JP3223233B2 - Oxide thin film, substrate for electronic device, and method of forming oxide thin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an oxide thin film is an epitaxial mainly composed of ZrO ₂ formed on the Si single crystal substrate, a method of forming the substrate and the oxide thin film for electronic devices using the same It is about.

[0002]

2. Description of the Related Art An electronic device in which a superconducting film or a dielectric film is formed and integrated on an Si substrate which is a semiconductor crystal substrate has 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, and a superconducting wiring LS
In semiconductors and dielectrics such as I, LS with higher integration
I, dielectric isolation LSI using SOI technology, nonvolatile memory, infrared sensor, optical modulator and optical switch OE
IC (Opto-electronic integrated circuit: opto-electronic 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 thin film materials, and a superconducting or dielectric epitaxial film that is as close to a perfect single crystal as possible is desired.

[0004] The crystal structures of the main oxide superconductors and ferroelectrics, which are valuable in 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
i is provided with an epitaxially grown buffer layer, on which a perovskite oxide is epitaxially grown. Phys. Lett. , Vol. 5
4, No. 8, p. 754-p. 756 (1989),
Japanese Journal of Appli
Physics, Vol. 27, no. 4, L6
34-635 (1988) and JP-A-2-82585.
No. pp. 147-64.

In particular, since ZrO ₂ has good lattice matching with the Si crystal of the substrate and also has excellent lattice matching with the perovskite crystal, ZrO ₂ is used as a buffer material between the Si substrate and the perovskite crystal film from an early stage. ZrO
_2. Epitaxial films are attracting attention.

Furthermore, ZrO ₂ is high chemical stability, insulation, wide band gap (about 5 eV), equipped with a large dielectric constant (approximately 20), Thus, epitaxial ZrO ₂ film on Si, the buffer It can be used not only as a layer but also as a capacitor for SOI devices and DRAMs.

Conventionally, various methods and compositions have been studied for producing a ZrO ₂ epitaxial film. For example, Appl. Phys. Lett. , Vol. 53,
No. 16, p. 1506-08 (1988) (hereinafter, referred to as
In the first conventional example), an YSZ (Yttria-stabilized zirconia) oxide target obtained by adding Y ₂ O ₃ to ZrO ₂ was used, and Si was produced by ion beam sputtering.
It is stated that a YSZ epitaxial film can be obtained on a (100) substrate. In addition, the above Japanese
Journal of Applied Physi
cs, Vol. 27, no. 8, L1404-05 (1
988) (hereinafter referred to as a second conventional example), a YSZ epitaxial film is obtained on a Si (100) substrate by a vapor deposition method in which a YSZ pellet is evaporated by an electron gun in a vacuum chamber into which oxygen is introduced. That is stated. Furthermore,
Appl. Phys. Lett. , Vol. 57, N
o. 11, p. 1137-39 (1990) (hereinafter, referred to as a third conventional example) states that an YSZ epitaxial film can be obtained on a Si (100) substrate by a laser ablation method using a YSZ target. Furthermore, ThinSolid Films, 299, 17-23 (1993)
(Hereinafter referred to as a fourth conventional example) states that an YSZ epitaxial film can be obtained on a Si (100) substrate by a reactive magnetron sputtering method using a target in which a Y piece is placed on metal Zr. Have been.

[0008]

As described above, YSZ
The film is mainly used as a buffer film for epitaxially growing a functional film, but in order to obtain a high-quality functional film, besides matching the lattice constant of the buffer film with the lattice constant of the functional film, It is necessary that the buffer film has good crystallinity and surface properties. The crystallinity of the buffer film is determined by the half width of the rocking curve of the reflection peak in XRD (X-ray diffraction) and the reflection high-speed electron diffraction (Reflct
ion High Energy Electron Diffraction-RHE
(Sometimes referred to as ED). In addition, the surface properties are streak properties of RHEED images and surface roughness (ten-point average roughness) measured by an atomic force electron microscope (hereinafter, sometimes referred to as AFM).
You can find out at

However, when the above conventional method is used industrially, the following problems occur. As in the first conventional example,
When a YSZ target is used by a sputtering method, Zr
And the sputtering yields of Y are different, the Zr /
Y composition changes with time. The RHEED image of the YSZ film obtained in the first conventional example is streak but not very sharp. The rocking curve of the (002) reflection peak of the YSZ film crystal and other surface properties have not been analyzed at all, but these are considered to be unsatisfactory.

[0010] As in the second conventional example, Y is also obtained by vapor deposition.
The SZ pellet is irradiated with an electron beam and heated in vacuum at a high temperature (about 2
000 ° C. or higher), and decomposition of Zr, Y, and O occurs.
The composition of the pellet changes over time. When the composition of Zr / Y is different, not only the lattice constant of the YSZ crystal changes, but also the crystallinity changes depending on the composition of Zr, Y, and O. Further, the obtained RHEED image of the YSZ film is a spot, which indicates that the surface property is poor. Although rocking curves and other surface properties have not been analyzed at all, it is considered that these are not good.

As in the third conventional example, in the laser ablation method, although the composition of the target surface hardly changes with time, YSZ cannot be formed on a large-area (10 cm ² or more) Si wafer with good distribution. This is because the direction in which the target evaporating substance is emitted by the laser is limited,
This is because the region where Z is formed is a part in the Si substrate. This phenomenon is also observed in other materials in the laser ablation method. In addition, oxide targets and pellets, which are generally sintered bodies, are difficult to be highly purified, and are unsuitable for producing a highly pure YSZ epitaxial film. Further, it is described that the obtained YSZ film has an excellent rocking curve half-width of 0.71 ° and an excellent surface roughness measured by AFM of about 1 nm. Particles which are considered to be precipitates are partially observed in the surface image, and the unevenness in this portion is 2 nm or more. These particles are often found in films made using laser ablation, and because a large energy laser evaporates the target,
It is thought that large clusters adhere to the film. Other characteristics such as RHEED are not mentioned.

[0012] As in the fourth conventional example, the sputtering method using a metal target, the above compositional variation is small, the thin film surface is exposed to plasma of Ar and O ₂ is sputter gas problem crystallinity is disturbed There is. The RHEED image of the obtained YSZ film is not sharp, and the half width of the rocking curve is inferior to 1.6 °. No other characteristics of the obtained YSZ film are mentioned.

