JP2939715B2 - Single crystal manufacturing equipment - 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 producing a single crystal, and more particularly to GaAs containing elements such as As and P having a high vapor pressure.
The present invention relates to an apparatus useful for producing a compound semiconductor single crystal such as s, InP and the like.

[0002]

2. Description of the Related Art As one method of manufacturing a single crystal of a compound semiconductor such as GaAs, a pulling method is known in which a seed crystal is brought into contact with a raw material melt and the seed crystal is gradually pulled to grow the single crystal. Have been. For example, a single crystal manufacturing apparatus used to carry out this manufacturing method is provided with a viewing window made of a quartz rod for observing the inside of a furnace at the start of crystal growth or during crystal growth. However, with the progress of crystal growth, a high vapor pressure component element such as As adheres to the viewing window and the window becomes cloudy, which makes it difficult to observe the inside of the furnace.

Therefore, conventionally, high-pressure gas has been blown against the end face of the inside of the furnace of the viewing window (Japanese Patent Laid-Open Publication No.
-140055), heating with a heater (described in JP-A-4-59690), and replacing a plurality of lenses for protecting the end face during crystal growth. Do (actual Kaihei 1-11)
No. 9063) has been proposed to prevent As or the like from adhering to the end face.

[0004]

However, when the present inventor studied the above prior art, it became clear that there were the following problems. That is, in the apparatus described in JP-A-50-140055, not only the convection of the gas in the furnace is disturbed by the sprayed gas, but also the heat balance and the like are disrupted by the adiabatic expansion of the sprayed high-pressure gas, The grown crystal is easily polycrystallized. Further, in the apparatus described in JP-A-4-59690, the upper part of the furnace is heated by a heater for heating the inner end face of the viewing window, although the upper part of the furnace is preferably cooled. As a result, the heat balance is lost and the grown crystal is likely to be polycrystallized. In addition, the actual practice 1-11-1906
In the device described in Japanese Patent Laid-Open Publication No. 3 (1994), the configuration of the device becomes complicated due to the rotation mechanism of the plurality of protective lenses, and the cost of the device itself and the cost of maintenance and the like increase.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is intended to prevent the observation window from fogging due to the attachment of high vapor pressure components without disturbing the heat balance in the furnace. An object of the present invention is to provide an improved single crystal manufacturing apparatus.

[0006]

In a crystal growth apparatus having a viewing window for observing the inside of a heating furnace, the viewing window includes a transparent rod projecting into the furnace, and a protruding portion of the rod in the furnace. And a cylindrical body surrounding the side surface of the rod and protruding from an inner end surface of the rod body, wherein the cylindrical body is in contact with a low-temperature portion caused by cooling in the heating furnace. With this configuration, the gas component in the furnace is cooled and solidified by the barrel of the viewing window and adheres to the barrel, so that the gas component adheres to the end face inside the furnace of the transparent rod for fluoroscopy. Can be prevented, the visibility in the furnace is secured from the start to the end of crystal growth, and the crystal growth process can be observed.

[0007] In the present invention, the thermal conductivity of the cylindrical body is preferably 10 Wm ^-1 K ^-1 or more. Further, the length of the cylindrical body is preferably longer than a length at which gas components in the furnace are solidified and sufficiently attached to the same cylindrical body, and shorter than a length that does not narrow the field of view. Further, the cylinder may be made of stainless steel or molybdenum.

[0008]

FIG. 1 is a diagram schematically showing an example of a single crystal manufacturing apparatus according to the present invention. As shown in FIG. 1, the single crystal manufacturing apparatus 1 includes a liquid-sealed Czochralski (L
A heating furnace for pulling a single crystal by the EC) method, 2 is a high-pressure vessel having a water-cooled jacket structure, 3 is a viewing window for observing the inside of the high-pressure vessel from the outside, and 4 is a water-cooled reflector that cools the ceiling of the high-pressure vessel. 5, a crucible for holding the raw material melt 6, 7 a liquid sealant such as B ₂ O ₃ , 8 a seed crystal, 9 a grown single crystal, 10 a grown crystal 9 supporting the seed crystal 8
, A crucible shaft for supporting the crucible 5, a heater 12, and a heat retaining member 13. In the single crystal manufacturing apparatus 1, the viewing window 3 is made of, for example, a transparent quartz rod 30 and a protective cover 31 surrounding the quartz rod 30.

The quartz rod 30 is a transparent rod, and penetrates through the ceiling of the high-pressure vessel 2 and the water-cooled reflector section 4 and protrudes into the vessel 2. And this quartz rod 30
From the outside, for example, a field of view as shown by a two-dot chain line in FIG. 1 is obtained, and a state in which the single crystal 9 grows can be observed.
The joint between the quartz rod 30 and the high-pressure vessel 2 has a hermetically sealed structure.

