JPH10130848A - Oxide deposition method - Google Patents

Abstract

(57) [Problem] To provide a good oxide thin film that can be easily made thick, has uniform film quality, and has no oxygen deficiency, and can be widely applied to electronic device applications and micro machine device applications. is there. The present invention provides a solution or an organosol in which an organic metal compound is dissolved or dispersed in an organic solvent in plasma formed in a high frequency induction plasma torch, and the organic metal compound is decomposed or decomposed in the plasma. Provided is a method for easily depositing an oxide thin film having an arbitrary composition with good productivity by attaching it to a substrate after evaporation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an oxide by using a sol obtained by a sol-gel method as a raw material and forming a thin film on a substrate by using thermal plasma. It can be used for thin film electronic devices using oxides and rigid and durable microstructures.

[0002]

2. Description of the Related Art As a method for forming an oxide film using a sol-gel method, a method of applying a sol, drying and annealing is repeatedly laminated. There is known a method in which a sol is formed into a mist and the coating and annealing are repeatedly laminated.

On the other hand, as a film forming method using thermal plasma, a thermal plasma CVD method (JP-A-5-320916),
Plasma SPRAY-ICP method (Appl. Phys. Lett. 14 (19
90.10) 1452), plasma flash evaporation method
314622), plasma spraying method (JP-A-6-7698)
6) The four methods are known.

[0004]

However, in the conventional sol-gel method, it is difficult to increase the film thickness, and there is a problem that a composition distribution and a layered interface occur in the thickness direction. In addition, there is a problem in the process that organic residues remain in the thin film or the abundance ratio of oxygen in the oxide film becomes lower than that of the desired crystal system.

On the other hand, in a film forming method using thermal plasma, in the case of a CVD method using a gas as a raw material, a reactive gas is expensive and the type of oxide is limited. Since the generated toxic gas must be treated, it has a disadvantage of increasing costs. In the SPRAY-ICP method using an aqueous solution obtained by dissolving a metal salt in nitric acid or hydrochloric acid as a raw material, since an inorganic acid is used as a raw material adjustment, a large amount of acid vapor is generated and the inside of a film forming apparatus is significantly corroded. There is also a problem that it is impossible to use a metal or a substrate on which a metal thin film is formed as a substrate.

A flash evaporation method using fine powder as a raw material,
In the thermal spraying method, the supply of powder is not constant and the film quality is not stable. It is difficult to control the deposition rate. The problem was that it was difficult to obtain fine powder raw materials. A method of producing a raw material powder using a sol-gel method (Japanese Patent Application Laid-Open No. 6-12955) has also been proposed.

Accordingly, the present invention is to solve such a problem, and an object of the present invention is to provide a method for easily forming an oxide thin film having an arbitrary composition with good productivity. A good oxide thin film that can be easily made thick, has uniform film quality, and has no oxygen deficiency can be obtained.

[0008]

According to a method of forming an oxide of the present invention, a material to be formed is supplied into plasma formed in a high frequency induction plasma torch, and the material to be formed is decomposed in the plasma. Alternatively, in a vapor-phase film formation method in which the film is evaporated and then attached to a substrate, a substance to be formed to be supplied to plasma is a solution or an organosol in which an organometallic compound is dissolved or dispersed in an organic solvent. .

The film-forming substance to be supplied into the plasma is a solution or an organosol in which a plurality of organometallic compounds are dissolved or dispersed in an organic solvent in a molar ratio for forming a film.

[0010] The plasma formed in the high frequency induction plasma torch is an oxygen plasma.

The present invention is characterized in that the temperature of the substrate is kept constant, and a crystalline oxide crystal to be formed on the substrate is grown.

The present invention is characterized in that an oxide formed on a substrate is annealed together with the substrate at an appropriate temperature to obtain a crystalline oxide crystal thin film.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The sol-gel method is characterized by being excellent in composition controllability and capable of forming a uniform thin film in a plane with good reproducibility. However, a non-uniform crystal phase is generated at the annealing interface, and the lamination method varies in the thickness direction. In addition, a sufficient film thickness cannot be obtained without lamination,
This is a method in which unreacted organic residues and oxygen deficiency are likely to occur.
Also, it is hard to say that productivity is high.