Further, Appl. Phys. 58 (6),
15 September 1985, page 2407, and Appl. Phys. 63 (2), 15
On page 581 of January 1988,
It is reported that "ZrO ₂ can be epitaxially grown on a Si single crystal substrate." It is stated that the crystal is not a single orientation film but includes other crystal planes. Usually, bulk ZrO ₂ is cubic at 2500 ° C. or higher, tetragonal at 2500 ° C. to around 1000 ° C., 1000
It becomes monoclinic from around ℃ to room temperature. Generally, a cubic crystal with high symmetry is easily obtained in an epitaxial thin film. This is because cubic crystals have more equivalent crystal planes than tetragonal crystals and monoclinic crystals. Because tetragonal and monoclinic materials have more non-equivalent crystal planes than cubic materials,
In addition to the orientation plane to be obtained, a different crystal plane is likely to be mixed. Therefore, since ZrO ₂ is also a monoclinic material at room temperature, a single-oriented epitaxial film has not been obtained so far.

The above Appl. Phys. 58 (6), 1
5 September The first 2407 pages of 1985, at a deposition temperature of the ZrO ₂ is 800 ° C. or less, ZrO ₂ film is obtained monoclinic, 800 ° C. in the tetragonal ZrO ₂
It is stated that a film is obtained. In these ZrO ₂ films, (11) other than the (002) orientation plane of ZrO ₂
It is shown that 1), (11-1) or (200) crystal planes exist, and a single orientation film of ZrO ₂ has not been obtained. There is no report that a single orientation film of ZrO ₂ has been obtained so far. In addition, reflection high-energy electron diffraction (Refle
ction High Energy Electron Diffraction-below, RH
Evaluation of the ZrO ₂ film crystal surface by EED) states that the RHEED image is a spot, and it is considered that large irregularities are present on the surface. Thus, a film having good crystallinity and surface properties of a ZrO ₂ epitaxial film has not been obtained so far.
Further, a semiconductor device using a ZrO ₂ film has not been fabricated and evaluated so far. However, as described above, when the semiconductor device is not unidirectionally oriented, a grain boundary is formed at an interface between different orientation planes, and When the property is poor, the interface with the electrode or semiconductor formed thereon is disturbed. Therefore, due to the disturbance of the physical quantity at the grain boundary and the interface, a decrease in the insulating property, a deterioration in the interface characteristics, and the like occur, and it is difficult to obtain good device characteristics.

As in the above conventional example, the rocking curve half width, surface roughness, RH of the YSZ film as the buffer layer
If any of the streak characteristics in the EED image is not good, a functional film epitaxially grown with high quality cannot be obtained thereon.

Accordingly, the present invention provides an epitaxial oxide thin film mainly composed of ZrO ₂ having good crystallinity and surface properties, an electronic device substrate provided with the oxide thin film, and a method for forming the oxide thin film. The purpose is to do so.

[0017]

This and other objects are achieved by the present invention which is defined below as (1) to (18). (1) Composition Zr _1-x R formed on Si single crystal substrate
_x O _2- δ (where R is a rare earth metal containing Y, x
= 0 to 0.75. Δ is 0 to 0.5. ) Wherein the half-width of the rocking curve of reflection of the (002) plane or the (111) plane is 1.5 ° or less, and at least 80% of the surface has a 10-point average with a reference length of 500 nm. An oxide thin film having a roughness _Rz of 0.60 nm or less. (2) Composition ZrO ₂ formed on Si single crystal substrate
Is a single-oriented epitaxial film, wherein the single-oriented epitaxial film is Zr in terms of only constituent elements excluding oxygen.
And the half-width of the rocking curve of reflection of the (002) plane or the (111) plane of the single-oriented epitaxial film is 1.5 ° or less, and the single-oriented epitaxial film has Is an oxide thin film having a ten-point average roughness Rz of 2 nm or less at a reference length of 500 nm. (3) As the Si single crystal substrate, the substrate surface is
The above (1) or (2) using a Si surface-treated substrate having a 1 × 1 surface structure formed by Zr metal and oxygen.
Oxide thin film. (4) The oxide thin film according to any one of (1) to (3), wherein a Si single crystal is used as the single crystal substrate so that the (100) plane or the (111) plane becomes the substrate surface. (5) The oxide thin film according to any one of (1) to (4), having an area of 10 cm ² or more. (6) An electronic device substrate having the oxide thin film according to any one of (1) to (5) on a substrate surface. (7) Formed on a single crystal substrate of Si and having a composition of Zr _1-x
R _x O _2- δ (where R is a rare earth metal containing Y,
x = 0 to 0.75. Δ is 0 to 0.5. A) a method of forming an oxide thin film which is an epitaxial film, wherein the inside of a vacuum chamber is initially evacuated to 1 × 10 ⁻⁵ Torr or more, and in this state, the Si single crystal substrate is heated to a predetermined temperature; Zr and at least one rare earth metal (Y
At least Zr of each of the metal elements is simultaneously evaporated from separate evaporation sources while controlling the ratio of Zr and the rare earth metal to supply the metal to the substrate surface of the single crystal substrate, and simultaneously with the supply of this metal. Alternatively, within a predetermined time, an oxidizing gas is introduced into the vacuum chamber, and the atmosphere at least in the vicinity of the single crystal substrate in the vacuum chamber is set to 1 × 10 ⁻⁴ to 1 × 10 ⁻² Torr, and the A method for forming an oxide thin film, comprising forming an oxide thin film on a substrate surface by epitaxial growth. (8) The predetermined time from the supply of the metal by evaporation to the introduction of the oxidizing gas is a time corresponding to 5 nm or less in terms of the thickness of the metal thin film formed on the single crystal substrate. The method for forming an oxide thin film. (9) The method for forming an oxide thin film according to the above (7) or (8), wherein the molar ratio of rare earth metal (including Y) / Zr from the evaporation source is controlled from 0 to 3 and simultaneously evaporated. (10) Rare earth metal (including Y) from evaporation source / Zr
(9) The method for forming an oxide thin film according to the above (9), wherein the molar ratio is controlled from 0.25 to 1.0 and simultaneously vaporized. (11) Composition Zr _1-x formed on Si single crystal substrate
R _x O _2- δ (where R is a rare earth metal containing Y,
x = 0 to 0.75. Δ is 0 to 0.5. A) heating a single crystal Si substrate in a vacuum layer, introducing an oxidizing gas into the vacuum layer, and at least one of Zr or Zr in a vacuum layer. Supplying the rare earth metal (including Y) by evaporation to the surface of the single crystal substrate, and epitaxially growing the oxide thin film on the substrate surface of the single crystal substrate to form a single oriented epitaxial film having the composition described above. A method for forming an oxide thin film, comprising: (12) As the Si single crystal substrate, the surface of the substrate is a Si surface-treated substrate having a 1 × 1 surface structure formed of Zr or Zr and at least one rare earth metal (including Y) and oxygen. The method for forming an oxide thin film according to (11) above, wherein (13) As the Si surface-treated substrate, a 0.2 to 10 nm Si oxide layer is formed on the surface of the substrate, and thereafter, the substrate temperature is set to 600 to 1200 ° C., and the oxidation is performed in the vacuum chamber. By introducing a reactive gas, at least the atmosphere near the substrate is set to 1 × 10 ⁻⁴ to 1 × 10 ⁻¹ Torr, and in this state, the surface of the substrate on which the Si oxide layer is formed is
The method for forming an oxide thin film according to any one of the above (7) to (12), wherein Zr or Zr and at least one rare earth metal (including Y) are supplied by evaporation to use a pretreated Si single crystal substrate. . (14) When forming the Si oxide, the Si single crystal substrate is placed in a vacuum chamber into which an oxidizing gas has been introduced, in a range of 300 to 700.
(13) The method for forming an oxide thin film according to the above (13), wherein the oxide thin film is formed by heating to a temperature of at least 1 ° 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. (15) As the Si single crystal substrate, a Si single crystal is
The method for forming an oxide thin film according to any one of the above (7) to (14), wherein the (100) plane or the (111) plane is used as a substrate surface. (16) 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 portions is formed only in the vicinity of the single crystal substrate.
(15) The method for forming an oxide thin film according to any one of (15) to (15). (17) The Si single crystal substrate has a substrate surface area of 10
cm ² or more, and rotating within the substrate to provide the oxidizing gas high partial pressure atmosphere over the entire single crystal substrate, thereby achieving substantially uniform oxidation over the entire substrate surface of the single crystal substrate. The method for forming an oxide thin film according to any one of the above (7) to (16), wherein the thin oxide film is formed. (18) When forming the epitaxial film, the S
The method for forming an oxide thin film according to any one of the above (7) to (17), wherein the i-single-crystal substrate is heated to 750 ° C. or higher.

