Actuator, liquid ejection head, and liquid ejection apparatus

Abstract

To provide an actuator having a wide effective area of a piezoelectric body and high reliability.SOLUTION: An actuator includes a first electrode, a piezoelectric body, and a second electrode on the surface of a substrate, in this order, and further includes an insulating film covering at least the side surface of the piezoelectric body. A plurality of inclined surfaces inclined with respect to the substrate are formed on an end portion of the surface of the first electrode opposite to the substrate, and an angle between the substrate and a first inclined surface farthest from the substrate among the plurality of inclined surfaces is smaller than angles between the substrate and the other inclined surfaces.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an actuator, a liquid ejection head, and a liquid ejection device.

Background Art

[0002] Actuators using piezoelectric bodies whose shape changes by applying an electric field are applied to various industrial products as means for moving or vibrating an object minutely and accurately. For example, piezoelectric bodies are used in small speakers, hard disk drives, printers (liquid ejection devices), etc. Some printers use piezoelectric bodies in liquid ejection heads for ejecting droplets. Such a liquid ejection head drives the piezoelectric body by applying an electric field to upper and lower electrodes formed so as to sandwich the piezoelectric body from above and below, and ejects droplets. Further, in order to prevent breakage of the driven piezoelectric body, measures such as forming the piezoelectric body so as to cover the end portion of the lower electrode having an inclined surface are taken (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As in Patent Document 1, it is preferable to form a slope at the end of the upper surface of the lower electrode because the covering property of the insulating film covering the lower electrode and the piezoelectric body is likely to be improved. However, the orientation of the portion of the piezoelectric body covering the slope of the lower electrode is likely to be disturbed. For this reason, the region overlapping the slope of the lower electrode in the piezoelectric body may not become an effective region that can be driven as designed. In particular, when only one slope is formed at the end of the upper surface of the lower electrode, if the inclination angle of the slope of the lower electrode is reduced to improve the covering property of the insulating film, the horizontal length of the slope becomes long, so the effective region of the piezoelectric body that can be driven as designed is likely to become narrow. On the other hand, if the end of the lower electrode is made perpendicular so that the effective region of the piezoelectric body does not become narrow, the covering property of the insulating film may decrease and the reliability of the actuator may decrease.

[0005] An object of the present disclosure is to provide an actuator having a wide effective region of a piezoelectric body and high reliability.

Means for Solving the Problems

[0006] An actuator according to an aspect of the present disclosure has a first electrode, a piezoelectric body, and a second electrode in this order on the surface of a substrate, and further has an insulating film covering at least the side surface of the piezoelectric body. The actuator is characterized in that a plurality of slopes inclined with respect to the substrate are formed at the end of the surface of the first electrode on the side opposite to the substrate, and the angle between the first slope farthest from the substrate and the substrate among the plurality of slopes is smaller than the angle between the other slopes and the substrate.

Effects of the Invention

[0007] According to the present disclosure, it is possible to provide an actuator having a wide effective region of a piezoelectric body and high reliability.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the present disclosure, and not all combinations of the features described in the following embodiments are essential for the solution means of the present disclosure. Note that the same components will be described with the same reference numerals.

[0010] <<Embodiment 1>> <Configuration of the Liquid Ejection Device> FIG. 1 is a perspective view schematically showing a part of a liquid ejection apparatus (not shown). The liquid ejection apparatus of the present embodiment is a one-pass type liquid ejection apparatus that records an image by moving a recording medium 1 once. The liquid ejection apparatus includes a liquid ejection head 4 as a full-line head in which element substrates having ejection ports for ejecting liquid are arranged across a side corresponding to the entire width of the recording medium 1. The recording medium 1 is conveyed in the direction of the arrow (+Y direction) by a conveying means 2, and recording is performed by the liquid ejection head 4. The liquid ejection head 4 of the present embodiment can be implemented in any form including the example shown in FIG. 1. In the example shown in FIG. 1, a liquid ejection apparatus equipped with eight liquid ejection heads 4 (4Ka, 4Kb, 4Ya, 4Yb, 4Ma, 4Mb, 4Ca, 4Cb) is shown. These eight liquid ejection heads 4 are positioned in the liquid ejection apparatus by a reference member.

[0011] As described above, the liquid ejection head 4 of the present embodiment is a so-called page-wide type head of one-pass type having a length corresponding to the width of the recording medium 1. Note that the width of the recording medium 1 is the size in the direction (X direction) orthogonal to the conveyance direction of the recording medium 1. The liquid ejection head may be a so-called serial type liquid ejection head that performs recording while scanning the liquid ejection head with respect to the recording medium. Examples of the serial type liquid ejection head include a configuration in which one element substrate for black ink and one element substrate for color ink are mounted respectively. Another example of the serial type liquid ejection head is a configuration having a width smaller than that of the recording medium, in which several element substrates are arranged such that the ejection ports overlap in the arrangement direction of the ejection port array.

[0012] <Flow path configuration of liquid ejection head> FIG. 2 is a schematic diagram showing the flow path configuration in the element substrate 50 of the liquid ejection head 4 of the present embodiment. FIG. 2(a) is a cross-sectional view seen from the ejection port 11 side of the flow path block 10 in the element substrate 50. FIG. 2(b) is a cross-sectional view taken along the line IIb-IIb in FIG. 2(a). The element substrate 50 includes three types of substrates (the first flow path substrate 20, the second flow path substrate 100, and the third flow path substrate 40), and forms a flow path by combining each substrate. As shown in FIG. 2(a), the flow path block 10 includes ejection ports 11 arranged along the Y direction, pressure chambers 12 prepared to communicate with each of these ejection ports 11, and supply channels 13. Each of the supply channels 13 connected to the common liquid chamber 14 supplies liquid (hereinafter also referred to as ink) to the pressure chamber 12. The arrows in FIG. 2 indicate the flow of the liquid (ink).

[0013] As shown in FIG. 2(b), the element substrate 50 in the present embodiment is configured by laminating the first flow path substrate 20, the second flow path substrate 100, and the third flow path substrate 40 in the Z direction. The first flow path substrate 20 is a substrate including the ejection port 11 for ejecting ink. The second flow path substrate 100 is a substrate in which the piezoelectric element 140 and the pressure chamber 12 are formed. The third flow path substrate 40 is a substrate that isolates the piezoelectric body 400 portion of the piezoelectric element 140 from the ink, and is a substrate including a flow path for supplying ink from the common liquid chamber 14 to the pressure chamber 12.

[0014] The supply channel 13, the pressure chamber 12, and the ejection port 11 are formed corresponding to each of the individual piezoelectric elements 140. Adjacent pressure chambers 12 are separated by a partition wall and are not affected by the direct pressure of adjacent piezoelectric elements 140. Note that the piezoelectric element 140 is formed adjacent to the insulating film 200 that serves as a diaphragm.

[0015] The ink contained in the pressure chamber 12 forms a meniscus at the discharge port 11 in a stable state. When a voltage waveform is applied to the piezoelectric element 140 according to a discharge signal, the piezoelectric element 140 deforms and can expand or contract the pressure chamber 12. By combining the expansion and contraction operations, droplets (ink droplets) 60 are generated from the meniscus, and the ink droplets are discharged in the -Z direction.

[0016] The ink in the pressure chamber 12 consumed by the discharge operation is supplied from the common liquid chamber 14 by the capillary force of the discharge port 11, and the meniscus is reformed at the discharge port 11. In this embodiment, the combination of the discharge port 11, the piezoelectric element 140, and the pressure chamber 12 is referred to as a discharge element.

