JP6800636B2 - Piezoelectric film-forming substrate and its manufacturing method, piezoelectric substrate, and liquid discharge head - Google Patents

Description

The present invention relates to a piezoelectric film forming substrate and a method for manufacturing the same, a piezoelectric substrate, and a liquid discharge head.

In order to improve the adhesion between the base substrate and the lower electrode of the piezoelectric element in the piezoelectric film forming substrate, a layer structure having a Ti intermediate layer between the layers is often adopted (see Patent Document 1).

Further, in order to improve the piezoelectric characteristics of the piezoelectric element, it has been proposed to improve the (100) degree of orientation of the piezoelectric thin film, particularly PZT (lead zirconate titanate). Patent Document 2 discloses a layer structure having a Ti nucleus 100% film of 3 to 7 nm between the lower electrode layer and the piezoelectric thin film layer. Further, in Non-Patent Document 1, a PbTiO ₃ layer for controlling orientation is provided between the lower electrode layer and the piezoelectric thin film layer, and the piezoelectric layer has a composition in which the amount of PbO is abundant (the amount of TiO ₂ is deficient). (100) The suggestion that the plane orientation becomes dominant is disclosed. Regarding the PbTiO ₃ layer, Patent Document 1 also applies and dries the raw material compound (precursor) of the PbTiO ₃ layer as a base of PZT (lead zirconate titanate), and then coats and dries the raw material compound of PZT. , Finally firing is disclosed.

Japanese Unexamined Patent Publication No. 10-126204 Japanese Unexamined Patent Publication No. 2003-298136 (Patent No. 3965134)

P. Muralt, J. et al. Apple. Phys. 100, 051605 (2006)

Patent Document 2 and Non-Patent Document 1 disclose that a piezoelectric thin film having a high degree of orientation (100) can be obtained. However, in Patent Document 2, a lower electrode having at least an Ir layer is formed on the ZrO ₂ film, and a Ti nucleus 100% film is formed on the lower electrode, which is different from the layer structure provided in the present invention.

In the formation of the PbTIO ₃ layer as in Patent Document 1 and Non-Patent Document 1, there is a possibility that the configuration below the base electrode layer can be ignored. However, under the conditions for forming the PbTiO ₃ layer, particularly when the piezoelectric thin film is formed on the PbTiO ₃ precursor as in Patent Document 1, piezoelectric thin film is formed even if the composition is rich in the amount of PbO suggested in Non-Patent Document 1. The present inventors have found that the degree of (100) orientation of the body thin film may not be sufficiently improved.

The present invention has been made in view of the above problems. That is, the present invention provides a piezoelectric film forming substrate and a method for manufacturing the same, which can provide a piezoelectric element having a high ratio of orientation of the (100) plane of the piezoelectric thin film and, by extension, high piezoelectric characteristics. The present invention also provides a piezoelectric substrate using the piezoelectric film forming substrate, and a liquid discharge head including a piezoelectric element including the piezoelectric substrate.

One embodiment is
A base substrate layer containing at least SiO ₂ on its surface,
And an intermediate layer comprising a T i on the lower ground substrate layer,
An electrode layer containing Pt on the intermediate layer and
It has an orientation control layer on the electrode layer and
Ti was not detected on the surface of the electrode layer before the formation of the orientation control layer by the elemental quantitative analysis method .
The orientation control layer contains Pb, O and Ti, and the Ti in the Pb, O and Ti elements on the surface of the orientation control layer is 13.87 atomic% or more and 14.88 atomic% or less. The present invention relates to a substrate for forming a piezoelectric material .

By using the piezoelectric film-forming substrate of the above embodiment, it is possible to provide a piezoelectric substrate having a high ratio of orientation of the (100) plane of the piezoelectric thin film and, by extension, high piezoelectric characteristics. Further, by using this piezoelectric substrate, a liquid discharge head having excellent discharge droplet performance is provided.

It is a vertical cross-sectional schematic diagram which shows the piezoelectric thin film of one Embodiment. It is a vertical cross-sectional schematic diagram which shows the piezoelectric thin film of one Embodiment. It is a schematic perspective view which shows the liquid discharge head of one Embodiment. It is a schematic perspective sectional view which shows the liquid discharge head of one Embodiment. It is a schematic cross-sectional view which shows the liquid discharge head of one Embodiment. It is a figure which shows the X-ray diffraction pattern at the position (5) of the substrate in Example 1. FIG. It is a schematic diagram which shows the X-ray diffraction measurement point on the substrate in an Example and a comparative example. (A) is a diagram showing an XPS spectrum with respect to a total binding energy region on the Pt electrode surface of the piezoelectric film forming substrate of Example 1, and (b) is an enlarged view showing a Ti2p orbital region of the spectrum. It is a figure which shows the XPS spectrum with respect to the Ti2p orbital region on the Pt electrode surface of the piezoelectric film forming substrate of Comparative Example 1. It is a figure which shows the degree of (100) plane orientation of the PZT piezoelectric thin film laminated on the Ti amount ratio with respect to the Ti amount ratio on the orientation control layer surface of the piezoelectric film-forming substrate.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.
Here, a mechanism that causes high piezoelectric characteristics when the ratio of orientation of the (100) plane of the piezoelectric thin film is high will be described. The crystal orientation of the piezoelectric thin film formed by the sol-gel method is such that the orientation ratio of the (100) plane is higher than the orientation of the other planes ((111) plane, (110) plane, etc.), the direction of the polarization moment. Approaches the deformation direction of the piezoelectric body. Therefore, the larger the orientation ratio of the (100) plane is, the larger the deformation amount becomes, and it can be suitably used as an actuator such as a liquid discharge head.

1. 1. Piezoelectric film forming substrate FIGS. 1 and 2 are schematic vertical cross-sectional views of the piezoelectric film forming substrate of one embodiment. FIG. 1 shows a piezoelectric film forming substrate according to the first embodiment, which is composed of a laminate of a base substrate layer 1, an intermediate layer 2, and an electrode layer 3. Further, the schematic vertical cross-sectional view of FIG. 2 shows the piezoelectric film forming substrate according to the second embodiment in which the orientation control layer 4 is laminated on the piezoelectric film forming substrate having the configuration of FIG.

