JP2012166418A - Piezoelectric element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric element having improved adhesion between an insulating film and a second electrode.SOLUTION: The piezoelectric element 300 includes: a first electrode 60; a piezoelectric body layer 70 installed on the first electrode 60; the second electrode 80 installed on the piezoelectric body layer 70; and the insulating film (protective film) 100 installed on the second electrode 80. An irregular part 83 is installed in a region of the second electrode in contact with the insulating film 100.

Description

  The present invention relates to a piezoelectric element.

A piezoelectric element in which a piezoelectric layer is provided between the first electrode and the second electrode is bent and deformed by applying a voltage between the first electrode and the second electrode. Such a piezoelectric element is used as, for example, a pressure generating unit in a liquid ejecting head. A typical example of the liquid ejecting head is an ink jet recording head that ejects ink droplets from nozzle openings using pressure generated by displacement of a piezoelectric element.

Here, the piezoelectric element is easily broken due to an external environment such as moisture. In addition, a leak may occur between the first electrode and the second electrode on the surface of the piezoelectric layer. Therefore, in order to prevent such destruction of the piezoelectric element and not hinder the deformation of the piezoelectric element, the side surface of the piezoelectric layer constituting the piezoelectric element and the surface of the second electrode are covered with a moisture-resistant insulating film (protective film). In addition to covering, there is known one in which an opening is provided in this protective film so that the central portion of the surface of the second electrode is exposed (for example, see Patent Document 1).

JP 2007-216429 A (FIG. 1 etc.)

However, the configuration of Patent Document 1 has a problem that when the piezoelectric element is bent and deformed, the protective film may be peeled off from the second electrode. When the protective film is peeled off from the second electrode in this way, the insulation cannot be ensured and the peeled protective film may become a foreign substance.

Such peeling is a problem that occurs in a piezoelectric element having a protective film regardless of bending deformation due to a difference in thermal expansion coefficient between the second electrode and the protective film. However, it is considered to be particularly problematic in a liquid ejecting head such as an ink jet recording head that requires a large bending deformation of a piezoelectric element in order to eject ink.

In view of such circumstances, an object of the present invention is to provide a piezoelectric element having improved adhesion between a protective film and a second electrode.

The piezoelectric element of the present invention includes a first electrode, a piezoelectric layer provided on the first electrode, a second electrode provided on the piezoelectric layer, and an insulation provided on the second electrode. And a concavo-convex portion is provided in a region in contact with the insulating film of the second electrode.
In the present invention, an uneven portion is provided in the region in contact with the insulating film of the second electrode,
The adhesion between the second electrode and the insulating film can be improved.

The insulating film is provided with an opening for exposing the second electrode, and a region exposed from the opening of the second electrode is preferably a flat surface. Since the region exposed from the opening is a flat surface and no recess is provided, disconnection due to over-etching at the time of opening formation can be prevented.

It is preferable that the convex part which comprises the said uneven | corrugated | grooved part is formed in the peripheral part of the said 2nd electrode. By forming the convex portion, it is possible to maintain the strength of the second electrode, and it is possible to relax the requirement for alignment accuracy when forming the concave and convex portion.

It is preferable that a plurality of convex portions constituting the concave and convex portions are provided so as to extend apart from each other in the longitudinal direction and the short direction of the second electrode, and are arranged so as to cross each other in a lattice shape. By being comprised in this way, the contact area can be increased and the adhesiveness of a 2nd electrode and a protective film can be improved more.

