JP3310881B2 - Laminated thin film, substrate for electronic device, electronic device, and method of manufacturing laminated thin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated thin film comprising a perovskite type or tungsten bronze type dielectric layer and an electrode film, a substrate for an electronic device comprising the laminated thin film,
The present invention relates to an electronic device and a method of manufacturing a laminated thin film, and more particularly to a multilayer film structure mainly used for a semiconductor memory cell and a transistor cell.

[0002]

2. Description of the Related Art Electronic devices in which a superconducting film or a dielectric film is formed and integrated on a semiconductor crystal substrate, which is mainly a Si single crystal substrate, have been devised. By combining a semiconductor and a superconductor or a dielectric, for example, in a combination of a semiconductor and a superconductor, a SQUID, a Josephson element, a superconducting transistor, an electromagnetic wave sensor, a superconducting wiring LSI, and the like, and in a semiconductor and a dielectric, a higher degree of integration is achieved. LSI, dielectric isolation LSI using SOI technology,
Nonvolatile memory, infrared sensor, optical modulator and optical switch, OEIC (opto-electro integrated circuit: opto-electro
nic integrated circuits) are being prototyped.

In a semiconductor device using such a superconductor material or a dielectric material, it is necessary to use a single crystal as the superconductor material and the dielectric material in order to secure optimum device characteristics and reproducibility thereof. . In the case of a polycrystal, it is difficult to obtain good device characteristics due to disturbance of physical quantities by grain boundaries. The same is true for a thin film material, and a superconducting or dielectric epitaxial film as close as possible to a perfect single crystal is desired.

The crystal structures of main oxide superconductors and ferroelectrics, which are valuable for application, have a perovskite structure. Epitaxial growth of perovskite oxide largely depends on the material and crystal orientation of the substrate, and it is not possible at present to directly grow perovskite oxide on a Si substrate. Then, S
A buffer layer made of YSZ (a material in which Y is doped into ZrO ₂ ) epitaxially grown on an i-substrate is provided, and a YBCO and Bi-based superconducting film, which is a perovskite oxide, is epitaxially grown thereon. Phys
s. Lett. , Vol. 54, no. 8, p. 754
-P. 756 (1989), Japanese Jou
rnal of Applied Physics, V
ol. 27, no. 4, L634-635 (1988)
And JP-A-2-82585.

In particular, YSZ has good lattice matching with the Si crystal of the substrate and also has excellent lattice matching with the perovskite crystal. The YSZ film has attracted attention.

However, a perovskite-type oxide crystal in which a direct epitaxial growth has been realized by using a YSZ buffer layer has heretofore been made of YBa ₂ C
_{u 3 O 7-x (YBCO} ), BiSrCaCu 2 O x, L
aSrCoO _{3 and the} like, all of which are composite perovskites. The composite perovskite is a simple perovskite variant, K ₂ NiF ₄ type, Nd ₂ CuO ₄ type, Sr ₃
It has a crystal structure such as Ti ₂ O ₇ type. Such a composite perovskite has a long period structure in the c-axis direction and has strong anisotropy between the a-axis and the c-axis. Therefore, the c-axis orientation is strong, and a c-axis oriented epitaxial film can be easily obtained using the substrate as the c-plane.
As described in Appl. Phys. Lett. 57 (11) 1161-1163 (1990), the plane orientation relationship of the epitaxial film is YBCO
(001) // YSZ (001) // Si (100) and YBCO [110] // YSZ [100] /
/ Si [010], and the unit cell of YBCO is rotated by 45 ° in the c-plane with respect to the YSZ lattice, and the lattice is matched to grow epitaxially.

[0007] However, according to the study of the inventors, BaTiO ₃ , SrTi
O _3, PbTiO _3, PZT, a simple perovskite structure such as a material for the base described above PLZT, for example, in the case of _{BaTiO 3, BaTiO 3 (001)} // YSZ (001) // Si (100), and BaTiO ₃ [11
As in [0] // YSZ [100] // Si [010], it is impossible to rotate the unit cell of BaTiO ₃ by 45 ° in the c-plane with respect to the YSZ lattice so that the lattice can be matched and the epitaxial growth can be performed. Was impossible. There are no reports from other researchers.

This is based on BaTiO ₃ , SrTiO ₃ , PbTiO ₃ , PZT,
Materials based on a simple perovskite structure, such as PLZT, have a simple unit cell perovskite structure and low anisotropy. Therefore, it is considered that the (001) orientation growth of the simple perovskite structure becomes the (110) orientation and the lattice matching is achieved, rather than rotating in the plane to lattice match. Therefore, a (001) oriented epitaxial film having a simple perovskite structure cannot be obtained.

By the way, BaTiO ₃ , PbTiO ₃ , PZT, PLZT and the like are ferroelectrics, and a nonvolatile memory can be realized by combining with a semiconductor device. This memory utilizes the polarization reversal phenomenon of a ferroelectric substance. In the case of a ferroelectric substance such as BaTiO ₃ , PbTiO ₃ , PZT and PLZT, the polarization axis is in the c-axis direction of the perovskite structure. Therefore, in order to use these ferroelectric films for a memory, it is necessary to use a (001) oriented film. However, as described above, BaTiO ₃ , PbTiO ₃ , PZT
When a material having a simple perovskite structure such as PLZT was formed, an epitaxial film having a (001) orientation could not be obtained.

[0010]

SUMMARY OF THE INVENTION The main object of the present invention is to provide a laminated thin film having a c-plane unidirectional thin film composed of a simple perovskite type or tungsten bronze type material having a c-plane unidirectional orientation. An object of the present invention is to provide an electronic device substrate, an electronic device, and a method for manufacturing the laminated thin film provided.

In order to solve such a problem, the present inventors have conducted various studies and found that a thin film having high crystallinity and molecular flatness is used as a thin film containing ZrO ₂ as a main component. In particular, it has been found that a perovskite oxide thin film can be solved by finding a new crystal growth method.

[0012]

Specifically, such an object is achieved by the present invention described in the following (1) to (29). (1) An oxide thin film is formed on a semiconductor single crystal substrate, and the oxide thin film is an epitaxial thin film mainly composed of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y). And a layered thin film comprising an oxide thin film formed of a perovskite-type or tungsten bronze-type dielectric material on the oxide thin film and having a c-plane unidirectional alignment in parallel with the substrate surface. (2) The above-mentioned dielectric material of perovskite type or tungsten bronze type is barium titanate, strontium titanate, lead zircon titanate (PZT), strontium barium niobate (SBN) or barium lead niobate (PBN). The laminated thin film of (1). (3) The laminated thin film according to (1) or (2), wherein the oriented thin film is an epitaxial film. (4) The semiconductor single crystal substrate is a Si single crystal substrate having a Si (100) plane on the surface, and the oriented thin film and S
The laminated thin film according to the above (3), wherein the crystal axis orientation relationship of the i-single-crystal substrate is perovskite or tungsten bronze [100] // Si [010]. (5) An epitaxial film formed of a perovskite-type or tungsten bronze-type material on a Si single-crystal substrate formed of a Si single crystal having a Si (100) plane on the surface, and having a crystal axis orientation relationship of perovskite or A zirconium oxide stabilized with zirconium oxide or a rare earth metal element (including Sc and Y) between the silicon single crystal substrate and the oriented thin film, comprising an oriented thin film of tungsten bronze [100] // Si [010] An oxide thin film including at least one layer of an epitaxial thin film containing, as a main component, zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) having a composition of Zr _{1 -x} R _x
O _2- δ (where R is a rare earth metal element containing Sc and Y, x = 0 to 0.75 and δ = 0 to 0.5)
Wherein the zirconium oxide of the oxide thin film contains 93 mol% or more of Zr in terms of only the constituent elements except oxygen, and the half width of the rocking curve of (002) reflection of the oxide thin film is 1.5 ° A laminated thin film in which at least 80% of the surface of the oxide thin film has a ten-point average roughness Rz of 2 nm or less at a reference length of 500 nm. (6) The perovskite-type or tungsten-bronze-type material is barium titanate, strontium titanate, lead zircon titanate (PZT), strontium barium niobate (SBN) or barium lead niobate (PBN). ). (7) Zirconium oxide or rare earth metal element (Sc
And Y) containing zirconium oxide stabilized as a main component, a first epitaxial film formed on a semiconductor single crystal substrate, and a first perovskite-type material formed directly on the first epitaxial film. 2. An oxide thin film including an oriented thin film which is an epitaxial film of No. 2, wherein the semiconductor single crystal substrate is a Si single crystal substrate having a Si (100) plane on a surface thereof. Perovskite crystal orientation [100]
// Si [010], and the composition of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) in the oxide thin film is Zr _1-x R
_x O ₂₋ δ (where R is a rare earth metal element containing Sc and Y, x = 0 to 0.75, δ = 0 to 0.5), and the zirconium oxide of the oxide thin film Contains at least 93 mol% of Zr in terms of only the constituent elements except oxygen, the half-width of the rocking curve of (002) reflection of the oxide thin film is 1.5 ° or less, and the surface of the oxide thin film At least 80% of the laminated thin films have a ten-point average roughness Rz of 2 nm or less at a reference length of 500 nm. (8) The laminated thin film according to (7), wherein the perovskite-type material of the second epitaxial film is mainly composed of barium titanate, strontium titanate or a solid solution thereof. (9) Conductive orientation which is an epitaxial film formed of a metal or a conductive oxide on a Si single crystal substrate having a Si (100) plane on its surface and having a single orientation of c-plane or a-plane parallel to the substrate surface A thin film, and an alignment thin film formed of a perovskite type or a tungsten bronze type material on the conductive alignment thin film, wherein the alignment thin film is an epitaxial film, and a crystal axis orientation relationship between the Si substrate and the alignment thin film is perovskite or Tungsten bronze [100] // Si [010], wherein zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) is interposed between the Si single crystal substrate and the conductive alignment thin film. A laminated thin film including an oxide thin film including at least one epitaxial thin film as a main component. (10) The metal is Pt, Ir, Os, Re, Pd,
The laminated thin film according to the above (9), which is a metal containing at least one of Rh and Ru, and wherein the conductive oxide is an oxide containing In or a perovskite oxide. (11) The perovskite-type or tungsten bronze-type material of the alignment thin film is barium titanate, strontium titanate, lead zircon titanate (PZT), strontium barium niobate (SBN), or barium lead niobate (PBN). (9) or (1)
0) The laminated thin film. (12) The plane orientation relationship between the Si single crystal substrate, the conductive alignment thin film and the alignment thin film is perovskite or tungsten bronze (001) /// conductive thin film (001).
// A laminated thin film according to any one of the above (9) to (11), which is Si (100). (13) The composition of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) in the oxide thin film is Zr _{1 -x} R _x O ₂ -δ (where R is Sc and Y Is a rare earth metal element containing
= 0 to 0.75 and δ = 0 to 0.5) in any one of the above (1) to (4) and (7) to (12). (14) The laminate according to any one of (1) to (4) and (7) to (13), wherein the zirconium oxide of the oxide thin film contains 93 mol% or more of Zr in terms of only the constituent elements except oxygen. Thin film. (15) The above (1) to (1), wherein the half width of the rocking curve of the (002) reflection of the oxide thin film is 1.5 ° or less.
(4) The laminated thin film according to any one of (7) to (14). (16) at least 80% of the surface of the oxide thin film
The laminated thin film according to any one of (1) to (4) and (7) to (15), wherein a ten-point average roughness Rz at a reference length of 500 nm is 2 nm or less. (17) a first epitaxial film mainly composed of zirconium oxide stabilized with zirconium oxide or a rare earth metal element (including Sc and Y), and a perovskite-type material formed thereon (1) to (4) including at least a second epitaxial film according to
The laminated thin film according to any one of (16). (18) The laminated thin film according to (17), wherein the perovskite-type material of the second epitaxial film is mainly composed of barium titanate, strontium titanate or a solid solution thereof. (19) The laminated thin film according to the above (17) or (18), wherein the crystal axis orientation relationship between the Si single crystal substrate and the second epitaxial film made of the perovskite-type material is perovskite [100] // Si [010]. (20) An electronic device substrate comprising the laminated thin film according to any one of (1) to (19). (21) An electronic device comprising the laminated thin film according to any one of (1) to (20). (22) Si single crystal substrate, on this Si single crystal substrate,
Zirconium oxide or rare earth metal elements (Sc and Y
) Comprising: an oxide thin film formed of zirconium oxide stabilized by the above method; and an oriented thin film formed of a perovskite-type or tungsten bronze-type material on the oxide thin film. Heating a Si single crystal substrate in a vacuum chamber, introducing an oxidizing gas into the vacuum chamber, and applying Zr or Zr and at least one rare earth metal element (including Sc and Y) to the surface of the single crystal substrate. A method for producing a laminated thin film in which a single-oriented epitaxial film is formed by epitaxially growing the oxide thin film on the surface of the single crystal substrate by performing supply by evaporation and using the oxide thin film as the oxide thin film. (23) The zirconium oxide or zirconium oxide stabilized by the rare earth metal element (including Sc and Y) is Zr _{1 -x} R _x O ₂ -δ (where R is a rare earth metal element containing Sc and Y). And x = 0 to 0.75, and δ is 0 to 0.5.). (24) As the Si single crystal substrate, Z
r or Zr and at least one rare earth metal element (including Sc and Y) and oxygen
The method for producing a laminated thin film according to the above (22) or (23), using a Si surface-treated substrate having a surface structure of × 1. (25) The Si surface-treated substrate forms a Si oxide layer having a thickness of 0.2 to 10 nm on the surface of the Si single crystal substrate, and then sets the substrate temperature to 600 to 1200 ° C. An oxidizing gas is introduced into the atmosphere, and the oxygen partial pressure of at least the atmosphere near the substrate is reduced to 1 × 10 ^-4 to 1 × 10 ^-1 Torr.
In this state, Zr or Zr and at least one rare earth metal element (including Sc and Y) are vaporized and supplied to the substrate surface on which the Si oxide layer is formed. (24). (26) When forming the Si oxide layer, the Si single crystal substrate is placed in a vacuum chamber into which an oxidizing gas has been introduced.
The method for producing a laminated thin film according to (25) above, wherein the Si oxide layer is formed by heating to 0 ° C. and setting the oxygen partial pressure of the atmosphere in the vacuum chamber at least near the substrate to 1 × 10 ⁻⁴ Torr or more. (27) An oxidizing gas is injected from the vicinity of the surface of the Si single crystal substrate from the vicinity thereof, and an atmosphere having a higher partial pressure of the oxidizing gas than other parts is formed only in the vicinity of the Si single crystal substrate.
2) The method for manufacturing a laminated thin film according to any one of (26) to (26). (28) The Si single crystal substrate has a substrate surface area of 10
cm ² or more, and by rotating the substrate, the oxidizing gas high partial pressure atmosphere is provided over the entire surface of the Si single crystal substrate, and a substantially uniform oxide is formed over the entire surface of the Si single crystal substrate. The method for producing a laminated thin film according to any one of the above (22) to (27), which forms a thin film. (29) When forming the epitaxial film, the S
(22) to heating the i single crystal substrate to 750 ° C. or more
(28) The method for producing a laminated thin film according to any of (28).