The organometallic compound supplied into the oxygen plasma having a temperature of 10,000 degrees or more evaporates and reacts in the plasma, and is decomposed into carbon dioxide gas and water vapor. The metal is deposited as an oxide on the substrate in the form of oxide atoms, or after being activated and ionized. Therefore, there is no organic residue or oxygen deficiency in principle, and it is possible to continuously increase the film thickness without causing cracks. Naturally, there is no variation in the thickness direction. By adjusting the composition ratio, the substrate temperature, and the crystal orientation of the substrate, a desired crystalline oxide thin film can be formed. Since the film formation speed is high and the stable formation of the sol can be controlled, it is a highly productive method.

Hereinafter, the present invention will be described in detail based on examples.

(Example 1) A platinum substrate was placed in a vacuum chamber and heated to 400 ° C. The chamber and the plasma torch were evacuated to 1 torr or less, and argon gas for plasma generation was supplied into the torch. 10kW at the same time, 4
A high-frequency current of about MHz was applied to generate low-pressure glow plasma. Next, the pressure in the chamber and the plasma torch is gradually reduced to a constant pressure of about 200 torr, and the plasma gas source is replaced with oxygen from argon. At the same time, the high frequency power is increased to about 50 kW, and the thermal plasma is introduced into the torch and the chamber. Raised.

A solution prepared by dissolving 10 parts by weight of tetraethoxysilane in ethyl alcohol was fed at a rate of 1 ml per minute by a constant-rate liquid sending pump, and was injected into oxygen plasma in a mist. Oxygen plasma is always stable,
The film was formed for 10 minutes while maintaining the temperature at 0 ° C.

The platinum substrate was taken out into the atmosphere, and the uniformly formed silicon dioxide thin film was evaluated. The film thickness was 3 μm, and it was very dense glass when observed in cross section. X-ray analysis confirmed that it was amorphous, and absorption spectroscopy analysis confirmed that it had almost no hydroxyl groups. An aluminum electrode thin film was formed by a vacuum deposition method, and the electrical characteristics between the thin film and the substrate were measured.

Even if this film formation was repeated, no corrosion occurred in the chamber, and stable production was possible. In addition, no contamination of the thin film with impurities due to corrosion was detected.

(Example 2) A glass substrate was placed in a vacuum chamber and heated to 300 ° C. The chamber and the plasma torch were evacuated to 1 torr or less, and argon gas for plasma generation was supplied into the torch. 10kW at the same time,
A high-frequency current of about 4 MHz was passed to generate low-pressure glow plasma. Next, gradually reduce the pressure in the chamber and the plasma torch to a constant pressure of around 200 torr,
At the same time as replacing the plasma gas source with argon by oxygen, the high-frequency power was increased to about 50 kW to generate thermal plasma in the torch and the chamber.

5 parts by weight of indium 2-ethylhexanoate was dissolved in benzene, and stannous 2-ethylhexanoate was added in an amount of 2 mol% based on indium. The obtained organosol was added at a rate of 0.5 ml
The solution was fed at a rate of, and injected as a mist into the oxygen plasma. The oxygen plasma is always stable, and the substrate is kept at 300 ° C.
The film was formed for 10 minutes while maintaining the temperature.

The glass substrate was taken out into the atmosphere, and the uniformly formed ITO thin film was evaluated. The film thickness is 0.5 μm,
Electron microscopy confirmed granular grain boundaries. X-ray analysis showed that crystallization was insufficient, and the electrical characteristics were measured. As a result, the specific resistance showed a high value of 5 * 10 ⁻³ Ωcm.

When this glass substrate was subjected to vacuum annealing at 550 ° C., the conductivity of the ITO thin film was improved, and the specific resistance was reduced to 1 * 10 ⁻⁴ Ωcm. Further, the transmittance in the visible region was high, and it was sufficiently applicable as a transparent electrode.

Even if this film formation was repeated, no corrosion occurred in the chamber, and stable production was possible. In addition, no contamination of the thin film with impurities due to corrosion was detected.

