JPH026382A - Apparatus for pulling up single crystal - Google Patents

Abstract

PURPOSE:To make it possible to efficiently obtain a single crystal having a low oxygen concentration and homogeneous resistivity by providing a sub-heater above an inner crucible in an apparatus for pulling up the single crystal according to a double crucible method combined with a magnetostatic field applied Czochralski (MCZ) method. CONSTITUTION:A double crucible consisting of an inner crucible 22 and an outer crucible 21 and a heater 34 are provided in the interior of a vacuum vessel 27 and a sub-heater 34 for heating the inner crucible 22 is provided above the inner crucible 22. A magnet 11 is arranged on the outside of the vacuum vessel 27 and a strong static magnetic field is applied to a silicon melt 23 in the double crucible to pull up and grow a single crystal 23' while suppressing stirring of the silicon melt 23 by thermal convection, pull up and grow the single crystal 23'. Thereby, the upper part of the inner crucible 22 is heated by the subheater 34 to conduct the heat to the lower part of the inner crucible 22 and heat the silicon melt 23. As a result, a suitable temperature difference is produced in the inner radial direction of the silicon melt 23 in the inner crucible 22 and a polycrystal is hardly deposited even if the pulling up rate is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION - f-1 The present invention relates to a single crystal pulling apparatus for producing silicon single crystals, germanium single crystals, etc.

The double crucible method is a method for pulling a single crystal using a crucible with a double structure consisting of an inner crucible and an outer crucible. Dopanes 1 to 1 are added to the inner crucible, and the dopant, which increases in concentration according to the segregation coefficient, is filled with the melt from the outer crucible to pull up the crystals. Since the amount of dopant in the inner crucible is kept constant, it is possible to produce 1q of crystals with uniform resistivity. However, when the double lucking method is applied to the normal CZ (pulling) method, the oxygen concentration is 20X10”/cm3 <ASTM
2179 and below), which exceeds the normally used oxygen concentration (5 to 18 x 1017/clI3), which has been a problem. See Figure 6. However, in Fig. 6, the A region is the control range of oxygen 11 degrees when the single crucible method is applied to the CZ method, and the B region is the oxygen i1! degree control range when the double crucible method is applied to the MCZ method. C shows the degree of control.

MCZ method is Magnct+c Field App
It is an abbreviation for licdCzocbralsky Method. In the MCZ method, a strong static magnetic field is applied to the melt (e.g. silicon melt) when pulling a single crystal using the CZ (pulling) method.This static magnetic field suppresses stirring of the silicon melt due to thermal convection. Then, crystal growth is performed in a thermally J3 and chemically stable state.

This MCZ method includes a method of applying a horizontal magnetic field and a method of applying a vertical magnetic field. According to the MCZ method, it is easy to control the oxygen concentration, and it is difficult to control the oxygen concentration with the normal CZ method.
It is possible to form a crystalline structure with a low oxygen concentration of 7 cm3 of IQ atoms.

By combining the two-handed crucible method and the MCZ method, a method has been proposed that takes advantage of the advantages of the two methods and produces single crystals with low oxygen concentration and uniform resistivity6. In the MCZ method (horizontal magnetic culm), for example, the (!I! rectangular convection of the silicon melt is suppressed. Therefore, the heat exchange of the silicon solution is mainly performed in the horizontal direction, Compared to the normal CZ method, the temperature difference in the radial direction of the peritubo is smaller.

When the MCZ method and the two-hand crucible method are combined, this problem of temperature difference in the radial direction cannot be ignored. In other words, there is heat in the inner crucible! ! ! The temperature difference is much smaller than in the case of the MCZ method alone (the thermal response is also worse). For this reason, polycrystals tend to precipitate from the inner crucible during crystal pulling, causing problems with the quality of the 111 crystals obtained.Also, as the pulling speed increases, polycrystals tend to precipitate even more, so the pulling speed must be kept low. Unfortunately, it was not possible to increase the production efficiency of single crystals.

