JP6292332B2 - Liquid ejecting head, piezoelectric element, and method of manufacturing liquid ejecting head - Google Patents

Description

  The present invention relates to a liquid ejecting head, a liquid ejecting apparatus, a piezoelectric element, and a method for manufacturing a liquid ejecting head.

Piezoelectric elements having a characteristic of being charged when a crystal is distorted and distorted when placed in an electric field are widely used in liquid ejecting apparatuses such as ink jet printers, actuators, sensors, and the like.
Further, as a configuration of the piezoelectric element, there is known a configuration in which the lower electrode is an individual electrode for each piezoelectric layer and the upper electrode is a common electrode common to a plurality of individual electrodes (for example, see Patent Document 1). .)

JP 2010-42683 A

  In a piezoelectric element using the upper electrode as a common electrode, cracks and burnout may occur in the region of the piezoelectric layer not covered with the upper electrode. The cause is considered to be that the composition of the piezoelectric layer is made unstable by chemicals used when the upper electrode or the wiring is patterned.

  In view of the above, one of the objects of the present invention is to improve the stability of at least the piezoelectric element, the liquid ejecting head, and the liquid ejecting apparatus.

  In order to achieve at least one of the above objects, in the present invention, a plurality of individual electrodes, a piezoelectric layer formed on the individual electrodes, and formed on the piezoelectric layer, A common electrode serving as a common electrode; and a protective film covering a region of the piezoelectric layer not covered with the common electrode on the individual electrode.

  In the invention configured as described above, the piezoelectric element has a configuration in which the upper electrode is a common electrode. The protective film covers the region of the piezoelectric layer that is not covered by the common electrode on the individual electrode. Therefore, it is possible to reduce cracks and burnout on the individual electrodes and in a region not covered by the common electrode.

(A) and (b) are a partial top view and a vertical sectional view showing a main part of the piezoelectric element 3 included in the liquid jet head according to the embodiment of the present invention. FIG. 2 is an exploded perspective view showing an ink jet recording head 1 which is an example of a liquid ejecting head in an exploded manner. (A)-(c) is sectional drawing for demonstrating the manufacturing process of the recording head 1. FIG. (A)-(c) is sectional drawing for demonstrating the manufacturing process of the recording head 1. FIG. 2 shows an appearance of a recording apparatus (liquid ejecting apparatus) 200 having the recording head 1 described above. (A)-(c) is sectional drawing for demonstrating the manufacturing process of the recording head 1. FIG. (A)-(c) is sectional drawing for demonstrating the manufacturing process of the recording head 1. FIG.

  Hereinafter, the present invention will be described in detail based on embodiments. In addition, the structure described in this embodiment is only an example, and is not limited to this.

(1) Configuration of liquid ejection head and piezoelectric element:
FIGS. 1A and 1B are a partial top view and a vertical sectional view showing a main part of the piezoelectric element 3 included in the liquid jet head according to the embodiment of the invention. FIG. 2 is an exploded perspective view showing the ink jet recording head 1 which is an example of the liquid ejecting head in an exploded manner. 3A to 3C are cross-sectional views for explaining the manufacturing process of the recording head 1. 4A to 4C are cross-sectional views for explaining the manufacturing process of the recording head 1.

The recording head (liquid ejecting head) 1 illustrated in FIG. 2 includes a piezoelectric element 3 having a piezoelectric layer 30 and electrodes (20, 40), and pressure generation that causes a pressure change by the piezoelectric element 3 communicating with the nozzle opening 71. And a chamber 12. More specifically, the piezoelectric element 3 is configured by laminating the lower electrode 20, the piezoelectric layer 30, and the upper electrode 40 in this order on the diaphragm 16 having an elastic film.
The flow path forming substrate 10 is fixed to the side of the diaphragm 16 where the piezoelectric element 3 is not laminated. 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 path 13 is formed in a region outside the longitudinal direction of the pressure generation chamber of the flow path forming substrate 10, and the communication path 13 and the pressure generation chamber 12 are provided for each pressure generation chamber 12. It is communicated through.

  A nozzle plate 70 is fixed to the side of the flow path forming substrate 10 that is not fixed to the diaphragm 16. The nozzle plate 70 has a plurality of nozzle openings 71 that are part of a flow path for ejecting ink. Further, a protective substrate 50 to which a compliance substrate 60 is fixed is fixed to the side of the diaphragm 16 to which the piezoelectric element 3 is fixed.

