JP2014154355A - Oxide film formation method and cvd apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxide film formation method and a CVD apparatus which can suppress warping of a metal substrate simply.SOLUTION: An oxide film formation method is for forming a superconducting thin film 53 to be formed on a tape-like substrate 50 and comprises forming the superconducting thin film 53 on the surface 50A of the tape-like substrate 50, in a condition that the tape-like substrate 50 is bent in such a way that the nearly central part 50B, in the width direction, of the surface 50A side of the tape-like substrate 50 is curved more concavely than both side edge parts 50C and 50C, while heating the tape-like substrate 50.

Description

  The present invention relates to an oxide film forming method for forming an oxide thin film on the surface of a tape-shaped metal substrate, and a CVD apparatus.

In general, an oxide superconducting wire in which an intermediate layer or a superconducting layer as an oxide thin film is formed on the surface (at least one side) of a long metal substrate formed in a tape shape is known. This type of oxide superconducting wire is expected to be applied to power devices such as cables, coils, and magnets.
In general, an oxide superconducting wire is formed by forming an oriented ceramic layer as an intermediate layer on the surface of a metal substrate to form a metal substrate (hereinafter referred to as a tape-shaped substrate). It is obtained by sequentially laminating a layer and a stabilization layer.
In this type of oxide superconducting wire, the material used to form the oriented ceramic layer, which is an intermediate layer, is a ceramic such as CeO ₂ or yttria-stabilized zirconia (YSZ). An oxide intermediate layer (both oriented intermediate layer) is formed on the metal substrate by performing film formation at a high temperature (600 ° C. to 800 ° C.) in consideration of adhesion coefficient and crystallinity with the metal substrate, with a much smaller expansion coefficient. Say). On the oxide intermediate layer, for example, a thin film of yttrium-based oxide superconductor (YBCO) represented by the chemical formula YBa ₂ Cu ₃ O _7-y is formed at a high temperature (800 ° C. to 900 ° C.). .

By the way, when the oxide intermediate layer and the oxide superconducting layer as described above are formed on a metal substrate, since the film is formed under a high temperature condition, a large compressive internal stress is applied during the film formation, and after air cooling, a tape shape is formed. There was a problem that the base material was warped with the oxide intermediate layer having a convex surface, and the oxide intermediate layer easily peeled off from the metal substrate after the film formation. As a result, the yield of the manufacturing process of the oxide superconducting conductor deteriorates and the workability of the obtained oxide superconducting conductor is adversely affected.
In order to solve the above-described problem, conventionally, a technique for preventing warpage of a tape-like base material by forming an alignment intermediate layer on both surfaces of a metal substrate (see, for example, Patent Document 1), A technique (for example, see Patent Document 2) that relaxes the compressive stress of the alignment intermediate layer and prevents the warp of the tape-like substrate by forming a thin film having a tensile stress between the alignment intermediate layers is proposed. .

Japanese Patent Laid-Open No. 9-120719

JP 2007-179804 A

However, the conventional technique requires forming an alignment intermediate layer on both surfaces of the metal substrate, or forming a thin film having tensile stress between the metal substrate and the alignment intermediate layer. The film formation of the oxide intermediate layer or oxide superconducting layer requires extra time and manufacturing cost, and there is a problem that it is difficult to put into practical use.
An object of the present invention is to provide an oxide film forming method and a CVD apparatus that can solve the above-described problems of the conventional techniques and can easily suppress the warpage of a metal substrate.

  In order to solve the above problems, the present invention provides an oxide film forming method for forming an oxide film on a tape-shaped metal substrate, wherein the metal substrate is heated and the metal substrate is formed on the metal substrate. The oxide film is formed in a state curved in the width direction.

  In this configuration, an oxide film may be formed on the surface of the metal substrate in a curved state so that a substantially central portion in the width direction is recessed from both side edge portions. Further, the oxide film may be an oxide intermediate layer provided on the metal substrate and for forming superconductor crystal grains.

  The oxide film may be an oxide superconducting layer formed on the metal substrate via an oxide intermediate layer. In addition, on the susceptor that supports the metal substrate, the both side edges of the metal substrate are supported so as to be separated from the susceptor, thereby moving the metal substrate in the width direction of the metal substrate. It may be curved.

