JP2011119608A - Piezoelectric element, pump using the same, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric element of which composition of a piezoelectric part is more stable, along with its manufacturing method and a pump using the piezoelectric element. <P>SOLUTION: The piezoelectric element includes a piezoelectric part 6 including piezoelectric material, a lower electrode 5 formed on the main surface of the piezoelectric part 6, a barrier layer 4 formed on the lower electrode 5, and an oxide layer 3 formed on the barrier layer 4. The barrier layer 4 comprises titanium oxide doped with at least one element from among the elements contained in a lead based perovskite compound except for titanium and oxygen. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a piezoelectric element, a pump using the piezoelectric element, and a method for manufacturing the piezoelectric element.

Piezoelectric elements are elements that generate distortion due to the piezoelectric effect when a voltage is applied, and are used in a wide range of fields. The piezoelectric element is configured, for example, by sequentially stacking a substrate, a first electrode, a piezoelectric portion, and a second electrode. The piezoelectric material constituting the piezoelectric part is, for example, a lead-based perovskite compound that exhibits excellent piezoelectric characteristics. A typical example of the lead-based perovskite compound is lead zirconate titanate. In addition, the lead position (A site) of lead zirconate titanate is partially substituted with trivalent elements such as lanthanum and neodymium, and the position of zirconium and titanium in lead zirconate titanate (B site) is niobium or Substituted with pentavalent or hexavalent elements such as tantalum or tungsten, PbZrO ₃ —PbTiO ₃ solid solution (PZT) -based material, or Pb (B′B ′ ′) O ₃ (so-called relaxor material). However, B ′ is a cation such as magnesium or zinc, and B ′ ′ is a pentavalent or hexavalent cation such as niobium or tungsten).

  Conventionally, in such a piezoelectric element, the element diffuses from the piezoelectric material constituting the piezoelectric part to the substrate, and the composition of the piezoelectric material constituting the piezoelectric part changes, thereby causing variations in the piezoelectric characteristics of the piezoelectric part. The problem is known. Therefore, in order to solve this problem, for example, techniques of Patent Document 1 and Patent Document 2 have been proposed.

Patent Document 1 discloses a technique in which a barrier layer made of a ZrO ₂ film is provided between a substrate and a piezoelectric thin film (a film on which a piezoelectric material is formed). It is described that this barrier layer can suppress interdiffusion of atoms between the piezoelectric thin film and the substrate.

  In Patent Document 2, when there is an easily diffusing element in the manufacturing process of the piezoelectric thin film, a raw material in which the composition ratio of the easily diffusing element (for example, Mg) is set higher than the composition ratio in the manufactured piezoelectric thin film A technique for manufacturing a piezoelectric thin film using the above is disclosed. In this way, in anticipation of element diffusion, by setting the composition ratio of easily diffusing elements in the raw material to be higher than the composition ratio in the piezoelectric thin film after manufacture, even if the element diffuses from the raw material by heat treatment or the like Thus, a piezoelectric thin film substantially in the stoichiometric ratio can be manufactured.

JP 2003-110158 A Japanese Patent Laid-Open No. 11-298062

  However, in the technique described in Patent Document 1, as disclosed in the paragraph [0005], lead atoms may diffuse from the piezoelectric thin film to the lower electrode, the barrier layer, or the substrate.

  In the technique described in Patent Document 2, since the amount of diffusion of elements in the piezoelectric thin film is not constant, there is a possibility that a piezoelectric thin film according to the stoichiometric ratio cannot be obtained.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a piezoelectric element in which the composition of the piezoelectric portion is more stable. Moreover, the objective of this invention is providing the pump using this piezoelectric element, and the manufacturing method of this piezoelectric element.

  As a result of various studies, the present inventor has found that the above object is achieved by the present invention described below. That is, a piezoelectric element according to an aspect of the present invention includes a piezoelectric portion including a piezoelectric material, an electrode formed on a main surface of the piezoelectric portion, a barrier layer formed on the electrode, and the barrier layer The barrier layer is made of titanium oxide doped with at least one of elements excluding titanium and oxygen among elements contained in the lead-based perovskite compound.

