JP2004104106A - Piezoelectric actuator, method of manufacturing the same, ink jet head, and ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve lower permittivity over a whole piezoelectric layer without reducing the piezoelectric characteristic of a piezoelectric layer of a displaced region in a piezoelectric actuator. <P>SOLUTION: The piezoelectric actuator has a diaphragm 26, a common electrode 27 formed on the diaphragm 26, a piezoelectric body 29 formed on the common electrode 27, a crystal control layer 28 formed on the piezoelectric body 29, an individual electrode 33 formed on the crystal control layer 28, and electrode wiring 34 formed on the piezoelectric body 29. The crystal control layer 28 is formed on a part corresponding to the displaced region. A piezoelectric body 29a in the displaced region has the crystallinity of a perovskite structure. A piezoelectric body 29b in a wiring region has the crystallinity of a pyrochlore structure. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a piezoelectric actuator, a method for manufacturing the same, an ink jet head, and an ink jet recording apparatus.

イ ン ク ジ ェ ッ ト Conventionally, there has been known an ink jet head that performs recording using a piezoelectric effect of a piezoelectric body.

This type of ink jet head has a piezoelectric actuator in which a common electrode, a piezoelectric body, and an individual electrode are sequentially laminated, and an ink flow path forming substrate in which a pressure chamber is formed. A vibration plate is provided on one surface of the piezoelectric actuator. This diaphragm is adhered on the ink flow path forming substrate with an adhesive. When the ink is ejected, a voltage is applied to the common electrode and the individual electrodes, whereby the piezoelectric body expands and contracts. When the expansion and contraction are restricted by the diaphragm, the piezoelectric actuator bends and deforms in the laminating direction. The volume in the pressure chamber changes due to the bending deformation, and the ink in the pressure chamber is ejected from the nozzle.

By the way, the above-mentioned piezoelectric actuator is composed of a displacement area and a wiring area. The displacement area is an area located at a portion corresponding to the pressure chamber. Further, the wiring region is a region located in a portion other than the displacement region, and is a region where an electrode wiring for connecting an individual electrode and a drive circuit for applying a voltage to both electrodes is provided.

Here, in the above-described piezoelectric actuator, the same piezoelectric material is generally laminated over the displacement region and the wiring region from the viewpoint of facilitating the manufacture of the ink jet head and the like. In addition, the dielectric constant tends to be high in order to obtain high piezoelectric characteristics, and the piezoelectric material in the displacement region is required to have high piezoelectric characteristics from the viewpoint of improving the ink discharging performance. The piezoelectric body having a high dielectric constant is laminated over the entire surface. However, in this case, not only the piezoelectric material in the displacement region, but also the dielectric constant of the piezoelectric material in the wiring region where high piezoelectric characteristics are not required are increased. At this time, since the capacitance between the two electrodes in the wiring area increases, the voltage that must be applied between the two electrodes when ink is ejected increases. As a result, an excessive load is applied to the drive circuit.

Therefore, in order to solve the above problem, it is conceivable to stack a piezoelectric body having a low dielectric constant over the displacement region and the wiring region. However, in this case, the dielectric constant of not only the piezoelectric body in the wiring region but also the piezoelectric body in the displacement region becomes small. At this time, the piezoelectric characteristics of the piezoelectric body in the displacement region deteriorate. This is not preferable from the viewpoint of improving the performance of ejecting ink.

Therefore, as disclosed in Patent Document 1, there has been proposed an ink jet head in which a piezoelectric film having a lower dielectric constant than the above-mentioned piezoelectric body is provided between the piezoelectric body and the upper electrode in the wiring region. Thus, the dielectric constant of the entire piezoelectric body can be reduced while preventing the piezoelectric characteristics of the piezoelectric body in the displacement region from being deteriorated.
JP-A-9-156099

However, in the above-described ink jet head, a step is generated between the upper electrode in the displacement region and the upper electrode in the wiring region, so that the upper electrode is easily broken. Further, since the piezoelectric characteristics of the piezoelectric body in the wiring region are different from the piezoelectric characteristics of the piezoelectric film, the piezoelectric body and the film are easily separated from each other.

Therefore, there has been a demand for the development of a technique capable of preventing a reduction in the piezoelectric characteristics of the piezoelectric body in the displacement region and reducing the dielectric constant of the entire piezoelectric body without causing the above problem.

The present invention has been made in view of such a point, and an object of the present invention is to reduce the dielectric constant of the entire piezoelectric layer in a piezoelectric actuator without lowering the piezoelectric characteristics of the piezoelectric layer in a displacement region. It is in.

