JPH0955486A - Soi device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance an SOI device in reliability using an insulating layer of high quality by a method wherein a zirconium oxide film or an epitaxial zirconium oxide film stabilized by rare earth metal is formed as an insulating layer on a single-crystal Si substrate, and an Si film is formed on the epitaxial film. SOLUTION: A thin film transistor is equipped with a single-crystal Si substrate 1, an insulating layer 2 formed on the substrate 1, and an Si semiconductor thin film 3 formed thereon. The insulating layer 2 of the SOI device is formed on the surface of the single-crystal Si substrate 1 and made up with zirconium oxide or epitaxial zirconium oxide stabilized by rare earth metal. The insulating layer 2 is high in crystallinity and surface properties and excellent in lattice matching and wettability to Si. Therefore, an Si film can be enhanced in semiconductor properties.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SOI (Sil) semiconductor device having a Si single crystal substrate / insulating layer / Si film structure.
icon on Insulator) Devices and manufacturing methods thereof.

[0002]

2. Description of the Related Art With the progress of semiconductor technology in recent years, many semiconductor devices and methods for manufacturing the same have been proposed which enable high integration.

Hitherto, an SOS (Silicon on Sapphire) structure has been used to form a semiconductor element on an insulating substrate. This is a technique for forming a semiconductor thin film on a sapphire single crystal substrate.

However, in this technique, when a semiconductor thin film is formed, aluminum and oxygen, which are a part of the composition of sapphire, are taken into the semiconductor thin film, which sometimes deteriorates the electrical characteristics of the semiconductor thin film as impurities. It was Also, epitaxially grow a semiconductor thin film,
When trying to obtain a high-quality Si film, the lattice constants of Si and sapphire of the substrate do not match, a large amount of defects are introduced, and the crystallinity of the semiconductor thin film deteriorates. further,
Sapphire substrates are expensive and not suitable for mass production of devices.

Therefore, in order to avoid the problem of using sapphire as a substrate, in Japanese Patent Laid-Open Nos. 63-15442, 6-97401, 2-5567 and 6-85264, there are disclosed , An SOI (Silicon on Insulator) structure has been proposed in which an insulating layer is formed on a Si single crystal substrate and a Si semiconductor layer which is a functional layer is formed on the insulating layer.

This SOI structure enables high integration by manufacturing a semiconductor element in a Si single crystal substrate on which an integrated circuit is formed and a semiconductor thin film formed on the Si single crystal substrate via an insulating layer. . Further, in general, miniaturization of wiring is unavoidable as the integration density of LSI progresses. In this wiring, the wiring distributed resistance, interwiring capacitance, wiring-substrate capacitance, and the capacitance of the transistor itself constitute a CR distributed constant circuit, which causes a problem of signal delay and attenuation. In the semiconductor element formed on the insulating substrate, since the semiconductor element is formed on the insulating substrate, the capacitance between the wiring and the substrate can be reduced mainly, and the speed can be increased.

In addition, in such an SOI structure, a MOS
FE using the structure and structure peculiar to semiconductors such as pn connection
By providing T, CMOS type transistors, bipolar transistors, and the like, SOI devices such as display devices, high-voltage devices, three-dimensional circuit elements, and solar cells can be realized.

[0008]

However, in the SOI structure disclosed in each of the above patent publications, it is considered that the quality of the insulating layer used, that is, mainly the crystallinity and the surface property are not sufficient. S formed on it
It is presumed that it may be difficult to sufficiently bring out the characteristics of the functional layer by the i film. Incidentally, the above-mentioned JP-A-63-1544.
Japanese Unexamined Patent Publication No. 2 discloses a technique of forming a Si film on a stabilized zirconia single crystal film formed on a Si single crystal substrate. Although it uses a commonly used oxide forming method and is capable of epitaxial growth, a stabilized zirconia film having high crystallinity, high surface flatness, and excellent insulating properties cannot be obtained. For device applications, it is necessary to realize thin films with high crystallinity, high surface flatness, and excellent insulating properties.

Further, the Si film formed on the stabilized zirconia single crystal film is also an epitaxial film, but since the crystallinity and surface flatness of the stabilized zirconia film are not good, it was used as a functional layer. At this time, it is considered that the crystallinity of the Si film is poor, the interface of the stabilized zirconia / S is disturbed, and the insulating property of the stabilized zirconia film is insufficient, so that the semiconductor characteristics of the Si film cannot be sufficiently obtained.

In view of the above, it is an object of the present invention to provide an SOI device which enables high reliability by using a high quality insulating layer, and a manufacturing method thereof.

[0011]

The above objects are achieved by the present invention described in (1) to (19) below. (1) Si single crystal substrate, zirconium oxide or zirconium oxide epitaxial film stabilized with rare earth metal (including Y) formed as an insulating layer on the Si single crystal substrate, and formed on this epitaxial film Device with a patterned Si film. (2) The composition of zirconium oxide or zirconium oxide stabilized with a rare earth metal has a composition of Zr _1-x R _x O ₂ -δ.
(Here, R is a rare earth metal containing Y, and x = 0 to
0.75. Further, δ is 0 to 0.5. ) The SOI device according to (1) above. (3) The SOI device according to (1) or (2) above, which has a thin film transistor structure in which a gate electrode is formed on the Si film via a gate insulating film. (4) The half value width of the rocking curve of reflection on the (002) plane or the (111) plane of the epitaxial film is 1.
The SOI according to any one of the above (1) to (3), which is 5 ° or less
device. (5) At least 80 of the surface of the epitaxial film
% Is the SOI device according to any one of the above (1) to (4), wherein the ten-point average roughness R _z at a reference length of 500 nm is 2 nm or less. (6) The epitaxial film contains Zr in an amount of 93 mol% or more in terms of only constituent elements except oxygen (1).
The SOI device according to any one of (5) to (5). (7) The SOI device according to any one of (1) to (6) above, wherein the Si film is made of epitaxial Si. (8) The SOI device according to any one of (1) to (6) above, wherein the Si film is made of polycrystalline Si. (9) The SOI device according to any one of (1) to (6) above, wherein the Si film is made of amorphous Si. (10) As the Si single crystal substrate, the substrate surface is formed of Zr metal or Zr metal and at least one rare earth metal (including Y) and oxygen 1 ×
The SOI device according to any one of (1) to (9) above, which uses a Si surface-treated substrate having a surface structure of 1. (11) A Si single crystal is used as the Si single crystal substrate.
The SOI according to any one of (1) to (10) above, wherein the (100) plane or the (111) plane is used as a substrate surface.
device. (12) In a method for manufacturing an SOI device comprising a Si single crystal substrate, an insulating layer formed on this Si single crystal substrate, and a Si film formed on this insulating layer, in the vacuum layer, the Si single crystal substrate The surface of the single crystal substrate by heating the single crystal substrate, introducing an oxidizing gas into the vacuum layer, and supplying Zr or Zr and at least one rare earth metal (including Y) to the surface of the single crystal substrate by evaporation. And the composition of Zr _1-x R _x O _2- δ by epitaxially growing the oxide thin film.
(Here, R is a rare earth metal containing Y, and x = 0 to
0.75. Further, δ is 0 to 0.5. 4.) A method for manufacturing an SOI device, wherein the single-oriented epitaxial film of 1) is formed and the insulating film is used as the insulating layer. (13) As the Si single crystal substrate, a Si surface-treated substrate whose surface has a 1 × 1 surface structure formed by Zr or Zr and at least one rare earth metal (including Y) and oxygen The method for manufacturing an SOI device according to (12) above, which uses. (14) As the Si surface-treated substrate, a Si oxide layer having a thickness of 0.2 to 10 nm is formed on the surface of the substrate, and thereafter, the substrate temperature is set to 600 to 1200 ° C. and oxidation is performed in the vacuum chamber. Gas at least in the vicinity of the substrate is set to 1 × 10 ⁻⁴ to 1 × 10 ⁻¹ Torr by introducing a reactive gas, and in this state, on the substrate surface on which the Si oxide layer is formed,
The method for manufacturing an SOI device according to (12) or (13) above, wherein Zr or Zr and at least one rare earth metal (including Y) are supplied by evaporation and a pretreated Si single crystal substrate is used. (15) When the Si oxide is formed, the Si single crystal substrate is set to 300 to 700 in a vacuum chamber into which an oxidizing gas is introduced.
The method for manufacturing an SOI device according to (14) 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. (16) A Si single crystal is used as the Si single crystal substrate.
The SO according to any one of (12) to (15), which is used so that the (100) plane or the (111) plane becomes the substrate surface.
I device manufacturing method. (17) An oxidizing gas is injected from the vicinity of the surface of the Si single crystal substrate to create an atmosphere having a higher partial pressure of the oxidizing gas than other portions only in the vicinity of the single crystal substrate.
The method for manufacturing an SOI device according to any one of 2) to 16). (18) The Si single crystal substrate has a substrate surface area of 10
cm ² or more, and by rotating in the substrate, the oxidizing gas high partial pressure atmosphere is provided over the entire single crystal substrate, and substantially uniform oxidation is performed over the entire surface of the single crystal substrate. (1) to form a thin film
The method for manufacturing an SOI device according to any one of 2) to 17). (19) When the epitaxial film is formed, the S
i) heating the single crystal substrate to 750 ° C. or higher (12) to
The method for manufacturing an SOI device according to any one of (18).

