Liquid discharge head and method for manufacturing liquid discharge head

Abstract

To prevent the occurrence of cracks in a vibration plate even when the vibration plate is made thicker.SOLUTION: A liquid discharge head comprises a piezoelectric element, a vibration plate that vibrates in response to actuation of the piezoelectric element, and a pressure chamber substrate in which a pressure chamber is formed to apply pressure to liquid through the vibration of the vibration plate. The vibration plate includes, in order along the stacking direction from the pressure chamber substrate to the piezoelectric element, a first layer containing silicon as a constituent element, a second layer, and a third layer containing zirconium as a constituent element. The material constituting the second layer has a lower Young's modulus than the material constituting the third layer.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a liquid ejection head and a method for manufacturing a liquid ejection head. [Background technology]

[0002] A liquid ejection head used in a device such as a piezoelectric inkjet printer generally includes a piezoelectric element and a diaphragm that vibrates when driven by the piezoelectric element. For example, Patent Document 1 discloses a diaphragm in which an elastic film made of silicon dioxide (SiO2) and an insulating layer made of zirconium oxide (ZrO2) are laminated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-78407 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration described in Patent Document 1, there is room for improvement in the configuration of the diaphragm from the viewpoint of suppressing cracks in the diaphragm. [Means for solving the problem]

[0005] In order to solve the above problems, one embodiment of the liquid ejection head of the present disclosure is a liquid ejection head of a first embodiment of the present disclosure comprising a piezoelectric element, a vibration plate that vibrates when driven by the piezoelectric element, and a pressure chamber substrate in which a pressure chamber is provided that applies pressure to liquid by vibration of the vibration plate, the vibration plate having, in this order along a stacking direction that is a direction from the pressure chamber substrate toward the piezoelectric element, a first layer containing silicon as a constituent element, a second layer, and a third layer containing zirconium as a constituent element, and the Young's modulus of the material constituting the second layer is lower than the Young's modulus of the material constituting the third layer.

[0006] One aspect of the method for manufacturing a liquid ejection head disclosed herein is a method for manufacturing a liquid ejection head including a piezoelectric element, a vibration plate that vibrates when driven by the piezoelectric element, and a pressure chamber substrate in which a pressure chamber is provided that applies pressure to liquid by vibration of the vibration plate, wherein the process for forming the vibration plate includes a first step of forming a first layer containing silicon as a constituent element, a second step of forming a second layer on the first layer, and a third step of forming a third layer containing zirconium as a constituent element on the second layer. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a configuration diagram that illustrates a liquid ejection device including a liquid ejection head according to a first embodiment. [Diagram 2] FIG. 1 is an exploded perspective view of a liquid ejection head according to a first embodiment. [Diagram 3] 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 2 is a plan view showing a part of the liquid ejection head according to the first embodiment. [Diagram 5] 5 is a cross-sectional view taken along line BB in FIG. [Figure 6] 4 is a flowchart of a method for manufacturing the liquid ejection head according to the first embodiment. [Figure 7] 5A to 5C are diagrams illustrating a method for manufacturing the liquid ejection head according to the first embodiment. [Figure 8] FIG. 11 is a cross-sectional view of a liquid ejection head according to a second embodiment. [Figure 9] FIG. 11 is a cross-sectional view of a liquid ejection head according to a third embodiment. [Figure 10] FIG. 11 is a cross-sectional view of a liquid ejection head according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the dimensions and scale of each part in the drawings may differ from the actual dimensions, and some parts are shown diagrammatically to facilitate understanding. In addition, the scope of the present disclosure is not limited to these forms unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0009] In the following description, the mutually intersecting X-axis, Y-axis, and Z-axis are used as appropriate. In the following description, one direction along the X-axis is the X1 direction, and the direction opposite the X1 direction is the X2 direction. Similarly, the opposite directions along the Y-axis are the Y1 direction and the Y2 direction. In addition, the opposite directions along the Z-axis are the Z1 direction and the Z2 direction. The Z1 direction is an example of a "stacking direction." In addition, viewing in a direction along the Z-axis is sometimes called a "planar view."

[0010] Typically, the Z axis is the vertical axis, and the Z2 direction corresponds to the vertical downward direction. However, the Z axis does not have to be the vertical axis. Also, the X axis, the Y axis, and the Z axis are typically perpendicular to each other, but are not limited to this, and may intersect at an angle within a range of 80° to 100°.

[0011] 1. Embodiment 1-1. Overall configuration of the liquid ejection device 1 is a schematic diagram showing a configuration of a liquid ejection device 100 including a liquid ejection head 50 according to a first embodiment. The liquid ejection device 100 is an inkjet printing device that ejects ink, which is an example of a "liquid," as droplets onto a medium M. The medium M is typically printing paper. Note that the medium M is not limited to printing paper, and may be a printing target made of any material, such as a resin film or fabric.

[0012] As shown in FIG. 1, the liquid ejection device 100 includes a liquid container 10, a control unit 20, a transport mechanism 30, a moving mechanism 40, and a liquid ejection head 50.

[0013] The liquid container 10 is a container that stores ink. Specific examples of the liquid container 10 include a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack made of a flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the liquid container 10 is not particularly limited and may be any type.

[0014] The control unit 20 includes, for example, a processing circuit such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and a storage circuit such as a semiconductor memory, and controls the operation of each element of the liquid ejection device 100. Here, the control unit 20 controls the driving of the liquid ejection head 50.

[0015] The transport mechanism 30 transports the medium M in the Y2 direction under the control of the control unit 20. The movement mechanism 40 reciprocates the liquid ejection head 50 in the X1 direction and the X2 direction under the control of the control unit 20. In the example shown in FIG. 1, the movement mechanism 40 has a substantially box-shaped carriage 41 that houses the liquid ejection head 50, and a transport belt 42 to which the carriage 41 is fixed. Note that the number of liquid ejection heads 50 mounted on the carriage 41 is not limited to one, and may be multiple. In addition to the liquid ejection head 50, the above-mentioned liquid container 10 may be mounted on the carriage 41.

[0016] Under the control of the control unit 20, the liquid ejection head 50 ejects ink supplied from the liquid container 10 from each of a plurality of nozzles onto the medium M in the Z2 direction. This ejection is performed in parallel with the transport of the medium M by the transport mechanism 30 and the reciprocating movement of the liquid ejection head 50 by the movement mechanism 40, thereby forming an ink image on the surface of the medium M. The configuration and manufacturing method of the liquid ejection head 50 will be described in detail later.

