JP5321832B2 - Liquid ejecting head, liquid ejecting apparatus, and actuator device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid jetting head having improved drive durability, liquid jetting device, and actuator device. <P>SOLUTION: Reinforcing portions 65 composed of a material harder than the film forming a first electrode 60 are provided in the regions on the first electrode 60, wherein the regions correspond to both-end portions of a piezoelectric layer 70 in the width-direction of a piezoelectric element 300. The thickness of the reinforcing portions 65 is gradually reduced toward the inside of the width direction of the piezoelectric element 300. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a liquid ejecting head, a liquid ejecting apparatus, and an actuator device having a piezoelectric element displaceably provided on a substrate.

  A piezoelectric element used for a liquid ejecting head or the like has a configuration in which a piezoelectric layer made of a piezoelectric material exhibiting an electromechanical conversion function is sandwiched between two electrodes. As a typical example of the liquid ejecting head, for example, a part of the pressure generating chamber communicating with the nozzle opening for ejecting ink droplets is configured by a diaphragm, and the diaphragm is deformed by a piezoelectric element to There are ink jet recording heads that pressurize ink and eject ink droplets from nozzle openings. In addition, as a piezoelectric element mounted on the ink jet recording head, for example, a uniform piezoelectric material layer is formed over the entire surface of the diaphragm by a film forming technique, and this piezoelectric material layer is formed into a pressure generating chamber by a lithography method. There is one in which a piezoelectric element is formed so as to be separated into a corresponding shape and independent for each pressure generation chamber (for example, see Patent Document 1).

JP 2003-163387 A

  However, at the time of driving, stress concentrates in the vicinity of both ends in the width direction of the piezoelectric element of the diaphragm, and the diaphragm is broken, resulting in a decrease in driving durability.

  Such a problem is not limited to a liquid jet head typified by an ink jet recording head, and similarly exists in an actuator device mounted in another device.

  In view of such circumstances, it is an object of the present invention to provide a liquid ejecting head, a liquid ejecting apparatus, and an actuator device that have improved driving durability.

Aspect of the present invention for solving the above-mentioned problems, and the flow path forming substrate pressure generating chambers are arranged communicating with nozzle openings for ejecting a liquid, a first electrode provided on the passage forming substrate, said first comprising a second electrode provided on the first piezoelectric layer provided on the electrode and the piezoelectric layer, and a piezoelectric element corresponding to each pressure generating chamber, the piezoelectric element, the pressure generating chamber has a width along the arrangement direction, the first a on the electrode, the at the region corresponding to both ends of the piezoelectric layer in the width direction of the piezoelectric element, than the membrane that forms the first electrode The liquid ejecting head includes a reinforcing portion made of a hard material , and the thickness of the reinforcing portion gradually decreases toward the inner side in the width direction of the piezoelectric element.
In such an aspect, by providing a reinforcing portion made of a material harder than the film forming the first electrode in a region corresponding to both ends of the piezoelectric layer, the first electrode has a resistance against stress concentration at the widthwise end portion of the piezoelectric element. The rigidity is increased, and the driving durability of the piezoelectric element can be improved. Further, the reinforcing portion is gradually reduced in thickness toward the inner side in the width direction of the piezoelectric element, whereby the stress at the end portion in the width direction of the piezoelectric element can be dispersed to suppress stress concentration.

  The reinforcing portion is preferably made of a material having a Vickers hardness Hv of 1000 or more. According to this, it is possible to effectively improve the driving durability of the piezoelectric element.

  It is preferable that an arm portion extending continuously outward from the reinforcing portion in the width direction of the piezoelectric element is provided. According to this, an arm part functions as an etching stop layer, and can suppress the dispersion | variation in the film thickness of a 1st electrode. Thereby, the dispersion | variation in the resonant frequency and displacement amount of a piezoelectric element can be suppressed.

  The arm portion is preferably thinner than the reinforcing portion. According to this, it is possible to improve the driving durability of the piezoelectric element while securing a high displacement amount of the first electrode.

  It is preferable that a concave portion is provided at a boundary portion between the reinforcing portion and the arm portion, and an inner surface of the concave portion is curved. According to this, the stress applied to the first electrode at the end in the width direction of the piezoelectric element can be more effectively dispersed.

  A second reinforcing portion made of a material harder than the film forming the first electrode is provided in the longitudinal direction of the pressure generating chamber on the first electrode and in the center in the width direction of the piezoelectric element. It is preferred that According to this, the driving durability in the longitudinal direction of the piezoelectric element can be improved.

  It is preferable that the thickness of the second reinforcing portion gradually decreases toward the outer side in the width direction of the piezoelectric element. According to this, the stress with respect to the 2nd reinforcement part can be disperse | distributed, and stress concentration can be suppressed.

  It is preferable that a coating film made of an insulator covering at least the side surface of the piezoelectric layer is provided. According to this, destruction of the piezoelectric element due to moisture in the atmosphere can be suppressed.

According to still another aspect of the invention, there is provided a liquid ejecting apparatus including the liquid ejecting head according to the above aspect.
In this aspect, a liquid ejecting apparatus with improved reliability can be realized.