[0013]

The first oxide thin film (underlayer) of the present invention has:
A simple perovskite film, which is an oriented thin film, can be favorably epitaxially grown. Furthermore, for example, BaTiO ₃ -Zr _1
-x RxO _1- δ-Si, the plane orientation relation is BaTiO ₃ (001) // Zr _1-x
RxO _2- δ (001) // Si (100) and the crystal axis orientation is BaTiO ₃ [1
By growing on [00] // Zr _1-x RxO _2- δ [100] // Si [010], a (001) oriented BaTiO ₃ thin film can be obtained. Further, by using this laminated thin film as a base layer, that is, a buffer layer, other simple perovskite type, composite perovskite type ｛layered perovskite type (K ₂ NiF ₄₎
(Including molds), (ferro) dielectric materials such as tungsten bronze molds, and conductive epitaxial films such as metals and conductive oxides can be obtained on Si.

In particular, when the deposition substrate is rotated in the plane, a uniform and high-quality laminated oxide thin film having a large area of 10 cm ² or more can be obtained.

JP-A-2-258700 discloses that a perovskite-type oxide (BaTiO ₃ ) single crystal film is formed on a single-crystal oxide substrate by co-evaporation. Techniques of controlling the composition ratio using a metal element evaporation source, increasing the pressure of oxygen only in the vicinity of the substrate, and using a substrate having a specific orientation plane are disclosed. The laminated thin film according to the present invention further has a plane orientation relationship of BaTiO ₃ (00
1) // Zr _1-x RxO _2- δ (001) // Si (100) and BaTiO ₃ [100] //
An epitaxial film of Zr _1-x RxO _2- δ [100] // Si [010] can be formed. That is, a composition Zr _1-x RxO _2- δ formed on a Si (100) single crystal (where R is a rare earth metal containing Sc and Y, x = 0 to 0.75, δ = 0
０．５0.5) high crystallinity and an epitaxial film having flatness at the molecular level as a deposition substrate, a heating temperature of the deposition substrate of 850 ° C. to 1200 ° C., an initial stage of forming BaTiO ₃ , that is, The (001) epitaxial film can be grown on the Si substrate by setting the supply ratio Ba / Ti of the metal element to 0 to 1 (excess supply of the B-site metal) in the region of 0 to 1 nm in film thickness. Perovskite-type materials and tungsten bronze-type materials other than BaTiO ₃ can be similarly produced. That is, an excessive amount of B-site metal is supplied at the beginning of film formation.

Furthermore, the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2-258700 is not intended at all for a substrate having a large surface area of 10 cm ² or more, and there is no suggestion. In fact, Japanese Patent Application Laid-Open No. 2-258700 also discloses that a substrate area of 2.
There is only an embodiment of 25 cm ² (about 15 × 15 mm ² ). In the present invention, a substrate area of 10 cm ² or more is made possible by rotating the substrate in the plane of the substrate.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION A laminated thin film according to a first aspect of the present invention is composed mainly of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y), and is formed on a semiconductor single crystal substrate. An oxide thin film including at least one layer of the formed epitaxial thin film,
And a perovskite-type or tungsten-bronze-type material formed on the oxide thin film as an underlayer and c-plane orientation parallel to the substrate surface, that is, a (001) orientation, more preferably a c-plane single orientation, and still more preferably. It is characterized by comprising an oriented thin film grown epitaxially.

In this specification, the term “single alignment film” refers to
It means a crystallized film in which the target crystal planes are aligned in parallel with the substrate surface. Specifically, for example, (00
1) A single alignment film, that is, a c-plane single alignment film,
-Θ X-ray diffraction (XRD) is such that the reflection intensity other than the (00L) plane is 10% or less of the maximum peak intensity of the (00L) plane reflection;
It is preferably at most 5%. In this specification, (00L) is a generic term for equivalent surfaces such as (001) and (002), and the same applies to (L00).

In this specification, the term “epitaxial film” means that the crystal is aligned in the X-axis, Y-axis and Z-axis directions when the film plane is the XY plane and the film thickness direction is the Z axis. Is what you are doing. Specifically, first, when measurement is performed by X-ray diffraction, the peak intensity of the reflection of an object other than the target surface is one of the maximum peak intensity of the target surface.
It must be 0% or less, preferably 5% or less. For example, in a (001) epitaxial film, that is, a c-plane epitaxial film, the peak intensity of the film other than the (00L) plane in the 2θ-θ X-ray diffraction is 10% or less, preferably 5% of the maximum peak intensity of the (00L) plane. It is as follows. Second, RH
It is necessary to show a streak pattern in the EED evaluation. If these conditions are satisfied, it can be said that the film is an epitaxial film.
RHEED is a reflection high-speed electron diffraction (Reflecti
on High Energy Electron Diffraction) and RHE
The ED evaluation is an index of the orientation of the crystal axis in the film plane.

The simple perovskite structure has the formula AB
It is represented by O ₃ . Here, A and B represent cations entering the A site and the B site, respectively, in the perovskite crystal structure. A is Ca, Ba, Sr, Pb,
It is preferably at least one kind selected from K, Na, Li, La and Cd, and B is Ti, Zr, Ta and Nd.
Preferably, it is at least one selected from b.

The molar composition ratio of A / B in such a perovskite compound is from 0.8 to 1.2, and preferably from 0.9 to 1.1. By setting A / B in this range, the insulating properties of the dielectric can be ensured and the crystallinity can be improved.
Dielectric or ferroelectric properties can be improved.
On the other hand, if A / B is less than 0.8, the effect of improving crystallinity cannot be expected. When A / B exceeds 1.2, it tends to be difficult to form a uniform thin film. Such an A / B composition ratio is realized by controlling the film forming conditions as described below. Further, the composition of O in the above-mentioned ABO ₃ is not limited to 3. Some perovskite materials may form a stable perovskite structure with oxygen vacancies or excess oxygen.
In BO _X, the value of x is preferably 2.7 to 3.3. The composition ratio of A / B can be determined by X-ray fluorescence analysis.

The simple perovskite compound in the present invention
The thing is A¹⁺B⁵⁺O_Three , A²⁺B⁴⁺O_Three , A³⁺B³⁺O
_Three , A_X BO_Three , A (B '_0.67B "_0.33) O_Three , A
(B '_{0. 33}B "_0.67) O_Three , A (B_0.5 ⁺³ B_0.5 ⁺⁵ ) O
_Three , A (B_0.5 ²⁺ B_0.5 ⁶⁺ ) O_Three , A (B_0.5 ¹⁺ B
_0.5 ⁷⁺ ) O_Three , A³⁺(B_0.5 ²⁺ B_0.5 ⁴⁺ ) O_Three , A (B
_0.25 ¹⁺B_0.75 ⁵⁺) O_Three , A (B_0.5 ³⁺ B_0.5 ⁴⁺ )
O_2.75, A (B_0.5 ²⁺ B_0.5 ⁵⁺ ) O _2.75Any of
You may.

Specifically, CaTiO ₃ , BaTiO _3
3 , PbTiO ₃ , KTaO ₃ , BiFeO ₃ , NaT
aO ₃ , SrTiO ₃ , CdTiO ₃ , KNbO ₃ , L
iNbO ₃ , LiTaO ₃ , PZT (PbZrO ₃ -P
bTiO ₃ ), PLZT (P added with La ₂ O ₃ )
bZrO ₃ -PbTiO ₃ ), other Pb-based perovskites, and solid solutions thereof.

PLZT is composed of PbZrO ₃ -PbTiO ₃
A compound La doped into PZT is a solid solution of the system, according to the notation of _{ABO 3, A = Pb 0.89 ~} 0.91 L
a _{0. 11} ~ _0.09, a _{B = Zr 0.65 Ti 0.35, (} Pb
_0.89 to _0.91 La _0.11 to _0.09 ) (Zr _0.65 Ti _0.35 ) O ₃
Indicated by

The simple perovskite compound preferably used in the present invention is a titanate or a titanate-containing perovskite compound, for example, BaTiO 3.
₃ , SrTiO ₃ , PLZT, PZT, CaTiO ₃ ,
PbTiO _{3 and the} like are preferred.

The tungsten bronze type structure has a chemical formula A
It is represented by B ₂ O ₆ . Here, A and B represent cations entering the A site and the B site, respectively, in the tungsten bronze type crystal structure. A is Ca, Ba, S
r, Pb, K, Na, Li, Cd, Sc, Y and at least one selected from rare earth elements;
Is preferably at least one selected from Nb, Ta, Ti and Zr.

The molar composition ratio of A / B in such a tungsten bronze type compound is 0.3 to 0.7, and more preferably 0.4 to 0.6. By setting A / B in this range, the insulating properties of the dielectric can be ensured, and the crystallinity can be improved, so that the dielectric characteristics or ferroelectric characteristics can be improved. On the other hand, if A / B is less than 0.3, the effect of improving crystallinity cannot be expected. If A / B exceeds 0.7, it tends to be difficult to form a uniform thin film. Such an A / B composition ratio is realized by controlling the film forming conditions as described below. AB ₂ described above
The composition of O in O ₆ is not limited to 6. Some tungsten bronze materials may be those Crossed oxygen defects or oxygen excess and stable tungsten bronze structure, the AB ₂ O _X, the value of x is preferably from 5.6 to 6.3. The composition ratio of A / B can be determined by X-ray fluorescence analysis.

As the tungsten bronze type material in the present invention, Landoit-Borenstein Vo.
l. Any of the tungsten bronze-type materials described in 16 above. Specifically, (Ba, Sr) Nb ₂ O ₆ ,
PbNb ₂ O ₆ , (Pb, Ba) NbO ₆ , PbTa ₂
O ₆ , BaTa ₂ O ₆ , PbNb ₄ O ₁₁ , PbNb ₂ O
₆ , SrNb ₂ O ₆ , BaNb ₂ O _6, etc. and their solid solutions.

Of the above materials, the above simple perovskite type or tungsten bronze type materials are barium titanate, strontium titanate, PZT, SBN ((B
a, Sr) Nb ₂ O ₆ ), PBN ((Pb, Ba) Nb
₂ O ₆ ) is preferred. Preferably, the oriented thin film is an epitaxial film.

In the present invention, it is also possible to obtain a c-plane single orientation film composed of a composite perovskite compound (including a layered perovskite compound (including a compound having a K ₂ NiF ₄ type structure)).

[0031] Bi-based layered compound of the layered perovskite compounds are generally represented by the formula _{Bi 2 A m-1 B m} O 3m + 3. In the above formula, m is an integer of 1 to 5, A
Is any of Bi, Ca, Sr, Ba, Pb, Na, K and rare earth elements (including Sc and Y);
Is any of Ti, Ta and Nb. Specifically, Bi ₄ Ti ₃ O ₁₂ , Bi ₂ SrTa ₂ O ₉ , Bi ₂
SrNb ₂ O _{9 and the} like. In the present invention, any of these compounds may be used, or a solid solution thereof may be used.

The substrate to be used is a single crystal, and may be a semiconductor such as gallium arsenide or silicon. Among them, a Si single crystal substrate is preferable. It is preferable that the (100) plane of the Si single crystal or the like be used so as to be the substrate surface.

The crystal axis orientation relationship between the oriented thin film and Si is perovskite or tungsten bronze [100].
// Si [010] is preferred. Note that Si is cubic.

The laminated thin film according to the second aspect of the present invention is preferably formed of a perovskite type or tungsten bronze type material on a Si single crystal substrate formed of a Si single crystal having a Si (100) plane on the surface. , An epitaxial film having a crystal axis orientation relationship of perovskite or tungsten bronze [100] // Si [01
0]. In this case, the oriented thin film is formed on the Si single crystal substrate via another thin film.

The perovskite type or tungsten bronze type material is preferably barium titanate, strontium titanate, PZT, SBN or PBN. An oxide thin film including at least one epitaxial thin film mainly composed of zirconium oxide stabilized by zirconium oxide or a rare earth metal element (including Sc and Y) is interposed between the Si single crystal substrate and the oriented thin film. Preferably, it is provided.

The laminated thin film according to the third aspect of the present invention includes an oriented thin film which is an epitaxial film formed of a tungsten bronze type material on a semiconductor single crystal substrate. In this case, the oriented thin film is formed on the semiconductor single crystal substrate via another thin film.

The material of the alignment thin film is SBN or PB
N is preferred. An oxide thin film including at least one epitaxial thin film mainly composed of zirconium oxide stabilized with zirconium oxide or a rare earth metal element (including Sc and Y) is provided between the semiconductor single crystal substrate and the oriented thin film. Has been established. The semiconductor single crystal substrate is preferably a Si single crystal substrate having a Si (100) plane on the surface.

The laminated thin film according to the fourth aspect of the present invention is composed mainly of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) and formed on a semiconductor single crystal substrate. An oxide thin film having a first epitaxial film and an oriented thin film as a second epitaxial film formed of a perovskite-type material without providing an intervening layer on the first epitaxial film.

The perovskite-type material of the second epitaxial film is preferably composed mainly of barium titanate, strontium titanate or a solid solution thereof, particularly, composed mainly of barium titanate. Is preferred. The semiconductor single crystal substrate is a Si single crystal substrate, and the crystal axis orientation relationship between the Si single crystal substrate and the oriented thin film is perovskite [100] // Si [010]. In such a second epitaxial film, 80% or more of the surface, preferably 90% or more, more preferably 9% or more.
5% or more has a ten-point average roughness Rz at a reference length of 500 nm of preferably 2 nm or less, more preferably 1 nm or less, and still more preferably 0.5 nm or less. In the present invention, such a flat surface can be easily realized. In the present specification, for example, Rz of 2 nm or less at 80% or more of the surface means that Rz is found at 80% or more when measured at any 10 or more locations averagely distributed over the entire thin film. It means that it is 2 nm or less. Rz can be measured by an atomic force microscope (AFM).

On the laminated thin film of the fourth aspect, as described above, an oriented thin film made of perovskite or the like other than the second epitaxial film constituting material is formed.
Is excellent in crystallinity and surface flatness, so that a high-quality oriented thin film can be obtained.

