KR20130139784A - Method for filling raw material, and method for preparaing single crystal - Google Patents

Abstract

The purpose of the present invention is to provide a method for suppressing height unevenness of raw material injected into a quartz melting pot in manufacturing single crystals. In the process of filling the raw material, a recharge pipe has a cylindrical member, and a cone valve for opening and closing the bottom opening part of the cylindrical member. The recharge pipe accommodates the raw material. The recharge pipe is set in a chamber, and the raw material is filled successively in the recharge pipe more than two times by opening the opening part of the cylindrical member with the cone valve. At least one filling uses the recharge pipe having a different cone angle of the cone valve.

Description

Raw material filling method and manufacturing method of single crystal {METHOD FOR FILLING RAW MATERIAL, AND METHOD FOR PREPARAING SINGLE CRYSTAL}

The present invention relates to a method for charging a raw material into a quartz crucible using a charge tube in the production of a single crystal.

As a method for producing a silicon single crystal used as a substrate of a semiconductor integrated circuit, a CZ (Czochralski) method or an MCZ (magnetic field applied Czochralski) method for applying a magnetic field is generally used. In such a CZ / MCZ method, a silicon raw material can be filled and melted in a quartz crucible, and a seed crystal is complexed with the melt, followed by pulling up to grow a silicon single crystal. In the single crystal manufacturing apparatus (impression apparatus) of the CZ / MCZ method, the heater which heats a molten liquid is provided in the main chamber, and the quartz crucible which accommodates a molten liquid is provided in the inside.

Generally, first, a raw material is put into this quartz crucible and a raw material melts by heater heating. In recent years, due to the large diameter and long crystallization of silicon single crystals, the raw material initially placed in the quartz crucible is not sufficient, and additional raw materials may be added. This is called additional charge, and in the same way as the charge described later, the raw material is placed in a charge tube having a conical cone (cone valve) at the bottom thereof, and the raw material is put into a quartz crucible from the charge tube. . After all of these raw materials are melted, growth of silicon single crystal is started.

The quartz crucible is filled with a melt in which the raw material is dissolved, and silicon single crystal is grown therefrom. The grown single crystal is received and cooled in the pulling chamber connected through a gate valve on the top of the main chamber. Then, the single crystal is taken out from this pulling chamber.

In this production, if one single crystal is grown from one quartz crucible, the growth is terminated at this point, but the production cost is high because the quartz crucible cannot be broken and reused. Therefore, there are cases where multiple operations for growing a plurality of single crystals from one quartz crucible are performed. In this case, since the melt in the quartz crucible is reduced by the grown crystal powder after the single crystal growth, the following single crystal cannot be grown as it is. Therefore, the recharging which inputs a raw material again in order to compensate for this decrease is performed.

As a recharge method, the rod recharge method, the method of supplying from the raw material tank as disclosed in patent document 1, etc. have been proposed for a long time. However, the technique handled by many patent documents is a method of accommodating a raw material in the charge tube which has a conical valve in the lower end, and inject | pouring the raw material accommodated in the charge tube in a quartz crucible. Patent Documents 2 and 3 disclose the basis of this technique. For example, in patent document 3, the cone angle (vertical angle) of a cone valve is described as 40-100 degree | times, More preferably, it is 60-90 degree.

By using such a method, the silicon single crystal is taken out from the pulling chamber divided by the gate valve, and then the charge tube containing the raw material is suspended by wire, and the furnace internal pressure in the pulling chamber is adjusted to the furnace internal pressure in the main chamber by vacuum attraction. After that, the gate valve is opened to feed the raw materials.

For example, Patent Document 4 teaches an improvement of covering a wire with a protective tube, and Patent Document 5 teaches an improvement of enclosing a wire in a charge tube or a conical valve to prevent breakage, and Patent Document 6 teaches an improvement in raw material fall prevention. The technique which added a little improvement to the publicly disclosed technique of patent documents 2 and 3, such as teaching the improvement which slots a conical valve for the said is disclosed. However, the basic technology is the contents of Patent Documents 2 and 3.

