Piezoelectric element, liquid ejection head, and liquid ejection device

Abstract

To provide a piezoelectric element having good piezoelectric characteristics.SOLUTION: A piezoelectric element is provided in which a first electrode, a piezoelectric layer, and a second electrode are laminated on a substrate. This piezoelectric element is a piezoelectric element in which the first electrode, the piezoelectric layer, and the second electrode are sequentially laminated on the substrate, and includes an orientation control layer for controlling the orientation of the piezoelectric layer, which is provided between the piezoelectric layer and the first electrode, and a titanium layer containing at least Ti and provided between the first electrode and the orientation control layer.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a piezoelectric element, a liquid ejection head, and a liquid ejection apparatus. [Background technology]

[0002] Generally, a piezoelectric element has a structure in which a lower electrode layer, a piezoelectric layer, and an upper electrode layer are laminated in this order on a substrate. For example, when the piezoelectric layer is made of lead zirconate titanate (hereinafter referred to as PZT) with a rhombohedral crystal structure, it is known that the piezoelectric characteristics are improved if the PZT layer is oriented in the (100) plane. Therefore, methods for orienting the PZT layer in the (100) plane have been proposed (for example, Patent Document 1). Patent Document 1 discloses a structure having an orientation control layer made of lanthanum nickelate below the PZT layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-66600 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in cases where the substrate is strongly oriented, even if a piezoelectric layer is formed on an orientation control layer, the orientation of the piezoelectric layer may not be sufficient. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms. According to one form of the present disclosure, there is provided a piezoelectric element having a first electrode, a piezoelectric layer, and a second electrode stacked in this order on a substrate, the piezoelectric element having an orientation control layer provided between the piezoelectric layer and the first electrode for controlling the orientation of the piezoelectric layer, and a titanium layer containing at least Ti provided between the first electrode and the orientation control layer.

[0006] According to another aspect of the present disclosure, there is provided a liquid ejection head, the liquid ejection head including the piezoelectric element and a vibration plate that vibrates when the piezoelectric element is driven.

[0007] According to another aspect of the present disclosure, there is provided a liquid ejection device, the liquid ejection device including the liquid ejection head and a control unit that controls the operation of the liquid ejection head. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a schematic configuration of a liquid ejection device. [Figure 2] FIG. [Figure 3] Cross-sectional view of line III-III in Figure 2. [Figure 4] FIG. [Figure 5] Cross-sectional view of line VV in Figure 4. [Figure 6] STEM image of the sample. [Figure 7] FIG. 1 shows the EDX results of a sample. [Figure 8] X-ray diffraction pattern of Example 1. [Figure 9] X-ray diffraction pattern of Example 2. [Figure 10] X-ray diffraction pattern of a comparative example. [Figure 11] Figure showing the results of XPS. DETAILED DESCRIPTION OF THE INVENTION

[0009] A. Implementation: A1. Overall configuration of the liquid ejection device: FIG. 1 is a schematic diagram showing the overall configuration of a liquid ejection device 100 according to an embodiment. The liquid ejection device 100 is an inkjet printing device that performs printing by ejecting droplets of ink as a liquid onto a medium 12. The medium 12 can be printing paper or any other material such as a resin film or cloth. In the following description, mutually perpendicular X, Y, and Z directions are used. Furthermore, when specifying a direction, positive and negative signs are used in combination, with a positive direction being represented by "+" and a negative direction being represented by "-". In this embodiment, the X direction is the main scanning direction, which is the direction in which the liquid ejection head 26 moves. The Y direction is the sub-scanning direction, which is the medium feed direction perpendicular to the main scanning direction. The -Z direction is the ink ejection direction.

[0010] The liquid ejection device 100 includes a liquid ejection head 26, a head moving mechanism 20, a liquid storage unit 14, a transport mechanism 16, and a control unit 80.

[0011] The liquid storage unit 14 stores ink to be supplied to the liquid ejection head 26. The liquid storage unit 14 may be a bag-shaped liquid pack made of flexible film, an ink tank that can be refilled with ink, or a removable ink cartridge.

[0012] The liquid ejection head 26 has a plurality of nozzles N for ejecting ink. The plurality of nozzles N are arranged in the Y direction. The liquid ejection head 26 ejects ink supplied from the liquid storage unit 14 from the plurality of nozzles N toward the medium 12.

[0013] The head moving mechanism 20 includes a conveyor belt 21 and a carriage 22 that houses a liquid ejection head 26. The carriage 22 is connected to the conveyor belt 21 and is reciprocated in the X direction as the conveyor belt 21 is driven. The conveyor mechanism 16 conveys the medium 12 in the +Y direction.