The laminated thin film according to the fifth aspect of the present invention comprises a single crystal silicon substrate having a Si (100) surface on a Si single crystal substrate, and a metal selected from the group consisting of Pt, Ir, Os, Re, Pd, Rh and Ru. And an oriented thin film having a single c-plane or a-plane orientation parallel to the substrate, which is formed of at least one of the above or a conductive oxide.

An oxide thin film including at least one epitaxial thin film mainly composed of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) between the Si single crystal substrate and the oriented thin film. Is interposed.

The laminated thin film according to the sixth aspect of the present invention is obtained by forming Pt, Ir, Os, Re, and Pt on a Si single crystal substrate having a Si (100) plane on the surface.
An epitaxial film formed of at least one metal selected from Pd, Rh and Ru, or formed of a conductive oxide, and an oriented thin film formed of a perovskite-type or tungsten bronze-type material.

The perovskite type or tungsten bronze type material is preferably barium titanate, strontium titanate, PZT, PBN or SBN. Preferably, the oriented thin film is an epitaxial film.

The crystal axis orientation relationship between the Si substrate and the oriented thin film is perovskite or tungsten bronze [10
0] // Si [010].

At least an epitaxial thin film mainly composed of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) is provided between the Si single crystal substrate and the metal or conductive oxide thin film. An oxide thin film including one layer is interposed.

The crystal axis orientation relationship between the Si single crystal substrate, the metal or conductive oxide thin film and the oriented thin film is perovskite or tungsten bronze [100] // metal or conductive oxide [100] // Si [ 010]. The oxide thin film has a (001) orientation.

As described above, it is preferable that the laminated thin films of the first to sixth aspects have the following contents.

In each of the first to third and fifth to sixth aspects,
As in the fourth aspect, the oxide thin film is formed on a first epitaxial film mainly composed of zirconium oxide or zirconium oxide stabilized with a rare earth metal element (including Sc and Y) and on the first epitaxial film. It may be a two-layer or multilayer oxide thin film including at least a second epitaxial film made of a perovskite-type material.
Note that the perovskite-type material of the second epitaxial film is preferably formed using barium titanate, strontium titanate, or a solid solution thereof as a main component. In that case, the oriented thin film formed on the second epitaxial thin film of the oxide thin film is made of a material other than the second epitaxial film constituent material. The crystal orientation relationship between the perovskite-type material and the Si substrate is as follows:
00] // Si [010]. This perovskite / zirconium oxide or rare earth stabilized zirconium oxide-based film / Si structure further comprises an oriented thin film formed on the structure, for example, P
This is effective for improving the crystallinity of a ferroelectric such as ZT, SBN, and Bi layered compound, and the crystallinity of an electrode film such as Pt, and obtaining a c-plane single orientation or epitaxial film. Also, so-called metal-ferroelectric-insulator-semiconductor MFIS structure, metal-ferroelectric-metal-insulator-semiconductor MFMIS
Acts as a structural insulator.

The composition of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) in the oxide thin film is Zr _{1 -x} R _x O ₂ -δ (where R is a rare earth metal element). (Including Sc and Y), and x = 0 to 0.75 and δ = 0 to 0.5).

The half width of the rocking curve of the (002) reflection of the oxide thin film is preferably 1.5 ° or less. Here, the lower limit is generally about 0.7 ° at present, and particularly about 0.4 °.

At least 80%, preferably at least 90%, more preferably at least 95% of the surface of the oxide thin film has a ten-point average roughness Rz at a reference length of 500 nm of preferably 2 nm or less, more preferably 0 nm or less. 0.8 nm or less, more preferably 0.5 nm or less.

The basic structure of the laminated thin film of the present invention includes an oxide thin film formed on a semiconductor single crystal substrate when necessary, and an oriented thin film formed on the oxide thin film. Here, at least one layer in the oxide thin film has a composition Zr
_1-x RxO _2- δ (where R is a rare earth metal element (including Sc and Y), X = 0 to 0.75, δ = 0 to 0.5), and an epitaxial film of In addition, an oriented thin film having a crystal structure of a perovskite structure and a composition of BaTiO ₃ or the like is sequentially laminated, and these plane orientation relations are BaTiO ₃ (001) /
/ Zr _1-x RxO _2- δ (001) // Si (100)
It is preferable to have a structure of BaTiO ₃ [100] // Zr _{1 -x} RxO _2- δ [100] // Si [010].

By analogy with a conventional example such as YBCO, (001)
In order to obtain an oriented BaTiO ₃ epitaxial film, the plane orientation relationship is BaTiO ₃ (001) // Zr _1-x RxO _2- δ (001) // Si (10
0), and BaTiO ₃ [110] // Zr _1-x RxO _2- δ [100] // Si [010], and the unit cell of BaTiO _{3 is based on} the lattice of Zr _1-x RxO _2- δ It is presumed that the crystal is rotated by 45 ° in the c-plane to achieve lattice matching and epitaxial growth. However, according to the experiments of the inventors, such a surface relationship is difficult to configure, and BaTiO ₃ (0
01) // Zr _1-x RxO _2- δ (001) // Si (100) and BaTiO ₃ [100] /
/ Zr _1-x RxO _2- δ [100] // Si [010].

That is, although the lattice constant of the a-axis of the Zr _{1 -x} RxO ₂ -δ film is 0.52 and the a-axis of BaTiO ₃ is 0.40, the BaTiO ₃ [110] which rotates in the 45 ° plane and lattice-matches. ] // Zr _1-x RxO _2- δ
The misfit is 8.4% for the relationship [100] // Si [010].
However, the lattice matching BaTiO ₃ [100] // Zr according to the present invention is used.
_{In 1-x} RxO ₂ -δ [100] // Si [010], the a-plane of BaTiO ₃ crystal and Z
The r _1-x RxO _2- δ crystal a-plane does not rotate and matches as it is. At this time, the Zr _1-x RxO ₂ -δ 3 lattice (0.52 × 3 = 1.56 nm) is compared with the BaTiO ₃ 4 lattice (0 4 × 4 = 1.60 nm). At this time, the misfit matches well with 2.6%. Therefore, in the present invention, BaTiO ₃ [100] // Zr _1-x RxO _2- δ [100] /
By utilizing the relationship of / Si [010], an epitaxial BaTiO ₃ film of (001) orientation can be obtained.

The oxide thin film desirably has a single crystal orientation. This is because a grain boundary exists in a thin film having a plurality of crystal planes, so that epitaxial growth of an oriented thin film thereon becomes impossible.

The oxide thin film has an orientation thin film Ba
In order to form a TiO ₃ film or the like, the higher the crystallinity of the oxide thin film, the better, and the surface property is desirably flat at the molecular level. Conventional YSZ
Membrane, e.g., Appl. Phys. Lett. 57 (11) 1161-1163 (199
0), Japanese Journal of Applied Physics, vol. 27, No.
4, L1404 (1988) does not realize excellent flatness and is not suitable for forming a high-quality oriented thin film thereon. In the present invention, an oxide thin film having excellent crystallinity and surface properties can be obtained by a method described later, and a high-quality oriented thin film can be formed thereon.

The crystallinity of the oxide thin film can be evaluated by the half width of the rocking curve of the reflection peak in XRD (X-ray diffraction) and the image pattern by RHEED. In addition, the surface property is the streak property of the RHEED image,
And the surface roughness (ten-point average roughness Rz).

The half width of the rocking curve of reflection on the (002) plane and the flatness of the surface of the oxide thin film of the present invention are as described above. The RHEED image of the oxide thin film has a high streak property. That is, the RHEED image is streak and sharp.

As described above, the oxide thin film of the present invention has good crystallinity and good surface properties. There is no particular lower limit for the half width of the rocking curve and the ten-point average roughness Rz at a reference length of 500 nm, but the smaller the smaller, the better. At present, the lower limit is such that the half width of the rocking curve is as described above, and the ten-average point roughness Rz is about 0.1 nm.

The epitaxial film mainly composed of zirconium oxide or zirconium oxide stabilized with a rare earth metal element (including Sc and Y) as an oxide thin film has a composition of substantially ZrO ₂ or rare earth ( Stabilized zirconia to which Sc and Y are added) is preferred. The added rare earth elements used in the stabilized zirconia are Y, Pr, Ce, Nd, Gd, Tb, Dy, H
o and Er are preferred.

Rare earth metal elements (including Sc and Y)
Is, to preferably match the lattice constant of the Si substrate and the lattice constant of the oriented thin film with the lattice constant of the oxide thin film,
The type is selected. For example, rare earth metal elements (Sc
Z _0.7 R _0.3 O _2- δ using Y as
Had a lattice constant of 0.52 nm. This value can be changed by the value of x. For example, as described above,
The four lattices of the TiO ₃ crystal are matched with the three lattices of the Zr _{1 -x} R _x O ₂ -δ crystal, and can be adjusted by the value of x.

However, there is a limit when the adjustable region of matching is within the range of x. Therefore, matching can be made possible by changing the type of rare earth. For example, rare earth Pr is used instead of Y. At this time Zr _1-x R _x O _2- lattice constant of δ can be increased, it is possible to optimize the matching with BaTiO ₃ crystals. By selecting the kind and amount of the rare earth element in the oxide thin film in this way, it is possible to preferably match the lattice of the oxide thin film with the lattice of the oriented thin film.

ZrO ₂ is cubic from high temperature to room temperature.
A phase transition occurs from tetragonal to monoclinic. Stabilized zirconia is obtained by adding a rare earth element to stabilize a cubic crystal. The crystallinity of the Zr _{1 -x} R _x O ₂ -δ film depends on the range of x. Jpn. J. Appl. Phys. 27 (8) L1404-L1405 (1
As reported in 988), in the composition range where x is less than 0.2, the crystal becomes tetragonal or monoclinic. Until now,
An epitaxial film having a single orientation was obtained only in the cubic region where x was 0.2 or more. However, in the region where x exceeds 0.75, although it is cubic, for example, a (001) single orientation cannot be obtained, and a (111) oriented crystal is mixed. On the other hand, in the tetragonal or monoclinic region, J. Appl.
As described in s. 58 (6) 2407-2409 (1985), an orientation plane other than the one to be obtained is mixed, and a single orientation epitaxial film has not been obtained.

In our experiments, in the region where x exceeds 0.75, cubic crystals were mixed, but planes other than the target crystal planes were mixed. For example, when an attempt is made to obtain a (001) epitaxial film of Zr _{1 -x} R _x O ₂ -δ, x is (11) in this range.
The crystal of 1) was mixed, and the surface unevenness of the film was increased to about 5 nm. As x increases, the surface properties tend to deteriorate. Then, when a BaTiO ₃ film was formed thereon, a (001) single orientation could not be obtained. In the present specification, the cubic crystal a
Even in the case of plane orientation, (001) orientation may be displayed.

Based on such an experiment, Zr _{1 -x} R _x O
The upper limit of x in _2- δ is preferably 0.75, more preferably 0.50. In order to obtain a flatter surface, x is preferably 0.25 or less, more preferably 0.10 or less.

Incidentally, zirconium oxide containing no oxygen defect can be represented by the chemical formula ZrO ₂ , but zirconium oxide to which rare earth is added changes the amount of oxygen depending on the kind, amount and valence of the added metal element. The composition of the oxide thin film of the present invention was expressed using the chemical formulas Zr _{1 -x} R _x O ₂ -δ and δ. δ is usually about 0 to 0.5.

In the oxide thin film containing Zr, the ratio of Zr in the constituent elements excluding oxygen is preferably at least 93 mol%, more preferably more than 93 mol%, further preferably at least 95 mol%, particularly preferably at least 98 mol%. Most preferably 9
9.5 mol% or more. The higher the purity, the higher the insulation resistance and the smaller the leakage current, so that it is preferable as an intermediate layer requiring insulation properties. ZrO ₂
When a metal-insulator-semiconductor structure (MIS structure) is configured as compared with YSZ, the CV characteristics have small hysteresis and the MIS device has excellent interface characteristics.
Particularly, ZrO ₂ is preferable as the intermediate layer. The upper limit of the Zr content is 99.99% at present. Elements other than Zr and O in the oxide thin film containing Zr are rare earth metals, impurities such as P, and the like. The oxide intermediate layer preferably has excellent crystallinity and surface flatness.

In particular, when the oxide thin film has the above-mentioned x
Is less than 0.2, particularly high-purity Zr in which the ratio of Zr in constituent elements excluding oxygen is 93 mol% or more as described above.
In the case of an O ₂ epitaxial film, it is preferably a single orientation epitaxial film. Although _{Zr 1-x R x O 2-} δ in x epitaxial film in the range of 0.2 to 0.75 have stated that conventionally obtained, to date, the high purity ZrO ₂ as described above, A thin film having the above-mentioned crystallinity and surface properties in a single orientation was not obtained.

However, as a result of repeated studies by the present inventors, the formation of the high-purity ZrO ₂ by the method described later
Was used to obtain a thin film having the above-mentioned crystallinity and surface properties in a single orientation. In this composition, the effect of reducing the residual stress, which seems to be based on the difference in the thermal expansion coefficient from the Si substrate, was confirmed. This effect is remarkable as the purity of ZrO ₂ is increased. Therefore, it is considered that the residual stress with Si is reduced by the phase transition of ZrO ₂ . Also, YSZ
A zirconium oxide thin film with higher purity than a film has a higher film resistance and is excellent as an insulating film.

The higher the purity of the zirconium oxide thin film, the better the insulating properties and the lower the residual stress.

Further, since it is difficult to separate ZrO ₂ and HfO ₂ by the current high-purity technology, the purity of ZrO ₂ usually indicates the purity of Zr + Hf. Therefore, the purity of ZrO ₂ in the present specification is a value calculated by assuming that Hf and Zr are the same element, but there is no problem since HfO ₂ functions in the present invention in exactly the same manner as ZrO ₂ . A high-purity zirconium oxide thin film is made of cubic (10
Although any of 0) orientation, tetragonal (001) orientation and monoclinic (001) orientation may be used, monoclinic (001) orientation is particularly preferred.