As shown in FIG. 2, the protective cover 31 has a cover body 31a surrounding a side surface 30b of a portion protruding into the furnace 2 except for an end surface 30a inside the furnace of the quartz rod 30.
And a flange portion 31b provided at an upper edge of the cover main body 31a.

Although the cover body 31a is not particularly limited,
For example, it is a cylindrical body formed so that its cross section has a circular shape. The upper end of the cover body 31a is a water-cooled reflector section 4.
The reflector 40 is inclined at an angle (for example, 23 ° in the example of FIG. 2) along the inclination of the portion where the viewing window 3 is provided. The protective cover 31 is joined to the reflector 40 via the flange portion 31b, and is integrated with the reflector 40.

Since the reflector 40 is cooled by the water flowing in the cooling pipe 41, the cover body 31a is also cooled. When a gas component in the high-pressure vessel 2 comes into contact with the cover body 31a during crystal growth, the gas component is cooled and solidified, and adheres to the cover body 31a. This prevents the gas component from solidifying and adhering to the end surface 30a inside the furnace of the quartz rod, and prevents the end surface 30a from fogging. Therefore, in order to enhance the cooling effect, the protective cover 31 is made of a material such as a metal having a high thermal conductivity of 10 Wm ^-1 K ^-1 or more, such as a metal such as stainless steel (thermal conductivity: 15 K at 400 K). １８18 Wm ⁻¹ K ⁻¹ ) and molybdenum (thermal conductivity: 134 Wm ⁻¹ K ^{−1 at} 400 K). Since these stainless steels and molybdenum have a high melting point, they have the advantage of not contaminating the grown crystals and the atmosphere in the furnace.

Although not particularly limited, for example, the lower end of the cover main body 31a is made in consideration of the degree of inclination of the quartz rod 30 attached to the high-pressure vessel 2, the wide field of view, the flow of gas components in the high-pressure vessel 2, and the like. Therefore, it is inclined at an appropriate angle (for example, 14 ° in the example of FIG. 2).

The length of the cover body 31a is not less than the length at which the gas component in contact with the cover body 31a is solidified and sufficiently adhered, and not more than the length which does not narrow the field of view. Specifically, although not particularly limited, the protruding length d (see FIG. 2) from the end surface 30a inside the furnace of the quartz rod 30 to the farthest point of the lower edge of the cover main body 31a is 50 mm. According to an experiment conducted by the present inventors, a sufficiently practical effect was obtained when the protrusion length d was up to about 150 mm. Thus, the cover body 31a is
Projecting beyond the end face 30a of the end face 3a.
Oa is less likely to be directly exposed to the gas components in the furnace, and together with the cooling effect of the protective cover 31, it is possible to efficiently prevent the gas components from solidifying and adhering to the end face 30a. In addition,
The protruding length d is appropriately selected depending on the outer diameter of the quartz rod 30 and the distance to an object to be observed.

As described above, the quartz rod 3 of the viewing window 3
The gas component in the high-pressure vessel 2 is cooled and solidified by the protective cover 31, and adheres to the protective cover 31 by surrounding and protecting the 0 with the protective cover 31 cooled by the reflector 40. Therefore, the quartz rod 30 for see-through is used.
Since the end face 30a on the inside of the furnace is not fogged due to the adhesion of the gas component, the inside of the high-pressure vessel 2 can be observed from the outside through the viewing window 3 until the grown crystal 9 is separated from the raw material melt 6.

The protective cover 31 is not limited to a material made of stainless steel or molybdenum, but may be made of any material having a good thermal conductivity and a property of not contaminating the grown crystal and the atmosphere in the furnace. It may be manufactured by using.

The design of the protective cover 31 is not limited to that of the above-described embodiment, but can be variously changed. For example, as shown in FIG. 3, the cooling may be performed by winding a cooling pipe 32 around the cover main body 31 a of the protective cover 31 and flowing water or the like. Alternatively, as shown in FIG. 4, a cooling fin 33 may be provided on the cover body 31a to increase the cooling performance.

Further, the heat balance in the furnace and the disturbance of the convection of the gas are somewhat disadvantageous in comparison with the above embodiment,
As shown in FIG. 5, a high-pressure gas outlet 34 is provided below the cover main body 31a to blow gas onto the end face 30a of the quartz rod 30 so that the gas component in the furnace contacts the end face 30a while cooling. May be prevented.

Although the structure of the apparatus is somewhat complicated, as shown in FIG. 6, a cover 35 is provided near the lower end of the cover main body 31a so as to close the opening at the lower end substantially or to some extent. The cover body 35a may be rotatably supported by the cover 36, and the cover 35 may be rotated to open the cover main body 31a only during observation in the furnace.

Further, the present invention is not limited to the production of a GaAs single crystal, but may be applied to the production of other compound semiconductor single crystals such as InP, InAs, and GaSb. In addition to the crystal pulling apparatus of the above embodiment, the present invention can be applied to a single crystal manufacturing apparatus having a viewing window.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS LEC using the single crystal manufacturing apparatus 1 having the above configuration
A specific example in which a GaAs single crystal is manufactured by the method will be described, but the present invention is not limited by the specific example.