[0014] The control unit 80 includes processing circuits such as one or more CPUs (Central Processing Units) or FPGAs (Field Programmable Gate Arrays) and storage circuits such as semiconductor memories, and controls the overall operation of the liquid ejection device 100. The control unit 80 is electrically connected to the transport mechanism 16, the head moving mechanism 20, and the liquid ejection head 26, and controls each of these components. An image is printed on the medium 12 by ejecting liquid from the nozzles N onto the medium 12 transported by the transport mechanism 16.

[0015] A2. Liquid ejection head configuration: Fig. 2 is an exploded perspective view of the liquid ejection head 26 according to the embodiment. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. Fig. 4 is a plan view of the piezoelectric element 44. In Fig. 4, the formation region of the second electrode 445, other than the region where the first conductive layer 451 and the second conductive layer 452 are formed, is hatched. Fig. 5 is a cross-sectional view taken along line VV in Fig. 4.

[0016] 2, the liquid ejection head 26 includes a nozzle plate 62, two vibration absorbers 64, a flow path substrate 32, a pressure chamber substrate 34, a diaphragm 36, a seal 46, a housing 48, and a circuit board 50. The nozzle plate 62, the vibration absorbers 64, the flow path substrate 32, the pressure chamber substrate 34, the diaphragm 36, and the seal 46 are plate-like members that are elongated in the Y direction. The nozzle plate 62, the flow path substrate 32, the pressure chamber substrate 34, the diaphragm 36, and the seal 46 each have a structure that is approximately symmetrical with respect to a center line in the X direction. The planar sizes of the pressure chamber substrate 34, the diaphragm 36, and the seal 46 are smaller than the planar sizes of the flow path substrate 32 and the housing 48. During assembly, the nozzle plate 62 and two vibration absorbers 64, the flow path substrate 32, the pressure chamber substrate 34, the vibration plate 36, the sealing body 46, and the housing part 48 are stacked in this order and bonded together, for example, with an adhesive.

[0017] The nozzle plate 62 is a plate-like member in which a plurality of nozzles N are formed. The nozzles N are through-holes that are approximately circular in plan view. The plurality of nozzles N are arranged along the Y direction. There are two rows in which the plurality of nozzles N are arranged, and the two rows are aligned in the X direction. The two vibration absorbers 64 are flexible films and are arranged on either side of the nozzle plate 62 in the X direction.

[0018] The flow path substrate 32 has two first openings 32a, a plurality of second openings 32b, and a plurality of third openings 32c. The planar shape of the first openings 32a is a rectangle elongated in the Y direction. The first openings 32a are formed along sides of the flow path substrate 32 parallel to the Y direction. The plurality of second openings 32b are arranged in the Y direction. Similarly, the plurality of third openings 32c are arranged in the Y direction. There are two rows of the second openings 32b and two rows of the third openings 32c. In the X direction, the first openings 32a, one row of the second openings 32b, one row of the third openings 32c, one row of the third openings 32c, one row of the second openings 32b, and the first opening 32a are arranged in this order. In addition, the second openings 32b and the third openings 32c adjacent to each other in the X direction are formed so as to be positioned approximately at the same position in the Y direction.

[0019] A plurality of openings 34a are formed in the pressure chamber substrate 34. The planar shape of the openings 34a is a rectangle that is elongated in the X direction. The plurality of openings 34a are arranged in the Y direction. The plurality of openings 34a are arranged in two rows, and the two rows are formed side by side in the X direction. When viewed from the Z direction, the openings 34a are formed at positions that overlap the adjacent second openings 32b and third openings 32c formed in the flow path substrate 32.

[0020] A piezoelectric element 44 is formed on the vibration plate 36 at a position that overlaps with the opening 34a formed in the pressure chamber substrate 34 when viewed from the Z direction. The seal 46 reinforces the strength of the pressure chamber substrate 34 and the vibration plate 36 and protects the piezoelectric element 44. The seal 46 has a seal opening 46a and a seal recess 46b shown in FIG. 3. The seal opening 46a has a planar shape that is a rectangle that is elongated in the Y direction. As shown in FIG. 3, the seal recess 46b is recessed from the surface of the seal 46 that faces the piezoelectric element 44.

[0021] A drive circuit (not shown) for driving the piezoelectric element 44 is mounted on the circuit board 50. The drive circuit is realized by an IC (Integrated Circuit) chip that outputs a drive signal and a reference voltage for driving the piezoelectric element 44. The drive circuit and the piezoelectric element 44 are electrically connected via electrical wiring 51 shown in FIG.

[0022] The housing 48 is a case for storing ink and has a frame shape. When stacked, the pressure chamber substrate 34, the vibration plate 36, and the seal 46 are disposed in the internal space of the housing 48. A through hole 48a is formed in each of both ends of the housing 48 in the X direction.

