JPH01219162A - Production of thin oxide film and apparatus therefor - Google Patents

Abstract

PURPOSE:To produce the title thin oxide film having density approximating that of a bulk and having a uniform composition by depositing the vaporized raw material on a substrate, and simultaneously projecting oxygen ion beam drawn out with the energy in a specified range on the deposit. CONSTITUTION:The inside of a film forming chamber 11 is evacuated to a high vacuum, gaseous oxygen is introduced from the gas inlet 4 of an ion source 12, and K-cell vapor-deposition sources 10 and 10' or a electron beam vapor- deposition source 9 are vapor-deposited on the substrate 3. The oxygen ion generated in a plasma chamber 14 and drawn out with the energy of 10-500eV or a neutral oxygen ion beam is projected on the deposit on the substrate 3. Since a molecular beam and an oxygen ion beam can be independently and stably generated, the composition of the respective elements including oxygen can be accurately controlled. By this method, the process can be simplified, and the characteristics of the thin oxide film can be improved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to superconducting elements, optical elements, and piezoelectric elements.

The present invention relates to an apparatus and method for manufacturing various oxide thin films used in surface elastic elements and the like.

[Prior Art] The best conventional method for producing oxide thin films is sputtering. As shown in Fig. 3, the sputtering device generates plasma by electric discharge between opposing electrode plates, and causes ions to collide with a target 1 placed on one of the electrode plates.At this time, atoms or atoms sputtered from the target 1 are This is an apparatus for manufacturing a thin film by depositing molecules on a substrate 3 on an electrode plate (substrate holder) 2 placed opposite a target 1. At this time, a sputtering gas such as Ar is introduced from the gas inlet 4 and exhausted from the exhaust port 5.

Generally, an oxide thin film is produced by using a desired oxide as a target material and mixing O2 gas into Ar sputtering gas.

However, in the above-mentioned sputtering method, the control of the oxygen amount depends on the oxygen partial pressure, and it also varies greatly depending on the substrate temperature, so the control of the oxygen amount is not sufficient, and the reproducibility is not sufficient due to changes in the target composition ratio over time, etc. There was a drawback that it was not.

Further, crystal defects including such oxygen defects reduce the density of the film, causing a reduction in film properties such as a reduction in electric breakdown voltage.

In addition to the sputtering method, an apparatus has been published that obtains an oxide film by incorporating an ion source 6 such as a Kauffman type as shown in FIG. , J. Martin;
Material 5science, Volume 21, 1-
25, 1985). This device is provided with an evaporation source 7 at the lower part of the device, and a substance from the evaporation source 7 is evaporated onto a substrate 3 placed on an electrode plate (substrate holder) 2.
At this time, oxygen ion irradiation is performed from the ion source 6 to produce an oxide film free of oxygen defects. In addition,
In FIG. 4, 4 is a gas inlet and 5 is an exhaust port.

In such an apparatus, a filament 8 made of tungsten or the like is used in the Kauffman ion source 6 for emitting thermionic electrons to generate plasma. Oxygen gas pressure during ion source operation is 1 x 10-'T
Since the vacuum is lower than orr, if a filament is used, the life until the ion source stops operating due to filament breakage is short, about several hours, and the filament diameter becomes thinner with time until the filament breaks, so the ion current The change in value over time is large and irregular. Therefore, in the apparatus shown in FIG. 4, it has been impossible to control the amount of oxygen irradiation with sufficient accuracy.

Furthermore, the apparatus shown in Figure 4 uses a resistance heating boat type evaporation source or an electron beam evaporation source as the evaporation source, and does not have a mechanism for stabilizing the evaporated molecular beam intensity, so the shape of the evaporated material changes during evaporation. The evaporation molecular beam intensity is highly unstable due to changes over time. Therefore, in addition to the above-mentioned inaccuracy in the amount of oxygen, the composition of evaporated elements other than oxygen is also inaccurate, making it impossible to sufficiently control the elemental composition of the produced thin paper.

[Problems to be Solved by the Invention] The present invention solves the conventional drawbacks of difficulty in controlling the amount of oxygen, insufficient reproducibility of film composition, and a large number of crystal defects. It is an object of the present invention to manufacture an oxide thin film having a similar density and no compositional deviation, and to provide an apparatus for the same.