Furthermore, another aspect of the present invention includes a first electrode provided on a substrate, a piezoelectric layer provided on the first electrode, and a second electrode provided on the piezoelectric layer. Reinforcement made of a material harder than the film forming the first electrode in a region corresponding to both end portions of the piezoelectric layer in the width direction of the piezoelectric element on the first electrode. The actuator device is characterized in that a thickness is gradually reduced toward the inner side in the width direction of the piezoelectric element.
In such an aspect, by providing a reinforcing portion made of a material harder than the film forming the first electrode in a region corresponding to both ends of the piezoelectric layer, the first electrode has a resistance against stress concentration at the widthwise end portion of the piezoelectric element. The rigidity is increased, and the driving durability of the piezoelectric element can be improved. Further, the reinforcing portion is gradually reduced in thickness toward the inner side in the width direction of the piezoelectric element, whereby the stress at the end portion in the width direction of the piezoelectric element can be dispersed to suppress stress concentration.

FIG. 3 is an exploded perspective view illustrating a schematic configuration of the recording head according to the first embodiment. 2A and 2B are a plan view and a cross-sectional view of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view of a main part of the recording head according to the first embodiment. FIG. 3 is a plan view of a main part of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating the method for manufacturing the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating the method for manufacturing the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating the method for manufacturing the recording head according to the first embodiment. FIG. 2 is a perspective view illustrating a schematic configuration of the recording apparatus according to the first embodiment. FIG. 6 is a cross-sectional view of a main part of a piezoelectric element and a pressure generation chamber of a recording head according to a second embodiment. FIG. 9 is a cross-sectional view of a main part of a piezoelectric element and a pressure generation chamber of a recording head according to a third embodiment. FIG. 6 is a cross-sectional view of main parts of a piezoelectric element and a pressure generation chamber of a recording head according to a fourth embodiment.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
FIG. 1 is an exploded perspective view showing a schematic configuration of an ink jet recording head which is an example of a liquid jet head according to Embodiment 1 of the present invention. FIG. 2 is a plan view of a flow path forming substrate and its AA. 'Is a sectional view, and FIG. 3 is a sectional view taken along the line BB ′ of FIG.

  As shown in the drawing, the flow path forming substrate 10 is made of a silicon single crystal substrate in the present embodiment, and an elastic film 50 made of an oxide film is formed on one surface thereof.

  A plurality of pressure generating chambers 12 are arranged in parallel in the width direction of the flow path forming substrate 10. In addition, a communication portion 13 is formed in a region outside the longitudinal direction of the pressure generation chamber 12 of the flow path forming substrate 10, and the communication portion 13 and each pressure generation chamber 12 are provided for each pressure generation chamber 12. Communication is made via a supply path 14 and a communication path 15. The communication part 13 communicates with a reservoir part 31 of a protective substrate, which will be described later, and constitutes a part of a reservoir that becomes a common ink chamber of each pressure generating chamber 12. The ink supply path 14 is formed with a narrower width than the pressure generation chamber 12, and maintains a constant flow path resistance of ink flowing into the pressure generation chamber 12 from the communication portion 13. In this embodiment, the ink supply path 14 is formed by narrowing the width of the flow path from one side. However, the ink supply path may be formed by narrowing the width of the flow path from both sides. Further, the ink supply path may be formed by narrowing from the thickness direction instead of narrowing the width of the flow path.

  Further, on the opening surface side of the flow path forming substrate 10, a nozzle plate 20 having a nozzle opening 21 communicating with the vicinity of the end of each pressure generating chamber 12 on the side opposite to the ink supply path 14 is provided with an adhesive. Or a heat-welded film or the like. The nozzle plate 20 is made of, for example, glass ceramics, a silicon single crystal substrate, or stainless steel.

  On the other hand, the elastic film 50 is formed on the side opposite to the opening surface of the flow path forming substrate 10 as described above, and the insulator film 55 is formed on the elastic film 50. Further, the first electrode 60, the piezoelectric layer 70, and the second electrode 80 are laminated on the insulator film 55 by a process described later to constitute the piezoelectric element 300. Here, the piezoelectric element 300 refers to a portion including the first electrode 60, the piezoelectric layer 70, and the second electrode 80. In general, one electrode of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each pressure generating chamber 12. In addition, here, a portion that is configured by any one of the patterned electrodes and the piezoelectric layer 70 and in which piezoelectric distortion is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion. In the present embodiment, the first electrode 60 is a common electrode of the piezoelectric element 300, and the second electrode 80 is an individual electrode of the piezoelectric element 300. However, there is no problem even if this is reversed for the convenience of the drive circuit and wiring.

  The piezoelectric layer 70 is made of a piezoelectric material that is formed on the first electrode 60 and has an electromechanical conversion effect, and in particular, a ferroelectric material having a perovskite structure among the piezoelectric materials. The piezoelectric layer 70 is preferably a crystal film having a perovskite structure. For example, a ferroelectric material such as lead zirconate titanate (PZT) or a metal oxide such as niobium oxide, nickel oxide, or magnesium oxide is used. Those to which is added are suitable.

  As shown in FIGS. 2 and 3, in the present embodiment, a region in which the end portion in the longitudinal direction of the pressure generation chamber 12 of the first electrode 60 (the end portion in the longitudinal direction of the piezoelectric element 300) is opposed to the pressure generation chamber 12. By providing the inside, the end portion (length) in the longitudinal direction of the piezoelectric active portion serving as a substantial driving portion of the piezoelectric element 300 is defined. Further, by providing an end in the short direction of the pressure generation chamber 12 of the second electrode 80 (an end in the short direction of the piezoelectric element 300) in a region facing the pressure generation chamber 12, the piezoelectric active portion The end portion (width) in the short direction is defined. That is, the piezoelectric active part is provided only in a region opposite to the pressure generating chamber 12 by the patterned first electrode 60 and second electrode 80. Furthermore, in this embodiment, as shown in FIG. 3, the piezoelectric layer 70 and the second electrode 80 are patterned so that the width on the second electrode 80 side is narrow, and the side surfaces thereof are inclined surfaces.