[0017] An example of the specific dimensions of the above structure in this embodiment will be described. The individual discharge elements, that is, the piezoelectric element 140, the discharge port 11, and the pressure chamber 12, are arranged at a density of 150 npi (nozzles per inch) in the Y direction. The size (length) of the piezoelectric element 140 in the X direction is about 500 μm, and the size (width) of the piezoelectric element 140 in the Y direction is about 110 μm. The diameter of the discharge port 11 is 25 μm, the thickness of the discharge port 11 is 30 μm, and the thickness of the first flow path substrate 20 is 100 μm. The size (length) of the pressure chamber 12 in the X direction is 550 μm, the size (width) of the pressure chamber 12 in the Y direction is 120 μm, and the size (height) of the pressure chamber 12 in the Z direction is 100 μm. Also, the viscosity of the ink used is 4 cp, and the minimum ink discharge amount from each discharge port 11 is 3 pL.

[0018] In this embodiment, the driving frequency of each piezoelectric element 140 is 30 kHz. Such a driving frequency can be appropriately set according to the time required for the ink to be actually discharged after applying a voltage to the piezoelectric element 140 in each discharge element, and for new ink to be refilled to enable the next discharge operation.

[0019] The liquid ejection head 4 is configured by arranging a plurality of element substrates on which a plurality of ejection elements are arrayed. Each of the element substrates is generally connected to a flexible wiring substrate (not shown in general), and further connected to an electrical wiring substrate (not shown). The electrical wiring substrate is provided with a power supply terminal for supplying power and a signal input terminal for receiving an ejection signal. On the other hand, in an ink supply unit (not shown), a circulation flow path (not shown) is formed for supplying ink having a coloring material supplied by an ink tank (not shown) to each element substrate and for recovering ink that has not been consumed in recording.

[0020] Under the above configuration, each of the ejection elements arranged on the element substrate 50 uses the power supplied from the power supply terminal based on the recording data input from the signal input terminal, and ejects the ink supplied from the ink supply unit from the ejection port in the -Z direction. Note that the dimensional values of each part shown above are merely examples and may be appropriately changed according to the required specifications.

[0021] As an example of the liquid ejection head 4 of the liquid ejection device, an inkjet recording head of a printer (image recording device) can be cited. However, the liquid ejected from the liquid ejection head 4 is not limited to ink. For example, the liquid ejection head 4 may eject a primer.

[0022] An actuator 700 configured to be deformable by driving a piezoelectric element 140 is used for the liquid ejection head 4 of the liquid ejection device. In the present embodiment, a configuration will be described in which an actuator with a wide effective area of the piezoelectric body and high reliability can be provided by forming a plurality of inclined surfaces at the end of the upper surface of the first electrode covered with the piezoelectric body. Note that the effective area of the piezoelectric body is, as described above, an area in which the piezoelectric body can be driven (deformed) as designed.

[0023] <Configuration of Actuator> FIG. 3 is an enlarged cross-sectional view schematically showing a part of the actuator 700 of the present embodiment. In FIG. 3, only the second flow path substrate 100 of the element substrate 50 is shown in a simplified manner to make the configuration of the actuator 700 easier to understand.

[0024] As shown in FIG. 3, the actuator 700 of the present embodiment includes an insulating film 200, a first electrode 300, a piezoelectric body 400, a second electrode 500, and an insulating film 600. The insulating film 200, the first electrode 300, the piezoelectric body 400, the second electrode 500, and the insulating film 600 are arranged in this order on one surface of the second flow path substrate 100. Further, the insulating film 600 covers at least the side surface of the piezoelectric body 400. Note that the piezoelectric element 140 is constituted by the first electrode 300, the piezoelectric body 400, and the second electrode 500. A recess 110 for forming the pressure chamber 12 is formed on the surface of the second flow path substrate 100 opposite to the actuator 700. The piezoelectric body 400 is arranged so as to overlap at least a part of the recess 110. Further, the insulating film 200 formed on the upper surface of the second flow path substrate 100 may be referred to as a substrate insulating film. The insulating film 600 that covers at least the side surface of the piezoelectric body 400 may be referred to as a piezoelectric body insulating film.

[0025] Furthermore, the second flow path substrate 100 preferably has a flat surface. The material of the second flow path substrate 100 is appropriately selected and used from, for example, silicon, silicon carbide, quartz, gallium nitride, gallium arsenide, indium phosphide, sapphire, etc. Also, in order to easily form the recess 110, an SOI (Silicon On Insulator) wafer may be used for the second flow path substrate 100. The SOI wafer has a silicon oxide layer formed on a silicon substrate and a silicon layer formed on the silicon oxide layer. The silicon oxide layer is also referred to as a BOX (Buried Oxide) layer. The layer thickness of the silicon oxide layer can be selected between several tens of nm and several hundreds of μm. Also, the layer thickness of the silicon layer can be selected relatively freely. By appropriately combining the layer thickness of the silicon oxide layer and the layer thickness of the silicon layer and using the silicon oxide layer as an etching stop layer, only the silicon layer can be removed by performing selective etching. Through such etching, a recess 110 having the surface of the silicon oxide layer as the bottom surface is obtained. Thereby, it is possible to easily form the recess 110 having an extremely flat bottom surface.

[0026] An insulating film 200 is formed on the upper surface of the second flow path substrate 100. As the material of the insulating film 200, for example, general insulating materials such as silica, silicon nitride, silicon oxynitride, alumina, and tetraethyl orthosilicate can be used. Furthermore, when the material of the second flow path substrate 100 has conductivity, it is preferable to form the insulating film 200 between the first electrode 300 and the second flow path substrate 100. On the other hand, when the material of the second flow path substrate 100 is an insulator, a structure in which the insulating film 200 is omitted may be used. In other words, when the material of the second flow path substrate 100 is an insulator, the actuator 700 may not include the insulating film 200. Furthermore, when the actuator 700 does not include the insulating film 200, the bottom of the recess 110 in the second flow path substrate 100 may function as a diaphragm.

[0027] The first electrode 300 is formed on the upper surface of the insulating film 200. When viewed from above (in the Z direction) of the second flow path substrate 100, the first electrode 300 is formed in a rectangular shape that is longer in the X direction than in the Y direction. Incidentally, when the material of the second flow path substrate 100 is an insulator, the first electrode 300 may be formed on the upper surface of the second flow path substrate 100. The first electrode 300 is also referred to as a lower electrode. The first electrode 300 may be exposed to a high temperature of several hundred degrees Celsius in the manufacturing process of the actuator 700. In this case, as the material of the first electrode 300, for example, materials with a high melting temperature such as copper (Cu), platinum (Pt), gold (Au), chromium (Cr), cobalt (Co), titanium (Ti), etc. are preferably used. Further, the material of the first electrode 300 may be, for example, an alloy of any of copper, platinum, gold, chromium, cobalt, and titanium. The material of the first electrode 300 may be a laminate of any of copper, platinum, gold, chromium, cobalt, and titanium.