[Means for Solving the Problems] In order to achieve such an object, the present invention apparatus includes a substrate holder for supporting and heating a substrate disposed in a film forming chamber, and a material to be deposited on the substrate. and an ion source that generates plasma and irradiates the thin film to be deposited on the substrate with an oxygen ion beam extracted from the plasma in the same manner as the deposition.

The method of the present invention uses the above-mentioned oxide thin film manufacturing apparatus,
In a vacuum higher than I It is characterized by irradiation with acceleration to a constant energy in the range of ~500 eV.

[Function] The oxide thin film manufacturing apparatus according to the present invention generates plasma using microwaves, and generates a voltage of lθ to 500 eV from the plasma.
The device has an ion source that extracts oxygen ions with energy of 200 mL, and can irradiate the thin film deposited on the substrate in vacuum with oxygen ions at the same time as the deposition.

According to the present invention, a thin film is deposited on a substrate by molecular beam evaporation with good composition controllability, and the deposited film on the substrate is irradiated with an oxygen ion beam or a neutral oxygen beam at an energy of lθ to 500 eV. can produce oxide thin films without crystal defects. Therefore, an oxide 119 film with good composition control and no crystal defects can be obtained.

FIG. 1 is a schematic diagram of a specific example of an oxide thin film manufacturing apparatus according to the present invention. The apparatus for producing an oxide thin film of the present invention is a Knudsen cell (a molecular beam source) which is a molecular beam source for filling thin film raw materials, which are raw materials for an oxide thin film, and evaporating them using molecular beams.
k-cell) 10.10' and an electron beam evaporation source 9 for evaporating other thin materials. Then, the microwaves generated by the microwave source 13 are guided to the plasma chamber 14 to generate oxygen plasma, extract oxygen ions with an energy of 10 to 500 eV, and irradiate the substrate 3 on the substrate holder 2 with oxygen ions. The ion source 12 is equipped with an ion source 12 that performs the following steps. Although only two k-cells are shown, it is of course possible to provide three or more.

Inside the film forming chamber 11, a monitor 15, such as a crystal resonator or an ion cage, is provided to monitor the intensity of the molecular beam, and a Faraday cup 16 is provided to monitor ions.

Further, an electron emission source 17 such as a thermionic filament is provided between the ion irradiation port of the ion source 12 and the substrate 3, and when forming an insulating film on the substrate 3, irradiates ions or electrons to the substrate 3. It is possible to prevent the deposited film from being charged.

The oxide thin film manufacturing apparatus according to the present invention operates as follows. First, the film forming chamber 11 is brought to a high vacuum (higher vacuum than 1x 1O-5 Torr) using a cryopump or the like. After that, oxygen gas is introduced from the gas inlet 4 of the ion τ source 12, and the gas pressure (lxlO-5 to I
degree of vacuum up to O-3 Torr) e.g. 2×10-'Torr
Oxygen gas is introduced until the temperature reaches rr. In molecular beam evaporation, which deposits elements other than oxygen, the above-mentioned vacuum (
For example, the substrate 3 is deposited from a k-cell deposition source 10.10' or an electron beam deposition source 9 in an atmosphere of 2.times.10-'Torr). At this time, the molecular beam intensity is monitored by a monitor 15 such as a crystal oscillator or an ion gauge, and by feeding this back to the evaporation sources, the input power to each evaporation source can be controlled.

The oxygen ion beam generated in the plasma chamber 14 and extracted with an energy of 10 to 500 eV is irradiated onto the substrate 3;
is monitored and fed back to the microwave source to control the ion current value. The oxygen ion beam irradiated at this time is variable from lO to 2000 pA/cm2.

In oxygen ion irradiation, setting the oxygen ion energy is important. In other words, ion energy or 1oke
Above V, some crystal defects remain in the obtained thin film, and 500c
In the range exceeding V and up to 10 keV, the film thickness decreases significantly due to the sputtering effect, and below 10 eV, the energy is too low and becomes similar to normal vacuum evaporation, resulting in an oxide thin film with a density close to that of the bulk without crystal defects. Cannot be produced. Therefore, the oxygen ion energy is set to 10 to 500 eV.