The base substrate layer 1 contains at least SiO ₂ or SiN on the surface, but as another material, a material that is not deformed or melted in the heat treatment that can be performed in the process of forming each layer formed on the substrate layer 1 is preferable. Further, it is preferable that the surface of the base substrate layer 1 is smooth, diffusion of elements during heat treatment can be prevented, and mechanical strength is sufficient. Further, when the liquid discharge head is manufactured using the piezoelectric substrate obtained by the present embodiment, the base substrate layer 1 may also serve as a pressure chamber substrate for forming a pressure chamber. For example, for such a purpose, a semiconductor substrate made of silicon (Si) or the like or a metal substrate such as tungsten (W) or heat-resistant stainless steel (SUS) can be preferably used as the material of the base substrate layer 1, but zirconia or alumina can be preferably used. , A ceramic substrate such as silica may be used. Further, a plurality of types of these substrate materials may be combined, or they may be laminated and used as a multilayer structure. SiO ₂ or SiN is formed on the surface of these materials to form the base substrate layer 1. For example, the Si substrate can be oxidized or nitrided to modify the surface to a layer containing SiO ₂ or SiN.

The intermediate layer 2 is a layer to be inserted in order to improve the adhesion between the base substrate layer 1 and the electrode layer 3. Therefore, the material of the intermediate layer 2 includes at least one of Ti and TiO ₂ . It is also possible to laminate the Ti layer and the TiO _two layer. Further, the intermediate layer 2 preferably has a layer thickness of 2 nm or more and 50 nm or less. This is because if the layer thickness of the intermediate layer 2 is 2 nm or more, a sufficient layer thickness for exhibiting adhesion can be secured, and if it is 50 nm or less, wasteful consumption of the material can be suppressed.

The material of the electrode layer 3 may be any material usually used for a piezoelectric element containing Pt, for example, a Pt metal film, an oxide film containing Pt, Ti, Ta, Ir, Sr, In, Sn, Au, etc. It may contain metals such as Al, Fe, Cr and Ni, and oxides thereof. The electrode layer 3 may be composed of one layer, or may be a stack of two or more of these layers. These metals and oxides may be formed by coating and firing on a substrate by a sol-gel method or the like, or may be formed by sputtering, vapor deposition or the like. Further, it may be used by patterning it into a desired shape. The electrode layer 3 preferably has a layer thickness of 40 nm or more and 1000 nm or less. In the first embodiment, a sputtering method having a relatively small heat history is suitable.

Since the several atomic layers on the sputtered surface are disturbed by ions, residual irradiation ions and formation of non-crystalline layers occur, heat treatment may be performed after sputtering in order to remove and stabilize them. This heat treatment may be performed in the sputtering apparatus or may be removed from the sputtering apparatus.

When a piezoelectric thin film was formed on a piezoelectric thin film having such a layer structure, a phenomenon was observed in which the degree of orientation of the (100) plane of the piezoelectric thin film varied depending on the heat treatment conditions. Regarding the cause of this, when the surface state of the piezoelectric film forming substrate before the piezoelectric thin film was formed, that is, the electrode layer 3 was examined, the degree of orientation decreased when the presence of Ti was confirmed on the electrode surface, and the Ti It was found that a high degree of orientation can be obtained when the existence is not confirmed. Conventionally, the detailed configuration of the piezoelectric film forming substrate with respect to Ti, which increases the degree of (100) plane orientation of the piezoelectric thin film, has not been clarified so far.

Therefore, the piezoelectric film forming substrate according to the first embodiment of the present invention has an intermediate substrate layer containing at least SiO ₂ or SiN on the surface and at least one of Ti and TiO ₂ on the substrate layer. It has a layer and an electrode layer containing Pt on the intermediate layer, and the surface of the electrode layer is characterized in that Ti is not detected by the elemental quantitative analysis method.

It is known to passivate the surface of the Ti layer in order to suppress the movement (migration) of Ti from the Ti layer. However, Ti migration occurs slightly depending on the temperature and time of the heat treatment after Pt sputtering. Therefore, in the present embodiment, the conditions for suppressing Ti migration are selected by controlling the temperature and time of the heat treatment at the time of forming the electrode layer and after forming the electrode layer. The selection of such heat treatment conditions can be performed experimentally. For example, when the electrode layer is formed by a sputtering method, the heat treatment after sputtering is preferably a temperature of 280 ° C. or lower. Further, in order to achieve the purpose of the heat treatment after sputtering such as removal of residual irradiation ions and crystallization, the temperature is preferably 100 ° C. or higher, more preferably 150 ° C. or higher. The heat treatment time varies depending on the temperature conditions, but is preferably 5 minutes or less, and the purpose of the heat treatment after sputtering can be achieved even in about 1 minute.

The orientation control layer 4 is a layer that controls the orientation of the piezoelectric thin film layer laminated on the layer, and contains Pb, O, and Ti as constituent atoms. The material of the orientation control layer 4 is not particularly limited, but preferably contains at least Pb and / or an organometallic oxide containing Ti. In particular, it is more preferably a composite organometallic oxide of Pb and Ti. When the lead zirconate titanate (PZT) is laminated as a piezoelectric thin film on the upper portion, the orientation control layer 4 also has an effect of suppressing the diffusion of Pb to the lower portion due to the temperature load at the time of film formation. Further, it also has an effect of suppressing the diffusion of Ti in the lower intermediate layer into the upper piezoelectric thin film layer due to a temperature load.

Examples of the method for producing the orientation control layer 4 include a metalorganic vapor phase growth method (MOCVD (Metal Organic Chemical Vapor Deposition) method) and a sol-gel method. Among them, the sol-gel method is preferable because it is the cheapest and the orientation control layer can be easily formed. In the sol-gel method, first, a coating liquid containing a hydrolyzable compound of each component metal as a raw material, a partially hydrolyzable compound thereof, or a partially polycondensable compound (orientation control layer material) thereof is prepared. The prepared coating liquid is applied onto the substrate, and the coating liquid is dried to form the coating liquid.

Examples of the raw material for producing the orientation control layer material include organometallic compounds. For example, metal complexes such as lead or titanium alkoxides, organic acid salts, and β-diketone complexes are typical examples. As for the metal complex, various other complexes such as an amine complex can be used. Examples of the β-diketone for forming the β-diketone complex include acetylacetone (= 2,4-pentanedione) and heptafluorobutanoyl pivaloylmethane (= 1- (heptafluoropropyl) -4,4-dimethyl-). 1,3-Pentanedione), dipivaloylmethane (= 2,2,6,6-tetramethyl-3,5-heptandione), trifluoroacetylacetone, benzoylacetone and the like can be mentioned.

