JPH0948692A - Single crystal production apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an improved single crystal production apparatus effective for preventing the clouding of an inspection window caused by the deposition of a component having high vapor pressure without causing the disturbance of the thermal balance in the furnace, etc. SOLUTION: An inspection window 3 is provided with a protection cover 31 surrounding a quartz rod 30 for inspection. The protection cover 31 is composed of a cover main body 31a surrounding the side face 30b of the rod protruding into the furnace 2 excluding the end face 30a of the quartz rod 30 in the furnace and a flange part 31b formed on the upper edge of the cover main body 31a. The flange part 31b is bonded and integrated to a reflector 40 of a water-cooled reflector part 4 in a high-pressure vessel 2 and the cover main body 31a is cooled by the flange. When the gas component in the high-pressure vessel 2 is brought into contact with the cover main body 31a during the growth of crystal, the gas component is cooled, solidified and deposited on the surface of the cover main body 31a. Accordingly, the solidification and deposition of the gas component on the end face 30a of the quartz rod in the furnace can be prevented to prevent the clouding of the end face of the rod.

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 particularly to GaA containing elements such as As and P having a high vapor pressure.
The present invention relates to a device that is useful when applied to the production of compound semiconductor single crystals such as s and InP.

[0002]

2. Description of the Related Art As one of methods for producing a single crystal of a compound semiconductor such as GaAs, there is known a pulling method in which a seed crystal is brought into contact with a raw material melt and the single crystal is gradually pulled up to grow the single crystal. Has been. For example, a single crystal manufacturing apparatus used for carrying out this manufacturing method is provided with a viewing window made of a quartz rod for observing the inside of the furnace at the start of crystal growth or during the growth. However, as the crystal growth progresses, a high vapor pressure component element such as As adheres to the observation 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 onto the end surface of the viewing window inside the furnace (Japanese Patent Laid-Open No. Sho 50).
No. 140055), heating by a heater (described in Japanese Patent Laid-Open No. 4-59690), and a plurality of lenses for protecting the end face can be exchanged during crystal growth. Yes (Actual Kaihei 1-11
No. 9063), there has been proposed a device for preventing As or the like from adhering to the end face.

[0004]

However, when the present inventor examined the above-mentioned prior art, it became clear that there were the following problems. That is, in the apparatus described in the above-mentioned JP-A-50-140055, not only the convection of the gas in the furnace is disturbed by the blown gas, but also the heat balance and the like are destroyed due to the adiabatic expansion of the blown high-pressure gas, The grown crystal is easily polycrystallized. Further, in the apparatus described in Japanese Patent Application Laid-Open No. 4-59690, although it is preferable that the upper part of the furnace is originally cooled, the upper part of the furnace is heated by the heater that heats the end surface of the peep window inside the furnace. As a result, the heat balance is lost and the grown crystal is easily polycrystallized. Furthermore, actual Kaihei 1-11906
In the device described in Japanese Patent Publication No. 3, the structure of the device is 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.

The present invention has been made to solve the above-mentioned problems, and it is possible to prevent the sight glass from becoming cloudy due to the adhesion of high vapor pressure components without disturbing the heat balance in the furnace. An object is to provide an improved single crystal production apparatus.

[0006]

In a crystal growth apparatus having a peep window for observing the inside of a heating furnace, the peek window is a transparent rod which projects into the furnace, and a protruding portion of the rod in the furnace. A cylindrical body surrounding the side surface of the rod and projecting from the end surface of the rod inside the furnace, the cylindrical body being in contact with a low temperature portion due to cooling in the heating furnace. By doing so, the gas component in the furnace is cooled and solidified by the tube of the sight glass and adheres to the cylinder, so that the gas component adheres to the end surface of the transparent transparent rod body inside the furnace. Since this can be prevented, the visibility in the furnace can be secured and the crystal growth process can be observed from the start to the end of crystal growth.

