Piezoelectric device and liquid ejecting head

Abstract

This invention provides a piezoelectric device and a liquid jet head for suppressing the intrusion of moisture into the interior of a vibrating plate and for preventing damage such as interlayer delamination or cracking of the vibrating plate. The piezoelectric device comprises: a substrate having a recess; a vibrating plate; and a piezoelectric actuator. The vibrating plate has: a first layer comprising silicon as a constituent element; a second layer disposed between the first layer and the piezoelectric actuator, comprising at least one metal element selected from chromium, titanium, aluminum, tantalum, hafnium, and iridium, and any one or two of silicon nitride as a constituent element; a third layer disposed between the second layer and the piezoelectric actuator, comprising zirconium as a constituent element; and a fourth layer on the piezoelectric actuator side of the third layer, comprising at least one metal element selected from chromium, titanium, aluminum, tantalum, hafnium, and iridium, and any one or two of silicon nitride as a constituent element.

Description

Technical Field

[0001] The present invention relates to a piezoelectric device and a liquid jet head having a vibrating plate disposed on a substrate and a piezoelectric actuator. Background Technology

[0002] As a liquid ejector head for electronic devices, an inkjet recording head is known. The inkjet recording head includes: a substrate having a pressure chamber communicating with a nozzle; a vibrating plate disposed on one side of the substrate; and a piezoelectric vibrator disposed on the vibrating plate. The ink in the pressure chamber is pressure-changed by the piezoelectric actuator, causing ink droplets to be ejected from the nozzle. For example, Patent Document 1 discloses a vibrating plate having an elastic film made of silicon dioxide and an insulating film made of zirconium oxide. Here, the elastic film is formed by thermally oxidizing one side of a monocrystalline silicon substrate. The insulating film is formed by thermally oxidizing a layer of zirconium monomers formed on the elastic film using a sputtering method or the like.

[0003] When moisture penetrates the vibrating plate, it can cause the zirconium oxide to become embrittled, resulting in damage such as delamination or cracks between the elastic membrane and the insulating membrane.

[0004] Especially in high temperature and high humidity environments, moisture can penetrate into the vibrating plate from the interface between the elastic membrane and the insulating membrane on the end face of the piezoelectric actuator, the interface between the second electrode and the insulating membrane on the end face of the piezoelectric actuator, and the surface of the second electrode on the opposite side of the piezoelectric actuator substrate.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-78407 Summary of the Invention

[0006] The present invention addresses the aforementioned problems by providing a piezoelectric device, characterized by comprising: a substrate having a recess; a vibrating plate; and a piezoelectric actuator, wherein the substrate, the vibrating plate, and the piezoelectric actuator are sequentially laminated along a first direction, the vibrating plate having: a first layer comprising silicon as a constituent element; a second layer disposed between the first layer and the piezoelectric actuator, comprising, as a constituent element, at least one metal element selected from chromium, titanium, aluminum, tantalum, hafnium, and iridium, and any one or two of silicon nitride; a third layer disposed between the second layer and the piezoelectric actuator, comprising zirconium as a constituent element; and a fourth layer on the piezoelectric actuator side of the third layer, the fourth layer comprising, as a constituent element, at least one metal element selected from chromium, titanium, aluminum, tantalum, hafnium, and iridium, and any one or two of silicon nitride.

[0007] Furthermore, another aspect of the present invention relates to a liquid jet head, characterized by comprising: a piezoelectric actuator; a vibrating plate that vibrates by being driven by the piezoelectric actuator; a flow channel forming substrate having a pressure chamber provided thereon, which applies pressure to the liquid by the vibration of the vibrating plate, wherein the flow channel forming substrate, the vibrating plate, and the piezoelectric actuator are sequentially laminated along a first direction, the vibrating plate having: a first layer comprising silicon as a constituent element; a second layer disposed between the first layer and the piezoelectric actuator and comprising, as a constituent element, at least one metal element selected from chromium, titanium, aluminum, tantalum, hafnium, and iridium, and any one or two of silicon nitride; a third layer disposed between the second layer and the piezoelectric actuator and comprising zirconium as a constituent element; and a fourth layer having a fourth layer on the piezoelectric actuator side of the third layer, the fourth layer comprising, as a constituent element, at least one metal element selected from chromium, titanium, aluminum, tantalum, hafnium, and iridium, and any one or two of silicon nitride.

[0008] Furthermore, another aspect of the present invention lies in a liquid injection device, characterized in that it comprises a liquid injection head as described above. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the inkjet recording device according to Embodiment 1.

[0010] Figure 2 This is an exploded perspective view of the recording head according to Embodiment 1.

[0011] Figure 3 This is a top view of the channel forming substrate of the recording head according to Embodiment 1.

[0012] Figure 4 This is a cross-sectional view of the recording head according to Embodiment 1.

[0013] Figure 5 This is a cross-sectional view of the recording head according to Embodiment 1.

[0014] Figure 6 This diagram illustrates the manufacturing method of the piezoelectric device according to Embodiment 1.

[0015] Figure 7 This is a cross-sectional view of the recording head according to Embodiment 2.

[0016] Figure 8 This is a STEM image of sample 1.

[0017] Figure 9 This is a STEM image of sample 2.

[0018] Figure 10 This is a STEM image of sample 3.

[0019] Figure 11 A graph showing the analytical results of sample 1 obtained by SIMS.

[0020] Figure 12 A graph showing the analytical results of sample 2 obtained by SIMS.

[0021] Figure 13 A graph showing the analytical results of sample 3 obtained by SIMS.

[0022] Figure 14 A graph showing the analytical results obtained from RBS for sample 4.

[0023] Figure 15 A graph showing the analytical results of sample 6 obtained by SIMS.

[0024] Figure 16 This is a sectional view of Comparative Example 1.

[0025] Figure 17 This is a cross-sectional view of Comparative Example 2.

[0026] Figure 18 This is a sectional view of Comparative Example 3.

[0027] Figure 19 This is a sectional view of Comparative Example 4.

[0028] Figure 20 A graph showing the results of leakage current.

[0029] Figure 21 This is a cross-sectional view showing a variation of Embodiment 1.

[0030] Figure 22 This is a cross-sectional view showing a variation of Embodiment 1. Detailed Implementation

[0031] The present invention will now be described in detail based on embodiments. However, the following description is merely an illustration of one aspect of the invention and can be modified freely within the scope of the invention. Components marked with the same symbol in the various figures represent the same component, and descriptions are appropriately omitted. Furthermore, in the various figures, X, Y, and Z represent three mutually orthogonal spatial axes. In this specification, the directions along these axes will be defined as the X direction, Y direction, and Z direction. The direction in which the arrow marks in each figure point will be defined as the positive (+) direction, and the opposite direction of the arrow marks will be defined as the negative (-) direction. Furthermore, the three spatial axes X, Y, and Z, for which no positive or negative directions are defined, will be described as the X-axis, Y-axis, and Z-axis. Furthermore, in the various embodiments below, as an example, the "first direction" will be defined as the -Z direction, and the "second direction" will be defined as the +Z direction. Furthermore, the view taken along the Z-axis will be referred to as a "top view".

[0032] Here, typically, the Z-axis is a vertical axis, and the +Z direction is equivalent to the downward direction of the vertical direction. However, the Z-axis does not have to be a vertical axis. Furthermore, although the X-axis, Y-axis, and Z-axis are typically orthogonal to each other, they are not limited to this; for example, they can intersect at an angle between 80° and 100°.

[0033] Implementation Method 1

[0034] Figure 1 The figure illustrates an inkjet recording device 1 as an example of a liquid jetting device according to Embodiment 1 of the present invention.

[0035] like Figure 1 As shown, an inkjet recording device 1, as an example of a liquid jetting device, is a printing device that jets liquid ink as ink droplets onto a medium S such as printing paper, thereby printing images, etc., by arranging the dots formed on the medium S. Furthermore, in addition to recording paper, any material such as resin film or cloth can be used as the medium S.

[0036] In the following text, the movement direction of the recording head 2 (in other words, the main scanning direction) among the three spatial axes X, Y, and Z will be defined as the X-axis, the transport direction of the medium S orthogonal to the main scanning direction will be defined as the Y-axis, and the direction of the nozzle 21 on which the recording head 2 is formed (see reference) will be defined as the Y-axis. Figure 2 The surface parallel to the nozzle surface is designated as the XY plane, and the direction intersecting the nozzle surface, i.e., the XY plane, which in this embodiment is orthogonal to the XY plane, is designated as the Z-axis. The ink droplets are sprayed along the +Z direction of the Z-axis.

[0037] The inkjet recording device 1 includes a liquid container 3, a delivery mechanism 4 for discharging medium S, a control unit 5 as a control unit, a moving mechanism 6, and an inkjet recording head 2 (hereinafter also referred to as the recording head 2).

[0038] The liquid container 3 separately stores multiple types (e.g., multiple colors) of ink ejected from the recording head 2. Examples of liquid containers 3 include cassettes that can be detached from the inkjet recording device 1, ink pouches made of flexible sheets, and ink canisters that can be refilled with ink. Furthermore, although not specifically illustrated, the liquid container 3 stores multiple types of ink of different colors or varieties.

[0039] Although the control unit 5 is not specifically illustrated, it is configured, for example, to include a control device such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and a storage device such as a semiconductor memory. The control unit 5 comprehensively controls the various elements of the inkjet recording device 1, namely the transport mechanism 4, the moving mechanism 6, and the recording head 2, by executing a program stored in the storage device.

[0040] The conveying mechanism 4 is controlled by the control unit 5 to convey the medium S along the Y direction, and for example, it has a conveying roller 4a. In addition, the conveying mechanism 4 for conveying the medium S is not limited to the conveying roller 4a, but may also be a mechanism for conveying the medium S by means of a belt or roller.

[0041] The moving mechanism 6 is controlled by the control unit 5, thereby causing the recording head 2 to move back and forth along the X-axis in the +X and -X directions.

[0042] Specifically, the moving mechanism 6 of this embodiment includes a conveyor body 7 and a conveyor belt 8. The conveyor body 7 is a generally box-shaped structure, also known as a carriage, that houses the recording head 2 and is fixed to the conveyor belt 8. The conveyor belt 8 is a seamless belt that is mounted along the X-axis. Under the control of the control unit 5, the conveyor belt 8 rotates, thereby causing the recording head 2 and the conveyor body 7 to move back and forth along guide rails (not shown) in the +X and -X directions. Additionally, a liquid container 3 can also be mounted on the conveyor body 7 along with the recording head 2.

[0043] Under the control of the control unit 5, the recording head 2 ejects ink supplied from the liquid container 3 as ink droplets from each of the plurality of nozzles 21 along the +Z direction onto the medium S. By implementing the ejection of ink droplets from the recording head 2 in parallel with the transport of the medium S by the transport mechanism 4 and the reciprocating movement of the recording head 2 by the moving mechanism 6, an image formed by ink, i.e., printing, is achieved on the surface of the medium S. Here, the recording head 2 is an example of a "piezoelectric device".

[0044] Figure 2 An exploded perspective view of an inkjet recording head 2, which is an example of a liquid jetting head in this embodiment. Figure 3 This is a top view of the flow channel forming substrate 10 of the recording head 2. Figure 4 For Figure 3 The cross-sectional view of record head 2 with reference to line A-A'. Figure 5 For Figure 3 The cross-sectional view of record head 2 with reference to line B-B'.

[0045] As shown in the accompanying drawings, the recording head 2 of this embodiment includes a flow channel forming substrate 10 as an example of a "substrate". The flow channel forming substrate 10 is composed of a silicon substrate, a glass substrate, an SOI substrate (Silicon-On-Insulator), and various ceramic substrates.

[0046] In the flow channel forming substrate 10, a plurality of pressure chambers 12 are arranged side by side along the +X direction, which is a first direction. The plurality of pressure chambers 12 are arranged in a straight line along the +X direction such that their positions in the +Y direction are the same. Pressure chambers 12 adjacent to each other in the +X direction are separated by partitions 11. Of course, the arrangement of the pressure chambers 12 is not particularly limited; for example, among the pressure chambers 12 arranged side by side along the +X direction, they can also be arranged in a staggered arrangement, where every other one is arranged at a position offset in the +Y direction.

