Piezoelectric device, liquid ejection head and liquid ejection apparatus

Abstract

To provide a piezoelectric device for suppressing moisture from invading into the inside of a diaphragm, and suppressing generation of damages such as delamination and cracks of the diaphragm, and to provide a liquid injection head.SOLUTION: A piezoelectric device includes a substrate 10 having a recess 12, a diaphragm 50, and a piezoelectric actuator 300. The diaphragm has a first layer 51 containing silicon, a second layer 52 arranged between the first layer 51 and the piezoelectric actuator, and containing any one of or both of at least one metal element selected from the group consisting of chromium, titanium, aluminum, tantalum, hafnium, and iridium, and silicon nitride, a third layer 53 arranged between the second layer and the piezoelectric actuator, and containing zirconium, and a fourth layer 200 at a piezoelectric actuator side of the third layer, containing any one of or both of at least one metal element selected from the group consisting of chromium, titanium, aluminum, tantalum, hafnium and iridium, and silicon nitride.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a piezoelectric device having a vibration plate and a piezoelectric actuator provided on a substrate, a liquid ejection head for ejecting liquid, and a liquid ejection apparatus. [Background technology]

[0002] Inkjet recording heads are known as liquid ejection heads, which are one type of electronic device. The inkjet recording head includes a substrate provided with a pressure chamber communicating with a nozzle, a vibration plate provided on one side of the substrate, and a piezoelectric actuator provided on the vibration plate. The piezoelectric actuator is driven to cause a pressure change in the ink in the pressure chamber, causing ink droplets to be ejected from the nozzle. For example, Patent Document 1 discloses a vibration 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 silicon single crystal substrate. The insulating film is formed by thermally oxidizing a layer of simple zirconium formed on the elastic film by a sputtering method or the like. [Prior art documents] [Patent documents]

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

[0004] If moisture penetrates into the diaphragm, the zirconium oxide becomes brittle due to the intrusion, causing damage such as delamination and cracks between the elastic film and the insulating film.

[0005] In particular, in high temperature and high humidity environments, moisture penetrates into the diaphragm from the interface between the elastic film and the insulator film at the end face of the piezoelectric actuator, the interface between the second electrode and the insulator film at the end face of the piezoelectric actuator, and the surface of the second electrode on the side opposite the substrate of the piezoelectric actuator. [Means for solving the problem]

[0006] An aspect of the present invention that solves the above problem comprises: a substrate having a recess; The insulating film has a first layer including silicon as a constituent element, a second layer including at least one metal element selected from the group consisting of chromium, titanium, aluminum, tantalum, hafnium, and iridium as a constituent element, and silicon nitride, or both, stacked along a first direction, and a third layer including zirconium as a constituent element. A vibration plate and a piezoelectric actuator are provided. The piezoelectric actuator has a first electrode, a piezoelectric layer, and a second electrode, and the first electrode, the piezoelectric layer, and the second electrode are laminated in this order in the first direction. The third layer Above a fourth layer including at least one metal element selected from the group consisting of chromium, titanium, aluminum, tantalum, hafnium, and iridium, and / or silicon nitride, the fourth layer is conductive, and the first electrode, the piezoelectric layer, and the fourth layer are sandwiched between the third layer and the second electrode in the first direction, from the third layer side; The piezoelectric device is characterized by the above-mentioned. Another aspect of the present invention is a piezoelectric device comprising: a substrate having a recess; a vibration plate having a first layer containing silicon as a constituent element, a second layer containing at least one metal element selected from the group consisting of chromium, titanium, aluminum, tantalum, hafnium, and iridium as a constituent element, or both of silicon nitride, and a third layer containing zirconium as a constituent element, and a piezoelectric actuator, the piezoelectric actuator having a first electrode, a piezoelectric layer, and a second electrode, the first electrode, the piezoelectric layer, and the second electrode being stacked in this order in the first direction, a fourth layer containing at least one metal element selected from the group consisting of chromium, titanium, aluminum, tantalum, hafnium, and iridium as a constituent element, or both of silicon nitride, above the third layer in the first direction, and the first electrode, the piezoelectric layer, and the second electrode being sandwiched between the third layer and the fourth layer in the first direction from the third layer side.

[0007] Another aspect of the present invention is A piezoelectric device according to any one of the above aspects, wherein the recess is a pressure chamber that applies pressure to a liquid by vibration of the vibration plate. The liquid ejection head is characterized in that

[0008] Furthermore, another aspect of the present invention is a liquid-jet apparatus comprising the liquid-jet head according to the above aspect. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of an ink jet recording apparatus according to a first embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of the recording head according to the first embodiment. [Diagram 3] 3 is a plan view of a flow path forming substrate of the recording head according to the first embodiment. FIG. [Figure 4] 1 is a cross-sectional view of a recording head according to a first embodiment. [Diagram 5] 1 is a cross-sectional view of a recording head according to a first embodiment. [Figure 6] 5A to 5C are diagrams illustrating a method for manufacturing the piezoelectric device according to the first embodiment. [Figure 7] FIG. 11 is a cross-sectional view of a recording head according to a second embodiment. [Figure 8] This is a STEM image of sample 1. [Figure 9] 1 is a STEM image of sample 2. [Figure 10] 1 is a STEM image of sample 3. [Figure 11] FIG. 1 is a diagram showing the results of analysis of Sample 1 by SIMS. [Figure 12] FIG. 13 is a diagram showing the analysis results of Sample 2 by SIMS. [Figure 13] FIG. 13 is a diagram showing the analysis results of Sample 3 by SIMS. [Figure 14] FIG. 13 is a diagram showing the results of analysis of Sample 4 by RBS. [Figure 15] FIG. 13 is a diagram showing the analysis results of Sample 6 by SIMS. [Figure 16] FIG. 1 is a cross-sectional view of Comparative Example 1. [Figure 17] FIG. 11 is a cross-sectional view of Comparative Example 2. [Figure 18] FIG. 11 is a cross-sectional view of Comparative Example 3. [Figure 19] FIG. 11 is a cross-sectional view of Comparative Example 4. [Figure 20] 13 is a graph showing the results of leakage current. [Figure 21] FIG. 4 is a cross-sectional view showing a modified example of the first embodiment. [Figure 22] FIG. 4 is a cross-sectional view showing a modified example of the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in detail below based on the embodiments. However, the following description shows one aspect of the present invention, and can be arbitrarily modified within the scope of the present invention. In each drawing, the same reference numerals indicate the same members, and the description is omitted as appropriate. In each drawing, X, Y, and Z represent three spatial axes that are mutually orthogonal. In this specification, the directions along these axes are the X direction, the Y direction, and the Z direction. The direction in which the arrow in each drawing points is the positive (+) direction, and the opposite direction to the arrow is the negative (-) direction. In addition, the three spatial axes of X, Y, and Z, which are not limited to the positive and negative directions, are described as the X axis, the Y axis, and the Z axis. In each of the following embodiments, the "first direction" is the -Z direction, and the "second direction" is the +Z direction, as an example. In addition, viewing in a direction along the Z axis is called "planar view."

[0011] Typically, the Z axis is a vertical axis, and the +Z direction corresponds to the downward direction in the vertical direction. However, the Z axis does not have to be a vertical axis. Also, the X axis, the Y axis, and the Z axis are typically perpendicular to each other, but are not limited to this, and may intersect at an angle within a range of 80° to 100°, for example.

[0012] (Embodiment 1) FIG. 1 is a diagram illustrating a schematic diagram of an ink jet recording apparatus 1, which is an example of a liquid ejecting apparatus according to a first embodiment of the present invention.

[0013] 1, an inkjet recording device 1, which is an example of a liquid ejection device, is a printing device that ejects and impacts ink, which is a type of liquid, onto a medium S, such as printing paper, as ink droplets, and prints images, etc., by forming an arrangement of dots on the medium S. Note that the medium S can be made of any material, such as a resin film or cloth, in addition to recording paper.

[0014] In the following, of the three spatial axes X, Y, and Z, the movement direction of the recording head 2 described later (in other words, the main scanning direction) is defined as the X axis, the transport direction of the medium S perpendicular to the main scanning direction is defined as the Y axis, a plane parallel to the nozzle surface in which the nozzles 21 of the recording head 2 (see FIG. 2) are formed is defined as the XY plane, the direction intersecting the nozzle surface, i.e., the direction perpendicular to the XY plane in this embodiment, is defined as the Z axis, and ink droplets are ejected in the +Z direction along the Z axis.

[0015] The inkjet recording device 1 includes a liquid container 3, a transport mechanism 4 that feeds out the medium S, a control unit 5 that serves as a control section, a moving mechanism 6, and an inkjet recording head 2 (hereinafter also simply referred to as the recording head 2).

[0016] The liquid container 3 individually stores multiple types (e.g., multiple colors) of ink to be ejected from the recording head 2. Examples of the liquid container 3 include a cartridge that is detachable from the inkjet recording device 1, a bag-shaped ink pack made of a flexible film, and an ink tank that can be refilled with ink. Although not specifically shown, the liquid container 3 stores multiple types of ink with different colors and types.

[0017] Although not specifically shown, the control unit 5 includes, for example, 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 each element of the inkjet recording device 1, i.e., the transport mechanism 4, the movement mechanism 6, the recording head 2, etc., by the control device executing a program stored in the storage device.

[0018] The transport mechanism 4 is controlled by the control unit 5 to transport the medium S in the Y direction, and has, for example, a transport roller 4a. Note that the transport mechanism 4 that transports the medium S is not limited to the transport roller 4a, and may transport the medium S by a belt or a drum.

[0019] The moving mechanism 6 is controlled by the control unit 5 to reciprocate the recording head 2 in the +X direction and the -X direction along the X axis.

[0020] Specifically, the movement mechanism 6 of this embodiment includes a conveyor 7 and a conveyor belt 8. The conveyor 7 is a substantially box-shaped structure, a so-called carriage, that houses the recording head 2, and is fixed to the conveyor belt 8. The conveyor belt 8 is an endless belt that is stretched along the X-axis. The conveyor belt 8 rotates under the control of the control unit 5, so that the recording head 2 moves back and forth together with the conveyor 7 in the +X and -X directions along a guide rail (not shown). It is also possible to mount the liquid container 3 on the conveyor 7 together with the recording head 2.

[0021] The recording head 2 ejects ink supplied from the liquid container 3 as ink droplets from each of the multiple nozzles 21 in the +Z direction onto the medium S under the control of the control unit 5. The ejection of ink droplets from the recording head 2 is performed 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 movement mechanism 6, thereby forming an image in ink on the surface of the medium S, that is, printing is performed. Here, the recording head 2 is an example of a "piezoelectric device."

[0022] Fig. 2 is an exploded perspective view of an ink jet recording head 2 which is an example of a liquid jet head of this embodiment. Fig. 3 is a plan view of a flow path forming substrate 10 of the recording head 2. Fig. 4 is a cross-sectional view of the recording head 2 taken along line AA' in Fig. 3. Fig. 5 is a cross-sectional view of the recording head 2 taken along line BB' in Fig. 3.