In the present invention, the thermal conductivity of the cylinder is preferably 10 Wm ^-1 K ^-1 or more. In addition, the length of the cylindrical body is preferably not less than a length at which the gas component in the furnace is solidified and sufficiently adhered to the cylindrical body and is not more than a length that does not narrow the field of view. Further, the tubular body may be made of stainless steel or molybdenum.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of an example of a single crystal manufacturing apparatus according to the present invention. As shown in the figure, the single crystal manufacturing apparatus 1 is a liquid-sealed Czochralski (L
EC is a heating furnace for pulling a single crystal, 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, 4 is a water-cooled reflector for cooling the ceiling of the high-pressure vessel Part, 5 is a crucible for containing the raw material melt 6, 7 is a liquid sealant such as B ₂ O ₃ , 8 is a seed crystal, 9 is a grown single crystal, 10 is a grown crystal while supporting the seed crystal 8.
Is a crystal pulling shaft, 11 is a crucible shaft that supports the crucible 5, 12 is a heater, and 13 is a heat retaining member. 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, which penetrates the ceiling portion of the high-pressure container 2 and the water-cooled reflector portion 4 and projects into the container 2. And this quartz rod 30
When viewed from the outside, a field of view shown by a chain double-dashed line in FIG. 1 can be obtained, and the growth of the single crystal 9 can be observed.
The joint between the quartz rod 30 and the high-pressure container 2 has an airtight sealing structure.

As shown in FIG. 2, the protective cover 31 has a cover body 31a which surrounds the side surface 30b of the portion projecting into the furnace 2 except for the end surface 30a inside the furnace of the quartz rod 30.
And a flange portion 31b provided on the upper edge of the cover body 31a.

The cover body 31a is not particularly limited,
For example, it is a cylindrical body shaped to have a circular cross section. The upper end of the cover body 31a has a water-cooled reflector portion 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 the gas component in the high-pressure container 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 components from solidifying and adhering to the end surface 30a inside the furnace of the quartz rod, and prevents the end surface 30a from becoming cloudy. Therefore, in order to enhance the cooling effect, the protective cover 31 is made of a material such as a metal having a good thermal conductivity of 10 Wm ^-1 K ^-1 or more, such as stainless steel (heat conductivity: 15 -18 Wm ^-1 K ^-1 ) and molybdenum (heat conductivity: 400 K, 134 Wm ^-1 K ^-1 ). Since these stainless steels and molybdenum have high melting points, they have an advantage that they do not contaminate the grown crystal and the atmosphere in the furnace.

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

The length of the cover main body 31a is not less than the length at which the gas component in contact with the cover main body 31a is solidified and sufficiently adhered, and is not more than the length that does not narrow the visual field. Specifically, although not particularly limited, the protruding length d (see FIG. 2) from the end surface 30a of the quartz rod 30 inside the furnace to the furthest point of the lower edge of the cover body 31a is 50 mm. According to an experiment conducted by the present inventor, a sufficiently practicable effect was obtained when the protrusion length d was up to about 150 mm. In this way, the cover main body 31a has the quartz rod 30.
Of the end surface 3a by protruding from the end surface 30a of the
It becomes difficult for 0a to be directly exposed to the gas component in the furnace, and in combination with the cooling effect of the protective cover 31, it is possible to efficiently prevent the gas component from solidifying and adhering to the end surface 30a. In addition,
The protrusion 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
Since 0 is surrounded and protected by the protective cover 31 that is cooled by the reflector 40, the gas component in the high-pressure container 2 is cooled and solidified by the protective cover 31, and adheres to the protective cover 31. Therefore, the transparent quartz rod 30
Since the end face 30a on the inside of the furnace does not become cloudy due to the adhesion of the gas component, the inside of the high-pressure container 2 can be observed from the outside through the observation window 3 until the grown crystal 9 is separated from the raw material melt 6.

The protective cover 31 is not limited to the one made of stainless steel or molybdenum, and any material can be used as long as it has a good thermal conductivity and does not contaminate the grown crystal or the atmosphere in the furnace. You may use and produce.

Further, the protective cover 31 is not limited to the one in the above embodiment, but various design changes are possible. For example, as shown in FIG. 3, a cooling pipe 32 may be wound around the cover body 31a of the protective cover 31 and water or the like may be supplied to cool the cover body 31a. Alternatively, as shown in FIG. 4, cooling fins 33 may be provided on the cover body 31a to improve the cooling performance.

Further, the heat balance in the furnace and the turbulence of gas convection are somewhat disadvantageous as compared with the above embodiment,
As shown in FIG. 5, a high-pressure gas outlet 34 is provided below the cover body 31a to blow gas onto the end surface 30a of the quartz rod 30, thereby cooling and allowing the gas components in the furnace to contact the end surface 30a. May be blocked.