  The present invention further includes a reaction chamber having a source gas ejection portion for ejecting a source gas and a susceptor that supports the tape-shaped substrate, and the source gas is placed on the surface of the tape-shaped substrate in the reaction chamber. A CVD apparatus for forming an oxide superconducting thin film on the surface of the tape-shaped substrate by supplying and chemically reacting, wherein the reaction chamber includes a heating means for heating the tape-shaped substrate, and the susceptor Is provided with a support portion that supports the tape-shaped substrate in a state where the substantially central portion in the width direction on the surface side of the tape-shaped substrate is curved so as to be recessed from both side edge portions.

  According to the present invention, the metal substrate is heated and the oxide film is formed in a state in which the metal substrate is curved in the width direction of the metal substrate. Therefore, warpage of the metal substrate that occurs after cooling can be easily suppressed, It can suppress that an oxide film peels from a metal substrate.

It is a figure which shows schematic structure of the CVD apparatus of this embodiment. It is a sectional side view which shows the shape of a susceptor. It is a figure which shows the procedure of film-forming, (A) is a cross-sectional schematic diagram of the tape-shaped base material which shows the state which curved the tape-shaped base material, (B) is superconductivity on the surface of a tape-shaped base material. It is a cross-sectional schematic diagram which shows the state which formed the thin film, (C) is a cross-sectional schematic diagram which shows the superconducting wire after cooling. It is a schematic block diagram in the reaction chamber of the CVD apparatus concerning another embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a CVD apparatus according to the present embodiment. The CVD apparatus 1 uses a chemical vapor deposition method (CVD method) to form, for example, a yttrium-based oxide superconductor represented by the chemical formula YBa ₂ Cu ₃ O _7-y on the surface of a substrate. This is a device for forming a thin film of a body (hereinafter referred to as YBCO).
The CVD apparatus 1 of the present embodiment supplies a base material transport unit 40 that winds and runs a superconducting base material (hereinafter referred to as a tape-like base material 50) formed in a long tape shape, and a material for the superconducting thin film. Reaction for forming a superconducting thin film on the surface of the tape-like base material 50, the raw material solution supply unit 30, the vaporizer 20 for vaporizing the raw material solution, the vaporized raw material gas, and the tape-like base material 50, respectively. The room 10 is provided.

The raw material solution supply unit 30 is a thin film raw material solution formed on the surface of the tape-shaped substrate 50 (for example, YBCO raw material Y, Ba, Cu diketone metal complexes each in an appropriate amount of tetrahydrofuran (THF). ) Are mixed in a predetermined amount and supplied to the vaporizer 20.
The vaporizer 20 sprays the raw material solution supplied from the raw material solution supply unit 30 together with Ar as a carrier gas, and then heats and vaporizes the raw material solution. Thereafter, the vaporized source gas is mixed with O ₂ and supplied to the reaction chamber 10.

The substrate transport unit 40 is configured to be able to reciprocate the tape-shaped substrate 50, and transports the tape-shaped substrate 50 in the reaction chamber 10 at a predetermined speed (1 to 100 m / h). In the present embodiment, the tape-shaped substrate 50 is reciprocally conveyed into the reaction chamber 10 to which the raw material gas is supplied, whereby a predetermined film thickness (for example, 0.5 μm to 3 μm) is formed on the surface of the tape-shaped substrate 50. A superconducting thin film (superconducting layer) as an oxide film can be efficiently formed. In addition, the tape-like base material 50 on which the superconducting thin film is formed is then formed with a stabilization layer on the superconducting thin film by a sputtering apparatus (not shown) to produce a superconducting wire.
The tape-like base material 50 has a tape shape with a width of about 10 mm, and for example, a tape-like base material having an intermediate layer formed on one surface of a metal substrate having a thickness of 0.1 mm is used. Specifically, the tape-like substrate 50 is formed on a non-oriented metal substrate by a sputtering apparatus using an ion beam assist called an IBAD (Ion Beam Assisted Deposition) method using a low-magnetic non-oriented metal substrate. A layer or multilayer biaxially oriented intermediate layer is formed.
The intermediate layer is an oriented intermediate layer for forming a film of biaxially oriented crystal grains of a superconductor. Examples of a material for forming the oriented intermediate layer include CeO ₂ and yttria stabilized zirconia (YSZ). Ceramics such as) can be used.

  The reaction chamber 10 forms a film on the surface of the tape-shaped substrate 50 by spraying the raw material gas supplied from the vaporizer 20 onto the surface of the tape-shaped substrate 50 running inside. As shown in FIG. 1, the reaction chamber 10 includes a susceptor 13 made of metal (for example, stainless steel) that supports the tape-like substrate 50 and is heated by heat transfer, and a heater (heating means) 15 that heats the susceptor 13. And. That is, the CVD apparatus 1 is a cold wall (internal heat) type CVD apparatus.

