JPH1192270A - Apparatus for producing crystal and production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a simple structural apparatus for producing a crystal, capable of producing the crystal in high quality and having a large diameter, and further to provide a producing method thereof. SOLUTION: This apparatus for producing a crystal is capable of growing a crystal by heating and melting a crystalline material in a cylindrical crucible 1 by a side face heater 3 and cooling the melted crystalline material by taking down the crucible to crystallize the crystalline material. The crystal producing apparatus has a rotating structure of the side face heater 3, installed for rotating the side face heater 3. The method for producing the crystal comprises heating and melting the crystalline material in the cylindrical crucible by the side face heater 3, and cooling the crystalline material by taking down the crucible to crystallize the crystalline material. The crystallization is carried out by taking down the crucible while rotating the side face heaters without rotating the crucible and cooling the crystalline material to crystallize the material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal manufacturing apparatus and a crystal manufacturing method for manufacturing a crystal material (glass material) such as quartz or fluorite used for an optical member such as a lens.

[0002]

2. Description of the Related Art Optical members are used in telescopes, cameras, exposure apparatuses for manufacturing semiconductor integrated circuits, and the like.
In particular, a high quality optical member is desired for an exposure apparatus.

[0003] In recent years, with the increasing integration of semiconductor integrated circuits,
There is an increasing demand for ultrafine pattern formation. As an apparatus for transferring a fine pattern onto a wafer, a step-and-repeat small-size projection exposure apparatus (stepper) is often used. In order to achieve high integration, it is necessary to increase the resolution of the stepper projection lens. To increase the resolution of the projection lens, it is necessary to use exposure light of a short wavelength and increase the numerical aperture of the projection lens (increase the diameter).

The short wavelength of the exposure light is g-line (wavelength 43
6 nm), h-line (wavelength 405 nm), i-line (wavelength 365)
nm), and the use of Kr-F excimer laser light (wavelength 248 nm) and Ar-F excimer laser light (wavelength 193 nm) is expected to be promising in the future.

In the wavelength range up to the i-line, it is possible to use a conventional optical lens in the optical system, but in the wavelength range of Kr-F excimer laser light and Ar-F excimer laser light, the transmittance is low. Low, it is not possible to use conventional optical glass.

For this reason, it is common to use quartz glass or fluorite having a high transmittance for short-wavelength light in the optical system of the excimer laser exposure apparatus.

On the other hand, in order to correct the chromatic aberration of the optical system, it is desirable to have two or more glass materials having different refractive indexes.

Further, each lens constituting the stepper projection lens is polished with the ultimate surface precision. However, since the polishing rate differs depending on the crystal orientation in the case of polycrystal, it is necessary to ensure the lens surface precision. It becomes difficult.

Further, in the case of polycrystal, impurities are easily segregated at the crystal interface, and the uniformity of the refractive index is impaired, and a tendency is caused by laser irradiation.

For these reasons, a large diameter single crystal fluorite is desired for a projection lens of an excimer laser exposure apparatus.

For example, fluorite is conventionally manufactured by a crucible pulling-down method (Bridgeman method), and the manufacturing apparatuses thereof include a one-chamber type shown in FIG. 5 and a two-chamber type shown in FIG. , 214, 976). FIG. 5 is a schematic sectional view of a conventional one-chamber type crystal manufacturing apparatus.
This apparatus mainly includes a housing 5 forming a furnace chamber 6 and a graphite side heater 3 arranged in the furnace chamber. The side heater 3 is supplied with electric power from a side heater power supply 8, and the electric power is supplied to the heater controller 9.
Is controlled by

The upper part of the crucible support rod 2 reaches the furnace chamber 6 through the bottom of the housing 5, and the crucible 1 is mounted on the upper end of the crucible support rod 2. The raw material is put into the crucible 1, the inside of the furnace chamber 6 is evacuated, and the furnace temperature is set to the melting point of fluorite or more (normally 1390 to 1 Celsius).
Raise to 450 degrees) and melt. When growing crystals,
The crucible 1 is lowered at a speed of about 0.1 to 5 mm / hour,
Crystallize from the bottom.