[0023] As shown in the figure, the recording head 2 of this embodiment includes a flow path forming substrate 10 as an example of a "substrate." The flow path forming substrate 10 is made of a silicon substrate, a glass substrate, an SOI substrate, or any of various ceramic substrates.

[0024] In the flow path 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 on a straight line along the +X direction so that their positions in the +Y direction are the same. The pressure chambers 12 adjacent to each other in the +X direction are partitioned by partition walls 11. Of course, the arrangement of the pressure chambers 12 is not particularly limited to this, and for example, the pressure chambers 12 arranged side by side in the +X direction may be arranged in a so-called staggered arrangement in which every other pressure chamber 12 is shifted in the +Y direction.

[0025] Furthermore, the shape of the pressure chamber 12 in this embodiment when viewed in the +Z direction may be a rectangle, a parallelogram, or a rectangle with semicircular ends at both ends in the longitudinal direction, i.e., a rounded rectangle, an ellipse, an egg, or other oval shape, a circle, a polygon, etc. This pressure chamber 12 corresponds to a "recess" provided in the "substrate".

[0026] On the +Z direction side of the flow passage forming substrate 10, a communication plate 15 and a nozzle plate 20 are laminated in this order.

[0027] The communication plate 15 is provided with a nozzle communication passage 16 that connects the pressure chamber 12 and the nozzle 21 .

[0028] The communication plate 15 is provided with a first manifold portion 17 and a second manifold portion 18 which constitute a part of a manifold 100 which serves as a common liquid chamber to which the multiple pressure chambers 12 are commonly connected. The first manifold portion 17 is provided so as to penetrate the communication plate 15 in the +Z direction. The second manifold portion 18 is provided so as to open on the surface on the +Z direction side, without penetrating the communication plate 15 in the +Z direction.

[0029] Furthermore, in the communicating plate 15, a supply communication passage 19 that communicates with the Y-axis end of the pressure chamber 12 is provided independently for each pressure chamber 12. The supply communication passage 19 communicates between the second manifold portion 18 and the pressure chamber 12, and supplies ink in the manifold 100 to the pressure chamber 12.

[0030] As the communicating plate 15, a silicon substrate, a glass substrate, an SOI substrate, various ceramic substrates, a metal substrate such as a stainless steel substrate, or the like can be used. Note that it is preferable that the communicating plate 15 is made of a material having approximately the same thermal expansion coefficient as the flow path forming substrate 10. By using materials having approximately the same thermal expansion coefficient for the flow path forming substrate 10 and the communicating plate 15 in this manner, it is possible to reduce the occurrence of warping due to heat caused by the difference in thermal expansion coefficient.

[0031] The nozzle plate 20 is provided on the side of the communication plate 15 opposite to the flow path forming substrate 10, that is, on the surface on the +Z direction side.

[0032] The nozzle plate 20 is formed with nozzles 21 that communicate with each pressure chamber 12 via the nozzle communication passage 16. In this embodiment, the nozzles 21 are arranged in two rows, one in a row along the +X direction, and the other in a row spaced apart in the +Y direction. That is, the nozzles 21 in each row are arranged so that their positions in the +Y direction are the same. Of course, the arrangement of the nozzles 21 is not particularly limited to this, and for example, the nozzles 21 may be arranged in a so-called staggered arrangement, in which every other nozzle 21 arranged in the +X direction is arranged at a position shifted in the +Y direction. As such a nozzle plate 20, a silicon substrate, a glass substrate, an SOI substrate, various ceramic substrates, a metal substrate such as a stainless steel substrate, an organic material such as a polyimide resin, or the like can be used. Note that it is preferable that the nozzle plate 20 is made of a material having a thermal expansion coefficient substantially equal to that of the communication plate 15. By using materials having a thermal expansion coefficient substantially equal to that of the communication plate 15 in this way, it is possible to reduce the occurrence of warping due to heat caused by the difference in thermal expansion coefficient.

[0033] A vibration plate 50 and a piezoelectric actuator 300 are laminated in this order on the surface of the flow path forming substrate 10 on the -Z direction side. That is, the flow path forming substrate 10, the vibration plate 50, and the piezoelectric actuator 300 are laminated in this order in the -Z direction. A fourth layer 200 is provided on the piezoelectric actuator 300 side of the vibration plate 50. The vibration plate 50, the piezoelectric actuator 300, and the fourth layer 200 will be described in detail later.

[0034] As shown in FIG. 2 and FIG. 4, a protective substrate 30 having approximately the same size as the flow path forming substrate 10 is bonded to the surface of the flow path forming substrate 10 in the -Z direction. The protective substrate 30 has a holding portion 31 which is a space for protecting the piezoelectric actuator 300. The holding portion 31 is provided independently for each row of the piezoelectric actuators 300 arranged side by side in the +X direction, and two holding portions 31 are formed side by side in the +Y direction. In addition, the protective substrate 30 is provided with a through hole 32 penetrating in the +Z direction between the two holding portions 31 arranged side by side in the +Y direction. The ends of the individual lead electrodes 91 and the common lead electrode 92 drawn from the electrodes of the piezoelectric actuators 300 are extended so as to be exposed in the through hole 32, and the individual lead electrodes 91 and the common lead electrode 92 are electrically connected to the wiring substrate 120 in the through hole 32.

[0035] 4, a case member 40 is fixed onto the protective substrate 30. The case member 40 defines, together with the flow path forming substrate 10, a manifold 100 that communicates with the multiple pressure chambers 12. The case member 40 has substantially the same shape as the above-mentioned communicating plate 15 in a plan view, and is joined to the protective substrate 30 and also to the above-mentioned communicating plate 15. In this embodiment, the case member 40 is joined to the communicating plate 15. Although not particularly shown, the case member 40 is also joined to the protective substrate 30.

[0036] Such a case member 40 has a recess 41 on the protective substrate 30 side, the recess 41 being deep enough to accommodate the flow path forming substrate 10 and the protective substrate 30. The recess 41 has an opening area larger than the surface of the protective substrate 30 bonded to the flow path forming substrate 10. The opening surface of the recess 41 on the nozzle plate 20 side is sealed by the communication plate 15 while the flow path forming substrate 10 and the like are accommodated in the recess 41. As a result, a third manifold portion 42 is defined by the case member 40 and the flow path forming substrate 10 on the outer periphery of the flow path forming substrate 10. The manifold 100 of this embodiment is configured by the first manifold portion 17 and the second manifold portion 18 provided on the communication plate 15, and the third manifold portion 42 defined by the case member 40 and the flow path forming substrate 10. The manifold 100 is provided continuously across the +X direction in which the pressure chambers 12 are arranged side by side, and the supply communication passages 19 that communicate between the pressure chambers 12 and the manifold 100 are arranged side by side in the +X direction.

[0037] Further, a compliance substrate 45 is provided on the surface of the communication plate 15 on the +Z direction side where the first manifold portion 17 and the second manifold portion 18 open. This compliance substrate 45 seals the openings of the first manifold portion 17 and the second manifold portion 18 on the liquid ejection surface 20a side. In this embodiment, such a compliance substrate 45 includes a sealing film 46 made of a flexible thin film, and a fixed substrate 47 made of a hard material such as metal. Since the region of the fixed substrate 47 facing the manifold 100 is an opening 48 that is completely removed in the thickness direction, one surface of the manifold 100 is a compliance portion 49 that is a flexible portion sealed only by the sealing film 46 that has flexibility.

[0038] The diaphragm 50 and the piezoelectric actuator 300 of this embodiment will be described.

[0039] As shown in FIG. 4 and FIG. 5, the piezoelectric actuator 300 includes a first electrode 60, a piezoelectric layer 70, and a second electrode 80, which are sequentially stacked from the +Z direction side, which is the vibration plate 50 side, toward the -Z direction side. The piezoelectric actuator 300 is a pressure generating means that generates a pressure change in the ink in the pressure chamber 12. Such a piezoelectric actuator 300 is also called a piezoelectric element, and refers to a portion including the first electrode 60, the piezoelectric layer 70, and the second electrode 80. In addition, a portion where a piezoelectric strain occurs in the piezoelectric layer 70 when a voltage is applied between the first electrode 60 and the second electrode 80 is called an active portion 310. In contrast, a portion where no piezoelectric strain occurs in the piezoelectric layer 70 is called an inactive portion. That is, the active portion 310 refers to a portion where the piezoelectric layer 70 is 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. That is, the piezoelectric actuator 300 has a plurality of active sections 310 formed therein. In general, one of the electrodes of the active sections 310 is an individual electrode independent of each other for each active section 310, and the other electrode is configured as a common electrode common to the plurality of active sections 310. In this embodiment, the first electrode 60 constitutes an individual electrode, and the second electrode 80 constitutes a common electrode. Of course, the first electrode 60 may constitute a common electrode, and the second electrode 80 may constitute an individual electrode. In this piezoelectric actuator 300, a portion facing the pressure chamber 12 in the Z-axis direction becomes a flexible portion, and a portion outside the pressure chamber 12 becomes a non-flexible portion.

[0040] Specifically, as shown in Figs. 3 to 5, the first electrode 60 is separated for each pressure chamber 12 to form an individual electrode independent for each active section 310. The first electrode 60 is formed with a width narrower than the width of the pressure chamber 12 in the +X direction. That is, in the +X direction, the end of the first electrode 60 is located inside the region facing the pressure chamber 12. Also, as shown in Fig. 4, the end of the first electrode 60 on the nozzle 21 side is disposed outside the pressure chamber 12 in the Y axis. An individual lead electrode 91, which is a lead-out wiring, is connected to the end of the first electrode 60 disposed outside the pressure chamber 12 in the Y axis.

[0041] The first electrode 60 is 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), titanium oxide (TiO X ), titanium tungsten (TiW), etc. can be used.

[0042] As shown in Figs. 3 to 5, the piezoelectric layer 70 has a predetermined width in the +Y direction and is continuously provided over the +X direction. The width of the piezoelectric layer 70 in the +Y direction is longer than the length of the pressure chamber 12 in the +Y direction, which is the longitudinal direction of the pressure chamber 12. Therefore, on both sides of the pressure chamber 12 in the +Y direction and the -Y direction, the piezoelectric layer 70 is extended to the outside of the region facing the pressure chamber 12. The end of such a piezoelectric layer 70 on the opposite side to the nozzle 21 in the Y axis is located outside the end of the first electrode 60. That is, the end of the first electrode 60 on the opposite side to the nozzle 21 is covered by the piezoelectric layer 70. In addition, the end of the piezoelectric layer 70 on the nozzle 21 side is located inside 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. As described above, the individual lead electrode 91 made of gold (Au) or the like is connected to the end of the first electrode 60 that extends to the outside of the piezoelectric layer .

[0043] Further, the piezoelectric layer 70 is formed with recesses 71 corresponding to the partition walls 11. The width of the recesses 71 in the +X direction is the same as or wider than the width of the partition walls 11. In this embodiment, the width of the recesses 71 in the +X direction is wider than the width of the partition walls 11. This suppresses the rigidity of the parts of the vibration plate 50 facing both ends of the pressure chambers 12 in the +X direction and the -X direction, that is, the arms of the vibration plate 50, and thus the piezoelectric actuator 300 can be displaced satisfactorily. The recesses 71 may be provided penetrating the piezoelectric layer 70 in the +Z direction, which is the thickness direction, or may be provided halfway through the thickness direction of the piezoelectric layer 70 without penetrating the piezoelectric layer 70 in the +Z direction. That is, the piezoelectric layer 70 may be completely removed from the bottom surface of the recesses 71 in the +Z direction, or a part of the piezoelectric layer 70 may remain.