[0028] When the piezoelectric body 400 is formed in contact with the upper surface of the first electrode 300, the first electrode 300 may also serve as a film that controls to follow the crystal orientation of the piezoelectric body 400. In this case, the material of the first electrode 300 is appropriately selected to have an appropriate crystal structure according to the material of the piezoelectric body 400. Incidentally, the film that controls to follow the crystal orientation of the piezoelectric body 400 is also referred to as a crystal orientation control film. For example, when the material of the piezoelectric body 400 is lead zirconate titanate (PZT), it is preferable to use platinum as the material of the first electrode 300 that also serves as a crystal orientation control film. For the film formation of the first electrode 300 made of platinum, a general film formation method such as magnetron sputtering can be used. When forming the first electrode 300, the film thickness of the first electrode 300 is appropriately adjusted so that the desired orientation of the piezoelectric body 400 can be obtained. When the material of the first electrode 300 is platinum, a laminate or alloy layer of titanium, titanium oxide, etc. may be formed between the first electrode 300 and the insulating film 200 as an adhesion layer to improve the adhesion between the first electrode 300 and the insulating film 200.

[0029] Further, the first electrode 300 may be a laminate having an adhesion layer for improving the adhesion to the insulating film 200 and a conductor layer laminated on the upper surface of the adhesion layer. In this case, as the material of the adhesion layer, it is possible to use thin films such as titanium and chromium. As the material of the conductor layer, it is possible to use metal materials such as copper, platinum, gold, chromium, cobalt, and titanium. Further, the material of the conductor layer may be an alloy of any of copper, platinum, gold, chromium, cobalt, and titanium. As described above, when the piezoelectric body 400 is formed in contact with the upper surface of the conductor layer, the material of the conductor layer also serving as the crystal orientation control film is appropriately selected to have an appropriate crystal structure according to the material of the piezoelectric body 400.

[0030] A plurality of inclined surfaces, for example, two inclined surfaces 301 and 302, are formed at the end portion on the +X direction side on the upper surface of the first electrode 300. In addition, a plurality of inclined surfaces are also formed at the end portions on the +Y direction side and the -Y direction side on the upper surface of the first electrode 300. Since the plurality of inclined surfaces formed at the end portions on the +Y direction side and the -Y direction side have the same configuration as the plurality of inclined surfaces formed at the end portion on the +X direction side, illustration and description thereof are omitted.

[0031] In the present embodiment, among the two inclined surfaces 301 and 302, the inclined surface farthest from the second flow path substrate 100 in the +Z direction is referred to as the first inclined surface 301. Among the two inclined surfaces 301 and 302, the inclined surface second farthest from the second flow path substrate 100 is referred to as the second inclined surface 302. The angle between the first inclined surface 301 and the second flow path substrate 100 is referred to as the first angle θ1, and the angle between the second inclined surface 302 and the second flow path substrate 100 is referred to as the second angle θ2. In addition, the angle between each inclined surface of the first electrode 300 and the second flow path substrate 100 is defined as the angle between each inclined surface of the first electrode 300 and the flat surface on the second flow path substrate 100. For example, as shown in FIG. 3, the angle between each inclined surface of the first electrode 300 and the second flow path substrate 100 may be the angle between each inclined surface of the first electrode 300 and the upper surface of the insulating film 200. The angle between each inclined surface of the first electrode 300 and the second flow path substrate 100 may be the angle between each inclined surface of the first electrode 300 and the upper surface of the second flow path substrate 100.

[0032] The first inclined surface 301 is formed in a planar shape that extends long in the Y direction. The first inclined surface 301 extends obliquely downward from the end of the portion parallel to the second flow path substrate 100 on the upper surface of the first electrode 300. The second inclined surface 302 is formed in a planar shape that extends long in the Y direction in parallel with the first inclined surface 301. The second inclined surface 302 extends obliquely downward from the lower end of the first inclined surface 301. Also, the first angle θ1 is smaller than the second angle θ2. For example, the first angle θ1 is preferably 12 degrees or more and 22 degrees or less. The second angle θ2 is preferably 27 degrees or more and 37 degrees or less.

[0033] The piezoelectric body 400 is formed on the upper surface of the first electrode 300, in other words, on the surface of the first electrode 300 opposite to the insulating film 200 (second flow path substrate 100). The piezoelectric body 400 covers the upper surface of the first electrode 300 including the two inclined surfaces 301 and 302. The portions of the piezoelectric body 400 covering the two inclined surfaces 301 and 302 are inclined with respect to the second flow path substrate 100 along the two inclined surfaces 301 and 302. As the material of the piezoelectric body 400, lead zirconate titanate, which easily obtains a large displacement amount, is mainly used. Also, as the material of the piezoelectric body 400, it is possible to use a piezoelectric material other than lead zirconate titanate. For example, examples of the material of the piezoelectric body 400 include piezoelectric materials such as barium titanate, lead titanate, lead metaniobate, bismuth titanate, zinc oxide, aluminum nitride, and potassium sodium niobate.

[0034] The piezoelectric body 400 is formed using a general film-forming method such as sputtering or coating by spin coating. The thickness of the piezoelectric body 400 is preferably about 2 μm. When the piezoelectric body 400 is formed by coating, the piezoelectric body 400 is formed in several layers. Further, after forming the piezoelectric body 400, the piezoelectric body 400 is fired to orient the piezoelectric body 400 in a desired crystal orientation. The firing temperature of the piezoelectric body 400 is appropriately selected according to the piezoelectric material. When the material of the piezoelectric body 400 is lead zirconate titanate, the firing temperature of the piezoelectric body 400 may be within the range of 600°C to 900°C. After firing the piezoelectric body 400, the piezoelectric body 400 is processed into a desired device shape by etching using a wet etching method, a dry etching method, or the like. The position of the end portion of the piezoelectric body 400 formed by etching may be a position on a plurality of inclined surfaces of the first electrode 300, or may be a position on the insulating film 200 beyond the end portion on the +X direction side of the first electrode 300. Further, the end portion of the piezoelectric body 400 on the +X direction side may cover all of the plurality of inclined surfaces of the first electrode 300, or may cover a part of the plurality of inclined surfaces.

[0035] The second electrode 500 is formed on the upper surface of the piezoelectric body 400, in other words, on the surface of the piezoelectric body 400 opposite to the first electrode 300. As the material of the second electrode 500, it is possible to use a general electrode material having conductivity. For example, as the material of the second electrode 500, it is possible to use metal materials such as aluminum (Al), tungsten (W), copper, titanium, chromium, gold, and platinum. When the internal stress of the first electrode 300 becomes large during the formation of the first electrode 300 and the piezoelectric body 400 bends, the second electrode 500 may have an internal stress in the direction opposite to that of the first electrode 300. Thereby, it is possible to impart a function of canceling the stress generated in the piezoelectric body 400 to the second electrode 500. As the material of the second electrode 500 that can have an internal stress in the direction opposite to that of the first electrode 300, for example, an alloy of titanium and tungsten can be mentioned. Incidentally, the upper wiring 801 is electrically connected to the portion on the +X direction side of the second electrode 500. The lower wiring 802 (see FIGS. 8(a) and 8(b)) is electrically connected to the portion of the first electrode 300 that protrudes in the -X direction from the piezoelectric body 400.

