Homoepitaxial thin film, method for producing same, and device for producing same

Abstract

In order to form a homoepitaxial thin film on the surface of a substrate (2) having the surface of a LiNbO3 single crystal or a LiTaO3 single crystal, the same composition as the single crystal is deposited on the surface of the substrate having the surface of the LiNbO3 single crystal or the LiTaO3 single crystal by a high-frequency sputtering method. The manufacturing apparatus (1) has a chamber (11) and a high-frequency power supply for supplying high-frequency power to a target (121) disposed inside the chamber. The sputtering electrode (12) is disposed such that a surface normal (PL1) of the target is offset from a substrate located at a film formation position and the surface normal (PL1) of the target is inclined by 15-75 DEG with respect to a surface normal (PL2) of the substrate.

Description

Technical Field

[0001] The present invention relates to a homoepitaxial thin film, a method for manufacturing the same and a manufacturing device. Background Art

[0002] Lithium niobate (LiNbO3, hereinafter referred to as LN) and lithium tantalate (LiTaO3, hereinafter referred to as LT) as oxide single crystals are materials with excellent piezoelectricity and electro-optical effects. In recent years, from the perspective of improving the performance of communication / optical control elements using the two materials, composite substrates formed by bonding single crystal LN and single crystal LT to a silicon substrate or sapphire substrate as a supporting substrate and thinning the single crystal LN and single crystal LT have attracted attention. The single crystal LN thin plates or single crystal LT thin plates on these composite substrates are produced by top-down processing such as grinding.

[0003] Grinding technology includes, for example, chemical mechanical polishing (CMP) and ion beam dressing. Usually, CMP is used for micron-level thickness grinding or surface flattening, and ion beam dressing is used for nanometer-level grinding. However, the excellent physical properties of the single crystal structure are related to the crystal structure and composition of the surface layer in many device products, but since single crystal LN and single crystal LT are difficult-to-etch materials, these grinding processes may cause atomic-level damage such as defects and changes in composition to the surface layer. In addition, as a low-damage grinding method, a dressing method based on a gas cluster ion beam can be cited, but due to the slow grinding speed, the problem of increased manufacturing cost arises (see patent document 1).

[0004] In addition, as a method of obtaining a thin single crystal LN or single crystal LT by a method different from the above-mentioned grinding technology, there can be cited a method of ion implantation of light elements and a method of dividing and transferring the single crystal after ion implantation by heat treatment (Patent Document 2). However, the structural integrity of the single crystal that is divided as a result of the large amount of high-energy ions doped is damaged, and sometimes the original properties of the material are degraded. In this case, there is also a means of further restoring the damage inside the crystal by additional heat treatment, but it is necessary to adjust the heat treatment conditions according to the form of the final product, resulting in a problem of complicating the manufacturing process.

[0005] In addition, in the silicon single crystals used in many semiconductor devices, for substrates whose surface contains defects of a type that cannot be ignored to achieve the performance required of the device products, the structural integrity of the surface of the silicon single crystal is restored by forming a new thin film layer through epitaxial growth using vapor phase growth (see Patent Document 3).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2020-43214

[0009] Patent Document 2: International Publication No. 2009 / 081651

[0010] Patent Document 3: Japanese Patent Application Publication No. 2010-177355 Summary of the invention

[0011] Problems to be solved by the invention

[0012] In LN single crystals and LT single crystals, as in silicon single crystals, epitaxial growth technology that can restore the function of the single crystal surface layer that is easily lost during the thin plate formation process is expected, but there has been no corresponding technology in the past. The reason is that LN single crystals and LT single crystals used in many devices are subjected to reduction reaction treatment within a range that does not damage crystallinity in order to prevent charging during the manufacturing process and eliminate product defects caused by residual charges. Usually, in the case of epitaxial growth, in order to obtain sufficient crystallinity, the substrate is heated to about 600℃ to 1100℃ for growth.

[0013] However, if such a temperature is applied to LN single crystal and LT single crystal that have been subjected to reduction reaction, oxygen atoms in the process atmosphere diffuse to the substrate side and reoxidize, and the original charge suppression capability of the substrate is deteriorated. Therefore, epitaxial growth on LN single crystal and LT single crystal is preferably deposited by a low temperature process, and under such conditions, it is difficult to obtain a fully crystallized epitaxial film.

