JPH04331709A - Amorphous ferroelectric oxide material and its production - Google Patents

Abstract

PURPOSE:To provide a noncrystalline (amorphous) ferroelectric oxide material applicable to thin-film type capacitor elements, ferroelectric memories, electrooptical devices, etc., and a method for producing the aforementioned material. CONSTITUTION:An amorphous ferroelectric oxide material is characterized in that the above-mentioned material is composed of a ternary oxide consisting essentially of a transition metallic oxide (M2O3)-boron oxide (B2O3)-perovskite type compound (ABO3) and the aforementioned ternary oxide has an amorphous structure (M2O3 is at least one selected from the group composed of oxides of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Y, Zr, Nb, Pd, Hf, Ta, W, In and lanthanum- series elements; ABO3 is the perovskite type compound capable of exhibiting ferroelectricity, antiferroelectricity or paraelectricity).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amorphous ferroelectric oxide material that can be used to construct thin-film capacitor elements, ferroelectric memories, electro-optical devices, etc., and a method for manufacturing the same.

0002

BACKGROUND OF THE INVENTION Conventionally, inorganic ferroelectric materials such as perovskite dielectric materials exhibit their ferroelectric properties based on certain rules in crystal symmetry. Therefore, in order to make the ferroelectric property noticeable, increasing the crystallinity of the material makes the ferroelectric property noticeable. In fact, many efforts have been made to improve the crystallinity of materials having a perovskite crystal structure in connection with the above-mentioned matters, such as adjusting the firing temperature or improving the sintered density. On the other hand, in capacitors, ferroelectric memories, etc. that use ferroelectric materials, if the material is polycrystalline, the presence of grain boundaries may cause a drop in withstand voltage, and leakage current may occur along the grain boundaries. In capacitors, this causes loss, and in memory, there is a problem in that information retention is impaired. Furthermore, the presence of grain boundaries makes it difficult to miniaturize various devices, which has become a major problem as various devices that utilize the dielectric properties of materials are becoming smaller. Further, even when a dielectric material is used as an electro-optical element, the presence of crystal grain boundaries causes light scattering, which causes serious problems such as a decrease in optical signal intensity and an increase in noise in making the optical device function. To address these problems, attempts have been made to construct microdevices such as capacitors, ferroelectric memories, or electro-optical devices by constructing thin films of ferroelectric materials. In thin films,
In order to avoid the occurrence of grain boundaries, attempts have been made to fabricate single-crystal dielectric thin films and amorphous dielectric thin films. Regarding single-crystal dielectric thin films, see, for example, Nishihara, Haruna, and Suhara: Photonic Integrated Circuits (Ohmsha, 1988) 17
Page 4 describes an example in which a single crystal thin film of PLZT, which is well known as a ferroelectric material, was fabricated. According to the same book, in order to obtain a single-crystal PLZT thin film, epitaxial growth is performed on a sapphire single-crystal substrate by a sputtering film forming method. In addition, the book also describes the growth of ferroelectric LiNbO3 thin films using liquid phase epitaxial growth (LPE).
(GGG) There are examples of growth on single crystal substrates. However, both methods use expensive single crystal substrates, require strict control of various conditions for epitaxial growth, and require that the crystal axis on which the crystal grows is regulated by the orientation of the single crystal. Furthermore, if the difference between the lattice constant of the single crystal substrate and the lattice constant of the thin film becomes too large, it becomes difficult to grow the single crystal thin film, so the actual production of the thin film is not easy. Furthermore, the epitaxial growth method described above requires a high heat treatment temperature of approximately 600°C or higher to single-crystallize a thin film, so there is the problem that the surface properties of the film are impaired by the heat treatment of the film. This has been a major barrier to the development of microdevices from ferroelectric materials.