  Here, a device for providing the piezoelectric element 300 on a predetermined substrate and driving the piezoelectric element 300 is referred to as an actuator device. In the present embodiment, the elastic film 50, the insulator film 55, and the first electrode 60 function as a diaphragm, but of course not limited to this, for example, without providing the elastic film 50 and the insulator film 55. Only the first electrode 60 may act as a diaphragm.

  Further, as shown in FIG. 3, the region on the first electrode 60 and corresponding to both ends of the piezoelectric layer 70 in the width direction of the piezoelectric element 300 is harder than the film forming the first electrode 60. A reinforcing portion 65 made of a material is provided. The reinforcing portion 65 is a region on the first electrode 60 corresponding to both end portions of the piezoelectric layer 70 in the width direction of the piezoelectric element 300, specifically, between the first electrode 60 and the piezoelectric layer 70. Is provided. An arm portion 66 extends continuously from the reinforcing portion 65 to the outside in the width direction of the piezoelectric element 300. Thus, the reinforcement part 65 and the arm part 66 are integral, and comprise the reinforcement film | membrane.

  In other words, the reinforcing film includes a reinforcing portion 65 provided between the first electrode 60 and the piezoelectric layer 70, and an arm portion 66 extending continuously from the reinforcing portion 65 to the outside in the width direction of the piezoelectric element 300. And has an opening in a region facing the piezoelectric element 300, and an end portion is provided so as to enter the piezoelectric layer 70.

  The reinforcing portion 65 described above gradually decreases in thickness toward the inner side in the width direction of the piezoelectric element 300. That is, the end portion of the reinforcing film has a tapered shape whose thickness gradually decreases toward the pressure generating chamber 12 side.

  In the present embodiment, the arm portion 66 extends to a region corresponding to the partition wall 11 that partitions the pressure generation chamber 12 in the juxtaposition direction.

  The reinforcing portion 65 may be provided in a region corresponding to at least both ends of the piezoelectric layer 70, and is opposed to the piezoelectric active portion as long as the displacement of the piezoelectric element 300 (piezoelectric active portion) is not hindered. It may be provided up to the area.

  Here, FIG. 4 is a plan view of the reinforcing portion 65, the arm portion 66, and the second reinforcing portion 67 described later on the flow path forming substrate.

  As shown in FIGS. 3 and 4, a second reinforcing portion 67 made of a material harder than the film forming the first electrode 60 is provided on the first electrode 60 and in the center in the width direction of the piezoelectric element 300. It is provided over the longitudinal direction of the pressure generating chamber 12. In the present embodiment, the second reinforcing portion 67 is provided so that the end portion is outside the longitudinal end portion of the pressure generating chamber 12. In addition, both end portions of the second reinforcing portion 67 are gradually reduced in thickness toward the outer side in the width direction of the piezoelectric element 300. In the present embodiment, the second reinforcing portion 67 is provided so that the end portion is outside the longitudinal end portion of the pressure generating chamber 12, but the second reinforcing portion 67 extends in the longitudinal direction. As long as it is provided. For example, the end of the second reinforcing portion 67 may be outside or inside the longitudinal end of the pressure generating chamber 12 or may be provided intermittently.

Here, the reinforcing film (the reinforcing part 65 and the arm part 66) and the second reinforcing part 67 are made of a material harder than the film forming the first electrode 60. The material of the reinforcing portion 65, the arm portion 66, and the second reinforcing portion 67 preferably has a Vickers hardness Hv of 1000 or more. For example, diamond-like carbon (DLC), titanium carbonitride (TiCN), titanium nitride aluminum ( TiAlN), aluminum oxide (Al ₂ O ₃ ), titanium diboride (TiB ₂ ), vanadium carbide (VC), titanium carbide (TiC), ditungsten pentaboride (W ₂ B ₅ ), niobium diboride ( NbB ₂ ), zirconium carbide (ZrC), lanthanum hexaboride (LaB ₆ ), tungsten carbide (WC), dimolybdenum pentaboride (Mo ₂ B ₅ ), zirconium diboride (ZrB ₂ ), chromium diboride _(CrB 2), two carbide three chromium _{(Cr 3 C} 2), diboride, vanadium _(VB 2), diboride, tantalum _(TaB 2) Titanium nitride (TiN), niobium carbide (NbC), carbide Molybdenum _(Mo 2 C), zirconium nitride (ZrN), vanadium nitride (VN), tantalum carbide (TaC), niobium nitride (NbN), chromium nitride (CrN) Is mentioned. The materials of the reinforcing portion 65 and the arm portion 66 and the second reinforcing portion 67 are preferably made of the same material from the viewpoint that they can be molded simultaneously as described later, but may be different. Moreover, the thickness of the reinforcement part 65, the arm part 66, and the 2nd reinforcement part 67 is not specifically limited, What is necessary is just a grade which does not reduce the displacement amount of a diaphragm significantly. In this embodiment, diamond-like carbon (DLC) having a thickness of 50 nm is used.

  As described above, by providing the reinforcing portions 65 made of a material harder than the first electrode 60 in the regions corresponding to the both ends in the width direction of the piezoelectric layer 70, the stress concentration at the end portions in the width direction of the piezoelectric element 300 is reduced. The rigidity of one electrode 60 is increased, and the driving durability of the piezoelectric element 300 can be improved. In other words, there is no possibility that the diaphragm including the first electrode 60 is broken even if the driving of the piezoelectric element 300 is repeated.