  According to such a configuration, the element doped in the barrier layer prevents the element from diffusing from the piezoelectric portion toward the first electrode, so that the composition of the piezoelectric portion becomes more stable. Therefore, variations in piezoelectric characteristics between the piezoelectric elements are reduced, and a piezoelectric element having a predetermined piezoelectric characteristic can be obtained more stably.

  In another aspect, in the above piezoelectric element, the barrier layer is preferably lead titanate.

  According to such a configuration, the lead doped in the barrier layer prevents the element from diffusing from the piezoelectric portion toward the first electrode, so that the composition of the piezoelectric portion becomes more stable. Therefore, variations in piezoelectric characteristics between the piezoelectric elements are reduced, and a piezoelectric element having a predetermined piezoelectric characteristic can be obtained more stably.

  In another aspect, in the above-described piezoelectric element, the lead titanate is formed by forming a titanium layer on the oxide film, forming lead or lead oxide on the titanium layer, and then performing heat treatment. It is formed.

  According to such a configuration, the lead titanate barrier layer is formed by performing heat treatment after forming the titanium layer and the lead or lead oxide layer separately rather than directly generating lead titanate. The lead titanate layer can be formed relatively easily while controlling the lead doping amount. Since the lead titanate barrier layer formed in this way is provided, the diffusion of elements from the piezoelectric portion toward the first electrode is prevented by the lead doped in the barrier layer. More stable. Therefore, variations in piezoelectric characteristics between the piezoelectric elements are reduced, and a piezoelectric element having a predetermined piezoelectric characteristic can be obtained more stably.

  In another aspect, in the above-described piezoelectric element, the lead titanate forms a titanium layer on the oxide film, forms lead or lead oxide on the titanium layer, and converts the lead or the oxidation It is characterized by being formed by heat treatment after an electrode is formed on lead.

  According to such a configuration, the lead doped in the barrier layer prevents the element from diffusing from the piezoelectric portion toward the first electrode, so that the composition of the piezoelectric portion becomes more stable. Therefore, variations in piezoelectric characteristics between the piezoelectric elements are reduced, and a piezoelectric element having a predetermined piezoelectric characteristic can be obtained more stably.

  A pump according to another aspect of the present invention includes any one of the above-described piezoelectric elements.

  According to such a configuration, it is possible to obtain a pump including a piezoelectric element having a predetermined piezoelectric characteristic with reduced variation between the piezoelectric elements. Therefore, the variation between pumps is reduced and the function of the pump becomes more stable.

  And the manufacturing method of the piezoelectric element concerning another one aspect | mode of this invention WHEREIN: The process of forming an electrode on the main surface of a piezoelectric part provided with a piezoelectric material, the process of forming a barrier layer on the said electrode, The said barrier Forming an oxide layer on the layer, wherein the barrier layer is made of titanium oxide doped with at least one of elements excluding titanium and oxygen among elements contained in the lead-based perovskite compound. And

  According to such a configuration, the element doped in the barrier layer prevents the element from diffusing from the piezoelectric portion toward the first electrode, so that the composition of the piezoelectric portion becomes more stable. Therefore, variations in piezoelectric characteristics between the piezoelectric elements are reduced, and a piezoelectric element having a predetermined piezoelectric characteristic can be obtained more stably.

  According to another aspect, in the above-described method for manufacturing a piezoelectric element, the step of forming the barrier layer includes forming a titanium layer on the oxide film and forming lead or lead oxide on the titanium layer. The barrier layer made of lead titanate is formed by heat treatment.

  According to such a configuration, the lead doped in the barrier layer prevents the element from diffusing from the piezoelectric portion toward the first electrode, so that the composition of the piezoelectric portion becomes more stable. Therefore, variations in piezoelectric characteristics between the piezoelectric elements are reduced, and a piezoelectric element having a predetermined piezoelectric characteristic can be obtained more stably.

  According to another aspect, in the above-described piezoelectric element manufacturing method, the step of forming the barrier layer includes forming a titanium layer on the oxide film, forming lead or lead oxide on the titanium layer, The barrier layer made of lead titanate is formed by heat treatment after forming an electrode on the lead or lead oxide.