  Next, the configuration of the piezoelectric element 3 will be described with reference to FIG.

As shown in FIG. 1A, the piezoelectric element 3 has a configuration in which the upper electrode 40 is a common electrode, and is laminated on the diaphragm 16.
That is, as shown in FIG. 1B, a lower electrode 20 having a layer containing at least one of platinum (Pt), iridium (Ir), and titanium (Ti) is laminated immediately above the diaphragm 16. ing. The lower electrode 20 is an individual electrode, and is formed for every four piezoelectric elements in this embodiment. Of course, using four piezoelectric elements is an example, and the present invention is not limited to this.

A piezoelectric layer 30 containing at least lead (Pb), zirconium (Zr), and titanium (Ti) is laminated immediately above the lower electrode 20. The piezoelectric layer 30 is made of a perovskite oxide, and is made of lead zirconate titanate containing Pb as the A site element and Zr and Ti as the B site element. Such a perovskite oxide includes a perovskite oxide having a composition represented by the following general formula.
Pb (Zr, Ti) Ox (1)
(Pb, MA) (Zr, Ti) Ox (2)
Pb (Zr, Ti, MB) Ox (3)
(Pb, MA) (Zr, Ti, MB) Ox (4)
Here, MA is one or more metal elements excluding Pb, and MB is one or more metal elements excluding Zr, Ti, and Pb. x is 3 as a standard, but may deviate from 3 within a range where a perovskite structure can be taken. The ratio of the A site element to the B site element is 1: 1 as a standard, but may be deviated from 1: 1 within a range where a perovskite structure can be taken.
The MB element includes Nb (niobium), Ta (tantalum), and the like.

  The formation of the piezoelectric layer 30 with lead zirconate titanate is merely an example, and other lead-based piezoelectric materials or compositions that are lead-free piezoelectric materials are (Bi, Ba) (Zr, Ti ) It may be formed of a piezoelectric material represented by Ox.

  An upper electrode 40 is stacked immediately above the piezoelectric layer 30. The upper electrode 40 is a common electrode common to all the piezoelectric elements 3, and is continuously formed on each piezoelectric layer 30. As the metal constituting the upper electrode 40, iridium (Ir), gold (Au), platinum (Pt), or the like can be used. Of course, in addition to this, a different metal may be contained in the above-described metal.

  As shown in FIG. 1B, the longitudinal end of the lower electrode 20 extends to the outside from the longitudinal end of the pressure generating chamber 12. Further, the longitudinal end portion of the patterned upper electrode 40 corresponding to each pressure generating chamber 12 is positioned in front of the longitudinal end portion of the region where the lower electrode 20 is formed. Further, the longitudinal end portion of the upper electrode 40 extends outward from the longitudinal end portion of the pressure generating chamber 12. That is, in the piezoelectric layer 30, there are a region located on the lower electrode 20 but not covered by the upper electrode 40 and a region located on the lower electrode 20 and covered by the upper electrode 40. . Of course, the positional relationship between the longitudinal ends of the lower electrode 20 and the upper electrode 40 is merely an example. For example, the longitudinal end of the upper electrode 40 is formed in front of the longitudinal end of the pressure generating chamber 12. It may be.

  In addition, a region of the piezoelectric element 3 that is deformed by the action of an electric field is defined as an active portion 3a, and a region that is not deformed by the action of an electric field is defined as an inactive portion 3b. In the piezoelectric element 3 shown in FIG. 1B, the active portion 3a is a region in which the lower electrode 20 is disposed in a region in which the piezoelectric layer 30 is disposed, and a region in which the upper electrode 40 is disposed. Is the active part 3a. The inactive portion 3b is a region in which the lower electrode 20 is disposed in a region in which the piezoelectric layer 30 is disposed, but a region that is not covered by the upper electrode 40 is defined as the inactive portion 3b. Note that the boundary between the active part 3a and the non-active part 3b is also affected by the position of the generated electric field, and thus is not necessarily defined by the positions of the lower electrode 20 and the upper electrode 40 described above.

