JPH11255591A - Auxiliary apparatus for melting single crystal raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a susceptor crucible from being damaged by improving the thermal efficiency when heating and melting the raw material in an auxiliary crucible. SOLUTION: This apparatus is obtained by forming a melt tap hole 1a for discharging a melt in the interior to the outside at the time of tilting in the auxiliary crucible 1 made of quartz, supporting the auxiliary crucible 1 with a boron nitride(BN) crucible 21 as a susceptor crucible, embedding a carbon heater 22 in a comb-toothed form in the BN crucible 21 and in a zigzag form even in the base of the BN crucible 21, forming one or more slits 23 for preventing cracking in the longitudinal direction and attaching a joint serving both as a tilting shaft and as an electrode to the BN crucible 21. The BN is an insulating material without reacting with the quartz and having a lower thermal conductivity than that of the quartz. Pyrolytic boron nitride(PBN) may be used in place of the BN.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a pulling CZ (Czoc).
The present invention relates to a raw material auxiliary melting apparatus in a single crystal pulling apparatus for manufacturing a dislocation-free single crystal of Si (silicon) by the hralski method, and more particularly, to heat and melt a single crystal raw material in an auxiliary crucible. The present invention relates to a single crystal raw material auxiliary melting device for supplying a main crystal to a main crucible by tilting the auxiliary crucible.

[0002]

2. Description of the Related Art In general, in a single crystal manufacturing apparatus by the pulling CZ method, a high pressure-resistant airtight chamber is decompressed to about 10 torr and fresh Ar (argon) gas is flown, and a quartz crucible provided below the chamber is provided. The polycrystal in is melted by heating, and the seed crystal is immersed in the surface of this melt from above,
The seed crystal and the quartz crucible are rotated and moved up and down, and the seed crystal is pulled up to form a conical upper cone with the upper end protruding below the seed crystal, and a conical lower part with a cylindrical body and lower end protruding. It is configured to grow a single crystal (so-called ingot) composed of a cone portion.

[0003] As a conventional method for dissolving a raw material in such an apparatus, a crucible for pulling a single crystal (hereinafter referred to as a crucible).
A method has been proposed in which the amount of the molten raw material in the main crucible is reduced by using an auxiliary crucible. For example, JP-A-55-1308
No. 94 proposes a method in which a raw material is dissolved in an auxiliary crucible that communicates with a main crucible, and is additionally supplied from the auxiliary crucible to the main crucible via a communication pipe. In addition, Japanese Unexamined Patent Publication No.
Japanese Patent Application Laid-Open No. 6-164097 proposes a method in which a solid raw material is supplied from an outside of a pulling device to an auxiliary crucible in the pulling device and melted, and the dissolved raw material is additionally supplied from the auxiliary crucible to the main crucible.

Further, as a structure for supplying the melt in the auxiliary crucible to the main crucible, a tilting method for tilting the auxiliary crucible is generally used. 4 and 5 show a resistance heating type structure as a conventional example using the tilting method. The auxiliary crucible 1 made of quartz is provided with a melt tapping port 1a for taking out an internal melt (not shown) at the time of tilting. The auxiliary crucible 1 is supported by a carbon crucible 3 as a susceptor crucible.
The tilting shaft 2 is attached to a position corresponding to the vicinity of. A carbon heater 4 is fixed around the carbon crucible 3 so as not to contact the carbon crucible 3, and a pair of electrode joints 5 is coupled to the carbon heater 4.

In such a structure, when a DC voltage is applied to both ends of the electrode joint 5, the carbon heater 4 as a resistor generates heat and the raw material in the auxiliary crucible 1 passes through the carbon crucible 3 by the carbon heater 4. Is heated. When the raw material in the auxiliary crucible 1 is melted, the auxiliary crucible 1 and the carbon crucible 3 are tilted integrally, and the melt in the auxiliary crucible 1 is supplied to a main crucible (not shown) via the melt tapping port 1a.

FIGS. 6 and 7 show an induction heating type structure as another conventional example using the tilting method. Melt tap 1a
The quartz auxiliary crucible 1 on which is formed the carbon crucible 3
, And the carbon crucible 3 is supported by an insulating induction heating crucible 6 such as alumina. Inside the induction heating crucible 6, a copper water-cooled pipe coil 7 in which a cavity for flowing cooling water is formed is embedded, and the induction heating crucible 6 is fitted with a pair of tilt shafts and electrode joints 8. ing. In such a structure,
When an AC voltage is applied to both ends of the tilt shaft and electrode joint 8, an induction magnetic field is generated by the coil 7 in the induction heating crucible 6, and the raw material in the auxiliary crucible 1 is heated by the induction magnetic field. When the raw material in the auxiliary crucible 1 is melted, the auxiliary crucible 1, the carbon crucible 3, and the induction heating crucible 6 are tilted integrally, and the melt in the auxiliary crucible 1 is transferred to the main crucible (not shown) through the melt tapping port 1a. Supplied.

