JP2009209413A - Method for selecting optimum condition for execution of aerosol deposition method, and film forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for selecting the optimum condition of execution of the aerosol deposition method so that the film after the annealing treatment can maintain the excellent performance. <P>SOLUTION: A base material and material particles are prepared. The film of the material particles is deposited on a surface of the base material by executing the aerosol deposition method under the predetermined condition of execution by using the base material and the material particles. The thickness and the modulus of elasticity of the formed film are measured. The film is annealed by heating the base material with the film deposited thereon. The performance of the annealed film is evaluated. The data of the considerably large number is collected by repeating the processes while changing the condition of execution. The optimum range of the film thickness and the modulus of elasticity is selected based on the relative merits of the performance of the evaluated film in the data of the considerably large number. Then, the condition of execution in which the film thickness and the modulus of elasticity in the optimum range are given is determined as the optimum condition of execution. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides a method for selecting an optimum implementation condition of an aerosol deposition method in which film formation is performed by spraying aerosol on a substrate at a high speed, and a composition based on the aerosol deposition method in the optimum implementation condition obtained by the method. It relates to a method of performing a membrane.

  In recent years, an aerosol deposition method has attracted attention as a method for forming a piezoelectric film in a piezoelectric actuator used in an inkjet printer or the like. In the aerosol deposition method, an aerosol formed by dispersing ceramic fine particles in a gas is sprayed from a nozzle and sprayed onto the substrate surface at a high speed to pulverize and deposit the fine particles on the substrate to form a ceramic thin film. is there. This method uses the normal temperature impact solidification phenomenon caused by the induction of the mechanochemical reaction caused by the release of the local impact energy generated by the collision of ceramic fine particles with the substrate surface. Is a film formation technique that acts as a reaction energy during film formation. This film forming method is performed at room temperature, and does not require the sintering process at 900 ° C. or higher, which is performed in the conventional ceramic forming method. Therefore, it is not necessary to design a thin film in consideration of dimensional accuracy, and a dense nanocrystal structure can be formed by crushing fine particles.

When film formation is performed by the aerosol deposition method, annealing treatment by heating is performed after film formation (see, for example, Patent Document 1). The annealing treatment is intended to stabilize the piezoelectric characteristics and the like of the thin film by heating the thin film formed by the aerosol deposition method to grow crystal grains on the surface of the thin film. In the conventional ceramic sintering process, a high temperature of 900 ° C. or higher is required, but in comparison with this, the annealing treatment can be performed at a relatively low temperature.
JP 2007-88449 A

  However, by performing the annealing treatment, the formed film may be peeled off, or the film may become conductive and short-circuited, which has been a factor in reducing the yield of products. However, the cause of these defects has not been accurately grasped.

  For this reason, it is desirable to optimize the implementation conditions of the aerosol deposition method for each type of substrate and material so as not to cause defects such as film peeling and short circuits due to annealing treatment. At the time of film formation, which is a stage, it was impossible to predict film performance after annealing including film peeling and short circuit.

  Accordingly, the present invention provides a method for selecting an optimum implementation condition for the aerosol deposition method so that the annealed film can maintain excellent performance, and film formation by the aerosol deposition method under the selected optimum implementation condition. The object is to provide a method of performing.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the elastic modulus and film thickness of the film before the annealing treatment and the film performance after the annealing treatment (particularly, the presence or absence of film peeling and the presence or absence of conduction) And the modulus of elasticity before the annealing treatment depends on the conditions of the aerosol deposition method (especially the flow velocity of the aerosol flow, the angle of incidence of the aerosol flow on the substrate surface, the relationship between the substrate and the injection nozzle) It was found that control is possible by adjusting the distance), and the present invention has been completed based on these findings.

  That is, the first aspect of the present invention is a method for selecting an optimum implementation condition of an aerosol deposition method in which film formation is performed by spraying an aerosol generated by dispersing material particles in a carrier gas as an aerosol flow on a substrate. A first step of preparing a base material and material particles for which selection of optimal implementation conditions is desired, and by performing an aerosol deposition method under a certain implementation condition using the base material and the material particles, After the second step of forming the film of the material particles on the surface of the base material, the third step of measuring the film thickness and elastic modulus of the film formed in the second step, the third step, A fourth step of annealing the film by heating the substrate on which the film is formed, a fifth step of evaluating the performance of the film annealed in the fourth step, while changing the execution conditions First Optimum film thickness and elastic modulus based on superiority or inferiority of the film performance evaluated in the fifth process in the sixth process in which a considerable number of data is collected by repeating the process to the fifth process The present invention relates to a selection method including a seventh step of selecting a range, and then determining an execution condition that gives a film thickness and an elastic modulus in the optimal range as the optimal execution condition.