  A protective film 80 is formed in a region including the boundary between the active portion 3a and the inactive portion 3b on the side where the upper electrode 40 is formed in the piezoelectric layer 30 so as to cover this region. In FIG. 1B, a protective film 80 is formed so as to cover a region of the piezoelectric layer 30 on the lower electrode 20 and not covered with the upper electrode 40.

  Here, it has been found that cracks and burnout due to the cracks are prominent in the vicinity of the boundary between the active portion 3a and the inactive portion 3b in the piezoelectric layer 30. As one of the causes, in the piezoelectric element 3 having the upper electrode 40 as a common electrode, the upper electrode film is formed on the piezoelectric layer 30 and then patterned to form the upper electrode 40 or the wiring is patterned. However, it is known that chemicals or the like are attached to the piezoelectric layer 30 during the patterning, thereby destabilizing the composition of the piezoelectric layer 30. Further, as another cause, stress concentration due to non-uniform strain generation in the piezoelectric layer 30 in the vicinity of the boundary between the active portion 3a and the inactive portion 3b in the piezoelectric layer 30 is caused. is there. Therefore, the protective film 80 is formed so as to cover the boundary between the active portion 3a and the inactive portion 3b, thereby reducing the occurrence of cracks and burnout in this region.

  Further, it is preferable that the end portion on the upper electrode 40 side in the longitudinal direction of the protective film 80 is formed in front of the pressure generation chamber 12. That is, it is preferable that the protective film 80 is not formed above the region where the pressure generation chamber 12 is formed. This is because the protection film 80 is prevented from covering the region where the pressure generation chamber 12 is formed, thereby preventing the driving of the piezoelectric element 3 from being hindered.

As a material of the protective film 80, an organic material such as polyimide (aromatic polyimide) can be used. When the protective film 80 is formed of polyimide, the film thickness is preferably 1.7 μm or more. In addition, the protective film 80 may be formed of an epoxy adhesive or a silicon adhesive. Moreover, when forming the protective film 80 with an adhesive agent, it is preferable that a film thickness shall be 1.6 micrometers or more.
If the protective film 80 is an organic protective film, the protective film 80 can be easily formed.

(2) Manufacturing Method of Piezoelectric Element and Liquid Ejecting Head A manufacturing method of the above-described piezoelectric element 3 and a recording head (liquid ejecting head) 1 including the piezoelectric element 3 will be described with reference to FIGS. Here, a case where polyimide (organic protective film) is used as the protective film 80 will be described as an example.

As a method for manufacturing the recording head 1, first, the flow path forming substrate 10 is formed from a silicon single crystal substrate or the like. For example, the elastic film (diaphragm 16) made of silicon dioxide (SiO ₂ ) is integrated by thermally oxidizing the silicon substrate 15 having a film thickness of about 625 μm, which is relatively thick and highly rigid, with a diffusion path of about 1100 ° C. Form. The thickness of the elastic film is not limited as long as it has elasticity, but can be, for example, about 0.5 to 2 μm.

Next, as shown in FIG. 3A, a lower electrode film for forming the lower electrode 20 is formed on the diaphragm 16 by sputtering or the like. As a constituent metal of the lower electrode 20, one or more kinds of metals such as Pt, Au, Ir, Ti, and the like can be used. Although the thickness of a lower electrode is not specifically limited, For example, it can be set as about 50-500 nm. After forming a layer such as a TiAlN (titanium aluminum nitride) film, an Ir film, an IrO (iridium oxide) film, or a ZrO ₂ (zirconium oxide) film on the diaphragm 16 as an adhesion layer or a diffusion prevention layer, The electrode 20 may be formed.

  Next, a precursor solution containing at least a lead salt, a zirconium salt, and a titanium salt is applied to the surface of the lower electrode 20. The metal molar concentration ratio in the precursor solution can be determined according to the composition of the perovskite oxide to be formed. The molar ratio of the A site element and the B site element in the above formulas (1) to (4) is 1: 1 as a standard, but may be deviated from 1: 1 within the range in which the perovskite oxide is formed.