[0047] Furthermore, the pressure chamber 12 in this embodiment can also be a rectangular shape, parallelogram shape, or rectangle shape observed in the +Z direction, with the two ends in the long side direction set to semi-circular shapes, such as a rounded rectangle shape, an ellipse shape, or an egg shape, or a flat oval shape, or a circular shape, or a polygonal shape. This pressure chamber 12 is equivalent to a "recess" provided on the "substrate".

[0048] On the +Z direction side of the flow channel forming substrate 10, a connecting plate 15 and a nozzle plate 20 are sequentially laminated.

[0049] In the connecting plate 15, a nozzle connecting channel 16 is provided to connect the pressure chamber 12 and the nozzle 21.

[0050] Furthermore, the connecting plate 15 is provided with a first manifold portion 17 and a second manifold portion 18, which constitute part of a common liquid chamber that connects multiple pressure chambers 12 in a shared manner. The first manifold portion 17 is provided so as to penetrate the connecting plate 15 in the +Z direction. In addition, the second manifold portion 18 is provided so as to not penetrate the connecting plate 15 in the +Z direction but to have an opening on the surface in the +Z direction.

[0051] Furthermore, in the connecting plate 15, the supply connecting channel 19, which communicates with the end of the pressure chamber 12 on the Y-axis, is independently provided for each of the pressure chambers 12. The supply connecting channel 19 connects the second manifold 18 to the pressure chamber 12, thereby supplying ink from the manifold 100 to the pressure chamber 12.

[0052] As such a connecting plate 15, silicon substrates, glass substrates, SOI substrates, various ceramic substrates, stainless steel substrates, and other metal substrates can be used. Furthermore, it is preferable that the connecting plate 15 uses a material with approximately the same coefficient of thermal expansion as the flow channel forming substrate 10. Thus, by using materials with approximately the same coefficient of thermal expansion for both the flow channel forming substrate 10 and the connecting plate 15, warping due to heat caused by differences in coefficients of thermal expansion is reduced.

[0053] The nozzle plate 20 is disposed on the surface of the connecting plate 15 opposite to the flow channel forming substrate 10, i.e., on the +Z direction side.

[0054] On the nozzle plate 20, nozzles 21 are formed that communicate with each pressure chamber 12 via nozzle communication channels 16. In this embodiment, the nozzle columns arranged side-by-side along the +X direction are separated into two columns in the +Y direction. That is, the multiple nozzles 21 in each column are arranged such that their positions in the +Y direction are the same. Of course, the arrangement of the nozzles 21 is not particularly limited. For example, among the nozzles 21 arranged side-by-side in the +X direction, a so-called staggered arrangement can be used, in which every other nozzle is arranged at a position offset in the +Y direction. As such a nozzle plate 20, metal substrates such as silicon substrates, glass substrates, SOI substrates, various ceramic substrates, and stainless steel substrates, as well as organic materials such as polyimide resin, can be used. In addition, it is preferable that the nozzle plate 20 uses a material with a coefficient of thermal expansion that is approximately the same as that of the communication plate 15. In this way, by using materials with approximately the same coefficient of thermal expansion for the nozzle plate 20 and the communication plate 15, it is possible to suppress warping caused by heat due to differences in coefficients of thermal expansion.

[0055] A vibrating plate 50 and a piezoelectric actuator 300 are sequentially laminated on the -Z direction side of the flow channel forming substrate 10. That is, the flow channel forming substrate 10, the vibrating plate 50, and the piezoelectric actuator 300 are sequentially laminated along the -Z direction. A fourth layer 200 is provided on the piezoelectric actuator 300 side of the vibrating plate 50. The vibrating plate 50, the piezoelectric actuator 300, and the fourth layer 200 will be described in detail later.

[0056] like Figure 2 as well as Figure 4 As shown, a protective substrate 30 having approximately the same size as the flow channel forming substrate 10 is bonded to the surface of the flow channel forming substrate 10 in the -Z direction. The protective substrate 30 has a holding portion 31 that protects the piezoelectric actuator 300. The holding portion 31 is provided independently for each row of piezoelectric actuators 300 arranged side by side in the +X direction, and two are formed side by side in the +Y direction. Furthermore, on the protective substrate 30, a through hole 32 extending in the +Z direction is provided between the two holding portions 31 arranged side by side along the +Y direction. The ends of individual lead electrodes 91 and common lead electrodes 92, which are led out from the electrodes of the piezoelectric actuators 300, are provided to be exposed in the through hole 32, and the individual lead electrodes 91 and common lead electrodes 92 are electrically connected to the wiring substrate 120 in the through hole 32.

[0057] In addition, such as Figure 4 As shown, a housing component 40 is fixed on the protective substrate 30. This housing component is formed together with the manifold 100 and flow channel forming substantially 10, which communicate with the plurality of pressure chambers 12. The housing component 40 has a shape substantially the same as the aforementioned connecting plate 15 when viewed in plan view, and is engaged with both the protective substrate 30 and the connecting plate 15. In this embodiment, the housing component 40 is engaged with the connecting plate 15. Furthermore, although not specifically illustrated, the housing component 40 and the protective substrate 30 are also joined together.

[0058] The housing component 40 has a recess 41 on the protective substrate 30 side, the recess 41 having a depth capable of accommodating the flow channel forming substrate 10 and the protective substrate 30. This recess 41 has a larger opening area compared to the surface of the protective substrate 30 that engages with the flow channel forming substrate 10. Furthermore, when the flow channel forming substrate 10 and the like are accommodated within the recess 41, the opening surface of the recess 41 on the nozzle plate 20 side is sealed by the connecting plate 15. Thus, a third manifold portion 42 is formed on the outer periphery of the flow channel forming substrate 10 by the housing component 40 and the flow channel forming substrate 10. Then, the manifold 100 of this embodiment is constituted by the first manifold portion 17 and the second manifold portion 18 provided in the connecting plate 15, and the third manifold portion 42 formed by the housing component 40 and the flow channel forming substrate 10. The manifold 100 is continuously arranged in the +X direction, spanning and side by side with pressure chambers 12, and the supply connection channels 19 that connect each pressure chamber 12 to the manifold 100 are arranged side by side in the +X direction.

[0059] Furthermore, a malleable substrate 45 is provided on the +Z direction side of the openings of the first manifold portion 17 and the second manifold portion 18 of the connecting plate 15. This malleable substrate 45 seals the openings on the liquid injection surface 20a side of the first manifold portion 17 and the second manifold portion 18. In this embodiment, such a malleable substrate 45 includes a sealing film 46 made of a flexible thin film and a fixing substrate 47 made of a hard material such as metal. Since the area of ​​the fixing substrate 47 opposite to the manifold 100 becomes an opening 48 that is completely removed in the thickness direction, one side of the manifold 100 becomes a flexible portion, or malleable portion 49, sealed only by the flexible sealing film 46.

[0060] The vibrating plate 50 and the piezoelectric actuator 300 of this embodiment will be described.

[0061] like Figure 4 as well as Figure 5As shown, the piezoelectric actuator 300 includes a first electrode 60, a piezoelectric layer 70, and a second electrode 80, which are sequentially laminated from the +Z direction side (which serves as the vibrating plate 50) towards the -Z direction side. The piezoelectric actuator 300 serves as a pressure generating unit that causes pressure changes in the ink within the pressure chamber 12. Such a piezoelectric actuator 300 is also called a piezoelectric element, and refers to the portion including the first electrode 60, the piezoelectric layer 70, and the second electrode 80. Furthermore, the portion in the piezoelectric layer 70 that generates piezoelectric strain when a voltage is applied between the first electrode 60 and the second electrode 80 is called an active portion 310. Conversely, the portion in the piezoelectric layer 70 that does not generate piezoelectric strain is called an inactive portion. That is, the active portion 310 refers to the portion of the piezoelectric layer 70 sandwiched between the first electrode 60 and the second electrode 80. In this embodiment, an active portion 310 is formed for each pressure chamber 12, which is a recess. In other words, a plurality of active portions 310 are formed in the piezoelectric actuator 300. Furthermore, it is generally configured such that the electrode of any one of the active parts 310 is set as a separate electrode independent for each active part 310, and the electrode of the other part is set as a common electrode shared by multiple active parts 310. In this embodiment, the first electrode 60 is a separate electrode, and the second electrode 80 is a common electrode. Of course, it is also possible that the first electrode 60 is a common electrode and the second electrode 80 is a separate electrode. The portion of the piezoelectric actuator 300 that faces the pressure chamber 12 on the Z-axis is a flexible portion, and the outer portion of the pressure chamber 12 is a non-flexible portion.

[0062] Specifically, such as Figures 3 to 5 As shown, the first electrode 60 is divided for each pressure chamber 12, thereby forming a separate electrode for each active part 310. The first electrode 60 is formed in the +X direction with a width narrower than the width of the pressure chamber 12. That is, in the +X direction, the end of the first electrode 60 is located inside the region opposite the pressure chamber 12. Furthermore, as... Figure 4 As shown, on the Y-axis of the first electrode 60, the end on the nozzle 21 side is positioned further outward than the pressure chamber 12. A separate lead electrode 91, serving as a lead wire, is connected to the end of the first electrode 60 positioned further outward than the pressure chamber 12 on the Y-axis.

[0063] The first electrode 60 can be made of a conductive material, such as iridium (Ir), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), chromium (Cr), nickel-chromium (NiCr), tungsten (W), titanium (Ti), or titanium oxide (TiO). X ), titanium tungsten (TiW), etc.

[0064] like Figures 3 to 5As shown, the piezoelectric layer 70 is continuously disposed with a predetermined width in the +Y direction and spanning the +X direction. The width of the piezoelectric layer 70 in the +Y direction is longer than its length in the +Y direction, which is the long side of the pressure chamber 12. Therefore, the piezoelectric layer 70 extends to the outside of the region opposite to the pressure chamber 12 on both sides of the pressure chamber 12 in the +Y and -Y directions. The end of the piezoelectric layer 70 on the Y-axis opposite to the nozzle 21 is located on the outer side compared to the end of the first electrode 60. That is, the end of the first electrode 60 opposite to the nozzle 21 is covered by the piezoelectric layer 70. Furthermore, the end of the piezoelectric layer 70 on the nozzle 21 side is located on the inner side compared to the end of the first electrode 60, and the end of the first electrode 60 on the nozzle 21 side is not covered by the piezoelectric layer 70. In addition, a separate lead electrode 91 made of gold (Au) or the like is connected to the end of the piezoelectric layer 70 that extends to the outside of the first electrode 60.

[0065] Furthermore, recesses 71 corresponding to each partition 11 are formed on the piezoelectric layer 70. The width of the recess 71 in the +X direction is the same as or larger than the width of the partition 11. In this embodiment, the width of the recess 71 in the +X direction is greater than the width of the partition 11. As a result, since the rigidity of the portion of the vibrating plate 50 that faces the two ends of the pressure chamber 12 in the +X and -X directions, i.e., the so-called arm portion of the vibrating plate 50, is suppressed, the piezoelectric actuator 300 can be displaced well. In addition, the recess 71 can be provided to penetrate the piezoelectric layer 70 in the +Z direction, which is the thickness direction, or it can be provided to penetrate the piezoelectric layer 70 to the middle in the thickness direction of the piezoelectric layer 70 without penetrating the piezoelectric layer 70 in the +Z direction. That is, on the bottom surface of the recess 71 in the +Z direction, the piezoelectric layer 70 can be completely removed or a part of the piezoelectric layer 70 can remain.

[0066] Such a piezoelectric layer 70 is constructed using a piezoelectric material composed of a composite oxide with a perovskite structure represented by the general formula ABO3. In this embodiment, lead zirconate titanate (PZT; Pb(Zr,Ti)O3) is used as the piezoelectric material. By using PZT in the piezoelectric material, a piezoelectric layer 70 with a large piezoelectric constant d31 is obtained.

[0067] In a perovskite-structured composite oxide represented by the general formula ABO3, an octahedron is formed by setting the oxygen coordination number at site A to 12 and at site B to 6. In this embodiment, lead (Pb) is located at site A, and zirconium (Zr) and titanium (Ti) are located at sites B.

[0068] Piezoelectric materials are not limited to PZT as described above. Other elements may also be included at sites A or B. For example, piezoelectric materials can also be perovskite materials such as barium zirconium titanate (Ba(Zr,Ti)O3), lanthanum lead zirconium titanate ((Pb,La)(Zr,Ti)O3), lead magnesium zirconium titanate of niobium (Pb(Zr,Ti)(Mg,Nb)O3), and silicon-containing lead zirconium titanate of niobium (Pb(Zr,Ti,Nb)O3).

[0069] Furthermore, piezoelectric materials can also be materials with suppressed Pb content, known as low-lead materials, or materials that do not use Pb, known as lead-free materials. Using low-lead materials as piezoelectric materials reduces the amount of Pb used. Conversely, using lead-free materials as piezoelectric materials simply eliminates the need for Pb. Therefore, by using low-lead or lead-free materials as piezoelectric materials, the environmental impact can be reduced.

[0070] As a non-lead piezoelectric material, examples include BFO-type materials containing bismuth ferrite (BFO; BiFeO3). In BFO, bismuth (Bi) is located at site A and iron (Fe) is located at site B. Other elements can also be added to BFO. For example, at least one element selected from manganese (Mn), aluminum (Al), lanthanum (La), barium (Ba), titanium (Ti), cobalt (Co), cerium (Ce), samarium (Sm), chromium (Cr), potassium (K), lithium (Li), calcium (Ca), strontium (Sr), vanadium (V), niobium (Nb), tantalum (Ta), molybdenum (Mo), tungsten (W), nickel (Ni), zinc (Zn), praseodymium (Pr), neodymium (Nd), and europium (Eu) can be added to BFO.

[0071] Furthermore, as other examples of non-lead piezoelectric materials, KNN-type materials containing sodium niobate (KNN; KNaNbO3) can be cited. Other elements can also be added to KNN. For example, at least one element selected from manganese (Mn), lithium (Li), barium (Ba), calcium (Ca), strontium (Sr), zirconium (Zr), titanium (Ti), bismuth (Bi), tantalum (Ta), antimony (Sb), iron (Fe), cobalt (Co), silver (Ag), magnesium (Mg), zinc (Zn), copper (Cu), vanadium (V), chromium (Cr), molybdenum (Mo), tungsten (W), nickel (Ni), aluminum (Al), silicon (Si), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), and europium (Eu) can be added to KNN.

[0072] Piezoelectric materials also include materials with a portion of an element missing, materials with a portion of an element in excess, and materials with a portion of an element replaced by another element. Materials whose chemical composition has deviated due to missing or excess elements, or materials whose elements have been replaced by other elements, are also included in the piezoelectric materials according to this embodiment, provided that the basic properties of the piezoelectric layer 70 remain unchanged. Of course, the piezoelectric materials that can be used in this embodiment are not limited to materials containing Pb, Bi, Na, K, etc., as described above.

[0073] like Figures 2 to 5 As shown, the second electrode 80 is continuously disposed on the side of the piezoelectric layer 70 opposite to the first electrode 60, i.e., the -Z direction side, and constitutes a common electrode shared by multiple active parts 310. The second electrode 80 is continuously disposed across the +X direction with a predetermined width in the +Y direction. In addition, the second electrode 80 is also disposed on the inner surface of the recess 71, i.e., on the side surface of the recess 71 of the piezoelectric layer 70, and on the vibrating plate 50, which serves as the bottom surface of the recess 71. Of course, the second electrode 80 may be disposed only on a portion of the inner surface of the recess 71, or it may be disposed without spanning the entire inner surface of the recess 71. That is, in this embodiment, the second electrode 80 is not disposed at the ends of the piezoelectric actuator 300 on the +Y and -Y direction sides on the flow channel forming substrate 10, and the vibrating plate 50 is disposed with its surface exposed in the -Z direction.

[0074] The materials used for the second electrode 80 include noble metals such as iridium (Ir), platinum (Pt), palladium (Pd), and gold (Au), as well as conductive oxides such as lanthanum nickel oxide (LNO). Furthermore, the second electrode 80 can also be a laminate of multiple materials. Preferably, the second electrode 80 uses an electrode containing iridium (Ir) and titanium (Ti). In this embodiment, the second electrode 80 uses a laminated electrode of iridium (Ir) and titanium (Ti).

[0075] Furthermore, a separate lead electrode 91 as a lead wire is led out from the first electrode 60. A common lead electrode 92 as a lead wire is led out from the second electrode 80. At the ends of these separate lead electrodes 91 and the common lead electrode 92 that are connected to the ends of the piezoelectric actuator 300, a flexible wiring board 120 as described above is connected. A drive circuit 121 is mounted in the wiring board 120, and the drive circuit 121 has a switching element for driving the piezoelectric actuator 300.

[0076] like Figure 5As shown, the vibrating plate 50 has a first layer 51, a second layer 52, and a third layer 53, which are laminated sequentially along the -Z direction. That is, the vibrating plate 50 has a first layer 51, a second layer 52 disposed between the first layer 51 and the piezoelectric actuator 300, and a third layer 53 disposed between the second layer 52 and the piezoelectric actuator 300. The first layer 51 is disposed in the vibrating plate 50 on the side closest to the flow channel forming substrate 10, i.e., the +Z direction side, and is in contact with the -Z direction side of the flow channel forming substrate 10. Furthermore, the third layer 53 is disposed in the vibrating plate 50 on the side closest to the -Z direction and is in contact with the piezoelectric actuator 300. The second layer 52 is located between the first layer 51 and the third layer 53. Additionally, although in Figure 4 and Figure 5 In this illustration, the interfaces between the layers constituting the vibrating plate 50 are clearly shown for ease of explanation, but these interfaces may not be clearly defined. For example, the constituent materials of two adjacent layers may be mixed together near the interface. The vibrating plate 50 having such a first layer 51, a second layer 52, and a third layer 53 is continuously arranged such that it spans the entire surface of the flow channel forming substrate 10 in the -Z direction.

[0077] The first layer 51 is a layer containing silicon (Si) as a constituent element. Specifically, the first layer 51 is, for example, an elastic film made of silicon oxide (SiO2). Here, in addition to silicon oxide and its constituent elements, the first layer 51 may also contain small amounts of elements such as zirconium (Zr), titanium (Ti), iron (Fe), chromium (Cr), or hafnium (Hf) as impurities. Such impurities have the effect of softening silicon oxide (SiO2).

[0078] Thus, the first layer 51 in this embodiment includes, for example, silicon oxide. This first layer 51 allows the flow channel forming substrate 10, which is made of a single-crystal silicon substrate, to be formed by thermal oxidation, thereby enabling it to be formed with better productivity compared to the case formed by sputtering.

[0079] In addition, silicon in the first layer 51 can exist not only in the state of oxide, but also in the state of monomer, nitride, or oxynitride. Furthermore, impurities in the first layer 51 can be elements that are inevitably mixed in during the formation of the first layer 51, or elements that are intentionally mixed into the first layer 51.

[0080] The thickness T1 of the first layer 51 is determined based on the thickness T and width W of the vibrating plate 50. The thickness T1 of the first layer 51 is preferably in the range of 100 nm or more and 20,000 nm or less, and more preferably in the range of 500 nm or more and 1,500 nm or less.

[0081] The third layer 53 is a layer containing zirconium (Zr) as a constituent element. Specifically, the third layer 53 is, for example, an insulating film made of zirconium oxide (ZrO2). Here, in addition to containing zirconium oxide and its constituent elements, the third layer 53 may also contain small amounts of elements such as titanium (Ti), iron (Fe), chromium (Cr), or hafnium (Hf) as impurities. Such impurities have the effect of softening zirconium oxide (ZrO2).

[0082] Thus, the third layer 53 may, for example, contain zirconium oxide. Such a third layer 53 is obtained, for example, by thermally oxidizing the layer after forming a zirconium monomer layer using a sputtering method or the like. Therefore, when forming the third layer 53, it is possible to easily obtain a third layer 53 of the desired thickness. Furthermore, since zirconium oxide has excellent electrical insulation, mechanical strength, and toughness, by including zirconium oxide in the third layer 53, the characteristics of the vibrating plate 50 can be improved. In addition, for example, it has the advantage that, when the piezoelectric layer 70 is composed of lead zirconate titanate, by including zirconium oxide in the third layer 53, it is easy to obtain a piezoelectric layer 70 with a high orientation rate preferentially oriented on the (100) plane when forming the piezoelectric layer 70.

[0083] Furthermore, the zirconium in the third layer 53 can exist not only as an oxide, but also as a monomer, nitride, or oxynitride. Additionally, impurities in the third layer 53 can be elements that are unavoidably introduced during its formation, or elements that are intentionally introduced. For example, such impurities could be those contained in the zirconium palladium used in the sputtering process to form the third layer 53.

[0084] The thickness T3 of the third layer 53 is determined based on the thickness T and width W of the vibrating plate 50. The thickness T3 of the third layer 53 is preferably in the range of 100 nm or more and 20,000 nm or less.

[0085] The second layer 52 is located between the first layer 51 and the third layer 53. Therefore, it prevents the first layer 51 from contacting the third layer 53. Thus, compared to a structure where the first layer 51 and the third layer 53 are in contact, the reduction of silicon oxide in the first layer 51 by zirconium in the third layer 53 is reduced.

[0086] The second layer 52 functions as a moisture-blocking membrane to suppress the formation of gaps (vacancies) at its interface with the third layer, thereby preventing moisture from entering the interface between the second and third layers.

[0087] Such a second layer 52 is a layer comprising one or both of silicon and nitrogen, including at least one metallic element selected from chromium (Cr), titanium (Ti), aluminum (Al), tantalum (Ta), hafnium (Hf), iridium (Ir), nickel (Ni), and copper (Cu), and silicon nitride (SiN) with the chemical formula Si3N4. The metallic element in such a second layer 52 may exist in the form of an oxide, a monomer, a nitride, or an oxide oxynitride. Furthermore, the second layer 52 may be a layer containing only one of the aforementioned metallic elements, or a layer containing two or more metallic elements. Additionally, the second layer 52 may be a layer containing both the aforementioned metallic elements and silicon nitride.

[0088] Furthermore, preferably, the second layer 52 is a layer containing a metal element that is less prone to oxidation than zirconium, and the second layer 52 is preferably composed of an oxide of such metal element, for example. In other words, preferably, the second layer 52 contains a metal element whose oxide formation free energy is greater than that of zirconium. Preferably, this metal element contains any one of chromium, titanium, and aluminum, and is preferably composed of an oxide of such metal element. Furthermore, the magnitude of the oxide formation free energy can be evaluated, for example, based on the well-known Elingham diagram.

[0089] The second layer 52, by including a metal element that is less susceptible to oxidation than zirconium, reduces the reduction of the silicon oxide contained in the first layer 51 compared to a structure where the metal element in the second layer 52 is more easily oxidized than zirconium, i.e., compared to a structure where the oxide formation free energy of the metal element in the second layer 52 is lower than that of the oxide of zirconium. As a result, the adhesion between the first layer 51 and the third layer 53 is improved compared to a structure without the second layer 52.

[0090] Furthermore, the second layer 52 is composed of oxides of chromium, titanium, and aluminum, which improves the adhesion to the first layer 51 and the third layer 53 compared to materials composed of monomers, nitrides, and carbon.

[0091] Chromium is less oxidizable than silicon. In other words, the free energy of oxide formation of chromium is greater than that of silicon oxide. Therefore, when chromium is included as a metallic element in the second layer 52, the reduction of silicon oxide contained in the first layer can be reduced compared to the case where the second layer 52 does not contain a metallic element that is less oxidizable than silicon.

[0092] Furthermore, when the second layer 52 contains chromium, for example, chromium forms an oxide, thus the second layer 52 contains chromium oxide. Such a second layer 52 is obtained by thermally oxidizing the layer after forming a layer of chromium monomer using a sputtering method or the like. Therefore, when forming the second layer 52, it is possible to easily obtain a second layer 52 of the desired thickness.

[0093] Here, the chromium oxide contained in the second layer 52 can be in any state, such as polycrystalline, amorphous, or monocrystalline. However, when the chromium oxide contained in the second layer 52 has an amorphous structure, the compressive stress generated in the second layer 52 can be reduced compared to when the chromium oxide contained in the second layer 52 is in a polycrystalline or monocrystalline state. As a result, the strain generated at the interface between the first layer 51 or the third layer 53 and the second layer 52 can be reduced.

[0094] Oxides of titanium or aluminum are easily moved by heat. Therefore, when titanium or aluminum is included as a metallic element in the second layer 52, the interlayer adhesion between each of the first layer 51 or the third layer 53 and the second layer 52 can be improved through the anchoring effect or chemical bonding generated by the oxide of this metallic element. Furthermore, titanium readily forms oxides with silicon or zirconium. Therefore, when titanium is included as a metallic element in the second layer 52, the adhesion between the first layer 51 and the second layer 52 can be improved by forming an oxide with titanium and silicon, and the adhesion between the second layer 52 and the third layer 53 can be improved by forming an oxide with titanium and zirconium.

[0095] Furthermore, when the second layer 52 contains titanium, for example, titanium forms an oxide, thus the second layer 52 contains titanium oxide. Such a second layer 52 is obtained by thermally oxidizing the layer after forming a layer of titanium monomers using a sputtering method or the like. Therefore, when forming the second layer 52, it is possible to easily obtain a second layer 52 of the desired thickness.

[0096] Here, the titanium oxide contained in the second layer 52 can be in any state of polycrystalline, amorphous, or monocrystalline. However, it is preferable that the titanium oxide contained in the second layer 52 is in a polycrystalline or monocrystalline state, and particularly preferable that it has a rutile structure as a crystalline structure. Even among the possible crystalline structures of titanium oxide, the rutile structure is the most stable, and even if it moves due to heat, it is difficult to change into polymorphs such as anatase or brookite. Therefore, compared with the case where the crystalline structure of the titanium oxide contained in the second layer 52 is other crystalline structures, the thermal stability of the second layer 52 can be improved.

[0097] Furthermore, when the second layer 52 contains aluminum, for example, aluminum forms an oxide, thus the second layer 52 contains aluminum oxide. Such a second layer 52 is obtained by thermally oxidizing the layer after forming a layer of aluminum monomers using a sputtering method or the like. Therefore, when forming the second layer 52, it is possible to easily obtain a second layer 52 of the desired thickness.

[0098] Here, the alumina contained in the second layer 52 can be in any of the following states: polycrystalline, amorphous, or monocrystalline. In the case of being polycrystalline or monocrystalline, it has a trigonal crystal structure as a crystalline structure.

[0099] Furthermore, in the second layer 52, in addition to the aforementioned metallic elements, elements such as titanium (Ti), silicon (Si), iron (Fe), chromium (Cr), or hafnium (Hf) may also be present in small amounts as impurities. For example, these impurities may be elements contained in the first layer 51 or the third layer 53. These impurities may exist, for example, in an oxide state along with the metallic elements in the second layer 52. Such impurities, even if they reduce the diffusion of silicon from the first layer 51 to the second layer 52, will also have the effect of suppressing the diffusion of silicon to the third layer 53.

[0100] Based on this viewpoint, it is preferable that the second layer 52 and the third layer 53 each contain impurities. When the second layer 52 and the third layer 53 each contain impurities, compared to the case where they do not contain impurities, by softening the second layer 52 and the third layer 53, the risk of cracking in the vibrating plate can be reduced.

[0101] Preferably, the impurity content in the second layer 52 is higher than that in the third layer 53. In other words, preferably, the peak concentration of impurities in the thickness direction of the laminate composed of the second layer 52 and the third layer 53 is located in the second layer 52. In this case, the formation of gaps at the interface between the second layer 52 and the third layer 53 or in the third layer 53 is prevented or reduced. In contrast, when the peak concentration is located in the third layer 53, the crystalline structure in the third layer 53 is deformed due to impurities. Therefore, gaps are formed at the interface between the second layer 52 and the third layer 53 or in the third layer 53. As a result, the risk of cracks in the vibrating plate 50 increases.

[0102] The metallic elements in the second layer 52 can exist not only in the form of oxides, but also in the form of monomers, nitrides, or oxynitrides. Furthermore, the impurities in the second layer 52 can be elements that are inevitably mixed in during the formation of the second layer 52, or elements that are intentionally mixed into the second layer 52.

[0103] Furthermore, the thickness T2 of the second layer 52 is determined based on the thickness T and width W of the vibrating plate 36. Although not specifically limited, it is preferably thinner than the thickness T1 of the first layer 51 and the thickness T3 of the third layer 53. In this case, it has the advantage of making it easier to optimize the characteristics of the vibrating plate 36.

[0104] When the metal element contained in the second layer 52 is titanium, the thickness T2 of the second layer 52 is preferably in the range of 20 nm to 50 nm, more preferably in the range of 25 nm to 40 nm. Furthermore, when the metal element contained in the second layer 52 is aluminum, it is preferably in the range of 20 nm to 50 nm, particularly preferably in the range of 20 nm to 35 nm. Furthermore, when the metal element contained in the second layer 52 is chromium, it is preferably in the range of 1 nm to 50 nm, more preferably in the range of 2 nm to 30 nm. Therefore, regardless of whether the metal element contained in the second layer 52 is titanium, aluminum, or chromium, as long as the thickness T2 of the second layer 52 is within the range of 20 nm to 50 nm, the preferred conditions are met. By keeping the thickness T2 within such a range, the effect of improving the adhesion between the first layer 51 and the third layer 53 through the second layer 52 can be appropriately achieved.

[0105] In contrast, when the thickness T2 is too thin, the effect of reducing the diffusion of silicon monomers from the first layer 51 by the second layer 52 tends to decrease, depending on the type of metal element contained in the second layer 52. For example, when the second layer 52 is composed of titanium oxide, when the thickness T2 is too thin, depending on the heat treatment conditions during manufacturing, silicon monomers diffusing from the first layer 51 to the second layer 52 may sometimes reach the third layer 53. On the other hand, when the thickness T2 is too thick, the heat treatment during the manufacturing of the second layer 52 may not be sufficiently implemented, or the heat oxidation may take a long time, which may have adverse effects on other layers.

[0106] By configuring the second layer 52 in this manner, voids can be suppressed at the interface between the second layer 52 and the third layer 53. Therefore, it is possible to prevent moisture from penetrating from the end face of the piezoelectric actuator 300 into the interface between the second layer 52 and the third layer 53. Consequently, it is possible to prevent the zirconium of the third layer 53 from becoming embrittled due to moisture, and to suppress damage such as interlayer delamination or cracks in the third layer 53 between the upper and lower layers of the third layer 53.

[0107] Furthermore, in this embodiment, since the second layer 52 is continuously disposed across the entire surface of the substrate 10 forming the flow channel in the -Z direction, when viewed from above in the +Z direction, the second layer 52 is disposed such that it covers the pressure chamber 12. That is, the second layer 52 is disposed at a position overlapping the pressure chamber 12 in the +Z direction. Incidentally, the second layer 52 only needs to be disposed at least in the portion overlapping the pressure chamber 12 when viewed from above in the +Z direction; it may not be disposed in areas other than the pressure chamber 12, such as the portion overlapping the partition wall 11. Even in this case, the second layer 52 can suppress moisture intrusion into the interface between the third layer 53 and the portion overlapping the pressure chamber 12.

[0108] A fourth layer 200 is provided above the third layer 53 of the vibrating plate 50, that is, in the -Z direction on the side opposite to the first layer 51 in the Z-axis. The fourth layer 200 is provided in such a way that it spans approximately the entire surface of the -Z direction side of the flow channel forming substrate 10.

[0109] The fourth layer 200 is disposed directly above the third layer 53 in the -Z direction, in a portion other than the piezoelectric actuator 300, such as within the recess 71. That is, the fourth layer 200 is in contact with the third layer 53. Furthermore, in the portion where the piezoelectric actuator 300 is disposed, the first electrode 60 and the piezoelectric layer 70 are sandwiched between the third layer 53 and the fourth layer 200. Specifically, the second electrode 80 is disposed directly above the fourth layer 200 in the -Z direction. In other words, the third layer 53, the first electrode 60, the piezoelectric layer 70, the fourth layer 200, and the second electrode 80 are sequentially laminated along the -Z direction. That is, "the fourth layer 200 is disposed on the piezoelectric layer 70 side of the third layer 53" means that this includes the structure where the fourth layer 200 is disposed directly above the third layer 53, and also includes the state where other components are located between and above the fourth layer 200, in other words, the state where they are disposed above it.

[0110] The fourth layer 200 functions as a moisture barrier to suppress the intrusion of moisture into the interface between the third layer 53 and the layer on the -Z direction side, and to suppress the intrusion of moisture from the -Z direction surface side of the second electrode 80.

[0111] Such a fourth layer 200 can use the same material as the second layer 52. That is, the fourth layer 200 is a layer that includes at least one or both of silicon and nitrogen, such as silicon nitride (SiN) containing silicon and nitrogen, and includes at least one metal element selected from chromium, titanium, aluminum (Al), tantalum, hafnium, iridium (Ir) and the chemical formula Si3N4. The metal element of such a fourth layer 200 can exist not only in the state of oxide, but also in the state of monomer, nitride, or oxynitride. Furthermore, the fourth layer 200 can contain only one of the aforementioned metal elements, or it can contain two or more metal elements. In addition, the fourth layer 200 can be a layer containing both the aforementioned metal elements and silicon nitride. In particular, the fourth layer 200 is preferably a layer composed of an oxide or nitride of the metal element contained in the second electrode 80. Thus, the fourth layer 200 is composed of oxides or nitrides of the metal elements contained in the second electrode 80, thereby improving the adhesion between the two by using materials containing the same metal elements as the fourth layer 200 and the second electrode 80.

[0112] Furthermore, it is preferable that the fourth layer 200 is made of a conductive material. However, even if the fourth layer 200 is made of an insulating material, the decrease in electric field strength of the piezoelectric layer 70 caused by the second electrode 80 can be suppressed by making the thickness T4 of the fourth layer 200 thinner, thereby suppressing the displacement reduction caused by the decrease in electric field strength.

[0113] Furthermore, the fourth layer 200 in this embodiment can also protect the piezoelectric layer 70 from the influence of moisture or hydrogen by sandwiching the piezoelectric layer 70 between it and the second layer 52. Moreover, by not placing the fourth layer 200 on the vibrating plate 50 side of the piezoelectric layer 70, it is possible to suppress the disruption of the crystal structure of the piezoelectric layer 70 due to the fourth layer 200, and the crystal structure of the piezoelectric layer 70 can be controlled by the third layer 53.

[0114] In addition, by using the same material as the second layer 52, the fourth layer 200 can be easily manufactured without the need to prepare multiple materials, and costs can be reduced.

[0115] Furthermore, it is preferable that the thickness T2 of the second layer 52 is greater than the thickness T4 of the fourth layer 200. That is, it is preferable that T2 > T4. This is because, in the vibrating plate 50, moisture is more likely to penetrate from the lower side of the third layer 53, i.e., the first layer 51 side, compared to the side above the third layer 53, i.e., the second electrode 80 side. Therefore, by making the thickness T2 of the second layer 52 disposed on the first layer 51 side of the third layer 53 thicker, it is possible to prevent moisture from penetrating from the lower side of the third layer 53, i.e., the second layer 52 side. In addition, by making the thickness T4 of the fourth layer 200 thinner than the thickness T2 of the second layer 52, it is possible to suppress the situation where the deformation of the vibrating plate 50 and the piezoelectric actuator 300 is greatly hindered by the fourth layer 200.

[0116] Preferably, displacement is more likely to occur when the thickness T4 of the fourth layer 200 is, for example, in the range of 5 nm or more and 20 nm or less. For example, when the thickness T4 of the fourth layer 200 is too thin, the function of shielding moisture becomes less effective, and when the thickness T4 of the fourth layer is too thick, as described above, it hinders the displacement of the vibrating plate 50 and the piezoelectric actuator 300.

[0117] Furthermore, in this embodiment, since the fourth layer 200 is continuously disposed across approximately the entire surface of the substrate 10 in the -Z direction, when viewed from above in the +Z direction, the fourth layer 200 is disposed in such a way that it covers the pressure chamber 12. That is, the fourth layer 200 is disposed at a position overlapping the pressure chamber 12 when viewed from above in the +Z direction. Incidentally, the fourth layer 200 only needs to be disposed at least in the portion overlapping the pressure chamber 12 when viewed from above in the +Z direction; it can also be disposed in areas other than the pressure chamber 12, such as the portion overlapping the partition wall 11. Even in this case, the fourth layer 200 can suppress the intrusion of moisture into the third layer 53 in the portion overlapping the pressure chamber 12.

[0118] Figure 6 This is a diagram used to illustrate the manufacturing method of a piezoelectric device. The following is based on... Figure 6 The manufacturing method of piezoelectric devices will be explained using the manufacturing of a recording head as an example.

[0119] like Figure 6 As shown, the method for manufacturing the recording head includes a substrate preparation step S10, a diaphragm formation step S20, a piezoelectric actuator and a fourth layer formation step S30, and a pressure chamber formation step S40. Here, the diaphragm formation step S20 includes a first layer formation step S21, a second layer formation step S22, and a third layer formation step S23. Each step will be described in turn below.

[0120] The substrate preparation process S10 is a process of preparing a substrate that should become the flow channel forming substrate 10. The substrate is, for example, a single-crystal silicon substrate.

[0121] The vibratory plate forming process S20 is the process of forming the aforementioned vibratory plate 50, and is performed after the substrate preparation process S10. In the vibratory plate forming process S20, the first layer forming process S21, the second layer forming process S22, and the third layer forming process S23 are performed sequentially.

[0122] The first layer formation process S21 is the process of forming the aforementioned first layer 51. In the first layer formation process S21, for example, the first layer 51 composed of silicon oxide (SiO2) is formed by thermally oxidizing one side of the single-crystal silicon substrate prepared in the substrate preparation process S10. In addition, the method of forming the first layer 51 is not particularly limited to this, and for example, it can be formed by sputtering, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), spin coating, etc.

[0123] The second layer forming process S22 is the process of forming the aforementioned second layer 52. In the second layer forming process S22, for example, a layer of chromium, titanium, or aluminum is formed on the first layer 51 by sputtering, and the second layer 52, composed of chromium oxide, titanium oxide, or aluminum oxide, is formed by thermal oxidation of the first layer. Furthermore, the method for forming the second layer 52 is not particularly limited to this; for example, CVD, PVD, ALD, spin coating, etc., can be used. Moreover, the thermal oxidation in the second layer forming process S22 can be performed simultaneously with the thermal oxidation in the third layer forming process S23 described later.

[0124] The third layer forming process S23 is the process of forming the aforementioned third layer 53. In the third layer forming process S23, for example, a zirconium layer is formed on the second layer 52 by sputtering, and the third layer 53 composed of zirconium oxide is formed by thermal oxidation of the layer. Through these first layer forming processes S21, second layer forming process S22, and third layer forming process S23, the vibrating plate 50 is formed. In addition, the formation of the third layer 53 is not limited to this; for example, CVD, PVD, ALD, spin coating, etc. can be used.

[0125] The piezoelectric actuator and fourth layer formation process S30 is the process for forming the aforementioned piezoelectric actuator 300 and fourth layer 200, and is performed after the third layer formation process S23. The piezoelectric actuator and fourth layer formation process S30 includes a first electrode formation process S31, a piezoelectric body layer formation process S32, a fourth layer formation process S33, and a second electrode formation process S34.

[0126] The first electrode formation step S31 is the step of forming the aforementioned first electrode 60. In the first electrode formation step S31, the first electrode 60 is formed by using known film formation techniques such as sputtering and known processing techniques such as photolithography and etching.

[0127] The piezoelectric layer formation step S32 is the step for forming the aforementioned piezoelectric layer 70. In the piezoelectric layer formation step S32, for example, a precursor layer of the piezoelectric layer is formed using the sol-gel method, and the piezoelectric layer 70 is formed by sintering and crystallizing the precursor layer. Of course, the method for forming the piezoelectric layer 70 is not particularly limited to this; for example, it can also be formed using MOD (Metal-Organic Decomposition), sputtering, laser ablation, etc. Furthermore, in the piezoelectric layer formation step S32, the piezoelectric layer 70 is formed into a predetermined shape using known processing techniques such as photolithography and etching.

[0128] The fourth layer forming process S33 is the process of forming the aforementioned fourth layer 200. In the fourth layer forming process S33, for example, a layer of chromium, titanium, or aluminum is formed on the first layer 51 by sputtering, and a second layer 52 composed of chromium oxide, titanium oxide, or aluminum oxide is formed by thermal oxidation of the first layer. Furthermore, the method for forming the second layer 52 is not particularly limited to this; CVD, PVD, ALD, spin coating, etc., can also be used.

[0129] The second electrode formation step S34 is the step of forming the aforementioned second electrode 80. In the second electrode formation step S34, the second electrode 80 is formed by known film formation techniques such as sputtering and known processing techniques such as photolithography and etching. As a result, a piezoelectric actuator 300 having a first electrode 60, a piezoelectric layer 70, and a second electrode 80, and a fourth layer 200 are formed.

[0130] After the piezoelectric actuator 300 is formed, the side of the substrate that is different from the side on which the piezoelectric actuator 300 is formed is ground by CMP (chemical mechanical polishing) or the like, as needed, thereby achieving planarization of the side or adjustment of the thickness of the substrate.

[0131] The pressure chamber formation process S40 is the process for forming the aforementioned pressure chamber 12, and is performed after the piezoelectric actuator and the fourth layer formation process S30. In the pressure chamber formation process S40, for example, the pressure chamber 12 is formed by anisotropic etching on one of the two surfaces of the monocrystalline silicon substrate after the formation of the piezoelectric actuator 300, which is different from the surface where the piezoelectric actuator 300 is formed. As a result, a flow channel forming substrate 10 with the pressure chamber 12 formed is obtained. At this time, the etchant used for anisotropic etching of the monocrystalline silicon substrate can be, for example, an aqueous solution of potassium hydroxide (KOH). Furthermore, at this time, the first layer 51 functions as a stop layer to stop the anisotropic etching.

[0132] After the pressure chamber forming process S40, the recording head 2 is manufactured by appropriately performing a process such as bonding the protective substrate 30, the connecting plate 15, etc., to the flow channel forming substrate 10 using an adhesive.

[0133] Implementation Method 2

[0134] Figure 7 This is a cross-sectional view of the main part of an inkjet recording head 2, which is an example of a liquid ejection head according to Embodiment 2 of the present invention. Furthermore, the same symbols are used for the same components as in the above-described embodiment, and repeated descriptions are omitted.

[0135] like Figure 7 As shown, a vibrating plate 50, a piezoelectric actuator 300, and a fourth layer 200 are provided on the -Z direction side of the flow channel forming substrate 10.

[0136] The vibrating plate 50 has the same first layer 51, second layer 52 and third layer 53 as in Embodiment 1 described above.

[0137] A first electrode 60, a piezoelectric layer 70, and a second electrode 80 are sandwiched between the third layer 53 and the fourth layer 200. That is, the fourth layer 200 is disposed on the -Z direction side of the second electrode 80. Of course, the fourth layer 200 is disposed directly above the portion of the third layer 53 where the second electrode 80 is not disposed.

[0138] This recording head 2 with a fourth layer 200 can be formed by replacing the order of the piezoelectric actuator and the fourth layer forming step S33 of the fourth layer forming step S30, and the second electrode forming step S34. That is, after performing the second electrode forming step S34 and forming the second electrode 80, the fourth layer 200 can be formed over the second electrode 80 and the vibrating plate 50 by performing the fourth layer forming step S33.

[0139] Sample 1

[0140] A first layer 51 with a thickness of 1460 nm, consisting of silicon oxide, is formed by thermal oxidation of one side of a single-crystal silicon substrate in the opposite orientation (110).

[0141] Next, a zirconium film is formed on the first layer 51 by sputtering, and the film is thermally oxidized at 900°C to form a third layer 53 with a thickness of 400 nm made of zirconium oxide.

[0142] Based on the above, a vibrating plate consisting of a first layer 51 and a third layer 53 is manufactured.

[0143] Sample 2

[0144] On top of the first layer 51, which is the same as that of the sample 1 described above, a second layer 52 with a thickness of 20 nm made of alumina was formed by atomic layer deposition (ALD).

[0145] Next, a third layer 53, identical to that of sample 1, was formed on top of the second layer 52.

[0146] In this way, a vibrating plate 50 consisting of a first layer 51, a second layer 52 and a third layer 53 is manufactured.

[0147] Sample 3

[0148] On top of the first layer 51, which is the same as that of the sample 1 described above, a film made of titanium is formed by sputtering and thermal oxidation of the film, thereby forming a second layer 52 with a thickness of 40 nm made of titanium oxide.

[0149] Next, a third layer 53, identical to that of sample 1, was formed on top of the second layer 52.

[0150] In this way, a vibrating plate 50 consisting of a first layer 51, a second layer 52 and a third layer 53 is manufactured.

[0151] Experimental Example 1

[0152] The cross-sections of samples 1-3 were observed using STEM (scanning transmission electron microscopy). Figures 8 to 10 The results are shown in the figure.

[0153] Furthermore, samples 1 to 3 were exposed for more than 24 hours in an atmosphere of heavy water vapor at a temperature of 45°C and a humidity of 95% RH or higher, and analysis based on SIMS (Secondary Ion Mass Analysis) was performed. Figures 11 to 13 The results are shown in the figure.

[0154] like Figure 9 as well as Figure 10As shown, in samples 2 and 3, no gap was formed between the second layer 52 and the third layer 53. In contrast, as... Figure 8 As shown, in sample 1, a gap 400 is generated between the first layer 51 and the third layer 53.

[0155] In addition, such as Figure 12 as well as Figure 13 As shown, in samples 2 and 3, moisture did not penetrate from the outside into the interface between the second layer 52 and the third layer 53. In contrast, as... Figure 11 As shown, in sample 1, moisture penetrates from the outside into the space between the first layer 51 and the third layer 53. That is, in the vibrating plate 50, moisture penetrates from the interface between the third layer 53 and the layer relative to the third layer 53 in the +Z direction. This is referred to as the moisture penetration path R1.

[0156] Furthermore, based on this result, by setting a second layer 52, it is possible to suppress the formation of gaps 400 at the interface between the second layer 52 and the third layer 53, and to suppress the intrusion of moisture into the interface.

[0157] Sample 4

[0158] A piezoelectric actuator 300 was formed on the vibrating plate 50 of sample 1. The piezoelectric actuator 300 has a first platinum (Pt) electrode 60, a piezoelectric layer 70 of lead zirconate titanate (PZT; Pb(Zr,Ti)O3) and a second electrode 80 of iridium (Ir) and titanium (Ti).

[0159] Experimental Example 2

[0160] Sample 4 was exposed to a heavy water vapor atmosphere at 45°C and 95% RH or higher for more than 24 hours, and analysis based on RBS (Rutherford Backscattering Spectrometry) was performed. Figure 14 The results are shown in [the document / reference]. Additionally, in [the document / reference]... Figure 22 In this context, H represents hydrogen and D represents deuterium.

[0161] like Figure 14 As shown, deuterium D was detected between the third layer 53 and the second electrode 80. Since deuterium is almost non-existent in nature, it is... Figure 14The results show that deuterium has penetrated from the outside into the space between the third layer 53 and the second electrode 80. In other words, within the vibrating plate 50, moisture has penetrated into the interior from the second electrode 80 side. The moisture intrusion path from the second electrode 80 side of the vibrating plate 50 can be considered from two directions: the interface between the third layer 53 and the layer on the -Z direction side of the third layer 53 on the end face of the vibrating plate 50, and the surface of the second electrode 80 in the -Z direction. The moisture intrusion path from the interface between the third layer 53 and the layer on the -Z direction side of the third layer 53 is referred to as moisture intrusion path R2. Furthermore, the moisture intrusion path from the surface side of the second electrode 80 in the -Z direction of the third layer 53 is referred to as moisture intrusion path R3.

[0162] Sample 5

[0163] On the vibrating plate 50 of sample 1, iridium and titanium are laminated in sequence to form the second electrode 80.

[0164] Sample 6

[0165] A fourth layer 200 composed of titanium nitride was formed on the second electrode 80 of sample 5.

[0166] Experimental Example 3

[0167] Sample 6 was exposed to a heavy water vapor atmosphere at 45°C and 95% RH or higher for more than 24 hours, and then analyzed using SIMS (Secondary Ion Mass Analysis). Figure 15 The results are shown in the figure.

[0168] like Figure 15 As shown, the fourth layer 200 can suppress the intrusion of moisture into the interior of the vibrating plate 50, namely the third layer 53.

[0169] Sample 7

[0170] A fourth layer 200 with a thickness of 10 nm, composed of iridium oxide, was formed on the vibrating plate 50 of sample 1 by sputtering.

[0171] Next, a second electrode 80 identical to that of sample 5 was formed on the fourth layer 200.

[0172] Sample 8

[0173] A fourth layer 200 with a thickness of 30 nm, consisting of aluminum oxide, was formed on the same vibrating plate 50 and second electrode 80 as sample 5 by atomic layer deposition (ALD).

[0174] Test Example 4

[0175] Scratch tests were performed before and after immersing samples 5, 7, and 8 in pure water for more than 30 minutes. The results are shown in Table 1 below.

[0176] Table 1

[0177]

[0178] As shown in Table 1, in samples 7 and 8, no decrease in scratch strength was observed before and after immersion in pure water. In contrast, in sample 5, it can be considered that the scratch strength decreased significantly after immersion in pure water, therefore, the third layer 53 became brittle due to moisture. Furthermore, a decrease in scratch strength of more than 5% before and after immersion in pure water was considered as moisture intrusion.

[0179] Based on the results of these test examples 1 to 4, a comprehensive evaluation was conducted on the structures of Embodiment 1 and Embodiment 2, and the structures of Comparative Examples 1 to 4 used as comparisons. Figures 16-19 The structures of Comparative Examples 1 to 4 are shown in Table 2 below.

[0180] like Figure 16 As shown, Comparative Example 1 is a structure without a second layer 52 and a fourth layer 200.

[0181] like Figure 17 As shown, Comparative Example 2 is configured with only the fourth layer 200 of Embodiment 1, without the second layer 52.

[0182] like Figure 18 As shown, Comparative Example 3 is configured with only the fourth layer 200 of Embodiment 2, without the second layer 52.

[0183] like Figure 19 As shown, Comparative Example 4 is a structure that has only a second layer 52 and no fourth layer 200.

[0184] Table 2

[0185]

[0186] As shown in Table 2, in the structures provided with the second layer 52 and the fourth layer 200 of Embodiments 1 and 2, the intrusion of moisture into the interior of the vibrating plate 50 can be suppressed, thereby preventing the third layer 53 from becoming brittle due to the intruded moisture. Therefore, interlaminar delamination between the third layer 53 and the layers above and below it, or cracks in the vibrating plate 50, can be suppressed. Furthermore, since moisture intrusion path R1 is easier to penetrate than moisture intrusion paths R2 and R3, the structure of Comparative Example 4 can suppress moisture intrusion compared to the structure of Comparative Example 1. Therefore, the structure of Comparative Example 4 can suppress interlaminar delamination or cracks in the vibrating plate 50 compared to Comparative Examples 1-3.

[0187] Furthermore, it is preferable that the second layer 52 and the third layer 53 have the same valence. Here, "the second layer 52 and the third layer 53 have the same valence" means that the difference X between the valence of the main constituent element of the second layer 52 and the valence of the main constituent element of the third layer 53 is in the range of -0.5 ≤ X ≤ +0.5. By setting the valence of the second layer 52 and the third layer 53 to be the same in this way, the overall insulation of the vibrating plate 50 is improved, and therefore, leakage current among the multiple active parts 310 of the piezoelectric actuator 300 can be suppressed. Therefore, leakage current can be suppressed, thereby reducing the displacement reduction of the active parts 310 caused by leakage current.

[0188] For example, if the third layer 53 is composed of zirconium oxide (ZrO2) with a +4 valence, it is preferable that the constituent elements of the second layer 52 use the same +4 valence and stable titanium, hafnium, iridium, etc.

[0189] Furthermore, it is preferable that the valences of the second layer 52 and the third layer 53 are different. Here, different valences of the second layer 52 and the third layer 53 mean that the difference X between the valence of the main constituent element of the second layer 52 and the valence of the main constituent element of the third layer 53 is in the range of X < -0.5 and +0.5 ≤ X. That is, when the constituent element of the second layer 52 has a valence of +4, it is preferable that the constituent element of the third layer 53 has a valence of less than +3.5 or greater than +4.5.

[0190] In this way, by making the valences of the second layer 52 and the third layer 53 different, the constituent elements of the second layer 52 can easily move towards the -Z direction side of the third layer 53. Therefore, when the active part 310 is selectively driven, a small current flows by causing leakage current in the other undriven active parts 310, thereby suppressing the deterioration deviation of the continuously moving active parts 310 and the other unmoving active parts 310. Therefore, the deviation of displacement reduction of multiple active parts 310 can be suppressed, and the deviation of ink droplet ejection characteristics can be suppressed, thereby improving print quality.

[0191] For example, if the third layer 53 is composed of zirconium oxide (ZrO2) with a +4 valence, it is preferable that the constituent elements of the second layer 52 are chromium, aluminum, tantalum, etc., with valences different from those of the third layer 53.

[0192] Sample 9

[0193] A first layer 51 with a thickness of 1460 nm, consisting of silicon oxide, is formed by thermal oxidation of one side of a single-crystal silicon substrate in the opposite orientation (110).

[0194] Next, a zirconium film is formed on the first layer 51 by sputtering, and the film is thermally oxidized at 900°C to form a third layer 53 with a thickness of 400 nm made of zirconium oxide. Thus, a vibrating plate 50 consisting of the first layer 51 and the third layer 53 is formed.

[0195] Next, the first electrode 60, the piezoelectric layer 70 and the second electrode 80 are formed and patterned on the vibrating plate 50, thereby forming a piezoelectric actuator 300 with the same shape as in Embodiment 1.

[0196] Subsequently, by using potassium hydroxide aqueous solution (KOH) as an etching solution, anisotropic etching was performed on the other side of the single-crystal silicon substrate, thereby forming a recess with the first layer 51 as the bottom surface.

[0197] Sample 10

[0198] Except for setting the thickness of the third layer 53 to 645 nm, everything else is the same as that of sample 9.

[0199] Sample 11

[0200] A second layer 52 with a thickness of 40 nm composed of titanium oxide was formed by sputtering a titanium film on the first layer 51 of the sample 9 and then thermally oxidizing the film.

[0201] In addition, except that the thickness of the third layer 53 formed on the second layer 52 is set to 250 nm, all other layers are set to be the same as those of the sample 9 described above.

[0202] Sample 12

[0203] A second layer 52 with a thickness of 40 nm composed of chromium oxide was formed by sputtering a chromium film on the first layer 51 of the sample 9 and then thermally oxidizing the film.

[0204] In addition, except that the thickness of the third layer 53 formed on the second layer 52 is set to 500 nm, all other thicknesses are the same as those of the sample 9 described above.

[0205] Sample 13

[0206] Except for setting the thickness of the third layer 53 to 250 nm, everything else is the same as that of the aforementioned sample 12.

[0207] Experimental Example 5

[0208] A withstand voltage test, described later, was performed on multiple active parts of the piezoelectric actuators of each of samples 9 to 13 to obtain an average value. Figure 20 The results are shown in Table 3 below.

[0209] In addition, the withstand voltage test involves varying the voltage applied between the first electrode 60 and the second electrode 80 from 40V to 180V. If the leakage current exceeds 1000nA, the voltage application is stopped, and the voltage exceeding 1000nA is set as the "withstand voltage".

[0210] Table 3

[0211]

[0212] according to Figure 20 As shown in Table 3, by making the valence of the third layer 53 and the second layer 52 the same as in sample 11, the insulation of the vibrating plate 50 is increased, thereby suppressing the leakage current between the multiple active parts 310.

[0213] Furthermore, by making the valence of the third layer 53 and the second layer 52 different, as in samples 12 and 13, the leakage current can be increased and the other active parts 310 can be driven by micro-vibration.

[0214] As described above, the recording head 2, as an example of the piezoelectric device of this application, includes a flow channel forming substrate 10, a vibrating plate 50, and a piezoelectric actuator 300. The flow channel forming substrate 10 is a substrate having a pressure chamber 12 as a recess. The flow channel forming substrate 10, the vibrating plate 50, and the piezoelectric actuator 300 are sequentially laminated along the -Z direction, which is a first direction. Furthermore, the vibrating plate 50 has a first layer 51 comprising silicon as a constituent element. Additionally, the vibrating plate 50 has a second layer 52 disposed between the first layer 51 and the piezoelectric actuator 300, and comprising at least one metal element selected from chromium, titanium, aluminum, tantalum, hafnium, and iridium, and any one or both of silicon nitride as a constituent element. Furthermore, the vibrating plate 50 has a third layer 53 disposed between the second layer 52 and the piezoelectric actuator 300, and comprising zirconium as a constituent element. Furthermore, a fourth layer 200 is provided on the piezoelectric actuator 300 side of the third layer 53, the fourth layer 200 comprising, as a constituent element, at least one metallic element selected from chromium, titanium, aluminum, tantalum, hafnium and iridium and any one or two of silicon nitride.

[0215] By providing the second layer 52 in this manner, the formation of voids (vacancies) at the interface of the third layer 53 on the side of the first layer 51 can be suppressed, thereby preventing moisture from penetrating from the interface of the third layer 53 on the side of the first layer 51. Furthermore, by providing the fourth layer 200, the penetration of moisture from the piezoelectric actuator 300 side of the third layer 53 can be suppressed. Therefore, the embrittlement of the third layer 53 due to moisture can be suppressed, thereby preventing damage such as interlaminar peeling or cracking of the vibrating plate 50.

[0216] Furthermore, in the recording head 2 of this embodiment, it is preferable that the second layer 52 and the fourth layer 200 contain at least one metallic element selected from chromium, titanium, and aluminum. Therefore, by containing metallic elements that are more easily oxidized than zirconium, the reduction of the silicon oxide contained in the first layer 51 can be reduced compared to a structure where the metallic element contained in the second layer 52 is more easily oxidized than zirconium. As a result, the adhesion between the first layer 51 and the third layer 53 can be improved compared to a structure that does not use the second layer 52. Furthermore, the adhesion between the third layer 53 and the fourth layer 200 can also be improved.

[0217] Furthermore, in the recording head 2 of this embodiment, the piezoelectric actuator 300 has a first electrode 60, a piezoelectric layer 70, and a second electrode 80, which are sequentially laminated along the -Z direction, which is a first direction. Preferably, the first electrode 60 and the piezoelectric layer 70 are sandwiched between the third layer 53 and the fourth layer 200, starting from the third layer 53 side. This way, since the second electrode 80 is not sandwiched between the fourth layer 200 and the third layer 53, allowing the fourth layer 200 to contact the second electrode 80 side of the third layer 53, the intrusion of moisture from the interface on the second electrode 80 side of the third layer 53 can be suppressed. Furthermore, by sandwiching the piezoelectric layer 70 between the second layer 52 and the fourth layer 200, the piezoelectric layer 70 can also be protected from the effects of moisture or hydrogen. Furthermore, by not placing the fourth layer 200 on the vibrating plate 50 side of the piezoelectric layer 70, it is possible to suppress the disorder of the crystal structure of the piezoelectric layer 70 due to the fourth layer 200, and the crystal structure of the piezoelectric layer 70 can be controlled by the third layer 53.

[0218] Furthermore, in the recording head 2 of this embodiment, the piezoelectric actuator 300 has a first electrode 60, a piezoelectric layer 70, and a second electrode 80, which are sequentially laminated along the -Z direction, which is a first direction. Preferably, the first electrode 60, the piezoelectric layer 70, and the second electrode 80 are sandwiched between the third layer 53 and the fourth layer 200, starting from the third layer 53 side. Even with the structure of sandwiching the second electrode 80 between the third layer 53 and the fourth layer 200, the fourth layer 200 can suppress the intrusion of moisture from the second electrode 80 side of the third layer 53 of the vibrating plate 50. Furthermore, by sandwiching the piezoelectric layer 70 between the second layer 52 and the fourth layer 200, the piezoelectric layer 70 can also be protected from the effects of moisture or hydrogen. Furthermore, by not placing the fourth layer 200 on the vibrating plate 50 side of the piezoelectric layer 70, it is possible to suppress the disorder of the crystal structure of the piezoelectric layer 70 due to the fourth layer 200, and the crystal structure of the piezoelectric layer 70 can be controlled by the third layer 53.

[0219] Furthermore, in the recording head 2 of this embodiment, it is preferable that the second layer 52 and the fourth layer 200 cover the pressure chamber 12, which is a recess, when viewed from above in the +Z direction, which is opposite to the -Z direction, which is the first direction. This allows for reliable suppression of interlayer delamination and cracking damage to the vibrating plate 50 at the flexible portion opposite the pressure chamber 12.

[0220] Furthermore, in the recording head 2 of this embodiment, it is preferable that the second layer 52 and the fourth layer 200 are made of the same material. Therefore, by using the same material in the second layer 52 and the fourth layer 200, the variety of materials can be reduced compared to using different materials, thus reducing costs.

[0221] Furthermore, in the recording head 2 of this embodiment, it is preferable that the thickness T2 of the second layer 52 is greater than the thickness T4 of the fourth layer 200. In the vibrating plate 50, since moisture is particularly prone to intrusion from the second layer 52 side, by making the thickness T2 of the second layer 52 greater than the thickness T4 of the fourth layer 200, the intrusion of moisture into the interior of the vibrating plate 50 can be effectively reduced.

[0222] Furthermore, in the recording head 2 of this embodiment, it is preferable that the second layer 52 and the third layer 53 have different valences. Therefore, when the active part 310 is selectively driven, a small current flows by causing leakage current in the other undriven active parts 310, thereby suppressing the deterioration deviation of the continuously moving active parts 310 and the other unmoving active parts 310. Thus, deviations in the displacement reduction of multiple active parts 310 can be suppressed, and deviations in the ink droplet ejection characteristics can be suppressed, thereby improving print quality.

[0223] Furthermore, in the recording head 2 of this embodiment, it is preferable that the second layer 52 and the third layer 53 have the same valence. This improves the insulation of the vibrating plate 50, thereby suppressing leakage current and further suppressing the displacement reduction of the active part 310.

[0224] Furthermore, in the recording head 2 of this embodiment, it is preferable that the first layer 51 comprises silicon oxide and the third layer 53 comprises zirconium oxide. Thus, by setting the first layer 51 as an etch stop layer, the pressure chamber 12 can be formed with high precision by etching in the flow channel forming substrate 10. Furthermore, the crystal structure of the piezoelectric layer 70 can be controlled by the surface state of the third layer 53.

[0225] Furthermore, in the recording head 2 of this embodiment, it is preferable that the second layer 52 comprises chromium oxide. By including chromium oxide in the second layer 52, the adhesion between the second layer 52 and the third layer 53 can be improved, thereby suppressing the formation of voids at the interface.

[0226] Furthermore, in the recording head 2 of this embodiment, it is preferable that the chromium oxide contained in the second layer 52 has an amorphous structure. This reduces compressive stress, which is an internal stress of the second layer 52, and also reduces strain at the interface with the first layer 51 or the third layer 53.

[0227] Furthermore, in the recording head 2 of this embodiment, it is preferable that the fourth layer 200 comprises chromium oxide. By including chromium oxide in the fourth layer 200, the adhesion between the fourth layer 200 and the third layer 53 or the second electrode 80, etc., can be improved, thereby suppressing the formation of voids at the interface.

[0228] Furthermore, in the recording head 2 of this embodiment, it is preferable that the chromium oxide contained in the fourth layer 200 has an amorphous structure. This reduces compressive stress, which is an internal stress of the fourth layer 200, and also reduces strain at the interface between the fourth layer 200 and the third layer 53.

[0229] Furthermore, in the recording head 2 of this embodiment, it is preferable that the second layer 52 comprises titanium oxide. By including titanium oxide in the second layer 52, the adhesion between the second layer 52 and the third layer 53 can be improved, thereby suppressing the formation of voids at the interface.

[0230] Furthermore, in the recording head 2 of this embodiment, it is preferable that the titanium oxide contained in the second layer 52 has a rutile structure. This improves the thermal stability of the second layer 52 compared to cases where the titanium oxide contained in the second layer 52 has a rutile structure.

[0231] Furthermore, in the recording head 2 of this embodiment, it is preferable that the fourth layer 200 comprises titanium oxide. By including titanium oxide in the fourth layer 200, the adhesion between the fourth layer 200 and the third layer 53 or the second electrode 80, etc., can be improved, thereby suppressing the formation of voids at the interface.

[0232] Furthermore, in the recording head 2 of this embodiment, it is preferable that the titanium oxide included in the fourth layer 200 has a rutile structure. Thus, by having a rutile structure, the thermal stability of the fourth layer 200 can be improved compared to cases where the titanium oxide included in the fourth layer 200 has other crystalline structures.

[0233] Furthermore, in the recording head 2 of this embodiment, it is preferable that the second layer 52 comprises aluminum oxide. By including aluminum oxide in the second layer 52, the adhesion between the second layer 52 and the third layer 53 can be improved, thereby suppressing the formation of voids at the interface.

[0234] Furthermore, in the recording head 2 of this embodiment, it is preferable that the alumina included in the second layer 52 has an amorphous structure or a trigonal crystal structure. In this way, the alumina becomes a dense film by having an amorphous structure or a trigonal crystal structure, thereby making it difficult for cracks to appear.

[0235] Furthermore, in the recording head 2 of this embodiment, it is preferable that the fourth layer 200 comprises aluminum oxide. In this way, by including aluminum oxide in the fourth layer 200, the adhesion between the fourth layer 200 and the third layer 53 can be improved, thereby suppressing the formation of voids at the interface.

[0236] Furthermore, in the recording head 2 of this embodiment, it is preferable that the alumina included in the fourth layer 200 has an amorphous structure or a trigonal crystal structure. In this way, the alumina becomes a dense film by having an amorphous structure or a trigonal crystal structure, thereby making it difficult for cracks to appear.

[0237] Furthermore, in the recording head 2 of this embodiment, it is preferable that the thickness T2 of the second layer 52 is thinner than the respective thicknesses T1 and T3 of the first layer 51 and the third layer 53. In this way, by making the thickness T2 of the second layer 52 thinner than the thickness T1 of the first layer 51 and the thickness T3 of the third layer 53, the characteristics of the vibrating plate 50 can be easily optimized.

[0238] Furthermore, in the recording head 2 of this embodiment, it is preferable that the thickness T2 of the second layer 52 is in the range of 20 nm or more and 50 nm or less. When the thickness T2 of the second layer 52 is too thin, due to heat treatment during manufacturing, silicon monomers that diffuse from the first layer 51 to the second layer 52 may reach the third layer 53 and form gaps between the second layer 52 and the third layer 53. Furthermore, when the thickness T2 of the second layer 52 is too thick, the heat treatment during the manufacturing of the second layer 52 cannot be fully implemented, or a longer time is required for thermal oxidation, which sometimes has adverse effects on other layers. By setting the thickness T2 of the second layer 52 to the aforementioned range, the diffusion of silicon in the third layer 53 can be suppressed, thereby suppressing the formation of gaps, and the heat treatment of the second layer 52 can be implemented in a shorter time.

[0239] Furthermore, in the recording head 2 of this embodiment, it is preferable that the second layer 52 and the third layer 53 each contain impurities. By containing impurities in the second layer 52, the diffusion of silicon from the first layer 51 to the second layer 52 can be reduced, or even if silicon diffuses from the first layer 51 to the second layer 52, the diffusion of silicon to the third layer 53 can be reduced. In addition, by containing impurities in the third layer 53, the third layer 53 can be softened.

[0240] Furthermore, in the recording head 2 of this embodiment, it is preferable that the impurity content in the second layer 52 is higher than the impurity content in the third layer 53. In this case, the formation of gaps at the interface between the second layer 52 and the third layer 53 or in the third layer 53 is reduced.

[0241] As an example of the liquid jetting device of this application, the inkjet recording device 1 includes the aforementioned recording head 2. Thus, the inkjet recording device 1 can suppress damage such as interlaminar peeling and cracking of the diaphragm 50, thereby suppressing a reduction in its lifespan.

[0242] Other implementation methods

[0243] While various embodiments of the present invention have been described above, the basic structure of the present invention is not limited to the structure described above.

[0244] Here, in Figure 21 The diagram shows a variation of embodiment 1. For example... Figure 21As shown, the vibrating plate 50 has a first layer 51, a second layer 52, and a third layer 53. The second layer 52 has layers 55 and 56. Layers 55 and 56 are laminated sequentially along the -Z direction. Layers 55 and 56 are layers containing the same constituent elements as the second layer 52 described above. However, the composition of the materials constituting layers 55 and 56 is different. Specifically, the types or contents of impurities in layers 55 and 56 are different. These impurities are the same as those in Embodiment 1 described above, such as elements like titanium (Ti), silicon (Si), iron (Fe), chromium (Cr), or hafnium (Hf). The formation of such layers 55 and 56 is carried out, for example, by forming layers composed of monomers of the metal element using sputtering or the like, and adjusting the heat treatment time or temperature to make the distribution of impurities in the thickness direction different for each layer. In addition, the formation of these layers is not particularly limited; for example, CVD or the like can be used to form individual films for each layer.

[0245] When silicon is included as an impurity in layer 56, layer 56 can be understood as the "second layer," and in this case, layer 55 can be understood as the "fourth layer." That is, layer 55 is disposed between the first layer 51 and layer 56, and contains the elements contained in layer 56 and silicon. In this way, by including silicon in layer 55, the diffusion of silicon from the first layer 51 to the second layer 52 can be reduced, or even if silicon diffuses from the first layer 51 to the second layer 52, the diffusion of that silicon to the third layer 53 can be reduced. Furthermore, it also has the effect of making it difficult for gaps to form at the interface between the first layer 51 and the second layer 52.

[0246] Here, although layer 56 may contain silicon, it is preferable that the silicon content in layer 55 is higher than that in layer 56. In other words, it is preferable that the silicon content in layer 56 is lower than that in layer 55. By setting the silicon content relationship between layers 55 and 56 in this way, for example, in the case that layer 55 contains titanium oxide, the crystallization strain caused by silicon in titanium oxide in layer 55 can be reduced. Furthermore, by reducing the silicon content in layer 56, the adhesion between layer 56 and the third layer 53 can be improved.

[0247] Furthermore, by including zirconium as an impurity in layer 56, the diffusion of zirconium from the third layer 53 to layer 55 is reduced, or even if zirconium diffuses from the third layer 53 to layer 55, its diffusion to the first layer 51 is also reduced. Additionally, it has the effect of making it difficult for gaps to form at the interface between the third layer 53 and layer 55.

