JP2012139922A - Piezoelectric element, liquid jetting head, liquid jetting apparatus, and method for manufacturing piezoelectric element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric element having good displacement characteristic and high reliability.SOLUTION: The piezoelectric element 100 includes: a first electrode layer 10; a piezoelectric material layer 20 formed above the first electrode layer 10; and a second electrode layer 30 formed above the piezoelectric material layer 20. The second electrode layer 30 includes: a first layer 32 formed on a top 22 of the piezoelectric material layer 20; and a second layer 36 formed on a top 34 of the first layer 32. A material of the second layer 36 is the same as a material of the first layer 32, and the density of the second layer 36 is less than that of the first layer 32.

Description

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

  For example, in a liquid ejecting apparatus such as an ink jet printer, a liquid ejecting head that ejects droplets of ink or the like is known. The liquid ejecting head includes a piezoelectric element for changing the pressure in the pressure chamber. The piezoelectric element has a piezoelectric layer sandwiched between an upper electrode and a lower electrode, and the piezoelectric layer can be deformed by a drive signal or the like. By displacing the piezoelectric element in this way, the liquid ejecting head can eject ink or the like supplied from the nozzle hole into the pressure chamber. Therefore, it is desired that the piezoelectric element has good displacement characteristics.

  In such a piezoelectric element, when the upper electrode is formed on the piezoelectric layer, the piezoelectric layer may be damaged (see Patent Document 1). As a result, the reliability of the piezoelectric element may be reduced. For example, in the technique described in Patent Document 2, the upper electrode is formed by sputtering.

JP 2009-196329 A JP 2007-266275 A

  One of the objects according to some aspects of the present invention is to provide a piezoelectric element having good displacement characteristics and high reliability. Another object of some aspects of the present invention is to provide a liquid ejecting head and a liquid ejecting apparatus having the piezoelectric element. Another object of some aspects of the present invention is to provide a method for manufacturing the piezoelectric element.

The piezoelectric element according to the present invention is
A first electrode layer;
A piezoelectric layer formed above the first electrode layer;
A second electrode layer formed above the piezoelectric layer;
Including
The second electrode layer includes
A first layer formed on the upper surface of the piezoelectric layer;
A second layer formed on an upper surface of the first layer;
Have
The material of the second layer is the same as the material of the first layer,
The density of the second layer is smaller than the density of the first layer.

  According to such a piezoelectric element, the first layer having a high density improves the interface state between the piezoelectric layer and the second electrode layer, and ensures high reliability. The restraining force with respect to the piezoelectric layer can be reduced to have good displacement characteristics. Details will be described later.

  In the description according to the present invention, the word “upper” is used, for example, “specifically” (hereinafter referred to as “A”) is formed above another specific thing (hereinafter referred to as “B”). The word “above” is used to include the case where B is formed directly on A and the case where B is formed on A via another object. Used.

In the piezoelectric element according to the present invention,
The thickness of the second layer may be greater than the thickness of the first layer.

  According to such a piezoelectric element, it is possible to have better displacement characteristics.

In the piezoelectric element according to the present invention,
The piezoelectric layer is formed to cover the first electrode layer,
The second layer may be further formed on the side of the piezoelectric layer.

  According to such a piezoelectric element, it is possible to have better displacement characteristics than in the case where the first layer having a high density is formed on the side surface of the piezoelectric layer. Furthermore, the second layer can suppress moisture from entering the piezoelectric layer.

In the piezoelectric element according to the present invention,
The density of the second electrode may decrease as it goes upward.

  Such a piezoelectric element can have good displacement characteristics and high reliability.

A liquid ejecting head according to the present invention includes:
The piezoelectric element according to the present invention is included.

  According to such a liquid ejecting head, the liquid ejection characteristics are good and high reliability can be obtained.

A liquid ejecting apparatus according to the present invention includes:
The liquid ejecting head according to the invention is included.

  According to such a liquid ejecting apparatus, the liquid ejection characteristics are good and high reliability can be obtained.