FIG. 6 is a schematic sectional view of a conventional two-chamber type crystal manufacturing apparatus. The graphs on the right side of FIGS. 5 and 6 show the temperature along the vertical direction at the center of the furnace. In the case of the one-chamber type, the temperature distribution along the center of the furnace is one as shown on the right side of FIG. Fig. 6 for the two-room type, while the shape is mountain-shaped.
As shown on the right side of FIG.

In order to produce a high-quality single crystal, there are several points to be taken into consideration, such as reducing the crystal growth rate, smoothing the inner surface of the crucible, and setting the starting point of the crystal at one point at the bottom of the crucible.

The present inventors have found that it is important to keep the isotherm of the melting point (corresponding to the solid-liquid interface) as horizontal as possible in the temperature distribution of the crystal solution.

In the apparatus as shown in FIGS. 5 and 6, a temperature difference is generated between the vicinity of the furnace wall of the crystal melt and the center thereof due to the large diameter of the projection lens and thus the crucible, and the temperature distribution is controlled. It becomes difficult. As a countermeasure, an apparatus has been proposed in which a heater is added to the upper or lower part of the furnace liquid to control the temperature (see JP-A-4-34198 and JP-A-4-349199). However, such devices have a complicated structure.

As a simple method, the structure of the crucible was devised to improve the temperature distribution of the crystal solution.
There is a type (disk type) divided into a plurality of areas by the partition plate 1a as shown in FIG. (Cheredov V.
N. , Nieorgany Cesky material, No.
3, vol. 28, (1992) 550).

In FIG. 7, the crucible 1 is divided into three regions 7. The regions 7 communicate with each other via the central hole 1b of the partition plate 1a of the upper and lower crucibles, and proceed to the upper part of the crucible 1.

As a result of a detailed study by the present inventors, FIG.
Also in the conventional example, the temperature distribution of the solution near the melting point of the fluorite does not keep the isotherm sufficiently horizontal in the temperature distribution of the crystal solution, and high-quality crystals, particularly crystals having a large diameter (for example, 250 mm or more in diameter). Is difficult to obtain.

Further, as the diameter increases, a temperature difference also occurs in the cross section of the crucible, and it becomes difficult to control the temperature distribution. Some countermeasures include a mechanism for rotating a crucible as shown in FIG. In FIG. 8, the crucible 1 and the crucible support rod 2 are rotated by a crucible rotation motor 2c. The motor for rotating the crucible is supplied with power from a power source 2d for rotating the crucible, and the power is controlled by the rotation control device 13.

[0021]

However, as a result of a detailed study conducted by the present inventor, even in the conventional example shown in FIG. 8, the crystal growth stripes are not horizontal, and a high-quality large-diameter (for example, 250
(Millimeters or more) was difficult to obtain.

The present inventors have clarified that the cause is that vibration occurs when the crucible is rotated and the crucible does not become horizontal.

An object of the present invention is to provide an apparatus and a method for producing a crystal having a simple structure and capable of producing a high-quality large-diameter crystal.

[0024]

According to the present invention, there is provided a crystal manufacturing apparatus, wherein a crystalline material in a cylindrical crucible is heated and melted by a side heater, and the crystalline material is cooled by pulling down the crucible to crystallize. The apparatus for producing a crystal according to claim 1, further comprising a side heater rotating mechanism for rotating the side heater.

In the method for producing a crystal according to the present invention, the crystalline material in the cylindrical crucible is heated and melted by a side heater.
In a crystal manufacturing method for cooling and crystallizing the crystalline material by pulling down a crucible, the crystal material is cooled and crystallized by rotating the side heater without rotating the crucible without rotating the crucible. It is characterized by.

Another crystal manufacturing apparatus of the present invention is a crystal manufacturing apparatus in which a crystalline material in a cylindrical crucible is heated and melted by a side heater, and the crystalline material is cooled and crystallized by pulling down the crucible. Wherein a cylindrical heat equalizing cylinder and a heat equalizing cylinder rotating mechanism for rotating the heat equalizing cylinder are provided between the tub and the side heater.

