JPH0692787A - Formation of single crystalline thin film - Google Patents

Abstract

PURPOSE:To form the single crystalline thin film having excellent crystallinity on a base material without depending on the material quality and crystallinity of the base material. CONSTITUTION:The base material 1 is provided thereon with a mask 2 which can prevent the sticking of the chemical species in a gaseous phase 3 to the base material. The base material 1 is continuously moved in an arrow A direction, by which the part covered with the mask 2 is successively delivered to the gaseous phase 3 for crystal growth. The thin film is successively deposited from the gaseous phase 3 to the part delivered from below the mask 2 on the base material 1 in such a manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a single crystalline thin film on a substrate, and more particularly to a method for forming a single crystalline thin film made of an oxide material on a long substrate. .

[0002]

2. Description of the Related Art In the manufacturing technology of semiconductor devices, liquid phase epitaxy (L
PE), metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), ion beam epitaxy (IB)
Various methods such as E) are adopted. These methods are
It is possible to form a high-quality single crystal thin film, which is an indispensable technique in the manufacture of semiconductor devices.

In the field of superconductivity, liquid nitrogen temperature (77.
Y system (90K), which has higher critical temperature than 3K), Bi
With the discovery of the (108K) -based and Tl-based (125K) oxide superconducting materials, methods for forming single crystal thin films have been studied in order to apply these materials to electronic devices. It has been found that methods such as a laser vapor deposition method and a reactive vapor deposition method are effective for forming a high quality single crystal thin film for an oxide superconducting material.

[0004]

The conventional method for forming a single crystal thin film described above utilizes epitaxy, that is, the phenomenon that another kind of crystal grows on a specific crystal plane with a certain orientation relationship. In general, a thin film is formed on the surface of a single crystal substrate.

Since these conventional methods are premised on the use of a single crystal substrate, in order to form a good quality single crystal thin film, a single crystal substrate having a crystal structure similar to that of the thin film material and having a close lattice constant is adopted. Was extremely important.

Therefore, in the above-mentioned prior art, the single crystal thin film can be formed only on the substrate made of a specific material, and the size of the single crystal thin film that can be formed is also determined by the size of the substrate that can be adopted. However, it has not been possible to freely form a single crystal thin film having a desired size and length.

On the other hand, in the field of semiconductor thin films, an amorphous substrate having periodic grooves engraved on its surface is used, and crystal nuclei are generated in selective orientations at the groove edges.
There is a graphoepitaxy technique for single crystallization of a film deposited on a substrate. According to this technique, a single crystal thin film having excellent crystallinity for Si can be formed without using a single crystal substrate.

However, even in graphoepitaxy, the size of the substrate on which the periodic grooves can be formed is limited. Therefore, as described above, a single crystal thin film can be freely formed on a base material having a desired size and length. Was difficult to form.

An object of the present invention is to provide a method capable of forming a single crystal thin film having excellent crystallinity on a base material without depending on the material and crystallinity of the base material.

A further object of the present invention is to provide a method capable of freely forming a single crystal thin film having excellent crystallinity on a substrate having a desired size.

[0011]

A method for forming a single crystalline thin film according to the present invention is for forming a single crystalline thin film mainly composed of crystals having a specific orientation in a continuous region on a substrate. More preferably, it is for forming a single crystal thin film made of a crystal having a single orientation. The method according to the present invention provides a mask capable of preventing the chemical species in the gas phase from adhering to the substrate, and moving the substrate relative to the mask, thereby removing the substrate to be crystal-grown. It is characterized in that the portion covered by the mask in the continuous region is continuously sent to the environment for crystal growth.

In the present invention, the substrate may be of any material and shape. The material and shape of the base material are those obtained by forming a single crystalline thin film,
The method of the present invention can be applied to form a single crystal thin film on a longer substrate, such as a tape-shaped substrate, although it may be appropriately determined depending on the film forming conditions.

In the present invention, the mask for covering the base material is not particularly limited as long as it can prevent chemical species for vapor phase growth from adhering to the base material, and its material and shape. As the above, those preferable may be appropriately used depending on the film forming conditions and the like.

The mask must be provided so as to effectively prevent chemical species in the gas phase from flying onto the substrate. Therefore, when covering the base material with the mask, it is necessary to prevent molecules and atoms for vapor phase growth from entering the gap between the mask and the base material. Therefore, depending on the conditions for vapor phase growth, for example, when using the vapor deposition method or the like, the distance between the substrate and the mask is preferably 3 mm or less.

In the present invention, the substrate is moved relative to the mask. That is, when the mask is fixed, the base material is moved, and when the base material is fixed, the mask is moved. Further, the mask and the base material may be moved together.

For example, when a single crystalline thin film is to be formed on a base material using a tape-shaped base material, a mask is fixed and the tape-shaped base material is continuously passed through the mask in a vapor phase for crystal growth. You can send it to.

Since the tape-shaped base material can be wound, the tape-shaped base material is unwound from the first reel and, while being wound on the second reel, crystals are to be grown through the mask. It is also possible to feed the base material into the phase and sequentially form the single crystalline thin film on the tape.

It is also possible to cover the substrate with a mask having a window such as a slit so that the chemical species in the gas phase can be attached to the substrate through the window. In this case, if the base material or the mask is moved so that the window moves on the base material, the single crystalline thin film can be formed on the base material on the portion where the window passes.

In the present invention, the environment phase for crystal growth is a vapor phase, and sputtering and vapor deposition methods can be used for vapor phase growth of crystals.

The vapor phase growth method preferably used in the present invention includes, for example, laser vapor deposition method, reactive vapor deposition method,
Metal Organic Chemical Vapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE) and Ion Beam Epitaxy (IB)
E) etc.