[0017] 1-2. Overall configuration of liquid ejection head Fig. 2 is an exploded perspective view of a liquid ejection head 50 according to the first embodiment. Fig. 3 is a cross-sectional view taken along line AA in Fig. 2. As shown in Fig. 2 and Fig. 3, the liquid ejection head 50 has a flow path substrate 51, a pressure chamber substrate 52, a nozzle plate 53, a vibration absorber 54, a vibration plate 55, a plurality of piezoelectric elements 56, a sealing plate 57, a case 58, and a wiring substrate 59.

[0018] A pressure chamber substrate 52, a vibration plate 55, a plurality of piezoelectric elements 56, a case 58, and a sealing plate 57 are disposed in an area located in the Z1 direction from the flow path substrate 51. On the other hand, a nozzle plate 53 and a vibration absorber 54 are disposed in an area located in the Z2 direction from the flow path substrate 51. Each element of the liquid ejection head 50 is roughly a plate-like member that is elongated in the direction along the Y axis, and is joined to one another by, for example, an adhesive.

[0019] As shown in FIG. 2, the nozzle plate 53 is a plate-like member provided with a plurality of nozzles N arranged in a direction along the Y axis. Each nozzle N is a through hole that allows ink to pass through. In this manner, the nozzle plate 53 has a plurality of nozzles N that eject ink. The nozzle plate 53 is manufactured by processing a silicon single crystal substrate by a semiconductor manufacturing technique that uses a processing technique such as dry etching or wet etching. However, other known methods and materials may be used as appropriate to manufacture the nozzle plate 53.

[0020] The flow path substrate 51 is a plate-like member for forming an ink flow path. As shown in FIG. 2 and FIG. 3, the flow path substrate 51 is provided with an opening R1, a plurality of supply flow paths Ra, and a plurality of communication flow paths Na. The opening R1 is an elongated through hole extending in a direction along the Y axis in a plan view seen in a direction along the Z axis so as to be continuous across a plurality of nozzles N. On the other hand, each of the supply flow paths Ra and the communication flow paths Na is a through hole provided individually for each nozzle N. Each of the plurality of supply flow paths Ra communicates with the opening R1. The flow path substrate 51 is manufactured by processing a silicon single crystal substrate by, for example, a semiconductor manufacturing technique, in the same manner as the nozzle plate 53 described above. However, other known methods and materials may be appropriately used for manufacturing the flow path substrate 51.

[0021] The pressure chamber substrate 52 is a plate-like member in which a plurality of pressure chambers C corresponding to a plurality of nozzles N are provided. The pressure chambers C are located between the flow path substrate 51 and the vibration plate 55, and are spaces called cavities for applying pressure to the ink filled in the pressure chambers C. The pressure chambers C apply pressure to the ink by the vibration of the vibration plate 55. The plurality of pressure chambers C are arranged in a direction along the Y axis. Each pressure chamber C is formed of a hole 52a opening on both sides of the pressure chamber substrate 52, and has an elongated shape extending in a direction along the X axis. In this manner, the pressure chamber substrate 52 has a plurality of pressure chambers C communicating with the nozzles N. The end of each pressure chamber C in the X2 direction communicates with the corresponding supply flow path Ra. On the other hand, the end of each pressure chamber C in the X1 direction communicates with the corresponding communication flow path Na. The pressure chamber substrate 52 is manufactured, for example, by processing a silicon single crystal substrate by semiconductor manufacturing technology, similar to the nozzle plate 53 described above. However, each of the pressure chamber substrates 52 may be manufactured using other known methods and materials as appropriate.

[0022] A vibration plate 55 is disposed on the surface facing the Z1 direction of the pressure chamber substrate 52. The vibration plate 55 is an elastically deformable plate-like member, and vibrates when driven by the piezoelectric element 56. Details of the vibration plate 55 will be described later with reference to FIG.

[0023] A piezoelectric element 56 is disposed on the surface of the vibration plate 55 facing the Z1 direction. The piezoelectric element 56 is a passive element that deforms when a drive signal is supplied, and has an elongated shape extending in the direction along the X axis. One piezoelectric element 56 is provided for each pressure chamber, and the multiple piezoelectric elements 56 are arranged in the direction along the Y axis so as to correspond to the multiple pressure chambers C. When the vibration plate 55 vibrates in conjunction with the deformation of the piezoelectric element 56, the pressure in the pressure chamber C fluctuates, and ink is ejected from the nozzle N. Details of the piezoelectric element 56 will be described later with reference to FIGS. 4 and 5.

[0024] The case 58 is a case for storing ink to be supplied to the multiple pressure chambers C, and is bonded to the surface of the flow path substrate 51 facing the Z1 direction with an adhesive or the like. The case 58 is made of, for example, a resin material, and is manufactured by injection molding. The case 58 is provided with a storage section R2 and an inlet IH. The storage section R2 is a recessed portion whose outer shape corresponds to the opening R1 of the flow path substrate 51. The inlet IH is a through hole that communicates with the storage section R2. The space formed by the opening R1 and the storage section R2 functions as a liquid storage chamber R, which is a reservoir that stores ink. Ink is supplied to the liquid storage chamber R from the liquid container 10 via the inlet IH.

[0025] The vibration absorber 54 is a member for absorbing pressure fluctuations in the liquid storage chamber R. The vibration absorber 54 is, for example, a compliance substrate that is a flexible sheet member that can be elastically deformed. Here, the vibration absorber 54 is disposed on a surface of the flow path substrate 51 facing the Z2 direction so as to close the opening R1 and the multiple supply flow paths Ra of the flow path substrate 51 and form the bottom surface of the liquid storage chamber R.

[0026] The sealing plate 57 is a structure that protects the multiple piezoelectric elements 56 and reinforces the mechanical strength of the pressure chamber substrate 52 and the vibration plate 55. The sealing plate 57 is bonded to the surface of the vibration plate 55 by, for example, an adhesive. The sealing plate 57 has recesses that accommodate the multiple piezoelectric elements 56.

[0027] A wiring board 59 is bonded to the surface of the pressure chamber substrate 52 or the vibration plate 55 facing the Z1 direction. The wiring board 59 is a mounting component on which a plurality of wires for electrically connecting the control unit 20 and the liquid ejection head 50 are formed. The wiring board 59 is a flexible wiring board such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable). A drive circuit 60 for driving the piezoelectric elements 56 is mounted on the wiring board 59. The drive circuit 60 selectively supplies a drive signal for driving each piezoelectric element 56 to each piezoelectric element 56 via the wiring board 59.

[0028] 1-3. Diaphragm and piezoelectric element Fig. 4 is a plan view showing a part of the liquid ejection head 50 according to the first embodiment. Fig. 5 is a cross-sectional view taken along line BB in Fig. 4. Below, the vibration plate 55 and the piezoelectric element 56 will be described in detail with reference to Figs. 4 and 5, but prior to the description of the vibration plate 55 and the piezoelectric element 56, the pressure chamber substrate 52 will first be described.

[0029] As shown in Figs. 4 and 5, the pressure chamber substrate 52 is provided with holes 52a that form pressure chambers C. Accordingly, in the pressure chamber substrate 52, a wall-like partition 52b extending in the direction along the X-axis is provided between two adjacent holes 52a. The pressure chamber substrate 52 is manufactured, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology. In Fig. 4, the planar shape of the hole 52a when formed by anisotropic etching on a silicon single crystal substrate with a surface orientation (110) is shown by a dashed line. Note that the planar shape of the hole 52a is not limited to the example shown in Fig. 4 and may be any shape.

[0030] Here, the pressure chambers C are formed after the piezoelectric elements 56 are formed. The pressure chambers C are formed, for example, by anisotropically etching the surface of the silicon single crystal substrate after the piezoelectric elements 56 are formed, which is different from the surface on which the piezoelectric elements 56 are formed. At this time, for example, an aqueous potassium hydroxide solution (KOH) or the like is used as an etchant for the anisotropic etching. In addition, at this time, when the first layer 55a is made of silicon oxide, the first layer 55a functions as a stop layer for stopping the anisotropic etching. After the pressure chambers C are formed as described above, the flow path substrate 51 and the like are bonded to the pressure chamber substrate 52 by an adhesive. Note that after the piezoelectric elements 56 are formed, if necessary, the surface of the silicon single crystal substrate opposite the surface on which the piezoelectric elements 56 are formed is ground by CMP (chemical mechanical polishing) or the like to flatten the surface or adjust the thickness of the substrate.

[0031] As shown in Fig. 4, the piezoelectric element 56 overlaps the pressure chamber C in plan view. As shown in Fig. 5, the piezoelectric element 56 has a first electrode 56a, a piezoelectric layer 56b, and a second electrode 56c, which are laminated in this order in the Z1 direction. The piezoelectric element 56 may have electrodes and piezoelectric layers alternately laminated in multiple layers between the first electrode 56a and the second electrode 56c, and may expand and contract toward the vibration plate 55. Another layer, such as a layer for improving adhesion, may be appropriately interposed between the layers of the piezoelectric element 56 or between the piezoelectric element 56 and the vibration plate 55.

[0032] The first electrodes 56a are individual electrodes spaced apart from one another for each piezoelectric element 56. Specifically, a plurality of first electrodes 56a extending in the direction along the X-axis are arranged in the direction along the Y-axis at intervals from one another. A drive signal including a predetermined voltage pulse is supplied from the control unit 20 to the first electrodes 56a of each piezoelectric element 56.

[0033] The first electrode 56a has, for example, a layer made of iridium (Ir) and a layer made of titanium (Ti), which are laminated in this order in the Z1 direction. Here, iridium is an electrode material with excellent conductivity. For this reason, by using iridium as a constituent material of the first electrode 56a, it is possible to reduce the resistance of the first electrode 56a. In addition, when forming the piezoelectric layer 56b, the layer made of titanium controls the orientation of the piezoelectric layer 56b by using island-shaped Ti as crystal nuclei, thereby enhancing the crystallinity or orientation of the piezoelectric layer 56b. Note that instead of or in addition to the layer made of iridium, a layer made of another metal material may be provided.

[0034] 4 and 5, the piezoelectric layer 56b has a band shape extending in the direction along the Y-axis so as to be continuous across the multiple piezoelectric elements 56. In the example shown in FIG. 4, the piezoelectric layer 56b has through-holes 56b1 extending in the direction along the X-axis in regions corresponding to the gaps between adjacent pressure chambers C in a plan view. As a result, the piezoelectric layer 56b is provided individually for each piezoelectric element 56, as viewed in the cross section shown in FIG. 5. The piezoelectric layer 56b may be provided individually for each of the multiple piezoelectric elements 56.

[0035] The piezoelectric layer 56b is made of a second piezoelectric material having piezoelectricity. The second piezoelectric material is a piezoelectric material having a perovskite crystal structure represented by a general composition formula ABO3. Specifically, the material constituting the piezoelectric layer 56b is a piezoelectric material containing one or more elements selected from lead (Pb), titanium (Ti), zirconium (Zr), potassium (K), sodium (Na), niobium (Nb), barium (Ba), iron (Fe), bismuth (Bi), tantalum (Ta), chromium (Cr), iridium (Ir), hafnium (Hf), lithium (Li), carbon (C), and lanthanum (La). Examples of the piezoelectric material include, but are not limited to, barium titanate (BaTiO3), lead zirconate titanate (Pb(Zr,Ti)O3), and potassium sodium niobate ((K,Na)NbO3).

[0036] The second electrode 56c is a band-shaped common electrode that extends in the direction along the Y-axis so as to be continuous across the plurality of piezoelectric elements 56. A predetermined constant potential is supplied to the second electrode 56c.

[0037] The second electrode 56c is made of, for example, iridium (Ir). The material of the second electrode 56c is not limited to iridium, and may be, for example, a metal material such as titanium (Ti), platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), or copper (Cu). The second electrode 56c may be made of one of these metal materials alone, or may be made of two or more of these materials in a combination such as a laminate.

[0038] In the above-described piezoelectric element 56, when a voltage is applied between the first electrode 56a and the second electrode 56c, the piezoelectric layer 56b is deformed by the inverse piezoelectric effect. Here, a vibration plate 55 is bonded to the piezoelectric element 56, and the vibration plate 55 vibrates in accordance with the deformation of the piezoelectric layer 56b.

[0039] 5, the vibration plate 55 has a first layer 55a, a second layer 55b, and a third layer 55c, in this order, along a stacking direction DL that is a direction from the pressure chamber substrate 52 toward the piezoelectric element 56. In the example shown in Fig. 5, the stacking direction DL is the Z1 direction.

[0040] The first layer 55a is a layer containing silicon as a constituent element. More specifically, the first layer 55a is an insulating film composed of, for example, silicon oxide (SiO2). Note that the material constituting the first layer 55a is not limited to SiO2 as long as it contains silicon as a constituent element, and may be, for example, a simple substance, nitride, or oxynitride of silicon (Si), or may be a material containing, in addition to silicon (Si), one or more elements selected from titanium (Ti), aluminum (Al), tantalum (Ta), chromium (Cr), iridium (Ir), hafnium (Hf), zirconium (Zr), and carbon (C) as a constituent element in the form of a simple substance, oxide, nitride, or oxynitride.

