JP3367616B2 - Single crystal manufacturing method and single crystal manufacturing apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high quality single crystal manufacturing technique, and more specifically to a single crystal manufacturing method and a manufacturing apparatus therefor having few defects, a long crystal length, and a controllable crystal orientation. It is about.

[0002]

2. Description of the Related Art The following are the major conventional single crystal production methods. In FIG. 5, the Czochralski method (Cz
Method). In FIG. 5, the target material is heated and melted in the crucible 501 by the heating heater 502, and the seed crystal 504 is brought into contact with the liquid surface of the melt 505 so that the melting point of the crucible 501 is kept below the melting point. That is, the single crystal 503 is grown by pulling it toward the temperature region of.

In FIG. 6, the floating zone method (FZ
Method). In FIG. 6, the light from the heating light source 601 is reflected by the concave mirror 606 to form the base material 602.
Is condensed on the upper part of the substrate to form a fusion zone 605. Melting part 6
When the seed crystal 604 is brought into contact with 05 and the crystal base material 602 is moved at the speed V ₁ while moving the seed crystal at the speed V ₂ , a single crystal 603 is formed. Here, the orientation of the single crystal 603 matches the crystal orientation of the seed crystal. Also, the outer diameter D of the single crystal
₂ is represented by the formula: D ₂ = D ₁ × (V ₁ / V ₂ ) ^1/2 (1) Here, D ₁ is the outer diameter of the crystal base material. Furthermore, a single crystal fiber such as lithium niobate or sapphire whose growth orientation is controlled can be manufactured by a laser melting pedestal method (LHPG method) using a CO ₂ laser as a heating light source.

FIG. 7 shows the Bridgman-Stockburger method. This method uses a heater 702 for heating and a heat insulating material 7.
The heating furnace 701 constituted by 04 and 40 is kept above the melting point of the desired material. Then, after encapsulating this material in a growth container 706 made of quartz glass or the like, the growth container 70
6 is put in the heating furnace 701, the material is melted, and the melt 7
It will be 05. Subsequently, one end of the growth container 706 is attached to the heating furnace 7
From 01 to a region kept below the melting point of this material. Then, the single crystal 703 is grown.

FIG. 8 shows a solution temperature change method which is one of the solution growth methods. In this method, a saturated solution 8 in which a desired material is dissolved in an organic solvent, water, or the like is placed in a growth container 801.
02, in which microcrystals of the material are seed crystals 80
After adding as 4, the solution is slowly cooled. That is, the grown crystal 803 is obtained by utilizing the fact that the solubility varies depending on the temperature. In addition to this, as a solution growth method, there is a solvent evaporation method in which crystals are grown by evaporating the solvent of the saturated solution 802.

[0006]

In order to provide a single crystal material for an optical signal processing element or an optical storage element, a single crystal having a desired crystallization method and high crystal quality is required. There is a need to provide a single crystallization technique that takes into consideration the melting point, sublimability, and crystallinity of the material to be crystallized. However, in the above-described single crystallization technique, for a material that easily decomposes and has a sublimable property such as a crystal of a polymer material such as an organic material, the following will be applied to the production of a single crystal in which the growth direction is controlled. There is a problem.

That is, in the Cz method, sublimation from the surface of the melt occurs violently, and fine crystals adhere to seed crystals and the like, making continuous production of single crystals difficult. FZ method and L
Also in the HPG method, when the material is directly heated in spots by the local heating of the melting portion 605, unlike an inorganic material, an organic material undergoes high temperature sublimation and is difficult to produce a single crystal.

In the Bridgman-Stockburger method, although there is no problem of sublimation due to the existence of the growth vessel 706 as shown in the configuration of FIG. 7, it is difficult to control the crystal growth orientation, and the growth peculiar to the material. Only the azimuth can grow.

Further, in the solution growth method, as in the Bridgman-Stockburger method, there is a problem in controlling the growth orientation, and in addition, there are problems in the solvent intake and crystal polymorphism.

In view of the above problems, the present invention provides a single crystal manufacturing method and a single crystal manufacturing method capable of controlling sublimation and controlling the orientation, and obtaining a single crystal excellent in electrical characteristics and optical characteristics without defects and dislocations. I will provide a.

