JP2012035490A - Method of manufacturing piezoelectric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric actuator which can be driven stably while minimizing a decrease in displacement and enhancing the adhesion of a substrate and a lower electrode, and to provide a liquid ejection head equipped with a piezoelectric actuator, and a liquid ejector.SOLUTION: A titanium film 61, and a platinum film 62 formed on the titanium film 61 and having a film thickness ratio of 1.5 or less are fired with a PZT precursor film 71 containing titanium, platinum, and oxygen. When the film thickness of the titanium film 61 is set to 40 nm or less, diffusion of titanium to the interface with the PZT precursor film 71 due to firing can be minimized, and thereby formation of titanium oxide is minimized. Furthermore, a lower limit of the film thickness of the titanium film 61 is determined according to the film thickness of the platinum film 62. Consequently, adhesion between an elastic film 50 and an insulator film 55 and a lower electrode 60 can be enhanced while minimizing a decrease in displacement, and a piezoelectric actuator 310 which can be driven stably and a manufacturing method the piezoelectric actuator 310 can be obtained.

Description

  The present invention relates to a method for manufacturing a piezoelectric actuator.

Piezoelectric materials including crystals typified by lead zirconate titanate (PZT) have a piezoelectric effect and the like, and thus are applied to piezoelectric actuators. The piezoelectric actuator includes a substrate and a piezoelectric element having a pair of electrodes. The piezoelectric actuator is driven by applying a voltage between a pair of electrodes and deforming the piezoelectric body according to the voltage.
In addition, an ink jet type as a liquid ejecting head in which a part of a pressure generating chamber communicating with a nozzle opening for discharging ink as liquid is configured by a piezoelectric actuator and pressurizing ink in the pressure generating chamber to discharge ink from the nozzle opening 2. Description of the Related Art An ink jet recording apparatus is known as a recording head and a liquid ejecting apparatus.

Using a substrate having an insulator film that is an oxide film, a lower electrode film as a lower electrode composed of an adhesion layer and a platinum layer, a titanium layer, a piezoelectric layer, and an upper electrode film as an upper electrode are sequentially formed on the insulator film. An actuator device as a stacked piezoelectric actuator is known.
Specifically, the lower electrode film is formed by forming an adhesion layer made of titanium having a thickness of 5 to 50 nm on the insulator film, and then forming a platinum layer made of platinum on the adhesion layer and having a thickness of 50 to 500 nm. (See Patent Document 1).

JP 2007-118193 A

When the adhesion layer is thickened, the adhesion between the oxide film and the lower electrode is improved, but titanium is diffused to the interface between the lower electrode and PZT during firing of PZT, and titanium oxide is formed at the interface, resulting in a decrease in displacement.
Therefore, it is difficult to obtain a piezoelectric actuator, a liquid ejecting head including the piezoelectric actuator, a liquid ejecting apparatus, and the like that can improve the adhesion between the substrate and the lower electrode while suppressing a decrease in displacement and can perform stable driving.

  The present invention has been made to solve the above-described problems, and can be realized as the following forms or application examples.

[Application Example 1]
A titanium film forming step of forming a titanium film having a thickness of 40 nm or less on the oxide film of the substrate having an oxide film; and a ratio of film thickness (platinum film thickness) / (the titanium film) on the titanium film. A platinum film forming step of forming the platinum film having a thickness of 1.5 or less; and a piezoelectric precursor film forming step of forming a piezoelectric precursor film containing lead, zircon and titanium on the platinum film; And a piezoelectric layer forming step of firing the piezoelectric precursor film to form a piezoelectric layer.

  According to this application example, a titanium film having a thickness of 40 nm or less and a ratio of the thickness (platinum film thickness) / (titanium film thickness) formed on the titanium film is 1.5 or less. The platinum film is fired together with the piezoelectric precursor film containing titanium, platinum and oxygen. By setting the film thickness of the titanium film to 40 nm or less, titanium diffusion due to baking to the interface with the piezoelectric precursor film is suppressed, and formation of titanium oxide is suppressed. Further, the lower limit of the thickness of the titanium film is determined according to the thickness of the platinum film. Therefore, it is possible to obtain a method of manufacturing a piezoelectric actuator capable of improving the adhesion between the substrate and the lower electrode while suppressing a decrease in displacement and performing stable driving.