When the compositional Zr _{1 -x} R _x O ₂ -δ epitaxial film described above is used as the oxide thin film of the laminated thin film of the present invention, the physical quantity is not disturbed by the grain boundaries, and the oxide film is formed thereon. The crystallinity of the oriented thin film such as the BaTiO ₃ film as the oriented thin film is improved. It is difficult to obtain a single-oriented epitaxial film, for example, a (001) -oriented thin film of BaTiO ₃ on an oxide thin film having poor surface properties and poor crystallinity. As described above, the (110) orientation planes are mixed and the (110) orientation grows preferentially. Surface properties, providing an oxide thin film with excellent crystallinity, and, depending on the growth conditions of the oriented thin film described below,
A (001) oriented epitaxial perovskite thin film is obtained. When a high-quality epitaxial perovskite thin film is obtained on the epitaxial oxide thin film, another high-quality perovskite crystal film, tungsten bronze crystal film, or metal crystal film is obtained thereon. In this case, the composition Zr
_The entire two-layer structure of the first epitaxial film of _1-x R _x O ₂ -δ and the second epitaxial film composed of perovskite, preferably BaTiO ₃ , SrTiO ₃ or a solid solution thereof, is an oxide thin film ( (Underlayer), on which a high-quality alignment film, that is, another perovskite film, tungsten bronze film, or metal film having good orientation can be obtained.

The thickness of the oxide thin film and the thickness of the oriented thin film vary depending on the application.
Is preferably about 2 to 50 nm, the thickness of the oriented thin film (second epitaxial film) is about 1 to 50 nm, and the total is about 3 to 100 nm. When only the oxide thin film containing Zr is used as the underlayer, the thickness of the oxide thin film containing Zr is preferably 2 nm or more, more preferably 10 nm or more, preferably 200 nm or less, more preferably 100 nm or less. When an oriented thin film of perovskite or tungsten bronze is used as the ferroelectric layer, the thickness is about 20 to 1000 nm.

When the above two-layer structure is used as an underlayer, Z
Both the oxide thin film containing r and the perovskite alignment thin film are preferably thin. When used as an insulating layer having an MFIS or MFMIS structure, an oxide thin film having ZrO ₂ as a main component is particularly excellent in insulating properties. Also, MIS
When used as an oxide layer of a semiconductor device such as a dielectric layer of a capacitor or a gate oxide layer of a MISFET, the oxide thin film is made as thin as 0.5 to 20 nm, particularly 1 to 10 nm, and the oriented thin film is made as thin as 5 to 10 nm. It is preferable to set it to 300 nm. This is to increase the capacitance of the laminated thin film as a capacitor.

An oxide thin film having a structure in which a rare earth oxide-based thin film described below is laminated on the above-described zirconium oxide-based thin film may be used. In this case, the oriented thin film is formed on the rare earth oxide thin film. In the underlayer having a configuration in which the first and second epitaxial films are stacked, a stacked body of a zirconium oxide-based thin film and a rare earth oxide-based thin film is considered as the first epitaxial film. The preferred range of the thickness of the laminate is the same as the thickness range of the zirconium oxide-based thin film when the rare-earth oxide-based thin film is not provided. In this laminate, both the thin films preferably have a thickness not less than 0.5 nm.

This rare earth oxide thin film is made of Y, La, C
e, Pr, Nd, Sm, Eu, Gd, Tb, Dy, H
being substantially composed of a rare earth oxide containing at least one of o, Er, Tm, Yb and Lu, especially at least one of Ce, Pr, Nd, Gd, Tb, Dy, Ho and Er Is preferred. When two or more rare earth elements are used, the ratio is arbitrary.

When such a rare-earth oxide-based thin film is formed directly on a substrate, the thin film (11)
1) Although showing an orientation, a rare earth oxide-based thin film of (001) orientation can be obtained by forming it on a zirconium oxide-based thin film of (001) orientation. When the above-mentioned stabilized zirconia is used as the oxide thin film, hysteresis is observed in the CV characteristics, and this point is inferior to the ZrO ₂ high-purity film. In this case, by laminating the rare earth oxide-based thin film on the zirconium oxide-based thin film, it is possible to eliminate the hysteresis of the CV characteristic. Further, by stacking the rare earth oxide-based thin films, the matching of the lattice matching with the ferroelectric layer is further improved. When the rare earth oxide based thin film is laminated, the zirconium oxide based thin film is
The film may have a uniform element distribution, or may have a gradient structure in which the composition changes in the film thickness direction. When the film has a gradient structure, the content of the rare earth element in the zirconium oxide-based thin film is gradually or gradually increased from the substrate side to the rare earth oxide-based thin film, and the Zr content is gradually or gradually reduced. With such a graded structure film, the lattice misfit between the zirconium oxide-based thin film and the rare earth oxide-based thin film is reduced or absent, and the rare-earth oxide-based thin film is formed into a highly crystalline epitaxial film. It becomes easy to form a film. In the case of such a laminated structure, it is preferable to use the same rare earth element added to the rare earth oxide-based thin film as the rare earth element added to the zirconium oxide-based thin film.

An additive may be introduced into the zirconium oxide-based thin film and the rare earth oxide-based thin film for improving the characteristics. For example, when these layers are doped with an alkaline earth element such as Ca or Mg, the number of pinholes in the film decreases,
Leakage can be suppressed. Al and Si
Has the effect of improving the resistivity of the film. Further, M
Transition metal elements such as n, Fe, Co, and Ni can form a level (trap level) due to impurities in the film, and conductivity can be controlled by using this level.

In the laminated thin film of the present invention, the substrate surface of the Si single crystal substrate, that is, the surface on which the insulating layer is formed may be oxidized shallowly (eg, about 5 nm or less) to form a layer such as SiO ₂ . This is because oxygen in the oxide thin film containing ZrO ₂ as a main component sometimes diffuses to the substrate surface of the Si single crystal substrate. Further, depending on the method of film formation, the Si oxide layer may remain on the surface of the Si substrate when forming the oxide thin film.

The oxide thin film composed of the first and second epitaxial films is used as a base layer, and the oriented thin film formed thereon is made of a perovskite other than the perovskite constituting the second epitaxial film, for example, PbTiO.
₃ , simple perovskites such as PZT, PLZT, and other Pb-based perovskites; layered perovskites (K ₂ N)
complex perovskite containing containing iF ₄ inch), such as B
i-based perovskite; (Sr, Ba) Nb ₂ O ₆ ,
(Pb, Ba) Tungsten bronze-type oxide such as Nb ₂ O ₆ or the like, for example, a ferroelectric (F) having an MFIS structure. In addition, specifically, as the alignment thin film formed on the underlayer having the two-layer structure, specifically,
Bi-based oxide superconducting film, YBa ₂ Cu ₃ O _7-8 (YBC
O) High-temperature superconducting films such as superconducting films, and La _1-x S
oxide conductive films such as r _x CoO ₃ and La _1-x Sr _x Ca _x RuO ₃ , In ₂ O ₃ , In ₂ O ₃ (Sn doped), other oxide conductive films, Pt, Si, Ge, GaAs, etc. Semiconductor and metal films. The conductive oxide film will be further described later.

As described above, the oxide thin film having a one-layer structure or a multilayer structure according to the present invention can be used as a metal-ferroelectric-insulator-semiconductor MFIS structure or a metal-ferroelectric-metal-insulator-
It is suitable for an insulator having a semiconductor MFMIS structure. MFI
In the S structure, a single-layer or multi-layer oxide thin film may be provided on a semiconductor, preferably a Si (100) surface, and the dielectric thin film of the present invention or another ferroelectric thin film may be provided thereon.

On the other hand, in the MFMIS structure, S
On the i (100) plane, an oxide thin film preferably having a two-layer structure is provided as an insulating layer (I), and a conductive epitaxial film is formed thereon as a metal electrode film. A body thin film is provided.

The metal electrode thin film is used as an electrode for a ferroelectric thin film and a conductive thin film necessary for forming an MFMIS structure required for memory application of the ferroelectric thin film.
That is, for example, Pt, Ir, Os, Re, Pd, R
An epitaxial film formed of at least one kind of metal selected from h and Ru and having a unidirectional tetragonal (001) or cubic (100) orientation is formed in parallel with the substrate surface, and is used as a metal electrode thin film. .

The electrode thin film is preferably made of a metal, but may be made of a conductive epitaxial film even if it is not a metal. The conductive epitaxial film functions as an electrode on the lower side of the ferroelectric layer, and a ferroelectric layer having good lattice matching with the intermediate layer and high crystallinity can be obtained.

The metal electrode thin film is made of Pt, Ir, Os, R
A simple metal or an alloy containing at least one of e, Pd, Rh and Ru is preferred. The conductive oxide film as the conductive epitaxial film preferably contains the following conductive oxide.

NaCl type oxide: TiO, VO, NbO, RO
_1-x (where, R: one or more rare earth elements (including Sc and Y), 0 ≦ x <1), LiVO _{2 and the} like.

Spinel type oxide: LiTi ₂ O ₄ , LiM _x T i _2-x
O ₄ (where M = Li, Al, Cr, 0 <x <2), Li _1-x M _x Ti ₂ O ₄
(Where M = Mg, Mn, 0 <x <1), LiV ₂ O ₄ , Fe ₃ O ₄ , etc.

Perovskite oxide: ReO ₃ , WO ₃ , Mx
ReO ₃ (where M metal, 0 <x <0.5), MxWO ₃ (where
M = metal, 0 <x <0.5), A ₂ P ₈ W ₃₂ O ₁₁₂ (where A = K, Rb,
Tl), Na _x Ta _y W _1-y O ₃ (where 0 ≤ x <1, 0 <y <1),
RNbO ₃ (where R: one or more rare earth elements (including Sc and Y)), Na _1-x Sr _x NbO ₃ (where 0 ≦ x ≦ 1), RTiO ₃ (
Here, R: one or more kinds of rare earths (including Sc and Y)), Ca _{n + 1} T _n O _{3n + 1-y} (where n = 2,3, ..., y> 0),
CaVO ₃ , SrVO ₃ , R _1-x Sr _x VO ₃ (where R: one or more rare earth elements (including Sc and Y), 0 ≦ x ≦ 1), R _1-x Ba _x
VO ₃ (where R: one or more rare earth elements (including Sc and Y), 0 ≦ x ≦ 1), Sr _{n + 1} V _n O _{3n + 1-y} (where n = 1,2,
3 ...., y> 0), Ba _{n + 1} V _n O _{3n + 1-y} (where n = 1,2,3
...., y> 0), R ₄ BaCu ₅ O _13-y (where R: one or more rare earth elements (including Sc and Y), 0 ≦ y), R ₅ SrCu ₆ O
₁₅ (where R: one or more rare earths (including Sc and Y)), R ₂ SrCu ₂ O _6.2 (where R: one or more rare earths (including Sc and Y)), R _{1- x} Sr _x VO ₃ (where R: one or more rare earths (including Sc and Y)), CaCrO ₃ , SrCrO
₃ , RMnO ₃ (where R: one or more rare earths (Sc and
Y ₁ ), R _1-x Sr _x MnO ₃ (where R: one or more rare earth elements (including Sc and Y), 0 ≦ x ≦ 1), R _1-x Ba _x Mn
O ₃ (where, R: one or more rare earths (including Sc and Y), 0 ≦ x ≦ 1), Ca _1-x R _x MnO _3-y (where, R: one or more rare earths ( Sc and Y), 0 ≤ x ≤ 1, 0
≦ y), CaFeO ₃ , SrFeO ₃ , BaFeO ₃ , SrCoO ₃ , BaCoO ₃ , RCoO
₃ (where R: one or more rare earths (including Sc and Y)), R _1-x Sr _x CoO ₃ (where R: one or more rare earths (including Sc and Y), 0 ≦ x ≦ 1), R _1-x Ba _x CoO ₃ (where R: one or more rare earth elements (including Sc and Y),
0 ≦ x ≦ 1), RNiO ₃ (where R: one or more rare earths (including Sc and Y)), RCuO ₃ (where R: one or more rare earths (including Sc and Y)) , RNbO ₃ (where
R: one or more rare earths (including Sc and Y)), Nb ₁₂ O
₂₉ , CaRuO ₃ , Ca _1-x R _x Ru _1-y Mny _{y 3} (where R: one or more rare earth elements (including Sc and Y), 0 ≦ x ≦ 1, 0 ≦ y
≦ 1), SrRuO ₃ , Ca _1-x Mg _x RuO ₃ (where 0 ≦ x ≦ 1),
Ca _1-x Sr _x RuO ₃ (where 0 <x <1), BaRuO ₃ , Ca _{1- x} Ba _x
RuO ₃ (where 0 <x <1), (Ba, Sr) RuO ₃ , Ba _1-x K _x Ru
O ₃ (where 0 <x ≦ 1), (R, Na) RuO ₃ (where R:
One or more rare earths (including Sc and Y)), (R, M) RhO ₃
(Where, R: at least one kind of rare earth (including Sc and Y), M = Ca, Sr, Ba), SrIrO ₃ , BaPbO ₃ , (Ba, Sr) PbO _3-y
(Where 0 ≤ y <1), BaPb _1-x Bi _x O ₃ (where 0 <x
≤ 1), Ba _1-x K _x BiO ₃ (where 0 <x ≤ 1), Sr (Pb, Sb) O
_3-y (where 0 ≤ y <1), Sr (Pb, Bi) O _3-y (where 0
≤y <1), Ba (Pb, Sb) O _3-y (where 0 ≤y <1), Ba
(Pb, Bi) O _3-y (where 0 ≤ y <1), MMoO ₃ (where M =
(Ca, Sr, Ba), (Ba, Ca, Sr) TiO _3-x (where 0 ≤x),
etc.

Layered perovskite type oxide (including K ₂ NiF ₄ type): at least one of R _{n + 1} Ni _n O _{3n + 1} (where R: Ba, Sr, rare earth (including Sc and Y)) , n = 1 to 5), R _{n + 1} Cu _n O _{3n + 1} (where R: Ba, Sr, rare earth (Sc
And Y), n = 1 to 5), Sr ₂ RuO ₄ , Sr ₂ RhO ₄ , Ba ₂ RuO ₄ , Ba ₂ RhO ₄ , and the like.