[0044] Such a piezoelectric layer 70 is made of a piezoelectric material made of a composite oxide having 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 as the piezoelectric material, a piezoelectric layer 70 having a relatively large piezoelectric constant d31 can be obtained.

[0045] In a composite oxide having a perovskite structure represented by the general formula ABO3, 12 oxygen atoms are coordinated to the A site, and 6 oxygen atoms are coordinated to the B site to form an octahedron. In this embodiment, lead (Pb) is located at the A site, and zirconium (Zr) and titanium (Ti) are located at the B site.

[0046] The piezoelectric material is not limited to the above PZT. Other elements may be included in the A site or B site. For example, the piezoelectric material may be a perovskite material such as barium zirconate titanate (Ba(Zr,Ti)O3), lead lanthanum zirconate titanate ((Pb,La)(Zr,Ti)O3), lead magnesium zirconate titanate (Pb(Zr,Ti)(Mg,Nb)O3), or lead zirconate titanate niobate containing silicon (Pb(Zr,Ti,Nb)O3).

[0047] Alternatively, the piezoelectric material may be a material with a reduced Pb content, so-called low-lead material, or a material that does not use Pb, so-called lead-free material. If a low-lead material is used as the piezoelectric material, the amount of Pb used can be reduced. Also, if a lead-free material is used as the piezoelectric material, Pb can be eliminated. Therefore, the use of low-lead or lead-free materials as piezoelectric materials can reduce the environmental impact.

[0048] An example of a lead-free piezoelectric material is a BFO-based material containing bismuth ferrite (BFO; BiFeO3). In BFO, bismuth (Bi) is located at the A site, and iron (Fe) is located at the B site. Other elements may 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) may be added to BFO.

[0049] Another example of a lead-free piezoelectric material is a KNN-based material containing potassium sodium niobate (KNN; KNaNbO3). Other elements may 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) may be added to KNN.

[0050] The piezoelectric material includes a material having a composition with a partial deficiency of an element, a material having a composition with an excess of a part of an element, and a material having a composition with a part of an element substituted with another element. As long as the basic characteristics of the piezoelectric layer 70 are not changed, the piezoelectric material according to this embodiment includes a material having a composition that is deviated from the stoichiometric composition due to a deficiency or excess, and a material having a part of an element substituted with another element. Of course, the piezoelectric material that can be used in this embodiment is not limited to the above-mentioned materials containing Pb, Bi, Na, K, etc.

[0051] As shown in FIG. 2 to FIG. 5, the second electrode 80 is provided continuously on the −Z direction side of the piezoelectric layer 70, which is the opposite side to the first electrode 60, and constitutes a common electrode common to a plurality of active sections 310. The second electrode 80 is provided continuously over the +X direction so that the +Y direction has a predetermined width. The second electrode 80 is also provided on the inner surface of the recess 71, that is, on the side surface of the recess 71 of the piezoelectric layer 70 and on the vibration plate 50 which is the bottom surface of the recess 71. Of course, the second electrode 80 may be provided only on a part of the inner surface of the recess 71, or may not be provided over the entire inner surface of the recess 71. That is, in this embodiment, the second electrode 80 is not provided on the end portions of the piezoelectric actuator 300 on the +Y direction side and the −Y direction side on the flow path forming substrate 10, and the vibration plate 50 is provided exposed on the surface in the −Z direction.

[0052] The second electrode 80 may be made of a material such as a precious metal material, such as iridium (Ir), platinum (Pt), palladium (Pd), or gold (Au), or a conductive oxide, such as lanthanum nickel oxide (LNO). The second electrode 80 may be made of a laminate of a plurality of materials. The second electrode 80 is preferably made of a material containing iridium (Ir) and titanium (Ti). In this embodiment, the second electrode 80 is a laminated electrode of iridium (Ir) and titanium (Ti).

[0053] Furthermore, an individual lead electrode 91, which is an extraction wiring, is drawn out from the first electrode 60. A common lead electrode 92, which is an extraction wiring, is drawn out from the second electrode 80. The ends of the individual lead electrodes 91 and the common lead electrode 92 opposite to the ends connected to the piezoelectric actuator 300 are connected to the wiring board 120, which is flexible as described above. A drive circuit 121 having a switching element for driving the piezoelectric actuator 300 is mounted on the wiring board 120.

[0054] As shown in FIG. 5, the vibration plate 50 has a first layer 51, a second layer 52, and a third layer 53, which are laminated in this order in the -Z direction. That is, the vibration plate 50 has a first layer 51, a second layer 52 arranged between the first layer 51 and the piezoelectric actuator 300, and a third layer 53 arranged between the second layer 52 and the piezoelectric actuator 300. The first layer 51 is arranged on the side of the vibration plate 50 closest to the flow path forming substrate 10, that is, on the +Z direction side, and is in contact with the surface of the flow path forming substrate 10 on the -Z direction side. The third layer 53 is arranged on the side of the vibration plate 50 closest to the -Z direction, and is in contact with the piezoelectric actuator 300. The second layer 52 is interposed between the first layer 51 and the third layer 53. 4 and 5, for convenience of explanation, the interface between the layers constituting the vibration plate 50 is clearly shown, but the interface does not have to be clear, and for example, the constituent materials of two adjacent layers may be mixed near the interface between the two layers. The vibration plate 50 having such a first layer 51, second layer 52, and third layer 53 is provided continuously over the entire surface of the flow path forming substrate 10 on the -Z direction side.

[0055] The first layer 51 is a layer containing silicon (Si) as a constituent element. Specifically, the first layer 51 is an elastic film made of, for example, silicon oxide (SiO2). Here, the first layer 51 may contain small amounts of elements such as zirconium (Zr), titanium (Ti), iron (Fe), chromium (Cr), or hafnium (Hf) as impurities, in addition to silicon oxide and its constituent elements. Such impurities have the effect of softening silicon oxide (SiO2).

[0056] In this manner, the first layer 51 of the present embodiment contains, for example, silicon oxide. Such a first layer 51 can be formed with better productivity by thermally oxidizing the flow path forming substrate 10 made of a silicon single crystal substrate, as compared with the case of forming the first layer 51 by a sputtering method.

[0057] Silicon in first layer 51 may exist in the form of an oxide, or may exist in the form of an element, a nitride, an oxynitride, etc. Impurities in first layer 51 may be elements that are inevitably mixed in when first layer 51 is formed, or may be elements that are intentionally mixed in first layer 51.

[0058] The thickness T1 of the first layer 51 is determined according to the thickness T and width W of the diaphragm 50. The thickness T1 of the first layer 51 is preferably within a range of, for example, 100 nm or more and 20,000 nm or less, and more preferably within a range of 500 nm or more and 1,500 nm or less.

[0059] The third layer 53 is a layer containing zirconium (Zr) as a constituent element. Specifically, the third layer 53 is an insulating film made of, for example, zirconium oxide (ZrO2). Here, in addition to zirconium oxide and its constituent elements, the third layer 53 may 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 the zirconium oxide (ZrO2).

[0060] Thus, the third layer 53 contains, for example, zirconium oxide. Such a third layer 53 can be obtained, for example, by forming a layer of simple zirconium by sputtering or the like, and then thermally oxidizing the layer. Therefore, when forming the third layer 53, the third layer 53 can be easily obtained with a desired thickness. In addition, since zirconium oxide has excellent electrical insulation properties, mechanical strength, and toughness, the characteristics of the diaphragm 50 can be improved by including zirconium oxide in the third layer 53. In addition, for example, when the piezoelectric layer 70 is made of lead zirconate titanate, the third layer 53 contains zirconium oxide, which has the advantage that the piezoelectric layer 70 that is preferentially oriented in the (100) plane with a high orientation rate can be easily obtained when forming the piezoelectric layer 70.

[0061] Zirconium in the third layer 53 may exist in the form of an oxide, or may exist in the form of an element, a nitride, an oxynitride, or the like. The impurities in the third layer 53 may be elements that are inevitably mixed in when the third layer 53 is formed, or may be elements that are intentionally mixed in the third layer 53. For example, the impurities are impurities contained in a zirconium target used when the third layer 53 is formed by a sputtering method.

[0062] The thickness T3 of the third layer 53 is determined according to the thickness T and width W of the diaphragm 50. The thickness T3 of the third layer 53 is preferably within the range of 100 nm to 20000 nm, for example.

[0063] The second layer 52 is interposed between the first layer 51 and the third layer 53. This prevents contact between the first layer 51 and the third layer 53. Therefore, compared to a configuration in which the first layer 51 and the third layer 53 are in contact with each other, reduction of silicon oxide in the first layer 51 by zirconium in the third layer 53 is reduced.

[0064] The second layer 52 functions as a moisture barrier film that prevents voids from being formed at the interface with the third layer and prevents moisture from entering the interface between the second layer and the third layer.

[0065] Such a second layer 52 is a layer containing at least one metal element selected from the group consisting of chromium (Cr), titanium (Ti), aluminum (Al), tantalum (Ta), hafnium (Hf) and iridium (Ir) as a constituent element, and / or a layer containing silicon and nitrogen, such as silicon nitride (SiN) having a chemical formula of Si3N4. The metal element of such a second layer 52 may exist in the form of an oxide, or may exist in the form of a simple substance, a nitride or an oxynitride. The second layer 52 may contain only one of the above-mentioned metal elements, or may contain two or more of them. The second layer 52 may contain both the above-mentioned metal element and silicon nitride.

[0066] The second layer 52 is preferably a layer containing a metal element that is less easily oxidized than zirconium, and the second layer 52 is preferably composed of, for example, an oxide of the metal element. In other words, the second layer 52 preferably contains a metal element having a higher oxide formation free energy than zirconium. The metal element preferably contains any one of chromium, titanium, and aluminum, and the second layer 52 is preferably composed of an oxide of the metal element. The table relationship of the oxide formation free energy can be evaluated, for example, based on the known Ellingham diagram.

[0067] Since the second layer 52 contains a metal element that is less easily oxidized than zirconium, the reduction of silicon oxide contained in the first layer 51 can be reduced compared to a configuration in which the metal element contained in the second layer 52 is more easily oxidized than zirconium, that is, compared to a configuration in which the oxide formation free energy of the metal element contained in the second layer 52 is smaller than the oxide formation free energy of zirconium. As a result, the adhesion between the first layer 51 and the third layer 53 can be increased compared to a configuration in which the second layer 52 is not used.

[0068] Furthermore, since the second layer 52 is made of oxides of chromium, titanium, and aluminum, the adhesion between the first layer 51 and the third layer 53 can be increased more than with simple substances, nitrides, and carbon-based materials.

[0069] Chromium is less easily oxidized than silicon. In other words, the free energy of formation of an oxide of chromium is greater than the free energy of formation of an oxide of silicon. Therefore, when chromium is contained as a metal element in the second layer 52, the reduction of silicon oxide contained in the first layer can be reduced compared to when the second layer 52 does not contain a metal element that is less easily oxidized than silicon.

