JP2002114599A - Method for manufacturing artificial quartz and artificial quartz by the manufacture method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain artificial quartz which is grown mainly in a specified direction such that the quartz has no inclusion of impurities and handling of the quartz in the succeeding cutting process, or the like, is made easy. SOLUTION: A great number of seed quartz 6 is supported in the position perpendicular to the vertical direction of a growing furnace, and a controlling plate 7 is disposed in contact with the seed quartz in the upper face side of the seed quartz. The controlling plate 7 consists of a quartz plate cut along an R plane, and a holding plate 71 made of iron, or the like, is disposed above the controlling plate 7. While growing of the quartz proceeds, the crystal grows in the Z axis direction where no controlling plate is disposed but does not grow on the face of the seed quartz tightly in contact with the controlling plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an artificial quartz used as a quartz oscillator or an optical element and the like, and more particularly to an artificial quartz obtained by the method. The present invention relates to a manufacturing method.

[0002]

2. Description of the Related Art Artificial quartz is grown by a hydrothermal synthesis method. An artificial quartz growing furnace (autoclave) is sandwiched between a convection control plate and a raw material for growing (raw crystal) is placed below and a seed crystal is placed above. Install each. The growth furnace is filled with a growth solution (alkali solution), and the growth furnace is sealed and heated.
Then, a temperature gradient is set so that the temperature on the lower side of the growing furnace is higher than that on the upper side, and the growing solution is thermally convected in the growing furnace.
As a result, the growing material melted in the lower part of the growing furnace is
It reaches the upper part of the growth furnace, where it cools and becomes supersaturated and precipitates and grows on the seed crystal. By performing this operation continuously for a predetermined period, an artificial crystal having a predetermined size can be obtained.

In recent years, the use of artificial quartz as an optical component other than a quartz oscillator and as a surface acoustic wave device has been increasing. When used as an optical component, it is required to reduce impurities in the crystal as much as possible. When used as a surface acoustic wave device, from the viewpoint of manufacturing efficiency, it is required to provide a specific growth region on a large wafer. Was. In order to meet such demands, a manufacturing method has been invented which mainly grows in a specific direction as disclosed in Japanese Patent Publication No. 57-49520. Tokunosho 5
No. 7-49520 is a manufacturing method in which an upper basic growth surface of a seed crystal is cut off by a plate made of a material different from quartz to thereby form a crystal on the lower basic growth surface. Although the plate disclosed here is disclosed only as a plate made of a different substance from the single crystal to be grown, an iron plate is often used in practice in terms of cost.

[0004] However, the iron plate easily generates oxides on its surface, and after a predetermined growth period, the grown crystal and the iron plate are firmly fixed, and it is necessary to separate the two from each other. Cracking and chipping sometimes occurred. Further, there is a problem that the grown crystal is broken due to a difference in thermal expansion coefficient from that of the crystal.

[0005]

In order to avoid such a problem of the adhesion between the crystal and the control plate, it has been considered that a fluororesin resin material or a stainless steel material is used for the control plate. It has been put to practical use. However, resin materials and stainless materials have the disadvantage that impurities are likely to occur when placed in a high-temperature, high-pressure hydrothermal synthesis environment.In the case of stainless materials, electrolytic corrosion may occur. I sometimes did.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In obtaining an artificial quartz crystal mainly grown in a specific orientation, the incorporation of impurities during hydrothermal synthesis is small, and peeling from the control plate is prevented. It is an object of the present invention to obtain an artificial quartz that is easy and easy to handle in a post-process of a peeling surface.

[0007]

In order to achieve the above-mentioned object, the present inventor has proposed a control plate for regulating the growth of artificial quartz without firmly adhering to the crystal to be grown and generating impurities. As a result of studying a material having a small number of grains, the inventors have found that the above problem can be solved by using a quartz plate having a different cutting orientation from the seed quartz, and has the following features.

That is, according to a first aspect of the present invention, there is provided a method for producing artificial quartz by a hydrothermal synthesis method using thermal convection,
It is characterized in that the seed crystal having a predetermined cutting orientation is grown in a state in which the seed crystal is brought into close contact with a control plate made of a quartz plate having a cutting orientation different from the cutting orientation.

According to the first aspect, the seed crystal grows mainly in the direction opposite to the direction in which the control plate is arranged. For example, in a Z-plate quartz (XY plane), the main growth surface is in the thickness direction (Z
In the case where only one of the Z growth surfaces is grown, the control plate is brought into close contact with the other Z growth surface, and the crystal is mainly grown on one of the Z growth surfaces. grow up.