According to a first aspect of the present invention, there is provided a piezoelectric actuator including a lower electrode, a piezoelectric layer formed on the lower electrode, and an upper electrode formed on the piezoelectric layer and applying a voltage to the piezoelectric layer together with the lower electrode. Wherein the piezoelectric layer is composed of a piezoelectric layer in a displacement region and a piezoelectric layer in a wiring region located in a portion other than the displacement region, and a dielectric constant of the piezoelectric layer in the wiring region is It is lower than the dielectric constant of the piezoelectric layer.

According to the present invention, the dielectric constant of the entire piezoelectric layer can be reduced by lowering only the dielectric constant of the wiring region without deteriorating the piezoelectric characteristics of the piezoelectric layer in the displacement region.

According to a second aspect of the present invention, there is provided a piezoelectric actuator including a lower electrode, a piezoelectric layer formed on the lower electrode, and an upper electrode formed on the piezoelectric layer and applying a voltage to the piezoelectric layer together with the lower electrode. Wherein the piezoelectric layer comprises a piezoelectric layer in a displacement region and a piezoelectric layer in a wiring region located in a portion other than the displacement region, and the piezoelectric layer in the displacement region has a perovskite structure. The piezoelectric layer in the wiring region has a pyrochlore structure.

Thereby, while the piezoelectric layer in the displacement region has a perovskite structure, the piezoelectric layer in the wiring region has a pyrochlore structure, the piezoelectric layer in the displacement region has ferroelectricity, and the piezoelectric layer in the wiring region has The dielectric constant is lower than that of the piezoelectric layer in the displacement region. Therefore, according to the present invention, the dielectric constant of the entire piezoelectric layer can be further reduced without lowering the piezoelectric characteristics of the piezoelectric layer in the displacement region.

According to a third aspect, in the second aspect, the crystal formed of lanthanum lead titanate is provided on a surface of the piezoelectric layer in the displacement region on the upper electrode side or on a surface of the piezoelectric layer in the displacement region on the lower electrode side. A control layer is formed.

As a result, the crystal control layer is formed on the upper electrode side surface of the piezoelectric layer in the displacement region or on the lower electrode side surface of the piezoelectric layer in the displacement region. The piezoelectric layer can be grown in a perovskite structure. Therefore, according to the configuration of the present invention, the piezoelectric layer in the displacement region can be grown with a perovskite structure.

In a fourth aspect based on the third aspect, the crystal control layer is formed of one of Pt, a Pt-Ti alloy, and an Ir-Ti alloy on a surface opposite to the piezoelectric layer. An active layer is formed.

Thus, on the surface of the crystal control layer opposite to the piezoelectric layer, an active layer having a function of causing lead lanthanum titanate to act as a crystal control layer is formed. Will function more actively. Therefore, when forming the piezoelectric layer, the piezoelectric layer in the displacement region can be reliably grown with the perovskite structure. Therefore, according to the configuration of the present invention, the piezoelectric layer in the displacement region can be reliably grown with the perovskite structure.

In a fifth aspect based on any one of the first to fourth aspects, the piezoelectric layer is made of lead titanate, lead zirconate titanate, lead zirconate, lead lanthanum titanate, lead lanthanum zirconate titanate. And a piezoelectric ceramic containing at least one of lead magnesium niobate.

According to the present invention, since the piezoelectric layer is made of the above-described piezoelectric ceramics having ferroelectricity, it is possible to obtain a piezoelectric layer in the displacement region having high piezoelectric characteristics.

A sixth invention is an ink-jet head including any one of the first to fifth inventions.

A seventh invention is an ink jet recording apparatus provided with the sixth invention.

According to an eighth aspect of the present invention, there is provided a process of forming an upper electrode made of any one of Pt, Pt-Ti alloy, and Ir-Ti alloy on a substrate, and forming a lead lanthanum titanate layer on the upper electrode. Forming a piezoelectric layer on the upper electrode and the individualized lead lanthanum titanate layer; forming a piezoelectric layer on the upper electrode and on the individualized lead lanthanum titanate layer; Forming a lower electrode on the layer.

According to a ninth invention, a step of forming an upper electrode made of any one of Pt, a Pt-Ti alloy, and an Ir-Ti alloy on a substrate, and a portion corresponding to a displacement region in the upper electrode are separately performed. Forming a lead lanthanum titanate layer on the substrate and the individualized upper electrode; forming a piezoelectric layer on the lead lanthanum titanate layer; and forming a lower layer on the piezoelectric layer. And a step of forming an electrode.