[0070] Furthermore, when the second layer 52 contains chromium, for example, chromium forms an oxide, and contains chromium oxide. Such a second layer 52 is obtained by forming a layer of simple chromium by a sputtering method or the like, and then thermally oxidizing the layer. Therefore, when forming the second layer 52, the second layer 52 of the desired thickness can be easily obtained.

[0071] Here, the chromium oxide contained in the second layer 52 may be in any of a polycrystalline, amorphous, or single crystalline state. However, when the chromium oxide contained in the second layer 52 has an amorphous structure, that is, is in an amorphous state, 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 single crystalline 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.

[0072] The oxide of titanium or aluminum is easily moved by heat. Therefore, when the second layer 52 contains titanium or aluminum as a metal element, the adhesive strength between the first layer 51 or the third layer 53 and the second layer 52 can be increased by the anchor effect or chemical bond of the oxide of the metal element. Moreover, titanium easily forms an oxide together with silicon or zirconium. Therefore, when the second layer 52 contains titanium as a metal element, the adhesive strength between the first layer 51 and the second layer 52 can be increased by forming an oxide together with silicon, or the adhesive strength between the second layer 52 and the third layer 53 can be increased by forming an oxide together with zirconium.

[0073] Furthermore, when the second layer 52 contains titanium, for example, titanium constitutes an oxide, and the second layer 52 contains titanium oxide. Such a second layer 52 is obtained by forming a layer of simple titanium by a sputtering method or the like, and then thermally oxidizing the layer. Therefore, when forming the second layer 52, the second layer 52 of the desired thickness can be easily obtained.

[0074] Here, the titanium oxide contained in the second layer 52 may be in any state of polycrystal, amorphous, or single crystal. However, the titanium oxide contained in the second layer 52 is preferably in a polycrystal or single crystal state, and in particular, preferably has a rutile structure as a crystal structure. Among the crystal structures that titanium oxide can have, the rutile structure is the most stable, and is unlikely to change to a polymorph such as anatase or blockite even if it moves due to heat. Therefore, the thermal stability of the second layer 52 can be improved compared to when the crystal structure of the titanium oxide contained in the second layer 52 is another crystal structure.

[0075] Furthermore, when the second layer 52 contains aluminum, for example, aluminum constitutes an oxide, and the second layer 52 contains aluminum oxide. Such a second layer 52 is obtained by forming a layer of simple aluminum by a sputtering method or the like, and then thermally oxidizing the layer. Therefore, when forming the second layer 52, the second layer 52 of the desired thickness can be easily obtained.

[0076] Here, the aluminum oxide contained in the second layer 52 may be in any state of polycrystal, amorphous or single crystal, and when in a polycrystal or single crystal state, it has a trigonal crystal structure.

[0077] Further, in addition to the above-mentioned metal elements, the second layer 52 may contain small amounts of elements such as titanium (Ti), silicon (Si), iron (Fe), chromium (Cr) or hafnium (Hf) as impurities. For example, the impurities are elements contained in the first layer 51 or the third layer 53. The impurities exist, for example, in the form of oxides together with the metal elements of the second layer 52. Such impurities have the effect of reducing the diffusion of silicon from the first layer 51 to the second layer 52, or suppressing the diffusion of silicon to the third layer 53 even if the silicon diffuses from the first layer 51 to the second layer 52.

[0078] From this viewpoint, it is preferable that each of the second layer 52 and the third layer 53 contains impurities. When each of the second layer 52 and the third layer 53 contains impurities, the risk of cracking of the diaphragm can be reduced by making each of the second layer 52 and the third layer 53 softer than when each of the second layer 52 and the third layer 53 does not contain impurities.

[0079] Here, the content of impurities in the second layer 52 is preferably higher than the content of impurities in the third layer 53. In other words, it is preferable that the concentration peak of impurities in the thickness direction of the laminate consisting 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, if the concentration peak is located in the third layer 53, the crystal structure in the third layer 53 will be distorted by the impurities. For this reason, gaps will be formed at the interface between the second layer 52 and the third layer 53 or in the third layer 53, which may increase the risk of cracks in the diaphragm 50.

[0080] The above-mentioned metal elements in the second layer 52 may exist in the form of an oxide, or may exist in the form of an element, a nitride, an oxynitride, etc. Furthermore, the impurities in the second layer 52 may be elements that are inevitably mixed in when the second layer 52 is formed, or may be elements that are intentionally mixed in the second layer 52.

[0081] Furthermore, the thickness T2 of the second layer 52 is determined according to the thickness T and width W of the diaphragm 36, and is not particularly limited, but is preferably thinner than both the thickness T1 of the first layer 51 and the thickness T3 of the third layer 53. In this case, there is an advantage that the characteristics of the diaphragm 36 can be easily optimized.

[0082] Specifically, the thickness T2 of the second layer 52 is preferably in the range of 20 nm to 50 nm, and more preferably in the range of 25 nm to 40 nm, when the metal element contained in the second layer 52 is titanium. When the metal element contained in the second layer 52 is aluminum, the thickness T2 is preferably in the range of 20 nm to 50 nm, and particularly preferably in the range of 20 nm to 35 nm. When the metal element contained in the second layer 52 is chromium, the thickness T2 is preferably in the range of 1 nm to 50 nm, and more preferably in the range of 2 nm to 30 nm. From this, it can be seen that the preferable conditions are satisfied as long as the thickness T2 of the second layer 52 is in the range of 20 nm to 50 nm, regardless of whether the metal element contained in the second layer 52 is titanium, aluminum, or chromium. By having the thickness T2 in such a range, the effect of increasing the adhesion between the first layer 51 and the third layer 53 by the second layer 52 can be suitably exhibited.

[0083] On the other hand, if the thickness T2 is too thin, the effect of the second layer 52 in reducing the diffusion of elemental silicon from the first layer 51 tends to decrease depending on the type of metal element contained in the second layer 52. For example, when the second layer 52 is made of titanium oxide, if the thickness T2 is too thin, elemental silicon diffused from the first layer 51 to the second layer 52 may reach the third layer 53 depending on the conditions of the heat treatment during production. On the other hand, if the thickness T2 is too thick, the heat treatment during production of the second layer 52 may not be performed sufficiently, or the thermal oxidation may take a long time, which may adversely affect other layers.

[0084] By providing the second layer 52 in this manner, it is possible to prevent the occurrence of voids at the interface between the second layer 52 and the third layer 53. Therefore, it is possible to prevent moisture from penetrating into the interface between the second layer 52 and the third layer 53 from the end face side of the piezoelectric actuator 300. Therefore, it is possible to prevent the zirconium of the third layer 53 from becoming embrittled due to moisture, and it is possible to prevent delamination between the third layer 53 and the layers above and below the third layer 53, and damage such as cracks in the third layer 53.

[0085] In this embodiment, since the second layer 52 is provided continuously over the entire surface of the flow path forming substrate 10 on the -Z direction side, the second layer 52 is provided to cover the pressure chamber 12 in a plan view from the +Z direction. That is, the second layer 52 is provided at a position overlapping the pressure chamber 12 in the +Z direction. Incidentally, the second layer 52 only needs to be provided in at least a portion overlapping the pressure chamber 12 in a plan view from the +Z direction, and does not have to be provided in an area other than the pressure chamber 12, for example, in a portion overlapping the partition wall 11. Even in this case, the second layer 52 can suppress moisture from penetrating into the interface with the third layer 53 in the portion overlapping the pressure chamber 12.

[0086] Moreover, a fourth layer 200 is provided on the third layer 53 of the vibration plate 50, that is, on the -Z direction opposite to the first layer 51 in the Z axis. The fourth layer 200 is provided over substantially the entire surface of the flow path forming substrate 10 on the -Z direction side.

[0087] The fourth layer 200 is provided directly above the third layer 53 in the -Z direction in a portion other than the piezoelectric actuator 300, for example, in the recess 71. That is, the fourth layer 200 contacts the third layer 53. In addition, in the portion where the piezoelectric actuator 300 is provided, the first electrode 60 and the piezoelectric layer 70 are sandwiched between the third layer 53 and the fourth layer 200. That is, the second electrode 80 is provided 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 laminated in this order in the -Z direction. In other words, when the fourth layer 200 is provided on the piezoelectric layer 70 side of the third layer 53, this includes a configuration in which the fourth layer 200 is provided directly on the third layer 53, as well as a configuration in which another member is interposed between the fourth layer 200 and the third layer 53, in other words, a configuration in which the fourth layer 200 is provided above the third layer 53.

[0088] This fourth layer 200 functions as a moisture-shielding film that prevents moisture from penetrating the interface between the third layer 53 and layers further towards the -Z direction, and also prevents moisture from penetrating from the -Z direction surface side of the second electrode 80.

[0089] The fourth layer 200 may be made of the same material as the second layer 52. That is, the fourth layer 200 is a layer containing at least one metal element selected from the group consisting of chromium, titanium, aluminum, tantalum, hafnium, and iridium (Ir) as a constituent element, and / or a layer containing silicon and nitrogen, such as silicon nitride (SiN) having a chemical formula of Si3N4. The metal element of the fourth layer 200 may exist in the form of an oxide, or may exist in the form of a simple substance, a nitride, or an oxynitride. The fourth layer 200 may contain only one of the above-mentioned metal elements, or may contain two or more of them. The fourth layer 200 may contain both the above-mentioned metal elements and silicon nitride. In particular, the fourth layer 200 is preferably made of an oxide or a nitride of the metal element contained in the second electrode 80. In this way, since the fourth layer 200 is composed of an oxide or nitride of the metal element contained in the second electrode 80, the adhesion between the fourth layer 200 and the second electrode 80 can be improved since the fourth layer 200 and the second electrode 80 are made of materials containing the same metal element.

[0090] Moreover, 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, by making the thickness T4 of the fourth layer 200 relatively thin, it is possible to suppress a decrease in the electric field strength applied to the piezoelectric layer 70 by the second electrode 80, and to suppress a decrease in displacement due to a decrease in the electric field strength.

[0091] In addition, the fourth layer 200 of this embodiment can also protect the piezoelectric layer 70 from moisture and hydrogen by sandwiching the piezoelectric layer 70 between itself and the second layer 52. By not providing the fourth layer 200 on the vibration plate 50 side of the piezoelectric layer 70, the crystal structure of the piezoelectric layer 70 is prevented from being disturbed by the fourth layer 200, and the crystal structure of the piezoelectric layer 70 can be controlled by the third layer 53.

[0092] In addition, by using the same material as the second layer 52 for the fourth layer 200, it is not necessary to prepare a plurality of materials, which facilitates manufacturing and reduces costs.

[0093] Moreover, it is preferable that the thickness T2 of the second layer 52 is thicker than the thickness T4 of the fourth layer 200. That is, it is preferable that T2>T4 is satisfied. Here, this is because moisture is more likely to penetrate into the vibration plate 50 from the first layer 51 side, which is lower than the third layer 53, than from the second electrode 80 side, which is upper than the third layer 53. For this reason, by making the thickness T2 of the second layer 52 disposed on the first layer 51 side of the third layer 53 relatively thick, it is possible to make it difficult for moisture to penetrate from the second layer 52 side, which is lower than the third layer 53. Moreover, 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 deformation of the vibration plate 50 and the piezoelectric actuator 300 from being significantly hindered by the fourth layer 200.