[0018]

The oxide thin film of the present invention has a composition of Zr _1-x R _x O ₂ -δ formed on the surface of a Si single crystal substrate (where R is a rare earth metal containing Y, Zr _1-x R _x O _2-
δ preferably x = 0 to 0.75, more preferably x =
Oxide thin film is an epitaxial film of a is) 0.20 to 0.50 is, 1.50 ° half-value width of less of a rocking curve, and the reference length 500nm with 0.60nm following ten-point average roughness R _z In addition, since the crystal constituting the epitaxial film of the composition ZrO ₂ has a single orientation, the oxide thin film is used as a buffer film, and when a functional film is formed thereon, a high quality epitaxially grown film is obtained. Can be obtained.

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

In Japanese Patent Application Laid-Open No. 2-258700, a perovskite oxide (BaTiO ₃ ) single crystal film is formed on a single crystal oxide substrate by co-evaporation. Techniques of controlling the composition ratio using an evaporation source, increasing the pressure of oxygen only in the vicinity of the substrate, and using a substrate having a specific orientation surface are disclosed.
However, the technique disclosed in JP-A-2-258700 does not the target Y ₂ O ₃ containing ZrO ₂ single crystal film,
Moreover, since this is a technique for forming an oxide film on an oxide substrate, an oxidizing gas (oxygen gas) is introduced during the preparation of a film, which is a heating process of the substrate. In contrast, in the present invention,
Since it is a technology to form an oxide film on a non-oxide substrate,
When an oxidizing gas (oxygen gas) is introduced during preparation for film formation as in the technique of JP-A-2-258700, the substrate surface of the Si single crystal substrate is oxidized and an oxide thin film (for example,
SiO ₂ ) is formed, and the substrate surface is deteriorated. On the other hand, in the present invention, Zr and rare-earth metal (including Y) are not introduced during the film formation preparation without introducing an oxidizing gas.
Among them, at least Zr is evaporated to supply a metal to the substrate surface first, and thereafter, an oxidizing gas is introduced simultaneously or slightly with a delay to form an oxide film on the substrate surface. Further, the second method of the present invention solves the conventional problem in JP-A-2-258700 by using a method of treating a Si surface. JP-A-2-258700
In the publication, there is no description about such a characteristic process. Furthermore, the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2-258700 does not target a substrate having a large surface area of 10 cm ² or more at all, and does not suggest it. In fact, Japanese Patent Application Laid-Open No. 2-258700 discloses that the substrate area is 2.25 cm.
There are only ² (about 15 × 15 mm ² ) embodiments. In the present invention, the substrate area can be increased to 10 cm ² or more by rotating the substrate in the substrate plane.

[0021]

DETAILED DESCRIPTION OF THE INVENTION The oxide thin film of the present invention is composed of a composition Zr _1-x R _x O _2- δ (here, R
Is a rare earth metal containing Y, and x = 0 to 0.75, preferably 0.2 to 0.50).

The crystallinity of this oxide epitaxial film depends on the range of x. In general, in a small region where x is less than 0.2, Zr _{1 -x} R _x O ₂ -δ becomes a tetragonal crystal. Above that, it becomes cubic. In order to use this oxide thin film as, for example, a buffer layer, it is desirable that the oxide thin film has a single crystallinity as described above. In particular, a cubic crystal has higher crystal opposition than a tetragonal crystal and is excellent as a buffer layer. This is presumably because the crystals on the buffer layer surface are more regularly arranged in the cubic system than in the tetragonal system, and the crystallinity of the functional film formed thereon is higher.

On the other hand, in the region where x exceeds 0.75, the crystal is cubic, but a plane other than the target crystal plane is mixed. For example, when an attempt is made to obtain a (100) epitaxial film of Zr _{1 -x} R _x O ₂ -δ, a crystal of (111) is mixed in this range.

That is, from the range where tetragonal and cubic crystals can be formed and the range where a desired crystal plane can be obtained, Zr ₁ -xR
_In xO2 _- δ, x is 0 to 0.75, preferably 0.2
An epitaxial film excellent as a buffer layer can be obtained in the range of 0.50 to 0.50.

The type of the rare earth metal is selected in order to preferably match the lattice constant of the functional film formed on the oxide thin film with the lattice constant of the oxide thin film.
For example, Z _0.7 R _0.3 O ₂₋ using Y as a rare earth metal
δ lattice constant was 0.515 nm. This value can be changed by the value of x. A YBCO film (lattice constant: 0.386 nm), which is a functional film described later, is a Z _0.7 R film on this film.
By rotating by 45 ° with respect to the lattice on the surface of the _0.3 O _2- δ film, the lattice is matched and can be adjusted by the value of x. However, the adjustable region of matching is x
There is a limit within the range. 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
It is possible to increase the lattice constant of the _{1-x R x O 2- δ} . By selecting the kind and amount of the rare earth in this way, it is possible to preferably match the lattice of the functional film.

The zirconium oxide containing no oxygen vacancies is represented by the chemical formula ZrO ₂ , but the amount of oxygen changes depending on the type, amount and valence of the added metal element in the zirconium oxide containing a rare earth containing Y. For this purpose, 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.