Pyrochlore type oxide: R ₂ V ₂ O _7-y (where R: one or more rare earth elements (including Sc and Y), 0
≤y <1), Tl ₂ Mn ₂ O _7-y (where 0 ≤y <1), R ₂ Mo ₂ O
_7-y (where R: one or more rare earth elements (including Sc and Y), 0 ≦ y <1), R ₂ Ru ₂ O _7-y (where R: Tl, Pb, B
i, one or more of rare earth elements (including Sc and Y), 0
≤y <1), Bi _2-x Pb _x Pt _2-x Ru _x O _7-y (where 0 ≤x ≤2,
0 ≦ y <1), Pb ₂ (Ru, Pb) O _{7- y} (where 0 ≦ y <1), R ₂ R
h ₂ O _7-y (where, at least one of R: Tl, Pb, Bi, Cd, rare earth (including Sc and Y), 0 ≦ y <1), R ₂ Pd ₂ O
_7-y (where R: Tl, Pb, Bi, Cd, rare earth (Sc and Y
At least one of the following: 0 ≦ y <1), R ₂ Re ₂ O _7-y (where R: one of the following: Tl, Pb, Bi, Cd, rare earth (including Sc and Y) 0 ≦ y <1), R ₂ Os ₂ O _7-y (where R: Tl, Pb, Bi, Cd, rare earth (including Sc and Y))
One or more of them, 0 ≦ y <1), R ₂ Ir ₂ O _7-y (where
R: at least one of Tl, Pb, Bi, Cd, rare earth (including Sc and Y), 0 ≦ y <1), R ₂ Pt ₂ O _7-y (where R: T
One or more of l, Pb, Bi, Cd, and rare earths (including Sc and Y), 0 ≦ y <1).

Other oxides: R ₄ Re ₆ O ₁₉ (where R:
One or more rare earths (including Sc and Y)), R ₄ Ru ₆ O
₁₉ (where, R: one or more rare earths (including Sc and Y)), Bi ₃ Ru ₃ O ₁₁ , V ₂ O ₃ , Ti ₂ O ₃ , Rh ₂ O ₃ , VO ₂ , CrO ₂ , N
bO ₂ , MoO ₂ , WO ₂ , ReO ₂ , RuO ₂ , RhO ₂ , OsO ₂ , IrO ₂ , Pt
O ₂ , PdO ₂ , V ₃ O ₅ , V _n O _2n-1 (n = integer from 4 to 9), SnO
_2-x (where 0 ≤ x <1), La ₂ Mo ₂ O ₇ , (M, Mo) O (where M = Na, K, Rb, Tl), Mo _n O _3n-1 (n = 4, 8, 9, 10), Mo
₁₇ O ₄₇ , Pd _1-x Li _x O (where x ≦ 0.1) and the like. An oxide containing In.

Of these, oxides containing In or conductive perovskite oxides are particularly preferable, and In ₂
O ₃ , In ₂ O ₃ (Sn doped), RCoO ₃ , RMn
O ₃ , RNiO ₃ , R ₂ CuO ₄ , (R, Sr) CoO ₃
, (R, Sr, Ca) RuO ₃ , (R, Sr) RuO ₃
, SrRuO ₃ , (R, Sr) MnO ₃ (R is a rare earth containing Y and Sc), and their related compounds are preferred. The conductive metal or metal oxide preferably has a bulk resistivity of 10 ⁻⁵ to 10 ⁻² Ωcm.
Further, the specific resistance as a thin film is preferably 10 ^-5 to 10 ^-2 Ωcm. Also, a superconducting material may be used.

These conductive epitaxial thin films not only function as electrodes, but also preferably match the lattice constant of the ferroelectric layer formed on the conductive epitaxial thin film with its own lattice constant, and have high crystallinity. It plays a role in forming a ferroelectric layer. For this reason, the metal electrode thin film or the conductive oxide film preferably has excellent crystallinity and surface flatness. Metal electrode thin films or conductive oxide films are cubic (100), tetragonal (001), and orthorhombic (0).
01) or monoclinic (001) oriented crystals,
In particular, it is preferable that these films have a single orientation and further be an epitaxial film.

Although the thickness of the conductive epitaxial film varies depending on the application, it is 5 to 500 nm, preferably 5 to 500 nm as described above.
It is preferably about 0 to 150 nm. The conductive epitaxial film is preferably as thin as not to impair the crystallinity and surface properties.
In particular, when the conductive epitaxial film functions as an electrode, the thickness is preferably about 50 to 500 nm.

In any case, it is not necessary to use the first and second epitaxial films as the underlayer, and there are materials which can be epitaxially grown on the underlayer of only the first epitaxial film. Is used as the underlayer, the underlayer has a perovskite structure, so that a higher quality alignment film can be obtained thereon.

The electronic device substrate of the present invention can have a large-area substrate having the uniform laminated thin film, for example, a substrate area of 10 cm ² or more. As a result, not only the substrate but also the electronic devices manufactured using the substrate are extremely inexpensive as compared with the related art. Although there is no particular upper limit on the area of the substrate, a semiconductor process using a Si wafer of 2 inches to 8 inches, particularly a 6-inch type, is currently mainstream and can cope with this. Even if it is not on the entire surface of the Si wafer, but within a 2 to 8 inch substrate, it is also possible to obtain a laminated thin film by partially selecting it with a mask or the like.

Next, the method for forming an oxide thin film of the present invention will be described in detail.

In carrying out the forming method of the present invention, it is desirable to use a vapor deposition apparatus 1 as shown in FIG.

The vapor deposition apparatus 1 has a vacuum chamber 1a, in which a holder 3 for holding a single crystal substrate 2 is disposed at a lower portion. The holder 3 is connected to a motor 5 via a rotation shaft 4 and is rotated by the motor 5 so that the single crystal substrate 2 can be rotated in the substrate plane. In the holder 3,
A heater 6 for heating the single crystal substrate 2 is incorporated.

The vapor deposition device 1 also has an oxidizing gas supply device 7, and the oxidizing gas supply port 8 of the oxidizing gas supply device 7 is disposed immediately below the holder 3. Thus, the partial pressure of the oxidizing gas is increased near the single crystal substrate 2. Further below the holder 3, a Ba evaporator 9, a Ti evaporator 10, a Zr evaporator 1
1 and a rare earth metal element (including Sc and Y) evaporating section 12 are arranged. In these Ba evaporator 9, Ti evaporator 10, Zr evaporator 11, and rare earth metal element (including Sc and Y) evaporator 12, energy for evaporation is supplied to the metal sources in addition to the respective metal sources. An energy supply device (an electron beam generator, a resistance heating device, etc.) for supplying is provided. In the drawings, P is a vacuum pump.

In the method for forming a laminated thin film of the present invention,
First, a Si single crystal substrate is set on the holder. At this time, as the single crystal substrate, a single crystal substrate of Si is used, and as a substrate surface on which a target oxide thin film is formed,
The (100) plane is selected. This is because the functional film formed on the substrate surface is made into a single crystal epitaxially grown, and the crystal is oriented in an appropriate direction. The substrate surface is
Preferably, the surface is etched and cleaned using a mirror-finished wafer. The etching cleaning is performed using a 40% ammonium fluoride aqueous solution or the like.

On this substrate, the present applicant has already filed Japanese Patent Application No.
An epitaxial film containing ZrO ₂ as a main component is formed by a method proposed in US Pat.

In the method of forming an oxide thin film of the present invention, the method described in the above-mentioned patent application can be used. Hereinafter, a method of forming an oxide thin film will be described first, and then a method of forming an oriented thin film formed thereon will be described.

Here, a description will be given by taking a ZrO ₂ thin film as an oxide thin film and a BaTiO ₃ thin film as an alignment thin film as an example.

First, a method for forming an oxide thin film will be described. In this method, first, a single crystal substrate is set on the holder. Since the purified Si single crystal substrate is extremely reactive, the purpose is to protect it,
In order to grow a good epitaxial film containing ZrO ₂ as a main component, the surface of the Si single crystal substrate is subjected to a surface treatment as follows.

First, a Si single crystal substrate whose surface has been cleaned is placed in a vacuum chamber, and heated while introducing an oxidizing gas to form a Si oxide layer on the surface of the Si single crystal substrate. Oxidizing gases include oxygen, ozone, atomic oxygen,
NO ₂ or the like can be used. Since the surface of the cleaned Si single crystal substrate is extremely reactive as described above, it is used as a protective film to protect the surface of the Si single crystal substrate from rearrangement and contamination. The thickness of the Si oxide layer is preferably about 0.2 to 10 nm.
If the thickness is less than 0.2 nm, the protection of the Si surface is incomplete. The reason for setting the upper limit to 10 nm will be described later.

The above-mentioned heating is carried out at a temperature of 300 to 700 ° C. for about 0 to 10 minutes. At this time, the heating rate is about 30 to 70 ° C./min. If the temperature is too high,
If the rate of temperature rise is too fast, the formation of the Si oxide film becomes insufficient, and if the temperature is too low or the holding time is too long,
The Si oxide film is too thick.

For example, when oxygen is used as the oxidizing gas, the oxidizing gas is initially introduced into the vacuum chamber at 1 × 10 ⁻⁷ to 1 × 10 ^−7.
It is preferable that a vacuum of about × 10 ⁻⁴ Torr is provided, and the oxygen partial pressure of the atmosphere at least in the vicinity of the Si single crystal substrate is about 1 × 10 ⁻⁴ Torr or more by introducing an oxidizing gas. Although the upper limit of the oxygen partial pressure in the case of processing in a vacuum chamber is about 1 × 10 ⁻¹ Torr, a Si oxide film may be formed by heating in air and thermally oxidizing.

After the above steps, heating is performed in a vacuum. Since the Si surface crystal is protected by the protective film, there is no contamination such as formation of a SiC film by reacting with hydrocarbons as residual gas.

The heating temperature is 600 to 1200 ° C., especially 7
The temperature is preferably set to 00 to 1100 ° C. If the temperature is lower than 600 ° C., a 1 × 1 structure described later cannot be obtained on the surface of the Si single crystal substrate. If the temperature exceeds 1200 ° C., Si
The protection of the surface crystal is not sufficient, and the crystallinity of the Si single crystal substrate is disturbed.

While such heating is performed, Zr and an oxidizing gas or Zr, a rare earth metal and an oxidizing gas are supplied to the surface. In this process, the metal such as Zr reduces and removes the protective film made of the Si oxide formed in the previous step. At the same time, a 1 × 1 surface structure is formed on the exposed Si surface crystal surface by Zr and oxygen or Zr, a rare earth metal element and oxygen. At this time, it is preferable that the oxygen partial pressure of the atmosphere in the vicinity of the Si single crystal substrate be 1 × 10 ⁻⁴ Torr or more and about 1 × 10 ⁻¹ Torr or less.

The surface structure can be examined by an RHEED image pattern. For example, in the case of a 1 × 1 surface structure aimed at by the present invention, the electron beam incident direction is [110].
2A, a complete streak pattern with a one-time period C1 as shown in FIG. 2A is obtained, and the same pattern is obtained even when the incident direction is [1-10]. On the other hand, the clean Si single crystal surface has a surface structure of, for example, 1 × 2, 2 × 1, or a mixture of 1 × 2 and 2 × 1 in the case of a (100) plane. In such a case, the pattern of the RHEED image has a one-time period C1 as shown in FIG. 2B in one or both of the electron beam incident directions [110] and [1-10].
And a pattern having a double cycle C2. 1 × 1 of the present invention
In the surface structure of No. 2, when viewed from the above RHEED pattern, when the incident direction is both [110] and [1-10], the double cycle C2 of FIG. 2B is not observed.

The clean Si (100) surface may have a 1 × 1 structure in some cases. Although it was observed several times in our experiments, the condition showing 1 × 1 is unclear, and it is impossible at present to obtain 1 × 1 stably and reproducibly on a Si-clean surface.

S of any structure of 1 × 2, 2 × 1, 1 × 1
The i-clean surface is easily contaminated at high temperatures in a vacuum, and reacts particularly with hydrocarbons contained in the residual gas to form SiC on the surface, and the crystal on the substrate surface is disturbed. Therefore, it has not been possible to stably form a 1 × 1 structure suitable for crystal growth of an oxide film on a Si substrate.

The supply amount of Zr or Zr and the rare earth metal is 0.3 to 10 nm, particularly 3 to 7 nm in terms of oxide.
The degree is preferred. If it is less than 0.3 nm, the effect of reducing the Si oxide cannot be sufficiently exerted, and if it exceeds 10 nm, irregularities at the atomic level are likely to be generated on the surface. This is because it may not be. The reason why the preferable upper limit of the thickness of the Si oxide layer is set to 10 nm is that if the thickness exceeds 10 nm, the Si oxide layer may not be sufficiently reduced even if the metal is supplied as described above. Because it comes out.

When oxygen is used as the oxidizing gas, 2
It is preferable to supply about 50 cc / min. The optimum amount of oxygen is determined by the size of the vacuum chamber, the pumping speed of the pump, and other factors, and the optimum flow rate is determined in advance.

The reason for performing the above-mentioned Si substrate surface treatment is as follows.

The surface structure in several atomic layers on the crystal surface is as follows:
This is generally different from a virtual surface atomic arrangement structure that can be considered when a bulk (three-dimensional large crystal) crystal structure is cut. This is because the disappearance of the crystal on one side changes the situation around the atoms that have appeared on the surface, and correspondingly tries to become a stable state with lower energy. The structural change mainly includes a case where the atomic position is merely relaxed and a case where the rearrangement of atoms occurs to form a rearranged structure. The former is present on most crystal surfaces. The latter generally form a superlattice structure on the surface. When the magnitudes of the unit vectors of the bulk surface structure are a and b, a superlattice structure having a magnitude of ma and nb is called an m × n structure. The surface of the cleaned Si (100) has a 1 × 2 or 2 × 1 structure, and the Si (111) surface has a complex superstructure having a large unit mesh of a 7 × 7 or 2 × 8 structure. In addition, these purified S
The i-surface is highly reactive, and reacts particularly with a residual gas in a vacuum, especially a hydrocarbon, at a temperature (700 ° C. or higher) at which an oxide thin film is epitaxially formed, and the Si surface is formed on the surface.
The formation of C contaminates the substrate surface and disturbs surface crystals.

In order to epitaxially grow an oxide on a Si substrate, the structure of the Si surface must be stable and play a role of transmitting crystal structure information to the grown oxide film. In the oxide epitaxial film crystal,
Since the atomic arrangement structure considered when cutting the bulk crystal structure is a 1 × 1 structure, the surface structure of the substrate for epitaxially growing an oxide is 1 × 2, 2 × 1, 7
Complex superstructures with large unit meshes of × 7 or 2 × 8 structures are not preferred and require a stable 1 × 1 structure. In addition, since the epitaxial growth is performed at a temperature of 700 ° C. or more, it is necessary to protect the reactive Si surface.

Next, as described above, the surface treated S
A single-oriented epitaxial film containing ZrO ₂ as a main component is formed using an i-single-crystal substrate.

In forming a single-oriented epitaxial film containing ZrO ₂ as a main component, first, a Si single crystal substrate whose surface has been treated is heated. The heating temperature at the time of film formation is desirably 400 ° C. or higher for crystallization of ZrO ₂ ,
Further, the crystallinity is excellent at about 750 ° C. or more, and particularly preferably 850 ° C. or more in order to obtain surface flatness at a molecular level. Note that the upper limit of the heating temperature of the single crystal substrate is 1300 ° C.
It is about.