FIG. 2 is an exploded perspective view illustrating a schematic configuration of a recording head. FIG. 4A is a plan view of a main part of the recording head, and FIG. FIG. 6A is a cross-sectional view of the recording head taken along line XX, and FIG. 5B is a cross-sectional view taken along line YY. It is an upper surface schematic diagram of the 2nd electrode concerning this embodiment. FIG. 6 is a partial cross-sectional schematic diagram illustrating a manufacturing process of a recording head. FIG. 6 is a partial cross-sectional schematic diagram illustrating a manufacturing process of a recording head. FIG. 6 is a partial cross-sectional schematic diagram illustrating a manufacturing process of a recording head. FIG. 6 is a partial cross-sectional schematic diagram illustrating a manufacturing process of a recording head. 1 is a perspective view illustrating a schematic configuration of a recording apparatus according to an 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 according to Embodiment 1 of the present invention. FIG. 2A is a plan view of a main part of the ink jet recording head.
FIG. 2B is a cross-sectional view taken along the line AA ′ of FIG.

As shown in the figure, the flow path forming substrate 10 of the ink jet recording head I is made of a silicon single crystal substrate, and one surface thereof is made of silicon dioxide previously formed by thermal oxidation.
An elastic film 50 having a thickness of 0.5 to 2 μm is formed. In the flow path forming substrate 10, a plurality of pressure generating chambers 12 partitioned by a partition wall 11 are arranged in parallel in the width direction. In addition, a communication portion 13 is formed in a region outside the longitudinal direction of the pressure generating chamber 12 of the flow path forming substrate 10, and the communication portion 13 is formed.
And the pressure generation chambers 12 communicate with each other via an ink supply path 14 provided in each pressure generation chamber 12. The communication part 13 constitutes a part of a reservoir that communicates with a reservoir part of a protective substrate, which will be described later, and serves as a common ink chamber for the pressure generating 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, 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 on the opening surface side of the flow path forming substrate 10 will be described later. It is fixed by an adhesive, a heat welding film or the like through a mask film.

On the other hand, an elastic film 50 made of silicon dioxide and 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 made of zirconium oxide (ZrO ₂ ) or the like is laminated. On the insulator film 55, the piezoelectric element 300 including the first electrode 60, the piezoelectric layer 70, and the second electrode 80 is formed.

Here, the piezoelectric element 300 refers to a portion including the first electrode 60, the piezoelectric layer 70, and the second electrode 80. Furthermore, in the present embodiment, the piezoelectric element 300 includes a protective film 100 described later. 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 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. In any case, the piezoelectric active part 320 is formed for each pressure generating chamber 12.

In the present embodiment, the piezoelectric electrode 300 serving as a substantial drive unit of the piezoelectric element 300 is provided by providing the longitudinal end of the pressure generation chamber 12 of the first electrode 60 in a region facing the pressure generation chamber 12. An end (length) in the longitudinal direction of the body active part 320 is defined. Further, the end portions of the piezoelectric layer 70 and the second electrode 80 in the width direction of the pressure generation chamber 12 are provided in regions opposite to the pressure generation chamber 12, so that the end portions of the piezoelectric active portion 320 in the short direction. (Width) is specified. That is, the piezoelectric active part 320 is provided only in a region facing the pressure generating chamber 12 by the patterned first electrode 60 and second electrode 80.

In the present embodiment, the first electrode 60 is provided across the parallel arrangement direction of the plurality of piezoelectric elements 300, and the longitudinal end of the pressure generation chamber 12 of the first electrode 60 is opposed to the pressure generation chamber 12. It was provided so that it would be a position to do. In the above-described example, the elastic film 50, the insulator film 55, and the first electrode 6
Although 0 acts as a diaphragm deforming together with the piezoelectric element 300, it is of course not limited to this. For example, only the first electrode 60 acts as a diaphragm without providing the elastic film 50 and the insulator film 55. You may make it do.

The first electrode 60, the piezoelectric layer 70, and the second electrode 80 (piezoelectric active portion 320) constituting the piezoelectric element 300 are covered with a protective film (insulating film) 100 made of an insulating material having moisture resistance. Yes. Specifically, the protective film 100 is provided so as to cover the side surface of the piezoelectric layer 70 and the periphery of the upper surface of the second electrode 80. That is, the main portion of the upper surface of the second electrode 80 is not provided with the protective film 100, and the opening 10 for exposing the main portion of the upper surface of the second electrode 80.
1 is provided. The opening 101 penetrates the protective film 100 in the thickness direction and the piezoelectric element 30.
For example, the protective film 100 is formed over the entire surface of the flow path forming substrate 10 and then selectively patterned. By doing so, it can be formed.

By covering the piezoelectric element 300 with the protective film 100 in this way, it is possible to suppress the destruction of the piezoelectric element 300 caused by moisture in the atmosphere. Here, as a material of such a protective film 100, a material having moisture resistance may be used, but, for example, a known insulating inorganic material or insulating resin material is preferably used. Known insulating inorganic material, for example, silicon oxide _(SiO x), tantalum oxide _(TaO x), it is preferable to use such aluminum oxide (AlO _x), in particular, aluminum oxide is an inorganic amorphous material (AlO _x )
For example, it is preferable to use alumina (Al ₂ O ₃ ). As a known insulating resin material, for example, a known photosensitive resin material may be used, or a non-photosensitive resin material may be used. When the insulating resin material is a photosensitive resin material, a known unsaturated bond-containing polymerizable compound,
A photopolymerization initiator or the like may also be included. Specifically, the insulating resin material may be a photoresist or a resin composition such as polyimide, cycloten, benzocyclobutene (BCB), or a polyvinyl alcohol derivative. When aluminum oxide is used as the material of the protective film 100, moisture permeation in a high humidity environment can be sufficiently prevented even if the thickness of the protective film 100 is as thin as about 100 nm. In addition, since the opening 101 is provided in the protective film 100, the displacement of the piezoelectric element 300 is not hindered, and the ink ejection characteristics can be maintained satisfactorily.

Here, since the protective film 100 may be peeled off from the second electrode 80 due to, for example, a difference in thermal expansion coefficient or displacement when the piezoelectric element 300 is driven, such a protective film 100 is used.
In order to suppress the peeling of the second electrode 80 from the second electrode 80, in this embodiment, the contact area of the second electrode 80 with the protective film is provided with unevenness. This point will be described with reference to FIG.

3A is a cross-sectional view taken along line XX in FIG. 2A, and FIG. 3B is a cross-sectional view of FIG.
It is sectional drawing in the YY line in FIG.

As shown in FIG. 3A, a concave portion 81 is formed on the upper surface of the second electrode 80 (the surface opposite to the surface on which the piezoelectric layer 70 is provided), so that a relatively convex portion is formed. A concavo-convex portion 83 in which 82 is simultaneously formed is formed. Since the uneven portion 83 is formed on the upper surface of the second electrode 80 in this way, the surface area of the second electrode 80 increases and the second electrode 80 and the protective film 100 formed on the second electrode 80 Adhesion is improved. Thereby, peeling of the protective film 100 from the second electrode 80 can be suppressed.

The uneven portion 83 is formed in a region in contact with the protective film 100 on the upper surface of the second electrode 80. That is, as shown in FIG. 3B, the uneven portion 83 is not provided in the region exposed from the opening 101 of the second electrode 80 (region facing the opening 101 of the second electrode 80). As described in detail later, since the concave and convex portion 83 is not provided in the region exposed to the opening 101 of the second electrode 80 as described in detail later, the manufacturing accuracy at the time of manufacturing the concave portion 81 is improved, thereby stabilizing the displacement characteristics. To do.

As shown in FIG. 4, the recess 81 has a rectangular shape in a top view. The concave portions 81 formed on the upper surface of the second electrode 80 are formed so as to form a so-called matrix state in which the concave portions 81 are arranged on the upper surface of the second electrode 80 so as to be spaced apart from each other in the longitudinal direction and the lateral direction of the second electrode 80. Yes. As a result, the convex portion 82 has a so-called lattice shape in which a plurality of straight portions extend in the vertical and horizontal directions (longitudinal direction and short direction of the second electrode) in the top view and intersect with each other (orthogonal). Is formed.
The region exposed from the opening 101 of the protective film on the upper surface of the second electrode 80 is a flat surface because the uneven portion 83 is not provided.

