JP3111220B1 - Oriented single-layer ferroelectric oxide thin film, method for producing the same, and switching element using the ferroelectric thin film - Google Patents

Abstract

Kind Code: A1 An oriented single-layer ferroelectric oxide thin film having a smooth surface and useful for producing a high-quality switching element, an industrially advantageous production method thereof, and having the smooth surface To provide a high-quality switching element in which a conductive thin film is laminated on a ferroelectric oxide thin film. An oriented single-layer ferroelectric oxide thin film is formed by forming a ferroelectric oxide thin film having a smooth surface on a single crystal substrate. A coating liquid for forming a ferroelectric oxide thin film is applied and dried on a single crystal substrate, and then a step of performing calcination is repeated a plurality of times to deposit a calcined ferroelectric oxide thin film having a predetermined thickness. After that, the calcined thin film is crystallized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferroelectric oxide thin film having a smooth surface, an industrially advantageous production method thereof, and a switching method comprising laminating a conductive thin film on the ferroelectric oxide thin film. It relates to an element.

[0002]

2. Description of the Related Art Ferroelectric oxide thin films, for example, ferroelectric lead zirconium titanate (hereinafter referred to as PZT) are formed by sputtering, laser ablation, chemical vapor deposition (CVD), sol-gel, organic Metal coating disassembly method (M
OD). Among these production methods, the one with the simplest film-forming operation and the smallest capital investment and cost is the organometallic coating decomposition method, which can be said to be an industrially superior method.

In order to obtain a ferroelectric oxide thin film, for example, a PZT thin film by this organometallic coating decomposition method, three kinds of organic metal solutions containing Pb, zirconium and titanium (coating liquids for forming a PZT thin film) are prepared. Then, these three kinds of PZT thin film forming coating liquids are mixed so as to have a desired composition ratio of the ferroelectric PZT, and coated on a substrate (a coating step). Then, the coated substrate is kept at an appropriate temperature. The organic solvent is evaporated (drying step), and the substrate is calcined at an appropriate temperature higher than the drying step (calcining step). Finally, the calcined thin film is crystallized at the same temperature or a higher temperature as the calcining step. (Crystallization step) Combine the steps, but since the thickness of the PZT thin film obtained in one coating step is limited, the above coating, drying and calcining are necessary to obtain a PZT thin film having the desired thickness. A series of steps consisting of How as essential it has been adopted.

However, this organometallic coating / decomposing method has two problems in spite of being an industrially superior method.

One of the problems is that the surface of the obtained ferroelectric thin film is not smooth and has large irregularities. That is, for example, as shown in FIG. 4, the coating liquid for forming a PZT thin film contains lead, zirconium, and titanium.
As shown in FIG. 6, the surface of the PZT thin film produced by using a series of organic metal solutions and repeating a series of steps of coating, drying, calcining, and crystallization ten times has extremely large irregularities as shown in FIG. Will be formed. By the way, as a typical application example of such a ferroelectric oxide thin film, PZT
An element (switching element) that joins a thin film and a conductive thin film and controls the conductivity of the conductive thin film by polarization generated in a ferroelectric PZT has been proposed (S. Mathews et al., SC
IENCE vol. 276 (1996) 238.). This switching element is manufactured by further laminating a conductive thin film on a ferroelectric PZT thin film under the condition of heating, and as shown in FIG. PZ
When a T thin film is used, the adhesion between the ferroelectric oxide thin film and the conductive thin film deteriorates, and the unevenness of the generated unevenness causes the current flowing through the conductive thin film to become non-uniform. If not, problems will arise.

The second is to form a ferroelectric oxide thin film having a desired film thickness, for example, at 600 ° C. each time.
This is a point that requires a crystallization step under the high temperature conditions described above. As described above, when a conventional PZT thin film is manufactured, a series of steps of coating, drying, calcining, and crystallization is performed by, for example, one step.
The operation has to be repeated zero or more times. Therefore, in the conventional method, there is a problem that a precise control system of the crystallization step and a large expenditure of energy cost are required. Therefore, improvement for such a problem has been strongly demanded.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances of the prior art, and has an oriented single-layer structure having a smooth surface and useful for producing a high-quality switching element. It is an object of the present invention to provide a dielectric oxide thin film, an industrially advantageous production method thereof, and a high-quality switching element obtained by laminating a conductive thin film on the ferroelectric oxide thin film.

