JP6194686B2 - Method for manufacturing piezoelectric film, method for manufacturing electro-mechanical conversion element - Google Patents

Description

  The present invention relates to a method for manufacturing a piezoelectric film, a method for manufacturing an electromechanical conversion element, a liquid discharge head, and an ink jet printer.

  In recent years, an electro-mechanical conversion element including a piezoelectric film has been used in various fields such as an image recording apparatus such as a printer or a facsimile, or a liquid discharge head such as an ink jet printer used as an image forming apparatus (for example, Patent Document 1).

  The electro-mechanical conversion element can be composed of, for example, a first electrode (lower electrode), a piezoelectric film (electro-mechanical conversion layer), and a second electrode (upper electrode) disposed on the substrate.

  At this time, various film forming methods such as a hydrothermal synthesis method, a vapor deposition method, an AD method, a spin coating method, and an ink jet method have been known as a piezoelectric film forming method.

  In particular, it is a method of discharging and applying a sol-gel droplet, which is a precursor of the piezoelectric film, onto the first electrode (lower electrode) with high resolution by an ink jet method in accordance with a desired pattern shape of the piezoelectric film. In recent years, a method for manufacturing a piezoelectric film by an ink jet method has attracted attention.

  This is because the piezoelectric film can be formed in accordance with the desired piezoelectric film pattern according to the method of manufacturing the piezoelectric film by the ink jet method, and it is not necessary to perform dry etching or the like after heating after coating, There is no increase in costs due to increase or material disposal. Moreover, since it is not necessary to perform patterning by dry etching or the like as described above, even when the piezoelectric film contains a lead component, the environmental impact of lead waste can be greatly reduced.

  However, the process-specific problems described below still exist in the method of manufacturing the piezoelectric film by the ink jet method.

  The amount of the sol-gel liquid used when forming the piezoelectric film on the first electrode is much smaller than that of the spin coating method. For this reason, in the step of drying the sol-gel film (sol-gel liquid), the vapor concentration of the solvent evaporating from the trace amount liquid becomes low at the pattern end of the sol-gel film, and the drying of the sol-gel film becomes faster. Then, a difference in drying speed occurs in the sol-gel film, so that a so-called coffee stain phenomenon occurs in which the film thickness along the ridge line of the sol-gel film increases extremely, and the edge and center of the pattern of the sol-gel film are generated. There was a problem that remarkable film thickness unevenness occurred in the portion.

  The coffee stain phenomenon will be described with reference to FIGS.

  FIG. 1 is a model diagram showing a mechanism of a coffee stain phenomenon generated from a sol-gel droplet landed on a first electrode, and FIG. 2 is a diagram illustrating a process for drying a sol-gel film on the first electrode. It is a model figure showing the flow in the landed droplet.

  The sol-gel droplet landed on the first electrode initially evaporates while maintaining the same shape as shown in FIG. The circle in the figure schematically shows the solute in the sol-gel droplet. However, as the evaporation proceeds, as shown in FIG. 1B, a solute concentration deviation occurs in the sol-gel droplet, and the vapor concentration of the solvent becomes lower at the pattern edge. At the same time, the edge region of the sol-gel droplet is thickened (gelled) (FIG. 1C).

  As indicated by the arrows in FIGS. 1D and 2, the solute is supplied to the end portion by the internal flow in which only the height is lowered while the edge of the sol-gel droplet is stopped. The film thickness along the side increases. The internal flow of the sol-gel droplet shown in FIG. 1D and FIG. 2 is caused by a temperature gradient in the vertical direction of the sol-gel droplet and convection due to a density difference.

  In the finally obtained piezoelectric film, due to the coffee stain phenomenon, as shown in FIG. 1 (E), remarkable film thickness unevenness occurs between the film thickness at the end and the center. FIG. 1E is an enlarged view of the cross section of the central portion from the end of the obtained piezoelectric film.

  In addition, during the process of drying the sol-gel film, heating means such as a hot plate and a lamp annealing device are used as in the spin coating method. At this time, the metal film surface existing around the pattern of the piezoelectric film is used. Drying is further promoted by the heat storage and heat transfer effect. For this reason, there was a problem that the above-mentioned film thickness unevenness became remarkable. When an electro-mechanical conversion element is formed using such a piezoelectric film, a problem occurs in the electrical characteristics of the electro-mechanical conversion element.

  In response to the above problems, a method has been proposed in which a high boiling point solvent is added to a sol-gel solution used in an ink jet method to increase the vapor concentration at the end of the sol-gel film and to suppress the rate of natural drying. Yes. However, even this method cannot sufficiently suppress the occurrence of the coffee stain phenomenon.

  In view of the above-described problems of the prior art, an object of the present invention is to provide a method for manufacturing a piezoelectric film that suppresses unevenness in film thickness and is excellent in productivity.

In order to solve the above problems, the present invention comprises a step of partially applying a sol-gel liquid to a first electrode surface provided on a substrate by an ink jet method to form a patterned sol-gel film;
Drying the sol-gel film by heat-treating the sol-gel film,
The step of drying the sol-gel film includes a first temperature raising step of raising the heating temperature of the sol-gel film from room temperature to a predetermined change point temperature _Tc at a first temperature raising rate;
A second temperature raising step of changing the temperature rising rate to the second temperature rising rate after reaching the change point temperature _Tc and raising the heating temperature of the sol-gel film to the drying temperature of the sol-gel film; Have
The change point temperature T _c satisfies the relationship of T _bp −23 ≦ T _c ≦ T _bp +23 with the boiling point T _bp of the main solvent of the sol-gel solution,
The heating rate per minute of the first heating rate is 45% or less of the boiling point of the main solvent of the sol-gel liquid,
The method of manufacturing a piezoelectric film is characterized in that the first temperature rise rate is slower than the second temperature rise rate.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the manufacturing method of the piezoelectric material film which suppressed film thickness nonuniformity and was excellent in productivity.

Illustration of coffee stain phenomenon Model diagram showing the flow in a droplet landed on the first electrode in a conventional drying process Explanatory drawing of the surface modification method of the 1st electrode surface which concerns on the 1st Embodiment of this invention. Explanatory drawing of the industrial inkjet drawing apparatus which can be used for application | coating of the sol-gel liquid which concerns on the 1st Embodiment of this invention. Explanatory drawing of the example of a manufacture flow of a piezoelectric material film concerning a 1st embodiment of the present invention. Explanatory drawing of the manufacturing process of the piezoelectric film which concerns on the 1st Embodiment of this invention Explanatory drawing of the structure of the liquid discharge head which concerns on the 3rd Embodiment of this invention. Explanatory drawing of the structure of the liquid discharge head which concerns on the 3rd Embodiment of this invention. Explanatory perspective view of the configuration of an ink jet printer according to a fourth embodiment of the present invention. Side surface explanatory drawing of the mechanism part of the inkjet printer which concerns on the 4th Embodiment of this invention. Explanatory drawing of the piezoelectric film pattern formed by the inkjet system in Example 1 of this invention PE hysteresis curve of electromechanical transducer according to embodiment 1 of the present invention

Hereinafter, modes for carrying out the invention will be described with reference to the drawings, but the present invention is not limited to these examples.
[First Embodiment]
Hereinafter, an embodiment of a method for producing a piezoelectric film of the present invention will be described.

  The method of manufacturing a piezoelectric film according to the present embodiment includes a step of partially applying a sol-gel liquid to the surface of a first electrode provided on a substrate by an inkjet method to form a patterned sol-gel film. And a step of drying the sol-gel film by heat-treating the sol-gel film.

