WO2017018397A1

WO2017018397A1 - Sapphire single-crystal ribbon and method for producing same

Info

Publication number: WO2017018397A1
Application number: PCT/JP2016/071788
Authority: WO
Inventors: 古滝　敏郎; 佐藤　次男; 高橋　正幸
Original assignee: 並木精密宝石株式会社
Priority date: 2015-07-27
Filing date: 2016-07-26
Publication date: 2017-02-02

Abstract

[Problem] To provide: a flexible sapphire single-crystal ribbon which is resistant to tensile stress and for which cracking or breaking is prevented; and a method for producing same. [Solution] Dies that have a slit and are arranged so as to have parallel width directions are accommodated in a crucible. An aluminum oxide raw material is fed into the crucible and heated. The aluminum oxide raw material is melted in the crucible to prepare an aluminum oxide melt. Via the slits, an aluminum oxide melt reservoir is formed in a slit upper section. A seed crystal is brought into contact with the aluminum oxide melt at the slit upper part, and the seed crystal is drawn up, to thereby grow a sapphire single-crystal ribbon of a flexible as-grown single crystal having desired principal surface and longitudinal direction dimensions. This causes the surface of the grown and formed sapphire single-crystal ribbon to be free of micro-cracks.

Description

Sapphire single crystal ribbon and manufacturing method thereof

The present invention relates to a sapphire single crystal ribbon and a method for producing the sapphire single crystal ribbon.

Superconductors are brought into a state of zero electrical resistance by being maintained at a temperature lower than the critical temperature. Using this characteristic, for example, generation of a high magnetic field or high-density transmission of a large capacity current has been attempted. . Conventionally, metal-based, compound-based, and oxide-based materials are known as superconductors, and among these superconductors, the critical temperature at which the oxide-based material exhibits a superconducting state can be increased.

For example, by forming such a superconductor into a long strip (ribbon) having dimensions in the longitudinal direction, it can be used for power transmission / distribution, various devices, electrical connection between elements, AC winding, etc. Can be used. As a method for forming an oxide superconductor into a strip-like body, a method is known in which an oxide superconducting layer is formed on the surface of a base substrate having a longitudinal dimension.

Sapphire single crystal is required as the ribbon of the base material. The reason is that the ribbon is provided with high electrical resistance, thermal conductivity, and electrical insulation by producing the ribbon from sapphire single crystal. If the laminated superconductor is in a superconducting state, the electric resistance becomes zero, and a current can be passed through the superconductor composed of the base substrate and the superconductor layer. Furthermore, a configuration is disclosed in which a superconductor including the sapphire single crystal ribbon is bent to be wound in a coil shape (see, for example, Patent Document 1).

Japanese Patent No. 5233011

However, Patent Document 1 discloses a configuration in which a superconductor including a sapphire single crystal ribbon is wound. However, since a sapphire single crystal has low resistance to tensile stress, the sapphire single crystal ribbon is bent and wound. It was difficult to do. When the present applicant actually produced and wound a superconductor provided with a sapphire single crystal ribbon, it was found that the sapphire single crystal ribbon was cracked and broken.

When the present applicant verified the reason why the sapphire single crystal ribbon was weak against tensile stress, it was found that the micro cracks on the surface of the sapphire single crystal ribbon induced cracking and destruction. The microcracks are formed innumerably on the surface of the sapphire single crystal by abrasive grains, a grinding machine, or the like when surface processing such as grinding or polishing is performed after the sapphire single crystal is grown in a ribbon shape. The present applicant has found that cracks and breakage are caused by the progress of cracks inside the sapphire single crystal from the microcracks.

Therefore, the present applicant has found through verification that it is important to have resistance against tensile stress and to suppress the progression of microcracks.

The present invention has been made in view of the above circumstances, and has an object to provide a sapphire single crystal ribbon that has resistance to tensile stress, is prevented from being broken or broken, and has flexibility, and a method for manufacturing the same. To do.

The above-mentioned problem is solved by the following present invention. That is, the sapphire single crystal ribbon of the present invention has a longitudinal dimension and is flexible.

In the method for producing a sapphire single crystal ribbon according to the present invention, a die having slits and arranged in parallel in the width direction is housed in a crucible, and an aluminum oxide raw material is charged into the crucible and heated to obtain an aluminum oxide raw material. Prepare an aluminum oxide melt by melting in a crucible, form an aluminum oxide melt pool at the upper part of the slit through the slit, and pull the seed crystal by bringing the seed crystal into contact with the aluminum oxide melt at the upper part of the slit. A sapphire single crystal ribbon having a desired main surface and a longitudinal dimension and having flexibility is grown.

The ribbon shape of the sapphire single crystal ribbon is a rectangular shape in the plane direction, and specific dimensions are a width of 100 mm or less, a thickness of 0.5 mm or less, and a length in the longitudinal direction of 1000 mm or more. Refers to a sapphire single crystal of size.

Note that it is preferable to simultaneously grow a plurality of sapphire single crystal ribbons from a common seed crystal because it is possible to reduce the manufacturing cost of one sapphire single crystal ribbon. When simultaneously manufacturing a plurality of sapphire single crystal ribbons, a plurality of dies are accommodated in a crucible and the width directions of the dies are arranged in parallel.

According to the present invention, microcracks are formed on the surface of a sapphire single crystal by growing a sapphire single crystal ribbon so as to have a longitudinal dimension, and further by not performing surface processing such as grinding or polishing. Is prevented. By not having microcracks on the surface, the progress of microcracks is prevented, and the sapphire single crystal ribbon is provided with resistance to tensile stress and flexibility, and cracking and destruction are prevented.

Further, the As-grown single crystal of the sapphire single crystal ribbon grown to have a dimension in the longitudinal direction is not subjected to surface processing such as grinding or polishing, and the As-grown has no microcracks formed on the surface. By selecting a single crystal, flexibility can be imparted to the sapphire single crystal ribbon, and the surface processing steps can be reduced.

Furthermore, by selecting an As-grown single crystal that is not subjected to surface processing such as grinding or polishing and has no microcracks formed on the surface, the progress of microcracks is prevented and resistance to tensile stress is provided. , Cracking and destruction are prevented.

As described above, the sapphire single crystal ribbon of the present invention can be bent or wound by applying an external force.