[0003]Amorphous thin films, like single crystal thin films,
Since there are no grain boundaries, it is expected that it will be put into practical use to solve the various problems that occur in the aforementioned ferroelectric polycrystalline materials. LiteratureJapanese Journal
al Applied Physics, Vol. 2
4 (1985) Supplement 24-2,
pp 404-406 and Applied Physics Volume 54 No. 6
No. (1985) pp. 568-575, attempts have been made to make PbTiO3 into an amorphous thin film by sputtering. however,
Although the sputtered thin films produced while adjusting the substrate temperature during film formation at various temperatures from 200° C. to the liquid nitrogen temperature have an amorphous structure, they do not exhibit ferroelectricity. Furthermore, it has been reported that fine crystals of Pb and PbO 2 also precipitate in the same thin film. Another problem is that the thin film does not function as a dielectric film because it becomes conductive due to the precipitation of Pb. Furthermore, in the same report, in order to convert this conductive thin film into a ferroelectric material, the thin film is heat-treated at a temperature of 600° C. or higher to obtain a PbTiO3 thin film having a perovskite crystal structure. However, the thin film obtained by this method is polycrystalline, and it is thought that the above-mentioned problems will be encountered when attempting to miniaturize various devices using ferroelectric materials. on the other hand,
The two documents mentioned above and JP-A-61-10223
In the publication, an amorphous thin film is obtained by thinning LiNbO3 material by sputtering at a substrate temperature of about 100°C. This thin film has many vacancies in the amorphous crystal lattice due to its amorphous structure, and when an electric field is applied to the light element Li adjacent to the vacancies, an electric field is created between the lattice points where Li atoms exist and the vacancies. It goes back and forth depending on the direction of application. This mechanism allows this material to have a larger relative dielectric constant than its crystalline cousin, which results in
It has been reported that ferroelectricity appears to occur in amorphous thin films containing light elements such as Li. However, PbTiO3, PbZrO3,
For typical perovskite dielectric materials such as BaTiO3, amorphous ferroelectrics have not been obtained so far.

0004

OBJECTS OF THE INVENTION The present invention provides capacitors with an amorphous structure, which have no grain boundaries or pores found in sintered bodies, and which have low loss and ferroelectric memories with high information retention. Another object of the present invention is to provide a ferroelectric oxide material that can be applied to electro-optical devices and a method for manufacturing the same.

[0005]

[Means for Solving the Problems] The present invention provides a method for producing a ternary oxide mainly composed of a transition metal oxide (M2O3)-boron oxide (B2O3)-perovskite compound (ABO3) by vacuum evaporation or sputtering. An amorphous thin film is formed on a substrate using an amorphous film forming method such as , while maintaining the substrate temperature below 300°C, and it is strengthened as it is without heat treatment. The above problem is solved by adopting a method for obtaining a dielectric oxide material. That is, the present invention provides a transition metal oxide (M2O3)-boron oxide (B2O3)-perovskite compound (ABO3).
An amorphous ferroelectric oxide material consisting of a ternary oxide whose main component is Sc, and wherein the ternary oxide has an amorphous structure.
Ti, V, Cr, Mn, Fe, Co, Ni, Y, Zr,
ABO3 is at least one selected from the group consisting of Nb, Mo, Pd, Hf, Ta, W, In, and oxides of lanthanum series elements, and ABO3 is a perovskite compound exhibiting ferroelectricity, antiferroelectricity, or paraelectricity. It is. ). Furthermore, the present invention provides a method for producing the above ternary oxide as an amorphous thin film on a substrate using a film forming method while maintaining the substrate temperature at 300°C or less, and in the same state as produced. The present invention provides a method for producing an amorphous ferroelectric oxide material, which is characterized by obtaining an oxide material.

