JPH05147935A - Amorphous ferroelectric oxide material and its production - Google Patents

Abstract

PURPOSE:To obtain a ferroelectric thin film having high transparency by forming an amorphous thin film of a ternary oxide based on the oxide of a transition metal, aluminum oxide and a pyrochlore type compd. on a substrate at a prescribed temp. CONSTITUTION:The oxide of a transition metal (M2O3), e.g. Fe2O3 is blended with aluminum oxide (Alambda2o3) and a pyrochlore type compd. (A2B2O3), e.g. Cd2 Nb2O7 or Pb.Nb,0, so as to give a compsn. within the region defined by points alpha, beta, gamma, delta, epsilon in the triangular compsn. diagram and they are wet-mixed and filled into a laboratory dish. This dish is put on the cathode plate of a film forming device such as an RF magnetron sputtering device and the mixture is used as a target. An SiO2 film of about 200nm thickness is previously formed on a substrate such as an Si wafer with (111) orientation by oxidation treatment. The device is evacuated to about <=2X10<-7> Torr and sputtering gas such as a gaseous mixture having 7:3 ratio of Ar:O2 is introduced into the device. A thin film is formed by sputtering on the substrate at <=300 deg.C, e.g. 20-25 deg.C while keeping about 25mTorr total pressure of gas.

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 capable of forming a thin film type capacitor element, a ferroelectric memory, an electro-optical device and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, in an inorganic ferroelectric material represented by a perovskite dielectric material,
The ferroelectric property is expressed based on a certain rule in crystal symmetry. In the Pyrochlore dielectric material, which is also known to exhibit ferroelectricity, the cause of the ferroelectricity is due to a certain rule in crystal symmetry. For this reason, it is important to enhance the crystallinity of the material in order to make the ferroelectricity remarkable. In fact, many efforts have been made in relation to the above-mentioned matters such as adjusting the firing temperature or improving the sintering density in order to improve the crystallinity of the material having the Pyrochlore crystal structure. On the other hand, in the case of capacitors, ferroelectric memories, etc. to which such ferroelectrics are applied, if the material is polycrystalline,
Due to the existence of the grain boundary, there is a problem that the withstand voltage is lowered and a leak current is generated along the grain boundary, which causes a loss in the capacitor and impairs the retention of information in the memory. In addition, it is difficult to miniaturize various devices due to the existence of crystal grain boundaries, which is a big problem in today's miniaturization of various devices that apply dielectric characteristics. Further, when the dielectric material is developed 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 when the optical device is made to function.
In response to these problems, a ferroelectric material composed of a thin film,
There are attempts to construct a microdevice-type capacitor, a ferroelectric memory, or an electro-optical device. In order to avoid the occurrence of grain boundaries in thin films, attempts have been made to produce single crystal dielectric thin films and amorphous dielectric thin films. In single crystal dielectric thin film, sapphire is used for the substrate to promote epitaxial growth.
A single crystal substrate such as MgO or GGG can be used properly considering the matching of the lattice constant with the thin film. Further, a method such as a sputtering method or a liquid phase epitaxial growth method (LPE method) is used for forming the film. However, in either method, an expensive single crystal substrate is used as a substrate, various conditions must be strictly controlled for epitaxial growth, and the crystal axis of crystal growth is restricted to the orientation of the single crystal. Further, 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, and thus actual thin film production is not easy. further,
With the epitaxial growth method described above,
Since a high heat treatment temperature of approximately 600 ° C. or higher is required for single crystallization of a thin film, there is also a problem that the heat treatment of the film impairs the surface property of the film. It was a big barrier.

Amorphous thin films, like single crystal thin films,
Since there is no crystal grain boundary, it is expected to be put to practical use in order to solve various problems occurring in the above-mentioned ferroelectric polycrystalline material. However, conventional Pyrochl
There is no example of producing an amorphous ferroelectric thin film by using an ore type dielectric.

[0004]

The object of the present invention is that the material according to the present invention has an amorphous structure, and as a result there is no grain boundary or pores found in a sintered body, a capacitor with low loss and a ferroelectric memory with high information retention. Or to provide a material applicable to an electro-optical device or the like.