And the process of drying a sol-gel film can have the following 1st temperature rising processes and a 2nd temperature rising process. The first temperature raising step can be a step of raising the heating temperature of the sol-gel film from room temperature to a predetermined change point temperature _Tc at a first temperature raising rate. In the second temperature raising step, after reaching the change point temperature _Tc , the temperature raising rate is changed to the second temperature raising rate, and the heating temperature of the sol-gel film is increased to the drying temperature of the sol-gel film. It can be set as the process to heat.

At this time, the change point temperature T _c preferably satisfies the relationship of T _bp −23 ≦ T _c ≦ T _bp +23 with the boiling point T _bp of the main solvent of the sol-gel solution. The temperature rising rate per minute of the first temperature rising rate is preferably 45% or less of the boiling point of the main solvent of the sol-gel liquid. Furthermore, the first temperature rise rate is preferably slower than the second temperature rise rate.

  Each step will be described below.

  First, a process of forming a patterned sol-gel film by partially applying a sol-gel liquid to the surface of the first electrode provided on the substrate by an ink jet method will be described.

  In this step, a sol-gel liquid, which is a precursor of the piezoelectric film, is partially applied to the surface of the first electrode provided on the substrate according to the pattern of the target piezoelectric film by an inkjet method, This is a step of forming a sol-gel film.

  A method of partially applying the sol-gel liquid by the ink jet method is not particularly limited, and the sol-gel liquid can be directly applied on the first electrode by the ink jet method without performing a pretreatment process. However, in order to prevent the formation of a fine pattern and to prevent the sol-gel solution from adhering to a portion other than the target, it is preferable to perform a pretreatment step before applying the sol-gel solution.

  Here, a configuration example of the pretreatment process will be described.

  As the pretreatment step, for example, it is preferable to include a step of partially modifying the surface of the first electrode provided on the substrate (hereinafter also referred to as “surface modification step”). As the surface modification step, it is preferable to control the wettability of the first electrode surface, for example, by partially modifying the surface of the first electrode. By performing the surface modification step, a surface energy contrast can be provided on the surface of the first electrode. When the sol-gel liquid is applied, the sol-gel liquid is wet and spreads only in the hydrophilic region. Therefore, it is possible to easily paint differently. That is, by performing the surface modification step, when the sol-gel solution is applied to the surface of the first electrode, it can be easily applied only to a desired place.

  For this reason, for example, it is preferable to modify the surface of the first electrode surface in advance in accordance with the shape of the sol-gel film (piezoelectric film) to be formed. In this case, as the portion for surface modification, either the portion that forms the sol-gel film or the portion that does not form the sol-gel film may be surface modified, depending on the surface characteristics after the surface modification. You can choose.

  As a method for controlling the wettability of the first electrode surface, for example, a hydrophobic or hydrophilic liquid or a film may be applied to the first electrode surface, or a method of forming a film.

  Specifically, for example, a method utilizing the phenomenon of self-arrangement on a specific metal of alkanethiol shown below can be mentioned.

  A specific operation example will be described with reference to FIG.

  Since alkanethiol has the property of forming a SAM film on the surface of a platinum group metal, a material in which a first electrode 32 made of platinum, a platinum group metal, or an alloy thereof is formed on a substrate 31 is prepared. (FIG. 3A).

  Then, when SAM treatment is performed by dipping the substrate on which the first electrode is formed into an alkanethiol solution, a SAM film (self-assembled monomolecular film) 33 is formed on the surface of the first electrode 32 (FIG. 3). (B)). Since an alkyl group is disposed in the SAM film 33, the entire surface of the first electrode surface on the substrate becomes hydrophobic.

  Next, a photolithography process for forming a photoresist 34 having a predetermined opening is performed by a photolithography method using the photoresist 34 and the photomask 35. After the photolithography process, the SAM film is patterned in accordance with the shape of the desired piezoelectric film by an etching process (FIG. 3C). At this time, for example, the SAM film can be etched by irradiation with oxygen plasma or UV light.

  In the region where the photoresist 34 remains in the photolithography process, the patterned SAM film remains even after the resist is removed, and the hydrophobicity is maintained in this region. On the other hand, the resist-removed region in the photolithography process becomes hydrophilic because the SAM film on the surface of the first electrode is removed by the etching process (FIG. 3D).

  By performing the surface modification step as described above as the pretreatment step, the surface of the first electrode can be partially modified, so that the sol-gel solution can be easily and accurately obtained. It becomes possible to apply to the surface portion of the first electrode.

  In addition, although the example using a platinum group electrode was demonstrated as an example of a surface modification process, it is not limited to the form which concerns, For example, it can also be set as the following modifications.

  In this modification, lanthanum nickelate (LNO) is used as the first electrode formed on the substrate. In this case, a platinum film is formed in advance under the LNO film. By patterning the LNO film in advance into a target piezoelectric film shape by a photolithography process and an etching process, both the region where the LNO film is removed and the platinum film is exposed and the region where the LNO film remains are formed. When this substrate is SAM-treated (the substrate is dipped into the alkanethiol solution), the SAM film is formed only on the platinum film and becomes water repellent, while the SAM film is not formed on the LNO and becomes hydrophilic. Therefore, the sol-gel liquid can be separately applied by the ink jet method.

  Next, a step of forming a patterned sol-gel film by partially applying a sol-gel liquid to the surface of the first electrode provided on the substrate by an inkjet method (hereinafter referred to as “sol-gel film forming step”). Is also described in detail.

  For the application of the sol-gel liquid by the ink jet method, for example, a general industrial ink jet drawing apparatus 40 as shown in FIG. 4 can be used.

  The industrial inkjet drawing apparatus 40 shown in FIG. 4 is provided with a stage 43 for fixing a substrate 42 as an object to which a sol-gel solution is applied on a gantry 41, and the stage 43 holds the substrate in the Y direction. Y-axis driving means 44 that can be moved to the right is provided.

  The sol-gel solution is applied to the substrate 42 by the ink jet head 45 provided to face the substrate 42. The inkjet head 45 is connected to a sol-gel liquid supply pipe 46 and supplies and applies the sol-gel liquid to the substrate 42 in response to a signal from a control unit (not shown). The inkjet head 45 is fixed to a head base 47, and the head base 47 is connected to an X-axis drive means 49 provided on an X-axis support member 48, and can be moved in the X direction. Yes. For this reason, the inkjet head 45 can be moved to a desired position on the substrate 42 together with the Y-axis driving means 44 provided on the gantry 41 side.

  Based on the pattern image of the piezoelectric film previously input to the control unit of the ink jet drawing apparatus, the industrial ink jet drawing apparatus 40 causes the sol-gel droplet to land only on the piezoelectric film pattern forming portion from the ink jet head 45. A pattern can be applied.

  The sol-gel solution used in this process is preferably adjusted in viscosity and surface tension in advance so that it can be applied by the inkjet head 45. The film thickness obtained by one film formation is preferably about 50 to 100 nm, and the sol-gel solution concentration is preferably optimized from the relationship between the film formation area and the amount of sol-gel liquid applied.

  The sol-gel liquid to be used is not particularly limited, and any material that exhibits piezoelectricity after film formation can be used.

  For example, various materials such as PZT when deposited, lead lanthanum added lead zirconate titanate (PLZT), lead magnesium niobate (PMN), lead nickel niobate (PNN), barium titanate (BT), etc. A raw material solution to be a piezoelectric ceramic material can be used.