The amorphous ferroelectric oxide material of the present invention is a transition metal oxide (M2O3)-boron oxide (B2O3
)-A ternary oxide whose main component is a perovskite type compound (ABO3). Here, M2O3 is Sc,T
i, V, Cr, Mn, Fe, Co, Ni, Y, Zr, N
b, Mo, Pd, Hf, Ta, W, In, and La,
Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, H
At least one selected from the group consisting of oxides of lanthanum series elements such as o, Er, Tm, Yb and Lu
BO3 is a perovskite compound exhibiting ferroelectricity, antiferroelectricity, or paraelectricity. The amorphous ferroelectric oxide material of the present invention is formed by forming the above-mentioned ternary oxide in the form of a thin film having an amorphous structure. FIG. 1 shows the composition range in which the thin film exhibits ferroelectricity while having an amorphous structure. The same compositional regions are α, β, γ, δ, ε in Figure 1.
, φ. Here, the straight line αβ is a straight line represented by aM2O3-(1-a)B2O3, and the straight line βγ is represented by 0.90B2O3-0.10(bM2O3
3-(1-b)ABO3), the straight line γδ is a straight line represented by cB2O3-(1-c)ABO3, and the straight line δε is 0.20(dB2O3-(1-d
)M2O3)-0.80ABO3, the straight line εφ is the straight line represented by eABO3-(1-e)M2O3, and the straight line φα is 0.90M2O3-0.1
0(fABO3-(1-f)B2O3), and for each composition line, 0.10≦a≦0.9
0 and 0.00≦b≦1.00 and 0.20≦c≦0.
90 and 0.00≦d≦1.00 and 0.20≦e≦0
．． It is a composition line defined in the range of 90 and 0.00≦f≦1.00. In the figure, ABO3 represents various perovskite dielectric materials (PbTiO3, BaTiO3
ferroelectric materials such as PbZrO3, antiferroelectric materials such as PbZrO3)
represents. In FIG. 1 and in the triangular composition diagram to be described later, the increments on the three sides represent 1 scale of 0.1 (mol ratio). As can be seen from this figure, an amorphous film cannot be formed in a region with a high concentration of perovskite dielectric material. However, by adding M2O3 or B2O3 in excess, the material becomes amorphous and exhibits ferroelectricity.

According to the method for producing an amorphous ferroelectric thin film of the present invention, the above ternary oxide is deposited as an amorphous thin film on a substrate using a film forming method while maintaining the substrate temperature at 300° C. or less. By producing the ferroelectric oxide material, the ferroelectric oxide material can be obtained in the state in which it is produced. As a film forming means, a commonly used thin film forming process such as a vacuum evaporation method or a sputtering method is used. During film formation, the substrate temperature was adjusted to the crystallization temperature of the amorphous composite oxide (500 to 60
(0°C) Hereinafter, an amorphous oxide thin film having ferroelectricity can be obtained by forming the film in an oxygen atmosphere at a substrate temperature of preferably 300°C or less. In the present invention, a thin film exhibiting ferroelectric properties can be easily obtained without epitaxial growth performed using a single crystal substrate or the like during film formation, or without heat treatment for thin film crystallization after film formation. This greatly reduces the time and effort required to produce ferroelectric thin films, and allows the production of films with very good surface properties and no grain boundaries. micro devices such as minute capacitors,
It is expected to be applied to electro-optical devices, etc.

[0008]

【Example】

Example 1 An RF magnetron sputtering device was used to prepare a thin film. A stainless steel petri dish with a diameter of 76 mm and a depth of 4 mm was placed on the cathode plate, and B2O3, Fe2O
3. A target filled with a mixed powder of PbTiO3 and PbO2 was used. Note that PbO is replaced with PbTiO to compensate for loss due to lead evaporation during sputtering.
It was added in an excess of 5 mol% relative to No. 3. B2O3,Fe
Prior to filling each powder of 2O3, PbTiO3, and PbO2 into a stainless steel petri dish, a mixture of powders of each oxide material was wet-mixed using ethanol as a solvent for 30 minutes in a paint shaker. Thereafter, the mixture was further desolventized and dried, then filled into a stainless steel petri dish and used as a sputtering target. The sputtering gas is a mixed gas of Ar:O2=7:3.
The purity of each O2 gas used was 99.995% or higher. A Si wafer with (111) orientation was used as the substrate. The Si wafer used was an n-type one with a resistivity of approximately 1 (Ωcm). A film of S with a thickness of 200±20 nm was deposited on the Si wafer by oxidation treatment in advance.
An iO2 layer is provided. The purpose of providing this layer is mainly to ensure electrical insulation during dielectric evaluation. Prior to film formation, the substrate temperature was raised to 200° C., and a process was performed to remove water mainly adsorbed on the substrate surface. Furthermore, pre-sputtering was performed for about 30 minutes before film formation to clean the target surface and stabilize the film quality and thin film composition during sputtering film formation. Before introducing the sputtering gas, the degree of vacuum is 2 x 10-7 Torr.
I have confirmed that the following has been reached. During sputter film formation,
The total gas pressure was kept constant at 25 mTorr. During sputtering, the copper anode that fixes the substrate is cooled with water.
The substrate temperature during film formation was maintained at 20-25°C. The high frequency input power was 110 W, and sputtering film formation was performed for 30 to 60 minutes. The thickness of the thin films obtained in this way varied due to the sputtering rate varying depending on the composition of the target, but each thin film had a thickness of approximately 5.
The film thickness was 00 to 1000 nm.