[0005]

SUMMARY OF THE INVENTION The present invention is a transition metal oxide (M ₂ O ₃ ) -aluminum oxide (Al ₂ O ₃ )-
A ternary oxide containing a Pyrochlore-type compound (A ₂ B ₂ O ₇ ) as a main component is placed on the substrate by an amorphous film forming means such as vacuum deposition or sputtering, and the substrate temperature is set to 3
While keeping the temperature below 00 ° C., it is produced as an amorphous thin film,
The above problem is solved by adopting a method of obtaining a ferroelectric oxide material in the as-prepared state without subjecting this to heat treatment or the like. That is, the present invention, the transition metal oxide (M ₂ O ₃₎ - Aluminum oxide (Al ₂ O ₃₎ -Pyrochlore type compound (A ₂
Becomes a B ₂ O ₇₎ ternary oxide as a main component, and an amorphous ferroelectric material in which the ternary oxide is characterized by having an amorphous structure (wherein, M ₂ O ₃ is S
c, Ti, V, Cr, Mn, Fe, Co, Ni, Y, Z
At least one selected from the group consisting of oxides of r, Nb, Mo, Pd, Hf, Ta, W, In and lanthanum series elements, and A ₂ B ₂ O ₇ is Pyr which exhibits ferroelectricity.
It is an ochlore type compound. ) Is provided. Further, according to the present invention, the above ternary oxide is formed as an amorphous thin film on a substrate by using a film forming means while maintaining the substrate temperature at 300 ° C. or less, and the ferroelectric film is produced as it is. The present invention provides a method for producing an amorphous ferroelectric oxide material, which is characterized by obtaining an oxide material.

[0006] Amorphous ferroelectric oxide material of the present invention, the transition metal oxide (M ₂ O ₃₎ - Aluminum oxide (Al ₂ O ₃₎ -Pyrochlore type compound (A ₂
It consists of a ternary oxide whose main component is B ₂ O ₇ ). Here, M ₂ O ₃ is Sc, Ti, V, Cr, Mn, Fe, C
o, Ni, Y, Zr, Nb, Mo, Pd, Hf, Ta,
W, In, La, Ce, Pr, Nd, Sm, Eu,
At least one selected from the group consisting of oxides of lanthanum series elements of Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and A ₂ B ₂ O ₇ is Py showing ferroelectricity.
It is a chlorore type compound. The amorphous ferroelectric oxide material of the present invention is formed by forming the above ternary oxide in the form of an amorphous structure. FIG. 1 shows a composition showing ferroelectricity while the thin film has an amorphous structure.
The same composition region is a region surrounded by α, β, γ, δ, ε, φ in FIG. Here, the straight line αβ is aM ₂ O
₃ - (1-a) is a straight line represented by Al ₂ O _3, linear βγ is _{0.90Al 2 O 3 -0.10 (bM 2} O 3 -
(1-b) A ₂ B ₂ O ₇ ) is a straight line, the straight line γδ is a straight line represented by cAl ₂ O _3- (1-c) A ₂ B ₂ O ₇ , and the straight line δε is 0.20 (dAl ₂ O ₃ −
(1-d) M ₂ O ₃ ) −0.80 A ₂ B ₂ O ₇ is a straight line, and the straight line εφ is eA ₂ B ₂ O ₇ − (1-e).
It is a straight line represented by M ₂ O ₃ , and the straight line φα is 0.90M
_{2 O 3 -0.10 (fA 2 B} 2 O 7 - (1-f) Al 2
O ₃ ), and in each composition line 0.10 ≦ a ≦ 0.90 and 0.00 ≦ b ≦ 1.00 and 0.20 ≦ c ≦ 0.90 and 0.00 ≦ d ≦ 1.00
And 0.20 ≦ e ≦ 0.90 and 0.00 ≦ f ≦ 1.0
It is a composition line defined in the range of 0. In the figure, A ₂ B ₂ O ₇ represents various Pyrochlore-type dielectric materials (ferroelectric materials such as Cd ₂ Nb ₂ O ₇ and Pb ₂ Nb ₂ O ₇ ). In FIG. 1 and in the triangular composition diagram described later, the division of the three sides represents one scale of 0.1 (mol ratio). As can be seen from this figure, an amorphous film cannot be formed in a region where the concentration of the Pyrochlore type dielectric material is high. However, this M ₂ O ₃ or Al ₂ O
By excessively adding ₃ , 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 formed as an amorphous thin film on a substrate by using a film forming means while keeping the substrate temperature at 300 ° C. or lower. By manufacturing, the ferroelectric oxide material can be obtained as it is. As a film forming means, a generally used thin film forming process such as a vacuum vapor deposition method and a sputtering method is used. During film formation, the substrate temperature was set to the crystallization temperature (500 to 6) of the amorphous composite oxide.
By forming the film in an oxygen atmosphere at a substrate temperature of 00 ° C. or lower, preferably 300 ° C. or lower, an amorphous oxide thin film having ferroelectricity can be obtained. According to the present invention, a thin film exhibiting ferroelectric characteristics can be easily obtained without performing heat treatment for crystallizing a thin film after epitaxial growth or film formation using a single crystal substrate or the like at the time of film formation. For this reason, the time and effort required to prepare the ferroelectric thin film are greatly reduced, and a film with very good surface properties and without grain boundaries can be prepared. It is expected to be applied to micro devices such as capacitors and electro-optical devices.

