JP2007246942A - Method for making body having film formed by aerosol deposition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for making a film formed body consisting of oxides of high optical transmittance by an aerosol deposition method. <P>SOLUTION: Surface layers of raw fine particles consisting of oxides are turned to be in an oxygen-want state, and a carrier gas having the oxidizing property is used to promote the cohesion between particles generated at the time of substrate collision/cracking of the raw fine particles. Thereby, generation of voids is suppressed, the denseness of a film deposition body is enhanced, and its transmittance is enhanced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of forming an optically transparent oxide film using an aerosol deposition method.

  In the aerosol deposition method (hereinafter referred to as AD method), a raw material composed of ceramic or metal fine particles having a particle size of several tens of nanometers to several μm is mixed with gas to form an aerosol, which is sprayed onto a substrate through a nozzle. Is a technology to form In recent years, the AD method has attracted attention as a method capable of forming a dense film having a crystal structure similar to that of fine particles as a raw material at a low substrate temperature and at a high film formation rate.

  A film forming apparatus using the AD method will be described with reference to FIG. FIG. 2 is a schematic diagram showing the basic configuration of the film forming apparatus. In the figure, 21 is a deposition substrate, 22 is an XY stage for moving the deposition substrate 21, 23 is a nozzle, 24 is a deposition chamber, 25 is a classifier, 26 is an aerosol generator, and 27 is a high-pressure gas supply source. , 28 is a mass flow controller, 29 is a pipeline, and arrows in the figure schematically show the substrate scanning direction. Raw material fine particles made of ceramics or metal are mixed with a carrier gas (not shown) supplied via a mass flow controller 28 in the aerosol generator 26 to be aerosolized. The inside of the film forming chamber 24 is depressurized to about 50 Pa by a vacuum pump (not shown), and the raw material fine particles aerosolized by the gas flow generated by the differential pressure between this pressure and the pressure inside the aerosol generator 26. Is introduced into the film forming chamber 24 through the classifier 25, accelerated through the nozzle 23, and sprayed onto the film formation substrate 21. The raw material fine particles conveyed by the gas are accelerated up to several hundred m / s by passing through a nozzle having a minute opening of 1 mm or less.

  The accelerated raw material fine particles collide with the deposition target substrate 21, and the kinetic energy is released at a stretch, so that a film is formed. However, even if all the kinetic energy of the accelerated raw material fine particles is spent on raising the temperature of the raw material fine particles that have collided with the substrate, the temperature is about an order of magnitude compared to the temperature necessary for sintering ceramics, for example. There are many unclear points about the mechanism by which a low and dense film body can be obtained. However, it is considered that the crushing generated at the time of substrate collision of raw material fine particles plays an important role in the film forming process. Note that “crushing of raw material fine particles” means both crushing of raw material fine particles that have come to the substrate and crushing of raw material fine particles that have already adhered to the substrate surface.

  That is, in Japanese Patent Application Laid-Open No. 2003-73855, in the case of raw material fine particles made of a brittle material, the average particle diameter of the fine particles is 50 nm or more, and the shape thereof is an aspherical irregular shape, at least at one or more corners. It is disclosed that a dense film-formed body can be obtained as a result of having a shape having, because the impact force at the time of substrate collision is concentrated on the corner portion and the crushing of the raw material fine particles is promoted.

Also, “Influence of Carrier Gas Conditions on Electrical and Optical Properties of Pb (Zr, Ti) O ₃ Thin Films Prepared by Aerosol Deposition.” J. et al. Appl. Phys. Vol. 40, 5528-5532 (2001), it is also reported that an optically transparent 10 μm thick PZT (PbZrTiO ₃ ) film is formed by appropriately selecting the type of carrier gas. .
JP 2003-73855 A Jpn. J. et al. Appl. Phys. Vol. 40, 5528-5532 (2001)

  However, as a result of systematic examination for forming an oxide film with a large film thickness by our AD method, a film with a thickness of about 10 μm shows a relatively good light transmittance. When the film thickness is larger than that, the light transmittance is gradually impaired. For example, it has been found that there is a problem that almost no light is transmitted in a film-formed body having a film thickness exceeding about 50 μm.

To solve the above problem,
The first means provided by the present invention include:
The raw material fine particles made of oxide are mixed with a carrier gas to form an aerosol, and together with the carrier gas, the raw material fine particles are accelerated through a nozzle and jetted toward the surface of the deposition substrate to form a film-formed body in a reduced pressure chamber. An aerosol deposition method, in which the surface of the raw material fine particles is in an oxygen-deficient state, and the carrier gas has an oxidizing property.

The second means provided by the present invention includes
In the first means, the oxygen-deficient state on the surface of the raw material fine particles is formed by heat-treating the raw material fine particles in a reducing atmosphere. Is the method.

The third means provided by the present invention includes
In the first or second means, the carrier gas contains oxygen, and is a method of forming a film formation by an aerosol deposition method.

Furthermore, the fourth means provided by the present invention includes:
In any one of the first to third means, the film forming body has a light transmission property in a visible light region or a near infrared light region. is there.

  An oxide film formed by the AD method, which exhibits good light transmission at a relatively thin stage (˜7 μm), but the light transmission decreases as the film thickness increases. As a result of observing the structure of the body with an electron microscope, a dense film was formed at the stage where the film thickness was thin. Almost no pores were observed at the crystal grain boundaries. It became clear that the presence of pores at the grain boundaries tended to be observed.