Further, as shown in FIG. 3, the thickness H <b> 2 of the convex portion 82 is configured to be the same as that of the conventional second electrode 80. The thickness H1 of the recess 81 is thinner than the thickness of the conventional second electrode 80, and is about half in this embodiment. Thus, by providing the recessed part 81 thinner than the thickness of the conventional 2nd electrode 80, while improving the adhesiveness of the 2nd electrode 80 and the protective film 100, the rigidity of the 2nd electrode 80 falls. Therefore, the displacement characteristics can be improved without hindering the displacement of the piezoelectric element when the piezoelectric element 300 is driven.

Further, in the concavo-convex portion 83, the convex portion 82 is provided so as to be positioned at the peripheral edge portion of the second electrode 80. Since the protrusions 82 are provided on the peripheral edge of the second electrode 80 as described above, the end of the second electrode 80 becomes thick, so that the strength of the second electrode 80 is increased, and details will be described later. This is preferable because the manufacturing accuracy at the time of manufacturing the recess 81 is improved, and the displacement characteristics are thereby stabilized.

In the present embodiment, the protective film 100 is formed of a plurality of piezoelectric elements 30 as shown in FIG.
However, the present invention is not particularly limited to this, and for example, the protective film 100 may be provided for each piezoelectric element 300.

On the protective film 100, 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 another opening 100 a provided in the protective film 100.

Further, on the flow path forming substrate 10 on which the piezoelectric element 300 is formed, the protective substrate 30 having the piezoelectric element holding portion 31 having a space that does not hinder the movement of the piezoelectric element 300 in a region facing the piezoelectric element 300. Are joined by an adhesive 35. The piezoelectric element holding part 31
Need only have a space that does not hinder the movement of the piezoelectric element 300, and the space may or may not be sealed.

Further, the protective substrate 30 is provided with a reservoir portion 32 in a region facing the communication portion 13, and the reservoir portion 32 communicates with the communication portion 13 of the flow path forming substrate 10 as described above. A reservoir 111 serving as a common ink chamber for the pressure generation chamber 12 is configured. Further, in the region between the piezoelectric element holding portion 31 and the reservoir portion 32 of the protective substrate 30, there is a protective substrate 3.
A through-hole 33 that penetrates 0 in the thickness direction is provided, and a part of the first electrode 60 and the tip of the lead electrode 90 are exposed in the through-hole 33. This tip portion is a piezoelectric element 300 described later.
Is connected via a connection wiring to a drive circuit for driving the drive circuit.

A drive circuit 200 for driving the piezoelectric element 300 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 200. The drive circuit 200 and the lead electrode 90 are electrically connected via a connection wiring 210 made of a conductive wire such as a bonding wire.

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

On the protective substrate 30, a compliance substrate 40 comprising a sealing film 41 and a fixing plate 42.
Are joined. Here, 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).
1, one surface of the reservoir 32 is sealed. 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 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir is sealed only with a flexible sealing film 41. Yes.

In such an ink jet recording head of this embodiment, after taking ink from an external ink supply means (not shown) and filling the interior from the reservoir 111 to the nozzle opening 21, according to the recording signal from the drive circuit 200, Each voltage is generated by applying a voltage between the first electrode 60 and the second electrode 80 corresponding to the pressure generating chamber 12 to bend and deform the elastic film 50, the first electrode 60, and the piezoelectric layer 70. The pressure in the chamber 12 increases and ink droplets are ejected from the nozzle openings 21.

(Production method)
The method for manufacturing a piezoelectric element of the present invention will be described by taking as an example the case of being provided in a liquid jet head.

