JP2014154741A - Method of manufacturing electromechanical conversion film, electromechanical conversion element, liquid discharge head, and ink-jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an electromechanical conversion film which improves productivity and improves uniformity of film quality within a substrate surface.SOLUTION: A method of manufacturing an electromechanical conversion film includes: an application step (1) of applying a sol-gel solution containing a composite oxide precursor onto an electrode; a film forming step (2) of forming the film by removing/drying a solvent component of the applied sol-gel solution; a first temporary calcination step (3) of forming an amorphous composite oxide film by calcinating the formed film through conduction heating or convection heating and removing an organic component; a laminated film forming step (4) of forming an amorphous composite oxide laminated film with desired film thickness by repeating the steps (1) to (3) at least once or more; a second temporary calcination step (5) of uniformly thermally decomposing the entire laminated film by calcinating the entire amorphous composite oxide laminated film through congestion heating; a main calcination step (6) of forming a crystalline composite oxide film by calcinating the amorphous composite oxide laminated film; and a laminated film forming step (7) of forming a crystalline composite oxide laminated film with desired film thickness by repeating the steps (1) to (6) at least once or more.

Description

  The present invention relates to an electromechanical conversion film technology, and more particularly, a method for manufacturing an electromechanical conversion film constituting an electromechanical conversion element used as a drive source for a liquid discharge head provided in an ink jet recording apparatus, and the like. The present invention relates to an electromechanical conversion element in which an electromechanical conversion film manufactured by the above method is sandwiched between electrodes, a liquid discharge head using the electromechanical conversion element, and an ink jet recording apparatus including the liquid discharge head.

In an ink jet recording apparatus used as an image forming apparatus such as a printer, a facsimile machine, and a copying apparatus, an electromechanical conversion element is used as a drive source of a liquid discharge head.
There are known liquid ejection heads that use a piezoelectric actuator in a longitudinal vibration mode that expands and contracts in the axial direction of an electromechanical transducer, and those that use a piezoelectric actuator in a flexural vibration mode.
In such a piezoelectric actuator, it is preferable that a large piezoelectric constant is obtained and that the in-plane variation of the piezoelectric performance of the piezoelectric film is small.
Considering these points, a piezoelectric film having excellent crystal orientation is preferable. As a technique related to crystal orientation, it is known to use a composite oxide film such as lead zirconate titanate (PZT) as a piezoelectric film.
Various researches have been made on piezoelectric films. For example, a PZT layer is applied before organic thermal decomposition of a buffer layer (mainly PbTiO ₃ ) formed on a substrate, and both layers are subjected to organic heat. A method of manufacturing a PZT thin film by decomposing and performing a crystallization heat treatment (430 to 500 ° C.) has been proposed. In the pyrolysis step, the baking is performed in two stages of baking and RTA pyrolysis. According to this sol-gel method, a ferroelectric crystallized thin film made of PZT and a capacitor using the same can be manufactured at a low temperature of 500 ° C. or less (see Patent Document 1).
In addition, when forming a PZT film by the sol-gel method, there is a method of heating in a state where the substrate is adsorbed by an apparatus including a hot plate in which a plurality of through holes are formed in the step of gelling the organometallic sol. Proposed. According to this method, warpage of the wafer is prevented, the thermal decomposition conditions in the wafer surface are uniform, crystal orientation variation is suppressed, and in-plane uniformity of piezoelectric characteristics is obtained (see Patent Document 2).
Further, there has been proposed a method of forming a PZT film by a sol-gel method, omitting thermal decomposition, and using only a drying process and a main baking process. That is, after the PZT thin film is laminated until a desired film thickness is obtained in the drying process, the main baking is performed for a long time with the RTA apparatus, and thermal decomposition and crystallization are simultaneously advanced. According to this method, the film forming temperature can be lowered and shortened, the leakage current can be reduced, and the manufacturing process can be simplified as compared with the conventional technique (see Patent Document 3).

  As described above, various methods for producing electromechanical conversion films by the sol-gel method have been proposed, but they are not yet sufficient, and it is desired to develop a production method with high productivity and high film quality uniformity in the substrate surface. Yes.

As described above, the method for producing an electromechanical conversion film by the sol-gel method has a problem that the characteristics of the formed complex oxide film are not uniform within the substrate surface.
In the sol-gel method, a complex oxide precursor-containing solution (sol-gel solution) for forming an electromechanical conversion film is applied onto an electrode provided on a substrate surface by spin coating or the like, and then dried and fired. A composite oxide film is used. Firing is generally divided into provisional firing (thermal decomposition) and main firing, and finally a crystalline composite oxide film is formed.
As a reason why the characteristics in the substrate plane are not uniform, temperature variation is generated at the time of firing the composite oxide film as a major problem factor. The electromechanical conversion film is sandwiched between electrodes (lower electrode and upper electrode) arranged to face each other to form an electromechanical conversion element.
In particular, in a manufacturing method provided with a drying process, a temporary baking process (amorphous film formation), and a main baking process (crystalline film formation), the temporary baking process is performed by conduction heating or convection heating using a hot plate apparatus. If this is the case, temperature variation will occur even more.
As for temperature variation in baking by conduction heating or convection heating using a hot plate apparatus, the symmetry of the film configuration on the substrate surface is broken by forming the composite oxide film by the lamination method, and temperature is added thereto. And the thermal expansion coefficient cause warpage of the substrate. This warpage causes a temperature difference between the portion where the complex oxide film formed on the substrate is in contact with the hot plate surface and the portion where it is not. As a result, the state of the composite oxide film after pre-baking in the substrate surface, that is, the thermal decomposition state is different, and the film quality of the composite oxide film is different.
In other words, in the pre-baking step, firing by conduction heating or convection heating using a hot plate apparatus is advantageous in terms of productivity, but it reduces temperature variation in the substrate surface and reduces the complex oxide film quality. There is a need to improve uniformity.
On the other hand, as a method other than the hot plate, there is an RTA (Rapid Thermal Annealing) method. However, since the RTA method generally uses a method of heating with non-contact radiant heat (radiant heating), there is a feature that even if the substrate is warped, temperature variation is unlikely to occur. Therefore, it is advantageous from the viewpoint of improving the uniformity of the film quality within the substrate surface to carry out the preliminary baking step by the RTA method.
However, the RTA apparatus used for the RTA method has a quartz chamber for covering the lamp, and the wafer is heated in the chamber. For this reason, volatile components when thermally decomposed adhere to the chamber and become contaminated. This contamination absorbs the energy of heat radiation, and the wafer becomes difficult to be heated. For this reason, since maintenance of a chamber is required and also a carrier gas for replacing the atmosphere in the chamber is required, maintenance and expensive equipment installation are required. Further, in terms of productivity, the RTA apparatus requires a time for opening and closing the chamber and a heat treatment from room temperature as compared with the hot plate apparatus, and therefore, the productivity is inferior.
That is, in the pre-baking step, firing by radiant heating using an RTA apparatus is advantageous from the viewpoint of improving the uniformity of the composite oxide film quality, but has a problem of poor productivity.

  The present invention has been made in view of the above prior art, and in the sol-gel method for producing an electromechanical conversion film by a process including a coating process, a film forming process, a temporary baking process, and a main baking process, the productivity is high, It is an object of the present invention to provide a method for producing an electromechanical conversion film with high uniformity of film quality within the substrate surface.