Examples of the lead compound include organic acid salts such as lead acetate and organometallic alkoxides such as diisopropoxy lead. As the titanium compound, organometallic alkoxides such as tetraethoxytitanium, tetraisopropoxytitanium, tetran-butoxytitanium, tetraisobutoxytitanium, tetratert-butoxytitanium, and dimethoxydiisopropoxytitanium are preferable, but organometallic acid salts or organic salts are preferable. Metal complexes can also be used.

The coating liquid is a precursor of lead titanate, which is an orientation control layer material, by dissolving or dispersing each of the above-mentioned raw material organometallic compounds in an appropriate organic solvent, for example, heat-treating, and further hydrolyzing. A compound containing, for example, a composite organometallic oxide of Pb and Ti is prepared. The composite organometallic oxide includes an organic substance containing Pb and an organic substance containing Ti. The ratio of Pb and Ti in the orientation control layer material is preferably 1/1 or more and 1.8 / 1 or less, and more preferably 1.2 / 1 or more and 1.5 / 1 or less.

Further, the organic solvent used for preparing the coating liquid is appropriately selected from various known solvents in consideration of dispersibility and coatability. Examples of the organic solvent used for preparing the coating liquid include alcohol solvents such as methanol, ethanol, n-butanol, n-propanol and isopropanol, ether solvents such as tetrahydrofuran and 1,4-dioxane, methyl cellosolve and ethyl cellosolve. Examples thereof include cellosolve-based solvents, amide-based solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone-based solvents, and nitrile-based solvents such as acetonitrile. Among these, it is preferable to use an alcohol solvent.

The amount of the organic solvent in the coating liquid is not particularly limited, but it is preferable to adjust the amount of the organic solvent so that the metal solid content concentration is 15% by mass or more and 30% by mass or less.

As a coating method of the coating liquid, a known coating method such as spin coating, dip coating, bar coating, and spray coating can be used. Further, when applying the coating liquid on the substrate, it is preferable that the surface to be coated with the coating liquid on the substrate is arranged in the horizontal direction (direction orthogonal to the vertical direction). Thereby, a coating layer having a uniform film thickness and a uniform distribution of the orientation control layer material can be obtained. The coating liquid may be applied only once or multiple times.

In the drying step after the step of forming the coating layer, the organic solvent is evaporated from the coating layer in a windless environment to obtain an orientation control layer. This step may be performed at a drying temperature suitable for the organic solvent used, and is usually at a temperature of 50 ° C. or higher, preferably 100 ° C. or higher. The drying temperature is 450 ° C. or lower, preferably 300 ° C. or lower. Moreover, the drying time is preferably less than 30 minutes. In particular, in this embodiment, it is carried out under the condition that the formula (1) described later is satisfied. This step is performed by placing the substrate in a heat source such as a dryer, hot plate, tube furnace, or electric furnace, or by bringing the substrate into direct contact with a heat source such as a dryer, hot plate, tube furnace, or electric furnace. Can be done. Among these, a hot plate that heats from the back surface of the substrate is preferable from the viewpoint of uniformity of heating temperature.

The step of forming the orientation control layer (dry coating layer) is performed so that the surface (coated surface) coated with the coating liquid of the substrate is in a windless environment. Specifically, the coated surface is not provided with an air supply port for supplying hot air or hot air, or an exhaust port for exhausting air. In addition, when the air supply port and the exhaust port are provided, the flow of vaporized organic solvent and hot air on the substrate is prevented. As a result, the flow velocity of the gas is set to 0.05 m / s or less at a position of 20 cm on the surface on which the coating liquid is applied on the substrate.

The film thickness of the orientation control layer 4 after drying in this way is preferably 10 nm or more and 100 nm or less. If it is 10 nm or more, the effect of controlling the orientation and the effect of suppressing diffusion can be sufficiently obtained, and if it is 100 nm or less, the characteristics of the piezoelectric thin film are not adversely affected.

According to the study by the present inventors, the surface state of the orientation control layer changes depending on the drying conditions for forming the orientation control layer, and even if raw materials having the same composition ratio are used, the piezoelectric thin film formed on the same composition ratio ( 100) It was found that the degree of orientation of the surface changes. In particular, it has been found that a high degree of orientation of the (100) plane of the piezoelectric thin film can be obtained when the Ti in the Pb, O, and Ti elements on the surface of the orientation control layer is 14.88 atomic% or less. The Ti element ratio on the surface of the orientation control layer is more preferably 14.8 atomic% or less.

Further, the method for manufacturing a substrate for forming a piezoelectric material according to the second embodiment is a step of forming an intermediate layer containing at least one of Ti and TiO ₂ on a base substrate layer containing at least SiO ₂ or SiN on the surface. At least a step of forming an electrode layer containing Pt on the intermediate layer and a step of forming an orientation control layer containing Pb and Ti on the surface of the electrode are included in the step of forming the orientation control layer. The present invention relates to a method for manufacturing a substrate for forming a piezoelectric material, wherein the temperature T (° C.) and the time t (minutes) applied to the substrate for the piezoelectric body satisfy the following formula (1).

（但し ５０≦Ｔ≦４５０， ０＜ｔ＜３０ ）
上記式（１）を満足することで配向制御層の表面におけるＰｂ、Ｏ、Ｔｉ元素中の該Ｔｉを１４．８８原子％以下とすることができる。

(However, 50 ≤ T ≤ 450, 0 <t <30)
By satisfying the above formula (1), the Ti in the Pb, O, and Ti elements on the surface of the orientation control layer can be adjusted to 14.88 atomic% or less.

2. 2. Piezoelectric Substrate Next, the piezoelectric substrate according to the third embodiment of the present invention will be described. The piezoelectric substrate of this embodiment is formed by forming a piezoelectric thin film on the electrode layer 3 shown in FIG. 1 or on the orientation control layer 4 shown in FIG. The orientation control layer becomes lead titanate when the piezoelectric thin film is fired, and functions as a part of the piezoelectric thin film. The piezoelectric substrate is formed into a piezoelectric element by providing an electrode (also referred to as an upper electrode) facing the electrode layer 3 (also referred to as a lower electrode) via a piezoelectric thin film. A piezoelectric element is an element that converts a force applied to a piezoelectric body into a voltage or a voltage into a force by the piezoelectric effect, but in the present invention, it is particularly used as an element (actuator) that converts a voltage into a force. Is preferable. The upper electrode may be formed on the entire surface of the piezoelectric thin film or may be formed on a part of the piezoelectric thin film. Further, the upper electrode may be formed integrally with the piezoelectric substrate, or may be detachable. The material of the upper electrode can be used without particular limitation as long as it is a conductive material capable of applying a voltage to the piezoelectric thin film, and the same material as the material of the lower electrode can be used.
Further, each wiring layer to the upper and lower electrodes of the piezoelectric element may be formed on the piezoelectric substrate. For example, each wiring layer can be formed in the same layer as the lower electrode by using the lower electrode material. .. In this case, the upper electrode can be connected to the wiring layer via a through hole, a lead-out electrode, or the like.