  According to such a configuration, the lead doped in the barrier layer prevents the element from diffusing from the piezoelectric portion toward the first electrode, so that the composition of the piezoelectric portion becomes more stable. Therefore, variations in piezoelectric characteristics between the piezoelectric elements are reduced, and a piezoelectric element having a predetermined piezoelectric characteristic can be obtained more stably.

  The piezoelectric element and the manufacturing method thereof according to the present invention can provide an element having a more stable composition of the piezoelectric portion. And since the pump of this invention using such a piezoelectric element uses such a piezoelectric element with few variations between elements, the variation between pumps is reduced and the function of a pump becomes more stable.

It is sectional drawing which shows the structure of the pump which concerns on embodiment. It is sectional drawing which shows the structure of the piezoelectric element which concerns on embodiment.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.

  FIG. 1 is a cross-sectional view illustrating a configuration of a pump according to an embodiment. FIG. 2 is a cross-sectional view showing the configuration of the piezoelectric element according to the embodiment.

  As shown in FIG. 1, the pump 30 using the piezoelectric element in the present embodiment includes a piezoelectric element 1 that is deformed by a piezoelectric effect by application of a voltage, and can discharge a fluid in accordance with the deformation of the piezoelectric element 1. A head 20 is provided. In the present embodiment, the pump 30 is, for example, an ink jet recording head.

  The piezoelectric element 1 is an element that is deformed by a piezoelectric effect by application of a voltage. As shown in FIG. 2, the piezoelectric element 1 has a flat plate shape and includes a piezoelectric part 6 including a piezoelectric material and one main surface of the piezoelectric part 6. Formed on the lower electrode 5 formed, the barrier layer 4 formed on the lower electrode 5, the oxide layer 3 formed on the barrier layer 4, and the other main surface opposite to the main surface of the piezoelectric portion 6. The upper electrode 7 is formed on the substrate 2.

  The substrate 2 is a flat plate member made of a crystalline silicon substrate or the like.

The oxide layer 3 is quartz (SiO ₂ ) in the present embodiment. The thickness of the oxide layer 3 is, for example, about 1.0 μm. In addition, the oxide layer 3 may be an amorphous silicon oxide film such as a natural oxide film. The oxide layer 3 is formed to have a thickness of about 500 nm to 3 μm, for example.

  The barrier layer 4 is made of titanium oxide doped with at least one of elements excluding titanium and oxygen among elements contained in the lead-based perovskite compound. More specifically, the elements contained in the lead-based perovskite type compound are lead, lanthanum, magnesium, niobium and tungsten. The thickness of the barrier layer 4 is, for example, about 20 to 25 nm.

  Furthermore, since the barrier layer 4 is a piezoelectric material, it has an effect of enhancing the piezoelectric characteristics of the piezoelectric portion 6. More specifically, the orientation of the piezoelectric portion 6 can be more easily controlled in the manufacturing process. More specifically, the thickness of the barrier layer 4 is, for example, about 10 nm to 1.0 μm, but the barrier layer 4 has a thickness that can provide the function and effect as the barrier layer 4. There is no particular limitation.

As described above, the barrier layer 4 is titanium oxide doped with at least one of elements excluding titanium and oxygen among the elements contained in the lead-based perovskite compound, and the piezoelectric portion 6 described later is formed from the lead-based perovskite compound. Therefore, the diffusion of elements from the piezoelectric portion 6 to the lower electrode 5 can be reduced. Furthermore, by providing the barrier layer 4 made of such a piezoelectric material, the adhesion between the lower electrode 5 and the piezoelectric portion 6 is higher than when SiO ₂ is directly applied, and the crystal orientation of the lower electrode 5 is also improved. . If the orientation of the lower electrode 5 is good, the crystal orientation of the piezoelectric portion 6 is also improved, so that a piezoelectric element having a higher piezoelectric constant can be obtained.