Then, as shown in FIG. 3A, the applied precursor solution is crystallized to form the piezoelectric layer 30. As an example, preferably, the precursor solution is heated and dried at about 140 to 190 ° C., and then degreased by heating at about 300 to 400 ° C., for example, heated at about 550 to 850 ° C. To crystallize.
In addition, in order to thicken the piezoelectric layer 30, the combination of the coating process, the drying process, the degreasing process, and the baking process may be performed a plurality of times. In order to reduce the firing process, the firing process may be performed after the combination of the coating process, the drying process, and the degreasing process is performed a plurality of times. Further, a combination of these steps may be performed a plurality of times. In the example shown in FIG. 3B, after the piezoelectric layer 30 is formed on the lower electrode film 20, the lower electrode 20 and the piezoelectric layer 30 are patterned in regions facing the pressure generation chambers 12.

  In addition, as a heating apparatus for performing the above-described drying and degreasing, a hot plate, an infrared lamp annealing apparatus that heats by irradiation with an infrared lamp, or the like can be used. An infrared lamp annealing device or the like can be used as the heating device for performing the firing. Preferably, the temperature rising rate may be made relatively fast by using an RTA (Rapid Thermal Annealing) method or the like.

  On the piezoelectric layer 30 thus formed, as shown in FIG. 3B, the upper electrode 40 is formed by sputtering or the like. As the metal constituting the upper electrode, one or more kinds of metals such as Ir, Au, and Pt can be used. Moreover, the thickness of the upper electrode is not particularly limited, but can be, for example, about 10 to 200 nm. In the example shown in FIG. 3C, after forming the upper electrode film, the upper electrode film is patterned in a region facing each pressure generating chamber 12 to form the piezoelectric element 3.

  Subsequently, the lead electrode 45 is formed. For example, as shown in FIG. 3C, a lead layer is formed by forming a gold layer over the front surface of the flow path forming substrate 10 and then patterning each piezoelectric element 3 through a mask pattern made of a resist or the like. 45 is provided (FIG. 4A). A lead electrode 45 extending from the vicinity of the end on the ink supply path 14 side to the diaphragm 16 is connected to each lower electrode 20 shown in FIG.

  The lower electrode 20, the upper electrode 40, and the lead electrode 45 can be formed by a sputtering method such as a DC (direct current) magnetron sputtering method. The thickness of each layer can be adjusted by changing the voltage applied to the sputtering apparatus and the sputtering processing time.

  Then, as shown in FIG. 4A, a protective film 80 is formed so as to cover the boundary between the active part and the inactive part of the piezoelectric layer 30. As a method for forming the protective film 80, for example, first, a polyimide film is formed on the piezoelectric layer 30 including the upper electrode 40. Next, for example, a polyimide layer is patterned through a mask pattern made of resist or the like, and dry etching is performed to form the protective film 80. Further, if a photosensitive polyimide is used as the protective film 80, it may be patterned by exposing and developing using a mask pattern after film formation.

  Thus, the piezoelectric element 3 having the piezoelectric layer 30 and the electrodes (20, 40) is formed, and a piezoelectric actuator including the piezoelectric element 3 and the diaphragm 16 is formed.

  Next, as shown in FIG. 4B, the protective substrate 50 on which the piezoelectric element holding portion 52 and the like are formed in advance is bonded onto the flow path forming substrate 10 with an adhesive, for example. As the protective substrate 50, for example, a silicon single crystal substrate, glass, a ceramic material, or the like can be used. Although the thickness of the protective substrate 50 is not specifically limited, For example, it can be set as about 400 micrometers. The reservoir portion 51 penetrating in the thickness direction of the protective substrate 50 constitutes the reservoir 9 serving as a common ink chamber together with the communication path 13. The piezoelectric element holding portion 52 provided in the region facing the piezoelectric element 3 has a space that does not hinder the movement of the piezoelectric element 3. In the through hole 53 of the protective substrate 50, the vicinity of the end portion of the lead electrode 45 drawn from each piezoelectric element 3 is exposed.

Next, after polishing the silicon substrate 15 to a certain thickness, the silicon substrate 15 is further etched to a predetermined thickness (for example, about 70 μm) by wet etching with hydrofluoric acid. Next, as shown in FIG. 4B, a mask film 17 is newly formed on the silicon substrate 15 and patterned into a predetermined shape. Silicon nitride (SiN) or the like can be used for the mask film 17. Next, the silicon substrate 15 is anisotropically etched (wet etching) using an alkaline solution such as KOH. As a result, a plurality of liquid flow paths including the pressure generating chambers 12 and the narrow ink supply paths 14 defined by the plurality of partition walls 11 (see FIG. 2), and a common liquid flow path connected to each ink supply path 14. The communication path 13 is formed. The liquid flow paths (12, 14) are arranged in the width direction D1, which is the short direction of the pressure generating chamber 12.
The pressure generation chamber 12 may be formed before the piezoelectric element 3 is formed.