[0041] The thickness t1 of the first layer 55a is determined according to the thickness t and width of the diaphragm 55, and is not particularly limited, but is within the range of 100 nm to 3000 nm.

[0042] The second layer 55b is a layer made of a material having a Young's modulus lower than that of the material making up the third layer 55c. For example, when the third layer 55c is made of zirconium oxide (ZrO2), since the Young's modulus of zirconium oxide (ZrO2) is 200 GPa, the Young's modulus of the material making up the second layer 55b is smaller than 200 GPa. By interposing such a second layer 55b between the first layer 55a and the third layer 55c, the rigidity of the diaphragm 55 can be reduced even if the thickness t of the diaphragm 55 is increased. As a result, cracks in the diaphragm 55 can be suppressed even if the thickness t of the diaphragm 55 is increased.

[0043] On the other hand, if the Young's modulus of the material constituting the second layer 55b is equal to or greater than the Young's modulus of the material constituting the third layer 55c, increasing the thickness t of the diaphragm 55 will result in excessive rigidity of the diaphragm 55, which will easily cause cracks in the diaphragm 55. For example, if the third layer 55c is made of zirconium oxide (ZrO2), and the second layer 55b is made of oxides such as titanium oxide (TiO2), aluminum oxide (Al2O3), and hafnium oxide (HfO2), or nitrides such as aluminum nitride (AlN), silicon nitride (Si3N4), and titanium nitride (TiN), the Young's modulus of the material constituting the second layer 55b will be equal to or greater than the Young's modulus of the material constituting the third layer 55c. The Young's modulus of titanium oxide is 300 GPa, the Young's modulus of aluminum oxide is 300 to 350 GPa, the Young's modulus of titanium oxide is 265 GPa, the Young's modulus of aluminum nitride is 340 to 350 GPa, the Young's modulus of silicon nitride is 280 to 300 GPa, and the Young's modulus of titanium nitride is 200 GPa.

[0044] Furthermore, in the case where second layer 55b is omitted, as in the case where the Young's modulus of the material constituting second layer 55b is equal to or greater than the Young's modulus of the material constituting third layer 55c, increasing the thickness t of diaphragm 55 makes diaphragm 55 too rigid, making diaphragm 55 more likely to crack.

[0045] The second layer 55b includes a first piezoelectric material, which is a piezoelectric material having piezoelectricity. This allows the second layer 55b to withstand the heat of a thermal oxidation process, even if the thermal oxidation process is performed when the third layer 55c is formed. When the third layer 55c is made of zirconium oxide (ZrO2), the third layer 55c is formed by forming a layer of zirconium on the second layer 55b and then oxidizing the layer under high heat conditions. Since the second layer 55b includes the first piezoelectric material, the second layer 55b can withstand the thermal oxidation.

[0046] In addition, since the second layer 55b contains the first piezoelectric material, there is an advantage that the Young's modulus of the material constituting the second layer 55b can be easily reduced. Furthermore, since the second layer 55b contains the first piezoelectric material, the second layer 55b can function as an adhesion layer that enhances adhesion between the first layer 55a and the third layer 55c.

[0047] The first piezoelectric material is a piezoelectric material having a perovskite crystal structure represented by the general composition formula ABO3, similar to the second piezoelectric material constituting the piezoelectric layer 56b described above. Specifically, the first piezoelectric material constituting the second layer 55b is a piezoelectric material containing one or more elements selected from the group consisting of lead (Pb), titanium (Ti), zirconium (Zr), potassium (K), sodium (Na), niobium (Nb), barium (Ba), iron (Fe), bismuth (Bi), tantalum (Ta), chromium (Cr), iridium (Ir), hafnium (Hf), lithium (Li), carbon (C), and lanthanum (La). More specifically, examples of the first piezoelectric material include, but are not limited to, lead titanate (PbTiO3), barium titanate (BaTiO3), lead zirconate titanate (Pb(Zr,Ti)O3), potassium sodium niobate ((K,Na)NbO3), etc. The Young's modulus of lead titanate (PbTiO3) is 132 GPa, the Young's modulus of barium titanate (BaTiO3) is 116 GPa, the Young's modulus of lead zirconate titanate (Pb(Zr,Ti)O3) is 58 to 73 GPa, and the Young's modulus of potassium sodium niobate ((K,Na)NbO3) is 100 to 130 GPa.

[0048] Note that "the second layer 55b includes a first piezoelectric material having piezoelectricity" includes a configuration in which the second layer 55b includes a piezoelectric material exhibiting piezoelectricity, as well as a configuration in which the second layer 55b includes a constituent element that constitutes a piezoelectric material exhibiting piezoelectricity. In other words, even if the second layer 55b does not exhibit piezoelectricity, if the second layer 55b includes a constituent element that constitutes a piezoelectric material, it is included in "the second layer 55b includes a first piezoelectric material having piezoelectricity."

[0049] The Young's modulus of the first piezoelectric material should be lower than that of the material constituting the third layer 55c. That is, the Young's modulus of the first piezoelectric material is preferably less than 200 GPa, and more preferably 132 GPa or less. For example, among the above-mentioned examples of the first piezoelectric material, it is preferable to use a material having a Young's modulus of 132 GPa or less, that is, lead titanate (PbTiO3), barium titanate (BaTiO3), lead zirconate titanate (Pb(Zr,Ti)O3), potassium sodium niobate ((K,Na)NbO3), etc. In this way, by having the Young's modulus of the first piezoelectric material be 132 GPa or less, the rigidity of the vibration plate 55 can be suitably reduced.

[0050] Among these, the first piezoelectric material is preferably lead zirconate titanate or potassium sodium niobate, in which case the Young's modulus of the first piezoelectric material can be made lower than in embodiments using other piezoelectric materials.

[0051] The first piezoelectric material used for the second layer 55b may be the same material as the second piezoelectric material used for the piezoelectric layer 56b, or may be a different material from the second piezoelectric material used for the piezoelectric layer 56b.

[0052] When the first piezoelectric material is different from the second piezoelectric material, the Young's modulus of the first piezoelectric material is preferably lower than that of the second piezoelectric material, which can more effectively suppress cracks in the vibration plate 55 than when the Young's modulus of the first piezoelectric material is equal to or greater than that of the second piezoelectric material.

[0053] On the other hand, when the first piezoelectric material is the same as the second piezoelectric material, i.e., when the piezoelectric element 56 has a piezoelectric layer 56b including the first piezoelectric material, the manufacturing process can be simplified by using the same piezoelectric material for the piezoelectric layer 56b and the second layer 55b.