[0014] The problem to be solved by the present invention is to form a homoepitaxial thin film on the surface of a substrate having a surface of an LN single crystal or an LT single crystal.

[0015] Means for solving problems

[0016] The present invention for solving the above-mentioned problems is a method for manufacturing a homoepitaxial thin film, which deposits a composition identical to the above-mentioned single crystal on the above-mentioned surface of a substrate having a surface of a LiNbO3 single crystal or a LiTaO3 single crystal by a high-frequency sputtering method. Here, the substrate itself may be a substrate of a LiNbO3 single crystal or a LiTaO3 single crystal, or it may be a substrate of which only the surface is a LiNbO3 single crystal or a LiTaO3 single crystal.

[0017] In the above invention, the Euler angle of the above LiNbO3 single crystal surface is It can have a plane orientation of (0°±5°, 0°±5°, 0°±5°), (90°±5°, 90°±5°, 0°±5°), (180°±5°, 90°±5°, 0°±5°), (0°±5°, -95°~260°, 0°±5°) or a plane orientation crystallographically equivalent thereto.

[0018] In the above invention, the Euler angle of the above LiTaO3 single crystal surface is It can have a plane orientation of (90°±5°, 90°±5°, 0°±5°), (0°±5°, -95° to 140°, 0°±5°) or a plane orientation crystallographically equivalent thereto.

[0019] In the above invention, the temperature of the above substrate may be set to less than 450° C., preferably less than 350° C., and more preferably less than 250° C., and epitaxial growth may be performed by the above high-frequency sputtering method.

[0020] In the above invention, a direct current voltage may be applied to the substrate to perform epitaxial growth by the high-frequency sputtering method.

[0021] In the above invention, epitaxial growth can be performed by the high-frequency sputtering method using argon gas and oxygen gas as process gases.

[0022] In the above invention, epitaxial growth can be performed by the high-frequency sputtering method to alleviate the impact of positive ions or negative ions on the substrate.

[0023] In the above invention, the above single crystal may be subjected to a reduction reaction treatment.

[0024] The above-mentioned problems can also be solved by a homoepitaxial thin film manufacturing apparatus using the homoepitaxial thin film manufacturing method of the above-mentioned invention.

[0025] In addition, the present invention for solving the above-mentioned problems is a homoepitaxial thin film manufacturing device, which has a chamber and a high-frequency power supply for supplying high-frequency power to a target material arranged inside the above-mentioned chamber, and deposits a composition identical to the above-mentioned single crystal on a substrate having a surface of a LiNbO3 single crystal or a LiTaO3 single crystal arranged in the above-mentioned chamber by sputtering.

[0026] In the above invention, a sputtering electrode may be provided in which a surface normal line of the target material is offset from the substrate located at a film forming position.

[0027] In the above invention, the sputtering electrode may be arranged so that a surface normal line of the target material is inclined at 15° to 75° with respect to a surface normal line of the substrate.

[0028] The above invention may further include a shielding plate disposed in front of the target in the chamber so as to shield a surface where a surface normal of the target intersects with a surface of the substrate.

[0029] The above invention may further include a heater provided on the back side of the substrate to heat the substrate.

[0030] The above invention may further include a rotation shaft that is electrically floated relative to surrounding members and rotates the substrate from a back surface side of the substrate.

[0031] The above invention may further include a high-frequency matching device connected to the rotating shaft and capable of adjusting the reactance of the rotating shaft.

[0032] The above invention may further include a DC power supply, wherein the DC power supply is connected to the rotating shaft and applies a DC voltage to the rotating shaft.

[0033] In the above invention, a porous metal plate to which grounding or direct current voltage can be applied and a porous quartz plate covering the porous metal plate may be further provided in front of the target in the chamber.

[0034] The above invention may further include a susceptor that holds the single crystal substrate and has electrical conductivity, and heat is supplied from the heater to the substrate via the susceptor.

[0035] The above invention may further include a susceptor that holds the single crystal substrate and has conductivity, and a DC voltage may be applied to the substrate from the DC power supply via the susceptor.

[0036] The present invention for solving the above-mentioned problems is a homoepitaxial thin film formed on the surface of a LiNbO3 single crystal or a LiTaO3 single crystal and composed of the same composition as the above-mentioned single crystal.