[0008]

Means for Solving the Problems The present inventors have solved the above problems.
As a result of intensive examination to make
Coating liquid for ferroelectric oxide thin film formation
And then repeat the process of calcining several times.
A calcined thin film of ferroelectric oxide having a predetermined thickness in advance.
After that, the calcined thin film is subjected to one crystallization step.
By attaching, a ferroelectric oxide thin film having a smooth surface
It was found that a film was obtained, and the present invention was completed.
That is, according to the present invention, first, on a single crystal substrate
ToHaving a smooth surface consisting of irregularities at the molecular layer level,
Single layerOriented monolayer formed with ferroelectric oxide thin film
A ferroelectric oxide thin film is provided. Second, the first invention
In the above, the oriented single-layer ferroelectric oxide thin film has the general formula Pb (Zr_xTi_1-x) O₃  (Where x represents a numerical value of 0.3 ≦ x ≦ 0.7), which is a ferroelectric zirconium lead titanate.
An oriented single-layer ferroelectric oxide thin film is provided. Third,
Coating solution for forming ferroelectric oxide thin film on single crystal substrate
・ Repeating the process of drying and then calcining several times
Deposit a calcined thin film of ferroelectric oxide
After stacking, the calcined thin film is crystallized.
The oriented single-layer ferroelectric oxide thin film according to the first or second invention.
A method of making a membrane is provided. Fourth, in the third invention
Wherein the crystallization temperature is at least 600 ° C.
A method for producing an oriented single-layer ferroelectric oxide thin film is provided.
You. Fifth, the oriented single-layer ferroelectric oxide thin film has the general formula Pb (Zr_xTi_1-x) O₃  (Where x represents a numerical value of 0.3 ≦ x ≦ 0.7), which is a ferroelectric zirconium lead titanate.
Fabrication of the oriented single-layer ferroelectric oxide thin film of the third or fourth invention
A manufacturing method is provided. Sixth, any of the first to fifth issues
Conductive thin film on oriented single-layer dielectric oxide thin film
A switching element formed by stacking films is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The oriented ferroelectric oxide thin film according to the present invention is characterized in that it has a smooth surface and is a single layer. Here, “smooth surface” refers to the molecular layer level.
It is defined as a surface consisting of irregularities of depth. In addition, the term “single layer” in the present invention refers to a “predetermined by repeating a process of applying and drying a coating liquid for forming a ferroelectric oxide thin film on a single crystal substrate and then performing calcination a plurality of times. Means a thin film layer formed by depositing a calcined ferroelectric oxide thin film having a thickness and then subjecting the calcined thin film to a single crystallization step. Therefore, even if the same ferroelectric oxide thin film forming coating liquid is used, a thin film layer formed by repeating at least a plurality of crystallization steps as in the past is treated as a “multilayer” or “multilayer”, It is not included in the “single layer” of the present invention.

As a ferroelectric oxide which is an object of the present invention,
Is, for example, PbTiO₃, (Pb, La) (Ti, Zr) O₃, Bi₄Ti₃O
₁₂, SrBi₂Ta₂O₉Conventionally all known applications
The following general formula Pb (Zr_xTi_1-x) O₃  (Where x represents a numerical value of 0.3 ≦ x ≦ 0.7)
Conium lead titanate is preferably used.

In the oriented single-layer ferroelectric oxide thin film according to the present invention, a step of applying and drying a coating liquid for forming a ferroelectric oxide thin film on a single crystal substrate and then performing calcination is repeated a plurality of times. Thus, the ferroelectric oxide calcined thin film having a predetermined film thickness is deposited in advance, and then the calcined thin film is crystallized.