According to a tenth aspect of the present invention, there is provided a process for forming a diaphragm on a substrate and forming a lower electrode on the diaphragm or forming a lower electrode also serving as a diaphragm on the substrate; Forming an active layer made of any one of Pt-Ti alloy and Ir-Ti alloy, forming a lead lanthanum titanate layer on the active layer, and forming a lead lanthanum titanate layer on the active layer. A step of individualizing a portion corresponding to the displacement region, a step of forming a piezoelectric layer on the active layer and the individualized lanthanum lead titanate layer, and a step of forming an upper electrode on the piezoelectric layer; This is a method for manufacturing a piezoelectric actuator including:

An eleventh invention includes a step of forming a diaphragm on a substrate and a step of forming a lower electrode on the diaphragm or a step of forming a lower electrode also serving as a diaphragm on the substrate, and a step of forming Pt on the lower electrode. Forming an active layer made of any one of a Pt-Ti alloy and an Ir-Ti alloy, singulating a portion corresponding to a displacement region in the active layer, Forming a lead lanthanum titanate layer on the activated active layer, forming a piezoelectric layer on the lead lanthanum titanate layer, and forming an upper electrode on the piezoelectric layer. This is a method for manufacturing a piezoelectric actuator.

According to the present invention, the piezoelectric layer in the displacement region maintains a high dielectric constant in order to maintain high piezoelectric characteristics, and the dielectric constant of the piezoelectric layer in the wiring region that does not require the piezoelectric characteristics is reduced, so that the displacement characteristics of the actuator are reduced. Without reducing the dielectric constant of the entire piezoelectric layer. Therefore, it is possible to achieve both reduction of the load on the drive circuit and improvement of the ejection performance.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
As shown in FIG. 1, an ink jet head 1 according to the present embodiment is incorporated in an ink jet printer 3 as an ink jet type recording apparatus, and performs recording by causing ejected ink droplets to land on a recording medium 5 such as paper. is there.

The inkjet head 1 is mounted on a carriage 9 that reciprocates along the carriage shaft 7 and reciprocates in the main scanning direction X together with the carriage 9. The roller 10 is configured to convey the recording medium 5 in the sub-scanning direction Y each time the carriage 9 moves by one scan in the main scanning direction X.

As shown in FIG. 2, the inkjet head 1 includes a head body 17 in which a common ink chamber 11, a plurality of pressure chambers 19, and a plurality of nozzles 15 are formed, and a piezoelectric body that applies pressure to the ink in the pressure chamber 19. An actuator 21 is provided.

The pressure chambers 19 of the head body 17 are arranged at predetermined intervals along the sub-scanning direction Y. The pressure chamber 19 is formed in a substantially rectangular shape whose opening cross section (XY cross section) is elongated in the main scanning direction X. An ink supply port 23 connected to the common ink chamber 11 is formed at one longitudinal end (right end in FIG. 2) at the bottom of the pressure chamber 19, and a nozzle 15 is provided at the other end (left end in FIG. 2). Is formed.

As shown in FIGS. 2 to 5, the piezoelectric actuator 21 includes a vibration plate 26 made of 2 μm Cr, a common electrode 27 formed on the vibration plate 26 and made of 5.5 μm thick Cu, and a common electrode 27. A piezoelectric body 29 made of Pb (Zr, Ti) O ₃ (PZT) having a thickness of 3 μm formed thereon and lead lanthanum titanate (PLT, (Pb) having a thickness of 0.05 μm formed on the piezoelectric body 29 , La) TiO ₃ ), an individual electrode 33 of Pt having a thickness of 0.2 μm formed on the crystal control layer 28, and an individual electrode 33 formed on the piezoelectric body 29 and formed on the individual electrode 33. An electrode wiring 34 made of Pt and having a thickness of 0.2 μm (electrode wiring is omitted in FIG. 2) is provided. In the present invention, the lower electrode is constituted by the common electrode 27, the piezoelectric layer is constituted by the piezoelectric body 29, and the upper electrode is constituted by the individual electrode 33 and the electrode wiring.

Here, a portion of the piezoelectric actuator 21 corresponding to each pressure chamber 19 (a portion directly above each pressure chamber 19) is referred to as a displacement region, and a portion of the piezoelectric actuator 21 other than the displacement region is referred to as a wiring region.

(4) The crystal control layer 28 and the individual electrode 33 are formed so as to be located at a portion corresponding to the displacement region. The crystal control layer 28 is for growing the piezoelectric body 29 formed on the crystal control layer 28 in a perovskite structure when a piezoelectric body 29 described later is formed.