The half-width of the rocking curve of reflection of the (002) plane or the (111) plane of the oxide thin film of the present invention is 1.50 ° or less, and 80% or more, preferably 90% or more of the surface. In particular, the surface roughness (ten-point average roughness R _z ) by AFM of 95% or more is 0.6 at a reference length of 500 nm.
0 nm or less. Note that the above percentage is expressed as Zr
It is a value obtained by measuring 10 or more arbitrary locations distributed on average over the entire surface of the O ₂ thin film. Also, the RH of the oxide thin film
EED images also have high streak properties. That is, RHEED
The image is streak and sharp. As described above, the oxide thin film of the present invention has good crystallinity and good surface properties. Therefore, a high quality functional epitaxial film can be formed on the surface of the oxide thin film of the present invention. 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 a ten-point average roughness R _{z at} a rocking curve half width of about 0.7 ° and a reference length of 500 nm.
Is about 0.10 nm.

In particular, when the above-mentioned oxide thin film is an epitaxial film having a high purity of ZrO ₂ having a Zr content of 93 mol% or more in terms of only the constituent elements excluding oxygen, the conventional single-crystal oxide film is conventionally used as described above. Although a mono-oriented thin film was not obtained, the present invention was the first to obtain a ZrO ₂ thin film as a high-purity single-oriented epitaxial film having a Zr of 93 mol% or more in terms of only the constituent elements excluding oxygen.

The above-mentioned ZrO ₂ thin film preferably has a Zr content of 93 mol% or more, especially 95 mol% or more, further 98 mol% or more, and further 99.5 mol% or more, in terms of constituent elements excluding oxygen. The higher the purity, the higher the insulation resistance and the smaller the leakage current.

The upper limit of the Zr content is 99.99% at present.

The oxide thin film may contain impurities such as rare earth alloys and P at less than 7 mol%.

The crystal of the ZrO ₂ thin film has only a single orientation plane, and 80% or more, preferably 90% or more, particularly 95% or more of the surface has a ten-point average roughness at a reference length of 500 nm. Rz is 2 nm or less. In addition, when only a single orientation surface is provided as described above and the surface property is good, the interface with a functional film or the like formed thereon is good. Therefore, since the interface characteristics can be improved, satisfactory insulation properties can be maintained and good device characteristics can be obtained. In addition, as the half width of the rocking curve, the same value as described above is obtained.

The RHEED image of the ZrO ₂ thin film has a particularly high streak property. That is, the RHEED image is streak and sharp. As described above, this ZrO ₂ thin film becomes a single crystal, and when used for a dielectric layer of a MIS capacitor or the like, the physical quantity is not disturbed by grain boundaries and the like, and a good function is exhibited.

Although the thickness of the oxide thin film varies depending on the application,
The buffer layer has a thickness of 5 to 500 nm, preferably 50 to 1 nm.
It is preferably about 50 nm. The buffer layer is preferably as thin as not to impair the crystallinity and surface properties of the oxide thin film. When used as an insulating layer of an insulating substrate, 50 to 5
A thickness of about 00 nm is preferable. Further, when it is used as an oxide layer of a semiconductor device, such as a dielectric layer of a MIS capacitor or a gate oxide layer of a MISFET, it is preferable to use 0.1.
It is preferably from 5 to 50 nm, particularly preferably from 1 to 30 nm.

The functional film formed on the oxide thin film is an epitaxial film mainly having a perovskite structure, and specifically, a Bi-based oxide superconducting film, YBa ₂
High temperature superconducting film such as Cu ₃ O _7-8 (YBCO) superconducting film,
Ferroelectric films such as BaTiO ₃ , PbTiO ₃ , PZT, PLZT, other Pb-based perovskites, other Bi-based perovskites, Bi-layered compounds, and La
An oxide conductive film such as _1-x Sr _x CoO ₃ or La _1-x Sr _x Ca _x RuO ₃ may be used. In addition, In ₂ O ₃ (Sn
Dope), other oxide conductive films, Pt, Si, Ge, G
It is also suitable as a substrate for growing a film of a semiconductor or metal such as aAs.

The electronic device substrate of the present invention can have a large-area substrate having a uniform oxide 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 this substrate are extremely inexpensive as compared with the related art. There is no particular upper limit on the area of the substrate.
The mainstream is a semiconductor process using a wafer, especially a 6-inch type, which can cope with this.

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 the 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 apparatus 1 further includes an oxidizing gas supply device 7, and an 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 Zr evaporator 9 and a rare earth metal evaporator 10
Is arranged. In the Zr evaporator 9 and the rare-earth metal evaporator 10, an energy supply device for supplying energy for evaporation to a metal source such as an electron beam generator is arranged in addition to the respective metal sources. . In the drawings, P is a vacuum pump.

Hereinafter, a first method for forming an oxide thin film will be described first, and then a second method for forming an oxide thin film will be described.

In the first forming method of the present invention, first,
A single crystal substrate is set on the holder. At this time, a Si single crystal substrate is used as the single crystal substrate, and a (100) plane or a (111) plane is selected as a substrate surface on which a target oxide thin film is formed. The functional film formed on the substrate surface is a single crystal epitaxially grown,
Moreover, it is for making the crystal have an appropriate orientation. Preferably, the substrate surface is etched and cleaned using a mirror-finished wafer. 40% etching cleaning
This is performed using an ammonium fluoride aqueous solution or the like.

Next, the inside of the vacuum chamber is controlled to 10 ^-5 by a vacuum pump.
After evacuation to about Torr or more, the single crystal substrate is heated.
During heating, the single-crystal substrate is evacuated to as high a vacuum as possible to avoid oxidation. Although there is no particular upper limit for the degree of vacuum, it is usually about 5 × 10 ⁻⁶ Torr in consideration of workability. Heating temperature is Z
The temperature is preferably 400 ° C. or more for crystallization of rO ₂ , and more preferably about 750 ° C. or more, and particularly preferably 850 ° C. or more for obtaining the crystal surface of the molecular level film. Note that the upper limit of the heating temperature of the single crystal substrate is 1300 ° C.
It is about.

Next, at least Zr of Zr and rare earth metal (here, Y is taken as an example) is heated and evaporated by an electron beam or the like. At this time, the oxidizing gas described below has not yet been introduced into the vacuum chamber.

The timing of supplying Zr and Y and the oxidizing gas to the single crystal substrate must never be the oxidizing gas first. When the oxidizing gas is supplied first, the substrate surface reacts with the oxidizing gas to form an oxide layer. As a result, the crystal lattice information of the substrate is not transmitted to the film containing ZrO ₂ as a main component, and epitaxial growth becomes impossible. The optimal supply timing of oxygen is determined by converting at least Zr out of Zr and the rare earth metal into a thickness when all the metal elements reaching the substrate surface form a metal thin film, and the total amount is 5 times.
nm or less, particularly after supplying 0.01 to 5 nm is particularly desirable. The supply of Zr and the rare earth metal reduces and removes a small amount of oxides generated before film formation, and converts the substrate lattice information into ZrO _2.
Is transmitted to the film whose main component is epitaxial growth.