The substrate may be any single-crystal substrate.
Can be used, but the flat surface of the ferroelectric oxide thin film
From the viewpoint of lubricity, its crystal structure is ferroelectric oxide
It is preferable to use something similar or the same as.
For example, zirconium titanate as a ferroelectric oxide
When lead (PZT) is used, a single-crystal substrate
Single crystal SrTiO with crystal structure similar or identical to PZT
₃, Nb-doped SrTiO₃, La-doped SrTiO₃, LaAlO₃, YAl
O₃, LaGaO₃, LaSrGaO₄, LaSrAlO₄, NdGaO₃, Al₂O
₃, MgO, CeO₂, Yttrium stabilized zirconia (YS
Z), Bi₂Sr₂CuO_x, Bi₂Sr₂Ca_nCu_{n + 1}O_{2n + 6}(n
= 1,2), YBa₂Cu₃O_{7 + d}Use an oxide such as
No. In the present invention, a single crystal substrate is a ferroelectric acid.
It is sufficient that the layer in contact with the oxide has a single crystal structure.
For example, a multilayer structure with various other layers provided on its lower surface
But it doesn't matter. Examples of such a multilayer substrate include, for example,
For example, single crystal SrTiO formed on Si wafer₃, Nb
OP SrTiO₃, La-doped SrTiO₃, LaAlO₃, YAlO₃, LaG
aO₃, LaSrGaO₄, LaSrAlO₄, NdGaO₃, Al₂O₃, MgO,
 CeO₂, Yttrium stabilized zirconia (YSZ), Bi₂Sr
₂CuO_x, Bi₂Sr₂Ca_nCu_{n + 1}O_{2n + 6}(n = 1,2), YBa
₂Cu₃O_{7 + d}Thin film substrate, etc.
And a substrate on which a polycrystalline metal film is deposited.

As the coating liquid for forming a ferroelectric oxide thin film applied on a single crystal substrate, any of conventionally known metal alkoxides or metal salts of organic acids can be used, and these include alcohols, ketones and esters. And then dissolved in an organic solvent such as a fatty acid, and then subjected to a coating step. For example,
In order to produce a PZT thin film, the coating liquid applied to the single crystal substrate includes lead, zirconium, and titanium, respectively.
Solutions of three kinds of organometallic compounds are prepared, and a mixed solution of these is mixed at a predetermined composition ratio (Pb (Zr _x Ti _1-x ) O ₃ (0.3 ≦ x ≦
0.7)) and applied on a single crystal substrate.

The coating liquid for forming a ferroelectric oxide thin film is applied to a single crystal substrate. This application step is performed by a conventionally known application method such as spin coating or dipping.

The ferroelectric oxide applied on the single crystal substrate is dried by a heating means such as a hot plate to remove the organic solvent contained therein. This drying step is preferably performed at a temperature of 80 to 300 ° C.

Next, the ferroelectric oxide after the drying step is subjected to a calcining step, and when the thickness of the ferroelectric oxide has not reached a required thickness, the ferroelectric oxide has a predetermined thickness. After the above-mentioned coating step and drying step are further repeated until is obtained, the process is moved to a calcination step. Of course, if a predetermined film thickness is obtained in the first coating-drying step, it may be directly transferred to the calcining step.

A ferroelectric oxide having a required thickness is deposited on a single crystal substrate, and after drying the organic solvent, the ferroelectric oxide is calcined. This calcining step is preferably performed at 35
The temperature of the reaction furnace is maintained at a temperature selected from 0 ° C. to 500 ° C., and then oxygen or a mixed gas containing oxygen is flowed into the reaction furnace, and then the ferroelectric oxidation deposited on the single crystal substrate is performed. It is preferable to adopt a mode in which the substance is placed in a reaction furnace and heated.

When the coating and drying steps are repeated many times, the coating and drying steps are repeated three to five times, then the calcining step is performed once, and then the coating and drying steps are repeated. Thereafter, a finishing calcination step may be performed.

In the calcining step, the ferroelectric oxide calcined thin film having a predetermined thickness deposited on the single crystal substrate is then subjected to a crystallization step. In this crystallization step, the reaction furnace is preferably maintained at a temperature selected from 600 ° C. or more and 750 ° C. or less, and then oxygen or a mixed gas containing oxygen is allowed to flow into the reaction furnace and then deposited on the single crystal substrate. Preferably, the ferroelectric oxide thin film is placed in a reactor and heated.

In the present invention, contrary to conventional wisdom, a coating liquid for forming a ferroelectric oxide thin film is applied to a single crystal substrate.
The ferroelectric oxide calcined thin film having a predetermined film thickness is deposited in advance by repeating the process of drying and then calcining a plurality of times, and then the calcined thin film is subjected to one crystallization step. As a result, an oriented ferroelectric oxide single-layer thin film having a smooth surface can be obtained.

Therefore, a switching element in which a conductive thin film is laminated on such an oriented ferroelectric oxide single-layer thin film is shown in FIG.
As shown in (1), it has excellent adhesion to the substrate, allows a uniform current to flow, and has good switching characteristics.

