JP2000215797A - Thin film forming method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin film forming method and a device, capable of forming, in a low cost, a high quality protection film for protecting a dielectric of a plasma display panel. SOLUTION: Liquid raw material 4 comprising an organic metal compound containing a magnesium oxide precursor and one or more kinds of organic matter is atomized by an ultrasonic piezoelectric transducer 10 in an atomization vessel 11 to produce atomized fine particles. The atomized fine particles having atomized ultrafine particle sizes are supplied into a reaction vessel 15 in a normal pressure through a supply nozzle 16 by being carried by a carrier gas 6, and a temperature control of the atomized fine particles is executed by a temperature control heater 7. The atomized fine particles are supplied under a normal pressure to a body to be treated 2 retained in the heated state in the reaction vessel 15, and a magnesium oxide layer is formed on the body to be treated 2 without using a vacuum vessel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for forming a thin film, and more particularly to a method and apparatus for protecting a dielectric layer when a plasma display panel (also called a gas discharge display panel or DDP) used for a display device or the like is manufactured. The present invention relates to a method and an apparatus for forming a thin film suitably used for forming a protective film.

[0002]

2. Description of the Related Art In an AC-driven plasma display panel, a protective film is provided to protect a dielectric layer from ion bombardment due to discharge. Generally, a magnesium oxide (MgO) film is used for this protective film.

On the other hand, the driving voltage of the plasma display panel is determined by many factors such as the element structure and the filling gas. One of the factors is the secondary electron emission coefficient of the protective film in contact with the discharge space. . The larger the secondary electron emission coefficient is, the lower the voltage can be driven. The protective film made of magnesium oxide has a large secondary electron emission coefficient, and is suitable for the protective film from such a viewpoint.

Conventionally, when a protective film made of a magnesium oxide film is formed, an evaporation source is evaporated in an oxygen atmosphere in a vacuum by irradiating electron energy using an electron beam, so that the surface of the dielectric layer is oriented. A method of depositing a crystalline magnesium oxide thin film having a property is generally adopted.

[0005]

However, when the display screen of the plasma display panel is to be enlarged, a large-area substrate is required. Accordingly, after accommodating this substrate, a magnesium oxide protective film is formed. A large vacuum vessel is required to form.

Further, since the electron beam evaporation method is a method of forming a thin film utilizing a physical phenomenon, there is a limit in improving the quality of a formed film, and it is difficult to control the film structure.

For this reason, it is difficult to cope with the high functionality of the protective film for low power consumption, and a large vacuum vessel is required, resulting in a problem that the cost of the manufacturing apparatus becomes very high.

With respect to the driving voltage of a plasma display panel using a magnesium oxide protective film, it is necessary to further reduce the voltage from the viewpoint of power consumption when the panel is enlarged. Accordingly, there has been a demand for a technique for forming a protective film at a low cost for forming an AC-driven plasma display panel having a low driving voltage and a high luminous efficiency.

The present invention has been made in view of the above circumstances, and has as its object to provide a thin film forming method and apparatus capable of forming a high-quality protective film for protecting a dielectric of a plasma display panel at low cost.

[0010]

According to the thin film forming method of the present invention, a magnesium oxide layer is formed on an object to be processed by using a liquid material composed of an organic compound containing a magnesium component. By forming a layer, the treatment can be performed in a normal-pressure reaction vessel. Even if the object to be processed becomes large, it is sufficient to enlarge the normal-pressure reaction vessel in accordance with it, and a large-sized vacuum vessel can be used. Since there is no need to use it, simplification of protective film formation,
High productivity and low cost can be achieved.