[0054] The thickness t2 of the second layer 55b is determined according to the thickness t and width of the diaphragm 55, and is not particularly limited, but is within the range of 20 nm to 2000 nm.

[0055] The third layer 55c is a layer containing zirconium as a constituent element. More specifically, the third layer 55c is an elastic film made of, for example, zirconium oxide (ZrO2). Note that the material constituting the third layer 55c is not limited to ZrO2 as long as it contains zirconium as a constituent element, and may be, for example, a simple substance, nitride, or oxynitride of zirconium (Zr), or may be a material containing one or more elements selected from titanium (Ti), aluminum (Al), tantalum (Ta), chromium (Cr), and hafnium (Hf) as a constituent element in the form of a simple substance, oxide, nitride, or oxynitride in addition to zirconium (Zr).

[0056] The thickness t3 of the third layer 55c is preferably smaller than the sum of the thickness t1 of the first layer 55a and the thickness t2 of the second layer 55b. In this case, the Young's modulus of the entire diaphragm 55 can be made lower than in a case where the thickness t3 of the third layer 55c is equal to or greater than the sum of the thickness t1 of the first layer 55a and the thickness t2 of the second layer 55b.

[0057] The thickness t3 of the third layer 55c is determined according to the thickness t and width of the diaphragm 55, and is not particularly limited, but is within the range of 100 nm or more and 2000 nm or less, for example.

[0058] The thickness t of the diaphragm 55 is preferably 200 nm or more and 7000 nm or less, and more preferably 2000 μm or more and 5000 nm or less. When the thickness t is within such a range, the effect of the present disclosure becomes remarkable.

[0059] Moreover, the sum of the thickness t1 of the first layer 55a, the thickness t2 of the second layer 55b, and the thickness t3 of the third layer 55c is preferably greater than the thickness tp of the piezoelectric layer 56b. In other words, the thickness tp of the piezoelectric layer 56b is preferably smaller than the sum of the thickness t1 of the first layer 55a, the thickness t2 of the second layer 55b, and the thickness t3 of the third layer 55c. In this case, since the neutral axis of the vibration plate 55 is not located within the piezoelectric layer 56b, the deformation efficiency of the piezoelectric element 56 can be improved.

[0060] The above-described diaphragm 55 has a vibration area PV that vibrates when driven by the piezoelectric element 56. The vibration area PV is a part of the diaphragm 55, and is a portion that overlaps with the pressure chamber C in a plan view. In this embodiment, each of the first layer 55a, the second layer 55b, and the third layer 55c that configure the diaphragm 55 is provided across the entire vibration area PV when viewed along the Z-axis.

[0061] Here, the vibration region PV is divided into a first region RE1 and a second region RE2. The first region RE1 is a region that overlaps with the piezoelectric layer 56b in a planar view. The second region RE2 is a region that does not overlap with the piezoelectric layer 56b in a planar view. By having the second region RE2 in the vibration region PV, it is possible to increase the efficiency of deformation of the vibration region PV by the piezoelectric element 56 compared to an embodiment in which the vibration region PV is composed of only the first region RE1.

[0062] 5, the first region RE1 and the second region RE2 each include a first layer 55a, a second layer 55b, and a third layer 55c. The third layer 55c may not be present in the second region RE2. In this case, the second layer 55b may not be present in the second region RE2.

[0063] In this manner, the piezoelectric layer 56b is located inside the second layer 55b when the diaphragm 55 is viewed in plan view. This allows the second layer 55b to be provided over a wider area than the piezoelectric layer 56b, thereby making it possible to suitably suppress cracks in the diaphragm 55.

[0064] 1-4. Manufacturing method of liquid ejection head 6 is a flowchart of a method for manufacturing the liquid ejection head 50 according to the first embodiment. The method for manufacturing the liquid ejection head 50 includes a step S10 of forming a vibration plate 55 and a step S20 of forming a piezoelectric element 56, as shown in FIG.

[0065] Step S10 includes a first step S1 of forming a first layer 55a, a second step S2 of forming a second layer 55b, and a third step S3 of forming a third layer 55c.

[0066] Step S20 includes Step S4 of forming a first electrode 56a, Step S5 of forming a piezoelectric layer 56b, and Step S6 of forming a second electrode 56c.

[0067] Each step will be described in detail below with reference to FIG.

[0068] 7 is a diagram for explaining the manufacturing method of the liquid ejection head 50 according to the first embodiment. In Fig. 7, the transition of these steps is shown in the order of a first step S1, a second step S2, a third step S3, a step S4, a step S5, and a step S6 from the top to the bottom of the figure.

[0069] In the first step S1, a first layer 55a is formed on a substrate 520, such as a silicon single crystal substrate, for forming the pressure chamber substrate 52. For example, when the substrate 520 is a silicon single crystal substrate, the first layer 55a is formed by thermally oxidizing one surface of the substrate 520.

[0070] The method for forming the first layer 55a is not limited to thermal oxidation, and may be, for example, a CVD method or an atomic layer deposition (ALD) method.

[0071] In the second step S2, the second layer 55b is formed on the first layer 55a. For example, when the second layer 55b is made of a piezoelectric material, the second layer 55b is formed by forming a piezoelectric precursor layer on the first layer 55a by a sol-gel method, and then baking and crystallizing the precursor layer.

[0072] The method for forming the second layer 55b is not limited to thermal oxidation, and may be, for example, a CVD method or an atomic layer deposition (ALD) method.

[0073] In the third step S3, a third layer 55c is formed on the second layer 55b. For example, when the third layer 55c is made of zirconium oxide, the third layer 55c is formed by forming a zirconium layer on the second layer 55b by a film forming method such as a sputtering method, and then thermally oxidizing the layer. That is, the third step S3 includes a step S31 of forming a metal layer made of a metal such as zirconium, and a step S32 of thermally oxidizing the metal layer.

[0074] The method for forming the third layer 55c is not limited to thermal oxidation, and may be, for example, a CVD method or an atomic layer deposition (ALD) method.

[0075] The diaphragm 55 is obtained by step S10, which includes the first step S1, the second step S2, and the third step S3.

[0076] In step S4, the first electrode 56a is formed on the diaphragm 55. The first electrode 56a is formed by a known film formation technique such as sputtering, and a known processing technique using photolithography, etching, or the like.

[0077] In step S5, the piezoelectric layer 56b is formed on the first electrode 56a so as to cover the first electrode 56a. The piezoelectric layer 56b is formed, for example, by forming a precursor layer of a piezoelectric body by a sol-gel method, and then baking and crystallizing the precursor layer.

