JPH10200059A - Ferroelectric thin film element and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively draw out the excellent ferroelectric properties of oxide ferroelectrics having a Bi-based layered bevelskite structure, such as SrBi ₂ Ta ₂ O _9, to develop devices. A ferroelectric polycrystalline thin film containing a large number of c-axis oriented components capable of improving applicability, and a ferroelectric thin film element capable of being formed with good reproducibility at a relatively low crystallization temperature and a method of manufacturing the same It is intended to provide. SOLUTION: In a ferroelectric thin-film element having a ferroelectric polycrystalline thin film 6 on a substrate 1, a template layer 5 for preferentially orienting the ferroelectric polycrystalline thin film 6 to a desired plane orientation is formed with the substrate 1 and the ferroelectric film. It is provided between the body polycrystalline thin film 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferroelectric thin film element used for a ferroelectric nonvolatile memory element, a pyroelectric infrared sensor element, a piezoelectric element, and the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Ferroelectrics have many functions such as spontaneous polarization, high dielectric constant, electro-optic effect, piezoelectric effect and pyroelectric effect, and many of them include capacitors, oscillators, optical modulators and infrared sensors. Used for device development. Conventionally,
Although bulk materials have been used for these applications, the field of application has been rapidly expanding with recent advances in thin film formation technology. For example, DRAM, MMI
By applying the invention to capacitors of various semiconductor elements such as C, miniaturization and high integration of the elements are achieved. Also, DR
A non-volatile memory utilizing spontaneous polarization characteristics has been developed by using it for a memory capacitor portion of an AM or a gate insulating film of a MOS transistor.

The development of these devices requires a ferroelectric material having excellent characteristics such as a large residual spontaneous polarization (Pr), a small coercive electric field (Ec), a low leakage current, and a high resistance to repetition of polarization reversal. is required. Furthermore, in order to reduce the operating voltage and adapt to the semiconductor microfabrication process, it is desired to realize the above characteristics with a thin film having a thickness of 200 nm or less.

[0004] Currently, the strength for the purpose of application to the dielectric nonvolatile memory or the _{like, PZT (PbZr 1-x Ti} x O 3) oxide ferroelectric material and Bi ₄ Ti ₃ O having a beginning and perovskite structure ₁₂ , SrBi ₂ Ta ₂ O ₉ , SrBi ₂ Nb
Attempts were made to reduce the thickness of oxide ferroelectric materials having a Bi-based layered perovskite structure, such as ₂ O ₉ , by various thin film forming methods such as sputtering, vapor deposition, sol-gel, MOD, and MOCVD. Have been.

[0005] Among these ferroelectric materials, SrBi ₂ Ta ₂ O ₉ has attracted attention because of its excellent polarization reversal resistance (NAT).
URE, V0L374, p627, 1995). Conventionally, SrBi ₂ Ta ₂
O ₉ is formed by the MOD method. Normal MOD
In the method, an organometallic raw material containing each constituent element of a thin film is mixed so as to have a predetermined film composition, and a raw material solution whose concentration and viscosity are adjusted is used.
Further, the step of calcination for removing organic components is repeated until a predetermined thickness is reached to form an amorphous film, and finally, crystallization by main calcination is performed.

When the crystal is grown from such an amorphous state, the orientation of each crystal grain tends to be spontaneously uniform due to the anisotropy of the growth rate, or the orientation of the underlying crystal substrate is inherited. Except for the case of epitaxial growth, a non-oriented polycrystalline thin film usually tends to be formed. In the case of a material having a strong anisotropy such as a ferroelectric crystal, its ferroelectric property exists in a specific crystal axis direction, and thus such a non-oriented film cannot sufficiently bring out the properties of the material itself. Therefore, some method of controlling the crystal orientation of the ferroelectric thin film is required to effectively bring out the material characteristics suitable for each device.

In the case of SrBi ₂ Ta ₂ O ₉ , it has been reported that the material properties of a thin film having a strong c-axis orientation are superior to those of a normal non-oriented thin film in terms of polarization reversal resistance and leak current characteristics. (International Symposium on I
ntegrated Ferroelectrics, Proceedings, 29C, 1996
Year).

In the case of SrBi ₂ Ta ₂ O ₉ , the temperature of the crystallization heat treatment is usually 800.
A high temperature of at least ℃ is required (refer to the 55th Annual Meeting of the Japan Society of Applied Physics, 20pM19, 1994). For this reason, when applied to device development, there arises a problem that sufficient device characteristics cannot be realized due to a reaction with underlying silicon or an electrode material. Therefore, it is desirable that the crystallization temperature be as low as possible.