In the present invention, such switching
To fabricate the device, the ferroelectric oxide thin film obtained above
The conductive thin film is further laminated under heated conditions.
I just need. As the conductive thin film, any conventionally known conductive thin film can be used.
Can be used, but reactivity at the interface with the ferroelectric oxide thin film
Smaller than the crystallization temperature of the ferroelectric oxide thin film, for example, 5
It is preferable to use one that can grow crystals even at a temperature of 50 ° C or less.
Is done. As such a conductive thin film, for example, Bi₂
Sr₂CuO_x, PbSr₂CuO_y, PbSr ₂CaCu₂O_z, ZnO, etc.
I can do it. Conventionally known methods for crystal growth of conductive thin films
Growth methods such as molecular beam epitaxy and laser ablation
Method, electron beam evaporation, chemical vapor deposition,
Use growth methods such as gel-gel method and organometallic coating decomposition method
Below, preferably below the crystallization temperature of the ferroelectric oxide thin film
For example, a temperature of 550 ° C. or less may be employed.

[0024]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 [Preparation of PZT thin film] According to the flowchart shown in FIG.
A ZT thin film was prepared. First, three kinds of organometallic compound solutions each containing a lead, titanium and zirconium atom were prepared (manufactured by Kojundo Chemical Co., Ltd., organic lead solution; SYM-PB05, organic titanium solution; SYM-TI05, organic zirconium solution). SY
M-ZR04). In addition, lead, titanium,
The molar concentrations of the zirconium atoms were 0.5 mol / liter, 0.5 mol / liter and 0.4 mol / liter, respectively.

Next, these solutions were mixed such that the molar ratio of lead, zirconium, and titanium was 1.1: 0.5: 0.5. However, the lead contained in the mixed solution was mixed by 10% in excess of the stoichiometric ratio as described above. This compensates for the desorption of lead during the heat treatment. Next, this mixed solution was
The solution was dropped onto a doped SrTiO ₃ (001) substrate about two or three times with a dropper, and applied onto the substrate by a spin coating method (coating step). The spin coating condition is 10 at 500 revolutions / second.
The substrate is rotated for about second, and subsequently, the substrate is rotated at 4000 revolutions / second for about 30 seconds. The raw material necessary for laminating a PZT thin film of about 40 nm was deposited by one coating process.

Next, the substrate is placed on a hot plate at 80
The organic solvent was dried by heating at 300C for 3 minutes and 250C for 10 minutes (drying step). Further, these application step and drying step were repeated four times (a total of five times).

Next, this sample was placed in a reaction furnace heated to 480 ° C., and was heated in an oxygen gas stream for 20 minutes (calcination step). Thereafter, the coating step and the drying step were repeated five times and calcined under the same conditions.

Finally, this sample was placed in a reactor heated to 650 ° C., and heated in an oxygen stream for 20 minutes (crystallization step). Through the above steps, Nb-doped SrTiO ₃ (001)
A PZT thin film having a thickness of 400 nm was successfully fabricated on the substrate.

The crystal structure of the PZT thin film obtained above was measured by X-ray diffraction (θ / 2θ scan). As a result, it was found that the PZT thin film was epitaxially grown with a relationship of PZT [001] // Nb-doped SrTiO ₃ [001]. Furthermore, according to the measurement result of X-ray diffraction (pole figure), the in-plane PZT thin film is PZT [100] // Nb-doped SrTiO ₃ [10
[0] was found to have been epitaxially grown. In addition, the surface of this thin film was cleaned with an atomic force microscope (A
FM). The result is shown in FIG. From FIG. 5, it can be seen that no protrusion-like particles are observed on the surface of the thin film and that the film is extremely smooth. The mean square roughness of the thin film calculated from the AFM observation was only 0.9 nm.

COMPARATIVE EXAMPLE 1 [Preparation of Comparative PZT Thin Film] In order to show that it is important that the crystallization step is performed only once, the conventional method shown in FIG. 4 is used instead of the flowchart shown in FIG. A PZT thin film for comparison was produced in the same manner as in Example 1 except that the crystallization step was repeated 10 times. The surface of the thin film was observed with an atomic force microscope (AFM) in the same manner as in Example 1. FIG. 6 shows the result.
From FIG. 6, it can be seen that significant irregularities are formed on the surface of the thin film. Further, the average square roughness of the thin film calculated from the AFM observation result was an extremely large value of 3.6 nm.

