JP2558659B2 - Infrared heating single crystal manufacturing equipment - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to growing a single crystal such as a refractory oxide material in an infrared heating single crystal manufacturing apparatus.

2. Description of the Related Art For example, in the production of single crystals of electrically insulating materials such as refractory oxides, a floating zone type single crystal production apparatus using light heating using an infrared lamp such as a halogen lamp is used as a heating source.

The infrared heating single crystal manufacturing apparatus, an infrared lamp such as a halogen lamp is arranged as a heat source at one focus of the spheroidal mirror, and at the other focus, a material rod or a crystal rod to be heated is disposed, and This is a device that reflects infrared rays emitted from an infrared lamp by a spheroidal mirror and condenses it on an object to be heated, and in this device, for example, the spheroidal mirror described in Japanese Utility Model Publication No. 46-23686 is used. One mono-elliptical type, or a bi-ellipse, as described in Japanese Patent Publication No. 50-29405, in which two spheroidal mirrors, each of which is approximately a half body, are faced to each other so that their focal points coincide. The type is common.

For example, a specific example of a bi-elliptical type infrared heating single crystal manufacturing apparatus belonging to the method of Japanese Patent Publication No. 50-29405 will be described with reference to FIG.

In the figure, (1) and (2) are two symmetrical ellipsoidal spheroidal mirrors, which are face-to-face coupled so that the focal points F0 and F0 of one of them coincide with each other. (3) and (4) are the first and second focal points F1 and F of the other of the spheroidal mirrors (1) and (2).
Two heat sources fixedly arranged at 2, for example, an infrared lamp such as a halogen lamp. Reference numeral (5) is a heated portion disposed at the focal point F0 of each spheroidal mirror (1), (2), which coincides with each other. A raw material rod (6) extending vertically from above and a crystal extending vertically from below. It is a portion where the rod (7) is butted, that is, a melting zone (floating zone) where crystal growth is performed. (8) is a transparent quartz tube that surrounds the raw material rod (6) and the crystal rod (7), and holds a suitable atmospheric gas for the crystals in the quartz pipe (8).

In single crystal growth by infrared heating using the above device,
First and second focal points F1 and F of each spheroidal mirror (1) and (2)
Infrared rays emitted from the infrared lamps (3) and (4) arranged in 2 are reflected by the spheroidal mirrors (1) and (2), and are reflected on the heated portion (5) arranged at the focal point F0. Focus and heat.

The heated portion (5) is melted by the radiant energy due to the infrared irradiation, and the raw material rod (6) and the crystal rod (7) are vertically lowered while being rotated to grow a single crystal.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention By the way, since the infrared heating single crystal manufacturing apparatus is a melting zone method, it is less contaminated with impurities, can be applied to decomposition and melting compounds, and can uniformly introduce additives. Although it has an advantage that it cannot be seen, since the heating remarkably depends on the degree of light absorption of the sample, some problems as described below remain in the case of growing a transparent crystal.

In the case of transparent crystals, the solid-liquid phase interface (solid-liquid interface) during crystal growth generally tends to be concave toward the liquid phase. In such a case, defects such as dislocations and low-angle grain boundaries in the crystal have the property of maintaining an angle close to a right angle to the solid-liquid interface. Defects will be concentrated in the center. As a result, a large strain is generated in the obtained crystal, and it becomes easy to polycrystallize and cracks run.

Means for Solving the Problems The present invention has been proposed in view of the above problems, and a technical means for solving the problems is to use an infrared lamp as a heat source at one focus of a spheroidal mirror. The transparent quartz tube sample chamber is placed so as to surround the other focal point, and the light from this infrared lamp is the abutting portion of the raw material rod and the crystal rod placed in the transparent quartz tube sample chamber. In an apparatus for concentrating and heating a heating section to grow a single crystal, an opaque quartz tube is placed at the end of the opaque quartz tube so that the crystal rod is further surrounded in the transparent quartz tube sample chamber. The feature is that they are arranged in the vicinity.

Function The opaque quartz tube transmits light and heats the crystal rod, and when the light passes through it, it cannot scatter and scatters.Therefore, it is irradiated near the end of the crystal rod.If there is no opaque quartz tube, it gathers in the heated area. The emitted light is scattered and heats the crystal rod. In addition, the opaque quartz tube is more likely to absorb light and radiant heat from infrared lamps, raw material rods, their melts, crystal rods, etc., compared to transparent quartz tubes, as the light path is scattered and the optical path becomes longer. It serves as a heat retaining cylinder that prevents heat loss that is absorbed and raises its own temperature and is conducted from the crystal surface to the atmosphere, and that does not require a heater.

Therefore, this opaque quartz tube reduces the heat release from the crystal surface to the atmosphere for the crystal having poor light absorption, and positively improves the concave solid-liquid interface to the convex interface for the liquid phase.

EXAMPLE An example applied to the bi-elliptical single crystal manufacturing apparatus of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a sectional view of an infrared heating single crystal manufacturing apparatus showing an embodiment of the present invention. FIG. 2 is an enlarged view of a heated portion of a conventional apparatus that does not use an opaque quartz tube, and FIG. 3 is an enlarged view of a heated portion of an apparatus embodying the present invention.