[0023] As shown in FIG. 3 , a space Rb extending in the Y direction is formed at each of both ends of the housing 48 in the X direction. The space Rb is in communication with the through-hole 48a. The flow path substrate 32 is connected to the vibration absorber 64, thereby forming the space Ra, the supply liquid chamber 26a, and the supply flow path 26b. The space Ra is the internal space of the first opening 32a. The supply liquid chamber 26a is a space surrounded by the vibration absorber 64 and the partition wall 32d separating the first opening 32a and the second opening 32b. The supply flow path 26b is the internal space of the second opening 32b. The space Ra is in communication with the space Rb and the supply liquid chamber 26a, and the supply liquid chamber 26a is in communication with the supply flow path 26b. The pressure chamber substrate 34 is connected to the vibration plate 36, thereby forming a pressure chamber C. The pressure chamber C is a space surrounded by the opening 34a and the vibration plate 36. The pressure chamber C is in communication with the supply flow path 26b. The flow path substrate 32 and the nozzle plate 62 are connected to form a communication flow path 26c. The communication flow path 26c is the internal space of the third opening 32c. The communication flow path 26c is in communication with the pressure chamber C and the nozzle N.

[0024] The spaces Ra and Rb function as liquid storage chambers that store ink to be supplied to the pressure chambers C. The spaces Rb communicate with the multiple spaces Ra aligned in the Y direction, and ink supplied via the through-holes 48a is stored in the multiple spaces Ra via the spaces Rb. The ink stored in the spaces Ra flows through the supply liquid chamber 26a and the supply flow path 26b and is supplied to the pressure chambers C.

[0025] In a plan view seen from the Z direction, the piezoelectric element 44 is disposed at a position overlapping with each of the two pressure chambers C. A drive signal and a reference voltage are input from the circuit board 50 to the piezoelectric element 44 via electrical wiring 51. When the drive signal and the reference voltage are input and a voltage is applied, the piezoelectric element 44 deforms, the diaphragm 36 vibrates in conjunction with the deformation of the piezoelectric element 44, and the pressure inside the pressure chamber C fluctuates, causing ink to be ejected from the nozzle N.

[0026] A3. Piezoelectric element configuration: 5, the piezoelectric element 44 is formed by stacking a first electrode 441, a titanium layer 442, an orientation control layer 443, a piezoelectric layer 444, and a second electrode 445 in this order on the vibration plate 36. Here, when viewed from the Z direction, a portion where the first electrode 441, the titanium layer 442, the orientation control layer 443, the piezoelectric layer 444, and the second electrode 445 overlap is referred to as a first region R1. The first region R1 is a portion where the piezoelectric layer 444 deforms when a voltage is applied between the first electrode 441 and the second electrode 445.

[0027] The diaphragm 36 serving as a substrate includes a silicon substrate 361 and an insulator layer 362. Silicon dioxide is formed on the surface of the silicon substrate 361 located on the +Z direction side and in contact with the insulator layer 362. The insulator layer 362 is made of zirconium oxide (ZrO2). The insulator layer 362 may also be made of silicon nitride (SiN) or the like. In this embodiment, the insulator layer 362 is a non-oriented layer. Another layer such as a metal oxide may be interposed between the silicon substrate 361 and the insulator layer 362.

[0028] The first electrode 441 is made of a titanium (Ti) layer, a platinum (Pt) layer, and an iridium (Ir) layer. Note that the first electrode 441 is not limited to a plurality of layers of Ti, Pt, and Ir, and may be a single layer of a metal material such as Ti, Pt, Ir, aluminum (Al), nickel (Ni), gold (Au), or copper (Cu), or may be formed by stacking a plurality of layers of these metal materials.

[0029] The titanium layer 442 is a canceling layer having a function of canceling the influence of the orientation from the base layer to the piezoelectric layer 444. In the present embodiment, the base layer is the first electrode 441. In the present embodiment, since the first electrode 441 is a metal layer containing Pt, it is likely to have a (111) orientation. Therefore, if the orientation control layer 443 is formed on the first electrode 441 without providing the titanium layer 442, the orientation control layer 443 may be affected by the first electrode 441 having a (111) orientation and may not be sufficiently (100) oriented. Therefore, in the present embodiment, by forming the titanium layer 442 between the first electrode 441 and the orientation control layer 443, the influence of the orientation of the first electrode 441 can be canceled, and the orientation control layer 443 can be sufficiently (100) oriented. Then, the piezoelectric layer 444 formed on the orientation control layer 443 can be favorably (100) oriented. Therefore, the piezoelectric characteristics of the piezoelectric element 44 can be improved. The titanium layer 442 is mainly a layer containing Ti. When the amount of substance [mol] of a metal element different from Ti contained in the titanium layer 442 is na and the amount of substance [mol] of Ti contained in the titanium layer 442 is nt, nt satisfies the following formula (1). na < nt ··· Formula (1) It is preferable that nt satisfies the following formula (2), and it is more preferable that nt satisfies the following formula (3). Thereby, the function of canceling the influence of the above-mentioned orientation can be further improved. na ≦ 0.4 × nt ··· Formula (2) na ≦ 0.2 × nt ··· Formula (3) The thickness of the titanium layer is preferably 1 nm or more and 30 nm or less. Thereby, the function of canceling the influence of the above-mentioned orientation can be favorably exhibited. Further, the titanium layer 442 is preferably amorphous.