Another crystal production method of the present invention is a crystal production method in which a crystalline material in a cylindrical crucible is heated and melted by a side heater, and the crystalline material is cooled and crystallized by pulling down the crucible. In the above, a soaking cylinder is provided between the crucible and the side heater, and the crucible is rotated while rotating the soaking cylinder without rotating, so that the crystalline material is cooled and crystallized. I do.

[0028]

According to the present invention, the amount of heat applied directly or indirectly from the side heater to the upper surface of the crucible can be kept constant, and the solid-liquid interface of the melting point can be kept horizontal in the temperature distribution of the crystal solution. . As a result, high-quality, large-diameter crystals can be obtained. Hereinafter, the operation of the present invention will be described in detail.

FIG. 9 is a schematic diagram for explaining the heat flow of a conventional one-chamber type crucible. FIG. 10 is a schematic diagram for explaining the heat flow of a conventional disk-type crucible. In this figure, considering the heat transfer state in the crucible,
The crystal solution receives heat mainly from the crucible 1 in the crystal manufacturing apparatus shown in FIG. 9 by heat conduction, and also receives heat from the partition plate 1a in the crucible 1 in the disk type crystal manufacturing apparatus shown in FIG. In addition, the crucible 1 is moved from the side heater 3 to the crucible 1.
Heat is applied to the top and side surfaces of the device by radiation. Heat is taken away from the lower surface of the crucible 1 to the space below by radiation, and from the lower part of the crucible 1 to the crucible support bar 2 by conduction.

Eventually, the temperature distribution in the crystal solution is such that the heat transfer from the side heater 3 to the upper surface of the crucible 1 is Q ₁ , the heat transfer from the side heater 3 to the side of the crucible 1 is Q ₂ , Assuming that the downward heat conduction is Q ₃ , it is determined by the overall balance of Q ₁ , Q ₂ , and Q ₃ .

When the crucible 1 is horizontal, the isothermal line 15 becomes symmetrical with respect to the center of the crucible 1, resulting in horizontal crystal growth stripes 16 as shown in FIG.

However, when the crucible 1 is tilted, the crystal solution causes a tilted isothermal line as shown in FIG. As a result, the crystal growth stripes have an inclined shape as shown in FIG. 13 or a convex shape as shown in FIG.
The above analysis was performed by the present inventor for the first time.

In the present invention, the above-mentioned problem of the inclination of the crucible 1 is solved by rotating the side heater 3 and not rotating the crucible 1 instead. If the crucible is not rotated, the vibration of the crucible 1 can be significantly reduced. In addition, since the side heater 3 rotates, the temperature distribution in the cross section of the crucible 1 can have a symmetrical temperature distribution with respect to the center of the crucible 1. Therefore, according to the present invention, it becomes possible to manufacture a large diameter single crystal optical material.

Further, a soaking tube 11 is provided between the crucible 1 and the side heater 3, and the soaking tube 11 is rotated. The heat generated from the side heater 3 is transmitted to the soaking tube 11 by radiation, and further transmitted from the soaking tube 11 to the crucible 11. Here, since the heat equalizing cylinder 11 is rotating, the temperature distribution in the cross section of the crucible 1 can have a symmetrical temperature distribution with respect to the center of the crucible 1. Therefore, according to the present invention, it becomes possible to manufacture a large-diameter crystal optical material.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples, as long as the object of the present invention is achieved. Each component may be replaced with a substitute.

An embodiment of the present invention will be described below with reference to the drawings. The region for accommodating the raw materials in the apparatus of the illustrated embodiment may be other than that illustrated.

(First Embodiment) FIG. 1 is a schematic sectional view of a crystal manufacturing apparatus according to a first embodiment of the present invention.

The first embodiment is an embodiment having a side heater rotating mechanism for rotating the side heater.