For example, taking the case of forming a YSZ film on a Si substrate as an example, the oxidation reaction of Zr metal and Y metal is 1
At 000 K, Zr + O ₂ = ZrO ₂ ΔG = −187.
6 (kcal / mol) 4 / 3Y + O ₂ = 2 / 3Y ₂ O ₃ ΔG = −227.
1 (kcal / mol) Both free energy changes are negative and large. That is, Z
r and Y are easily oxidized, indicating that they act as reducing agents. Assuming a solid phase reaction with SiO ₂ on the surface of the Si substrate, SiO ₂ + Zr = ZrO ₂ + Si ΔG = −43.1
29 (kcal / mol) ΔG indicates that SiO ₂ is reduced by Zr. The same applies to Y. This reaction makes it possible to remove the oxide film on the substrate surface immediately before film formation.
That is, a favorable YSZ epitaxial growth can be realized by supplying a Zr + Y metal before the YSZ film formation and thereafter supplying oxygen, Zr and Y to grow the YSZ. When the degree of non-oxidation on the substrate surface is good, the supply of the metal to the substrate by evaporation and the supply of the oxidizing gas may be performed simultaneously.

Next, a Zr metal, a rare earth metal (represented by Y in the following description) and an oxidizing gas are supplied to a single crystal substrate to obtain a thin film containing ZrO ₂ as a main component. Here, the film formation rate is desirably 0.05 to 1.00 nm / s, preferably 0.100 to 0.500 nm / s.
The reason is that if it is too slow, the substrate will be oxidized, and if it is too early, the formed thin film will have poor crystallinity and will have irregularities on the surface. Therefore, the optimum value of the film formation rate is determined by the amount of oxygen introduced. Therefore, prior to the deposition of a thin film containing ZrO ₂ as a main component, how much each of the Zr and Y metals evaporates per unit time depending on the amount of power applied to the deposition source.
Whether a vapor deposition film of r, Y, ZrO ₂ , and Y ₂ O ₃ is to be formed is measured and calibrated for each metal by a film thickness meter installed near a substrate in a vacuum vapor deposition tank. As the oxidizing gas, oxygen, ozone, atomic oxygen, and NO ₂ can be used. Here, description will be made on the assumption that oxygen is used.
Oxygen is continuously evacuated 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,
10 ^-4 to 10 ^-2 at least near the single crystal substrate in the vacuum chamber
Create an oxygen atmosphere of about Torr. 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 ⁻² Torr in order to deposit the metal source in the evaporation source in the vacuum chamber without deteriorating the metal source and 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 of the vacuum chamber has a low pressure of 10 ^-4 -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. However, the substrate area is increased to 10 cm ² or more, for example, a large single crystal substrate area of 2 inches in diameter. In order to form a film, the substrate is rotated as shown in FIG. 1 and a high oxygen partial pressure is supplied to the entire surface of the substrate, whereby 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 when the rotation speed is low, the respective composition distributions of Zr, Y, and O occur in the film thickness direction and in the plane. 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.

Rare earth metal (including Y) to ZrO ₂
Has the following effects.

ZrO ₂ alone is cubic → tetragonal →
Phase transition with monoclinic at room temperature. Stabilized zirconia is obtained by adding a rare earth metal (including Y) to stabilize a cubic crystal. In order to use ZrO ₂ as a buffer layer for growing perovskite crystals, it is preferable to use a cubic film having high symmetry. Therefore, Zr and each metal element of the rare earth metal (including Y) are separated from the evaporation source by Zr.
And vaporizing simultaneously while controlling the ratio of the rare earth metal and vapor deposition on the single crystal substrate. Here, the molar ratio of rare earth metal (including Y) / Zr from the evaporation source is preferably 0 to 3.0, and more preferably 0.25 to 1.0. Thereby, an oxide thin film having the above preferable composition ratio can be obtained.

Next, the second forming method will be described. In this method, first, a single crystal substrate is set on the holder. At this time, a Si single crystal substrate is used as the single crystal substrate, and a (100) plane or a (111) plane is selected as a substrate surface on which a target oxide thin film is formed. 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. Preferably, the substrate surface is etched and cleaned using a mirror-finished wafer.
The etching cleaning is performed with a 40% ammonium fluoride aqueous solution or the like. The Si single crystal substrate used for manufacturing the MIS capacitor of the present invention can have a substrate area of, for example, 10 cm ² or more. As a result, the MIS capacitor can be made extremely inexpensive as compared with the related art.
There is no particular upper limit on the area of the substrate, but at present, 400
It is cm ^2. As a result, a semiconductor process using a 2-inch to 8-inch Si wafer, particularly a 6-inch type, is now mainstream and can cope with this.

Since the purified Si single crystal substrate has a very high reactivity, the Si single crystal substrate is used for the purpose of protecting the substrate and growing a good epitaxial film containing ZrO ₂ as a main component. The surface is surface-treated 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 will be insufficient, and conversely, if the temperature is too low or the holding time is too long,
The Si oxide film is too thick.

When oxidizing gas is introduced, for example, when oxygen is used as oxidizing gas, the inside of the vacuum chamber is initially 1 × 10 ⁻⁷ to 1 × 10 ^−7.
It is preferable that the vacuum is set to about × 10 ⁻⁴ Torr, and the introduction of an oxidizing gas is performed so that at least the oxygen partial pressure of the atmosphere near the Si single crystal substrate becomes 1 × 10 ⁻⁴ .
The state in which the oxygen partial pressure of this atmosphere has an upper limit is a pure oxygen state, but it may be air, particularly preferably about 1 × 10 ⁻¹ Torr or less.

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.

Then, Zr and an oxidizing gas or Zr, a rare earth (including Y) metal and an oxidizing gas are supplied to the surface. In this process, the metal such as Zr is replaced by the Si
The oxide protective film is reduced and removed. 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 (including Y) and oxygen.

The surface structure was determined by reflection high-energy electron diffraction (Reflec
tion High Energy Electron Diffraction: RH
(Referred to as EED). For example, in the case of a 1 × 1 surface structure aimed at by the present invention, the electron beam incident direction is [110], and a complete streak pattern with a one-time period C1 as shown in FIG. Is exactly the same pattern when [1-10] is set. On the other hand, the Si single crystal clean surface is, for example, (1
00) plane, 1 × 2, 2 × 1, or 1 × 2 and 2 ×
1 has a mixed surface structure. In such a case, the pattern of the RHEED image has the incident direction [1] of the electron beam.
10] or [1-10] or both
1 time period C1 and 2 times period C as shown in FIG.
It becomes a pattern with 2. In the 1 × 1 surface structure of the present invention, when viewed from the above RHEED pattern, the incident directions are both [110] and [1-10], and FIG.
No double cycle C2 is seen.