In addition, PZT here is a solid solution of lead zirconate (PbZrO ₃ ) and lead titanate (PbTiO ₃ ), and the characteristics differ depending on the ratio, but the ratio is not limited and is required. It can be selected according to the piezoelectric performance or the like. Among them, the ratio (molar ratio) of PbZrO ₃ and PbTiO ₃ is 53:47, and it is expressed by the chemical formula PZT (PZT (53/47)) represented by Pb (Zr _0.53 , Ti _0.47 ) O _3. Can be preferably used because it exhibits particularly excellent piezoelectric properties.

  Next, a step of drying the sol-gel film (hereinafter also referred to as “drying step”) will be described.

  In the present embodiment, the step of drying the sol-gel film can include the following first temperature raising step and second temperature raising step. The first temperature raising step can be a step of raising the heating temperature of the sol-gel film from room temperature to a predetermined change point temperature at a first temperature raising rate. In the second temperature raising step, after reaching the change point temperature, the temperature raising rate is changed to the second temperature raising rate, and the heating temperature of the sol-gel film is raised to the drying temperature of the sol-gel film. It can be a process. That is, in the drying step, the drying can be performed step by step at two types of drying temperatures having different levels of the temperature rising rate.

  As described in the above prior art, when a sol-gel liquid is applied by an ink jet method, a so-called coffee stain phenomenon may occur in the drying process because the amount of sol-gel liquid applied is very small. . In this case, extreme film thickness unevenness occurs between the end and the center of the piezoelectric film pattern. For example, when an electro-mechanical conversion element is used, there is a problem in that the electric characteristics are defective. The coffee stain phenomenon is considered to be caused by a deviation in the solute concentration in the sol-gel film during the drying process, and the vapor concentration of the solvent at the end of the pattern is lowered.

  Therefore, the inventors of the present invention have examined that the heating temperature of the sol-gel film is increased by the first temperature rising rate and the second temperature rising rate having different temperature increasing rates, and is dried stepwise. Thus, it was found that the vapor concentration distribution of the solvent can be reduced in the sol-gel film formation region. For this reason, a good firing state can be obtained during heat treatment, variation in film thickness due to uneven drying can be suppressed, the occurrence of coffee stain phenomenon can be suppressed, and the time required for the drying process can be shortened to improve productivity. I found out.

  And in a drying process, it is preferable that the change point temperature changed from a 1st temperature rising rate to a 2nd temperature rising rate is the boiling point vicinity of the main solvent which comprises a sol-gel liquid. Moreover, it is preferable that the heating rate per minute of the first heating rate is 45% or less of the boiling point of the main solvent of the sol-gel liquid, and the first heating rate is the second heating rate. It is preferably slower than the rate.

  First, the change point temperature will be described.

  When the change point temperature is significantly lower than the vicinity of the boiling point of the main solvent constituting the sol-gel liquid, the temperature increase rate is higher than the first temperature increase rate in a state where the evaporation of the solvent component in the sol-gel liquid does not proceed. It will switch to the quick 2nd temperature increase rate. In this case, after changing to the second temperature rising rate, the temperature rising rate becomes faster until reaching the drying temperature of the sol-gel film, so that the solute concentration deviation becomes large in the patterned sol-gel film, Since the vapor density of the solvent is lowered, a coffee stain phenomenon may occur.

  On the other hand, when the temperature at the change point is significantly higher than the vicinity of the boiling point of the main solvent constituting the sol-gel liquid, the first temperature rise is performed at a point in time when most of the solvent components in the sol-gel liquid have already evaporated. It switches to the 2nd temperature rising rate whose temperature rising rate is faster than the rate. That is, in spite of the environment in which the coffee stain phenomenon does not occur, the heating is advanced at the first temperature rising rate that is slower than the second temperature rising rate even after the boiling point of the main solvent constituting the sol-gel liquid is exceeded. It will be. For this reason, the time which a drying process takes becomes long, and productivity may fall.

For this reason, it is preferable that the changing point temperature is around the boiling point of the main solvent constituting the sol-gel liquid. In particular, the change point temperature T _c preferably satisfies the relationship T _bp −23 ≦ T _c ≦ T _bp +23 with the boiling point T _bp of the main solvent of the sol-gel liquid, for example, T _bp −20 ≦ T It is more preferable to satisfy the relationship of _c ≦ T _bp +20. It is more preferable that the relationship of T _bp −10 ≦ T _c ≦ T _bp +10 is satisfied.

  Next, the first temperature increase rate will be described.

  As described above, the first temperature rising rate is preferably 45% or less of the boiling point of the main solvent of the sol-gel liquid at a temperature rising rate (temperature rising rate) per minute of the first temperature rising rate. . This is because when the temperature rising rate per minute of the first temperature rising rate is faster than 45% of the boiling point of the main solvent constituting the sol-gel liquid, a trace amount liquid is formed at the end of the sol-gel liquid film pattern. In some cases, the vapor concentration of the solvent evaporating from the liquid becomes lower and drying becomes faster. For this reason, the coffee stain phenomenon may occur.

  In particular, the first temperature rising rate is more preferably 25% or less of the boiling point of the main solvent of the sol-gel liquid at a temperature rising rate per minute of the first temperature rising rate. By setting the temperature increase rate per minute of the first temperature increase rate to 25% or less of the boiling point of the main solvent of the sol-gel liquid, the occurrence of the coffee stain phenomenon can be more reliably prevented.

  In addition, the main solvent described here means a solvent having the largest content when the volume is taken as a reference among the solvents contained in the sol-gel solution.

  Further, the lower limit value of the first temperature rise rate is not particularly limited, but for example, the temperature rise rate per minute of the first temperature rise rate is preferably 8% or more of the boiling point of the main solvent. 20% or more is more preferable. By selecting the first temperature increase rate from the above range, it is possible to suppress the occurrence of coffee stain reduction and further improve productivity. In addition, the film thickness in the central portion of the pattern can be more reliably set to be equal to or less than the film thickness at the end portion.

  Next, the relationship between the first temperature rise rate and the second temperature rise rate will be described.

  As described above, since the first temperature increase rate when the heating temperature is raised from room temperature to the change point temperature is within the predetermined range, the occurrence of the coffee stain phenomenon can be suppressed. When the heating temperature reaches the change point temperature, most of the main solvent components constituting the sol-gel liquid are evaporated. Therefore, at a temperature higher than the change point temperature, the rate of temperature increase becomes faster. However, the coffee stain phenomenon is less likely to occur. Rather, when the second temperature increase rate used from the change point temperature to the drying temperature is slower than the first temperature increase rate used from the room temperature to the change temperature, the main solvent component of the sol-gel liquid has evaporated. Thereafter, the time required to reach the drying temperature is extended. For this reason, there exists a problem that a tact time falls. For this reason, as described above, the first temperature increase rate is preferably slower than the second temperature increase rate.

  When the first temperature rise rate and the second temperature rise rate are the same, that is, when the temperature rise rate is monotonously dried at one type of temperature rise rate, this is already the same as described above. Even after most of the solvent components in the gel solution are evaporated, the gel solution is dried at the same temperature rise rate. For this reason, since the required time of a drying process is extended and productivity falls, it is unpreferable.

  For the above reasons, a proper firing state can be efficiently obtained during the heat treatment by appropriately selecting the first temperature rising rate, the second temperature rising rate, and the change point temperature. For this reason, the variation in the film thickness due to nonuniform drying is suppressed, and the occurrence of the coffee stain phenomenon can be suppressed. In addition, the drying process time can be shortened and productivity can be improved.