In view of the problems of chemical formula 11 pressure, it is an object of the present invention to provide a single crystal pulling apparatus that can efficiently obtain a single crystal having a low oxygen concentration and a uniform resistivity.

1肚台11 To achieve the above-mentioned object, this Brahma gist is a single crystal thorn device as set forth in the claims.

The single crystal pulling apparatus of the present invention is equipped with a single crystal pulling apparatus equipped with two crucibles consisting of an inner crucible and an outer crucible, and a heater for heating the single crystal raw material in the two outer crucibles. A magnet is provided on the outside of the small crucible, and the 41 crystals are pulled up in the static magnetic field formed by this magnet, and a sub-heater is provided above the inner crucible to heat the inner crucible. In addition, in the single crystal pulling apparatus described above, the heater and the rib heater may not be provided separately but may be configured as one. In this case, the integrated heater directly heats not only the outer crucible but also the inner crucible.

A superconducting magnet may be used as the magnet for generating the static magnetic field. Further, the static Ilu field may be either a transverse magnetic field or a longitudinal magnetic field.

As an example, the case of manufacturing and covering single crystal silicon will be explained.

The E part of the inner crucible 22 is heated to J by the leave heater 34. This heat is transmitted to the lower part of the inner crucible 22 and heats the molten silicon 23 near the inner crucible. Therefore, there is an appropriate temperature difference between the molten silicon 23 in the crucible and the inner diameter of the crucible. For this reason, the b polycrystals even precipitate by increasing the pulling speed.

Similarly, when the heater and sub-heater are integrated, the upper part of the inner crucible 22 is heated, the heat is transmitted to the lower part of the inner crucible 22, and the molten silicon 23 is heated.

Therefore, the molten silicon 23 in the crucible has an appropriate temperature difference in the inner diameter direction of the inner crucible. For this reason, it becomes difficult for b polycrystals to precipitate by increasing the bow speed.

The sub-heater can be moved up and down according to the movement of the crucible during lifting, making it right-handed.

Embodiments of the single crystal pulling apparatus according to the present invention will now be described with reference to the drawings.

The single IFi crystal pulling device 10 moves the magnet 11 to the right. The magnet 11 is configured to form a static magnetic field and pull a single crystal of a semiconductor such as silicon in the static magnetic field. As the magnet 11, it is also possible to use superconducting magnets 1 to 1.

The direction of the magnetic field may be either a horizontal or vertical magnetic field, but normally there is a reduced capacity inside the 3° magnet 11 that performs pulling in a horizontal field. 1. A pump system for setting the inside of the container 28 to a predetermined atmosphere is connected to the reduced pressure container 27, but this is omitted in the drawing.

An inner crucible 22 and an outer crucible 2 are placed in the medium heat section of the reduced pressure container 27.
A 2-ton crucible consisting of 1 is set up at -C.

Around the crucible, there is
3) A heater 24 is installed for heating 1J.
be .

A heat insulating ladle 29 is provided on the outside of the heater 24 (19 pieces).

A sub-heater 34 for heating the inner crucible is provided above the inner crucible. The inner crucible is heated by the rotor heater 34, and this heat heats the molten silicon 23 in the vicinity of the inner crucible. Therefore, the molten silicon 23 in the crucible
Wait for an appropriate temperature difference in the inner diameter direction of the inner crucible.

The shape of the sub-heater is not limited to the shape shown in FIG. 1, as long as it can heat the upper part of the inner crucible. For example, it is also possible to wind Kanthal 49103 into a coil and use the Iζ subheater 134. This heater is made of an insulator and is connected to the container via the lζ arm 102 (see Fig. 4).As shown in Fig. 5, the 2[n cylindrical heater 202.2
03 may be used to form the heater 234.3. The 1-knob heater follows the movement of the crucible during bowing.
If it is made movable downward, it will be the second edition.

By adjusting the output and shape of the sub heater 34 and the distance between the rib heater 34 and the inner crucible 22, the temperature distribution of the molten silicon can be made into a desired distribution. l The inner crucible 22 and the outer crucible 21 can be made of a material such as quartz glass or carbon.