In FIG. 1, (20) and (21) are two symmetrical ellipsoidal spheroidal mirrors, which are combined so as to face each other so that their respective focal points F0 and F0 coincide with each other to form a heating furnace section. The inner surfaces of the spheroidal mirrors (20) and (21), that is, the reflecting surfaces are plated with gold in order to effectively reflect infrared rays. (22) and (23) are heating sources fixed to the other focal points F1 and F2 of the spheroidal mirrors (20) and (21), for example, infrared lamps such as halogen lamps and xenon lamps.
(15) is the same focal point of each spheroidal mirror (20), (21)
A heated part arranged at F0 is supported by a raw material rod (14) supported at the lower end of an upper spindle (12) extending vertically downward from above and a upper end of a lower spindle (18) extending vertically downward from below. It is the part where the crystal rod (16) that was The sample chamber (13) defines a space (m1) in which the raw material rod (14) and the crystal rod (16) are arranged and a space (m2) in which the infrared lamps (22) and (23) are arranged. A transparent quartz tube forming a transparent quartz tube (24), the sample chamber (24) being kept in an atmosphere gas suitable for the crystal in the compartment defined by the transparent quartz tube (13), while the infrared lamps (22), (23) Cools the infrared lamps (22) and (23) by air so that they can be safely turned on. (17) is the heated part (15)
An opaque quartz tube installed vertically below the neighborhood.

In the single crystal growth by the device of the present invention, infrared rays emitted from infrared lamps (22) and (23) arranged at the first and second focal points F1 and F2 of the spheroidal mirrors (20) and (21). Is reflected by the spheroidal mirrors (20) and (21) and focused on the heated portion (15) arranged at the focal point F0 to be heated and melted, and the upper spindle (12) and the lower spindle (18) are A single crystal is grown by lowering it relatively.

At this time, as shown in FIG. 2, in the conventional method without the opaque quartz tube (17), the infrared ray lamp is used to heat the heated part (15) and its vicinity, but the infrared ray irradiation line (31). Materials that have poor light absorption in the infrared region, even if added, cause a large heat loss to the atmosphere around the crystal compared to a small amount of light absorption on the crystal surface, so even if the inside of the heated part is in the liquid phase, The surface is solidified (crystallized), and the solid-liquid interface becomes concave toward the liquid phase.

However, as shown in FIG. 3, if the opaque quartz tube (17) is installed vertically below the vicinity of the heated part (15), the temperature retaining effect of the quartz tube (17) that optimally changes the temperature gradient causes The temperature gradient from the crystal to the surrounding atmosphere becomes gentle, the radiation (32) from the crystal, that is, the heat loss is reduced, and the solid-liquid interface is improved in the convex direction toward the liquid phase.

Diameter of the opaque quartz tube (17) and heated part (15)
The relationship between the solid-liquid interface position and the upper end position of the opaque quartz tube (17) depends on the melting point and the crystal diameter of the crystal to be grown, but the diameter of the opaque quartz tube (17) is approximately 2 to 5 times the crystal diameter. It is desirable that the upper end of the opaque quartz (17) is located 10 mm above and 20 mm below the solid-liquid interface of the crystal.
In addition, as a method of supporting the opaque quartz tube (17), the transparent quartz tube (13) and the opaque quartz tube (17) are integrated downward in FIG.

EFFECTS OF THE INVENTION According to the present invention, an opaque quartz tube, which has a larger light absorption than transparent quartz, is installed around the crystal in an infrared heating single crystal manufacturing apparatus, so that a transparent crystal having a poor light absorption can be solidly grown. It is possible to improve the liquid interface to a suitable convexity toward the liquid phase, reduce defects such as dislocations and low-angle grain boundaries in the crystal, and generate large strain or polycrystallization or crystal growth in the obtained crystal. It is possible to prevent cracks that occur in the crystal, and to achieve extremely high-quality single crystal growth.

[Brief description of drawings]

FIG. 1 is a sectional view of an infrared heating single crystal production apparatus showing an embodiment of the present invention using a double quartz tube sample chamber. FIG. 2 is an enlarged cross-sectional view of a heated portion of a conventional system device that does not use an opaque quartz tube. FIG. 3 is an enlarged cross-sectional view of a heated portion of an infrared heating single crystal manufacturing apparatus using a double quartz tube sample chamber of an opaque quartz tube and a transparent quartz tube according to the present invention. FIG. 4 is a sectional view of a conventional infrared heating single crystal manufacturing apparatus. (20), (21) ...... spheroidal mirror, (22), (23) ...... heat source (infrared lamp) (14) …… raw material rod, (15) …… heated part, (16) …… Crystal rod, (13) …… Transparent quartz tube, (17) …… Opaque quartz tube, (31) …… Infrared lamp irradiation line, (32) …… Radiation ray from crystal, (33) …… Concave shape Solid-liquid interface of (34) …… Convex solid-liquid interface, F0, F1, F2 …… Focus.

Claims (1)

(57) [Claims] 1. An infrared lamp as a heat source is arranged at one focus of a spheroidal mirror, and a transparent quartz tube sample chamber is arranged so as to surround the other focal portion, and the light from the infrared lamp is the transparent quartz. In a device for growing a single crystal by condensing and heating a heated portion which is a butting portion of a raw material rod and a crystal rod arranged in a tube sample chamber, a portion close to the heated portion in the transparent quartz tube sample chamber Then, an infrared heating single crystal manufacturing apparatus is characterized in that an opaque quartz tube is arranged so that its end portion is near the heated portion so as to further surround the crystal rod.