As a result of intensive studies, the present inventors have conducted a first temporary baking in which film formation for each repeated cycle is performed by conduction heating or convection heating (hot plate apparatus) in the temporary baking step (thermal decomposition: amorphous film formation). It has been found that the above problems can be solved by combining the process and the second pre-baking process in which the entire laminated film formed by the desired repetition is performed by radiant heating (RTA apparatus).
That is, the above problem is a manufacturing method for forming an electromechanical conversion film,
(1) a coating step of coating a sol-gel solution containing a composite oxide precursor for forming an electromechanical conversion film on an electrode;
(2) a film formation step of removing and drying the solvent component of the applied sol-gel solution to form a film;
(3) First calcination step of firing the formed film by conduction heating or convection heating to remove an organic component bonded to the complex oxide precursor to form an amorphous complex oxide film When,
(4) Steps (1) to (3) are repeated at least once to form an amorphous composite oxide layered film having a desired film thickness,
(5) a second temporary firing step in which the entire amorphous composite oxide multilayer film is fired by radiation heating, and the entire multilayer film is thermally decomposed uniformly;
(6) a main firing step of firing the amorphous composite oxide laminated film obtained in the step (5) to form a crystalline composite oxide film;
(7) The above steps (1) to (6) are repeated at least once, and a laminated film forming step of forming a crystalline composite oxide laminated film having a desired film thickness;
It solves by the manufacturing method of the electromechanical conversion film characterized by having.

  According to the method for producing an electromechanical conversion film of the present invention, in the first preliminary firing step of forming an amorphous composite oxide, firing by conduction heating or convection heating is performed, and an amorphous composite oxide stack is formed. In the second pre-baking step for forming the film, since the baking is performed by radiant heating, the advantages of the conductive heating or convection heating method and the advantages of the radiant heating method are utilized, respectively, and the productivity is high and the substrate surface Thus, an electromechanical conversion film having high film quality uniformity is provided.

It is a flowchart for demonstrating the manufacturing process in the manufacturing method of the electromechanical conversion film of this invention. It is the schematic which shows the structural example of the liquid discharge head provided with the electromechanical conversion element of this invention. FIG. 3 is a schematic diagram illustrating a configuration example in which a plurality of single liquid ejection heads illustrated in FIG. 2 are arranged. It is a perspective explanatory view showing an example of an ink jet recording apparatus equipped with the liquid discharge head of the present invention. It is side surface explanatory drawing of the mechanism part of the inkjet recording device shown in FIG. It is the PE hysteresis curve of the center part and outer peripheral part of the board | substrate of the case (a) which combines a hot plate apparatus and an RTA apparatus, and the case (b) only of a hot plate apparatus. It is a figure which shows the XRD evaluation result of the baking film | membrane after repeating a coating process-a 1st temporary baking process 3 cycles (The temperature of a hotplate apparatus: (a) 500 degreeC, (b) 550 degreeC). It is each PE hysteresis curve in the center part and outer peripheral part of a board | substrate in each of the temperature of a hotplate apparatus 300 degreeC, 400 degreeC, 500 degreeC, and 580 degreeC. It is a figure which shows the piezoelectric constant (d31) in the center part and outer peripheral part of a board | substrate in each of the temperature of a hotplate apparatus 300 degreeC, 400 degreeC, 500 degreeC, and 580 degreeC.

As described above, the manufacturing method of the electromechanical conversion film in the present invention is as follows.
(1) a coating step of coating a sol-gel solution containing a composite oxide precursor for forming an electromechanical conversion film on an electrode;
(2) a film formation step of removing and drying the solvent component of the applied sol-gel solution to form a film;
(3) First calcination step of firing the formed film by conduction heating or convection heating to remove an organic component bonded to the complex oxide precursor to form an amorphous complex oxide film When,
(4) Steps (1) to (3) are repeated at least once to form an amorphous composite oxide layered film having a desired film thickness,
(5) a second temporary firing step in which the entire amorphous composite oxide multilayer film is fired by radiation heating, and the entire multilayer film is thermally decomposed uniformly;
(6) a main firing step of firing the amorphous composite oxide laminated film obtained in the step (5) to form a crystalline composite oxide film;
(7) The above steps (1) to (6) are repeated at least once, and a laminated film forming step of forming a crystalline composite oxide laminated film having a desired film thickness;
It is characterized by having.
The means for baking by conduction heating or convection heating is preferably a hot plate apparatus, and the means for baking by radiant heating is preferably an RTA apparatus.
Here, the hot plate device is a non-contact state in which a substrate is placed on a hot plate surface heated by a heat source and heated in a contact state (conduction heating), or a clearance is provided between the hot plate surface and the substrate. It is an apparatus which has a means to heat by (convection heating). As the substrate, a wafer such as Si can be used.
On the other hand, the RTA apparatus is an apparatus having means for heating (radiant heating) the substrate in a non-contact state by radiant heat radiated from a heat source.
RTA is an abbreviation for Rapid Thermal Annealing, and is a process of performing thermal decomposition or firing at a predetermined temperature for several seconds to several minutes. Specifically, in the second preliminary firing step, about 400 ° C. to 500 ° C. for about 60 seconds to Pyrolysis or baking is performed in about 5 minutes. The RTA device is a device capable of such processing.
In addition, in order to perform this baking process with an RTA apparatus, baking is performed at about 650 to 800 ° C. for about 30 seconds to 5 minutes.
Hereinafter, “first calcining step of forming an amorphous composite oxide film by baking by conduction heating or convection heating” is referred to as “amorphous composite oxide film by baking using a hot plate apparatus”. May be expressed as a “first calcining step for forming”.
Also, “second calcining step in which the entire laminated film is uniformly pyrolyzed by firing by radiant heating” is referred to as “second calcining step in which the entire laminated film is uniformly pyrolyzed by firing using the RTA apparatus”. It may be expressed as “process”.

As described above, it is advantageous from the viewpoint of productivity to perform the pre-baking process only with a hot plate apparatus, but when forming a composite oxide film by a lamination method, the symmetry of the film structure on the substrate surface is lost. Furthermore, there is a problem that the substrate is warped due to the thermal expansion coefficient, the thermal decomposition state after the preliminary firing of the composite oxide film is different, and the film quality is different. On the other hand, when the pre-baking step is performed only with the RTA apparatus, it is advantageous from the viewpoint of ensuring the uniformity of the composite oxide film (amorphous film), but there is a difficulty in productivity.
In contrast to the above, the present invention takes advantage of the advantages of firing by conduction heating or convection heating (baking by a hot plate device) and firing by radiation heating (baking by an RTA device), respectively, and a temporary firing step (amorphous film) In the thermal decomposition step for forming), in the formation of each film in each repeated cycle, the first temporary baking step is performed by a hot plate apparatus, and the laminated film stacked by the repeated cycle is subjected to the second by the RTA apparatus. Since the pre-baking step is performed and the entire laminated film is thermally decomposed uniformly, an electromechanical conversion film having high productivity and high uniformity of the composite oxide film quality within the substrate surface can be obtained. As the composite oxide, for example, lead zirconate titanate (PZT) is used.