[0009] Through the thin film forming process as described above, B
A sputtered thin film was prepared using ternary elements of 2O3, Fe2O3, and PbTiO3. In Figure 2, No. The compositions shown in numbers 1 to 25 were prepared, and the film structure and dielectric properties of each were measured. When the obtained thin film was examined for correspondence between the target composition and the thin film composition by induced plasma emission spectrometry, it was found that the two compositions corresponded with each other with an error of about 3%. Therefore, in the following description, the composition of the target will be used as the composition of the thin film. The dielectric properties were evaluated using a Soyer-Tower circuit, which is commonly used in the same property evaluation. Using this circuit, the electric field dependence of electric flux density (D) was evaluated and the value of spontaneous polarization (Ps) was determined. In the evaluation of dielectric properties, the electrode configuration shown in Figure 3 was used, and the electrode for applying an electric field to the thin film was brought out from the oxide thin film side, so that two capacitors C were equivalently connected.
1, C2 were connected in series to prevent the Schottky characteristic that occurs at the interface between the metal electrode and Si when the metal electrode is exposed from the Si side, and to perform accurate dielectric property evaluation. As the metal electrode, an Au electrode having a thickness of approximately 100 nm and a diameter of 4 mm was formed on the surface of the thin film by sputtering.

[0010] The sputtering thin film produced by the above thin film forming method is in the as-produced state (As-de
We evaluated the structure and dielectric properties of the (posit state). First, we will discuss the results of evaluating the structure of the thin film. FIG. 4 shows the XRD diffraction results of sputter-formed films of various compositions prepared along the dotted line A in FIG. 2. No. shown in the same figure. 7, No. 10, No. 15,
No. 18 corresponds to the number in FIG. 2 and represents the composition of the thin film sample. A Cu target was used as the XRD radiation source, and a monochromator was further attached. In the XRD results shown in FIG. 4, a diffraction line corresponding to the (111) plane of Si used as a substrate is also seen superimposed on the diffraction result of the thin film. As is clear from the figure, PbT
iO3 thin film No. In No. 7, it can be seen that the thin film undergoes crystallization even in the as-deposit state. However, the composition in which B2O3 and Fe2O3 are excessive (N
o. 10, No. 15, No. 18), no X-ray diffraction lines due to crystallization of the thin film are observed, indicating that the thin film is in an amorphous state. Further, FIG. 5 shows the XRD diffraction results of sputter-formed films of various compositions prepared along the dotted line B in FIG. No. shown in the same figure.
3. No. 16, No. 22 corresponds to the number in FIG. 2 and represents the composition of the thin film sample. As is clear from Figure 5, there are no clear diffraction lines in the XRD results other than the diffraction line corresponding to the (111) plane of Si, indicating that all thin films with these compositions have an amorphous structure. is understood. Furthermore, No. shown in FIG. 1~No. As a result of XRD analysis of all 25 films, in the thin film indicated by the black circle in the same figure, there were no clear diffraction lines other than the diffraction line corresponding to the (111) plane of Si, which is shown in Figure 2. It was found that in the region surrounded by α, β, γ, δ, ε, and φ, the thin film had an amorphous structure in the state in which the thin film was produced (as-deposited state).