The crystal manufacturing apparatus shown in FIG. 1 comprises a casing 5 forming a furnace chamber 6 and a side heater 3 made of, for example, graphite and arranged in the furnace chamber 6. In this example, the side heater 3 has a cylindrical shape whose top and bottom are open. Electric power is supplied from a side heater power supply 8 to the side heater 3. Although not specifically shown here, the electrode of the side heater to which power is supplied uses a brush, and the contact positions of the brush and the side heater are located at the upper end and the lower end of the side heater. It is a mechanism that can always supply constant power. The electric power is controlled by the heater control device 9.

The crucible 1 is made of, for example, graphite or platinum. A side heat insulating member 4 made of graphite whose surface is polished well is installed inside the housing 5 to protect the housing 5 from high heat.

The housing 5 is a double cylinder made of stainless steel, and a heat insulating member (not shown) is provided between the cylinders.

A crucible support rod 2 is provided so as to penetrate the housing 5 from the lower part of the housing 5 and supports the crucible 1. The crucible elevating motor 2a is supplied with electric power from a crucible elevating power supply 2b, and the electric power is controlled by the elevating controller 12.

Outside the lower portion of the side heater, a side heater rotating shaft 10 is provided. A side heater rotating shaft 10 is provided so as to be in contact with the lower outside of the side heater. The side heater 3 is rotated by a side heater rotation motor 3b. The side heater rotation motor 3b is supplied with electric power from the side heater rotation power supply 8a, and the electric power is controlled by the elevation control device 13.

If necessary, a side heater rotating shaft heat insulating member 10b is provided as a heat insulating means in a part of the side heater rotating shaft 10, and the heat is transmitted from the side heater 3 to the side heater rotating shaft 10 and discharged to the outside of the furnace chamber 6. Limit the amount of heat that can be applied.

As the heat insulating member, MgO, ceramic,
Metal mesh, heat-resistant brick, and porous carbon are preferred. Further, each combination of MgO, ceramic, metal mesh, heat-resistant brick, and porous carbon may be used.

In this crystal manufacturing apparatus, since the crucible 1 does not rotate, the crucible 1 does not vibrate and the crucible 1 can always be kept horizontal. Therefore, high-quality large-diameter (250 mm or more) crystals can be produced. Further, heat insulating members may be provided above and below the furnace chamber 6 as necessary.

(Second Embodiment) FIG. 2 is a schematic cross-sectional view of a crystal manufacturing apparatus according to a second embodiment of the present invention. The second embodiment is the same as the first embodiment, except that the inside of the crucible 1 is divided into a plurality of regions 7 by a partition plate 1a. Other points are the same as in the first embodiment.

In the present embodiment, since the inside of the crucible 1 is divided into a plurality of regions by the partition plate 1a, the temperature distribution in the horizontal direction becomes more uniform, and a more uniform high-quality, large-diameter crystal can be manufactured.

(Third Embodiment) FIG. 3 is a schematic sectional view of a crystal manufacturing apparatus according to a third embodiment of the present invention. In the third embodiment, a soaking tube 11 having a rotation mechanism is provided between the side heater 3 and the crucible 1.

That is, a soaking tube 11 is provided between the crucible 1 and the side heater 3. The soaking cylinder 11 is made of graphite or platinum. A heat equalizing cylinder rotating shaft 14 is provided below the heat equalizing cylinder, and the heat equalizing cylinder 11 is rotated by a heat equalizing cylinder rotating motor 14a. Motor 1 for rotating the soaking cylinder
4 a is supplied with electric power from the power supply for boiler 14 b, and the electric power is controlled by the rotation control device 13.

If necessary, a part of the rotary shaft 14 for heat equalizing cylinder may be used as a heat insulating means.
c to limit the amount of heat released from the heat equalizing cylinder 11 to the outside of the furnace through the rotary shaft of the heat equalizing cylinder. Other points are the first
The description is omitted because it is the same as that of the first embodiment.