A method for producing an electromechanical conversion film by the sol-gel method of the present invention will be described with reference to FIG.
FIG. 1 shows a manufacturing process flow in the method for manufacturing an electromechanical conversion film by the sol-gel method of the present invention. In the manufacturing process flow of FIG. 1, a temporary baking step that combines firing by conduction heating or convection heating (baking by a hot plate apparatus) and baking by radiation heating (baking by an RTA apparatus), which is a feature of the present invention, The first pre-baking step and the second pre-baking step of baking the entire obtained amorphous composite oxide laminated film by radiant heating and thermally decomposing the whole laminated film uniformly.

The method for producing an electromechanical conversion film of the present invention including the steps (1) to (7) will be described in detail below.
<(1) Application process>
In the application step (1), a sol-gel solution containing a complex oxide precursor for forming an electromechanical conversion film is applied on the electrode.
The electromechanical conversion film is sandwiched between opposed electrodes (upper electrode, lower electrode) to constitute an electromechanical conversion element. In the manufacturing method of the present invention, an electrode (for example, A sol-gel solution containing a composite oxide precursor is applied onto the platinum group lower electrode). Examples of the electromechanical conversion film include materials composed of complex oxides.
Examples of the composite oxide formed from such a sol-gel solution include lead zirconate titanate (PZT) and chemical formula ABO ₃ (A = Pb, Ba, Sr, elements selected from B = Ti, Zr, Sn, And a material having an element selected from Ni, Zn, Mg, and Nb as a main component. As a concrete description, for _{example, (Pb 1-x, Ba} x) (Zr 1-y, Ti y) O 3, (Pb 1-x, Sr x) (Zr 1-y, Ti y) O ₃ etc. are mentioned. These are cases where Pb at the A site in the general formula ABO ₃ is partially substituted with Ba or Sr. Such substitution is possible with a divalent element, and the effect thereof has an effect of reducing characteristic deterioration due to evaporation of lead during heat treatment.
Examples of composite oxides other than PZT include barium titanate. In this case, it is also possible to prepare a barium titanate precursor solution by dissolving barium alkoxide and a titanium alkoxide compound in a common solvent. is there.
That is, the sol-gel liquid contains a precursor whose main component is capable of forming a composite oxide described by the chemical formula ABO ₃ .

In the following description, lead zirconate titanate (PZT) will be described as a representative example.
Lead zirconate titanate (PZT) is a solid solution of lead zirconate (PbZrO ₃ ) and lead titanate (PbTiO ₃ ), and the characteristics differ depending on the ratio. In general, a composition exhibiting excellent piezoelectric characteristics is obtained when the ratio of PbZrO ₃ and PbTiO ₃ is 53:47, and is expressed as Pb (Zr _0.53 , Ti _0.47 ) O _{3 in} the chemical formula. It is indicated as PZT (53/47).
The composite oxide precursor sol-gel solution (PZT precursor solution) applied on the electrode provided on the substrate is synthesized, for example, by using lead acetate trihydrate, isopropoxide titanium, isopropoxide zirconium as starting materials. Can be used. Here, the crystal water of lead acetate is dissolved in methoxyethanol and then dehydrated. It is preferable to make the lead amount excessive by 10 mol% with respect to the stoichiometric composition, and this can prevent crystallinity deterioration due to so-called lead loss during heat treatment.
PZT precursor solution is synthesized by dissolving isopropoxide titanium and isopropoxide zirconium in methoxyethanol, proceeding with alcohol exchange reaction and esterification reaction, and mixing with methoxyethanol solution in which lead acetate is dissolved. Can do.
Since the metal alkoxide compound is easily hydrolyzed by moisture in the atmosphere, an appropriate amount of a stabilizer such as acetylacetone, acetic acid or diethanolamine may be added to the precursor solution as a stabilizer.
In order to obtain an electromechanical conversion film free from cracks by the first pre-baking step, the second pre-baking step, and the main baking step that follows, a film thickness of about 100 nm or less can be obtained in a single coating step. Thus, it is important to adjust the precursor concentration. That is, the change from the coating film to the crystallized film involves volume shrinkage, so that the film thickness must be controlled. When used as an electromechanical conversion element of a liquid discharge head, the thickness of the PZT film is more preferably about 1 μm to 2 μm. That is, in order to obtain this film thickness by the method described above, it is necessary to repeat a dozen steps.

<(2) Film formation process>
In the film forming step (2), the solvent component of the applied sol-gel solution is removed and dried to form a film.
After the PZT precursor solution is applied on the electrode by a solution coating method such as spin coating, the solvent is dried and removed to form a film made of the PZT precursor.
The solvent can be dried and removed at about 120 ° C. That is, this drying step is desirably performed at a temperature lower than the boiling point of methoxyethanol as a solvent. The drying step is not particularly limited as long as the solvent can be removed. For example, it can be carried out using a hot plate apparatus, and since drying is near 100 ° C., the substrate provided with electrodes on the surface does not warp, so that the uniformity of the film quality is ensured. As described above, the electromechanical conversion film is formed on the electrode.

<(3) First temporary firing step>
In the first pre-baking step (3), the formed film is heated by a hot plate apparatus to remove the organic component bonded as a constituent component of the composite oxide precursor and to form an amorphous material composed of the composite oxide. The film is formed.
In the first pre-baking step, the electrode support substrate on which the above-described precursor film is formed is directly brought into contact with the hot plate surface of the hot plate apparatus and heated to bond the organic component as a precursor constituent component Thermal decomposition of (alkoxy group, acetoxy group, etc.) forms an amorphous film.
The heating (pyrolysis) temperature by the hot plate apparatus in the first calcination step is preferably 400 ° C to 500 ° C, more preferably 400 ° C to 480 ° C. When the heating (pyrolysis) temperature is lower than 400 ° C., the organic component contained in the sol-gel liquid is not decomposed, and the organic component remains in the PZT precursor and becomes an impurity, which is formed through subsequent processes. The dielectric loss of the electromechanical conversion film tends to increase. On the other hand, when the temperature exceeds 500 ° C., the stable phase that should constitute the electromechanical conversion film is hindered by the generation of the pyrochlore phase (metastable phase), and the piezoelectric constant Decrease (d31 deteriorates). For this reason, when used as an electromechanical conversion element, the characteristics of the liquid discharge head are insufficient.
That is, it is possible to give an advantage in terms of productivity by performing the first temporary baking step with a hot plate apparatus. Further, if a film formed with a thickness of about 100 nm or less in a single coating process is directly brought into contact with a hot plate apparatus through a substrate and heated at a temperature of 400 ° C. to 500 ° C., the substrate is warped. Avoided. As a result, since the entire surface of the substrate is in contact with the hot plate surface, no temperature difference occurs, and the state after the first calcination step (thermal decomposition) of the composite oxide in the substrate surface is the same. (Amorphous) film quality becomes uniform.

  In the baking by the hot plate apparatus, the hot plate surface and the substrate are usually brought into contact with each other and heated. In order to further improve the uniformity of the film quality in the substrate surface, a clearance is provided between the hot plate surface and the substrate. It is also possible to heat by convection (non-contact).