[0009]

As described above, according to the prior art, the excellent ferroelectric properties of oxide ferroelectrics having a Bi-based layered perovskite structure, such as SrBi ₂ Ta ₂ O ₉ , can be effectively derived. And the crystallization temperature is high, so that the range of application is limited.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made of an oxide ferroelectric having a Bi-based layered bevelskite structure such as SrBi ₂ Ta ₂ O _9. Achieve a ferroelectric polycrystalline thin film containing a large number of c-axis oriented components that can effectively extract dielectric properties and enhance applicability to device development, and form it at a relatively low crystallization temperature with good reproducibility. It is an object of the present invention to provide a possible ferroelectric thin film element and a method for manufacturing the same.

[0011]

According to the present invention, there is provided a ferroelectric thin film device having a ferroelectric polycrystalline thin film on a substrate, the ferroelectric polycrystalline thin film having a desired plane orientation. Is provided between the substrate and the ferroelectric polycrystalline thin film.

Further, according to the present invention, there is provided the above ferroelectric thin film.
The device has a lower electrode on a substrate, and the lower electrode
A template layer is placed on top, and the template layer
Bi _FourTi_ThreeO₁₂And the ferroelectric polycrystalline thin film is SrB
i_Two(Ta_1-x, Nb_x)_TwoO₉(0 ≦ x ≦ 1),
The thickness of the template layer is greater than the thickness of the ferroelectric polycrystalline thin film
Is also thin.

Further, according to the present invention, in the above ferroelectric thin film element, both the template layer and the ferroelectric polycrystalline thin film are c-axis preferentially oriented.

In the present invention, the template layer is formed of Bi.
_A- axis preferential orientation composed of ₂ SiO _5, and the ferroelectric polycrystalline thin film is made of SrBi ₂ (Ta _1-x , Nb _x ) ₂ O ₉ (0 ≦ x ≦
1) and has c-axis preferential orientation.

Further, according to the present invention, in a method for manufacturing a ferroelectric thin film element for forming a ferroelectric polycrystalline thin film on a substrate, the template layer for preferentially orienting the ferroelectric polycrystalline thin film in a desired plane orientation is provided on the substrate. After forming the ferroelectric thin film on the template layer, a ferroelectric polycrystalline thin film preferentially oriented in the same plane orientation as the template layer is formed.

Further, according to the present invention, in the above-mentioned method of manufacturing a ferroelectric thin film element, a lower electrode is formed on a substrate,
After forming a c-axis preferred orientation Bi ₄ Ti ₃ O ₁₂ thin film as a template layer on the lower electrode, the Bi ₄ Ti ₃ O ₁₂
SrBi ₂ (Ta _1-x , Nb _x ) ₂ O ₉ (0 ≦ x ≦
An amorphous thin film comprising 1) is formed, and then SrBi
By subjecting the ₂ (Ta _1-x , Nb _x ) ₂ O ₉ amorphous thin film to a crystallization heat treatment, a c-axis preferentially oriented ferroelectric polycrystalline thin film is formed.

Further, according to the present invention, in the above-mentioned method for manufacturing a ferroelectric thin film element, a silicon substrate is used as a substrate, and a (100) silicon substrate is heated and held by a MOCVD method. The Bi ₂ SiO ₅ thin film of a-axis preferred orientation is formed as a template layer by supplying to the surface, and SrBi ₂ (Ta _1-x , Nb _x ) ₂ O ₉ (0 ≦ x) is formed on the Bi ₂ SiO ₅ thin film. ≦ 1), and then SrBi ₂ (T
The crystallization heat treatment is applied to the a _1-x , Nb _x ) ₂ O ₉ amorphous thin film.

Next, the operation of the present invention as described above will be described. As described above, if a base substrate (template) having an atomic arrangement similar to a desired crystal orientation state can be prepared, an orientation film can be obtained by using an epitaxial growth mechanism. Further, when a crystal growth nucleus is present in advance as in normal epitaxial growth, crystal growth at a lower temperature is possible as compared with crystal growth from a completely amorphous state. Therefore, how to achieve an effective template layer is a key to solving the above-mentioned problem.

According to the present invention, a template layer that can be used for forming a c-axis oriented SrBi ₂ Ta ₂ O ₉ thin film is formed when a lower electrode constituting a capacitor is a base or a silicon wafer itself. Is provided.