In some cases, the clean Si (100) surface has a 1 × 1 structure. Although it has been observed several times in our experiments, it is impossible at present to obtain 1 × 1 on a Si-clean surface with an unclear, stable and reproducible condition showing 1 × 1.

S of any structure of 1 × 2, 2 × 1, and 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 Si (100) plane has been described above as an example, but the (111) plane has a similar structure, although the structure of the clean surface is different, and an oxide film is crystal-grown on the Si substrate. Until now, it has been impossible to stably form a suitable 1 × 1 structure.

Zr or Zr and rare earth (including Y)
The supply amount of the metal is 0.3 to 10 n in terms of the oxide.
m, particularly preferably about 3 to 7 nm. If the thickness is less than 0.3 nm, the effect of reducing the Si oxide cannot be sufficiently exhibited, and
If the thickness exceeds nm, irregularities at the atomic level are likely to occur on the surface, and the crystal arrangement on the surface may not be a 1 × 1 structure due to the irregularities. The reason for setting the preferable upper limit of the thickness of the Si oxide layer to 10 nm is as follows.
If it exceeds 0 nm, even if the metal is supplied as described above, Si
This is because there is a possibility that the oxide layer cannot be sufficiently reduced.

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 surface treatment of the Si substrate has the following effects.

The surface structure of the crystal surface in several atomic layers 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 the crystal surface of the molecular level film. Note that the upper limit of the heating temperature of the single crystal substrate is 1300
It is about ° C.

Next, Zr is heated by an electron beam or the like to evaporate. Zr metal and an oxidizing gas are supplied to the single crystal substrate. If necessary, rare earth elements (including Y) are supplied in the same manner. A thin film containing ZrO ₂ as a main component is obtained. Here, the film formation rate is desirably 0.05 to 1.00 nm / s, preferably 0.100 to 0.500 nm / s. The reason is that if it is too slow, the substrate will be oxidized, and if it is too early, the formed thin film will have poor crystallinity and will have irregularities on the surface. Therefore, the optimum value of the film formation rate is determined by the amount of oxygen introduced. Therefore, prior to the deposition of the ZrO ₂ thin film, how much the Zr metal and the rare earth metal (including Y) evaporate per unit time depending on the amount of power applied to the deposition source, and deposit the deposited films of these metals and oxides. Whether it is formed or not is measured and calibrated by a film thickness meter installed near the substrate in the vacuum evaporation tank. 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 exhausted from the chamber by a vacuum pump, and is supplied to a nozzle provided in the vacuum evaporation tank at a rate of 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 in the vicinity of the single crystal substrate in the vacuum chamber by continuously injecting an oxygen gas of about 25 cc / min. 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.

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 operation conditions, it is suitable for obtaining a target substance 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.

The electronic device substrate obtained as described above is processed, for example, by a semiconductor process with the same structure, and the DRA is obtained by substituting the conventional SiO _2.
It can be configured as a capacitor and gate for M. Furthermore, by forming Si as a functional film on this substrate, it can be applied as an SOI device,
By forming a functional film of a superconductor, a nonvolatile memory, an infrared sensor, an optical modulator, an optical switch OEIC, S
It can be applied to QUIDs, Josephson devices, superconducting transistors, electromagnetic wave sensors, and superconducting wiring LSIs.

[0073]

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, a Si single crystal which was cut and mirror-polished so that the surface became (100) plane, and cut and mirror-polished so that the surface became (111) Polished single crystal Si was used. Mirror surface is 40% after purchase
Etching cleaning was performed with an ammonium fluoride aqueous solution. Note that all the single crystal substrates used were circular substrates 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. Heat and rotate. The rotation speed is
20 rpm.

Thereafter, metals Zr and Y were simultaneously supplied from independent evaporation sources while controlling the molar ratio of Y / Zr to 0.45. At this time, no oxygen is introduced. When the supply amount reached 1 nm in terms of the film thickness of the Zr + Y alloy, oxygen gas was introduced from the nozzle at a rate of 10 cc / min to react the metal with oxygen to obtain a YSZ film of about 150 nm.

FIG. 2 shows the result of XRD (CuKα ray) measured on the thin film obtained in this example. FIG. 2 (a)
FIG. 2B is an X-ray diffraction diagram when using a substrate, and FIG. 2B is when using a substrate. In FIG. 2A, the (002) peak of the fluorite structure of YSZ is clearly observed.
Further, in FIG. 2B, the (111) peak of the fluorite structure is clearly observed, and it can be seen that a crystal film strongly oriented in the direction reflecting the crystal structure and symmetry of the substrate is obtained.

FIG. 3 shows an electron diffraction pattern showing the crystal structure of a thin film using a substrate. Here, FIG. 3A is a diffraction pattern when an electron beam is incident from the [100] direction of Si, and FIG. 3B is a diffraction pattern when an electron beam is incident from the [110] direction of the Si substrate. As can be seen from the results, the diffraction pattern of YSZ has a sharp streak shape, indicating that the film is a single crystal and the surface is flat at the atomic level. In addition, a sample of 5 × 5 mm square was cut out of the thin film using the above substrate on a straight line including the center of the thin film, and an AFM (Atomic Foam) was cut out.
rce Microscopy: Atomic force microscope). 1
FIG. 4 shows a surface image of one of the thin films. No grain boundaries are observed. It turns out that it is flat at the atomic level. In addition, using the thin film surface images of all samples, JIS
B0610 ten-point average roughness according to R _z (reference length L: 50
0 nm) was 0.16 nm on average and 0.12 m at minimum. The half width of the rocking curve was 1.2 ° on average and 1.07 ° at minimum. This crystallinity is obtained over the entire surface of the Si substrate having a diameter of 2 inches as shown in FIG.

Next, the supply amount of only the metal before the supply of oxygen,
The dependence of the crystallinity of the formed YSZ film was examined. A YSZ film was formed on a Si single crystal substrate (the (100) plane was used as the substrate surface) in the same manner as described above, and the metal supply amounts (in terms of film thickness) were changed as shown in Table 1. I let it. The results of examining the formed YSZ film by XRD (X-ray diffraction) and RHEED are shown in Table 1.

[0080]

[Table 1]

As can be seen from Table 1, when the metal supply amount is set to 5 nm or less in terms of the film thickness, a YSZ film which has been successfully epitaxially grown can be obtained.

Example 2 As a single crystal substrate on which an oxide thin film was grown, a Si single crystal cut and mirror-polished so that the surface became (100) plane, and cut and mirror-polished so that the surface became (111) A polished Si single crystal wafer was used. After the purchase, the mirror surface was cleaned by etching with a 40% ammonium fluoride aqueous solution. Note that a circular substrate having a diameter of 2 inches was used as the Si substrate.