[0094] The thickness T4 of the fourth layer 200 is preferably within a range of, for example, 5 nm to 20 nm, in order to facilitate displacement. For example, if the thickness T4 of the fourth layer 200 is too thin, the moisture blocking function is reduced, and if the thickness T4 of the fourth layer is too thick, the displacement of the vibration plate 50 and the piezoelectric actuator 300 is hindered as described above.

[0095] In this embodiment, since the fourth layer 200 is provided continuously over substantially the entire surface of the -Z direction side of the flow path forming substrate 10, the fourth layer 200 is provided to cover the pressure chamber 12 in a plan view from the +Z direction. That is, the fourth layer 20 is provided at a position overlapping the pressure chamber 12 in a plan view from the +Z direction. Incidentally, the fourth layer 200 only needs to be provided in at least a portion overlapping the pressure chamber 12 in a plan view from the +Z direction, and does not have to be provided in an area other than the pressure chamber 12, for example, in a portion overlapping the partition wall 11. Even in this case, the fourth layer 200 can suppress moisture from entering the third layer 53 in the portion overlapping the pressure chamber 12.

[0096] 6A to 6C are diagrams for explaining a method for manufacturing a piezoelectric device. Hereinafter, a method for manufacturing a piezoelectric device will be explained with reference to FIG. 6, taking the case of manufacturing a recording head as an example.

[0097] 6, the method for manufacturing the recording head includes a substrate preparation step S10, a diaphragm formation step S20, a piezoelectric actuator and 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 below in order.

[0098] The substrate preparation step S10 is a step of preparing a substrate to become the flow path forming substrate 10. The substrate is, for example, a silicon single crystal substrate.

[0099] The diaphragm forming process S20 is a process for forming the above-mentioned diaphragm 50, and is performed after the substrate preparing process S 10. In the diaphragm forming process S20, a first layer forming process S21, a second layer forming process S22, and a third layer forming process S23 are performed in this order.

[0100] The first layer forming step S21 is a step of forming the above-mentioned first layer 51. In the first layer forming step S21, for example, one surface of the silicon single crystal substrate prepared in the substrate preparation step S10 is thermally oxidized to form the first layer 51 made of silicon oxide (SiO2). Note that the method of forming the first layer 51 is not particularly limited to this, and the first layer 51 may be formed by, for example, a sputtering method, a chemical vapor deposition method (CVD method), a vacuum deposition method (PVD method), an atomic layer deposition method (ALD method), a spin coating method, or the like.

[0101] The second layer forming step S22 is a step of forming the above-mentioned second layer 52. In the second layer forming step S22, for example, a layer of chromium, titanium or aluminum is formed on the first layer 51 by a sputtering method, and the layer is thermally oxidized to form the second layer 52 composed of chromium oxide, titanium oxide or aluminum oxide. Note that the method of forming the second layer 52 is not particularly limited to this, and for example, a CVD method, a PVD method, an ALD method, a spin coating method, or the like may be used. Also, the thermal oxidation in the second layer forming step S22 may be performed together with the thermal oxidation in the third layer forming step S23 described later.

[0102] The third layer forming step S23 is a step of forming the aforementioned third layer 53. In the third layer forming step S23, for example, a zirconium layer is formed on the second layer 52 by a sputtering method, and the layer is thermally oxidized to form the third layer 53 made of zirconium oxide. The diaphragm 50 is formed by the first layer forming step S21, the second layer forming step S22, and the third layer forming step S23. Note that the formation of the third layer 53 is not particularly limited thereto, and for example, a CVD method, a PVD method, an ALD method, a spin coating method, or the like may be used.

[0103] The piezoelectric actuator and fourth layer forming step S30 is a step of forming the piezoelectric actuator 300 and the fourth layer 200 described above, and is performed after the third layer forming step S23. The piezoelectric actuator and fourth layer forming step S30 includes a first electrode forming step S31, a piezoelectric layer forming step S32, a fourth layer forming step S33, and a second electrode forming step S34.

[0104] The first electrode formation step S31 is a step of forming the above-mentioned first electrode 60. In the first electrode formation step S31, the first electrode 60 is formed by a known film formation technique such as a sputtering method, and a known processing technique using a photolithography method, etching, or the like.

[0105] The piezoelectric layer forming step S32 is a step of forming the piezoelectric layer 70 described above. In the piezoelectric layer forming step S32, for example, a precursor layer of the piezoelectric layer is formed by a sol-gel method, and the precursor layer is fired and crystallized to form the piezoelectric layer 70. Of course, the method of forming the piezoelectric layer 70 is not particularly limited to this, and the piezoelectric layer 70 may be formed by, for example, a metal-organic decomposition (MOD) method, a sputtering method, a laser ablation method, or the like. In the piezoelectric layer forming step S32, the piezoelectric layer 70 is formed into a predetermined shape by a known processing technique using photolithography, etching, or the like.

[0106] The fourth layer forming step S33 is a step of forming the aforementioned fourth layer 200. In the fourth layer forming step S33, for example, a layer of chromium, titanium or aluminum is formed on the first layer 51 by a sputtering method, and the layer is thermally oxidized to form the second layer 52 composed of chromium oxide, titanium oxide or aluminum oxide. Note that the method of forming the second layer 52 is not particularly limited to this, and a CVD method, a PVD method, an ALD method, a spin coating method, or the like may also be used.

[0107] The second electrode formation step S34 is a step of forming the above-mentioned second electrode 80. In the second electrode formation step S34, the second electrode 80 is formed by a known film formation technique such as a sputtering method, and a known processing technique using a photolithography method, etching, etc. As a result, the piezoelectric actuator 300 having the first electrode 60, the piezoelectric layer 70, and the second electrode 80, and the fourth layer 200 are formed.

[0108] After the piezoelectric actuator 300 is formed, if necessary, one of the two surfaces of the substrate after the formation, other than the surface on which the piezoelectric actuator 300 is formed, is ground by CMP (chemical mechanical polishing) or the like to flatten that surface or adjust the thickness of the substrate.

[0109] The pressure chamber forming step S40 is a step of forming the pressure chamber 12 described above, and is performed after the piezoelectric actuator and fourth layer forming step S30. In the pressure chamber forming step S40, for example, the pressure chamber 12 is formed by anisotropically etching a surface of the silicon single crystal substrate after the piezoelectric actuator 300 is formed, which is different from the surface on which the piezoelectric actuator 300 is formed. As a result, the flow path forming substrate 10 in which the pressure chamber 12 is formed is obtained. At this time, for example, an aqueous potassium hydroxide solution (KOH) or the like is used as an etching liquid for anisotropically etching the silicon single crystal substrate. At this time, the first layer 51 functions as a stop layer that stops the anisotropic etching.

[0110] After the pressure chamber forming step S40, the recording head 2 is manufactured by appropriately performing steps such as bonding the protective substrate 30, the communication plate 15, etc. to the flow passage forming substrate 10 with an adhesive.

[0111] (Embodiment 2) 7 is a cross-sectional view of a main part of an ink jet recording head 2, which is an example of a liquid jet head according to embodiment 2 of the present invention. Note that the same members as those in the above-mentioned embodiment are given the same reference numerals and overlapping descriptions will be omitted.

[0112] As shown in FIG. 7, a vibration plate 50, a piezoelectric actuator 300, and a fourth layer 200 are provided on the −Z direction side of the flow path forming substrate 10.

[0113] The diaphragm 50 includes a first layer 51, a second layer 52, and a third layer 53, similar to the first embodiment described above.

[0114] 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. That is, the fourth layer 200 is provided on the -Z direction side of the second electrode 80. Of course, in a portion of the third layer 53 where the second electrode 80 is not provided, the fourth layer 200 is provided directly on the third layer 53.

[0115] The recording head 2 having such a fourth layer 200 can be formed by switching the order of the fourth layer forming step S33 and the second electrode forming step S34 in the above-mentioned piezoelectric actuator and fourth layer forming step S30. In other words, the fourth layer 200 can be formed over the second electrode 80 and the diaphragm 50 by performing the second electrode forming step S34 to form the second electrode 80 and then performing the fourth layer forming step S33.

[0116] (Sample 1) One surface of a silicon single crystal substrate having a surface orientation (110) was thermally oxidized to form a first layer 51 made of silicon oxide and having a thickness of 1460 nm.

[0117] Next, a film made of zirconium was formed on the first layer 51 by sputtering, and the film was thermally oxidized at 900° C. to form the third layer 53 made of zirconium oxide and having a thickness of 400 nm. In this manner, a diaphragm consisting of first layer 51 and third layer 53 was manufactured.

[0118] (Sample 2) A second layer 52 made of aluminum oxide and having a thickness of 20 nm was formed on the first layer 51, which was the same as that of the above-mentioned sample 1, by atomic layer deposition (ALD).

[0119] Next, a third layer 53 similar to that of sample 1 was formed on the second layer 52 .

[0120] In this manner, diaphragm 50 consisting of first layer 51, second layer 52 and third layer 53 was manufactured.

[0121] (Sample 3) A film made of titanium was formed by sputtering on the same first layer 51 as in the above-mentioned sample 1, and the film was thermally oxidized to form a second layer 52 made of titanium oxide and having a thickness of 40 nm.

[0122] Next, a third layer 53 similar to that of sample 1 was formed on the second layer 52 .

[0123] In this manner, diaphragm 50 consisting of first layer 51, second layer 52 and third layer 53 was manufactured.

[0124] (Test Example 1) The cross sections of Samples 1 to 3 were observed by a scanning transmission electron microscope (STEM), and the results are shown in Figures 8 to 10.

[0125] Samples 1 to 3 were exposed to a deuterium oxide atmosphere at 45° C. and 95% RH or higher for 24 hours or more, and analyzed by SIMS (secondary ion mass spectrometry). The results are shown in FIGS. 11 to 13.

[0126] 9 and 10, in Sample 2 and Sample 3, no gap was generated between the second layer 52 and the third layer 53. In contrast, in Sample 1, a gap 400 was generated between the first layer 51 and the third layer 53, as shown in FIG.

[0127] 12 and 13, in Sample 2 and Sample 3, moisture did not penetrate from the outside into the interface between the second layer 52 and the third layer 53. In contrast, in Sample 1, moisture penetrated from the outside into between the first layer 51 and the third layer 53, as shown in Fig. 11. That is, moisture penetrates into the diaphragm 50 from the interface between the third layer 53 and a layer further in the +Z direction than the third layer 53. This is referred to as moisture penetration path R1.

[0128] Furthermore, from this result, it can be seen that by providing the second layer 52, the formation of the gap 400 at the interface between the second layer 52 and the third layer 53 can be suppressed, and the intrusion of moisture into the interface can be suppressed.

[0129] (Sample 4) A piezoelectric actuator 300 was formed on the vibration plate 50 of sample 1, the piezoelectric actuator 300 having a first electrode 60 of platinum (Pt), a piezoelectric layer 70 of lead zirconate titanate (PZT; Pb(Zr,Ti)O3), and a second electrode 80 of iridium (Ir) and titanium (Ti).