  The reaction chamber 10 has a horizontally long rectangular parallelepiped shape, and the bottom wall 17 of the reaction chamber 10 is provided with a susceptor 13 that extends in the traveling direction of the tape-shaped substrate 50. The susceptor 13 is a heat conduction plate that heats the traveling tape-like substrate 50, and is a heater disposed on the lower surface of the susceptor 13 so as to keep the surface of the tape-like substrate 50 at an appropriate temperature in the reaction chamber 10. 15 is heated to a predetermined temperature (for example, 700 to 800 ° C.). In the tape-like substrate 50, a running region of the tape-like substrate 50 is formed at a substantially central portion in the width direction of the susceptor 13 (a direction orthogonal to the running direction of the tape-like substrate 50).

  On the upper wall 16 of the reaction chamber 10, a raw material gas ejection portion 21 connected to the vaporizer 20 is disposed. The source gas ejection part 21 has a rectangular source gas ejection port 21 a formed substantially at the center in the longitudinal direction of the upper wall 16 of the reaction chamber 10 (the traveling direction of the tape-shaped substrate 50). A mesh plate having a large number of pores (for example, φ1.5 mm) is disposed at the raw material gas outlet 21a, and the raw material gas and the carrier gas are ejected from the fine pores of the mesh plate at a predetermined ejection speed. The When a superconducting thin film is formed on the tape-shaped substrate 50, the jetting speed of the source gas is set to 10 m / s or more.

Further, on the upper wall 16 of the reaction chamber 10, rectangular shielding plates 12, 12 having substantially the same width as the susceptor 13 are suspended from both ends in the longitudinal direction of the source gas outlet 21 a. The shielding plate 12 is made of a material (for example, SUS) that has heat resistance with respect to the film forming temperature for forming the superconductor layer and does not react with the source gas. Further, the shielding plate 12 is disposed at a predetermined distance from the upper surface of the susceptor 13 (the traveling surface of the tape-shaped substrate 50) so that the tape-shaped substrate 50 can travel.
A superconductor layer is formed on the tape-shaped substrate 50 in a region (film formation region) sandwiched between the two shielding plates 12 and 12. That is, the shielding plates 12 and 12 suppress the diffusion of the raw material gas in the longitudinal direction so that a high-quality superconductor layer is formed in the film formation region.

  Note that a notch portion may be formed in a tunnel shape at the lower end portion of the shielding plate 12 so that the tape-shaped substrate 50 passes through the notch portion. Further, a shielding gas (for example, Ar) is jetted from the lower end surface of the shielding plate 12 or downward along the shielding plate 12 to form a gas curtain at the boundary between the film formation region and the non-film formation region. May be.

  On the bottom wall 17 of the reaction chamber 10, exhaust ports (not shown) having a length corresponding to the film formation region are formed on both sides in the width direction of the susceptor 13, and unreacted source gas and carrier gas are passed through the exhaust ports. Etc. can be exhausted to the outside of the reaction chamber 10.

By the way, the superconducting thin film is formed on an oriented ceramic layer as an intermediate layer under high temperature conditions. Since the thermal expansion coefficient of the intermediate layer is much smaller than that of the metal substrate, after forming the superconducting thin film, during the air cooling (cooling), due to the difference in thermal expansion coefficient between the intermediate layer and the metal substrate, the tape-like There was a problem that the base material 50 was warped with the superconducting thin film formed in a convex surface, and the intermediate layer and the superconducting thin film were easily separated from the metal substrate.
For this reason, in this invention, the CVD apparatus 1 has the structure which prevents the curvature of the tape-shaped base material 50 after air cooling (cooling), and suppresses peeling of an intermediate | middle layer and a superconducting thin film from a metal substrate.

Specifically, as shown in FIG. 2, the susceptor 13 is formed with a groove portion (support portion) 31 extending in the running direction of the tape-like base material 50 at a substantially central portion in the width direction. The groove 31 is formed to be curved so that the substantially central portion 31A in the width direction is recessed lower than the side edge portions 31B and 31B. For example, when the width W of the tape-like substrate 50 is 10 mm, the radius of curvature R of the groove 31 is set to 10 times the width W, that is, about 100 mm at the maximum.
The susceptor 13 includes base material restricting portions 32 and 32 that extend inward from the side edge portions 31 </ b> B and 31 </ b> B of the groove portion 31 and restrict the lifting of both side edge portions of the tape-like base material 50. Of course, the base material restricting portion 32 may be formed uniformly from one end to the other end of the groove portion 31 or may be formed at a predetermined interval.
Furthermore, in this embodiment, as shown in FIG. 1, the reaction chamber 10 includes rollers 33 and 33 disposed in the groove portion 31 outside the shielding plates 12 and 12. The rollers 33 and 33 are rotatably supported by support shafts 34 and 34 suspended from the upper wall 16 of the reaction chamber 10, and cooperate with the groove portion 31 to adjust the tape-like substrate 50 to the shape of the groove portion 31. To bend.

