JP2006123518A - Piezoelectric actuator, liquid ejection device, and manufacturing method of piezoelectric actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejection device which can reliably prevent breakage of a piezoelectric element over a long period of time. <P>SOLUTION: A first lead electrode 90 led from the piezoelectric element 300 and a second lead electrode 91 led from the first lead electrode 90 are provided. An insulating film 100 composed of an inorganic insulating material is continuously provided in the layers constituting the piezo electric device 300 and the pattern regions of the first lead electrode 90 and the second lead electrode 91. At least the piezo electric element 300 and the first lead electrode 90 are covered by the insulating film 100 except for a terminal portion 90a provided at the distal end of the first lead electrode 90. The second lead electrode 91 is provided to be extended on the insulating film 100 so as to be connected to the first lead electrode 90 at the terminal portion 90a. The connecting portion 91a to which connection wiring 130 is connected is provided in the distal end side of the second lead electrode 91. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a piezoelectric actuator, a liquid ejecting apparatus, and a method for manufacturing a piezoelectric actuator, and in particular, a part of a pressure generating chamber communicating with a nozzle opening for ejecting ink droplets is constituted by a diaphragm, and a piezoelectric element is provided on the surface of the diaphragm. The present invention is useful when applied to a liquid ejecting apparatus including an ink jet recording head that is disposed and ejects ink droplets by displacement of a piezoelectric element.

  A part of the pressure generation chamber communicating with the nozzle opening for discharging ink droplets is constituted by a vibration plate, and the vibration plate is deformed by a piezoelectric element to pressurize the ink in the pressure generation chamber to discharge ink droplets from the nozzle opening. Two types of ink jet recording heads have been put into practical use: those using a longitudinal vibration mode piezoelectric actuator that extends and contracts in the axial direction of the piezoelectric element, and those using a flexural vibration mode piezoelectric actuator.

  The former can change the volume of the pressure generation chamber by bringing the end face of the piezoelectric element into contact with the diaphragm, and it is possible to manufacture a head suitable for high-density printing, while the piezoelectric element is arranged in an array of nozzle openings. There is a problem that the manufacturing process is complicated because a difficult process of matching the pitch into a comb-like shape and an operation of positioning and fixing the cut piezoelectric element in the pressure generating chamber are necessary.

  On the other hand, the latter can flexibly vibrate, although a piezoelectric element can be built on the diaphragm by a relatively simple process of sticking a green sheet of piezoelectric material according to the shape of the pressure generation chamber and firing it. There is a problem that a certain amount of area is required for the use of, and high-density arrangement is difficult.

  On the other hand, in order to eliminate the disadvantages of the latter recording head, 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 shaped to correspond to the pressure generating chamber by lithography. In some cases, the piezoelectric element is formed so as to be independent for each pressure generating chamber. Further, such a piezoelectric element has a problem that it is easily destroyed due to an external environment such as moisture. In order to solve this problem, a sealing substrate (reservoir forming substrate) having a piezoelectric element holding portion is bonded to a flow path forming substrate in which a pressure generating chamber is formed, and the piezoelectric element is sealed in the piezoelectric element holding portion. There is something like that (see, for example, Patent Document 1).

  However, even if the piezoelectric element is sealed in this way, moisture in the piezoelectric element holding portion gradually increases due to, for example, moisture entering the piezoelectric element holding portion from the bonded portion between the sealing substrate and the flow path forming substrate. However, there is a problem that the piezoelectric element is eventually destroyed by the moisture. Such a problem exists not only in an ink jet recording head that ejects ink droplets, but also in other liquid ejecting heads that eject droplets other than ink.

JP 2003-136734 A (FIGS. 1, 2 and 5)

  In view of such circumstances, it is an object of the present invention to provide a piezoelectric actuator, a liquid ejecting apparatus, and a method for manufacturing the piezoelectric actuator that can reliably prevent destruction of the piezoelectric element over a long period of time.

The first aspect of the present invention for solving the above problems is as follows.
A piezoelectric element having a piezoelectric layer and an electrode for applying a voltage to the piezoelectric layer and integrated with the diaphragm via one electrode, an insulating film covering at least the outside of the piezoelectric element, and the insulating film A lead electrode connected to the other electrode of the piezoelectric element through a contact hole provided in the contact hole, and the insulating film remaining in the contact hole is sufficiently interposed between the one electrode and the other electrode. A piezoelectric actuator characterized in that electrical conduction between the other electrode and the lead electrode is ensured by applying and destroying an appropriate voltage.
According to the first aspect, since the piezoelectric layer is covered with the insulating film having a low moisture permeability, it is possible to prevent moisture from coming into contact with the piezoelectric layer. As a result, it is possible to reliably prevent deterioration of the piezoelectric layer due to moisture over a long period of time.
In addition, since the insulating film remaining in the contact hole is broken by applying voltage, the electric conduction to the piezoelectric element is not hindered by the insulating film. As a result, good electrical conduction through the lead electrode can be ensured.