Next, in order to observe the microstructure of the amorphous structure, No. 1 in FIG. High-resolution TEM observation was performed on films with 15 compositions. In TEM observation, etching is performed from the surface side of the thin film and the substrate side, and the structure approximately at the midpoint in the thickness direction of the thin film is observed. According to this, no lattice image could be recognized even at a resolution of 0.3 nm. Selected area electron diffraction was performed on the thin film sample in a region approximately 200 nm in diameter, and the observed diffraction rings showed a very wide halo pattern, indicating that the thin film was highly amorphous.

Next, the dielectric characteristics will be explained. first,
FIG. 6 shows the change in the dielectric hysteresis loop on the dotted line A in FIG. On the same line, No. The thin film of No. 7 became conductive, and the dielectric properties could not be evaluated. The numbers shown on the left shoulder of the hysteresis loop in FIG. 6 correspond to the numbers showing the composition in FIG. As is clear from this result and the structural analysis results shown in FIG.
10, No. 15, No. It was found that the thin film of No. 18 exhibits ferroelectricity while having an amorphous structure. In addition, the thin film composition on the straight line A in FIG. 2 is expressed as y(
0.5Fe2O3-0.5B2O3)-(1-y)Pb
FIG. 7 shows the dependence of the saturation charge density (Ps) of the thin film on y when expressed as TiO3. The saturation charge density is determined by the electric field from the hysteresis loop of the dielectric characteristics shown in Figure 6.
The electric field dependence of the electric flux density (D) at 00 to 500 kV/cm was extrapolated to the E=0 axis, and the electric flux density at the point where it intersects with the same axis was defined as the saturated charge density. It can be seen from Figure 7 that Ps exists over a wider composition range and the thin film exhibits ferroelectricity, but on the same line, PbT
It can be seen that ferroelectricity disappears in a composition region close to iO3. We believe that the phase precipitated in this composition range is not a ferroelectric phase but a paraelectric phase. Also, Figure 2
FIG. 8 shows the composition dependence of the hysteresis loop for each composition on the straight line B at . The numbers shown on the left shoulder of the hysteresis loop in FIG. 8 correspond to the numbers showing the composition in FIG. As is clear from this, ferroelectricity is observed in the thin film for all compositions. From this hysteresis loop, the saturation charge density (Ps) was determined using the method described above. The composition change of straight line B is 0.
80(xB2O3-(1-x)Fe2O3)-0.20
It is expressed as PbTiO3. Ps for x
The dependence of is shown in FIG. As can be seen from the figure, Ps exists for all x values, indicating ferroelectricity. Furthermore, the dielectric properties and structures of all the thin films shown in FIG. 2 were evaluated using X-rays. These results are summarized in the same figure. That is, in the figure, black circles indicate the composition of a thin film that exhibits amorphous ferroelectricity, and hatched circles indicate a composition that exhibits paraelectricity while having an amorphous structure. Furthermore, the white circles are crystalline thin films, and the thin films exhibited electrical conductivity. The structure and dielectric properties of thin films of various compositions examined on the same composition diagram are summarized. As is clear from this figure, the composition of the thin film material that exhibits ferroelectricity while having an amorphous structure is widely distributed in the figure, with α, β, γ, δ, ε, The region surrounded by φ can be defined as a composition region in which ferroelectricity is exhibited while maintaining an amorphous structure. Further, for all the compositions shown in FIG. 2, Table 1 shows the correspondence between the thin film composition and the saturation charge density Ps. For thin films exhibiting ferroelectricity, it is approximately 70 (nC/c
It has been found that it has a saturation charge density of more than m2), and this charge density reaches a maximum of about 300 (nC/cm2), and is considered to have sufficient practical characteristics as a ferroelectric material.

[0013]

[Table 1]

Example 2 A thin film was manufactured using the film forming method described in Example 1, except that the substrate was replaced with a glass substrate. The glass substrate is Corning's No. 7059 was used. No. shown in FIG.
15 and no. A thin film having a composition of 20% was prepared. The thickness of the thin film formed by sputtering was approximately 200 nm. The produced thin film had an amber color. Each thin film was coated with an antireflection coating in the near-infrared region, and the light transmittance was measured. FIG. 10 shows the dependence of transmittance on light wavelength. As can be seen from this result, the amorphous ferroelectric thin film has a light transmittance of 90% or more in the near-infrared region, and it can be seen that the thin film can be applied to electro-optical elements.