[0011] Further, a liquid raw material comprising an organometallic compound containing a magnesium oxide precursor and at least one or more organic substances is atomized to form atomized fine particles, which are supplied by temperature control means or into the atmosphere. When the temperature of the atomized fine particles is controlled by an active gas or the like and the atomized fine particles are supplied to the object under normal pressure to form a magnesium oxide layer on the object, a material for forming the magnesium oxide layer is formed. The atomized fine particles consisting of are supplied to the object under normal pressure. Therefore, even if the object to be processed becomes large, it is sufficient to increase the size of the normal-pressure reaction vessel in accordance with the size. By controlling the temperature of the fine particles, the desorption and evaporation of at least one or more solvent components in the space of the organic magnesium compound material are promoted, and the organic magnetism on the surface of the object to be processed is promoted. It promotes a chemical reaction of Um compound material, atomized particulate state effectively promoted to it Tekiru adsorption reaction at the surface of the object of the liquid.

Further, the object on which the magnesium oxide layer is formed is accommodated in a reaction vessel at normal pressure, and optical spectrum energy is supplied to the surface of the magnesium oxide layer of the object in the reaction vessel to form the magnesium oxide layer. By modifying the film structure, it is possible to control the crystal structure, the oxygen vacancy in the film, and the energy level of the thin film formed of the liquid material.

[0013] The thin film forming apparatus of the present invention further comprises means for atomizing a liquid material comprising an organometallic compound containing a magnesium oxide precursor and at least one or more kinds of organic substances to produce atomized fine particles; Means for controlling the temperature of the fine particles, and means for supplying the atomized fine particles to the object under normal pressure to form a magnesium oxide layer on the object to be processed. Atomized fine particles made of the material to be formed can be supplied to the object under normal pressure. Therefore, even if the object to be processed becomes large, it is enough to enlarge the reaction vessel at normal pressure, and it is easy to form the protective film. , High productivity, low cost, and the ability to control the temperature of the atomized fine particles facilitates desorption and evaporation of at least one or more solvent components in the space of the organomagnesium compound material. Rutotomoni to suppress a chemical reaction of the organomagnesium compound material other than the surface of the object, atomized particulate state effectively promoted to it Tekiru adsorption reaction at the surface of the object of the liquid.

A reaction vessel at normal pressure, a means for holding the object to be heated in the reaction vessel, an ultrasonic wave transmitting means for atomizing the liquid raw material by an atomization method using ultrasonic waves,
Means for supplying a carrier gas into the reaction vessel for supplying atomized ultrafine particle atomized fine particles to the object to be processed, and means for controlling the temperature in the process of supplying the atomized fine particles to the object to be processed. In the process, the object to be processed is heated in the reaction vessel, and at least one or more kinds of liquid materials contained in the liquid material in a process in which the fine particle liquid atomized by the ultrasonic wave is supplied into the reaction vessel by the carrier gas. By controlling the thermal decomposition temperature required for desorption and evaporation of the organic solvent component of
It promotes the adsorption reaction of atomized fine particles on the surface of the object to be treated, eliminates the incorporation of organic components into the film during the film formation process, and forms a crystalline magnesium oxide thin film free of impurity components.

[0015] A reaction vessel at normal pressure capable of accommodating the object on which the magnesium oxide layer is formed, and supplying optical spectrum energy to the surface of the magnesium oxide layer of the object in the reaction vessel to form the magnesium oxide layer. When a means for modifying the film structure is provided, it is possible to control the crystal structure, the oxygen vacancy in the film, and the energy level of the thin film formed from the liquid raw material.

Further, a means for holding the object to be processed in a reaction vessel at normal pressure in a heated state and a means for controlling the atmosphere of the magnesium oxide layer formed on the object to be controlled to an oxidizing or reducing atmosphere gas space. Means for supplying a gas into the reaction vessel, and irradiating the magnesium oxide layer with light spectrum energy such as ultraviolet rays in the atmosphere gas to promote the oxygen deficiency state in the film, thereby controlling the composition of the thin film film structure network. Means for reforming the thin film by controlling the crystal structure, oxygen vacancies and energy levels in the thin film formed from the liquid raw material, and by heating the object to be processed, The reforming is performed effectively.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the thin film forming apparatus of the present invention is applied to a protective film forming apparatus for a plasma display panel will be described below with reference to the drawings.