By the way, Pt has a function of causing lead lanthanum titanate formed on Pt to act as a crystal control layer. Here, since the individual electrode 33 is made of Pt, it also has a role of causing the above-described lead lanthanum titanate to act as the crystal control layer 28. The active layer in the present invention is constituted by the individual electrodes 33.

The crystallinity of the piezoelectric body 29a in the displacement region has a perovskite structure. The perovskite structure is a cubic crystal structure represented by ABO ₃ (where A includes Pb and B includes Zr and Ti). The piezoelectric body 29a having a perovskite structure is a ferroelectric. On the other hand, the crystallinity of the piezoelectric body 29b in the wiring region has a pyrochlore structure. The pyrochlore structure is a crystal structure represented by A ₂ B ₂ O ₇ (where A includes Pb and B includes Zr and Ti). As described below, the piezoelectric body 29b having a pyrochlore structure has a lower dielectric constant than the piezoelectric body 29a having a perovskite structure.

FIG. 6 shows a film thickness ratio and a relative dielectric constant of a two-layer film in which a piezoelectric material having a perovskite structure (hereinafter referred to as a perovskite layer) and a piezoelectric material having a pyrochlore structure (hereinafter referred to as a pyrochlore layer) are stacked. Shows the relationship with The total thickness of the two-layer film is 3.0 μm. For example, when the thickness of the piezoelectric body having the perovskite structure is 2.1 μm, the thickness of the piezoelectric body having the pyrochlore structure is 0.9 μm. As can be seen from FIG. 6, the relative dielectric constant increases as the thickness of the piezoelectric body of the perovskite structure increases, and the relative dielectric constant decreases as the thickness of the piezoelectric body of the pyrochlore structure increases. I understand.

(6) According to FIG. 6, when the thickness of the perovskite layer is 2.1 μm and the thickness of the pyrochlore layer is 0.9 μm, the relative dielectric constant is 90. When converted from the value of the relative dielectric constant, the dielectric constant of the 3 μm-thick pyrochlore layer is 32.9 (when the thickness of the perovskite layer and the pyrochlore layer is 1.5 μm, the relative dielectric constant is When converted from the value of the relative dielectric constant, the dielectric constant of the 3 μm-thick pyrochlore layer is 32.8). Further, from FIG. 6, the dielectric constant of the perovskite layer having a thickness of 3 μm is 350 (300 to 450). As described above, when the piezoelectric body in the wiring region is formed of the pyrochlore layer, the capacitance can be reduced to about 1/10 as compared with the case where the piezoelectric body in the wiring region is the perovskite layer.

Here, by forming a PI (polyimide) film having a dielectric constant of 3.55 as a low dielectric constant film on a PZT film having a perovskite structure having a thickness of 3 μm as a piezoelectric material in the wiring region, the capacitance is reduced. Consider reducing it to about 1/10 (refer to the above-mentioned Japanese Patent Application Laid-Open No. 9-156099). At this time, in calculation, the capacitance can be reduced to 1/10 by providing a PI film having a thickness of 0.274 μm. However, it is very difficult to form a PI film having a film thickness of 1 μm or less by coating film formation such as printing, and when the film thickness is 1 μm or less, its performance, ie, insulation Sex is not guaranteed. Therefore, in order to reduce the capacitance by forming the PI film, the thickness of the PI film must be 1 μm or more, and therefore, a step occurs in the piezoelectric body between the wiring region and the displacement region. , Causing a decrease in yield.

Also, when the SiO ₂ layer, TiO ₂ layer, or the like as the low dielectric constant film is formed by sputtering, CVD film formation, or the like in order to reduce the capacitance to about 1/10, the same reason as described above. As a result, the above-described steps are generated, and the yield is reduced. Furthermore, since fine patterning and a vacuum process are required at this time, the number of steps is increased, and the cost is increased.

On the other hand, in the present embodiment, the crystallinity of the piezoelectric body 29a in the displacement region has a perovskite structure and the crystallinity of the piezoelectric body 29b in the wiring region has a pyrochlore structure. The yield can be prevented from lowering due to disconnection, and the capacitance of the wiring region can be reduced to 1/10 at low cost.

The electrode wiring 34 is connected to one end of each individual electrode 33 and a voltage input terminal (not shown) for applying a voltage to each individual electrode 33.

(Method of manufacturing inkjet head)
Next, a method for manufacturing the inkjet head 1 will be described with reference to FIGS. The method of manufacturing the inkjet head 1 described below is called a transfer method.