Example 3 A thin film was fabricated using the same film forming method as in Example 1, using antiferroelectric PbZrO3 instead of ferroelectric PbTiO3 as the perovskite dielectric material. The composition of the produced thin film is shown in the triangular composition diagram of FIG. 1 and No.
．． 25 ~No. It is represented as a dot with numbers up to 48 added. Dielectric properties and X for As-deposited thin films
A structural analysis using lines was performed. Figure 1 summarizes the results.
Shown in 1. In the figure, black circles indicate the composition of a thin film that exhibits amorphous ferroelectricity, and hatched circles indicate the composition of a thin film that exhibits paraelectricity while having an amorphous structure. Furthermore, the white circles are crystalline thin films and indicate the composition of the thin film that exhibited conductivity. From this result, it was found that amorphous ferroelectricity was expressed in the region surrounded by α, β, γ, δ, ε, and φ in the triangular composition diagram. Here, Pb, which exhibits antiferroelectricity when used alone,
It has been found that ZrO3 material also exhibits remarkable ferroelectricity by adding an excessive amount of Fe2O3 or B2O3. Further, Table 2 shows a list of saturation charge densities for each composition shown in FIG. According to the same table, B2O3-Fe2O
In the 3-PbZrO3 amorphous ferroelectric thin film,
A maximum saturation charge density of about 400 (nC/cm2) was observed.

[0016]

[Table 2]

Example 4 A thin film was fabricated using ferroelectric BaTiO3 as a perovskite dielectric material using the same film forming method as in Example 1. The composition of the produced thin film is shown in the triangular composition diagram of FIG. 1,
No. 25 and No. 49 ~No. 71
It is expressed as a dot with the number up to. In the figure, black circles indicate the composition of a thin film that exhibits amorphous ferroelectricity, and hatched circles indicate the composition of a thin film that exhibits paraelectricity while having an amorphous structure. Furthermore, the white circles are crystalline thin films, indicating the composition of the thin film that exhibits paraelectricity. From this result, in the triangular composition diagram, α, β,
It has been found that amorphous ferroelectricity is expressed in the region surrounded by γ, δ, ε, and φ. The thin film structure was identified using the X-ray diffraction method described in Example 1. Further, Table 3 shows a list of saturation charge densities for each composition shown in FIG. In this dielectric evaluation, the maximum
(nC/cm2) was observed.

[0018]

[Table 3]

Example 5 In the M2O3-B2O3-PbTiO3 system, each thin film was prepared using the elements shown in Table 4 as M. The thin film was prepared by the method described in Example 1. Also,
The structure of the thin film was evaluated by X-ray diffraction under the same conditions as described in Example 1. Furthermore, the method for evaluating the dielectric properties of the thin film is also the same as in Example 1. However, in sputtering film formation, M is Zr, Mo, Pd, Hf, T
In the case of a and W, metal fine powder of each element was used instead of M2O3 as the target. Other Sc, Ti
, V, Cr, Mn, Co, Ni, Y, Nb, In, La
, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy,
For Ho, Er, Tm, Yb, and Lu, M2O3 type oxide materials were used as targets. Also, Ni2O3
Because it contains water of crystallization, it was heated to about 200°C to drive off the water of crystallization and become anhydrous before being used as a target. Films having compositions indicated by dots in FIG. 13 were prepared for all M elements, and the structure and dielectric properties of the films were evaluated in an as-deposited state. In the figure, black circles indicate the composition of a thin film that exhibits amorphous ferroelectricity, and hatched circles indicate the composition of a thin film that exhibits paraelectricity while having an amorphous structure. Furthermore, the white circles are crystalline thin films, indicating the composition of the thin film that has become conductive. From this result, in the triangular composition diagram, α, β
We have found that amorphous ferroelectricity is expressed in the region surrounded by , γ, δ, ε, and φ. Also, in the same composition diagram, No. Various M
The saturation charge density (Ps) measured in Table 4 is shown in Table 4. From this, it can be seen that Ps is observed in all the thin films shown in the same table, and that ferroelectricity is expressed in each thin film.