The second aspect of the present invention is:
In the piezoelectric actuator described in the first aspect,
The lead electrode has one end directly in contact with the other electrode and the entire outside is covered with the insulating film, and one end is interposed through a contact hole provided in the insulating film. And a second lead electrode in contact with the other end of the first lead electrode.
According to the second aspect, since the piezoelectric element is also covered with the lead electrode, a more reliable moisture-proof structure of the piezoelectric element can be obtained.

The third aspect of the present invention is:
In the piezoelectric actuator described in the first aspect,
The lead electrode has a first lead electrode whose one end is in direct contact with the other electrode, and a second lead electrode whose one end is in contact with the other end of the first lead electrode. ,
The insulating film is in contact with the outer peripheral surface of the piezoelectric element to cover the piezoelectric element and includes a first contact hole that secures contact between one end of the first lead electrode and the other electrode of the piezoelectric element. The insulating film, the first insulating film coated on the piezoelectric element, and the outer peripheral surface of the first lead electrode so as to cover the piezoelectric element, and the other end of the first lead electrode and the second electrode A piezoelectric actuator comprising a second insulating film having a contact hole for ensuring contact with a lead electrode.
According to the third aspect, since the piezoelectric element is covered with the two-layer insulating film and the first lead electrode, a more reliable moisture-proof structure of the piezoelectric element can be obtained.

The fourth aspect of the present invention is:
In the piezoelectric actuator according to any one of the first to third aspects,
The insulating film is a piezoelectric actuator that is broken by applying a DC voltage between the one electrode and the other electrode and then breaking by applying an AC voltage.
According to the fourth aspect, the insulating film remaining as a residue when a DC voltage is applied can be completely removed.

According to a fifth aspect of the present invention,
In the piezoelectric actuator according to any one of the first to fourth aspects,
The piezoelectric actuator is characterized in that the insulating film is made of an amorphous material.
According to the fifth aspect, since the insulating film having an extremely low moisture permeability can be formed, it is possible to reliably prevent adverse effects on the piezoelectric element caused by moisture.

The sixth aspect of the present invention is:
In the piezoelectric actuator described in the fifth aspect,
The piezoelectric actuator is characterized in that the amorphous material is aluminum oxide.
According to the sixth aspect, since the insulating film having an extremely low moisture permeability can be formed, it is possible to reliably prevent the piezoelectric element from being damaged due to moisture.

The seventh aspect of the present invention is
A liquid comprising a liquid ejecting head that uses the piezoelectric actuator according to any one of the first to sixth aspects as a drive source for discharging the liquid in the pressure generation chamber from the nozzle opening. It is an injection device.
According to the seventh aspect, since the liquid ejecting head capable of performing stable liquid ejection is provided, a highly reliable liquid ejecting apparatus can be provided.

The eighth aspect of the present invention is
Covering the outside of the piezoelectric element integrated with the diaphragm via one electrode with an insulating film;
Forming a contact hole for ensuring electrical continuity with the other electrode of the piezoelectric element in the insulating film, leaving the insulating film thin;
Forming a lead electrode connected to the other electrode;
And a step of applying a sufficient voltage between the one electrode and the other electrode to destroy and remove the insulating film remaining in the contact hole.
According to the eighth aspect, since the piezoelectric layer is covered with the insulating film having a low moisture permeability, it is possible to prevent moisture from coming into contact with the piezoelectric layer. As a result, it is possible to reliably prevent deterioration of the piezoelectric layer due to moisture over a long period of time.
Further, since the contact hole is first formed with the insulating film remaining thin, the surface of the underlying electrode or the like is not damaged. Furthermore, since the remaining insulating film is destroyed by applying voltage, the electric conduction to the piezoelectric element is not hindered by the insulating film. As a result, it is possible to ensure good electrical conduction through the electrodes without causing damage to the substrate due to the removal of the insulating film.

The ninth aspect of the present invention provides
In the method of manufacturing a piezoelectric actuator described in the eighth aspect,
The contact hole of the insulating film is formed by removing the insulating film by an ion milling method.
According to the ninth aspect, good electrical conduction through the lead electrode can be ensured. Further, the film thickness of the insulating film to be left can be easily adjusted by controlling the milling rate at this time.