  Next, as shown in FIG. 4C, the nozzle plate 70 is bonded to the surface of the silicon substrate 15 opposite to the protective substrate 50. The nozzle plate 70 can be made of glass ceramics, silicon single crystal substrate, stainless steel, or the like, and is fixed to the opening surface side of the flow path forming substrate 10. For this fixation, an adhesive, a heat welding film, or the like can be used. The nozzle plate 70 is formed with nozzle openings 71 communicating with the vicinity of the end of each pressure generating chamber 12 on the side opposite to the ink supply path 14. Therefore, the pressure generation chamber 12 communicates with the nozzle opening 71 that discharges the liquid.

  Next, the compliance substrate 60 having the sealing film 61 and the fixing plate 62 is bonded onto the protective substrate 50. The sealing film 61 is made of, for example, a material having low rigidity such as a polyphenylene sulfide (PPS) film having a thickness of about 6 μm, and seals one surface of the reservoir unit 51. The fixed plate 62 is made of a hard material such as a metal such as stainless steel (SUS) having a thickness of about 30 μm, for example, and an area facing the reservoir 9 is an opening 63.

A driving circuit 65 for driving the piezoelectric elements 3 arranged in parallel is fixed on the protective substrate 50. For the drive circuit 65, a circuit board, a semiconductor integrated circuit (IC), or the like can be used. The drive circuit 65 and the lead electrode 45 are electrically connected via the connection wiring 66. As the connection wiring 66, a conductive wire such as a bonding wire can be used.
Thus, the recording head 1 is manufactured.

  The recording head 1 takes in ink from an ink introduction port connected to an external ink supply unit (not shown), and fills the interior from the reservoir 9 to the nozzle opening 71 with ink. When a voltage is applied between the lower electrode 20 and the upper electrode 40 for each pressure generating chamber 12 in accordance with a recording signal from the drive circuit 65, the deformation of the piezoelectric layer 30, the lower electrode 20 and the diaphragm 16 causes deformation from the nozzle opening 71. Ink droplets are ejected.

(3) Liquid ejecting apparatus:
FIG. 5 shows the appearance of a recording apparatus (liquid ejecting apparatus) 200 having the recording head 1 described above. When the recording head 1 is incorporated in the recording head units 211 and 212, the recording apparatus 200 can be manufactured. In the recording apparatus 200 shown in FIG. 5, the recording head 1 is provided in each of the recording head units 211 and 212, and ink cartridges 221 and 222 as external ink supply units are detachably provided. A carriage 203 on which the recording head units 211 and 212 are mounted is provided so as to be able to reciprocate along a carriage shaft 205 attached to the apparatus main body 204. When the driving force of the driving motor 206 is transmitted to the carriage 203 via a plurality of gears and a timing belt 207 (not shown), the carriage 203 moves along the carriage shaft 205. A recording sheet 290 fed by a sheet feeding roller (not shown) is conveyed onto the platen 208 and printed by ink supplied from the ink cartridges 221 and 222 and ejected from the recording head 1.

(4) Example:
Hereinafter, although an example is shown, the present invention is not limited by the following examples.

Here, an ink jet recording head of Example 1-3 below was manufactured, and a DC current test was performed on the piezoelectric element.
[Example 1]
An ink jet recording head having a protective film made of polyimide having a film thickness of 0.7 μm so as to cover the end of the active part (near the boundary between the active part and the inactive part) in the piezoelectric element was taken as Example 1. The Young's modulus E of this polyimide is 3.0 GPa.
[Example 2]
Example 2 was an ink jet recording head similar to Example 1 except for a protective film made of polyimide having a film thickness of 2.6 μm.
[Example 3]
Example 3 was an ink jet recording head similar to Example 1 except for a protective film made of an adhesive having a thickness of 3.0 μm. The Young's modulus E of the adhesive is 3.0 Gpa.