Further, in the present invention, a thin film mainly composed of crystals having a specific orientation in a continuous region on the substrate can be formed in the vapor phase by the laser ablation method.

In this case, when the base material is moved relative to the mask, in a continuous region of the base material on which the crystal is to be grown, the portion covered by the mask and the environment for crystal growth are exposed. It is preferable that the boundary region with the portion to be formed is sent to the environment for crystal growth at a moving speed of 1 cm / min or more.

In this case, the laser ablation is performed at a substrate temperature of 650 to 750 ° C. and an oxygen gas pressure of 30 to.
A laser energy density of 1.5 to 3.3 J is used by using a laser having a wavelength region of 500 mTorr, 248 to 1060 nm.
More preferably, it is carried out under the condition of / cm ² .

The speed at which the boundary region between the portion covered by the mask and the portion exposed to the environment for crystal growth is sent to the environment for crystal growth is, for example, by changing the moving speed of the substrate relative to the mask. It can be adjusted freely.

For example, when it is desired to form a single crystal thin film on a base material using a tape-shaped base material, the tape-shaped base material is moved at a moving speed of 1 cm / min or more relative to the fixed mask. By sending out into the gas phase, the single crystalline thin film can be sequentially formed on the tape-shaped substrate according to the method described above.

In the present invention, it is also possible to use a base material on which a metal thin film is formed in advance. In this case, the metal thin film can be evaporated in a single crystal thin film forming environment, and the metal thin film is formed in a boundary region between a portion covered by the mask and a portion exposed to the environment for crystal growth on the base material. A temperature gradient is provided so that the thin film forms a solid-liquid boundary.

This temperature gradient is such that the temperature decreases as it goes from the vapor phase for crystal growth to the place where the mask is provided. For example, it is provided by adjusting the substrate temperature with a heater or cooling means. You can Such a temperature gradient can promote the alignment of crystal orientations of the formed thin film.

Further, in the present invention, by flowing a gas in the direction in which the base material is relatively moved, the base material is released to a portion of the base material where the mask is uncovered and sent to the environment for crystal growth. It is possible to provide a gas flow in the same direction as the relative movement direction of.

Such a gas flow can be generated, for example, by discharging gas from a slit-shaped hole provided at the end of the mask toward the environment for crystal growth.

The direction of the gas flow depends on the atmosphere for crystal growth, but it is desirable to maintain it within a predetermined range in which crystal growth is performed. By using this gas flow, it is possible to grow a single crystalline thin film so that specific crystal orientations are aligned with the gas flow direction.

When it is desired to form a thin film composed of oxide crystals, oxygen gas can be preferably used as the gas.

The method for forming a single crystalline thin film of the present invention described above is particularly applied as a method for forming a single crystalline thin film of an oxide superconductor on a substrate. As described above, the oxide superconductor includes a Y-based material such as Y-Ba-Cu-O, B, or the like.
Bi system such as i-Sr-Ca-Cu-O, Tl-Bi-S
Examples include Tl-based compounds such as r-Ca-Cu-O.

In order to form a monocrystalline thin film made of an oxide superconductor according to the present invention, for example, various vapor deposition methods such as reactive vapor deposition, laser ablation, MBE, CV, etc.
Methods such as D, ion plating, spray pyrolysis, and flash plasma can be used.

For example, when laser ablation is used to form a single crystalline thin film of an oxide superconductor, Y
Of a system-based, Bi-based or Tl-based sintered body target with a laser to generate plasma, and the base material sent out from under the mask is exposed to this plasma to form a single crystalline thin film made of a superconductor. be able to.

Conventionally, a thin film of an oxide superconducting material has been formed.
Single crystals of MgO, SrTiO ₃ , ZrO _{2 and the} like have been used as the substrate, but in the present invention, not only these materials but also MgO, SrTiO ₃ and Zr are used as the base material.
Polycrystalline such and rO _2, can be used yttria-stabilized zirconia sheet and metal substrates such as metal tape and the like.

When a single crystalline thin film of an oxide superconductor is formed according to the present invention, oxygen gas is preferred as the gas flowing in the moving direction of the substrate as described above. Further, the metal film formed in advance on the substrate is preferably made of silver, for example.

[0037]

1 (a) to 1 (c) are perspective views schematically showing a process of forming a thin film according to the present invention.

According to the present invention, as shown in FIG. 1 (a), the base material 1 is sent out from one end thereof through the mask 2 into the vapor phase 3 for crystal growth. The sent-out direction is the direction of arrow A shown in the figure.

On the other hand, the chemical species existing in the vapor phase 3 are deposited on the substrate 1 as shown by the arrow B in the figure. As shown in the figure, the chemical species in the vapor phase do not adhere to the portion of the substrate 1 covered with the mask 2, while the chemical species attach to the portion sent out from under the mask 2 into the vapor phase. become.
In this way, when the base material 1 is continuously sent out in the direction of the arrow A, a thin film is continuously formed on the base material.

Next, a process in which a single crystalline thin film is formed by moving the base material will be described. First, for the sake of explanation, it is assumed that the base material is sent out from a state in which one end of the base material is slightly in the gas phase. FIG. 1B shows a point in time when the base material is being sent out from FIG. 1A. The region indicated by 1a in the base material 1 is a region where the base material has been exposed to the gas phase before the movement, and has not experienced the movement from under the mask to the gas phase.

In this region, the thin film formed on the surface of the base material is often a crystal having a random orientation or an amorphous state. Even when the thin film has a natural orientation, the crystal of the thin film orients a specific crystal axis in the normal direction on the surface of the substrate, but rarely achieves the specific orientation in the plane of the substrate.