In addition, at the bottom of the inner crucible, for example, a straight line [6 mm, length 1
Install a 50 mm tube to connect the inner crucible and outer crucible. However, it is not shown in the drawing for simplicity.

Even if the upper part of the inner crucible is covered with a material (such as carbon) that has a good heat conductivity9 to make it easier to absorb radiation from the heater,
:stomach.

A single crystal lifting device 25 is provided above the two small crucibles. Further, a crucible rotation support device 26 is installed below the two-wheeled crucible.

Next, referring to FIG. 2, another embodiment of the present invention will be briefly described.

In the single crystal pulling apparatus 100, the heater 24 and the sub-heater 34 in the above-mentioned embodiment are integrated into the heater 12.
4 has been formed.

The upper part of the heater 124 is close to the upper edge of the inner crucible,
The inner crucible 22 receives and takes away heat from its vicinity. The other configurations are the same as in the previous embodiment.

As an example, FIG. 1.2 schematically shows a state in which a single crystal silicon 23' is lifted up by a single crystal lifting device 25.

Next, an experimental example in which single-crystal silicon was manufactured using the single-crystal thorn device α of the present invention will be described.

20 kg of polysilicon was packed into the inner and outer crucibles of the single crystal pulling apparatus shown in FIG. 1, and phosphorus (P) was added as a dopant. Static magnetic field of transverse magnetic field 0.3
Multiply T (Tesla) and draw a 5-inch crystal in the (111) direction.

The silicon single crystal is pulled at an average pulling speed a 1 , 0
The speed was 81'am/min. This is 35% higher than the 62-fold crucible pulling speed of 0°8 mm/min in the normal MCZ method.

Moreover, the resistivity distribution of the pulled crystal was as shown in FIG. 2, and was almost constant and good.

Furthermore, the oxygen concentration is 1QxlQ in the entire area from Imbok 1
am'''3 or less, and 6Wi by the normal 2...crucible method
mlQ 25
According to TM F1'21-79.

The single crystal pulling device of the present invention uses NTD (neutron irradiation)
-8i method can be used as an alternative.

The invention is not limited to the embodiments described above. For example, the configuration of the sub-heater and the heater connected to the sub-heater of the present invention can also be applied to a single crystal pulling apparatus using a normal double crucible method (07 method).

111 Circle 1 According to the single crystal pulling apparatus of the present invention, it is possible to efficiently obtain a single crystal with low oxygen degree and uniform resistivity. Furthermore, the pulling speed can be significantly increased.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing an embodiment of the single crystal pulling apparatus according to the present invention, FIG. 2 is a conceptual diagram showing another embodiment of the single crystal pulling apparatus according to the present invention, and FIG. A graph showing the resistivity of Ti crystal silicon produced by the single crystal pulling apparatus shown in Figure 1 and a normal apparatus, Figures 4 and 5 are diagrams showing examples of sub-heaters, and Figure 6 is a graph showing the single-crucible method in addition to the C7 method. The control range (area △) of oxygen concentration when applying 2... and oxygen concentration when applying crucible method to MCZ method
It is a graph which shows the control range (area B) of. 10...Two single crystal pulling devices...Insulating material 21...Outer crucible 22...Inner crucible 23...Melted silicon 23'...Single crystal silicon 24.124...Heater 25. ... Single crystal lifting device 26 ... Crucible rotation support device 27 ... Decompression container 28 ... Container chamber 23, 134, 234 ... Sub-heater Fig. 1 and b Fig. 3 Solidification ↑ Fig. 2 Fig. Diagram

Claims (1)

[Claims] In a single crystal pulling apparatus equipped with a double crucible consisting of an inner crucible and an outer crucible, and a heater for heating the single crystal raw material in the double crucible, a magnet is provided outside the double crucible, and the magnet forms 1. A single crystal pulling apparatus, characterized in that the single crystal is pulled in a static magnetic field, and the inner crucible is further heated by providing a sub-heater above the inner crucible.