  In addition, especially about the holding time after reaching the change point temperature from the first heating rate to the second heating rate and the holding time after reaching the final drying temperature used in the drying step It is not limited. For example, after reaching the change point temperature or the drying temperature, it can be maintained for an arbitrary time. However, when the solvent can be sufficiently removed only by the temperature rising process, the temperature change rate change point temperature and the final drying can be performed. It is not necessary to maintain the temperature after reaching the temperature.

  Also, the drying temperature is not particularly limited. The temperature may be any temperature that can sufficiently remove the solvent contained in the sol-gel solution. For example, the boiling point of the solvent having the highest boiling point among the solvents contained in the sol-gel solution can be set as the drying temperature.

  Moreover, the process of thermally decomposing a sol-gel film and / or the process of crystallizing a sol-gel film can be performed after the process (drying process) of drying a sol-gel film.

  The step of thermally decomposing the sol-gel film (hereinafter also referred to as “thermal decomposition step”) is to remove organic substances in the sol-gel film from which the solvent component has been removed, and to remove the piezoelectric film (for example, PZT film). This is a step of forming a pattern. The step of crystallizing the sol-gel film (hereinafter also referred to as “crystallization step”) is a step of sintering and crystallizing the thermally decomposed piezoelectric film at a higher temperature.

  By performing the process of thermally decomposing the sol-gel film and / or the process of crystallizing the sol-gel film, the sol-gel film can be entirely changed to a piezoelectric body, and exhibits sufficient performance as a piezoelectric body. It becomes possible to make it. Moreover, it is preferable to implement the said process in both processes.

  About a thermal decomposition process and a crystallization process, it can also carry out continuously from the temperature (temperature which reached | attained), ie, the drying temperature, which heated up at the drying process. In addition, after the drying step, after cooling from the drying temperature, the temperature can be raised to the respective set temperatures.

  About a thermal decomposition process and a crystallization process, it does not specify about a temperature increase rate and final attainment temperature, It can select with the component etc. which are contained in a sol-gel liquid (film | membrane).

  As described above, the piezoelectric film can be formed by the steps described above. However, there is a case where the target film thickness cannot be obtained with the piezoelectric film manufactured by applying the droplet once by the ink jet method. In this case, a piezoelectric film having a desired film thickness can be obtained by repeatedly performing the above-described method for manufacturing a piezoelectric film.

  When the above-described method for manufacturing a piezoelectric film is repeatedly performed, the repeated steps and combinations can be arbitrarily selected.

  FIG. 5 shows an example of an operation flow in the case of repeatedly manufacturing the piezoelectric film. The arrows (a), (b), and (c) in FIG. 5 mean the repetition of the process, and can be repeated arbitrarily and at any timing as described below.

  In the operation flow shown in FIG. 5, the step of preparing the substrate provided with the first electrode (S50) is set as the starting point, and the point where the film forming step of the piezoelectric film is completed (S55) is described as the end point. ing. And it has a sol-gel film formation process (S51), a drying process (S52), a thermal decomposition process (S53), and a crystallization process (S54).

  First, as a first example, repetition may be performed at any timing after any of the drying step (S52), the thermal decomposition step (S53), and the crystallization step (S54).

  For example, first, only a sol-gel film forming step (S51) and a drying step (S52) are repeated a predetermined number of times to laminate a plurality of sol-gel films (arrows in FIG. 5A). And a thermal decomposition process (S53) can be performed at arbitrary timing, and also a crystallization process (S54) can be performed. In some cases, after the crystallization step (S54), the same process can be repeated. That is, the process returns to the sol-gel film forming step (S51) (arrow in FIG. 5C), and after repeating the sol-gel film forming step (S51) and the drying step (S52) a predetermined number of times, thermal decomposition is further performed. A process (S53) and a crystallization process (S54) can also be performed.

  As a modification, the sol-gel film forming step (S51), the drying step (S52), and the thermal decomposition step (S53) are repeated a predetermined number of times to stack the sol-gel film ((b) in FIG. 5). Arrow). And a crystallization process (S54) can be performed at arbitrary timings. In some cases, the process further returns to the sol-gel film forming step (S51) (arrow in FIG. 5C), the sol-gel film forming step (S51), the drying step (S52), and the thermal decomposition step (S53). ) May be repeated, and a crystallization step (S54) may also be performed.

  As a second example, a sol-gel film forming step (S51), a drying step (S52), a thermal decomposition step (S53), and a crystallization step (S54) are repeated in this order to form and stack layers (FIG. 5). Middle (c) arrow) method.

  In the sol-gel film forming step (S51), the above-described pretreatment step can be repeatedly performed together with the sol-gel film forming step (S51).

  Here, a configuration example of the operation procedure of the pretreatment step when repeatedly forming a sol-gel film will be described below by taking the same alkanethiol as described above as an example.

  As described above, the second and subsequent pretreatment steps can be performed in the same manner as the first time. However, when a PZT film, for example, is formed as the piezoelectric film, the SAM film is formed on the patterned PZT piezoelectric film, which is an oxide thin film, even if SAM treatment is performed by dipping each substrate in an alkanethiol solution. Not. That is, the hydrophilicity is maintained on the PZT piezoelectric film even after the SAM treatment. For this reason, since the SAM film is formed only on the first electrode composed of, for example, platinum, a platinum group metal, or an alloy thereof exposed outside the PZT piezoelectric film pattern and becomes hydrophobic, the SAM film patterning step The process can be simplified. Depending on the material of the piezoelectric film and the like, the SAM film patterning step can be performed in the same manner as the first time.

  This will be specifically described with reference to FIG.

  FIG. 6D illustrates the same state as that in FIG. 3D, and a SAM film having an opening is formed over the first electrode 32 provided over the substrate 31. For this reason, the hydrophilic part 50 and the hydrophobic part 51 are formed.

  Next, in FIG. 6E, a step of forming a patterned sol-gel film by partially applying a sol-gel liquid by an ink jet method is performed. In the drawing, a sol-gel solution is applied from the inkjet head 52, and a sol-gel film 53 is formed on the hydrophilic portion 50 in FIG.

  In FIG. 6 (F), the formed sol-gel film is subjected to a drying step and subsequently a thermal decomposition step to form a piezoelectric film 54. At this time, the SAM film is also removed by heating. Note that only the drying step can be performed without performing the pyrolysis step as described above.

  6 (D ′) to FIG. 6 (F ′) show a state where the repetition is performed.

  FIG. 6D ′ shows a state where the substrate having the piezoelectric film 54 obtained in FIG. 6F is dipped in the alkanethiol liquid together with the substrate. As described above, since the SAM film is not formed on the piezoelectric film 54, the SAM film having the opening can be formed without going through the steps of FIGS. 3B and 3C.

  Thereafter, in FIGS. 6E and 6F, a sol-gel film 53 ′ is formed in the same manner as in the processes of FIGS. A piezoelectric film 54 'can be formed. Furthermore, similarly, the piezoelectric film can be laminated by repeating FIG. 6D ′ to FIG. 6F ′ a predetermined number of times.

  A piezoelectric film having a desired thickness can be formed by repeatedly forming and laminating the piezoelectric film by the method described above. Specifically, for example, the piezoelectric film can be formed to a thickness of 5 μm.

  Even when the piezoelectric film is repeatedly formed, it is preferable to perform the drying step in the same manner as the step of drying the sol-gel film. That is, the drying step includes a first temperature raising step and a second temperature raising step, and the temperature is raised from room temperature to the drying temperature by the first temperature raising step and the second temperature raising step. -It is preferred to dry the gel membrane.

  This is because, as the desired piezoelectric film thickness increases, the number of times the drying process is repeated increases, so that the time required for the drying process can be shortened at any time by performing the procedure according to the above-described drying process. For this reason, it is possible to bring about a great effect in shortening the tact time in all the steps of forming the piezoelectric film and to further improve the productivity.