[0020]

[Table 4]

[0021]

[Effect of the invention] As described above, M2O3-B2O3-AB
By thinning O3 (ABO3 is a perovskite dielectric)-based thin film at a low substrate temperature, for example around 25°C, by RF sputtering, a highly transparent ferroelectric thin film with an amorphous structure can be created. This makes it possible to apply ferroelectricity to sensors, memories, and electro-optical devices.

[Brief explanation of drawings]

FIG. 1 is a compositional diagram for explaining the present invention.

FIG. 2 is a compositional diagram for explaining one embodiment of the present invention, as well as an explanatory diagram of dielectric properties and thin film structure.

FIG. 3 is a structural diagram of a thin film for explaining the dielectric property evaluation method of the present invention.

FIG. 4 shows an X-ray diagram for explaining one embodiment of the present invention.
This is a line diffraction pattern.

FIG. 5 is an X-ray diffraction pattern for explaining the same example.

FIG. 6 is a diagram showing the electric field dependence of dielectric characteristics for explaining the same example.

FIG. 7 is a diagram showing composition dependence of saturation charge density for explaining the same example.

FIG. 8 is a diagram showing the electric field dependence of dielectric characteristics for explaining the same example.

FIG. 9 is a diagram showing composition dependence of saturation charge density for explaining the same example.

FIG. 10 is a diagram showing wavelength-dependent characteristics of light transmittance for explaining another embodiment of the present invention.

FIG. 11 is a compositional diagram for explaining another example of the present invention, as well as an explanatory diagram of dielectric properties and thin film structure.

FIG. 12 is a compositional diagram for explaining another example of the present invention, as well as an explanatory diagram of dielectric properties and thin film structure.

FIG. 13 is a compositional diagram for explaining another example of the present invention, as well as an explanatory diagram of dielectric properties and thin film structure.

Claims (4)

[Claims] [Claim 1] Transition metal oxide (M2O3)-boron oxide (B2O3)-perovskite compound (ABO3)
An amorphous ferroelectric oxide material comprising a ternary oxide containing as a main component, the ternary oxide having an amorphous structure. (However, M2O3 is Sc
, Ti, V, Cr, Mn, Fe, Co, Ni, Y, Zr
, Nb, Mo, Pd, Hf, Ta, W, In, and oxides of lanthanum series elements, and ABO3 is a perovskite type that exhibits ferroelectricity, antiferroelectricity, or paraelectricity. It is a compound. ) [Claim 2] The ternary oxide is M2O3, B2O3, A
In the composition diagram of the three components of BO3, aM2O3-(1-
a) B2O3 and 0.90B2O3-0.10
(bM2O3-(1-b)ABO3) and cB2
O3-(1-c)ABO3 and 0.20(dB
2O3-(1-d)M2O3)-0.80ABO3 and eABO3-(1-e)M2O3 and 0
．． 90M2O3-0.10(fABO3-(1-f)B
2O3), 0.10≦
a≦0.90 and 0.00≦b≦1.00 and 0.20
≦c≦0.90 and 0.00≦d≦1.00 and 0.2
The amorphous ferroelectric oxide according to claim 1, characterized in that the amorphous ferroelectric oxide has a composition surrounded by six composition lines defined in the range of 0≦e≦0.90 and 0.00≦f≦1.00. material. 3. The amorphous ferroelectric oxide material according to claim 1, wherein the ternary oxide is formed in the form of a thin film. 4. A ternary oxide is produced as an amorphous thin film on a substrate using a film forming method while maintaining the substrate temperature at 300° C. or less, and the ferroelectric oxide is formed as it is in the produced state. 4. A method for producing an amorphous ferroelectric oxide material according to claim 3, characterized in that the material is obtained by: