JP2005330555A - Method for producing dielectric ceramic thick film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a dielectric ceramic thick film having satisfactory dielectric properties without performing heat treatment at the time of forming a dielectric ceramic thick film on a substrate made of metal or the like by an aerosol gas deposition process. <P>SOLUTION: In the case where the particulates of a dielectric ceramic material are made into an aerosol, are jetted onto a metal substrate arranged inside a decompressed chamber through a nozzle, and are collided, so as to be deposited, the dielectric ceramic thick film is formed in such a manner that, compared with the average particle diameter of the particulates directly collided against the surface of the substrate in the initial stage, the average particle diameter of the particulates collided in the subsequent stage is made larger. Further, the average particle diameter in the initial film formation stage is 0.3 to 0.6 μm and the average particle diameter in the subsequent film formation stage is 0.4 to 8.0 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a piezoelectric ceramic thick film by an aerosol gas deposition method, and in particular, by controlling the particle size to be deposited, the piezoelectric ceramic thickness can be obtained without causing damage to the substrate and without heat treatment. The present invention relates to a film manufacturing method.

Lead zirconate titanate (Pb (Zr, Ti) O ₃ , hereinafter abbreviated as PZT) has excellent piezoelectric properties, and has been widely applied to electronic devices such as actuators, sensors, filters, and sounding elements.

  In recent years, the above-mentioned device has been remarkably reduced in size and height, and attempts to develop a microactuator have been actively made by combining a semiconductor manufacturing process and a PZT film. In order to fuse the piezoelectric ceramic with the semiconductor process, a technique for forming a PZT film on the Si substrate is required. At present, the sol-gel method, MO-CVD method, sputtering method and the like are being put to practical use as the formation method.

  However, in order to apply to a device using a PZT film as an actuator, the film thickness is generally required to be 10 μm or more. In the sol-gel method, the MO-CVD method, the sputtering method, etc., the film formation speed is slow. Therefore, when actually forming a film, the limit is around 1 μm, and the application to the actuator is difficult, and it is mainly applied as a sensor. There are many cases.

  In the above situation, the aerosol gas deposition method (hereinafter abbreviated as AD method) has been studied as a process capable of forming a thick film at a relatively low temperature. The AD method is a method in which fine particles such as ceramic and metal are mixed in a gas to be aerosolized, collide and deposit through a nozzle on a substrate placed in a vacuum chamber, and a thick film is formed on the substrate. As an example, there is a technique disclosed in Patent Document 1. Further, Non-Patent Document 1 is a report of forming a PZT thick film of 10 μm or more on a stainless steel substrate by the AD method.

JP 2002-235181 A Formation of PZT thick film for micro actuator: ULVAC TECHNICAL JOURNAL No.57, p.6, (2002)

  However, when the PZT powder is formed on the stainless steel substrate by the AD method, there is a difficulty that if the particle size of the PZT powder to be collided is wrongly selected, the adhesion with the substrate cannot be secured. That is, if the particle size is too small, collision energy cannot be obtained, the hardness as a film cannot be secured, and film formation becomes impossible. On the other hand, if the particle size is too large, the collision energy is too large and the substrate is damaged, and film formation becomes impossible. As for this point, as a result of research leading to the present invention, in the AD method, when forming a film using one type of PZT powder having an average particle diameter, the hardness of the film is ensured and there is no damage to the substrate. It has been found that the average particle size is 0.3-0.6 μm.

However, focusing on the piezoelectric characteristics, when the PZT powder having the average particle diameter collides and is deposited using the AD method, the ceramic particles are pulverized to the nano level by colliding with the fine particles accelerated to the subsonic speed on the substrate. In addition, the piezoelectric properties of the PZT thick film after film formation are very fine compared to ordinary sintered ceramics, because it is based on the principle that broken particles are integrated by the emergence of a new surface. There is a problem that it is inferior. In order to solve this problem, the film is formed by the AD method, and then heat treatment is applied to grow the finely pulverized particles. The piezoelectric properties are improved and the heat treatment at 850 ° C. is equivalent to the sintered ceramic. It has been reported that the following piezoelectric characteristics can be obtained. However, according to this method, when an inexpensive metal material such as stainless steel is used as the substrate, the substrate is oxidized during the heat treatment, or the substrate and lead react to deteriorate the piezoelectric characteristics. Therefore, there has been a problem that the substrate material is limited to a Pt / Ti / SiO ₂ / Si substrate or a ceramic substrate. Furthermore, there is a problem that peeling occurs due to the difference in thermal expansion coefficient between the substrate and the PZT thick film by applying heat treatment.

  In this situation, an object of the present invention is to form a piezoelectric ceramic thick film on a substrate such as metal by an aerosol gas deposition method, and to provide a method for manufacturing a piezoelectric ceramic thick film having good piezoelectric characteristics without heat treatment. There is.

  The present invention directly converts the fine particles of a piezoelectric ceramic material such as PZT into an aerosol, and directly forms the above-mentioned when forming a thick film by an aerosol gas deposition method in which the particles are collided and deposited through a nozzle on a substrate placed in a decompressed chamber. It is characterized in that the average particle size of the fine particles to be collided after that is larger than the average particle size of the fine particles to be collided on the substrate, which effectively acts on the piezoelectric characteristics and has an adhesion property to the substrate such as metal. A method for producing a good ceramic thick film is provided.

  That is, in the method for producing a piezoelectric ceramic thick film according to the first aspect of the present invention, aerosol gas particles are produced in which fine particles of a piezoelectric ceramic material are aerosolized, sprayed through a nozzle onto a substrate placed in a decompressed chamber, and collided to deposit. In the method of manufacturing a piezoelectric ceramic thick film by the position method, the average particle diameter of the fine particles to be directly injected and collided on the substrate in the initial stage of deposition is the average particle diameter of the fine particles to be injected and collided and deposited in the subsequent stage. It is characterized by being smaller than the diameter.

  A method for producing a piezoelectric ceramic thick film according to a second invention is the method for producing a piezoelectric ceramic thick film according to the first invention, wherein the substrate is a metal substrate.

  The method for manufacturing a piezoelectric ceramic thick film according to a third aspect of the invention is characterized in that the average particle size of the fine particles deposited and collided directly on the substrate in the initial stage is 0.3 to 0.6 μm. It is a manufacturing method of the piezoelectric ceramic thick film of 1st invention.

  The piezoelectric ceramic thick film manufacturing method of the fourth invention is characterized in that the average particle size of the fine particles to be collided and deposited in the subsequent stage is 0.4 to 8.0 μm. This is a method for producing a ceramic thick film.

  Conventionally, in a method of forming a PZT thick film by the AD method, heat treatment is required to improve the piezoelectric characteristics of the PZT thick film. Therefore, although the substrate material is limited to Si substrate or ceramic substrate, according to the present invention, heat treatment is not applied in the formation of piezoelectric ceramic thick film on an inexpensive metal substrate, particularly stainless steel substrate or copper substrate. Also, it is possible to obtain piezoelectric characteristics equivalent to those of sintered ceramics. Therefore, in the manufacturing method of the present invention, an inexpensive stainless steel substrate or copper substrate can be selected, and since no heat treatment is required, the manufacturing cost can be greatly reduced, and the industrial merit is great.

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

  FIG. 2 is a schematic view showing an apparatus for forming a piezoelectric ceramic thick film by the AD method used in the embodiment of the present invention. A nozzle 2 is attached to the film forming chamber 1, and a frame 4 for fixing the substrate 3 is attached to the tip of the nozzle 2. A vacuum pipe 5 and a vacuum pump 6 are connected to the film forming chamber 1. The nozzle 2 is connected to an aerosol generator 7 outside the film forming chamber 1. The vacuum pipe 5 and the vacuum pump 6 depressurize the film forming chamber 1. Film formation is performed by colliding and depositing the fine powder, which has been aerosolized, into the film forming chamber 1, which has been reduced in pressure, onto the substrate 3 through the nozzle 2.