  As described above, since there is a relationship between the elastic modulus and film thickness of the film before annealing and the film performance after annealing, a considerable amount of data can be obtained while changing the conditions during film formation. By obtaining the above, it is possible to select the elastic modulus and film thickness when excellent film performance can be achieved. The film forming conditions when the elastic modulus and film thickness are achieved are determined as the optimum conditions for carrying out the aerosol deposition method. As described above, in the aerosol deposition method, it is possible to select an optimum implementation condition that allows the annealed film to maintain excellent performance.

  In the first aspect of the present invention, the execution conditions to be changed in the sixth step are the flow velocity of the aerosol flow when sprayed on the base material, the distance between the surface of the base material and the injection nozzle for injecting the aerosol flow, It is preferably at least one of the inclination angles of the aerosol flow with respect to the surface of the substrate.

  The elastic modulus of the film before annealing varies greatly depending on the difference in these implementation conditions. By changing these implementation conditions, it is possible to efficiently select the elastic modulus when excellent film performance can be achieved. it can.

  In the third aspect of the present invention, it is preferable to evaluate the film performance in the fifth step based on at least the presence or absence of film peeling.

  Accordingly, it is possible to select an optimum execution condition of the aerosol deposition method in which the thin film formed by the aerosol deposition method does not peel from the substrate by the annealing treatment.

  In 1st this invention, it is preferable to evaluate the film | membrane performance in a 5th process based on the presence or absence of film | membrane peeling and the presence or absence of conduction | electrical_connection.

  Accordingly, it is possible to select the optimum conditions for the aerosol deposition method in which the thin film formed by the aerosol deposition method is not peeled off from the base material by the annealing process and a short circuit does not occur. That is, it is possible to select the optimum conditions for the aerosol deposition method for producing a thin film that can be suitably used as a piezoelectric film.

  The second aspect of the present invention is a film forming method in which film formation is performed by performing an aerosol deposition method under the optimum execution conditions selected by the method according to the first aspect of the present invention.

  According to the second aspect of the present invention, since the film is formed by performing the aerosol deposition method under the selected optimum execution conditions, the formed film has very excellent film performance after the annealing treatment. Thus, problems such as film peeling and short circuit can be avoided.

  According to the present invention, it is possible to select an optimal implementation condition for the aerosol deposition method in that the film after annealing can maintain excellent performance. In addition, an aerosol deposition method can be performed under the selected optimum execution conditions to produce a thin film that retains excellent performance even after annealing.

  The present invention is for selecting an optimum execution condition of an aerosol deposition method in which film formation is performed by spraying an aerosol generated by dispersing material particles in a carrier gas as an aerosol flow onto a substrate. First, the aerosol deposition method will be described.

  FIG. 1 is a diagram schematically showing a film forming apparatus based on an aerosol deposition method according to an embodiment of the present invention. The film forming apparatus includes an aerosol generator 1 for generating aerosol by dispersing material particles in a carrier gas, and a chamber 2 for performing film formation inside.

  The aerosol generator 1 stores a predetermined amount of material particles and introduces a carrier gas. In the aerosol generator 1, a winding gas is generated when the carrier gas is introduced, and further, by applying vibration using an ultrasonic vibration device from the lower part, the material particles are dispersed in the carrier gas to generate an aerosol. As said carrier gas, inert gas, such as helium and argon, nitrogen, air, oxygen etc. can be used, for example.

  One end of an aerosol supply pipe 3 is inserted in the upper part of the aerosol generator 1. The other end of the aerosol supply pipe 3 is disposed inside the chamber 2 and is connected to an injection nozzle 4.

  A mechanical booster pump, a rotary pump, and the like are connected to the chamber 2 so that the inside of the chamber 2 can be depressurized. As a result, the internal pressure of the chamber 2 becomes lower than the internal pressure of the aerosol generator 1, so that the aerosol generated in the aerosol generator 1 is sucked into the aerosol supply pipe 3 by the differential pressure and passes through it. And supplied to the injection nozzle 4.