[0078] In step S6, a second electrode 56c is formed on the piezoelectric layer 56b so as to cover the piezoelectric layer 56b. The second electrode 56c is formed by a known film formation technique such as a sputtering method, and a known processing technique using photolithography, etching, etc., similar to the first electrode 56a.

[0079] In the above manufacturing method, since second layer 55b made of a material with a lower Young's modulus than the material making up third layer 55c is interposed between first layer 55a and third layer 55c, it is possible to reduce the rigidity of diaphragm 55 even if the thickness of diaphragm 55 is increased. As a result, it is possible to suppress cracks in diaphragm 55 even if the thickness of diaphragm 55 is increased.

[0080] As described above, the second layer 55b includes the first piezoelectric material having piezoelectricity. The third step S3 includes a step S32 of thermally oxidizing zirconium. In this manner, even if a thermal oxidation process is performed when forming the third layer 55c, the second layer 55b can withstand the heat of the thermal oxidation process.

[0081] As described above, in the liquid ejection head 50, the second layer 55b made of a material with a lower Young's modulus than the material making up the third layer 55c is interposed between the first layer 55a and the third layer 55c, so that even if the thickness t of the vibration plate 55 is increased, the rigidity of the vibration plate 55 can be reduced. As a result, even if the thickness t of the vibration plate 55 is increased, cracks in the vibration plate 55 can be suppressed.

[0082] 2. Second embodiment A second embodiment of the present disclosure will be described below. In the following example, for elements whose actions and functions are similar to those of the first embodiment, the reference numerals used in the description of the first embodiment will be used and detailed descriptions of each will be omitted as appropriate.

[0083] 8 is a cross-sectional view of a liquid ejection head 50A according to the second embodiment. The liquid ejection head 50A is configured similarly to the liquid ejection head 50 of the first embodiment, except that it includes a vibration plate 55A instead of the vibration plate 55 of the first embodiment. The vibration plate 55A is configured similarly to the vibration plate 55 of the first embodiment, except that a first intermediate layer 55d is added.

[0084] The first intermediate layer 55d is a layer interposed between the first layer 55a and the second layer 55b. That is, the vibration plate 55A has the first intermediate layer 55d between the first layer 55a and the second layer 55b in the stacking direction DL. The first intermediate layer 55d suppresses the elements constituting the first piezoelectric material from diffusing into the first layer 55a. This can reduce the formation of reinforced glass in the first piezoelectric material due to the reaction of an alkali metal or an alkaline earth metal with silicon contained in the first layer 55a. Therefore, even if the first piezoelectric material contains an alkali metal or an alkaline earth metal, it is possible to suppress cracks due to a decrease in strength of the vibration plate 55.

[0085] 8, the first intermediate layer 55d is provided in each of the first region RE1 and the second region RE2. This makes it possible to suppress the elements constituting the first piezoelectric material from diffusing into the first layer 55a in each of the first region RE1 and the second region RE2.

[0086] The material constituting the first intermediate layer 55d is, for example, an oxide or nitride of one or more elements selected from titanium (Ti), aluminum (Al), tantalum (Ta), chromium (Cr), hafnium (Hf), iron (Fe), yttrium (Y), and niobium (Nb).

[0087] The thickness t4 of the first intermediate layer 55d is preferably smaller than the thickness t2 of the second layer 55b, and specifically, is preferably 10 μm or more and 100 μm or less, which can suitably reduce the rigidity of the diaphragm 55A.

[0088] According to the second embodiment described above, even if the thickness t of the diaphragm 55A is increased, cracks in the diaphragm 55A can be suppressed.

[0089] 3. Third embodiment The third embodiment of the present disclosure will be described below. In the following exemplary embodiment, the elements having the same actions and functions as those in the first embodiment will be referred to by the same reference numerals used in the description of the first embodiment, and detailed descriptions thereof will be omitted as appropriate.

[0090] 9 is a cross-sectional view of a liquid ejection head 50B according to the third embodiment. The liquid ejection head 50B is configured similarly to the liquid ejection head 50 of the first embodiment, except that it includes a vibration plate 55B instead of the vibration plate 55 of the first embodiment. The vibration plate 55B is configured similarly to the vibration plate 55 of the first embodiment, except that a second intermediate layer 55e is added.

[0091] The second intermediate layer 55e is a layer interposed between the second layer 55b and the third layer 55c. That is, the vibration plate 55B has the second intermediate layer 55e between the second layer 55b and the third layer 55c. This can suppress the first piezoelectric material from diffusing into the third layer 55c and can increase the adhesion between the second layer 55b and the third layer 55c.

[0092] 9, the second intermediate layer 55e is provided in each of the first region RE1 and the second region RE2. This makes it possible to suppress the first piezoelectric material from diffusing into the third layer 55c in each of the first region RE1 and the second region RE2, and to increase the adhesion between the second layer 55b and the third layer 55c.

[0093] The material constituting the second intermediate layer 55e is, for example, an oxide or nitride of one or more elements selected from titanium (Ti), aluminum (Al), tantalum (Ta), chromium (Cr), hafnium (Hf), iron (Fe), yttrium (Y), and niobium (Nb).

[0094] The thickness t5 of the second intermediate layer 55e is preferably smaller than the thickness t2 of the second layer 55b, and specifically, is preferably 10 μm or more and 100 μm or less, which can suitably reduce the rigidity of the diaphragm 55A.

[0095] According to the third embodiment described above, even if the thickness t of the diaphragm 55B is increased, cracks in the diaphragm 55B can be suppressed.

[0096] 4. Fourth embodiment The fourth embodiment of the present disclosure will be described below. In the following exemplary embodiments, the elements having the same actions and functions as those in the first embodiment will be referred to by the same reference numerals used in the description of the first embodiment, and detailed descriptions thereof will be omitted as appropriate.

[0097] 10 is a cross-sectional view of a liquid ejection head 50C according to the fourth embodiment. The liquid ejection head 50C is configured similarly to the liquid ejection head 50 of the first embodiment, except that it includes a vibration plate 55C instead of the vibration plate 55 of the first embodiment. The vibration plate 55C is configured similarly to the vibration plate 55 of the first embodiment, except that a first intermediate layer 55d and a second intermediate layer 55e are added.

[0098] In the diaphragm 55C, the first intermediate layer 55d is a layer interposed between the first layer 55a and the second layer 55b, similar to the first intermediate layer 55d in the second embodiment. In the diaphragm 55C, the second intermediate layer 55e is a layer interposed between the second layer 55b and the third layer 55c, similar to the second intermediate layer 55e in the second embodiment. Note that the material constituting the first intermediate layer 55d and the material constituting the second intermediate layer 55e may be the same or different from each other.