[0130] (Test Example 2) Sample 4 was exposed to a deuterium vapor atmosphere at a temperature of 45°C and a humidity of 95% or more for 24 hours or more, and analyzed by Rutherford backscattering spectroscopy (RBS). The results are shown in Figure 14. In Figure 14, H represents hydrogen and D represents deuterium.

[0131] As shown in FIG. 14, deuterium D was detected between the third layer 53 and the second electrode 80. Since deuterium is almost not present in nature, the results shown in FIG. 14 show that deuterium has penetrated between the third layer 53 and the second electrode 80 from the outside. In other words, moisture penetrates into the diaphragm 50 from the second electrode 80 side. The moisture penetration path from the second electrode 80 side of the diaphragm 50 can be considered to be both the interface between the third layer 53 and the layer on the -Z direction side of the third layer 53 at the end face of the diaphragm 50, and the surface of the second electrode 80 in the -Z direction. The moisture penetration 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 penetration path R2. In addition, the moisture penetration path from the surface side of the second electrode 80 of the third layer 53 in the -Z direction is referred to as moisture penetration path R3.

[0132] (Sample 5) On the diaphragm 50 of Sample 1, a second electrode 80 was formed by laminating iridium and titanium in this order.

[0133] (Sample 6) On the second electrode 80 of Sample 5, a fourth layer 200 made of titanium nitride was formed.

[0134] (Test Example 3) Sample 6 was exposed to a deuterium oxide atmosphere at 45° C. and 95% RH or higher for 24 hours or more, and then analyzed by SIMS (secondary ion mass spectrometry). The results are shown in FIG.

[0135] As shown in FIG. 15, fourth layer 200 can prevent moisture from entering inside diaphragm 50, that is, third layer 53.

[0136] (Sample 7) On the diaphragm 50 of sample 1, a fourth layer 200 made of iridium oxide and having a thickness of 10 nm was formed by sputtering.

[0137] Next, the second electrode 80 , which was the same as that of Sample 5 , was formed on the fourth layer 200 .

[0138] (Sample 8) On the same diaphragm 50 and second electrode 80 as in Sample 5, a fourth layer 200 made of aluminum oxide and having a thickness of 30 nm was formed by atomic layer deposition (ALD).

[0139] (Test Example 4) Scratch tests were performed on Samples 5, 7, and 8 before and after they were immersed in pure water for 30 minutes or more. The results are shown in Table 1 below.

[0140] [Table 1]

[0141] 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, the scratch strength significantly decreased after immersion in pure water, which suggests that the third layer 53 was embrittled by moisture. Note that a decrease of 5% or more in scratch strength after immersion in pure water was determined to indicate moisture intrusion.

[0142] Based on the results of these Test Examples 1 to 4, a comprehensive evaluation was performed on the structures of Embodiments 1 and 2 and the comparative structures of Comparative Examples 1 to 4. The structures of Comparative Examples 1 to 4 are shown in Figs. 16 to 19 and Table 2 below.

[0143] As shown in FIG. 16, Comparative Example 1 had a structure in which the second layer 52 and the fourth layer 200 were not provided.

[0144] As shown in FIG. 17, Comparative Example 2 had a structure in which the second layer 52 was not provided, and only the fourth layer 200 of the first embodiment was provided.

[0145] As shown in FIG. 18, Comparative Example 3 had a structure in which the second layer 52 was not provided, and only the fourth layer 200 of the second embodiment was provided.

[0146] As shown in FIG. 19, Comparative Example 4 had a structure in which the fourth layer 200 was not provided and the second layer 52 was provided.

[0147] [Table 2]

[0148] As shown in Table 2, in the structure provided with the second layer 52 and the fourth layer 200 of the first and second embodiments, the intrusion of moisture into the inside of the diaphragm 50 can be suppressed, and the embrittlement of the third layer 53 due to the intruded moisture can be suppressed. Therefore, delamination between the third layer 53 and the layers above and below the third layer 53 and cracks in the diaphragm 50 can be suppressed. Note that moisture is more likely to infiltrate through the moisture intrusion path R1 than through the moisture intrusion paths R2 and R3, so the structure of Comparative Example 4 can suppress the intrusion of moisture more effectively than the structure of Comparative Example 1. Therefore, the structure of Comparative Example 4 can suppress delamination, cracks, and the like in the diaphragm 50 more effectively than Comparative Examples 1 to 3.

[0149] In addition, the second layer 52 and the third layer 53 preferably 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 within the range of -0.5≦X≦+0.5. By making the valence of the second layer 52 and the third layer 53 the same in this way, the insulation of the entire vibration plate 50 is increased, so that the leakage current between the multiple active parts 310 of the piezoelectric actuator 300 can be suppressed. Therefore, the leakage current can be suppressed, and the displacement reduction of the active part 310 due to the leakage current can be reduced.

[0150] For example, when the third layer 53 is made of zirconium oxide (ZrO2) with a valence of +4, the second layer 52 is preferably made of a constituent element such as titanium, hafnium, or iridium, which has the same valence of +4 and is stable.

[0151] Moreover, it is preferable that the second layer 52 and the third layer 53 have different valences. Here, 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 within the range of X<-0.5, +0.5≦X. In other words, 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 a valence of +4.5 or more.

[0152] 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 are more likely to move toward the -Z direction side of the third layer 53. Therefore, when the active sections 310 are selectively driven, a leakage current is generated in the other active sections 310 that are not driven, causing a minute current to flow, thereby suppressing the variation in deterioration between the active sections 310 that are continuously driven and the other active sections 310 that are not driven. Therefore, the variation in the decrease in displacement of the multiple active sections 310 can be suppressed, and the variation in the ejection characteristics of the ink droplets can be suppressed, thereby improving the print quality.

[0153] For example, when the third layer 53 is made of zirconium oxide (ZrO2) with a valence of +4, the second layer 52 preferably uses, as a constituent element, chromium, aluminum, tantalum, or the like, which has a valence different from that of the third layer 53.

[0154] (Sample 9) One surface of a silicon single crystal substrate having a surface orientation (110) was thermally oxidized to form a first layer 51 made of silicon oxide and having a thickness of 1460 nm.

[0155] Next, a film made of zirconium was formed on the first layer 51 by sputtering, and the film was thermally oxidized at 900° C. to form the third layer 53 made of zirconium oxide and having a thickness of 400 nm. In this way, the diaphragm 50 made up of the first layer 51 and the third layer 53 was formed.

[0156] Next, a first electrode 60, a piezoelectric layer 70, and a second electrode 80 were formed on the vibration plate 50 and patterned to form a piezoelectric actuator 300 having the same shape as in the first embodiment.

[0157] Thereafter, the other surface of the silicon single crystal substrate was anisotropically etched using an aqueous potassium hydroxide solution (KOH) or the like as an etching solution, thereby forming a recess having the first layer 51 as its bottom surface.

[0158] (Sample 10) The thickness of the third layer 53 was 645 nm, but other than that, the sample was the same as Sample 9.

[0159] (Sample 11) A film made of titanium was formed on the first layer 51 of sample 9 by sputtering, and the film was thermally oxidized to form a second layer 52 made of titanium oxide and having a thickness of 40 nm.

[0160] Moreover, the thickness of the third layer 53 formed on the second layer 52 was set to 250 nm, and other than that, the thickness was the same as that of the above-mentioned sample 9.

[0161] (Sample 12) A film made of chromium was formed on the first layer 51 of sample 9 by sputtering, and the film was thermally oxidized to form a second layer 52 made of chromium oxide and having a thickness of 40 nm.

[0162] Moreover, the thickness of the third layer 53 formed on the second layer 52 was set to 500 nm, and other than that, the thickness was the same as that of the above-mentioned sample 9.

[0163] (Sample 13) The thickness of the third layer 53 was set to 250 nm, but other than that, the thickness was the same as that of the above-mentioned sample 12.

[0164] (Test Example 5) A withstand voltage test, which will be described later, was carried out to obtain an average value for a plurality of active parts of the piezoelectric actuator of each of Samples 9 to 13. The results are shown in FIG.

[0165] In the withstand voltage test, the voltage applied between the first electrode 60 and the second electrode 80 is varied from 40V to 180V, and when the leakage current exceeds 1000nA, the voltage application is stopped. The voltage exceeding 1000nA is taken as the "withstand voltage."

[0166] [Table 3]

[0167] The results shown in FIG. 20 and Table 3 indicate that by matching the valence of the third layer 53 and the second layer 52 as in sample 11, the insulation properties of the diaphragm 50 are improved and leakage current between multiple active portions 310 can be suppressed.

[0168] 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 to drive the other active portions 310 to produce micro-vibrations.

[0169] As described above, the recording head 2, which is an example of the piezoelectric device of the present invention, includes the flow path forming substrate 10, which is a substrate having the pressure chamber 12, which is a recess, the vibration plate 50, and the piezoelectric actuator 300, and the flow path forming substrate 10, the vibration plate 50, and the piezoelectric actuator 300 are laminated in this order in the -Z direction, which is the first direction. The vibration plate 50 also has a first layer 51 containing silicon as a constituent element. The vibration plate 50 also has a second layer 52, which is disposed between the first layer 51 and the piezoelectric actuator 300 and contains at least one metal element selected from the group consisting of chromium, titanium, aluminum, tantalum, hafnium, and iridium, and silicon nitride, or both, as constituent elements. The vibration plate 50 also has a third layer 53, which is disposed between the second layer 52 and the piezoelectric actuator 300 and contains zirconium as a constituent element. The fourth layer 200 is located on the piezoelectric actuator 300 side of the third layer 53 and contains, as a constituent element, either or both of at least one metal element selected from the group consisting of chromium, titanium, aluminum, tantalum, hafnium, and iridium and silicon nitride.

[0170] By providing the second layer 52 in this manner, it is possible to suppress the formation of voids at the interface of the third layer 53 on the first layer 51 side, and to suppress the intrusion of moisture from the interface of the third layer 53 on the first layer 51 side. Furthermore, by providing the fourth layer 200, it is possible to suppress the intrusion of moisture from the piezoelectric actuator 300 side of the third layer 53. Therefore, it is possible to suppress the third layer 53 from becoming embrittled due to moisture, and to suppress the destruction of the diaphragm 50, such as delamination and cracks.

[0171] In the recording head 2 of this embodiment, the second layer 52 and the fourth layer 200 preferably contain at least one metal element selected from the group consisting of chromium, titanium, and aluminum. According to this, the second layer 52 and the fourth layer 200 contain a metal element that is more easily oxidized than zirconium, and thus the reduction of silicon oxide contained in the first layer 51 can be reduced compared to a configuration in which the metal 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 increased compared to a configuration without the second layer 52. The adhesion between the third layer 53 and the fourth layer 200 can also be increased.