Further, in each step of drying the sol-gel film, since the vapor concentration distribution of the solvent is controlled in the sol-gel film formation region, the occurrence of the coffee stain phenomenon is suppressed, and the film thickness is caused by non-uniform drying. The variation of is also suppressed. For this reason, it becomes possible to suppress the film thickness nonuniformity of a piezoelectric film. As a result, the piezoelectric film formed by repeating the above process also has a desired shape, and a high-quality device with good electrical characteristics can be provided.
[Second Embodiment]
Hereinafter, an embodiment of a method for producing an electromechanical conversion element of the present invention will be described.

  The manufacturing method of the electromechanical conversion element of this embodiment may include a step of disposing the second electrode on the piezoelectric film obtained by the manufacturing method of the piezoelectric film described in the first embodiment. it can.

  The step of disposing the second electrode on the piezoelectric film is not particularly limited, and the second electrode can be formed on the piezoelectric film by a sputtering method or the like.

  Further, the material of the second electrode is not particularly limited, and the second electrode can be made of the same material as that of the first electrode, or can be made of a different material. Specifically, for example, as the second electrode, a platinum group metal such as platinum or an alloy thereof, or a conductive oxide or the like can be used, for example.

The electro-mechanical conversion element obtained by the method of manufacturing an electro-mechanical conversion element of the present embodiment has an electro-mechanical conversion element with excellent electric characteristics because the film thickness unevenness of the piezoelectric film constituting it is suppressed. [Third Embodiment]
Hereinafter, an embodiment of the liquid discharge head of the present invention will be described.

  The liquid discharge head of this embodiment can be a liquid discharge head including the electro-mechanical conversion element obtained by the method for manufacturing the electro-mechanical conversion element described in the second embodiment. . The structure will be described with reference to FIGS. 7 is a schematic diagram showing an example of the configuration of one nozzle, and FIG. 8 is a liquid discharge head formed by arranging a plurality of the one-nozzle liquid discharge heads 60 shown in FIG. The outline of 67 is shown.

  7 and 8, a nozzle that discharges droplets, a pressurizing chamber that communicates with the nozzle, a diaphragm that forms part of the wall of the pressurizing chamber, and a second plate formed on the diaphragm 2 shows a liquid ejection head having the electro-mechanical conversion element described in the embodiment.

  The configuration of the liquid discharge head 60 will be specifically described with reference to FIG.

  The liquid discharge head 60 includes a pressurizing chamber (pressure chamber) 61 that is an ink chamber for storing a liquid such as ink (hereinafter referred to as “ink”). The pressurizing chamber 61 is, for example, an electro-mechanical converter. The substrate 64 on which the element 66 is formed can be formed by etching. A part of the wall of the pressurizing chamber is constituted by the diaphragm 65 as an ejection driving means for boosting the liquid in the pressurizing chamber 61, and the electromechanical conversion element 66 is disposed on the diaphragm 65. As the electro-mechanical conversion element 66, it is preferable to use the electro-mechanical conversion element described in the second embodiment as described above. Furthermore, it has a nozzle plate 63 as an ink nozzle including a nozzle 62 as a nozzle hole as an ink discharge port for discharging the ink in the pressurizing chamber 61 into droplets.

  As a mechanism by which the liquid discharge head 60 discharges droplets, a piezoelectric film (electro-mechanical conversion film) 662 is supplied by supplying power to the first electrode (lower electrode) 661 and the second electrode (upper electrode) 663. As a result, a stress is generated, which causes the diaphragm (diaphragm) 65 to vibrate. Along with this vibration, the ink in the pressurizing chamber 61 is ejected from the nozzle 62 in the form of droplets. Note that illustration and description of liquid supply means, which is ink supply means for supplying ink into the pressurizing chamber 61, ink flow paths, and fluid resistance are omitted.

  FIG. 8 shows the liquid discharge head 67 formed by arranging a plurality of the liquid discharge heads 60 described with reference to FIG. 7 as described above.

  In the liquid discharge head according to the present embodiment, since the electro-mechanical conversion element that suppresses the film thickness unevenness of the piezoelectric film and has good electrical characteristics described in the second embodiment is used, ink droplet discharge failure And stable ink droplet ejection characteristics can be obtained.

In addition, the electro-mechanical conversion element has a simple structure, and has performance equivalent to that of bulk ceramics. Further, due to its configuration, etching removal from the back surface for forming a pressure chamber, nozzle having nozzle holes By joining the plates, a liquid discharge head can be easily formed.
[Fourth Embodiment]
Hereinafter, an embodiment of the ink jet printer of the present invention will be described.

  The ink jet printer of this embodiment can be configured to include the liquid ejection head described in the third embodiment.

  A specific configuration example of the ink jet printer will be described with reference to FIGS. 9 is a perspective explanatory view of the ink jet printer, and FIG. 10 is a side explanatory view of a mechanism portion of the ink jet printer.

  An ink jet printer (recording apparatus main body) 70 according to the present embodiment is an ink jet head that includes a carriage 71 that is movable in the main scanning direction and a liquid ejection head described in the third embodiment that is mounted on the carriage 71. A head 80 is provided. A printing mechanism 73 including an ink cartridge 72 that supplies ink to the recording head 80 is accommodated. Further, a paper feed cassette (or a paper feed tray) 75 on which a large number of sheets 74 can be stacked from the front side can be detachably attached to the lower part of the inkjet printer 70.

  Further, the manual feed tray 76 for manually feeding the paper 74 can be opened, the paper 74 fed from the paper feed cassette 75 or the manual feed tray 76 is taken in, and a required image is displayed by the printing mechanism unit 73. After recording, the paper is discharged onto a paper discharge tray 77 mounted on the rear side.

  The printing mechanism 73 holds a carriage 71 slidably in the main scanning direction by a main guide rod 78 and a sub guide rod 79 which are guide members horizontally mounted on left and right side plates (not shown). As described above, the recording head 80 provided with the liquid ejection head described in the third embodiment for ejecting ink droplets of each color on the carriage 71 has a plurality of ink ejection openings (nozzles) crossing the main scanning direction. Are arranged with the ink droplet ejection direction downward. For example, the carriage 71 may be provided with a recording head 80 that ejects ink droplets for each job of yellow (Y), cyan (C), magenta (M), and black (Bk).

  Also, each ink cartridge 72 for supplying ink of each color to the recording head 80 can be mounted on the carriage 71 in a replaceable manner. The ink cartridge 72 may have a configuration in which an air port communicating with the atmosphere is provided above, a supply port for supplying ink to the recording head 80 is provided below, and a porous body filled with ink inside. In this case, the ink supplied to the liquid ejection head (inkjet head) is maintained at a slight negative pressure by the capillary force of the porous body. Further, although the heads 80 of the respective colors are used here as the recording heads, a single head having nozzles for ejecting ink droplets of the respective colors may be used.

  The carriage 71 is slidably fitted to the main guide rod 78 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the sub guide rod 79 on the front side (upstream side in the paper conveyance direction). . In order to move and scan the carriage 71 in the main scanning direction, a timing belt 84 is stretched between a driving pulley 82 and a driven pulley 83 that are rotationally driven by a main scanning motor 81, and the timing belt 84 is fixed to the carriage 71. ing. Then, the carriage 71 is reciprocated by forward and reverse rotation of the main scanning motor 81.