The lower electrode 5 is one electrode for applying a voltage to the piezoelectric portion 6. The lower electrode 5 is, for example, platinum (Pt), iridium (Ir), iridium oxide (IrO _x ), titanium (Ti), or the like. The thickness of the lower electrode 5 is, for example, about 100 nm to 200 nm.

The piezoelectric portion 6 is a lead-based perovskite compound. Here, the lead-based perovskite compound is a compound in which the position (A site) of lead zirconate titanate or lead zirconate titanate is partially substituted with a trivalent element such as lanthanum or neodymium, or titanium zirconate. As a lead acid zirconium or titanium position (B site) substituted with pentavalent or hexavalent elements such as niobium, tantalum or tungsten, PbZrO ₃ -PbTiO ₃ solid solution (PZT) based materials, or so-called relaxor materials It is represented by known Pb (B ′ B ′ ′) O ₃ (where B ′ is a cation such as magnesium or zinc, and B ′ ′ is a pentavalent or hexavalent cation such as niobium or tungsten). It is a substance to be used. The thickness of the piezoelectric part 6 is formed to about 500 nm to 10 μm.

The upper electrode 7 serves as the other electrode for applying a voltage to the piezoelectric portion 6. The upper electrode 7 is, for example, platinum (Pt), iridium (Ir), iridium oxide (IrO _x ), titanium (Ti), or the like. The thickness of the upper electrode 7 is formed to about 100 nm.

  By configuring the piezoelectric element 1 as described above, the element doped in the barrier layer prevents the diffusion of the element from the piezoelectric portion 6 toward the lower electrode 5, so that the composition of the piezoelectric portion 6 becomes more stable. . Therefore, the variation in the piezoelectric characteristics between the piezoelectric elements 1 is reduced, and the piezoelectric element 1 having the predetermined piezoelectric characteristics can be obtained more stably.

  The pump 30 includes, for example, a hollow substantially rectangular parallelepiped pump head 20. The hollow portion is a cavity 222 for storing a fluid. The upper surface member forming one surface of the pump head 20 is constituted by the piezoelectric element 1. The bottom surface member forming the other surface facing the one surface of the pump head 20 is composed of a flat nozzle plate 21, and the nozzle plate 21 has a through-hole penetrating the nozzle plate 21. A certain nozzle port 211 is formed. In order to supply a fluid to the cavity 222 (the hollow portion) of the pump head 20, the side member forming the side surface (circumferential surface) sandwiched between the one surface and the other surface of the pump head 20 is used. A fluid supply hole (not shown) is formed.

  In the pump head 20 having such a configuration, in the piezoelectric element 1 laminated on the substrate 2 shown in FIG. 2, a recess 2A reaching the oxide layer 3 is formed on the substrate 2 by, for example, etching. Further, an ink chamber substrate 22 on which a nozzle plate 21 made of, for example, silicon is laminated is prepared, and a recess 22A that reaches the nozzle plate 21 is formed in the ink chamber substrate 22 by, for example, etching. Then, the substrate 2 and the ink chamber substrate 22 are joined so that the recess 2A and the recess 22A are combined to form the cavity 222. Thus, a pump having the configuration shown in FIG. 1 is created. Note that the substrate 2 forming the recess 2A and the ink chamber substrate 22 forming the recess 22A are the side members. The cavity 222 is a space for storing the fluid to be discharged, and has a volume that is variable by deformation of the piezoelectric element 1. For example, the piezoelectric element 1 is deformed into a convex shape or a concave shape into the cavity 222 by applying a voltage, and thereby the volume of the cavity 222 is varied.

  In the above embodiment, the pump 30 is an ink jet recording head. However, the pump 30 is preferably used for a pump that dilutes liquid fuel with a diluting liquid and supplies the diluted liquid fuel to the fuel cell. be able to.

  Next, a method for manufacturing the piezoelectric element 1 as shown in FIG. 2 will be described. The manufacturing method of the piezoelectric element 1 in the present embodiment includes a step of forming the oxide layer 3 on the substrate 2, a step of forming the precursor barrier layer 4A made of the material of the barrier layer 4 by sputtering on the oxide layer 3, and The method includes a step of forming the barrier layer 4, a step of forming the lower electrode 5, a step of forming the piezoelectric portion 6, and a step of forming the upper electrode 7. In the following manufacturing process, the substrate 2 is a silicon substrate having a thickness of 200 μm.