Next, Zr is heated and evaporated by an electron beam or the like and supplied to the substrate surface, and an oxidizing gas and, if necessary, a rare earth element are supplied to the substrate surface to form a thin film containing ZrO ₂ as a main component. I do. The film formation rate is preferably set at 0.
01 nm / s or more, more preferably 0.03 nm / s or more, still more preferably 0.05 nm / s or more, and preferably 1.00 nm / s or less, more preferably 0.50 nm / s or less, and still more preferably Is 0.10 nm / s or less. If the film formation rate is too low, it is difficult to keep the film formation rate constant, while if the film formation rate is too high, the crystallinity of the formed thin film deteriorates, and the surface becomes uneven.

Therefore, prior to the deposition of the ZrO ₂ thin film,
A film installed near a substrate in a vacuum evaporation tank to determine how much the Zr metal and the rare earth metal element evaporate per unit time depending on the power amount condition applied to the evaporation source and form a metal and oxide evaporation film. Measure and calibrate with a thickness gauge. As the oxidizing gas, oxygen, ozone, atomic oxygen, NO ₂ or the like can be used. Here, description will be made on the assumption that oxygen is used. Oxygen is continuously evacuated from the chamber by a vacuum pump while continuously injecting oxygen gas at 2 to 50 cc / min, preferably 5 to 25 cc / min, by a nozzle provided in the vacuum evaporation tank. An oxygen atmosphere of about 10 ^-3 to 10 ^-1 Torr is formed at least in the vicinity of the single crystal substrate. The optimal oxygen amount is determined by the size of the chamber, the pumping speed of the pump, and other factors, and an appropriate flow rate is determined in advance. Here, the upper limit of the oxygen gas pressure is set to 10 ^-1 To
The reason for rr is to prevent the metal source in the evaporation source in the vacuum chamber from deteriorating and to vapor-deposit the evaporation source at a constant evaporation rate. Further, when introducing oxygen gas into the vacuum deposition tank, it is preferable to inject oxygen gas from the vicinity of the surface of the single crystal substrate to create an atmosphere with a high oxygen partial pressure only in the vicinity of the single crystal substrate. The reaction on the substrate can be further promoted by the amount introduced. At this time,
Since the inside of the vacuum chamber is continuously evacuated, most parts of the vacuum chamber have a low pressure of 10 ^-4 to 10 ^-6 Torr.

In a narrow region of about 1 cm ² of the single crystal substrate, the oxidation reaction can be promoted on the single crystal substrate by this method, but the substrate area is 10 cm ² or more, for example, a diameter of 2 cm 2.
Fig. 1
By rotating the substrate as described above and supplying a high oxygen partial pressure to the entire surface of the substrate, a large-area film can be formed. At this time, the rotation speed of the substrate is desirably 10 rpm or more. This is because if the number of rotations is low, a film thickness distribution occurs in the substrate surface. Although there is no particular upper limit on the number of rotations of the substrate, it is usually about 120 rpm due to the mechanism of the vacuum apparatus.

Further, the epitaxial film containing ZrO ₂ as a main component was used as a deposition substrate, and further, an alignment thin film of BaTiO _{3 was used.}
A method for forming a film, a SrTiO ₃ film or a solid solution film of BaTiO ₃ to obtain a laminated thin film will be described. Here, BaTiO ₃ will be described as an example. The deposition substrate on which the oxide thin film has been formed is placed in a vacuum chamber and heated. Continue heating while introducing oxidizing gas.

Next, Ba is heated with an electron beam or the like to evaporate. Ba metal and oxidizing gas are supplied to the single crystal substrate. At the same time, Ti is supplied in the same manner, and the supply amount is Ba: T
i = 1: 1 to obtain a BaTiO ₃ epitaxial thin film. Here, the temperature of the deposition substrate at the time of film formation and the supply ratio of Ba / Ti at the initial stage of film formation affect the orientation of the BaTiO ₃ film, and the plane orientation relationship of the BaTiO ₃ epitaxial crystal changes the BaTiO ₃ (0
01) // Zr _1-x RxO _2- δ (001) // Si (100) and BaTiO ₃ (10
0] // Zr _1-x RxO _2- δ [100] // Si [010], the heating temperature during the formation of BaTiO ₃ is 800 to 1300 ° C., preferably 900 to 1200 ° C. . The initial growth here is in the range of 0 to 1 nm in film thickness.

The supply ratio of Ba / Ti in the initial stage of growth is desirably 0 to 1, preferably 0 to 0.8 in molar ratio. Here, the reason why the Ba / Ti ratio is set to 0 means that only Ti may be supplied at the beginning of growth. The reason is that if the heating temperature is too low, or if the Ba / Ti ratio in the initial stage of growth is not appropriate, the BaTiO ₃ formed will have the (110) orientation instead of the desired (001) orientation, or the (001) orientation. BaTiO ₃ thin film
(110) Orientation is mixed. If the initial Ba / Ti ratio is too large, the supplied Ba reacts with the underlying ZrO ₂ , so that BaTiO ₃ having the desired orientation cannot be obtained. In order to avoid the reaction between Ba and ZrO ₂ , it is preferable to make Ti excess in the early stage of growth. If the temperature is too high, the laminated films will interdiffuse and the crystallinity will decrease. The deposition rate is
0.05-1.00 nm / s, preferably 0.100-0.
It is desirable to set it to 500 nm / s. The reason is that if it is too slow, the metal evaporation source will be oxidized by the introduced oxygen and the evaporation rate will be unstable, making it impossible to make the composition constant. On the other hand, if the speed is too high, the crystallinity of the formed thin film is poor and the surface becomes uneven. Therefore, prior to the deposition of the BaTiO ₃ thin film, the degree to which the Ba metal and the Ti metal evaporate per unit time depending on the power amount conditions applied to the deposition source to form a deposited film of these metals and oxides is determined by a vacuum. It is measured and calibrated by a film thickness meter installed near the substrate in the evaporation tank. As is well known in other perovskites and tungsten bronze, A-site metal and B-site metal exist, but the initial supply is perovskite and A / B is 0 to 1, especially 0 to 0.
8, it is preferable to set the value to 0 to 0.5 with tungsten bronze.

As the oxidizing gas, oxygen, ozone,
Atomic oxygen, NO _{2 and the} like can be used. Here, description will be made on the assumption that oxygen is used. Oxygen is continuously exhausted from the chamber by a vacuum pump, and is supplied to a nozzle provided in the vacuum evaporation tank at 2 to 50 cc / min, preferably 5 to 50 cc / min.
An oxygen gas of about 10 ^-3 to 10 ^-1 Torr is created at least near the single crystal substrate in the vacuum chamber by continuously injecting 25 cc / min of oxygen gas. The optimal oxygen amount is determined by the size of the chamber, the pumping speed of the pump, and other factors, and an appropriate flow rate is determined in advance. Here, the upper limit of the oxygen gas pressure is set to 10 ^-1 Torr so that the metal source in the evaporation source in the vacuum chamber is not degraded and the evaporation rate is deposited at a constant rate. Further, when introducing oxygen gas into the vacuum deposition tank, it is preferable to inject oxygen gas from the vicinity of the surface of the single crystal substrate to create an atmosphere with a high oxygen partial pressure only in the vicinity of the single crystal substrate. The reaction on the substrate can be further promoted by the amount introduced. At this time, since the inside of the vacuum chamber is continuously evacuated, most of the vacuum chamber has a low pressure of 10 ^-4 to 10 ^-6 Torr.

In a narrow region of about 1 cm ² of the single crystal substrate, the oxidation reaction can be promoted on the single crystal substrate by this method, but the substrate area is 10 cm ² or more, for example, 2 mm in diameter.
Fig. 1
By rotating the substrate as described above and supplying a high oxygen partial pressure to the entire surface of the substrate, a large-area film can be formed. At this time, the rotation speed of the substrate is desirably 10 rpm or more. This is because if the number of rotations is low, a film thickness distribution occurs in the substrate surface. Although there is no particular upper limit on the number of rotations of the substrate, it is usually about 120 rpm due to the mechanism of the vacuum apparatus. Thus, the laminated thin film of the present invention is obtained. The metal epitaxial film is formed according to a conventional method.

Although the details of the manufacturing method have been described above, this manufacturing method is particularly clear in comparison with the conventional vacuum vapor deposition method, sputtering method, and laser ablation method. Since it can be carried out under easy operating conditions, it is suitable for obtaining a target product with high reproducibility and high completeness over a large area. In addition, the method
Even if a BE apparatus is used, a target thin film can be obtained in exactly the same manner.

Further, a metal orientation film, an orientation film of a perovskite material other than BaTiO ₃ or an orientation film of tungsten bronze material can be formed thereon in multiple layers. In this case, the alignment film can also be formed by an evaporation method, a sputtering method, or a sol-gel method.

After forming these alignment films, annealing may be performed as necessary. For example, in an oxide alignment film such as a Bi oxide film, leakage may increase due to oxygen defects, but annealing is performed in an oxidizing atmosphere such as air to reduce oxygen defects and improve insulation. be able to. The annealing temperature is preferably 400-8
The temperature is 50 ° C, more preferably 450 to 800 ° C, and the annealing time is preferably 1 second to 30 minutes, more preferably 5 to 15 minutes. Note that in the case where an electrode layer is provided over the oxide alignment film, annealing may be performed before or after the electrode layer is formed.

The laminated oxide thin film obtained as described above and the substrate for an electronic device using the same are processed, for example, by using a semiconductor process with the same structure, and the conventional S
It is configured as a capacitor and a gate for a DRAM by replacing iO _2, and a non-volatile memory is formed by integrating with a FET and the like by a semiconductor process. Further, by forming Si as a functional film on this substrate, it can be applied as an SOI device, and by forming a functional film of a superconductor, an infrared sensor, an optical modulator, and an optical switch OEIC are configured. Further, the present invention can be applied to SQUIDs, Josephson devices, superconducting transistors, electromagnetic wave sensors, and superconducting wiring LSIs.

[0135]

EXAMPLES Hereinafter, the present invention will be described in more detail by showing specific examples of the present invention.

Example 1 As a single crystal substrate on which an oxide thin film was grown, an Si single crystal wafer cut and mirror-polished so that the surface became a (100) plane was used. After the purchase, the mirror surface was cleaned by etching with a 40% ammonium fluoride aqueous solution. The Si substrate used was a 5ΩcmP type circular substrate having a diameter of 2 inches.

The single crystal substrate was fixed to a substrate holder provided with a rotation and heating mechanism installed in a vacuum chamber, and the vacuum evaporation chamber was evacuated to 10 ⁻⁶ Torr by an oil diffusion pump. In order to protect with an oxide, the substrate was rotated at 20 rpm and heated at 600 ° C. while introducing oxygen near the substrate from the nozzle at a rate of 25 cc / min. Here, a Si oxide film is formed on the substrate surface by thermal oxidation. By this method, a Si oxide film having a thickness of about 1 nm was formed.

Subsequently, the substrate was heated to 900 ° C. and rotated. The rotation speed was 20 rpm. At this time, oxygen gas was introduced from the nozzle at a rate of 25 cc / min, and metal Zr was evaporated from the evaporation source onto the substrate, thereby supplying 5 nm in terms of the thickness of the Zr metal oxide. A Si surface-treated substrate having a surface structure was obtained. This surface is RHEE
The figure measured by D is shown in FIG.

In FIG. 3, the pattern was measured in the incident direction [110], but the pattern was completely the same even when rotated by 90 °. That is, it is confirmed that a Si surface-treated substrate having a stable 1 × 1 surface structure is obtained.

Further, metal Zr was supplied from the evaporation source onto the Si surface-treated substrate while the substrate temperature was 900 ° C., the rotation speed was 20 rpm, and oxygen gas was introduced from the nozzle at a rate of 25 cc / min. A 10 nm thick ZrO ₂ film
Obtained on the processing substrate.

FIG. 4 shows the results of X-rays measured on the obtained thin film. In FIG. 4, the (002) peak of ZrO ₂ is clearly observed. It can be seen that a crystal film strongly oriented in the direction reflecting the crystal structure and symmetry of ZrO ₂ was obtained. The peaks shown in the figure are reflections from only one reflection surface, and it can be seen that the ZrO ₂ film is a single-orientation highly crystalline film which is not seen in the conventional example. Further, the half width of the rocking curve of this reflection was 0.7 ° (actual measurement value), and it was confirmed that the orientation was excellent.

FIG. 5 shows the RHEED pattern of this thin film. The incident direction of the electron beam is [110] on the Si substrate.
Shown one from the direction. As you can see from this result,
The diffraction pattern on the surface of the thin film having this structure is a completely streak-like pattern. This completely streak pattern indicates that ZrO ₂ has excellent crystallinity and surface properties. The same crystallinity and surface properties were obtained for the YSZ film. But Z
The rO ₂ film showed a resistance five times higher than that of YSZ and was found to be excellent in insulation. Further, the obtained ZrO ₂ film was JIS B at 10 places over almost the entire surface.
10610 average roughness Rz (reference length L: 500
nm) was measured by AFM and found to be on average 0.70 n
m, 0.95 nm at the maximum, 0.10 nm at the minimum, and 0.80 nm or less at 90% of the measurement points, which was flat at the molecular level.

Using the thus obtained Si single crystal substrate on which the ZrO ₂ film was formed as a deposition substrate, a substrate temperature of 900 ° C., a rotation speed of 20 rpm, and oxygen gas of 25 cc / cm. Minutes with the metal Ba
By supplying Ti and metal Ti at a ratio of 1: 1 from the evaporation source, a BaTiO ₃ film having a thickness of 300 nm was obtained on the vapor deposition substrate. At the initial stage of film formation, only Ti is converted to a TiO ₂ film thickness of 0.1.
After supplying 5 nm, the metal Ba and the metal Ti are supplied at a ratio of 1: 1. The film forming speed of BaTiO ₃ is set to 0.05 nm / s and the thickness is set to 2 nm.
After the film formation, the film formation speed was further increased to 0.2 nm / s.

FIG. 6 shows the results of X-rays measured on the BaTiO ₃ thin film obtained on the ZrO ₂ film. FIG. 6 shows BaTiO ₃
The (001) and (002) peaks are clearly observed. It can be seen that a (001) crystal film strongly oriented in the direction reflecting the crystal structure and symmetry of BaTiO ₃ was obtained. In particular, these peaks are reflections from only one equivalent reflecting surface, respectively, and it can be seen that these peaks are monocrystalline and highly crystalline films. Further, the half width of the rocking curve of this reflection was 1.4 ° (actually measured value), and it was confirmed that the orientation was excellent. BaTi measured in the same manner as above
The Rz of the O ₃ thin film was 0.45 nm or less at all measured positions.