In this specific example, the quartz rod 3
0 has an outer diameter of 50 mm and the quartz rod 30 of the cover body 31a.
The protruding length d from the end face 30a of the cover body 3 is 50 mm.
The outer diameter of 1a is 68 mm, the inclination angles of the upper and lower ends of the cover body 31a are 23 ° and 14 °, respectively, and the cover body 31a
Had a thickness of about 0.3 mm. The protective cover 31 was made of stainless steel.

In a pBN crucible 5 having a diameter of 12 inches, 27.0 kg of a GaAs polycrystalline raw material and a liquid sealing material 7 are placed.
B ₂ O ₃ as the raw material and 20 kg of these raw materials and sealant
After heating and melting in an Ar gas atmosphere of / cm ² , while rotating the crystal pulling shaft 10 clockwise at 6 rpm and rotating the crucible shaft 11 counterclockwise at 20 to 30 rpm, the crystal pulling shaft 10 is rotated at 6 rpm. The crucible shaft 11 was raised at a speed of 1.7 mm / h while being raised at a speed of 0.0 to 8.0 mm, and a GaAs single crystal having a diameter of 4 inches and a length of a straight body of 300 mm was grown.

As a result, when the length of the grown crystal 9 is 100 mm, when the crystal length is 200 mm, when the grown crystal 9 is cut off from the raw material melt 6, the crystal 9 can be cut through the viewing window 3 at each time. The shape and the boundary between the crystal 9 and the raw material melt 6 could be confirmed.

The projecting length d of the cover body 31a is set to 1
When the crystal was pulled up under the same growth conditions as in the above specific example, the shape of the crystal and the boundary between the crystal and the raw material melt could always be confirmed through the viewing window 3 until the crystal was separated.

Further, when the protective cover 31 was replaced with a molybdenum cover and the crystal was pulled up under the same growth conditions as in the above embodiment, the crystal shape and the crystal fusion with the raw material were always passed through the viewing window 3 until the crystal was separated. The boundary with the liquid could be confirmed.

As a comparison, when a crystal was grown under the same growth conditions as in the above specific example using a pulling device in which the protective cover 31 was not attached to the viewing window 3, the crystal was grown when the length of the grown crystal was 100 mm. High pressure vessel 2 when the length is 200 mm
I was able to observe the inside, but the illuminance was
1 was about 1/10 that of the case where 1 was attached. Further, when separating the grown crystal from the raw material melt, the high pressure vessel 2
It was impossible to observe inside. The illuminance at the start of crystal growth was the same as the illuminance at the start of crystal growth in the above specific example.

[0028]

According to the present invention, in a crystal growth apparatus having a viewing window for observing the inside of a heating furnace, the viewing window surrounds a transparent rod protruding into the furnace and a side surface of a protruding portion of the rod in the furnace. And a cylindrical body protruding from the inner end surface of the rod body,
Since the cylindrical body is in contact with a low-temperature portion due to cooling in the heating furnace, gas components in the furnace are cooled and solidified by the cylindrical body of the viewing window and adhere to the cylindrical body, and are used for fluoroscopy. Since the gas component can be prevented from adhering to the end face inside the furnace of the transparent rod body, from the start to the end of crystal growth,
The view in the furnace is secured, and the crystal growth process can be observed.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an example of a single crystal manufacturing apparatus according to the present invention.

FIG. 2 is a front view showing an example of a protective cover of the single crystal manufacturing apparatus.

FIG. 3 is a schematic view showing another example of the protective cover.

FIG. 4 is a schematic view showing another example of the protective cover.

FIG. 5 is a schematic view showing another example of the protective cover.

FIG. 6 is a schematic view showing another example of the protective cover.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single crystal manufacturing apparatus 2 High pressure vessel 3 Viewing window 30 Quartz rod (rod) 30a End face 30b Side face 31 Protective cover (tubular body)

Claims (4)

(57) [Claims] 1. A crystal growth apparatus having a viewing window for observing the inside of a heating furnace, wherein the viewing window surrounds a transparent rod protruding into the furnace and a side surface of a protruding portion of the rod in the furnace. And a cylindrical body protruding from the inner end surface of the rod body,
The single crystal manufacturing apparatus, wherein the cylindrical body is in contact with a low temperature portion caused by cooling in the heating furnace. 2. The thermal conductivity of the cylinder is 10 Wm ⁻¹ K ^−1.
2. The apparatus for producing a single crystal according to claim 1, wherein: 3. The length of the cylindrical body is not less than a length at which gas components in the furnace are solidified and sufficiently attached to the same cylindrical body, and not more than a length that does not narrow the field of view. The single crystal production apparatus according to claim 1 or 2, wherein 4. The apparatus for producing a single crystal according to claim 1, wherein the cylindrical body is made of stainless steel or molybdenum.