[0012]

The present invention provides a Si single crystal substrate and a composition Zr _1-x R _x O ₂ -δ formed on this Si single crystal substrate.
An SOI device such as a thin film transistor is constituted by a structure including an insulating layer which is an epitaxial film of 1. and a Si film formed on the insulating layer. Composition Zr _1-x R
_{The xO 2-} δ epitaxial film is stable at high temperatures and does not contaminate the Si film by being reduced at high temperatures unlike sapphire. Further, the insulating property is high, and the Si film and the Si of the substrate can be completely insulated. Further, the lattice constant is close to that of Si, and the crystallinity of the Si semiconductor thin film is improved. Furthermore, the surface of the epitaxial film having the composition Zr _1-x R _x O _2- δ is flat at the molecular level, and the continuity of the Si film formed thereon is high. Furthermore, the effect of reducing the residual stress, which is considered to be due to the difference in the thermal expansion coefficient between the Si single crystal substrate and the epitaxial film having the composition Zr _1-x R _x O _2- δ, was confirmed. Although details are unknown, this effect is remarkable especially in the composition film in the vicinity of x of 0, and it is speculated that the residual stress with Si is reduced by the phase transition of ZrO ₂ .

From the above, the SOI device of the present invention is
The performance of the device for each application can be increased.

[0014]

Concrete Structure The SOI device of the present invention can be applied to, for example, a thin film transistor (TFT). An example of the basic structure is shown in FIG. This TFT includes a Si single crystal substrate 1, an insulating layer 2 formed on the Si single crystal substrate 1, a Si semiconductor thin film 3 formed on the insulating layer 2, source and drain electrodes 4 and 5, and a gate insulating layer. 6 and a gate electrode 7 formed on the gate insulating layer 6.

The insulating layer in the SOI device of the present invention is formed on the surface of a Si single crystal substrate and has a composition substantially stabilized by zirconium oxide or a rare earth metal zirconium oxide {generally the 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 is x
, And Jan. J. Appl. Phys. Two
7 (8) L1404-L1405 (1988), Zr in small regions where x is less than 0.2.
_1-x R _x O _2- δ becomes a tetragonal crystal. Above that,
It becomes cubic. Although a mono-oriented epitaxial film is obtained in the cubic region, in the small region where x is less than 0.2, J. Appln. Phys. 58 (6) 2407-
As described in 2409 (1985), the other oriented surface to be obtained is mixed, and a single oriented epitaxial film is not obtained.

Therefore, it is preferable that the crystal of the insulating layer is a cubic crystal and has a single crystallinity.
In the SOI device of the present invention, epitaxial Si may be provided as a functional layer on the surface of the insulating layer, but in this case, the cubic crystal is more regularly arranged than the tetragonal crystal in the insulating layer. This is because it is easy to epitaxially grow Si formed on top. Further, a grain boundary exists in a thin film having a plurality of crystal planes, and when a high electric field is applied to the thin film, local electric field concentration occurs in the grain boundary, and the thin film is likely to deteriorate.

On the other hand, in the region where x exceeds 0.75, cubic crystals are present, but planes other than the intended crystal plane are mixed. For example, when trying to obtain a (100) epitaxial film of Zr _1-x R _x O ₂ -δ, (111) crystals are mixed in this range.

That is, x is 0 to 0.75, preferably 0.2 to 0.50 in Zr _1-x R _x O ₂ -δ from the range in which cubic crystals can be formed and the range in which a target crystal plane is obtained. Within the range, an excellent epitaxial film as an insulating layer film can be obtained.

Further, in particular, even when the insulating layer film is an epitaxial film having a high-purity composition ZrO ₂ in which Zr is 93 mol% or more in terms of only constituent elements except oxygen, it is also a single-oriented epitaxial film. It is preferable. Conventionally, Z
In the case of an epitaxial film having a high-purity composition ZrO ₂ with r of 93 mol% or more, a single orientation has not been obtained so far, but the present inventors first converted it to only constituent elements except oxygen. As a result, a single oriented film of an epitaxial film having a high-purity composition ZrO ₂ with Zr of 93 mol% or more was obtained.

Incidentally, the epitaxial film mentioned here means
If the substrate surface of the film is the XY plane and the film thickness direction is the Z axis,
The crystals are aligned in the X-axis, Y-axis, and Z-axis directions, and the intensity other than the desired reflection in the X-ray or electron diffraction measured from each direction is the maximum intensity of the desired surface. Says 5% or less. For example, in the (001) epitaxial film, that is, the c-plane epitaxial film, the reflection intensity of the film other than the (001) plane in the 2θ-θX-ray diffraction of the film is
A film having a maximum peak intensity of (001) plane reflection of 5% or less and showing a spot or streak pattern in RHEED evaluation can be said to be a (001) epitaxial film. The same applies to the (111) epitaxial film.