Table 1 shows each condition (film thickness t, Young's modulus E, product of Young's modulus and film thickness: E × t) in Examples 1 to 4 when this withstand voltage evaluation is performed, and the end of the active portion Shows the state of burnout. That is, “◯” indicates that no burning occurred, and “Δ” indicates that the burning is reduced as compared with the case where no protective film is formed.

As shown in Table 1, in Examples 2 and 3 in which the product of the Young's modulus E and the film thickness t is 7800 (Pa · m) or more, no burning at the end of the active portion 3a was observed. In Example 1 where the product of Young's modulus E and film thickness t was 2100 (Pa · m), it was observed that burning at the end of the active portion 3a was reduced.
From the above, it was found that burning was suppressed by forming the protective film 80 so as to cover the boundary between the active part 3a and the inactive part 3b. Moreover, if the product of the Young's modulus E and the film thickness t is 2000 (Pa · m) or more, the burnout can be reduced. More preferably, the product of the Young's modulus E and the film thickness t is 7800 (Pa · m) or more. It was found that burning would not occur if there was.

(5) Second embodiment:
Hereinafter, a case where the protective film 80 is an inorganic protective film will be described as a second embodiment. 6A to 6C are cross-sectional views for explaining the manufacturing process of the recording head 1. 7A to 7C are cross-sectional views for explaining the manufacturing process of the recording head 1.

  The protective film 80 according to the second embodiment is the same as that of the first embodiment in the configuration formed so as to cover the boundary between the active part 3a and the inactive part 3b in the piezoelectric layer 30. On the other hand, the order of the steps for forming the protective film 80 is different from that of the first embodiment in that it is immediately after the step for forming the upper electrode 40. This is because the protective film 80 is formed of an organic material in the first embodiment, whereas the protective film 80 is formed of an inorganic material in the second embodiment.

As an example, the protective film 80 according to the second embodiment is formed of, for example, aluminum oxide (Al ₂ O ₃ ) as an inorganic protective film. Then, the case of forming the protective film 80 with _Al 2 _{O 3} is preferably be a 25nm or more thickness.

A manufacturing method of the above-described piezoelectric element 3 and a recording head (liquid ejecting head) 1 including the piezoelectric element 3 will be described with reference to FIGS. Here, the case where Al ₂ O ₃ (inorganic protective film) is used as the protective film 80 will be described as an example. The conditions for configuring the recording head 1 are the same as those in the first embodiment.

First, as in the first embodiment, the flow path forming substrate 10 is formed from a silicon single crystal substrate or the like. Then, an elastic film (vibrating plate 16) made of silicon dioxide (SiO ₂ ) is integrally formed by thermally oxidizing the silicon substrate 15 with a diffusion path of about 1100 ° C.

  Next, as shown in FIG. 6A, the lower electrode 20 is formed on the elastic film 16 by sputtering or the like. Then, as shown in FIG. 6B, the applied precursor solution is crystallized to form the piezoelectric layer 30. On the piezoelectric layer 30 thus formed, as shown in FIG. 6B, the upper electrode 40 is formed by sputtering or the like.

Then, a protective film 80 is formed so as to cover the boundary between the active portion 3a and the inactive portion 3b of the piezoelectric layer 30. As a method of forming the protective film 80, as shown in FIG. 6C, first, an Al ₂ O ₃ film is formed on the piezoelectric layer 30 including the upper electrode 40. Next, for example, a layer of aluminum oxide is patterned through a mask pattern made of a resist or the like, and further, a protective film 80 is formed by dry etching.

  Subsequently, as shown in FIG. 7A, the lead electrode 45 is formed on the protective film 80. For example, the lead electrode 45 is provided by forming a gold layer over the front surface of the flow path forming substrate 10 and then patterning each piezoelectric element 3 through a mask pattern made of a resist or the like. That is, in the second embodiment, after the formation of the protective film 80, patterning for forming the lead electrode 45 is performed. Therefore, the piezoelectric layer 30 can be protected from a chemical used when the lead electrode 45 is patterned by the protective film 80.