<(4) Laminated film forming step>
In the laminated film forming step (4), the above steps (1) to (3) are repeated at least once to form an amorphous laminated film having a desired film thickness.
In the production method of the present invention, in order to obtain an electromechanical conversion film free from cracks, it is preferable to control so as to obtain a film thickness of about 100 nm or less in a single coating process.
The film thickness of the electromechanical conversion film is preferably 0.5 μm to 5 μm, more preferably 1 μm to 2 μm. If the film thickness is thinner than this range, sufficient displacement cannot be generated. If the film thickness is thicker than this range, many layers are stacked, so that the number of processes increases and the process time becomes longer. That is, if the film thickness of an electromechanical conversion film, for example, a PZT film is set to about 1 μm to 2 μm, the same process needs to be repeated ten times (cycles) to obtain this film thickness.

As described above, since it is desirable that the film thickness be about 100 nm in a single coating step, the above steps (1) to (3) are repeated to form an amorphous laminated film.
For example, after applying a sol-gel solution on an electrode provided on a substrate, the solvent component is removed and dried at about 120 ° C. to form a film, and pre-baked on a hot plate set at about 450 ° C. to about 100 nm. If the cycle for forming an amorphous film is repeated three times, an amorphous laminated film of about 300 nm is formed. If an amorphous laminated film is formed in this way, the substrate surface temperature does not vary greatly between the central portion and the outer peripheral portion, so that a uniform film can be obtained. For example, after repeating the above steps (1) to (3) for 3 cycles, it is possible to move to the second pre-baking step of the next step.

<(5) 2nd temporary baking process. >
In the second pre-baking step (5), the entire amorphous laminated film obtained is heated by an RTA apparatus and uniformly pyrolyzed. In the second pre-baking step, the entire laminated film is heated with radiant heat in a non-contact state using an RTA apparatus, and further a thermal decomposition reaction is performed to form a uniform amorphous composite oxide.
The heating (pyrolysis) temperature in the second pre-baking step is preferably higher than the heating temperature in the first pre-baking step and not higher than 530 ° C. By setting the temperature higher than the heating temperature of the first preliminary baking step and lower than 530 ° C., the organic components remaining in the first preliminary baking step can be decomposed, and the decomposition is performed uniformly within the substrate surface. It can be made to be.
For example, when heating (firing) is set to about 450 ° C. in the first preliminary baking step, heating and baking is performed with the temperature by thermal radiation of the RTA apparatus set to about 480 ° C. Since there is no difference in temperature at the part, a homogeneous film can be obtained.
The RTA apparatus used in the second preliminary firing step can also be used for the next (6) main firing step. In this case, it is necessary to equip with a lamp capable of heating at a higher temperature (for example, about 700 ° C. or higher) as a device specification (spec). If such an RTA apparatus is used, after the second preliminary firing step (for example, about 480 ° C.) is performed, the temperature is increased as it is (for example, about 700 ° C.) and the next main firing step is continuously performed. Can do.

The RTA apparatus has a lamp as a radiant heat source. Depending on the position of the lamp, there are a method of heating the substrate surface from above, a method of heating from below, and a method of heating from above and below. Any specification can be used, but among these, the up-and-down heating method is the most preferable because the top-and-bottom heating method is the easiest to obtain uniform temperature of the substrate.
When the second pre-baking step is performed with an RTA apparatus, heating is performed by non-contact thermal radiation, so that even if the substrate is warped, temperature variations are unlikely to occur. For this reason, the uniformity of the film quality in the substrate surface is improved by performing the second temporary baking step by RTA.
Since the RTA apparatus can be fired by rapid heating (for example, about 10 ° C./second to about 30 ° C./second), generation of a pyrochlore phase can be avoided and a composite oxide film having desired characteristics can be formed. be able to.
Note that the RTA apparatus includes a quartz chamber for covering the lamp, and the substrate on which the complex oxide film is formed is heated in the chamber. Therefore, volatile components when pyrolyzed adhere to the inside of the chamber and are easily contaminated. This contamination absorbs heat radiation energy and makes it difficult for the substrate to be heated. Consider maintenance such as the need to clean the chamber and the introduction of a carrier gas to change the atmosphere in the chamber. It is necessary to keep it.

<(6) Main firing step>
In the main firing step (6), the amorphous laminated film obtained in the step (5) is fired (annealed) to be converted into a crystalline film.
As described above, the RTA apparatus used in the second preliminary firing step can also be used for the main firing step. If the RTA apparatus is used, the second preliminary baking step can be performed at about 480 ° C., for example, and then the temperature can be raised to about 700 ° C. to continue the main baking step.
If the amorphous laminated film obtained in the above step (5) is heated up to 700 ° C. as it is with an RTA apparatus and subjected to main firing, a crystalline film in which the uniformity of film quality within the substrate surface is maintained can be obtained. If converted and the above steps (1) to (3) are repeated three cycles, the film thickness is about 300 nm.

The pressure generating means of the liquid discharge head is a piezoelectric type that discharges ink droplets by deforming and displacing the diaphragm forming the wall surface of the discharge chamber using an electromechanical conversion element such as a piezoelectric element. As known, the piezoelectric type includes a transverse vibration (bend mode) type utilizing deformation in the d31 direction, a longitudinal vibration type utilizing deformation in the d33 direction, and a shear mode type utilizing shear deformation. It is done.
As an electromechanical conversion film obtained by the production method of the present invention, for example, a film having a transverse vibration (bend mode) type characteristic utilizing deformation in the d31 direction can be cited. In the present invention, the electromechanical conversion film will be described mainly with a transverse vibration (bend mode) type utilizing deformation in the d31 direction.

<(7) Laminated film forming step>
Steps (1) to (6) are repeated at least once to form a crystalline laminated film having a desired film thickness.
For example, if the steps (1) to (3) are repeated 3 cycles and the steps (1) to (6) are repeated 6 cycles, the film thickness is about 1.8 μm.

An electromechanical transducer is formed by patterning the upper electrode on the crystalline laminated film produced by the laminated film forming step (7).
As described above, using the PZT precursor solution, the heating temperature in the first preliminary baking step (hot plate apparatus) is set to about 450 ° C., and the heating temperature in the second temporary baking step (RTA apparatus) is about 480 ° C. If the cycle is set to be an amorphous film and the film is fired at about 700 ° C. (for example, an RTA apparatus) to be a crystalline film, there is no difference in temperature between the central portion and the outer peripheral portion of the substrate. A homogeneous film is obtained. For example, there is almost no variation in electrical characteristics (relative permittivity, dielectric loss, remanent polarization, coercive electric field) between the central portion and the outer peripheral portion of the substrate, and the same characteristics as a normal ceramic sintered body are exhibited. The piezoelectric constant d31 also shows substantially the same value (for example, about -120 pm / V) at the center and the outer periphery of the substrate, and is the same value as the ceramic sintered body.

The electromechanical conversion element of the present invention has a configuration in which an electromechanical conversion film obtained by the production method of the present invention is sandwiched between electrodes (electrodes arranged oppositely: a lower electrode and an upper electrode). A liquid discharge head is configured using such an electromechanical transducer.
The schematic diagram of FIG. 2 shows a configuration example of a droplet discharge head including the electromechanical transducer of the present invention.
The electromechanical conversion element 40 has a structure in which a lower electrode 42, an electromechanical conversion film 43, and an upper electrode 44 are sequentially stacked on a vibration plate 30 constituting a part of the pressure chamber 21 via an adhesion layer 41. ing. The pressure chamber 21 includes a pressure chamber substrate [Si substrate] 20 and a nozzle plate 10 provided with nozzles 11.
Hereinafter, each constituent layer other than the electromechanical conversion film described above will be described.

(Pressure chamber substrate [Si substrate])
As the pressure chamber substrate [Si substrate] 20, it is preferable to use a silicon single crystal substrate, and it is usually preferable to have a thickness of 600 μm to 800 μm. There are three types of plane orientations, (100), (110), and (111). In this configuration, a single crystal substrate mainly having a (111) plane orientation is mainly used.
Further, when a pressure chamber as shown in FIG. 1 is manufactured, for example, a silicon single crystal substrate can be processed using etching. As an etching method in this case, it is common to use anisotropic etching. Anisotropic etching utilizes the property that the etching rate differs with respect to the plane orientation of the crystal structure.

(Diaphragm)
A vibration plate 30 disposed on a silicon substrate (Si substrate), that is, a pressure chamber substrate [Si substrate] 20, has a thickness of several microns and includes a silicon oxide film, a silicon nitride film, a silicon oxynitride film, and each of these films. A laminated film may be used. Further, a ceramic film such as an aluminum oxide film or a zirconia film in consideration of a difference in thermal expansion may be used. These materials are insulators.
The silicon-based insulating film may be a thermal oxide film or a CVD (Chemical Vapor Deposition) deposited film, and the metal oxide film may be formed by a sputtering method.
As shown in FIG. 1, the vibration plate 30 is deformed and displaced by the force generated by the electromechanical conversion film 43, and discharges ink in the pressure chamber 21. Therefore, it is preferable that the base has a predetermined strength. For example, a film (SiO ₂ ) formed by thermally oxidizing a Si wafer used for forming the pressure chamber substrate 20 is used.
In particular, when lead zirconate titanate (PZT) is used as the material of the electromechanical conversion film 43, the linear expansion coefficient close to 8 × 10 ⁻⁶ (1 / K) of PZT is 5 ×. A material having a linear expansion coefficient of about 10 ⁻⁶ to 10 × 10 ⁻⁶ (1 / K) is preferable.

(Adhesion layer)
As described below, a platinum group electrode is preferably used as the lower electrode 42 in the present invention. However, when platinum is used for the electrode, it is necessary to provide an adhesion layer because of poor adhesion to the base (vibration plate), particularly SiO _2. There is.
As the adhesion layer 41, a metal material such as titanium or tantalum, titanium oxide, tantalum oxide, titanium nitride, tantalum nitride, or a laminated film thereof is effective. However, in the case of a conductive oxide, the diaphragm is the same oxide. Since it is an object (silicon oxide), sufficient film adhesion can be obtained without arranging these adhesion layers. In the configuration of FIG. 1, an adhesion layer 41, for example, a titanium (Ti) film is provided assuming that a platinum group electrode is used.
Here, the thickness of the adhesion layer is preferably 20 nm to 70 nm. When the film thickness is smaller than this range, there is a concern about the adhesion, and when the film thickness is larger than this range, the lower electrode 42 formed on the adhesion layer is affected.

(Lower electrode)
Since the lower electrode 42 is electrically connected as a common electrode for inputting a signal to the electromechanical transducer, the diaphragm 30 below the insulator is used as an insulator or an insulator if it is a conductor. Become.
As the lower electrode 42, a platinum group electrode made of a single metal such as platinum, rhodium, ruthenium or iridium having high heat resistance and low reactivity, or other platinum group elements mainly composed of platinum such as platinum-rhodium An electrode made of any of the above alloy materials can be used. In this invention, the form deposited on the electroconductive oxide film may be sufficient.
In addition, when PZT is used for the electromechanical conversion film, it may not be said that the platinum electrode has sufficient barrier properties with respect to lead (Pb) contained in PZT. It is possible to use an electrode made of a platinum group. Further, a conductive material film (for example, a conductive oxide) having a barrier property against lead (Pb) may be provided on the surface of the platinum electrode. By such a method, even when platinum is used for the lower electrode and PZT is used for the electromechanical conversion film, deterioration of the characteristics of the metal electrode is avoided.
In FIG. 2, since the adhesion layer 41 is formed on the vibration plate (for example, SiO ₂ film formed on the Si substrate), even when platinum is used for the lower electrode 42, Adhesion can be maintained well.
As a method for manufacturing the electrode of the lower electrode 42, a general sputtering method or vacuum film formation such as vacuum deposition can be applied. The film thickness of the lower electrode 42 is preferably about 100 nm to 300 nm.

(Upper electrode)
As the upper electrode 44, the same material as the lower electrode 42 (a platinum group electrode made of a single metal such as platinum, rhodium, ruthenium, iridium, or an electrode made of an alloy film such as platinum-rhodium) can be used.
In addition, as described above, when a complex oxide (PZT) containing lead is used as the electromechanical conversion film, the reaction between lead and the upper electrode (metal) or diffusion to the upper electrode occurs to deteriorate the piezoelectric characteristics. Therefore, a conductive material (for example, a conductive oxide) having a barrier property against lead (Pb) can be used as necessary.

The ink jet recording apparatus has many advantages such as extremely low noise and high-speed printing, and furthermore, an inexpensive plain paper having a degree of freedom of ink can be used.
A liquid discharge head used in an ink jet recording apparatus includes a nozzle that discharges ink droplets, a liquid chamber (pressure chamber) that communicates with the nozzle, and a pressure generating unit that discharges ink in the liquid chamber.
The pressure generating means is a piezo-type device that discharges ink droplets by deforming and displacing the diaphragm forming the wall surface of the liquid chamber (pressure chamber) using an electromechanical conversion element such as a piezoelectric element. There is a bubble type (thermal type) in which bubbles are generated by boiling an ink film by using an electric-thermal conversion element such as a heating resistor disposed in the discharge to discharge ink droplets. In addition, the piezoelectric type includes a longitudinal vibration type using deformation in the d33 direction, a transverse vibration (bend mode) type using deformation in the d31 direction, and a shear mode type using shear deformation. With the progress of semiconductor processes and MEMS, thin film actuators in which a liquid chamber and a piezoelectric element are directly formed on a Si substrate have been devised.
A preferable electromechanical transducer in the present invention includes a transverse vibration (bend mode) type utilizing deformation in the d31 direction.
That is, the electromechanical conversion film produced by the manufacturing method of the present invention is sandwiched between electrodes to form an electromechanical conversion element, and a liquid discharge head can be configured.
The liquid discharge head according to the present invention includes an electromechanical conversion element in which a lower electrode, an electromechanical conversion film, and an upper electrode are sequentially stacked on a diaphragm constituting a part of a pressure chamber, if necessary, with an adhesion layer. It has a provided structure (see FIG. 2).
FIG. 3 shows a plurality of single liquid ejection heads shown in FIG. In FIG. 3, reference numeral 21 is a pressure chamber, 10 is a nozzle plate, 11 is a nozzle, 20 is a pressure chamber substrate (Si substrate), 30 is a diaphragm, and 40 is an electromechanical transducer.
If a liquid discharge head is configured using an electromechanical conversion element having an electromechanical conversion film with high in-plane uniformity of the present invention, ink droplet discharge characteristics can be maintained with a driving force equivalent to that of a ceramic sintered body, and continuous. Even when ejected, stable ink droplet ejection characteristics can be maintained.

In addition, an ink jet recording apparatus can be configured by providing a liquid discharge head.
If the liquid ejection head of the present invention is used, the ejection stability, durability, and image quality are good, so that the liquid ejection head can be applied to printers used in offices and personal computers, and inkjet recording apparatuses such as MFPs.
An example of an ink jet recording apparatus equipped with the liquid discharge head of the present invention will be described with reference to FIGS. 4 is an explanatory perspective view of the recording apparatus, and FIG. 5 is an explanatory side view of a mechanism portion of the recording apparatus.

  The ink jet recording apparatus includes a carriage 93 that can move in the main scanning direction inside an apparatus main body 81, a liquid discharge head 94 that is an ink jet head that implements the present invention mounted on the carriage, and ink that supplies ink to the liquid discharge head. A paper feed cassette (or a paper feed tray) 84 that accommodates a printing mechanism portion 82 including a cartridge 95 and the like, and can stack a large number of sheets 83 from the front side in the lower portion of the apparatus main body 81. It can be inserted and removed freely, and the manual feed tray 85 for manually feeding the paper 83 can be opened, the paper 83 fed from the paper feed cassette 84 or the manual feed tray 85 is taken in, After a required image is recorded by the printing mechanism unit 82, the image is discharged onto a paper discharge tray 86 mounted on the rear side.

  The printing mechanism 82 holds a carriage 93 slidably in the main scanning direction by a main guide rod 91 and a sub guide rod 92 which are guide members horizontally mounted on left and right side plates (not shown). The liquid discharge head 94 according to the present invention that discharges ink droplets of each color (Y), cyan (C), magenta (M), and black (Bk) crosses a plurality of ink discharge ports (nozzles) with the main scanning direction. The ink droplets are mounted with the ink droplet discharge direction facing downward. In addition, each ink cartridge 95 for supplying ink of each color to the head 94 is replaceably mounted on the carriage 93.

  The ink cartridge 95 has an air port that communicates with the atmosphere above, a supply port that supplies ink to the liquid discharge head 94 below, and a porous body filled with ink inside. The ink supplied to the liquid discharge head 94 is maintained at a slight negative pressure by the capillary force. In addition, although the liquid discharge heads 94 of the respective colors are used here as the recording heads, a single head having nozzles that discharge ink droplets of the respective colors may be used.

  Here, the carriage 93 is slidably fitted to the main guide rod 91 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the sub guide rod 92 on the front side (upstream side in the paper conveyance direction). doing. In order to move and scan the carriage 93 in the main scanning direction, a timing belt 100 is stretched between a driving pulley 98 and a driven pulley 99 that are rotationally driven by a main scanning motor 97, and the timing belt 100 is moved to the carriage 93. The carriage 93 is driven to reciprocate by forward and reverse rotation of the main scanning motor 97.

  On the other hand, in order to convey the paper 83 set in the paper feed cassette 84 to the lower side of the liquid discharge head 94, the paper feed roller 101 and the friction pad 102 for separating and feeding the paper 83 from the paper feed cassette 84, and the paper 83 A guide member 103 for guiding, a conveyance roller 104 for reversing and conveying the fed paper 83, a conveyance roller 105 pressed against the peripheral surface of the conveyance roller 104, and a feed angle of the sheet 83 from the conveyance roller 104 are defined. A leading end roller 106 is provided. The transport roller 104 is rotationally driven by a sub-scanning motor 107 through a gear train.

  A printing receiving member 109 is provided as a paper guide member that guides the paper 83 sent from the transport roller 104 below the liquid discharge head 94 corresponding to the range of movement of the carriage 93 in the main scanning direction. A conveyance roller 111 and a spur 112 that are rotationally driven to send the paper 83 in the paper discharge direction are provided on the downstream side of the printing receiving member 109 in the paper conveyance direction, and the paper 83 is further delivered to the paper discharge tray 86. A roller 113 and a spur 114, and guide members 115 and 116 that form a paper discharge path are disposed.

  During recording, the liquid ejection head 94 is driven in accordance with the image signal while moving the carriage 93 to eject ink onto the stopped sheet 83 to record one line, and after the sheet 83 is conveyed by a predetermined amount Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 83 has reached the recording area, the recording operation is terminated and the paper 83 is discharged.

Further, a recovery device 117 for recovering the ejection failure of the liquid ejection head 94 is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 93. The recovery device 117 includes a cap unit, a suction unit, and a cleaning unit. The carriage 93 is moved to the recovery device 117 side during printing standby, and the liquid ejection head 94 is capped by the capping means, and the ejection port portion is kept in a wet state to prevent ejection failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant and stable ejection performance is maintained.
When a discharge failure occurs, the discharge port (nozzle) of the liquid discharge head 94 is sealed with a capping unit, and bubbles and the like are sucked out from the discharge port with a suction unit through the tube. Dust and the like are removed by the cleaning means, and the ejection failure is recovered. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.

  As described above, since the ink jet recording apparatus of the present invention is equipped with the liquid ejection head of the present invention, there is no ink droplet ejection failure due to vibration plate drive failure, and stable ink droplet ejection characteristics can be obtained. Quality is improved.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to these Examples at all. Any modification of these embodiments as appropriate without departing from the gist of the present invention is within the scope of the present invention.
Hereinafter, embodiments of the present invention will be described with reference to the drawings (FIG. 1).

[Example 1]
An electromechanical conversion film was prepared by the sol-gel method according to the following procedure to constitute an electromechanical conversion element. The electromechanical transducer is a lateral vibration (bend mode) type utilizing deformation in the d31 direction.
A thermal oxide film (film thickness of 1 micron) was formed on a silicon wafer (Si wafer), and a titanium film (film thickness of 50 nm) was formed by sputtering as an adhesion layer on the thermal oxide film. Subsequently, a platinum film (thickness: 200 nm) was formed as a lower electrode on the titanium film by sputtering. Note that the surface on which the thermal oxide film is formed plays a role as a diaphragm after subsequent processing.
Next, a sol-gel solution containing a composite oxide precursor for forming an electromechanical conversion film is applied on the lower electrode (application process), and then the solvent component of the applied sol-gel liquid is removed and dried. Filmed (film forming process).
Specifically, PZT (53/47) was formed as an electromechanical conversion film. Therefore, the synthesis of a sol-gel solution (abbreviation: PZT precursor solution) containing a complex oxide precursor for forming an electromechanical conversion film is composed of lead acetate trihydrate, isopropoxide titanium, isopropoxide zirconium as starting materials. Was used. Crystal water of lead acetate was dissolved in methoxyethanol and then dehydrated. The lead amount is 10 mol% excess relative to the stoichiometric composition. This is to prevent crystallinity deterioration due to so-called lead loss during heat treatment.
The PZT precursor solution was synthesized by dissolving isopropoxide titanium and isopropoxide zirconium in methoxyethanol, proceeding with alcohol exchange reaction and esterification reaction, and mixing with the methoxyethanol solution in which the lead acetate was dissolved. The PZT concentration was 0.1 mol / l.
This PZT precursor solution was spin-coated on a platinum film (lower electrode), and then the solvent component was removed and dried at 120 ° C. to form a film. This film formation step (drying step) is desirably performed at a temperature lower than the boiling point of methoxyethanol as a solvent. In addition, although the drying process is performed on a hot plate, the substrate (silicon wafer) does not warp because it is as low as 120 ° C. and is in the 100 ° C. range, so that the uniformity of the film quality is ensured.

As the next step, the first preliminary firing step is entered. Before describing the first preliminary firing step, the flow in this example will be described.
In this example, “application process (sol-gel solution is spin-coated on electrode)”, “film formation process (solvent component removal / drying)” and “first temporary baking process (firing by conduction heating or convection heating: “Heating by hot plate” ”was performed as a set (one cycle), and the above steps were repeated every cycle.
The subsequent “second preliminary firing step (firing by radiation heating: heating by an RTA device)” and “main firing step (for example, firing by an RTA device)” were performed once every three cycles.
In the present embodiment, the manufacturing process is configured by the flow as described above. However, the manufacturing process is not limited to this, and the second pre-baking step (by the film thickness of PZT obtained in the above one cycle) The number of repetitions of the heating by the RTA apparatus and the main baking process (heating by the RTA apparatus) can be arbitrarily changed.

In the first pre-baking step, the film formed in the film forming step is heated by a hot plate apparatus to remove the organic component bonded as a constituent component of the composite oxide precursor, thereby forming an amorphous material composed of the composite oxide. A film was formed.
Specifically, the hot plate apparatus was set to 450 ° C., and the substrate (silicon wafer) was placed on the hot plate for 3 minutes. At this time, when the temperature difference generated was measured with a thermocouple, it was 450 ° C. and 445 ° C. at the center and the outer periphery of the substrate on which the film was formed, respectively, and there was no significant difference.
After the pre-baking step was completed, the film thickness obtained in one cycle was 100 nm. From this result, the above-described coating process (application by spin coating) to first temporary baking process (temporary baking by a hot plate apparatus) were repeated three cycles. This corresponds to a so-called laminated film forming process for forming an amorphous laminated film.

After the first calcination step (temporary calcination using a hot plate apparatus) in the third cycle, the second calcination process (heating using an RTA apparatus) was started.
The second pre-baking step is a step of heating the entire amorphous laminated film formed in the laminated film forming step with an RTA apparatus.
The RTA apparatus in the present example is of an upper / lower lamp installation type, and serves as both the second temporary firing step and the post-firing main firing step. Therefore, the second preliminary firing step and the main firing step can be performed continuously by setting the sequence in the RTA apparatus.
The temperature at the center and the outer periphery of the substrate on which the laminated film was formed in the second pre-baking step was both 480 ° C., indicating the same temperature.

After the substrate is placed in the RTA apparatus, the second preliminary baking process (heating by the RTA apparatus) is performed at 480 ° C. for 5 minutes, and then the temperature is raised to 700 ° C. to perform the main baking process (heating by the RTA apparatus). Conducted for 3 minutes. After the main baking, the obtained film thickness was 300 nm.
The step of setting the main baking step after repeating the coating step to the first preliminary baking step three times was repeated six times. As a result, a PZT film having a thickness of 1.8 μm was obtained.
In the stage of only thermal decomposition by the first preliminary baking step (preliminary baking by a hot plate apparatus), there is a warp when a substrate having a film thickness of 1.8 μm is placed on the hot plate, and the center and outer periphery at this time As a result of measuring the temperature of the part, they were 450 ° C. and 410 ° C., respectively. This indicates that there is a slight difference between the portions where the substrate is not in contact with the hot plate surface due to warpage.
On the other hand, after the thermal decomposition by the second calcination step, there was no warp when measured in the same manner as described above. As a result of measuring the temperature at the center and the outer periphery at this time, both were 480 ° C. and the same temperature. Indicated. That is, it was shown that the thermal decomposition state in the whole amorphous laminated film was made uniform by thermal decomposition by RTA calcination.

  A platinum (P) film (200 nm) was formed by sputtering as an upper electrode on the obtained PZT film. The upper electrode was patterned by photolithography. As a result, an electromechanical conversion element in which an electromechanical conversion film made of PZT was sandwiched between the upper electrode and the lower electrode was formed. As shown in FIGS. 2 and 3, the electromechanical transducer 40 formed in this way is disposed on the vibration plate 30 constituting one surface of the pressure chamber substrate [Si substrate] 20 via an adhesion layer 41. Composed.

After the patterning of the upper electrode, the electrical characteristics were evaluated at each of the central portion and the outer peripheral portion of the substrate. The relative dielectric constant of the film at the center is 1220, the dielectric loss is 0.02, the remanent polarization is 19.3 μC / cm ² , the coercive electric field is 36.5 kV / cm, and it has the same characteristics as a normal ceramic sintered body. Have. The outer peripheral film has a relative dielectric constant of 1200, a dielectric loss of 0.02, a remanent polarization of 19.2 μC / cm ² , a coercive electric field of 36.5 kV / cm, and has the same characteristics as a normal ceramic sintered body. Have.
FIG. 6A shows respective PE hysteresis curves in the central portion and the outer peripheral portion of the substrate when the pre-baking process is combined with a hot plate apparatus and an RTA apparatus. In addition, FIG. 6B shows a PE hysteresis curve when the pre-baking process is performed only with the hot plate apparatus.

The electromechanical conversion ability was calculated by measuring the amount of deformation by applying an electric field with a laser Doppler vibrometer and fitting it by simulation. The piezoelectric constant d31 was -120 pm / V at the center and -119 pm / V at the outer periphery, which was also the same value as the ceramic sintered body. These variations are characteristic values that can be sufficiently designed as a liquid discharge head.
That is, in the thermal decomposition by the first temporary baking process (heating by the hot plate apparatus), although there are variations in the amorphous laminated film, the thermal decomposition is performed again in the second temporary baking process (heating by the RTA apparatus). This shows that the thermal decomposition state in the entire amorphous laminated film is made uniform.

  That is, according to the manufacturing method by the sol-gel method of the present invention, the advantages of the conductive heating or convection heating means (heating by the hot plate apparatus) and the advantages of the radiant heating means (heating by the RTA apparatus) are utilized, respectively. Thus, an electromechanical conversion film having high uniformity and high uniformity of film quality (composite oxide, for example, PZT) in the substrate surface can be obtained. This electromechanical conversion film has the same characteristics (piezoelectric constant) as the ceramic sintered body.

[Example 2]
In Example 1, although the temperature of the 1st temporary baking process (heating with a hotplate apparatus) was implemented at 450 degreeC, temperature conditions were changed and the temperature of a hotplate was 300 degreeC, 400 degreeC, 500 degreeC, and 550, respectively. Preliminary firing was carried out at a setting of ° C. At that time, the conditions were changed so that the firing temperature in the second preliminary firing step (heating by the RTA apparatus) was + 30 ° C. with respect to the set temperature of the hot plate in the first preliminary firing step. That is, the RTA firing temperature in the second preliminary firing step was set to 330 ° C., 430 ° C., 530 ° C., and 580 ° C., respectively. A PZT film was formed in the same manner as in Example 1 except that each temperature condition was set.

Here, after repeating the coating process (application by spin coating) -film formation process (drying process) -first temporary baking process (heating by a hot plate apparatus) three cycles, the second temporary baking process (by RTA apparatus) Evaluation was performed by XRD (X-ray diffraction) in a state before performing (heating). FIG. 7 shows the results when the set temperatures of the hot plate are 500 ° C. and 550 ° C.
From FIG. 7, it can be seen that under the pre-baking condition with the hot plate apparatus at 550 ° C., the pre-baking condition with the hot plate apparatus at 550 ° C. occurs even though the pyrochlore phase (metastable phase) is not generated. I understand. When such a pyrochlore phase is generated, this pyrochlore phase has the characteristics of a paraelectric phase, which is not preferable because the piezoelectric properties are inferior to the ferroelectric phase of the desired perovskite phase.

Films are formed up to 1.8 μm along the steps shown in FIG. 1 under the above temperature conditions, and an upper electrode is sputter-deposited on the formed PZT film in the same manner as in Example 1 for patterning and electromechanical conversion. It was set as the element. The electrical characteristics of this electromechanical transducer were evaluated.
FIG. 8 shows the PE hysteresis curves of the central part and the outer periphery of the substrate when the set temperature of the hot plate is 300 ° C., 400 ° C., 500 ° C., and 580 ° C., and FIG. 9 shows the piezoelectric constant (d 31).
8 and 9 that the dielectric loss is large under the temperature condition of 300 ° C. This indicates that the state of thermal decomposition is insufficient. Further, under the temperature condition of 550 ° C., a pyrochlore phase was generated, d31 was deteriorated, and the characteristics of the liquid discharge head were insufficient.
That is, the heating temperature (set temperature of the hot plate) in the first temporary baking step is preferably 400 ° C. to 500 ° C. Within this range, characteristics such as dielectric loss and d31 are maintained well, and even when used as a liquid ejection head, there is no ink droplet ejection failure due to vibration plate drive failure.

[Example 3]
In accordance with the manufacturing process shown in FIG. 1, an electromechanical conversion film (PZT film) is prepared in the same manner as in Example 1, and the droplet discharge head shown in FIG. 3 (a configuration in which a plurality of single liquid discharge heads are arranged) The electromechanical conversion element (40 in the figure) was formed.
The electromechanical conversion film (PZT film) constituting the electromechanical conversion element 40 in the figure has high productivity, can be formed by a manufacturing method with high in-plane uniformity of the composite oxide film quality, and is equivalent to bulk ceramics. Has performance.
After forming the electromechanical conversion element, the pressure chamber substrate 20 is formed by etching from the back surface of the substrate (Si wafer), and the nozzle plate 10 having the nozzle holes is joined to the pressure chamber substrate, whereby a liquid discharge head can be formed. In FIG. 3, descriptions of the liquid supply means, the flow path, and the fluid resistance are omitted.
Since the liquid discharge head is configured using the electromechanical conversion film of the present invention having performance equivalent to that of bulk ceramics, stable ink droplet discharge characteristics can be obtained, and improvement in image quality can be expected.

[Example 4]
An ink jet recording apparatus was configured by arranging the liquid discharge heads of Example 3 on a carriage 93 held by the printing mechanism unit 82 shown in FIGS. 4 and 5.
When this ink jet recording apparatus was used for printing at 2 kHz in an environment of 25 ° C., there was no ink droplet ejection failure due to diaphragm drive failure, stable ink droplet ejection characteristics were obtained, and high quality images were formed. It was done.

  That is, the electromechanical conversion film formed by the highly productive manufacturing method of the present invention has high in-plane uniformity and maintains the same characteristics (piezoelectric constant) as the ceramic sintered body. For this reason, if a piezoelectric element is formed using an electromechanical conversion film and applied to a liquid discharge head, it has excellent discharge stability and durability. Therefore, it is suitable for inkjet printers such as printers and MFPs used in offices and personal computers. Besides being applicable, it can be applied to 3D molding technology.

(Reference numerals in FIGS. 2 and 3)
10 Nozzle plate 11 Nozzle 20 Pressure chamber substrate [Si substrate]
21 Pressure chamber 30 Diaphragm 40 Electromechanical conversion element 41 Adhesion layer 42 Lower electrode 43 Electromechanical conversion film 44 Upper electrode (reference numerals in FIGS. 4 and 5)
DESCRIPTION OF SYMBOLS 81 Device main body 82 Printing mechanism part 83 Paper 84 Paper feed cassette 85 Manual feed tray 86 Paper discharge tray 91 Main guide rod 92 Subordinate guide rod 93 Carriage 94 Liquid discharge head 95 Ink cartridge 97 Main scanning motor 98 Drive pulley 99 Drive pulley 100 Timing belt DESCRIPTION OF SYMBOLS 101 Feed roller 102 Friction pad 103 Guide member 104 Conveyance roller 105 Conveyance roller 106 Front end roller 107 Sub scanning motor 109 Printing receiving member 111 Conveyance roller 112 Spur 113 Discharge roller 114 Spur 115,116 Guide member 117 Recovery device

Japanese Patent No. 3427795 Japanese Patent No. 4110503 Japanese Patent Laid-Open No. 08-340084

Claims (8)

A manufacturing method for forming an electromechanical conversion film,
(1) a coating step of coating a sol-gel solution containing a composite oxide precursor for forming an electromechanical conversion film on an electrode;
(2) a film formation step of removing and drying the solvent component of the applied sol-gel solution to form a film;
(3) First calcination step of firing the formed film by conduction heating or convection heating to remove an organic component bonded to the complex oxide precursor to form an amorphous complex oxide film When,
(4) Steps (1) to (3) are repeated at least once to form an amorphous composite oxide layered film having a desired film thickness,
(5) a second temporary firing step in which the entire amorphous composite oxide multilayer film is fired by radiation heating, and the entire multilayer film is thermally decomposed uniformly;
(6) a main firing step of firing the amorphous composite oxide laminated film obtained in the step (5) to form a crystalline composite oxide film;
(7) The above steps (1) to (6) are repeated at least once, and a laminated film forming step of forming a crystalline composite oxide laminated film having a desired film thickness;
A method for producing an electromechanical conversion film comprising:   The method for producing an electromechanical conversion film according to claim 1, wherein the baking by the conduction heating or the convection heating is performed by a hot plate apparatus, and the baking by the radiant heating is performed by an RTA apparatus.   The method for producing an electromechanical conversion film according to claim 1 or 2, wherein the heating in the first pre-baking step is performed at 400C to 500C.   The heating in the second pre-baking step is performed at a temperature higher than the heating temperature of the first pre-baking step and in a range of 530 ° C or lower. Manufacturing method of electromechanical conversion film. The main component of the composite oxide formed from the sol-gel solution is described by the chemical formula ABO ₃ , the composition element A is selected from Pb, Ba, Sr, and the composition element B is Ti, Zr, Sn, Ni, Zn, Mg The method for producing an electromechanical conversion film according to claim 1, wherein Nb is selected from Nb and Nb.   6. An electromechanical conversion element, wherein an electromechanical conversion film obtained by the manufacturing method according to claim 1 is sandwiched between electrodes.   A liquid discharge head comprising the electromechanical transducer according to claim 6.   An ink jet recording apparatus comprising the liquid discharge head according to claim 7.