[Application Example 2]
The method of manufacturing a piezoelectric actuator, wherein the platinum film has a thickness of 30 nm or less.
In this application example, a method of manufacturing a piezoelectric actuator having uniform adhesion can be obtained by suppressing variation in adhesion between the substrate and the lower electrode.

1 is a schematic perspective view illustrating an example of an ink jet recording apparatus according to an embodiment. FIG. 2 is an exploded partial perspective view showing a schematic configuration of an ink jet recording head. (A) is a partial top view of an inkjet recording head, (b) is the AA fragmentary sectional view in (a). The flowchart figure which shows the manufacturing method of a piezoelectric actuator. The schematic sectional drawing showing the manufacturing method of a piezoelectric actuator. The schematic sectional drawing showing the manufacturing method of a piezoelectric actuator. The schematic sectional drawing showing the manufacturing method of a piezoelectric actuator. The schematic sectional drawing showing the manufacturing method of a piezoelectric actuator. The figure showing the relationship between the film thickness of a contact | adherence layer, and a displacement fall rate. The figure showing the relationship between the film thickness of platinum, and adhesive force.

Hereinafter, embodiments will be described in detail with reference to the drawings.
FIG. 1 is a schematic perspective view illustrating an example of an ink jet recording apparatus 1000 as a liquid ejecting apparatus. The ink jet recording apparatus 1000 includes an ink jet recording head 1 as a liquid ejecting head.
In FIG. 1, an ink jet recording apparatus 1000 includes recording head units 1A and 1B. The recording head units 1A and 1B are detachably provided with cartridges 2A and 2B constituting ink supply means. A carriage 3 on which the recording head units 1A and 1B are mounted is a carriage shaft 5 attached to the apparatus main body 4. Are provided so as to be axially movable.

  The recording head units 1A and 1B, for example, discharge a black ink composition and a color ink composition, respectively. Then, the driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and a timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted moves along the carriage shaft 5. . On the other hand, the apparatus main 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 not-shown paper feed roller, is conveyed on the platen 8. It is like that.

  The recording head units 1 </ b> A and 1 </ b> B include the ink jet recording head 1 at a position facing the recording sheet S. In the drawing, the ink jet recording head 1 is located on the recording sheet S side of the recording head units 1A and 1B, and is not directly illustrated.

FIG. 2 is an exploded partial perspective view showing the ink jet recording head 1 according to the embodiment. The shape of the ink jet recording head 1 is a substantially rectangular parallelepiped, and FIG. 2 is an exploded partial perspective view cut along a plane orthogonal to the longitudinal direction of the ink jet recording head 1 (the direction of the white arrow in the figure).
3A is a partial plan view of the ink jet recording head 1, and FIG. 3B is a partial sectional view taken along line AA in FIG.

2 and 3, the ink jet recording head 1 includes a flow path forming substrate 10, a nozzle plate 20, a protective substrate 30, a compliance substrate 40, and a drive circuit 200.
The flow path forming substrate 10, the nozzle plate 20, and the protective substrate 30 are stacked so that the flow path forming substrate 10 is sandwiched between the nozzle plate 20 and the protective substrate 30, and the compliance substrate 40 is formed on the protective substrate 30. ing.

  The flow path forming substrate 10 is made of a silicon single crystal plate having a plane orientation (110). A plurality of pressure generating chambers 12 are formed in a row on the flow path forming substrate 10 by anisotropic etching. The cross-sectional shape of the pressure generation chamber 12 in the width direction of the ink jet recording head 1 is trapezoidal, and the pressure generation chamber 12 is formed long in the width direction of the ink jet recording head 1.

  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 in each pressure generation chamber 12. It communicates via an ink supply path 14 as a liquid supply path. 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 the nozzle plate 20, nozzle openings 21 communicating with the outside are formed in the vicinity of the end of each pressure generating chamber 12 on the side opposite to the ink supply path 14.
The nozzle plate 20 is made of glass ceramics, a silicon single crystal substrate, non-rust steel, or the like.
The flow path forming substrate 10 and the nozzle plate 20 are fixed by an adhesive, a heat welding film, or the like via a mask film 51. The mask film 51 is made of silicon nitride or the like, and the flow path forming substrate 10 is anisotropically etched using an alkaline solution such as KOH through the mask film 51, whereby the pressure generating chamber 12, The communication part 13 and the ink supply path 14 are formed.