  Further, since the reinforcing portion 65 gradually decreases in thickness toward the inner side in the width direction of the piezoelectric element 300, the stress at the end portion in the width direction of the piezoelectric element 300 is dispersed and the stress on the first electrode 60 is reduced. Concentration can be suppressed. Thereby, destruction of the diaphragm including the first electrode 60 is suppressed, and the driving durability of the piezoelectric element 300 can be improved. Further, since the contact area with the first electrode 60 can be ensured even if the contact area with the piezoelectric layer 70 is small, the driving durability of the piezoelectric element 300 can be improved without deteriorating the displacement characteristics of the piezoelectric element 300. Can be improved.

  In addition, since the arm portion 66 extends to a region corresponding to the partition wall that divides the pressure generating chamber 12 in the juxtaposed direction, the arm portion is formed when the piezoelectric layer 70 and the second electrode 80 are formed by etching. 66 acts as an etching stop layer. Etching is substantially stopped by etching the piezoelectric layer 70 until the arm portion 66 is exposed. Thereby, the 1st electrode 60 is not etched and the dispersion | variation in the film thickness of the 1st electrode 60 can be suppressed. Therefore, variations in the resonance frequency and displacement of the piezoelectric element 300 in the plane of the flow path forming substrate 10 can be suppressed. As a result, there is no variation in the liquid discharge amount for each piezoelectric element 300.

  A second reinforcing portion 67 made of a material harder than the film forming the first electrode 60 is provided at the center in the width direction of the piezoelectric element 300, and the second reinforcing portion 67 extends in the longitudinal direction of the pressure generating chamber. By being provided, the driving durability in the longitudinal direction of the piezoelectric element can be improved. In other words, there is no possibility that the diaphragm including the first electrode 60 is broken even if the driving of the piezoelectric element 300 is repeated.

  Further, the second reinforcing portion 67 gradually decreases in thickness toward the outer side in the width direction of the piezoelectric element 300, thereby dispersing the stress at the end of the second reinforcing portion 67, and thereby the first electrode 60. It is possible to suppress stress concentration on the surface. Thereby, destruction of the diaphragm including the first electrode 60 is suppressed, and driving durability can be improved. Further, since the contact area with the first electrode 60 can be secured even if the contact area with the piezoelectric layer 70 is small, the driving durability of the piezoelectric element is improved without degrading the displacement characteristics of the piezoelectric element 300. Can be made.

  In addition, at least the side surface of the piezoelectric layer 70 of the piezoelectric element 300 is covered with a coating film 200 made of an insulating material having moisture resistance. In the present embodiment, the coating film 200 covers the side surface of the piezoelectric layer 70 and the peripheral surfaces of the side surface and the upper surface of the second electrode 80, and the coating film 200 extends to the upper surface of the arm portion 66. That is, the main portion, which is a substantially central region on the upper surface of the second electrode 80, is not provided with the coating film 200, and is provided with the opening 201 that opens the main portion of the upper surface of the second electrode 80.

  The opening 201 penetrates the coating film 200 in the thickness direction and opens in a rectangular shape along the longitudinal direction of the piezoelectric element 300. For example, the opening 201 covers the entire surface of the flow path forming substrate 10. After the film 200 is formed, it can be formed by selective patterning.

By covering the piezoelectric element 300 with the coating film 200 in this way, it is possible to suppress the destruction of the piezoelectric element 300 due to moisture in the atmosphere. Here, the material of the coating film 200 may be any material having moisture resistance. For example, silicon oxide (SiO _x ), tantalum oxide (TaO _x ), aluminum oxide (AlO _x ), etc. It is preferable to use an inorganic insulating material, and in particular, it is preferable to use an inorganic amorphous material such as aluminum oxide (AlO _x ), for example, alumina (Al ₂ O ₃ ). When aluminum oxide is used as the material of the coating film 200, moisture permeation in a high humidity environment can be sufficiently prevented even if the film thickness of the coating film 200 is relatively thin, about 100 nm. In the present embodiment, alumina (Al ₂ O ₃ ) is used as the coating film 200.

  Further, by providing the opening 201 in the coating film 200, it is possible to satisfactorily maintain the ink ejection characteristics without hindering the displacement of the piezoelectric element 300 (piezoelectric active portion).

  On the coating film 200, for example, a lead electrode 90 made of gold (Au) or the like is provided. One end of the lead electrode 90 is connected to the second electrode 80 through a communication hole 202 provided in the coating film 200, and the other end extends to the ink supply path 14 side of the flow path forming substrate 10. The extended tip is connected to a drive circuit 120 for driving a piezoelectric element 300 described later via a connection wiring 121.

  On the flow path forming substrate 10 on which such a piezoelectric element 300 is formed, a protective substrate 30 having a reservoir portion 31 constituting at least a part of the reservoir 100 is bonded via an adhesive 35. In the present embodiment, the reservoir portion 31 is formed across the protective substrate 30 in the thickness direction and across the width direction of the pressure generating chamber 12, and as described above, the communication portion 13 of the flow path forming substrate 10 is formed. The reservoir 100 is configured as a common ink chamber for the pressure generating chambers 12.

  A piezoelectric element holding portion 32 having a space that does not hinder the movement of the piezoelectric element 300 is provided in a region of the protective substrate 30 that faces the piezoelectric element 300. The piezoelectric element holding part 32 only needs to have a space that does not hinder the movement of the piezoelectric element 300, and the space may be sealed or unsealed.