[0037] In the above invention, the Euler angle of the above LiNbO3 single crystal surface is It can have a plane orientation of (0°±5°, 0°±5°, 0°±5°), (90°±5°, 90°±5°, 0°±5°), (180°±5°, 90°±5°, 0°±5°), (0°±5°, -95°~260°, 0°±5°) or a plane orientation crystallographically equivalent thereto.

[0038] In the above invention, the Euler angle of the above LiTaO3 single crystal surface is It can have a plane orientation of (90°±5°, 90°±5°, 0°±5°), (0°±5°, -95° to 140°, 0°±5°) or a plane orientation crystallographically equivalent thereto.

[0039] In the above invention, the above single crystal may be subjected to a reduction reaction treatment.

[0040] Effects of the Invention

[0041] According to the present invention, a homoepitaxial thin film can be formed on the surface of the substrate having the surface of the LN single crystal or the LT single crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a diagram showing an embodiment of the homoepitaxial thin film manufacturing apparatus of the present invention.

[0043] Figure 2 It is a cross-sectional view showing an embodiment of the homoepitaxial thin film of the present invention.

[0044] Figure 3 It is a graph showing the X-ray diffraction results of LiNbO 3 single crystal and homoepitaxial thin film (X-ray diffraction apparatus (SmartLab manufactured by Rigaku Corporation), out-of-plane crystallinity evaluation: ω-2θ measurement).

[0045] Figure 4 The diagram shows the X-ray diffraction results of LiNbO3 single crystal and homoepitaxial thin film (X-ray diffraction apparatus (Smart Lab manufactured by Rigaku Corporation), in-plane crystallinity evaluation: extreme point measurement LiNbO3 (012)).

[0046] Figure 5 1 and 2 are diagrams showing the X-ray diffraction results of LiNbO 3 single crystal and homoepitaxial thin film.

[0047] Figure 6 1 and 2 are diagrams showing the X-ray diffraction results of LiNbO 3 single crystal and homoepitaxial thin film.

[0048] Figure 7 1 and 2 are diagrams showing the X-ray diffraction results of LiNbO 3 single crystal and homoepitaxial thin film.

[0049] Figure 8 It is shown that the use Figure 1 A graph showing the X-ray diffraction results of 250 nm of homoepitaxial thin films formed by the homoepitaxial thin film manufacturing device and deposited on substrates having various crystal plane orientations.

[0050] Fig. 9 1 is a diagram showing a transmission electron microscope image and a selected area electron diffraction image of a LiNbO 3 single crystal and a homoepitaxial thin film (part 1).

[0051] Fig.10 2 is a diagram showing a transmission electron microscope image and a selected area electron diffraction image of a LiNbO 3 single crystal and a homoepitaxial thin film (part 2).

[0052] Fig.11 3 is a diagram showing a transmission electron microscope image and a selected area electron diffraction image of a LiNbO 3 single crystal and a homoepitaxial thin film.

[0053] Fig.12Graph showing the light absorption rate in the visible region before and after homoepitaxial thin film deposition of a LiNbO 3 single crystal subjected to a reduction treatment (spectrophotometer (Agilent Cary 7000)). DETAILED DESCRIPTION

[0054] Figure 1 The cross-sectional view shows an embodiment of the homoepitaxial thin film manufacturing apparatus 1 of the present invention. The homoepitaxial thin film manufacturing apparatus 1 of this embodiment is a sputtering apparatus that deposits a composition identical to that of an LN single crystal or an LT single crystal on the surface of a substrate having the surface of the single crystal by a high-frequency sputtering method.

[0055] That is, the homoepitaxial thin film manufacturing apparatus 1 of the present embodiment injects high frequency power into a target material composed of LN powder sintering or LT powder sintering to form plasma, and positive ions accelerated by a DC negative bias generated on the surface of the target material collide with the target material, thereby, particles sputtered from the surface of the target material are used as the material of the homoepitaxial thin film. It should be noted that the substrate 2 has a surface of a LiNbO3 single crystal or a LiTaO3 single crystal, and the LiNbO3 single crystal or the LiTaO3 single crystal may be subjected to a reduction reaction treatment.