Example 2 [Preparation of switching element]
A switching element of the present invention was fabricated by growing a conductive thin film on a PZT thin film. First, the PZT thin film is placed in a high vacuum (1x10
⁽⁻⁸ mbar) molecular beam epitaxy apparatus. Next, the surface of the PZT thin film was irradiated with ozone gas. At this time, the degree of vacuum in the epitaxy apparatus is about 5 × 10 ⁻⁶ mbar. By setting the substrate to 550 ° C. in this state, an extremely thin Bi ₂ Sr ₂ CuO _x thin film of only 9 nm could be formed. The Bi ₂ Sr ₂ CuO _x thin film thus obtained has a resistivity of about 0.1Ω.
cm conductor. (See Fig. 1)

Next, the Bi ₂ Sr ₂ CuO _x thin film / P obtained above
Bi ₂ Sr ₂ CuO _{x with} ZT thin film / Nb-doped SrTiO ₃ substrate structure
As shown in FIG. 7, two gold electrodes were deposited on the thin film by an electron beam evaporation method. The thickness of the gold electrode is 140 nm, and these are called a source electrode and a drain electrode, respectively. As a result, a conductive Nb-doped SrTiO ₃ substrate is used as a gate electrode.
A three-terminal switching element was produced. FIG. 7 shows a schematic diagram of such a switching element. In this device, when a voltage is applied to its gate electrode, the ferroelectric PZT is polarized, and the conductivity of the Bi ₂ Sr ₂ CuO _x thin film is controlled by the polarization charge. The current is turned on and the current is turned off by the polarization of PZT.
To switch between states, the conductive thin film must be thin
Preferably. FIG. 8 shows the characteristics when voltages of −3 V and 3 V are applied to the gate electrode of this switching element. When a gate voltage of 3 V is applied, the current is in an off state where almost no current flows as shown by 801. On the other hand, when a gate voltage of -3 V is applied, a current flows as shown by 802 and the current is turned off. It is in the on state. That is, it is understood that the switching element of the present invention has good switching characteristics. This is because the PZT thin film used in Example 2 is shown in FIG.
It is considered that the very smooth and conductive Bi ₂ Sr ₂ CuO _x having a thickness of 9 nm can be laminated on the PZT because of the smoothness as shown in FIG.

Comparative Example 2 [Preparation of Comparative Switching Element]
A switching element for comparison was fabricated in the same manner as in Example 2 except that the PZT thin film was replaced with that of Comparative Example 1.
This switching element has also been reported by the present inventors. Ota et al., Proceedings of the 60th Annual Conference of the Japan Society of Applied Physics 1999, No. 1 pp.154 (1p-ZV-6)). As shown in FIG. 6, the switching element for comparison has a large unevenness on the surface of the PZT thin film, so that Bi ₂ Sr ₂ Cu
O _x thin film sufficient conductivity unless laminated between the source and drain electrodes as 22nm is not obtained. FIG. 9 shows the switching characteristics of the comparative switching element. In FIG. 9, 901
The characteristic indicated by was temporarily set to “current off state”, and the characteristic indicated by 902 was set to current on state. However, despite the “current off state”, a current of the same level as in the on state was flowing, and the switching characteristics were extremely inferior to those of the switching element described in Example 2. The reason for this is that the unevenness of the PZT thin film used in Comparative Example 2 is severe as shown in FIG.
Unless the film thickness of the Bi ₂ Sr ₂ CuO _x thin film laminated on the ZT was 22 nm, which was larger than that in Example 2, conductivity could not be obtained. It is presumed that switching became difficult due to this thick film thickness.

[0035]

According to the present invention, contrary to conventional common sense,
A process for applying and drying a coating liquid for forming a ferroelectric oxide thin film on a single crystal substrate and then performing a calcining process a plurality of times to form a calcined thin film of a predetermined thickness in advance. After that, since the calcined thin film was subjected to one crystallization step, the smoothness comprising irregularities at the molecular layer level was obtained.
A single-layer oriented ferroelectric oxide single-layer thin film having a stable surface is obtained. Therefore, a switching element in which a conductive thin film is laminated on such an oriented ferroelectric oxide single-layer thin film has excellent adhesion to a substrate and a uniform current flows as shown in FIG. Which is industrially extremely useful. Further, according to the method for producing a ferroelectric oxide single-layer thin film of the present invention , unevenness at the molecular layer level
A single-layer ferroelectric oxide thin film having a smooth surface and excellent in crystallographic properties can be easily and inexpensively formed by a simple process.