[0011]

[Means for Solving the Problems ] The above-mentioned problems are solved.
For the purpose of the single crystal production method according to the present invention, a crystal base material is inserted from one end of a straight pipe and a cooling gas is provided around the straight pipe.
While flowing, a part of the outer circumference of the straight tube in the axial direction was heated by infrared light irradiation, and the tip of the crystal base material was melted by radiant heat from the tube wall of the straight tube, and was inserted from the tube wall of the straight tube. It is characterized in that the seed crystal is brought into contact with the melting tip of the crystal base material, and the seed crystal is moved farther from the infrared light irradiation portion while moving the crystal base material closer to the infrared light irradiation portion .

Further, the method for producing a single crystal according to the present invention is
Insert the crystal base material from one end of the straight pipe and
An axis centered on the melting tip of the crystal matrix with the heater placed
Axial direction of the straight pipe while controlling the temperature gradient before and after along the direction
Part of the outer circumference is heated by infrared light irradiation,
The tip of the above crystal base material is melted by the radiant heat from the wall.
Therefore, the seed crystal inserted from the wall of the straight pipe is used as the crystal base material.
Of the above crystal base material to the infrared irradiation part.
Move the seed crystal farther from the infrared irradiation part while moving it closer.
It is characterized by being moved so that it can move smoothly.

Further, in the above-mentioned method for producing a single crystal,
It is characterized in that it is performed in a pressurized atmosphere .
It

[0014]

On the other hand, a book for solving the above-mentioned problems
An apparatus for producing a single crystal according to the present invention uses a straight tube for inserting a crystal base material and a seed crystal, and a part of the straight tube in the axial direction with infrared light.
A heating device for heating by irradiation, a moving device for moving the crystal base material and the seed crystal in the axial direction, and a gas flow around the straight pipe.
And having a ventilation device which give rise to.

Further , the single crystal production apparatus according to the present invention is
A straight pipe for inserting the crystal base material and the seed crystal, and this straight pipe
A heating device that heats a part of the axial direction by infrared light irradiation,
Moving device for moving the crystal base material and seed crystal in the axial direction
And a heater arranged around the straight pipe.
And

Furthermore, in the above-mentioned single crystal production apparatus,
Thus, the straight pipe is housed in the pressurizing chamber .

In addition, in the above single crystal production apparatus
The CO ₂ laser was used as the heating device .
It is characterized by

[0019]

[0020]

According to the above construction, the crystal base material is indirectly heated by the radiant heat from the straight tube heated by infrared light, and the orientation controllable FZ method is adopted. The uniform heating of the melted part can prevent sublimation and decomposition of the melted part. Moreover, even if it is called uniform heating, the temperature gradient is small like the heater heating, and the axial direction of the melted part is small. Since the length is large and the melted portion cannot be stably held by the surface tension, it is possible to partially heat the melted width by light irradiation.

Further, the temperature gradient along the axial direction of the straight pipe can be accurately controlled by flowing the cooling gas around the straight pipe together with the partial heating by the light irradiation, and the volume of the fusion zone can be controlled more accurately. , FZ method stabilizes the important fusion zone.

Further, by arranging the straight pipe in the pressurizing chamber filled with the pressurizing gas, the molten portion is formed under the pressurization, so that sublimation is further suppressed and the material having high vapor pressure is crystallized. Growth is possible.

Further, by arranging a heater around the straight pipe, it is more preferable to control the temperature gradient before and after the melting portion, and it becomes possible to grow crystals with good crystallinity.

[0024]

EXAMPLES Examples of the present invention will now be described with reference to FIGS. An example of producing the single crystal of the present invention is shown in FIG. FIG. 1 shows an embodiment in which radiant heat and cooling gas are used in combination. In FIG. 1, a part of the straight tube 106 made of quartz glass or the like in the axial direction is heated by infrared light 101. Straight pipe 1 due to radiant heat 107 from the high temperature portion of the straight pipe
The upper part of the base material 102 inserted in 06 is heated and melted. The melting portion 105 is brought into contact with the seed crystal 104 inserted in the straight pipe 106, the seed crystal 104 is moved at a speed V ₂ , and the base material 102 is moved at a speed V ₁ to draw a single crystal 103. It is made. In addition, single crystal 103
The outer diameter D _{2 of} is determined by the above equation (1). Single crystal 103
Has the same crystal orientation as that of the seed crystal 104. Further, by using CO ₂ laser light as infrared light and flowing a cooling gas 108 such as He around the straight pipe, only a very narrow range of the straight pipe is kept at a high temperature, and the heating and melting portion above the base material 102 is maintained. It is possible to reduce the volume of 105, which makes it easier to produce a single crystal of a material having low viscosity. Melting part 1
The size of 05 can be controlled by the power of the laser light 101, the flow rate of the gas 108, and the material and diameter of the straight pipe 106.
In addition, as a heating device for the straight tube 106 due to its structure, there is a condensing device using a lamp in addition to a laser oscillator.
The second moving device and the seed crystal 104 moving device are arranged.