  Since the cavity inside the injection nozzle 4 has such a shape that the cross-sectional area decreases as it travels inside, the aerosol entering the inside of the injection nozzle 4 from the introduction opening of the injection nozzle 4 is accelerated. Then, the aerosol flow 5 is sprayed from the injection opening of the injection nozzle 4 onto the substrate 7 at a high speed. The material particles colliding with the surface of the base material 7 are crushed and deposited to form a thin film.

  Inside the chamber 2, a substrate holder 6 serving as a holding unit for attaching the substrate 7 to the lower surface is disposed above the injection opening of the injection nozzle 4. The substrate holder 6 has a rectangular plate shape, and is suspended from the ceiling of the chamber 2 in a horizontal posture by a driving device 8 as driving means. The driving device 8 is configured to drive the substrate holder 6 in the left-right direction in FIG. By this reciprocating motion in the left-right direction, scanning film formation on the substrate 7 is performed. By this scanning film formation, a thin film is formed in a predetermined wide range of the substrate 7.

  As a base material that is a film formation target, a stainless steel substrate is typically exemplified, but the substrate is not limited thereto, and may be a substrate made of other metal, silicon, semiconductor, resin, or the like. Moreover, what formed the thin film which consists of ceramics, such as an alumina and a zirconia, on the sheet | seat which consists of these materials can also be used as a base material. In the aerosol deposition method according to an embodiment of the present invention, a base material that is a film formation target refers to a substrate in which a diffusion prevention layer and a lower electrode are stacked on a vibration plate. According to a preferred embodiment, the vibration plate is a stainless steel substrate, the diffusion prevention layer is an alumina or zirconia thin film separately formed by an aerosol deposition method, and the lower electrode is a Ti / Pt formed by a sputtering method. It is an electrode layer which consists of.

  A typical example of a material constituting the material particles, that is, a thin film material formed by an aerosol deposition method is lead zirconate titanate (PZT). Lead zirconate titanate is generally known as a material that achieves a desired piezoelectric effect with a film thickness of about several μm. According to the study by the present inventors, PZT is a material that has a very narrow range of optimum conditions for the aerosol deposition method, and therefore, the significance of applying the present invention is particularly great.

  However, the material constituting the material particles is not limited to this. For example, aluminum oxide, zirconium oxide, barium titanate, lead titanate, lead magnesium niobate (PMN), lead nickel niobate (PNN), zinc niobate Ceramics such as lead and organic resins may be used.

  The particle size of the material particles may be any particle size that can be used in the aerosol deposition method, and may be, for example, about 0.5 μm to 5.0 μm.

  The film thickness of the thin film formed by the aerosol deposition method is usually about several μm to several tens of μm.

  Next, each step in the optimum execution condition selection method of the present invention will be specifically described.

  (1) In the first step, a base material and material particles for which selection of optimal implementation conditions is desired are prepared.

  Even when the aerosol deposition method is performed under the same conditions, the elastic modulus of the thin film obtained varies depending on the type of base material and the type of material particles.

  FIG. 2 is a graph showing that the elastic modulus of the thin film formed thereon varies depending on the type of substrate that is the film formation target. FIG. 2 shows the relationship between the thickness of the PZT film formed by the aerosol deposition method and the elastic modulus (before annealing) of the PZT film for two types of base materials. The experimental method is in accordance with Example 1 described later.

  The data shown by diamonds in FIG. 2 is based on a stainless steel plate in which an alumina film is formed by an aerosol deposition method and a Ti (0.05 μm) / Pt (0.5 μm) layer is laminated as a lower electrode. This data relates to the case where it is used, and the data indicated by squares shows data when a sintered alumina plate is used as a base material. From this graph, the elastic modulus of the thin film decreases with increasing film thickness when the film thickness is less than about 10 μm, and the elastic modulus tends to be almost constant when the film thickness exceeds about 10 μm. However, it can be seen that the elastic modulus of the thin film varies greatly depending on the type of substrate.

  Moreover, since the kind of material which comprises a thin film will differ if the kind of material particle differs, it is natural that the elasticity modulus of a thin film changes with kinds of material particle.

  Therefore, it is preferable to determine the optimum implementation conditions for the aerosol deposition method for each type of substrate and each type of material particles. In this step, a base material and material particles that require information on optimum execution conditions are prepared.

  (2) In the second step, using the substrate and material particles prepared in the first step, an aerosol deposition method is performed under certain implementation conditions to form a film of the material particles on the surface of the substrate. To do.