An elastic film 50 constituting a vibration plate as a substrate is formed on the surface of the flow path forming substrate 10 facing the surface to which the nozzle plate 20 is fixed. The elastic film 50 is made of an oxide film formed by thermal oxidation.
An insulator film 55 made of an oxide film is formed on the elastic film 50 of the flow path forming substrate 10. The insulator film 55 is formed as follows, for example.
First, a zirconium film is formed. The zirconium film can be formed by a sputtering method or the like. The insulator film 55 made of zirconium oxide is formed by thermally oxidizing the zirconium film in a diffusion furnace at 500 to 1200 ° C.
In the embodiment, the diaphragm as a substrate is composed of the elastic film 50 and the insulator film 55.

Further, on the insulator film 55, a lower electrode 60 having a thickness of, for example, about 0.01 to 0.02 μm, a piezoelectric layer 70 having a thickness of, for example, about 0.5 to 5 μm, and a thickness of For example, the piezoelectric element 300 including the upper electrode 80 of about 0.01 μm is formed.
The lower electrode 60 includes, for example, metals such as platinum, iridium, and titanium, and oxides thereof.
The piezoelectric layer 70 includes, for example, a piezoelectric material PZT. As the piezoelectric material, for example, a relaxor ferroelectric material in which a metal such as niobium, nickel, magnesium, bismuth or yttrium is added to PZT may be used. Moreover, you may use what is called a lead-free piezoelectric material which does not contain lead in a piezoelectric material.
For the upper electrode 80, a metal such as gold, platinum, or iridium can be used.

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 generation 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 embodiment, the lower electrode 60 is a common electrode of the piezoelectric element 300, and the upper 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 either case, a piezoelectric active part is formed for each pressure generating chamber 12. In addition, here, the piezoelectric element 300 and the elastic film 50 and the insulator film 55 serving as substrates on which displacement occurs due to the driving of the piezoelectric element 300 are collectively referred to as a piezoelectric actuator 310.

A method for manufacturing the piezoelectric actuator 310 will be described below.
FIG. 4 is a flowchart showing a part of the manufacturing method of the piezoelectric actuator 310.
The manufacturing method of the piezoelectric actuator 310 includes step 1 (S1) as a titanium film forming process, step 2 (S2) as a platinum film forming process, step 3 (S3) as a piezoelectric precursor film forming process, Step 4 (S4) as a piezoelectric layer forming process.

  5 (a) and 5 (b) show the substrate forming step, FIG. 5 (c) shows the titanium film forming step (S1), FIG. 5 (d) shows the platinum film forming step (S2), and FIG. e) shows an iridium film forming step, FIG. 6 (f) shows a seed titanium film forming step, and FIGS. 6 (g) to 7 (j) show a piezoelectric precursor film forming step (S3) or a piezoelectric layer forming step. (S4) and FIGS. 7 (k) to 8 (m) show the piezoelectric actuator forming step. Here, FIGS. 5A to 7J are enlarged schematic sectional views, and FIGS. 7K to 8M are schematic sectional views.

  In FIG. 5A, in the substrate forming step, a flow path forming substrate wafer 110, which is a silicon wafer, is thermally oxidized in a diffusion furnace at about 1100 ° C., and an elastic film 50 is formed on the surface thereof. In the embodiment, a silicon wafer having a relatively thick film thickness of about 625 μm and a high rigidity is used as the flow path forming substrate wafer 110.

  In FIG. 5B, in the substrate forming step, an insulator film 55 made of zirconium oxide is formed on the elastic film 50. Specifically, after forming a zirconium film on the elastic film 50 by, for example, a sputtering method or the like, the zirconium film is thermally oxidized in, for example, a diffusion furnace at 500 to 1200 ° C. to thereby form an insulator film made of zirconium oxide. 55 is formed.

  5C, in the titanium film forming step (S1), a titanium film 61 having a thickness of 40 nm or less as an adhesion layer is formed on the insulator film 55. In the embodiment, the titanium film 61 is formed with a thickness of 20 nm. By providing the titanium film 61 in this manner, the adhesion between the insulator film 55 and the lower electrode 60 shown in FIG. 3 can be enhanced.

  In FIG. 5D, in the platinum film forming step (S2), the titanium film 61 is made of platinum, and the ratio of film thickness (platinum film thickness) / (titanium film thickness) is 1.5 or less. A platinum film 62 is formed. In the embodiment, the platinum film 62 is formed with a thickness of 30 nm.