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. The substrate is rotated at 20 rpm to protect it with a substance, and oxygen is introduced near the substrate from the nozzle.
It was heated at 600 ° C. while introducing at a rate of 5 cc / min.
Here, a Si oxide film is formed on the surface of the substrate by thermal oxidation. By this method, a Si oxide film of about 1 nm was formed.

Then, 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 a metal Zr was evaporated from the evaporation source on the substrate by:
By supplying 5 nm in terms of the thickness of the Zr metal oxide, a Si surface-treated substrate having a 1 × 1 surface structure was obtained. b. By evaporating metal Zr from the evaporation source on the substrate,
By supplying 5 nm in terms of the thickness of the r metal oxide, a Si surface-treated substrate having a 1 × 1 surface structure was obtained. c The metal Zr and Y are evaporated on the substrate while suppressing the molar ratio of Y / Zr to 0.22 to 5 nm in terms of oxide film thickness.
Then, a Si surface-treated substrate having a 1 × 1 surface structure was obtained. FIGS. 6 to 8 show diagrams of these surfaces measured by RHEED.

All of these were measured in the direction of incidence [110], and the same pattern was obtained even when rotated by 90 °. That is, S having a stable 1 × 1 surface structure
It is confirmed that an i-surface treated substrate has been obtained.

Further, metal Zr is supplied from the evaporation source onto the Si surface-treated substrate in a state where the substrate temperature is 900 ° C., the rotation speed is 20 rpm, and oxygen gas is introduced from the nozzle at a rate of 25 cc / min. A 50 nm thick ZrO ₂ film
Obtained on the substrates a and b. By supplying Zr and Y from the evaporation source under the same conditions on the c-treated substrate, a 50 nm-thick YSZ (Zr _0.92 Y _0.18 O ₂ -δ) film was obtained.

X measured for the three types of obtained thin films
The results of the line are shown in FIGS. The figure shows the ZrO ₂ (00
2) Peak (FIG. 9), YSZ (002) peak (FIG. 1)
1) is clearly observed. In FIG. 10, the (111) peak of ZrO ₂ completely overlaps the peak of the Si substrate. It can be seen that a crystal film strongly oriented in the direction reflecting the crystal structures and symmetry of ZrO ₂ and YSZ was obtained. In particular, these peaks are reflections from only one reflection surface, respectively. 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 widths of the rocking curves of this reflection are 0.7 ° (actual value) and 0.8 ° (actual value), respectively.
It was 0.7 ° (actual measurement value including the Si substrate), and it was confirmed that the orientation was excellent.

FIGS. 12 to 14 show the RHE of this thin film.
ED (Reflection High Energy Electron Diffraction
) Shows the pattern. The incident direction of the electron beam is [1] on the Si substrate.
10] direction. As can be seen from the results, the diffraction pattern on the surface of the thin film having this structure is a completely streak pattern, which is completely different from the pattern in which the streak is partially close to a spot in the conventional example. This completely streak pattern is ZrO ₂
Is excellent in crystallinity and surface properties. In addition, as a result of measuring the resistivity of the ZrO ₂ film and the YSZ, it was found that the resistivity was 5 times higher than that of the YSZ and the insulating property was excellent. In addition, with respect to three types of films, JIS was applied to almost all of the surfaces at 10 locations.
Ten-point average roughness Rz according to B0610 (reference length L: 50
0 nm), the Zr on the Si (100) substrate was measured.
The average of the O ₂ film is 0.70 nm, the maximum is 0.95 nm, the minimum is 0.10, and the average of the ZrO ₂ film on the Si (111) substrate is 0.80 nm, the maximum is 1.00 nm, and the minimum is 0.08. ,
0.75n on average for YSZ film on Si (100) substrate
m, 0.80 nm at the maximum, and 0.12 at the minimum, and were flat at the molecular level.

The Y of the YSZ film is represented by Pr, Ce, Nd,
When Gd, Tb, Dy, Ho, Er, etc. were changed, the same results as above were obtained.

[0090]

According to the manufacturing method of the present invention, an oxide thin film containing ZrO ₂ as a main component has high reproducibility with good reproducibility under an operating condition in which there is no room for impurities to be present on a Si single crystal and the control is easy. Furthermore, it can be formed over a large area over the entire surface of a substrate having a diameter of 2 inches or more, and is of high industrial value.

[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.

FIGS. 2A and 2B are X-ray diffraction diagrams of a YSZ thin film obtained on a single crystal substrate. FIGS. 2A and 2B each show a Si single crystal ((100) plane used) single crystal substrate as a single crystal substrate. And a Si single crystal (using (111) plane) single crystal substrate.

FIG. 3 is a drawing substitute photograph showing a crystal structure of a thin film,
FIG. 2A shows a reflection high-speed electron diffraction pattern of the YSZ film shown in FIG. 2A, where FIG. 2A shows the case where an electron beam is incident from the [100] direction of the Si single crystal substrate, and FIG.
It is a diffraction pattern when an electron beam enters from the [110] direction of the i single crystal substrate.

FIG. 4 is a drawing substitute photograph showing a crystal structure of a thin film,
3 is a thin-film surface image of the YSZ film shown in FIG. 2A by an atomic force microscope.

FIG. 5 is a graph showing the ten-point average roughness Rz of the YSZ film and the half-width of a rocking curve along the entire diameter of the wafer according to the example.

FIG. 6 is a drawing substitute photograph showing the surface structure of the Si substrate a in Example 2 having a 1 × 1 surface structure formed by Zr metal and oxygen, showing a RHEED pattern, It is a diffraction pattern in which an electron beam was incident from the crystal [110] direction.

FIG. 7 is a drawing substitute photograph showing the surface structure of the Si substrate b in Example 2 having a 1 × 1 surface structure formed by Zr metal and oxygen, showing a RHEED pattern, It is a diffraction pattern in which an electron beam was incident from the crystal [110] direction.

FIG. 8 shows 1 formed by Zr metal, Y metal and oxygen.
14 is a drawing substitute photograph showing the surface structure of the Si substrate c in Example 2 having a × 1 surface structure, which shows a RHEED pattern and is a diffraction pattern in which an electron beam is incident from the Si single crystal [110] direction. It is.

FIG. 9 is an X-ray diffraction diagram of a film structure of ZrO ₂ obtained on a Si (100) substrate.

FIG. 10 is an X-ray diffraction diagram of a film structure of ZrO ₂ obtained on a Si (111) substrate.

FIG. 11 is an X-ray diffraction diagram of a YSZ film structure obtained on a Si (100) substrate.

FIG. 12 is a drawing substitute photograph showing the crystal structure of ZrO ₂ obtained on a Si (100) substrate, showing a RHEED diffraction pattern when an electron beam is incident from [110] on a Si single crystal substrate. It is.