(Example 3) A silicon substrate on which a platinum electrode was formed by a sputtering method was placed in a vacuum chamber, and 500
Heated to ° C. 1 to chamber and plasma torch
The air was evacuated to rr or less, and argon gas for plasma generation was supplied into the torch. At the same time, a high-frequency current of about 10 kW and 4 MHz was passed to generate low-pressure glow plasma. Next, the pressure in the chamber and the plasma torch is gradually reduced to a constant pressure of about 200 torr, and the plasma gas source is replaced with oxygen from argon. At the same time, the high frequency power is increased to about 50 kW, and the thermal plasma is introduced into the torch and the chamber. Raised.

Lead acetate trihydrate was dissolved in acetic acid to form a solution. Titanium isopropoxide in an equimolar amount to lead was dissolved in methyl cellosolve and mixed. After acetylacetone was added to stabilize the mixture, 5 parts by weight of water was added to the mixture, and the mixture was aged at room temperature for 3 days or more. The obtained organosol is
The liquid was fed at a rate of 0.5 ml / min by a constant-rate liquid sending pump, and was injected into oxygen plasma in a mist state. The oxygen plasma was always stable, and the film was formed for 30 minutes while keeping the substrate at 500 ° C.

The silicon substrate was taken out into the atmosphere, and a uniformly formed thin film of lead titanate was evaluated. The film thickness is 5μm
In electron microscopic observation, a granular crystal grain boundary was confirmed. X-ray analysis showed that crystallization had progressed sufficiently. An aluminum electrode thin film was formed by a vacuum deposition method, and the electrical characteristics between the aluminum electrode thin film and the platinum electrode on the substrate were measured.
When the DE hysteresis was measured, it was found that the ferroelectric thin film had a high coercive electric field and a high remanent polarization.

Even if this film formation was repeated, no corrosion occurred in the chamber, and stable production was possible. In addition, no contamination of the thin film with impurities due to corrosion was detected.

(Example 4) A nickel substrate was placed in a vacuum chamber and heated to 500 ° C. The chamber and the plasma torch were evacuated to 1 torr or less, and argon gas for plasma generation was supplied into the torch. 10k at the same time
A high-frequency current of about 4 MHz was applied to generate low-pressure glow plasma. Next, the pressure in the chamber and the plasma torch is gradually reduced to a constant pressure of about 200 torr, and the plasma gas source is replaced with oxygen from argon. At the same time, the high frequency power is increased to about 50 kW, and the thermal plasma is introduced into the torch and the chamber. Raised.

Zirconium acetylacetonate and yttrium acetylacetonate in an amount of 5 mol% based on zirconium were dissolved in acetic acid and ethyl carbitol, and a small amount of triethylene glycol was added. The obtained organosol was fed at a rate of 5 ml / min by a constant-rate feed pump, and was injected into oxygen plasma in the form of a mist. The oxygen plasma was always stable, and the film was formed for 30 minutes while keeping the substrate at 500 ° C.

The nickel substrate was taken out into the atmosphere, and a uniformly formed zirconia thin film was evaluated. The film thickness is 50μ
m, it could be peeled off from the nickel substrate. X-ray analysis showed a monoclinic structure,
After heating to ° C., the mixture was gradually cooled. When X-ray analysis was performed again, it was found to be cubic stabilized zirconia. It has a very dense structure, showing high Young's modulus and high environmental reliability and chemical resistance.

Even if this film formation was repeated, no corrosion occurred in the chamber, and stable production was possible. In addition, no contamination of the thin film with impurities due to corrosion was detected.

Example 5 SrTiO ₃ was placed in a vacuum chamber.
A (100) single crystal substrate was placed and heated to 750 ° C. The chamber and the plasma torch were evacuated to 1 torr or less, and argon gas for plasma generation was supplied into the torch. At the same time, a high-frequency current of about 10 kW and 4 MHz was passed to generate low-pressure glow plasma. Next, the pressure in the chamber and the plasma torch is gradually reduced to a constant pressure of about 200 torr, and the plasma gas source is replaced with oxygen from argon. At the same time, the high frequency power is increased to about 50 kW, and the thermal plasma is introduced into the torch and the chamber. Raised.

Yttrium, barium and acetylacetonate of copper were dissolved in a mixed solvent of pyridine and propionic acid at a molar ratio of 1: 2: 3. The obtained organosol was fed at a rate of 0.2 ml / min by a fixed-rate feed pump, and was injected into oxygen plasma in a mist state. Oxygen plasma is always stable, and the substrate is kept at 750 ° C. for 3 hours.
The film was formed for 0 minutes.