  The “certain execution condition” is not particularly limited as long as the film can be normally formed by the aerosol deposition method. However, since this process is a process for collecting data on the optimum execution condition, It is necessary to accurately record the implementation conditions applied in.

  (3) In the third step, the thickness and elastic modulus of the thin film formed in the second step are measured.

  In this step, the film thickness and elastic modulus of the thin film are measured before annealing. This is because the present inventors have found that there is a relationship between the film thickness and elastic modulus and the presence or absence of film peeling and the presence or absence of conduction, which are film performances after annealing. This relationship is shown in FIG.

  FIG. 3 is a graph showing the relationship between the evaluation of film performance after annealing and the film thickness and elastic modulus. The horizontal axis indicates the film thickness of the thin film, and the vertical axis indicates the elastic modulus of the thin film before annealing. . Details will be described in Example 1 described later. These data are based on a stainless steel plate in which an alumina film is formed on the surface and a Ti (0.05 μm) / Pt (0.5 μm) layer is laminated as a lower electrode. As a material, the present invention relates to a case where a PZT film is formed on this substrate by an aerosol deposition method. A lot of data was acquired by changing the deposition conditions of the aerosol deposition method. The data indicated by the circles indicate that there was no film peeling after the annealing treatment and the electrical evaluation was good. The data indicated by the triangles indicate that there was no film peeling after annealing, but the electrical evaluation was poor. The data indicated by crosses are those in which film peeling was confirmed after annealing. In addition, the presence or absence of film peeling is judged visually after the formation of the thin film, and the electrical evaluation is based on the presence or absence of conduction. An upper electrode is provided on the surface of the formed thin film, and a conduction tester is used between the lower electrode And evaluated.

  As can be seen from FIG. 3, the data indicating that the evaluation of the film performance after the annealing process indicated by the circles is good is the range enclosed by the ellipse (the elastic modulus is approximately 80 to 180 GPa, the film thickness is approximately 4 to 4). 10 μm). Therefore, in order to improve the film performance after annealing, the aerosol deposition method is performed under such conditions that the film thickness and elastic modulus of the thin film before annealing are within the range enclosed by the ellipse. Should be implemented. Therefore, in this step, the film thickness and elastic modulus of the thin film are measured before annealing.

  (4) Fourth step: After the third step, annealing is performed by heating the base material having a thin film formed on the surface in the second step.

  In the aerosol deposition method, the sprayed fine particles collide with the substrate and adhere while being pulverized, so that the formed thin film as it is for finer particles due to collision, generation of lattice defects, etc. The piezoelectric properties do not reach a sufficient level. For this reason, it is necessary to perform an annealing process after the film formation in order to achieve the necessary piezoelectric characteristics.

  Annealing treatment is heating the thin film formed by the aerosol deposition method, which achieves growth of crystal grains on the surface of the thin film and correction of lattice defects, thereby improving the piezoelectric properties and the like of the thin film. it can.

  Annealing can be performed, for example, by heating at about 500 to 1000 ° C. for about several minutes to several hours.

  (5) Fifth step: The performance of the thin film annealed in the fourth step is evaluated.

  In the evaluation of the film performance, it is evaluated whether or not the thin film is in close contact with the base material and whether or not the formed thin film can exhibit performance that matches the intended purpose of the piezoelectric element or the like. Specifically, as described above, the presence / absence of film peeling may be visually evaluated, or the electrical evaluation based on the presence / absence of conduction between electrodes disposed above and below the thin film may be performed. The former film peeling is an evaluation item that is always required when a thin film is formed on a substrate by the aerosol deposition method, and the latter electric evaluation is an evaluation item that is particularly useful when the formed thin film is used as a piezoelectric film. It is.

  (6) Sixth step: While changing the implementation conditions of the aerosol deposition method in the second step, a considerable amount of data is collected by repeating the second step to the fifth step.

  The implementation conditions to be changed in this step may be any conditions as long as they affect the film thickness or elastic modulus of the thin film to be formed.

  The implementation conditions that affect the thickness of the thin film include various things such as the spraying time of the aerosol flow on the base material, the average particle diameter of the material particles, the scanning speed and the number of scans of the substrate.

  Implementation conditions that affect the elastic modulus include the flow velocity of the aerosol flow when sprayed on the substrate, the inclination angle of the aerosol flow with respect to the surface of the substrate, and the distance between the injection nozzle and the substrate. These greatly influence the elastic modulus of the thin film to be formed.