As can be seen from this much literature, the recharging method using a recharge tube is one of the techniques widely used. However, there is no addition of examination to the angle of the conical valve after patent document 3.

The raw materials to be filled as described above are generally polycrystalline or rarely single crystals, and those obtained by crushing such crystals are used, and voids exist in the state filled in the charge tube. Therefore, in order to add the raw material corresponded to the part which grew the single crystal, it is not enough to single input by a charge tube. Therefore, a plurality of injections are performed continuously.

Patent Publication No. 62-260791 Japanese Patent Application Laid-Open No. 2-157180 WO2002 / 068732 Patent Publication No. 2006-89294 Patent Publication No. 2008-13376 Patent Publication No. 2008-88000

In the case where the raw material is continuously fed as described above multiple times, since the angle of the conical valve is constant by using a charge tube of the same type in the conventional method, the raw material is concentrated at the same position in the radial direction. Therefore, the additionally added raw material accumulates high in a donut shape in a quartz crucible, and the height nonuniformity of an unmelted raw material becomes large. Therefore, even if the raw material added before is melted to some extent and then the next addition or all the raw materials are added well, the melting of the raw material takes time and the additional raw material takes time to melt. there was.

This invention is made | formed in view of the said problem, and an object of this invention is to provide the method which can suppress the height nonuniformity of the input raw material into a quartz crucible when manufacturing a single crystal.

In order to achieve the above object, the present invention provides a single crystal having a step of filling a raw material in a quartz crucible, a step of melting the raw material in the quartz crucible into a molten liquid, and a step of raising a single crystal from the molten liquid. In the step of filling a raw material into the quartz crucible, the raw material is accommodated in a recharge tube having a cylindrical member made of quartz containing the raw material and a conical valve for opening and closing the lower end opening of the cylindrical member. The method for filling a raw material in which a rechargeable tube containing a fuel cell is set in a chamber, and a raw material filling in which the raw material accommodated in the rechargeable tube is introduced into the quartz crucible by opening the opening of the cylindrical member at the conical valve is performed two or more times in succession. At least one time of the raw material filling performed two or more times in succession In charging, there is provided a method of filling a raw material characterized in that the cone angle of the conical valve charging the raw material using different Recharge the tube.

In this way, by using a conical valve having a different cone angle, the raw material can be put in a position different from that of the raw material in the case of other raw material filling, and even if the raw material filling is performed continuously, the height of the raw material into the quartz crucible Unevenness can be suppressed. Therefore, raw material filling and melting can be performed efficiently, and the productivity of manufacture of a single crystal can be improved.

At this time, the cone angle of the cone valve is preferably in the range of 30 to 150 degrees.

In the case of such a conical angle, the raw material can be smoothly introduced without reducing the capacity of the charge tube, and the raw material filling can be performed more efficiently.

At this time, in the at least one time of raw material filling, it is preferable to fill the raw material by using the recharge tube in which the cone angle of the cone valve is different by 15 degrees or more.

By setting it as such a cone angle different from 15 degree | times or more, the injection position of the raw material in a quartz crucible can be changed effectively, and the height nonuniformity of a raw material can be suppressed reliably.

At this time, the diameter of the quartz crucible is preferably 610 mm or more.

In such a large-diameter quartz crucible, the necessity of suppressing the height nonuniformity of the raw material according to the present invention is high, and works more effectively in improving the productivity of the production of the single crystal.

Moreover, this invention repeats the process of filling a raw material in a quartz crucible, the process of melting the said raw material in a said quartz crucible into a molten liquid, and the process of pulling up a single crystal from the said molten liquid, and using the same quartz crucible A method of manufacturing a plurality of single crystals, the method of filling the raw material in the first pulling up of the single crystal and / or the step of filling the raw material in the pulling of each of the single crystal after the second, the raw material of the present invention Provided is a method for producing a single crystal, characterized in that the raw material is filled by a filling method.