  On the other hand, in order to convey the paper 74 set in the paper feed cassette 75 to the lower side of the recording head 80, first, a paper feed roller 85 and a friction pad 86 for separating and feeding the paper 74 from the paper feed cassette 75 are provided. Yes. Further, a guide member 87 that guides the paper 74, a transport roller 88 that reverses and transports the fed paper 74, a transport roller 89 that is pressed against the peripheral surface of the transport roller 88, and the paper 74 from the transport roller 88. And a tip roller 90 for defining the feed angle. The transport roller 88 is rotationally driven by a sub-scanning motor 91 through a gear train.

  A printing receiving member 92 is provided as a paper guide member for guiding the paper 74 fed from the transport roller 88 below the recording head 80 corresponding to the range of movement of the carriage 71 in the main scanning direction. On the downstream side of the printing receiving member 92 in the sheet conveyance direction, a conveyance roller 93 and a spur 94 that are rotationally driven to send out the sheet 74 in the sheet discharge direction are provided. Further, a discharge roller 95 and a spur 96 for sending the sheet 74 to the discharge tray 77, and guide members 97 and 98 for forming a discharge path are provided.

  At the time of recording, the recording head 80 is driven according to the image signal while moving the carriage 71 to eject ink onto the stopped paper 74 to record one line. Record the line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 74 has reached the recording area, the recording operation is terminated and the paper 74 is discharged.

  In FIG. 9, a recovery device 99 for recovering the ejection failure of the head 80 is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 71. The recovery device 99 includes a cap unit, a suction unit, and a cleaning unit. For example, the carriage 71 moves to the recovery device 99 side during printing standby, and capping the recording head 80 by the capping means, and keeping the ejection port portion in a wet state can 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 ejection failure occurs, the ejection port (nozzle) of the recording head 80 is sealed with a capping unit, and bubbles and the like are sucked out from the ejection port with the suction unit through the tube. Etc. can be removed by a cleaning means, and ejection failure can be recovered. Further, the sucked ink can be 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.

  The ink jet recording apparatus of this embodiment is equipped with the liquid discharge head (ink jet head) described in the third embodiment. As described above, the liquid discharge head uses an electro-mechanical conversion element in which the non-uniformity of the film thickness of the piezoelectric film of the electro-mechanical conversion element constituting the liquid discharge head is suppressed and the electric characteristics are good. Therefore, there is no ink droplet ejection failure due to electro-mechanical transducer vibration plate drive failure. For this reason, the ink jet recording apparatus of the present embodiment can obtain stable ink droplet ejection characteristics and can improve the image quality.

Specific examples will be described below, but the present invention is not limited to these examples.
[Examples 1 and 2]
In this example, a piezoelectric film and an electromechanical conversion element were formed by the following procedure, and the characteristics were evaluated.

  A manufacturing procedure will be described with reference to FIGS. 3, 6, and 11.

  First, as shown in FIG. 3A, a member was prepared in which a first electrode (lower electrode) 32 made of platinum was formed on the surface of a silicon substrate 31 by sputtering.

Next, as shown in FIG. 3B, a SAM film 33 was formed on the entire surface of the first electrode 32 (platinum) on the silicon substrate 31. The SAM film 33 was obtained by dipping the entire substrate in an alkanethiol solution and self-aligning it. Alkanethiol solution was used dodecanethiol _{CH 3 (CH 2) 11 -SH} .

  As shown in FIG. 3C, a portion of the SAM film where the piezoelectric film is to be formed is removed, and a photoresist 34 is formed using a photomask 35 by photolithography to protect the necessary portion of the SAM film. Patterned (photolithographic process). At this time, patterning was performed so that the pattern 110 shown in FIG. 11 was obtained.

  Then, in FIG. 11, the portion of the piezoelectric film pattern 111 is irradiated with oxygen plasma from the upper surface side of the silicon substrate to remove the SAM film of the portion forming the piezoelectric film pattern. It was made hydrophilic (etching process).

  As shown in FIG. 3D, the photoresist 34 was peeled off. The contact angle of the SAM film formed by the steps so far with respect to pure water is 110 degrees, indicating hydrophobicity, and the contact angle of the surface of the first electrode 32 (platinum) on the substrate from which the SAM film has been removed is 10 degrees or less. It showed hydrophilicity.

  As shown in FIG. 6D, in the region where the piezoelectric film pattern is formed, that is, the region 50 where the sol-gel liquid is applied, the SAM film is removed by the photolithography process and the etching process before the application. The surface was made hydrophilic. On the other hand, the region 51 where the sol-gel liquid is not applied is not patterned in the photolithography process, and is still in a state where a hydrophobic SAM film is held even after the photoresist 34 is removed.

  Next, in FIG. 6E, a sol-gel solution that is a PZT precursor is applied to the hydrophilic portion 50 of the first electrode 32 (platinum) formed on the silicon substrate formed in the above process by an ink jet method. The process of apply | coating is shown. In the inkjet method, the general industrial inkjet drawing apparatus 40 shown in FIG. 4 was used.

  The used sol-gel solution will be described. In this example, a sol-gel solution that becomes a PZT film was used. The sol-gel solution used lead acetate trihydrate, isopropoxide titanium and isopropoxide zirconium as starting materials. Crystallized lead acetate was dissolved in 2-methoxyethanol (boiling point: 124 ° C.), which is the main solvent, and then dehydrated. And sol-gel solution is prepared by dissolving isopropoxide titanium and isopropoxide zirconium in methoxyethanol, proceeding with alcohol exchange reaction and esterification reaction, and mixing with 2-methoxyethanol solution in which lead acetate is dissolved. Was synthesized. At this time, the above solutions are mixed so that the molar ratio of the metal species contained in the sol-gel solution is Pb: Zr: Ti = 115: 53: 47. In addition, in the molar ratio of the above metal species, the lead addition amount is 15 mol% excess with respect to the target stoichiometric composition. This is to prevent crystallinity deterioration due to so-called lead loss during heat treatment. Further, diethylene glycol monomethyl ether (boiling point: 194.1 ° C.) and 1-nonanol (boiling point: 213 ° C.) having a boiling point higher than that of methoxyethanol were added to the synthesized sol-gel solution. The PZT concentration in the sol-gel solution was adjusted to 0.2 mol / L so that the film thickness of the piezoelectric body obtained by one film formation was about 80 nm to 90 nm.

  As shown in FIG. 11, the piezoelectric film pattern 111 formed by the inkjet method is a long pattern having a width of 50 μm and a length of 1000 μm, and 1: 1 pitch in the width direction (the pattern width and the space width between the patterns are the same 50 μm). ). Note that the width direction means a direction represented by an arrow 112 in FIG.

  Then, as shown in FIG. 6E, for example, a sol-gel solution was applied to the surface of the first electrode 32 by an inkjet head 52 of an industrial inkjet drawing apparatus. At this time, because of the contrast of the contact angle on the surface of the first electrode 32, the sol-gel liquid spreads only to the hydrophilic portion 50 and forms a sol-gel film corresponding to the piezoelectric film pattern 111.

  And the 1st heating process, ie, the drying process, was performed about the obtained sol-gel film. The drying process was performed by first raising the temperature from room temperature to 124 ° C., which is the changing point temperature, as the first temperature raising process by heating the lower surface of the substrate with a hot plate. In this case, the change point temperature was set to the same temperature as the boiling point of 2-methoxyethanol which is the main solvent of the sol-gel solution. As shown in Table 1, the first heating rate used was 30 ° C./min in Example 1 and 56 ° C./min in Example 2. The heating rate (heating rate) per minute of the first heating rate is 24% in Example 1 and 24% in Example 2 with respect to the boiling point (124 ° C.) of 2-methoxyethanol which is the main solvent. 45%.