The substrate was taken out into the atmosphere, and the uniformly formed YBCO thin film was evaluated. The film thickness is 0.5 μm,
The superconducting critical temperature measured from the current-voltage curve was 90K. X-ray analysis showed strong (001) and (200) peaks.

Even if this film formation was repeatedly performed, no corrosion occurred in the chamber, and stable production was possible. In addition, no contamination of the thin film with impurities due to corrosion was detected.

Example 6 A silicon substrate on which a platinum electrode was formed by a sputtering method was placed in a vacuum chamber, and 500
Heated to ° C. 1 to chamber and plasma torch
The air was evacuated to rr or less, and argon gas for plasma generation was supplied into the torch. At the same time, a high-frequency current of about 10 kW and 4 MHz was passed to generate low-pressure glow plasma. Next, the pressure in the chamber and the plasma torch is gradually reduced to a constant pressure of about 200 torr, and the plasma gas source is replaced with oxygen from argon. At the same time, the high frequency power is increased to about 50 kW, and the thermal plasma is introduced into the torch and the chamber. Raised.

After dissolving titanium isopropoxide in diethanolamine and butyl cellosolve, 2 moles of lead acetate trihydrate and 2 moles of zirconium acetylacetonate were added to titanium and dissolved therein. The obtained organosol was fed at a rate of 0.5 ml / min by a constant-rate feed pump, and was injected into oxygen plasma in a mist state. The oxygen plasma was always stable, and the film was formed for 30 minutes while keeping the substrate at 500 ° C.

The silicon substrate was taken out to the atmosphere, and a uniformly formed thin film of lead zirconate titanate was evaluated. The film thickness was 5 μm, and a granular crystal grain boundary was confirmed by electron microscopic observation. X-ray analysis revealed that the crystal system was of the pyrochlore type. The sample was heated to 800 ° C. in an oxygen atmosphere in a rapid heating annealing furnace (RTA) with lamp heating and held for 1 minute. X-ray analysis was performed again, and it was found that the crystal system was a perovskite type. An aluminum electrode thin film was formed by a vacuum evaporation method, and the electrical characteristics were measured between the aluminum electrode thin film and a platinum electrode on the substrate. As a result, the dielectric constant was 1800, indicating high piezoelectric characteristics.

Even if this film formation was repeated, no corrosion occurred in the chamber, and stable production was possible. In addition, no contamination of the thin film with impurities due to corrosion was detected.

(Embodiment 7) A TFT is placed in a vacuum chamber.
Place the glass substrate on which the (thin film transistor) is formed,
Heated to 400 ° C. The chamber and the plasma torch were evacuated to 1 torr or less, and argon gas for plasma generation was supplied into the torch. At the same time, a high-frequency current of about 10 kW and 4 MHz was passed to generate low-pressure glow plasma. Next, the pressure in the chamber and the plasma torch was gradually reduced to a constant pressure of about 200 torr, and the plasma gas source was replaced with oxygen from argon.
The high frequency power was increased to about W, and thermal plasma was generated in the torch and the chamber.

A solution prepared by dissolving 5 parts by weight of trimethoxymethylsilane in methyl alcohol was fed at a rate of 1 ml / min by a constant-rate feed pump, and was injected into oxygen plasma by atomization. Oxygen plasma is always stable,
The film was formed for 3 minutes while maintaining the temperature at 00 ° C.

The glass substrate was taken out into the atmosphere, and the uniformly formed silicon dioxide thin film was evaluated. 0.3μm thickness
In observation of the cross section, it was very dense glass. When a nickel probe was brought into contact with the electrode portion on the glass substrate by applying pressure, and the electrical characteristics between the probe and the substrate were measured, good insulating characteristics were shown.

Even if this film formation was repeated, no corrosion occurred in the chamber, and stable production was possible. In addition, no contamination of the thin film with impurities due to corrosion was detected.