Oxide layer 3 formation process:
An oxide layer 3 is formed on the substrate 2 using a film formation method such as thermal oxidation or CVD. The oxide layer 3 is SiO ₂ having a thickness of 0.1 μm.

Barrier layer 4 formation process:
Next, after cooling the substrate 2 on which the oxide layer 3 is formed to room temperature (20 ° C.), the material of the barrier layer 4 is formed on the oxide layer 3 to form the precursor barrier layer 4A, and heat treatment such as baking is performed. As a result, the barrier layer 4 is formed.

  As the material of the barrier layer 4, a titanium film is formed on the oxide layer 3 by sputtering, and further, titanium and oxygen are removed from elements contained in the lead-based perovskite compound by sputtering. The film is formed by forming a film made of at least one element. Of the elements contained in the lead-based perovskite compound, at least one of the elements excluding titanium and oxygen is any one of lead, lead oxide, lanthanum, magnesium, niobium, and tungsten. The titanium film has a thickness of 20 nm, and the lead film, lead oxide film, lanthanum film, magnesium film, niobium film, and tungsten film have a thickness of 1 to 5 nm.

  After the formation of the precursor barrier layer 4A, a heat treatment such as firing is performed to form the barrier layer 4 made of titanium oxide doped with at least one of elements other than titanium and oxygen among elements contained in the lead-based perovskite compound. To do. The heat treatment is performed at a baking temperature of 700 ° C. for 24 hours or more. A diffusion furnace is used for firing.

Lower electrode 5 formation process:
Next, the lower electrode 5 is formed on the barrier layer 4. A sputtering method is used to form the lower electrode 5. The lower electrode 5 is platinum having a thickness of 100 nm. For example, a titanium layer, a titanium oxide layer, a titanium layer, a platinum layer, and a titanium layer are stacked with a thickness of 0.01 μm, 0.01 μm, 0.005 μm, 0.5 μm, and 0.005 μm.

Piezoelectric part 6 formation process:
Next, the piezoelectric portion 6 is formed on the lower electrode 5. Specifically, the piezoelectric portion 6 is formed on the lower electrode 5 by sputtering at a high temperature (about 600 ° C.). The thickness of the piezoelectric portion 6 is 5 μm. The target of the sputtering method is PZT adjusted so that zirconium and titanium have a molar ratio after film formation of 53 to 47.

In addition, as a sputtering target, zirconium and titanium were adjusted to 53 to 47 in the molar ratio after film formation, and lead and lanthanum were adjusted to 100 to 1 in the molar ratio after film formation. (Pb _0.99 La _0.01 ) (Zr _0.53 Ti _0.47 ) O ₃ may be used.

Further, instead of the above, as a sputtering target, zirconium and titanium have a molar ratio of 53 to 47 after film formation, and titanium and magnesium have a molar ratio of 46 to 1 after film formation. Adjusted Pb (Zr _0.53 Ti _0.46 Mg _0.01 ) O ₃ may be used.

Further, instead of the above, as a sputtering target, Pb (Mg _1/3 Nb _2/3 ) O adjusted so that the molar ratio of magnesium and niobium after film formation becomes 1 to 2 after film formation. ₃ may be used.

Further, instead of the above, as a sputtering target, Pb [(Zr _0.2 Ti _0.3 (Mg _1/3 Nb _2/3 ) _0.3 (Zr _1/3 Nb _2/3 ) _0.1 (Mg _1/3 W _2/3 ) _0.1 ] O ₃ may be used.

Upper electrode 7 formation process:
Next, the upper electrode 7 is formed on the piezoelectric portion 6. The upper electrode 7 is formed by laminating titanium and gold with a thickness of 10 nm and 200 nm, respectively. For this lamination, a sputtering method or a vapor deposition method is used.