It is a perspective view showing typically a sapphire single crystal ribbon concerning an embodiment and an example of the present invention. It is a schematic conceptual diagram which shows thickness T and the fluctuation range (DELTA) T of thickness of the sapphire single crystal ribbon which concern on embodiment and the Example of this invention. It is a side view showing a superconductor provided with a sapphire single crystal ribbon concerning an embodiment and an example of the present invention. FIG. 4 is a schematic diagram partially showing a superconducting coil formed by bending the superconductor of FIG. 3. It is a block diagram which shows schematically and the manufacturing apparatus of the sapphire single crystal ribbon by EFG method schematically. (A) It is a top view which shows typically an example of the die | dye which concerns on embodiment of this invention. (B) It is a front view of the same figure (a). (C) It is a side view of the same figure (a). (A) It is explanatory drawing which shows an example of the seed crystal which concerns on embodiment of this invention. (B) It is explanatory drawing which shows the other example of the seed crystal which concerns on embodiment of this invention. (C) It is explanatory drawing which shows the further another example of the seed crystal which concerns on embodiment of this invention. It is a perspective view which shows typically the positional relationship of the seed crystal and partition plate in embodiment of this invention. (A) It is a front view which shows typically the positional relationship of the seed crystal and partition plate in embodiment of this invention. (B) It is a front view which shows a mode that a part of seed crystal is fuse | melted in embodiment of this invention. It is a perspective view which shows typically a mode that the sapphire single-crystal ribbon in embodiment of this invention grows. It is a schematic diagram which shows the relationship between the slit space | interval TS in embodiment of this invention, and the thickness T of a sapphire single crystal ribbon. It is a perspective view showing partially and typically a plurality of sapphire single crystal ribbons according to an embodiment of the present invention obtained by the EFG method. (A) It is a front view of the seed crystal which concerns on the example of a change of embodiment of this invention. (B) It is a top view of the figure (a). (C) It is a side view of the same figure (a). (A) It is a bottom view of the sapphire single crystal ribbon grown using the seed crystal of FIG. (B) It is a front view of the same figure (a). (C) It is a side view of the same figure (a). (A) It is a front view of the seed crystal which concerns on the other modification of this invention. (B) It is a top view of the figure (a). (C) It is a side view of the same figure (a). It is explanatory drawing which shows the positional relationship of the seed crystal shown in FIG. 15, and a partition plate.

The first feature of the present embodiment is that the sapphire single crystal ribbon has a dimension in the longitudinal direction and has flexibility.

The second feature is that the sapphire single crystal ribbon does not have microcracks on the surface.

The third feature is that the sapphire single crystal ribbon is an As-grown single crystal.

The fourth feature is that a die having slits and arranged in parallel in the width direction is accommodated in a crucible, an aluminum oxide raw material is charged into the crucible and heated, and the aluminum oxide raw material is melted and oxidized in the crucible. An aluminum melt is prepared, an aluminum oxide melt pool is formed at the upper part of the slit through the slit, the seed crystal is brought into contact with the aluminum oxide melt at the upper part of the slit, and the seed crystal is pulled up. This is a method for producing a sapphire single crystal ribbon in which a sapphire single crystal ribbon having dimensions in the longitudinal direction and having flexibility is grown.

The fifth feature is that the grown sapphire single crystal ribbon is a method for producing a sapphire single crystal ribbon having no microcracks on the surface.

The sixth feature is that the grown sapphire single crystal ribbon is a method for producing a sapphire single crystal ribbon which is an As-grown single crystal.

In the present invention, the microcrack means, for example, when an etching solution such as heated phosphoric acid, phosphoric acid / sulfuric acid mixed solution, strong alkaline melt such as potassium hydroxide is applied on the surface of the sapphire single crystal, or visually. Therefore, the crack which can be observed shall be pointed out.

In the present invention, the As-grown single crystal refers to a single crystal that has not been subjected to surface processing such as grinding or polishing in the state of crystal growth.

According to these configurations, As is obtained by growing a sapphire single crystal ribbon so as to have a longitudinal dimension, and without performing surface processing such as grinding or polishing, and no microcracks are formed on the surface. By selecting the -grown single crystal, the formation of microcracks on the surface of the sapphire single crystal is prevented. By not having microcracks on the surface, the progress of microcracks is prevented, and the sapphire single crystal ribbon is provided with resistance to tensile stress and flexibility, and cracking and destruction are prevented. Furthermore, the process of surface processing of the sapphire single crystal ribbon can be reduced.

The seventh feature is that the sapphire single crystal ribbon has a width of 100 mm or less, a thickness of 0.5 mm or less, and a length in the longitudinal direction of 1000 mm or more.

The eighth feature is that the grown sapphire single crystal ribbon has a width of 100 mm or less, a thickness of 0.5 mm or less, and a length in the longitudinal direction of 1000 mm or more. It is that.

According to these configurations, a sapphire single crystal ribbon having high versatility and desirable dimensions for a superconducting coil can be obtained. In addition, there is no upper limit in particular and it can set arbitrarily, However As a standard in use, 10 km or less is mentioned.

The ninth feature is that the sapphire single crystal ribbon has a width of 10 mm, a thickness of 0.1 mm, and a length of 1000 mm.

The tenth feature is that the sapphire single crystal ribbon has a width of 10 mm, a thickness of 0.1 mm, and a length of 1000 mm.

According to these configurations, a sapphire single crystal ribbon having the most versatile and desirable dimensions for a superconducting coil can be obtained.

In the present invention, the ribbon shape of the sapphire single crystal ribbon is a rectangular shape in the plane direction, and specific dimensions include a length of 100 mm or less, a thickness of 0.5 mm or less, and a longitudinal dimension. Refers to a sapphire single crystal having a size of 1000 mm or more.

An eleventh feature is that the sapphire single crystal ribbon has a ratio of the width to the thickness (the width / the thickness) of 20 or more and 1000 or less.

A twelfth feature is that the ratio of the width to the thickness (the width / the thickness) is a method for producing a sapphire single crystal ribbon that is 20 or more and 1000 or less.

According to these configurations, it is possible to stably impart flexibility to the sapphire single crystal ribbon, and it is possible to further strengthen the resistance to tensile stress and the reliability of preventing cracking and destruction.

The thirteenth feature is that the sapphire single crystal ribbon is bent into a curved shape having a diameter of 300 mm or less.

The fourteenth feature is that the sapphire single crystal ribbon is produced by bending the grown sapphire single crystal ribbon into a curved shape having a diameter of 300 mm or less.

