JPH0967186A - Apparatus for producing signal crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the quality of a signal crystal to be produced and to reduce a unit requirement for electric power by providing the subject apparatus with a protector for shielding SiO so as to cover the inside surface of a chamber and the outer peripheral surface of a cooling cylinder apart prescribed distances both from the inside surface and the outer peripheral surface, thereby lessening the change in the emissivity of the inside surface and the outer peripheral surface with lapse of time. SOLUTION: The emissivity of the inside surface of the chamber and the outer peripheral surface of the cooling cylinder is <=0.2 and the spacing between these surface and the protector is 1 to 30mm. The protector consists of a carbon composite material. Fig. illustrates the sectional view of the apparatus for producing a signal crystal. A crucible 2 for holding a silicon molten metal, a heater 3, a heat insulating cylinder 4 and a spill tray 5 are arranged in the chamber 1. The cooling cylinder 6 is disposed by directing its axial central direction toward a perpendicular direction and the silicon signal crystal is pulled up through the cooling cylinder 6 by a pulling up device. The inside surface of the chamber 1 and the outer peripheral surface of the cooling cylinder 6 are provided with the projector 7 and an upper ring 8 is installed above the heat insulating cylinder 4. The protector 7 has a cylindrical part 7a and a ring 9 is fixed to the cooling cylinder 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a single crystal such as silicon by a pulling method, and more particularly to an apparatus for producing a single crystal through a cooling cylinder.

[0002]

2. Description of the Related Art There is an apparatus for pulling a single crystal from a molten metal in a crucible surrounded by a chamber through a cooling cylinder as an apparatus for producing a single crystal by a pulling method. (For example, JP-A-57-205397 and JP-A-2-97.
JP-A-6-293587 discloses that the apparent emissivity of the chamber is increased and the single crystal being pulled is cooled by forming irregularities on the inner surface of the chamber.

On the contrary, Japanese Patent Application Laid-Open No. 59-199598 discloses that a silver plating layer is formed on the inner surface of the chamber to form a heat ray reflecting layer.

Japanese Patent Publication No. 57-40119 discloses that a cover made of infrared reflecting metal is provided so as to cover the upper surface of the molten metal in the crucible.

Incidentally, Japanese Patent Application Laid-Open No. 2-97479 discloses that
It is described that unevenness is formed on the inner surface of the cooling cylinder to absorb radiant heat from the single crystal and accelerate cooling of the single crystal.

[0006]

In order to prevent the temperature inside the chamber from rising unnecessarily, it is preferable to reduce the emissivity of the outer peripheral surface of the cooling cylinder and the inner surface of the chamber.
For this reason, as described in JP-A-59-199598, a silver reflective layer is formed on these surfaces.

However, in the silicon single crystal manufacturing apparatus, these surfaces are corroded by the SiO gas evaporated from the molten metal in the crucible, and the emissivity of these surfaces increases with time. As a result, the quality of the obtained single crystal changes with time.

An object of the present invention is to provide an apparatus for producing a single crystal in which the emissivity of the inner surface of the chamber and the outer peripheral surface of the cooling cylinder is small with time, and the quality of the produced single crystal is extremely small.

[0009]

A single crystal manufacturing apparatus of the present invention comprises a crucible for holding a molten metal, a chamber surrounding the crucible,
In a single crystal production apparatus equipped with a cooling cylinder vertically extending above the crucible and a pulling device for pulling a single crystal into a columnar shape from the molten metal in the crucible through the cooling cylinder, the inner surface of the chamber and the cooling It is characterized in that a protective body for the SiO shield is provided so as to cover the outer peripheral surface of the cylinder and to be separated from the inner surface and the outer peripheral surface by a predetermined distance.

In the apparatus for producing a single crystal of the present invention, the emissivity of the inner surface of the chamber and the outer peripheral surface of the cooling cylinder is 0.2 or less, and the distance between the inner surface and outer peripheral surface and the protective body is 1 to 30 mm. It is preferable that the protector is made of a carbon composite material.