FIG. 7 shows the RHEED pattern of this thin film. The incident direction of the electron beam is [110] on the Si substrate.
Shown one from the direction. As you can see from this result,
The diffraction pattern on the surface of the thin film having this structure is a completely streak-like pattern. This completely streak pattern indicates that BaTiO ₃ is excellent in crystallinity and surface properties. YS instead of ZrO ₂ film
In the same manner, the BaT film is formed on the Z film and the ZrO ₂ film stabilized by other rare earth metal elements (including Sc) of Y.
An iO ₃ film was obtained.

FIG. 8 shows a TEM photograph of a cross section of this thin film. In the figure, from the bottom, a Si substrate, a SiO ₂ layer, a ZrO ₂ film,
The BaTiO ₃ films are formed in this order, and each crystal lattice can be observed. The SiO ₂ layer is an amorphous film, and ZrO
_It is presumed that the film was formed by diffusion of oxygen during the formation of the ₂ film and the BaTiO ₃ film. From this photograph, BaTiO ₃ was changed to Zr.
It can be seen that epitaxial growth was directly performed on O ₂ without inclusions. Also, it can be seen that the ZrO ₂ lattice and the BaTiO ₃ lattice are lattice-matched at 3: 4. Also,
The relationship between the crystal planes (that is, the plane orientation) of the Si substrate, the oxide thin film containing ZrO ₂ as a main component, and the oriented thin film of BaTiO ₃ thin film is shown by TEM image, X-ray diffraction and RHEED.
From BaTiO ₃ (001) // Zr _1-x RxO _2- δ (001) // Si (100), and
It is confirmed that it is formed of BaTiO ₃ [100] // Zr _1-x RxO ₂ -δ [100] // Si [010]. The BaTiO ₃ thin film obtained in the present invention has been realized for the first time as a (001) BaTiO ₃ thin film epitaxially grown on a Si substrate. Further Sr
TiO _3, BaTiO _3, and a solid solution of SrTiO ₃ were also prepared using the same method and evaluated by X-ray diffraction and RHEED. As a result, completely the same epitaxial film was obtained.

The relative dielectric constant of the obtained laminated thin film using BaTiO ₃ was measured.
Showed a high value. In addition, a Pt electrode, S
When an Al electrode was formed on the i-substrate and the CV characteristics were measured, a hysteresis as shown in FIG. 9 was obtained, and the hysteresis width was 0.2 V, that is, a 0.2 V memory window was obtained. become.

Further, by utilizing this characteristic, the laminated thin film can be
An element used for the gate oxide film of T was fabricated, and the memory operation was confirmed.

Example 2 In Example 1, the thickness of BaTiO ₃ was 50 nm, the thickness was 300 nm, and the composition was Sr _0.25 Ba _0.75 Nb ₂ O.
Substrate temperature 800 ℃ by sputtering SBN thin film of ₆
And a laminated thin film of SBN (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) was obtained. FIG. 10 shows the results of X-rays measured on the thin film. Only reflection by the c-plane was obtained, indicating that the film was a single alignment film. RHEED is shown in FIG. Although the RHEED pattern is not streak, it can be seen from these that the obtained SBN thin film is a c-plane single-oriented film having good crystallinity. In the same way, instead of SBN, a PBN thin film with the composition Pb _0.38 Ba _0.62 Nb ₂ O ₃ was formed, and PBN (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100)
Was obtained. In the case of PBN, the substrate temperature is 650 ° C.
Was set to form a film. X measured on the obtained thin film
The result of the line is shown in FIG. It can be seen that PBN has a c-plane single orientation similarly to SBN. Note that the SBN thin film is 90
For those formed at a substrate temperature of 0 ° C., RHEED
From measurement and TEM evaluation, it was found that the c-plane had a single orientation and the crystal axis orientation relationship with the Si substrate was SBN [100] // Si [010].

Example 3 In the same manner as in Example 2, PZT (001) / BaTiO ₃ (001) / ZrO ₂ (001)
A laminated thin film of / Si (100) was obtained. The thickness of BaTiO ₃ was 50 nm, and the thickness of PZT was 300 nm. PZT is formed by sputtering at a substrate temperature of room temperature, and then 700 in air.
Annealed at 10 ° C. for 10 minutes to obtain a crystallized film.

FIG. 13 shows the results of X-rays measured on the thin film. Only reflection by the c-plane of PZT was obtained, indicating that the film was a single orientation film. FIG. 14 shows CV characteristics. Hysteresis is seen from this figure, and about 0.5
It can be seen that a memory window of V was obtained. Utilizing this characteristic, this laminated thin film can be used as a transistor (FET).
An element (MFIS structure) is fabricated as a gate oxide film of
Confirmed memory operation.

Example 4 In the same manner as in Example 2, Pt (001) / BaTiO ₃ (001) / ZrO ₂ (001) /
A laminated thin film of Si (100) was obtained. The thickness of BaTiO ₃ was 100 nm, and the thickness of Pt was 100 nm. Pt was formed at a substrate temperature of 700 ° C. by vapor deposition.

FIG. 15 shows a cross-sectional TEM photograph of the laminated thin film, and FIG. 16 shows an X-ray result measured for the thin film. FIG. 17 shows RHEED. From these, epitaxial Pt (001) with good film quality
It can be seen that is obtained. Ir, O instead of Pt
s, Re, Pd, Rh, Ru and their alloys (Pt
(Including alloys), an epitaxial film having good film quality was obtained in the same manner as the crystalline Pt produced similarly.

Example 5 BaTiO ₃ was further formed to a thickness of 300 nm on the Pt of Example 4 to obtain a composition BaTiO ₃ (001) / Pt (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (10
0) was obtained. The RHEED, X-ray diffraction and DE hysteresis characteristic lines of this thin film are shown in FIG.
FIG. 19 and FIG. BaTiO from X-ray diffraction
_{The three} films were confirmed to be c-plane unidirectionally oriented films, and RH
The axial orientation relationship from EED to Si substrate is BaTiO ₃ [100] // S
It can be seen that i [010]. Further, Rz measured in the same manner as above was 0.50 nm or less at all measured positions. The DE hysteresis is performed by depositing a Pt electrode on a BaTiO ₃ film, and forming a Pt electrode on the BaTiO ₃ film.
The measurement was performed using a (001) film as an electrode and a Sawyer tower circuit. The relative permittivity was measured using an electrode similar to that used for the DE hysteresis measurement, and 100
It was 1000 when measured at kHz. Further, utilizing this DE hysteresis, a memory cell was fabricated on a Si substrate together with the FET, and the memory operation was confirmed.

Embodiment 6 On the Pt of Embodiment 4, SBN and PBN are further added (the same as in Embodiment 2).
Is formed to a thickness of 300 nm, and the composition SBN (001) / Pt (001) / B
aTiO ₃ (001) / ZrO ₂ (001) / Si (100) laminated thin film and PBN (0
01) / Pt (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) laminated thin film was obtained. However, the substrate temperature during the formation of SBN and PBN was 800 ° C. and 650 ° C., respectively, and after the formation, annealing was performed at 750 ° C. for 10 minutes in air. SBN
RHEED, X-ray diffraction and DE hysteresis characteristic lines of the thin film are shown in FIGS. 21, 22 and 23, respectively. X-ray diffraction of the PBN thin film is shown in FIG. X-ray diffraction reveals that the SBN and PBN thin films are c-plane unidirectionally oriented films. From RHEED, it was found that the axial orientation relationship with the Si substrate was SBN [100] // Si [010] and PBN [100] // Si [010]. The relative dielectric constant was 200 for SBN and 310 for PBN. Further, a memory cell is fabricated on a Si substrate together with the FET by utilizing the DE hysteresis,
Confirmed memory operation.

[0156] BaTiO to the thickness of BaTiO ₃ and 50nm in Example 7 Example 1 ₃ (00
1) / ZrO ₂ (001) / Si (100) laminated film, Pt (001) / BaTi of Example 4
O ₃ (001) / ZrO ₂ (001) / Si (100) laminated films were prepared and used as these substrates. However, in Examples 1 and 4, the deposition rate of the ZrO ₂ film was 0.06 nm / s.
nm / s. As a result, the above-mentioned Rz of the ZrO ₂ film was 0.80 nm or less at all measured positions, and 80% of the measured positions.
Was 0.40 nm or less.

The substrate was heated to 700 ° C. in a vacuum chamber,
Rotated at m. Then, radical oxygen gas is introduced from the ECR oxygen source at a rate of 10 cc / min, and Bi ₂ O ₃ ,
TiOx a (x = 1.67) by evaporation from each evaporation source was formed a Bi ₄ Ti ₃ O ₁₂ oxide film having a thickness of 300 nm. The supply from the evaporation source was performed while controlling the molar ratio of Bi ₂ O ₃ : TiOx to be 2: 3. Thus, Bi ₄ Ti ₃ O ₁₂ / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100),
A multilayer thin film of Bi ₄ Ti ₃ O ₁₂ / Pt (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) was obtained.

FIG. 25 shows that Bi ₄ Ti ₃ O ₁₂ / Pt (001) / BaTiO ₃ (00
The RHEED pattern of 1) / ZrO ₂ (001) / Si (100) is shown in FIG.
The result of a line diffraction is shown. The obtained Bi ₄ Ti ₃ O ₁₂ was confirmed to be a c-plane unidirectional film by X-ray diffraction, and was confirmed to be an epitaxial film by RHEED, and the orientation relationship with the Si substrate was Bi ₄ Ti ₃ O ₁₂ [ 100] // Si [010]. The results of X-ray diffraction and RHEED of the Bi ₄ Ti ₃ O ₁₂ film formed on the BaTiO ₃ (001) film were the same.

In addition, Bi ₄ Ti ₃ O ₁₂ (001) / BaTiO ₃ (001) / ZrO
_A Pt electrode was formed on the sample surface of the ₂ (001) / Si (100) structure and an Al electrode was formed on the Si substrate, and the CV characteristics were measured. As a result, a hysteresis as shown in FIG. 27 was obtained, and the hysteresis width was 0.
This means that a memory window of 3 V, that is, 0.3 V was obtained. Furthermore, utilizing this characteristic, the laminated thin film can be FE
An element used for the gate oxide film of T was fabricated, and the memory operation was confirmed.

[0160] BaTiO _3, which was 50nm thickness of BaTiO ₃ in the Example 8 Example 1 (00
1) / ZrO ₂ (001) / Si (100) laminated film, Ir (001) / BaTi of Example 4
O ₃ (001) / ZrO ₂ (001) / Si (100) laminated films were prepared and used as substrates. However, the conditions for forming the ZrO ₂ film on these substrates were the same as in Example 7.

The substrate was heated to 700 ° C. in a vacuum chamber,
Rotated at m. Then, radical oxygen gas is introduced from the ECR oxygen source at a rate of 10 cc / min, and Bi ₂ O ₃ ,
By evaporating Sr metal and Nb ₂ O ₅ from the respective evaporation sources, a Bi ₂ SrNb ₂ O ₉ oxide film having a thickness of 300 nm was formed. The supply from the evaporation source was performed while controlling the molar ratio of Bi ₂ O ₃ : Sr: Nb ₂ O ₅ to 1: 1: 1. Thus, Bi ₂ SrNb ₂ O ₉ / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100), Bi ₂ Sr
A laminated thin film of Nb ₂ O ₉ / Ir (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) was obtained.

FIG. 28 shows that Bi ₂ SrNb ₂ O ₉ / Ir (001) / BaTiO ₃ (00
The RHEED pattern of 1) / ZrO ₂ (001) / Si (100) is shown in FIG.
The result of a line diffraction is shown. The obtained Bi ₂ SrNb ₂ O ₉ was confirmed to be a c-plane unidirectional film by X-ray diffraction, and was confirmed to be an epitaxial film by RHEED. Further, the orientation relationship with the Si substrate was Bi ₂ SrNb ₂ O ₉ [ 100] // Si [010]. Ba
For the Bi ₂ SrNb ₂ O ₉ film formed on the TiO ₃ (001) film,
The line diffraction and RHEED results were similar.

In addition, Bi ₂ SrNb ₂ O ₉ (001) / BaTiO ₃ (001) / ZrO ₂
After annealing a (001) / Si (100) structure sample in air at 650 ° C for 10 minutes, a Pt electrode was formed on the surface and an Al electrode was formed on the Si substrate.
When the V characteristic was measured, a hysteresis as shown in FIG. 30 was obtained, and the hysteresis width was 0.35 V, that is, a 0.35 V memory window was obtained. Further, utilizing this characteristic, an element using the laminated thin film as the gate oxide film of the FET was manufactured, and the memory operation was confirmed.

The above-mentioned effects were similarly realized by using a perovskite film or a tungsten bronze film other than the above, or a conductive epitaxial layer or an oxide thin film of another material other than the above.

[0165]

The manufacturing method according to the present invention provides a method of obtaining a c-plane oriented simple perovskite thin film such as an epitaxially grown (001) BaTiO ₃ thin film on a Si substrate via an oxide thin film containing ZrO ₂ as a main component. It can be formed in a large area over the entire surface of a substrate with a diameter of 2 inches or more with high reproducibility and high quality under operating conditions that have no room for impurities and that are easy to control. It has high utility value. Specifically, a conventional thin film structure is processed by a semiconductor process, and the conventional Si
By substituting O ₂ , it can be configured as a capacitor and a gate for a DRAM. Furthermore, by forming Si as a functional film on this substrate, it can be applied as an SOI device, and by utilizing the characteristics of ferroelectrics and superconductors, it can be used for nonvolatile memories, infrared sensors, optical modulators, optical switches, OEICs. , SQUID, Josephson element, superconducting transistor, electromagnetic wave sensor, and superconducting wiring LSI.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a vapor deposition apparatus used in a method for manufacturing an electronic device substrate of the present invention.

FIG. 2A is a schematic diagram showing a RHEED pattern of a 1 × 1 surface structure, and FIG. 2B is a schematic diagram showing a RHEED pattern of 2 × 1, 1 × 2, or a mixture thereof. It is.

FIG. 3 is a drawing substitute photograph showing a surface structure of a Si substrate having a 1 × 1 surface structure formed by Zr metal and oxygen, which shows a RHEED pattern, and is viewed from a Si single crystal [110] direction. It is a diffraction pattern in which an electron beam was incident.