  In FIG. 6 (e), in the iridium film forming step, an iridium film 63 is formed on the platinum film 62. The thickness of the iridium film 63 is 5 nm, for example. By forming the iridium film 63, diffusion of lead from the piezoelectric layer 70 shown in FIG. 3 can be reduced.

  6F, in the seed titanium film forming step, a seed titanium film 64 made of titanium and having a thickness of 1 to 20 nm, and in the embodiment, a thickness of 4 nm is formed on the iridium film 63. By providing the seed titanium film 64 on the iridium film 63 in this way, when the piezoelectric layer 70 shown in FIG. 3 is formed on the seed titanium film 64 in a later step, the preferred orientation direction of the piezoelectric layer 70 is set. Can be controlled to (100) or (111), and the piezoelectric layer 70 having a suitable piezoelectric effect can be obtained. The seed titanium film 64 functions as a seed for promoting crystallization when the piezoelectric body is crystallized. After the piezoelectric body layer 70 is baked, part or all of the seed titanium film 64 is in the piezoelectric body layer 70. It is something that diffuses.

The lower electrode film 65 is formed by the titanium film 61, the platinum film 62, the iridium film 63 and the seed titanium film 64.
Each layer of the lower electrode film 65 can be formed by, for example, a DC magnetron sputtering method.

  6 (g) to 7 (j), the piezoelectric layer 70 shown in FIG. 3 is formed by the piezoelectric precursor film forming step (S3) and the piezoelectric layer forming step (S4). In the embodiment, a so-called sol in which a metal organic material is dissolved and dispersed in a catalyst is applied, dried, gelled, and further fired at a high temperature to obtain a piezoelectric layer 70 made of a metal oxide. A piezoelectric layer 70 is formed. As a material of the piezoelectric layer 70, for example, a ferroelectric piezoelectric material such as PZT, or a relaxor ferroelectric material in which a metal such as niobium, nickel, magnesium, bismuth or yttrium is added thereto is used.

Furthermore, it is not limited to the manufacturing method of the piezoelectric layer film by these liquid phase methods, The manufacturing method of the piezoelectric layer film using vapor deposition methods, such as sputtering, may be used.
The method is not limited to the sol-gel method, and for example, a MOD (Metal-Organic Decomposition) method or the like may be used.

  In FIG. 6G, a PZT precursor film 71 which is a piezoelectric precursor film is formed on the lower electrode film 65 before patterning. That is, a sol containing a metal organic compound is applied (application process) on the flow path forming substrate 10 on which the lower electrode film 65 is formed. Next, the PZT precursor film 71 is heated to a predetermined temperature and dried for a predetermined time. For example, in the embodiment, the PZT precursor film 71 can be dried (drying process) by holding at 170 to 180 ° C. for 8 to 30 minutes. Moreover, 0.5-1.5 degreeC / sec is suitable for the temperature increase rate in a drying process. The “temperature increase rate” referred to here is the time from the temperature at which the temperature difference between the temperature at the start of heating (room temperature) and the attained temperature increases by 20% to the temperature at which the temperature difference reaches 80%. It is defined as the rate of change. For example, when the temperature is raised from room temperature 25 ° C. to 100 ° C. in 50 seconds, the rate of temperature rise is (100−25) × (0.8−0.2) /50=0.9 [° C./sec]. Become.

Next, the dried PZT precursor film 71 is degreased (degreasing step) by heating it to a predetermined temperature and holding it for a certain period of time. For example, in the embodiment, the PZT precursor film 71 is degreased by heating to a temperature of about 300 to 400 ° C. and holding for about 10 to 30 minutes. The degreasing referred to here is to release the organic component contained in the PZT precursor film 71 as, for example, NO ₂ , CO ₂ , H ₂ O or the like. Moreover, in degreasing, it is preferable that a temperature increase rate shall be 0.5-1.5 degree-C / sec.

  In FIG. 6 (h), the PZT precursor film 71 is heated to a predetermined temperature and fired (firing process), and is crystallized by holding for a certain period of time to form a piezoelectric film 72. In baking, it is preferable to heat the PZT precursor film 71 to 680-900 degreeC. In the embodiment, the PZT precursor film 71 is baked by heating at 680 ° C. for 5 to 30 minutes to form the piezoelectric film 72. Here, the heating method of the PZT precursor film 71 in the baking is not particularly limited, but it is preferable to use a RTA (Rapid Thermal Annealing) method or the like, for example, to relatively increase the temperature rising rate. For example, in the embodiment, the PZT precursor film 71 is heated at a relatively high temperature increase rate using an RTA apparatus that is heated by irradiation with an infrared lamp. Note that the rate of temperature rise when the PZT precursor film 71 is fired is 50 ° C./sec or more.