The material of the piezoelectric thin film is not particularly limited, but preferably contains lead zirconate titanate (PZT). As the PZT, a perovskite type crystal represented by the general formula Pb _{(1.00 to 1.20)} (Zr _x Ti _1-x ) O ₃ (x is 0.4 to 0.6) is preferable. By setting the composition of Zr and Ti in the above range, a perovskite crystal having high piezoelectricity can be obtained.
A trace amount of elements other than Pb, Zr, and Ti may be doped into the piezoelectric thin film. Specific examples of elements that can be used as dopants when doping are La, Ca, Sr, Ba, Sn, Th, Y, Sm, Ce, Bi, Sb, Nb, Ta, W, Mo, Cr. , Co, Ni, Fe, Cu, Si, Ge, Sc, Mg, Mn and the like. The addition amount is preferably 0.1% by mass to 2% by mass of Pb _{(1.00 to 1.20)} (Zr _x Ti _1-x ) O ₃ (x is 0.4 to 0.6).

Examples of the method for producing the piezoelectric thin film include a sputtering method, a metalorganic vapor phase growth method (MOCVD (Metal Organic Chemical Vapor Deposition) method), and a sol-gel method. Among them, the sol-gel method is preferable because it is the cheapest and can easily form a piezoelectric thin film. In the sol-gel method, first, a coating liquid containing a hydrolyzable compound of each component metal as a raw material, a partially hydrolyzable compound thereof, or a partially polycondensable compound (piezoelectric precursor) thereof is prepared. As the doping element, a compound containing these elements may be added at the time of preparing the coating liquid. The prepared coating liquid is applied onto the substrate, and the coating liquid is dried to form a coating layer. After that, the coating layer is heated in air and further fired at a temperature equal to or higher than the crystallization temperature to crystallize the piezoelectric thin film.
As a method similar to the sol-gel method, there is an organometallic decomposition method (MOD (Metal Organic Deposition) method). In the MOD method, a coating liquid containing a thermally decomposable organometallic compound (metal complex and metal organic acid salt) as a piezoelectric precursor, for example, a metal β-diketone complex or a carboxylate is applied onto a substrate. To work. Next, for example, the coating liquid is heated in air or oxygen to cause evaporation of the solvent in the coating liquid and thermal decomposition of the organic metal compound, and further crystallized by firing at a crystallization temperature or higher. This is a method of forming a piezoelectric thin film by crystallization.
In the present specification, the above-mentioned sol-gel method, MOD method, and a method combining these methods are collectively referred to as a "sol-gel method".

3. 3. Method for Manufacturing Piezoelectric Thin Film Next, the method for manufacturing the piezoelectric thin film of the present embodiment will be described below. The manufacturing method of the present embodiment includes a coating layer forming step, a drying coating layer forming step, and a drying coating layer heating step. Hereinafter, each step will be described.
In addition, in this specification, a "coating layer" represents a layer composed of a coating liquid coated on a substrate before the organic solvent evaporates. Further, the "dry coating layer" represents a coating layer after the organic solvent has evaporated.

(1) Coating layer forming step In the coating layer forming step, a coating liquid containing an organic solvent and a piezoelectric precursor is applied onto a substrate for forming a piezoelectric thin film. In this way, a substrate on which a coating layer containing an organic solvent and a piezoelectric precursor is formed is prepared. Examples of the piezoelectric precursor include hydrolyzable compounds of each component metal, partially hydrolyzable compounds thereof, partially polycondensable compounds thereof, thermally decomposable compounds, and raw materials for these compounds. Examples of the raw material for producing these compounds include organometallic compounds. For example, metal complexes such as alkoxides, organic acid salts, and β-diketone complexes of the above metals are typical examples. As for the metal complex, various other complexes such as an amine complex can be used. Examples of the β-diketone for forming the β-diketone complex include acetylacetone (= 2,4-pentanedione) and heptafluorobutanoyl pivaloylmethane (= 1- (heptafluoropropyl) -4,4-dimethyl-). 1,3-Pentanedione), dipivaloylmethane (= 2,2,6,6-tetramethyl-3,5-heptandione), trifluoroacetylacetone, benzoylacetone and the like can be mentioned.

Specific examples of the organometallic compound suitable as a raw material include organic acid salts such as lead acetate and organometallic alkoxides such as diisopropoxylead as lead compounds. As the titanium compound, organometallic alkoxides such as tetraethoxytitanium, tetraisopropoxytitanium, tetran-butoxytitanium, tetraisobutoxytitanium, tetratert-butoxytitanium, and dimethoxydiisopropoxytitanium are preferable, but organometallic acid salts or organic salts are preferable. Metal complexes can also be used. As for the zirconium compound, an organometallic alkoxide, an organic acid salt, or an organometallic complex of zirconium can be used as in the case of the lead compound and the titanium compound. Similar to the above can be used for other metal compounds, but the present invention is not limited thereto. Further, the above metal compounds may be used in combination. The organometallic compound may be a composite organometallic compound containing two or more kinds of component metals in addition to the compound containing one kind of metal as described above.

The coating liquid is a composite organometallic oxide (composite organometallic oxide) which is a piezoelectric precursor by dissolving or dispersing each of the above-mentioned raw material organometallic compounds in an appropriate organic solvent, for example, heat-treating, and further hydrolyzing. Prepare one containing (containing two or more kinds of component metals).

Further, the organic solvent used for preparing the coating liquid is appropriately selected from various known solvents in consideration of dispersibility and coatability. Examples of the organic solvent used for preparing the coating liquid include alcohol solvents such as methanol, ethanol, n-butanol, n-propanol and isopropanol, ether solvents such as tetrahydrofuran and 1,4-dioxane, methyl cellosolve and ethyl cellosolve. Examples thereof include cellosolve-based solvents, amide-based solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone-based solvents, and nitrile-based solvents such as acetonitrile. Among these, it is preferable to use an alcohol solvent.
The amount of the organic solvent in the coating liquid is not particularly limited, but it is preferable to adjust the amount of the organic solvent so that the metal solid content concentration is 15% by mass or more and 30% by mass or less. When the amount of the organic solvent in the coating liquid is within these ranges, the layer thickness of the piezoelectric thin film in one coating can be easily set to 150 nm or more and 400 nm or less.