First, as shown in FIG. 7A, an upper electrode 49 made of Pt is formed on an MgO substrate 47 by sputtering or vapor deposition. Next, as shown in FIG. 7B, a lead lanthanum titanate layer 30 is formed on the upper electrode 49 by sputtering or vapor deposition. Next, as shown in FIG. 7C, the crystal control layer 28 is formed by individualizing the lead lanthanum titanate layer 30 in the displacement region by edging or the like. Next, as shown in FIG. 7D, a piezoelectric body 29 made of Pb (Zr, Ti) O ₃ is formed on the crystal control layer 28 and the upper electrode 49 by sputtering or vapor deposition. Accordingly, the piezoelectric body 29a formed on the crystal control layer 28, that is, in the displacement region, grows in a perovskite structure. On the other hand, the piezoelectric body 29b formed on the upper electrode 49, that is, in the wiring region grows in a pyrochlore structure.

  Next, as shown in FIG. 8A, a common electrode 27 made of Cu is formed on the piezoelectric body 29 by sputtering or vapor deposition. Thereafter, the diaphragm 26 made of Cr is formed on the common electrode 27 by sputtering, vapor deposition, or the like. Next, as shown in FIG. 8B, the head body 17 in which the pressure chamber 19 is formed on the vibration plate 26 is electrodeposited. Next, as shown in FIG. 8C, the MgO substrate 47 is removed by etching or the like. Finally, as shown in FIG. 8D, the individual electrodes 33 and the electrode wirings 34 are formed by individualizing the upper electrodes 49 corresponding to the portions of the displacement area where the upper electrodes 49 and the electrode wirings 34 are to be formed by etching or the like. I do. At the same time, the piezoelectric bodies 29a in the displacement area are also individualized.

(Operation method of inkjet head)
Here, an operation method of the inkjet head according to the present embodiment will be described. First, a voltage is applied to the common electrode 27 and the individual electrodes 33. When a voltage is applied to both electrodes 27 and 33, piezoelectric body 29 expands and contracts. When the expansion and contraction are restricted by the vibration plate 26, the piezoelectric actuator 21 bends and deforms in the stacking direction. The volume in the pressure chamber 19 changes due to the bending deformation, and the ink in the pressure chamber 19 is ejected from the nozzle 15 through the ink flow path 25.

According to the present embodiment, since the crystal control layer 28 made of lead lanthanum titanate is laminated between the piezoelectric body 29a in the displacement area and the individual electrode 33, the displacement occurs during the formation of the piezoelectric body 29. The piezoelectric body 29a in the region can be grown with a perovskite structure. Therefore, according to the configuration of the present embodiment, the piezoelectric body 29a in the displacement region can be grown in a perovskite structure.

{Circle around (4)} Since the individual electrode 33 also has a function of causing the lead lanthanum titanate to act as the crystal control layer 28, the lead lanthanum titanate functions more actively as the crystal control layer 28. Therefore, according to the configuration of the present embodiment, the piezoelectric body 29a in the displacement region can be reliably grown in the perovskite structure when the piezoelectric body 29 is formed.

Also, since the piezoelectric body 29a in the displacement area has a perovskite structure, while the piezoelectric body 29b in the wiring area has a pyrochlore structure, the piezoelectric body 29a in the displacement area has ferroelectricity and the piezoelectric body 29b in the wiring area has a ferroelectric property. Has a lower dielectric constant than the piezoelectric body 29a in the displacement region. Therefore, the piezoelectric properties of the piezoelectric body 29a in the displacement region are enhanced, and the dielectric constant of the entire piezoelectric body 29 is reduced. Therefore, the dielectric constant of the entire piezoelectric body 29 can be reduced while preventing the piezoelectric characteristics of the piezoelectric body 29a in the displacement region from being lowered.

Further, since the piezoelectric body 29 is made of Pb (Zr, Ti) O ₃ having ferroelectricity, it is possible to obtain a piezoelectric body 29a having a high piezoelectric characteristic in the displacement region.

According to the present embodiment, the individual electrode 33 is made of Pt, but may be made of a Pt-Ti alloy or an Ir-Ti alloy.

(Embodiment 2)
The piezoelectric actuator according to the present embodiment is obtained by forming a crystal control layer on the upper electrode after individualizing the upper electrode, and has substantially the same configuration as the piezoelectric actuator of the first embodiment. Hereinafter, a configuration different from the first embodiment will be described.

As shown in FIG. 9, the piezoelectric actuator 21 includes a vibration plate 26 made of 2 μm Cr, a common electrode 27 made of 5.5 μm thick Cu formed on the vibration plate 26, and a common electrode 27 formed on the common electrode 27. A piezoelectric body 29 made of Pb (Zr, Ti) O ₃ having a thickness of 3 μm, a crystal control layer 28 made of lead lanthanum titanate having a thickness of 0.05 μm formed on the piezoelectric body 29, and a crystal control layer An individual electrode 33 made of Pt having a thickness of 0.2 μm formed on the crystal control layer 28 and an electrode wiring 34 made of Pt having a thickness of 0.2 μm connected to the individual electrode 33 and formed on the crystal control layer 28; have.