Since the crystal growth does not progress on the surface in close contact with the control plate, the two do not firmly adhere to each other, and the other Z growth surface after the completion of the growth maintains the substantially flat state of the seed crystal. Therefore, peeling from the control plate is extremely easy, and the artificial quartz grown during the peeling operation is not damaged. In addition, since the seed crystal is maintained in a planar state, a very smooth surface in which the cutting orientation is determined can be obtained, and thus can be used as a reference surface in various subsequent cutting processes.

Further, since the control plate is made of quartz, the discharge of impurities is extremely small, and the chance of taking in impurities by the crystal to be grown is reduced.

According to a second aspect of the present invention, there is provided a method for producing an artificial quartz by a hydrothermal synthesis method using thermal convection, wherein a quartz film is formed on a part of a surface of a seed quartz having a predetermined cutting orientation. It is characterized in that growing is carried out in a state of being brought into close contact with the metal plate. The metal plate is preferably made of a material such as iron that easily forms an oxide on the surface.

According to the second aspect, similarly to the first aspect, the seed crystal grows mainly in the direction opposite to the direction in which the control plate is arranged. Since the surface in close contact with the control plate has a structure in which a quartz film is formed on the surface, the grown artificial quartz does not firmly adhere, and the Z-growth surface on which the control plate has been placed after growth is almost completely seed-free. The plane state of the crystal is maintained. Therefore, peeling from the control plate is extremely easy, and the artificial quartz grown during the peeling operation is not damaged.
In addition, since the seed crystal is maintained in a planar state, a very smooth surface in which the cutting orientation is determined can be obtained, and thus can be used as a reference surface in various subsequent cutting processes.

Further, since the surface of the control plate is made of quartz, the discharge of impurities is extremely small, and the chance of taking in impurities by the crystal to be grown is reduced. Further, since the base material of the control plate is made of a metal plate such as iron, material cost can be reduced, and handling is simplified because of high mechanical strength.

Further, as set forth in claim 3, in the method for manufacturing artificial quartz according to claim 2, a side wall may be formed on the metal plate, and the growth of the crystal may be regulated on the side wall.

According to the third aspect, since the growth of the crystal is restricted by the side wall, a crystal corresponding to the arrangement of the control plate and the side wall can be obtained, and the surface whose growth is restricted by the side wall is formed on the side wall. It does not stick firmly.

A fourth aspect of the present invention discloses a specific configuration of the seed crystal. In the method of manufacturing an artificial crystal according to the first, second, or third aspect, the seed crystal is an XY plane quartz plate. Is characterized in that crystal is grown mainly in one Z-axis direction.

In the XY plane crystal (Z-plate crystal), the main growth surface is in the thickness direction (Z-axis direction). When only one Z growth surface is grown, a control plate is mounted on the other Z growth surface. By bringing them into close contact and promoting growth in this state, crystals grow mainly on one Z growth surface side. Since the crystal grown in this way has a configuration in which the seed crystal is located on the end face,
Suitable for optical components without impairing the optical characteristics of quartz.

According to a fifth aspect of the present invention, in the method of manufacturing an artificial quartz according to the first to fourth aspects,
The control plate closely contacting the seed crystal to be grown may be arranged on the upstream side of the thermal convection.

In the growth furnace, the growing solution is subjected to thermal convection, and impurities are also thermally convected together with the growing solution. According to the above configuration, since the control plate is arranged on the upstream side of the heat convection, that is, above the seed crystal to be grown in many cases, the deposition of impurities on the seed crystal and the artificial crystal having advanced crystal growth is prevented. . Therefore, an artificial quartz with few impurities can be obtained.

A sixth aspect of the present invention is an artificial quartz crystal manufactured by the manufacturing method according to the first to fifth aspects,
It is extremely easy to peel off from the control plate, and it is possible to obtain an extremely smooth surface in which the cutting orientation is determined without causing damage to the artificial quartz grown by the peeling operation. Further, the content of impurities can be extremely reduced.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

First, an artificial crystal growing furnace for growing an artificial crystal using the artificial crystal growing solution (hereinafter, simply referred to as a growing solution) according to the present invention. Hereinafter, the configuration of the growing furnace will be described.