The tenth aspect of the present invention provides
In the method of manufacturing a piezoelectric actuator described in the eighth aspect,
The method for producing a piezoelectric actuator characterized in that the insulating film is broken by applying a DC voltage between the one electrode and the other electrode, and further breaking by applying an AC voltage. is there.
According to the tenth aspect, the insulating film remaining as a residue when a DC voltage is applied can be completely removed.

Hereinafter, the present invention will be described in detail based on embodiments.
<Embodiment 1>
FIG. 1 is an exploded perspective view showing an ink jet recording head according to Embodiment 1 of the present invention, and FIG. 2 is a plan view and a cross-sectional view of FIG.

  In this embodiment, as clearly shown in FIG. 2B, the first lead electrode 90 whose one end is in direct contact with the upper electrode film 80 and is entirely covered with the insulating film 100, and the insulating film One end portion of the film 100 has a second lead electrode 91 in contact with the other end portion of the first lead electrode 90 through a contact hole 100a.

  More specifically, as shown in FIGS. 1 and 2, the flow path forming substrate 10 is composed of a silicon single crystal substrate having a plane orientation (110) in this embodiment, and one surface thereof is previously formed by thermal oxidation. An elastic film 50 made of silicon dioxide and having a thickness of 1 to 2 μm is formed. 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. The communication unit 13 constitutes a part of a reservoir 110 that communicates with a reservoir unit 32 of a protective substrate 30 described later and serves as a common ink chamber for the pressure generation chambers 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.

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 portion of each pressure generating chamber 12 on the side opposite to the ink supply path 14 is provided with an adhesive or It is fixed via a heat welding film or the like. The nozzle plate 20 has a thickness of, for example, 0.01 to 1 mm, a linear expansion coefficient of 300 ° C. or less, for example, 2.5 to 4.5 [× 10 ⁻⁶ / ° C.], glass ceramics, silicon It consists of a single crystal substrate or non-rust steel.

  On the other hand, as described above, the elastic film 50 having a thickness of, for example, about 1.0 μm is formed on the side opposite to the opening surface of the flow path forming substrate 10. For example, an insulator film 55 having a thickness of about 0.4 μm is formed. Further, on the insulator film 55, a lower electrode film 60 having a thickness of, for example, about 0.2 μm, a piezoelectric layer 70 having a thickness of, for example, about 1.0 μm, and a thickness of, for example, about 0 The upper electrode film 80 having a thickness of 0.05 μm is laminated by a process described later to constitute the piezoelectric element 300. Here, the piezoelectric element 300 refers to a portion including the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 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 this case, 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 320. In this embodiment, the lower electrode film 60 is a common electrode of the piezoelectric element 300, and the upper electrode film 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. In either case, a piezoelectric active part is formed for each pressure generating chamber. Further, here, the piezoelectric element 300 and the vibration plate that is displaced by driving the piezoelectric element 300 are collectively referred to as a piezoelectric actuator.

  For example, in the present embodiment, as shown in FIG. 3, the lower electrode film 60 is formed in a region facing the pressure generation chamber 12 in the longitudinal direction of the pressure generation chamber 12, and corresponds to the plurality of pressure generation chambers 12. It is provided continuously in the area. Further, the lower electrode film 60 extends to the vicinity of the end of the flow path forming substrate 10 outside the row of the pressure generating chambers 12, and a connection wiring 130 extended from a driving IC 120 described later is provided at the tip of the lower electrode film 60. The connecting portion 60a is connected. The piezoelectric layer 70 and the upper electrode film 80 are basically provided in a region facing the pressure generation chamber 12, but in the longitudinal direction of the pressure generation chamber 12, the piezoelectric layer 70 and the upper electrode film 80 are outside the end portion of the lower electrode film 60. The end surface of the lower electrode film 60 is covered with the piezoelectric layer 70. In the vicinity of the end in the longitudinal direction of the pressure generating chamber 12, a piezoelectric inactive portion 330 having the piezoelectric layer 70 but not substantially driven is formed. Further, one end portion of the first lead electrode 90 is connected in the vicinity of one end portion of the upper electrode film 80 constituting each piezoelectric element 300. In the present embodiment, these first lead electrodes 90 are extended from the piezoelectric inactive portion 330 outside the pressure generating chamber 12 onto the insulator film 55.

  In addition, the second lead electrode 91 is connected to the first lead electrode 90 via an insulating film 100 made of an inorganic insulating material. Here, the electrical continuity between the first lead electrode 90 and the second lead electrode 91 is such that one end of the second lead electrode 91 is connected to the first lead electrode via a contact hole 100a provided in the insulating film 100. It is ensured by contacting the terminal portion 90a which is the other end portion of 90. However, although the contact hole 100a of the insulating film 100 can be preferably formed by, for example, ion milling, the processing is not sufficient and the insulating film 100 may remain thin. Further, even if the contact hole 100a penetrates once, an oxide film may be formed on the surface of the terminal portion 90a of the first lead electrode 90 thereafter. In these cases, in any case, electrical contact failure occurs between the second lead electrode 91 and the first lead electrode 90, and a predetermined electrical conductivity cannot be ensured at the connection portion between the two. .

