JP5741528B2 - Raw material filling method and single crystal manufacturing method - Google Patents

Description

  The present invention relates to a method of filling a raw material into a quartz crucible using a recharge 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 and a MCZ (magnetic field applied Czochralski) method for applying a magnetic field are generally used. In these CZ / MCZ methods, a silicon raw material is filled in a quartz crucible and melted, a seed crystal is deposited in the melt, and then pulled up to grow a silicon single crystal. In a CZ / MCZ single crystal manufacturing apparatus (pulling machine), a heater for heating a melt is installed in a main chamber, and a quartz crucible for storing the melt is installed inside the heater.

  Usually, the raw material is first packed in this quartz crucible, and the raw material is melted by heating with a heater. With the recent increase in the diameter and length of silicon single crystals, there are cases where more raw materials are added than the raw materials initially packed in the quartz crucible. This is called follow-up charge, and similarly to the recharge described later, the raw material is filled in a recharge tube having a conical cone (conical valve) at the lower end, and the raw material is charged into the quartz crucible through the recharge tube. Then, after all these raw materials are melted, the growth of the silicon single crystal is started.

  The quartz crucible is filled with a melt in which raw materials are dissolved, from which a silicon single crystal is grown. The grown single crystal is accommodated in a pulling chamber connected to the upper part of the main chamber via a gate valve and cooled. Thereafter, the single crystal is taken out from the pulling chamber.

  In such production, if only one single crystal is grown from one quartz crucible, the growth is terminated at this point, but the quartz crucible is cracked and cannot be reused, resulting in an increase in production cost. End up. Therefore, there are cases where a multi-operation for growing a plurality of single crystals from one quartz crucible is performed. In that case, after growing the single crystal, the melt in the quartz crucible is reduced by the amount of the grown crystal, so that the next single crystal cannot be grown as it is. Therefore, recharging is performed in which the raw material is charged again to compensate for this decrease.

  As a recharging method, a rod recharging method and a method of supplying from a raw material tank as disclosed in Patent Document 1 have been proposed for a long time. However, the technique taken up in many patent documents is a method in which a raw material is stored in a recharge tube having a conical valve at the lower end, and the raw material stored in the recharge tube is put into a quartz crucible. Patent Documents 2 and 3 disclose the basics of this technology. For example, Patent Document 3 describes that the conical angle (vertex angle) of the conical valve is 40-100 degrees, more preferably 60-90 degrees.

  By using such a method, after the silicon single crystal is taken out from the pulling chamber partitioned by the gate valve, the recharge tube containing the raw material is hung with a wire and attached, and the pressure inside the pulling chamber is increased by vacuuming. After adjusting to the furnace pressure in the main chamber, the gate valve is opened and the raw material is charged.

For example, in Patent Document 4, the wire is covered with a protective tube, and in Patent Document 5, the wire is enclosed in a recharge tube or a conical valve to prevent breakage. A technique in which some improvements are made to the disclosed techniques of Patent Documents 2 and 3 is disclosed, such as an improvement of inserting a groove in a conical valve. However, the basic technique is the contents shown in Patent Documents 2 and 3.
As can be seen from so many documents, the recharge method using a recharge tube is one of the widely used technologies. However, since Patent Document 3, no consideration has been given to the angle of the conical valve.

  The raw material to be filled as described above may usually be polycrystalline or rarely single crystal, and those crushed crystals are used, and there are voids when packed in a recharge tube. Therefore, in order to add a raw material corresponding to the amount of the single crystal grown, it is not sufficient to make a single charge with a recharge tube. For this reason, a plurality of inputs are continuously performed.

JP-A-62-260791 JP-A-2-157180 WO2002 / 068732 JP 2006-89294 A JP 2008-13376 A JP 2008-88000 A

  As described above, when the raw material is continuously charged a plurality of times, the conventional method uses a recharge pipe of the same shape, so the angle of the conical valve is constant, so that it is concentrated at the same position as seen in the radial direction. Raw materials are dropped. For this reason, the added raw material is piled up in a donut shape in the quartz crucible, and the unevenness of the unmelted raw material height increases. Therefore, after waiting for the raw material previously charged to melt to some extent, the next charging is performed, or even if all the raw materials are successfully input, it takes time to melt the raw material. There was a problem that it took.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method capable of suppressing the unevenness of the height of the input material in the quartz crucible during the production of a single crystal. And