Further, the term "single orientation film" as used herein refers to a crystallized film in which target crystal planes are aligned parallel to the substrate surface, and for example, (001) single orientation film, that is, c-plane single orientation film. Then, the 2θ-θX-ray diffraction of the film means that the reflection intensity other than the (001) plane is 5% or less of the maximum peak intensity of the (001) plane reflection. Similarly, in the (111) single orientation film, the reflection intensity other than the (111) plane is 5% or less of the maximum peak intensity of the (111) plane reflection.

In the ZrO ₂ thin film, it is preferable that Zr is 93 mol% or more, particularly 95 mol% or more, further 98 mol% or more, further 99.5 mol% or more in terms of constituent elements except oxygen. The higher the purity, the higher the insulation resistance and the smaller the leak current. Therefore, it is particularly preferable for use in the insulating layer film.

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, Zr _0.7 R _0.3 O using Y as a rare earth metal
The lattice constant of _2- δ was 0.515 nm. This value can be changed by the value of x. If a YBCO film (lattice constant 0.386 nm), which will be described later, is provided on this film as a functional film, the angle is 45 ° with respect to the lattice on the surface of the Zr _0.7 R _0.3 O ₂ δ film.
By rotating, the grid matches and can be adjusted by the value of x. However, there is a limit when the adjustable range of matching is within the range of x. Therefore, matching can be enabled by changing the type of rare earth. For example, Pr of rare earth is used instead of Y. At this time, the lattice constant of Zr _1-x R _x O ₂ -δ can be increased, and the matching with the Si crystal can be optimized. By thus selecting the type and amount of rare earth, it is possible to preferably match with the lattice of the functional film.

The upper limit of the Zr content is currently 99.99%. The insulating layer film is less than 7 mol% P
It may contain impurities such as.

Zirconium oxide containing no oxygen deficiency is represented by the chemical formula ZrO ₂ , but the amount of oxygen in zirconium oxide containing rare earth elements containing Y varies depending on the type, amount and valence of the added metal element. Therefore, the composition of the oxide thin film of the present invention is represented by the chemical formulas Zr _1-x R _x O _2- δ and δ. δ is usually about 0 to 0.5.

The full width at half maximum of the rocking curve of reflection of the (002) plane or the (111) plane of the above-mentioned insulating layer film of the present invention is preferably 1.50 ° or less.
0% or more, preferably 90% or more, particularly 95% or more A
The surface roughness (ten-point average roughness R _z ) by FM is the reference length 5
It is preferably 2 nm or less at 00 nm. The above percentages are values obtained by measuring 10 or more arbitrary points evenly distributed over the entire surface of the thin film. Further, the RHEED image of the insulating layer film also 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 surface properties. There is no particular lower limit to the full width at half maximum of the rocking curve and the ten-point average roughness R _z at the reference length of 500 nm, but the smaller the lower limit, the better. At present, the lower limit value is such that the half-width of the rocking curve is about 0.7 ° and the ten-point average roughness R _z at a reference length of 500 nm is about 0.10 nm.

In the SOI device of the present invention, the substrate surface of the Si single crystal substrate, that is, the thin film forming surface side is shallowly oxidized (for example, about 5 nm or less), and SiO ₂ is added.
And other layers may be formed. This is because oxygen in the ZrO ₂ thin film may diffuse to the substrate surface of the Si single crystal substrate. In addition, depending on the method of film formation, ZrO
_{2 When} forming a thin film, the Si oxide layer may remain on the surface of the Si substrate.

The thickness of the Zr _1-x R _x O ₂ -δ thin film is 0.5.
.About.500 nm, preferably about 1 to 300 nm, and for SOI devices that require particularly insulating properties, a thick film thickness of 50 to 500 nm is selected.

When the composition Zr _1-x R _x O ₂ -δ epitaxial film described above is used as the insulating layer film of the SOI device of the present invention, the physical quantity is not disturbed by grain boundaries, and a good function is exhibited. .

The Si semiconductor film formed on the insulating layer described above is preferably composed of an Si film which is an epitaxial Si film, a polycrystalline Si film, or an amorphous Si film.

In an SOI device having a Si semiconductor film composed of an epitaxial Si film, since the substrate on which the Si film is formed is covered with the epitaxial film containing ZrO ₂ as a main component, impurities in the Si semiconductor film, for example, , Conventional S
Al, which is an impurity from sapphire in the OS structure, is reduced, and the semiconductor film characteristics (eg, mobility) of the Si film are improved. Also, the matching of the thermal expansion coefficients of ZrO ₂ and Si reduces the stress in the Si film and improves the crystallinity of the Si epitaxial film. Thus, since a high quality Si semiconductor film can be obtained on the insulating substrate, the present invention is further effective when applied to a bipolar CMOS device or the like including the TFT of the example of the SOI device of FIG. When an epitaxial film containing ZrO ₂ having a high purity as a main component is used for the insulating layer, the insulating property is particularly improved, and the IC is formed on the bulk Si substrate.
A three-dimensional device is also possible by producing

Further, in an SOI device having a Si semiconductor film made of polycrystalline Si, the polycrystalline Si is oriented in Si (100) because the insulating layer film has high crystallinity.
Therefore, since there are few grain boundaries connected in the in-plane direction of the film, semiconductor characteristics (for example, leak current, switching characteristics, etc.) in the in-plane direction in the polycrystalline Si film are improved.

S composed of amorphous Si
In an SOI device including an i semiconductor film, its semiconductor characteristics are greatly affected by the flatness of the interface and surface of the amorphous Si film and the substrate and the continuity of the film. The insulating layer film in the SOI device of the present invention is, as described above,
It has excellent flatness and has only irregularities at the molecular level. Therefore, the amorphous Si formed on top of it is ZrO ₂
The interface with the insulating layer film containing as a main component is flat, and the surface irregularities are extremely small. Further, the wettability between ZrO ₂ and Si is good, and the continuity is excellent even with a thin film thickness. Therefore,
Due to the effect of ZrO _2, an excellent amorphous Si film can be obtained. For example, when a TFT is formed, an element having excellent switching characteristics can be manufactured.

The Si film as described above has a thickness of 5 to 2000 nm.
The film thickness is selected in each SOI device application.

TF which is one of the SOI devices of the present invention
In the T element, it is preferable to use an epitaxial or polycrystalline Si film having a thickness of about 100 to 500 nm. In the TFT device using the amorphous Si film, 5 to 5
It is preferable to use a thin film of about 0 nm. The thinner, the T
It is possible to reduce the leakage current of the FT element,
Considering the film quality, about several tens of nm is particularly preferable.

The source electrode, the drain electrode and the gate electrode may be made of a usual material used in SOI devices, and are preferably made of Al, Si or the like.

The gate insulating layer may be formed of a usual material used in SOI devices, for example, SiO.
It is preferably formed of ₂ , Si ₃ N ₄ , ZrO _2, or the like.