By using the raw material filling method of the present invention for further charging or recharging in the production of such single crystals by multi-pooling, the raw material filling and melting can be efficiently performed and the productivity of the single crystal can be improved. .

As mentioned above, according to this invention, raw material filling and melting with a quartz crucible can be performed efficiently, and the productivity of manufacture of a single crystal can be improved.

1 is a schematic view showing an example of a single crystal production apparatus that can be used in the present invention.
2 is a schematic diagram showing an example of a rechargeable tube that can be used in the present invention.
3 is a schematic view of filling raw materials into a quartz crucible by a charge tube.
4 is a schematic diagram showing an example of a conical valve that can be used in the present invention.
Fig. 5 is a graph and a schematic diagram showing the distribution of input raw materials according to the cone angle of the cone valve required in the experiment.

EMBODIMENT OF THE INVENTION Hereinafter, although this invention is demonstrated in detail, referring drawings as an example of embodiment, this invention is not limited to this.

1 is a single crystal manufacturing apparatus of the CZ method that can be used in the raw material filling method of the present invention.

The single crystal manufacturing apparatus 20 of FIG. 1 includes a main chamber 1, a quartz crucible 6 and a graphite crucible 7 containing a molten liquid 5 in the main chamber 1, a quartz crucible 6, and The single crystal which is connected to the heater 8 arranged around the graphite crucible 7, the heat insulating member 9 around the outside of the heater 8, and the gate chamber 3 is connected to the upper part of the main chamber 1. It is comprised by the pulling chamber 2 which accommodates the (monocrystal ingot) 4, and the gas rectification cylinder 12 which surrounds the single crystal 4 in pulling. In the pulling chamber 2, a gas inlet 11 for introducing gas circulating in the furnace is provided, and a gas outlet 10 for discharging gas circulating in the furnace is provided at the bottom of the main chamber 1. It is. In addition, a heat shield member 13 for blocking heat radiation from the heater 8 and the melt 5 may also be provided. The quartz crucible 6 and the graphite crucible 7 can be lifted in the direction of the crystal growth axis, and the quartz crucible 6 and the graphite crucible 7 are replenished to supplement the liquid level drop of the melt 5 which crystallized and decreased during crystal growth. Raise. Thereby, the height of the liquid level of the molten liquid 5 is kept substantially constant.

In addition, according to the manufacturing conditions, a magnetic field generating device (not shown) is provided outside the main chamber 1, and the melt 5 is convection by applying a magnetic field in the horizontal or vertical direction. It is also possible to use a device of the so-called MCZ method, which suppresses the loss and promotes stable growth of the single crystal 4.

In the case of single crystal production by the above-mentioned single crystal production apparatus 20, as shown in Fig. 2, a cylindrical cylindrical member 15 containing a raw material (polycrystalline or single crystal) 14 and the cylindrical member ( The raw material 14 is accommodated in the recharge tube 17 which has the conical valve 16 for opening and closing the opening part of the lower end of 15, and the recharge tube 17 which accommodated the said raw material 14 is pulled up in the chamber 2 In the quartz crucible 6, the raw material 14 held in the recharge tube 17 by hanging with the wire 18 in the inside and opening the opening of the cylindrical member 15 in the conical valve 16 as shown in FIG. Fill the raw material into the tank. In the present invention, this raw material filling is performed two or more times in succession before single crystal pulling up.

In the present invention, the raw material 14 is filled by using a charge tube 17 having a different cone angle of the conical valve 16 in at least one time of raw material filling performed two or more times. . Here, in the present invention, the conical angle of the conical valve 16 refers to the vertex angle (vertical angle of the longitudinal section) θ of the conical valve 16, as shown in FIG.