When a plurality of organometallic compounds are used, the ratio of each organometallic compound in the coating liquid is determined by the material of the piezoelectric thin film to be manufactured, for example, Pb _{(1.00 to 1.20)} (Zr _x Ti _{1- ). It} is preferable that the composition ratio of _x ) O ₃ (x is 0.4 to 0.6) is almost the same as that of the composition ratio. When forming a piezoelectric thin film composed of Pb _{(1.00 to 1.20)} (Zr _x Ti _1-x ) O ₃ (x is 0.4 to 0.6), lead compounds are generally volatile. It is expensive and lead loss may occur due to evaporation during the heat treatment process described below. Therefore, in anticipation of this deficiency, lead may be present in a slightly excessive amount, for example, 2 mol% or more and 40 mol% or less with respect to the required amount of lead in terms of composition ratio. The degree of lead deficiency varies depending on the type of lead compound and film formation conditions, and can be determined experimentally.

In the coating liquid, as stabilizers, 1,8-diazabicyclo [5.4.0] -7-undecene (hereinafter, may be referred to as "DBU"), 1,5-diazabicyclo [4.3]. .0] Non-5-ene (hereinafter sometimes referred to as "DBN") and 1,4-diazabicyclo [2.2.2] octane (hereinafter sometimes referred to as "DABCO") can be added. In addition, β-diketones (for example, acetylacetone, heptafluorobutanoylpivaloylmethane, dipivaloylmethane, trifluoroacetylacetone, benzoylacetone, etc.) and ketone acids conventionally used as other stabilizers. (For example, acetoacetic acid, propionyl acetic acid, benzoyl acetic acid, etc.), lower alkyl esters such as ethyl, propyl, butyl of these ketone acids, oxy acids (for example, lactic acid, glycolic acid, α-oxybutyric acid, salicylic acid, etc.), Lower alkyl esters of these oxy acids, oxyketones (eg, diacetone alcohol, acetoin, etc.), α-amino acids (eg, glycine, alanine, etc.), alkanolamines (eg, diethanolamine, triethanolamine, monoethanol). Amino acid) and the like may be used in combination.

The amount of the stabilizer in the coating liquid is preferably 0.05 times or more and 5 times or less, and 0.1 times or more and 1.5 times or less of the total number of moles of metal atoms. More preferably.

In the coating process, for example, the coating liquid is applied onto the electrodes of the substrate having the electrodes on the surface. As a coating method of the coating liquid, a known coating method such as spin coating, dip coating, bar coating, and spray coating can be used. Further, when applying the coating liquid on the substrate, it is preferable that the surface to be coated with the coating liquid on the substrate is arranged in the horizontal direction (direction orthogonal to the vertical direction). Thereby, a coating layer having a uniform film thickness and a uniform distribution of the piezoelectric precursor can be obtained. The coating liquid may be applied only once or multiple times.
The film thickness of the piezoelectric thin film (piezoelectric thin film after production) obtained by applying the coating liquid once is not particularly limited, but is preferably 150 nm or more and 400 nm or less. When the film thickness of the piezoelectric thin film is 150 nm or more, it is possible to manufacture a piezoelectric thin film having excellent piezoelectric characteristics with a small number of coatings. Further, when the thickness of the piezoelectric thin film is 400 nm or less, epitaxial crystal growth in the layer thickness direction can be effectively performed.

The film thickness of the piezoelectric thin film can be controlled by changing the concentration of the piezoelectric precursor in the coating liquid and the coating conditions, and these conditions can be obtained from experiments. For example, a coating liquid having a solid content concentration of 20% by mass or more and 25% by mass or less is applied by a spin coating method at 2000 rpm, and the coating liquid is dried and the piezoelectric precursor is heat-treated. As a result, a piezoelectric thin film having a film thickness of 200 nm or more and 330 nm or less can be formed for each coating. The film thickness of the piezoelectric body (including the orientation control layer) finally formed is preferably 4 μm or less.

(2) Dry coating layer forming step In the drying coating layer forming step after the coating layer forming step, the organic solvent is evaporated from the coating layer in a windless environment to dry including the piezoelectric precursor. Obtain a coating layer. This step may be performed at a drying temperature suitable for the organic solvent used, and is usually at a temperature of 50 ° C. or higher, preferably 100 ° C. or higher and 450 ° C. or lower. This step is performed by placing the substrate in a heat source such as a dryer, hot plate, tube furnace, or electric furnace, or by bringing the substrate into direct contact with a heat source such as a dryer, hot plate, tube furnace, or electric furnace. Can be done. Among these, a hot plate that heats from the back surface of the substrate is preferable from the viewpoint of uniformity of heating temperature.
The process of forming the dry coating layer is performed so that the surface (coated surface) of the substrate coated with the coating liquid is in a windless environment. Specifically, the coated surface is not provided with an air supply port for supplying hot air or hot air, or an exhaust port for exhausting air. In addition, when providing an air supply port and an exhaust port, prevent the flow of organic solvent and hot air on the substrate. As a result, the flow velocity of the gas is set to 0.05 m / s or less at a position of 20 cm on the surface on which the coating liquid is applied on the substrate.

(3) Heating step of the dry coating layer After the formation of the dry coating layer, in the heating step of the dry coating layer, the dry coating layer is heated and the piezoelectric precursor contained in the dry coating layer is used as a piezoelectric material. To form a thin film. This step can be performed by placing the substrate in a heat source such as a dryer, hot plate, tube furnace, electric furnace, or by bringing these heat sources into contact with the substrate. At this time, heating is preferably performed at 500 ° C. or higher and 800 ° C. or lower. The heating step of the dry coating layer may be divided into a plurality of times, or may be performed only once. Preferably, the piezoelectric thin film is formed by heating the dry coating layer by tentative firing and then firing and crystallizing the dry coating layer at a temperature equal to or higher than the crystallization temperature thereof.

4. Piezoelectric Thin Film Manufacturing Equipment The piezoelectric thin film manufacturing equipment includes a coating means, a drying means, and a heating means. As a coating means, it is possible to form a coating layer by coating a coating liquid containing an organic solvent and a piezoelectric precursor on a substrate. The substrate is designed to be mounted on the mounting portion. As a drying means, it is possible to evaporate an organic solvent from the coating layer in a windless environment to obtain a dry coating layer containing a piezoelectric precursor. The heating means can heat the dry coating layer to form a piezoelectric thin film from the piezoelectric precursor contained in the dry coating layer.