[0056] like Figure 1 As shown, a homoepitaxial thin film manufacturing apparatus 1 includes a chamber 11 which can be set to a predetermined vacuum degree, a sputtering electrode 12 provided in the chamber 11 , and a susceptor 13 also provided in the chamber 11 .

[0057] The chamber 11 of this embodiment includes a film forming chamber 111 in which a target 121 mounted on a sputtering electrode 12 exists and a substrate 2 mounted on a susceptor 13 exists. The film forming chamber 111 can be set to a predetermined vacuum level by an exhaust device 113 provided at an exhaust port 112 of the chamber 11.

[0058] The sputtering electrode 12 of this embodiment supplies high-frequency power to the target 121 installed at the front end. The frequency of the high-frequency power is not limited, and may include a frequency of 13.56 MHz. In addition, the target 121 is an LN target or an LT target, but may also include a certain proportion of Li2O, and the molar ratio thereof includes LiNbO3 (or LiTaO3): Li2O in the range of 100:0 to 50:50.

[0059] The base 13 of this embodiment is made of a conductive material, holds the substrate 2, and can be rotated at a specified rotation speed by a driving device 132 connected to the rotating shaft 131. The base 13 can also be provided with a countersink (a recessed portion corresponding to the outer shape of the substrate 2) so that a deposition process can be performed on multiple substrates 2 in one process. The material constituting the base 13 is not particularly limited, and examples thereof include Inconel, silicon carbide, graphite, silicon, etc. The conductivity of the base 13 does not necessarily need to be displayed at room temperature, and can also be displayed when the substrate 2 is heated at less than 450°C.

[0060] In addition, a heater 133 for heating the substrate 2 to a predetermined temperature is provided at the bottom of the susceptor 13. The heating method of the heater 133 is not limited, and examples thereof include a resistance heating method using graphite or silicon carbide as a resistor, a light heating method using a halogen lamp, etc. If a homoepitaxial thin film is deposited by high-frequency sputtering while the substrate 2 is maintained at a temperature of less than 450° C., epitaxial growth of the deposited thin film can be promoted, and reoxidation of the LN single crystal or LT single crystal treated by the reduction reaction can be prevented.

[0061] The rotating shaft 131 of the susceptor 13 is maintained in an electrically floating state. By electrically floating the rotating shaft 131, it is possible to adjust to mitigate the impact of positive ions. By rotating the substrate 2 while depositing a thin film in an electrically floating state, it is possible to uniformly deposit a thin film on the entire surface of the substrate 2 while satisfying the requirement of mitigating the impact of negative ions.

[0062] The homoepitaxial thin film manufacturing apparatus 1 of the present embodiment includes a high frequency matcher 134, which is connected to the rotating shaft 131 of the susceptor 13 and can adjust the reactance of the electrically floating rotating shaft 131. The reactance here corresponds to the capacitance and inductance in the high frequency matcher 134. The adjustment of the high frequency matcher 134 is performed by measuring the DC voltage in the high frequency matcher 134 generated during deposition to diagnose the state of electrical coupling of the substrate 2 to the high frequency plasma.

[0063] Here, when the DC voltage shows a negative maximum value, it means that the capacitive substrate sheath and the capacitor are in a series resonance state, positive ions are attracted to the substrate 2, and reverse sputtering occurs. In contrast, when the DC voltage shows a positive maximum value, it corresponds to the parallel resonance state of the floating capacitance of the substrate 2 and the high-frequency matching device 134 including the rotating shaft 131, and negative charged particles are attracted to the substrate 2. In the case of this embodiment, by adjusting the reactance to the latter and maintaining it, the re-evaporation of Li atoms deposited on the substrate 2 caused by reverse sputtering can be suppressed, and the epitaxial growth of the deposited thin film can be promoted.

[0064] The homoepitaxial thin film manufacturing apparatus 1 of the present embodiment further includes a DC power supply 135, which is connected to the rotating shaft 131 and applies a DC voltage to the electrically floating rotating shaft 131. The DC power supply 135 may apply either a negative voltage or a positive voltage, but preferably applies a positive voltage from the viewpoint of promoting epitaxial growth of the deposited thin film.

