JP2001213691A - Reflection material of single crystal growth equipment and melting method using its equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To melt silicon in a simple manner in a short time. SOLUTION: The reflection material 26 is equipped with the disk plate 27, having a mirror finished and bottom side surface and a higher melting point than silicon, and the rod 28, being installed vertically at center of the disk plate 27 supported by a holder 21 at the top. At melting silicon lumps or particles 29, the lumps or particles 29 are put in the pot 17 inside the furnace, the rod 28 of reflection material 26 is attached to the seed crystal holder 21 being hung with the wire 19 from the rotating/raising structure 18 installed at the top of the furnace 11, the disk plate 27 of the reflection material 26 is let down with the wire 19 and kept horizontally above the pot 17 in a way of covering the opening mouth of the pot 17 in part, and then, the pot 17 is heated. Polycrystal lumps or particles 24 are put in the pot 17 and melted by heating the pot.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for growing a silicon single crystal by the Czochralski method (hereinafter referred to as "CZ method"), wherein a reflecting member used for melting silicon and a reflecting member used therefor. The present invention relates to a method for melting silicon.

[0002]

2. Description of the Related Art Conventionally, as a method for growing a silicon single crystal, a CZ method for growing a high-purity silicon single crystal for a semiconductor from a silicon melt in a crucible is known. This method attaches a seed crystal to a seed crystal holder suspended inside the furnace body above the crucible via a wire from a rotation / pulling mechanism provided at the top of the furnace body having a crucible inside,
Unwinding the wire, bringing the seed crystal into contact with the silicon melt, pulling up the seed crystal, creating a seed drawing portion from the silicon melt, and then gradually growing the crystal to the desired diameter of the silicon rod Thereby, a dislocation-free single crystal ingot having a necessary plane direction can be obtained. The silicon melt is melted in the crucible, and the crucible is heated by a carbon heater.

However, the melting temperature of polycrystalline silicon is about 14
Since the temperature is 00 ° C. and a silicon single crystal is grown, it takes a relatively long time to completely melt the mass or granular material initially filled in the crucible. In particular, a relatively large amount of silicon melt is required in accordance with the growing diameter and length of the single crystal to be grown today, and the time required to melt this silicon has led to a problem that the efficiency of the silicon single crystal ingot growing process is reduced. . In order to solve this problem, an apparatus has been proposed in which an infrared reflecting plate is provided above the crucible except for a portion through which a silicon single crystal ingot to be grown passes (for example, Japanese Patent Publication No. 57-40119, Japanese Patent Publication No. Hei 6-1994). 3
3218). In these devices, the crucible surrounded by the infrared reflecting plate can be efficiently heated by the carbon heater, so that the lump or granular material made of silicon put in the crucible can be melted easily in a short time. It has become.

[0004]

However, in the above-described apparatus, since a reflector is not provided at a portion where a single crystal ingot to be grown passes, heat is radiated from the portion where the single crystal ingot passes to an upper portion of the furnace body, and a lump is formed. Alternatively, there was a problem that the time required to melt the granular material could not be sufficiently reduced. If the reflector is provided all over the crucible, the reflector may hinder the growth of the single crystal ingot. However, there is still a problem that needs to be solved.
An object of the present invention is to provide a reflecting member of a single crystal growing apparatus capable of melting a lump or granular substance made of silicon in a short time and simply, and a method for melting silicon using the same.

[0005]

The invention according to claim 1 is
As shown in FIG. 1, a furnace body 11 having a crucible 17 therein
Wire 1 from the rotation / pulling-up mechanism 18
A reflecting member 26 detachably attached to a seed crystal holder 21 suspended inside the furnace body above the crucible 17 via a crucible 9 and having a melting point equal to or higher than the melting point of silicon whose lower surface is mirror-finished; This is a reflecting member of a single crystal growing apparatus including a plate 27 and a rod 28 erected at the center of the disk 27 and whose upper portion is configured to be attachable to the holder 21. According to the second aspect of the present invention, a lump or granular material 29 made of silicon is put into a crucible 17 provided inside the furnace body, and is rotated via a wire 19 from a rotation / pulling-up mechanism 18 provided at an upper portion of the furnace body 11. The rod 28 of the reflecting member 26 according to claim 1 is attached to the suspended seed crystal holder 21, and the wire 19 is extended to cover a part of the opening of the crucible 17 above the crucible 17. The disk 27 is held horizontally and the crucible 17 is heated to remove
Is a method of melting silicon.