FIG. 2 shows an embodiment in which the irradiation of infrared light 201, the cooling gas flow 208, and the storage in the pressurizing chamber 209 are used together. In FIG. 2, the seed crystal 204, the base material 202, and the straight pipe 206 are placed in the pressure chamber 209,
The chamber is filled with a high pressure inert gas. The rotation of the fan 210 creates a gas flow 208 around the straight pipe. Thereafter, as in FIG. 1, a part of the straight tube 206 in the axial direction is heated by the infrared light 201, and the base material 2 is heated by the radiant heat 207.
The upper part of 02 is melted by heating. The fusion crystal 205 is used as the seed crystal 20.
The single crystal 203 is produced by bringing the single crystal 203 into contact with 4 and drawing. In this example, the straight pipe 20 is introduced into the pressure chamber 209.
Since 6 is stored, the melting portion 205 is placed in the pressurized atmosphere, and thus sublimation is further suppressed.

FIG. 3 shows an embodiment in which the irradiation of infrared light 301, the cooling gas flow 308, and the installation of the heater 309 are used together. In FIG. 3, the infrared light 301 in the straight tube 306
A heater 309 is installed before and after the irradiation position of. The heater temperature is adjusted to control the temperature and the temperature gradient before and after the fusion zone 305 in the axial direction, and a part of the outer circumference of the straight pipe 306 is irradiated with infrared light 30.
1, and the upper part of the base material 302 is heated and melted by radiant heat 307. The single crystal 303 is produced by bringing the melted portion 305 into contact with the seed crystal 304 and drawing it.
By installing the heater 309, the temperature gradient in the axial direction other than the melting portion 305 can be gently changed, and high quality crystal growth can be performed.

The present invention is basically based on irradiation of a straight tube with infrared light, and even if ventilation of the cooling gas to the outer circumference of the straight tube, storage in a pressurizing chamber, or installation of a heater is added independently. It can also be used in any combination.

The materials for the base material used in this embodiment are as follows. That is, as a material, 3-nitroaniline (m-NA), 2-methyl-4-nitroaniline (MNA), 3-methyl- (2,4-dinitrophenyl) -aminopropanoate (MAP), 3 -Methyl-4-nitropyridine-1-oxide (POM), 3
-Aminophenyl (m-AP), 2-adamantylamino-5-nitropyridine (AANP), N- (4-nitrophenyl) -L-prolinol (NPP), N- (nitrophenyl) -N-methylamino Acetonitrile (N
PAN), 4-nitrodimethylaniline (NDMA),
4-N, N-dimethylamino-2-acetamide-4-nitroaniline (DAN), 2- (N-prolinol)-
5-nitropyridine (PNP), 2-cycloacetylamino-5-nitropyridine (COANP), 3,9-dinitro-5a, 6,11a, 12-tetrahydro-
[1,4] Benzoxazino [3,2-b] [1,4]
Benzoxazine (DNBB), 4'-nitrobenzylidene-3-acetamino-4-methoxyaniline (MN
BA), dicyanovinyl anisole (DIVA),
(-) 4- (4'-Dimethylaminophenyl) -3-
(2'-Hydroxypropylamino) cyclobutene-
3,4-dione (DAD), 2-methoxy-5-nitrophenol (MNP), stilbazolium-P-toluenesulfonic acid (SPTS), 3,5-dimethyl-1-
(4-nitrophenyl) pyrazole (DMNP), N-
Methoxymethyl-4-nitroaniline (MMNA) and the like.