According to these structures, it is possible to bend and wind by applying external force to the sapphire single crystal ribbon by providing flexibility, and it can be bent into a curved shape with a diameter of 300 mm or less. As a coil application, it can be wound on a winding base and can be suitably used.

Furthermore, the fifteenth feature is a sapphire single crystal ribbon having a main surface and the main surface being an r-plane (10-12), a c-plane (0001), or an r-plane or c-plane having an off angle. That is.

A sixteenth feature is a method for producing a sapphire single crystal ribbon having a main surface and the main surface being an r-plane (10-12), a c-plane (0001), or an r-plane or c-plane having an off angle. It is that.

According to these configurations, it is possible to set an optimum plane orientation as a main surface as a formation surface of the superconducting layer.

Further, the seventeenth feature is that the aluminum oxide raw material is added to the aluminum oxide melt in the crucible while the seed crystal is pulled up to grow the sapphire single crystal ribbon or after the sapphire single crystal ribbon is grown. Furthermore, it is set as the manufacturing method of the sapphire single crystal ribbon which throws in and replenishes the said aluminum oxide melt.

According to these configurations, it becomes possible to continuously grow crystals of a sapphire single crystal ribbon and to improve mass productivity.

The eighteenth feature is that the sapphire single crystal ribbon has a dimension T in the thickness direction and a dimension in the longitudinal direction, and a variation width ΔT in the dimension T in the thickness direction is within 0.05 mm. (However, ΔT is greater than 0 mm).

The nineteenth feature is that the fluctuation range ΔT of the sapphire single crystal ribbon is within 0.025 mm.

In addition, the twentieth feature is that the slit has a gap TS, the desired main surface, the dimension T in the thickness direction, and the dimension in the longitudinal direction, and the gap TS and the thickness dimension T. Is a method for producing a sapphire single crystal ribbon in which the sapphire single crystal ribbon is grown under conditions satisfying the relationship of TS ≦ T.

The twenty-first feature is that a method for producing a sapphire single crystal ribbon in which the relationship between the interval TS and the thickness T satisfies TS ≦ 0.5T.

In the present invention, the thickness T refers to the average thickness of the sapphire single crystal ribbon or the dimension in the thickness direction set in advance for manufacturing.

According to these configurations, the sapphire single crystal ribbon is grown on the condition that the dimension T in the thickness direction and the slit interval TS of the die satisfy the relationship of TS ≦ T, and the variation width ΔT in the dimension T in the thickness direction. By using a sapphire single crystal ribbon with a thickness of 0.05 mm or less, the thickness T can be made uniform and the thickness variation ΔT can be reduced, resulting in characteristic variations and stress concentration during winding (especially the minimum thickness portion). Damage due to stress concentration on the surface can be suppressed.

Further, according to these configurations, the sapphire single crystal ribbon is grown so as to have a dimension T in the thickness direction and a dimension in the longitudinal direction, and further, surface cracking or polishing is not performed, and microcracks are formed on the surface. By selecting an As-grown single crystal in which no is formed, microcrack formation on the surface of the sapphire single crystal is prevented.

Hereinafter, a sapphire single crystal ribbon for a base substrate according to the present embodiment, which is used for forming a superconducting layer of a superconducting coil, will be described with reference to FIGS.

As shown in FIGS. 3 and 4, the superconductor 37 is formed by providing a superconducting layer 35 made of a superconducting material on the surface of the base material 2 having a ribbon-like thin or thin flexibility. Since the base substrate 2 is required to have high electrical resistance, thermal conductivity, and electrical insulation, it is preferably made of a sapphire single crystal (hereinafter referred to as “sapphire single crystal ribbon 2”). Description).

The ribbon shape of the sapphire single crystal ribbon 2 in the present invention has dimensions in the longitudinal direction as shown in FIG. 1, the shape in the plane direction is rectangular, and specific dimensions include a width W of 100 mm or less, a thickness This refers to a sapphire single crystal having a length T of 0.5 mm or less and a length L of 1000 mm or more as a dimension in the longitudinal direction. A sapphire single crystal having a width W of 100 mm or less, a thickness T of 0.5 mm or less, and a length L of 1000 mm or more is desirable because of its high versatility for superconducting coils. The upper limit of the length L is not particularly limited and can be set arbitrarily, but a guideline for use is 10 km or less.

Furthermore, a sapphire single crystal ribbon having a width W of 10 mm, a thickness of T 0.1 mm, and a length of L 1000 mm is most versatile and desirable for a superconducting coil. The thickness T refers to the average thickness of the sapphire single crystal ribbon 2 or the dimension in the thickness direction that is set in advance for manufacturing.

FIG. 2 is a conceptual diagram schematically showing the average thickness T and the thickness fluctuation range ΔT of the sapphire single crystal ribbon 2. In the figure, the dimensional variation in the thickness direction is emphasized. Even if the crystal growth is performed such that the average dimension in the thickness direction of the sapphire single crystal ribbon 2 is T, the dimension in the thickness direction changes. At this time, when the maximum thickness of the sapphire single crystal ribbon 2 grown is T _max and the minimum thickness is T _min , the difference ΔT = T _max −T _min is the fluctuation width in the dimension T in the thickness direction. is there.

In the present invention, the variation width ΔT in the thickness direction of the sapphire single crystal ribbon 2 is set to 0.05 mm or less, so that the characteristic variation of the sapphire single crystal ribbon 2 and the stress concentration during winding (particularly, the minimum thickness portion). T concentration of stress on the _min part), can further suppress the damage due to the stress concentration at the time the wound.

Since the sapphire single crystal has a high thermal conductivity, the heat-resistant temperature becomes 200 ° C. or higher, the expansion or contraction of the base substrate 2 itself is suppressed, and the possibility of distortion in the superconducting layer 35 is reduced, and the critical current density Jc is reduced. In addition to preventing the heat treatment, it is possible to withstand the heat treatment temperature when heat treatment is performed after winding. Furthermore, when the superconducting layer 35 is composed of oxide superconductivity, it can withstand the heat treatment temperature necessary for forming the oxide superconducting layer.

The sapphire single crystal ribbon 2 according to the present invention is an As-grown single crystal. An As-grown single crystal refers to a single crystal that has not been subjected to surface processing such as grinding or polishing in a crystal-grown state. That is, the formation of microcracks on the surface of the single crystal by abrasive grains or a grinding machine when performing surface processing such as grinding or polishing is prevented. By not having a microcrack on the surface, the progress of the microcrack is prevented, and the sapphire single crystal ribbon 2 has resistance and flexibility against tensile stress, and is microscopic when bent or wound by applying external force. Cracks and breakage due to cracks are prevented.