The conditions desired for such a template layer are that the template layer has a crystal structure similar to that of the intended SrBi ₂ Ta ₂ O ₉ and that the atomic arrangement is similar. Therefore, in the present invention, as described above, when c-axis-oriented SrBi ₂ Ta ₂ O ₉ is formed on a base electrode, a c-axis oriented film of Bi ₄ Ti ₃ O ₁₂ having a similar crystal structure is formed. Used as a template layer. In the case where c-axis oriented SrBi ₂ Ta ₂ O ₉ is directly formed on a silicon wafer,
An a-axis oriented film of Bi ₂ SiO ₅ is used as a template layer.

Each template layer and SrBi ₂ T
The value of the mismatch of the crystal lattice with a ₂ O ₉ is estimated as follows.

SrBi ₂ Ta ₂ O ₉ (c-plane) / Bi ₄ Ti ₃
O ₁₂ (c-plane): about 1.9% SrBi ₂ Ta ₂ O ₉ (c-plane) / Bi ₂ SiO ₅ (a-plane):
Approximately 2.4% From such a small value of lattice mismatch, it is possible to sufficiently realize a c-axis oriented film of SrBi ₂ Ta ₂ O ₉ by using these template layers. Here, the following lattice constants were used for the above estimation.

SrBi ₂ Ta ₂ O ₉ : a = 0.55306
5 nm, b = 0.553445 nm, c = 2.49833
9 nm (see Acta Cryst. B48 (1992) 418) Bi ₄ Ti ₃ O ₁₂ : a = 0.54100 nm, b = 0.5
4489 nm, c = 3.2815 nm (see JCPDS card, 35-795) Bi ₂ SiO ₅ : a = 1.5217 nm, b = 0.4747
7 nm, c = 0.5325 nm (JCPDS card, 3
In the present invention, the c-axis oriented Bi ₄ Ti ₃ O ₁₂ thin film and the a-axis oriented Bi ₂ SiO ₅ thin film can be produced by MOCVD. The substrate used in the present invention is Bi ₄
When producing a Ti ₃ O ₁₂ template layer, it is preferable to use a silicon substrate surface coated with an electrode layer such as Pt / Ti or Pt / Ta. Also, Bi ₂
When producing a SiO ₅ template layer, (100)
It is preferable to use a surface silicon substrate. Here, a circuit element such as a transistor may be incorporated on the surface of the silicon substrate.

The organometallic raw materials used in the MOCVD method include orthotribismuth Bi (o-C ₇ H ₇ ) ₃ , triphenyl bismuth Bi (C ₆ H ₅ ) ₃ , titanium isopropoxide Ti (i-OC ₇ H) ₇ ) ₄ etc. are used. These organometallic raw materials are heated and vaporized and supplied onto a heated and held substrate together with a carrier gas such as Ar. At this time, O ₂ gas is simultaneously supplied as a reaction gas. The film forming parameters include a raw material heating temperature, a carrier gas flow rate, an O ₂ gas flow rate, a film forming pressure, and a substrate temperature.

When a Bi ₄ Ti ₃ O ₁₂ thin film is formed on a Pt electrode, the substrate temperature is preferably 500 ° C. to 650 ° C., and the film forming pressure is preferably 10 Torr or less. On the other hand, when forming Bi ₂ SiO ₅ on a silicon substrate, the substrate temperature is 600 ° C.
And the film forming pressure is preferably about 5 Torr.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view showing a schematic structure of a ferroelectric thin film element according to a first embodiment of the present invention. In FIG. 1, 1 is a silicon substrate, 2 is a SiO ₂ layer, 3 is a Ti adhesive layer, 4 is a Pt electrode layer, and 5 is c
The Bi ₄ Ti ₃ O ₁₂ template layer 6 with the axis preferred orientation is a ferroelectric polycrystalline thin film of SrBi ₂ Ta ₂ O _{9 with the} c axis preferred orientation. As will be explained the basic structure of a ferroelectric thin film element in the present embodiment, in practice, the Pt electrode layer 4 and the lower electrode, the upper electrode on the SrBi ₂ Ta ₂ O ₉ ferroelectric polycrystalline thin film 6 It is used as an electronic device by forming a formed capacitor structure.