  After reaching the change point temperature of 124 ° C., hold for 1 minute, and then, as shown in Table 1, Example 1 is 60 ° C./min, and Example 2 is 90 ° C./min. Then, a second temperature raising step for raising the temperature to 300 ° C., which is the drying temperature of the sol-gel film, was performed.

  After drying the sol-gel film in the drying step, the second heating step, that is, the thermal decomposition step for performing the thermal decomposition treatment of the organic matter is performed at a temperature of 500 ° C., and the first layer as shown in FIG. The piezoelectric film 54 (PZT piezoelectric film pattern) was obtained. The film thickness of the obtained piezoelectric film 54 of the first layer is measured at the end / center of the pattern longitudinal direction, and the film thickness ratio is calculated from the film thickness measured at the end and center of the piezoelectric film 54 did. Table 1 shows the film thickness measurement results and the film thickness ratio calculation results as the first piezoelectric film.

  As shown in Table 1, the film thickness ratio (end / center) was 0.96 in Example 1 and 1.21 in Example 2, and a piezoelectric film having a substantially uniform film thickness was obtained. It was confirmed that

  Subsequently, after repeating isopropyl alcohol washing as a repeating process, a SAM film was formed by the same dipping treatment. In the second and subsequent SAM treatments, the SAM film is not formed on the piezoelectric film 54 that is an oxide film, so that the SAM film pattern as shown in FIG. 6D ′ is obtained without performing the photolithography process. It was. The contact angle at this time was 105 degrees on the SAM film, which is the hydrophobic portion 51 with respect to pure water, and 25 degrees on the piezoelectric film (PZT film) 54, which is the hydrophilic portion 50.

  Then, as shown in FIG. 6E ′, alignment is performed on the pattern of the piezoelectric film 54 formed for the first time in this state, and the sol-gel solution is again applied by the ink jet head 52 of the industrial ink jet drawing apparatus. Applied.

  As shown in FIG. 6 (F ′), similarly to the first time, a two-step drying process having a first temperature raising process and a second temperature raising process, and a thermal decomposition process were carried out and overcoated. A piezoelectric film (PZT piezoelectric film) 54 'was obtained. In the case of the drying process, two types of temperature rising rates and the temperature at which the first temperature rising rate and the second temperature rising rate are changed are as follows. And the same.

  Thereafter, the above-described steps are further repeated 6 times in total, including the above-mentioned 2 steps (the first layer and the 1-time repeat step), to form a total of 6 layers of piezoelectric films. (First time). Crystallization treatment (temperature 750 ° C.) was performed with an RTA (rapid heat treatment) apparatus on the six layers of the piezoelectric film obtained by repeating the second heating step from the series of sol-gel solution coating.

  For convenience of explanation in Comparative Example 1 described later, this point is referred to as “repeatedly applied 6 times (first time)”. At this time, no defects such as cracks occurred in the piezoelectric film in any of the examples.

  Subsequently, the piezoelectric film was repeatedly formed on the piezoelectric film in the same manner 6 times (second time). That is, the SAM film treatment → sol-gel solution application → drying process at two temperature rising rates (300 ° C.) → thermal decomposition process at 500 ° C. is repeated 6 times, and the 7th to 12th piezoelectric layers A body membrane was formed. Thereafter, in the same manner as in the first case, crystallization was further performed at 750 ° C. After the crystallization treatment, the obtained piezoelectric film was confirmed, but defects such as cracks did not occur. In this case as well, during the drying step, the two types of temperature rising rates and the temperature at which the first temperature rising rate and the second temperature rising rate are changed are described as follows. It was the same as that in the drying step after the gel solution application.

  Further, the piezoelectric film was repeatedly formed 6 times on the obtained piezoelectric film (third time). That is, the SAM film treatment → sol-gel liquid application → drying process at two temperature rising rates (300 ° C.) → thermal decomposition process at 500 ° C. is repeated 6 times, and the 13th to 18th piezoelectric layers A body membrane was formed. Thereafter, in the same manner as in the first and second times, crystallization was further performed at 750 ° C. For convenience of explanation in Comparative Example 1, this time point is expressed as “repeated 6 times (third time)”. Also in this case, in the drying step, the first layer sol-gel solution of each example is used for two types of temperature increase rates and the temperature at which the first temperature increase rate and the second temperature increase rate are changed. The same as in the drying step after coating.

  After completion of crystallization, the film thickness was measured at the end / center of the piezoelectric film pattern longitudinal direction, and the film thickness ratio was calculated from the film thickness measured at the end and center of the piezoelectric film. The measurement results of the film thickness and the calculation results of the film thickness ratio are shown in Table 1 as “repeated 6 times (third time) piezoelectric film”.

  As can be seen from the results shown in Table 1, the film thickness difference (edge portion-center portion) in the pattern longitudinal direction is −0.1 μm in Example 1 and +0.3 μm in Example 2, and the film thickness ratio is Example 1 was 0.94 and Example 2 was 1.23. That is, it was confirmed that a good piezoelectric film with almost no film thickness unevenness in the pattern was obtained in both Examples 1 and 2.

  Next, a second electrode (Pt) is formed on the formed piezoelectric film by sputtering and patterned to form an electro-mechanical conversion element, which has electrical characteristics and electro-mechanical conversion capability. (Piezoelectric constant) was evaluated. The evaluation results of electrical characteristics are shown in Table 1 as relative permittivity, dielectric loss, and breakdown voltage. According to Table 1, all of the piezoelectric films produced in Examples 1 and 2 exhibited excellent electrical characteristics in terms of relative dielectric constant, dielectric loss, and breakdown voltage, and characteristics sufficient to have a function as a piezoelectric film. Was obtained.

In addition, the piezoelectric films obtained in Examples 1 and 2 each have a remanent polarization of 19.5 μC / cm ² and a coercive electric field of 36.5 kV / cm, and have characteristics equivalent to those of an ordinary ceramic sintered body. I confirmed that I have it. The PE hysteresis curve of the electromechanical conversion element of Example 1 is shown in FIG.

The electro-mechanical conversion ability was calculated by measuring the amount of deformation by applying an electric field with a laser Doppler vibrometer and fitting it through simulation. According to the evaluation results, the piezoelectric constant d ₃₁ of Examples 1 and 2 was 110 to 125 pm / V, which was also the same value as the ceramic sintered body. This is a characteristic value that can be sufficiently designed as a liquid discharge head.

Further, an attempt was made to further increase the film thickness without arranging the second electrode (upper electrode).
That is, SAM film treatment → sol-gel solution coating → drying step at two temperature rising rates (300 ° C.) → thermal decomposition step at 500 ° C. is repeated 6 times, and then crystallization treatment is performed at 750 ° C. The operation was performed 10 times in total to form a piezoelectric film having a total of 60 layers and a thickness of 5 μm. It was confirmed that the obtained piezoelectric film was obtained without defects such as cracks.
[Example 3]
In the drying step, a piezoelectric film was prepared and evaluated in the same manner as in Example 1 except that the temperature at which the first temperature rising rate and the second temperature rising rate were changed to 145 ° C. The evaluation results are shown in Table 1.

  According to Table 1, the film thickness ratio of the first piezoelectric film is 0.96, and the film thickness ratio at the time of repeated application six times (third time), that is, when the 18-layer piezoelectric film is formed is 0. .94. In this comparative example, the film thickness unevenness of the piezoelectric film hardly occurred, and the film thickness configuration and electrical characteristics were the same as in Example 1.

