JPH09255471A - Production of single crystal and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a single crystal capable of supplying a raw material in a crucible within a short time without generating the splash of a molten liquid preceding to the pulling up the single crystal. SOLUTION: This method for producing a single crystal is to fill a lump shaped polycrystalline silicon in a crucible 2 as a raw material for a crystal, melt the raw material for the crystal by a heater 4, adjust the height of discharging ports of feeding pipes 7,7... from the surface of a molten liquid by elevating the raw material feeding device 6, feeding a granular polycrystalline silicon in a raw material vessel 6a into the crucible 2 from plural feeding 7, 7..., while rotating the crucible 2, and melt and diffuse the granular polycrystalline silicon supplied to the molten liquid 8 by the heater 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a single crystal such as a silicon single crystal used as a semiconductor material.

[0002]

2. Description of the Related Art Generally, Czochralski method (CZ method) and two-layer pulling method (D
The pulling method such as LCZ method: Double Layered CZ) is widely used. In the CZ method, a quartz crucible having a bottomed cylindrical shape is filled with a crystal raw material and melted, and a seed crystal is immersed in the melt and pulled up to solidify the melt at the lower end of the seed crystal to form a single crystal. This is a method of growing crystals. A heater is concentrically arranged outside the crucible so as to melt the crystal raw material in the crucible.

In the DLCZ method, a crystal raw material is filled in a crucible and melted, and a heater outside the crucible causes the crystal raw material in the crucible to coexist with a solid layer on the lower side and a melt layer on the upper side, and a melt layer is present in the melt layer. In this method, a single crystal is grown by dipping the seed crystal and pulling it up to solidify the melt at the lower end of the seed crystal.

In these pulling methods, prior to pulling a single crystal, a polycrystal, which is a raw material for crystallization, is filled in a crucible and melted. The polycrystal used at this time has a diameter of 10
Solid raw materials such as a cylindrical cut rod of about 0 mm, a lump raw material that is a crushed material of the cut rod, and a granular raw material having a diameter of several mm. When the cut rod or the massive raw material is filled in the crucible, a space is generated between the raw materials in the crucible. Therefore, even if the crucible is filled with the maximum amount of solid raw material that can be loaded, melting it will cause the molten liquid to reach the maximum filling amount of the crucible.
Less than 60%. With the increase in the diameter of single crystals in recent years, it is required to increase the melt amount in the initial stage of pulling, but due to the space between the raw materials as described above, the crucible size must be increased to obtain the desired melt liquid. Therefore, there is a problem in that a single crystal manufacturing apparatus becomes large in size.

In order to solve this, after melting the solid raw material, the solid raw material is further supplied to increase the amount of the molten liquid. FIG. 5 is an explanatory view showing a conventional manner of increasing the amount of the melt. In the figure, 2 is a crucible, and the crucible 2 is filled with a molten liquid 8 obtained by melting a lump material. The cut rod 10 suspended above the crucible 2 is dipped in the melt 8 in the crucible 2, and the cut rod 10 is gradually immersed in the melt 8 to melt. The melt 8 in the crucible 2 is increased by this method.

[0006]

However, the cut rod currently used is about 30 kg at the maximum, and if the desired additional amount of the raw material is more than this, it is necessary to perform the melting work of the cut rod a plurality of times. There is. Since the cut rod is crushed by a rapid temperature change, its melting work is performed for a long time, and there is a problem that the productivity of a single crystal is remarkably reduced by performing this work a plurality of times. .

Further, as a method of increasing the amount of the molten liquid in the crucible, it is conceivable to put the lumpy raw material into the molten liquid. However, the lumped raw material put into the crucible causes splashing in the molten liquid, and the splashed molten liquid is in the crucible Adhere to the wall. The adhered melted liquid solidifies, and when the solidified mass on the inner wall surface of the crucible falls into the melted liquid during pulling of the single crystal, there is a problem that dislocation occurs in the pulled single crystal.