In this crystal production apparatus, heat is applied to the crucible indirectly through the soaking tube 11. Further, since the crucible 1 does not rotate, the crucible 1 does not vibrate and the crucible is always kept horizontal. Therefore, the temperature distribution can be kept even more uniform. Further, heat insulating members may be provided above and below the furnace chamber 6 as necessary.

(Fourth Embodiment) FIG. 4 is a schematic sectional view of a crystal manufacturing apparatus according to a fourth embodiment of the present invention. The fourth embodiment is the same as the third embodiment, except that the inside of the crucible 1 is divided into a plurality of regions 7 by a partition plate 1a.

If necessary, the heat equalizing cylinder rotating shaft 14 has a heat equalizing cylinder rotating shaft heat insulating member 14c at a part thereof.
The amount of heat released from the heat equalizing cylinder to the outside of the furnace through the rotary shaft of the heat equalizing cylinder is limited. In this apparatus, since the crucible 1 does not rotate, the crucible does not vibrate, and the crucible can always be kept horizontal. Further, heat insulating members may be provided above and below the furnace chamber 6 as necessary.

[0055]

As described above, according to the present invention,
With a simple method of installing a rotating mechanism on the side heater, the crucible can be kept horizontal while maintaining a symmetrical temperature distribution with respect to the center of the crucible in the temperature distribution in the cross section of the crucible. Crystals such as fluorite can be produced.

Further, according to the present invention, the temperature distribution in the crucible cross-section can be adjusted with respect to the center of the crucible by a simple method of installing a soaking tube having a rotating mechanism between the top of the crucible and the side heater. Since the crucible can be kept horizontal while having a symmetrical temperature distribution, it is possible to produce high-quality crystals such as large-diameter fluorite.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view of a manufacturing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic vertical sectional view of a manufacturing apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic vertical sectional view of a manufacturing apparatus according to a third embodiment of the present invention.

FIG. 4 is a schematic vertical sectional view of a manufacturing apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a schematic vertical sectional view of a conventional one-chamber type / block type “crucible descent method manufacturing apparatus”.

FIG. 6 is a schematic vertical sectional view of a conventional two-chamber type / block type “crucible descent method manufacturing apparatus”.

FIG. 7 is a schematic vertical sectional view of a disk type “crucible descent method manufacturing apparatus”.

FIG. 8 is a schematic vertical sectional view of a disk type “crucible descent method manufacturing apparatus” equipped with a conventional crucible rotation mechanism.

FIG. 9 is a schematic diagram showing the flow of heat in a conventional block type crucible.

FIG. 10 is a schematic diagram showing the flow of heat in a conventional disk-type crucible.

FIG. 11 is a schematic diagram of horizontal crystal growth stripes.

FIG. 12 is a schematic diagram of an isothermal line of a crystal solution in a tilted crucible.

FIG. 13 is a schematic view of a tilted crystal growth stripe.

FIG. 14 is a schematic diagram of a downward convex crystal growth stripe.

[Description of Signs] 1 crucible, 1a crucible partition plate, 1b hole, 2 crucible support rod, 2a crucible lifting motor, 2b power supply for crucible lifting motor, 2c crucible rotation motor, 2 power supply for crucible rotation, 3 side heater, 3b side surface Heater rotation motor, 4 side heat insulation member, 5 housing (chamber), 6 furnace room, 7 area, 8 side heater heating power supply, 8a side heater rotation power supply, 9 heater control device, 10 side heater rotation shaft, 11 Side heater rotating shaft heat insulating member, 12 elevation control device, 13 rotation control device, 14 equalizing cylinder rotating shaft, 14a equalizing cylinder rotating motor, 14b power supply for equalizing cylinder rotation, 14c equalizing cylinder rotating shaft heat insulating member, 15 etc. Temperature line, 16 crystal growth fringes.