  Then, as shown in FIG. 7B, the protective substrate 50 on which the piezoelectric element holding portion 52 and the like are formed in advance is bonded onto the flow path forming substrate 10 with, for example, an adhesive. Next, a mask film 17 is newly formed on the silicon substrate 15 and patterned into a predetermined shape. Then, as shown in FIG. 7C, the nozzle plate 70 is bonded to the surface of the silicon substrate 15 opposite to the protective substrate 50. Next, the compliance substrate 60 having the sealing film 61 and the fixing plate 62 is bonded onto the protective substrate 50 and divided into a predetermined chip size. Thus, the recording head 1 is formed.

(6) Examples Hereinafter, examples according to the second embodiment will be described, but the present invention is not limited to the following examples.

Here, an ink jet recording head in Example 4 below was manufactured, and a DC current test was performed on the piezoelectric element.
[Example 4]
An example of an ink jet recording head having a protective film made of Al ₂ O ₃ with a film thickness of 90 nm so as to cover the end of the active part of the piezoelectric layer constituting the piezoelectric element (near the boundary between the active part and the inactive part) It was set to 4. This Young's modulus E of Al ₂ O ₃ is 200 GPa.
[Example 5]
An ink jet recording head similar to that of Example 4 was used in Example 5 except for a protective film made of Al ₂ O _{3 having a} thickness of 45 nm.

Table 2 shows the conditions (film thickness t, Young's modulus E, product of Young's modulus and film thickness: E × t) in Examples 4 to 5 when this withstand voltage evaluation is performed, and the end of the active portion. Indicates the presence or absence of burning.

As shown in Table 2, it can be seen that also in the second embodiment, the burning of the piezoelectric layer is reduced. That is, in the protective film in which the product of the Young's modulus E and the film thickness t is 4500 (Pa · m) or more, no burning at the end of the active part was observed.
From the first embodiment and the second embodiment, if the product of the Young's modulus E and the film thickness t is 5000 (Pa · m) or more, burning at the end of the active portion can be suppressed.
For this reason, it was found that burning was suppressed by forming a protective film made of an inorganic material at the boundary between the active part and the inactive part.

(7) Application and others:
Various modifications can be considered for the present invention.
In the above-described embodiment, an individual piezoelectric body is provided for each pressure generation chamber. However, a common piezoelectric body may be provided for a plurality of pressure generation chambers, and an individual electrode may be provided for each pressure generation chamber.
In the above-described embodiment, a part of the reservoir is formed on the flow path forming substrate. However, the reservoir may be formed on a member different from the flow path forming substrate.
In the above-described embodiment, the upper side of the piezoelectric element is covered with the piezoelectric element holding unit, but the upper side of the piezoelectric element can be opened to the atmosphere.
In the embodiment described above, the pressure generating chamber is provided on the opposite side of the piezoelectric element with the diaphragm interposed therebetween, but it is also possible to provide the pressure generating chamber on the piezoelectric element side. For example, if a space surrounded by fixed plates and piezoelectric elements is formed, this space can be used as a pressure generating chamber.

  The liquid ejected from the fluid ejecting head may be any material that can be ejected from the liquid ejecting head, such as a solution in which a dye or the like is dissolved in a solvent, or a sol in which solid particles such as pigments or metal particles are dispersed in a dispersion medium. Is included. Such fluids include ink, liquid crystal, and the like. The liquid ejecting head can be mounted on an image recording apparatus such as a printer, a color filter manufacturing apparatus such as a liquid crystal display, an electrode manufacturing apparatus such as an organic EL display, a biochip manufacturing apparatus, and the like.

As described above, according to the present invention, a technique for improving the performance of at least a piezoelectric element having a piezoelectric layer, a liquid ejecting head, and a liquid ejecting apparatus can be provided according to various aspects.
In addition, the configurations disclosed in the embodiments and modifications described above are mutually replaced, the combinations are changed, the known technology, and the configurations disclosed in the embodiments and modifications described above are mutually connected. It is possible to implement a configuration in which replacement or combination is changed. The present invention includes these configurations and the like.