[0006] The reflecting member according to the first aspect and the second aspect.
In the melting method according to the above, when the crucible 17 is heated to start melting the silicon, as shown by solid arrows in FIGS. 1 and 3, the diffusion of the heat released from the upper surface of the crucible 17 of the melted silicon is reflected by the reflecting member. The disk 27 prevents the heat and reflects the heat toward the lump or granule made of the silicon 24. By applying the heat reflected by the disk 27, the melting time of the lump or granule made of silicon is shortened as compared with the related art. The reason why the lower surface of the disk 27 is mirror-finished is to increase the amount of heat reflected by the lower surface of the disk 27, and the mirror surface finishing includes mirror polishing or mirror etching.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. As shown in FIGS. 1 and 2,
In an apparatus for growing a single crystal from a silicon melt by the CZ method, a heat insulating material 12 concentrically with the furnace body 11 is provided inside the furnace body 11.
And a carbon heater 13 are arranged, and a bottomed cylindrical quartz crucible 17 is fitted to a graphite susceptor 16 fixed to the upper end of a rotating shaft 14 at the center of the furnace body 11. A rotating / pulling-up mechanism 18 is provided above the furnace body 11 via a cylindrical chamber 15, and a seed crystal holder 21 is suspended above the crucible 17 from the rotating / pulling-up mechanism 18 via a wire 19. Can be When growing a silicon single crystal, a seed crystal (not shown) is attached to the seed crystal holder 21, and the rotation / pulling-up mechanism 18 pulls up a high-purity silicon single crystal ingot grown from the seed crystal while rotating the seed crystal. A high-purity silicon single crystal ingot is grown at the lower end of the crystal.

On the other hand, the furnace body 11 and the chamber 15
At the upper part of the furnace body 11 to which the chamber 15 is mounted via the 5a, a shielding plate 22 capable of closing the opening 11a at that portion is provided. The shield plate 22 opens the opening 11a in a storage state in the storage part 11b provided in the furnace body 11 and projects from the storage part 11b to open the opening 1a.
1a is configured to be closed. At the upper edge of the heat insulating material 12, a disk-shaped infrared reflecting plate 23 is disposed inwardly so as to surround the crucible 17 and the upper portion of the carbon heater 13, and the infrared reflecting plate 23 is a single crystal to be grown. A hole 23a slightly larger than the outer shape of the single crystal ingot grown at the center thereof is provided so as not to come into contact with the ingot. As shown in FIG. 4, the seed crystal holder 21 has a seed crystal insertion hole 21a formed along the central axis at the bottom of the chuck body 21d, and is perpendicular to the insertion hole 21a and with respect to the axis of the insertion hole 21a. As a result, the pin hole 21b is formed. The pin hole 21b is formed so that the cross-sectional area at the center of the pin hole 21b overlaps the insertion hole 21a by about half. The seed crystal is attached when growing the silicon single crystal by inserting a seed crystal (not shown) into the insertion hole 21a and inserting the locking pin 24 into the pin hole 21b of the seed crystal holder 21. ing.

The reflecting member 26 of the present invention is detachably attached to the seed crystal holder 21 and includes a disk 27 and a rod 28 whose upper part is configured to be attachable to the holder 21. The disk 27 is a plate material made of molybdenum having a melting point equal to or higher than the melting point of silicon and having an outer diameter slightly smaller than the hole 23 a of the infrared reflecting plate 23. The lower surface of the disk 27 is mirror-finished such as mirror polish or mirror etching. The rod 28 is a rod made of molybdenum and having a circular cross section. The lower end of the rod 28 is press-fitted into a mounting hole (not shown) formed in the center of the disk 27 and is erected at the center of the disk 27. Rod 28
Is formed in a shape similar to a seed crystal not shown. That is, the rod 28 has an outer diameter that can be inserted into the insertion hole 21a of the seed crystal holder 21, and a notch surface 28a that is notched deeply downward is formed on the upper side of the rod 28.