Since the inclination of the inclined surface of the conical valve is different depending on the cone angle, when the inclination of the inclined surface is different, the raw material can be introduced at a position different from the input position of the raw material in the case of other raw material filling. If the cone angle of the cone valve is large, the raw material is discharged to the outside, and if the cone angle is small, the raw material is dropped near the center. By combining these, the height of the input raw material can be prevented from increasing only in a specific part, and the height of the input raw material can be smoothed. Therefore, it is not necessary to make time empty every filling of raw materials, and melting also advances efficiently. Thereby, productivity of single crystal manufacture can be improved effectively.

The cone angle θ of the cone valve 16 as shown in FIG. 4 is not particularly limited, but is preferably set in the range of 30 to 150 degrees.

If it is 30 degrees or more, the height of the conical valve can be suppressed, so the capacity of the recharge tube is not reduced, and if it is 150 degrees or less, the falling speed of the raw material does not decrease too much and the raw material can be dropped farther from the crucible center. have. Further, the cone angle θ is more preferably in the range of 40 to 120 degrees. If it is 40 degrees or more, the fall speed of a raw material will not become too fast, and if it is 120 degrees or less, a conical valve will not be shaken and stable at the time of raw material input. In addition, it also depends on the relationship between the size of the quartz crucible and the size of the recharge tube, but in the case of such a conical angle θ, it is certain that the feeding position is not too far from the center of the crucible, and the raw material strongly hits the inner wall of the quartz crucible. Can be prevented.

As described above, when the filling of the raw material is performed by changing the cone angle θ of the cone valve 16, as shown in FIG. 4, the recharge tube 17 having a cone angle θ of at least 15 degrees different from the cone valve 16. It is preferable to use.

As described above, in the case of a conical valve having a conical angle θ of 15 degrees or more, the raw material can be introduced at a position different from the input position of the raw material in other raw material filling, and the height of the input raw material into the quartz crucible is more uniform. It can be done.

For example, as shown in FIG. 4, conical valves 16a, 16b, and 16c having three levels of cone angle θ can be prepared, and the raw material filling can be performed by changing the cone valve used for each raw material filling. Alternatively, a conical valve having a different conical angle θ may be used for at least one time raw material filling. Therefore, when the raw material is filled three times continuously, for example, the first is the conical valve 16a and the second is the conical valve. 16c and 3rd can be used in the order of the conical valve 16a, and raw material can be filled.

Such a raw material filling method of the present invention is preferably used when the raw material 14 is filled in a quartz crucible 6 with a diameter of 610 mm or more.

Such a large-diameter quartz crucible has a large capacity, an increase in the number of fillings of the raw material to be continuously executed, and a large aperture, which makes the height position of the injected raw material likely to be nonuniform. Since the thickness of the charge tube is limited by the gas rectifier or the like, it is basically the same as the thickness of the grown crystal. On the other hand, a quartz crucible is also used with a diameter approximately three times the diameter of the grown crystal diameter. Therefore, the distance from the charge tube to the crucible wall is the distance to which the rechargeable raw material is to be blown, which is approximately equal to the crystal diameter. That is, the size ratio may be constant, and the distance to fly the actual rechargeable raw material increases as the crucible diameter increases. For this reason, this invention is suitable.

The raw material filling method of the present invention comprises the steps of filling the quartz crucible 6 with the raw material 14 using the single crystal manufacturing apparatus 20 described above, and melting the raw material 14 in the quartz crucible 6 to melt the liquid ( 5) and the step of pulling up the single crystal 4 from the molten liquid 5 repeatedly, and producing a single crystal by multi-pulling to produce a plurality of single crystals 4 using the same quartz crucible 6. Can be used for

In this case, in the step of filling the raw material 14 in the pulling of the first single crystal 4, and / or in the step of filling the raw material 14 in the pulling of each single crystal 4 after the second, The raw material 14 is filled by the raw material filling method of the invention.

The raw material can be filled by the method of the present invention in the additional charge of the raw material in the pulling of the first single crystal, or the raw material can be filled by the present invention in the recharging of the single crystal after the second.

According to the present invention as described above, in the production of single crystals in the Czochralski method (including the MCZ method), the raw material filling time or raw material melting time can be shortened, and the productivity can be effectively improved.