Next, the method of manufacturing the SOI device of the present invention will be described in detail, centering on the method of forming the insulating layer and the Si semiconductor film.

In carrying out the forming method of the present invention, it is desirable to use the vapor deposition device 11 as shown in FIG.

The vapor deposition apparatus 11 has a vacuum chamber 11a, and in the vacuum chamber 11a, a holder 13 for holding the single crystal substrate 12 is arranged at the bottom. The holder 13 is connected to a motor 15 via a rotary shaft 14, and is rotated by the motor 15 so that the single crystal substrate 12 can be rotated within the substrate surface.
A heater 16 for heating the single crystal substrate 12 is built in the holder 13.

The vapor deposition device 11 also includes an oxidizing gas supply device 17, and the oxidizing gas supply port 18 of the oxidizing gas supply device 17 is arranged immediately below the holder 13. Thus, the partial pressure of the oxidizing gas is increased near the single crystal substrate 12.
Below the holder 13, a Zr evaporation unit 19 and a rare earth metal evaporation unit 20 are arranged. In addition to the respective metal sources, an energy supply device for supplying energy for vaporization to a metal source such as an electron beam generator is arranged in the Zr vaporization part 19 and the rare earth metal vaporization part 20. . In the figure, P is a vacuum pump.

The method of forming the insulating layer film will be described below.

In this method, first, the single crystal substrate is set in the holder. At this time, a Si single crystal substrate is used as the single crystal substrate, and the (100) plane or the (11) plane is used as the substrate surface on which the target insulating layer film is formed.
1) A face is selected. This is because the insulating layer film formed on the substrate surface is a single crystal epitaxially grown, and the crystal has an appropriate orientation. It is preferable that the surface of the substrate is cleaned by etching using a mirror-finished wafer. Etching cleaning is performed with a 40% ammonium fluoride aqueous solution or the like. At this time, the Si single crystal substrate can have a substrate area of, for example, 10 cm ² or more. As a result, the SOI device can be made extremely inexpensive as compared with the conventional one. Although there is no particular upper limit on the area of the substrate, it is currently about 400 cm ² . As a result, semiconductor processes using Si wafers of 2 to 8 inches, particularly 6-inch type, are currently the mainstream, and it is possible to cope with this.

Since the cleaned Si single crystal substrate has extremely high reactivity, the Zr _1-x R _{x is used for} the purpose of protecting it.
For the purpose of growing a good epitaxial film containing O _{2 −} δ as a main component, the substrate surface of the Si single crystal substrate 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. As the oxidizing gas, oxygen, ozone, atomic oxygen,
NO ₂ or the like can be used. Since the substrate surface of the cleaned Si single crystal substrate is extremely reactive as described above, it is used as a protective film to protect the Si single crystal substrate surface from rearrangement and contamination. The layer thickness of the Si oxide layer is preferably about 0.2 to 10 nm.
This is because 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 heating is carried out at a temperature of 300 to 700 ° C. for about 0 to 10 minutes. At this time, the rate of temperature rise is about 30 to 70 ° C./minute. The temperature is too high,
If the heating rate 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 becomes too thick.

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

After the above steps, heating is performed in vacuum. Since the Si surface crystal is protected by the protective film, there is no contamination such as reaction with the residual gas hydrocarbon to form the SiC film.

The heating temperature is 600 to 1200 ° C., especially 7
The temperature is preferably set to 00 to 1100 ° C. If it is less 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, the protective film will cause Si
The surface crystal is not sufficiently protected and the crystallinity of the Si single crystal substrate is disturbed.

Then, Zr and an oxidizing gas or Zr and a rare earth (including Y) metal and an oxidizing gas are supplied to the surface. In this process, the metal such as Zr is the Si formed in the previous step.
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 and a rare earth metal (including Y) and oxygen.

The surface structure is a reflection high-energy electron diffraction (Refle
ction High Energy Electron Diffraction: RH
It can be examined by the pattern of the image by EED). For example, in the case of the 1 × 1 surface structure which is the object of the present invention, the electron beam incident direction is [110], and a perfect streak pattern with a 1 × period C1 as shown in FIG. The same pattern can be obtained by changing [1 -10]. On the other hand, the Si single crystal clean surface has, for example, a surface structure of 1 × 2, 2 × 1, or a mixture of 1 × 2 and 2 × 1 in the case of the (100) plane. In such a case, the pattern of the RHEED image has a 1 × period as shown in FIG. 3B in either the electron beam incident direction [110] or [1 -10] or both. The pattern has C1 and a double cycle C2. In the 1 × 1 surface structure of the present invention, the double cycle C2 of FIG. 3B is not seen in both the [110] and [1-10] incident directions as seen in the RHEED pattern.

The Si (100) clean surface has a size of 1 × 1.
May show structure. Although it was observed several times in our experiments, it is impossible at present to obtain 1 × 1 on a clean Si surface with unclear and stable reproducibility under the condition of 1 × 1.

S of either 1 × 2, 2 × 1, or 1 × 1 structure
The i clean surface is easily contaminated at high temperature in vacuum, and particularly reacts with hydrocarbons contained in the residual gas to form SiC on the surface, and the crystals on the substrate surface are disturbed. Therefore, it has hitherto been impossible to stably form a 1 × 1 structure suitable for crystal growth of an oxide film on a Si substrate.

Although the Si (100) plane has been described above as an example, basically the same phenomenon appears in the (111) plane, although the structure of the clean plane is different, and an oxide film is crystal-grown on the Si substrate. It has heretofore been impossible to stably form a suitable 1 × 1 structure.

Zr or Zr and rare earth (including Y)
The amount of metal supplied is 0.3 to 10 nm in terms of its oxide.
Particularly, about 3 to 7 is preferable. If it is less than 0.3 nm, the effect of reducing Si oxide cannot be sufficiently exerted, and if it exceeds 10 nm, unevenness at the atomic level tends to occur on the surface, and the crystal array on the surface has a 1 × 1 structure due to unevenness. This is because it may not be The reason why the preferable upper limit of the thickness of the Si oxide layer is 10 nm is that if the thickness exceeds 10 nm, the Si oxide layer may not be sufficiently reduced even if a metal is supplied as described above. Because it will come out.

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

The above Si substrate surface treatment has the following effects.

The surface structure of several atomic layers on the crystal surface is
It is generally different from the atomic arrangement structure of a virtual surface that is considered when a bulk (three-dimensional large crystal) crystal structure is cut. This is because the situation around the atoms appearing on the surface changes due to the disappearance of the crystal on one side, and in response to this, a stable state with lower energy is attempted. The structural change is mainly limited to relaxation of atomic position, and atomic recombination occurs to form a rearranged structure. The former is present on most crystal surfaces. The latter generally forms the superlattice structure of the surface. When the unit vector size of the bulk surface structure is a and b, when a superlattice structure of ma and nb is generated, this 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 complicated superstructure with a large unit mesh of 7 × 7 or 2 × 8 structure. In addition, these cleaned S
The i surface is highly reactive, and especially at the temperature (700 ° C. or higher) at which an oxide thin film is epitaxially formed, it reacts with residual gas in a vacuum, especially hydrocarbons, and Si
The formation of C pollutes the substrate surface and disturbs the surface crystals.