[0172] 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, and the first electrode 60, the piezoelectric layer 70, and the second electrode 80 are laminated in this order in the −Z direction, which is the first direction. It is preferable that the first electrode 60 and the piezoelectric layer 70 are sandwiched between the third layer 53 and the fourth layer 200 from the third layer 53 side. In this way, by not sandwiching the second electrode 80 between the fourth layer 200 and the third layer 53, the fourth layer 200 can be in contact with the second electrode 80 side of the third layer 53, so that moisture intrusion from the interface on the second electrode 80 side of the third layer 53 can be suppressed. In addition, 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 moisture and hydrogen. Furthermore, by not providing the fourth layer 200 on the vibration plate 50 side of the piezoelectric layer 70, the crystal structure of the piezoelectric layer 70 is prevented from being disturbed by the fourth layer 200, and the crystal structure of the piezoelectric layer 70 can be controlled by the third layer 53.

[0173] 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, and the first electrode 60, the piezoelectric layer 70, and the second electrode 80 are laminated in this order in the −Z direction, which is the first direction. It is preferable that 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 from the third layer 53 side. Even in the configuration in which the second electrode 80 is sandwiched 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 vibration plate 50. In addition, 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 moisture and hydrogen. Furthermore, by not providing the fourth layer 200 on the vibration plate 50 side of the piezoelectric layer 70, the crystal structure of the piezoelectric layer 70 is prevented from being disturbed by the fourth layer 200, and the crystal structure of the piezoelectric layer 70 can be controlled by the third layer 53.

[0174] Furthermore, in the recording head 2 of this embodiment, it is preferable that the pressure chamber 12, which is a recess, is covered by the second layer 52 and the fourth layer 200 in a plan view in the +Z direction, which is the opposite direction to the -Z direction, which is the first direction. This can reliably suppress delamination and damage such as cracks of the vibration plate 50 in the flexible portion facing the pressure chamber 12 of the vibration plate 50.

[0175] In the recording head 2 of the present embodiment, the second layer 52 and the fourth layer 200 are preferably made of the same material. By using the same material for the second layer 52 and the fourth layer 200, the number of types of materials can be reduced, and costs can be reduced, compared to the case where different materials are used.

[0176] In the recording head 2 of this embodiment, the thickness T2 of the second layer 52 is preferably thicker than the thickness T4 of the fourth layer 200. Since moisture easily penetrates into the diaphragm 50, particularly from the second layer 52 side, by making the thickness T2 of the second layer 52 thicker than the thickness T4 of the fourth layer 200, the penetration of moisture into the inside of the diaphragm 50 can be efficiently reduced.

[0177] In the recording head 2 of this embodiment, the second layer 52 and the third layer 53 preferably have different valences. With this, when the active sections 310 are selectively driven, a leakage current is generated in the other active sections 310 that are not driven, causing a minute current to flow, thereby suppressing the variation in deterioration between the active sections 310 that are continuously driven and the other active sections 310 that are not driven. Therefore, the variation in the displacement reduction of the multiple active sections 310 can be suppressed, and the variation in the ejection characteristics of the ink droplets can be suppressed, thereby improving the print quality.

[0178] In the recording head 2 of the present embodiment, the second layer 52 and the third layer 53 preferably have the same valence. This can improve the insulation of the diaphragm 50, suppress leakage current, and suppress the displacement reduction of the active portion 310.

[0179] In the recording head 2 of this embodiment, the first layer 51 preferably contains silicon oxide, and the third layer 53 preferably contains zirconium oxide. This allows the pressure chambers 12 to be formed with high precision by etching in the flow path forming substrate 10, using the first layer 51 as an etching stop layer. In addition, the crystal structure of the piezoelectric layer 70 can be controlled by the surface state of the third layer 53.

[0180] In the recording head 2 of the present embodiment, the second layer 52 preferably contains chromium oxide. In this manner, when the second layer 52 contains chromium oxide, the adhesion between the second layer 52 and the third layer 53 is improved, and the formation of voids at the interface can be suppressed.

[0181] In the recording head 2 of the present embodiment, the chromium oxide contained in the second layer 52 preferably has an amorphous structure. This can reduce the compressive stress, which is the internal stress of the second layer 52, and can reduce distortion occurring at the interface with the first layer 51 or the third layer 53.

[0182] In the recording head 2 of the present embodiment, the fourth layer 200 preferably contains chromium oxide. In this manner, the fourth layer 200 contains chromium oxide, which improves the adhesion between the fourth layer 200 and the third layer 53, the second electrode 80, etc., and can suppress the formation of voids at the interface.

[0183] In the recording head 2 of the present embodiment, the chromium oxide contained in the fourth layer 200 preferably has an amorphous structure. This can reduce the compressive stress, which is the internal stress of the fourth layer 200, and can reduce distortion occurring at the interface between the fourth layer 200 and the third layer 53.

[0184] In the recording head 2 of the present embodiment, the second layer 52 preferably contains titanium oxide. In this manner, when the second layer 52 contains titanium oxide, the adhesion between the second layer 52 and the third layer 53 is improved, and the formation of voids at the interface can be suppressed.

[0185] In the recording head 2 of the present embodiment, the titanium oxide contained in the second layer 52 preferably has a rutile structure. In this manner, when the titanium oxide contained in the second layer 52 has a rutile structure, the thermal stability of the second layer 52 can be improved compared to when the titanium oxide contained in the second layer 52 has a different crystal structure.

[0186] In the recording head 2 of the present embodiment, the fourth layer 200 preferably contains titanium oxide. In this manner, the fourth layer 200 contains titanium oxide, which improves the adhesive strength between the fourth layer 200 and the third layer 53, the second electrode 80, etc., and can suppress the formation of voids at the interface.

[0187] In the recording head 2 of the present embodiment, the titanium oxide contained in the fourth layer 200 preferably has a rutile structure. In this manner, when the titanium oxide contained in the fourth layer 200 has a rutile structure, the thermal stability of the fourth layer 200 can be improved compared to when the titanium oxide contained in the fourth layer 200 has a different crystal structure.

[0188] In the recording head 2 of the present embodiment, the second layer 52 preferably contains aluminum oxide. In this manner, when the second layer 52 contains aluminum oxide, the adhesion between the second layer 52 and the third layer 53 is improved, and the formation of voids at the interface can be suppressed.

[0189] In the recording head 2 of the present embodiment, the aluminum oxide contained in the second layer 52 preferably has an amorphous structure or a trigonal structure. In this way, the aluminum oxide having an amorphous structure or a trigonal structure becomes a dense film and is less likely to crack.

[0190] In the recording head 2 of the present embodiment, the fourth layer 200 preferably contains aluminum oxide. In this manner, the fourth layer 200 contains aluminum oxide, which improves the adhesion between the fourth layer 200 and the third layer 53 and suppresses the formation of voids at the interface.

[0191] In the recording head 2 of the present embodiment, the aluminum oxide contained in the fourth layer 200 preferably has an amorphous structure or a trigonal structure. In this way, the aluminum oxide having an amorphous structure or a trigonal structure becomes a dense film and is less likely to crack.

[0192] 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 thicknesses T1, T3 of the first layer 51 and the third layer 53. In this manner, 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, it is easy to optimize the characteristics of the diaphragm 50.

[0193] In the recording head 2 of this embodiment, the thickness T2 of the second layer 52 is preferably in the range of 20 nm to 50 nm. If the thickness T2 of the second layer 52 is too thin, the silicon element diffused from the first layer 51 to the second layer 52 may reach the third layer 53 during heat treatment during manufacturing, and voids may be formed between the second layer 52 and the third layer 53. If the thickness T2 of the second layer 52 is too thick, the heat treatment during manufacturing of the second layer 52 may not be performed sufficiently, or a long time may be required for thermal oxidation, which may adversely affect other layers. By setting the thickness T2 of the second layer 52 within the above-mentioned range, it is possible to suppress the diffusion of silicon in the third layer 53 and suppress the formation of voids, and it is also possible to perform the heat treatment of the second layer 52 in a relatively short time.

[0194] In the recording head 2 of this embodiment, each of the second layer 52 and the third layer 53 preferably contains an impurity. By containing an impurity in the second layer 52, it is possible to reduce the diffusion of silicon from the first layer 51 to the second layer 52, or to reduce the diffusion of silicon to the third layer 53 even if silicon diffuses from the first layer 51 to the second layer 52. Furthermore, by containing an impurity in the third layer 53, it is possible to soften the third layer 53.

[0195] In the recording head 2 of the present embodiment, the impurity content in the second layer 52 is preferably 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.

[0196] An inkjet recording apparatus 1, which is an example of a liquid ejecting apparatus according to the present invention, includes the above-mentioned recording head 2. It is possible to realize an inkjet recording apparatus 1 in which damage such as delamination and cracks in the diaphragm 50 is suppressed, thereby suppressing a decrease in the life span.

[0197] (Other embodiments) Although each embodiment of the present invention has been described above, the basic configuration of the present invention is not limited to the above.

[0198] Here, a modified example of the first embodiment is shown in FIG. 21. As shown in FIG. 21, the diaphragm 50 has a first layer 51, a second layer 52, and a third layer 53. The second layer 52 has a layer 55 and a layer 56. The layers 55 and 56 are laminated in this order in the -Z direction. The layers 55 and 56 are layers containing the same constituent elements as the second layer 52 described above. However, the compositions of the materials constituting the layers 55 and 56 are different from each other. Specifically, the types or contents of impurities in the layers 55 and 56 are different from each other. The impurities are elements such as titanium (Ti), silicon (Si), iron (Fe), chromium (Cr), or hafnium (Hf), as in the first embodiment described above. The layers 55 and 56 are formed by forming layers made of a single metal element by a sputtering method or the like, and adjusting the time or temperature of heat treatment so as to make the distribution of impurities in the thickness direction of the layers different. The formation of these layers is not particularly limited, and each layer may be formed individually by, for example, a CVD method or the like.

[0199] When the layer 56 contains silicon as an impurity, the layer 56 can be regarded as the "second layer", and in this case, the layer 55 can be regarded as the "fourth layer". That is, the layer 55 is disposed between the first layer 51 and the layer 56, and contains the elements contained in the layer 56 and silicon. In this way, the layer 55 contains silicon, so that the diffusion of silicon from the first layer 51 to the second layer 52 is reduced, or even if silicon diffuses from the first layer 51 to the second layer 52, the diffusion of the silicon to the third layer 53 can be reduced. In addition, there is also an effect that a gap is less likely to occur at the interface between the first layer 51 and the second layer 52.

[0200] Here, layer 56 may contain silicon, but the silicon content in layer 55 is preferably higher than the silicon content in layer 56. In other words, the silicon content in layer 56 is preferably lower than the silicon content in layer 55. By setting the relationship between the silicon contents in layers 55 and 56 in this way, for example, when layer 55 contains titanium oxide, crystal distortion due to 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 third layer 53 can be increased.

[0201] Furthermore, by containing zirconium as an impurity in layer 56, 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, diffusion of the zirconium to the first layer 51 can be reduced. Another effect is that gaps are less likely to occur at the interface between the third layer 53 and layer 55.

[0202] Even with this configuration, as in the above-described first embodiment, it is possible to suppress the intrusion of moisture into the inside of the diaphragm, particularly the intrusion of moisture from the moisture intrusion path R1, and to suppress delamination and cracks in the diaphragm 50. Of course, the second layer 52 having such layers 55 and 56 may be applied to the second embodiment.