Crystal growth of the sapphire single crystal so as to have a dimension in the longitudinal direction and further surface treatment such as grinding or polishing are not performed, thereby preventing formation of microcracks on the surface of the sapphire single crystal. By not having a microcrack on the surface, the progress of the microcrack is prevented, and the sapphire single crystal ribbon 2 is provided with resistance to tensile stress and flexibility, and cracking and destruction are prevented.

Further, the As-grown single crystal of the sapphire single crystal ribbon 2 grown to have a dimension in the longitudinal direction is not subjected to surface processing such as grinding or polishing, and no As-grown crack is formed on the surface. By selecting the grown single crystal, flexibility can be imparted to the sapphire single crystal ribbon 2 and the surface processing steps can be reduced.

By imparting flexibility, the sapphire single crystal ribbon 2 of the present invention can be bent or wound by applying an external force, and can be bent into a curved shape having a diameter of 300 mm or less. Can be wound around the winding base and can be used preferably. The diameter of the sapphire single crystal ribbon 2 may be further wound with a smaller diameter such as 200 mm or less or 100 mm or less, or may be wound with a larger diameter such as 500 mm or less, and can be appropriately selected depending on the intended use.

Further, by providing the sapphire single crystal ribbon 2 having resistance to tensile stress and flexibility, the superconductor 37 can be wound, and even if the superconductor 37 is wound, the sapphire single crystal ribbon 2 is wound. Generation of cracks and destruction is prevented. Therefore, it can be used for various magnets such as superconducting magnets and magnets for nuclear magnetic resonance diagnostic apparatuses, cables, power transmission and distribution, AC windings, generators, transformers, superconducting fault current limiters, and the like.

Furthermore, the sapphire single crystal ribbon 2 has a main surface 2a, and the main surface 2a is an r-plane (10-12), a c-plane (0001), or an r-plane or c-plane having an off angle. The off-angle is an angle with respect to the r-plane or c-plane, and is set within 5 °. By setting the main surface 2a in such a plane orientation, it is possible to set an optimum plane orientation as a formation surface of the superconducting layer 35. Further, as another plane orientation of the main surface 2a, an a plane (1120) or an m plane (1010), or a plane having an off angle set within 5 ° from the a plane or the m plane can be selected.

Furthermore, by setting the numerical range of the ratio of width W to thickness T (width W / thickness T) as 20 or more and 1000 or less, flexibility can be stably imparted to the sapphire single crystal ribbon 2, Resistance to tensile stress and reliability for prevention of cracking and breakage can be further strengthened.

As described above, the superconductor 37 or the superconducting coil 36 includes at least the sapphire single crystal ribbon 2 and the superconducting layer 35. As a still more preferable configuration, a superconductor 37 or a superconducting coil 36 having a buffer layer 34 is shown (see FIG. 3 or FIG. 4).

The buffer layer 34 includes cerium oxide (CeO ₂ ), SrTiO ₃ , Nb-doped SrTiO ₃ , RE ₂ O ₃ (RE is a rare earth element), MgO, LaMnO ₃ , YSZ, Y ₂ O ₃ , LaAlO ₃ , LaCrO ₃ , Formed from a suitable material, such as one or more epitaxial layers selected from NdGaO ₃ , LaNiO ₃ , lanthanum zirconate (LZO), NbTiO ₃ , TiN, TZN, TiB ₂ , Pd, Ag, PT, and Au can do. The buffer layer 34 has a thickness of 20 nm to 300 nm.

Further, a superconducting layer 35 is formed on the main surface 2 a or the buffer layer 34. The superconducting layer 35, an oxide _{_{_{_{superconductor, YBa 2 Cu 3 O 7,}}}} Y1Ba 2 Cu 3 O 7-δ, REBa such _{_{_{_{GdBa 2 Cu 3 O 7 2 Cu}}}} 3 O 7 (RE is a rare earth element _{_{_{_{), Bi 2 Sr 2 Cu 3}}}} O x, Bi-Sr-Ca-Cu-O system, Bi-Pb-Sr-Ca -Cu-O system, Tl-Ba-Ca-Cu -O system _(Tl 1 Ba ₂ _{_{_{Ca n-1 Cu n O 2n}}} + 3 (n is an integer between _1-4), (integer between n is _{_{1 ~ 4) Tl 2 Ba 2}} Ca n-1 Cu n O 2n + 4), Tl-Pb-Ba -Ca-Cu-O _{_{_{_{system, Hg 1 Ba 2 Ca n-}}}} 1 Cu n O 2n + 2 (n is an integer between 1-4) can be selected from. The thickness of the superconducting layer 35 is 410 nm to 2 μm.

Next, a method for manufacturing a sapphire single crystal ribbon according to an embodiment of the present invention will be described with reference to FIGS. In addition, about the location and content which overlap with description of the said sapphire ribbon 2, description is simplified or abbreviate | omitted.

As shown in FIG. 5, the sapphire single crystal ribbon manufacturing apparatus 1 includes a growth container 3 for growing a sapphire single crystal ribbon 2 and a pulling container 4 for pulling up the grown sapphire single crystal ribbon 2. EFG (Edge -The sapphire single crystal ribbon 2 is grown and grown by the defined Film-fed (GrowTh) method.

The growth container 3 includes a crucible 5, a crucible drive unit 6, a heater 7, an electrode 8, a die 9, and a heat insulating material 10. The crucible 5 is made of molybdenum and melts the aluminum oxide raw material. The crucible drive unit 6 rotates the crucible 5 with the vertical direction as an axis. The heater 7 heats the crucible 5. The electrode 8 energizes the heater 7. The die 9 is installed in the crucible 5 and determines the liquid surface shape of an aluminum oxide melt (hereinafter simply referred to as “melt” if necessary) 21 when pulling up the sapphire single crystal ribbon 2. The heat insulating material 10 surrounds the crucible 5, the heater 7 and the die 9.

Furthermore, the growth vessel 3 includes an atmosphere gas inlet 11 and an exhaust port 12. The atmosphere gas introduction port 11 is an introduction port for introducing, for example, argon gas into the growth vessel 3 as the atmosphere gas, and prevents oxidation of the crucible 5, the heater 7, and the die 9. On the other hand, the exhaust port 12 is provided for exhausting the inside of the growth vessel 3.