On the other hand, a method (continuous CZ method) of adding a polycrystalline raw material during a pulling period of a single crystal is known. Continuous C
The Z method is a method in which a polycrystalline raw material is supplied to the melt at the time of pulling a single crystal to keep the amount of the melt constant. The amount of the molten liquid is increased by supplying the granular raw material into the crucible from a supply pipe communicating with a raw material supply device provided above the crucible. It is conceivable to use this type of single crystal manufacturing apparatus to supply a granular raw material to the melt in order to increase the amount of the melt prior to the pulling. However, what is practically used in the continuous CZ method is a single crystal having a diameter of about 200 mm, and the supply rate of the granular raw material using this single crystal growth apparatus is 100 g / min or less. At such a supply rate, an extremely long time is required for increasing the amount of raw material before the pulling.

Further, in the continuous CZ method, the applicant of the present application has proposed a device capable of increasing the supply rate from the raw material supply device in response to the demand for increasing the amount of the initial melt with the increase in diameter (Japanese Utility Model Publication No. 5-43107). Gazette). This is an apparatus in which a plurality of raw material supply ports are uniformly arranged in the outer region of a double crucible having an inner region and an annular outer region. By supplying raw materials from multiple supply pipes, the amount of raw material supplied per hour can be increased, and the positions of the raw materials dropped can be made uniform within the surface of the molten liquid to prevent turbulence in the convection of the molten liquid during crystal pulling. The single crystal was improved in quality, and the granular raw material was supplied from each supply port during the single crystal pulling period.

The present invention has been made in view of the above circumstances, and before the pulling of a single crystal, the raw material is supplemented into the crucible from a plurality of raw material supply pipes to prevent the molten liquid from splashing. It is an object of the present invention to provide a single crystal manufacturing method and manufacturing apparatus capable of shortening the replenishment time of raw materials.

[0011]

A method for producing a single crystal according to a first aspect of the present invention is a method for producing a single crystal in which a raw material for a crystal in a crucible is melted and the crystal is pulled up from a melt while rotating the crucible to grow the crystal. In the method, a plurality of raw material supply pipes are used,
Prior to the pulling of the single crystal, a raw material for crystal is supplied from the plurality of raw material supply pipes into the crucible.

Since the raw materials are replenished from a plurality of supply pipes, 1
The amount supplied per unit time is larger than that when replenished from one supply pipe. Further, as compared with the case where one supply pipe having a diameter capable of supplying the same amount as a plurality of supply pipes is used, the area of the surface contact area of the raw material to the melt is small, and the melt does not splash to the crucible wall surface.

A method for producing a single crystal according to a second aspect of the present invention is a method for producing a single crystal in which a raw material for a crystal in a crucible is melted, and while the crucible is rotated, a crystal is pulled up from a melt to grow. Using a supply pipe, a step of loading a crystal raw material into the crucible and melting it, and a step of supplying the crystal raw material from the plurality of raw material supply pipes into the crucible filled with the melt And

The crystal raw material is loaded into the crucible and melted, and, for example, granular raw materials are supplied from a plurality of raw material supply pipes to increase the amount of the melt in the crucible, and then the single crystal is pulled up. Since the raw materials are replenished from a plurality of supply pipes, the supply amount per unit time is large, and the molten liquid does not splash to the crucible wall surface.

A method for producing a single crystal according to a third aspect of the present invention is a method for producing a single crystal in which a raw material for a crystal in a crucible is melted, and while the crucible is rotated, a crystal is pulled out from a molten liquid to grow. After the pulling of the single crystal by using a supply pipe, a process of supplying a crystal raw material from the plurality of raw material supply pipes into the crucible, a process of melting the supplied crystal raw material, and a crystal from a melt. It has a process of pulling it up and growing it.

When the single crystal is pulled up continuously after the pulling of the single crystal, the raw material for crystallization is supplied from the plurality of supply pipes to the last remaining melt, so that the melt does not splash to the wall surface of the crucible. The amount of raw material in the crucible is increased.

