for pulling the silicon single crystal described above was
The number of bubbles mentioned above is shown in Table 2, and the state of the vertical cross section of the straight body part and the bottom part is shown in FIGS. 7 and 8.

Table 2 Physical properties of quartz crucible after single crystal pulling Measurements were taken at a total of 30 locations, including 5 locations.

What you need to be careful about here is that quartz crucibles are heated at a high temperature of about 1450°C for a long time and under reduced pressure.
Even if it is considered bubble-free before its use, the individual bubbles will expand due to the softening of the quartz glass and will be easier to observe. In other words, the bubbles that are melted and sealed in the quartz glass layer during quartz crucible manufacturing are caused by atmospheric gas at atmospheric pressure (or air if quartz crucible manufacturing is performed in air).
Naturally, it expands under high temperature and reduced pressure. However, as shown in Table 2 and FIGS. 7A and 7B, the quartz crucible according to the present invention has a clearly bubble-free transparent quartz glass layer on its inner surface even after use. On the other hand, quartz crucibles made using the conventional method either have a thin transparent quartz glass layer on the inner surface that is bubble-free to some extent before pulling the silicon single crystal, or bubbles expand during the pulling of the silicon single crystal, and these bubbles interact with each other. As a result, 7g of clearly dense bubbles can be seen on the inner surface of the quartz crucible after pulling the silicon single crystal (Table 2).
and Figures 8A and 8B).

〔Effect of the invention〕

In the present invention, particles of silicon dioxide powder that have passed through a high-temperature gas atmosphere are attached to the inner surface of the crucible, and the high-temperature gas atmosphere completely melts and adheres the particles to the quartz crucible, so that the particles are substantially bubble-free. A transparent quartz glass layer of almost pure components with few hydroxyl groups can be integrally provided on the inner surface of the crucible so that its thickness can be adjusted.

Therefore, when pulling a single crystal, there is almost no occurrence of irregularities on the inner surface of the crucible or the generation of cristobalite, and stable single crystal pulling is possible.

In addition, the present invention has extremely good workability, and it is possible to easily manufacture a quartz crucible with superior characteristics compared to conventional methods, and it is also possible to precisely control the thickness of the transparent quartz glass layer. be.

Furthermore, in the present invention, since there are no impurities or air mixed in the transparent layer, the purity required for the material in order to obtain the various effects described above is only high purity silicon dioxide powder for forming the transparent quartz glass layer. Therefore, it is possible to reduce the manufacturing cost of the quartz crucible.

Furthermore, the amount of quartz dissolved in the silicon melt during pulling of the single crystal becomes constant, and it is easy to control it, making it possible to pull a high-purity silicon single crystal.

Further, the quartz crucible of the present invention hardly causes any unevenness on the inner surface of the crucible or the generation of cristobalite during pulling of a single crystal, and thus enables stable pulling.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a manufacturing apparatus for explaining an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a manufacturing apparatus for explaining a carbon electrode according to an embodiment of the present invention. Figure 3 is
FIG. 4 is a graph showing the roughness of the inner surface of the quartz crucible after single crystal growth in the quartz crucible according to the present invention, and FIG. 6A and 6B are graphs showing the roughness of the inner surface of a quartz crucible after single crystal growth by the method, and FIGS. 6A and 6B are drawings showing the state of point devitrification on the inner surface of the crucible after single crystal growth. 6B shows the inner surface of the crucible of the present invention, FIG. 6B shows the inner surface of the conventional crucible, FIGS. 7A and 7B are drawings showing the longitudinal cross-section of the wall of the crucible of the present invention, and FIG. 8A and FIG. 8B is a drawing showing a longitudinal section of a wall of a conventional crucible. DESCRIPTION OF SYMBOLS 1... Mold, 2... Support rotating shaft, 3... Molded object, 4
...Transparent quartz glass 1a, 5...Heating source, 51,5
2゜53...carbon electrode, 6...silicon dioxide powder,
71... Closure plate, 75... Opening, 8... High temperature gas atmosphere, 9... Supply tank, 91... Stirring propeller, 92... Quantitative feeder, 93... Nozzle, 10
. . . External power supply, 11 . . . Support member, 12 . . . Drive roller. Representative Yasushi Ishikawa Figure 1 Figure 2 Figure U Figure 3 1mm Measurement length [mm] Maximum roughness: 33.7μm Figure 4 Inner surface roughness m of the quartz crucible according to the present invention after single crystal growth
m Measurement length (: mm) Maximum roughness 285μlη Fig. 5 Inner surface roughness after single crystal growth of a quartz crucible according to the conventional method No. 6A ll] [Ii Inner surface roughness after crystal growth of a quartz crucible according to the present invention No. 6B Figure 7A: Inner surface of quartz crucible after I11 crystal growth according to conventional method
Outside Figure 7B Vertical section (bottom) of the quartz crucible according to the present invention No. 8A
Figure: 7 tons of quartz crucible made by conventional method! 4i inside square side (straight body part)
jl Outside Figure 8B