FIG. 13 is a drawing substitute photograph showing the crystal structure of ZrO ₂ obtained on a Si (111) substrate, showing a RHEED diffraction pattern when an electron beam is incident from [110] on a Si single crystal substrate. It is.

FIG. 14 is a drawing substitute photograph showing the crystal structure of YSZ obtained on a Si (100) substrate, showing a RHEED diffraction pattern when an electron beam is incident from [110] on a Si single crystal substrate. is there.

FIG. 15A is a schematic diagram illustrating a RHEED pattern having a 1 × 1 surface structure, and FIG. 15B is a schematic diagram illustrating 2 × 1, 1 ×.
2 or R of the surface structure when they are mixed
It is a schematic diagram which shows a HEED pattern.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Evaporation 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 Zr evaporator 10 Rare earth metal evaporator

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-82585 (JP, A) Proc. SPIE Int. SoC. Opt. Eng. , 1187, p. 47-56, (1989) (58) Fields investigated (Int. Cl. ⁷ , DB name) C30B 1/00-35/00 H01L 21/20 H01L 21/314 INSPEC (DIALOG)

Claims (18)

(57) [Claims] 1. A method of forming a composition Zr on a Si single crystal substrate.
_1-x R _x O ₂ -δ (where R is a rare earth metal containing Y, x = 0 to 0.75, and δ is 0 to 0.5). The rocking curve of reflection of the (002) plane or the (111) plane has a half-width of 1.5 ° or less, and at least 80% of the surface has a ten-point average roughness _Rz at a reference length of 500 nm. An oxide thin film having a thickness of 0.60 nm or less. 2. A composition Z formed on a Si single crystal substrate.
a single orientation epitaxial film of rO ₂ , wherein the single orientation epitaxial film contains 93% or more of Zr in terms of only a constituent element excluding oxygen, and the (002) plane or (111) 1.) The half width of the rocking curve of the surface reflection is 1.
An oxide thin film in which at least 80% of the surface of the single-oriented epitaxial film has a ten-point average roughness Rz at a reference length of 500 nm of 2 nm or less. 3. A Si surface-treated substrate having a 1 × 1 surface structure formed of Zr metal and oxygen as the Si single crystal substrate.
Oxide thin film. 4. An Si single crystal as the single crystal substrate,
4. The oxide thin film according to claim 1, wherein the (100) plane or the (111) plane is used as a substrate surface. 5. The oxide thin film according to claim 1, which has an area of 10 cm ² or more. 6. An electronic device substrate having the oxide thin film according to claim 1 on a substrate surface. 7. A composition Z formed on a single crystal substrate of Si.
r _1-x R _x O ₂₋ δ (where R is a rare earth metal containing Y and x = 0 to 0.75; and δ is 0 to 0.5)
It is. A) a method of forming an oxide thin film which is an epitaxial film, wherein the inside of a vacuum chamber is initially evacuated to 1 × 10 ⁻⁵ Torr or more, and in this state, the Si single crystal substrate is heated to a predetermined temperature; Zr and at least one of the at least one rare earth metal (including Y) each metal element are simultaneously evaporated from separate evaporation sources while controlling the ratio of Zr to the rare earth metal to form a single crystal substrate surface. An oxidizing gas is introduced into the vacuum chamber at the same time or after a predetermined time delay with the supply of the metal, and the atmosphere in the vacuum chamber at least in the vicinity of the single crystal substrate is reduced to 1 × 10 ⁻⁴ to 1 ×. 10 ^-2 Torr
Forming an oxide thin film on the substrate surface of the single crystal substrate by epitaxial growth. 8. A predetermined time from supply of the metal by evaporation to introduction of the oxidizing gas is a time corresponding to 5 nm or less in terms of a thickness of a metal thin film formed on the single crystal substrate. 7. The method for forming an oxide thin film according to item 7. 9. A rare earth metal (including Y) from an evaporation source /
9. The method for forming an oxide thin film according to claim 7, wherein the Zr molar ratio is controlled from 0 to 3 while simultaneously evaporating. 10. A rare earth metal (including Y) from an evaporation source
10. The method for forming an oxide thin film according to claim 9, wherein the evaporation is performed simultaneously while controlling the molar ratio of / Zr from 0.25 to 1.0. 11. Composition Z formed on Si single crystal substrate
r _1-x R _x O ₂₋ δ (where R is a rare earth metal containing Y and x = 0 to 0.75; and δ is 0 to 0.5)
It is. A) heating a single crystal Si substrate in a vacuum layer, introducing an oxidizing gas into the vacuum layer, and at least one of Zr or Zr in a vacuum layer. Supplying the rare earth metal (including Y) by evaporation to the surface of the single crystal substrate, and epitaxially growing the oxide thin film on the substrate surface of the single crystal substrate to form a single oriented epitaxial film having the composition described above. A method for forming an oxide thin film, comprising: 12. A Si surface having a 1 × 1 surface structure formed of Zr or Zr and at least one rare earth metal (including Y) and oxygen as the Si single crystal substrate. 12. A processing substrate is used.
The method for forming an oxide thin film. 13. As the Si surface-treated substrate, a 0.2-10 nm Si oxide layer is formed on the surface of the substrate.
Thereafter, the substrate temperature is set to 600 to 1200 ° C., and an oxidizing gas is introduced into the vacuum chamber to at least set the atmosphere near the substrate to 1 × 10 ^-4 to 1 × 10 ^-1 Torr.
In this state, Zr or Zr and at least one rare earth metal (Y) are formed on the surface of the substrate on which the Si oxide layer is formed.
The method for forming an oxide thin film according to any one of claims 7 to 12, wherein the pretreated Si single crystal substrate is supplied by evaporating. 14. When forming the Si oxide, the Si single crystal substrate is placed in a vacuum chamber into which an oxidizing gas has been introduced.
14. The method for forming an oxide thin film according to claim 13, wherein the Si oxide layer is formed by heating to 700 ° 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. 15. The method for forming an oxide thin film according to claim 7, wherein a Si single crystal is used as the Si single crystal substrate so that the (100) plane or the (111) plane becomes the substrate surface. . 16. 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 formed only in the vicinity of the single crystal substrate. The method for forming an oxide thin film according to any one of the above. 17. The Si single crystal substrate having a substrate surface area of 10 cm ² or more and rotating in the substrate to provide the oxidizing gas high partial pressure atmosphere over the entire single crystal substrate. 17. The method for forming an oxide thin film according to claim 7, wherein a substantially uniform oxide thin film is formed over the entire surface of the single crystal substrate. 18. When forming the epitaxial film,
8. The method according to claim 7, wherein the Si single crystal substrate is heated to 750.degree.
20. The method for forming an oxide thin film according to any one of the above items.