The method for manufacturing a piezoelectric element according to the present invention includes:
Forming a first electrode layer;
Forming a piezoelectric layer above the first electrode layer;
Forming a first layer constituting the second electrode layer on the upper surface of the piezoelectric layer by sputtering;
Forming a second layer constituting the second electrode layer on the upper surface of the first layer by sputtering;
Including
The second layer is formed of the same material as the first layer,
The sputtering power density for forming the second layer is larger than the sputtering power density for forming the first layer.

  According to such a method of manufacturing a piezoelectric element, the first layer having a high density can improve the interface state between the piezoelectric layer and the second electrode layer, and can ensure high reliability. By using the second layer having a small size, the restraining force on the piezoelectric layer can be reduced, and a piezoelectric element that can have good displacement characteristics can be obtained. Details will be described later.

In the method for manufacturing a piezoelectric element according to the present invention,
The step of forming the first layer and the step of forming the second layer may be performed continuously.

  According to such a method for manufacturing a piezoelectric element, the manufacturing time can be shortened and the efficiency of the manufacturing process can be improved.

In the method for manufacturing a piezoelectric element according to the present invention,
In the step of forming the first layer and the step of forming the second layer,
The first layer and the second layer may be formed by gradually increasing the sputtering power density.

  According to such a method for manufacturing a piezoelectric element, a piezoelectric element having good displacement characteristics and high reliability can be obtained.

In the method for manufacturing a piezoelectric element according to the present invention,
Before the step of forming the second layer, further comprising the step of patterning the first layer and the piezoelectric layer,
In the step of forming the second layer,
Furthermore, the second layer may be formed on the side of the patterned piezoelectric layer.

  According to such a method for manufacturing a piezoelectric element, it is possible to obtain a piezoelectric element having better displacement characteristics than in the case where the first layer having a high density is formed on the side surface of the piezoelectric layer. Furthermore, since the second layer can prevent moisture from entering the piezoelectric layer, it is not necessary to form a separate protective layer, and the process can be simplified.

In the method for manufacturing a piezoelectric element according to the present invention,
Sputtering power density for forming the first layer is a 0.2 kW / ^{m 2} or more 10 kW / ^{m 2} or less,
The sputtering power density for forming the second layer may be 20 kW / m ² or more and 80 kW / m ² or less.

  According to such a method for manufacturing a piezoelectric element, the density of the second layer can be surely made smaller than the density of the first layer.

FIG. 3 is a cross-sectional view schematically showing the piezoelectric element according to the embodiment. The graph which shows the fatigue characteristic of an Example. The graph which shows the displacement characteristic of an Example. Sectional drawing which shows typically the manufacturing process of the piezoelectric element which concerns on this embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric element which concerns on this embodiment. Sectional drawing which shows typically the piezoelectric element which concerns on the modification of this embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric element which concerns on the modification of this embodiment. FIG. 3 is a cross-sectional view schematically illustrating the liquid ejecting head according to the embodiment. FIG. 3 is an exploded perspective view schematically illustrating the liquid ejecting head according to the embodiment. FIG. 3 is a perspective view schematically illustrating the liquid ejecting apparatus according to the embodiment.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

1. Piezoelectric Element First, the piezoelectric element according to the present embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a piezoelectric element 100 according to this embodiment.

  As shown in FIG. 1, the piezoelectric element 100 includes a first electrode layer 10, a piezoelectric layer 20, and a second electrode layer 30. Further, the piezoelectric element 100 can include a protective layer 40. The piezoelectric element 100 is formed on the substrate 1, for example.

  The substrate 1 is a flat plate formed of, for example, a semiconductor or an insulator. The substrate 1 may be a single layer or a structure in which a plurality of layers are stacked. The internal structure of the substrate 1 is not limited as long as the upper surface is planar. For example, the substrate 1 may have a structure in which a space or the like is formed.

  The substrate 1 may include a diaphragm that is flexible and can be deformed (bent) by the operation of the piezoelectric layer 20. Examples of the material of the diaphragm include silicon oxide, zirconium oxide, and a laminate thereof.

  The first electrode layer 10 is formed on the substrate 1. The shape of the first electrode layer 10 is, for example, a layer shape or a thin film shape. The thickness of the first electrode layer 10 is, for example, not less than 50 nm and not more than 300 nm. The planar shape of the first electrode layer 10 is not particularly limited as long as the piezoelectric layer 20 can be disposed between the second electrode layers 30 when the second electrode layers 30 are opposed to each other.