  In FIG. 7I, when the first layer of the piezoelectric film 72 is formed on the lower electrode film 65, the lower electrode film 65 and the first piezoelectric film 72 are simultaneously patterned.

  Here, for example, when the first piezoelectric film 72 is formed after patterning after the seed titanium film 64 is formed, the seed titanium film 64 is altered for patterning by photo process, ion milling, and ashing. End up. Therefore, even if the first piezoelectric film 72 is formed on the altered seed titanium film 64, the crystallinity of the piezoelectric film 72 is not good, and the first piezoelectric film 72 is formed on the first piezoelectric film 72. Since the other piezoelectric film 72 is also grown by affecting the crystal state of the first piezoelectric film 72, the piezoelectric film 72 having good crystallinity is not formed.

  In contrast, if the first piezoelectric film 72 is formed and then patterned simultaneously with the lower electrode film 65, the first piezoelectric film 72 is the second and subsequent piezoelectric films 72 compared to the seed titanium film 64. As a seed for crystal growth, the property is strong. Even if an extremely thin altered layer is formed on the surface layer by patterning, the crystal growth of the second and subsequent piezoelectric films 72 is not greatly affected.

  In FIG. 7 (j), a piezoelectric film having a predetermined thickness composed of a plurality of layers of piezoelectric films 72 is repeated by repeating the piezoelectric film forming process including the coating process, the drying process, the degreasing process, and the baking process described above after patterning. The body layer 70 is formed. For example, when the film thickness per sol is about 0.1 μm, the entire film thickness of the piezoelectric layer 70 composed of ten piezoelectric films 72 is about 1.1 μm, for example.

  As described above, when the first layer of the piezoelectric film 72 is formed on the lower electrode film 65, these are simultaneously patterned to form the lower electrode film 72 when the second piezoelectric film 72 is formed. In the vicinity of the boundary between the portion where the 65 and first layer piezoelectric films 72 are formed and the other portion, the adverse effect on the crystallinity of the second layer piezoelectric film 72 due to the difference in the base is reduced, that is, relaxed. it can. Thereby, in the vicinity of the boundary between the lower electrode film 65 and the other part, the crystal growth of the second piezoelectric film 72 proceeds well, and the piezoelectric layer 70 having excellent crystallinity can be formed.

  When the piezoelectric film 72 is thus formed, the titanium film 61, the platinum film 62, the iridium film 63, and the seed titanium film 64 constituting the lower electrode film 65 are also heated at the same time. Diffusion, formation of platinum crystal grains, oxidation, and the like occur, and an alloy containing titanium, platinum, oxygen, and iridium is formed. Therefore, in FIGS. 6 (h) to 7 (j), the state of the lower electrode film 65 is considered to be different depending on each stage, and therefore each film is not shown in detail.

  In FIG. 7 (k), after the piezoelectric layer 70 is formed, for example, an upper electrode film made of iridium is formed on the entire surface of the flow path forming substrate wafer 110, and the piezoelectric layer 70 and the upper electrode film are Patterning is performed in a region facing the pressure generation chamber 12 to form the piezoelectric element 300 and the piezoelectric actuator 310 including the lower electrode 60, the piezoelectric layer 70, and the upper electrode 80. The upper electrode film can be formed by sputtering, for example, DC or RF sputtering.

  In FIG. 8L, a protective film 100 is formed and patterned into a predetermined shape so as to cover the piezoelectric element 300 and the piezoelectric actuator 310 of the flow path forming substrate wafer 110, and the connection hole 120 is formed. As the protective film 100, a material having moisture resistance, for example, an inorganic insulating material such as silicon oxide, tantalum oxide, or aluminum oxide is preferably used. In particular, aluminum oxide that is an inorganic amorphous material, for example, alumina is used. preferable.

  By covering the piezoelectric element 300 with the protective film 100 in this way, it is possible to prevent the piezoelectric element 300 from being damaged due to moisture in the atmosphere. 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 the embodiment, as shown in FIG. 2, the protective film 100 is continuously provided over the plurality of piezoelectric elements 300, but the present invention is not particularly limited thereto. You may make it provide for every.