[0248] Even with this structure, similar to Embodiment 1 described above, it can suppress the intrusion of moisture into the interior of the vibrating plate, especially the intrusion of moisture through the moisture intrusion path R1, and can suppress interlayer delamination and cracking of the vibrating plate 50. Of course, a second layer 52 having such layers 55 and 56 can also be used in Embodiment 2.

[0249] In the role of Figure 21 In the recording head 2 of an example of the piezoelectric device shown, the vibrating plate 50 also has a layer 55, which is a fifth layer disposed between the first layer 51 and the second layer 56 and includes the elements contained in the layer 56 and silicon as constituent elements.

[0250] In addition, Figure 21 In the recording head 2 shown, preferably, the second layer, i.e., layer 56, also contains silicon as a constituent element, and the silicon content in the fourth layer, layer 55, is higher than the silicon content in layer 56. In this way, by setting layer 55 as the fourth layer and setting the silicon content of layers 55 and 56 as described above, it is difficult for gaps to be generated at the interface between the second layer 52 and the third layer 53.

[0251] In addition, Figure 22 The diagram shows a variation of embodiment 1. For example... Figure 22 As shown, the vibrating plate 50 has a first layer 51, a second layer 52, and a third layer 53. The second layer 52 has layers 55, 56, and 57. Layers 55, 56, and 57 are laminated sequentially along the -Z direction. Layers 55, 56, and 57 each contain the same constituent elements as the second layer 52 described above.

[0252] However, the compositions of the materials constituting layers 55, 56, and 57 are different. Specifically, the types or contents of impurities in layers 55, 56, and 57 are different. These impurities are the same as those in Embodiment 1 described above, such as elements like titanium (Ti), silicon (Si), iron (Fe), chromium (Cr), or hafnium (Hf). The formation of these layers 55, 56, and 57 is, for example, performed by forming layers composed of monomers of the metal element using a sputtering method, and adjusting the heat treatment time or temperature to differentiate the distribution of impurities in the thickness direction for each layer. Furthermore, the formation of these layers is not particularly limited; for example, CVD methods can be used to form individual films for each layer.

[0253] Furthermore, when zirconium is included as an impurity in layer 57, layer 56 can be understood as the "second layer," and in this case, layer 57 can be understood as the "fifth layer." That is, layer 57 is disposed between layer 56 and the third layer 53, and contains the elements contained in layer 56 and zirconium. In this way, by including zirconium in layer 57, the diffusion of zirconium from the third layer 53 to the second layer 52 is reduced, or even if zirconium diffuses from the third layer 53 to the second layer 52, the diffusion of zirconium to the first layer 51 is also reduced. In addition, it also has the effect of making it difficult for gaps to be generated at the interface between the third layer 53 and the second layer 52.

[0254] Even with this structure, it can suppress the intrusion of moisture into the interior of the vibrating plate in the same way as in Embodiment 1, especially suppressing the intrusion of moisture through the moisture intrusion path R1, and can suppress interlayer delamination and cracking of the vibrating plate 50. Of course, a second layer 52 having such layers 55, 56 and 57 can also be used in Embodiment 2.

[0255] In the role of Figure 22 In the recording head 2 of an example of the piezoelectric device shown, the vibrating plate 50 also has a layer 57, which is a fifth layer disposed between the second layer 56 and the third layer 53 and includes the elements contained in layer 56 and silicon as constituent elements. In this way, by setting layer 57, it is difficult to create gaps at the interface between the second layer 52 and the third layer 53.

[0256] For example, although the first electrode 60 is set as a separate electrode of the piezoelectric actuator 300 and the second electrode 80 is set as a common electrode of the plurality of piezoelectric actuators 300 in the various embodiments described above, it is not particularly limited to this. The first electrode 60 may also be set as a common electrode of the plurality of piezoelectric actuators 300 and the second electrode 80 may be set as a separate electrode of each piezoelectric actuator 300.

[0257] Furthermore, although the inkjet recording device 1 described above exemplifies a case where the recording head 2 is mounted on the transport body 7 and moves back and forth along the X-axis, which is the main scanning direction, it is not particularly limited to this. For example, the present invention can also be applied to a so-called line recording device in which the recording head 2 is fixed and only the medium S, such as paper, moves along the Y-axis, which is the sub-scanning direction, to perform printing.

[0258] Furthermore, although the inkjet recording head was described as an example of a liquid jetting head and an inkjet recording device as an example of a liquid jetting device in the above embodiments, the present invention is broadly applicable to liquid jetting heads and liquid jetting devices as a whole, and can of course be applied to liquid jetting heads or liquid jetting devices that jet liquids other than ink. Other liquid jetting heads include, for example, various recording heads used in image recording devices such as printers, color material jetting heads used in the manufacture of color filters such as liquid crystal displays, electrode material jetting heads used in the electrode formation of organic EL (Electroluminescence) displays, FED (Surface Emitting Displays), etc., and biological organic matter jetting heads used in the manufacture of biochips, and can also be applied to liquid jetting devices equipped with the liquid jetting heads mentioned above.

[0259] Furthermore, this invention is not limited to liquid jetting heads, such as inkjet printing heads, but can also be applied to piezoelectric devices such as ultrasonic devices, motors, pressure sensors, thermoelectric elements, and ferroelectric elements. Moreover, piezoelectric devices also include completed systems utilizing these piezoelectric devices, such as liquid jetting devices utilizing the aforementioned liquid jetting heads, ultrasonic sensors utilizing the aforementioned ultrasonic devices, robots using the aforementioned motors as drive sources, IR sensors utilizing the aforementioned thermoelectric elements, and ferroelectric memory utilizing ferroelectric elements.

[0260] Symbol Explanation

[0261] 1…Inkjet recording device (liquid jet device); 2…Inkjet recording head (liquid jet head); 3…Liquid container; 4…Conveyor mechanism; 4a…Conveyor roller; 5…Control unit; 6…Moving mechanism; 7…Conveyor body; 8…Conveyor belt; 10…Flow channel forming substrate (substrate); 11…Block; 12…Pressure chamber (recess); 15…Connecting plate; 16…Nozzle connecting channel; 17…First manifold section; 18…Second manifold section; 19…Supply connecting channel; 20…Nozzle plate; 20a…Liquid jet surface; 21…Nozzle; 30…Protective substrate; 31…Holding part; 32…Through hole; 40…Outer shell component; 41…Recess; 42…Third… Manifold section; 43…Connection port; 44…Inlet port; 45…Moldable substrate; 46…Sealing film; 47…Fixed substrate; 48…Opening; 49…Moldable part; 50…Vibrating plate; 51…First layer; 52…Second layer; 53…Third layer; 55-57…Layer; 60…First electrode; 70…Piezoelectric layer; 71…Recess; 80…Second electrode; 91…Individual lead electrode; 92…Common lead electrode; 100…Manifold; 120…Wiring substrate; 121…Drive circuit; 200…Fourth layer; 300…Piezoelectric actuator; 310…Active part; 400…Gap; R1, R2, R3…Moisture intrusion path; S…Medium.

Claims

1. A piezoelectric device, characterized in that, have: A substrate having a recess; Vibrating plate; piezoelectric actuator, The substrate, the vibrating plate, and the piezoelectric actuator are laminated sequentially along a first direction. The vibrating plate has the following characteristics: The first layer contains silicon as a constituent element; The second layer is disposed between the first layer and the piezoelectric actuator, and comprises, as a constituent element, at least one metallic element selected from chromium, titanium, aluminum, tantalum, hafnium and iridium and any one or both of silicon nitride. The third layer, which is disposed between the second layer and the piezoelectric actuator, includes zirconium as a constituent element. A fourth layer is provided on the piezoelectric actuator side of the third layer, the fourth layer comprising, as a constituent element, at least one metallic element selected from chromium, titanium, aluminum, tantalum, hafnium, and iridium, and any one or two of silicon nitride. The piezoelectric actuator has a first electrode, a piezoelectric layer, and a second electrode. The first electrode, the piezoelectric layer, and the second electrode are sequentially laminated along the first direction. Between the third layer and the fourth layer, the first electrode and the piezoelectric layer are sandwiched from the side of the third layer.

2. A piezoelectric device, characterized in that, have: A substrate having a recess; Vibrating plate; piezoelectric actuator, The substrate, the vibrating plate, and the piezoelectric actuator are laminated sequentially along a first direction. The vibrating plate has the following characteristics: The first layer contains silicon as a constituent element; The second layer is disposed between the first layer and the piezoelectric actuator, and comprises, as a constituent element, at least one metallic element selected from chromium, titanium, aluminum, tantalum, hafnium and iridium and any one or both of silicon nitride. The third layer, which is disposed between the second layer and the piezoelectric actuator, includes zirconium as a constituent element. A fourth layer is provided on the piezoelectric actuator side of the third layer, the fourth layer comprising, as a constituent element, at least one metallic element selected from chromium, titanium, aluminum, tantalum, hafnium, and iridium, and any one or two of silicon nitride. The piezoelectric actuator has a first electrode, a piezoelectric layer, and a second electrode. The first electrode, the piezoelectric layer, and the second electrode are sequentially laminated along the first direction. Between the third layer and the fourth layer, starting from the third layer side, are the first electrode, the piezoelectric layer, and the second electrode.

3. The piezoelectric device as described in claim 1 or 2, characterized in that, When viewed from above in a direction opposite to the first direction, the second and fourth layers cover the recess.

4. The piezoelectric device as described in claim 1 or 2, characterized in that, The second layer and the fourth layer are made of the same material.

5. The piezoelectric device as described in claim 1 or 2, characterized in that, The second layer is thicker than the fourth layer.

6. The piezoelectric device as described in claim 1 or 2, characterized in that, The valences of the second layer and the third layer are different.

7. The piezoelectric device as described in claim 1 or 2, characterized in that, The second layer and the third layer have the same valence.

8. The piezoelectric device as described in claim 1 or 2, characterized in that, The second layer contains at least one of chromium oxide, titanium oxide, and aluminum oxide.

9. The piezoelectric device as claimed in claim 8, characterized in that, The fourth layer contains at least one of chromium oxide, titanium oxide, and aluminum oxide.

10. The piezoelectric device as claimed in claim 9, characterized in that, The fourth layer contains chromium oxide with an amorphous structure.

11. The piezoelectric device as claimed in claim 9, characterized in that, The fourth layer contains titanium oxide with a rutile structure.

12. The piezoelectric device as claimed in claim 9, characterized in that, The fourth layer contains alumina with an amorphous structure or a trigonal crystal system.

13. The piezoelectric device as described in claim 1 or 2, characterized in that, The thickness of the second layer is thinner than the thickness of the first layer and the thickness of the third layer.

14. The piezoelectric device as described in claim 1 or 2, characterized in that, The thickness of the second layer is in the range of 20nm or more and 50nm or less.

15. The piezoelectric device as described in claim 1 or 2, characterized in that, The vibrating plate also has a fifth layer, which is disposed between the first layer and the second layer and includes, as a constituent element, the elements contained in the second layer and silicon.

16. The piezoelectric device as claimed in claim 15, characterized in that, The second layer also contains silicon as a constituent element. The silicon content in the fifth layer is higher than that in the second layer.

17. The piezoelectric device as claimed in claim 1 or 2, characterized in that, The vibrating plate also has a sixth layer, which is disposed between the second layer and the third layer and includes, as a constituent element, the elements contained in the second layer and silicon.

18. The piezoelectric device as claimed in claim 1 or 2, characterized in that, The impurity content in the second layer is higher than that in the third layer.

19. A liquid injection head, characterized in that, The piezoelectric device comprising any one of claims 1 to 18 The piezoelectric actuator, the vibrating plate, and the flow channel forming substrate are laminated along a first direction in the order of the flow channel forming substrate, the vibrating plate, and the piezoelectric actuator, wherein the vibrating plate vibrates by being driven by the piezoelectric actuator, and the flow channel forming substrate is provided with a pressure chamber that applies pressure to the liquid by the vibration of the vibrating plate.

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