[0030] The Ti content of the titanium layer 442 measured by EDX (Energy Dispersive X-ray spectroscopy) analysis is higher than the Ti content of the orientation control layer 443 measured by EDX analysis. Here, the content is expressed in atomic percent (atom%). In this embodiment, the orientation control layer 443 contains iron (Fe). The Fe content of the titanium layer 442 measured by EDX analysis is lower than the Fe content of the orientation control layer 443 measured by EDX analysis. The Fe content of the titanium layer 442 measured by EDX analysis is higher than the Fe content of the first electrode 441 measured by EDX analysis. By including Fe in the titanium layer 442, the adhesiveness of the orientation control layer 443 can be improved compared to when Fe is not included. In this embodiment, the EDX analysis was performed using a JEM-ARM200F manufactured by JEOL Ltd. In another embodiment, the titanium layer 442 does not need to include Fe.

[0031] The orientation control layer 443 has a function of controlling the orientation of the piezoelectric layer 444. The orientation control layer 443 contains at least one of lead (Pb) and bismuth (Bi) as a constituent element. In this embodiment, the orientation control layer 443 contains lead (Pb), bismuth (Bi), iron (Fe), and titanium (Ti). Specifically, the orientation control layer 443 is composed of ((Pb,Bi)(Fe,Ti)O x ) In addition, orientation control layer 443 has a perovskite structure. The thickness of orientation control layer 443 is preferably 5 nm or more and 200 nm or less. By setting the thickness of orientation control layer 443 to the above thickness, it is possible to improve the displacement efficiency, which is indicated by the amount of displacement of piezoelectric layer 444 relative to the applied voltage, while maintaining the orientation control function.

[0032] In another embodiment, orientation control layer 443 may contain Pb, Fe, and Ti, but not Bi. Alternatively, orientation control layer 443 may contain Bi, Fe, and Ti, but not Pb. Furthermore, orientation control layer 443 does not have to have a perovskite structure.

[0033] The piezoelectric layer 444 is made of a composite oxide containing Pb, Zr, and Ti as constituent elements. In this embodiment, the piezoelectric layer 444 is made of lead zirconate titanate (PZT), which has a rhombohedral crystal system and a perovskite structure. The piezoelectric layer 444 is not limited to PZT, and may be made of, for example, potassium sodium niobate ((K,Na)NbO), lead lanthanum zirconate titanate ((Pb,La)(Zr,Ti)O), lead zirconium niobate titanate (Pb(Zr,Ti,Nb)O), lead magnesium zirconium niobate titanate (Pb(Zr,Ti)(Mg,Nb)O), lead magnesium niobate-lead titanate solid solution (Pb(Mg,Nb)O-PbTiO), or bismuth sodium titanate ((Bi,Na)TiO). Furthermore, the crystal structure of the piezoelectric layer 444 is not limited to a perovskite structure, and may be any crystal structure that has piezoelectric properties.

[0034] The second electrode 445 is made of Ir. Note that the second electrode 445 is not limited to Ir, and may be a single layer of a metal material such as Pt, Al, Ni, Au, or Cu, or may be formed by stacking multiple layers of these metal materials.

[0035] As shown in FIG. 4, the first electrode 441 is formed for each pressure chamber C, i.e., for each first region R1. The first electrodes 441 are drawn in the +X direction and are individually electrically connected to the drive circuit via first wiring 446 that is electrically connected to the first electrodes 441. The first wiring 446 is formed of a conductive material with lower resistance than the first electrodes 441. Specifically, the first wiring 446 is formed by laminating a gold (Au) conductive film on the surface of a conductive film made of nichrome (NiCr). In contrast, the second electrode 445 is formed so as to cover the multiple first regions R1 aligned in the Y direction. In other words, the first electrodes 441 are individually provided in the multiple first regions R1. In contrast, the second electrode 445 is commonly provided for the multiple first regions R1. An individual drive voltage is applied to the first electrode 441 for each first region R1, and a common reference voltage is applied to the second electrode 445 for the multiple first regions R1 aligned in the Y direction. The piezoelectric layer 444 is formed with through-holes 444a between adjacent first regions R1. The through-holes 444a are regions where the piezoelectric layer 444 is not formed.