Further, although the structure of the apparatus is somewhat complicated, as shown in FIG. 6, a rotating mechanism for a lid 35 near the lower end of the cover main body 31a that can close the opening of the lower end almost completely or to some extent. The cover body 31a may be rotatably supported by 36, and the lid body 35 may be rotationally moved to open the cover body 31a only when observing the inside of the furnace.

Furthermore, it goes without saying that the present invention is applicable not only to the production of GaAs single crystals, but also to the production of other compound semiconductor single crystals such as InP, InAs and GaSb, and is used in the LEC method. In addition to the crystal pulling apparatus of the above-mentioned embodiment, it can be applied to a single crystal manufacturing apparatus having a viewing window.

[0021]

Example Using the single crystal production apparatus 1 having the above-mentioned configuration, LEC
A specific example of manufacturing a GaAs single crystal by the method will be described, but the present invention is not limited to the specific example.

In this specific example, the quartz rod 3 of the viewing window 3
The outer diameter of 0 is 50 mm, and the quartz rod 30 of the cover body 31a
The protrusion length d from the end face 30a of the cover is 50 mm, and the cover body 3
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.
Had a thickness of about 0.3 mm. The protective cover 31 is made of stainless steel.

In a crucible 5 made of pBN having a diameter of 12 inches, 27.0 kg of GaAs polycrystalline raw material and liquid encapsulating material 7 are used.
B ₂ O ₃ as a 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 at 6 rpm clockwise and rotating the crucible shaft 11 at 20 to 30 rpm counterclockwise, the crystal pulling shaft 10 is rotated at 6 rpm. The crucible shaft 11 was raised at a speed of 0.0 to 8.0 mm and the crucible shaft 11 was raised at a speed of 1.7 mm per hour to grow a GaAs single crystal having a diameter of 4 inches and a straight body length of 300 mm.

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 separated from the raw material melt 6, the crystal 9 is cut through the sight window 3 at each time. The shape and the boundary between the crystal 9 and the raw material melt 6 could be confirmed.

Further, the protrusion length d of the cover body 31a is set to 1
When the crystal was pulled up to 50 mm 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 observation window 3 until the crystal was separated.

Further, when the protective cover 31 was made of molybdenum and the crystal was pulled up under the same growth conditions as in the above specific example, the shape of the crystal and the melting of the raw material with the crystal were always kept through the observation window 3 until the crystal was cut. 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 a protective cover 31 was not attached to the observation window 3, when the length of the grown crystal was 100 mm, the crystal was grown. High pressure container 2 when the length is 200 mm
I was able to observe the inside, but the illuminance was protective cover 3
It was about 1/10 of the case where 1 was attached. When separating the grown crystal from the raw material melt, the high pressure container 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 peep window for observing the inside of a heating furnace, the peek window surrounds a transparent rod projecting into the furnace and a side surface of the projecting portion of the rod in the furnace. And a cylindrical body projecting from the end surface of the rod body inside the furnace,
Since the tubular body is in contact with the low temperature portion of the heating furnace due to cooling, the gas component in the furnace is cooled and solidified by the tubular body of the sight window and adheres to the tubular body. Since it is possible to prevent the gas component from adhering to the end surface inside the furnace of the transparent rod of, from the start to the end of the crystal growth,
The visibility in the furnace is secured and the crystal growth process can be observed.

[Brief description of 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 container 3 Viewing window 30 Quartz rod (rod) 30a End face 30b Side face 31 Protective cover (cylindrical body)

Claims (4)

[Claims] 1. A crystal growth apparatus having a peep window for observing the inside of a heating furnace, wherein the peek 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 projecting from the end surface of the rod body inside the furnace,
The apparatus for producing a single crystal, wherein the cylindrical body is in contact with a low temperature portion of the heating furnace due to cooling. 2. The thermal conductivity of the cylindrical body is 10 Wm ⁻¹ K ^−1.
It is above, The single crystal manufacturing apparatus of Claim 1 characterized by the above-mentioned. 3. The length of the cylindrical body is equal to or longer than a length at which a gas component in the furnace is solidified and sufficiently adhered to the cylindrical body, and is a length not longer than a field of view not narrowed. The single crystal production apparatus according to claim 1 or 2, which is characterized. 4. The single crystal manufacturing apparatus according to claim 1, wherein the cylindrical body is made of stainless steel or molybdenum.