  On the other hand, if the insulating film 100 is excessively removed during the work associated with the formation of the contact hole 100a, there is a problem that the terminal portion 90a as a base is damaged.

  Therefore, in this embodiment, when forming the contact hole 100a, the insulating film 100 is first left thin. As a result, it is possible to prevent damage to the terminal portion 90a which is the base.

  On the other hand, the insulating film 100 remaining in the contact hole 100a applies a sufficient voltage between the connection portion 60a of the lower electrode film 60 and the connection portion 91a of the second lead electrode 91 after the piezoelectric actuator is completed. To ensure good electrical conductivity between the first lead electrode 90 and the second lead electrode 91. Here, the voltage applied between the connection portion 60a of the lower electrode film 60 and the connection portion 91a of the second lead electrode 91 may be either direct current or alternating current. Furthermore, after applying the direct current voltage, an alternating voltage is applied. You may apply.

  The second lead electrode 91 is extended to the vicinity of the end portion of the flow path forming substrate 10, and the vicinity of the end portion is the connection portion 91 a to which the connection wiring 130 is connected, like the connection portion 60 a of the lower electrode film 60. It has become.

  Here, the insulating film 100 is provided in the pattern area of each layer constituting the piezoelectric element 300, the first lead electrode 90, and the second lead electrode 91. At least the piezoelectric element 300 and the first lead electrode 90 are covered with the insulating film 100 except for the terminal portion 90 a of the first lead electrode 90. For example, in this embodiment, the insulating film 100 is continuously provided up to the lower electrode film 60 outside the row of the piezoelectric elements 300, and the lower electrode film 60 as well as the piezoelectric elements 300 and the first lead electrodes 90 are provided. The insulating film 100 is covered except for the connection portion 60a.

  Further, as described above, the insulating film 100 is continuously provided up to the pattern region of the second lead electrode 91. That is, the insulating film 100 is continuously provided to the vicinity of the end portion of the flow path forming substrate 10, and the connection portion 91 a of the second lead electrode 91 is also located on the insulating film 100.

The material of the insulating film 100 is not particularly limited as long as it is an inorganic insulating material. Examples thereof include silicon oxide (SiO _x ), tantalum oxide (TaO _x ), and aluminum oxide (AlO _x ). It is preferable to use aluminum oxide (AlO _x ) which is an inorganic amorphous material. When aluminum oxide is used as the material of the insulating film 100, moisture permeation in a high humidity environment can be sufficiently prevented even if the insulating film 100 is formed as a thin film of about 100 nm. For example, when an organic insulating material such as a resin is used as the material of the insulating film, moisture permeation cannot be sufficiently prevented when the insulating film is as thin as the insulating film of the inorganic insulating material. In addition, if the thickness of the insulating film is increased in order to prevent moisture permeation, there is a possibility that the movement of the piezoelectric element is hindered. In addition, the inorganic insulating material can surely break the insulating film 100 in the contact hole 100a when a voltage is applied to the piezoelectric element.

  As described above, the insulating film 100 covers the surfaces of the piezoelectric element 300 and the first lead electrode 90, and the connection portion 91 a to the connection wiring 130 is connected to the second lead electrode 91 provided on the insulating film 100. By providing, destruction due to moisture (humidity) of the piezoelectric layer 70 can be surely prevented. That is, the piezoelectric element 300 and the first lead electrode 90 are covered with the insulating film 100 that continues to the pattern region of the second lead electrode 91 except for the terminal portion 90a. Further, the terminal portion 90 a of the first lead electrode 90 is blocked by the second lead electrode 91. Therefore, moisture can penetrate only from the end portion of the insulating film 100, and even if it penetrates, moisture can be substantially prevented from reaching the piezoelectric layer 70, and the moisture of the piezoelectric layer 70 can be prevented. It is possible to more reliably prevent the damage caused by.

  Furthermore, since the insulating film 100 is also provided below the connection portion 91a of the second lead electrode 91 with the connection wiring 130, there is an effect that the adhesion of the second lead electrode 91 is enhanced. Thereby, for example, when the connection wiring 130 is connected to the second lead electrode 91 by wire bonding or the like, it is possible to prevent a defect such as peeling of the second lead electrode 91 from occurring.

  In addition, with the processing of the contact hole 100a, the base terminal portion 90a is not damaged, and at the same time, the second lead electrode 91 and the first lead electrode 90 are electrically connected via the contact hole 100a. Can also be performed well.