Examples of the material of the first electrode layer 10 include various metals such as nickel, iridium, and platinum, their conductive oxides (for example, iridium oxide), and composite oxides of strontium and ruthenium (SrRuO _x : SRO). And a composite oxide of lanthanum and nickel (LaNiO _x : LNO). The first electrode layer 10 may have a single-layer structure made of the materials exemplified above, or may have a structure in which a plurality of materials are stacked.

  The first electrode layer 10 is paired with the second electrode layer 30 and serves as one electrode for applying a voltage to the piezoelectric layer 20 (for example, a lower electrode formed below the piezoelectric layer 20). be able to.

  The substrate 1 may not have a diaphragm, and the first electrode layer 10 may have a function as a diaphragm. That is, the first electrode layer 10 has a function as one electrode for applying a voltage to the piezoelectric layer 20 and a function as a diaphragm that can be deformed by the operation of the piezoelectric layer 20. It may be.

  Moreover, although not shown in figure, between the 1st electrode layer 10 and the board | substrate 1, the layer which provides both adhesiveness, and the layer which provides intensity | strength and electroconductivity may be formed, for example. Examples of such layers include various metals such as titanium, nickel, iridium, and platinum, and oxide layers thereof.

  The piezoelectric layer 20 is formed on the first electrode layer 10. The shape of the piezoelectric layer 20 is, for example, a layer shape or a thin film shape. The thickness of the piezoelectric layer 20 is, for example, not less than 300 nm and not more than 3000 nm. The upper surface 22 of the piezoelectric layer 20 and the side surface 24 of the piezoelectric layer 20 are connected to each other at an obtuse angle, for example. Although not shown, the upper surface 22 and the side surface 24 may be connected to each other at a right angle.

As the piezoelectric layer 20, a perovskite oxide piezoelectric material can be used. More specifically, examples of the material of the piezoelectric layer 20 include lead zirconate titanate (Pb (Zr, Ti) O ₃ : PZT) and lead zirconate titanate niobate (Pb (Zr, Ti, Nb). ) O ₃ : PZTN), barium titanate (BaTiO ₃ ), potassium sodium niobate ((K, Na) NbO ₃ ).

  The piezoelectric layer 20 can have piezoelectricity and can be deformed by applying a voltage from the first electrode layer 10 and the second electrode layer 30.

  The second electrode layer 30 is formed on the piezoelectric layer 20. The shape of the second electrode layer 30 is, for example, a layer shape or a thin film shape. The planar shape of the second electrode layer 30 is not particularly limited, but is, for example, rectangular.

  The second electrode layer 30 is paired with the first electrode layer 10 and serves as the other electrode for applying a voltage to the piezoelectric layer 20 (for example, an upper electrode formed above the piezoelectric layer 20). be able to.

  The second electrode layer 30 includes a first layer 32 and a second layer 36. The first layer 32 is formed on the upper surface of the piezoelectric layer 22. More specifically, the first layer 32 is in contact with the piezoelectric layer 20 and forms the lower surface of the second electrode layer 30. The shape of the first layer 32 is, for example, a layer shape or a thin film shape. The thickness of the first layer 32 is, for example, not less than 1 nm and not more than 10 nm. As the first layer 32, the materials listed above as the material of the first electrode 20 can be used.

  The second layer 36 is formed on the upper surface 34 of the first layer 32. In the illustrated example, the second layer 36 is in contact with the first layer 32 and forms the upper surface of the second electrode layer 30. The shape of the second layer 36 is, for example, a layer shape or a thin film shape. The thickness of the second layer 36 is larger than the thickness of the first layer 32, for example, not less than 20 nm and not more than 100 nm. The material of the second layer 36 is the same as the material of the first layer 32.

  The density of the second layer 36 is smaller than the density of the first layer 32. That is, it can be said that the first layer 32 is a dense layer as compared with the second layer 36. Therefore, it can be said that the sheet resistance of the second layer 36 is larger than the sheet resistance of the first layer 32. The crystallinity of the second layer 36 may be lower than the crystallinity of the first layer 32. By having the first layer 32 and the second layer 36, the second electrode layer 30 decreases in density as it goes upward.