(Method of manufacturing inkjet head)
Next, a method of manufacturing the inkjet head 1 will be described with reference to FIGS. The method of manufacturing the inkjet head 1 described below is called a transfer method.

First, as shown in FIG. 10A, an upper electrode 49 made of Pt is formed on an MgO substrate 47. Next, as shown in FIG. 10B, the individual electrodes 33 are formed by individualizing the upper electrode 49 in the displacement region by etching or the like. Next, as shown in FIG. 10C, a crystal control layer 28 made of lead lanthanum titanate is formed on the individual electrodes 33 and the MgO substrate 47 by sputtering or vapor deposition. Next, as shown in FIG. 10D, a piezoelectric body 29 made of Pb (Zr, Ti) O ₃ is formed on the crystal control layer 28 by sputtering or vapor deposition. Accordingly, the piezoelectric body 29a formed on the crystal control layer 28 formed on the individual electrode 33, that is, in the displacement region grows in a perovskite structure. On the other hand, the piezoelectric body 29b formed on the crystal control layer 28 formed on the MgO substrate 47, that is, in the wiring region grows in a pyrochlore structure. The reason why the piezoelectric body 29b formed in the wiring region does not grow in the perovskite structure is that lanthanum lead titanate formed directly on the MgO substrate 47 cannot sufficiently function as the crystal control layer 28.

  Next, as shown in FIG. 10E, a common electrode 27 made of Cu is formed on the piezoelectric body 29 by sputtering or vapor deposition. Thereafter, the diaphragm 26 made of Cr is formed on the common electrode 27 by sputtering, vapor deposition, or the like. Next, as shown in FIG. 11A, the head body 17 having the pressure chamber formed on the vibration plate 26 is electrodeposited. Next, as shown in FIG. 11B, the MgO substrate 47 is removed by etching or the like. Next, as shown in FIG. 11C, a Pt layer is formed on the crystal control layer 28 in the wiring region, and thereafter, the Pt layer corresponding to the portion where the electrode wiring 34 is formed is individualized by etching or the like. Then, the electrode wiring 34 is formed. Finally, as shown in FIG. 11D, the individual electrodes 33 and the piezoelectric bodies 29 are individualized by etching or the like.

In this embodiment, the same effects as those of the first embodiment can be obtained.

(Embodiment 3)
The piezoelectric actuator according to the present embodiment is manufactured by a so-called direct construction method, and has substantially the same configuration as the piezoelectric actuator of the first embodiment. Hereinafter, a configuration different from the first embodiment will be described.

As shown in FIG. 12, the piezoelectric actuator 21 has a diaphragm 26 made of 2 μm Cr, a common electrode 27 formed on the diaphragm 26 and 5.5 μm thick Cu, and a common electrode 27 formed on the common electrode 27. An adhesion layer 32 made of Ti having a thickness of 50 nm, an orientation control layer 36 made of a Pt-Ti alloy having a thickness of 0.2 μm formed on the adhesion layer 32, and an adhesion control layer 36 formed on the orientation control layer 36. A crystal control layer 28 made of lead lanthanum titanate having a thickness of 50 nm; a piezoelectric body 29 made of Pb (Zr, Ti) O ₃ having a thickness of 3 μm formed on the crystal control layer 28; It has a formed individual electrode 33 made of Pt having a thickness of 0.2 μm and an electrode wiring formed on the piezoelectric body 29 and connected to the individual electrode 33 and made of Pt having a thickness of 0.2 μm. I have. The active layer in the present invention is constituted by the orientation control layer 36.

(4) The adhesive layer 32 plays a role of bonding the common electrode 27 and the orientation control layer 36. The orientation control layer 36 is for growing the piezoelectric body 29a in the displacement region in a perovskite structure regardless of the material of the substrate. Further, the orientation control layer 36 also has a role of causing the above-described lead lanthanum titanate to act as the crystal control layer 28. The Ti content of the orientation control layer 36 is 1 to 2%.

(Method of manufacturing inkjet head)
Next, a method of manufacturing the inkjet head 1 will be described with reference to FIGS. The method of manufacturing the ink jet head 1 described below is called a direct method.