Example

Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to this.

(Experiment)

As shown in FIG. 4, three levels of cone valves were prepared by dividing the cone angle θ by 100 degrees, 70 degrees, and 50 degrees. This was set at the bottom of the charge tube and the raw material was placed in the charge tube as shown in FIG. 2.

Then, at room temperature, a plate was placed in the quartz crucible and selected in place of the silicon melt, and the raw material in the charge tube was put on the plate as shown in FIG. 3. This experiment was performed using three levels of cone valves with different cone angles as shown in FIG. 4.

As a result, as shown in Fig. 5 (a), the dropped raw material formed a donut-shaped acid. The height is measured in FIG. 5 (b). The number in the graph of FIG. 5 (b) is expressed as a ratio with a distance from the center of the quartz crucible to the inner wall as 1. As can be seen from FIG. 5 (b), as the cone angle θ increases, the peak of the mountain moves to the outside of the crucible, and the height of the mountain tends to decrease.

As mentioned above, it turns out that the position where a raw material falls can be controlled by dividing the cone angle of a cone valve. Conventionally, a plurality of raw material fillings have been carried out with only one type of angle. However, the height of the donut-shaped acid became high at the same position, and there was complexity in operation such as waiting for the melted raw material to be melted to some extent and executing the next pouring, which took time to melt. However, since the drop position of the raw material is changed by changing the cone angle, it has been found that, for example, by using a cone valve whose cone angle is changed every time it is added, the height of the mountain can be smoothed and can be suppressed low. Although this charging experiment was conducted at room temperature, the charging of raw materials such as a recharge is practically performed under high temperature, and the first charged raw material starts to melt when additionally charged with subsequent raw materials. For this reason, the following Examples 1-3 and the comparative example were implemented under the high temperature conditions of an actual apparatus.

(Example 1)

Using a single crystal manufacturing apparatus shown in FIG. 1, a silicon crucible having a diameter of 26 inches (660 mm) in a main chamber and a quartz crucible having a diameter of 8 inches (200 mm) using a magnetic field applied Czochralski method (MCZ method) Was nurtured.

After the silicon single crystal was grown in this apparatus, 120 kg of raw material was further charged into the quartz crucible, and it was melted. At this time, the raw material was continuously added three times as 40 kg of each input amount. In the third injection, the cone angle θ of each cone valve was set to 50 degrees for the first dose, 70 degrees for the second dose, and 100 degrees for the third dose.

Since the inside of the main chamber was depressurized, the charge tube was mounted in the pulling chamber under normal pressure, and the vacuum pump was then depressurized in the pulling chamber to the same pressure as the main chamber, and the gate valve was opened. Thereafter, the charge tube was lowered to the vicinity of the surface of the melt, and the raw material was discharged by opening the opening at the conical valve. The empty recharge tube was then pulled back into the impression chamber, the gate valve closed and returned to normal pressure. This operation was repeated and 3 times raw material input was performed.

As a result, a situation in which the acid was too high to be added when the raw material was added did not occur, and the operation could be performed without clogging. As a result, the time taken for melting could be reduced by 15% compared to the comparative example presented later.

(Example 2)

A total of 120 kg of raw material input and melting were performed in the same manner as in Example 1, except that the cone angle of the conical valve was set to 100 degrees for the first dose, 50 degrees for the second dose, and 100 degrees for the third dose.

As a result, in the case of inserting the raw materials in the same manner as in Example 1, a situation in which the acid was too high and cannot be added did not occur, and it was possible to work without clogging. As a result, the time taken for melting could be reduced by about 14% compared to the comparative example presented later.

(Example 3)

A total of 120 kg of raw material input and melting were performed in the same manner as in Example 1 except that the cone angle of the conical valve was set to 100 degrees for the first dose, 70 degrees for the second dose, and 50 degrees for the third dose.