  As such a protective substrate 30, it is preferable to use substantially the same material as the coefficient of thermal expansion of the flow path forming substrate 10, for example, glass, ceramic material, etc. In this embodiment, the same material as the flow path forming substrate 10 is used. The silicon single crystal substrate was used.

  The protective substrate 30 is provided with a through hole 33 that penetrates the protective substrate 30 in the thickness direction. The vicinity of the end portion of the lead electrode 90 drawn from each piezoelectric element 300 is provided so as to be exposed in the through hole 33.

  A drive circuit 120 for driving the piezoelectric elements 300 arranged in parallel is fixed on the protective substrate 30. For example, a circuit board or a semiconductor integrated circuit (IC) can be used as the drive circuit 120. The drive circuit 120 and the lead electrode 90 are electrically connected via a connection wiring 121 made of a conductive wire such as a bonding wire.

  In addition, a compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the protective substrate 30. Here, the sealing film 41 is made of a material having low rigidity and flexibility, and one surface of the reservoir portion 31 is sealed by the sealing film 41. The fixing plate 42 is formed of a relatively hard material. Since the region of the fixing plate 42 facing the reservoir 100 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir 100 is sealed only with a flexible sealing film 41. Has been.

  In such an ink jet recording head of this embodiment, ink is taken in from an ink introduction port connected to an external ink supply unit (not shown), and the interior from the reservoir 100 to the nozzle opening 21 is filled with ink, and then the drive circuit 120 is filled. In accordance with the recording signal from the first electrode 60 and the second electrode 80 corresponding to the pressure generating chamber 12, the elastic film 50, the insulator film 55, the first electrode 60, and the piezoelectric layer. By bending and deforming 70, the pressure in each pressure generating chamber 12 is increased, and ink droplets are ejected from the nozzle openings 21.

  Here, a manufacturing method of the ink jet recording head will be described with reference to FIGS. 5 to 7 are cross-sectional views showing a method for manufacturing the ink jet recording head.

First, as shown in FIG. 5A, silicon dioxide (SiO ₂₎ constituting an elastic film 50 on the surface of a flow path forming substrate wafer 110, which is a silicon wafer in which a plurality of flow path forming substrates 10 are integrally formed. ) Is formed. Next, as shown in FIG. 5B, an insulator film 55 made of, for example, zirconium oxide is formed on the elastic film 50 (silicon dioxide film 51).

  Next, as shown in FIG. 5C, a first electrode 60 made of platinum is formed on the insulator film 55. Although the formation method of the 1st electrode 60 is not specifically limited, For example, sputtering method, chemical vapor deposition method (CVD method), physical vapor deposition method (PVD method) etc. are mentioned. The material of the first electrode 60 is not particularly limited, and platinum, iridium, metals other than these materials, or metal oxides can be used. When lead zirconate titanate (PZT) is used as the piezoelectric layer 70 as in the present embodiment, it is desirable that the material has little change in conductivity due to diffusion of lead oxide. As platinum, iridium or the like is preferably used.

  Next, as illustrated in FIG. 5D, a diamond-like carbon (DLC) film 68 that forms the reinforcing portion 65, the arm portion 66, and the second reinforcing portion 67 is formed on the first electrode 60. The method for forming the diamond-like carbon film 68 is not particularly limited, and examples thereof include chemical vapor deposition (CVD) such as vacuum vapor deposition, sputtering, and ion plating, and physical vapor deposition (PVD). Note that the thickness of the diamond-like carbon film 68 is 50 nm in the present embodiment.

  Then, as shown in FIG. 6A, the diamond-like carbon film 68 is patterned to form the reinforcing portion 65, the arm portion 66, and the second reinforcing portion 67. Specifically, the region facing the piezoelectric element is removed leaving the central portion in the width direction of the piezoelectric element (not shown). At this time, the pressure generating chamber (not shown) side of the reinforcing portion 65 and the end surface of the second reinforcing portion 67 are inclined. The diamond-like carbon film 68 is patterned by dry etching such as ion milling through a resist formed in a predetermined shape on the diamond-like carbon film 68 by a photolithography method.

  Next, as shown in FIG. 6B, for example, a piezoelectric layer 70 made of lead zirconate titanate (PZT) or the like and a second electrode 80 made of iridium, for example, are used. On the entire surface.

  The material of the piezoelectric layer 70 constituting the piezoelectric element 300 is, for example, a ferroelectric piezoelectric material such as lead zirconate titanate (PZT), or niobium, nickel, magnesium, bismuth, yttrium, or the like. A relaxor ferroelectric or the like to which a metal is added is used. The composition may be appropriately selected in consideration of the characteristics, usage, etc. of the piezoelectric element 300. The method for forming the piezoelectric layer 70 is not particularly limited. For example, in this embodiment, a so-called sol in which a metal organic material is dissolved and dispersed in a solvent is applied, dried, gelled, and further fired at a high temperature. The piezoelectric layer 70 was formed by using a so-called sol-gel method for obtaining a piezoelectric layer 70 made of an oxide. The method for forming the piezoelectric layer 70 is not limited to the sol-gel method. For example, the piezoelectric layer 70 may be formed using a thin film forming method such as a MOD method or a sputtering method. Actually, the piezoelectric layer 70 is formed by repeating the above-described process of forming a thin piezoelectric film by the sol-gel method a plurality of times, and a piezoelectric layer having a thickness of 1300 nm made up of a plurality of piezoelectric films. 70 is formed.