  When the barrier layer 4 in the piezoelectric element 1 thus obtained was observed with a transmission electron microscope (TEM) and measured with an energy dispersive X-ray analysis (EDS), the barrier layer 4 was observed from the oxide layer 3 side. It was confirmed that the lead content increased toward the lower electrode 5.

  As another embodiment, the barrier layer 4 may be formed after the step of forming the lower electrode 5. That is, after depositing the material of the barrier layer 4, the lower electrode 5 may be formed on the deposited barrier layer 4, and heat treatment may be performed to form the barrier layer 4.

  The inventor changed the conditions of the barrier layer 4 formation process, and compared the characteristics of the piezoelectric element 1 manufactured according to the above embodiment with the characteristics of the piezoelectric element (comparative example) in which the barrier layer is titanium oxide. The test results of the following Examples 1 to 3 will be described.

  In any of Examples 1 to 3 and Comparative Example, as a sputtering method target used in the formation process of the piezoelectric portion 6, adjustment was made so that zirconium and titanium had a molar ratio of 53:47 after film formation. PZT was used.

The piezoelectric constant _{d 31} was measured according to the method of the ceramic Volume 42, No. 3, 2007 page 184 describes.

<Example 1>
In the formation process of the barrier layer 4, after forming titanium with a thickness of 20 nm on the oxide layer 3, lead with a thickness of 1 nm is formed, and after the heat treatment, the barrier layer 4 is formed. Thereafter, the process proceeds to the formation process of the lower electrode 5.

<Example 2>
In the formation process of the barrier layer 4, after forming titanium with a thickness of 20 nm on the oxide layer 3, lead oxide with a thickness of 3 nm is formed, and after the heat treatment, the barrier layer 4 is formed. Thereafter, the process proceeds to the formation process of the lower electrode 5.

<Example 3>
In the step of forming the barrier layer 4, after forming titanium having a thickness of 20 nm on the oxide layer 3, lead having a thickness of 1 nm is formed. Then, it progresses to the formation process of the lower electrode 5, and after forming the lower electrode 5, heat processing is performed and the barrier layer 4 is formed.

<Comparative example>
In the formation process of the barrier layer 4, titanium having a thickness of 20 nm is formed on the oxide layer 3, and after the heat treatment, a barrier layer made of titanium oxide is formed. Thereafter, the process proceeds to the formation process of the lower electrode 5.

表１に示されるように、実施例１〜３ではいずれもｄ_３１は、絶対値で１４２ｐｍ／Ｖ前後であり、本実施の形態におけるバリア層４の存在によって、圧電素子間の圧電特性のバラツキが低減されることを示している。

As shown in Table 1, in each of Examples 1 to 3, d ₃₁ is an absolute value of around 142 pm / V, and due to the presence of the barrier layer 4 in the present embodiment, variations in piezoelectric characteristics between the piezoelectric elements. Is reduced.

Furthermore, in Examples 1 to 3, d ₃₁ exhibited a high piezoelectric characteristic of 140 pm / V or more in absolute value. Furthermore, compared with the comparative example, in each of Examples 1 to 3, the dielectric constant was as high as 1026 or higher.

  The inventor tested the characteristics of the piezoelectric element 1 manufactured according to the above embodiment by changing the conditions of the barrier layer 4 forming step and the piezoelectric portion 6 forming step. Comparative examples corresponding to Examples 4 to 7 are piezoelectric elements in which the barrier layer is titanium oxide, and the conditions in the process of forming the piezoelectric portion 6 of each comparative example are the same as those of the corresponding examples. The test results of Examples 4 to 7 below will be described.

<Example 4>
In the step of forming the barrier layer 4, after forming titanium with a thickness of 20 nm on the oxide layer 3, lead and lanthanum are each formed with a thickness of 1 nm, and heat treatment is performed to form the barrier layer 4. In the formation process of the piezoelectric part 6, as sputtering targets, zirconium and titanium are 53 to 47 in a molar ratio after film formation, and lead and lanthanum are 100 to 1 in a molar ratio after film formation. (Pb _0.99 La _0.01 ) (Zr _0.53 Ti _0.47 ) O ₃ adjusted as described above is used.