The pulling container 4 includes a shaft 13, a shaft driving unit 14, a gate valve 15, and a substrate inlet / outlet 16, and pulls up a plurality of flat plate-shaped sapphire single crystal ribbons 2 grown and grown from the seed crystal 17. The shaft 13 holds a seed crystal 17. Further, the shaft driving unit 14 moves the shaft 13 up and down toward the crucible 5 and rotates the shaft 13 around the lifting direction. The gate valve 15 partitions the growth container 3 and the pulling container 4. The substrate entrance / exit 16 takes in and out the seed crystal 17.

The manufacturing apparatus 1 also has a control unit (not shown), and the rotation of the crucible drive unit 6 and the shaft drive unit 14 is controlled by this control unit.

Next, the die 9 will be described. The die 9 is made of molybdenum and has a number of partition plates 18 as shown in FIG. In FIG. 6, as an example of the die, 30 partition plates 18 are provided and 15 dies 9 are formed. The partition plates 18 have the same flat plate shape and are arranged in parallel to each other so as to form a minute gap (slit) 19 to form one die 9. The slit 19 is provided over almost the entire width of the die 9. Further, since the plurality of dies 9 have the same shape and are arranged in parallel at a predetermined interval so that the width directions thereof are parallel to each other, a plurality of slits 19 are provided. A slope 30 is formed at the upper part of each partition plate 18, and the opening 20 is formed by arranging the slopes 30 so as to face outward. Moreover, the slit 19 has a role which raises the melt 21 to the opening part 20 from the lower end of each die | dye 9 by capillary action.

As shown in FIG. 8, the width WD of the die 9 is set according to the width W of the sapphire single crystal ribbon 2. Therefore, it is desirable to set the die width WD to 100 mm or less, more preferably 10 mm, because the sapphire single crystal ribbon 2 having a desired width W can be obtained by crystal growth.

The aluminum oxide raw material charged into the crucible 5 is melted (raw material melt) based on the temperature rise of the crucible 5 to become a melt 21. A part of the melt 21 enters the slit 19 of the die 9, and ascends in the slit 19 based on the capillary phenomenon as described above, and is exposed from the opening 20. 22 (see FIG. 9B) is formed. In the EFG method, the sapphire single crystal ribbon 2 grows according to the shape of the melt surface formed by the aluminum oxide melt pool (hereinafter referred to as “melt pool” if necessary) 22. In the die 9 shown in FIG. 6, the shape of the melt surface is an elongated rectangle, so that a flat sapphire single crystal ribbon 2 is manufactured.

Next, the seed crystal 17 will be described. As shown in FIGS. 7, 8, and 9, in this embodiment, a plate-shaped substrate is used as the seed crystal 17, and the c-axis is along the surface direction of the principal surface (a surface orthogonal to the crystal surface 28). A horizontal sapphire single crystal substrate is used. Further, the seed crystal 17 is arranged so that the planar direction of the seed crystal 17 and the width direction of the die 9 are orthogonal to each other at an angle of 90 °. Accordingly, the c-axis of the seed crystal 17 is perpendicular to the partition plate 18. Further, since the seed crystal 17 and the sapphire single crystal ribbon 2 are orthogonal to each other at an angle of 90 °, FIG. 5 shows the side surface of the sapphire single crystal ribbon 2. By making the positional relationship between the planar direction of the seed crystal 17 and the width direction of the partition plate 18 perpendicular (by crossing the seed crystal 17 with the partition plate 18), the contact area between the melt 21 and the seed crystal 17 is minimized. It becomes possible to do. Therefore, the contact part of the seed crystal 17 becomes easy to become familiar with the melt 21, and the occurrence of crystal defects in the sapphire single crystal ribbon 2 is reduced or eliminated.

If the contact area with the substrate holder (not shown) under the shaft 13 is large, the seed crystal 17 is deformed due to a stress due to a difference in thermal expansion coefficient, and may be damaged in some cases. On the contrary, the fixation of the seed crystal 17 may be loosened due to the difference in thermal expansion coefficient. Therefore, it is preferable that the contact area between the seed crystal 17 and the substrate holder is small. The seed crystal 17 needs to have a substrate shape that can be securely fixed to the substrate holder.

FIG. 7 is a diagram showing an example of the substrate shape of the seed crystal 17. Among these, (a) and (b) in the figure are those in which a notch 23 is provided in the upper part of the seed crystal 17. By using this notch 23, for example, a U-shaped substrate holder can be inserted from the lower side of the two notches 23, and the seed crystal 17 can be reliably held while reducing the contact area. Become.

Further, as shown in FIG. 7C, a notch hole 24 may be provided inside the seed crystal 17. Using this cutout hole 24, for example, locking claws are inserted into the two cutout holes 24, and the contact area between the substrate holder and the seed crystal 17 is reduced, and the seed crystal 17 is securely held. It becomes possible.

Next, a method for manufacturing the sapphire single crystal ribbon 2 using the manufacturing apparatus 1 will be described. First, a predetermined amount of granulated aluminum oxide raw material powder (99.99% aluminum oxide), which is a sapphire raw material, is charged into a crucible 5 in which a die 9 is housed. The aluminum oxide raw material powder may contain a compound or element other than aluminum oxide depending on the purity or composition of the sapphire single crystal ribbon to be produced.

Subsequently, in order not to oxidize the crucible 5, the heater 7, or the die 9, the inside of the growth vessel 3 is replaced with argon gas, and the oxygen concentration is set to a predetermined value or less.

Next, the crucible 5 is heated to a predetermined temperature by the heater 7 to melt the aluminum oxide raw material powder. Since the melting point of aluminum oxide is about 2050 ° C. to 2072 ° C., the heating temperature of the crucible 5 is set to a temperature higher than the melting point (for example, 2100 ° C.). After a while after heating, the raw material powder is melted and an aluminum oxide melt 21 is prepared. Further, a part of the melt 21 rises through the slit 19 of the die 9 by capillary action to reach the surface of the die 9, and a melt pool 22 is formed above the slit 19.

Next, as shown in FIGS. 8 and 9, the seed crystal 17 is lowered while holding the seed crystal 17 at an angle perpendicular to the width direction of the melt reservoir 22 above the slit 19, so that the seed crystal 17 is melted in the melt reservoir 22. Touch the liquid surface. The seed crystal 17 is previously introduced into the pulling container 4 from the substrate entrance 16. In FIG. 8, the melt 21 and the melt reservoir 22 are not shown in order to prioritize the visibility of the slit 19 and the opening 20.