As the material of the straight pipe, besides quartz glass, heat-resistant lead glass, soda-lime glass,
There are glass materials such as potassium lime glass, barium glass and borosilicate glass, polymer materials such as Teflon, silicon, Kepler and polyimide, ceramic materials and the like, and opaque materials are also possible. The cooling gas may be a rare gas such as helium or argon, nitrogen, oxygen or the like. In this case, helium, which has good thermal conductivity, is most effective.

Next, specific examples according to the present invention will be described. The specific example 1 is based on the method shown in FIG. 1, the specific example 2 is shown in FIG. 2, and the specific example 3 is based on the method shown in FIG.

Specific Example 1 A Pyrex glass glass tube (inner diameter 4 mm, wall thickness 1 mm) was used as a straight tube, helium gas (flow rate 15 l / min) as gas, and AANP solution solidified body (diameter 2 mmφ) as base material. Using a c-axis oriented crystal of the same crystal as a seed crystal, the pulling rate was 0.04 to 0.4.
A single crystal was prepared with a moving speed ratio of the seed crystal and the base material of 1 to 10 mm / min. Fabricated crystal is 2-0.6mmφ, length 2
A product of 0 mm was obtained. Further, under the same conditions, a single crystal was produced using a seed crystal having a crystal axis of 40 ° from the c-axis.
Consistency between the single crystallinity of these single crystals and the growth direction of the seed crystal was confirmed by an X-ray precession photograph, and the crystal orientation was also confirmed to match the seed crystal.

(Specific Example 2) The pressure chamber was filled with 3 atm of helium gas. A Pyrex glass tube (inner diameter: 4 mm, wall thickness: 1 mm) was used as the straight tube, and a gas flow of 0.25 m / sec was generated around the straight tube by a fan.
M-NA melt solidified body (diameter 2 mmφ) is used as the base material,
Using a c-axis oriented crystal of the same crystal as a seed crystal, a single crystal was produced with a pulling rate of 0.04 to 0.4 mm / min and a moving speed ratio of the seed crystal and the base material of 1 to 10. Although m-NA has a high sublimation property and could be manufactured only up to a length of 5 mm by the method shown in FIG. 1, by using the pressurizing chamber, a product having a diameter of 2 to 0.6 mmφ and a length of 20 mm was obtained.

(Specific Example 3) The heater temperature in FIG. 3 was adjusted so that a gentle temperature gradient other than the melted portion as shown in FIG. 4 could be obtained without the heater. Other conditions were the same as in Example 1 to prepare an AANP single crystal. As a result, in the presence of the heater, the heat escape by the CO ₂ laser was reduced, the laser power was reduced to 1/3, and the occurrence of cracks in the single crystal due to the rapid temperature change was reduced by about 1/10.

Table 1 shows the results when the above-mentioned materials were manufactured according to the present invention.

[0035]

[Table 1] In each case, a high quality single crystal having the same orientation as the seed crystal was obtained. In addition, as a ventilation device which is a supply source of the cooling gas, an opening of a gas cylinder or a fan is used.

[0036]

As described above, according to the present invention, in the FZ method in which the orientation can be controlled by using the seed crystal, the indirect heating using the radiant heat from the straight tube heated by the infrared light is performed. By doing so, it suppresses sublimation and enables crystal growth of the highly sublimable material with controlled orientation. Further, in the present invention, a CO ₂ laser is further used as an infrared light source, and a more stable crystal having a good temperature gradient in a narrow and uniform heating range is provided by flowing a gas around the straight tube. Allows fabrication. Further, in the present invention,
Furthermore, the use of a pressure chamber with an inert gas further suppresses sublimation, and enables crystallographic growth of highly sublimable materials in a controlled orientation. In addition to the infrared heating device,
By controlling the temperature and temperature gradient by the heater, crystal growth is facilitated and crystal growth with good crystallinity is enabled. Thus, by using the single crystal manufacturing method in which indirect heating is performed via a straight tube, for a material with high sublimability, a part of the base material is melted by using infrared light, and an arbitrary crystal is formed by using a seed crystal. It has become possible to produce oriented crystals. In particular, since the volume and surface area of the heating and melting part can be reduced as compared with the conventional Cz method using a seed crystal, the influence of sublimation can be suppressed. In addition, since the volume of the fusion zone is small, the time required for the material to stay above the melting point can be shortened as compared with the conventional Bridgman method and Cz method.
This is advantageous for producing a single crystal of a material that is easily decomposed by heat. Such a technique is expected to be applied to optical devices such as optical non-linear effects, but especially for the production of single crystals of organic materials, which have been difficult to produce in any orientation due to its high sublimability. It is advantageous.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a method for producing a single crystal according to the present invention.