[0007]

However, in the above-described conventional example of the resistance heating type, the insulation between the conductive carbon crucible 3 and the carbon heater 4 is ensured, and the raw material comes into contact with the carbon heater 4. In order to prevent contamination, it is necessary to separate the carbon crucible 3 and the carbon heater 4 from each other, so that there is a problem that thermal efficiency is poor. In particular, as shown in FIGS.
In the case of the structure in which the tilting shaft 2 is mounted in the vicinity of a, the space a between the carbon crucible 3 and the carbon heater 4 on the side opposite to the tap hole 1a does not contact the carbon heater 4 when the carbon crucible 3 is tilted. Need to be greatly separated from each other. Therefore, a large space is required.

[0008] Similarly, in the above-mentioned conventional example of the induction heating type, the conductivity of silicon is low at a low temperature and high at a high temperature. Therefore, in this method, it is necessary to start induction heating after dissolving a part of the raw materials and supplying the raw materials into the auxiliary crucible 1 during the initial heating. Also, with this method,
Since the coil 7 is buried in the induction heating crucible 6, a slit for preventing cracking cannot be formed in the induction heating crucible 6, so that after the molten liquid in the auxiliary crucible 1 is discharged, the remaining solidifies and expands. In addition, there is a problem that the induction heating crucible 6 and the coil 7 therein are damaged. Further, in the conventional example of the induction heating type, there is also a problem of electric discharge and leakage of cooling water.

The present invention has been made in view of the above-mentioned problems of the prior art, and has a small space for heating and melting a raw material in an auxiliary crucible, thereby improving the thermal efficiency when heating and melting the raw material. It is another object of the present invention to provide a single crystal raw material auxiliary melting apparatus capable of preventing a susceptor crucible from being damaged.

[0010]

According to the present invention, in order to achieve the above object, a susceptor crucible for supporting an auxiliary crucible is formed of an insulating material, and a susceptor crucible and a carbon heater are integrated. That is, according to the present invention, in a single crystal raw material auxiliary melting apparatus for heating a single crystal raw material in an auxiliary crucible to melt the raw material and supplying the molten raw material to a main crucible by tilting the auxiliary crucible, A susceptor crucible supporting the auxiliary crucible is formed of an insulating material, a carbon heater integrated with the susceptor crucible is provided, and the susceptor integrated with the carbon heater and the auxiliary crucible can be tilted integrally. A featured single crystal raw material auxiliary melting apparatus is provided.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a configuration diagram showing a single crystal pulling apparatus to which an embodiment of a single crystal raw material auxiliary melting apparatus according to the present invention is applied, FIG. 2 is a plan view showing the auxiliary melting apparatus of FIG. 1 in detail, and FIG. It is a side view which shows the auxiliary | assistant dissolution apparatus in detail.

In FIG. 1, a cylindrical heater 12 is arranged around a main crucible 11 made of quartz, and a cylindrical heat insulating material 13 is arranged around the heater 12. These members 11 to 13 are arranged in the lower chamber 14.
Although not shown, the main crucible 11 is supported by a carbon crucible, and the main crucible 11 and the carbon crucible are supported so as to be movable up and down and rotatable around an axis. On top of the lower chamber 14 is the upper chamber 1
5 is arranged, and a cable 15 for pulling the single crystal 10 from the upper chamber 15 is movable vertically.
It is suspended rotatably around an axis.

An auxiliary chamber 17 is also disposed above the lower chamber 14, in which the molten material is supplied into the main crucible 11 as shown in FIGS. An auxiliary melting device 20 is arranged. The lower chamber 14, the upper chamber 15, and the auxiliary chamber 17 communicate with each other and are maintained at a low pressure.
In addition, an inert gas such as Ar is flowing.

In FIG. 2 and FIG. 3, the auxiliary crucible 1 made of quartz is provided with a melt tapping port 1a for taking out an internal melt (not shown) when tilted, and this auxiliary crucible 1 acts as a susceptor crucible. It is supported by a BN (Boron Nitride: boron nitride) crucible 21. A comb-shaped groove is provided on the outer peripheral portion of the BN crucible 21, and a part of the carbon heater 22 has a comb-shaped resistor embedded in the comb-shaped groove. Also, on the bottom surface of the BN crucible 21, a part of the carbon heater 22 is embedded in a similarly shaped groove as a resistor arranged in a zigzag shape. The BN crucible 21 has an axial direction (vertical direction).
One or more slits 23 for preventing cracks are formed in the slit. The slit 23 absorbs an increase in the volume of the BN crucible 21. As a preferred embodiment of the slit 23, a slit having a gap of several mm
It can be provided in about several places. BN crucible 21 also has
A tilt shaft / electrode joint 24 is attached. The tilting shaft 2 of the conventional resistance heating type carbon crucible 3 shown in FIG.
Are provided separately from the electrode joint 5 of the carbon heater 4. However, in the present invention, these can be integrated into a tilt shaft / electrode joint 24. The carbon heater 22 is energized by applying a predetermined voltage so that a current flows from one side of the tilt shaft / electrode joint 24 to the other.