[0036] As shown in FIG. 5, the first region R1 is the region where the piezoelectric layer 444 is sandwiched between the first electrode 441 and the second electrode 445. The second region R2 is the region where the piezoelectric layer 444 is not sandwiched between the first electrode 441 and the second electrode. The thickness T1 of the titanium layer 442 in the first region R1 is thicker than the thickness T2 of the titanium layer 442 in the second region R2. The piezoelectric layer 444 in the second region R2 has less impact on the ejection performance and therefore does not require as much piezoelectric performance as the titanium layer 442 in the first region R1. Therefore, the thickness T2 can be thinner than the thickness T1. Furthermore, by forming the titanium layer 442 in the second region R2, cracks in the piezoelectric layer 444 at the boundary between the first region R1 and the second region R2 can be suppressed compared to when the titanium layer 442 is not formed in the second region R2. If the titanium layer 442 is not formed in the second region R2, there is a risk that a difference in orientation of the piezoelectric layer 444 will occur at the boundary between the first region R1 and the second region R2. However, by forming the titanium layer 442 in the second region R2, it is possible to make the difference in orientation less likely to occur.

[0037] As shown in FIG. 4, a strip-shaped first conductive layer 451 and a second conductive layer 452 extending in the Y direction are formed on the second electrode 445. The first conductive layer 451 and the second conductive layer 452 are electrically connected to the second electrode 445. The first conductive layer 451 and the second conductive layer 452 are disposed opposite each other in the X direction, sandwiching the piezoelectric element 44 therebetween. The first conductive layer 451 and the second conductive layer 452 are conductive patterns having a structure in which a gold conductive film is laminated on the surface of a conductive film made of nichrome, for example. The first conductive layer 451 and the second conductive layer 452 also function as weights for suppressing vibration of the diaphragm 36.

[0038] A4. How to make a piezoelectric element: First, the diaphragm 36 is fabricated. Specifically, silicon dioxide is formed on the surface in the +Z direction by thermally oxidizing the silicon substrate 361. Next, a Zr layer is formed by sputtering, and the Zr is thermally oxidized to form a ZrO layer as the insulator layer 362.

[0039] Next, the first electrode 441 is formed. Specifically, a Ti layer and a Pt layer are laminated in this order by sputtering. Next, an Ir layer is laminated by sputtering. Next, the Ti layer, Pt layer, and Ir layer are patterned using photolithography. Specifically, a resist is applied to the Ir layer, and after exposure, the Ti, Pt, and Ir are ion-milled. Next, the resist is removed by oxygen plasma ashing, and the substrate is cleaned.

[0040] Next, the titanium layer 442 is formed. For example, it is formed by sputtering. The titanium layer 442 may also be formed by CVD (Chemical Vapor Deposition) or MOD. Next, the orientation control layer 443 is formed by MOD (Metal Organic Decomposition). Specifically, first, a propionic acid solution of Pb, Bi, Fe, and Ti adjusted to a molar ratio of Bi:Pb:Fe:Ti=110:10:50:50 is applied to the diaphragm 36 by spin coating. Next, drying and degreasing are performed at 350°C using a hot plate. Next, heat treatment is performed at 700°C for 5 minutes by RTA (Rapid Thermal Anneal).

[0041] Next, the piezoelectric layer 444 is formed by a solution method. Specifically, an acetic acid solution of Pb, Zr, and Ti, adjusted to a molar ratio of Pb:Zr:Ti=118:52:48, is first applied onto the orientation control layer 443 by spin coating. Next, drying and degreasing are performed at 200°C and 410°C using a hot plate. Next, heat treatment is performed at 740°C for 5 minutes using RTA (Rapid Thermal Anneal).

[0042] Next, the second electrode 445 is formed. Specifically, Ir is deposited by sputtering. Next, the Ir layer is patterned using photolithography.

[0043] According to the above embodiment, piezoelectric element 44 has titanium layer 442, which cancels the influence of the orientation of first electrode 441 and allows orientation control layer 443 to be sufficiently (100) oriented. Furthermore, piezoelectric layer 444 formed on orientation control layer 443 can be favorably (100) oriented. Therefore, the piezoelectric characteristics of piezoelectric element 44 can be improved.

[0044] B. Other Embodiments: (B1) In the above embodiment, the first electrode 441 is formed for each first region R1, and the second electrode 445 is provided in common to multiple first regions R1 arranged in the Y direction. Alternatively, the first electrode 441 may be provided in common to multiple first regions R1 arranged in the Y direction, and the second electrode 445 may be provided for each first region R1.