[0008]

【Example】

Example 1 An RF magnetron sputtering apparatus was used to prepare a thin film, and a stainless petri dish having a diameter of 76 mm and a depth of 4 mm was placed on a cathode plate, and Al ₂ O ₃ and Fe ₂ O were placed therein.
₃ and Cd ₂ Nb ₂ O ₇ mixed powder was used as a target. Al ₂ O ₃ , Fe ₂ O ₃ , Cd ₂
Each Nb ₂ O ₇ powder was wet-mixed for 30 minutes with a paint shaker using ethanol prepared by mixing powders of each oxide material, before filling the stainless petri dish. Then, the solvent was further removed and dried, and then a stainless petri dish was filled and used as a sputtering target. Sputtering gas is Ar: O ₂ =
A mixed gas of 7: 3 was used, and the purity of each gas of Ar and O ₂ was 99.995% or more. The board has (1
11) A Si wafer having an orientation was used. The Si wafer was an n-type and had a resistivity of about 1 (Ωcm). A film thickness of 20 was previously formed on the Si wafer by oxidation treatment.
A 0 nm SiO ₂ layer is provided. The purpose of providing this layer is mainly to secure electric insulation at the time of evaluation of dielectric properties. Prior to the film formation, the substrate temperature was raised to 200 ° C., and the moisture adsorbed mainly on the substrate surface was desorbed. Further, 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. The degree of vacuum is 2 × 10 ^-7 before introducing the sputtering gas.
It was confirmed that the pressure was below Torr. During the sputtering film formation, the total gas pressure was kept constant at 25 mTorr. During the sputtering, the copper anode fixing the substrate was water-cooled to maintain the substrate temperature during film formation at 20 to 25 ° C. The high frequency input power was 110 W, and the sputtering film formation was performed for 30 to 60 minutes. The thin films obtained in this manner showed a change in film thickness due to a change in the sputtering rate depending on the composition of the target, but each of the thin films showed a film thickness of 500 to 1000 nm.

By the thin film forming process as described above, A
A sputtered thin film made of ternary 1 ₂ O ₃ , Fe ₂ O ₃ , and Cd ₂ Nb ₂ O ₇ was prepared. No. 2 in FIG. The compositions shown by the numbers 1 to 25 were prepared, and the film structure was evaluated and the dielectric properties were measured for each of them. When the correspondence between the target composition and the thin film composition of the obtained thin film was examined by inductive plasma emission analysis, it was found that the two compositions corresponded with an error of about 3%. Therefore, in the following description, the composition of the target is used as the composition of the thin film. Dielectric properties were evaluated by a Soya tower circuit commonly used in the characterization.
With this circuit, the electric field dependence of the electric flux density (D) was evaluated and the value of spontaneous polarization (Ps) was obtained. In the evaluation of the dielectric property, the electrode configuration as shown in FIG. 3 is used, and the electrode 4 for applying an electric field to the thin film 1 is taken out from the oxide thin film 2 side so that two capacitors C ₁ are equivalently formed. , C ₂ are connected in series, the Schottky characteristic generated at the interface between the metal electrode and Si when the metal electrode is taken out from the Si 3 side is prevented, and accurate dielectric property evaluation is performed. The metal electrode has a thickness of about 100 nm on the surface of the thin film and a diameter of 4 mm.
Au electrode was formed by the sputtering method.