  In the present embodiment, the tip of the lower electrode film 60 extended to the vicinity of the communication portion 13 is a connection portion 60a with the connection wiring 130. For example, as shown in FIG. The first lead electrode 90A electrically connected to 60 extends to a region outside the arranged piezoelectric elements 300 in the longitudinal direction of the piezoelectric element 300, and the second lead electrode 91A flows through the second lead electrode 91A. It is good also as extending to the edge part vicinity of the formation board | substrate 10, and making the front-end | tip part into the connection part 91b to which the connection wiring 130 is connected. In this case, except for the terminal portions 90a of the first lead electrodes 90 and 90A, the layers constituting the piezoelectric element 300, the patterns of the first lead electrodes 90 and 90A, and the second lead electrodes 91 and 91A The region is covered with the insulating film 100.

  Further, a protective substrate 30 having a piezoelectric element holding portion 31 capable of securing a space that does not hinder the movement of the region facing the piezoelectric element 300 is bonded to the surface of the flow path forming substrate 10 on the piezoelectric element 300 side. It is joined via the agent 35. Since the piezoelectric element 300 is formed in the piezoelectric element holding part 31, it is protected in a state hardly affected by the external environment. Here, the terminal portion 90 a of the first lead electrode 90 is desirably disposed outside the piezoelectric element holding portion 31. That is, by adhering the protective substrate 30 onto the insulating film 100, the adhesive strength between the protective substrate 30 and the flow path forming substrate 10 can be improved.

  The protective substrate 30 is provided with a reservoir portion 32 in a region corresponding to the communication portion 13 of the flow path forming substrate 10. In this embodiment, the reservoir portion 32 is provided along the direction in which the pressure generating chambers 12 are arranged so as to penetrate the protective substrate 30 in the thickness direction, and as described above, the communication portion of the flow path forming substrate 10. 13, a reservoir 110 serving as a common ink chamber for each pressure generating chamber 12 is configured.

  In addition, examples of the material of the protective substrate 30 include glass, ceramic material, metal, resin, and the like, but it is more preferable that the material is substantially the same as the coefficient of thermal expansion of the flow path forming substrate 10. In this embodiment, the silicon single crystal substrate made of the same material as the flow path forming substrate 10 is used.

  A compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the protective substrate 30. The sealing film 41 is made of a material having low rigidity and flexibility (for example, a polyphenylene sulfide (PPS) film having a thickness of 6 μm). Yes. The fixing plate 42 is made of a hard material such as metal (for example, stainless steel (SUS) having a thickness of 30 μm). Since the region of the fixing plate 42 facing the reservoir 110 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir 110 is sealed only by the flexible sealing film 41. Has been.

  In such an ink jet recording head of this embodiment, ink is taken in from an external ink supply means (not shown), filled with ink from the reservoir 110 to the nozzle opening 21, and then subjected to pressure according to a recording signal from the drive IC 120. By applying a voltage between each of the lower electrode film 60 and the upper electrode film 80 corresponding to the generation chamber 12, the elastic film 50, the insulator film 55, the lower electrode film 60, and the piezoelectric layer 70 are bent and deformed. The pressure in each pressure generating chamber 12 is increased, and ink droplets are ejected from the nozzle openings 21.

Here, a method of manufacturing such an ink jet recording head will be described with reference to FIGS. 5 to 7 are cross-sectional views of the pressure generation chamber 12 in the longitudinal direction. First, as shown in FIG. 5A, a flow path forming substrate wafer 140, which is a silicon wafer, is thermally oxidized in a diffusion furnace at about 1100 ° C. to form a silicon dioxide film 51 constituting the elastic film 50 on the surface thereof. To do. In the present embodiment, a silicon wafer having a relatively thick plate thickness of about 625 μm and high rigidity is used as the flow path forming substrate 10. Next, as shown in FIG. 5B, a zirconium (Zr) layer is formed on the elastic film 50 (silicon dioxide film 51), and then thermally oxidized in, for example, a diffusion furnace at 500 to 1200 ° C. to form zirconium oxide ( An insulator film 55 made of ZrO ₂ ) is formed. Next, as shown in FIG. 5C, for example, after the lower electrode film 60 is formed by laminating platinum and iridium on the insulator film 55, the lower electrode film 60 is patterned into a predetermined shape.

  Next, as shown in FIG. 5 (d), a piezoelectric layer 70 made of, for example, lead zirconate titanate (PZT) or the like, and an upper electrode film 80 made of, for example, iridium, are connected to the flow path forming substrate wafer 140. On the entire surface. Next, as shown in FIG. 6A, the piezoelectric layer 300 is formed by patterning the piezoelectric layer 70 and the upper electrode film 80 in regions facing the pressure generation chambers 12.