5. Orientation evaluation method Next, a method for evaluating the orientation of the (100) plane of the piezoelectric thin film will be described. The orientation state of the (100) plane of the piezoelectric thin film can be easily confirmed from the detection angle and intensity of the diffraction peak in the X-ray diffraction measurement by the 2θ / θ method using Cu Kα rays for the wavelength, which is generally used for the crystalline thin film. .. For example, as shown in FIG. 6, in the diffraction chart obtained from the piezoelectric thin film of the present embodiment, the (100) plane has a peak intensity near 22 °, and the (110) plane has a peak intensity near 31 °. 111) The planes have peak intensities around 38 °. The ratio of the intensity of the (100) plane can be obtained by dividing the peak intensity of the (100) plane by the sum of the peak intensities of the (100) plane, the (110) plane, and the (111) plane.
Since good piezoelectricity can be obtained, the ratio of the strength of the (100) plane to the sum of the peak strengths of the (100) plane, the (110) plane, and the (111) plane is 80% or more in each part of the substrate. Preferably, 90% or more is more preferable. Further, it is preferable that the main surface of the substrate and the (100) surface of the piezoelectric thin film are parallel to each other.

6. Element quantitative analysis method Next, an element quantitative analysis method for the surface of a thin film will be described. In the present invention, an X-ray photoelectron spectroscopy (XPS) analyzer of ULVAC-PHI Co., Ltd. Auantera SXM is used, and analysis software (MultiPak Version 9.3.0.3) is used, and Japanese Patent Application Laid-Open No. 7-35711 The element amount (atomic%) is calculated using the relative sensitivity coefficient method described.
(Measurement condition)
X-ray source: Monochromatic AlKα
X-ray output: 25W15kV
X-ray beam diameter: 100 μm
Photoelectron extraction angle: 45 °
The element quantitative analysis method for the thin film surface is not limited to XPS, and analysis methods such as fluorescent X-ray (XRF) analysis and high-frequency glow discharge emission surface analysis (GDS) can be used in addition to XPS. ..

In the present specification, "the absence of Ti by the elemental quantitative analysis method" means that, for example, the Ti2p peak is not detected in the region where the binding energy is 450 nm or more and less than 470 nm by XPS. Further, "the Ti in the Pb, O, and Ti elements on the surface of the orientation control layer is 14.88 atomic% or less" means that, for example, the amount of Ti element obtained by elemental quantitative analysis by XPS is Pb. It means that the value divided by the total amount of elements of O and Ti is 14.88% or less. Here, the elemental amount of Ti on the surface of the orientation control layer is calculated from the spectrum corresponding to the Ti2p orbital of XPS, the elemental amount of Pb is calculated from the spectrum corresponding to the Pb4f orbital, and the elemental amount of O is calculated from the spectrum corresponding to the O1s orbital. You can do things.

7. Liquid Discharge Heads FIGS. 3 to 5 show a liquid discharge head according to an embodiment using a piezoelectric substrate. The liquid discharge head M is composed of a liquid discharge head substrate 21, a plurality of liquid discharge ports 22, a plurality of pressure chambers 23, and an actuator 25 arranged so as to correspond to each pressure chamber 23. ing. Each pressure chamber 23 is provided corresponding to each liquid discharge port 22 and communicates with the liquid discharge port 22. The actuator 25 causes a change in the volume of ink in the pressure chamber 23 due to its vibration, and ejects droplets of ink or the like from the liquid ejection port 22. The liquid discharge port 22 is formed on the nozzle plate 24 at a predetermined interval, and the pressure chamber 23 is formed on the liquid discharge head substrate 21 in parallel so as to correspond to the liquid discharge port 22. In the present embodiment, the liquid discharge port 22 is provided on the surface facing the pressure generating surface of the actuator 25, but it may be provided on a surface other than the surface facing the pressure generating surface of the actuator 25. Each actuator 25 is composed of a diaphragm 26 and a piezoelectric element 30, and the piezoelectric element 30 is composed of a piezoelectric thin film 27 and a pair of electrodes (lower electrode 28 and upper electrode 29). An opening 21A corresponding to each pressure chamber 23 is formed on the upper surface of the liquid discharge head substrate 21, and each actuator 25 is arranged so as to close the opening. FIG. 5 shows a configuration in which the diaphragm 26 is exposed at the opening. However, if the liquid in the pressure chamber 23 can be discharged from the liquid discharge port 22 by the vibration generated by the actuator 25, the discharge liquid discharge head A part of the board 21 may remain. Note that FIG. 3 shows a state in which the nozzle plate 24 is separated and deployed from the liquid discharge head substrate 21 for the sake of explanation, and the nozzle plate 24 is actually mounted on the liquid discharge head substrate 21 as shown in FIG. It is joined.
The material of the diaphragm 26 is not particularly limited, but semiconductors such as Si, metals, metal oxides, glass and the like exemplified as the material of the base substrate layer are preferable. The liquid discharge head substrate 21 and the diaphragm 26 may be formed by joining or adhering, or the diaphragm 26 may be formed directly on the liquid discharge head substrate 21. Further, the lower electrode 28 and the piezoelectric thin film 30 may be formed directly on the liquid discharge head substrate 21 without providing the diaphragm 26. In that case,

In the actuator to which the present invention is applied, the diaphragm 26 corresponds to the base substrate, the base substrate layer 2 containing SiO ₂ or SiN is formed on the surface, and the intermediate layer 3 is formed on the base substrate layer. When the intermediate layer has conductivity, it forms a part of the lower electrode 28. Further, when the orientation control layer is formed on the lower electrode and the piezoelectric thin film is formed on the lower electrode, the orientation control layer is also fired at the final stage of forming the piezoelectric thin film to form a part of the piezoelectric thin film. Become.