FIG. 8 is a diagram showing the positional relationship between the seed crystal 17 and the partition plate 18. As described above, by making the plane direction of the seed crystal 17 perpendicular to the width direction of the partition plate 18, the contact area between the seed crystal 17 and the melt 21 can be reduced. Therefore, the contact portion of the seed crystal 17 becomes compatible with the melt 21, and crystal defects are less likely to occur in the grown and grown sapphire single crystal ribbon 2. Therefore, the yield of the sapphire single crystal ribbon 2 can be improved.

When the seed crystal 17 is brought into contact with the melt surface, the lower part of the seed crystal 17 may be brought into contact with the upper part of the partition plate 18 and melted. FIG. 9B is a diagram showing a state in which a part of the seed crystal 17 is melted. By melting part of the seed crystal 17 in this way, the temperature difference between the seed crystal 17 and the melt 21 can be quickly eliminated, and the generation of crystal defects in the sapphire single crystal ribbon 2 is further reduced. It becomes possible.

Subsequently, the substrate holder is pulled up by the shaft 13 at a predetermined rising speed to start pulling up the seed crystal 17 to form the sapphire single crystal ribbon 2 as shown in FIG. FIG. 10 is an explanatory view showing a state in which the sapphire single crystal ribbon 2 grows. FIG. 11 is a schematic diagram showing the relationship between the slit interval TS and the thickness T of the sapphire single crystal ribbon 2. In the present embodiment, the thickness T of the sapphire single crystal ribbon 2 is controlled by adjusting growth conditions such as the speed at which the seed crystal 17 is pulled up, and the relationship with the interval TS between the slits 19 is TS ≦ T. As a result, the sapphire single crystal ribbon 2 is grown while expanding from the interval TS of the slit 19 and is pulled up and grown by the thickness T.

In the growth method of the present embodiment, the thickness T can be made uniform by growing so that the relationship between the interval TS of the slits 19 and the thickness T of the sapphire single crystal ribbon 2 satisfies TS ≦ T, as shown in FIG. The thickness variation ΔT can be reduced. Thereby, thickness fluctuation | variation (DELTA) T can be suppressed and the damage by the characteristic dispersion | variation and the stress concentration at the time of winding can be suppressed. More preferably, by growing so as to satisfy the relationship of TS ≦ 0.5T, the thickness T can be made more uniform, and the thickness variation ΔT can be suppressed to prevent damage due to characteristic variation and stress concentration during winding.

Further, a flat sapphire single crystal ribbon 2 having a width W substantially equal to the width WD of the die 9 is grown.

The sapphire single crystal ribbon 2 is grown with the width WD of the die 9 (that is, the width W of the sapphire single crystal ribbon 2), and the sapphire single crystal ribbon 2 is pulled up to a predetermined length (length L) at a predetermined speed. Thus, a flat sapphire single crystal ribbon 2 is obtained.

Thereafter, the obtained sapphire single crystal ribbon 2 is cooled, the gate valve 15 is opened, moved to the lifting container 4 side, and taken out from the substrate entrance 16. The appearance of the obtained flat plate-shaped sapphire single crystal ribbon 2 is shown in FIG.

In addition, as shown in FIGS. 5 and 8 to 12, a plurality of sapphire single crystal ribbons 2 can be simultaneously grown from a common seed crystal 17 to lower the manufacturing cost of the sapphire single crystal ribbon 2. Is possible and preferable. When manufacturing a plurality of sapphire single crystal ribbons 2 at the same time, a plurality of dies are accommodated in a crucible and the width directions of the dies are arranged in parallel. By pulling up the seed crystal 17, it is possible to produce a plurality of sapphire single crystal ribbons 2 having a desired principal surface 2 a and a longitudinal dimension L and having flexibility as As-grown single crystals.

In the EFG method, the sapphire single crystal ribbon 2 is grown and grown while the surface direction of the main surface 2a of the sapphire single crystal ribbon 2 is the same crystal direction as the crystal surface 28 of the seed crystal 17. As an example, when the seed crystal 17 is made of a sapphire single crystal and the crystal plane 28 is a c-plane, all the main surfaces 2a of the obtained flat plate-shaped sapphire single crystal ribbon 2 can be a c-plane. Therefore, it is possible to obtain a plurality of sapphire single crystal ribbons 2 with no variation in view of the crystal direction.

Therefore, the die 9 including the seed crystal 17 and the partition plate 18 needs to be positioned precisely. Therefore, as shown in FIG. 5, the manufacturing apparatus 1 is provided with a crucible driving unit 6 that rotates the crucible 5 in which the die 9 is installed, and a control unit (not shown) that controls the rotation. The shaft 13 is also provided with a shaft drive unit 14 that rotates the shaft 13 and a control unit (not shown) that controls the rotation of the shaft 13. That is, the positioning of the seed crystal 17 with respect to the die 9 is adjusted by rotating the shaft 13 or the crucible 5 by the control unit.

Note that the crystal plane 28 of the seed crystal 17 is not limited to the c-plane, and can be set to a desired crystal plane such as an r-plane, a-plane, or m-plane. Thus, by setting the crystal plane 28 arbitrarily, the surface direction of the main surface 2a of the sapphire single crystal ribbon 2 can be arbitrarily changed.

The pulling rate can be set constant from the time when the crystal growth is disclosed by the start of pulling up the seed crystal 17 until the crystal growth is completed with the desired length L, so that the variation ratio of the width W / thickness T is set. This is preferable because it is within the range of 20 or more and 1000 or less. Further, it is preferable to set the pulling speed constant so that the thickness variation ΔT can be suppressed and the thickness can be kept within the range of 0.05 mm and 0.025 mm.

The interval TS between the slits 19 is set to 0.25 mm / 0.1 mm / 0.075 mm / 0.05 mm / 0.025 mm, respectively, and the thickness T is 0.5 mm / 0.2 mm / 0.15 mm / 0.1 mm / The seed crystal 17 was pulled up under the condition of 0.05 mm to grow the sapphire single crystal ribbon 2. In any of the sapphire single crystal ribbons 2, the thickness variation ΔT was within 0.05 mm, and no breakage occurred even when bent into a curved shape having a diameter of 300 mm.