[0036] The insulating film 600 is formed to cover the upper surface of the second electrode 500, the side surface of the piezoelectric body 400, a part of the upper surface of the first electrode 300, and a part of the upper surface of the insulating film 200. The insulating film 600 is disposed across between the upper wiring 801 and the second electrode 500, between the upper wiring 801 and the piezoelectric body 400, between the lower wiring 802 and the first electrode 300, and between the upper wiring 801 (or the lower wiring 802) and the insulating film 200. Incidentally, the insulating film 600 covers a portion located on the -X direction side of the piezoelectric body 400 on the upper surface of the first electrode 300, including a plurality of inclined surfaces formed at the end portion on the -X direction side of the upper surface of the first electrode 300. Also, when an end portion of the piezoelectric body 400 covers a part of the plurality of inclined surfaces of the first electrode 300, the insulating film 600 covers the other parts of the plurality of inclined surfaces of the first electrode 300. In other words, the insulating film 600 covers the portion not covered by the piezoelectric body 400 on the upper surface of the first electrode 300. As the material of the insulating film 600, similar to the insulating film 200 formed on the upper surface of the second flow path substrate 100, silica, silicon nitride, silicon oxynitride, alumina, tetraethyl orthosilicate, etc. are preferably used. Also, the material of the insulating film 600 may be a laminated film of any one of silica, silicon nitride, silicon oxynitride, alumina, and tetraethyl orthosilicate. For example, the material of the insulating film 600 may be a laminated film in which an alumina film formed in contact with the second electrode 500 and the first electrode 300 and a silicon oxide film formed to cover the alumina film are laminated.

[0037] In order to sufficiently displace the piezoelectric body 400, the potential difference applied between the second electrode 500 (upper wiring 801) and the first electrode 300 (lower wiring 802), that is, the potential difference applied in the film thickness direction of the piezoelectric body 400, is preferably about 30 V or more. When the piezoelectric body 400 is formed using a semiconductor, a relatively large potential difference is applied to the semiconductor device in order to displace the piezoelectric body 400. On the other hand, the dielectric breakdown electric field strength of the insulating film 600 is about 10 MV / cm. Therefore, by setting the film thickness of the insulating film 600 to 30 nm or more, the probability of the actuator 700 failing can be reduced. In order to form the insulating film 600 having a film thickness such that dielectric breakdown does not occur with good productivity, a chemical vapor deposition (CVD) method or a sputtering method is generally used as the film formation method of the insulating film 600.

[0038] In order to displace the piezoelectric body 400 by applying a desired voltage to the second electrode 500 and the first electrode 300, the second electrode 500 is electrically connected to the upper wiring 801, and the first electrode 300 is electrically connected to the lower wiring 802. An upper through hole 601 penetrating in the vertical direction (Z direction) is formed in a portion of the insulating film 600 covering the second electrode 500. One end side of the upper wiring 801 is inserted into the upper through hole 601 so as to be joined to the second electrode 500. A lower through hole 602 (see FIG. 7(d)) penetrating in the vertical direction (Z direction) is formed in a portion of the insulating film 600 covering the first electrode 300. One end side of the lower wiring 802 is inserted into the lower through hole 602 so as to be joined to the first electrode 300.

[0039] As materials for the upper wiring 801 and the lower wiring 802, it is possible to use generally used metal materials. For example, as materials for the upper wiring 801 and the lower wiring 802, it is possible to use metal materials such as aluminum, copper, and gold. Examples of the materials for the upper wiring 801 and the lower wiring 802 include alloys of any of aluminum, copper, and gold. Further, in order to improve the adhesion between the upper wiring 801 and the lower wiring 802 and the insulating film 600, thin films such as titanium and chromium may be formed between the upper wiring 801 and the lower wiring 802 and the insulating film 600.

[0040] As described above, in order to sufficiently displace the piezoelectric body 400, it is necessary to apply a relatively high voltage to the second electrode 500 and the first electrode 300. Further, since the surface density of the actuators 700 provided in plurality on the chip-type liquid ejection head (element substrate 50) is high, there is a possibility that current flows on the surface of the element substrate 50 in an environment with high humidity, causing a failure of the actuator 700. For this reason, it is preferable that the upper wiring 801 and the lower wiring 802 are covered with a highly insulating passivation film 900. As the material of the passivation film 900, materials having high insulation such as silica, silicon nitride, and alumina are preferably used. In the liquid ejection head, it is preferable that the passivation film 900 has moisture resistance. For example, a passivation film partially including a silicon nitride film has higher moisture resistance than a passivation film formed of a silicon oxide film and is preferable. A passivation film partially including a silicon nitride film can obtain sufficient moisture resistance and insulation even with a thinner film thickness than a passivation film formed of a silicon oxide film. By using a passivation film having moisture resistance, it is possible to suppress the influence of a high-humidity environment on the displacement characteristics of the piezoelectric body 400.

[0041] Since it may affect the displacement characteristics of the piezoelectric body 400, it is difficult to planarize the upper wiring 801 and the lower wiring 802 formed on the upper surface of the insulating film 600 by a chemical mechanical polishing method (CMP method) or the like. For this reason, the step shape based on the upper through hole 601 appears on the surface of the upper wiring 801, and the step shape based on the lower through hole 602 appears on the surface of the lower wiring 802. Therefore, the passivation film 900 covers a step of 30 nm or more generated in the portion inserted into the upper through hole 601 in the upper wiring 801 and a step of 30 nm or more generated in the portion inserted into the lower through hole 602 in the lower wiring 802.

[0042] In the present embodiment, the first electrode 300 is processed into an appropriate size according to the design. At that time, by controlling the shape of the end portion of the first electrode 300, it is possible to improve the covering property of the insulating film 600 that covers the side surface of the piezoelectric body 400 formed on the upper surface of the first electrode 300 and expand the effective region of the piezoelectric body 400.

[0043] If the end portion of the first electrode 300 has a vertical structure, voids are likely to occur in the step portion of the insulating film 600 that covers the upper surface of the second electrode 500 and the side surface of the piezoelectric body 400 on the +X direction side, and the covering property of the insulating film 600 may be reduced and the reliability may be lowered. In addition, since the portion of the piezoelectric body 400 far from the second flow path substrate 100 is displaced as a free end, the amount of displacement is larger than that of the portion of the piezoelectric body 400 close to the second flow path substrate 100. For this reason, stress concentration on the piezoelectric body 400 and the insulating film 600 is likely to occur when the piezoelectric body 400 is driven.

[0044] In this embodiment, a plurality of inclined surfaces, for example, two inclined surfaces 301 and 302, are formed at the end of the upper surface of the first electrode 300. As a result, the change in the height of the stepped portion of the insulating film 600 that covers the upper surface of the second electrode 500 and the side surface on the +X direction side of the piezoelectric body 400 becomes gentle along the two inclined surfaces 301 and 302 of the first electrode 300. By forming the two inclined surfaces 301 and 302 at the end of the upper surface of the first electrode 300, the covering property of the insulating film 600 that covers the side surface on the +X direction side of the piezoelectric body 400 can be improved, and the reliability can be enhanced. Also, by forming the two inclined surfaces 301 and 302 at the end of the upper surface of the first electrode 300, the horizontal length of the two inclined surfaces 301 and 302 can be shortened. Therefore, since the region overlapping the two inclined surfaces 301 and 302 in the piezoelectric body 400 becomes narrow, it becomes possible to expand the effective region of the piezoelectric body 400 and enhance the operating efficiency of the piezoelectric body 400.

[0045] Also, the angle (first angle θ1) between the first inclined surface 301 and the second flow path substrate 100 is smaller than the angle (second angle θ2) between the second inclined surface 302 and the second flow path substrate 100. As a result, since the inclination angle increases in order from the first inclined surface 301, which is the farthest from the second flow path substrate 100, the concentration of stress on the piezoelectric body 400 and the insulating film 600 when driving the piezoelectric body 400 can be alleviated. Also, since the inclination angle increases in order from the first inclined surface 301, which is the farthest from the second flow path substrate 100, the covering property of the portion covering the two inclined surfaces 301 and 302 in the piezoelectric body 400 can be improved. As described above, the first angle θ1 is preferably 12 degrees or more and 22 degrees or less. The second angle θ2 is preferably 27 degrees or more and 37 degrees or less. Thereby, the covering property of the insulating film 600 that covers the side surface on the +X direction side of the piezoelectric body 400 is improved, and the horizontal length of the two inclined surfaces 301 and 302 can be shortened.