As-deposited state (As-de) of the sputtering thin film produced by the above-mentioned thin film forming method.
The structure and dielectric properties of the (position state) were evaluated.
First, the results of evaluating the structure of the thin film will be described. FIG. 4 shows the XRD diffraction result of the film after the sputter film formation of various compositions produced on the dotted line A in FIG. No. shown in FIG. 10, No. 15, No. 18 is shown in FIG.
It corresponds to the number inside and represents the composition of the thin film sample. XR
A Cu target was used as the D radiation source, and a monochromator was attached. In the XRD result shown in FIG. 4, the diffraction line corresponding to the (111) plane of Si used as the substrate is also seen to be superimposed on the diffraction result of the thin film. Cd ₂ Nb
₂ O ₇ thin film No. In No. 7, the thin film was crystallized in the As-deposit state, but Al ₂ O ₃ and Fe
Composition in which ₂ O ₃ is excessive (No. 10, No. 15, N
o. In 18), no X-ray diffraction line due to crystallization of the thin film was observed, which shows that the thin film is in an amorphous state. Further, FIG. 5 shows the XRD diffraction result of the film after the sputter film formation of various compositions produced on the dotted line B of FIG. No. shown in FIG. 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 FIG. 5, there is no clear diffraction line other than the diffraction line corresponding to the (111) plane of Si in the result of XRD, and all the thin films of these compositions have an amorphous structure. Understand. Further, No. 2 shown in FIG. 1
~ No. As a result of performing XRD analysis on all the 25 films, in the thin films indicated by black circles in FIG.
There is no clear diffraction line other than the diffraction line corresponding to the (111) plane of i, and the region surrounded by α, β, γ, δ, ε, φ in FIG. As-deposit
It was found that the thin film had an amorphous structure in (state).

Then, in order to observe the fine structure of the amorphous structure, No. 1 in FIG. High-resolution TEM observation was performed on the film having the composition of 15. In TEM observation, etching is performed from the surface side and the substrate side of the thin film, and the structure near the midpoint in the thickness direction of the thin film is observed. According to this, the lattice image could not be recognized even at the resolution of 0.3 nm. The thin film sample was subjected to selected area electron beam diffraction in a region with a diameter of about 200 nm, and the observed diffraction ring showed a very wide halo pattern, indicating that the thin film has a very high amorphous property.

Next, the dielectric characteristics will be described. First,
FIG. 6 shows a change in the dielectric hysteresis loop on the dotted line A in FIG. No. on the same line. In the film of No. 7, the thin film became conductive, and the dielectric characteristics could not be evaluated. The number on the left shoulder of the hysteresis loop in FIG. 6 is
It corresponds to the number indicating the composition in FIG. As is clear from this result and the result of the structural analysis in FIG.
o. 10, No. 15, No. It was found that the thin film of 18 exhibits ferroelectricity while having an amorphous structure. In addition, the thin film composition on the straight line A in FIG.
_{(0.5Fe 2 O 3 -0.5Al 2 O} 3) - (1-y)
When expressed as Cd ₂ Nb ₂ O ₇ , the dependence of the saturation charge density (Ps) of the thin film on y was shown. The saturated charge density is calculated from the hysteresis loop of the dielectric characteristics shown in FIG.
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 intersecting the coaxial was defined as the saturated charge density. It can be seen that Ps is present over a wider composition range than in FIG. 7 and the thin film exhibits ferroelectricity, but on the same line, Cd ₂ Nb
It can be seen that the ferroelectricity disappears in the composition region close to ₂ O ₇ . It is considered that the phase precipitated in this composition region is not the ferroelectric phase but the paraelectric phase. Also, in FIG. 2 and line B, the composition dependence of the hysteresis loop is shown for each composition (FIG. 8). The numbers shown on the left shoulder of the hysteresis loop in FIG. 8 correspond to the numbers indicating the composition in FIG. As is clear from this, it can be seen that ferroelectricity is observed in the thin films in all compositions. The saturation charge density (Ps) was obtained by the method described above from this hysteresis loop. The composition change of the straight line B is 0.
_{80 (xAl 2 O 3 - (} 1-x) Fe 2 O 3) -0.2
It is represented by the notation 0Cd ₂ Nb ₂ O ₇ . P for x
The dependence of s is shown in FIG. As can be seen from the figure, it can be seen that Ps exists for all x values and exhibits ferroelectricity. Further, the dielectric characteristics and the structure by X-ray were evaluated for the compositions of all the thin films shown in FIG. The results are shown together in the figure. That is,
In the figure, the black circles indicate the composition of the thin film exhibiting amorphous ferroelectricity, and the shaded circles indicate the composition exhibiting paraelectricity while having an amorphous structure. Further, the white circles are crystalline thin films, and the thin films showed conductivity. The structure and dielectric properties of the 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 has an amorphous structure and exhibits ferroelectricity is widely distributed in the figure, and in the figure, α, β, γ, δ, ε, The region surrounded by φ (portion covered with thin ink) can be defined as a composition region in which ferroelectricity is exhibited while taking an amorphous structure. Also,
Table 1 shows the correspondence between the thin film composition and the saturation charge density Ps for all the compositions shown in FIG. It has been found that a thin film exhibiting ferroelectricity has a saturated charge density of about 35 (nC / cm ² ) or more, and this charge density reaches up to about 113 (nC / cm ² ). Therefore, it is considered that it has sufficient practical characteristics.