On the other hand, in the region which has undergone the movement between the region 1a and the mask 2, crystals having various orientations are formed in the initial portion 1b under the influence of the region which is not moved. Accordingly, a specific crystal orientation becomes dominant, and a region 1c having the same orientation is formed. In the figure, in order to schematically show such a state, the distribution state of the crystal orientation is represented by an arrow.

This is because the crystal growth edge is formed in the boundary region between the portion covered by the mask and the portion exposed to the vapor phase in the substrate, and the same orientation as this growth edge is formed on the substrate newly exposed by the movement. It is believed that this is due to the tendency of crystals having Therefore, if a growth edge having a specific crystal orientation can be reliably formed, a thin film having strong single crystallinity can be formed without being significantly affected by the material of the base material and the crystal orientation.

When the substrate is further moved in this manner, crystals having the same orientation as that of the region 1c will grow (FIG. 1 (c)). As shown above, once the specific oriented grains are formed, the continuous movement of the substrate and the effect of the mask make the crystalline grains having a specific orientation continuous regardless of the material and crystal orientation of the substrate. Will be formed on the substrate.

In the method described above, a tape-shaped substrate is used, and if the substrate is moved in the longitudinal direction from one end of the tape, a monocrystalline thin film can be formed in the longitudinal direction of the substrate. You can

Further, according to the present invention, in a method for forming a thin film mainly composed of crystals having a specific orientation in a continuous region on a substrate from a gas phase by using a laser ablation method, the substrate is When moving relative to the mask, the boundary region between the part covered by the mask and the part exposed to the environment for crystal growth is a continuous region of the base material to be crystal-grown. Is sent to the environment for moving at a moving speed of 1 cm / min or more, and is almost affected by the distance between the mask and the substrate on the substrate newly exposed to the environment for crystal growth. It is possible to form a thin film having strong single crystallinity.

This is because the boundary region between the portion covered with the mask during vapor phase growth and the portion exposed to the environment for crystal growth is sent to the environment for crystal growth at a moving speed of 1 cm / min or more. , The time period of contact of the boundary region with molecules and atoms for vapor phase growth caught in a small space between the mask and the substrate is further shortened, and a specific crystallographic orientation is provided in the boundary region on the substrate. The sharp edges of the crystals are more reliably formed, and as a result, crystal grains having a specific crystal orientation are further formed on the substrate newly exposed to the environment for crystal growth. It is thought to be easier.

According to the above method, as shown in the following examples, even when the distance between the mask and the base material is set to be larger than 3 mm, the single crystal thin film having the uniform crystal orientation is formed on the base material. Can be formed.

Further, as shown in FIG. 2, when a mask 12 having a window 12a formed thereon is covered on a base material 11 and vapor deposition or the like is performed on the mask 12, a thin film is formed only on the window 12a of the base material 11. be able to. If the substrate 11 or the mask 12 is continuously moved in this state, a thin film can be formed in the region 11a (shown by the one-dot chain line in FIG. 1) where the window 12a has moved.

In this case as well, since the above-described continuous movement and the effect of the mask are brought about, a monocrystalline thin film can be formed in the region 11a. By using such a mask, a single crystal thin film can be formed in an arbitrary region on the base material.

Further, as shown in FIG. 3, a base material 21 on which a metal thin film 20 is formed in advance is used, and a boundary area between a part of the base material 21 covered with the mask 22 and a part exposed to the vapor phase 23 (see FIG. (Indicated by C in FIG.
A single crystalline thin film can be formed. The temperature gradient can be set by, for example, the heater 24 provided below the base material.

Due to the set temperature gradient, the metal thin film has a solid-liquid boundary in the boundary region C. The state of the solid-liquid boundary is enlarged and shown in FIG. As shown in the figure, in the portion 21a covered with the mask 23, the metal thin film 20 of a predetermined thickness remains, but in the boundary region C, the metal thin film melts to form a solid-liquid boundary and the temperature is high. The metal forming the thin film comes to evaporate from the portion.

As a result, the film in the boundary region C is eroded and has a step shape. Such a state can be observed with an electron microscope. For example, when a thin silver film is formed on a substrate, stairs are formed in a shape corresponding to the contour lines of temperature, and the height of one staircase is about 100Å.
An electron microscope observation revealed that the width of the terrace is about 1000 Å.

When a mask is provided so that the film formation region is interrupted in the region where the steps are formed in this way, that is, the growth end of the crystal is formed, the chemical species deposited from the vapor phase are the corners of the steps. The nucleus will be generated by aligning the directions.
Then, when the base material is continuously moved in the direction of the arrow shown in FIG. 3, since the steps of the metal thin film are always formed in the region where the temperature gradient is provided, the thin film has the orientation aligned with the corner of this step. Will grow up. As a result, a single crystalline thin film is continuously formed.

The formation of a thin film provided with such a temperature gradient is
As described above, the present invention can be applied to a case where a single crystalline thin film is formed in the longitudinal direction of a tape-shaped substrate, or a case where a mask having a window is provided and a single crystalline thin film is formed on an arbitrary region of the substrate.

Further, in the present invention, the base material is moved as described above, and as shown in FIG.
The moving direction of the base material 31 from the end portion 32a of 2 (arrow D in the figure).
The gas having a specific orientation can be grown in the region of the base material 31 where the directionality of the gas flow is maintained by flowing the gas 34 (shown in FIG.

The region in which the directionality of the gas flow is maintained is considered to be limited to a very narrow range, but once a thin film with uniform orientation is formed in this region, the region in which the directionality of the gas flow collapses ( For example, even if the film is formed at a portion apart from the gas ejection port), the film can be formed according to the orientation of the base film formed according to the gas flow. Therefore, even in the case of forming a thick film, it is possible to grow a crystal having a specific orientation by aligning the orientation with the underlayer whose orientation is controlled by the gas flow.