The method for producing a single crystal according to a fourth aspect of the present invention is the method for producing a single crystal according to the first, second or third aspect, wherein the raw material for crystal is melted in a crucible provided in the production apparatus, and the crucible is rotated to crystallize from the melt. In the method for producing a single crystal in which the raw material is pulled up to grow, the outlet of the raw material supply pipe is arranged in the melt.

Since the outflow port of the raw material supply pipe is in the melt and the crystal raw material does not flow directly into the melt from the supply pipe and does not splash, the supply speed of the crystal raw material can be increased. The raw material in the crucible is increased in a short time.

In the apparatus for producing a single crystal according to the fifth aspect of the invention, the raw material for crystal is supplied from a plurality of raw material supply pipes into the crucible and melted, and the crystal is pulled from the melt while rotating the crucible to grow the crystal. In the crystal manufacturing apparatus, the raw material supply pipe is characterized in that the outlet is directed toward the center of the crucible.

Since the outlet of the raw material supply pipe faces the center side of the crucible and does not adhere to the crucible wall surface even if splashing occurs on the melt surface, the supply rate of the crystal raw material can be increased, The amount of raw material in the crucible is increased in a short time.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. Embodiment 1. FIG. 1 is a schematic sectional view showing the structure of a single crystal manufacturing apparatus used for carrying out the method of the present invention. In the figure, 1 is a chamber. The chamber 1 is a substantially cylindrical vacuum container, and a crucible 2 is arranged at a substantially central position of the chamber 1. The crucible 2 is a quartz inner layer holding container 2a with a bottomed cylindrical shape.
And an outer layer holding container 2b made of graphite and having a cylindrical shape with a bottom fitted on the outer side of the inner layer holding container 2a. A shaft 3 for rotating and moving the crucible 2 up and down is attached to the lower surface of the outer layer holding container 2b, and, for example, a resistance heating type heater 4 is arranged up and down on the outer periphery of the outer layer holding container 2b. .
The heater 4 has a cylindrical shape concentric with the crucible 2, and a heat insulating cylinder 5 is arranged on the outer periphery of the heater 4 and the bottom of the chamber 1. By adjusting the relative positions of the crucible 2 and the heater 4 in the vertical direction, the polycrystalline raw material supplied into the crucible 2 is melted and the molten state of the melt 8 is maintained.

On the other hand, above the crucible 2, a pull chamber (not shown) is formed continuously above the chamber 1. A raw material supply device 6 is arranged so as to be able to move up and down above the outside of the pull chamber. The raw material supply device 6 is a raw material container with a bottom opening.
6a, a feeder 6b arranged below the raw material container 6a, and a funnel 6c for receiving the raw material supplied from the feeder 6b. By supplying a predetermined amount of the raw material to the funnel 6c by the feeder 6b, the crystal raw material filled in the raw material container 6a can be supplied at a predetermined speed. A branch opening is provided at the bottom of the funnel 6c, and a plurality of supply pipes 7, 7 ... Are connected. Each supply pipe 7, 7 ... penetrates the chamber 1,
A plurality of outlets are circumferentially arranged facing the melt 8 loaded in the crucible 2. The outlets of the supply pipes 7, 7 ... Can move in the height direction as the raw material supply device 6 moves up and down.

At the time of pulling up the single crystal, a pulling shaft is pierced through the pull chamber, a seed crystal is attached to the lower end of the pulling shaft, and the seed crystal is immersed in the melt 8 and then raised while rotating the seed crystal. Thus, a single crystal can be grown from the lower end of the seed crystal.

A procedure for filling the crucible 2 with the raw material for crystallization using the apparatus configured as described above will be described. First, massive polycrystalline silicon is loaded into the crucible 2 as a crystallization raw material, and the crystallization raw material is melted by the heater 4. Next, the height of the outlets of the supply pipes 7, 7, ... From the melt surface is adjusted to 20 mm to 30 mm by raising and lowering the raw material supply device 6. While rotating the crucible 2, the granular polycrystalline silicon filled in the raw material container 6a was introduced into the crucible 2 through the supply pipes 7, 7 ... 480 g / min (80 g / m
In × 6 supply pipes). The granular polycrystalline silicon supplied to the melt 8 is melted and diffused by the heater 4.