Next, the fabrication of the above-mentioned dielectric thin film element will be described. As a substrate, an SiO ₂ layer 2 having a thickness of 200 nm is formed by thermally oxidizing the surface of a silicon wafer, and then a Ti layer 3 having a thickness of 30 nm is formed.
An m-type Pt electrode layer 4 was used. Where T
The i layer 3 is used as an adhesive layer between the SiO ₂ layer 2 and the Pt electrode layer 3. Ti and Pt were formed by a normal sputtering method. In the present embodiment uses a silicon wafer to the substrate, is formed a circuit element on a semiconductor substrate and its surface, such as a GaAs substrate, an upper portion thereof is covered with an interlayer insulating layer such as SiO ₂ or SiN _X May be used.

Next, a Bi ₄ Ti ₃ O ₁₂ thin film was formed as a template layer 5 on the Pt electrode layer 4 by MOCVD as follows. Bi material as ortho-tolyl bismuth _{Bi (o-C 7 H 7} ) 3, Ti raw material as titanium isopropoxide _{Ti (i-OC 3 H 7} ) 4 was used. Bi
The raw material was heated to 160 ° C. and the Ti raw material was heated and vaporized to 50 ° C., respectively, and introduced together with Ar as a carrier gas and O _{2 as a} reaction gas into a film forming chamber, and supplied to the heated and held substrate surface. At this time, the carrier gas flow rate of the Bi raw material is 200 s.
ccm, 50 sccm for Ti raw material, and 1000 sccm for O ₂ gas. The distance between the source gas supply nozzle in the film forming chamber and the substrate is about 8 cm, and the substrate temperature is 600
C. and the film forming pressure was 5 Torr. Note that the film formation conditions used here are such that if the pressure in the film formation chamber is too high, a gas phase reaction is likely to occur, and if the distance between the nozzle and the substrate is too short, the nozzle temperature will increase, and This was set in consideration of the occurrence of the reaction.

Under the above conditions, Bi ₄ Ti ₃ O ₁₂ having a thickness of about 10 nm was obtained in a film forming time of 10 minutes. It can be seen from the X-ray diffraction pattern of FIG. 2 that the orientation is preferentially oriented along the c-axis. In FIG. 2, (006), (0
08) and (001 2) are peaks indicating the c-axis orientation of Bi ₄ Ti ₃ O ₁₂ , and (117) is (1) of Bi ₄ Ti ₃ O ₁₂
17) This is a peak indicating orientation, and Pt (111) is Pt
This is a peak due to the electrode layer 4.

Next, an SrBi ₂ Ta ₂ O ₉ thin film was formed on the Bi ₄ Ti ₃ O ₁₂ template layer 5 by the MOD method. Here, the raw material solution for coating includes tantalum ethoxide Ta (OC ₂ H ₅ ) ₅ , bismuth 2 ethylhexanate Bi (C ₇ H ₁₅ COO) ₂ , strontium 2 ethyl hexanate Sr (C ₇ H) as starting materials. _{Using 15} C00) ₂ and xylene as a solvent, they were mixed and synthesized to have a predetermined composition. Using this raw material solution, application by spin coating and drying at 250 ° C. for 5 minutes in the air are repeated three times on the Bi ₄ Ti ₃ O ₁₂ film (template layer 5) having the c-axis preferred orientation described above. Then, a heat treatment for crystallization was performed at 700 ° C. for 30 minutes in an oxygen stream. Thereby, the film thickness of 200 n
m of SrBi ₂ Ta ₂ O ₉ ferroelectric polycrystalline thin film 6 was formed. For comparison, as a comparative example, a SrBi ₂ Ta ₂ O ₉ thin film was formed on a Pt / Ti electrode without the Bi ₄ Ti ₃ O ₁₂ template layer 5 in the same process as in the present embodiment.

The X-ray diffraction patterns of these thin films obtained are shown in FIG. 3 (this embodiment) and FIG. 4 (comparative example). Bi
_In FIG. 3 (this embodiment) using the ₄ Ti ₃ O ₁₂ template layer 5, the c-axis preferential orientation of SrBi ₂ Ta ₂ O ₉ is clearly seen. On the other hand, FIG. 4 (comparative example) in which the template layer 5 is not used shows a non-oriented pattern, a low reflection intensity, and insufficient crystallization. 3 and 4, (006), (0)
08) and (0010) are peaks indicating the c-axis orientation of SrBi ₂ Ta ₂ O ₉ , and (115) is SrBi ₂ Ta ₂ O 9
₉ is a peak showing the (115) orientation of Pt (11).
1) and Pt are peaks due to the Pt electrode layer 4.

From the above results, the c-axis oriented Bi ₄ Ti ₃ O ₁₂
The insertion of the template layer 5 is extremely effective for realizing the c-axis preferential orientation of the SrBi ₂ Ta ₂ O ₉ ferroelectric polycrystalline thin film 6 and improves the crystallinity, that is, reduces the crystallization temperature. I knew it was there.