To achieve the above object, the present invention includes a step of filling a raw material in a quartz crucible, a step of melting the raw material in the quartz crucible to form a melt, and a step of pulling a single crystal from the melt in the manufacture of a single crystal having bets, in the step of filling the raw material into the quartz crucible, and quartz cylindrical member for accommodating the raw material, and a conical valve for opening and closing the opening of the lower end of the cylindrical member material containing the raw material to recharge tube, sets the recharge tube containing the raw material into the chamber and housed in the recharge pipe into the quartz crucible by opening the opening portion of the cylindrical member with said conical valve having a the charged raw material filling method of performing two or more times in succession, the introduction of at least one of the material of the introduction of the raw material to carry out the consecutive two or more times, said conical Bal Providing raw material filling method, wherein the cone angle of filling the raw material with different the recharge pipe.

  In this way, by using a conical valve with a different cone angle, the raw material can be charged at a position different from the raw material charging position when filling other raw materials. It is possible to suppress unevenness in the height of the raw material charged in the crucible. Therefore, raw material filling and melting can be performed efficiently, and productivity of single crystal production can be improved.

At this time, it is preferable that the conical angle of the conical valve be in the range of 30 to 150 degrees.
With such a cone angle, the raw material can be introduced smoothly without reducing the capacity of the recharge tube, and the raw material can be charged more efficiently.

At this time, it is preferable to fill the raw material using the recharge pipe in which the conical valve has a cone angle different by 15 degrees or more in the at least one raw material filling.
By setting the cone angle to be different by 15 degrees or more, the raw material charging position in the quartz crucible can be effectively changed, and the unevenness of the height of the raw material can be surely suppressed.

At this time, the diameter of the quartz crucible is preferably 610 mm or more.
Such a large-diameter quartz crucible is highly necessary to suppress unevenness in the height of the raw material according to the present invention, and works effectively by improving the productivity of single crystal production.

  The present invention also includes a step of filling a raw material in a quartz crucible, a step of melting the raw material in the quartz crucible to form a melt, and a step of pulling a single crystal from the melt, thereby repeating the same quartz. A method of producing a plurality of single crystals using a crucible, the step of filling the raw material in pulling up the first single crystal and / or the raw material in pulling up the single crystal after the second one In the step of filling a single crystal, the raw material is filled by the raw material filling method of the present invention.

  By using the raw material filling method of the present invention for recharging and recharging in the production of a single crystal by such multi-pooling, raw material filling and melting can be carried out efficiently, and the productivity of the single crystal can be improved.

  As described above, according to the present invention, the raw material filling and melting into the quartz crucible can be carried out efficiently, and the productivity of single crystal production can be improved.

It is the schematic which shows an example of the single crystal manufacturing apparatus which can be used for this invention. It is the schematic which shows an example of the recharge pipe | tube which can be used for this invention. It is the schematic at the time of filling a raw material in a quartz crucible with a recharge pipe | tube. It is the schematic which shows the example of the conical valve which can be used in this invention. It is the graph and schematic which show distribution of the input raw material by the cone angle of the cone valve calculated | required in experiment.

Hereinafter, the present invention will be described in detail as an example of an embodiment with reference to the drawings, but the present invention is not limited thereto.
FIG. 1 shows a CZ method single crystal manufacturing apparatus that can be used in the raw material filling method of the present invention.

  1 includes a main chamber 1, a quartz crucible 6 and a graphite crucible 7 that store a melt 5 in the main chamber 1, and a heater 8 disposed around the quartz crucible 6 and the graphite crucible 7. A heat insulating member 9 around the outside of the heater 8, a pulling chamber 2 connected to the upper portion of the main chamber 1 via a gate valve 3 and containing a grown single crystal (single crystal ingot) 4; A gas rectifying cylinder 12 surrounding the crystal 4 is provided. The pulling chamber 2 is provided with a gas inlet 11 for introducing a gas to be circulated in the furnace, and a gas outlet 10 for discharging the gas circulated in the furnace is provided at the bottom of the main chamber 1. Further, a heat shield member 13 for blocking heat radiation from the heater 8 or the melt 5 can also be provided. The quartz crucible 6 and the graphite crucible 7 can be moved up and down in the direction of the crystal growth axis, and the quartz crucible 6 and the graphite crucible 7 are raised so as to compensate for the liquid level drop of the melt 5 that has been crystallized and decreased during crystal growth. Thereby, the height of the liquid surface of the melt 5 is kept substantially constant.