[0203] In the recording head 2, which is an example of a piezoelectric device shown in Figure 21, the vibration plate 50 is provided between the first layer 51 and the second layer 56, and further has a fifth layer 55 which contains silicon and the elements contained in layer 56 as constituent elements.

[0204] 21, it is preferable that layer 56, which is the second layer, further contains silicon as a constituent element, and that the silicon content in layer 55, which is the fourth layer, is higher than the silicon content in layer 56. In this manner, by providing layer 55, which is the fourth layer, and by setting the silicon contents of layers 55 and 56 as described above, gaps are less likely to occur at the interface between second layer 52 and third layer 53.

[0205] Moreover, a modified example of the first embodiment is shown in Fig. 22. As shown in Fig. 22, the diaphragm 50 has a first layer 51, a second layer 52, and a third layer 53. The second layer 52 has a layer 55, a layer 56, and a layer 57. The layers 55, 56, and 57 are laminated in this order in the -Z direction. Each of the layers 55, 56, and 57 is a layer that contains the same constituent elements as the second layer 52 described above.

[0206] However, the compositions of the materials constituting the layers 55, 56, and 57 are different from each other. Specifically, the types or contents of impurities in the layers 55, 56, and 57 are different from each other. The impurities are elements such as titanium (Ti), silicon (Si), iron (Fe), chromium (Cr), and hafnium (Hf) as in the above-mentioned embodiment 1. The layers 55, 56, and 57 are formed, for example, by forming a layer made of a simple metal element by a sputtering method or the like, and adjusting the time or temperature of a heat treatment so as to make the distribution of impurities in the thickness direction of the layer different. The formation of these layers is not particularly limited, and each layer may be formed by individual film formation by a CVD method or the like.

[0207] Furthermore, when layer 57 contains zirconium as an impurity, layer 56 can be regarded as the "second layer", and in this case, layer 57 can be regarded as the "fifth layer". That is, layer 57 is disposed between layer 56 and third layer 53, and contains zirconium and the elements contained in layer 56. In this manner, by containing zirconium in layer 57, the diffusion of zirconium from the third layer 53 to the second layer 52 can be reduced, or even if zirconium diffuses from the third layer 53 to the second layer 52, the diffusion of the zirconium to the first layer 51 can be reduced. In addition, there is an effect that gaps are less likely to occur at the interface between the third layer 53 and the second layer 52.

[0208] Even with this configuration, as in the above-described first embodiment, it is possible to suppress the intrusion of moisture into the inside of the diaphragm, particularly the intrusion of moisture from the moisture intrusion path R1, and to suppress delamination and cracks in the diaphragm 50. Of course, the second layer 52 having such layers 55, 56, and 57 may be applied to the second embodiment.

[0209] 22, a recording head 2 which is an example of a piezoelectric device has a vibration plate 50 which is disposed between a second layer 56 and a third layer 53 and further has a fifth layer 57 which contains silicon and the elements contained in layer 56 as constituent elements. By providing layer 57 in this manner, a gap is less likely to occur at the interface between second layer 52 and third layer 53.

[0210] For example, in each of the above-described embodiments, the first electrode 60 is an individual electrode of the piezoelectric actuator 300, and the second electrode 80 is a common electrode of the multiple piezoelectric actuators 300, but this is not particularly limited, and the first electrode 60 may be a common electrode of the multiple piezoelectric actuators 300, and the second electrode 80 may be an individual electrode of each piezoelectric actuator 300.

[0211] In addition, in the above-mentioned inkjet recording device 1, an example has been given in which the recording head 2 is mounted on a transport body 7 and moves back and forth along the X-axis, which is the main scanning direction, but this is not particularly limited to this, and the present invention can also be applied to, for example, a so-called line-type recording device in which the recording head 2 is fixed and printing is performed simply by moving a medium S, such as paper, along the Y-axis, which is the sub-scanning direction.

[0212] In the above embodiment, an ink jet recording head is used as an example of a liquid jet head, and an ink jet recording device is used as an example of a liquid jet device, but the present invention is intended for a wide range of liquid jet heads and liquid jet devices in general, and can of course be applied to liquid jet heads and liquid jet devices that jet liquids other than ink. Other liquid jet heads include, for example, various recording heads used in image recording devices such as printers, color material jet heads used in manufacturing color filters for liquid crystal displays, electrode material jet heads used in forming electrodes for organic EL displays, FEDs (field emission displays), and bioorganic material jet heads used in biochip manufacturing, and can also be applied to liquid jet devices equipped with such liquid jet heads.

[0213] Furthermore, the present invention is not limited to liquid jet heads such as ink jet recording heads, but can also be applied to ultrasonic devices, motors, pressure sensors, pyroelectric elements, ferroelectric elements, and other piezoelectric devices. Furthermore, completed products using these piezoelectric devices, such as liquid jetting devices using the liquid jetting heads described above, ultrasonic sensors using the ultrasonic devices described above, robots using the motors described above as a driving source, IR sensors using the pyroelectric elements described above, and ferroelectric memories using ferroelectric elements, are also included in the piezoelectric devices. [Explanation of symbols]

[0214] 1...inkjet recording device (liquid ejection device), 2...inkjet recording head (liquid ejection head), 3...liquid container, 4...transport mechanism, 4a...transport roller, 5...control unit, 6...movement mechanism, 7...transport body, 8...transport belt, 10...flow path forming substrate (substrate), 11...partition wall, 12...pressure chamber (recess), 15...communication plate, 16...nozzle communication passage, 17...first manifold portion, 18...second manifold portion, 19...supply communication passage, 20...nozzle plate, 20a...liquid ejection surface, 21...nozzle, 30...protective substrate, 31...holding portion, 32...through hole, 40...case member, 41...recess, 42...third manifold portion, 43...connection port, 44...inlet port, 45...compliance substrate, 46...sealing film, 47...fixed substrate, 48...opening, 49...compliance portion, 50...diaphragm, 51...first layer, 52...second layer, 53...third layer, 55-57...layers, 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 portion, 400...gap, R1, R2, R3...moisture intrusion path, S...medium

Claims

1. A substrate having a recess; A diaphragm having a first layer including silicon as a constituent element, a second layer including at least one metal element selected from the group consisting of chromium, titanium, aluminum, tantalum, hafnium, and iridium as a constituent element, and silicon nitride, or both, stacked along a first direction, and a third layer including zirconium as a constituent element; A piezoelectric actuator; 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 laminated in this order in the first direction; a fourth layer including, as a constituent element, at least one metal element selected from the group consisting of chromium, titanium, aluminum, tantalum, hafnium, and iridium, and silicon nitride, or both, located above the third layer in the first direction; the fourth layer is electrically conductive; the first electrode, the piezoelectric layer, and the fourth layer are sandwiched between the third layer and the second electrode in the first direction, from the third layer side; A piezoelectric device characterized by:

2. A substrate having a recess; A diaphragm having a first layer including silicon as a constituent element, a second layer including at least one metal element selected from the group consisting of chromium, titanium, aluminum, tantalum, hafnium, and iridium as a constituent element, and silicon nitride, or both, stacked along a first direction, and a third layer including zirconium as a constituent element; A piezoelectric actuator; 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 laminated in this order in the first direction; a fourth layer including, as a constituent element, at least one metal element selected from the group consisting of chromium, titanium, aluminum, tantalum, hafnium, and iridium, and silicon nitride, or both, located above the third layer in the first direction; the first electrode, the piezoelectric layer, and the second electrode are sandwiched between the third layer and the fourth layer in the first direction, from the third layer side; A piezoelectric device characterized by:

3. 3. The piezoelectric device according to claim 1, wherein the second layer and the fourth layer contain at least one metal element selected from the group consisting of chromium, titanium, and aluminum.

4. The fourth layer contains iridium.

3. The piezoelectric device according to claim 1, wherein the piezoelectric element is a piezoelectric material.

5. The substrate has a partition wall that defines the recess, In a plan view in a direction opposite to the first direction, the first layer, the second layer, the third layer, and the fourth layer are provided so as to cover the recess and the partition wall; 5. The piezoelectric device according to claim 1, wherein the piezoelectric element is a piezoelectric material.

6. 6. The piezoelectric device according to claim 1, wherein the second layer and the fourth layer are made of the same material.

7. 7. The piezoelectric device according to claim 1, wherein the second layer is thicker than the fourth layer.

8. 8. The piezoelectric device according to claim 1, wherein the second layer and the third layer have different valences.

9. 8. The piezoelectric device according to claim 1, wherein the second layer and the third layer have the same valence.

10. the first layer comprises silicon oxide; 10. The piezoelectric device according to claim 1, wherein the third layer contains zirconium oxide.

11. 11. The piezoelectric device according to claim 1, wherein the second layer contains chromium oxide.

12. The piezoelectric device according to claim 11 , wherein the chromium oxide contained in the second layer has an amorphous structure.

13. The piezoelectric device according to claim 11 or 12, wherein the fourth layer contains chromium oxide.

14. The piezoelectric device according to claim 13 , wherein the chromium oxide contained in the fourth layer has an amorphous structure.

15. 11. The piezoelectric device according to claim 1, wherein the second layer contains titanium oxide.

16. The piezoelectric device according to claim 15 , wherein the titanium oxide contained in the second layer has a rutile structure.

17. The piezoelectric device according to claim 15 or 16, wherein the fourth layer contains titanium oxide.

18. The piezoelectric device according to claim 17 , wherein the titanium oxide contained in the fourth layer has a rutile structure.

19. 11. The piezoelectric device according to claim 1, wherein the second layer contains aluminum oxide.

20. 20. The piezoelectric device according to claim 19, wherein the aluminum oxide contained in the second layer has an amorphous structure or a trigonal structure.

21. 21. The piezoelectric device according to claim 19, wherein the fourth layer contains aluminum oxide.

22. 22. The piezoelectric device according to claim 21, wherein the aluminum oxide contained in the fourth layer has an amorphous structure or a trigonal structure.

23. 23. The piezoelectric device according to claim 1, wherein the second layer has a thickness smaller than each of the first layer and the third layer.

24. 24. The piezoelectric device according to claim 1, wherein the second layer has a thickness in the range of 20 nm to 50 nm.

25. A piezoelectric device as described in any one of claims 1 to 24, characterized in that the vibration plate further has a fifth layer provided between the first layer and the second layer and containing silicon and an element contained in the second layer as a constituent element.

26. The second layer further contains silicon as a constituent element, 26. The piezoelectric device of claim 25, wherein the fifth layer has a higher silicon content than the second layer.

27. A piezoelectric device as described in any one of claims 1 to 26, characterized in that the vibration plate further has a sixth layer disposed between the second layer and the third layer and containing silicon and an element contained in the second layer as a constituent element.

28. 28. The piezoelectric device according to claim 1, wherein each of the second layer and the third layer contains an impurity.

29. 30. The piezoelectric device according to claim 28, wherein the second layer has a higher impurity content than the third layer.

30. A piezoelectric device according to any one of claims 1 to 29, wherein the recess is a pressure chamber that applies pressure to a liquid by vibration of the vibration plate. A liquid jet head comprising:

31. A liquid ejecting apparatus comprising the liquid ejecting head according to claim 30.

Images