According to the single crystal manufacturing apparatus of the present invention,
Attack of SiO on the inner surface of the chamber and the outer peripheral surface of the cooling cylinder is prevented, and the emissivity of these surfaces is prevented from increasing with time.

[0012]

1 is a sectional view of a single crystal manufacturing apparatus according to an embodiment, in which a crucible 2 for holding a molten silicon is arranged in the center of a chamber 1, and a heater 3 is provided so as to surround the outer periphery thereof. It is arranged. A heat insulating cylinder 4 surrounds the outer circumference of the heater 3. A spill tray 5 is arranged at the bottom of the chamber 1.

A cooling cylinder (a water cooling cylinder in this embodiment) 6 is provided penetrating the top of the chamber 1 with the axial direction of the cylinder being the vertical direction. A silicon single crystal is pulled through the cooling cylinder 6 by a pulling device (not shown).

A protective member 7 is provided so as to cover the inner surface of the chamber 1 and the outer peripheral surface of the cooling cylinder 6 and at a slight distance (preferably 1 to 30 mm) from these surfaces. In this embodiment, the upper ring 8 is installed on the upper surface of the heat insulating cylinder 4, and the outer peripheral edge of the protector 7 is supported by the upper ring 8.

The protector 7 is a cylindrical portion 7 surrounding the cooling cylinder 6.
a. A ring 9 is fixed to the lower end of the cooling cylinder 6 by bolting or the like, and the lower end of the cylindrical portion 7a of the protector 7 is supported by the ring 9. A claw 9a protruding from the ring 9 engages with the outer peripheral edge of the lower end of the cylinder 7a, and a spacer (not shown) is arranged between the cooling cylinder 6 and the protector 7.

As the protector 7, a carbon composite material having good heat resistance and corrosion resistance is suitable. Although not shown, the protector 7 is provided with a viewing window and a diameter control window.

In this embodiment, the emissivity of the inner surface of the chamber 1 and the outer peripheral surface of the cooling cylinder 6 is 0.15, and the emissivity of the inner peripheral surface of the cooling cylinder 6 and the protector 7 is 0.8. Has become.

When a silicon single crystal is pulled up by such a single crystal manufacturing apparatus, attack of SiO on the inner surface of the chamber 1 and the outer peripheral surface of the cooling cylinder 6 is prevented by the protector 7, so that the inner surface of the chamber and the outer circumference of the cooling cylinder are prevented. The emissivity of the surface changes little over time. As a result, the variation of the quality of the obtained silicon single crystal becomes extremely small. Moreover, the heat loss is also reduced by the protector 7.

As a result of various experiments, according to the present embodiment, the occurrence rate of crystal defects can be reduced to 1/3 or less as compared with the conventional example (apparatus without the protector 7), and the unit consumption of electric power can be reduced. I was able to save about 20%.

[0020]

As described above, according to the apparatus for producing a single crystal of the present invention, the emissivity of the inner surface of the chamber and the outer peripheral surface of the cooling cylinder is significantly reduced with time, and the quality of the produced single crystal is stable. . Also, the power consumption rate can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of an apparatus according to an embodiment.

[Explanation of symbols]

 1 Chamber 2 Crucible 3 Heater 6 Cooling Tube 7 Protective Body

Claims (2)

[Claims] 1. A crucible for holding a molten metal, a chamber surrounding the crucible, a cooling cylinder vertically extending above the crucible, and a single crystal columnarly pulled from the molten metal in the crucible through the cooling cylinder. In a single crystal manufacturing apparatus equipped with a pulling device, a protective body for SiO shield is provided so as to cover the inner surface of the chamber and the outer peripheral surface of the cooling cylinder, and to be separated from the inner surface and the outer peripheral surface by a predetermined distance. An apparatus for producing a single crystal. 2. The emissivity of the inner surface of the chamber and the outer peripheral surface of the cooling cylinder is 0.2 or less, and the interval between the inner surface and the outer peripheral surface and the protector is 1 to 30 mm.
And the protective body is made of a carbon composite material.