[0045] (B2) The method for producing piezoelectric element 44 is not limited to the above. For example, etching for patterning first electrode 441 may be an etching method other than ion milling. Furthermore, the method for forming orientation control layer 443 is not limited to the MOD method, and may be other methods such as a sol-gel method or a sputtering method.

[0046] (B3) In the above embodiment, the first electrode 441 is formed by laminating a Ti layer, a Pt layer, and an Ir layer. The three layers of the Ti layer, the Pt layer, and the Ir layer are extended in the +X direction to electrically connect to the drive circuit. Alternatively, only the Ir layer of the three layers may be extended in the +X direction to be electrically connected to the first electrode 441 and the circuit board 50.

[0047] C. Examples and Comparative Examples: C1. Preparation of Examples and Comparative Examples: The following Examples 1, 2, and a comparative example were prepared.

[0048] In Example 1, a titanium layer and an orientation control layer were laminated in this order on a first electrode, and lead zirconate titanate was formed as a piezoelectric layer on the orientation control layer.

[0049] In Example 2, a titanium layer and an orientation control layer were laminated in this order on a first electrode, and potassium sodium niobate was formed as a piezoelectric layer on the orientation control layer.

[0050] As a comparative example, a sample was used that did not have a titanium layer, but had an orientation control layer laminated on the first electrode, and lead zirconate titanate formed as a piezoelectric layer on the orientation control layer.

[0051] C2. Evaluation of titanium layer and orientation control layer: A section of the sample cut out from Example 1 was used as a sample, and a cross section of the sample was exposed using a focused ion beam (FIB), and a scanning transmission electron microscope-energy-dispersive spectroscopy (STEM-EDS) line profile in the cross section depth direction was observed. The spherical aberration scanning transmission analytical electron microscope used was a JEM-ARM200F manufactured by JEOL Ltd.

[0052] Figure 6 is a STEM image of the sample. Figure 7 shows the results of EDX of the sample. As shown in Figure 6, a titanium layer with different contrast can be seen between the orientation control layer and the first electrode. As shown in Figure 7, it can be seen that the titanium layer between the orientation control layer and the first electrode contains a large amount of Ti. The titanium layer is thought to be amorphous titanium oxide (TiOx).

[0053] C3. Evaluation of the piezoelectric layer: The X-ray diffraction patterns of Example 1, Example 2, and Comparative Example were measured to evaluate the degree of orientation of the piezoelectric layer. The X-ray diffraction apparatus used was a Bruker D8 DISCOVER with GADDS. Measurement conditions were tube voltage: 50 kV, tube current: 100 mA, detector distance: 15 cm, collimator diameter: 0.1 mm, and measurement time: 180 seconds. The two-dimensional data obtained by the measurement was converted into an X-ray diffraction intensity curve with a 2θ range of 20° to 50°, a χ range of -95° to -85°, a step width of 0.02°, and an intensity normalization method of bin normalization. Furthermore, the sample of Example 1 before the formation of the piezoelectric layer and the sample of the Comparative Example before the formation of the piezoelectric layer were subjected to composition analysis in the depth direction while performing reverse sputtering using X-ray photoelectron spectroscopy (XPS). The X-ray photoelectron spectroscopy apparatus used was an ESCALAB 250 manufactured by Thermo Fisher Scientific.

[0054] FIG. 8 is the X-ray diffraction pattern of Example 1. FIG. 9 is the X-ray diffraction pattern of Example 2. FIG. 10 is the X-ray diffraction pattern of the Comparative Example. In the X-ray diffraction pattern of the Comparative Example, the peak intensity of the (100) plane near 22° and the peak intensity of the (110) plane near 31° are high, and the peak intensity of the (111) plane near 38° is observed. In contrast, the X-ray diffraction patterns of Examples 1 and 2 have a high peak intensity of the (100) plane. In other words, in the Comparative Example, the piezoelectric layer is not (100) oriented, whereas in Examples 1 and 2, the piezoelectric layers are (100) oriented.

[0055] 11 shows the results of XPS analysis of Ti composition in the film thickness direction of the sample of Example 1 before the piezoelectric layer was formed and the sample of the Comparative Example before the piezoelectric layer was formed. At the positions indicated by circles in FIG. 11, a peak is observed in Example 1, whereas no peak is observed in the Comparative Example. In other words, it can be confirmed that no titanium layer was formed in the Comparative Example.

[0056] From the above results, in Examples 1 and 2, in which a titanium layer was formed below the orientation control layer, the piezoelectric layer was (100) oriented. In contrast, in the comparative example, no titanium layer was formed, and the piezoelectric layer was not (100) oriented. This is thought to be because the titanium layer cancels the orientation state of the lower layer, i.e., the base information, and therefore the formation of the titanium layer allows the piezoelectric layer to be oriented.