  While varying these implementation conditions, the aerosol deposition method is repeated using the same substrate and material particles as used in the first step, and a considerable amount of data is collected. The considerable amount of data collected has a relationship that exists between the film thickness and elastic modulus of the film before annealing and the film performance after annealing (particularly, whether there is film peeling or pinholes). This is the number of data required to be revealed. Although it is preferable to collect a statistically significant number, it is only necessary to collect a number that can roughly determine the relevance even if it is not significant.

  It should be noted that the flow rate of the aerosol flow when sprayed on the substrate described above can be adjusted by the type of carrier gas and the flow rate of the carrier gas.

  FIG. 4 is a graph showing the relationship between the set flow rate of the carrier gas and the estimated flow velocity of the aerosol flow when helium gas or oxygen gas is used as the carrier gas. Here, helium gas or oxygen gas was used as a carrier gas at various flow rates, and an estimated value of the average flow velocity when PZT particles having a particle size of 3 μm were injected was obtained by jet simulation. From this graph, the relationship between the set flow rate of the carrier gas and the flow velocity of the aerosol flow varies greatly depending on the type of the carrier gas, and the flow velocity of the aerosol flow is accelerated in the helium gas with a small molecular weight compared to the oxygen gas. It can be seen that it increases.

  FIG. 5 is a graph showing that the flow velocity of the aerosol flow affects the elastic modulus of the formed thin film. FIG. 5 shows the relationship between the flow velocity of the aerosol flow adjusted by changing the type of carrier gas and the flow rate of the carrier gas, and the elastic modulus of the formed PZT thin film. Here, a stainless steel plate having an alumina film with a thickness of about 2 μm formed on the surface was used as a substrate, and a PZT thin film with a thickness of about 5 μm was formed while changing the type of carrier gas and the flow rate of the carrier gas. The specific experimental method was the same as in Example 1. The estimated flow velocity in FIG. 5 is a value converted from the graph of FIG. This graph shows that the elastic modulus of the formed PZT thin film increases linearly as the flow velocity of the aerosol flow increases.

  Regarding the inclination angle of the aerosol flow with respect to the substrate surface, it has been found that the elastic modulus of the film is improved when the aerosol flow is inclined to some extent as compared with the case where the aerosol flow is perpendicular to the substrate. . This is because if the aerosol flow is perpendicular to the base material, the impact force is insufficient and coarse particles that have not adhered to the base material are mixed into the film, creating voids in the film. In some cases, if the aerosol flow is tilted to some extent with respect to the base material, the particles that have not adhered to the base material will easily escape to the side opposite to the side where the aerosol flow is sprayed, so voids are less likely to occur. As a result, it is considered that the elastic modulus of the film is improved.

  As for the distance between the injection nozzle and the base material, the collision force of the particles increases and becomes a dense film when it is close to a certain extent compared to the case where the injection nozzle is away from the base material. It has been found that the elastic modulus of the membrane is improved.

  Using the above knowledge, the second step is repeated while changing the implementation conditions of the aerosol deposition method so that a considerable number of thin films having different film thicknesses and elastic moduli can be obtained. For a considerable number of thin films thus obtained, the film thickness and elastic modulus are measured (third step), and after annealing treatment (fourth step) under the same conditions, the film performance is evaluated on the same basis. (Fifth step). In this way, a considerable amount of data is collected regarding the conditions for carrying out the aerosol deposition method, the film thickness and elastic modulus of the thin film, and the film performance after annealing.

  (7) Seventh step: In a considerable number of data obtained in the sixth step, the optimum range of film thickness and elastic modulus is selected based on the superiority or inferiority of the film after annealing treatment, and then the film in the optimum range The execution condition given the thickness and elastic modulus is determined as the optimal execution condition.

  In this step, first, in the considerable number of data obtained in the sixth step, the optimum range of the film thickness and elastic modulus before the annealing treatment is selected based on the superiority or inferiority of the film after the annealing treatment. For this purpose, the considerable number of data is arranged so that the relationship between the numerical values of the thin film thickness and the elastic modulus and the superiority or inferiority of the film performance can be understood. For this purpose, for example, as shown in FIG. 3 and FIG. 6, a graph with the horizontal axis as the film thickness and the vertical axis as the elastic modulus is prepared, and the above-described equivalent is shown so that the superiority or inferiority of the film performance can be understood. Plot the number data. As a result, it is possible to determine at a glance the range in which data with good film performance after annealing is concentrated (the range surrounded by an ellipse in FIG. 3). Thus, the range in which data with good film performance is concentrated may be selected as the optimum range of film thickness and elastic modulus.