  Next, as shown in FIG. 6B, a first lead electrode 90 is formed. Specifically, a metal layer 95 made of a predetermined metal material, for example, aluminum (Al) in this embodiment, is formed on the entire surface of the flow path forming substrate wafer 140. Then, for example, the first lead electrode 90 is formed by patterning the metal layer 95 for each piezoelectric element 300 through a mask pattern (not shown) made of a resist or the like. In the present embodiment, the first lead electrode 90 is made of only the metal layer 95 made of aluminum, but is not limited to this. For example, the metal layer 95 is formed via an adhesion layer made of titanium tungsten (TiW). The first lead electrode 90 may be formed of the adhesion layer and the metal layer 95.

Next, as shown in FIG. 6C, for example, an insulating film 100 made of aluminum oxide (Al ₂ O ₃ ) is formed and patterned into a predetermined shape. That is, the insulating film 100 is formed on the entire surface of the flow path forming substrate wafer 140, and then the insulating film 100 in a region facing the connection portion 60 a of the lower electrode film 60 is removed and the terminals of the first lead electrode 90 are removed. The insulating film 100 in the region facing the portion 90a is removed to form a contact hole 100a. At this time, the insulating film 100 in the contact hole 100a is left thin to prevent damage to the terminal portion 90a as a base.

  In the present embodiment, the layers constituting the piezoelectric element 300, the first lead electrode 90, and the second lead electrode 91 formed in the process described later, together with the regions facing the connection portion 60a and the terminal portion 90a. Other than the pattern area is also removed. Of course, the insulating film 100 may be removed only in a region facing the connection portion 60a and the terminal portion 90a. The method for removing the insulating film 100 is not particularly limited, but for example, dry etching such as ion milling is preferably used. Thereby, the insulating film 100 can be selectively removed favorably.

  Next, the second lead electrode 91 is formed. For example, in the present embodiment, as shown in FIG. 6D, an adhesion layer 96 made of, for example, titanium tungsten (TiW) is formed over the entire surface of the flow path forming substrate wafer 140, and this adhesion layer 96. A metal layer 97 made of, for example, gold (Au) or the like is formed on the entire upper surface. Thereafter, the metal layer 97 is patterned for each piezoelectric element 300 through a mask pattern (not shown), and the adhesion layer 96 is patterned by etching, whereby the second lead electrode 91 is formed.

  Next, as shown in FIG. 7A, a protective substrate wafer 150 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 140. Since the protective substrate wafer 150 has a thickness of, for example, about 625 μm, the rigidity of the flow path forming substrate wafer 140 is significantly improved by bonding the protective substrate wafer 150.

Next, as shown in FIG. 7B, after the flow path forming substrate wafer 140 is polished to a certain thickness, it is further wet-etched with a mixed aqueous solution of hydrofluoric acid and nitric acid, thereby allowing the flow path forming substrate wafer. 140 is set to a predetermined thickness. For example, in this embodiment, the flow path forming substrate wafer 140 is etched so as to have a thickness of about 70 μm. Next, as shown in FIG. 7C, a mask film 52 made of, for example, silicon nitride (SiN _x ) is newly formed on the flow path forming substrate wafer 140 and patterned into a predetermined shape. Then, the flow path forming substrate wafer 140 is anisotropically etched through the mask film 52 to form the pressure generating chamber 12, the communication portion 13, the ink supply path 14, and the like in the flow path forming substrate wafer 140. .

  After that, unnecessary portions of the outer peripheral edge portions of the flow path forming substrate wafer 140 and the protective substrate wafer 150 are removed by cutting, for example, by dicing. The nozzle plate 20 having the nozzle openings 21 formed on the surface of the flow path forming substrate wafer 140 opposite to the protective substrate wafer 150 is bonded, and the compliance substrate 40 is bonded to the protective substrate wafer 150. By dividing the flow path forming substrate wafer 140 and the like into the flow path forming substrate 10 and the like having one chip size as shown in FIG. 1, the ink jet recording head of this embodiment is obtained.

  Finally, by applying a sufficient voltage between the connection portion 60a of the lower electrode film 60 and the connection portion 91a of the second lead electrode 91, the insulating film 100 remaining in the contact hole 100a is destroyed and the first film Good electrical conductivity between the lead electrode 90 and the second lead electrode 91 is ensured. Here, the voltage applied between the connection portion 60a of the lower electrode film 60 and the connection portion 91a of the second lead electrode 91 may be either direct current or alternating current. Furthermore, after applying the direct current voltage, an alternating voltage is applied. As described above, it may be applied. However, when the AC voltage is applied after the DC voltage is applied, the electrical conductivity between the connecting portions 60a and 91a can be ensured best. That is, when the voltage is applied to destroy the insulating film 100, application of a unidirectional voltage with direct current may cause sparse film residue. In this case, sufficient electrical conductivity should be ensured. I can't. Even in such a case, by applying a bidirectional AC voltage thereafter, the film residue can be completely removed to ensure good electrical conductivity. It is considered that the same phenomenon occurs when only an alternating voltage is applied.