  Next, as shown in FIG. 6C, the piezoelectric layer 300 is formed by patterning the piezoelectric layer 70 and the second electrode 80 in regions facing the pressure generating chambers 12. Patterning of the piezoelectric layer 70 and the second electrode 80 can be performed collectively by dry etching through a resist formed in a predetermined shape on the second electrode 80 by photolithography. The etching is substantially stopped by etching the piezoelectric layer 70 until the reinforcing film is exposed. In the present embodiment, the reinforcing film is also provided in a region corresponding to the partition that partitions the pressure generating chambers in the juxtaposed direction, that is, the first electrode 60 is provided so as to cover the first electrode 60. 60 is not over-etched, and variations in the film thickness of the first electrode 60 can be suppressed.

  Next, after removing the resist, as shown in FIG. 6D, after forming the coating film 200 over the entire surface of the flow path forming substrate wafer 110, the coating film 200 is patterned into a predetermined shape. Thus, the opening 201 is formed. At this time, the communication hole 202 shown in FIG. 2 is formed at the same time.

  Next, the lead electrode 90 is formed. Specifically, as shown in FIG. 7A, a metal film made of, for example, gold (Au) or the like is formed over the entire surface of the flow path forming substrate wafer 110, and then shown in FIG. 7B. Thus, for example, the lead electrode 90 is formed by patterning the metal film for each piezoelectric element 300 through a mask pattern (not shown) made of a resist or the like.

  Although not shown, a protective substrate wafer that is a silicon wafer and serves as a plurality of protective substrates 30 is bonded to the piezoelectric element 300 side of the flow path forming substrate wafer 110 by an adhesive 35. The protective substrate 30 is preliminarily formed with a reservoir portion 31, a piezoelectric element holding portion 32, and the like. Further, the protective substrate 30 is made of, for example, a silicon single crystal substrate having a thickness of about 400 μm, and the rigidity of the flow path forming substrate 10 is remarkably improved by bonding the protective substrate 30. Thereafter, the flow path forming substrate wafer 110 is set to a predetermined thickness.

  Next, a mask film is newly formed on the flow path forming substrate wafer 110 and patterned into a predetermined shape. Then, by performing anisotropic etching (wet etching) using an alkaline solution such as KOH on the flow path forming substrate wafer 110 through the mask film, the pressure generating chamber 12 corresponding to the piezoelectric element 300, the communication portion 13, An ink supply path 14 and a communication path 15 are formed.

  Thereafter, the mask film on the surface side where the pressure generation chamber 12 of the flow path forming substrate wafer 110 is opened is removed, and unnecessary portions of the outer peripheral edge portions of the flow path forming substrate wafer 110 and the protective substrate wafer are, for example, It is removed by cutting by dicing or the like. Then, the nozzle plate 20 having the nozzle openings 21 formed on the surface of the flow path forming substrate wafer 110 opposite to the protective substrate wafer is bonded, and the compliance substrate 40 is bonded to the protective substrate wafer. The ink jet recording head having the above-described structure is manufactured by dividing the flow path forming substrate wafer 110 and the like into a single chip size flow path forming substrate 10 as shown in FIG.

  Further, these ink jet recording heads 1 constitute a part of a recording head unit having an ink flow path communicating with an ink cartridge or the like, and are mounted on an ink jet recording apparatus. FIG. 8 is a perspective view showing a schematic configuration of the ink jet recording apparatus.

  As shown in FIG. 8, the ink jet recording apparatus I which is the liquid ejecting apparatus of the present embodiment has a plurality of different colors such as black (B), cyan (C), magenta (M), yellow (Y), and the like. An ink jet recording head 1 (hereinafter referred to as a recording head) to which an ink cartridge (liquid storing means) 2 having a storage chamber for storing the ink is mounted. The recording head 1 is mounted on a carriage 3, and the carriage 3 on which the recording head 1 is mounted is provided on a carriage shaft 5 attached to the apparatus body 4 so as to be movable in the axial direction. Then, the driving force of the driving motor 6 is transmitted to the carriage 3 through a plurality of gears and a timing belt 7 (not shown), so that the carriage 3 is moved along the carriage shaft 5. On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, so that a recording medium S such as paper fed by a paper feeding device (not shown) is conveyed on the platen 8. ing.

(Embodiment 2)
FIG. 9 is a cross-sectional view of main parts of the piezoelectric element and the pressure generation chamber of the recording head according to the second embodiment. Since the present embodiment is the same as the first embodiment except for the shape of the reinforcing membrane, the same reference numerals are given to the portions showing the same action, and redundant description is omitted.

  As shown in FIG. 9, the region on the first electrode 60 corresponding to both end portions of the piezoelectric layer 70 in the width direction of the piezoelectric element 300 is made of a material harder than the film forming the first electrode 60. A reinforcing portion 65A is provided. An arm portion 66A extends continuously from the reinforcing portion 65A to the outer side in the width direction of the piezoelectric element 300. In this way, the reinforcing portion 65A and the arm portion 66A are integrated to constitute a reinforcing film. Further, the thickness of the reinforcing portion 65A gradually decreases toward the inner side in the width direction of the piezoelectric element 300. The arm portion 66A is thinner than the reinforcing portion 65A.

  Further, a second reinforcing portion 67 made of a material harder than the film forming the first electrode 60 is provided in the longitudinal direction of the pressure generating chamber 12 on the first electrode 60 and in the central portion in the width direction of the piezoelectric element 300. It is provided over.

  Thus, by making the arm portion 66A of the reinforcing film thinner, the restraining force of the diaphragm can be reduced than in the first embodiment, and the displacement amount of the diaphragm can be improved as compared with the first embodiment. it can.

