JP2619986B2 - Hot water surface temperature measuring device for single crystal pulling device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the temperature of a molten metal used in a single crystal growing apparatus by a pulling method.

[0002]

2. Description of the Related Art FIG. 3 shows a schematic configuration of a single crystal growing apparatus using a pulling method.

A quartz crucible 12 is fitted in a graphite crucible 10. The graphite crucible 10 is surrounded by a heater 14,
The heater 14 is further surrounded by a graphite insulation 16.
These components are arranged in the main chamber 18 with their respective central axes concentric. A polycrystalline metal piece is put in the quartz crucible 12, and power is supplied to the heater 14. The molten metal surface 22 of the melt 20
Temperature affects the crystal growth rate and crystal disorder,
It is necessary to detect the temperature of the molten metal surface 22 and adjust the power supplied to the heater 14. Therefore, conventionally, a viewing window 24 is provided at the shoulder of the main chamber 18, and the radiation thermometer 26 is fixed to the viewing window 24.

[0004]

However, the radiated light from the inner wall of the heated quartz crucible 12 is reflected by the molten metal surface 22 to be incident on the radiation thermometer 26, or the radiated light from other than the molten metal surface 22 is radiated by the radiation temperature. Since the light enters the total 26, the temperature of the molten metal surface 22 could not be measured accurately. This measurement error could exceed 10 ° C. The degree of the influence of the radiated light on the detection temperature depends on the level of the quartz crucible 12 which can be raised and lowered with respect to the heater 14, the amount of the melt 20 in the quartz crucible 12,
Since it differs depending on the temperature of the melt 20 and the power supplied to the heater 14, it is difficult to accurately correct the temperature detected by the radiation thermometer 26.

[0005] A diameter of 3 m is particularly difficult to automatically control for growing single crystals.
In order to increase the success rate of growing a drawn portion having a length of m and a length of about 10 cm, which is called necking extending from a seed crystal, it is required to accurately measure the temperature of the molten metal surface 22. In the growth of the narrowed portion, there are many cases where the crystal is melted or the diameter rapidly increases, so that it is difficult to control the diameter stably or to continue the growing of the narrowed portion. The rate was usually 50% or less, but it is considered that the above measurement error of the surface temperature has greatly affected the cause.

In view of this, there has been proposed a configuration in which a radiation thermometer is arranged so that the optical axis is directed from directly above the melt to directly below the melt (Japanese Patent Laid-Open No. 1-126295).

However, since the radiation thermometer is disposed in the chamber, there is a problem that the entire radiation thermometer receives radiant heat and the life of the radiation thermometer is shortened. Further, when the radiation thermometer is to be arranged on the ceiling outside the chamber, a sufficient arrangement space cannot be obtained due to the relationship with the pulling wire winding and rotating device.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to prevent the radiation thermometer from shortening its life due to radiant heat, and to secure a sufficient space for disposing the radiation thermometer.
Moreover, it is an object of the present invention to provide a temperature measuring apparatus for a single crystal pulling apparatus, which can accurately measure the temperature of the molten metal.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, in the apparatus for measuring the temperature of a molten metal for a single crystal pulling apparatus according to the present invention, the temperature rises substantially vertically upward from the melt surface in a pull chamber. A reflector, preferably a total reflection prism, which is arranged so that the emitted light is incident thereon, and is arranged outside the pull chamber and on the side of the pull chamber, so that the emitted light totally reflected by the reflector is incident. A radiation thermometer. The pull chamber is a cylindrical member (arbitrarily shaped in cross section) having a diameter smaller than that of the main chamber, following the upper end of the main chamber accommodating the crucible containing the melt.

In this apparatus, the temperature of the melt surface is measured by irradiating radiant light, which travels substantially vertically upward from the melt surface, to a radiation thermometer. Is hardly incident on the radiation thermometer, and the temperature of the melt surface can be measured more accurately. As a result, it is possible to increase the success rate of growing a drawn portion having a diameter of about 3 mm and a length of about 10 cm, in which automatic control of growing a single crystal is particularly difficult.

Further, since the radiation thermometer is arranged outside the pull chamber, it is possible to prevent the life of the radiation thermometer from being shortened by radiant heat.

In addition, since the radiation thermometer is arranged on the side of the pull chamber, a sufficient space for disposing the radiation thermometer can be secured.

If a limiting cylinder for limiting the solid angle of incidence is attached to the radiation incident surface of the reflector, the temperature of the melt surface can be measured more accurately.

[0014]

FIG. 1 shows a schematic structure of a single crystal growing apparatus by a pulling method. The same components as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

A radiation thermometer 30 is mounted on the upper portion of the small-diameter pull chamber 28 following the upper end of the shoulder of the main chamber 18. FIG. 2 shows the details of this mounting state.
In the figure, the central axis C is the central axis of the pull chamber 28.