[0057] D. Other forms: The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features of the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0058] (1) According to one embodiment of the present disclosure, a piezoelectric element is provided in which a first electrode, a piezoelectric layer, and a second electrode are sequentially stacked on a substrate. This piezoelectric element has an orientation control layer provided between the piezoelectric layer and the first electrode for controlling the orientation of the piezoelectric layer, and a titanium layer containing at least Ti provided between the first electrode and the orientation control layer. According to this embodiment, the piezoelectric element can cancel the influence of the orientation of the first electrode by having a titanium layer and can sufficiently orient the orientation control layer. Then, the piezoelectric layer formed on the orientation control layer can be favorably oriented. Therefore, the piezoelectric characteristics of the piezoelectric element can be improved.

[0059] (2) In the piezoelectric element of the above embodiment, the titanium layer may have a function of canceling the influence of the orientation from the first electrode to the piezoelectric layer. According to this embodiment, the orientation control layer can be sufficiently oriented.

[0060] (3) In the piezoelectric element of the above embodiment, when the amount of substance of a metal element different from Ti contained in the titanium layer is na and the amount of substance of Ti contained in the titanium layer is nt, na < nt may be satisfied.

[0061] (4) In the piezoelectric element of the above embodiment, na ≦ 0.4 × nt may be satisfied.

[0062] (5) In the piezoelectric element of the above embodiment, na ≦ 0.2 × nt may be satisfied.

[0063] (6) In the piezoelectric element of the above embodiment, the orientation control layer may contain at least one of Pb and Bi.

[0064] (7) In the piezoelectric element of the above embodiment, the orientation control layer may contain Pb, Bi, Fe, and Ti.

[0065] (8) In the piezoelectric element of the above embodiment, the orientation control layer may contain Pb, Fe, and Ti and may not contain Bi.

[0066] (9) In the piezoelectric element of the above embodiment, the orientation control layer may contain Bi, Fe, and Ti, but may not contain Pb.

[0067] (10) In the piezoelectric element of the above aspect, the Ti content in the titanium layer measured by EDX analysis may be higher than the Ti content in the orientation control layer measured by EDX analysis.

[0068] (11) In the piezoelectric element of the above embodiment, the titanium layer may contain Fe, and the Fe content in the titanium layer measured by EDX analysis may be smaller than the Fe content in the orientation control layer measured by EDX analysis.

[0069] (12) In the piezoelectric element of the above aspect, the Fe content in the titanium layer measured by EDX analysis may be higher than the Fe content in the first electrode measured by EDX analysis.

[0070] (13) In the piezoelectric element of the above embodiment, when the region of the piezoelectric layer sandwiched between the first electrode and the second electrode is defined as a first region and the region of the piezoelectric layer not sandwiched between the first electrode and the second electrode is defined as a second region, the thickness of the titanium layer in the first region may be thicker than the thickness of the titanium layer in the second region.

[0071] (14) In the piezoelectric element of the above aspect, the orientation control layer may be a complex oxide having a perovskite structure.

[0072] (15) In the piezoelectric element of the above aspect, the titanium layer may be 1 nm or more and 30 nm or less, and the orientation control layer may be 5 nm or more and 200 nm or less.

[0073] (16) According to one embodiment of the present disclosure, there is provided a piezoelectric element including a first electrode, a piezoelectric layer, and a second electrode stacked in this order on a substrate. The piezoelectric element includes an orientation control layer disposed between the piezoelectric layer and the first electrode for controlling the orientation of the piezoelectric layer, and a cancellation layer disposed between the first electrode and the orientation control layer for canceling the influence of the first electrode on the orientation of the piezoelectric layer. According to this embodiment, the influence of the orientation of the first electrode can be canceled, and the orientation control layer can be sufficiently oriented.

[0074] (17) In the piezoelectric element of the above aspect, the piezoelectric layer may contain Pb, Zr, or Ti.

[0075] (18) In the piezoelectric element of the above aspect, the piezoelectric layer may contain K, Na, or Nb.

[0076] (19) According to one aspect of the present disclosure, there is provided a liquid ejection head. This liquid ejection head may include the piezoelectric element of the above aspect and a vibration plate that vibrates when the piezoelectric element is driven. According to this aspect, it is possible to provide a liquid ejection head including an oriented piezoelectric element having good piezoelectric characteristics.