First, as shown in FIG. 5A, a flow path forming substrate wafer 11 which is a silicon wafer.
A silicon dioxide film 51 made of silicon dioxide (SiO ₂ ) constituting the elastic film 50 is formed on the 0 surface. Next, as shown in FIG. 5B, the elastic film 50 (silicon dioxide film 51).
), An insulator film 55 made of zirconium oxide is formed. Next, as shown in FIG. 5C, the first electrode 60 is formed on the entire surface of the insulator film 55 and patterned into a predetermined shape (not shown). The material of the first electrode 60 is not particularly limited. However, when lead zirconate titanate (PZT) is used as the piezoelectric layer 70, it is desirable that the material has little change in conductivity due to diffusion of lead oxide. . For this reason, platinum, iridium, etc. are used suitably as a material of the 1st electrode 60. FIG.

Next, as shown in FIG. 6A, the piezoelectric layer 70 and the second electrode 80 are sequentially stacked on the first electrode 60. In this embodiment, the piezoelectric layer 70 is obtained by applying and drying a so-called sol in which an organometallic compound is dissolved and dispersed in a solvent, gelling, and baking at a high temperature to obtain the piezoelectric layer 70 made of a metal oxide. It is formed using a so-called sol-gel method. The method for manufacturing the piezoelectric layer 70 is not limited to the sol-gel method, and for example, a MOD (Metal-Organic Decomp)
osition), sputtering, laser ablation, etc. PVD (Physical Va
Por Deposition) method or the like may be used. The second electrode 80 can be made of a highly conductive metal such as iridium (Ir). The second electrode 80 has the same thickness as the conventional second electrode (for example, a thickness of 10 to 100 nm, and in this embodiment, 50 n
m).

Next, as shown in FIG. 6B, the piezoelectric element 300 is formed by simultaneously patterning the piezoelectric layer 70 and the second electrode 80. Specifically, by patterning the piezoelectric layer 70 and the second electrode 80, the piezoelectric element 300 is formed in a region opposite to the region where each pressure generating chamber 12 of the flow path forming substrate wafer 110 is formed. .

Thereafter, the uneven portion 83 in the present embodiment is formed on the upper surface of the second electrode 80. FIG. 7 (a)
As shown in FIG. 2, a mask pattern 84 made of a resist or the like is formed on the upper surface of the second electrode 80. Then, as shown in FIG. 7B, the concave and convex portion 83 is formed by etching the upper surface of the second electrode 80 through the mask pattern 84. Specifically, the concave portion 81 is formed by forming a mask pattern 84 having the same shape as the convex portion 82 and performing etching for a predetermined time through the mask pattern 84. Thereby, the uneven part 83 is formed on the upper surface of the second electrode. As an etching method, for example, dry etching such as ion milling or reactive dry etching (RIE) can be performed. In this embodiment, dry etching is used.

In this case, in the present embodiment, the convex portion 82 of the concave and convex portion 83 is formed so as to be positioned at the end portion of the second electrode 80. Accordingly, even if the alignment accuracy of the mask pattern 84 is somewhat low and the position of the mask pattern for forming the concave portion 81 is shifted, it is possible to prevent etching other than the upper surface of the second electrode 80, and the manufacturing accuracy Will improve.

Subsequently, after removing the mask pattern 84, a protective film 100 is formed as shown in FIG. The formation method of the protective film 100 is not specifically limited, A well-known film-forming method can be used. Known film formation methods include vapor deposition methods such as CVD and PVD, sputtering, MOD, sol-gel, and spin coating. Then, protective film 1
A mask is provided at 00 and etched to form the opening 101. The protective film 100 can be etched by dry etching such as ion milling or reactive dry etching (RIE). In this case, in this embodiment, the uneven portion 83 is not formed in the region facing the opening 101 of the second electrode 80. That is, in the region facing the opening 101 of the second electrode 80, since the concave portion is not formed and the thickness of the second electrode 80 is the same as the conventional one, overetching occurs when the opening 101 is formed. Even if it does, disconnection etc. do not arise, manufacture is easy, manufacture accuracy improves, and, thereby, a displacement characteristic is stabilized.