[Brief description of the drawings]

FIG. 1 is produced by the steps of Example 2 of the present invention.
FIG. 2 is a schematic view of a switching element substrate composed of an oxide single crystal / PZT ferroelectric film / conductive film.

FIG. 2 Oxide single crystal / PZ produced by conventional process
FIG. 2 is a schematic view of a switching element substrate composed of a T ferroelectric film / conductive film.

FIG. 3 is a flowchart of the production of a PZT thin film according to the first embodiment of the present invention.

FIG. 4 is a flow chart of the production of a PZT thin film according to Comparative Example 1 (conventional example).

FIG. 5 is a graph showing AFM images and undulations of a PZT thin film according to Example 1 of the present invention.

FIG. 6 is a graph showing AFM images and undulations of a PZT thin film according to Comparative Example 1 (conventional example).

FIG. 7 is a schematic diagram of a switching element according to a second embodiment of the present invention.

FIG. 8 illustrates a switching element according to a second embodiment of the present invention.
Graph showing characteristics.

FIG. 9 is a graph showing one characteristic of the switching element according to Comparative Example 2.

[Explanation of symbols]

101 Conductive thin film 102 PZT thin film 103 Oxide single crystal 201 Where current is interrupted due to unevenness of PZT 202 Arrow indicating current direction 203 Conductive thin film 204 PZT thin film 205 Oxide single crystal 501 AFM image of PZT thin film 502 1 μm length line segment 503 Line measured undulation 504 Degree of undulation measured along black line shown in 503 601 AFM image of PZT thin film 602 Line segment showing 1 μm length 603 Undulation Measured line segment 604 Degree of undulation measured along black line shown at 603 701 Constant voltage source 702 Arrow indicating direction of drain current ( _ID ) 703 Load resistance 704 Voltmeter ( _VDS ) 705 Electrode ( Drain) 706 Conductive thin film 707 PZT thin film 708 Nb-doped SrTiO ₃ single crystal substrate (conductive; gate electrode) 709 Gate voltage source (V _GS ) 710 causing polarization in PZT 710 Electrode (source) 801 Current off state (V _GS = 3V) 802 Current on state (V _GS = -3V) 901 Current off state (V _GS = 3V) 9 02 Current on state (V _GS = -3V)

──────────────────────────────────────────────────続 き Continued on the front page (56) References Kyong-Moo Lee et al. , "Effects of Heat on Treatment on Epitaxy and Surface Morphology of Pb (Zr, Ti) 03 Films on Nb. 35, No. 8, 1998 pp. 791-794 (58) Field surveyed (Int. Cl. ⁷ , DB name) C30B 1/00-35/00 CA (STN) JICST file (JOIS) REGISTRY (STN)

Claims (6)

(57) [Claims] 1. The method according to claim 1, wherein the surface of the single-crystal substrate is formed on the surface of a single crystal substrate.
An oriented single-layer ferroelectric oxide thin film formed by forming a single-layer ferroelectric oxide thin film having a smooth surface . 2. An oriented single-layer ferroelectric oxide thin film has a general formula Pb (Zr_xTi_1-x) O₃  (Where x represents a numerical value of 0.3 ≦ x ≦ 0.7), which is a ferroelectric zirconium lead titanate.
The oriented single-layer ferroelectric oxide thin film according to claim 1. 3. A process for applying and drying a coating solution for forming a ferroelectric oxide thin film on a single crystal substrate and then performing a calcining process a plurality of times to temporarily prepare a ferroelectric oxide thin film having a predetermined film thickness. 3. The method for producing an oriented single-layer ferroelectric oxide thin film according to claim 1, wherein the calcined thin film is crystallized after depositing the calcined thin film. 4. The method for producing an oriented single-layer ferroelectric oxide thin film according to claim 3, wherein the crystallization temperature is 600 ° C. or higher. 5. An oriented single-layer ferroelectric oxide thin film represented by the general formula Pb (Zr_xTi_1-x) O₃  (Where x represents a numerical value of 0.3 ≦ x ≦ 0.7), which is a ferroelectric zirconium lead titanate.
The oriented single-layer ferroelectric oxide thin film according to claim 3 or 4.
Production method. 6. A switching element obtained by laminating a conductive thin film on the oriented single-layer ferroelectric oxide thin film according to claim 1.