[0077] (20) According to one aspect of the present disclosure, there is provided a liquid ejection device. The liquid ejection device may include the liquid ejection head and a control unit that controls the operation of the liquid ejection head. According to this aspect, it is possible to provide a liquid ejection device including a liquid ejection head having a piezoelectric element with excellent piezoelectric characteristics. [Explanation of symbols]

[0078] 12...medium, 14...liquid storage section, 16...transport mechanism, 20...head movement mechanism, 21...transport belt, 22...carriage, 26...liquid ejection head, 26a...supply liquid chamber, 26b...supply flow path, 26c...communicating flow path, 32...flow path substrate, 32a...first opening, 32b...second opening, 32c...third opening, 32d...partition wall, 34...pressure chamber substrate, 34a...opening, 36...vibration plate, 44...piezoelectric element, 46...sealing body, 46a...sealing body opening, 46b...sealing body recess, 48...casing section, 48a, 444a...through holes, 50...drive circuit, 51...electrical wiring, 62...nozzle plate, 64...vibration absorber, 80...controller, 100...liquid ejection device, 361...silicon substrate, 362...insulator layer, 441...first electrode, 442...titanium layer, 443...orientation control layer, 444...piezoelectric layer, 445...second electrode, 446...first wiring, 451...first conductive layer, 452...second conductive layer, C...pressure chamber, N...nozzle, R1...first region, R2...second region, Ra, Rb...space, T1, T2...thickness

Claims

1. A piezoelectric element in which a first electrode, a piezoelectric layer, and a second electrode are laminated in this order on a substrate, an orientation control layer provided between the piezoelectric layer and the first electrode for controlling the orientation of the piezoelectric layer; a titanium layer containing at least Ti provided between the first electrode and the orientation control layer, the orientation control layer contains Ti, A piezoelectric element, wherein the Ti content in the titanium layer measured by EDX analysis is greater than the Ti content in the orientation control layer measured by EDX analysis.

2. 2. The piezoelectric element according to claim 1, The orientation control layer includes at least one of Pb and Bi.

3. A piezoelectric element according to claim 2, The orientation control layer comprises Fe.

4. A piezoelectric element in which a first electrode, a piezoelectric layer, and a second electrode are stacked in this order on a substrate, an orientation control layer provided between the piezoelectric layer and the first electrode for controlling the orientation of the piezoelectric layer; a titanium layer containing at least Ti provided between the first electrode and the orientation control layer, each of the orientation control layer and the titanium layer contains Fe; a piezoelectric element in which the Fe content in the titanium layer measured by EDX analysis is smaller than the Fe content in the orientation control layer measured by EDX analysis;

5. A piezoelectric element according to claim 4, The orientation control layer includes at least one of Pb and Bi.

6. A piezoelectric element according to claim 5, A piezoelectric element, wherein the orientation control layer contains Ti.

7. 7. The piezoelectric element according to claim 4, a content of Fe in the titanium layer measured by EDX analysis being greater than a content of Fe in the first electrode measured by EDX analysis;

8. A piezoelectric element in which a first electrode, a piezoelectric layer, and a second electrode are stacked in this order on a substrate, an orientation control layer provided between the piezoelectric layer and the first electrode for controlling the orientation of the piezoelectric layer; a titanium layer containing at least Ti provided between the first electrode and the orientation control layer, A piezoelectric element, wherein the orientation control layer contains Pb, Fe, and Ti, but does not contain Bi.

9. 9. The piezoelectric element according to claim 1, The titanium layer has a function of canceling the influence of orientation from the first electrode to the piezoelectric layer.

10. 10. The piezoelectric element according to claim 1, A piezoelectric element in which na<nt is satisfied, where na is the amount of substance of a metal element different from Ti contained in the titanium layer and nt is the amount of substance of Ti contained in the titanium layer.

11. The piezoelectric element according to claim 10, A piezoelectric element that satisfies na≦0.4×nt.

12. 12. The piezoelectric element according to claim 10, A piezoelectric element that satisfies na≦0.2×nt.

13. 13. The piezoelectric element according to claim 1, When a region of the piezoelectric layer sandwiched between the first electrode and the second electrode is defined as a first region, and a region of the piezoelectric layer not sandwiched between the first electrode and the second electrode is defined as a second region, A piezoelectric element, wherein the thickness of the titanium layer in the first region is greater than the thickness of the titanium layer in the second region.

14. 14. The piezoelectric element according to claim 1, A piezoelectric element, wherein the orientation control layer is a complex oxide having a perovskite structure.

15. 15. The piezoelectric element according to claim 1, the titanium layer has a thickness of 1 nm or more and 30 nm or less; A piezoelectric element, wherein the orientation control layer has a thickness of 5 nm or more and 200 nm or less.

16. 16. The piezoelectric element according to claim 1, The piezoelectric element, wherein the piezoelectric layer contains Pb, Zr, and Ti.

17. 16. The piezoelectric element according to claim 1, The piezoelectric element, wherein the piezoelectric layer contains K, Na, and Nb.

18. The piezoelectric element according to any one of claims 1 to 17, a vibration plate that vibrates when the piezoelectric element is driven.

19. The liquid ejection head according to claim 18; a control unit that controls the operation of the liquid ejection head.

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