[Second Embodiment] Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a sectional view showing a schematic structure of a ferroelectric thin film element according to a second embodiment of the present invention. In FIG. 5, 11 is a silicon substrate, 15 is a Bi ₂ SiO ₅ template layer with a-axis preferred orientation, and 16 is a SrBi ₂ Ta ₂ O ₉ ferroelectric polycrystalline thin film with c-axis preferred orientation. Although the basic configuration of the ferroelectric thin film element will be described in the present embodiment, in practice, an upper electrode is formed on the SrBi ₂ Ta ₂ O ₉ ferroelectric polycrystalline thin film 16 using the silicon substrate 11 as a lower electrode. It is used as an electronic device, for example, by using a capacitor structure as described above.

Next, the fabrication of the above ferroelectric thin film element will be described. A (100) low-resistance silicon wafer was used as a substrate. HF oxide film on silicon substrate surface
After removing with an aqueous solution and washing with pure water, the substrate is set on a substrate holder in the film formation chamber, and 1 × 10 ⁻⁷ To
Evacuated to rr. Thereafter, ortho tolyl bismuth Bi (o-C ₇ H ₇ ) ₃ as a Bi raw material is heated to 160 ° C. and vaporized, and a carrier gas Ar (flow rate 200 sccm) is used.
Was supplied to the substrate surface ((100) surface) together with the reaction gas O ₂ (flow rate 400 sccm) for 20 minutes. Here, the pressure in the film forming chamber is 5 Torr, and the substrate temperature is 600 ° C.
And

The substrate surface taken out exhibited a blue interference color, and the X-ray diffraction pattern shown in FIG. 6 was obtained. This diffraction pattern shows only the reflection peak of the a ₂ orientation of Bi ₂ SiO ₅ , and from this result, the supplied Bi and O react with the substrate silicon on the silicon surface, whereby Bi ₂ SiO ₅ is converted. It seems to have been formed. This result seems to be appropriate because the magnitude of the lattice mismatch between silicon and the a-plane of Bi ₂ SiO ₅ is extremely small at −0.5%. In FIG. 6, (200), (400),
And (600) are peaks indicating the a-axis orientation of Bi ₂ SiO ₅ .

Subsequently, a SrBi ₂ Ta ₂ O ₉ thin film was formed on the a-axis oriented Bi ₂ SiO ₅ template layer 15 by the MOD method in the same manner as in the first embodiment. FIG. 7 shows an X-ray diffraction pattern of the obtained thin film. Clearly it can be seen that a strong c-axis preferred orientation of SrBi ₂ Ta ₂ 0 ₉ can be seen. In FIG. 7, (00
6), (008) and (0010) are SrBi ₂ Ta ₂ O
A peak indicating the c-axis orientation of the _9, reflecting marked with ○ mark (200) and (400) is the peak of the a-axis orientation of the Bi ₂ SiO ₅ by Bi ₂ SiO ₅ template layer 15 either.

In the first and second embodiments, SrB
Although an example of the i ₂ Ta ₂ O ₉ ferroelectric polycrystalline thin film was shown, the SrBi ₂ Nb ₂ O ₉ ferroelectric polycrystalline thin film having the same crystal structure and the mixed crystal SrBi ₂ (Ta _{1− x} Nb
_x ) O ₉ (0 ≦ x ≦ 1) yielded similar results.

[0038]

As described above, according to the present invention,
SrB expected as a material for ferroelectric nonvolatile memory
_{i 2 Ta 2 O 9, SrBi} 2 Nb 2 0 9, SrBi 2 (Ta 1-x
Nb _x ) O ₉ (0 ≦ x ≦ 1) c-axis oriented film with good reproducibility,
And it can be formed at a low temperature. From this, it becomes possible to effectively extract the excellent characteristics of the c-axis oriented film of the above-mentioned material, that is, the polarization inversion resistance and the leak current characteristic, and improve the characteristics and reliability of the device. Further, since the above-mentioned material can be formed directly on a silicon substrate, it can be applied to a device having a memory effect in a transistor itself by applying to a gate insulating film of a MOS transistor.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic structure of a ferroelectric thin film element according to a first embodiment of the present invention.

FIG. 2 is a view showing an X diffraction pattern of a Bi ₄ Ti ₃ O ₁₂ template layer of the first embodiment.

