JPH05330979A - Device for liquid-phase epitaxial growth - Google Patents

Abstract

PURPOSE:To provide a device for liquid-phase epitaxial growth capable of simultaneously growing single crystal films on plural substrate bases and uniformizing thickness of grown single crystal films. CONSTITUTION:Plural sheets of substrate bases 14 are supported vertically at intervals on a horizontal holding bar 15 whose one end is connected to a motor 17. The motor 17 is vertica1ly moved by a lifter 19. When holding bar 15 is dropped, the lower half of the substrate bases 14 is immersed in a raw material solution 13 in a crucible 12, the motor 17 is driven at this position to grow single crystal films on the substrate bases 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid phase epitaxial growth apparatus for growing a single crystal film on the surface of a base substrate.

[0002]

2. Description of the Related Art Conventionally, magnetic garnet single crystals have been widely used in magnetostatic wave (MSW) devices such as delay line filters, oscillators and nonlinear devices, and magneto-optical elements such as optical isolators, circulators and switches utilizing the Faraday rotation effect. It is used. A liquid phase epitaxial growth method (LPE method) is known as a main method for producing the magnetic garnet single crystal.

This liquid phase epitaxial growth method uses a vertical process.
Insert the garnet into the platinum crucible held in the furnace under the specified conditions.
PbO and B as oxides and solvents of the constituent elements
₂O₃Fill with and homogenize at about 1200 ° C to form a solution
To do. This solution is applied to the liquidus (Liquidus) and solidus (Solidus)
s), that is, a constant temperature of around 900 ° C
Garnet to a supersaturated state and then
Substrate Gd₃Ga _FiveO₁₂(GGG) Submerge the substrate,
By rotating for a fixed time and growing for a predetermined time,
To grow a magnetic garnet single crystal film on the surface of the underlying substrate.
It Finally, place the base substrate at about 500 rpm above the solution.
Magnetic garnet single bond by rotating at rotation speed
This is to shake off the solution adhering to the crystal film.
It The base substrate was attached to the lower end of the support rod.
It is held horizontally by the substrate holder.

[0004]

However, the above-mentioned method has a drawback that mass productivity is poor because only one single crystal plate can be manufactured by one growth. Therefore, in order to improve mass productivity, there is also a method of holding a plurality of base substrates 2 in parallel on a substrate holder 1 so that a plurality of single crystal films can be grown at the same time as shown in FIG. In FIG. 1, 3 is a crucible, 4 is a raw material solution, 5 is a support, 6 is a support rod, and 7 is a heating furnace.

However, in this method, since the depth in the solution in which each base substrate is immersed is different, there is a problem that the growth conditions of each base substrate are different and the thickness of the grown single crystal film becomes uneven. .. If the thickness of the single crystal film is not uniform, variations in characteristics occur when it is used in a magnetostatic wave device, and it becomes practically unusable. Therefore, the object of the present invention is to
It is an object of the present invention to provide a liquid phase epitaxial growth apparatus capable of growing a plurality of underlying substrates at the same time and making the grown single crystal film uniform in thickness.

[0006]

In order to achieve the above object, according to the present invention, the central portions of a plurality of base substrates are detachably inserted and fixed to a horizontal support rod, and the base substrates are parallel and perpendicular to each other. While being supported, an elevating means for vertically moving the support rod in parallel to a position where the base substrate is immersed in the raw material solution, and a drive means for rotationally driving the support rod are provided.

[0007]

[Function] A plurality of base substrates fixed to a horizontal support bar are
The immersion is parallel to each other and perpendicular to the solution surface. Therefore, the immersion depth of each base substrate is the same, and the single crystal film growth conditions are also the same. As a result, there is almost no variation in the thickness of the grown single crystal film.

[0008]

FIG. 2 shows an apparatus for growing a magnetic garnet film which is an example of the present invention. Inside the electric furnace 10, a support base 11
A wide-mouthed box-shaped platinum crucible 12 whose bottom surface is supported by is arranged. The crucible 12 is filled with a raw material for a magnetic garnet film and a solvent to form a solution 13.

The disk-shaped base substrate 14 made up of a plurality of GGG substrates is vertically supported by a horizontally arranged support rod 15 made of platinum or platinum alloy with a space therebetween. As shown in FIG. 3, the support bar 15 is formed by flatly cutting two side surfaces 15a symmetrical with respect to the screw axis. Corresponding to this, the central portion of the base substrate 14 is connected to the flat surface 15a of the support bar 15. A rectangular insertion hole 14a having two mating sides is formed. Therefore, the base substrate 14 is prevented from rotating while being inserted into the support rod 15. A plurality of fixing jigs 16 made of platinum or platinum alloy are screwed onto the support rod 15, and the fixing jigs 16 press and hold both side surfaces of the central portion of the base substrate 14 to fix the base substrate 14. It is fixed to the support rod 15.

One end of the support rod 15 is connected to a motor (driving means) 17 arranged outside the furnace, and the support rod 15 is rotationally driven at a constant speed in one direction or the forward and reverse directions. A support 18 that supports the motor 17 is moved up and down in parallel by a lifter (elevating means) 19. The lifter 1
A groove 10a having a length corresponding to the movement stroke of 9 is formed in the side wall of the electric furnace 10, and the support rod 15 is movably inserted into the groove 10a.