[0099] According to the fourth embodiment described above, even if the thickness t of the diaphragm 55C is increased, cracks in the diaphragm 55C can be suppressed.

[0100] 5. Variations Each of the above-mentioned exemplary embodiments can be modified in various ways. Specific modified embodiments that can be applied to each of the above-mentioned embodiments are illustrated below. Note that two or more embodiments selected from the following exemplary embodiments can be appropriately combined as long as they are not contradictory to each other.

[0101] 5-1. Variation 1 In each of the above-described embodiments, an example is given in which the first electrode 56a is an individual electrode and the second electrode 56c is a common electrode, but this is not limited to this example, and the first electrode 56a may be a common electrode and the second electrode 56c may be an individual electrode. 5-2. Variation 2 In each of the embodiments described above, the piezoelectric layer 56b is provided in common to the multiple pressure chambers C, but this is not limiting, and the piezoelectric layer 56b may be divided for each pressure chamber C. In addition, both the first electrode 56a and the second electrode 56c may be individual electrodes.

[0102] 5-3. Variation 3 In each of the above-mentioned embodiments, a serial type liquid ejection device 100 in which a carriage 41 carrying a liquid ejection head 50 is moved back and forth is exemplified, but the present disclosure can also be applied to a line type liquid ejection device in which multiple nozzles N are distributed across the entire width of the medium M.

[0103] 5-4. Variation 4 The liquid ejection device 100 exemplified in each of the above-mentioned embodiments can be adopted in various devices such as facsimile machines and copy machines, in addition to devices dedicated to printing. However, the use of the liquid ejection device of the present disclosure is not limited to printing. For example, a liquid ejection device that ejects a solution of a color material is used as a manufacturing device that forms a color filter of a liquid crystal display device. Also, a liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device that forms wiring and electrodes of a wiring board.

[0104] 6. Summary of this disclosure The following is a summary of this disclosure.

[0105] (Additional Note 1) A liquid ejection head according to a first aspect of the present disclosure comprises a piezoelectric element, a vibration plate that vibrates when driven by the piezoelectric element, and a pressure chamber substrate in which a pressure chamber is provided that applies pressure to liquid by vibration of the vibration plate, the vibration plate having, in this order along a stacking direction that is a direction from the pressure chamber substrate toward the piezoelectric element, a first layer containing silicon as a constituent element, a second layer, and a third layer containing zirconium as a constituent element, and the Young's modulus of the material constituting the second layer is lower than the Young's modulus of the material constituting the third layer.

[0106] In the above embodiment, since the second layer, which is made of a material with a Young's modulus lower than that of the material of the third layer, is interposed between the first and third layers, the rigidity of the diaphragm can be reduced even if the thickness of the diaphragm is increased. As a result, cracks in the diaphragm can be suppressed even if the thickness of the diaphragm is increased.

[0107] (Note 2) In a second embodiment which is a preferred example of the first embodiment, the second layer includes a first piezoelectric material having piezoelectricity. In the above embodiment, even if a thermal oxidation treatment is performed when forming the third layer, the second layer can withstand the heat of the thermal oxidation treatment.

[0108] (Additional Note 3) In a third aspect which is a preferred example of the second aspect, the Young's modulus of the first piezoelectric material is 132 GPa or less. In the above aspect, the rigidity of the diaphragm can be suitably reduced.

[0109] (Note 4) In a fourth aspect which is a preferred example of the second or third aspect, the first piezoelectric material is lead zirconate titanate. In the above aspect, the Young's modulus of the first piezoelectric material can be made lower than in aspects using other piezoelectric materials.

[0110] (Note 5) In a fourth aspect which is a preferred example of the second or third aspect, the first piezoelectric material is potassium sodium niobate. In the above aspect, the Young's modulus of the first piezoelectric material can be made lower than in aspects using other piezoelectric materials.

[0111] (Note 6) In a sixth aspect, which is a preferred example of any one of the second to fifth aspects, the diaphragm has a first intermediate layer between the first layer and the second layer in the stacking direction, which suppresses diffusion of elements constituting the first piezoelectric material into the first layer. In the above aspect, even if the first piezoelectric material contains an alkali metal or an alkaline earth metal, it is possible to reduce the formation of reinforced glass by reacting with the first piezoelectric material contained in the first layer. Therefore, even if the first piezoelectric material contains an alkali metal or an alkaline earth metal, it is possible to suppress cracks due to a decrease in strength of the diaphragm.

[0112] (Note 7) In a seventh aspect, which is a preferred example of any one of the second to sixth aspects, the diaphragm has a second intermediate layer between the second layer and the third layer. In the above aspect, it is possible to suppress diffusion of the first piezoelectric material into the third layer and to increase adhesion between the second layer and the third layer.

[0113] (Note 8) In an eighth aspect, which is a preferred example of any one of the first to seventh aspects, the thickness of the third layer is smaller than the sum of the thickness of the first layer and the thickness of the second layer. In this aspect, the Young's modulus of the entire diaphragm can be made lower than in an aspect in which the thickness of the third layer is equal to or greater than the sum of the thickness of the first layer and the thickness of the second layer.

[0114] (Supplementary Note 9) In a ninth aspect which is a suitable example of any one of the first to eighth aspects, the thickness of the diaphragm is within a range of 2 μm to 10 μm. In the above aspect, the effect of the present disclosure becomes remarkable.

[0115] (Appendix 10) In a tenth aspect, which is a preferred example of any one of the second to ninth aspects, the piezoelectric element has a piezoelectric layer including a second piezoelectric material having piezoelectricity, and the Young's modulus of the first piezoelectric material is lower than that of the second piezoelectric material. In the above aspect, cracks in the vibration plate can be more suitably suppressed than in the aspect in which the Young's modulus of the first piezoelectric material is equal to or higher than that of the second piezoelectric material.

[0116] (Note 11) The piezoelectric element has a piezoelectric layer containing the first piezoelectric material. In the above aspect, the manufacturing process can be simplified by using the same piezoelectric material for the piezoelectric layer and the second layer.

[0117] (Note 12) In a twelfth aspect, which is a preferred example of any one of the first to eleventh aspects, the piezoelectric element has a piezoelectric layer having piezoelectricity, and the thickness of the piezoelectric layer is smaller than the sum of the thickness of the first layer, the thickness of the second layer, and the thickness of the third layer. In the above aspect, the neutral axis of the vibration plate is not located within the piezoelectric layer, so that the deformation efficiency of the piezoelectric element can be increased.