The upper part of the rod 28 is attached to the holder 21 by inserting the upper part of the rod 28 into the insertion hole 21a in the same manner as the attachment of the seed crystal (not shown), and then the locking pin 24 is inserted into the pin hole 21b of the seed crystal holder 21. This is done by inserting The body of the locking pin 24 inserted into the pin hole 21b abuts a notch surface 28a formed in the rod 27, and the movement of the rod 28 with respect to the insertion hole 21a is prohibited. It is configured to be attached to the seed crystal holder 21. On the other hand, the locking pin 2 is inserted through the pin hole 21b.
When the rod 4 is removed, the rod 28 is allowed to move with respect to the insertion hole 21a, and the reflecting member 26 is configured to be detachable from the seed crystal holder 21.

Next, a description will be given of a method of melting silicon using the reflecting member having such a configuration. As shown in FIG. 2, first, a lump or granule 29 made of silicon is put into a crucible 17 provided inside a furnace body. In this embodiment, silicon is a novel polycrystalline silicon made of a granular material. However, the silicon may be a crushed single crystal that has failed to grow, or the silicon may be a lump.
Thereafter, the rod 28 of the reflection member 26 is attached to the seed crystal holder 21 suspended via the wire 19 from the rotation / pulling-up mechanism 18 provided on the upper part of the furnace body 11 using the locking pin 24. As shown in FIG. 2, the attachment of the reflection member 26 is performed in a state where the chamber 15 is tilted with respect to the furnace body 11 and the seed crystal holder 21 is pulled out from the lower end of the chamber 15. After attaching the rod 27 to the seed crystal holder 21, the chamber 15 is returned again, and the reflecting member 26 is positioned above the crucible 17.

Next, the wire 19 is paid out and the crucible 17 is drawn out.
The disk 27 of the reflecting member 26 is held horizontally so as to cover a part of the opening of the crucible 17 above. Since the disk 27 has an outer diameter smaller than the hole 23a of the infrared reflecting plate 23,
When the wire 19 is unwound, the reflection member 26 has its hole 23a.
And descends through. By stopping the feeding of the wire 19 when the reflecting member 26 reaches the vicinity of the crucible 17, as shown in FIG. 3, the disc 27 of the reflecting member 26 covers a part of the opening of the crucible 17. Holds horizontally. Thereafter, the crucible 17 is heated by the carbon heater 13.
Is heated to melt the lumps or granules 29 placed in the crucible 17.

The heat of the carbon heater 13 disposed around the crucible 17 causes the lump or granular material 24 made of polycrystalline silicon put into the crucible 17 from the periphery to start melting. As shown by the solid arrows in FIGS. 1 and 3, the dissipation of the heat released from the upper surface of the crucible 17 of the polycrystalline silicon in which the melting has started is prevented by the disk 27 of the reflecting member 26, and the disk 27 Is reflected toward the clumps or granules 24. In particular, the reflectivity of the lower surface of the mirror-finished disk 27 is improved as compared with the case without the mirror surface finish.
The heat emitted from the upper surface of the crucible 17 is effectively reflected, and the heat makes the melting of the polycrystalline silicon faster. Also,
In this embodiment in which the infrared reflecting plate 23 is provided above the crucible 17 excluding the portion through which the silicon single crystal ingot to be grown is passed, as shown in FIG. 1, heat dissipation from the upper surface of the crucible 17 where melting has started. The reflection member 26 of the present invention
Is more effectively prevented by the infrared reflector 23. As a result, the melting time of the lump or granule made of silicon is further reduced.