<Example 5>
In the formation process of the barrier layer 4, after forming titanium with a thickness of 20 nm on the oxide layer 3, lead oxide with a thickness of 3 nm is formed, and heat treatment is performed to form the barrier layer 4. In the formation process of the piezoelectric portion 6, as a sputtering method target, zirconium and titanium have a molar ratio of 53 to 47 after film formation, and titanium and magnesium have a molar ratio of 46 to 1 after film formation. Pb (Zr _0.53 Ti _0.46 Mg _0.01 ) O ₃ adjusted as described above is used.

<Example 6>
In the formation process of the barrier layer 4, after forming titanium with a thickness of 20 nm on the oxide layer 3, lead oxide with a thickness of 3 nm is formed, and heat treatment is performed to form the barrier layer 4. Pb (Mg _1/3 Nb _2/3 ) adjusted so that the molar ratio of magnesium and niobium after film formation becomes 1: 2 as a sputtering target in the formation process of the piezoelectric portion 6 O ₃ is used.

<Example 7>
In the formation process of the barrier layer 4, after forming titanium with a thickness of 20 nm on the oxide layer 3, lead with a thickness of 1 nm is formed, and heat treatment is performed to form the barrier layer 4. In the step of forming the piezoelectric portion 6, Pb [(Zr _0.2 Ti _0.3 (Mg _1/3 Nb _2/3 ) _0.3 (Zr _1/3 Nb _2/3 )) _{0. 1} (Mg _1/3 W _2/3 ) _0.1 ] O ₃ is used.

表２に示されるように、バリア層４を有する各実施例４〜７では、それぞれ対応する比較例に比べて、いずれもｄ_３１が１．３〜１．５倍に高くなり、圧電定数の向上を示している。

As shown in Table 2, in each of Examples 4 to 7 having the barrier layer 4, d ₃₁ was 1.3 to 1.5 times higher than the corresponding comparative examples, and the piezoelectric constant was Shows improvement.

  In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not covered by the claims. To be construed as inclusive.

DESCRIPTION OF SYMBOLS 1 Piezoelectric element 2 Substrate 3 Oxide layer 4 Barrier layer 5 Lower electrode 6 Piezoelectric part 7 Upper electrode 20 Pump head 21 Nozzle plate 22 Ink chamber substrate 211 Nozzle port 222 Cavity

Claims (8)

A piezoelectric portion comprising a piezoelectric material;
An electrode formed on the main surface of the piezoelectric portion;
A barrier layer formed on the electrode;
An oxide layer formed on the barrier layer,
The barrier layer is made of titanium oxide doped with at least one of elements excluding titanium and oxygen among elements contained in the lead-based perovskite compound. The piezoelectric element according to claim 1, wherein the barrier layer is lead titanate. 3. The piezoelectric according to claim 2, wherein the lead titanate is formed by forming a titanium layer on the oxide film, forming lead or lead oxide on the titanium layer, and then performing heat treatment. 4. element. The lead titanate is formed by forming a titanium layer on the oxide film, forming lead or lead oxide on the titanium layer, forming an electrode on the lead or lead oxide, and then performing heat treatment. The piezoelectric element according to claim 2, wherein:   The pump provided with the piezoelectric element of any one of Claim 1 thru | or 4. Forming an electrode on the surface of the piezoelectric portion including the piezoelectric material;
Forming a barrier layer on the electrode;
Forming an oxide layer on the barrier layer,
The method for manufacturing a piezoelectric element, wherein the barrier layer is made of titanium oxide doped with at least one of elements excluding titanium and oxygen among elements contained in the lead-based perovskite compound. The step of forming the barrier layer includes forming a titanium layer on the oxide film, forming lead or lead oxide on the titanium layer, and then heat-treating to form the barrier layer made of lead titanate. The method for manufacturing a piezoelectric element according to claim 6. In the step of forming the barrier layer, a titanium layer is formed on the oxide film, lead or lead oxide is formed on the titanium layer, an electrode is formed on the lead or lead oxide, and then heat treatment is performed. The method for manufacturing a piezoelectric element according to claim 6, wherein the barrier layer made of lead titanate is formed.

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