Claims (1)

[Claims] 1. A translucent quartz crucible formed by heat-treating at least one kind of silicon dioxide powder among crystalline and amorphous silicon dioxide powder is fitted into a rotary mold, A heating source is inserted into the quartz crucible while rotating the mold to create a high-temperature gas atmosphere in the quartz crucible, and at least one kind of dioxide from crystalline and non-crystalline silicon dioxide powder is added to the high-temperature gas atmosphere. Silicon powder is passed little by little to melt at least a portion of the silicon dioxide powder, and the molten powder is scattered and deposited on the inner surface of the quartz crucible, thereby forming a substantially bubble-free transparent quartz glass layer over the quartz crucible. A method for manufacturing a quartz crucible, characterized by forming the crucible integrally on the inner surface to a predetermined thickness. 2. A patent claim characterized in that the opening of the quartz crucible is partially closed and a peripheral portion thereof is opened in a ring shape, so that the high temperature gas in the high temperature gas atmosphere is moved along the inner surface of the quartz crucible. A method for manufacturing a quartz crucible according to item 1. 3. The method for manufacturing a quartz crucible according to claim 1 or 2, characterized in that arc discharge between carbon electrodes is used as the heating source. 4. The method for manufacturing a quartz crucible according to claim 3, wherein the number of carbon electrodes is three. 5. The particle size of the silicon dioxide powder is 30 to 1,
The method for manufacturing a quartz crucible according to any one of claims 1 to 4, characterized in that the quartz crucible has a diameter of 0.000 μm and a feeding rate of 5 to 300 g/min. 6. Forming an unmolten quartz crucible preform made of at least one type of silicon dioxide powder among crystalline and amorphous silicon dioxide powders in the rotary mold while rotating the rotary mold; A heating source is inserted into the preform to create a high-temperature gas atmosphere inside the preform, and the preform is heated from the inside to melt and vitrify. At least one type of silicon dioxide powder among the silicon dioxide powders is passed through the silicon dioxide powder little by little to melt at least a portion of the silicon dioxide powder, and the molten powder is scattered and deposited on the surface of the preform, so that it is substantially free of silicon dioxide powder. A method for manufacturing a quartz crucible, comprising forming a transparent quartz glass layer of bubbles to a predetermined thickness on the inner surface of the preformed body in an integral manner. 7. A patent characterized in that the opening of the preform is partially closed and the peripheral part thereof is opened in a ring shape, so that the high-temperature gas in the high-temperature gas atmosphere is moved along the surface of the preform. A method for manufacturing a quartz crucible according to claim 6. 8. A method for manufacturing a quartz crucible according to claim 6 or 7, characterized in that arc discharge between carbon electrodes is used as the heating source. 9. The method for manufacturing a quartz crucible according to claim 8, wherein the number of carbon electrodes is three. 10. The particle size of the silicon dioxide powder is 30-1
. , 000 μm, and the feeding rate is 5 to 300 g/min. 11. A translucent quartz crucible formed by heat treating at least one type of silicon dioxide powder among crystalline and non-crystalline silicon dioxide powders is fitted into a rotary mold, and while the mold is rotated, A heating source is inserted into the quartz crucible to create a high-temperature gas atmosphere in the quartz crucible, and at least one type of silicon dioxide powder among crystalline and amorphous silicon dioxide powder is passed little by little into the high-temperature gas atmosphere. melting at least a portion of the silicon dioxide powder;
The molten powder is scattered and adhered onto the inner surface of the quartz crucible, and a substantially bubble-free transparent quartz glass layer is integrally formed on the inner surface of the quartz crucible with a predetermined thickness. quartz crucible. 12. Forming an unmolten quartz crucible preform made of at least one kind of silicon dioxide powder among crystalline and amorphous silicon dioxide powders in the rotary mold while rotating the rotary mold; A heating source is inserted into the preform to create a high-temperature gas atmosphere inside the preform, and the preform is heated from the inside to melt and vitrify. At least one type of silicon dioxide powder among the silicon dioxide powders is passed through the silicon dioxide powder little by little to melt at least a portion of the silicon dioxide powder, and the molten powder is scattered and deposited on the surface of the preform, so that it is substantially free of silicon dioxide powder. A quartz crucible characterized in that a transparent quartz glass layer of bubbles is integrally formed on the inner surface of the preformed body at a predetermined thickness.