In order to epitaxially grow an oxide on a Si substrate, the structure of the Si surface must be stable and the crystal structure information must be transmitted to the growing oxide film. In oxide epitaxial film crystal,
Since the atomic arrangement structure considered when the bulk crystal structure is cut 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 x7 or 2x8 structure are not preferred and a stable 1x1 structure is required. Further, since epitaxial growth is performed at a temperature of 700 ° C. or higher, it is necessary to protect the highly 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 the single-oriented epitaxial film containing ZrO ₂ as a main component, first, the surface-treated Si single crystal substrate is heated. The heating temperature during film formation is preferably 400 ° C. or higher for crystallization of ZrO ₂ .
Further, about 750 ° C. or higher has excellent crystallinity, and particularly 850 ° C. or higher is preferable in order to obtain the crystal level flatness of the molecular level film. Note that the upper limit of the heating temperature of the single crystal substrate is 1300.
It is about ℃.

Next, Zr is heated by an electron beam or the like to evaporate. Zr metal and oxidizing gas are supplied to the single crystal substrate. If necessary, rare earths (including Y) are also supplied by the same method. A thin film containing ZrO ₂ as a main component is obtained. ZrO
_{2 A} simple substance undergoes a phase transition with a monoclinic crystal from a high temperature to a cubic crystal → a tetragonal crystal → room temperature. Stabilized zirconia is obtained by adding a rare earth metal (including Y) in order to stabilize the cubic crystal. In order to use ZrO ₂ as a buffer layer for crystal growth of epitaxial Si or the like, it is preferable to use a cubic film having high symmetry. Therefore, each metal element of Zr and rare earth metal (including Y) is simultaneously evaporated from separate evaporation sources while controlling the ratio of Zr / rare earth metal to be deposited on the single crystal substrate. Here, the rare earth metal (Y
Is preferred) / Zr molar ratio is 0 to 3.0, preferably 0.25 to 1.0. This allows
An oxide thin film having the above preferable composition ratio can be obtained.
Here, the film formation rate is 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 fast, the crystallinity of the formed thin film will be poor and unevenness will occur on the surface. Therefore, the optimum film formation rate is determined by the amount of oxygen introduced. Therefore, prior to the vapor deposition of the ZrO ₂ thin film, the Zr metal and the rare earth metal (including Y) evaporate per unit time depending on the power amount condition applied to the vapor deposition source, and the vapor deposited film of those metals and oxides is formed. Whether or not it is formed is measured and calibrated by a film thickness meter installed near the substrate in the vacuum deposition tank. As the oxidizing gas, oxygen, ozone, atomic oxygen, NO ₂ or the like can be used. Here, it is assumed that oxygen is used below. Oxygen gas is continuously evacuated with a vacuum pump while continuously ejecting 2 to 50 cc / min, preferably 5 to 25 cc / min of oxygen gas through a nozzle provided in the vacuum vapor deposition tub, and a vacuum tub is provided. An oxygen atmosphere of about 10 ^-3 to 10 ^-1 Torr is created at least in the vicinity of the single crystal substrate. The optimum 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 obtained in advance. Here, the upper limit of the oxygen gas pressure is set to 10 ^-1 Torr in order to deposit the metal source in the evaporation source in the same vacuum chamber without degrading it and to keep the evaporation rate constant. Further, when introducing oxygen gas into the vacuum vapor deposition tank, it is preferable to inject oxygen gas onto the surface of the single crystal substrate from its vicinity to create an atmosphere with a high oxygen partial pressure only near the single crystal substrate, and to reduce oxygen The amount introduced can further promote the reaction on the substrate. At this time, since 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, the diameter is 2
Figure 1
By rotating the substrate as described above and supplying a high oxygen partial pressure to the entire surface of the substrate, a film can be formed in a large area. At this time, the rotation speed of the substrate is preferably 10 rpm or more. This is because when the rotation speed is slow, a film thickness distribution occurs in the substrate surface. There is no particular upper limit to the rotation speed of the substrate, but it is usually about 120 rpm due to the mechanism of the vacuum device.

Although the details of the manufacturing method have been described above, this manufacturing method has no room for inclusion of impurities and is controlled, as is particularly clear in comparison with the conventional vacuum 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 substance having high reproducibility and high integrity in a large area. Furthermore, this method is
Even if the BE apparatus is used, the target thin film can be obtained in exactly the same manner.

Since the single-oriented epitaxial film obtained as described above is used as an insulating layer of an SOI device, thereafter, a Si semiconductor film as a functional film, source and drain electrodes are formed by using a normal semiconductor manufacturing technique. The gate insulating film, the gate electrode, etc. are formed to be an SOI device.

In the present invention, it is particularly preferable that the functional film is an epitaxial Si film. This epitaxial Si film is formed by vacuum vapor deposition, sputtering,
It can be formed by any of the laser ablation method, the CVD method, the MBE method, etc., but the method of forming the insulating layer film described above can be used almost as it is, except for introducing the oxidizing gas.

In this case, the degree of vacuum in the vacuum chamber is set to 10 ^-9 Torr.
It is possible to form a film by using the ordinary MBE growth conditions as they are with the following ultra-high vacuum. Although it may be about 10 ⁻⁷ Torr, in this case, the substrate temperature needs to be increased to about 1000 ° C. and the film formation rate needs to be decreased to about 0.05 nm / sec.

[0069]

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

In manufacturing the SOI device, the vapor deposition apparatus having the structure shown in FIG. 2 was used.

Example 1 As a single crystal substrate on which an insulating layer film was grown, a Si single crystal cut and mirror-polished so that its surface became a (100) plane, and a mirror surface was cut so that its surface became a (111) plane. Polished single crystal Si was used. After purchase, the mirror surface was cleaned by etching with a 40% ammonium fluoride aqueous solution. As the single crystal substrate, a circular substrate having a diameter of 2 inches was used.

The above single crystal substrate was fixed to a substrate holder equipped with a rotation and heating mechanism installed in a vacuum chamber, the vacuum deposition chamber was evacuated to 10 ^-6 Torr by an oil diffusion pump, and then the substrate was heated to 850 ° C. Heat and spin. The rotation speed is
It was set to 20 rpm.

Thereafter, the metals Zr and Y were simultaneously supplied from independent evaporation sources while controlling the Y / Zr molar ratio to 0.45. At this time, oxygen is not introduced. When the supply amount is converted to the film thickness of Zr + Y alloy and reaches 1 nm, oxygen gas is introduced from the nozzle at a rate of 10 cc / min, and metal and oxygen are reacted to form an oxide thin film that is a YSZ film of about 10 nm. Obtained.