[0013]

[Table 1]

Example 2 A thin film was prepared by changing the substrate to a glass substrate by the film forming method described in Example 1. Corning's No. 1 for glass substrates 7059 was used. No. 2 shown in FIG. 1
5 and No. 5 A thin film having a composition of 20 was prepared. The film thickness of the sputter-formed thin film was about 200 nm.
The produced thin film had an amber color. In each of the thin films, an antireflection film was applied in the near infrared region, and the light transmittance was measured. FIG. 10 shows the light wavelength dependence of the transmittance. As can be seen from this result, it is understood that the amorphous ferroelectric thin film has a light transmittance of 90% or more in the near infrared region, and that the thin film can be applied to an electro-optical element.

Example 3 By the same film forming method as in Example 1, the Pyrochlore dielectric material was changed to ferroelectric Cd ₂ Nb ₂ O ₇ , and P
A thin film was prepared using b ₂ Nb ₂ O ₇ . The composition of the produced thin film is shown in the triangular composition diagram of FIG. 1 and N
o. 25-No. Numbers up to 48 are shown as points to be added. The As-deposited thin film was subjected to dielectric and structural analysis by X-ray. The results are summarized in Figure 11.
Shown in. In the figure, the black circles indicate the composition of the thin film exhibiting amorphous ferroelectricity, and the shaded circles indicate the composition of the thin film exhibiting paraelectricity while having an amorphous structure. Further, the white circles are crystalline thin films, which indicate the composition of the thin films having conductivity. From these results, in the triangular composition diagram, the region surrounded by α, β, γ, δ, ε, and φ (the part that is thinly blacked) shows the amorphous ferroelectricity in the thinly blacked compositional region. I found that. Here, Pb ₂ Nb ₂ O ₇ which exhibits antiferroelectricity by itself is used.
It has been found that the material also shows remarkable ferroelectricity by adding Fe ₂ O ₃ or Al ₂ O ₃ in excess. Table 2 shows a list of saturated charge densities for each composition shown in FIG. According to the table, Al ₂ O ₃ —Fe ₂ O
_{In the 3-} Pb ₂ Nb ₂ O ₇ -based amorphous ferroelectric thin film, a saturation charge density of about 158 (nC / cm ² ) at maximum was observed.

[0016]

[Table 2]

[0017] In Example _{4 M 2 O 3 -Al 2 O} 3 -Cd 2 Nb 2 O 7 system,
Each thin film was produced using the elements shown in Table 3. The thin film was manufactured by the method described in Example 1. Further, the structure evaluation of the thin film was performed by the X-ray diffraction method, and the conditions thereof were as described in Example 1. Furthermore, the method of evaluating the dielectric properties of the thin film is the same as in Example 1. However, in the sputtering film formation, M is Zr, Mo, Pd, H
In the case of f, Ta and W, metal fine powder of each element was used instead of M ₂ O ₃ as a target. Other S
c, Ti, V, Cr, Mn, Co, Ni, Y, Nb, I
n, La, Ce, Pr, Nd, Sm, Eu, Gd, T
b, Dy, Ho, Er, Tm, Yb, and Lu are M
_{A 2} O ₃ type oxide material was used as a target. Also, N
Since i ₂ O ₃ contains water of crystallization, it was heated to about 200 ° C. to eliminate the water of crystallization before it was used as a target to make it anhydrous. Fig. 12 corresponding to all M elements
A film having a composition indicated by a circle in FIG.
The structure and dielectric properties of the film were evaluated in the t-state. In the figure, the black circles indicate the composition of the thin film exhibiting amorphous ferroelectricity, and the shaded circles indicate the composition of the thin film exhibiting paraelectricity while having an amorphous structure. Further, the white circles are crystalline thin films, which indicate the composition of the conductive thin films. From this result, in the triangular composition diagram,
It was found that the region surrounded by α, β, γ, δ, ε, and φ (portion coated with thin ink) exhibits amorphous ferroelectricity in the composition region coated with thin ink. N in the composition diagram
o. Table 4 shows the saturation charge densities (Ps) measured at various M values for the film having the composition noted 49. From this, it can be understood that Ps is observed in all the thin films shown in the table, and the ferroelectricity is exhibited in each thin film.