  Furthermore, a convection of the melt 5 is suppressed by installing a magnetic field generator (not shown) outside the main chamber 1 according to manufacturing conditions and applying a horizontal or vertical magnetic field to the melt 5. In addition, a so-called MCZ method apparatus for achieving stable growth of the single crystal 4 can also be used.

  When the single crystal is manufactured by the single crystal manufacturing apparatus 20 described above, as shown in FIG. 2, a quartz cylindrical member 15 containing a raw material (polycrystalline or single crystal) 14, and a lower end of the cylindrical member 15 The raw material 14 is accommodated in a recharge pipe 17 having a conical valve 16 for opening and closing the opening, and the recharge pipe 17 containing the raw material 14 is pulled up and suspended in a chamber 2 by a wire 18 and set in FIG. As shown in the drawing, the opening of the cylindrical member 15 is opened by the conical valve 16 so as to charge the raw material 14 accommodated in the recharge pipe 17 into the quartz crucible 6. In the present invention, this raw material filling is performed twice or more continuously before pulling the single crystal.

In the present invention, the raw material 14 is filled using the recharge pipe 17 having a different cone angle of the conical valve 16 in at least one of the raw material fillings performed continuously twice or more in this way. Here, in the present invention, the conical angle of the conical valve 16 refers to the angle (vertical angle of the longitudinal section) θ of the apex of the conical valve 16, as shown in FIG.
Since the inclination of the inclined surface of the conical valve varies depending on the cone angle, if the inclination of the inclined surface is different, the raw material can be charged at a position different from the raw material charging position at the time of filling other raw materials. When the cone angle of the conical valve is large, the raw material is dropped to the outside, and when the cone angle is small, the raw material is dropped near the center. By combining this, it is possible to prevent the height of the input raw material from increasing only at a specific location and to smooth the height of the input raw material. Therefore, it is not necessary to make time for each raw material filling, and the melting proceeds efficiently. Thereby, productivity of single crystal manufacture can be improved effectively.

Although it does not specifically limit as cone angle (theta) of the cone valve 16 as shown in FIG. 4, It is preferable to set in the range of 30-150 degree | times.
If it is 30 degrees or more, the height of the conical valve can be suppressed, so the capacity of the recharge pipe is not reduced, and it is efficient. If it is 150 degrees or less, the dropping speed of the raw material does not decrease too much. The raw material can be dropped farther from the center of the crucible. Furthermore, the cone angle θ is more preferably in the range of 40 to 120 degrees. If it is 40 degree | times or more, the falling speed of a raw material will not become too fast, and if it is 120 degree | times or less, the conical valve at the time of raw material injection | throwing will not be shaken but will be stabilized. Also, depending on the relationship between the size of the quartz crucible and the size of the recharge tube, if the cone angle θ is such, the charging position is not too far from the center of the crucible, and the raw material is the inner wall of the quartz crucible. It can be surely prevented that it hits strongly.

In this way, when charging the raw material by changing the cone angle θ of the conical valve 16, it is preferable to use a recharge pipe 17 in which the cone angle θ of the conical valve 16 differs by 15 degrees or more as shown in FIG.
In this way, if the conical valve has a cone angle θ different by 15 degrees or more, the raw material can be reliably charged at a position different from the raw material charging position in the other raw material filling, and the amount of the raw material charged in the quartz crucible can be increased. The thickness can be made more uniform.

  For example, as shown in FIG. 4, conical valves 16a, 16b, and 16c having a three-degree cone angle θ are prepared, and the material can be charged by changing the cone valve to be used every time the material is charged. Alternatively, a conical valve having a different cone angle θ may be used in at least one raw material filling. Therefore, for example, when raw material filling is performed three times in succession, the first time is the conical valve 16a, the second is the conical valve 16c, 3 The second time can be filled with the raw material by using the conical valve 16a in this order.

Such a raw material filling method of the present invention is preferably used when the raw material 14 is filled into the quartz crucible 6 having a diameter of 610 mm or more.
Such a large-diameter quartz crucible has a large capacity and the number of continuous filling of raw materials increases, and since the diameter is large, the height position of the charged raw materials tends to be uneven. Since the thickness of the recharge tube is limited by the heat shielding member or the like, it is basically the same as the crystal thickness grown. On the other hand, the diameter of the quartz crucible is approximately three times that of the crystal to be grown. Therefore, the distance from the recharge tube to the crucible wall is the distance at which the recharge material is desired to be blown, and is approximately the crystal diameter. That is, even if the size ratio is constant, the actual distance increases as the crucible diameter increases. For this reason, this invention is suitable.

The raw material filling method of the present invention includes a step of filling the raw material 14 into the quartz crucible 6 using the single crystal manufacturing apparatus 20 described above, and a step of melting the raw material 14 into the melt 5 in the quartz crucible 6. The process of pulling up the single crystal 4 from the melt 5 can be repeated to produce a single crystal by multi-pooling that produces a plurality of single crystals 4 using the same quartz crucible 6.
In this case, in the step of filling the raw material 14 in the pulling up of the first single crystal 4 and / or the step of filling up the raw material 14 in the pulling up of each single crystal 4 after the second, the raw material filling method of the present invention. The raw material 14 is filled.

  In the follow-up charge of the raw material in the first pulling of the single crystal, it is possible to fill by the method of the present invention, or in the recharge in the pulling of the second and subsequent single crystals, the raw material can be charged by the present invention.

  With the present invention as described above, when manufacturing a single crystal in the Czochralski method (including the MCZ method), the raw material filling time and the raw material melting time can be shortened, and the productivity is effectively improved. be able to.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited to these.
(Experiment)
As shown in FIG. 4, a three-level conical valve with a conical angle θ of 100 degrees, 70 degrees, and 50 degrees was prepared. This was set at the lower end of the recharge tube, and the recharge tube was filled with the raw material as shown in FIG.

Next, at room temperature, a quartz crucible was laid on a plate and regarded as a substitute for silicon melt, and the raw material in the recharge tube was put on the plate as shown in FIG. This experiment was performed using three levels of conical valves with different cone angles as shown in FIG.
As a result, as shown in FIG. 5 (a), the dropped raw material formed a donut-like mountain. FIG. 5B shows the measured height. The numbers in the graph of FIG. 5B are expressed as a ratio, with the distance from the center of the quartz crucible to the inner wall being 1. As can be seen from FIG. 5B, 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.

  From the above, it was found that the position where the raw material falls can be controlled by swinging the cone angle of the cone valve. Conventionally, raw material filling has been performed several times at only one kind of angle. However, the height of the donut-shaped mountain increases at the same position, and there is a troublesome work such as waiting for the charged raw material to melt to some extent and then performing the next charging, and it takes time to melt. It was. However, it has been found that the height of the mountain can be suppressed gently and low by using, for example, a conical valve in which the cone angle is changed every time the material is dropped, since the position of the raw material changes by changing the cone angle. Although this charging experiment was performed at room temperature, material charging such as recharging is actually performed at a high temperature, and the previously charged material starts to melt when the material is further charged later. For this reason, the following Example 1-3 and the comparative example were performed under the high temperature conditions of the actual apparatus.

Example 1
Using the single crystal manufacturing apparatus shown in FIG. 1, a quartz crucible having a diameter of 26 inches (660 mm) is installed in the main chamber, and a magnetic field application Czochralski method (MCZ method) is used and the diameter is 8 inches (200 mm). The silicon single crystal was grown.

After growing a silicon single crystal in this apparatus, 120 kg of raw material was additionally filled in a quartz crucible and melted. At this time, the raw materials were continuously fed in three times with the same amount of each being 40 kg. When thrown three times, the cone angle θ of each conical valve was set to 50 degrees for the first throw, 70 degrees for the second throw, and 100 degrees for the third throw.
Since the inside of the main chamber was in a reduced pressure state, the recharge pipe was pulled up and installed in the chamber under normal pressure, and then the inside of the pulling chamber was reduced to the same pressure as the main chamber with a vacuum pump, and the gate valve was opened. Thereafter, the recharge pipe was lowered to near the melt surface, and the raw material was dropped by opening an opening with a conical valve. Thereafter, the evacuated recharge pipe was again pulled up into the chamber, the gate valve was closed, and the pressure was returned to normal pressure. This operation was repeated, and the raw material was charged three times.

  As a result, when the raw material was added, the mountain was too high to be input, and the operation could be carried out without stagnation. As a result, the time required for melting could be shortened by 15% compared to the comparative example shown later.

(Example 2)
A total of 120 kg of raw materials were charged and melted in the same manner as in Example 1 except that the conical angle of the conical valve was set to 100 degrees for the first throw, 50 degrees for the second throw, and 100 degrees for the third throw.
As a result, as in Example 1, the state that the crest was too high when the raw material was charged and the material could not be charged did not occur, and the operation could proceed without stagnation. As a result, the time required for melting could be shortened by about 14% compared with the comparative example shown later.

(Example 3)
A total of 120 kg of raw material was charged and melted in the same manner as in Example 1 except that the cone angle of the conical valve was set to 100 ° for the first throw, 70 ° for the second throw, and 50 ° for the third throw.
As a result, the first and second shots could be thrown in smoothly, but when the third shot was thrown, the height of the mountain was a little too high. I put my eyes. As a result, the time required for melting could be shortened by about 8% compared with the comparative example shown later.

(Comparative example)
A total of 120 kg of raw material was charged and melted in the same manner as in Example 1 except that a conical valve with a cone angle of 70 degrees was used for all three throws.
As a result, the first and second shots could be thrown in smoothly, but when the third shot was thrown, the donut-shaped mountain height was too high, so the timing was not opened without opening the gate valve. Waited. When the raw material began to melt and the mountain became lower, the gate valve was opened to lower the recharge pipe, and the third raw material was charged. As a result, the melting time was longer than in Example 1-3 described above.

  In the above Example 1-3, the cone angle is gradually increased, conversely is gradually decreased, the size is alternately used, or the sizes are alternately input three times, and the input amount at each time is the same. It was. However, the present invention is not limited to such an embodiment, and can be applied to four or more times or two times of continuous feeding, and can be applied even when the amount of charging of each time is different. While looking, it is possible to select an appropriate change angle according to the present invention.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

1 ... Main chamber, 2 ... Lifting chamber, 3 ... Gate valve,
4 ... single crystal, 5 ... melt, 6 ... quartz crucible, 7 ... graphite crucible,
8 ... heater, 9 ... heat insulating member, 10 ... gas outlet, 11 ... gas inlet,
12 ... Gas flow straightening tube, 13 ... Heat shield member, 14 ... Raw material, 15 ... Cylindrical member,
16 ... Conical valve, 17 ... Recharge pipe, 18 ... Wire,
20: Single crystal manufacturing apparatus.

Claims (5)

The quartz crucible in the production of a single crystal, comprising: filling a raw material into a quartz crucible; melting the raw material in the quartz crucible to form a melt; and pulling the single crystal from the melt. in the step of filling the raw material within, accommodating the material to recharge tube having a quartz cylindrical member for accommodating the raw material, and a conical valve for opening and closing the opening of the lower end of the cylindrical member, the material set the recharge pipe into the chamber containing the raw material filling performing the conical valve in the cylindrical opening of in the quartz crucible by opening the member the recharge pipe received therein and the introduction of the raw material two or more times in succession A method,
In introduction of at least one of the material of the introduction of the raw material to carry out the consecutive two or more times, the raw material filling, characterized by filling the raw material using the recharge pipe cone angle different from the conical valve Method.   2. The raw material filling method according to claim 1, wherein a conical angle of the conical valve is in a range of 30 to 150 degrees.   3. The raw material filling method according to claim 1, wherein in the at least one raw material filling, the raw material is filled using the recharge pipe having a cone angle of the conical valve different by 15 degrees or more.   The raw material filling method according to any one of claims 1 to 3, wherein a diameter of the quartz crucible is set to 610 mm or more. A step of filling a raw material in a quartz crucible, a step of melting the raw material in the quartz crucible to form a melt, and a step of pulling a single crystal from the melt are repeated, and a plurality of steps are performed using the same quartz crucible. A method for producing a single crystal of
5. The step of filling the raw material in the first pulling of the single crystal and / or the step of filling the raw material in the pulling of the single crystal after the second one, respectively. A method for producing a single crystal, wherein the raw material is filled by the raw material filling method according to claim 1.

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