In FIG. 8 (m), after a lead electrode film made of, for example, gold (Au) is formed over the entire surface of the flow path forming substrate wafer 110, the piezoelectric film is formed through a mask pattern (not shown) made of, for example, a resist. Patterning is performed for each element 300.
Although the piezoelectric element 300 and the piezoelectric actuator 310 are used up to the stage where the piezoelectric element 300 is formed, the piezoelectric element 300 and the piezoelectric actuator 310 including the protective film 100 and the lead electrode 90 may be used.

  2, 3, and 8 (m), one end of the lead electrode 90 is connected to the upper electrode 80 through a connection hole 120 formed in the protective film 100 and the upper electrode 80. On the other hand, the other end is extended, and at least the tip of the extended tip is exposed at the bottom of the through hole 33 formed in the protective substrate 30. The other end of the lead electrode 90 is connected to a drive circuit 200 that drives the piezoelectric element 300 via a connection wiring 210.

On the flow path forming substrate 10 on which the piezoelectric element 300 is formed, the protective substrate 30 is bonded with an adhesive 35.
The protective substrate 30 has a piezoelectric element holding portion 31 in a state where a space that does not hinder the movement of the piezoelectric element 300 is secured in a region facing the piezoelectric element 300.
In the embodiment, each piezoelectric element holding portion 31 is integrally provided in a region corresponding to each row of pressure generation chambers 12, but may be provided independently for each piezoelectric element 300.
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 protective substrate 30 is formed of a material that is substantially the same as the coefficient of thermal expansion of the flow path forming substrate 10. Then, a silicon single crystal substrate made of the same material as the flow path forming substrate 10 is used.

  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 the embodiment, the reservoir portion 32 is provided along the row of the pressure generating chambers 12 through the protective substrate 30 in the thickness direction, and is communicated with the communicating portion 13 of the flow path forming substrate 10 to be connected to each pressure. A manifold 130 serving as a common ink chamber for the generation chamber 12 is configured.

  The drive signal includes, for example, a drive system signal for driving the drive IC such as a drive power supply signal, and various control system signals such as a serial signal (SI), and the wiring includes a plurality of signals supplied with the respective signals. Consists of wiring.

  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 (for example, a polyphenylene sulfide (PPS) film having a thickness of 6 μm). The sealing film 41 seals one surface of the reservoir portion 32. It has been stopped. The fixing plate 42 is formed of a hard material such as metal (for example, stainless steel (SUS) having a thickness of 30 μm). Since the area of the fixing plate 42 facing the manifold 130 is an opening 43 that is completely removed in the thickness direction, one surface of the manifold 130 is sealed only with a flexible sealing film 41. Has been.

The inkjet recording head 1 can be manufactured as follows.
Unnecessary portions of the outer peripheral edge of the flow path forming substrate wafer 110 and the protective substrate wafer are removed by cutting, for example, by dicing. 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. By dividing the path forming substrate wafer 110 and the like into the channel forming substrate 10 and the like having one chip size as shown in FIGS. 2 and 3, the ink jet recording head 1 of the embodiment is obtained.

  In the ink jet recording head 1, after taking ink from the cartridges 2 </ b> A and 2 </ b> B and filling the interior from the manifold 130 to the nozzle opening 21 with ink, each corresponding to the pressure generating chamber 12 according to the recording signal from the drive circuit 200. A voltage is applied between the lower electrode 60 and the upper electrode 80. By applying voltage, the elastic film 50 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.

FIG. 9 is a diagram showing the thickness of the titanium film 61 and the displacement reduction rate.
In FIG. 9, the horizontal axis indicates the film thickness (nm) of the titanium film 61, and the vertical axis indicates the displacement reduction rate (%).
The rate of decrease in displacement is measured by initially measuring the amount of displacement of the piezoelectric actuator 310 when a constant voltage is applied, measuring the amount of displacement of the piezoelectric actuator 310 after being driven 19 billion times, and reducing the amount of displacement with respect to the initial amount of displacement. Evaluation was performed at the ratio of.
It was 3.9% at 20 nm and 5.5% at 50 nm. A displacement reduction rate of 5% or more is an undesirable decrease in the driving performance of the piezoelectric actuator 310.