On the other hand, when the seed crystal 17 is pulled up and the sapphire single crystal ribbon 2 is grown under the condition that the thickness T is thinner than the interval TS between the slits 19, the thickness variation ΔT exceeds 0.05 mm. When it was generated and bent into a curved shape having a diameter of 300 mm, breakage occurred.

Therefore, by setting the relationship between the thickness T and the interval TS between the slits 19 to be TS ≦ T, more preferably TS ≦ 0.5T, the thickness variation ΔT of the sapphire single crystal ribbon 2 is within 0.05 mm, more It can be preferably accommodated within 0.025 mm, and it has been found that the thickness T can be made uniform to suppress the thickness variation ΔT, and the damage due to characteristic variations and stress concentration during winding can be suppressed.

It should be noted that the present invention is not limited to the above-described embodiment, and can be modified by a configuration within a range not departing from the scope of the technical idea.

For example, the present invention can be applied to the growth of a sapphire single crystal ribbon having a step structure on the main surface and having an off angle set within 5 ° from the r-plane, c-plane, a-plane, and m-plane. It is. In the method of manufacturing a sapphire single crystal ribbon by the EFG method in which the main surface 2a of the sapphire single crystal ribbon 2 is, for example, c-plane, the m-axis of the seed crystal is aligned with the pulling direction of the sapphire single crystal ribbon. Further, the c-axis of the seed crystal positioned in the direction perpendicular to the pulling direction is set to a predetermined angle (for example, 0.05) with respect to the normal of the main surface of the sapphire single crystal ribbon with the pulling direction as the rotation axis. It may be grown at an angle of more than °. In addition, the description which overlaps with the said embodiment is abbreviate | omitted or simplified.

Here, the seed crystal in which the c-axis is inclined will be described with reference to FIG. An orthogonal coordinate system in which the normal of the plane of the seed crystal 31 shown in FIG. 13 is the Z axis, the normal of the side surface (crystal plane) of the seed crystal 31 is the Y axis, and the normal of the front of the seed crystal 31 is the X axis. It explains using. The Z axis is arranged in parallel to the pulling direction of the sapphire single crystal ribbon.

As shown in FIG. 13A, the c-axis of the seed crystal 31 is adjusted such that the angle α formed with the Z-axis (the axis in the pulling direction) is within a predetermined range (for example, 90 ° ± 0.5 °). In addition, as shown in FIG. 13B, the c-axis is inclined at a predetermined angle β (for example, a range of 0.05 ° or more and 1.0 ° or less) in the X-axis direction (a-axis direction). ing. On the other hand, the m-axis in the pulling-up axis direction (Z-axis direction) is perpendicular to the c-axis as shown in FIG. 13 (a), and this m-axis is as shown in FIG. 13 (c). The deviation angle γ from the pulling-up axis direction (Z-axis) is adjusted within a predetermined angle range (for example, 0.5 ° or less) in the X-axis direction with respect to the Z-axis.

In this way, by tilting the c-axis of the seed crystal 31 by a predetermined angle β in the X-axis direction, the sapphire single crystal ribbon 32 grown and grown using the seed crystal 31 is as shown in FIG. The c-axis is inclined at a predetermined angle β (in the range of 0.05 ° or more and 1.0 ° or less as described above) with respect to the normal nv direction of the main surface with the Z-axis (pull-up direction) as the rotation axis. That is, it is possible to obtain a sapphire single crystal ribbon having a c-axis inclination angle on the main surface corresponding to the predetermined angle β. Thereby, all the step structures in the main surface of the obtained sapphire single crystal ribbon become the same direction, and a sapphire single crystal ribbon without a crystal defect can be obtained. Further, the deviation angle between the m-axis and the Z-axis is formed within the γ (0.5 °), and as shown in FIG. 14C, the c-axis and the Z-axis have the α (90 ° ± 0.5 °). ) Formed within.

13 and 14, a sapphire single crystal whose c-axis is inclined at a predetermined angle β with respect to the nv direction using a seed crystal 31 whose c-axis is inclined at a predetermined angle β in the a-axis direction in advance. Although the case where the ribbon 32 is grown has been described, the present invention is not limited to this, and a sapphire single crystal ribbon may be grown using the seed crystal 33 shown in FIG.

As shown in FIG. 15A, the c-axis of the seed crystal 33 is adjusted so that the angle α formed with the Z-axis is within a predetermined range (for example, 90 ° ± 0.5 °). As shown in b), the c-axis is adjusted parallel to the Y-axis direction. On the other hand, the m-axis in the pulling direction (Z-axis) is perpendicular to the c-axis as shown in FIG. 15 (a), and the deviation angle γ from the Z-axis is Z-axis as shown in FIG. 15 (c). Is adjusted within a predetermined range (0.5 ° or less) in the X-axis direction (a-axis direction).

When the seed crystal 33 shown in FIG. 15 is used, the normal of the side surface (end face) of the seed crystal 33 is shifted by a predetermined angle β with respect to the normal of the partition plate 18 as shown in FIG.

Therefore, the shaft 13 or the crucible 5 is rotated by the control unit, so that the normal line of the side surface (end face) of the seed crystal 33 is accurately positioned within the range of the predetermined angle β with respect to the normal line of the partition plate 18. To do. Thereby, it is possible to obtain a sapphire single crystal ribbon whose c-axis is inclined in a predetermined direction by a predetermined angle β.

Further, during the growth of the sapphire single crystal ribbon 2 by pulling up the seed crystal 17 or after the growth of the sapphire single crystal ribbon 2, the aluminum oxide melt 21 remaining in the crucible 5 is not shown in each growth cycle. An aluminum oxide raw material may be further added and the aluminum oxide melt 21 may be replenished to continuously grow the sapphire single crystal ribbon 2. In this way, by introducing the aluminum oxide raw material into the crucible 5 for each growth cycle and replenishing the aluminum oxide melt 21, it becomes possible to continuously grow the crystal of the sapphire single crystal ribbon 2. Can be improved. When the sapphire single crystal ribbon 2 is continuously grown, the sapphire single crystal ribbon 2 may be grown with a length L or longer.

When continuously growing the sapphire single crystal ribbon 2 by using the gate valve 15, the leakage of atmospheric gas (for example, inert gas) in the growth vessel 3 and the leakage of heat are minimized. What is necessary is to prevent a drop in growth efficiency. In addition, the atmospheric gas may be continuously supplied.