[0046] As described above, according to the present embodiment, it is possible to provide an actuator 700 having a wide effective area of the piezoelectric body 400 and high reliability. That is, according to the present embodiment, a plurality of slopes, for example, two slopes 301 and 302, are formed at the end portion of the upper surface of the first electrode 300. By forming the two slopes 301 and 302 at the end portion of the upper surface of the first electrode 300, the covering property of the insulating film 600 covering the side surface on the +X direction side of the piezoelectric body 400 can be improved and the reliability can be enhanced. Further, by forming the two slopes 301 and 302 at the end portion of the upper surface of the first electrode 300, the horizontal length of the two slopes 301 and 302 can be shortened. Therefore, since the area overlapping the two slopes 301 and 302 in the piezoelectric body 400 becomes narrow, it becomes possible to widen the effective area of the piezoelectric body 400 and improve the operating efficiency of the piezoelectric body 400. Also, the angle (first angle θ1) between the first slope 301 and the second flow path substrate 100 is smaller than the angle (second angle θ2) between the second slope 302 and the second flow path substrate 100. Thereby, since the inclination angle increases in order from the first slope 301 which is the farthest from the second flow path substrate 100, the concentration of stress on the piezoelectric body 400 and the insulating film 600 when driving the piezoelectric body 400 can be alleviated. Further, since the inclination angle increases in order from the first slope 301 which is the farthest from the second flow path substrate 100, the covering property of the portion covering the two slopes 301 and 302 in the piezoelectric body 400 can be improved. In this way, it is possible to provide an actuator 700 having a wide effective area of the piezoelectric body 400 and high reliability.

[0047] Furthermore, the two slopes 301 and 302 may each be formed as a curved surface. In other words, the first slope 301 may be formed as a curved surface, and the second slope 302 may be formed as a curved surface. In this case, a portion where the angle between the tangent plane of each slope and the second flow path substrate 100 changes discontinuously is defined as the boundary portion between the first slope 301 and the second slope 302. Also in this case, the first slope 301 is formed in a curved surface shape that is convexly curved in a cross section (XZ cross section) viewed from the Y direction. The second slope 302 is formed in a curved surface shape that is convexly curved with a curvature larger than that of the first slope 301 in a cross section viewed from the Y direction. The angle between the tangent plane of the first slope 301 and the second flow path substrate 100 decreases as the contact point between the tangent plane of the first slope 301 and the first slope 301 moves farther from the second flow path substrate 100. The angle between the tangent plane of the second slope 302 and the second flow path substrate 100 decreases as the contact point between the tangent plane of the second slope 302 and the second slope 302 moves farther from the second flow path substrate 100.

[0048] Thereby, similar to the above-described embodiment, the covering property of the insulating film 600 covering the +X direction side surface of the piezoelectric body 400 can be improved, and the horizontal lengths of the two slopes 301 and 302 can be shortened. Also, since the inclination angle gradually increases from the first slope 301 that is farthest from the second flow path substrate 100, the concentration of stress on the passivation film 900 when driving the piezoelectric body 400 can be alleviated.

[0049] <First Modified Example> FIG. 4 is an enlarged cross-sectional view schematically showing a part of the actuator 700 according to the first modified example. Since the individual members in the first modified example have the same configuration as those in the above-described embodiment, the same reference numerals as those of the respective members in the above-described embodiment are used for description. In the first modified example, three slopes 301, 302, and 303 are formed at the +X direction side end portion on the upper surface of the first electrode 300 as another example of a plurality of slopes. Note that three slopes are also formed at the +Y direction side end portion and the -Y direction side end portion on the upper surface of the first electrode 300.

[0050] In the first modification, among the three slopes 301, 302, and 303, the slope farthest from the second flow path substrate 100 in the +Z direction is referred to as the first slope 301. Among the three slopes 301, 302, and 303, the slope second farthest from the second flow path substrate 100 is referred to as the second slope 302. Among the three slopes 301, 302, and 303, the slope third farthest from the second flow path substrate 100 is referred to as the third slope 303. The angle between the first slope 301 and the second flow path substrate 100 is referred to as the first angle θ1, and the angle between the second slope 302 and the second flow path substrate 100 is referred to as the second angle θ2. The angle between the third slope 303 and the second flow path substrate 100 is referred to as the third angle θ3. Note that the angle between each slope of the first electrode 300 and the second flow path substrate 100 is the angle between each slope of the first electrode 300 and the flat surface on the second flow path substrate 100, similar to the above-described embodiment.

[0051] The first slope 301 is formed in a planar shape that extends long in the Y direction. The first slope 301 extends obliquely downward from the end of the portion parallel to the second flow path substrate 100 on the upper surface of the first electrode 300. The second slope 302 is formed in a planar shape that extends long in the Y direction parallel to the first slope 301. The second slope 302 extends obliquely downward from the lower end of the first slope 301. The third slope 303 is formed in a planar shape that extends long in the Y direction parallel to the first slope 301 and the second slope 302. The third slope 303 extends obliquely downward from the lower end of the second slope 302. Also, the first angle θ1 is smaller than the second angle θ2 and the third angle θ3. In other words, the second angle θ2 is larger than the first angle θ1, and the third angle θ3 is larger than the second angle θ2. The portion of the piezoelectric body 400 covering the three slopes 301, 302, and 303 is inclined with respect to the second flow path substrate 100 along the three slopes 301, 302, and 303.

[0052] According to the first modification, similar to the above-described embodiment, it is possible to provide the actuator 700 having a wide effective region of the piezoelectric body 400 and high reliability.

[0053] Further, the first angle θ1 is preferably 12 degrees or more and 22 degrees or less. The second angle θ2 is preferably 27 degrees or more and 37 degrees or less. The third angle θ3 is preferably 67 degrees or more and 77 degrees or less. Thereby, the covering property of the insulating film 600 covering the side surface on the +X direction side of the piezoelectric body 400 can be improved, and the horizontal lengths of the three inclined surfaces 301, 302, and 303 can be shortened.

[0054] In addition, the three inclined surfaces 301, 302, and 303 may each be formed of a curved surface. In other words, the first inclined surface 301 may be formed of a curved surface, the second inclined surface 302 may be formed of a curved surface, and the third inclined surface 303 may be formed of a curved surface. In this case, a portion where the angle between the tangent plane of each inclined surface and the second flow path substrate 100 changes discontinuously is defined as the boundary portion between the first inclined surface 301, the second inclined surface 302, and the third inclined surface 303. Also in this case, the first inclined surface 301 is formed in a curved surface shape that is convexly curved in a cross section (XZ cross section) viewed from the Y direction. The second inclined surface 302 is formed in a curved surface shape that is convexly curved with a curvature larger than that of the first inclined surface 301 in a cross section viewed from the Y direction. The third inclined surface 303 is formed in a curved surface shape that is convexly curved with a curvature larger than that of the second inclined surface 302 in a cross section viewed from the Y direction. The angle between the tangent plane of the first inclined surface 301 and the second flow path substrate 100 decreases as the contact point between the tangent plane of the first inclined surface 301 and the first inclined surface 301 moves farther from the second flow path substrate 100. The angle between the tangent plane of the second inclined surface 302 and the second flow path substrate 100 decreases as the contact point between the tangent plane of the second inclined surface 302 and the second inclined surface 302 moves farther from the second flow path substrate 100. The angle between the tangent plane of the third inclined surface 303 and the second flow path substrate 100 decreases as the contact point between the tangent plane of the third inclined surface 303 and the third inclined surface 303 moves farther from the second flow path substrate 100.