First, as shown in FIG. 13A, the vibration plate 26 made of Cr is formed on a Si substrate 48. Next, as shown in FIG. 13B, a common electrode 27 made of Cu is formed on the vibration plate 26. Next, as shown in FIG. 13C, an adhesive layer 32 made of Ti is formed on the common electrode 27. Next, as shown in FIG. 13D, an orientation control layer 36 made of a Pt—Ti alloy is formed on the adhesive layer 32. Next, as shown in FIG. 13E, a lead lanthanum titanate layer 30 is formed on the orientation control layer. Next, as shown in FIG. 14A, the crystal control layer 28 is formed by individualizing the lead lanthanum titanate layer 30 in the displacement region by etching or the like.

Next, as shown in FIG. 14B, a piezoelectric body 29 made of Pb (Zr, Ti) O ₃ is formed on the crystal control layer 28 and the orientation control layer 36 by sputtering or vapor deposition. Accordingly, the piezoelectric body 29a formed on the crystal control layer 28, that is, in the displacement region, grows in a perovskite structure. On the other hand, the piezoelectric body 29b formed on the orientation control layer 36, that is, in the wiring region, grows in a pyrochlore structure. Next, as shown in FIG. 14C, an upper electrode 49 made of Pt is formed on the piezoelectric body 29 by sputtering or vapor deposition. Next, as shown in FIG. 14D, the individual electrodes 33 and the electrode wirings 34 are formed by individualizing the upper electrodes 49 corresponding to portions where the upper electrodes 49 and the electrode wirings 34 in the displacement area are formed by etching or the like. I do. At the same time, the piezoelectric bodies 29a in the displacement area are also individualized. Finally, as shown in FIG. 14E, the Si substrate 48 is processed to form the head main body 17 in which the pressure chamber 19 is formed. Note that a stopper layer (not shown) may be provided between the Si substrate 48 and the vibration plate 26 from the viewpoint of convenience in processing the Si substrate 48 to form the pressure chamber 19.

に お い て In the present embodiment, the same effect as in the first embodiment can be obtained.

According to the present embodiment, the adhesive layer 32 is provided between the common electrode 27 and the orientation control layer 36, but the adhesive layer 32 may not be provided.

According to the present embodiment, the orientation control layer 36 is made of a Pt—Ti alloy, but may be made of an Ir—Ti alloy.

According to the present embodiment, the crystal control layer 28 is formed by individualizing the lead lanthanum titanate layer 30 in the displacement region by etching or the like. However, as shown in FIG. Even if the orientation control layer 36 made of a Pt-Ti alloy is individualized instead of 30, the piezoelectric body 29a in the displacement region grows in a perovskite structure as described above.

According to the above embodiments, the diaphragm 26 and the common electrode 27 are provided separately, but the common electrode 27 may also serve as the diaphragm.

According to each of the above embodiments, the piezoelectric body 29 is made of Pb (Zr, Ti) O ₃ , but lead titanate (PbTiO ₃ ) and lead zirconate titanate (Pb (Zr, Ti) O ₃ ) ₃ ), lead zirconate (PbZrO ₃ ), lead lanthanum titanate ((Pb, La) TiO ₃ ), lead lanthanum zirconate titanate ((Pb, La) (Zr, Ti) O ₃ ), and magnesium niobate It may be made of a piezoelectric ceramic or the like containing at least one of lead (Pb (Mg, Nb) O ₃ ). Further, a piezoelectric body having a thickness different from that of each of the above embodiments may be used.

According to the above embodiments, the common electrode 27 is formed on the head main body 17, but the individual electrode 33 may be formed on the head main body 17. At this time, the common electrode 27 is formed on the piezoelectric body 29.

  Further, the common electrode 27, the individual electrode 33, the head main body 17 and the like may be made of a material and a thickness different from those of the above embodiments.

As described above, the present invention is useful when applied to printers such as computers, facsimile machines, and copiers.

FIG. 1 is a schematic configuration diagram of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view showing a part of the inkjet head in a cutaway manner. FIG. 3 is a plan view of the inkjet head. FIG. 4 is a sectional view taken along line AA of FIG. 3. FIG. 4 is a sectional view taken along line BB of FIG. 3. FIG. 3 is a diagram showing a relationship between a film thickness ratio and a relative dielectric constant of a two-layer film in which a piezoelectric body having a perovskite structure and a piezoelectric body having a pyrochlore structure are stacked. (A)-(d) are some of the manufacturing process drawings of an inkjet head. (A)-(d) are some of the manufacturing process drawings of an inkjet head. It is sectional drawing of an inkjet head. (A)-(e) is a part of manufacturing process drawing of an inkjet head. (A)-(d) are some of the manufacturing process drawings of an inkjet head. It is sectional drawing of an inkjet head. (A)-(e) is a part of manufacturing process drawing of an inkjet head. (A)-(e) is a part of manufacturing process drawing of an inkjet head. It is sectional drawing of the modification of an inkjet head.