FIG. 2 is a schematic view showing another embodiment of the method for producing a single crystal according to the present invention.

FIG. 3 is a schematic view showing still another embodiment of the method for producing a single crystal according to the present invention.

FIG. 4 is a diagram showing a temperature gradient generated in a straight tube by using a combination of infrared light and a heater in the method for producing a single crystal according to the present invention.

FIG. 5 is a diagram showing a conventional single crystal production method by the Czochralski method.

FIG. 6 is a diagram showing a conventional single crystal production method by a floating zone method.

FIG. 7 is a diagram showing a conventional single crystal production method by the Bridgman-Stockburger method.

FIG. 8 is a diagram showing a conventional single crystal production method by a solution growth method.

[Explanation of symbols]

101, 201, 301 Infrared light 601 Heating light source 501 Crucible 701 Heating furnace 801 Growth vessel 102, 202, 302, 602 Base material 502, 702 Heating heater 802 Saturated solution 103, 203, 303, 503, 603, 703 Single Crystal 803 Growth crystal 104, 204, 304, 504, 604, 804 Seed crystal 704 Heat insulating material 105, 205, 305, 605 Melting part 505, 705 Melt liquid 106, 206, 306 Glass tube 606 Concave mirror 706 Growth container 107, 207, 307 radiant heat 108,308 He gas 208 gas flow 209 pressurizing chamber 309 heater 210 fan

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroki Ito 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (72) Inventor Toshikuni Kaino 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo Japan (56) References JP-A-3-88790 (JP, A) JP-A-61-58880 (JP, A) JP-A-60-205178 (JP, A) JP-A-5-341139 ( (58) Fields investigated (Int.Cl. ⁷ , DB name) C30B 12/00 C30B 29/54

Claims (7)

(57) [Claims] 1. A crystal base material is inserted from one end of a straight pipe, and a part of the straight pipe in the axial direction is heated by infrared light irradiation while flowing a cooling gas around the straight pipe, and the straight pipe is heated. The tip of the crystal base material is melted by radiant heat from the tube wall, the seed crystal inserted from the tube wall of the straight tube is brought into contact with the melting tip of the crystal base material, and the crystal base material is irradiated with infrared light. A method for producing a single crystal in which a seed crystal is moved farther from an infrared light irradiation part while being moved closer. 2. When the crystal base material is inserted from one end of the straight pipe,
Where the crystal base material is melted by the heater placed around the straight pipe.
Controls the temperature gradient before and after along the axial direction centered on the edge.
Heat the part of the straight tube in the axial direction by irradiating infrared light.
However, the radiant heat from the wall of the straight pipe causes the crystal base material to
Seed crystal with the tip melted and inserted from the wall of the above straight pipe
To the melting tip of the crystal base material,
The seed crystal is moved to the infrared light irradiation section while moving toward the infrared
A single crystal manufacturing method in which the single crystal is moved away from the light irradiation part. 3. The method for producing a single crystal according to claim 1, wherein the single crystal is produced in a pressurized atmosphere. 4. A straight line for inserting a crystal base material and a seed crystal.
The tube and part of this straight tube in the axial direction are heated by infrared light irradiation.
Heating device and the above crystal base material and seed crystal in the axial direction.
The moving device to move and the passage that creates the gas flow around the straight pipe.
An apparatus for producing a single crystal having a wind device. 5. A straight pipe for inserting a crystal base material and a seed crystal, a heating device for heating a part of the straight pipe in the axial direction by infrared light irradiation , and a shaft for the crystal base material and the seed crystal. An apparatus for producing a single crystal having a moving device for moving in a direction and a heater arranged around a straight pipe . 6. A straight pipe is housed in a pressure chamber.
The single crystal production apparatus according to claim 4 or 5. 7. A CO ₂ laser is used as the heating device.
The single crystal production apparatus according to claim 4, wherein