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

(Manufacturing of lead zirconate titanate (PZT) coating liquid)
As a coating liquid for forming the piezoelectric thin film, a PZT coating liquid having a metal composition represented by Pb / Zr / Ti = 1.2 / 0.52 / 0.48 was prepared as follows.
1.2 mol of lead acetate hydrate was dehydrated by heating, and 1.2 mol of 1,8-diazabicyclo [5.4.0] -7-undecene and 1-methoxy-2-propanol (9. 0 mol) is mixed and heated and stirred to react. Then, 0.52 mol of tetra n-butoxyzirconium and 0.48 mol of tetraisopropoxytitanium were added and further heated to react, and the metal compounds were composited with each other. Next, water (5.0 mol) and ethanol (5.0 mol) were added and a hydrolysis reaction was carried out to obtain a piezoelectric precursor composed of an organometallic oxide. At that time, acetic acid (3.8 mol) and acetylacetone (0.6 mol) were added. After that, the solvent having a boiling point of 100 ° C. or lower is completely removed by a rotary evaporator, and diethylene glycol monoethyl ether (organic solvent) is added to adjust the concentration so that the concentration of the metal oxide converted into the above composition formula becomes 23% by mass. Then, a PZT coating solution was prepared.

[Example 1]
A silica (SiO ₂ ) layer of 500 nm is provided on the surface of a silicon substrate having a diameter of 6 inches (15 cm) by thermal oxidation as a base substrate layer 1, and Ti is 50 nm as an intermediate layer 2 and Pt is 200 nm as an electrode layer 3 by sputtering. , And used as a substrate for forming a piezoelectric material used in this embodiment (see FIG. 1). As annealing after sputtering, heat treatment was performed by the following method.
The above-mentioned substrate for forming a piezoelectric film is placed on a hot plate heated to 150 ° C. (“Shamal Hot Plate HHP-411” manufactured by AS ONE Corporation, the temperature unevenness of the plate surface is 150 ° C ± 1 ° C) for 1 minute, and the substrate is placed. Was heated. At this time, the hot plate was installed in a windless environment (wind speed 0 m / s) (measured at a position 2 cm above the substrate; an anemometer DT-8880 manufactured by CEM was used), and no shielding plate was provided.

[Example 2, Comparative Examples 1 to 3]
In Example 1, a substrate for forming a piezoelectric film was produced in the same step except that the surface temperature and heating time of the hot plate were changed to the conditions shown in Table 1.

The tops of the piezoelectric film forming substrates prepared in Examples 1 and 2 and Comparative Examples 1 and 3 were evaluated as follows. The piezoelectric film-forming substrate was divided into nine sheets as shown in FIG. 7, and when Ti was detected and detected on the Pt electrode surface of each piezoelectric film-forming substrate, the amount ratio was measured by XPS analysis. .. Here, the Ti amount ratio is calculated by dividing the atomic% calculated from the peak corresponding to the Ti2p orbital by the sum of the atomic% calculated from the peak corresponding to the Pt4f orbital and the atomic% calculated from the peak corresponding to the Ti2p orbital. It is the average value of three XPS measurements. In FIG. 7, (5) is a portion from the center of the substrate to a radius of 3 cm, and (1), (2), (3), (4), (6), (7), (8), and (9) are. A portion having a radius of 3 cm or more and 6 cm or less from the center of the substrate was measured. The results are shown in Table 1. Further, the XPS spectrum in the fully bound energy region of Example 1 is shown in FIG. 8 (a), and the XPS spectrum of only the Ti2p region (450 nm to 470 nm) in which the Ti2p peak was not detected is shown in FIG. 8 (b). Further, FIG. 9 shows an XPS spectrum in which the Ti2p peak of the piezoelectric film-forming substrate produced in Comparative Example 1 was detected.

Next, the PZT coating solution prepared as described above was applied to the Pt surface of the substrate by a spin coater (4000 rpm for 15 seconds) (coating layer forming step). Next, a hot plate heated to 280 ° C. (“Shamal Hot Plate HHP-411” manufactured by AS ONE Corporation, temperature unevenness on the board surface was 280 ° C. ± 1 ° C.) was prepared. A substrate coated with the PZT coating liquid was placed on the hot plate for 5 minutes to evaporate the organic solvent in the PZT coating liquid (step of forming the dry coating layer). At this time, the hot plate was installed in a windless environment (wind speed 0 m / s) (measured at a position 2 cm above the substrate; an anemometer DT-8880 manufactured by CEM was used), and no shielding plate was provided. Put 10 minutes the piezoelectric deposition substrate in an electric furnace of 650 ° C., _the piezoelectric precursor was a piezoelectric thin film made of _{Pb 1.2 (Zr 0.52 Ti 0.48)} O 3. The heat treatment step of 10 minutes in the electric furnace at 650 ° C. corresponds to the heating step of the dry coating layer. Then, the X-ray diffraction (2θ / θ method) of each piezoelectric thin film was measured by an X-ray diffractometer (RINT2100 manufactured by Rigaku Co., Ltd.). FIG. 6 shows the X-ray diffraction pattern of Example 1 (5), and the peak seen near 40 ° in the figure is the peak of the (111) plane of Pt provided on the substrate.

From FIG. 6, the ratio of the intensity of the (100) plane is obtained by dividing the peak intensity value of the (100) plane of the piezoelectric thin film by the sum of the peak intensity values of the (100) plane, the (110) plane, and the (111) plane. (Orientation degree). Since the peak of the (200) plane seen near 44 ° is a crystal plane equivalent to the (100) plane, it is not included in the ratio of the intensity of the (100) plane. Table 1 shows the degree of orientation in the (100) plane of Examples 1 and 2 and Comparative Examples 1 to 3.

As shown in Table 1, it was clarified that when Ti was not detected on the Pt electrode, a high (100) plane orientation of 90% or more was obtained. In particular, it has become possible to form a piezoelectric thin film having a high degree of plane orientation (100) without forming a layer that controls the orientation of the piezoelectric thin film.

[Example 3]
(Manufacturing of orientation control layer coating liquid)
A coating liquid for an orientation control layer having a metal composition represented by Pb / Ti = 1.2 / 1.0 was prepared as follows.
1.2 mol of lead acetate hydrate was dehydrated by heating, and 1.2 mol of 1,8-diazabicyclo [5.4.0] -7-undecene and 1-methoxy-2-propanol (9. 0 mol) is mixed and heated and stirred to react. Then, 1.0 mol of tetraisopropoxytitanium was added and further heated to react, and the metal compounds were composited with each other. Next, water (5.0 mol) and ethanol (5.0 mol) were added and a hydrolysis reaction was carried out to obtain an orientation control layer material composed of an organometallic oxide. At that time, acetic acid (3.8 mol) and acetylacetone (0.6 mol) were added. Then, the solvent having a boiling point of 100 ° C. or lower is removed with a rotary evaporator, diethylene glycol monoethyl ether (organic solvent) is added, and the solid content concentration is such that the concentration converted to lead titanate in the above metal composition becomes 1.0% by mass. Was adjusted to prepare a coating solution for the orientation control layer.