[0055] As a result, similar to the above-described embodiments, the covering property of the insulating film 600 covering the side surface on the +X direction side of the piezoelectric body 400 can be improved, and the horizontal lengths of the three slopes 301, 302, and 303 can be shortened. Further, since the inclination angle gradually increases from the first slope 301 that is the farthest from the second flow path substrate 100, the concentration of stress on the passivation film 900 when driving the piezoelectric body 400 can be alleviated.

[0056] Note that four or more slopes, such as four slopes, five slopes, and six slopes, may be formed at the end on the +X direction side of the upper surface of the first electrode 300. Here, let an integer of 3 or more be N, and an integer of 2 or more and N or less be k. Among the N slopes, the angle between the slope that is the k-th farthest from the second flow path substrate 100 and the second flow path substrate 100 is preferably larger than the angle between the slope that is the (k - 1)-th farthest from the second flow path substrate 100 and the second flow path substrate 100.

[0057] <Second Modified Example> FIG. 5 is an enlarged cross-sectional view schematically showing a part of the actuator 700 according to the second modified example. Since the individual members in the second modified example have the same configuration as those in the above-described embodiments, the same reference numerals as those of the respective members in the above-described embodiments will be used for description. As shown in FIG. 5, the piezoelectric body 400 of the second modified example is formed to extend up to the upper surface of the insulating film 200 beyond the end on the +X direction side of the first electrode 300.

[0058] According to the second modified example, similar to the above-described embodiments, an actuator 700 having a wide effective area of the piezoelectric body 400 and high reliability can be provided.

[0059] When the piezoelectric body 400 is formed by a sputtering method, the portion covering each slope of the first electrode 300 in the piezoelectric body 400 is likely to be inclined with respect to the second flow path substrate 100, as shown in FIG. 3, for example. Thereby, the step portion of the insulating film 600 that the upper wiring 801 electrically connected to the second electrode 500 crosses can be made lower. Further, even when the piezoelectric body 400 is formed by a sputtering method, depending on the film formation conditions of the piezoelectric body 400 such as pressure and power, the end portion of the piezoelectric body 400 can be made close to being parallel to the second flow path substrate 100.

[0060] <Third Modification> FIG. 6 is an enlarged cross-sectional view schematically showing a part of the actuator 700 of the third modification. Since the individual members in the third modification have the same configuration as those in the above-described embodiment, the same reference numerals as those of the respective members in the above-described embodiment will be used for description. The piezoelectric body 400 of the third modification is formed by a spin coating method. As shown in FIG. 6, when the piezoelectric body 400 is formed by a spin coating method, the portion covering each slope of the first electrode 300 in the piezoelectric body 400 is likely to have a smaller inclination with respect to the second flow path substrate 100 than when the piezoelectric body 400 is formed by a sputtering method. However, by adjusting the number of coating times by the spin coating method, the thickness of the piezoelectric body 400, the viscosity of the piezoelectric body 400, etc., the end portion of the piezoelectric body 400 can be inclined with respect to the second flow path substrate 100 in the same manner as when the piezoelectric body 400 is formed by a sputtering method. Thereby, similar to the case where the piezoelectric body 400 is formed by a sputtering method, the photolithography process and the etching process when forming the upper wiring 801 on the upper surface of the insulating film 600 located above the piezoelectric body 400 are facilitated.

[0061] According to the third modification, similar to the above-described embodiment, it is possible to provide the actuator 700 having a wide effective area of the piezoelectric body 400 and high reliability.

[0062] In the above-described embodiment, among the first electrode 300 and the second electrode 500, only the first electrode 300 may be formed of platinum, or both the first electrode 300 and the second electrode 500 may be formed of platinum.

[0063] In the above-described embodiment, the actuator 700 is used in the liquid discharge head 4 of the liquid discharge device, but is not limited thereto. For example, the actuator may be used in a speaker or a hard disk drive. Further, the actuator may be used in an autofocus mechanism of a portable camera module or an anti-shake mechanism of a digital camera.

[0064] <<Example>> Next, a specific example regarding the actuator 700 will be described with reference to the drawings.

[0065] <Example 1> Example 1 is an example corresponding to the above-described embodiment. In Example 1, the configuration and manufacturing method of the actuator 700 when forming the piezoelectric body 400 by the sputtering method will be described. Note that since the individual members in Example 1 have the same configuration as those in the above-described embodiment, the same reference numerals as those of the respective members in the above-described embodiment will be used for description.

[0066] FIGS. 7 and 8 are cross-sectional process diagrams for explaining the manufacturing process of Example 1. As shown in FIG. 7(a), a silicon single crystal substrate 100E serving as a material for the second flow path substrate 100 was prepared. Hereinafter, the substrate 100E serving as a material for the second flow path substrate 100 will simply be referred to as the substrate 100E. A silicon oxide film having a thickness of 500 nm was formed on the upper surface of this substrate 100E by a wet oxidation method using oxygen and hydrogen gases (O2 and H2 gases) to form the insulating film 200.

[0067] Subsequently, as shown in FIG. 7(b), a first electrode 300 was formed on the insulating film 200. When forming the first electrode 300, a film serving as the material of the first electrode 300 was formed on the upper surface of the insulating film 200 by sputtering. After film formation, a resist pattern was formed by photolithography so that the first electrode 300 would have a desired pattern, and etching by a dry etching method was performed to form the first electrode 300. By performing etching by the dry etching method, a plurality of inclined surfaces (for example, two inclined surfaces 301 and 302) were formed at the end of the upper surface of the first electrode 300. Incidentally, the material of the first electrode 300 was platinum, and the thickness of the first electrode 300 was 100 nm. As an adhesion layer for improving the adhesion between the first electrode 300 and the insulating film 200, a laminate of titanium and titanium oxide (not shown) was formed by sputtering.

[0068] Also, three inclined surfaces 301, 302, and 303 may be formed at the end of the upper surface of the first electrode 300. In this case, for example, the first angle θ1 can be 17 degrees, the second angle θ2 can be 32 degrees, and the third angle θ3 can be 72 degrees.

[0069] By adjusting the etching conditions when forming the first electrode 300, the end of the upper surface of the first electrode 300 can be made into a structure composed of a plurality of inclined surfaces that are planar or curved. For example, while retracting the resist during etching, a reaction product is deposited on the etched surface of the first electrode 300, and by adjusting the etching conditions of the dry etching apparatus, the end of the upper surface of the first electrode 300 can be made into a desired structure. The etching conditions depend on the configuration of the etching apparatus. For example, the RF power can be 400 - 600 W, the Bias power can be 100 - 200 W, the pressure can be 0.3 - 1.0 Pa, and the gas used can be a gas mixture of chlorine and argon.