The heat treatment time in the drying process is longer by 0.5 minutes per sol-gel liquid application than in Example 1, and in the series of 18 sol-gel liquid applications, the tact time of the entire process is It was 9 minutes longer than Example 1. However, the time required for manufacturing the piezoelectric film was substantially the same as that in Example 1, and it was confirmed that the piezoelectric film had sufficient productivity.
[Comparative Example 1]
The experiment was conducted in the same manner as in Example 1 except that the heat treatment was carried out at a single temperature rise rate from room temperature to the drying temperature of 300 ° C. with a temperature rise rate of 30 ° C./min in the drying step. .

  Table 1 shows the evaluation results. According to Table 1, the film thickness ratio of the first piezoelectric film is 0.96, and the piezoelectric film is repeatedly applied six times (third time), that is, a piezoelectric film in which a total of 18 piezoelectric films are stacked. However, the film thickness ratio was 0.94. The film thickness unevenness of the piezoelectric film hardly occurred, and the film thickness configuration and electrical characteristics were the same as in Example 1.

However, the heat treatment time in the drying step was 3 minutes longer per application of the sol-gel solution than in Example 1. When a piezoelectric film having a film thickness of about 1.5 μm as in Example 1 is manufactured, the application is repeated 6 times 3 times, so that the application of the sol-gel solution is performed 18 times. Therefore, as shown in Table 1, the tact time of the entire process was 54 minutes longer than that of Example 1. Therefore, the productivity was inferior in comparison with Example 1.
[Comparative Example 2]
In the drying process, a piezoelectric film was prepared and evaluated in the same manner as in Example 1 except that the temperature at which the first temperature rising rate and the second temperature rising rate were changed to 100 ° C. The evaluation results are shown in Table 1.

  According to Table 1, in Comparative Example 2, the film thickness ratio of the first piezoelectric film was 1.88, which was about twice as large as that in Example 1, and a coffee stain phenomenon was observed.

  Similarly, after the application of sol-gel solution, drying, and thermal decomposition was repeated 6 times, the crystallization process was performed with the RTA apparatus, that is, when the 6-layer piezoelectric film was formed (repeatedly applied 6 times ( The piezoelectric film was observed in the first time)). Then, in this comparative example, generation | occurrence | production of the crack was confirmed in the edge part of the piezoelectric material film | membrane whose film thickness became extremely thick by the coffee stain phenomenon.

Furthermore, after repeating the application of the sol-gel solution, drying and thermal decomposition under the same conditions 6 times, the time until the crystallization process was performed 3 times in total, that is, the application of the above Example 1 repeatedly 6 times (the third time) 18 layers of piezoelectric films corresponding to the above were formed. The obtained piezoelectric film was measured at the end / center in the pattern longitudinal direction in the same manner as in Example 1. As shown in Table 1, the film thickness ratio was 2. 0. That is, it was confirmed that the piezoelectric film with more emphasized coffee stain phenomenon was obtained, and the electric characteristics of the obtained piezoelectric film were also inferior to those of Examples 1 and 2.
[Comparative Example 3]
In the drying step, a piezoelectric film was prepared and evaluated in the same manner as in Example 1 except that the second temperature rising rate was 15 ° C./min. The evaluation results are shown in Table 1.

  According to Table 1, the film thickness ratio of the first piezoelectric film is 0.96, and the film thickness ratio at the time of repeated application six times (third time), that is, when the 18-layer piezoelectric film is formed is 0. .94. In this comparative example, the film thickness unevenness of the piezoelectric film hardly occurred, and the film thickness configuration and electrical characteristics were the same as in Example 1.

However, the heat treatment time in the drying process is about 9 minutes per application of the sol-gel solution compared to Example 1, and the tact time of the entire process is performed in a series of 18 sol-gel solution applications. It was about two and a half hours longer than Example 1, and the productivity was significantly inferior to that of Example.
[Comparative Example 4]
A piezoelectric film was prepared and evaluated in the same manner as in Example 1 except that, in the drying step, the first temperature rising rate was 60 ° C./min and the second temperature rising rate was 90 ° C./min. The evaluation results are shown in Table 1.

  According to Table 1, the film thickness of the first piezoelectric film was 80 nm / 30 nm at the edge / center, the film thickness ratio was as large as 2.5 or more, and a coffee stain phenomenon was observed. .

  Similarly, after the application of sol-gel solution, drying, and thermal decomposition was repeated 6 times, the crystallization process was performed with the RTA apparatus, that is, when the 6-layer piezoelectric film was formed (repeatedly applied 6 times ( The piezoelectric film was observed in the first time)). Then, in this comparative example, generation | occurrence | production of the crack was confirmed in the edge part of the piezoelectric material film pattern in which the film thickness became extremely thick by the coffee stain phenomenon.

  Furthermore, after repeating the application of the sol-gel solution, drying, and thermal decomposition 6 times in the same manner, the step of performing the crystallization treatment was performed 3 times in total, that is, the application of the above Example 1 repeatedly 6 times (the third time 18 layers of piezoelectric films corresponding to the above were formed.

  The film thickness of the obtained piezoelectric film was measured at the end / center of the pattern longitudinal direction in the same manner as in Example 1. The film thickness was 1.8 / 0.6 μm (end / center). ), The film thickness ratio was 3.0. That is, a piezoelectric film in which the coffee stain phenomenon is more emphasized is obtained, and compared with Examples 1 and 2 in which the film thickness ratio is 0.94 (Example 1) and 1.23 (Example 2). It was confirmed that the film thickness ratio was very large.

  Further, as in the case of Example 1, the second electrode (upper electrode) (Pt) is formed by sputtering on the formed patterned piezoelectric film, and is patterned, so that the electro-mechanical conversion element It took the form of When the obtained electro-mechanical conversion element was evaluated, it was confirmed that the piezoelectric film had a dielectric constant of 1100, a dielectric loss of 27, and a withstand voltage of 2 V, and did not function as a piezoelectric film.

31, 64 Substrate 32, 661 First electrode 54, 54 ', 662 Piezoelectric film 663 Second electrode 66 Electro-mechanical conversion element 60, 67 Liquid discharge head 70 Inkjet printer

International Publication No. 03/098714

Claims (4)

Forming a patterned sol-gel film by partially applying a sol-gel liquid to the first electrode surface provided on the substrate by an inkjet method;
Drying the sol-gel film by heat-treating the sol-gel film,
The step of drying the sol-gel film includes a first temperature raising step of raising the heating temperature of the sol-gel film from room temperature to a predetermined change point temperature _Tc at a first temperature raising rate;
A second temperature raising step of changing the temperature rising rate to the second temperature rising rate after reaching the change point temperature _Tc and raising the heating temperature of the sol-gel film to the drying temperature of the sol-gel film; Have
The change point temperature T _c satisfies the relationship of T _bp −23 ≦ T _c ≦ T _bp +23 with the boiling point T _bp of the main solvent of the sol-gel solution,
The heating rate per minute of the first heating rate is 45% or less of the boiling point of the main solvent of the sol-gel liquid,
The method for manufacturing a piezoelectric film, wherein the first temperature rise rate is slower than the second temperature rise rate.   2. The piezoelectric device according to claim 1, further comprising a step of thermally decomposing the sol-gel film and / or a step of crystallizing the sol-gel liquid after the step of drying the sol-gel film. Manufacturing method of body membrane.   A method for manufacturing a piezoelectric film, wherein the piezoelectric film having a desired film thickness is obtained by repeatedly performing the method for manufacturing a piezoelectric film according to claim 1.   An electro-mechanical conversion element comprising a step of disposing a second electrode on a piezoelectric film manufactured by the method for manufacturing a piezoelectric film according to claim 1. Production method.