  Although not shown, the second electrode layer 30 is formed above the third layer, for example, the third layer formed above the second layer 36 if the density decreases toward the top. A single layer or a plurality of layers may be provided above the second layer 36 such as a fourth layer.

  Further, the density of the first layer 32 may be uniform in the first layer 32, but may have a distribution in which the density gradually decreases toward the upper side, for example. Similarly, the density of the second layer 36 may be uniform in the second layer 36, but may have a distribution such that the density gradually decreases toward the upper side, for example. Since the density of the first layer 32 and the second layer 36 has a distribution, the entire second electrode layer 30 can also have a distribution in which the density gradually decreases toward the top.

  The protective layer 40 is formed on the second layer 36 and on the side (side surface 24) of the piezoelectric layer 20. Further, in the illustrated example, the protective layer 40 is also formed on the first electrode layer 10. Examples of the material of the protective layer 40 include aluminum oxide. The protective layer 40 can suppress moisture and the like from entering the piezoelectric layer 20.

  The protective layer 40 can have an opening 42. The opening 42 is formed on the second layer 36. For example, the deformation of the piezoelectric layer 20 may be limited by the protective layer 40 and the amount of displacement may be reduced. However, by forming the opening 42, the influence of the protective layer 40 on the deformation of the piezoelectric layer 20 is reduced. However, it is possible to reduce the amount of displacement of the piezoelectric element 100 by reducing the restraining force on the piezoelectric layer 20.

  The piezoelectric element 100 according to the present embodiment has, for example, the following characteristics.

  According to the piezoelectric element 100, the second layer 36 formed on the first layer 32 has a density smaller than that of the first layer 32. That is, the first layer 32 in contact with the piezoelectric layer 20 has a higher density than the second layer 36. Therefore, the piezoelectric element 100 has good fatigue characteristics and can have high reliability. Further, the piezoelectric element 100 can have good displacement characteristics. The reason will be described below.

  First, the reason why the piezoelectric element 100 can have high reliability will be described.

  FIG. 2 is a graph showing fatigue characteristics of the piezoelectric elements according to Examples 1 and 2. More specifically, FIG. 2 shows hysteresis curves at the initial stage (state before applying a pulse) and after application (state after applying 100 million pulses) in Examples 1 and 2. ing.

  In Examples 1 and 2, a silicon oxide layer having a thickness of 1 μm and a zircon oxide layer having a thickness of 400 nm are sequentially formed on a silicon substrate, and a platinum layer having a thickness of 100 nm is formed via a titanium layer having a thickness of 20 nm. A PZT layer having a thickness of 1 μm and an iridium layer having a thickness of 50 nm were sequentially formed to obtain a piezoelectric element. The silicon oxide layer was formed by a thermal oxidation method. The zircon oxide layer, titanium layer, platinum layer, PZT layer, and iridium layer were formed by sputtering.

In Example 1, the iridium layer was formed with a sputtering power density of 5 kW / m ² . In Example 2, the iridium layer was formed with a sputtering power density of 30 kW / m ² . As other conditions for forming the iridium layer, both of Examples 1 and 2 were performed using a DC magnetron sputtering apparatus, Ar was used as the sputtering gas, the sputtering gas pressure was 0.9 Pa, the sputtering gas flow rate was 50 SCCM, The substrate temperature (that is, the heating temperature of the object to be processed such as the PZT layer) was set to 250 ° C.

  2 that Example 1 has better fatigue characteristics than Example 2. FIG. This is because the sputtering power density in forming the iridium layer in Example 1 is smaller than that in Example 2, so the damage given to the PZT layer is small, and the interface state between the iridium layer and the PZT layer is good. Because.

  Here, the sheet resistance of the iridium layer of Example 1 was 3.75Ω / □, and the sheet resistance of the iridium layer of Example 2 was 4.15Ω / □. This shows that the iridium layer of Example 1 is denser and denser than the iridium layer of Example 2. That is, it can be said that the iridium layer having a high density can reduce damage to the PZT layer as compared with the iridium layer having a low density.