[0070] Subsequently, as shown in FIG. 7(c), a piezoelectric body 400 was formed on top of the first electrode 300, and a second electrode 500 was formed on top of the piezoelectric body 400. When forming the second electrode 500 and the piezoelectric body 400, a film serving as the material of the piezoelectric body 400 was formed on the upper surface of the first electrode 300 by a sputtering method. Also, by a sputtering method, a film serving as the material of the second electrode 500 was formed on the upper surface of the film serving as the material of the piezoelectric body 400. After film formation, a resist pattern was formed by photolithography so that the second electrode 500 and the piezoelectric body 400 would have a desired pattern, and the second electrode 500 and the piezoelectric body 400 were formed by etching. Note that the material of the piezoelectric body 400 was lead zirconate titanate, and the thickness of the piezoelectric body 400 was 2 μm. The material of the second electrode 500 was an alloy of titanium and tungsten, and the thickness of the second electrode 500 was 120 nm.

[0071] Thereby, a piezoelectric element 140 (see FIG. 2(b)) composed of the first electrode 300, the piezoelectric body 400, and the second electrode 500 was formed. The portions of the piezoelectric body 400 (and the second electrode 500) that cover the respective slopes of the first electrode 300 are inclined with respect to the substrate 100E. The boundary line when patterning the piezoelectric body 400 may be on any one of the plurality of slopes of the first electrode 300 or on the insulating film 200. The side surface of the piezoelectric body 400 formed by etching may be perpendicular to the substrate 100E (upper surface) as shown in FIG. 7(c) or may be inclined with respect to the substrate 100E.

[0072] Subsequently, as shown in FIG. 7(d), an insulating film 600 with a thickness of 100 nm was formed on the upper sides of the first electrode 300, the piezoelectric body 400, and the second electrode 500 by CVD method. Also, a resist pattern was formed by photolithography so that the upper through-hole 601 and the lower through-hole 602 would have a desired pattern, and etching was performed to form the upper through-hole 601 and the lower through-hole 602 in the insulating film 600. Note that the material of the insulating film 600 was tetraethyl orthosilicate (TEOS). Further, when forming the first electrode 300 by etching using a dry etching method, considering that a part of the underlying insulating film 200 would be removed, the film thickness and film formation conditions of the insulating film 600 may be determined.

[0073] Subsequently, as shown in FIG. 8(a), an upper wiring 801 and a lower wiring 802 were formed on the insulating film 600. When forming the upper wiring 801 and the lower wiring 802, a film serving as the material of the upper wiring 801 and the lower wiring 802 was formed on the upper surface of the insulating film 600 by sputtering method. After film formation, a resist pattern was formed by photolithography so that the upper wiring 801 and the lower wiring 802 would have a desired pattern, and etching was performed to form the upper wiring 801 and the lower wiring 802. As a result, the upper wiring 801 is electrically connected to the second electrode 500 through the upper through-hole 601 of the insulating film 600, and the lower wiring 802 is electrically connected to the first electrode 300 through the lower through-hole 602 of the insulating film 600.

[0074] Subsequently, as shown in FIG. 8(b), a silicon nitride film with a thickness of 50 nm was formed on the upper sides of the upper wiring 801 and the lower wiring 802 by CVD method to form a highly insulating passivation film 900. When forming the passivation film 900, a resist pattern was formed by photolithography so that it would have a desired pattern, and then etching was performed to form an opening only in the central side of the portion of the passivation film 900 that overlaps with the second electrode 500. Thereby, the moisture resistance can be enhanced and the reliability of the upper wiring 801 and the lower wiring 802 can be improved.

[0075] In this way, the actuator 700 of Example 1 is completed. Although not shown, next, a process of forming a recess 110 for holding ink with respect to the substrate 100E was performed to fabricate the second flow path substrate 100. Next, the first flow path substrate 20 was joined to the lower surface side of the second flow path substrate 100, and the third flow path substrate 40 was joined to the upper surface side of the second flow path substrate 100, thereby fabricating a liquid ejection head including a plurality of actuators 700. Then, in the same manner as the conventional method for manufacturing a liquid ejection head, mounting and assembling of electrical components and support members of the liquid ejection head were carried out. In this way, the liquid ejection head unit is completed.

[0076] According to Example 1, an actuator 700 having a wide effective region of the piezoelectric body 400 and high reliability can be manufactured.

[0077] <Example 2> Example 2 is an example corresponding to the above-described embodiment. In Example 2, the configuration and manufacturing method of the actuator 700 when the piezoelectric body 400 is formed by the spin coating method will be described. Note that since the individual members in Example 2 have the same configuration as those in the above-described embodiment, the same reference numerals as those of the respective members in the above-described embodiment will be used for description.

[0078] FIGS. 9 and 10 are process cross-sectional views for explaining the manufacturing process of Example 2. As shown in FIG. 9(a), a silicon single crystal substrate 100E serving as a material for the second flow path substrate 100 was prepared. Similar to Example 1, an insulating film 200 was formed on the upper surface of this substrate 100E.

[0079] Subsequently, as shown in FIG. 9(b), similar to Example 1, the first electrode 300 was formed on top of the insulating film 200. When forming the first electrode 300, similar to Example 1, a plurality of inclined surfaces (for example, two inclined surfaces 301 and 302) were formed at the end of the upper surface of the first electrode 300.

[0080] Subsequently, as shown in FIG. 9(c), a piezoelectric body 400 was formed on top of the first electrode 300, and a second electrode 500 was formed on top of the piezoelectric body 400. When forming the second electrode 500 and the piezoelectric body 400, a film serving as the material for the piezoelectric body 400 was formed on the upper surface of the first electrode 300 by coating using the spin coating method, and then fired at 800° C. so as to achieve a desired crystal orientation. Also, a film serving as the material for the second electrode 500 was formed on the upper surface of the film serving as the material for the piezoelectric body 400 by sputtering. After film formation, a resist pattern was formed by photolithography so that the second electrode 500 and the piezoelectric body 400 would have a desired pattern, and the second electrode 500 and the piezoelectric body 400 were formed by etching. Note that the material of the piezoelectric body 400 was lead zirconate titanate, and the thickness of the piezoelectric body 400 was 2 μm. The material of the second electrode 500 was an alloy of titanium and tungsten, and the thickness of the second electrode 500 was 120 nm.

[0081] Thereby, a piezoelectric element 140 (see FIG. 2(b)) composed of the first electrode 300, the piezoelectric body 400, and the second electrode 500 was formed. The portion covering each slope of the first electrode 300 in the piezoelectric body 400 (and the second electrode 500) is gently inclined with respect to the substrate 100E as compared with the case of forming the piezoelectric body 400 by sputtering. The boundary line when patterning the piezoelectric body 400 may be on any one of the plurality of slopes of the first electrode 300 or on the insulating film 200. The side surface of the piezoelectric body 400 formed by etching may be perpendicular to the substrate 100E (upper surface) as shown in FIG. 9(c) or may be inclined with respect to the substrate 100E.

[0082] Subsequently, as shown in FIG. 9(d), in the same manner as in Example 1, an insulating film 600 with a thickness of 100 nm was formed on the upper sides of the first electrode 300, the piezoelectric body 400, and the second electrode 500. When forming the insulating film 600, upper through holes 601 and lower through holes 602 were formed in the insulating film 600 in the same manner as in Example 1.

[0083] Subsequently, as shown in Fig. 10(a), similar to Example 1, upper wiring 801 and lower wiring 802 were formed on the insulating film 600. As a result, the upper wiring 801 is electrically connected to the second electrode 500 through the upper through-hole 601 of the insulating film 600, and the lower wiring 802 is electrically connected to the first electrode 300 through the lower through-hole 602 of the insulating film 600.