[0065] The target 121 of this embodiment is arranged so as not to directly face the substrate 2. Figure 1 As shown, the target 121 is offset relative to the rotation axis 131, and the surface normal PL1 of the target 121 is set to an inclination α of 15° to 75° relative to the substrate normal PL2 of the substrate 2. The DC negative bias generated on the surface of the target 121 accelerates the negative ions in the plasma and releases the negative ions along the surface normal L1 of the target 121. Therefore, by making the substrate 2 and the target 121 not face each other, it is possible to avoid direct collision between the negative ions and the substrate 2, and to mitigate the impact caused by the negative ions. As a result, the epitaxial growth of the deposited thin film can be promoted.

[0066] The homoepitaxial thin film manufacturing apparatus 1 of the present embodiment includes a shielding plate 122, which mitigates the impact of negative ions emitted from the target 121 along the surface normal PL1 of the target 121. The shielding plate 122 of the present embodiment is configured to shield the surface where the surface normal PL1 of the target 121 intersects with the surface of the substrate 2 in front of the target 121. Thus, it is possible to suppress the negative ions emitted along the surface normal PL1 of the target 121 from impacting the substrate 2, and further promote the epitaxial growth of the deposited thin film.

[0067] The homoepitaxial thin film manufacturing apparatus of this embodiment includes a porous metal plate 123 and a porous quartz plate 124. Figure 1 As shown, the porous metal plate 123 and the porous quartz plate 124 of the present embodiment are arranged in front of the target material 121 of the inner wall of the film forming chamber 111, and the porous quartz plate 124 is configured on the front surface of the porous metal plate 123. The porous metal plate 123 is electrically coupled with the plasma and supplies electrons to the plasma. At this time, the potential of the porous metal plate 123 can be grounded, or a negative potential controlled to supply electrons more actively can be supplied. In addition, in order to improve the efficiency of the power consumed by the actual sputtering phenomenon in the high-frequency power invested in the target material 121, the surface area can also be increased by overlapping multiple porous metal plates 123. The porous quartz plate 124 plays a role in preventing the deposition of sputtered particles on the porous metal plate 123 and maintaining a constant supply of electrons. In addition, the porous quartz plate 124 also has the function of preventing the material of the sputtered porous metal plate 123 from being reversely deposited on the substrate 2 when the negative potential is supplied.

[0069] The homoepitaxial thin film manufacturing apparatus of the present embodiment further includes a gas supply device 125 for supplying argon gas and oxygen gas, which are process gases during film formation, to the film formation chamber 111 .

[0070] Example

[0071] Figure 2 1 is a cross-sectional view showing an embodiment of a homoepitaxial thin film of the present invention. In the example shown in the figure, a homoepitaxial thin film 22 is formed on an LN single crystal 21. Deposition using the homoepitaxial thin film manufacturing apparatus 1 of the present embodiment is performed by setting the target 121 to LN, the heating temperature of the substrate 2 by the heater 133 to 300° C., the sputtering rate to 0.2 angstroms / second, and the flow ratio of argon gas to oxygen gas to 50:50.

[0072] Figure 3 to Figure 7 This is a graph showing the X-ray diffraction results of a 250 nm homoepitaxial thin film formed using the homoepitaxial thin film manufacturing apparatus 1 of the present embodiment. The X-ray diffraction apparatus used was Smart Lab manufactured by Rigaku Corporation, and ω-2θ was measured for out-of-plane crystallinity evaluation.

[0073] Figure 3 The figure below is a graph showing the X-ray diffraction results of the Z-cut plane (Euler angle (0°, 0°, 0°)), and the figure below is an enlarged view of the peak portion of the figure above. Figure 3 As shown, the diffraction peak of the homoepitaxial thin film can be confirmed at a slightly lower 2θ position than the diffraction peak of the substrate of this example.

[0074] Figure 4 The figure below is a graph showing the X-ray diffraction results of the X-cut plane (Euler angle (90°, 90°, 0°), and the figure below is an enlarged view of the peak part of the upper figure. Figure 4 As shown, Figure 3 Similarly, in the result of the Z-cut surface, the diffraction peak of the homoepitaxial thin film can be confirmed at a slightly lower 2θ position than the diffraction peak of the substrate of this example.