FIG. 1 is a sectional view showing the internal configuration of the growth furnace 1 according to the present embodiment. As shown in FIG.
An electric furnace (not shown) is provided around the outer periphery of the furnace main body 2, and the furnace main body 2 is heated by the electric furnace 3. The furnace main body 2 has a bottomed cylindrical shape with an open top, and a lid 22 for sealing the internal space 4 of the furnace main body 2 is attached to an upper end opening 21. A pressure gauge for measuring the internal pressure of the furnace body 2 is attached to the lid 22. Further, the inner space 4 of the furnace body 2
A convection control plate 23 is disposed at an intermediate position in the vertical direction. The convection control plate 23 partitions the internal space 4 of the furnace main body 2 into a lower raw material chamber 41 and an upper growth chamber 42.

The raw material chamber 41 contains a natural crystal (laska) 5 as a raw material for growing. On the other hand, training room 4
2 accommodates a plurality of seed crystals 6, 6,... Supported on the crystal growing shelf F.

The interior space 4 of the furnace body 2 is filled with a growing solution (alkaline solution) which is a feature of the present embodiment.

-Explanation of the artificial crystal growing operation- The artificial crystal growing operation by the growing furnace 1 in which the natural crystal 5 and the seed crystal 6 are housed and filled with the growing solution as described above will be described below.

In this growing operation, the furnace main body 2 is heated by the electric furnace 3. The heating state includes the growth room 4
The temperature of the raw material chamber 41 is set to be higher than that of the raw material chamber 41, and the temperature difference causes the growing solution to be supplied to the raw material chamber 41 under high temperature and pressure.
And the growth room 42 is subjected to thermal convection. In the present embodiment, for example, the temperature of the growth chamber 42 is set to 320 ° C.
Is set to 360 ° C. That is, both rooms 41,
Heat convection is performed by setting the temperature difference of 42 to 40 ° C. The temperature and the temperature difference between the two chambers 41 and 42 are not limited to the above.

As a result, the natural crystal 5 melted in the raw material chamber 41 reaches the growth chamber 42, where it is cooled and becomes supersaturated and grows on the seed crystal 6. By performing this operation continuously for a predetermined period, an artificial crystal having a predetermined size can be obtained.

FIG. 2 is an exploded perspective view showing a structure for attaching a seed crystal. In the figure, the crystal axis directions (X, Y,
Z), and the same applies to the following drawings. 3 is a cross-sectional view in the longitudinal direction of the assembled state in FIG. 2, and FIG. 4 is a cross-sectional view in the short direction.

The seed crystal 6 is a rectangular Z-plate crystal and is supported in large numbers so as to be positioned at right angles to the vertical direction of the growing furnace. More specifically, on the crystal growing shelf F, a large number of a pair of supports F1 and F1 are arranged at predetermined intervals, and a seed crystal 6 is supported between the supports F1 and F1 in a erected state. . Each support has a positioning step F
2 and F2 are formed, and a control plate 7 is provided on the upper surface side of the seed crystal in close contact with the seed crystal. The control plate 7 is formed of an R-plane cut quartz plate, and the R-plane cut has a cutting direction different from that of the seed crystal. Control board 7
A holding plate 71 made of iron or the like is installed above the supporting member F.
1, fixed to F1. In the present embodiment, the holding plate 71 is formed with an inverted concave portion 71a, and the control plate 7 is housed in the concave portion.

As the crystal growth proceeds, the seed crystal mainly grows in the Z-axis direction without the control plate as shown by the dotted line in FIGS. 3 and 4, but the surface of the seed crystal that is in close contact with the control plate is crystal grown. After the growth is completed, it can be easily removed from the support, and a smooth surface can be obtained without performing a treatment such as polishing.

Another configuration of the support will be described with reference to the drawings. 5 is an exploded perspective view, FIG. 6 is a longitudinal sectional view when FIG. 5 is assembled, and FIG. 7 is a transverse sectional view thereof.
In this configuration, the material and configuration of the control plate are different from those of the above embodiment. That is, the control plate 8 uses an iron plate (metal plate) on the surface of which a quartz film 8b is formed, and the side walls 81, 8 for regulating the growth in the X-axis direction.
Two. The method of forming a quartz film on an iron plate is as follows:
For example, it is formed by short-term hydrothermal synthesis in a growth furnace as shown in FIG. That is, a lasker is stored in the raw material chamber of the growth furnace, and an iron plate constituting the base material 8a of the control plate is suspended at a predetermined interval in the growth chamber, and is kept under the same environment as crystal growth for several days. As a result, a thin crystallized crystal is deposited on the surface of the iron plate, and the control plate 8 having the crystal film (crystallized film) 8b formed on the surface can be obtained. Such a method is, of course, applied to the bent portions (side walls 81, 8) as shown in FIG.
The present invention can also be applied to a metal plate having the condition 2).