  That is, the present invention increases the chemical activity by making the surface of the raw material fine particles made of oxide in an oxygen-deficient state, and releases the energy (movement of the raw material fine particles) when the raw material fine particles collide with the substrate. It promotes intergranular bonding induced by not only energy but also energy released by crushing raw material fine particles), and prevents the generation of pores.

  According to the present invention, it is possible to stably form a film-formed body made of an oxide having an ultra-thickness of 50 μm and good light transmittance using the AD method.

  Hereinafter, embodiments of the present invention will be described in detail using examples.

PZT (PbZr _0.52 Ti _0.48 O ₃ ) particles having an average particle diameter of 0.8 μm were used as the raw material fine particles. The raw material fine particles were first heat-treated in an oxygen atmosphere at 1000 ° C. for 6 hours, and then heat-treated in a hydrogen atmosphere under the conditions described later. After heat treatment in a hydrogen atmosphere, a film-formed body made of PZT having a thickness of 50 μm was formed using oxygen as a carrier gas. The nozzle opening of the nozzle is 5 nm × 0.3 nm, and the substrate used is quartz glass. The carrier gas flow rate was 4 l / min. At this time, the substrate collision speed of the PZT fine particles ejected from the nozzle was 240 m / s, and the deposition speed was 10 μm / min.

  FIG. 1 shows the relationship between the heat treatment conditions (heat treatment temperature and heat treatment time) of the PZT raw material fine particles in a hydrogen atmosphere and the light transmittance of the formed PZT film having a thickness of 50 μm. The measurement wavelength was 800 nm. In the figure, ◯ (white circle) indicates the heat treatment time and heat treatment temperature at which a PZT film having a transmittance of 50% or more was obtained, and ● (black circle) indicates a PZT film having a transmittance of 50% or less. Shows the heat treatment temperature and heat treatment time obtained. Moreover, the broken line in the figure is a line schematically showing the boundaries thereof.

  In the figure, the ● (black circle) mark at the origin is the case where heat treatment was not performed in a hydrogen atmosphere.

YIG (Y ₃ Fe ₅ O ₁₂ ) particles having an average particle diameter of 0.7 μm were used as the raw material fine particles. As in Example 1, the raw material fine particles were first heat-treated in an oxygen atmosphere at 1000 ° C. for 6 hours, and then heat-treated in a hydrogen atmosphere under the conditions described later. After heat treatment under a hydrogen atmosphere, a film-formed body made of YIG having a thickness of 50 μm was formed under the same conditions as in Example 1.

  In the case of YIG, since light is not originally transmitted in the visible light region, the light transmittance of the deposited YIG film with a thickness of 50 μm is measured using infrared light having a wavelength of 1.55 μm. The relationship with the heat treatment conditions was obtained. As a result, a YIG film having a transmittance of 50% or more was obtained under substantially the same conditions as the heat treatment conditions shown in FIG.

  As mentioned above, although this invention was demonstrated in detail using the Example, this invention is not restricted to the raw material microparticles | fine-particles described in the Example, or the film-forming body material, It is with respect to the oxide material which has a light transmittance as the attribute. Applicable. Moreover, although the case where hydrogen is used in the examples as the reducing atmosphere for forming the oxygen-deficient layer on the surface of the raw material fine particles has been described, the present invention is not limited to the case where hydrogen is used at all. Therefore, an atmosphere exhibiting reducibility at the heat treatment temperature, such as a nitrogen atmosphere, can be appropriately selected. Furthermore, in the present embodiment, only the case of oxygen was described as the oxidizing atmosphere, but the atmosphere is not limited to oxygen at all, and the air may vary depending on the relationship between the raw material fine particles or the film forming material. Alternatively, a mixed atmosphere of air and oxygen can be selected as appropriate.

  The film forming method according to the present invention is useful for forming a light-transmitting thick film forming body using the AD method, and industrial fields related to parts and materials using the film forming body. Is available in

It is a figure which shows the relationship between heat processing conditions and light transmittance. It is the schematic which showed the basic composition of the film-forming apparatus using AD method.

Explanation of symbols

21 Deposition substrate 22 XY stage 23 Nozzle 24 Deposition chamber 25 Classifier 26 Aerosol generator 27 High pressure gas supply source 28 Mass flow controller 29 Pipeline

Claims (4)

  The raw material fine particles made of oxide are mixed with a carrier gas to form an aerosol, and together with the carrier gas, the raw material fine particles are accelerated through a nozzle and jetted toward the surface of the substrate to be deposited to form a film-formed body in the reduced pressure chamber. A method for forming a film-forming body by an aerosol deposition method, wherein the surface of the raw material fine particles is in an oxygen-deficient state and the carrier gas has oxidizing properties.   The method for forming a film-forming body by an aerosol deposition method according to claim 1, wherein the oxygen-deficient state on the surface of the raw material fine particles is formed by heat-treating the raw material fine particles in a reducing atmosphere.   The method for forming a film-forming body by the aerosol deposition method according to claim 1, wherein the carrier gas contains oxygen. The method for forming a film-forming body by the aerosol deposition method according to claim 1, wherein the film-forming body has light transmittance in a visible light region or a near infrared light region.

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