  By providing the reinforcing portion 65A, the rigidity of the first electrode 60 with respect to the stress concentration at the end in the width direction of the piezoelectric element 300 can be increased, driving durability can be improved, and displacement characteristics can be improved. it can. In addition, the stress concentration at the first electrode 60 can be suppressed by dispersing the stress at the end in the width direction of the piezoelectric element 300. Further, by providing the second reinforcing portion 67, the driving durability in the longitudinal direction of the piezoelectric element 300 can be improved. Further, the arm portion 66A of the reinforcing film functions as an etching stop layer, and the first electrode 60 is not etched. Therefore, variations in the film thickness of the first electrode 60 can be suppressed.

  The method of manufacturing the reinforcing film according to the present embodiment is not particularly limited. For example, when patterning the piezoelectric layer 70 and the second electrode 80, etching is performed until the thickness of the reinforcing film is reduced to half. 66A can be formed.

(Embodiment 3)
FIG. 10 is a cross-sectional view of main parts of the piezoelectric element and the pressure generation chamber of the recording head according to the third embodiment. Since the present embodiment is the same as the first embodiment except for the shape of the reinforcing membrane, the same reference numerals are given to the portions showing the same action, and redundant description is omitted.

  As shown in FIG. 10, the region on the first electrode 60 corresponding to both end portions of the piezoelectric layer 70 in the width direction of the piezoelectric element 300 is made of a material harder than the film forming the first electrode 60. The reinforcement part 65B which becomes is provided. In the present embodiment, the reinforcing portion 65B is provided in a region corresponding to both ends of the piezoelectric layer 70 in the width direction of the piezoelectric element 300, and no arm portion is provided. The reinforcing portion 65 </ b> B is provided between the first electrode 60 and the piezoelectric layer 70, and the thickness gradually decreases toward the inner side in the width direction of the piezoelectric element 300. In addition, the thickness of the reinforcing portion 65 </ b> B gradually decreases toward the outer side in the width direction of the piezoelectric element 300. By setting it as such a structure, the restraining force of a diaphragm can further be reduced rather than Embodiment 2, and the amount of displacement can be improved. That is, the displacement characteristics can be further improved.

  Further, a second reinforcing portion 67 made of a material harder than the film forming the first electrode 60 is provided in the longitudinal direction of the pressure generating chamber 12 on the first electrode 60 and in the central portion in the width direction of the piezoelectric element 300. It is provided over.

  By providing the reinforcing portion 65B, the rigidity of the first electrode 60 with respect to the stress concentration at the end in the width direction of the piezoelectric element 300 is increased, and the driving durability of the piezoelectric element 300 can be improved. In addition, the stress concentration at the first electrode 60 can be suppressed by dispersing the stress at the end in the width direction of the piezoelectric element 300. Further, by providing the second reinforcing portion 67, the driving durability in the longitudinal direction of the piezoelectric element 300 can be improved.

  The manufacturing method of the reinforcing portion 65B of the present embodiment is not particularly limited. For example, when the piezoelectric layer 70 and the second electrode 80 are patterned, the diamond-like carbon film constituting the reinforcing portion 65B is also patterned, One electrode 60 may be exposed.

(Embodiment 4)
FIG. 11 is a cross-sectional view of main parts of the piezoelectric element and the pressure generation chamber of the recording head according to the fourth embodiment. Since the present embodiment is the same as the first embodiment except for the shape of the reinforcing membrane, the same reference numerals are given to the portions showing the same action, and redundant description is omitted.

  As shown in FIG. 11, the region on the first electrode 60 corresponding to both end portions of the piezoelectric layer 70 in the width direction of the piezoelectric element 300 is made of a material harder than the film forming the first electrode 60. A reinforcing portion 65C is provided. And the arm part 66C is continuously extended from the reinforcement part 65C on the width direction outer side of the piezoelectric element 300. In this way, the reinforcing portion 65C and the arm portion 66C are integrated to form a reinforcing film. That is, the reinforcing film is composed of a reinforcing portion 65C provided between the first electrode 60 and the piezoelectric layer 70, and an arm portion 66C that extends continuously outward from the piezoelectric element 300 in the width direction. Become. Further, the thickness of the reinforcing portion 65C gradually decreases toward the inner side in the width direction of the piezoelectric element 300. The reinforcing film is provided with a recess at a boundary portion between the reinforcing portion 65C and the arm portion 66C. The recess has a curved inner surface.

  Further, a second reinforcing portion 67 made of a material harder than the film forming the first electrode 60 is provided in the longitudinal direction of the pressure generating chamber 12 on the first electrode 60 and in the central portion in the width direction of the piezoelectric element 300. It is provided over.

  As described above, the concave portion is provided at the boundary portion with the region corresponding to the piezoelectric layer 70, and the inner surface of the concave portion has a curved surface, so that the diaphragm at the end portion in the width direction of the piezoelectric element 300 is provided. Can be more effectively dispersed. Thereby, destruction of the diaphragm including the first electrode 60 is further suppressed, and the driving durability of the piezoelectric element 300 can be further improved.

  Furthermore, in this embodiment, since the inner surface of the concave portion is formed in a curved surface shape, the covering of the coating film 200 on the reinforcing film is improved, and the piezoelectric element 300 is reliably protected by the coating film 200, so It is possible to reliably prevent the element 300 from being destroyed.