The pull chamber 28 has a double structure. A hole is formed in the pull chamber 28, and one end of the outer cylinder 32 is fixed to the hole. An inner cylinder 34 is fitted in the outer cylinder 32. A flange 36 is fixed to one end of the inner cylinder 34, and the flange 36 and the outer cylinder 32
A cover ring 40 is fixed to the flange 36 with screws 42 so as to cover the seal ring 38. On the end face of the flange 36,
A base plate 46 is fixed via an intermediate plate 44. The radiation thermometer 30 is fixed to the base plate 46 with screws 48. A bracket 50 is fixed to the base plate 46 with screws 52.
0 supports the objective lens side cylinder of the radiation thermometer 30. In front of the radiation thermometer 30, the base plate 4
A bracket 54 is fixed to the bracket 6, and a mirror 58 is fixed to the bracket 54 via a holding plate 56.

On the other hand, a lid 60 having a radiation light passing hole formed at the center is fixed to the inner end of the inner cylinder 34 inside the pull chamber 28 with a screw 62, and a radiation light passing hole is formed on the front surface of the lid 60. One surface of the L-shaped holding plate 64 on which is formed is fixed,
The total reflection prism 66 is fixed to the holding plate 64. On the other surface of the holding plate 64, a limiting cylinder 68 is provided in parallel with the central axis C.
Is fixed at one end. Therefore, the center axis of the restriction cylinder 68 is perpendicular to the molten metal surface 22, as shown in FIG.

In the above configuration, the radiated light from the molten metal surface 22 passes through the inside of the restricting cylinder 68, is totally reflected by the total reflection prism 66, is further reflected by the mirror 58, and is incident on the radiation thermometer 30. Is measured.

According to such a configuration, since the radiation light from the inner wall surface of the quartz crucible 12 does not enter the radiation thermometer 30, the temperature of the molten metal surface 22 can be measured more accurately.
The crystal growth diameter can be controlled more accurately. As a result, the success rate of growing a drawn portion having a diameter of about 3 mm and a length of about 10 cm, which is particularly difficult to automatically control for growing a single crystal, could be increased to 90% or more.

In the above embodiment, the case where the temperature of the molten metal surface 22 is more accurately measured by sufficiently restricting the incident light angle using the restriction cylinder 68 has been described.
8 may be removed. In this case, if the inner diameter of the inner cylinder 34 is reduced, obliquely incident radiation light from other than the molten metal surface 22 is absorbed by the black inner wall surface of the inner cylinder 34, and the effect of the present invention is obtained. However, since the amount of incident light decreases, the amplification factor of the detection signal must be increased.
The measurement accuracy is lower than when the restriction cylinder 68 is provided.

Although the mirror 58 of the above embodiment is used to make the whole apparatus compact, the present invention
A configuration in which the total reflection light from the total reflection prism 66 is directly guided to the radiation thermometer 30 may be employed.

Further, a mirror may be used instead of the total reflection prism 66. However, in this case, such a problem does not occur because a thermal stress acts between the two on the basis of the difference between the coefficient of thermal expansion of the deposited metal film such as silver and the coefficient of thermal expansion of the glass substrate, and the metal film is deteriorated. The total reflection prism 66 is more preferable.

[0023]

As described above, according to the apparatus for measuring the surface temperature of a single crystal pulling apparatus according to the present invention, the radiated light propagating substantially vertically upward from the surface of the melt is incident on the radiation thermometer. Since the temperature of the liquid surface is measured, the light emitted from the inner wall of the crucible containing the melt hardly enters the radiation thermometer, and the temperature of the melt surface can be measured more accurately. Since the radiation thermometer is located at the bottom, it is possible to prevent the life of the radiation thermometer from being shortened by radiant heat.Moreover, since the radiation thermometer is placed on the side of the pull chamber, it is necessary to secure a sufficient space for the radiation thermometer. This has the effect that it can be performed.

Further, if a restricting cylinder for restricting the solid angle of incidence is attached to the radiation incident surface of the reflector disposed in the pull chamber, the temperature of the melt surface can be measured more accurately. It works.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a single crystal growing apparatus by a pulling method, to which a radiation thermometer is attached.

FIG. 2 is a partially sectional side view showing details of a radiation thermometer in an attached state.

FIG. 3 is a schematic configuration diagram of a single crystal growing apparatus by a pulling method, to which a radiation thermometer is attached.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Graphite crucible 12 Quartz crucible 14 Heater 16 Graphite insulation material 18 Main chamber 20 Melt 22 Hot surface 26, 30 Radiation thermometer 28 Pull chamber 38 Seal ring 58 Mirror 66 Total reflection prism 68 Restriction cylinder

Claims (2)

(57) [Claims] 1. In a pull chamber (28), which is a cylindrical body having a smaller diameter than the main chamber, following the upper end of a main chamber (18) accommodating a crucible (12) containing a melt, the melt surface ( 22) a reflector (66) arranged so as to receive the radiated light propagating substantially vertically upward from the reflector, and the radiated light totally reflected by the reflector is incident outside the pull chamber and at the side of the pull chamber. And a radiation thermometer (30) arranged as described above. 2. A radiation incident surface of the reflector (66),
2. The apparatus according to claim 1, further comprising a restriction cylinder for restricting an incident solid angle.