  FIG. 8 is a graph showing the conductivity measured for several nozzles before and after applying a DC voltage. Referring to the figure, in this case, when no voltage is applied, four defective continuity rates are generated, whereas when voltage is applied, good continuity is observed at all points. The rate is secured.

  On the other hand, FIG. 9 is a graph in which the conductivity is measured for several nozzles when a DC voltage is applied, a DC voltage is applied, and an AC voltage is further applied after the DC voltage is applied. Referring to the figure, in this case, simply applying a DC voltage results in low conductivity in many places. This is considered to be due to the occurrence of film residue at each of these portions. On the other hand, when an alternating voltage is further applied, good conductivity is ensured at all locations. This is considered to be because the film residue could be completely removed by application of alternating current.

<Embodiment 2>
FIG. 10 is a plan view and a cross-sectional view of the ink jet recording head according to the second embodiment. In the present embodiment, the piezoelectric element 300 is covered with the insulating film 100 together with another insulating film 101. That is, in the present embodiment, as shown in FIG. 8, another insulating film 101 made of, for example, aluminum oxide is formed on the lower side of the first lead electrode 90. Provided on the insulating film 101 and connected to the upper electrode film 80 through a contact hole 101a. That is, the first lead electrode 90 ensures electrical continuity with the upper electrode film 80 through the contact hole 101a.

  An insulating film 100 is further formed on the insulating film 101, and is the same as that of the first embodiment except that the piezoelectric element 300 is covered with the insulating film 100 and the other insulating film 101. That is, the second lead electrode 91 ensures electrical continuity with the first lead electrode 90 through the contact hole 100 a provided in the insulating film 100.

  In such a configuration, the piezoelectric element 300 is covered with the two layers of the insulating film 100 and the other insulating film 101, and contact with moisture (humidity) of the piezoelectric layer 70 is prevented. The destruction caused by the moisture (humidity) can be further reliably prevented.

  Note that the contact hole 101a is formed in the same procedure as the contact hole 100a. That is, first, the insulating film 101 is left thin, and then the remaining thin film is removed by applying a voltage. Here, the voltage applied to remove the thin film is exactly the same as in the first embodiment, and may be either direct current or alternating current, and even if the alternating voltage is applied after the direct current voltage is applied. good. Further, the actions and effects for the respective voltage application modes can be considered in the same manner as in the first embodiment.

(Other embodiments)
As mentioned above, although each embodiment of this invention was described, this invention is not limited to embodiment mentioned above. For example, in the above-described embodiment, the piezoelectric element 300 is formed in the piezoelectric element holding portion 31 of the protective substrate 30. However, the present invention is not limited to this, and the piezoelectric element 300 may be exposed. Even in this case, since the pattern regions of the piezoelectric element 300, the first lead electrode 90, and the second lead electrode 91 are covered with the insulating film 100 made of an inorganic insulating material, the piezoelectric body is caused by moisture (humidity). The destruction of the layer 70 is reliably prevented. Further, for example, in the above-described embodiment, the connection portion 60a of the lower electrode film 60 and the terminal portion 90a of the first lead electrode 90 are provided outside the row of the piezoelectric elements 300. However, the present invention is not limited to this. For example, the lower electrode film 60 or the lead electrode 90A may be drawn from between the piezoelectric elements 300, and, for example, a plurality of connection portions 60a or terminal portions 90a may be provided.

  The ink jet recording head according to the above-described embodiment constitutes a part of a recording head unit including an ink flow path communicating with an ink cartridge or the like, and is mounted on the ink jet recording apparatus. FIG. 11 is a schematic view showing an example of the ink jet recording apparatus. As shown in FIG. 11, in the recording head units 1A and 1B having the ink jet recording head, cartridges 2A and 2B constituting ink supply means are detachably provided, and a carriage 3 on which the recording head units 1A and 1B are mounted. Is provided on a carriage shaft 5 attached to the apparatus body 4 so as to be movable in the axial direction. The recording head units 1A and 1B, for example, are configured to eject a black ink composition and a color ink composition, respectively. The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted is moved along the carriage shaft 5. The On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller (not shown), is conveyed on the platen 8. It is like that.