FIG. 2 is a schematic diagram showing the position of the surface of the granular raw material in the present embodiment. The granular raw material supplied from the supply pipes 7, 7 ... Is dropped in the contact surface regions P, P ... of the liquid surface of the molten liquid 8 loaded in the crucible 2. This landing area P,
The area of P ... Is extremely small as compared with the area of the landing area by one supply pipe having a diameter capable of supplying the same amount of raw material as those of the supply pipes 7, 7. Such a small landing area P, P
Since granular polycrystalline silicon is supplied to ..., Splash is unlikely to occur on the melt surface. Even if it happens, it does not adhere to the inner wall surface of the crucible because it is a small bounce. Furthermore, a large amount of the crystal raw material can be supplied per unit time as compared with the case where one supply pipe having the same diameter is provided.

[0026]

[Table 1]

Using the above-mentioned apparatus, a silicon single crystal was manufactured under the conditions shown in Table 1 above. First, the loading rate is 55%
Supplying 40 kg of raw material for crystallization into crucible 2 of 480 g / min
(80 g / min × 6 supply pipes). Replenishment time is short
It was 83 minutes. When the crystal raw material was supplied from the supply pipes 7, 7, ..., Splash of the melt 8 did not occur, and a high quality single crystal could be manufactured. Further, in the conventional cut rod supply method, when a crucible of the same size is used, it takes 8 hours to replenish the same amount of the crystal raw material. It has been found that it is possible to reduce the time required for increasing the melt volume in advance and to produce high-quality single crystals. Note that, due to the structure of the raw material supply device 6 and the supply pipes 7, 7, ..., And the molten state of the granular raw material into the molten liquid 8, the supply rate of the crystal raw material is 200 g / min per supply pipe. The following is preferable.

Further, after the single crystal pulling is completed and the grown single crystal is unloaded from the chamber 1, the single crystal may be continuously pulled under the same conditions. In this case, crucible 2
A small amount of the melt 8 remains inside, and the raw material for crystallization is replenished therein. First, the raw material container 6a is filled with granular polycrystalline silicon, and when the raw material supply device 6 is moved up and down, the supply pipes 7, 7 ...
Adjust the height of the outflow port from the melt surface. While the crucible 2 is being rotated, granular polycrystalline silicon is supplied into the crucible 2 from the supply pipes 7, 7, ... And the heater 4 melts and diffuses the granular polycrystalline silicon. After replenishing the polycrystalline silicon, the lower end of the seed crystal was immersed in the melt 8 and pulled while rotating the pulling shaft to grow a single crystal.

When the crystal raw material was supplied from the supply pipes 7, 7, the splash of the melt 8 did not occur, and a high quality single crystal could be manufactured. As described above, according to the method of the present invention, when the single crystal is continuously grown after the pulling of the single crystal is completed, the crystal raw material in the crucible can be replenished in a short time without adhering the splash of the melt to the crucible wall. You can

Embodiment 2 FIG. FIG. 3 is a schematic cross-sectional view showing the manner of supply of the crystal raw material in the second embodiment. As the manufacturing apparatus, the apparatus shown in FIG. 1 is used, the same parts are designated by the same reference numerals, and the description thereof will be omitted. When granular polycrystalline silicon is supplied from the supply pipes 7, 7 ... into the crucible 2, the raw material supply device is moved up and down to immerse the outlets of the supply pipes 7, 7 ... into the melt 8 to a depth of about 10 mm. Then, the crystallization raw material is melted in the melt 8. The raw material for crystal is the supply pipes 7,7 ...
Since the melt 8 is directly carried into the melt 8 through the passage, the melt 8 does not splash. Thereby, the supply rate of the crystal raw material can be further increased.

Embodiment 3 FIG. 4 is a schematic cross-sectional view showing only the main part of the single crystal manufacturing apparatus used in the third embodiment of the present invention. In the figure, 7a, 7a ... Are supply pipes communicating with the raw material supply device, and the tips of the supply pipes 7a, 7a are bent so that their respective outlets face the center of the crucible 2. Other configurations are the same as those in FIG. 1, and the same parts are denoted by the same reference numerals and the description thereof is omitted.