The results of XRD (CuKα ray) measured on the oxide thin film obtained in this example are shown in FIG. FIG.
4A is an X-ray diffraction diagram when the substrate is used, and FIG. 4B is an X-ray diffraction diagram when the substrate is used. Y in FIG.
The (002) peak of the fluorite structure of SZ is clearly observed, and the (111) peak of the fluorite structure is clearly observed in FIG. 4B, which shows the crystal structure and symmetry of the substrate. It can be seen that a crystal film strongly oriented in the reflected direction is obtained.

Furthermore, FIG. 5 shows an electron beam diffraction pattern showing the crystal structure of the thin film when the substrate is used. Here, FIG. 5A is a diffraction pattern when an electron beam is incident from the [100] direction of Si, and FIG. 5B is a diffraction pattern when it is incident from the [110] direction of a Si substrate. As can be seen from these results, since the diffraction pattern of YSZ has a sharp streak shape, it is clear that the film is a single crystal and its surface is flat at the atomic level. In addition, a thin film using the above substrate was cut into a 5 × 5 mm square sample on a straight line including the center of the thin film, and AFM (Atomic Foam)
rce Microscopy: Atomic force microscope). The surface image is shown in FIG. No grain boundaries are observed. this is,
The same was true when a substrate was used. It can be seen that it is flat at the atomic level. Also, using the thin film surface images of all the samples, the ten-point average roughness R according to JIS B0610
_{When z} (reference length L: 500 nm) was measured, it was 0.17 nm on average and 0.12 m at the minimum. The half-width of the rocking curve is 1.0 ° on average and 0.9 at the minimum.
°. From these, it was confirmed that the entire surface of the sample was a sample excellent in surface property and crystallinity.

Example 2 Further, as the single crystal substrate, similarly to the above, the surface was cut so as to have the (100) plane, the mirror-polished Si single crystal, and the surface was cut so as to have the (111) plane. A mirror-polished Si single crystal wafer was used. After purchase, the mirror surface was cleaned by etching with a 40% ammonium fluoride aqueous solution. A circular substrate having a diameter of 2 inches was used as the Si substrate.

The above single crystal substrate was fixed to a substrate holder equipped with a rotation and heating mechanism installed in a vacuum chamber, the vacuum deposition chamber was evacuated to 10 ^-6 Torr by an oil diffusion pump, and the substrate cleaning surface was oxidized with Si. The substrate is rotated at 20 rpm to protect it with an object, and oxygen is passed from the nozzle to the vicinity of the substrate at 2 rpm.
It was heated at 600 ° C. while being introduced at a rate of 5 cc / min.
Here, a Si oxide film is formed on the surface of the substrate by thermal oxidation. A Si oxide film of about 1 nm was formed by this method.

Then, thereafter, the substrate was heated to 900 ° C. and rotated. The rotation speed was 20 rpm. At this time, oxygen gas is introduced from the nozzle at a rate of 25 cc / min, and a metal Zr is evaporated from the evaporation source on the substrate,
By supplying 5 nm in terms of the film thickness of the Zr metal oxide, a Si surface-treated substrate having a 1 × 1 surface structure was obtained. b By evaporating the metal Zr from the evaporation source on the substrate, Z
By supplying 5 nm in terms of the film thickness of the r metal oxide, a Si surface-treated substrate having a 1 × 1 surface structure was obtained. c When the metals Zr and Y are evaporated on the substrate while suppressing the molar ratio of Y / Zr to 0.22, the oxide film thickness is converted to 5 nm.
It was supplied to obtain a Si surface-treated substrate having a 1 × 1 surface structure. Figures 7 to 9 show views of these surfaces measured by RHEED.

All of these were measured in the incident direction [110], but the patterns were exactly the same even when rotated by 90 °. That is, S having a stable 1 × 1 surface structure
It is confirmed that the i surface-treated substrate is obtained.

Further, on the Si surface-treated substrate, 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
It was obtained on the above-mentioned a and b treated substrates. Further, by supplying Zr and Y from the evaporation source to the c-treated substrate under the same conditions, a YSZ (Zr _0.92 Y _0.18 O ₂ -δ) film having a film thickness of 10 nm was obtained.

X measured on the three kinds of thin films obtained
The results of the line diffraction are shown in FIGS. In the figure, the (002) peak of ZrO ₂ (FIG. 10) and the YSZ (002) peak (FIG. 12) are observed. In FIG. 11, 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 structure and symmetry of ZrO ₂ and YSZ is obtained. In particular, these peaks are reflections from only one reflecting surface, and it can be seen that the ZrO ₂ film is a unidirectionally highly crystalline film, which is not seen in the conventional example. Furthermore, the half-widths of the rocking curves of this reflection are 0.8 ° (measured value), 0.9 ° (measured value),
It was confirmed that the orientation was 0.8 ° (measured value including the Si substrate) and the orientation was excellent.

Further, the RHE of this thin film is shown in FIGS.
ED (Reflection High Energy Electron Diffraction
) Indicates a pattern. The incident direction of the electron beam is [1 on the Si substrate.
10] direction. As can be seen from this result, the diffraction pattern on the surface of the thin film of this structure is a completely streak pattern, which is completely different from the pattern in which the streak is partially close to a spot as seen in the conventional example. This completely streak pattern is ZrO ₂
Indicates that it has excellent crystallinity and surface property. Further, as a result of measuring the resistivity of the ZrO ₂ film and the YSZ film, it was found that ZrO ₂ exhibited a resistance 5 times higher than that of YSZ and was excellent in insulation. Further, the ten-point average roughness Rz (reference length L: 500 nm) according to JIS B0610 was measured at ten locations on almost the entire surface of each of the three types of films,

For a ZrO ₂ film on a Si (100) substrate, the average is 0.65 nm, the maximum is 0.90 nm, and the minimum is 0.10 n.
On the average, the ZrO ₂ film on the Si (111) substrate has a thickness of 0.
80nm, 0.90nm at maximum, 0.10nm at minimum, and 0.7 on average for YSZ film on Si (100) substrate.
It was flat at the molecular level, with 0 nm, 0.90 nm at maximum, and 0.12 nm at minimum.

It should be noted that Y in the YSZ film is Pr, Ce, Nd,
When replaced with Gd, Tb, Dy, Ho, Er, etc., the same results as above were obtained.

Then, Zr on the above Si (100) substrate
On the O ₂ film (insulating layer film), a Si semiconductor film (hereinafter sometimes referred to as Si film) as a functional layer was formed.

In this example, three types of Si films were produced.
In order to obtain an epitaxial Si film for Sample No. 1, a 200 nm Si film was formed at a substrate temperature of 900 ° C. and a film formation rate of 0.05 nm / sec using an MBE method. Atmospheric pressure CVD to obtain polycrystalline Si for sample No. 2
Method, SiH ₄ (concentration 1%) diluted with H ₂ was used to form a 200 nm polycrystalline Si film at a substrate temperature of 700 ° C., and further, a hydroxylation treatment was performed by hydrogen plasma. For sample No. 3, in order to obtain amorphous Si, plasma CVD is used to
A film having a substrate temperature of 300 ° C. and a thickness of 10 nm was formed using H ₄ gas.
The results of evaluating these Si films by RHEED are shown in FIG.
18. In (a), a streak pattern is observed, which shows that Si is epitaxially grown on ZrO ₂ . In (b), a spot pattern of Si is observed. It can be seen that the spot has a ring shape and is a polycrystalline film. In particular, it can be seen that this film has a strong crystal orientation because the ring is close to the spot, and is excellent in crystallinity. In (c), it has a halo pattern and is in an amorphous state.