  First, in order to form a film on the substrate 3, a stainless substrate having a thickness of 100 μm was attached to the frame 4, and the piezoelectric ceramic powder was put into the aerosol generator 7. The piezoelectric ceramic powder used is a PZT-Nb fine powder, and the adjustment of the average particle diameter is controlled by changing the length of the ball mill grinding time. D (average particle diameter) = 0.4 μm, D = 1. Six types of powders of 0 μm, D = 2.0 μm, D = 5.0 μm, D = 8.0 μm, and D = 10.0 μm were prepared.

  First, for the film formation on the metal substrate, a D = 0.4 μm powder having good adhesion to the metal substrate was used. The film forming conditions are shown in Table 1. The number of scans and the scanning speed of the nozzle were adjusted so that the film thickness was 2 μm under the conditions shown in Table 1.

Next, in order to increase the particle size of the powder to be collided, the powder in the aerosol generator is replaced with the same ceramic material having an average particle size of D = 1.0 μm, and the same substrate as shown in Table 1 is used again. Film formation was performed under conditions. Then, the number of scans and the scanning speed of the nozzle were adjusted so that the ceramic film thickness was 12 μm. In addition, film formation was performed in the same manner for each of the powders D = 2.0 μm, D = 5.0 μm, D = 8.0 μm, and D = 10.0 μm. Furthermore, for the sake of comparison, when not replaced (D = 0.4 μm is continued until the film thickness reaches 12 μm), an electrode film is formed on the upper surface of the PZT thick film on the stainless steel substrate after film formation. and measured the piezoelectric constant _{d 31.} The result is shown in FIG.

  It can be seen that the PZT thick film according to the present invention has excellent piezoelectric characteristics. Here, in the case of powder of D = 10.0 μm, the surface of the formed thick film becomes very rough, and the quality of the thick film is likely to vary. Therefore, the average particle size used according to the present invention is D = 0. 4 to 8.0 μm is optimal.

  In the AD method, when one kind of PZT powder having an average particle diameter is used, the optimum average particle diameter of PZT that ensures the hardness of the film and does not damage the substrate is as described above. It has been found to be 0.3-0.6 μm. Even when two kinds of ceramic materials having an average particle diameter are used as in the present invention, this range is suitable for the average particle diameter of the ceramic material used in the initial film formation.

The figure which shows the piezoelectric characteristic of the PZT thick film by this invention. The schematic diagram which shows the film-forming apparatus by AD method in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Deposition chamber 2 Nozzle 3 Substrate 4 Frame 5 Vacuum piping 6 Vacuum pump 7 Aerosol generator

Claims (4)

  In the method for producing a piezoelectric ceramic thick film by the aerosol gas deposition method, fine particles of a piezoelectric ceramic material are aerosolized, sprayed through a nozzle onto a substrate placed in a decompressed chamber, and collided by deposition. In the production of a piezoelectric ceramic thick film, the average particle size of the fine particles sprayed and collided directly on the substrate is made smaller than the average particle size of the fine particles ejected and collided in the subsequent stage Method.   The method of manufacturing a piezoelectric ceramic thick film according to claim 1, wherein the substrate is a metal substrate.   2. The method of manufacturing a piezoelectric ceramic thick film according to claim 1, wherein the average particle size of the fine particles to be jetted, collided and deposited directly on the substrate in the initial stage is 0.3 to 0.6 [mu] m.   4. The method of manufacturing a piezoelectric ceramic thick film according to claim 3, wherein the average particle size of the fine particles to be collided and deposited in the subsequent step is 0.4 to 8.0 [mu] m.

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