As a result, the first and second doses could be added without clogging, but when the third dose was added, since the height of the acid was too high, the third dose was added after waiting for the raw material to melt. As a result, the time taken for melting could be reduced by about 8% compared to the comparative example presented later.

(Comparative Example)

A total of 120 kg of raw material input and melting were performed in the same manner as in Example 1 except that the conical valve having a conical angle of 70 degrees was used for all three administrations.

As a result, the first and second doses could be added without clogging, but when the third dose was added, the donut-shaped acid was too high, and the timing of the addition was waited without opening the gate valve. Since the raw material began to melt and the acid became low, the gate valve was opened, the charge tube was dropped, and the third dose of raw material was added. As a result, melting time became longer than Example 1 thru | or 3 mentioned above.

In Examples 1 to 3, the cone angle was gradually increased, or conversely, gradually decreased, or large and small were alternately used, and three times in a row were added. However, the present invention is not limited to this embodiment, and can be applied to four or more times or two times of continuous input, and also applicable to the case where each input amount is different, and the present invention while watching the situation in which the raw materials are introduced The appropriate change angle can be selected accordingly.

In addition, this invention is not limited to the said Example. The above embodiments are exemplary and have substantially the same constitution as the technical idea described in the claims of the present invention, and any one which exhibits the same operational effects is included in the technical scope of the present invention.

1-main chamber 2-impression chamber
3-gate valve 4-single crystal
5-melt 6-quartz crucible
7-graphite crucible 8-heater
9-insulation member 10-gas outlet
11-gas inlet 12-gas rectifier
13-heat shield 14-raw material
15-cylindrical member 16-conical valve
17-Recharge Tube 18-Wire
20-single crystal manufacturing equipment

Claims (7)

In the production of a single crystal having a step of filling a quartz crucible with a raw material, a step of melting the raw material in the quartz crucible to form a molten liquid, and a step of raising a single crystal from the molten liquid,
In the step of filling a raw material into the quartz crucible, the raw material is accommodated in a charge tube having a cylindrical member made of quartz containing the raw material and a conical valve for opening and closing the lower end of the cylindrical member. It is a raw material filling method which sets a rechargeable tube in a chamber, performs the raw material filling which injects the raw material accommodated in the said rechargeable tube into the said quartz crucible by opening the opening part of the said cylindrical member in the said conical valve,
And at least one of the filling of the raw material to be executed two or more times continuously, wherein the raw material is filled using the charge tube having a different cone angle of the conical valve.
The method of claim 1,
Raw material filling method characterized in that the cone angle of the cone valve in the range of 30 to 150 degrees.
The method of claim 1,
In the at least one raw material filling, the raw material filling method is characterized in that the raw material is filled by using the recharge tube having a cone angle of 15 degrees or more.
3. The method of claim 2,
In the at least one raw material filling, the raw material filling method is characterized in that the raw material is filled by using the recharge tube having a cone angle of 15 degrees or more.
5. The method according to any one of claims 1 to 4,
Raw material filling method characterized in that the diameter of the quartz crucible is 610mm or more.
A step of filling a raw material into a quartz crucible, a step of melting the raw material into a molten liquid in the quartz crucible, and a step of raising a single crystal from the molten liquid are repeatedly performed to produce a plurality of single crystals using the same quartz crucible. As a way to,
The process for filling the raw material in the first single crystal pulling and / or the step of filling the raw material in the pulling of each single crystal after the second time, wherein the raw material filling method according to any one of claims 1 to 4. A method for producing a single crystal, characterized in that the raw material is filled by.
A step of filling a raw material into a quartz crucible, a step of melting the raw material into a molten liquid in the quartz crucible, and a step of raising a single crystal from the molten liquid are repeatedly performed to produce a plurality of single crystals using the same quartz crucible. As a way to,
In the step of filling the raw material in the pulling of the first single crystal and / or the step of filling the raw material in the pulling of each of the single crystals after the second, filling the raw material by the raw material filling method of claim 5. A method for producing a single crystal, characterized in that.

Images