Next, such three kinds of Si films are used for the TFT.
Process into The structure of the TFT is shown in FIG. This structure is called a planar type in TFT.
A source electrode and a drain electrode made of Al were formed on the Si film to have a thickness of 50 nm by sputtering and patterned by etching. In order to make ohmic contact between the Al electrode and the Si semiconductor film, n-type conductive Si was used. Furthermore, by plasma CVD method, SiO
_Two films having a thickness of 200 nm were formed to serve as a gate insulating film. After patterning the gate insulating film, Al was deposited to a thickness of 50 nm. The Al film is etched to form a gate electrode, and sample No. 1
The TFT element of No. 3 was used.

Sample N using an epitaxial Si film
The TFT device of No. 1 showed good transistor characteristics, and the electron mobility of 200 nm epitaxial Si using sapphire as the substrate was 200 cm ² / Vs, while in this embodiment it was 400 cm ² / Vs. Double mobility was obtained. When p-type conductive Si was used, the hole mobility was also 100 cm ² / Vs when the sapphire substrate was used.
In the present invention, it was 200 cm ² / Vs. This is because the substrate of the Si film in this example is formed of ZrO ₂ , so that there are few impurities (for example, Al when a sapphire substrate is used) and stress in the Si film due to ZrO ₂ and Si thermal expansion matching. It is considered that the crystallinity of the Si epitaxial film is improved by the effect of the reduction of In addition, although a thin film FET is manufactured in this embodiment, since a high quality Si film can be obtained on an insulating substrate as described above, the effect can be further utilized when applied to a bipolar CMOS device. The ZrO ₂ layer also has excellent insulating properties, and a three-dimensional device can be realized by producing an IC on a bulk Si substrate.

T of sample No. 2 using a polycrystalline Si film
In the ET element, a large difference was observed in the leak current, in particular, as compared with the conventional TFT made of polycrystalline Si using a quartz substrate as the substrate. When 5 V is applied between the drain and the source and the gate voltage is 0 V, a comparison is made with a TFT manufactured by using quartz in exactly the same manner as the present embodiment.
^-12 A / μm, whereas in the present invention 9.5 × 1
The leak current was small, about 0 to ¹³ and an order of magnitude. It is considered that since the polycrystalline Si of the present embodiment is oriented to Si (100), there are few grain boundaries connected in the in-plane direction of the film, so that a leak current path is hard to be formed between the source and the drain.

Sample No. 3 using amorphous Si
In the TFT element of, the comparison was made with the conventional FET formed on glass. The FET on glass was also manufactured by the same process and conditions as in this example. Here, the amorphous Si film is
The film thickness (10 nm) is thinner than the film thickness used for a normal TFT. This has the effect of reducing leakage due to photoconductivity of the TFT. A large difference was observed in the ratio of ON current / OFF current when comparing TFTs made of amorphous Si.
In order to use the TFT as a switching element, a high ON / OFF ratio is required. 5 for TFT on glass
Although it was less than a digit, the present invention could take a ratio of 6 digits. The amorphous Si film used this time is 10
As thin as nm. Therefore, the interface and surface irregularities and the continuity of the film greatly affect the TFT characteristics. ZrO _{2 of the} present invention
As described above, the film has excellent flatness and has only irregularities at the molecular level, so the amorphous Si formed on it
Has a flat interface with ZrO ₂ and has no surface irregularities.
Further, the wettability of ZrO ₂ and Si is good, and the continuity is excellent even with a thin film thickness. Therefore, due to the effect of ZrO ₂
A film is obtained, and the TFT characteristics are excellent.

Further, three kinds of Si semiconductor films were formed on the other four kinds of substrates of Examples 1 and 2 in the same manner as described above to prepare TFT samples.
00) Almost the same effect as the TFT obtained by producing a Si semiconductor film as a functional layer on the ZrO ₂ film (insulating layer film) on the substrate was obtained.

[0092]

As described above, S using the epitaxially grown Zr _{1 -X} R _X O ₂ -δ thin film according to the present invention is used.
In the OI device, the insulating layer film made of Zr _{1 -X} R _X O ₂ -δ has high crystallinity and surface property, and is suitable for lattice matching with Si, matching of thermal expansion coefficient with Si, and wettability with Si. Is also excellent, the semiconductor characteristics of the Si film formed on the insulating layer film are improved. Therefore, the transistor characteristics of the SOI device can be improved. Specifically, when an epitaxial Si film is used, the mobility of the semiconductor can be increased, so that not only excellent FET characteristics can be obtained, but also bipolar CMOS and 3 A three-dimensional device can be easily realized. Further, when a polycrystalline Si film is used, an SOI device with less leakage can be obtained, and when amorphous Si is used, an SOI device having excellent switching characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing a basic structure of a TFT which is an example of an SOI device of the present invention.

FIG. 2 is a diagram showing an example of a vapor deposition apparatus used in the method for manufacturing an SOI device of the present invention.

FIG. 3A is a schematic view showing a RHEED pattern of a 1 × 1 surface structure, and FIG. 3B is a schematic diagram showing 2 × 1, 1 × 2,
Or RHE of the surface structure when these are mixed
It is a schematic diagram which shows an ED pattern.

FIG. 4 is an X-ray diffraction diagram of a YSZ thin film obtained on a single crystal substrate, wherein (a) and (b) are Si single crystal (using (100) plane) single crystal substrate as a single crystal substrate. And a Si single crystal (using (111) plane) single crystal substrate.

FIG. 5 is a drawing-substitute photograph showing the crystal structure of a thin film,
FIG. 5 is a reflection high-energy electron beam diffraction pattern of the YSZ film shown in FIG. 4A, where FIG. 4A shows an electron beam incident from the [100] direction of a Si single crystal substrate, and FIG.
3 is a diffraction pattern when an electron beam is incident from the [110] direction of the i single crystal substrate.

FIG. 6 is a drawing-substitute photograph showing the crystal structure of a thin film,
FIG. 5 is a thin film surface image of the YSZ film shown in FIG. 4A by an atomic force microscope.

FIG. 7 is a drawing-substituting photograph showing the surface structure of the Si substrate of 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 is incident from the crystal [110] direction.

8 is a drawing-substituting photograph showing the surface structure of the Si substrate of 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 is incident from the crystal [110] direction.

FIG. 9: 1 formed by Zr metal, Y metal and oxygen
It is a drawing-substituting photograph showing the surface structure of the Si substrate of c in Example 2 having the surface structure of × 1 and showing a RHEED pattern, which is a diffraction pattern in which an electron beam is incident from the Si single crystal [110] direction. Is.