  In the above-described embodiment, the ink jet recording head has been described as an example of the liquid ejecting head of the present invention. However, the basic configuration of the liquid ejecting head is not limited to the above-described configuration. The present invention covers a wide range of liquid ejecting heads, and can naturally be applied to those ejecting liquids other than ink. 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 (surface emitting 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.

FIG. 3 is an exploded perspective view 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. 3 is a plan view showing a wiring structure according to Embodiment 1. FIG. 6 is a plan view showing a modification of the wiring structure according to Embodiment 1. FIG. 5 is a cross-sectional view illustrating a manufacturing process of the recording head according to Embodiment 1. FIG. 5 is a cross-sectional view illustrating a manufacturing process of the recording head according to Embodiment 1. FIG. 5 is a cross-sectional view illustrating a manufacturing process of the recording head according to Embodiment 1. FIG. It is a graph which shows the electrical conductivity before and behind applying a DC voltage. It is the graph which added the case where the alternating voltage was further applied in the case of FIG. 6A and 6B are a plan view and a cross-sectional view of a recording head according to Embodiment 2. 1 is a schematic diagram of a recording apparatus according to an embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Flow path formation board | substrate, 12 Pressure generation chamber, 20 Nozzle plate, 21 Nozzle opening, 30 Protection board, 31 Piezoelectric element holding | maintenance part, 32 Reservoir part, 40 Compliance board | substrate, 50 Elastic film, 55 Insulator film, 60 Lower electrode film , 70 piezoelectric film, 80 upper electrode film, 100 insulating film, 110 reservoir, 120 drive IC, 130 connection wiring, 140 channel forming substrate wafer, 150 protective substrate wafer, 300 piezoelectric element

Claims (10)

  A piezoelectric element having a piezoelectric layer and an electrode for applying a voltage to the piezoelectric layer and integrated with the diaphragm via one electrode, an insulating film covering at least the outside of the piezoelectric element, and the insulating film A lead electrode connected to the other electrode of the piezoelectric element through a contact hole provided in the contact hole, and the insulating film remaining in the contact hole is sufficiently interposed between the one electrode and the other electrode. A piezoelectric actuator characterized in that electrical continuity between the other electrode and the lead electrode is ensured by applying and destroying an appropriate voltage. The piezoelectric actuator according to claim 1, wherein
The lead electrode has one end directly in contact with the other electrode and the entire outside is covered with the insulating film, and one end is interposed through a contact hole provided in the insulating film. And a second lead electrode in contact with the other end of the first lead electrode. The piezoelectric actuator according to claim 1, wherein
The lead electrode has a first lead electrode whose one end is in direct contact with the other electrode, and a second lead electrode whose one end is in contact with the other end of the first lead electrode. ,
The insulating film is in contact with the outer peripheral surface of the piezoelectric element to cover the piezoelectric element and includes a first contact hole that secures contact between one end of the first lead electrode and the other electrode of the piezoelectric element. The insulating film, the first insulating film coated on the piezoelectric element, and the outer peripheral surface of the first lead electrode so as to cover the piezoelectric element, and the other end of the first lead electrode and the second electrode A piezoelectric actuator comprising: a second insulating film provided with a contact hole for ensuring contact with a lead electrode. The piezoelectric actuator according to any one of claims 1 to 3,
2. The piezoelectric actuator according to claim 1, wherein the insulating film is broken by applying a DC voltage between the one electrode and the other electrode, and further breaking by applying an AC voltage. The piezoelectric actuator according to any one of claims 1 to 4, wherein
The piezoelectric actuator, wherein the insulating film is made of an amorphous material. The piezoelectric actuator according to claim 5, wherein
The piezoelectric actuator, wherein the amorphous material is aluminum oxide.   A liquid ejecting apparatus comprising: a liquid ejecting head that uses the piezoelectric actuator according to claim 1 as a driving source for ejecting liquid in a pressure generating chamber from a nozzle opening. Covering the outside of the piezoelectric element integrated with the diaphragm via one electrode with an insulating film;
Forming a contact hole for ensuring electrical continuity with the other electrode of the piezoelectric element in the insulating film, leaving the insulating film thin;
Forming a lead electrode connected to the other electrode;
And a step of applying a sufficient voltage between the one electrode and the other electrode to destroy and remove the insulating film remaining in the contact hole. In the manufacturing method of the piezoelectric actuator of Claim 8,
The method for manufacturing a piezoelectric actuator, wherein the contact hole of the insulating film is formed by removing the insulating film by an ion milling method. In the manufacturing method of the piezoelectric actuator of Claim 8,
The method for manufacturing a piezoelectric actuator, wherein the insulating film is broken by applying a DC voltage between the one electrode and the other electrode, and further breaking by applying an AC voltage.

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