  Next, the execution conditions of the aerosol deposition method when the film thickness and the elastic modulus in the optimum range thus obtained are given are determined as the optimum execution conditions. Such optimum implementation conditions are preferably determined for each type of substrate and each type of material particle.

  By performing actual film formation by the aerosol deposition method under the optimum execution conditions determined as described above, it becomes possible to reliably manufacture a thin film having excellent film performance. In the actual film formation in this case, it is preferable to use the same type of substrate and material particles as those used in the above-described method for selecting the optimum execution conditions. Moreover, it is preferable to make it the same about the conditions of annealing treatment.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1
1. First step Diffusion bonding SUS plate (head) and SUS plate for evaluation: 15 × 35 × 0.4t, as a diffusion preventing layer in the film forming apparatus based on the aerosol deposition method based on the embodiment described above An Al ₂ O ₃ film was formed with a thickness of about 2 μm.

This process will be specifically described below. An aerosol generator was charged with 140 g of Al ₂ O ₃ powder. Each SUS plate was set on the substrate holder, and the portions other than the film formation range were attached with tape. The substrate holder was set on the XY stage in the film forming chamber, and reciprocal scanning was started. In addition, the stage movement repeated the “U-shaped movement”, and two rows (two sheets) of film formation were performed in the same batch. The chamber as the film forming chamber was evacuated to reach the ultimate vacuum pressure of 10 to 20 Pa. Carrier gas was introduced from three systems (flow, crushing, acceleration), and the raw material powder was fluidly stirred. In accordance with a predetermined total flow rate (total of three systems), the flow gas flow rate was set constant while observing the flow state, and then the ratio of the crushing gas and the acceleration gas was changed to adjust the desired aerosol concentration. After performing idle injection: 5 min outside the film formation range, aerosol was injected onto each SUS plate for a predetermined film formation time. After the predetermined film formation time was completed, the film formation gas was stopped and the film formation chamber was opened in vacuum. The substrate holder was removed from the XY stage to obtain each SUS plate on which an AD film had been formed under the desired film formation conditions.

Each SUS plate on which the Al ₂ O ₃ film was formed was subjected to ultrasonic cleaning for 1 minute to remove the adhered powder. Water was removed at 150 ° C. × 30 min and dried. The Al ₂ O ₃ thickness of each SUS plate was measured using a step gauge. A Ti (0.05 μm) / Pt (0.5 μm) layer was formed as a lower electrode on the surface of the Al ₂ O ₃ film using a sputtering apparatus. Using a muffle furnace, annealing was performed at 500 ° C. for 30 minutes to release the Pt residual stress. The SUS plate / alumina film / lower electrode thus obtained was used as a substrate.

2. Second Step A PZT film was formed on the upper surface of the substrate by the same aerosol deposition method as described above (however, PZT powder: 200 g was used instead of Al ₂ O ₃ powder: 140 g). Thereafter, the surface was air blown to remove the adhered powder.

3. 3rd process About the obtained PZT film | membrane, the film thickness was measured using the level | step difference meter.

  Next, using a nanoindenter, the elastic modulus (before heat treatment) of the PZT film on the evaluation SUS plate was measured at a load of 5 mN. Note that the diffusion bonded SUS plate is not used as an evaluation substrate because load control is difficult because there are many flexible structures such as a diaphragm, and the elastic modulus cannot be measured accurately.

4). Fourth Step Using a muffle furnace, annealing was performed at 850 ° C. for 30 minutes to grow crystal grains of the PZT film on each SUS plate.

5. Fifth Step The appearance of the annealed PZT film was observed, and when there was peeling on the entire surface, it was determined that there was film peeling.

  On the other hand, Au (0.2 μm) serving as an upper electrode was formed on the surface of the PZT film on the diffusion bonded SUS substrate through a metal mask. Using a continuity tester, a short-circuit was confirmed between the lower electrode: Pt and the upper electrode: Au layer. When all the shorts were detected, the electrical evaluation was poor, and when the measurement was possible, the electrical evaluation was judged to be good.

6). Sixth step While changing the carrier gas flow rate (ie, aerosol flow rate) and the film formation time, repeat steps 2 to 5 to collect data on the film thickness, elastic modulus, and film performance of the thin film. did.