FIG. 10 is a diagram showing the relationship between the film thickness of platinum and the adhesion force.
In FIG. 10, the horizontal axis indicates the film thickness (nm) of the platinum film 62, and the vertical axis indicates the adhesion force (Kg / cm ² ). Here, the film thickness of the titanium film 61 was 20 nm, and the film thickness of the iridium film 63 was 20 nm.
The adhesion was evaluated by a tensile test. The evaluation of adhesion force was performed a plurality of times, and the minimum value, maximum value, and average value were shown in the figure.
It can be seen that when the film thickness of the platinum film 62 is 30 nm, the adhesion is improved and the variation is reduced.

According to such an embodiment, there are the following effects.
(1) Titanium film 61 having a film thickness of 40 nm or less and a ratio of film thickness (film thickness of platinum film 62) / (film thickness of titanium film 61) of 1.5 or less. The platinum film 62 is fired together with the PZT precursor film 71 containing titanium, platinum and oxygen. By setting the film thickness of the titanium film 61 to 40 nm or less, it is possible to suppress the diffusion of titanium due to the baking to the interface with the PZT precursor film 71 and to suppress the formation of titanium oxide. Further, the lower limit of the thickness of the titanium film 61 is determined according to the thickness of the platinum film 62. Therefore, it is possible to improve the adhesion between the elastic film 50 and the insulator film 55 and the lower electrode 60 while suppressing a decrease in displacement, and to obtain a piezoelectric actuator 310 and a method for manufacturing the piezoelectric actuator 310 that can be stably driven.

  (2) Since the film thickness of the platinum film 62 is 30 nm or less, the diffusion of titanium due to the baking to the interface with the PZT precursor film 71 is further suppressed, the decrease in displacement is further suppressed, and a more stable drive can be performed. 310 and the manufacturing method of the piezoelectric actuator 310 can be obtained.

  (3) Since the piezoelectric actuator 310 having the above-described effects is provided, the ink jet recording head 1 that can stably eject ink can be obtained.

  (4) Since the ink jet recording head 1 having the above-described effects is provided, an ink jet recording apparatus 1000 that can stably eject ink can be obtained.

In the above-described embodiment, an ink jet recording head has been described as an example of a liquid ejecting head. However, the present invention is widely intended for all liquid ejecting heads, and is a liquid ejecting head that ejects liquid other than ink. Of course, it is also applicable.
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.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet recording head, 1A, 1B ... Recording head unit, 2A, 2B ... Cartridge, 3 ... Carriage, 4 ... Device main body, 5 ... Carriage shaft, 6 ... Drive motor, 7 ... Timing belt, 8 ... Platen, 10 DESCRIPTION OF SYMBOLS ... Flow path formation board | substrate, 12 ... Pressure generating chamber, 13 ... Communication part, 14 ... Ink supply path, 20 ... Nozzle plate, 21 ... Nozzle opening, 30 ... Protection board, 31 ... Piezoelectric element holding part, 32 ... Reservoir part, 33 ... Through hole, 35 ... Adhesive, 40 ... Compliance substrate, 41 ... Sealing film, 42 ... Fixing plate, 43 ... Opening, 50 ... Elastic film, 51 ... Mask film, 55 ... Insulator film, 60 ... Bottom Electrode, 61 ... Titanium film, 62 ... Platinum film, 63 ... Iridium film, 64 ... Titanium film, 65 ... Lower electrode film, 70 ... Piezoelectric layer, 71 ... PZT precursor film, 72 ... Piezoelectric film, 80 ... Up Pole, 90 ... lead electrode, 100 ... protective layer, 130 ... manifold, 200 ... driving circuit, 300 ... piezoelectric element, 310 ... piezoelectric actuator, 1000 ... ink jet recording apparatus.

Claims (2)

A titanium film forming step of forming a titanium film having a thickness of 40 nm or less on the oxide film of the substrate having an oxide film;
On the titanium film, a platinum film forming step of forming the platinum film having a film thickness ratio (platinum film thickness) / (thickness of the titanium film) of 1.5 or less;
A piezoelectric precursor film forming step of forming a piezoelectric precursor film containing lead, zircon and titanium on the platinum film;
And a piezoelectric layer forming step of forming the piezoelectric layer by firing the piezoelectric precursor film. In the manufacturing method of the piezoelectric actuator of Claim 1,
The method for manufacturing a piezoelectric actuator, wherein the platinum film has a thickness of 30 nm or less.

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