(First Embodiment) First, a first embodiment will be described with reference to FIG. In FIG. 1, 15
Reference numeral denotes a reaction vessel for forming a thin film at normal pressure, and a heating stage 5 having a built-in panel heater is disposed inside. On the heating stage 5, an object 2 such as a glass substrate having a maximum diagonal of 50 inches, on which a protective film is to be formed, is placed and held. The reaction vessel 15 is provided with a supply nozzle 16 for supplying the atomized fine particles 1 to the inside, and is also configured to uniformly supply the atomized fine particles 1 to the processing target 2 via the atomized fine particle uniform dispersion plate 9. It is configured. The supply nozzle 16 is connected to the atomization container 11 through the atomization fine particle introduction pipe 8.
It is connected to the.

The ultrasonic vibrator 10 is provided inside the atomizing container 11.
And a liquid raw material 4 composed of an organic magnesium compound solution is accommodated therein.
Is generated. In addition, atomization container 1
1 is configured to introduce a carrier gas 6 made of oxygen or an inert gas, and the generated atomized fine particles 1 are loaded on the introduced carrier gas 6 and supplied to the reaction vessel 15 through the atomized fine particle introduction pipe 8. It is configured to be.

A buffer container 12 that can be automatically prepared is connected to the outside of the atomizing container 11, and the liquid raw material 4 is configured to circulate between the atomizing container 11 and the buffer container 12. Further, the atomization container 11 is provided with a concentration detector 13 for keeping the concentration of the liquid raw material 4 constant. 14 is a liquid level sensor.

On the surface of the supply nozzle 16, there is provided a temperature control heater 7 for controlling the atmosphere inside the supply nozzle 16 and the temperature of the atomized fine particles 1. Further, a uniform exhaust pipe 3 for discharging the atomized fine particles that have not contributed to the film formation to the outside is provided along with the supply nozzle 16.

In the above configuration, the concentration of the liquid raw material 4 composed of the organic magnesium compound solution stored in the atomization container 11 is measured by the concentration detector 13 in order to keep the concentration of the organic magnesium compound solution constant. Detected and adjusted to a certain concentration in a buffer container 12 that can be automatically mixed and circulated between the buffer container 12 and the atomization container 11. In the atomization container 11, when the ultrasonic vibration of 100 KHz to 2 MHz is applied to the liquid raw material 4 by the ultrasonic vibrator 10, the atomized fine particles 1 having an ultrafine particle diameter of 10 μm or less are generated. . The atomized fine particles 1 are supplied through an atomized fine particle introduction pipe 8 while maintaining a constant supply speed by a carrier gas 6 made of at least one kind of oxygen or an inert gas introduced into an atomization container 11. 16 is transferred.

At this time, the atomized fine particles 1 having an ultra-fine particle size
Nuclei particles, which are aggregates of molecules, are generated by repeating collisions, aggregation, and desorption / evaporation of vapor molecules with each other. When the core particles pass through the supply nozzle 16, the temperature of the core particles is controlled by the temperature control heater 7 on the surface of the supply nozzle 16, so that the temperature of the core particle does not exceed the decomposition temperature of the magnesium compound dissolved in the solvent. The liquid atomized fine particles 1 in the state of ultrafine particles are conveyed to 2 to promote the reaction efficiency of forming a thin film on the surface of the object 2 to be heated and held in advance.

In the magnesium compound solution used in this embodiment, the temperature of the object 2 required for forming a thin film is 500
C. or more is required. In order to form a thin film having good crystallinity, the temperature of the supply nozzle 16 is controlled to 300 ° C. or less in order to suppress overreaction during the transportation of the atomized fine particles 1. It is desirable to supply it to the body 2.

Thus, the magnesium oxide layer formed on the object 2 has a structure having a stoichiometric composition by dissociating at least one or more components. The film structure of the thin film of the magnesium oxide layer formed by this method by X-ray diffraction is preferentially oriented in the (1,0,0) plane direction,
The formed magnesium oxide thin film had a crystal structure. Further, according to the identification by infrared spectroscopic analysis, no organic component remains in the film, and good absorption of magnesium oxide without impurities is recognized.