The coating liquid of the orientation control layer prepared as described above was applied to the Pt surface of the piezoelectric film forming substrate by a spin coater (2000 rpm) in 15 seconds (coating layer forming step). Next, a hot plate heated to 130 ° C. (“Shamal Hot Plate HHP-411” manufactured by AS ONE Corporation, temperature unevenness on the board surface was 130 ° C. ± 1 ° C.) was prepared. A substrate coated with the coating liquid was placed on the hot plate for 1 minute to evaporate the organic solvent in the coating liquid (step of forming a dry coating layer). At this time, the hot plate was installed in a windless environment (wind speed 0 m / s) (measured at a position 2 cm above the substrate; an anemometer DT-8880 manufactured by CEM was used), and no shielding plate was provided.

[Examples 4 to 11, Comparative Examples 4 to 9]
In Example 3, a substrate for forming a piezoelectric material was produced in the same steps except that the steps for forming the dry coating layer were the drying temperature and the drying time shown in Table 2.

The tops of the piezoelectric film-forming substrates prepared in Examples 3 to 11 and Comparative Examples 4 to 9 were evaluated as follows. The piezoelectric film forming substrate was divided into nine sheets as shown in FIG. 7, and the Ti amount ratio on the surface of each orientation control layer was measured using XPS. Here, the Ti amount ratio (atomic%) is defined as the element amount calculated from the peak corresponding to the Ti2p orbit, the element amount calculated from the peak corresponding to the Pb4f orbit, the element amount calculated from the peak corresponding to the Ti2p orbit, and the O1s orbit. It can be calculated by dividing by the sum of the amount of elements calculated from the corresponding peak, and is the value of the average of three measurements of XPS. The results are shown in Table 2.

Next, the PZT coating liquid prepared as described above was applied to the surface of each orientation control layer in the same manner as in Examples 1 and 2 and Comparative Examples 1 to 3, and dried, and X of each piezoelectric thin film was applied. The degree of orientation of the (100) plane was derived by measuring the line diffraction (2θ / θ method) with an X-ray diffractometer (RINT2100 manufactured by Rigaku Co., Ltd.) (see Table 2). Here, the environment such as no wind on the hot plate and the shielding plate is the same as in Examples 1 and 2 and Comparative Examples 1 to 3. FIG. 10 shows the relationship between the Ti amount ratio in atomic% and the (100) plane orientation (%) of PZT derived by the above method. When the Ti amount ratio on the surface of the orientation control layer is 14.88 atomic%, the (100) plane orientation of PZT changes critically, and when it is 14.88 atomic% or less, the (100) plane orientation of PZT is high. There was found.

(Heating process conditions when forming the orientation control layer)
The degree of orientation of the (100) plane of the piezoelectric thin film varies depending on the heating process conditions (drying temperature and drying time) when forming the orientation control layer, and the smaller the heat load, the better the degree of orientation of the (100) plane (100). See Table 2). From FIG. 10 and Table 2, the drying temperature T (° C.) and the drying time t (minutes) of the preferable orientation control layer can be defined by the following formula (1).

（但し ５０≦Ｔ≦４５０， ０＜ｔ＜３０ ）

(However, 50 ≤ T ≤ 450, 0 <t <30)

Equation (1) is assumed to be an arithmetic progression with temperature in 10 ° C increments and time in 1 minute increments from the experimental data points of orientation (T = 200,280 ° C., t = 1,5,10 minutes). Then, the degree of orientation under each temperature / time condition is calculated. The critical point of the degree of orientation shown in FIG. 10 is set to 85%, and the boundary condition (temperature, time) point is derived. The relational expression between temperature and time is T = A × t ^ (-B) + C
The coefficients of A, B, and C were calculated and derived from the boundary condition points obtained above and the least squares fitting of this relational expression.

Here, the drying temperature and drying time conditions of the orientation control layers of Examples 3 to 11 showing the high (100) plane orientation of the piezoelectric thin film satisfy the formula (1). None of Comparative Examples 4 to 8 satisfy the formula (1). It was confirmed that the Ti amount ratio on the surface of the orientation control layer can be reduced to 14.88 atomic% or less by satisfying the formula (1).

1 Base substrate 2 Intermediate layer 3 Electrode layer 4 Orientation control layer 21 Liquid ejection head substrate 21A Opening 22 Ink ejection port 23 Pressure chamber 24 Nozzle plate 25 Actuator 26 Vibration plate 27 Piezoelectric thin film 28 Lower electrode 29 Upper electrode 30 Piezoelectric element

Claims (8)

A base substrate layer containing at least SiO ₂ on its surface,
And an intermediate layer comprising a T i on the lower ground substrate layer,
An electrode layer containing Pt on the intermediate layer and
It has an orientation control layer on the electrode layer and
Ti was not detected on the surface of the electrode layer before the formation of the orientation control layer by the elemental quantitative analysis method .
The orientation control layer contains Pb, O and Ti, and the Ti in the Pb, O and Ti elements on the surface of the orientation control layer is 13.87 atomic% or more and 14.88 atomic% or less. Piezoelectric film forming substrate. The orientation control layer, a piezoelectric film substrate according to claim 1 further comprising an organic substance containing Pb. The substrate for forming a piezoelectric material according to claim 1 or 2 , wherein the orientation control layer contains an organic substance containing Ti. A piezoelectric substrate comprising the piezoelectric film-forming substrate according to any one of claims 1 to 3 and a piezoelectric material provided on the surface of the piezoelectric film-forming substrate. The piezoelectric substrate according to claim 4 , wherein the piezoelectric body is PZT (lead zirconate titanate). A liquid discharge head having the piezoelectric substrate according to claim 4 or 5 . A coating liquid containing a piezoelectric precursor and an organic solvent is applied to the surface of the piezoelectric film forming substrate according to any one of claims 1 to 3 , and the coating liquid is dried and applied. It is characterized by having a step of forming a layer, a step of drying the coating layer to form a dry coating layer, and a step of firing the dry coating layer to form a thin film of a piezoelectric material. A method for manufacturing a piezoelectric substrate. The piezoelectric material according to claim 7, wherein the piezoelectric precursor is a thermally decomposable composite organometallic oxide prepared from an organometallic compound containing Pb, an organometallic compound containing Zr, and an organometallic compound containing Ti. Substrate manufacturing method.

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