As shown in FIG. 5, a plurality of a pair of supports F1, F1 are arranged on the crystal growing shelf F at a predetermined interval, and a seed crystal 6 is placed between the supports F1, F1. It is supported in a erected state. A positioning step is formed on the support, and a control plate 8 is provided on the upper surface of the seed crystal in close contact with the seed crystal. The control plate 8 is made of an iron plate on the surface of which a quartz compound is formed as described above,
It is fixed to the supporting members F1 and F1 by a not-shown locking member or the like.

According to such a configuration, it is possible to obtain an artificial crystal in which the growth of one of the Z planes and the growth of the -X and + X planes is regulated, and each regulated growth plane is in a flat state. can do. The regulation of the growth of the X plane, that is, the formation of the side wall in the control plate may be performed on only one side, for example, only on the + X plane.

[0036]

According to the first aspect, since a crystal having a cutting orientation different from that of the seed crystal is used for the control plate, it is possible to obtain a high-quality artificial crystal with less discharge of impurities. In addition, since strong bonding does not occur between the seed crystal and the control plate, peeling from the control plate is easy, and handling of the peeled surface in a subsequent step is easy.

According to the second aspect, since the control plate has a structure in which a metal plate is used as a base material and a crystal compound is generated on the surface, it is possible to obtain a high-quality artificial quartz with less discharge of impurities. Further, since the base material is made of a metal plate, material costs can be reduced, and handling is simplified because of high mechanical strength. In addition, since there is no strong fixation between the seed crystal and the control plate, the separation from the control plate is easy, and the handling of the peeled surface in a subsequent step is easy.

According to the third aspect, since the growth of the crystal is regulated by the side wall, in addition to the effect of the second aspect, a crystal corresponding to the arrangement of the control plate and the side wall can be obtained. In addition, the surface whose growth is regulated by the side wall does not firmly adhere to the side wall, and the subsequent cutting process is easy.

According to the fourth aspect, the crystal grows mainly on one Z growth surface side. Since the crystal grown in this manner has a configuration in which the seed crystal is located at the end face, it is possible to obtain a high-quality artificial crystal for optical components without impairing the optical characteristics of the crystal.

According to the fifth aspect, since the control plate is arranged on the upstream side of the heat convection, the deposition of impurities on the seed quartz and the artificial quartz with advanced crystal growth is prevented. Therefore, a high-quality artificial quartz with less impurities can be obtained.

According to the sixth aspect of the present invention, the artificial quartz having an extremely smooth surface whose cutting orientation is determined is extremely easy to be peeled from the control plate without causing damage to the artificial quartz grown by the peeling operation. You can get crystal. In addition, a high-quality artificial quartz having an extremely small impurity content can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an internal configuration of a growth furnace.

FIG. 2 is an exploded perspective view showing a support.

FIG. 3 is a longitudinal sectional view of FIG. 2;

FIG. 4 is a cross-sectional view in the lateral direction of FIG. 2;

FIG. 5 is an exploded perspective view showing another configuration example of the support tool.

6 is a longitudinal sectional view of FIG. 5;

FIG. 7 is a cross-sectional view in the lateral direction of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Artificial crystal growing furnace 2 Furnace main body 4 Internal space 5 Natural crystal 6 Seed crystal 7, 8 Control plate F1 Support

Claims (6)

[Claims] 1. A method for producing an artificial quartz by a hydrothermal synthesis method using thermal convection, wherein a part of a surface of a seed crystal having a predetermined cutting orientation is controlled by a quartz plate having a cutting orientation different from the cutting orientation. A method for producing artificial quartz, characterized in that growing is carried out in a state of being brought into close contact with a plate. 2. A method for producing an artificial quartz by a hydrothermal synthesis method using thermal convection, wherein a part of a surface of a seed quartz having a predetermined cutting orientation is brought into close contact with a metal plate having a quartz film formed on the surface. A method for producing an artificial quartz, characterized in that growing is carried out in a state where the artificial quartz is grown. 3. The method according to claim 2, wherein the metal plate has a side wall, and the growth of the crystal is restricted on the side wall. 4. The production of an artificial quartz according to claim 1, wherein the seed quartz is an XY plane quartz plate, and the quartz is grown mainly in one Z-axis direction. Method. 5. The method of manufacturing an artificial quartz according to claim 1, wherein the control plate closely contacting the seed crystal to be grown is arranged upstream of the thermal convection. 6. An artificial quartz crystal manufactured by the method of manufacturing an artificial quartz crystal according to claim 1.