After that, after forming the lead electrode, the wafer for the flow path forming substrate is bonded to the piezoelectric element side of the wafer for the flow path forming substrate with an adhesive, and the wafer for the protective substrate, which is a silicon wafer and serves as a plurality of protective substrates. Is reduced to a predetermined thickness. Next, the pressure generating chamber corresponding to the piezoelectric element is formed by anisotropically etching (wet etching) the flow path forming substrate wafer.

After that, unnecessary portions of the outer peripheral edge of the flow path forming substrate wafer and the protective substrate wafer are
For example, it is removed by cutting by dicing or the like. Then, a nozzle plate having a nozzle opening formed on the surface of the flow path forming substrate wafer opposite to the protective substrate wafer is bonded, and a compliance substrate is bonded to the protective substrate wafer. The ink jet recording head I of this embodiment is obtained by dividing a wafer or the like into one chip size flow path forming substrate 10 as shown in FIG.

(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 embodiment described above, the concavo-convex portion 83 is configured by the convex portions 82 having a lattice shape, but is not limited thereto. It is only necessary that the concave and convex portions are formed by forming the concave portions (or convex portions). For example, the uneven portion 83 may have a stripe shape along the longitudinal direction of the second electrode 80 in a top view. Moreover, although the recessed part 81 was rectangular shape in the top view in this embodiment, it is not limited to this, For example, circular shape may be sufficient. of course,
You may be comprised so that the recessed part and convex part of the uneven | corrugated | grooved part 83 may become reverse. However, as shown in the present embodiment, it is preferable that the convex portion 82 is provided at the end of the upper surface of the second electrode 80 because the strength increases without hindering the displacement.

In the above-described embodiment, the thickness of the convex portion 82 is the same as the thickness of the second electrode in the region facing the opening of the protective film 100, but is not limited thereto. For example, in the embodiment shown in FIG. 8A, the thickness of the protrusion 82 formed in the region in contact with the protective film 100 is larger than the thickness of the second electrode 80 in the region facing the opening 101 of the protective film 100. thin. Specifically, the thickness of the second electrode 80 in the region facing the opening 101 of the protective film 100 is larger than the thickness of the conventional second electrode 80, and the thickness of the convex portion 82 is the same as the conventional thickness of the second electrode 80. Are the same. Even in such a configuration, the thickness of the portion exposed from the opening is approximately the same as the conventional thickness of the second electrode 80, so that the second electrode 80 is over-etched when the opening 101 is formed. However, it is possible to further prevent disconnection. In this case, the rigidity of the second electrode increases, but the recess 81
However, since the thickness of the second electrode is smaller than that of the conventional second electrode, the displacement characteristics of the entire piezoelectric element 300 are not deteriorated.

Further, in the embodiment shown in FIG. 8B, the thickness of the convex portion 82 formed in the region in contact with the protective film 100 is larger than the thickness of the second electrode 80 in the region facing the opening 101 of the protective film 100. thick. Even in this case, if the thickness of the second electrode 80 is the same as the thickness of the conventional second electrode 80, even if the second electrode 80 is over-etched when the opening 101 is formed, the wire breaks. It is possible to prevent this possibility.

Moreover, in each embodiment mentioned above, although the uneven | corrugated | grooved part 83 was not provided in the area | region exposed from the opening 101 of the 2nd electrode 80 upper surface, it was set as the flat surface, However, It is not limited to this. For example, the uneven portion 83 may be provided over the entire upper surface, and the uneven portion 83 may also be formed in a region exposed from the opening 101 on the upper surface of the second electrode 80. In this case, if the thickness of the recess 81 in the region exposed from the opening 101 on the upper surface of the second electrode 80 is at least the same thickness as that of the conventional second electrode 80, it is preferable because the possibility of disconnection does not occur.