Also, the dimension in the pulling direction of the pulling container 4 is set to be larger than the length L of the sapphire single crystal ribbon 2.

The aluminum oxide raw material is fed into the crucible 5 at a rate corresponding to the crystal growth rate of the sapphire single crystal ribbon 2 to replenish the aluminum oxide melt 21. The aluminum oxide raw material may be fed into the crucible 5 in a solid state.

Thereafter, the superconducting layer 35 is deposited directly or more preferably via the buffer layer 34 on the main surface 2a of the crystal-grown sapphire single crystal ribbon 2. The buffer layer 34 is formed by physical vapor deposition, chemical vapor deposition (including CVD or MOCVD), sputtering, pulse laser vapor deposition, coating pyrolysis, coating photolysis, sol-gel, electrodeposition, chemical solution deposition, or the like. Deposition formation.

Furthermore, various methods can be applied to the formation of the superconducting layer 35, including physical vapor deposition, chemical vapor deposition (including CVD or MOCVD), pulsed laser vapor deposition, chemical solution deposition, and solution decomposition (as raw materials). A method of irradiating a metal organic compound solution with ultraviolet light (laser or lamp light), a sputtering method, a pulse laser ablation method, a coating pyrolysis method, or the like can be used. In this way, the superconductor 37 or the superconducting coil 36 is produced.

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus of sapphire

single crystal ribbon

2, 32 Sapphire single crystal ribbon or base material 2a Main surface 3 Growth container 4 Lifting container 5 Crucible 6 Crucible drive part 7 Heater 8 Electrode 9 Die 10 Heat insulating material 11 Atmospheric gas inlet 12 Exhaust Port 13 Shaft 14 Shaft drive 15 Gate valve 16 Substrate entry /

exit

17, 31, 33 Seed crystal 18 Partition plate 19 Slit 20 Opening 21 Aluminum oxide melt 22 Aluminum oxide melt reservoir 23 Notch portion of seed crystal 24 Seed crystal Notch 28 Crystal plane 30 Slope 34 Buffer layer 35 Superconducting layer 36 Superconducting coil 37 Conductor L Length of sapphire single crystal ribbon W Width of sapphire single crystal ribbon T Thickness of sapphire single crystal ribbon ΔT Width of sapphire single crystal ribbon in the thickness direction TS Slit width WD Die width

Claims

A sapphire single crystal ribbon having dimensions in the longitudinal direction and having flexibility.
The sapphire single crystal ribbon according to claim 1, wherein the sapphire single crystal ribbon has no microcracks on the surface.
The sapphire single crystal ribbon according to claim 1 or 2, wherein the sapphire single crystal ribbon is an As-grown single crystal.
4. The sapphire single crystal ribbon according to claim 1, wherein the sapphire single crystal ribbon has a width of 100 mm or less, a thickness of 0.5 mm or less, and a length in the longitudinal direction of 1000 mm or more.
The sapphire single crystal ribbon according to claim 4, wherein the width is 10 mm, the thickness is 0.1 mm, and the length is 1000 mm.
The sapphire single crystal ribbon according to claim 4 or 5, wherein a ratio of the width to the thickness (the width / the thickness) is 20 or more and 1000 or less.
The sapphire single crystal ribbon according to any one of claims 1 to 6, which is bent into a curved shape having a diameter of 300 mm or less.
The sapphire single crystal ribbon according to any one of claims 1 to 7, wherein the sapphire single crystal ribbon has a main surface and the main surface is an r-plane, a c-plane, or an r-plane or a c-plane having an off angle.
9. The thickness direction dimension T and the longitudinal direction dimension, and a variation width ΔT in the thickness direction dimension T is 0.05 mm or less. Sapphire single crystal ribbon.
The sapphire single crystal ribbon according to claim 9, wherein the fluctuation range ΔT is within 0.025 mm.
A die having a slit and arranged in parallel in the width direction is housed in a crucible,
An aluminum oxide raw material is put into a crucible and heated, and the aluminum oxide raw material is melted in the crucible to prepare an aluminum oxide melt.
Form an aluminum oxide melt pool at the top of the slit through the slit,
The seed crystal is brought into contact with the aluminum oxide melt at the top of the slit and the seed crystal is pulled up to grow a sapphire single crystal ribbon having a desired main surface and a longitudinal dimension and having flexibility. A method for manufacturing a sapphire single crystal ribbon.
The method for producing a sapphire single crystal ribbon according to claim 11, wherein the grown sapphire single crystal ribbon has no microcracks on the surface.
The method for producing a sapphire single crystal ribbon according to claim 11 or 12, wherein the grown sapphire single crystal ribbon is an As-grown single crystal.
14. The grown sapphire single crystal ribbon has a width of 100 mm or less, a thickness of 0.5 mm or less, and a length as a dimension in the longitudinal direction of 1000 mm or more. The manufacturing method of the sapphire single crystal ribbon as described in 2.
The method for producing a sapphire single crystal ribbon according to claim 14, wherein the width is 10 mm, the thickness is 0.1 mm, and the length is 1000 mm.
The method for producing a sapphire single crystal ribbon according to claim 14 or 15, wherein the ratio of the width to the thickness (the width / the thickness) is 20 or more and 1000 or less.
The method for producing a sapphire single crystal ribbon according to any one of claims 11 to 16, wherein the grown sapphire single crystal ribbon is bent into a curved shape having a diameter of 300 mm or less.
The sapphire single crystal ribbon according to any one of claims 11 to 17, wherein the sapphire single crystal ribbon has a main surface and the main surface is an r-plane, a c-plane, or an r-plane or c-plane having an off angle. Method.
During the growth of the sapphire single crystal ribbon by pulling up the seed crystal or after the growth of the sapphire single crystal ribbon, the aluminum oxide raw material is further added to the aluminum oxide melt in the crucible, The method for producing a sapphire single crystal ribbon according to any one of claims 11 to 18, wherein the liquid is replenished.
The slit has an interval TS, and has the desired main surface, the thickness-direction dimension T, and the longitudinal dimension, and the interval TS and the thickness dimension T satisfy the relationship TS ≦ T. The method for producing a sapphire single crystal ribbon according to any one of claims 11 to 19, wherein the sapphire single crystal ribbon is grown under conditions.
21. The method for producing a sapphire single crystal ribbon according to claim 20, wherein a relationship between the interval TS and the thickness T satisfies TS ≦ 0.5T.