[0015]

[Table 1] Here, the BN constituting the susceptal crucible 21
Is a material that is insulative and does not react with quartz, and has a lower thermal conductivity than quartz. Its main characteristics are as follows. Density: 1.92 g / cm ³ Flexural strength: 420 kg / cm ² Compressive strength: 570 kg / cm ² Thermal conductivity: 0.18 cal / cm · sec · ° C Thermal expansion coefficient: 0.86 × 10 ⁻⁶ / ° C (Room temperature to 1000
° C) Intrinsic specific resistance: 1 × 10 ¹⁴ Ω · cm Withstand voltage: 40 kV / mm

[0016] In place of BN, PBN (Pyrolytic
Boron Nitride (pyrolytic (pyrolytic) boron nitride) may be used. However, since PBN is usually manufactured by thermal CVD, it can be manufactured in a thin plate shape, cylindrical shape, or crucible shape, but is more expensive than BN. On the other hand, BN
Is manufactured by sintering after press molding,
Cylindrical and crucible shapes can be manufactured at low cost.

[0017]

Next, an embodiment and a conventional example (resistance heating type) will be described. First, the same carbon heater 22 was used as follows. Outer diameter: 260mm Height: 150mm Wall thickness: 10mm Slit width: 5mm Resistor width: 35mm Number of circumferential resistors (number of divisions): 20 Resistivity: 0.027Ω (1600 ° C)

[0018]

The following crucibles 1 were used as auxiliary crucibles. (1) Conventional example Outer diameter: 120 mm Height: 180 mm Effective melt holding amount: about 3 kg (2) Example Outer diameter: 220 mm Height: 180 mm Effective melt holding amount: about 10 kg

The dissolution rates of the raw materials were as follows. (1) Conventional example: 67 g / min (2) Example: 167 g / min Therefore, even if the auxiliary crucible 1 was enlarged, the heating efficiency was improved. Further, even after the raw material was dissolved and supplied to the main crucible 11, the BN crucible 21 and the carbon heater 22 were not damaged.

[0020]

As described above, according to the present invention, in a single crystal raw material auxiliary melting apparatus for supplying a molten raw material to a main crucible by tilting, a susceptor crucible supporting the auxiliary crucible is formed of an insulating material. In addition, since the susceptor crucible and the carbon heater are integrated, the heat efficiency in heating and melting the raw material in the auxiliary crucible can be improved with a small space occupation. In addition, since a slit for preventing cracks can be formed in the susceptor crucible, breakage of the susceptor crucible can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a single crystal pulling apparatus to which an embodiment of a single crystal raw material auxiliary melting apparatus according to the present invention is applied.

FIG. 2 is a plan view showing the auxiliary melting device of FIG. 1 in detail.

FIG. 3 is a side view showing the auxiliary melting device of FIG. 2 in detail.

FIG. 4 is a plan view showing a conventional auxiliary melting device.

FIG. 5 is a side view showing the auxiliary melting device of FIG. 4;

FIG. 6 is a side view showing another conventional auxiliary melting device.

FIG. 7 is a plan view showing the auxiliary melting device of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Auxiliary crucible 21 BN crucible 22 Carbon heater 23 Slit 24 Tilt axis and electrode joint

Claims (6)

[Claims] A single crystal raw material auxiliary melting apparatus for heating a single crystal raw material in an auxiliary crucible to melt the raw material and feeding the molten raw material to a main crucible by tilting the auxiliary crucible, A susceptor crucible supporting the susceptor crucible is formed of an insulating material, a carbon heater integrated with the susceptor crucible is provided, and the susceptor integrated with the carbon heater and the auxiliary crucible can be tilted integrally. Single crystal raw material auxiliary melting device. 2. The single crystal raw material auxiliary melting according to claim 1, wherein said carbon heater has a comb-shaped resistor embedded in a comb-shaped groove provided on an outer peripheral portion of said susceptor crucible. apparatus. 3. The single crystal raw material auxiliary melting apparatus according to claim 1, wherein the insulating material is boron nitride. 4. The single crystal raw material auxiliary melting apparatus according to claim 1, wherein the insulating material is pyrolytic boron nitride. 5. The single crystal material auxiliary melting apparatus according to claim 1, wherein a slit for preventing cracking is formed in an axial direction of the susceptor crucible. 6. The susceptor is provided with a tilt shaft and an electrode joint for tilting the susceptor and energizing the carbon heater.
5. The single crystal raw material auxiliary melting apparatus according to any one of items 1 to 4,