FIG. 4 is an X-ray diffraction diagram of a film structure of ZrO ₂ obtained on a Si (100) substrate.

FIG. 5 is a drawing substitute photograph showing a crystal structure of ZrO ₂ obtained on a Si (100) substrate, wherein RHEED is obtained when an electron beam is incident from the [110] direction of the Si single crystal substrate.
It is a figure showing a diffraction pattern.

FIG. 6 is an X-ray diffraction diagram of a BaTiO ₃ film obtained on a ZrO ₂ (001) / Si (100) substrate.

FIG. 7 is a drawing substitute photograph showing a crystal structure of a BaTiO ₃ film obtained on a ZrO ₂ (001) / Si (100) substrate, in which an electron beam is incident from the [110] direction of the Si single crystal substrate. RHE in case
It is a figure showing an ED diffraction pattern.

FIG. 8 is a cross-sectional TEM photograph of a BaTiO ₃ film obtained on a ZrO ₂ (001) / Si (100) substrate.

FIG. 9 is a graph showing C− of a BaTiO ₃ / ZrO ₂ / Si laminated structure (MOS structure).
It is a V characteristic.

FIG. 10 is an X-ray diffraction diagram of an SBN film obtained on a BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate.

FIG. 11 is a drawing substitute photograph showing the crystal structure of the SBN film obtained on the BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate, as viewed from the [110] direction of the Si single crystal substrate. FIG. 4 is a diagram illustrating a RHEED diffraction pattern when an electron beam is incident.

FIG. 12: PB obtained on BaTiO ₃ / ZrO ₂ / Si (100) substrate
FIG. 3 is an X-ray diffraction diagram of an N film.

FIG. 13 is an X-ray diffraction diagram of a PZT film obtained on a BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate.

FIG. 14 shows CV characteristics of a PZT (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) stacked structure (MOS structure).

FIG. 15 is a TEM photograph of a cross section of a Pt film obtained on a BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate.

FIG. 16 is an X-ray diffraction diagram of a Pt film obtained on a BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate.

FIG. 17 is a drawing substitute photograph showing a crystal structure of a Pt film obtained on a BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate,
FIG. 4 is a diagram showing a RHEED diffraction pattern when an electron beam is incident from the [110] direction of a Si single crystal substrate.

FIG. 18 is a drawing-substitute photograph showing the crystal structure of a BaTiO ₃ film obtained on a Pt (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate; FIG. 3 is a diagram showing a RHEED diffraction pattern when an electron beam is incident from the [110] direction of FIG.

FIG. 19 is an X-ray diffraction diagram of a BaTiO ₃ film obtained on a Pt (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate.

FIG. 20 shows the DE hysteresis characteristics of a BaTiO ₃ film obtained on a Pt (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate.

FIG. 21 is a drawing substitute photograph showing a crystal structure of an SBN film obtained on a Pt (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate. FIG. 4 is a diagram illustrating a RHEED diffraction pattern when an electron beam is incident from a [110] direction.

FIG. 22 is an X-ray diffraction diagram of an SBN film obtained on a Pt (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate.

FIG. 23 shows the DE hysteresis characteristics of the SBN film obtained on the Pt (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate.

FIG. 24 is an X-ray diffraction diagram of a PBN film obtained on a Pt (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate.

FIG. 25 is a drawing substitute photograph showing a crystal structure of a Bi ₄ Ti ₃ O ₁₂ film obtained on a Pt (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate, FIG. 4 is a diagram showing a RHEED diffraction pattern when an electron beam is incident from the [110] direction of a Si single crystal substrate.

FIG. 26 is an X-ray diffraction diagram of a Bi ₄ Ti ₃ O ₁₂ film obtained on a Pt (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate.

FIG. 27: Bi ₄ Ti ₃ O ₁₂ (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si
(100) CV characteristics of a laminated structure (MOS structure).

FIG. 28 is a drawing substitute photograph showing a crystal structure of a Bi ₂ SrNb ₂ O ₉ film obtained on an Ir (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate; FIG. 4 is a diagram showing a RHEED diffraction pattern when an electron beam is incident from the [110] direction of a Si single crystal substrate.

FIG. 29 is an X-ray diffraction diagram of a Bi ₂ SrNb ₂ O ₉ film obtained on an Ir (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si (100) substrate.

FIG. 30 shows Bi ₂ SrNb ₂ O ₉ (001) / BaTiO ₃ (001) / ZrO ₂ (001) / Si
(100) CV characteristics of a stacked structure (MOS structure).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Deposition apparatus 1a Vacuum tank 2 Single crystal substrate 3 Holder 4 Rotating shaft 5 Motor 6 Heater 7 Oxidizing gas supply device 8 Oxidizing gas supply port 9 Ba evaporator 10 Ti evaporator 11 Zr evaporator 12 rare earth metal element evaporator P Vacuum pump

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI H01L 27/108 H01L 39/24 ZAAW 39/02 ZAA 21/316 M 39/24 ZAA 27/10 651 // H01L 21/316 ( 56) References JP-A-8-264524 (JP, A) JP-A-8-1009099 (JP, A) Hiroaki MYOREN et. al, Proc. SPIE Int. Soc. Opt. Eng. 1989, Vol. 1187, p. 47-56 (58) Fields surveyed (Int. Cl. ⁷ , DB name) C30B 1/00-35/00 H01L 21/20 H01L 21/31-21/32 INSPEC (DIALOG) JICST file (JOIS)

Claims (29)

(57) [Claims] An oxide thin film is formed on a semiconductor single crystal substrate, and the oxide thin film mainly contains zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y). A laminated thin film comprising at least one epitaxial thin film, formed on the oxide thin film from a perovskite-type or tungsten bronze-type dielectric material, and having a c-plane unidirectionally oriented thin film parallel to the substrate surface. 2. The perovskite type or tungsten bronze type dielectric material includes barium titanate, strontium titanate, lead zircon titanate (PZT),
2. The laminated thin film according to claim 1, wherein the thin film is strontium barium niobate (SBN) or barium lead niobate (PBN). 3. The laminated thin film according to claim 1, wherein the oriented thin film is an epitaxial film. 4. The semiconductor single crystal substrate is made of Si (100).
A silicon single crystal substrate having a surface on the surface, wherein the crystallographic orientation relationship between the oriented thin film and the Si single crystal substrate is perovskite or tungsten bronze [100] // Si [01
0]. 5. An epitaxial film formed of a perovskite-type or tungsten bronze-type material on a Si single crystal substrate formed of a Si single crystal having a Si (100) plane on its surface, and having a crystal axis orientation relationship. Perovskite or tungsten bronze [100] // Si [01
0], wherein at least an epitaxial thin film mainly composed of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) is provided between the Si single crystal substrate and the oriented thin film. An oxide thin film including one layer is interposed, and the composition of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) in the oxide thin film is Zr _{1 -x} R _x O ₂ -δ ( Where R is S
a rare earth metal element containing c and Y, where x = 0 to 0.
75, δ = 0 to 0.5), and the zirconium oxide of the oxide thin film contains at least 93 mol% of Zr in terms of only the constituent elements excluding oxygen. A laminated thin film wherein the half width of the rocking curve of reflection is 1.5 ° or less, and at least 80% of the surface of the oxide thin film has a ten-point average roughness Rz at a reference length of 500 nm of 2 nm or less. 6. The perovskite type or tungsten bronze type material is barium titanate, strontium titanate, lead zircon titanate (PZT), strontium barium niobate (SBN) or barium lead niobate (PBN). Item 5. The laminated thin film according to Item 5. 7. A first epitaxial film mainly composed of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) and formed on a semiconductor single crystal substrate; Second using a perovskite-type material formed directly on the epitaxial film
An oxide thin film including an oriented thin film which is an epitaxial film of the above, wherein the semiconductor single crystal substrate is a Si single crystal substrate having a Si (100) plane on its surface, and the Si single crystal substrate and the crystal of the oriented thin film are The axial orientation relationship is perovskite [100] // S
i [010], and the composition of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) in the oxide thin film is Zr _1-x R _x O _2- δ (where R Is S
a rare earth metal element containing c and Y, where x = 0 to 0.
75, δ = 0 to 0.5), and the zirconium oxide of the oxide thin film contains at least 93 mol% of Zr in terms of only the constituent elements excluding oxygen. A laminated thin film wherein the half width of the rocking curve of reflection is 1.5 ° or less, and at least 80% of the surface of the oxide thin film has a ten-point average roughness Rz at a reference length of 500 nm of 2 nm or less. 8. The laminated thin film according to claim 7, wherein the perovskite-type material of the second epitaxial film contains barium titanate, strontium titanate or a solid solution thereof as a main component. 9. A conductive film which is an epitaxial film formed of a metal or a conductive oxide on a Si single crystal substrate having a Si (100) plane on its surface and having a single orientation of a c-plane or an a-plane parallel to the substrate surface. An oriented thin film, and an oriented thin film formed of a perovskite type or a tungsten bronze type material on the conductive oriented thin film, wherein the oriented thin film is an epitaxial film, and the crystal axis orientation relationship between the Si substrate and the oriented thin film is Perovskite or tungsten bronze [100] // Si [0
10], wherein at least one epitaxial thin film mainly composed of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) is provided between the Si single crystal substrate and the conductive alignment thin film. A laminated thin film with an oxide thin film including layers interposed. 10. The method according to claim 1, wherein the metal is Pt, Ir, Os, Re,
The laminated thin film according to claim 9, which is a metal containing at least one of Pd, Rh, and Ru, and wherein the conductive oxide is an oxide containing In or a perovskite oxide. 11. A perovskite-type or tungsten bronze-type material of the alignment thin film, wherein barium titanate,
Strontium titanate, lead zircon titanate (PZ
The laminated thin film according to claim 9 or 10, wherein T) is strontium barium niobate (SBN) or barium lead niobate (PBN). 12. A plane orientation relationship between the Si single crystal substrate, the conductive alignment thin film and the alignment thin film is perovskite or tungsten bronze (001) // conductive thin film (0).
01) // Si (100). 13. The composition of zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) of the oxide thin film is Zr _{1 -x} R _x O ₂ -δ.
(Where R is a rare earth metal element containing Sc and Y, and x = 0 to 0.75 and δ = 0 to 0.5). Laminated thin film. 14. The zirconium oxide of the oxide thin film converts Zr to 93 mol in terms of only constituent elements other than oxygen.
The laminated thin film according to any one of claims 1 to 4, and 7 to 13, which contains 1% or more. 15. A half-width of a rocking curve of (002) reflection of the oxide thin film is 1.5 ° or less.
A laminated thin film according to any one of to 4, 7-14. 16. At least 80% of the surface of the oxide thin film has a ten-point average roughness Rz of 2 at a reference length of 500 nm.
The laminated thin film according to any one of claims 1 to 4, and 7 to 15, wherein the thickness is not more than nm. 17. A first epitaxial film mainly composed of zirconium oxide stabilized with zirconium oxide or a rare earth metal element (including Sc and Y), and a perovskite formed thereon. 17. The laminated thin film according to claim 1, comprising at least a second epitaxial film made of a mold material. 18. The method according to claim 1, wherein the perovskite-type material of the second epitaxial film is mainly composed of barium titanate, strontium titanate or a solid solution thereof.
7. The laminated thin film of 7. 19. The laminated thin film according to claim 17, wherein a crystal axis orientation relationship between the Si single crystal substrate and the second epitaxial film made of the perovskite-type material is perovskite [100] // Si [010]. 20. An electronic device substrate comprising the laminated thin film according to claim 1. 21. An electronic device comprising the laminated thin film according to claim 1. 22. A silicon single crystal substrate, an oxide thin film formed on the single crystal silicon substrate by zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y), and the oxide thin film A method for producing a laminated thin film comprising a thin film and an oriented thin film formed of a perovskite type or a tungsten bronze type material, comprising: heating a Si single crystal substrate in a vacuum chamber; Introduction and supply of Zr or Zr and at least one rare earth metal element (including Sc and Y) by evaporation to the surface of the single crystal substrate, and epitaxially growing the oxide thin film on the surface of the single crystal substrate. A method for producing a laminated thin film, comprising forming a single-oriented epitaxial film as described above and using the same as the oxide thin film. 23. The zirconium oxide or zirconium oxide stabilized by a rare earth metal element (including Sc and Y) is selected from the group consisting of Zr _{1 -x} R _x O ₂ -δ (where R is S
a rare earth metal element containing c and Y, where x = 0 to 0.
75. Δ is 0 to 0.5. 23. The method for producing a laminated thin film according to claim 22, which has the composition of (22). 24. The Si single crystal substrate has a 1 × 1 surface structure formed on the substrate surface by Zr or Zr and at least one rare earth metal element (including Sc and Y) and oxygen. 24. The method for manufacturing a laminated thin film according to claim 22, wherein a Si surface-treated substrate is used. 25. The Si surface-treated substrate forms an Si oxide layer having a thickness of 0.2 to 10 nm on the surface of the Si single crystal substrate, and thereafter sets the substrate temperature to 600 to 1200 ° C. and forms a vacuum. An oxidizing gas is introduced into the tank, and at least the oxygen partial pressure of the atmosphere near the substrate is set to 1 × 10 ⁻⁴ to 1 × 10 ^4
-1 Torr, and in this state, Zr or Zr and at least one rare-earth metal element (including Sc and Y) are evaporated and supplied to the substrate surface on which the Si oxide layer is formed. 25. The method of manufacturing a laminated thin film according to claim 24, wherein: 26. When forming the Si oxide layer, the Si single crystal substrate is placed in a vacuum chamber into which an oxidizing gas has been introduced.
26. The method for producing a laminated thin film according to claim 25, wherein the Si oxide layer is formed by heating to about 700 [deg.] C. and setting the oxygen partial pressure of the atmosphere in the vacuum chamber at least near the substrate to 1 * 10 < ^-4 > Torr or more. 27. An oxidizing gas is sprayed onto the surface of the Si single crystal substrate from the vicinity thereof, and an atmosphere having a higher partial pressure of the oxidizing gas than other portions is created only in the vicinity of the Si single crystal substrate. The method for producing a laminated thin film according to any of the above. 28. The Si single crystal substrate having a substrate surface area of 10 cm ² or more and rotating the substrate to provide the oxidizing gas high partial pressure atmosphere over the entire Si single crystal substrate, 28. The method according to claim 22, wherein a substantially uniform oxide thin film is formed over the entire surface of the Si single crystal substrate. 29. When forming the epitaxial film,
3. The Si single crystal substrate is heated to 750 ° C. or higher.
29. The method for producing a laminated thin film according to any one of 2 to 28.