Using such a device, a single crystal is manufactured in the same procedure as in the first embodiment. Since the outlets of the supply pipes 7a, 7a ... Are directed toward the center of the crucible 2, the contact area P, P ... to the melt surface as shown in FIG. 2 is the center side of the crucible 2, It is possible to further prevent 8 from adhering to the wall surface. Thereby, the supply rate of the crystal raw material can be further increased.

Although FIG. 4 shows the case where the tip of the supply pipe is bent toward the center of the crucible 2, the present invention is not limited to this, and the outlet may be directed toward the center, for example, a straight shape. The supply pipe of may be arranged diagonally.

In the above-described embodiment, the supply pipe is 6
Although the case of providing a plurality of books has been described, the present invention is not limited to this, and a plurality of books may be provided. In addition, the case where the supply pipe is arranged so that the outlets are arranged in a circular shape is explained.
It is not limited to this, and it may be arranged at a position separated from the inner wall side of the crucible by an appropriate length.

[0035]

As described above, in the present invention, the raw material is filled into the crucible from a plurality of raw material supply pipes before pulling the single crystal, so that the splash of the molten liquid can be adhered to the crucible wall surface. Also, the replenishment time can be shortened. Further, since the outlet of the raw material supply pipe faces the center side of the crucible, the melt is further prevented from adhering to the wall surface of the crucible. Furthermore, since the outlet is arranged in the melt, the splash of the melt can be eliminated, and the present invention has excellent effects.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the structure of a single crystal manufacturing apparatus used for carrying out the method of the present invention.

FIG. 2 is a schematic diagram showing the position where the granular raw material is adhered to in the first embodiment.

FIG. 3 is a schematic cross-sectional view showing how the crystal raw material is supplied in the second embodiment.

FIG. 4 is a schematic cross-sectional view showing only a main part of a single crystal manufacturing apparatus used in a third embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a state of increasing the amount of a conventional melt.

[Explanation of symbols]

 1 Chamber 2 Crucible 6 Raw Material Supply Device 7, 7a Supply Pipe 8 Melt Liquid P Adhesion Area

Claims (5)

[Claims] 1. A method for producing a single crystal in which a raw material for a crystal in a crucible is melted, and the crucible is rotated to pull up the crystal from a molten liquid to grow the single crystal, wherein a plurality of raw material supply pipes are used to pull up the single crystal. Prior to the step 1, a method for producing a single crystal, characterized in that a raw material for crystallization is supplied into the crucible from the plurality of raw material supply pipes. 2. A method for producing a single crystal in which a raw material for crystal in a crucible is melted, and while the crucible is rotated, the crystal is pulled up from a melt to grow, a plurality of raw material supply pipes are used, and the crystal is formed in the crucible. 1. A method for producing a single crystal, comprising: a step of charging a raw material for melting and melting the raw material; and a step of supplying a raw material for crystallization from the plurality of raw material supply pipes into the crucible charged with the melt. 3. A method for producing a single crystal in which a raw material for a crystal in a crucible is melted, and the crucible is rotated to pull up the crystal from a molten liquid to grow the single crystal, wherein a plurality of raw material supply pipes are used to pull up the single crystal. After the end,
It has a step of supplying a crystal raw material into the crucible from the plurality of raw material supply pipes, a step of melting the supplied crystal raw material, and a step of pulling and growing crystals from the melt. Method for producing single crystal. 4. The method for producing a single crystal according to claim 1, 2 or 3, wherein an outlet of the raw material supply pipe is arranged in the melt. 5. An apparatus for producing a single crystal in which a raw material for crystallization is supplied into a crucible from a plurality of raw material supply pipes to be melted, and a crystal is pulled out from a molten liquid to grow while rotating the crucible. Is an apparatus for producing a single crystal, characterized in that the outlet is directed toward the center side of the crucible.