When the formed magnesium oxide layer having a thickness of 0.5 μm is used as a dielectric protective layer and applied to a plasma display panel of a three-electrode discharge type, the discharge starting voltage is 150 V. Good characteristics were shown.

In the present embodiment, the temperature of the atomized fine particles 1 in the supply nozzle 16 is set to 300 ° C. or less. However, the control temperature of the atomized fine particles 1 may be changed depending on the solvent component, type and concentration in the liquid raw material 4. The temperature may be 300 ° C. or higher. In some cases, the surface of the object 2 to be heated in a heated state may be lower than the lower limit of 500 ° C., and then firing may be performed as a post-treatment.

In this embodiment, the carrier gas 6 containing the atomized fine particles 1 is heated by the heater 7 for temperature control to control the temperature. However, the carrier gas made of oxygen or inert gas whose temperature is controlled is shown. May be introduced to control the temperature.

(Second Embodiment) Next, a second embodiment will be described with reference to FIG. This embodiment is for modifying the bonding state of the thin film of the magnesium oxide layer formed according to the first embodiment. In FIG. 2, reference numeral 17 denotes a normal-pressure thin-film reforming reaction vessel, which is provided adjacent to the normal-pressure thin-film forming reaction vessel 15 shown in FIG. Alternatively, ultraviolet light spectrum energy is irradiated in a state in which a reducing gas is introduced, and the generated reactive ionization and ionization products are supplied to the processing object 2.

A heating stage 2 having a built-in heating element for holding and heating the object 2 to be processed is provided inside the reaction vessel 17.
4 are provided. Reference numeral 23 denotes an ultraviolet light source composed of a xenon lamp. Around the heating stage 24, supply pipes 18, 20 for introducing an oxygen gas or a reducing inert gas 25 are connected. Reference numeral 19 denotes a supply gas exhaust pipe, and reference numeral 21 denotes a uniform exhaust plate for uniformly exhausting the supply gas.

Here, the object 2 on which the magnesium oxide thin film is formed according to the first embodiment is loaded into the reaction vessel 17 by a predetermined transport means (not shown) and is set on the heating stage 24. Then, the object 2 is set at 500
After heating and keeping the temperature at about 0 ° C., oxygen gas or reducing inert gas 25 is supplied from the supply pipe 18 and
A back pressure of about 50 mmH ₂ O is applied, and the supply gas is exhausted from the exhaust pipe 19 via the uniform exhaust plate 21. At this time, the flow rate of the supplied gas is desirably about 2 L. Further, by using an ultraviolet light emitting source 23 arranged in the upper part of the object 2 to be processed, in this case, having a light source wavelength of 185 nm, and applying a power of 300 to 500 W for irradiation, the film structure and composition of the formed thin film Further, an oxygen deficiency state in the film is established to control the film quality.

Thus, the optical energy level can be changed by intentionally disturbing the bonding state, composition, and arrangement of molecules in the thin film of the magnesium oxide layer formed on the processing target 2. .

The film quality of the magnesium oxide thin film formed by this method has an optical gap of 7.7 eV, and the film structure by X-ray diffraction is (1, 0, 0), (1, 1, 0),
Any of the (1, 1, 1) planes could be controlled by conditions such as the type of supply gas, supply flow rate, and electric energy.

When the formed magnesium oxide layer having a thickness of 0.5 μm is applied as a dielectric protective film to a three-electrode surface discharge type plasma display panel, the discharge starting voltage is 130 to 140 V. And good characteristics.

In this embodiment, a xenon lamp is used as an energy source for reforming the thin film. However, a form of light irradiation by another near-infrared ray or far-infrared ray light source may be added. Further, in some cases, the surface temperature of the object 2 to be heated in a heated state may be lower than about 500 ° C., and then firing may be performed as a post-treatment.