Next, a film forming procedure will be described.
First, the tape-like base material 50 is disposed in the groove portion 31 of the susceptor 13, and the base material transport unit 40 is operated so that the tape-like base material 50 travels on the groove portion 31. In this case, since the rollers 33 are disposed in the groove portion 31, the tape-like substrate 50 is formed in the region between the rollers 33 and 33 including the film formation region as shown in FIG. The film-formation surface (surface: surface of the intermediate layer 52 formed on the metal substrate 51) of the tape-like substrate 50 is curved so that the substantially central portion 50B in the width direction on the 50A side is recessed from both side edges 50C and 50C. The
While the tape-like base material 50 is curved, the heater 15 disposed on the lower surface of the susceptor 13 is operated to heat the tape-like base material 50 that travels in the groove portion 31 of the susceptor 13 and the raw material gas outlet The source gas is jetted toward the surface 50A of the tape-like substrate 50 through 21a. Thereby, when the tape-like base material 50 passes through the film formation region, the raw material gas is supplied to the surface 50A of the tape-like base material 50, and as shown in FIG. 3B, on the curved surface 50A. A superconducting thin film 53 is formed.

  Subsequently, the tape-like base material 50 on which the superconducting thin film 53 is formed is allowed to cool in the air. In this case, since the superconducting thin film 53 is formed in a state where the tape-like base material 50 is curved, the tape-like base material 50 is determined from the difference in thermal expansion coefficient between the intermediate layer 52 and the metal substrate 51 during cooling. Even if stress is generated so that the film-forming surface side of the superconducting thin film 53 is convex, warping of the tape-like substrate 50 that occurs after cooling can be easily suppressed as shown in FIG. The intermediate layer 52 and the superconducting thin film 53 can be prevented from peeling from the metal substrate 51.

Next, another embodiment will be described.
FIG. 4 is a schematic configuration diagram illustrating a reaction chamber of a CVD apparatus according to another embodiment.
The CVD apparatus of this embodiment is a so-called hot wall (external heat) type CVD apparatus, and is disposed outside the quartz tube 70 as a reaction chamber and the quartz tube 70, and heats the space in the quartz tube 70. And a heater (heating means) 71. When the heater 71 is energized to raise the temperature of the quartz tube 70, the tape-like substrate 50 supported by a susceptor 74 described later is heated to a desired temperature.
Although not shown, the CVD apparatus includes a base material transport unit that winds and runs the tape-shaped base material 50, a raw material solution supply unit that supplies the raw material of the superconducting thin film, and a vaporizer that vaporizes the raw material solution. I have.
On the upper wall of the quartz tube 70, a raw material gas ejection part 72 connected to the vaporizer is disposed, and the raw material gas and the carrier gas are ejected through the ejection port of the raw material gas ejection part 72.

A susceptor 74 for supporting the tape-like substrate 50 is provided inside the quartz tube 70. The susceptor 74 is disposed on both sides of the plate-shaped susceptor main body 75 extending in the traveling direction of the tape-shaped substrate 50 and the width direction of the susceptor main body 75 (direction orthogonal to the traveling direction of the tape-shaped substrate 50). And support pieces (support portions) 76 and 76 for supporting the tape-like substrate 50 so as to be able to travel.
Holding grooves 76B and 76B for holding the side portions of the tape-shaped substrate 50 are formed on the opposing surfaces 76A and 76A of the support pieces 76 and 76, respectively. The holding groove 76B is formed obliquely downward toward the susceptor body 75, and supports the side edges 50C so as to separate the widthwise side edges 50C of the tape-like substrate 50 from the susceptor body 75. Thereby, the tape-shaped base material 50 is supported by the susceptor 74 in a state where the substantially central portion 50B in the width direction on the surface 50A side is curved so as to be recessed from both side edge portions 50C and 50C. For this reason, in a state where the tape-like substrate 50 is curved, a warp of the tape-like substrate 50 generated after cooling can be easily suppressed by forming a superconducting thin film on the surface 50A of the tape-like substrate 50. It is possible to suppress the peeling of the intermediate layer and the superconducting thin film from the metal substrate.