[0075] Figure 5 to Figure 7 It is a rotated Y-cut plane (the respective Euler angles are (0°, -49°, 0°), (0°, 154°, 0°), (0°, -37°, 0°)). As shown in the figures, no unnecessary diffraction peaks are observed in the direction perpendicular to the surface of the substrate 2, which suggests the existence of a homoepitaxial thin film.

[0076] Figure 8This is a diagram showing the X-ray diffraction results of a 250 nm homoepitaxial thin film deposited on a substrate having various crystal plane orientations and formed using the homoepitaxial thin film manufacturing apparatus 1 of this embodiment. The X-ray diffraction apparatus used was Smart Lab manufactured by Rigaku Corporation, and the in-plane crystallinity evaluation was performed using the extreme point measurement of the LiNbO3 (012) plane. Figure 8 As shown, a diffraction pattern having a symmetry corresponding to each single crystal can be confirmed, and it can be determined that it is a thin film having the same crystal structure as the substrate, that is, a homoepitaxial thin film.

[0077] Figures 9 to 11 1 is a diagram showing a transmission electron microscope (TEM) image and a selected area electron diffraction (SAED) image of a 250 nm homoepitaxial thin film formed using the homoepitaxial thin film manufacturing apparatus 1 of the present embodiment. Figures 9 to 11 In each figure, the selected area electron diffraction image shown in the lower figure observes the part of the substrate and the part of the thin film represented by the circle in the upper figure respectively. Fig. 9 Observe the X-cut surface. Fig.10 Observe the 41Y cutting surface. Fig.11 Observe the 127Y cutting surface. Figures 9 to 11 In the selected area electron diffraction image of , the film shows a diffraction pattern equivalent to that of the substrate, so it can be directly confirmed that a homoepitaxial thin film having a single crystal structure equivalent to that of the substrate is deposited on a substrate having various crystal plane orientations.

[0078] Fig.12 Graph showing the light absorption rate of the homoepitaxial thin film of the reduced LN single crystal before and after deposition in the visible region, the dotted line represents the light absorption rate before deposition, and the solid line represents the light absorption rate after deposition. The spectrophotometer used was Cary 7000 manufactured by Agilent. Fig.12 As shown in FIG. 1 , there is almost no difference in the distribution of light absorption rate before and after the deposition of the homoepitaxial thin film. In addition, the LN single crystal that has not been subjected to the reduction treatment has no light absorption rate, which indicates that the homoepitaxial thin film deposited in this example has not been reoxidized on the substrate.

[0079] Description of Reference Numerals

[0080] 1…Homoepitaxial thin film manufacturing device

[0081] 11…Chamber

[0082] 111…Film-forming room

[0083] 112…Exhaust port

[0084] 113…Exhaust

[0085] 12…Sputtering electrode

[0086] 121…Target

[0087] 122…Shielding plate

[0088] 123… porous metal sheet

[0089] 124…Porous quartz plate

[0090] 125…Gas supply device

[0091] 13…Base

[0092] 131…Rotation axis

[0093] 132…Driver

[0094] 133…Heater

[0095] 134…High frequency matching device

[0096] 135…DC power supply

[0097] PL1…Surface normal of target

[0098] PL2…Surface normal of substrate

[0099] α…The angle between the surface normal of the target and the surface normal of the substrate

Claims

1. A method for producing a homoepitaxial thin film, comprising depositing a composition identical to that of a LiNbO3 single crystal or a LiTaO3 single crystal on a surface of a substrate having the surface of the single crystal by a high-frequency sputtering method.

2. The method for producing a homoepitaxial thin film according to claim 1, wherein: Euler angles of the LiNbO3 single crystal surface It has a plane orientation of (0°±5°, 0°±5°, 0°±5°), (90°±5°, 90°±5°, 0°±5°), (180°±5°, 90°±5°, 0°±5°), (0°±5°, -95°~260°, 0°±5°) or a crystallographically equivalent plane orientation.

3. The method for manufacturing a homoepitaxial thin film according to claim 1, wherein: Euler angle of the LiTaO3 single crystal surface It has a plane orientation of (90°±5°, 90°±5°, 0°±5°), (0°±5°, -95°~140°, 0°±5°) or a plane orientation crystallographically equivalent thereto.

4. The method for producing a homoepitaxial thin film according to any one of claims 1 to 3, wherein: The temperature of the substrate is set to less than 450° C., and epitaxial growth is performed by the high-frequency sputtering method.