[0036]

According to the method and apparatus for forming a thin film of the present invention, as is apparent from the above description, since a magnesium oxide film is formed from a liquid material, the processing can be performed in a reaction vessel at normal pressure. Therefore, even if the object to be treated becomes large, it is sufficient to make the normal-pressure reaction vessel large accordingly, and there is no need to use a large vacuum vessel. And cost reduction.

In addition, by controlling the temperature of the atomized fine particles having an ultra-fine particle size by the liquid material, the desorption and evaporation of the organic component are efficiently promoted, and the overreaction of the solute component other than the surface of the object to be processed is performed. , A dense magnesium oxide layer having high-performance electronic discharge characteristics having high crystallinity without organic components can be formed.

As a result, the discharge starting voltage, the discharge sustaining voltage and the luminous efficiency of the AC-driven plasma display panel can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a thin film forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a thin film reforming apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Atomized fine particle 2 Object to be processed 4 Liquid raw material 5 Heating stage 6 Carrier gas 7 Temperature control heater 10 Ultrasonic vibrator 11 Atomization container 15 Normal-pressure reaction container (for thin film formation) 16 Supply nozzle 17 Normal-pressure reaction container (For thin film reforming) 18, 20 Supply pipe 23 Ultraviolet light source 24 Heating stage 25 Oxygen gas or reducing inert gas

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuyuki Sawada 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 5C027 AA05 AA07 5C040 GE07 GE09 JA07 MA23

Claims (7)

[Claims] 1. A method for forming a thin film, comprising: forming a magnesium oxide layer on an object to be processed using a liquid raw material comprising an organic compound containing a magnesium component. 2. A magnesium oxide precursor and at least one
Atomization of liquid raw material composed of organometallic compounds containing more than one kind of organic matter to generate atomized fine particles, and control temperature of atomized fine particles by temperature control means or by inert gas supplied to atmosphere 2. The method according to claim 1, wherein the atomized fine particles are supplied to the object under normal pressure to form a magnesium oxide layer on the object. 3. An object on which a magnesium oxide layer is formed is accommodated in a reaction vessel under normal pressure, and optical spectrum energy is supplied to the surface of the magnesium oxide layer of the object in the reaction vessel to form the magnesium oxide layer. 3. The method according to claim 1, wherein the film structure is modified. 4. The magnesium oxide precursor and at least one
Means for atomizing a liquid raw material comprising an organometallic compound containing more than one kind of organic substance to generate atomized fine particles, means for enabling temperature control of the atomized fine particles, and coating the atomized fine particles under normal pressure. Means for forming a magnesium oxide layer on the object to be supplied by supplying the object to the object to be processed. 5. A reaction vessel at normal pressure, a means for holding the object to be processed in the reaction vessel in a heated state, an ultrasonic wave transmitting means for atomizing a liquid raw material by an ultrasonic atomization method, and atomization. Means for supplying a carrier gas for supplying atomized fine particles having an ultra-fine particle diameter to the object to be processed, and means for controlling the temperature in the process of supplying the atomized fine particles to the object to be processed. 5. The thin film forming apparatus according to claim 4, wherein: 6. A reaction vessel under normal pressure capable of accommodating an object on which a magnesium oxide layer is formed, and supplying optical spectrum energy to a surface of the magnesium oxide layer of the object in the reaction vessel to form the magnesium oxide layer. 6. The thin film forming apparatus according to claim 4, further comprising means for modifying a film structure. 7. A means for holding an object to be processed in a reaction vessel at normal pressure in a heated state, and an atmosphere of a magnesium oxide layer formed on the object to be processed is controlled to an oxidizing or reducing atmosphere gas space. Means for supplying a gas into the reaction vessel, and irradiating the magnesium oxide layer with light spectrum energy such as ultraviolet rays in the atmosphere gas to promote the oxygen deficiency state in the film, thereby controlling the composition of the thin film film structure network. 7. The thin film forming apparatus according to claim 6, further comprising: means for performing a thin film modification by means of a thin film.