Thus, the gas flow acts so as to form crystal nuclei having a specific orientation. Then, by successively moving the base material and exposing the region covered with the mask to the vapor phase in sequence, thin film growth can be performed so that the orientation is aligned with the crystal whose orientation is controlled by the gas flow as described above. I will proceed. In this way, it is possible to form a single crystal thin film having a uniform crystal orientation on the substrate.

As described above, the formation of a thin film for generating such a gas flow is performed when a single crystalline thin film is formed in the longitudinal direction of a tape-shaped substrate or when a mask having a window is provided to form an arbitrary substrate. It can be applied when a single crystalline thin film is formed in a region.

[0060]

【Example】

Example 1 As a base material, a Ni-Cr alloy tape having a thickness of 0.1 mm and a width of 5 mm was used, and a mask 42 was used as a base material 4 as shown in FIG.
A gap (d) of 0.1 mm was provided on the sheet 1 and fixed.

A reactive vacuum deposition method was used to form a thin film of yttria-stabilized zirconia on the Ni alloy tape. Oxygen is used as the reaction gas, and the gas pressure is 3 mTo
rr. The temperature of the base material was set to 750 ° C.

As described above, the thin film of yttria-stabilized zirconia was vacuum-deposited while continuously moving the substrate 41 in the direction of arrow E at a speed of 2 mm / min in FIG.

At this time, a non-oriented yttria-stabilized zirconia thin film was formed in the portion up to 5.2 cm from the tape tip, and subsequently, in the portion extending 3.8 cm, the (100) axis was perpendicular to the substrate surface. The resulting film was a uniaxially oriented film, and subsequently, the (010) axis and the (001) axis were strongly oriented in the plane of the substrate, and an yttria-stabilized zirconia thin film with uniform orientation was formed within an inclination angle of 5 °. It was confirmed by X-ray diffraction that this orientation (biaxial orientation) was realized over a length of 3 m.

For longer lengths, as long as the conditions of vacuum vapor deposition and the conditions of continuous movement of the substrate are stable, and the mask is fixed, the biaxial orientation is strong.
That is, it was expected that a single crystal thin film could be obtained.

Example 2 Using the same Ni-Cr alloy tape as in Example 1, as a substrate, a thin film of yttria-stabilized zirconia was formed by laser ablation.

Laser ablation is performed as shown in FIG. 7, and the Y-based sintered body target 54 is irradiated with a laser 55 to generate a plume 56 as shown in the drawing in a direction perpendicular to the target surface. The chemical species in the plume 56 were made to adhere to the base material 51 continuously fed from the mask 52. In laser ablation, the temperature of the base material was set to 650 to 750 ° C., and the pressure of oxygen gas was set to 30 to 500 mTorr. Also,
KrF excimer laser (wavelength 248 nm)
Laser energy density is 1.5 to 3.3 J / cm.
^{2. The} laser repetition frequency was 1 Hz to 100 Hz. The gap (d) between the base material 51 and the mask 53 is 0.1.
It was set to mm.

Even when laser ablation was used in this way, a yttria-stabilized zirconia thin film having strong single crystallinity could be formed over a length of 2 m from 12.5 cm from the tip of the tape-shaped substrate.

Example 3 Using the same substrate as in Example 1, first, a yttria-stabilized zirconia thin film was formed on the substrate without a mask. The thin film thus formed is (1
The (00) axis and the (111) axis were mixed and stood vertically and showed random orientation in the in-plane direction of the substrate.

Then, a Y ₁ Ba ₂ Cu ₃ O _x thin film was formed on the yttria-stabilized zirconia thin film formed on the substrate according to the present invention by using the laser ablation method as shown in FIG. 7. In the laser ablation method, the oxygen gas pressure was 200 mTorr and the substrate temperature was 7
The film formation rate was set to 00 ° C. and to 1.5 μm / min. Also,
As the laser, an excimer laser is used as in the second embodiment, and 1
The substrate is continuously moved at a speed of 8 mm / min, and Y ₁ Ba
_{A 2} Cu ₃ O _x thin film was continuously formed.

The thin film thus formed becomes a c-axis oriented film over the entire length of the tape, and is 5.
The orientation of the a and b axes becomes stronger from 6 cm,
It was confirmed that the orientation was within 4 ° over a length of 1.4 m.

Example 4 A tape-shaped substrate 1 m having the yttria-stabilized zirconia thin film having a strong single crystal prepared in Example 2 was prepared. Next, using a mask as in Example 3, laser ablation was performed under conditions of a substrate temperature of 700 ° C., an oxygen gas pressure of 200 mTorr, a film forming rate of 1.5 μm / min, and a substrate moving speed of 18 mm / min. And Y ₁ Ba ₂ Cu ₃ O
_{An X} thin film was formed.

In this case, a c-axis oriented film having a strong single crystal property was formed 8 mm from the tip of the tape, and the orientation of the film in the in-plane direction of the substrate was within 2 °, which was extremely good.

On the other hand, for comparison, the mask is not received.
By laser ablation method ₁Ba₂Cu₃O_X
Was formed, but the orientation in the in-plane direction of the substrate was 4 ° or more.
Met. In this way, a mask can be provided to form a thin film.
Reveals that a thin film with strong single crystal can be obtained
Became.

Example 5 The gap between the tape-shaped substrate and the mask in Example 4
Although (d) was 0.1 mm, it should be noted that
The value (d) of the gap is 0.1 mm to 5
mm, and other conditions are the same as in Example 4.
Then Y₁Ba₂Cu ₃O_XA thin film was formed.

As a result, for each value of the gap,
The tilt angle showing the orientation in the in-plane direction of the substrate as shown in Table 1 was obtained.

[0076]

[Table 1]

As shown in Table 1, it was revealed that in this example, if the gap (d) was 3 mm or less, a thin film having strong single crystallinity could be obtained.

Example 6 A thin film of yttria-stabilized zirconia and magnesium oxide was formed by using a Ni-based alloy tape called Hastelloy having a thickness of 0.1 mm and a width of 5 mm as a substrate and using a laser ablation method as shown in FIG. Were individually formed.

In the laser ablation method, the substrate temperature is set to 650 to 750 ° C., and the oxygen gas pressure is 30.
It was set to ˜500 mTorr. Also, as a laser K
Using an rF excimer laser (wavelength 248 nm), the laser energy density was 1.5 to 3.3 J / cm ² , and the laser repetition frequency was 1 to 100 Hz. In addition, the base material 51
The gap (d) between the mask 52 and the mask 52 was set to 0.8 mm.

In this embodiment, how the moving speed of the boundary region between the portion of the base material 51 covered with the mask 52 and the portion exposed to the environment for vapor phase growth has an effect on the film formation. In order to investigate the above, the moving speed of the base material 51 with respect to the mask 52 was changed in the range of 0.1 to 1.5 cm / min to form a thin film having a thickness of 0.2 μm over the entire base material.

The in-plane orientation of each of the obtained yttria-stabilized zirconia thin film and magnesium oxide thin film was investigated.

As a result, in each of the formed thin films, the (100) axis is oriented perpendicularly to the tape substrate surface, and along the growth edge of the thin film crystal in the direction parallel to the substrate surface ( The (010) axis was oriented.

In order to compare the degree of (010) in-plane orientation in each thin film, the mutual inclination of each crystal grain is ± 5 °.
The ratio within the range was determined, and the results are shown in Table 2.

[0084]

[Table 2]

As shown in Table 2, the moving speed of the tape base material with respect to the mask is 1 cm / min or more, that is, the boundary between the part of the base material covered with the mask and the part exposed to the environment for vapor phase growth. It has been clarified that a thin film having a good in-plane orientation can be obtained when the moving speed of the region is 1 cm / min or more.

Example 7 As in Example 6, the base material had a thickness of 0.1 mm and a width of 5 m.
First, a yttria-stabilized zirconia thin film was formed on a base material without using a mask by using a Ni-based alloy tape called m. Hastelloy. The thin film thus formed was one in which the (100) axis and the (111) axis were mixed and stood vertically on the surface of the substrate, and showed random orientation in the in-plane direction of the substrate.

Then, a Y ₁ Ba ₂ Cu ₃ O _x thin film was formed according to the present invention on the yttria-stabilized zirconia thin film formed on the substrate by using the laser ablation method as shown in FIG. 7. In the laser ablation method, the substrate temperature is set to 700 ° C. and the oxygen gas pressure is set to 2
It was set to 00 mTorr. Also, as a laser, KrF
Using an excimer laser (wavelength 248 nm), the laser energy density was 1.5 to 3.3 J / cm ² , and the laser repetition frequency was 1 to 100 Hz. The gap (d) between the base material 51 and the mask 52 was set to 1.0 mm.

In this embodiment, how the moving speed of the boundary region between the portion of the base material 51 covered with the mask 52 and the portion exposed to the environment for vapor phase growth has an effect on the film formation. In order to investigate the above, the moving speed of the base material 51 with respect to the mask 52 was changed in the range of 0.1 to 2.0 cm / min to form a thin film having a thickness of 1.0 μm over the entire base material.

The in-plane orientation of the obtained Y ₁ Ba ₂ Cu ₃ O _x thin film was investigated.

As a result, the thin film thus formed was one in which the c-axis was perpendicular to the surface of the substrate, and the a-axis and the b-axis were strongly oriented along the growth edge of the thin film crystal.

Further, in order to compare the degree of (010) in-plane orientation in the thin films, a ratio in which the inclination of the a-axis of each crystal grain is within ± 5 ° was obtained, and the results are shown in Table 3.

[0092]

[Table 3]

As shown in Table 3, the moving speed of the tape base material with respect to the mask is 1 cm / min or more, that is, the portion of the tape base material covered with the mask and the portion exposed to the environment for vapor phase growth. When the moving speed of the boundary region was 1 cm / min or more, the ratio exceeded 90%, and it was revealed that a thin film having good in-plane orientation can be obtained.

As can be seen from the above Examples 6 and 7, the moving speed of the boundary region between the portion of the base material covered with the mask and the portion exposed to the environment for vapor phase growth should be 1 cm / min or more. It was confirmed that good in-plane orientation can be achieved without setting the distance (d) between the mask and the substrate to 3 mm or less.

Example 8 Using a Ni-Cr alloy tape having a thickness of 0.1 mm and a width of 5 mm as a base material, a magnesium oxide thin film was formed on the base material by the reactive vacuum deposition method in the same manufacturing process as in the first embodiment. Formed. In this case, 3.2 cm from the tape tip
From this, a magnesium oxide thin film having strong single crystallinity was formed.

In the thin film thus formed, the (100) axis is oriented perpendicularly to the tape substrate surface, and the (010) axis is parallel to the tape substrate surface in one direction within an angle of 4 °. It was oriented. Also, the (001) axis was oriented to the same extent as the (010) axis.

Example 9 Bi was deposited on the magnesium oxide thin film prepared in Example 8.₂
Sr₂Ca₂Cu₃O _XThe thin film of excimer laser
It was formed by a solution method. Laser ablation method
Is a base material temperature of 720 ° C., oxygen gas pressure of 110 mTorr
r, the continuous moving speed of the substrate is 1.3 mm / min, and the film forming speed is 0.
It was performed under the condition of 18 μm / min. The thin film obtained is
Strong single crystal from 3.8 cm from the tape tip
It becomes a film and has c-axis orientation, and tilts of a-axis and b-axis
The angle was within 3.2 ° over the entire length.

Example 10 In Examples 1 to 9 described above, a thin film was formed on a tape-shaped substrate, but in Example 10, a mask having a window as described above was used to form a thin film on the substrate. A single crystalline thin film was formed in a predetermined area.

A yttria-stabilized zirconia sintered body sheet (50 × 50 mm) was used as a substrate, and a stainless steel mask (150 × 150 mm) having a 10 × 10 mm square window was used as a mask. Under the same film forming conditions as in Example 3, the gap between the mask and the substrate was 0.2 mm.
Then, the mask was continuously moved as shown in FIG. 2 to form a Y ₁ Ba ₂ Cu ₃ O _x thin film on the surface of the base material.

In the film thus formed, it was revealed that the a and b axes were oriented at an inclination angle of 3 ° or less. On the other hand, since the zirconia base material is a polycrystalline material, when a thin film is formed as it is on the base material without using a mask, c
A film in which only the axes were oriented was obtained, and the a and b axes were non-oriented.

Example 11 As a base material, a yttria-stabilized zirconia thin film was formed on a Ni-Cr alloy tape having a thickness of 0.1 mm and a width of 5 mm, and a thin film of silver was formed thereon to a thickness of 0.3 μm. What was done was used.

On the base material on which the silver thin film was formed,
As shown in FIG. 8, a Y ₁ Ba ₂ Cu ₃ O _x thin film was formed by an excimer laser ablation method. As shown in the figure, the base material 61 having the silver thin film 60 is 1 m from the tip of the mask 62 in the region exposed to the environment for forming the thin film.
The area up to m (indicated by F in the figure) has a temperature of 700
Hold at ° C. On the other hand, a temperature gradient of 30 ° C./mm was set from 1 mm from the tip of the mask 62. In such a temperature environment, the silver thin film forms a solid-liquid boundary as described above, and as shown in FIG. 4, in the boundary region between the portion of the substrate covered with the mask and the portion exposed to the thin film forming environment. It had a staircase shape.

As in the second embodiment, Y is used as the target 64.
An excimer laser 65 is used as a target 64 by using a system sintered body.
To generate a plume 66 and deposit the chemical species in the plume 66 on the base material 61. Base material 6
The moving speed of No. 1 is set to 5 mm / min, and the film forming speed is set to 0.
It was set to 41 μm / min.

Y ₁ Ba ₂ Cu thus formed
_{In the 3} O _X film, the a-axis and the b-axis start to align in the in-plane direction of the substrate 3.5 cm from the tape tip, and then 2 m
It was confirmed that the tilt angle was within 4 ° over the length of.

Example 12 Similar to Example 8, first, a thin film of magnesium oxide was formed on a Ni—Cr alloy tape (thickness 0.1 mm, width 5 mm). Then, a silver thin film having a thickness of 0.3 μm was formed on the alloy tape formed with magnesium oxide in the same manner as in Example 11.

Next, in the same process as in Example 11, a thin film of Bi ₂ Sr ₂ Ca ₂ Cu ₃ O _x was deposited on the magnesium oxide thin film formed on the base material by the excimer laser ablation method in the process using a mask. It was The formed Bi ₂ Sr ₂ Ca ₂ Cu ₃ O _x thin film begins to have the a and b axes aligned within the surface of the substrate 4 cm from the tip of the tape, and its inclination angle is 5 ° over a length of 2 m.
It was within.

Example 13 Magnesium oxide sintered substrate (size 50 × 50 × 0.
5 mm), as shown in FIG. 9, by moving from below the mask 72 of the substrate 71 in the direction of the arrow,
A thin film of Y ₁ Ba ₂ Cu ₃ O _x was formed. When forming the thin film, a silver film having a thickness of 0.5 μm was previously formed on the substrate. The temperature distribution and the position of the mask with respect to the temperature distribution were set in the same manner as in Example 11. Example 1
Under the same film forming conditions and moving conditions as in _{No. 1, a} Y ₁ Ba ₂ Cu ₃ O _x thin film was formed by the excimer laser ablation method. The obtained thin film has the a and b axes aligned in the plane of the substrate over the entire surface, and the tilt angle is 3 °.
It was within.

Example 14 As shown in FIG. 10, a Ni--Cr alloy (thickness 0.1 m
A mask 82, to which a pipe 85 is connected and a slit 82a is formed at the tip, is provided on a base material 81 having a width of 10 mm). The inside of the mask 82 is hollow, and the gas supplied from the pipe 85 is ejected from the slit 82a. The height of the slit is 0.
The width was 2 mm and the width was 10 mm, which is the same as that of the tape-shaped substrate.

A yttria-stabilized zirconia thin film was deposited by the vacuum evaporation method while continuously moving the substrate in the same manner as in the above-mentioned examples using the mask having the slits. In the film formation, oxygen gas was flown from the slit 82a at a flow rate of 2 cc / min in the same direction as the moving direction of the substrate. The gas pressure in the film forming chamber was set to 4 mTorr. Furthermore, the substrate temperature is set to 780 ° C. and 4
Film formation was performed at a speed of 0.05 μm / min while moving the substrate in the direction of the arrow shown in FIG. 10 at a speed of mm / min.

As a result of forming the thin film as described above, the total length of 1.8 m from the point 2.8 cm from the tip of the tape.
(001) orientation (perpendicular to the tape surface)
Moreover, a yttria-stabilized zirconia thin film having a (110) orientation in the gas flow direction on the tape was obtained. It can be said that the yttria-stabilized zirconia thin film axially oriented in this way is a single crystal thin film.

Example 15 Using the same tape-shaped substrate as in Example 14, a non-oriented yttria-stabilized zirconia thin film was preformed on the substrate over a length of 1.5 m without using a mask. Next, on the thin film thus formed, Y ₁ Ba ₂ Cu ₃ O _x
Was formed as shown in FIG. In forming a thin film, the substrate temperature is 700 ° C., the flow rate of oxygen flowing from the slit is 20 sccm, and the gas pressure in the film forming chamber is 150 m.
It was set to Torr. Also, the tape-shaped base material is 2.5
The film was formed by excimer laser ablation at a rate of cm / min.

Y ₁ Ba ₂ Cu ₃ formed under the above conditions
O _X thin film from the tape tip to 25mm showed c-axis orientation was no orientation with respect to a and b axes in the tape plane direction. However, from 25 mm to 1.
A thin film was obtained in which the a and b axes were aligned in the direction of the gas flowed in a specific direction over the entire length of 475 m, and the inclination angle was within 3 ° over the entire length.

Example 16 In the same manner as in Example 14, a thin film of magnesium oxide was formed on the Ni alloy tape. At this time, a magnesium oxide thin film having a (001) orientation (perpendicular to the tape surface) and a (100) orientation in the gas flow direction was obtained over a total length of 1.8 m from 2.8 cm from the tip of the tape.

Example 17 Using the same tape-shaped substrate as in Example 14, first, a non-oriented magnesium oxide thin film was formed thereon by a usual vacuum vapor deposition method.

Then, as shown in FIG. 10, the substrate temperature was 720 ° C., the oxygen flow rate was 30 sccm, and the gas pressure was 110 mT.
under the condition of orr, Bi ₂ Sr ₂ Ca ₂ Cu was formed on the magnesium oxide thin film by the excimer laser ablation method.
₃ O _X thin film was formed. In thin film formation, the tape moving speed was set to 1.8 cm / min and the film forming speed was set to 1.1 μm / min.

In the thin film formed as described above, the portion up to 3.2 cm from the tape tip showed c-axis orientation (perpendicular to the substrate surface), but orientation in the tape surface direction (a and b axes). Was random. However, the length is 1.2 cm from the tip of the tape 3.2 cm.
The film formed in the part extending over m is a
The b-axis and the b-axis were oriented in the same direction as the gas flow direction, and the tilt angle was constant within 4 °.

Example 18 Using a 50 × 50 mm polycrystalline magnesium oxide sintered body as a substrate and covering the substrate with a mask having a slit width of a gas nozzle of 50 mm, Y _{1 was formed} by a vacuum deposition method.
A Ba ₂ Cu ₃ O _x thin film was formed. The thin film is formed at a substrate temperature of 700 ° C., an oxygen gas flow rate of 10 sccm and a gas pressure of 10
It was carried out under the conditions of mTorr, film forming speed of 0.05 μm / min, and substrate moving speed of 0.5 mm / min.

The film thus formed has a size of 50 × 5.
In the area of 30 × 50 mm in the area of 0 mm,
It had strong single crystallinity with the a, b and c axes aligned.

Example 19 In the present invention, in order to confirm the effect of oxygen gas flown in a specific direction from a nozzle, oxygen gas was supplied in one direction using a gas nozzle and oxygen gas was supplied without using a gas nozzle. In that case, the other conditions were the same as in Example 15, and the experiment was performed. Table 4 shows the results of the experiment conducted five times for each of the case where the oxygen gas was used in a predetermined direction using the gas nozzle and the case where the oxygen gas was supplied in the arbitrary direction without using the gas nozzle.

[0120]

[Table 4]

Comparing the results of this experiment, it was revealed that the tilt angle of the a and b axes was decreased and the single crystallinity of the obtained thin film was strengthened by flowing the oxygen gas in one direction using the gas nozzle. . Further, by flowing the oxygen gas in one direction, the critical current density can be increased by 2 to 5 times as compared with the case where the gas nozzle is not used, and further effect by the gas nozzle flow was confirmed.

When the gas nozzle is used in Table 4, the average azimuths of the a and b axes are almost the same as the direction of the gas supplied from the gas nozzle, that is, the longitudinal direction of the tape. Otherwise, the average orientation of the a and b axes and the longitudinal direction of the tape showed little correlation. Thus, in the present invention, when a gas flow in a specific direction is used, not only can a single crystalline thin film be formed, but also the crystal orientation of the single crystalline thin film can be controlled.

In the examples shown above, the substrate on which the thin film made of a superconductor having a strong single crystal property is formed can be used as it is as a superconducting wire. Polycrystalline oxide superconducting materials have the major problem of blocking the current due to their grain boundaries, but films with strong single crystallinity have larger current capacities because they have fewer grain boundaries. .

For example, in Examples 3, 4 and 9
The critical current density of the formed superconducting thin film is 77.3K.
7.8 × 10 each^FiveA / cm²1.95x
10 ⁶A / cm²3.9 x 10^FiveA / cm²And
It was In addition, the ultra-fine particles formed in Examples 11 and 12
The critical current density of the conductive thin film is 77.3K
1.70 × 10⁶A / cm², 7.5 × 10^FiveA / c
m²Met. Furthermore, in Examples 15 and 17
The critical current density of the formed superconducting thin film is 77.3K.
Each 1.28 × 10⁶A / cm², 7.9 ×
10^FiveA / cm²Met. These values are
1 to 2 orders of magnitude higher than the critical current density of the superconducting thin film
is there.

Furthermore, as shown in Examples 10, 13 and 18, according to the present invention, a single crystalline thin film can be easily formed in a region having a large area.

[0126]

As described above, according to the present invention,
It is possible to form a thin film having strong single crystallinity in a desired region on the base material without depending on the material and crystallinity of the base material. In the present invention, a single crystalline thin film can be formed on a base material that is cheaper and has a desired shape, instead of the conventionally used single crystal substrate.

From the above characteristics, the present invention provides a Y system,
It is extremely useful as a method for forming a thin film on high-temperature oxide superconductors such as Bi-based and Tl-based oxides. For example, according to the present invention, by forming a superconducting thin film having strong single crystallinity on a tape-shaped metal substrate, a superconducting wire having a high critical current density can be obtained as described above.

Further, according to the present invention, a single crystalline thin film can be easily formed in an arbitrary region on a base material, particularly in a region having a large area. Therefore, a thin film effective as a magnetic shield or a high frequency component. Can be easily obtained.

Furthermore, the present invention is effective for forming a thin film of a superconducting device utilizing Josephson coupling, for example. For example, a single crystalline thin film can be formed according to the present invention on a tape-shaped substrate or a wafer having a large area. Since the present invention is capable of forming a single crystalline thin film of a superconductor in an arbitrary region on the base material or in a region having a larger area on the base material as described above, the superconductor thin film according to the present invention. By cutting the base material on which is formed to obtain chips, a large amount of superconducting devices can be efficiently produced.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing an example of a thin film forming process according to the present invention.

FIG. 2 is a plan view showing another example of the thin film forming process according to the present invention.

FIG. 3 is a schematic view showing a process of forming a single crystalline thin film on a base material on which a metal thin film is previously formed according to the present invention.

4 is an enlarged cross-sectional view showing a state of a metal thin film formed on a base material in the process shown in FIG.

FIG. 5 is a perspective view for explaining a process of forming a single crystalline thin film while flowing a gas in a predetermined direction in the present invention.

FIG. 6 is a sectional view showing a process for forming a single crystalline thin film in Example 1 according to the present invention.

FIG. 7 is a schematic view showing a state in which a single crystal thin film is formed by laser ablation in Example 2 according to the present invention.

FIG. 8 is a schematic view showing a state in which a single crystalline thin film is formed in Example 11 according to the present invention.

FIG. 9 is a plan view showing a process for forming a single crystalline thin film in Example 13 according to the present invention.

FIG. 10 is a perspective view showing a process for forming a single crystalline thin film in Example 14 according to the present invention.

[Explanation of symbols]

1, 11, 21, 31, 41, 51, 61, 81 Base material 2, 12, 22, 32, 42, 52, 62, 72, 82
Mask 3 Gas phase 20 Metal thin film 54, 64 Target 55, 65 Laser 56, 66 Plume 60 Silver film 71 Substrate 83a Slit 84 Oxygen gas 85 Piping

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location H01B 13/00 565 D 7244-5G H01L 39/24 ZAA B 9276-4M // H01B 12/06 ZAA 7244-5G (72) Inventor Gozo Fujino 1-3-3 Shimaya, Konohana-ku, Osaka City Sumitomo Electric Industries, Ltd. Osaka Plant (72) Inventor Shigeru Okuda 1-3-3 Shimaya, Konohana-ku, Osaka Sumitomo Electric Ki Kogyo Co., Ltd. Osaka Works (72) Inventor Tsukushi Hara 2-4-1 Nishitsujigaoka, Chofu-shi, Tokyo Tokyo Electric Power Co., Inc. Technical Research Institute (72) Hideo Ishii 2-4-1 Nishitsujigaoka, Chofu-shi, Tokyo No. TEPCO Technical Research Institute

Claims (5)

[Claims] 1. A method for forming from a vapor phase a thin film mainly composed of crystals having a specific orientation in continuous regions on a base material, wherein chemical species in the vapor phase are transferred to the base material. A mask capable of preventing adhesion is provided, and by moving the base material relative to the mask, a portion covered by the mask in a continuous region of the base material to be crystal-grown is a crystal. A method for forming a single crystal thin film, which is characterized in that the single crystal thin film is continuously sent to an environment for growth. 2. A substrate on which a metal thin film that can be evaporated in the environment for forming the single crystalline thin film is formed in advance is used, and the portion of the substrate covered with the mask and the environment for crystal growth are exposed. The method for forming a single crystalline thin film according to claim 1, wherein a temperature gradient is provided so that the metal thin film on the base material forms a solid-liquid boundary in a boundary region with a portion to be formed. 3. The base material is applied to a portion of the base material where the mask is uncovered and is sent to an environment for crystal growth by flowing a gas in a direction in which the base material is relatively moved. 2. The method for forming a single crystalline thin film according to claim 1, wherein a gas flow in the same direction as the relative moving direction of is applied. 4. The method for forming a single crystalline thin film according to claim 1, wherein the single crystalline thin film is formed of an oxide superconducting material. 5. A method for forming a thin film mainly composed of crystals having a specific orientation in a continuous region on a base material in a vapor phase by using a laser ablation method, the method comprising: When moving relative to the mask, in the continuous region of the base material on which the crystal is to be grown, the boundary region between the part covered by the mask and the part exposed to the environment for crystal growth is The method for forming a single crystalline thin film according to claim 1, wherein the single crystalline thin film is sent to the environment for crystal growth at a moving speed of 1 cm / min or more.