FIG. 3 is a view showing an X diffraction pattern of the SrBi ₂ Ta ₂ O ₉ ferroelectric polycrystalline thin film of the first embodiment.

FIG. 4 is a view showing an X diffraction pattern of a SrBi ₂ Ta ₂ O ₉ thin film of a comparative example.

FIG. 5 is a cross-sectional view illustrating a schematic structure of a ferroelectric thin film element according to a second embodiment.

FIG. 6 is a diagram showing an X-ray diffraction pattern of a Bi ₂ SiO ₅ template layer of a _second embodiment.

FIG. 7 is a diagram showing an X-ray diffraction pattern of a SrBi ₂ Ta ₂ O ₉ ferroelectric polycrystalline thin film according to a _second embodiment.

[Explanation of symbols]

Reference Signs List 1,11 silicon substrate 2 SiO ₂ layer 3 Ti adhesion layer 4 Pt electrode layer 5 Bi ₄ Ti ₃ O ₁₂ template layer 6,16 SrBi ₂ Ta ₂ O ₉ ferroelectric polycrystalline thin film 15 Bi ₂ SiO ₅ template layer

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/8242 H01L 27/10 651 21/8247 29/78 371 29/788 41/18 101Z 29/792 37/02 41/18

Claims (7)

[Claims] 1. A ferroelectric thin-film device having a ferroelectric polycrystalline thin film on a substrate, wherein the template layer for preferentially orienting the ferroelectric polycrystalline thin film in a desired plane orientation is formed on the substrate and the ferroelectric material. A ferroelectric thin film element provided between a polycrystalline thin film. 2. An electrode layer is provided on the substrate, the template layer is disposed on the electrode layer, the template layer is made of Bi ₄ Ti ₃ O ₁₂ and the ferroelectric polycrystalline thin film is made of S 4.
rBi ₂ (Ta _1-x , Nb _x ) ₂ O ₉ (0 ≦ x ≦ 1), wherein the thickness of the template layer is smaller than the thickness of the ferroelectric polycrystalline thin film. Item 2. The ferroelectric thin film element according to item 1. 3. The ferroelectric thin-film element according to claim 2, wherein both the template layer and the ferroelectric polycrystalline thin film are c-axis preferentially oriented. 4. The method according to claim 1, wherein the template layer is made of Bi ₂ SiO ₅ and has an a-axis preferred orientation, and the ferroelectric polycrystalline thin film is made of SrBi ₂ (Ta _1-x , Nb _x ) ₂ O ₉ (0 ≦ x ≦ 2. The ferroelectric thin film element according to claim 1, wherein the ferroelectric thin film element is composed of 1) and has c-axis preferred orientation. 5. A method of manufacturing a ferroelectric thin film element for forming a ferroelectric polycrystalline thin film on a substrate, comprising: forming a template layer on the substrate for preferentially orienting the ferroelectric polycrystalline thin film in a desired plane orientation. Forming a ferroelectric thin film on the template layer, thereby forming a ferroelectric polycrystalline thin film preferentially oriented in the same plane orientation as the template layer. Manufacturing method. 6. An electrode layer is formed on the substrate, and a Bi ₄ Ti ₃ O ₁₂ thin film having c-axis preferred orientation is formed on the electrode layer as the template layer, and then formed on the Bi ₄ Ti ₃ O ₁₂ thin film. To S
An amorphous thin film made of rBi ₂ (Ta _1-x , Nb _x ) ₂ O ₉ (0 ≦ x ≦ 1) is formed, and then the SrBi ₂ (Ta _1-x ,
8. The ferroelectric thin film element according to claim 7, wherein a ferroelectric polycrystalline thin film having c-axis preferred orientation is formed by subjecting the Nb _x ) ₂ O ₉ amorphous thin film to a crystallization heat treatment. Method. 7. A silicon substrate is used as the substrate.
By supplying a Bi organometallic raw material gas and an oxygen gas to the (100) plane of the silicon substrate heated and held by the OCVD method, a Bi ₂ SiO ₅ thin film having an a-axis preferred orientation is formed as the template layer. _An amorphous thin film made of SrBi ₂ (Ta _1-x , Nb _x ) ₂ O ₉ (0 ≦ x ≦ 1) is formed on the ₂ SiO ₅ thin film, and then the SrBi ₂ (Ta
_{1-x, Nb x) 2} O 9 ferroelectric according to claim 5, characterized in that to form a ferroelectric polycrystalline thin film of c-axis preferred orientation by applying crystallization heat treatment to an amorphous thin film A method for manufacturing a thin film element.