[0045]

As described above, the method for forming an oxide film according to the present invention provides a solution or organosol in which an organometallic compound is dissolved or dispersed in an organic solvent in plasma formed in a high-frequency induction plasma torch. Was supplied, the organometallic compound was decomposed or evaporated in plasma, and then attached to a substrate, whereby a method of easily forming an oxide thin film of any composition with good productivity could be provided. A good oxide thin film that can be easily formed into a thick film, has uniform film quality, and has no oxygen deficiency can be obtained, and can be widely applied to electronic device applications and micro machine device applications.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hisashi Komaki 3-1-2 Musashino, Akishima City, Tokyo JEOL Ltd.

Claims (9)

[Claims] A gas phase film forming method in which a film forming material is supplied into plasma formed in a high frequency induction plasma torch, and the film forming material is decomposed or evaporated in the plasma and then attached to a substrate. 3. The method for forming an oxide film according to claim 1, wherein the substance to be formed supplied into the plasma is a solution or an organosol in which an organic metal compound is dissolved or dispersed in an organic solvent. 2. A vapor deposition method in which a substance to be deposited is supplied into plasma formed in a high frequency induction plasma torch, and the substance to be deposited is decomposed or evaporated in the plasma and then attached to a substrate. 3. The method for forming an oxide according to claim 1, wherein the substance to be formed supplied into the plasma is a solution or an organosol in which a plurality of organometallic compounds are dissolved or dispersed in an organic solvent in a molar ratio for forming a film. 3. A solution or organosol in which an organic metal compound is dissolved or dispersed in an organic solvent is supplied into plasma formed in a high frequency induction plasma torch, and the organic metal compound is decomposed or evaporated in the plasma. A method for forming an oxide film, wherein the plasma formed in the high-frequency induction plasma torch is oxygen plasma in a vapor-phase film forming method for attaching to a substrate. 4. A solution or an organosol in which an organometallic compound is dissolved or dispersed in an organic solvent is supplied into plasma formed in a high-frequency induction plasma torch, and the organometallic compound is decomposed or evaporated in the plasma. Thereafter, in a vapor phase film forming method for attaching to a substrate, an oxide film forming method characterized in that a temperature of the substrate is kept constant and a crystalline oxide crystal to be formed on the substrate is grown. 5. A solution or organosol in which an organometallic compound is dissolved or dispersed in an organic solvent is supplied into plasma formed in a high frequency induction plasma torch, and the organometallic compound is decomposed or evaporated in the plasma. After that, in a vapor phase film deposition method of attaching to a substrate, the oxide formed on the substrate is annealed at an appropriate temperature together with the substrate to obtain a crystalline oxide crystal thin film, which is characterized by forming an oxide film. Method. 6. A solution or organosol in which an organic metal compound is dissolved or dispersed in an organic solvent is supplied into plasma formed in a high frequency induction plasma torch, and the organic metal compound is decomposed or evaporated in the plasma. Later, in the vapor deposition method to adhere to the substrate, the organometallic compound is a metal alkoxide, metal acetylacetonate,
The method for forming an oxide film according to any one of claims 1 to 5, wherein the method is a metal carboxylate or a partially alkyl-substituted product thereof. 7. A solution or an organosol in which an organic metal compound is dissolved or dispersed in an organic solvent is supplied into plasma formed in a high-frequency induction plasma torch, and the organic metal compound is decomposed or evaporated in the plasma. Thereafter, in a vapor phase film formation method of attaching to a substrate, an organic solvent for dissolving or dispersing the organometallic compound is a hydrocarbon, an alcohol, a cellosolve, a carbitol, a carboxylic acid, an alkanolamine, an ethylene glycol,
7. The oxide film forming method according to claim 1, wherein the mixed solution is any one of β-diketones and amines or a mixed solution. 8. A solution or organosol in which an organometallic compound is dissolved or dispersed in an organic solvent is supplied into plasma formed in a high frequency induction plasma torch, and the organometallic compound is decomposed or evaporated in the plasma. 8. The method according to claim 1, wherein the amount of water contained in the supplied solution or the organosol is 50 parts by weight or less in a vapor phase film forming method for attaching to the substrate. Membrane method. 9. A solution or organosol in which an organometallic compound is dissolved or dispersed in an organic solvent is supplied into plasma formed in a high frequency induction plasma torch, and the organometallic compound is decomposed or evaporated in the plasma. The method for forming an oxide film according to any one of claims 1 to 8, wherein the supplied solution or the organosol does not contain an inorganic acid in the vapor phase film forming method for attaching to the substrate.