DESCRIPTION OF SYMBOLS 1 ... Recording head, 3 ... Piezoelectric element, 9 ... Reservoir, 10 ... Channel formation substrate, 11 ... Partition, 12 ... Pressure generating chamber, 15 ... Silicon substrate, 16 ... Vibration plate, 20 ... Lower electrode, 30 ... Piezoelectric body Layer, 40 ... upper electrode, 45 ... lead electrode, 50 ... protective substrate, 60 ... compliance substrate, 70 ... nozzle plate

Claims (10)

And the pressure generating chamber,
An elastic membrane that seals at least a portion of the pressure generating chamber;
A first electrode formed on the opposite side of the elastic membrane from the pressure generating chamber;
A piezoelectric layer formed on the opposite side of the first electrode from the pressure generating chamber;
A second electrode formed on the opposite side of the piezoelectric layer from the pressure generating chamber;
A protective film covering a boundary between the second electrode and the piezoelectric layer,
In a direction perpendicular to the thickness direction of the elastic film, the end of the piezoelectric layer is located outside the end of the second electrode ,
The protective film is an organic protective film,
The protective film is a liquid jet head having a thickness of 0.7 μm or more and 3.0 μm or less .   The protective film has a thickness of 2.6 μm to 3.0 μm.
  The liquid jet head according to claim 1.   A pressure generating chamber;
  An elastic membrane that seals at least a portion of the pressure generating chamber;
  A first electrode formed on the opposite side of the elastic membrane from the pressure generating chamber;
  A piezoelectric layer formed on the opposite side of the first electrode from the pressure generating chamber;
  A second electrode formed on the opposite side of the piezoelectric layer from the pressure generating chamber;
  A protective film covering a boundary between the second electrode and the piezoelectric layer,
  In a direction perpendicular to the thickness direction of the elastic film, the end of the piezoelectric layer is located outside the end of the second electrode,
  The protective film is an inorganic protective film,
  The protective film has a thickness of 25 nm to 90 nm.
  Liquid jet head.   The second electrode has a thickness of 10 nm to 200 nm.
  The liquid jet head according to claim 1.   The first electrode has a thickness of 50 nm to 500 nm.
  The liquid jet head according to claim 1.   The elastic membrane has a thickness of 0.5 μm or more and 2 μm or less.
  The liquid jet head according to claim 1. A first electrode overlapping the space;
A piezoelectric layer formed on the opposite side of the space of the first electrode;
A second electrode formed on the opposite side of the piezoelectric layer from the first electrode;
A protective film covering a boundary between the second electrode and the piezoelectric layer,
In the direction from the space to the outside, the end of the piezoelectric layer is located outside the end of the second electrode,
The protective film is an organic protective film,
The protective film is a piezoelectric element having a thickness of 0.7 μm or more and 3.0 μm or less .   A first electrode overlapping the space;
  A piezoelectric layer formed on the opposite side of the space of the first electrode;
  A second electrode formed on the opposite side of the piezoelectric layer from the first electrode;
  A protective film covering a boundary between the second electrode and the piezoelectric layer,
  In the direction from the space to the outside, the end of the piezoelectric layer is located outside the end of the second electrode,
  The protective film is an inorganic protective film,
  The protective film has a thickness of 25 nm to 90 nm.
  Piezoelectric element. Forming an elastic membrane that seals at least a portion of the pressure generating chamber;
Forming a first electrode on the opposite side of the elastic membrane from the pressure generating chamber;
Forming a piezoelectric layer on the opposite side of the first electrode from the pressure generating chamber;
In the first direction orthogonal to the thickness direction of the elastic film, the end of the second electrode is positioned closer to the center of the pressure generating chamber than the end of the piezoelectric layer. Forming the second electrode on the opposite side of the pressure generating chamber;
An organic protective film that covers a boundary between the second electrode and the piezoelectric layer is formed to a thickness of 0.7 μm to 3.0 μm .   Forming an elastic membrane that seals at least a portion of the pressure generating chamber;
  Forming a first electrode on the opposite side of the elastic membrane from the pressure generating chamber;
  Forming a piezoelectric layer on the opposite side of the first electrode from the pressure generating chamber;
  In the first direction orthogonal to the thickness direction of the elastic film, the end of the second electrode is positioned closer to the center of the pressure generating chamber than the end of the piezoelectric layer. Forming the second electrode on the opposite side of the pressure generating chamber;
  An inorganic protective film that covers a boundary between the second electrode and the piezoelectric layer is formed to a thickness of 25 nm to 90 nm.
  A method for manufacturing a liquid jet head.

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