[0018]

[Table 3]

[0019]

As described above, M ₂ O ₃ -Al ₂ O ₃ -A
A thin film of ₂ B ₂ O ₇ (A ₂ B ₂ O ₇ is a Pyrochlore type dielectric) -based thin film is thinned by a low substrate temperature, for example, a substrate temperature of about 25 ° C. by an RF sputtering method or the like, so that a transparent film having an amorphous structure is obtained. A ferroelectric thin film with high optical property can be obtained, and it can be applied to a sensor, a memory, and an electro-optical element using ferroelectricity.

[Brief description of drawings]

FIG. 1 is a composition system diagram for explaining the present invention.

FIG. 2 is a composition system diagram for explaining one embodiment of the present invention, and an explanatory diagram of a dielectric property and a 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 is an X diagram for explaining an embodiment of the present invention.
It is a line diffraction pattern.

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

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

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

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

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

FIG. 10 is a diagram showing wavelength-independent characteristics of light transmittance for explaining the embodiment.

FIG. 11 is a composition system diagram for explaining another embodiment of the present invention, and an explanatory diagram of dielectric properties and thin film structure.

FIG. 12 is a composition system diagram for explaining another embodiment of the present invention, and an explanatory diagram of dielectric characteristics and a thin film structure.

Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H01B 3/00 F 9059-5G H01G 7/06 7924-5E (72) Inventor Hiroyuki Nii Ube City, Yamaguchi Prefecture Kogushi No.5, 1978, Ube Industries, Ltd., Inorganic Materials Research Center

Claims (4)

[Claims] 1. A ternary oxide containing a transition metal oxide (M ₂ O ₃ ) -aluminum oxide (Al ₂ O ₃ ) -Pyrochlore type compound (A ₂ B ₂ O ₇ ) as a main component, and An amorphous ferroelectric oxide material characterized in that a ternary oxide has an amorphous structure. (However, M ₂ O ₃ is Sc, Ti, V, Cr, Mn, Fe,
Co, Ni, Y, Zr, Nb, Mo, Pd, Hf, T
At least one selected from the group consisting of oxides of a, W, In and lanthanum series elements, and A ₂ B ₂ O ₇ is a Pyrochlore type compound exhibiting ferroelectricity or antiferroelectricity. ) 2. The ternary oxide is M ₂ O ₃ , Al ₂ O ₃ or A.
In the composition diagram of the three components of _{2 B 2 O 7, aM 2} O 3 -
(1-a) Al ₂ O ₃ and 0.90 Al ₂ O ₃ −
_{0.10 (bM 2 O 3 - (} 1-b) A 2 B 2 O 7) _{and, cAl 2 O 3 - (1} -c) A 2 B 2 O 7 and, 0.20 (dAl ₂ O ₃ - (1-d) M ₂ O ₃ )-
0.80A ₂ B ₂ O _{7 and, eA 2 B 2 O 7 -} (1
-E) M ₂ O _3, as well as, 0.90M ₂ O ₃ -0.10
_{(FA 2 B 2 O 7 -} (1-f) Al 2 O 3) 0.10 in the composition lines each represented by ≦ a ≦ 0.90 and 0.
00 ≦ b ≦ 1.00 and 0.20 ≦ c ≦ 0.90 and 0.00 ≦ d ≦ 1.00 and 0.20 ≦ e ≦ 0.90 and 0.00 ≦ f ≦ 1.00 The amorphous ferroelectric oxide material according to claim 1, which has a composition surrounded by six defined composition lines. 3. The amorphous ferroelectric oxide material according to claim 1 or 2, wherein the ternary oxide is formed in the form of a thin film. 4. A ternary oxide is formed as an amorphous thin film on a substrate using a film forming means while maintaining the substrate temperature at 300 ° C. or lower, and the ferroelectric oxide is produced as it is. The method for producing an amorphous ferroelectric oxide material according to claim 3, wherein a material is obtained.