FIG. 10 is an X-ray diffraction diagram of a ZrO ₂ film structure obtained on a Si (100) substrate.

FIG. 11 is an X-ray diffraction diagram of a ZrO ₂ film structure obtained on a Si (111) substrate.

FIG. 12 is an X-ray diffraction diagram of a YSZ film structure obtained on a Si (100) substrate.

FIG. 13 is a drawing-substituting 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] of a Si single crystal substrate. Is.

FIG. 14 is a drawing-substituting photograph showing a crystal structure of ZrO ₂ obtained on a Si (111) substrate, showing a RHEED diffraction pattern when an electron beam is incident from [110] of a Si single crystal substrate. Is.

FIG. 15 is a drawing-substituting photograph showing a crystal structure of YSZ obtained on a Si (100) substrate, showing a RHEED diffraction pattern when an electron beam is incident from [110] of a Si single crystal substrate. is there.

FIG. 16: Sample No. formed on the ZrO ₂ insulating layer
2 is a drawing-substituting photograph showing the surface structure of the epitaxial Si film for No. 1, showing a RHEED pattern,
It is a figure which shows the diffraction pattern when an electron beam injects from [110] of a Si single crystal substrate.

FIG. 17: Sample No. formed on the ZrO ₂ insulating layer
It is a drawing-substitute photograph showing the surface structure of a polycrystalline Si film for No. 2, showing a RHEED pattern, showing a diffraction pattern when an electron beam is incident from [110] of a Si single crystal substrate. .

FIG. 18 is a sample No. formed on the ZrO ₂ insulating layer.
3 is a drawing-substituting photograph showing the surface structure of an amorphous Si film for No. 3, showing a RHEED pattern, S
It is a figure which shows the diffraction pattern when an electron beam injects from [110] of an i single crystal substrate.

[Explanation of symbols]

 1 Si Single Crystal Substrate 2 Insulating Layer 3 Si Semiconductor Film 4 Source Electrode 5 Drain Electrode 6 Gate Insulating Film 7 Gate Electrode 11 Vapor Deposition Device 11a Vacuum Chamber 12 Single Crystal Substrate 13 Holder 14 Rotating Shaft 15 Motor 16 Heater 17 Oxidizing Gas Supply Device 18 Oxidizing Gas Supply Port 19 Zr Evaporator 20 Rare Earth Metal Evaporator

Claims (19)

[Claims] 1. A Si single crystal substrate, an epitaxial film of zirconium oxide stabilized with zirconium oxide or a rare earth metal (including Y) formed as an insulating layer on the Si single crystal substrate, and on the epitaxial film An SOI device having a Si film formed on the substrate. 2. The composition of the zirconium oxide or zirconium oxide stabilized with a rare earth metal has a composition of Zr _1-x R _x.
O _{2 −} δ (where R is a rare earth metal containing Y, and x =
It is 0 to 0.75. Further, δ is 0 to 0.5. )
The SOI device of claim 1, wherein 3. The SOI device according to claim 1, which has a thin film transistor structure in which a gate electrode is formed on the Si film via a gate insulating film. 4. The SOI device according to claim 1, wherein a half-width of a rocking curve of reflection on the (002) plane or the (111) plane of the epitaxial film is 1.5 ° or less. 5. The SOI device according to claim 1, wherein at least 80% of the surface of the epitaxial film has a ten-point average roughness R _z at a reference length of 500 nm of 2 nm or less. 6. The SOI device according to claim 1, wherein the epitaxial film contains 93 mol% or more of Zr in terms of only constituent elements except oxygen. 7. The SOI device according to claim 1, wherein the Si film is made of epitaxial Si. 8. The SOI device according to claim 1, wherein the Si film is made of polycrystalline Si. 9. The SOI device according to claim 1, wherein the Si film is made of amorphous Si. 10. The Si single crystal substrate has a substrate surface having a 1 × 1 surface structure formed by Zr metal or Zr metal and at least one rare earth metal (including Y) and oxygen. The SOI device according to claim 1, wherein a Si surface-treated substrate is used. 11. The SOI according to claim 1, wherein a Si single crystal is used as the Si single crystal substrate such that the (100) plane or the (111) plane becomes the substrate surface.
device. 12. A Si single crystal substrate, an insulating layer formed on the Si single crystal substrate, and Si formed on the insulating layer.
In a method for manufacturing an SOI device including a film, heating a Si single crystal substrate in a vacuum layer, introducing an oxidizing gas into the vacuum layer, and Zr or Zr and at least one rare earth metal (including Y). Is supplied to the surface of the single crystal substrate by evaporation, and the oxide thin film is epitaxially grown on the surface of the single crystal substrate to form a composition Zr _1-x R _x O _2-
δ (where R is a rare earth metal containing Y, and x = 0 to
0.75. Further, δ is 0 to 0.5. 4.) A method for manufacturing an SOI device, wherein the single-oriented epitaxial film of 1) is formed and the insulating film is used as the insulating layer. 13. The Si single crystal substrate, wherein the surface of the substrate is a Si surface having a 1 × 1 surface structure formed by Zr or Zr and at least one rare earth metal (including Y) and oxygen. 13. A processed substrate is used.
Method for manufacturing SOI device. 14. As the Si surface-treated substrate, a Si oxide layer of 0.2 to 10 nm is formed on the surface of the substrate,
After that, the substrate temperature is set to 600 to 1200 ° C., an oxidizing gas is introduced into the vacuum chamber to set the atmosphere at least near the substrate to 1 × 10 ⁻⁴ to 1 × 10 ⁻¹ Torr,
In this condition, Zr or Zr and at least one rare earth metal (Y
The method for manufacturing an SOI device according to claim 12 or 13, wherein a pre-processed Si single crystal substrate is supplied by evaporation. 15. When the Si oxide is formed, a Si single crystal substrate of 300 to 300 is formed in a vacuum chamber into which an oxidizing gas is introduced.
15. The method for manufacturing an SOI device according to claim 14, 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. 16. The SO single crystal substrate according to claim 12, wherein a Si single crystal is used as the Si single crystal substrate such that the (100) plane or the (111) plane becomes the substrate surface.
I device manufacturing method. 17. The surface of the Si single crystal substrate is injected with an oxidizing gas from the vicinity thereof to create an atmosphere having a higher partial pressure of the oxidizing gas than other portions only in the vicinity of the single crystal substrate. A method for manufacturing an SOI device according to any one of 1. 18. The Si single crystal substrate has a substrate surface area of 10 cm ² or more, and is rotated in the substrate to provide the oxidizing gas high partial pressure atmosphere over the entire single crystal substrate. The method for manufacturing an SOI device according to claim 12, wherein a substantially uniform oxide thin film is formed over the entire surface of the single crystal substrate. 19. When forming the epitaxial film,
2. The Si single crystal substrate is heated to 750 ° C. or higher.
The manufacturing method of the SOI device in any one of 2-18.