  By providing the reinforcing portion 65C, the rigidity of the first electrode 60 with respect to the stress concentration at the end portion in the width direction of the piezoelectric element 300 is increased, and driving durability can be improved. Further, by providing the second reinforcing portion 67, the driving durability in the longitudinal direction of the piezoelectric element 300 can be improved. Further, the arm portion 66C of the reinforcing film functions as an etching stop layer, and the first electrode 60 is not etched. Therefore, variations in the film thickness of the first electrode 60 can be suppressed.

  Furthermore, in the present embodiment, the inner surface of the concave portion is provided in a curved shape, and moreover, stress at the end in the width direction of the piezoelectric element 300 is further effectively distributed, and stress concentration on the first electrode 60 is further increased. Can be suppressed. Thereby, driving durability can be further improved.

  The method for manufacturing the reinforcing film of the present embodiment is not particularly limited. For example, when patterning the piezoelectric layer 70 and the second electrode 80, dry etching is performed until the reinforcing film reaches the reinforcing film at the same time, thereby reinforcing the reinforcing part 65C of the reinforcing film. A recess is formed at the boundary between the arm portion 66C and the arm portion 66C. Such a recess can be positively formed by appropriately changing the voltage, temperature, etc. during dry etching.

(Other embodiments)
As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment. For example, in the above-described embodiment, a silicon single crystal substrate is exemplified as the flow path forming substrate 10, but the present invention is not limited to this, and the present invention is also effective for an SOI substrate, a glass substrate, an MgO substrate, and the like. Further, the elastic film 50 made of silicon dioxide is provided in the lowermost layer of the diaphragm, but the structure of the diaphragm is not particularly limited to this.
In the embodiment described above, the coating film 200 is provided, but it may not be provided.
In the first to fourth embodiments, the second reinforcing portion 67 is provided, but none of them may be provided.

  In the ink jet recording apparatus I described above, the ink jet recording head 1 is mounted on the carriage 3 and moves in the main scanning direction. However, the present invention is not particularly limited thereto. The present invention can also be applied to a so-called line type recording apparatus in which printing is performed simply by moving a recording sheet S such as paper in the sub-scanning direction.

  In the above-described embodiment, the ink jet recording head has been described as an example of the liquid ejecting head. However, the present invention is widely applied to all liquid ejecting heads, and the liquid ejecting ejects liquids other than ink. Of course, it can also be applied to the head. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (field emission displays). Examples thereof include an electrode material ejection head used for electrode formation, a bioorganic matter ejection head used for biochip production, and the like.

  The present invention is not limited to a piezoelectric element mounted on a liquid jet head typified by an ink jet recording head, and can also be applied to a piezoelectric element mounted on another apparatus.

DESCRIPTION OF SYMBOLS 1 Inkjet recording head (liquid ejecting head), 10 Flow path formation board | substrate, 12 Pressure generation chamber, 13 Communication part, 14 Ink supply path, 15 Communication path, 20 Nozzle plate, 21 Nozzle opening, 30 Protection board, 31 Reservoir part , 32 piezoelectric element holding part, 40 compliance substrate, 60 first electrode, 65 reinforcing part, 66 arm part, 67 second reinforcing part, 70 piezoelectric layer, 80 second electrode, 90 lead electrode, 100 reservoir, 120 driving Circuit, 121 connection wiring, 300 piezoelectric element

Claims (10)

A flow path forming substrate in which pressure generation chambers communicating with nozzle openings for ejecting liquid are arranged in parallel ;
Comprising a second electrode provided on the channel forming a first electrode provided on the substrate, a piezoelectric layer provided on the first electrode and the piezoelectric layer, corresponding to the pressure generating chambers A piezoelectric element;
With
The piezoelectric element has a width along the arrangement direction of the pressure generating chamber, a on the first electrode, in a region corresponding to both end portions of the piezoelectric layer in the width direction of the piezoelectric element, wherein Having a reinforcing part made of a material harder than the film forming the first electrode ;
The liquid ejecting head according to claim 1, wherein the reinforcing portion gradually decreases in thickness toward an inner side in the width direction of the piezoelectric element.   The liquid ejecting head according to claim 1, wherein the reinforcing portion is made of a material having a Vickers hardness Hv of 1000 or more.   3. The liquid ejecting head according to claim 1, further comprising an arm portion extending continuously outward from the reinforcing portion in the width direction of the piezoelectric element.   The liquid ejecting head according to claim 3, wherein the arm portion is thinner than the reinforcing portion.   The liquid ejecting head according to claim 3, wherein a concave portion is provided at a boundary portion between the reinforcing portion and the arm portion, and an inner surface of the concave portion is curved.   A second reinforcing portion made of a material harder than the film forming the first electrode is provided in the longitudinal direction of the pressure generating chamber on the first electrode and in the center in the width direction of the piezoelectric element. The liquid ejecting head according to claim 1, wherein the liquid ejecting head is provided. The liquid ejecting head according to claim 6, wherein the thickness of the second reinforcing portion gradually decreases toward the outer side in the width direction of the piezoelectric element.   The liquid ejecting head according to claim 1, wherein a coating film made of an insulator that covers at least a side surface of the piezoelectric layer is provided.   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1. A piezoelectric element comprising: a first electrode provided on a substrate; a piezoelectric layer provided on the first electrode; and a second electrode provided on the piezoelectric layer;
On the first electrode, a region corresponding to both end portions of the piezoelectric layer in the width direction of the piezoelectric element is provided with a reinforcing portion made of a material harder than the film forming the first electrode,
The said reinforcement part is an actuator apparatus characterized by the thickness decreasing gradually toward the width direction inner side of the said piezoelectric element.

Images