Here, an example of the operation of the liquid phase epitaxial growth apparatus having the above configuration will be described. First, the garnet raw material and the solvent are mixed in the crucible 12, heated and melted at 1200 ° C. and held for 2 hours, and then the temperature is lowered to about 900 ° C. to bring the garnet into a supercooled state. On the other hand, the support rod 15 supporting the base substrate 14 is positioned above the crucible 12 to remove the solution 1
3 is held right above the surface of No. 3 for several minutes and preheated so that the temperature of the base substrate 14 becomes almost the same as the solution temperature (shown by the solid line in FIG. 2). After preheating the base substrate 14, the lifter 19
The support rod 15 is lowered by the above, and the lower half of the base substrate 14 is immersed in the solution 13 (shown by a chain double-dashed line in FIG. 2). Then, the motor 17 rotates the support rod 15 in one direction or in the reverse direction to grow the magnetic garnet single crystal film isothermally for several hours. At this time, the solution 13 is applied to the base substrate 14 up to the position shown in FIG. 4A, and the rotation speed of the motor 17 is adjusted so that the solution 13 does not reach the support rod 15 as shown in FIG. 4B. Adjust. This is because if the solution 13 is applied to the supporting rods 15, crystals also grow on the supporting rods 15 and it becomes difficult to separate the base substrate 14 from the supporting rods 15.
In this way, since the plurality of base substrates 14 are immersed vertically in the solution 13, the immersion depth of each base substrate 14 is the same, and the single crystal film growth conditions are the same. Therefore, the thickness of the grown single crystal film becomes uniform. After growing the single crystal film, the lifter 19 raises the support rod 15 to pull the base substrate 14 onto the solution 13. And the motor 17
Is rotated at a high speed to shake off the solution adhering to the base substrate 14. Then, the supporting rod 15 and the base substrate 14 are taken out of the electric furnace 10 by an apparatus (not shown), and the manufacturing is completed. The single crystal film grown by the above method,
As shown by hatching in FIG. 5, the base substrate 14 is formed in a ring shape in a portion other than the central portion.

Table 1 shows the film thickness of seven garnet single crystal films formed simultaneously by the conventional and the epitaxial growth apparatus of the present invention. The growing conditions are the same. As is clear from Table 1, the variation of the film thickness was 11 μm in the related art, but it was 0.5 μm in the present invention, and the uniformity of the film thickness was remarkably improved.

[0013]

[Table 1]

Although the magnetic garnet single crystal has been described in the above embodiments, the present invention is not limited to this. For example, the present invention is also applicable to liquid phase epitaxial growth of lithium niobate which is a single crystal for optical devices. Can be applied. Further, although the support rod having a plurality of base substrates attached thereto has a cantilevered support structure, it goes without saying that it may have a both-ends support structure. Also, the free end of the support rod may be supported by a crucible or other member when the base substrate is immersed. In the case of the double-end support structure, the support rod can be prevented from bending even if the number of base substrates increases.
It is possible to eliminate variations in the immersion position of the base substrate with respect to the solution. Further, although only the lower half of the base substrate is immersed in the solution and the single crystal film is grown while rotating the base substrate, the single crystal film may be grown while the entire base substrate is immersed in the solution.

[0015]

As is apparent from the above description, according to the present invention, the plurality of base substrates are vertically supported by the horizontal support rod, so that the plurality of base substrates are provided at the same depth of the solution. It can be dipped and a single crystal film can be grown under the same conditions. Therefore, the uniformity of the film thickness of the grown single crystal film is remarkably improved, and when used in a magnetostatic wave device, there is little variation in characteristics, and a good quality single crystal film can be mass-produced.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a conventional liquid phase epitaxial growth apparatus before immersion.

FIG. 2 is a longitudinal sectional view of a liquid phase epitaxial growth apparatus according to the present invention before immersion.

FIG. 3 is an exploded perspective view of a support rod and a base substrate.

FIG. 4 is a side view showing how the solution is applied as the base substrate rotates.

FIG. 5 is a front view showing a single crystal film grown on a base substrate.

[Explanation of symbols]

 10 Electric Furnace 12 Crucible 13 Solution 14 Base Substrate 15 Support Rod 17 Motor (Drive Means) 19 Lifter (Lifting Means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masato Kumagorani 2-26-10 Tenjin, Nagaokakyo City, Kyoto Prefecture Murata Manufacturing Co., Ltd. (72) Inventor Yutoku Sekijima 2-26-10 Tenjin, Nagaokakyo City, Kyoto Prefecture Murata Manufacturing Co., Ltd. (72) Inventor Hiroshi Takagi 2-26-10 Tenjin Tenjin, Nagaokakyo City, Kyoto Prefecture Murata Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. A liquid phase epitaxial growth for growing a single crystal film on the surface of a base substrate by immersing the base substrate in a crucible in which a single crystal raw material is melted and growing it for a predetermined time while rotating at a fixed position. In the device, the central portions of a plurality of base substrates are detachably inserted and fixed on a horizontal support rod, the base substrates are supported in parallel and vertically with each other, and the base substrates are supported up to a position where they are immersed in the raw material solution. Elevating means for moving the rod in parallel up and down,
A liquid phase epitaxial growth apparatus comprising: a driving unit that rotationally drives the support rod.