[0084] Subsequently, as shown in Fig. 10(b), similar to Example 1, a highly insulating passivation film 900 was formed on the upper sides of the upper wiring 801 and the lower wiring 802. When forming the passivation film 900, similar to Example 1, an opening was formed only at the central portion of the portion of the passivation film 900 that overlaps with the second electrode 500. As a result, the moisture resistance can be enhanced and the reliability of the upper wiring 801 and the lower wiring 802 can be improved.

[0085] In this way, the actuator 700 of Example 2 is completed. Although not shown, next, a process of forming a recess 110 for holding ink in the substrate 100E was performed to fabricate the second flow path substrate 100. Next, a plurality of actuators 700 were provided by bonding the first flow path substrate 20 to the lower surface side of the second flow path substrate 100 and bonding the third flow path substrate 40 to the upper surface side of the second flow path substrate 100. And, similar to the manufacturing method of the conventional liquid ejection head, mounting and assembling of electrical components and support members of the liquid ejection head were carried out. In this way, the liquid ejection head unit is completed.

[0086] According to Example 2, an actuator 700 with a wide effective area of the piezoelectric body 400 and high reliability can be manufactured.

[0087] <<Other Embodiments>> The disclosure of each embodiment includes configurations represented by the following actuator examples, liquid ejection head examples, and liquid ejection device examples.

[0088] <Configuration 1> An actuator having, in this order on the surface of a substrate, a first electrode, a piezoelectric body, and a second electrode, and further having an insulating film covering at least the side surface of the piezoelectric body, A plurality of inclined surfaces inclined with respect to the substrate are formed at an end portion of a surface of the first electrode on the side opposite to the substrate, An actuator, wherein an angle between a first inclined surface, which is the farthest from the substrate among the plurality of inclined surfaces, and the substrate is smaller than an angle between the other inclined surfaces and the substrate.

[0089] <Configuration 2> The actuator according to Configuration 1, wherein at least the first electrode among the first electrode and the second electrode is formed of platinum.

[0090] <Configuration 3> The actuator according to Configuration 1 or 2, wherein the material of the piezoelectric body is lead zirconate titanate.

[0091] <Configuration 4> The actuator according to any one of Configurations 1 to 3, wherein an angle between the first inclined surface and the substrate is 12 degrees or more and 22 degrees or less.

[0092] <Configuration 5> The actuator according to any one of Configurations 1 to 4, wherein an angle between a second inclined surface, which is the second farthest from the substrate among the plurality of inclined surfaces, and the substrate is 27 degrees or more and 37 degrees or less.

[0093] <Configuration 6> The plurality of inclined surfaces are three inclined surfaces, The actuator according to any one of Configurations 1 to 5, wherein an angle between a third inclined surface, which is the third farthest from the substrate among the three inclined surfaces, and the substrate is 67 degrees or more and 77 degrees or less.

[0094] <Configuration 7> The plurality of inclined surfaces are three inclined surfaces, Of the three slopes, the angle between the second slope, which is the second farthest from the substrate, and the substrate is greater than the angle between the first slope and the substrate. The actuator according to any one of Configurations 1 to 6, wherein the angle between the third slope, which is the third farthest from the substrate, and the substrate among the three slopes is greater than the angle between the second slope and the substrate.

[0095] <Configuration 8> Each of the plurality of slopes is formed of a curved surface. The actuator according to any one of Configurations 1 to 7, wherein the angle between the tangent plane of the curved surface and the substrate decreases as the contact point between the curved surface and the tangent plane moves farther from the substrate.

[0096] <Configuration 9> The piezoelectric body covers at least a part of the plurality of slopes. The actuator according to any one of Configurations 1 to 8.

[0097] <Configuration 10> The actuator according to Configuration 9, wherein the portion of the piezoelectric body covering at least a part of the plurality of slopes is inclined with respect to the substrate.

[0098] <Configuration 11> The actuator according to any one of Configurations 1 to 10, wherein the insulating film covers at least a part of the plurality of slopes in the first electrode.

[0099] <Configuration 12> The actuator according to any one of Configurations 1 to 11, wherein the insulating film covers the surface of the second electrode on the side opposite to the piezoelectric body.

[0100] <Configuration 13> The actuator according to Configuration 12, wherein the insulating film has a through hole for connecting a wiring electrically connected to the second electrode and the second electrode.

[0101] <Configuration 14> A liquid ejection head that ejects liquid by driving the actuator according to any one of Configurations 1 to 13.

[0102] <Configuration 15> A liquid ejection device including the liquid ejection head according to Configuration 14 that ejects liquid.

Description of Signs

[0103] 100 Second flow path substrate 200 Insulating film 300 First electrode 301 First inclined surface 302 Second inclined surface 400 Piezoelectric body 500 Second electrode 600 Insulating film 700 Actuator

Claims

1. An actuator having, in this order on the surface of a substrate, a first electrode, a piezoelectric body, and a second electrode, and further having an insulating film covering at least the side surface of the piezoelectric body, a plurality of inclined surfaces inclined with respect to the substrate are formed at an end of a surface of the first electrode on a side opposite to the substrate, An actuator, wherein an angle between a first inclined surface farthest from the substrate and the substrate among the plurality of inclined surfaces is smaller than an angle between the other inclined surfaces and the substrate.

2. The actuator according to claim 1, wherein at least the first electrode among the first electrode and the second electrode is formed of platinum.

3. The actuator according to claim 1, wherein the material of the piezoelectric body is lead zirconate titanate.

4. The actuator according to claim 1, wherein an angle between the first inclined surface and the substrate is 12 degrees or more and 22 degrees or less.

5. The actuator according to claim 1, wherein an angle between a second inclined surface second farthest from the substrate and the substrate among the plurality of inclined surfaces is 27 degrees or more and 37 degrees or less.

6. The plurality of inclined surfaces are three inclined surfaces, The actuator according to claim 1, wherein an angle between a third inclined surface third farthest from the substrate and the substrate among the three inclined surfaces is 67 degrees or more and 77 degrees or less.

7. The plurality of inclined surfaces are three inclined surfaces, Among the three inclined surfaces, an angle between a second inclined surface second farthest from the substrate and the substrate is larger than an angle between the first inclined surface and the substrate, The actuator according to claim 1, wherein an angle between a third inclined surface third farthest from the substrate and the substrate among the three inclined surfaces is larger than an angle between the second inclined surface and the substrate.

8. Each of the plurality of inclined surfaces is formed of a curved surface, The actuator according to claim 1, wherein an angle between a tangent plane of the curved surface and the substrate decreases as a contact point between the curved surface and the tangent plane moves farther from the substrate.

9. The piezoelectric body covers at least a part of the plurality of inclined surfaces. The actuator according to claim 1.

10. The actuator according to claim 9, wherein a portion of the piezoelectric body covering at least a part of the plurality of inclined surfaces is inclined with respect to the substrate.

11. The actuator according to claim 1, wherein the insulating film covers at least a part of the plurality of inclined surfaces in the first electrode.

12. The actuator according to claim 1, wherein the insulating film covers a surface of the second electrode on a side opposite to the piezoelectric body.

13. The actuator according to claim 12, wherein the insulating film has a through hole for connecting a wiring electrically connected to the second electrode and the second electrode.

14. A liquid ejection head that ejects liquid by driving the actuator according to any one of claims 1 to 13.

15. A liquid ejection device including the liquid ejection head according to claim 14 that ejects liquid.

Images