5. The method for producing a homoepitaxial thin film according to any one of claims 1 to 4, wherein: A direct current voltage is applied to the substrate, and epitaxial growth is performed by the high-frequency sputtering method.

6. The method for producing a homoepitaxial thin film according to any one of claims 1 to 5, wherein: The epitaxial growth is performed by the high-frequency sputtering method using argon gas and oxygen gas as process gases.

7. The method for producing a homoepitaxial thin film according to any one of claims 1 to 6, wherein: The epitaxial growth is performed by the high-frequency sputtering method to alleviate the impact of positive ions or negative ions on the substrate.

8. The method for producing a homoepitaxial thin film according to any one of claims 1 to 7, wherein: The single crystal is subjected to a reduction reaction treatment. 9 . A homoepitaxial thin film manufacturing apparatus using the homoepitaxial thin film manufacturing method according to any one of claims 1 to 8.

10. A homoepitaxial thin film manufacturing apparatus comprising a chamber and a high-frequency power supply for supplying high-frequency power to a target material arranged inside the chamber, The same composition as that of the single crystal is deposited on a substrate having a surface of the LiNbO 3 single crystal or the LiTaO 3 single crystal disposed in the chamber by a sputtering method. 11 . The homoepitaxial thin film manufacturing apparatus according to claim 10 , comprising a sputtering electrode arranged so that a surface normal of the target material is offset with respect to a substrate located at a film forming position.

12. The homoepitaxial thin film manufacturing apparatus according to claim 11, wherein: The sputtering electrode is arranged so that a surface normal line of the target is inclined at 15° to 75° with respect to a surface normal line of the substrate. 13 . The homoepitaxial thin film manufacturing apparatus according to claim 10 , further comprising a shielding plate arranged in front of the target in the chamber to shield a surface where a surface normal of the target intersects with a surface of the substrate. 14 . The homoepitaxial thin film manufacturing apparatus according to claim 10 , further comprising a heater, the heater being provided on the back side of the substrate to heat the substrate. 15 . The homoepitaxial thin film manufacturing apparatus according to claim 10 , further comprising a rotation shaft which is electrically floated relative to surrounding members and rotates the substrate from a back side of the substrate. 16 . The homoepitaxial thin film manufacturing apparatus according to claim 15 , further comprising a high-frequency matching device, wherein the high-frequency matching device is connected to the rotating shaft and is capable of adjusting the reactance of the rotating shaft. 17 . The homoepitaxial thin film manufacturing apparatus according to claim 15 or 16 , further comprising a DC power supply, wherein the DC power supply is connected to the rotating shaft and applies a DC voltage to the rotating shaft. 18 . The homoepitaxial thin film manufacturing apparatus according to claim 10 , further comprising a porous metal plate capable of being grounded or applied with a direct current voltage, and a porous quartz plate covering the porous metal plate, in front of the target inside the chamber.

19. The homoepitaxial thin film manufacturing apparatus according to claim 14, further comprising a susceptor which holds the substrate and has conductivity. Heat is supplied from the heater to the substrate via the susceptor.

20. The homoepitaxial thin film manufacturing apparatus according to claim 17, further comprising a susceptor which holds the substrate and has conductivity. A DC voltage is applied to the substrate from the DC power supply via the susceptor.

21. A homoepitaxial thin film formed on the surface of a LiNbO3 single crystal or a LiTaO3 single crystal and composed of the same composition as the single crystal.

22. The homoepitaxial thin film according to claim 21, wherein Euler angles of the LiNbO3 single crystal surface It has a plane orientation of (0°±5°, 0°±5°, 0°±5°), (90°±5°, 90°±5°, 0°±5°), (180°±5°, 90°±5°, 0°±5°), (0°±5°, -95°~260°, 0°±5°) or a crystallographically equivalent plane orientation.

23. The homoepitaxial thin film according to claim 21, wherein Euler angle of the LiTaO3 single crystal surface It has a plane orientation of (90°±5°, 90°±5°, 0°±5°), (0°±5°, -95°~140°, 0°±5°) or a plane orientation crystallographically equivalent thereto.

24. The homoepitaxial thin film according to any one of claims 21 to 23, wherein The single crystal is subjected to a reduction reaction treatment.

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