With this configuration, compared to conventional sputtering equipment and evaporation equipment with a Kauffman type ion source added,
Since molecular beams and oxygen ion beams can be generated independently and stably, the composition of each element including oxygen can be controlled independently and accurately.

r Example] The wooden invention will be described in detail below with reference to examples.

Example 1 (Ba2YCu306s) By using the ECR type ion source 7 as the ion source 12 in Fig. 1, it is possible to form a film continuously for more than 20 hours without maintenance of the ion source even if highly reactive oxygen gas is used. there were. After first exhausting the degree of vacuum in the ion source 12 and the film forming chamber 11 to I x 10-' Torr, oxygen gas is introduced from the gas inlet 4, and the ion source 12 and the film forming chamber 1 are
The vacuum degree of 1 was set to I x 10-'Torr. At this time, the oxygen ions generated in the plasma chamber 14 are
When pulled out with the energy of
An ion current value of A/cm2 was obtained, and the change in ion current value over time was extremely small at ±2% even during continuous operation for 10 hours.

As a substrate, 5rTi03 (110) plane and (100)
I used a surface. I prepared three trees in advance here.
The cell 10 is filled with Ba, Y, and Cu, respectively, and Ba,
Y and CU were each evaporated so that the composition of the film deposited on the substrate 3 would be Ba:Y:Cu-2+1:3, and the evaporation rate on the substrate 3 would be 0.85 people/sec. At the same time, the oxygen ion beam was applied to 5rTi at 100 cV and 50 μA/cm2.
(h) By irradiating the (110) plane or the (100) Go board, the stoichiometric Ba2Y(:Ll+Oa
, s polycrystalline or single crystal thin films were obtained. In particular, by maintaining the substrate temperature at a constant temperature between 400°C and 800°C, a single crystal film of Ba2YCu30B,s was obtained. At this time, Ba2Y is present on the 5rTi03 (100) surface.
The (001) plane of Cu306.5 is also 5rTiOs
On the (110) plane, Ba2YCu30B, (11
0) surface was epitaxially grown. This Ba2
The superconducting transition width Tc (the point where the resistance becomes O) after deposition of the YCu306.5 (110) plane single crystal film is as high as 82, as shown in Figure 2, and the superconducting transition width is as small as 2. .

Since it shows such an unprecedentedly high TC without annealing after vapor deposition, the composition including oxygen of the oxide thin film can be sufficiently controlled by the oxide thin film manufacturing apparatus and manufacturing method according to the invention. This has been proven.

Example 2 (La2-xsrxcu04)SrTi03
La2-xsr on the (110) and (100) planes
) ICu04 was grown.

100 eV, 50 μA/cm in the same manner as Example 1
After obtaining the oxygen ion beam of 2, in advance - cell 3
La, Sr, and Cu filled in the book are each evaporated, and La:Sr:Cu-1,85+0.15 is heated on the substrate 3.
:l and the deposition rate on the substrate 3 is 1.
．． By controlling the temperature of one cell to 5 people/sec and simultaneously irradiating the oxygen ion beam onto the 5rTi03 (110) surface or (100) substrate, Lal As5ro with a stoichiometric composition, A polycrystalline or single crystal thin film of +5Cu04 was obtained. In particular, the substrate temperature should be increased to 400℃.
5r by holding at a constant temperature between and 800℃
Ti(h) On the (110) plane, La1a5Sro, r
The (103) plane of 5cuOa is also 5rTi03(10
0) plane is La, a5SrolscuOa (00
1) A plane single crystal film was epitaxially grown.

The Tc of this La, 8SsrO, +5C1104 single crystal film is as high as 30, and the superconducting transition width ΔTC is as small as 1.5. Since the oxide thin film exhibits a high Tc almost like that of the bulk without annealing after vapor deposition, the composition including oxygen of the oxide thin film can be sufficiently controlled by the oxide thin film manufacturing apparatus and method according to the present invention. It has been proven that

Example 3 (LiNb03) A LiNbO3 film was grown on a sapphire zero-sided substrate.