  As described above, according to the present embodiment, the oxide film forming method for forming the superconducting thin film 53 to be formed on the tape-like base material 50, the tape-like base material 50 being heated and the tape The superconducting thin film 53 is formed on the surface 50A in a state where the substantially base portion 50B in the width direction on the surface 50A side of the tape-like substrate 50 is curved so as to be recessed from both side edge portions 50C and 50C. Further, the warpage of the tape-like substrate 50 that occurs after cooling can be easily suppressed, and the intermediate layer 52 and the superconducting thin film 53 can be prevented from peeling from the metal substrate 51 constituting the tape-like substrate 50.

  Further, according to the present embodiment, both side edge portions 50C of the tape-like base material 50 are separated from the susceptor body 75 on the susceptor 74 supporting the tape-like base material 50 in the width direction. , 50C is supported, the tape-like substrate 50 is bent in the width direction of the tape-like substrate 50, so that the tape-like substrate 50 can be easily bent.

  In addition, according to the present embodiment, the reaction chamber 10 including the source gas ejection portion 21 that ejects the source gas and the susceptor 13 that supports the tape-shaped substrate is provided, and the tape-shaped substrate 50 is provided in the reaction chamber 10. A CVD apparatus for forming a superconducting thin film 53 on the surface 50A of the tape-like substrate 50 by supplying a raw material gas to the surface 50A of the substrate to cause a chemical reaction. The reaction chamber 10 heats the tape-like substrate 50. The susceptor 13 is curved in such a manner that the substantially central portion 50B in the width direction on the surface 50A side of the tape-like substrate 50 is recessed from both side edge portions 50C and 50C. Since the superconducting thin film 53 can be formed on the curved surface 50A of the tape-like base material 50 with a simple configuration, the warpage of the tape-like base material 50 generated after cooling can be simplified. Inhibition can be prevented that the intermediate layer 52 and the superconducting thin film 53 from the metal substrate 51 constituting the tape-shaped substrate 50 is peeled off.

As mentioned above, although this invention was concretely demonstrated based on one Embodiment, this invention is not limited to the said embodiment, It can change in the range which does not deviate from the summary.
For example, in the present embodiment, the method of forming the superconducting thin film 53 on the surface 50A of the tape-like substrate 50 has been described. However, the present invention is not limited to this, and the superconducting thin film 53 is formed on the metal substrate 51. It can also be used when forming an oxide intermediate layer (oxide film).

DESCRIPTION OF SYMBOLS 1 CVD apparatus 10 Reaction chamber 13,74 Susceptor 15,71 Heater (heating means)
21, 72 Source gas ejection part 31 Groove part (support part)
DESCRIPTION OF SYMBOLS 50 Tape-like base material 50A Surface 50B Width direction substantially center part 50C Side edge part 51 Metal substrate 52 Intermediate layer 53 Superconducting thin film (oxide thin film)
70 Quartz tube (reaction chamber)
75 Susceptor body 76 Support piece 76B Holding groove

Claims (6)

An oxide film forming method for forming an oxide film on a tape-shaped metal substrate,
A method for forming an oxide, comprising: heating the metal substrate, and forming the oxide film in a state where the metal substrate is bent in a width direction of the metal substrate.   2. The oxide film according to claim 1, wherein the oxide film is formed on the surface of the metal substrate in a state where the substantially central portion in the width direction is curved so as to be recessed from both side edges. Membrane method.   3. The oxide film forming method according to claim 1, wherein the oxide film is an oxide intermediate layer provided on the metal substrate for forming superconductor crystal grains. 4.   4. The oxide film forming method according to claim 1, wherein the oxide film is an oxide superconducting layer formed on the metal substrate via an oxide intermediate layer.   On the susceptor supporting the metal substrate, the metal substrate is bent in the width direction of the metal substrate by supporting the both side edges so as to be separated from the susceptor. 5. The oxide film forming method according to claim 1, wherein the oxide film forming method is performed. A reaction chamber having a source gas ejection portion for ejecting source gas and a susceptor that supports the tape-shaped substrate is provided, and the source gas is supplied to the surface of the tape-shaped substrate in this reaction chamber to cause a chemical reaction. The CVD apparatus for forming an oxide superconducting thin film on the surface of the tape-shaped substrate,
The reaction chamber includes a heating unit that heats the tape-shaped substrate, and the susceptor is curved so that a substantially central portion in the width direction on the surface side of the tape-shaped substrate is recessed from both side edges. A CVD apparatus comprising a support portion for supporting the tape-like substrate.

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