After the lump or granule made of silicon is melted, a high-purity silicon single crystal for a semiconductor is grown from the silicon melt 31. At the time of this growth, a seed crystal (not shown) is replaced with a seed crystal holder 21 instead of the reflection member 26.
Attach to The removal of the reflection member 26 and the attachment of the seed crystal are performed by tilting the chamber 15 with respect to the furnace body 11 and pulling out the seed crystal holder 21 from the lower end of the chamber 15. At this time, as shown in FIG. 2, the inside of the furnace body 11 is prevented from being cooled by protruding the shielding plate 22 from the housing portion 11 b and closing the opening 11 a of the furnace body 11. After replacing the rod 27 with a seed crystal, the chamber 15
Is returned, and the shielding plate 22 is housed in the housing portion 11b to open the opening 11a again. Thereafter, the seed crystal is brought into contact with the silicon melt 31, and the rotation / pulling-up mechanism 18 pulls up the high-purity silicon single crystal ingot grown from the seed crystal while rotating, and puts the high-purity silicon single crystal ingot on the lower end of the seed crystal. Grow.

In the above-described embodiment, the disk 27
Although molybdenum having a melting point equal to or higher than the melting point of silicon was used, the disk 27 may be tungsten or a silicon wafer. When the reflecting member 26 is made of a silicon wafer, after all the silicon put in the crucible 17 is melted, the reflecting member 26 can be melted in a silicon melt in which a lump or granular material made of silicon is melted. If the reflecting member 26 is melted into the silicon melt, the operation of removing the reflecting member 26 from the furnace body 11 in a later step can be omitted.

[0016]

As described above, according to the present invention, a disk having a melting point equal to or higher than that of silicon whose lower surface is mirror-finished, and an upper portion which is erected at the center of the disk and can be attached to the holder can be attached. Using a reflecting member of a single crystal growing apparatus provided with a constituted rod, a lump or granule made of silicon is put into a crucible provided inside a furnace body, and a rotating / pulling mechanism provided at an upper part of the furnace body Attach the rod to the seed crystal holder suspended from the wire through the wire, pay out the wire, hold the disk horizontally so as to cover part of the crucible opening above the crucible, and heat the crucible When the crucible is heated and melting of the silicon starts, the disk prevents the heat released from the upper surface of the crucible from dissipating and reflects the heat. Due to the heat reflected by the disk, the melting time of the bulk or granular material made of silicon can be shortened as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a single crystal growing apparatus including a reflecting member of the present invention.

FIG. 2 is a schematic sectional view corresponding to FIG. 1 and showing a state where the chamber is tilted.

FIG. 3 is a sectional view showing a state in which a reflecting member is arranged above a crucible.

FIG. 4 is a perspective view showing a state in which the reflection member is attached to a holder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Furnace body 17 Crucible 18 Rotation / pulling-up mechanism 19 Wire 21 Seed crystal holder 26 Reflection member 27 Disk 28 Rod 29 Lumped or granular material made of silicon

Claims (2)

[Claims] 1. An inside of a furnace body above a crucible (17) via a wire (19) from a rotating / pulling-up mechanism (18) provided on an upper part of a furnace body (11) having a crucible (17) therein. A reflecting member (26) detachably attached to a seed crystal holder (21) suspended from the mirror, a disk (27) having a melting point equal to or higher than the melting point of silicon whose lower surface is mirror-finished; A reflecting member of a single crystal growing apparatus, comprising: a rod (28) that is provided upright at the center of a plate (27) and whose upper part is configured to be attachable to the holder (21). 2. Blocks or granules made of silicon (29)
Into a crucible (17) provided inside the furnace body, and a rotating / pulling-up mechanism (18) provided above the furnace body (11).
For seed crystal suspended from wire through wire (19)
The rod (28) of the reflecting member (26) according to claim 1 is attached to (21), and the wire (19) is fed out to partially open the crucible (17) above the crucible (17). The reflecting member to cover
A silicon melting method in which the disk (27) of (26) is held horizontally, and the crucible (17) is heated to melt the lump or the granular material (29).