After obtaining an oxygen ion beam under the conditions of 100 eV and 50 μA/cm2 in the same manner as in Example 1, the thermionic emission filament 17 (neutralization filament) was heated by electricity, and a thermionic shower was applied to the oxygen ion beam. , a neutral oxygen beam was obtained. Furthermore, Li is evaporated from the cell 10 and Nb is evaporated from the electron beam evaporation source 9, and the sapphire zero-face substrate is irradiated with the oxygen beam at the same time.
A NbO3 single crystal film was obtained. By neutralizing the oxygen ion beam, even the insulator LiNb0:+l can be used at a wavelength of 6.
Refractive index n for 33 nm light.

(Normal light) is 2. :11. n, (extraordinary light) is 2.17, indicating that L i N b O311A with a density close to that of the bulk is obtained.

[Effects of the Invention] As explained above, according to the oxide thin film manufacturing apparatus and manufacturing method of the present invention, an oxide single crystal thin film having a density close to that of a bulk can be produced by sufficiently controlling the composition including oxygen,
Can be formed stably. Therefore, oxide superconducting thin films with high superconducting transition temperatures can be fabricated without heat treatment for oxidation after thin film formation, and the range of applications for oxide thin films is expanded by simplifying the process and improving film properties. There is an advantage.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing eight components of the oxide thin film manufacturing apparatus according to the present invention, and FIG.
A characteristic diagram showing the resistivity characteristics with respect to temperature of the 2Y Cu 3065 film. Figure 3 is a cross-sectional view showing the configuration of a conventional sputtering device. Figure 4 shows the configuration of a vapor deposition device incorporating an ion source such as a Kauffman type. FIG. DESCRIPTION OF SYMBOLS 1... Terkerat, 2... Group 1 anti-holder, 3... Substrate, 4... Gas inlet, 5... Gas exhaust port, 6... Ion source, 7... Evaporation source , 8... Filament, 9... Electron beam evaporation source, 10, to'... Knudsen cell, (k-cell), 11... Film forming chamber, 12... Ion source, 13 ...Microwave source, 14...Plasma chamber, 15...Film thickness meter or ion cage, 16...Faraday cup, 17...Filament for neutralization, 18...Heater for heating the substrate. Patent Applicant Nippon Telegraph and Telephone Corporation Agent Patent Attorney Yoshi Tani - 1s, Invention 1: Juru defeat item book Getsuga's shape, cross section m1 showing the beak and claws Figure 1 Wen L ( K) 杏尤明r=JuruBq2ycu306.51
Thirst, charcoal bales? B')insu'''++ Figure 2: Jv rice's spetta &i''s decoy Figure 3: A five-split I0 town decoy diagram of I Jyorai Figure 4

Claims (1)

[Claims] 1) A substrate holder for supporting and heating a substrate disposed in a film forming chamber; an evaporation source for evaporating a substance to be deposited on the substrate; An oxide thin film manufacturing apparatus comprising: an ion source for irradiating the thin film deposited on the substrate with an oxygen ion beam extracted from plasma in the same manner as the deposition. 2) The oxide thin film manufacturing apparatus according to claim 1, further comprising electron irradiation means for irradiating the oxygen ion beam or the substrate with electrons to neutralize the ion beam charge. 3) An oxygen ion irradiation amount measuring means and a molecular beam irradiation amount measuring means are provided in the film forming chamber, and the respective measurement results are returned to the ion source and the evaporation source to measure the intensity of the oxygen ion beam and the amount of evaporation. The oxide thin film manufacturing apparatus according to claim 1 or 2, wherein the oxide thin film manufacturing apparatus is capable of controlling. 4) Using the apparatus for producing an oxide thin film according to any one of claims 1, 2, and 3, the raw material constituting the oxide is evaporated in a vacuum higher than 1 x 10^-^3 Torr. An oxide thin film characterized in that, at the same time, the deposited material on the substrate is irradiated with an oxygen ion beam or a neutral oxygen beam accelerated to a constant energy in the range of 10 to 500 eV. manufacturing method.