Claims (24)

[Claims] 1. The crystalline material in a cylindrical crucible is heated and melted by a heater provided at one or more of upper, lower and side surfaces, and is cooled by lowering the crucible. 1. A crystal manufacturing apparatus, comprising: a side heater rotating mechanism for rotating said side heater, wherein said crystal manufacturing apparatus is configured to perform crystallization. 2. The side heater rotating mechanism includes a side heater rotating shaft provided at one or more of an upper portion, a lower portion, and a side portion of the side heater, and a rotating motor for rotating the rotating shaft. The crystal manufacturing apparatus according to claim 1, wherein: 3. The crystal manufacturing apparatus according to claim 2, wherein at least one section of said side heater rotating shaft is made of heat insulating means. 4. The apparatus according to claim 3, wherein the heat insulating member is a heat insulating member. 5. The heat insulating member is made of MgO, ceramic,
The crystal manufacturing apparatus according to claim 4, wherein the apparatus is made of a material selected from a metal mesh, a heat-resistant refractory brick, and porous carbon. 6. The heat insulating member is made of MgO, ceramic,
The crystal manufacturing apparatus according to claim 4, wherein the apparatus is made of a material selected from a combination of a metal mesh, a heat-resistant refractory brick, and porous carbon. 7. The crystal manufacturing apparatus according to claim 1, wherein the crucible has only one area for accommodating the raw material. 8. The crystal production apparatus according to claim 1, wherein the crucible includes a partition plate, and a region for accommodating the raw material is divided into a plurality of regions. 9. The crystal manufacturing apparatus according to claim 8, wherein at least one of the partition plates has a hole in the center, and the upper and lower regions communicate with each other through the hole. 10. The apparatus according to claim 1, wherein the crystalline substance is fluorite. 11. A method for producing a crystal in which a crystalline substance in a cylindrical crucible is heated and melted by a side heater, and the crystalline substance is cooled and crystallized by pulling down the crucible, wherein the crucible is rotated. A method for producing a crystal, comprising: lowering a crystal while rotating the side heater to cool the crystalline substance; 12. The method according to claim 11, wherein the crystalline substance is fluorite. 13. A crystal manufacturing apparatus for heating and melting a crystalline material in a cylindrical crucible by a side heater and cooling the crystalline material by pulling down the crucible, wherein the crucible and the side heater A crystal manufacturing apparatus, comprising: a cylindrical soaking cylinder; and a soaking cylinder rotating mechanism for rotating the soaking cylinder. 14. The soaking cylinder rotating mechanism rotates the soaking cylinder rotating shaft and the soaking cylinder rotating shaft provided at one or more of upper, lower and side portions of the soaking cylinder. 14. The crystal production apparatus according to claim 13, comprising a rotation motor for the purpose. 15. The heat equalizing cylinder rotating shaft according to claim 14, wherein at least one section comprises a heat insulating means.
The crystal manufacturing apparatus according to the above. 16. The crystal manufacturing apparatus according to claim 15, wherein said heat insulating member is a heat insulating member. 17. The crystal manufacturing apparatus according to claim 16, wherein the heat insulating member is made of a material selected from MgO, ceramic, metal mesh, heat-resistant refractory brick, and porous carbon. 18. The crystal manufacturing apparatus according to claim 16, wherein the heat insulating member is made of a material selected from a combination of MgO, ceramic, metal mesh, heat-resistant refractory brick, and porous carbon. 19. The crucible according to claim 13, wherein the crucible has only one area for accommodating the raw material.
9. The crystal production apparatus according to any one of items 8 to 8. 20. The crystal production apparatus according to claim 13, wherein the crucible has a partition plate, and a region for accommodating the raw material is divided into a plurality of regions. 21. The crystal manufacturing apparatus according to claim 20, wherein at least one of the partition plates has a hole in the center, and the upper and lower regions communicate with each other through the hole. 22. The apparatus according to claim 13, wherein the crystalline substance is fluorite. 23. A method for producing a crystal in which a crystalline material in a cylindrical crucible is heated and melted by a side heater, and the crystalline material is cooled and crystallized by pulling down the crucible. A method for producing a crystal, comprising: providing a soaking tube between them, and lowering while rotating the soaking tube without rotating the crucible to cool the crystalline substance to crystallize. 24. The method according to claim 23, wherein the crystalline substance is fluorite.