7). Seventh Step The data obtained in the sixth step was entered in a graph with the horizontal axis as the film thickness and the vertical axis as the elastic modulus. At this time, the case where there was no film peeling after the annealing treatment and the electrical evaluation was good is indicated by a circle, and the case where there was no film peeling after the annealing treatment but the electrical evaluation was poor is indicated by a triangular mark. In the figure, the case where film peeling was confirmed after the annealing treatment was indicated by cross marks. The results are shown in FIG. The data indicated by the circles are concentrated in a range enclosed by an ellipse (elastic modulus is approximately 80 to 180 GPa, film thickness is approximately 4 to 10 μm). This range shows the optimum implementation conditions, and according to the implementation conditions that give the film thickness and elastic modulus within this range, the PZT film has excellent film performance after annealing (particularly, film performance as a piezoelectric film). Can be formed on the SUS plate / alumina film / lower electrode.

(Example 2)
Example 1 was repeated in the same manner except that in the first step, ZrO ₂ powder: 160 g was used instead of Al ₂ O ₃ powder: 140 g, and the substrate was made of SUS plate / zirconia film / lower electrode. The graph obtained by this is shown in FIG.

  Here, the data with good evaluation of the film performance indicated by the circles insist that the elastic modulus is about 100 to 150 GPa and the film thickness is about 3 to 7 μm. This range corresponds to the optimum execution conditions, and according to the execution conditions that give the film thickness and elastic modulus within this range, the PZT film with excellent film performance after the annealing treatment is formed on the SUS plate / zirconia film / lower electrode. Can be formed.

  Further, it can be seen from the comparison between FIG. 3 and FIG. 6 that the optimum execution conditions differ depending on the type of the base material (in this case, the type of the intermediate film as the diffusion preventing layer).

Schematic of the film-forming apparatus based on the aerosol deposition method in embodiment of this invention Graph showing the relationship between the elastic modulus before annealing and the film thickness according to the type of substrate A graph showing the relationship between the evaluation of film performance after annealing and the elastic modulus and film thickness before annealing for a stainless steel plate with an alumina film formed on the surface. A graph showing the relationship between the flow rate of the carrier gas and the flow velocity of the aerosol flow when helium gas or oxygen gas is used as the carrier gas. Graph showing the relationship between the flow velocity of the aerosol flow and the elastic modulus of the deposited PZT thin film A graph showing the relationship between the evaluation of film performance after annealing and the elastic modulus and film thickness before annealing for a stainless steel plate with a zirconia film formed on the surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aerosol generator 2 Chamber 3 Aerosol supply pipe 4 Injection nozzle 5 Aerosol flow 6 Substrate holder 7 Substrate 8 Driving device

Claims (5)

A method of selecting an optimal implementation condition of an aerosol deposition method in which film formation is performed by spraying an aerosol generated by dispersing material particles in a carrier gas on a substrate as an aerosol flow,
A first step of preparing the base material and material particles for which selection of the optimum implementation conditions is desired;
A second step of forming a film of the material particles on the surface of the substrate by performing an aerosol deposition method under certain implementation conditions using the substrate and the material particles;
A third step of measuring the film thickness and elastic modulus of the film formed in the second step;
After the third step, a fourth step of annealing the film by heating the base material on which the film is formed;
A fifth step of evaluating the performance of the film annealed in the fourth step;
A sixth step of collecting a considerable number of data by repeating the second step to the fifth step while changing the execution conditions;
In the substantial number of data, the optimum range of film thickness and elastic modulus was selected based on the superiority or inferiority of the film evaluated in the fifth step, and then the film thickness and elastic modulus of the optimum range were given. And a seventh step of determining the conditions as optimum execution conditions.   The implementation conditions to be changed in the sixth step are the flow velocity of the aerosol flow when sprayed on the base material, the distance between the surface of the base material and the injection nozzle for injecting the aerosol flow, and the aerosol with respect to the surface of the base material The selection method according to claim 1, wherein the selection angle is at least one of an inclination angle of the flow.   The selection method according to claim 1 or 2, wherein the film performance in the fifth step is evaluated based on at least the presence or absence of film peeling.   The selection method according to claim 3, wherein the film performance in the fifth step is evaluated based on the presence or absence of film peeling and the presence or absence of conduction.   The film-forming method of forming into a film by performing the aerosol deposition method on the optimal implementation conditions selected by the method of any one of Claims 1-4.