Moreover, in each embodiment mentioned above, although the opening 101 is provided in the protective film 100, it is not limited to this. Instead of providing the opening 101 in the protective film 100, the uneven portion 83 may be provided on the entire surface of the second electrode 80. The reason why the opening 101 is provided in the protective film 100 is to prevent the displacement of the piezoelectric element from being lowered due to the rigidity of the piezoelectric element being increased by providing the protective film, but the recess 81 is formed. Thus, since the rigidity of the second electrode is lowered, the piezoelectric element 3 is covered with a protective film.
Even if the entire surface of 00 is covered, the displacement characteristics of the piezoelectric element are not deteriorated. Further, in this case, since no opening is provided, there is no possibility of overetching, so that the entire second electrode 80 can be formed thin. Thereby, it can suppress that the displacement characteristic of a piezoelectric element reduces the 2nd electrode 80. FIG.

In the above-described embodiment, the concave portion 81 is formed to relatively form the convex portion 82 to form the concave and convex portion 83, but the present invention is not limited to this. By forming the convex portion, the concave portion 81 may be formed relatively to form the concave and convex portion 83. For example, a mask pattern corresponding to the concave portion is formed on the upper surface of the second electrode, and then the convex portion is formed by laminating the material of the second electrode through the mask pattern and finally lifting off the mask pattern. You may form a recessed part relatively.

In the above-described embodiment, the protective substrate 30 having the piezoelectric element holding portion 31 is provided. However, since the piezoelectric element 300 is covered with the protective film 100 to prevent destruction due to the external environment, A piezoelectric element holding portion that penetrates the substrate 30 in the thickness direction may be used, and a protective substrate may not be provided.

Further, the ink jet recording head I of this embodiment constitutes a part of a recording head unit having an ink flow path communicating with an ink cartridge or the like, and is mounted on the ink jet recording apparatus II. FIG. 9 is a schematic view showing an example of the ink jet recording apparatus.

As shown in FIG. 9, the recording head units 1A and 1B having the ink jet recording head I are detachably provided with cartridges 2A and 2B that constitute ink supply means.
The carriage 3 on which the recording head units 1A and 1B are mounted is provided on a carriage shaft 5 attached to the apparatus main body 4 so as to be movable in the axial direction. This recording head unit 1A
And 1B, for example, discharge 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 has a carriage shaft 5.
A recording sheet S that is a recording medium such as paper fed by a paper feed roller (not shown) is wound around the platen 8 and conveyed.

In the first embodiment described above, an ink jet recording head has been described as an example of a liquid ejecting head. However, the piezoelectric element of the present invention is intended for all liquid ejecting heads, and uses liquids other than ink. Of course, the present invention can also be applied to a liquid ejecting head for ejecting. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in manufacturing 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.

The piezoelectric element of the present invention can be applied not only to a piezoelectric element mounted as a pressure generating unit on such a liquid ejecting head but also to, for example, a memory or a sensor.

I ink jet recording head, II ink jet recording apparatus, 10 flow path forming substrate, 12 pressure generating chamber, 13 communicating portion, 14 ink supply passage, 20 nozzle plate, 21 nozzle opening, 30 protective substrate, 31 piezoelectric element holding portion, 32
Reservoir part, 40 compliance substrate, 60 first electrode, 70 piezoelectric layer, 80 second electrode, 83 uneven part, 90 lead electrode, 100 protective film, 10
1 opening, 111 reservoir, 200 drive circuit, 210 connection wiring, 30
0 Piezoelectric element

Claims (4)

A first electrode;
A piezoelectric layer provided on the first electrode;
A second electrode provided on the piezoelectric layer;
An insulating film provided on the second electrode;
An uneven portion is provided in a region of the second electrode that contacts the insulating film. The insulating film is provided with an opening for exposing the second electrode,
2. The piezoelectric element according to claim 1, wherein a region exposed from the opening of the second electrode is a flat surface. 3. The piezoelectric element according to claim 1, wherein a convex portion constituting the concave and convex portion is formed on a peripheral portion of the second electrode. The convex portions constituting the concave and convex portions are provided to extend in a plurality of positions in the longitudinal direction and the short direction of the second electrode, respectively, and are arranged so as to cross each other in a lattice shape. The piezoelectric element as described in any one of Claims 1-3.

Images