[0118] (Note 13) In a thirteenth aspect, which is a preferred example of any one of the first to twelfth aspects, the piezoelectric element has a piezoelectric layer having piezoelectricity, and when the diaphragm is viewed in plan, the piezoelectric layer is located inside the second layer. In the above aspect, the second layer is provided over a wider area than the piezoelectric layer, so that cracks in the diaphragm can be suitably suppressed.

[0119] (Appendix 14) A manufacturing method for a liquid ejection head that is a preferred example of the present disclosure is a manufacturing method for a liquid ejection head including a piezoelectric element, a vibration plate that vibrates when driven by the piezoelectric element, and a pressure chamber substrate in which a pressure chamber is provided that applies pressure to liquid by vibration of the vibration plate, wherein the process of forming the vibration plate includes a first step of forming a first layer containing silicon as a constituent element, a second step of forming a second layer on the first layer, and a third step of forming a third layer containing zirconium as a constituent element on the second layer.

[0120] In the above embodiment, since the second layer, which is made of a material with a Young's modulus lower than that of the material of the third layer, is interposed between the first and third layers, the rigidity of the diaphragm can be reduced even if the thickness of the diaphragm is increased. As a result, cracks in the diaphragm can be suppressed even if the thickness of the diaphragm is increased.

[0121] (Note 15) In a fifteenth aspect which is a preferred example of the fourteenth aspect, the second layer includes a first piezoelectric material having piezoelectricity, and the third step includes a step of thermally oxidizing zirconium. In the above aspect, even if a thermal oxidation treatment is performed when forming the third layer, it is possible to realize a second layer that can withstand the heat of the thermal oxidation treatment. [Explanation of symbols]

[0122] 10...liquid container, 20...control unit, 30...transport mechanism, 40...movement mechanism, 41...carriage, 42...transport belt, 50...liquid ejection head, 50A...liquid ejection head, 50B...liquid ejection head, 50C...liquid ejection head, 51...flow path substrate, 52...pressure chamber substrate, 52a...hole, 52b...partition wall, 53...nozzle plate, 54...vibration absorber, 55...diaphragm, 55A...diaphragm, 55B...diaphragm, 55C...diaphragm, 55a...first layer, 55b...second layer, 55c...third layer, 55d...first intermediate layer, 55e...second intermediate layer, 56...piezoelectric element, 56a...first electrode, 56b...piezoelectric layer, 56b1...through hole, 56c... Second electrode, 57...sealing plate, 58...case, 59...wiring board, 60...driving circuit, 100...liquid ejection device, 520...substrate, C...pressure chamber, DL...stacking direction, IH...inlet, M...medium, N...nozzle, Na...communicating flow path, PV...vibration area, R...liquid storage chamber, R1...opening, R2...accommodation section, RE1...first area, RE2...second area, Ra...supply flow path, S1...first process, S2...second process, S3...third process, S31...process, S32...process, S4...process, S5...process, S6...process, S10...process, S20...process, t...thickness, t1...thickness, t2...thickness, t3...thickness, t4...thickness, t5...thickness, tp...thickness.

Claims

1. A piezoelectric element; a vibration plate that vibrates when driven by the piezoelectric element; a pressure chamber substrate in which a pressure chamber is provided that applies pressure to a liquid by vibration of the vibration plate; The vibration plate is arranged along a lamination direction, which is a direction from the pressure chamber substrate toward the piezoelectric element. A first layer including silicon as a constituent element; A second layer; and a third layer containing zirconium as a constituent element, The Young's modulus of the material constituting the second layer is lower than the Young's modulus of the material constituting the third layer. A liquid ejection head comprising:

2. the second layer includes a first piezoelectric material having piezoelectric properties; 2. The liquid ejection head according to claim 1.

3. The Young's modulus of the first piezoelectric material is 132 GPa or less.

3. The liquid ejection head according to claim 2.

4. the first piezoelectric material is lead zirconate titanate; 4. The liquid ejection head according to claim 3.

5. the first piezoelectric material is potassium sodium niobate; 4. The liquid ejection head according to claim 3.

6. the vibration plate has a first intermediate layer between the first layer and the second layer in the stacking direction, the first intermediate layer suppressing diffusion of elements constituting the first piezoelectric material into the first layer; 6. The liquid ejection head according to claim 2, wherein the liquid ejection head is a liquid ejection head.

7. The diaphragm has a second intermediate layer between the second layer and the third layer.

6. The liquid ejection head according to claim 2, wherein the liquid ejection head is a liquid ejection head.

8. The thickness of the third layer is less than the sum of the thickness of the first layer and the thickness of the second layer.

6. The liquid ejection head according to claim 2, wherein the liquid ejection head is a liquid ejection head.

9. The thickness of the diaphragm is in the range of 2 μm to 10 μm.

6. The liquid ejection head according to claim 2, wherein the liquid ejection head is a liquid ejection head.

10. the piezoelectric element has a piezoelectric layer including a second piezoelectric material having piezoelectric properties; The Young's modulus of the first piezoelectric material is lower than the Young's modulus of the second piezoelectric material.

6. The liquid ejection head according to claim 2, wherein the liquid ejection head is a liquid ejection head.

11. the piezoelectric element has a piezoelectric layer including the first piezoelectric material; 6. The liquid ejection head according to claim 2, wherein the liquid ejection head is a liquid ejection head.

12. The piezoelectric element has a piezoelectric layer having piezoelectricity, a thickness of the piezoelectric layer is less than a sum of a thickness of the first layer, a thickness of the second layer, and a thickness of the third layer; 6. The liquid ejection head according to claim 2, wherein the liquid ejection head is a liquid ejection head.

13. The piezoelectric element has a piezoelectric layer having piezoelectricity, When the vibration plate is viewed in plan, the piezoelectric layer is located inside the second layer.

6. The liquid ejection head according to claim 2, wherein the liquid ejection head is a liquid ejection head.

14. A method for manufacturing a liquid ejection head including a piezoelectric element, a vibration plate that vibrates when driven by the piezoelectric element, and a pressure chamber substrate provided with a pressure chamber that applies pressure to liquid by vibration of the vibration plate, comprising: In the step of forming the diaphragm, A first step of forming a first layer containing silicon as a constituent element; a second step of forming a second layer on the first layer; and a third step of forming a third layer containing zirconium as a constituent element on the second layer. A method for manufacturing a liquid ejection head comprising the steps of:

15. the second layer includes a first piezoelectric material having piezoelectric properties; The third step includes a step of thermally oxidizing zirconium. The method for manufacturing a liquid ejection head according to claim 14 .

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