Explanation of reference numerals

1 inkjet head 17 head body 26 diaphragm 27 common electrode (lower electrode)
28 Crystal control layer 29a Piezoelectric body 29b in displacement area Piezoelectric body 32 in wiring area 32 Adhesive layer 33 Individual electrode (upper electrode)
36 Orientation control layer (active layer)

Claims (11)

A piezoelectric actuator comprising: a lower electrode, a piezoelectric layer formed on the lower electrode, and an upper electrode formed on the piezoelectric layer and applying a voltage to the piezoelectric layer together with the lower electrode,
The piezoelectric layer is constituted by a piezoelectric layer in a displacement region and a piezoelectric layer in a wiring region located in a portion other than the displacement region,
A piezoelectric actuator, wherein the dielectric constant of the piezoelectric layer in the wiring region is lower than the dielectric constant of the piezoelectric layer in the displacement region. A piezoelectric actuator comprising: a lower electrode, a piezoelectric layer formed on the lower electrode, and an upper electrode formed on the piezoelectric layer and applying a voltage to the piezoelectric layer together with the lower electrode,
The piezoelectric layer is constituted by a piezoelectric layer in a displacement region and a piezoelectric layer in a wiring region located in a portion other than the displacement region,
A piezoelectric actuator in which the piezoelectric layer in the displacement region has a perovskite structure, and the piezoelectric layer in the wiring region has a pyrochlore structure. 3. The piezoelectric actuator according to claim 2, wherein a crystal control layer made of lanthanum lead titanate is formed on a surface of the piezoelectric layer on the upper electrode side in the displacement region or on a surface of the piezoelectric layer on the lower electrode side in the displacement region. . 4. The piezoelectric actuator according to claim 3, wherein an active layer made of one of Pt, a Pt-Ti alloy, and an Ir-Ti alloy is formed on a surface of the crystal control layer opposite to the piezoelectric layer. . The piezoelectric layer is made of a piezoelectric ceramic containing at least one of lead titanate, lead zirconate titanate, lead zirconate, lanthanum lead titanate, lanthanum lead titanate zirconate, and lead magnesium niobate. 5. The piezoelectric actuator according to any one of 4. An inkjet head comprising the piezoelectric actuator according to any one of claims 1 to 5. An ink jet recording apparatus comprising the ink jet head according to claim 6. Forming an upper electrode composed of one of Pt, Pt-Ti alloy, and Ir-Ti alloy on the substrate;
Forming a lead lanthanum titanate layer on the upper electrode;
Individualizing a portion corresponding to a displacement region in the lead lanthanum titanate layer,
Forming a piezoelectric layer on the upper electrode and the individualized lanthanum lead titanate layer,
Forming a lower electrode on the piezoelectric layer;
The manufacturing method of the piezoelectric actuator provided with. Forming an upper electrode composed of one of Pt, Pt-Ti alloy, and Ir-Ti alloy on the substrate;
A step of individualizing a portion corresponding to a displacement region in the upper electrode,
Forming a lead lanthanum titanate layer on the substrate and the individualized upper electrode,
Forming a piezoelectric layer on the lead lanthanum titanate layer,
Forming a lower electrode on the piezoelectric layer;
The manufacturing method of the piezoelectric actuator provided with. Forming a diaphragm on a substrate, and forming a lower electrode on the diaphragm or forming a lower electrode also serving as a diaphragm on the substrate,
Forming an active layer made of any one of Pt, Pt-Ti alloy and Ir-Ti alloy on the lower electrode;
Forming a lead lanthanum titanate layer on the active layer;
Individualizing a portion corresponding to a displacement region in the lead lanthanum titanate layer,
Forming a piezoelectric layer on the active layer and on the individualized lanthanum lead titanate layer,
Forming an upper electrode on the piezoelectric layer;
The manufacturing method of the piezoelectric actuator provided with. Forming a diaphragm on a substrate, and forming a lower electrode on the diaphragm or forming a lower electrode also serving as a diaphragm on the substrate,
Forming an active layer made of any one of Pt, Pt-Ti alloy and Ir-Ti alloy on the lower electrode;
Individualizing a portion corresponding to a displacement region in the active layer;
Forming a lead lanthanum titanate layer on the lower electrode and on the individualized active layer,
Forming a piezoelectric layer on the lead lanthanum titanate layer,
Forming an upper electrode on the piezoelectric layer;
The manufacturing method of the piezoelectric actuator provided with.

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