  Therefore, in the piezoelectric element 100 according to the present embodiment, the first layer 32 that is in contact with the piezoelectric layer 20 has a density higher than that of the second layer 36, and therefore has good fatigue characteristics and high reliability. As described above, the fatigue characteristics are mainly caused by the interface state between the second electrode layer 30 and the piezoelectric layer 20. Therefore, even if the second layer 36 having a low density is formed on the first layer 32 like the piezoelectric element 100, the influence of the second layer 36 on the fatigue characteristics is extremely small, and the piezoelectric element 100 is good. It is inferred to have excellent fatigue properties.

  Next, the reason why the piezoelectric element 100 can have good displacement characteristics will be described.

  FIG. 3 is a graph showing the displacement characteristics of the piezoelectric elements according to Examples 1 and 2. More specifically, FIG. 3 shows the displacement amount with respect to the resonance frequency of the piezoelectric element in the first and second embodiments.

  3 that Example 2 has a larger displacement amount and better displacement characteristics than Example 1. This is because, as described above, in Example 2, the density of the iridium layer is smaller than that in Example 1, and accordingly, the restraining force against the deformation (displacement of the piezoelectric element) of the PZT layer is small.

  Therefore, in the piezoelectric element 100 according to the present embodiment, the second layer 36 formed on the first layer 32 has a density smaller than that of the first layer 32, and thus can have good displacement characteristics. For example, by making the thickness of the second layer 36 larger than the thickness of the first layer 32, the piezoelectric element 100 can have better displacement characteristics.

  As described above, in the piezoelectric element 100 according to the present embodiment, the first layer 32 having a high density makes the interface state between the piezoelectric layer 20 and the second electrode layer 30 good and ensures high reliability. By the second layer 36 having a low density, the restraining force on the piezoelectric layer 20 can be reduced, and good displacement characteristics can be obtained. Furthermore, in the piezoelectric element 100, since the material of the first layer 32 and the material of the second layer 36 are the same, they can be formed by a simple process.

  The piezoelectric element 100 as described above may be applied to, for example, a liquid ejecting head or a liquid ejecting apparatus (ink jet printer) using the liquid ejecting head as a piezoelectric actuator that pressurizes the liquid in the pressure generating chamber. The piezoelectric layer may be used for other purposes such as a piezoelectric sensor that detects deformation of the piezoelectric layer as an electrical signal.

2. Next, a method for manufacturing a piezoelectric element according to this embodiment will be described with reference to the drawings. 4 and 5 are cross-sectional views schematically showing the manufacturing process of the piezoelectric element 100 according to the present embodiment.

  As shown in FIG. 4, the first electrode layer 10 is formed on the substrate 1. Here, the substrate 1 is formed, for example, by laminating a silicon oxide layer and a zircon oxide layer in this order on a silicon substrate. The silicon oxide layer is formed by, for example, a thermal oxidation method. The zircon oxide layer is formed by sputtering, for example.

  The first electrode layer 10 is formed, for example, by forming a conductive layer (not shown) and then patterning the conductive layer. The conductive layer is formed, for example, by sputtering, vacuum deposition, or MOCVD (Metal Organic Chemical Vapor Deposition). The patterning is performed by, for example, a photolithography technique and an etching technique.

  Next, the piezoelectric layer 20 a is formed on the first electrode layer 10. The piezoelectric layer 20a is formed by, for example, a sputtering method, a laser ablation method, an MOCVD method, a sol-gel method, a MOD (Metal Organic Deposition) method, or the like.

Next, the first layer 32a is formed on the upper surface 22a of the piezoelectric layer 20a. The first layer 32a is formed by sputtering. The first layer 32a is performed using, for example, a DC magnetron sputtering apparatus. Sputtering power density for forming the first layer 32a is, for example, 0.2 kW / cm ² or more 10 kW / cm ² or less. The sputtering power density may be constant while the first layer 32a is formed, or may be changed gradually. As the sputtering gas, for example, Ar, Ne, and a mixed gas of these and oxygen are used. Other conditions for forming the first layer 32a include, for example, a sputtering gas pressure of 0.1 Pa to 2 Pa, a sputtering gas flow rate of 5 SCCM to 100 SCCM, and a substrate temperature of 25 ° C. to 350 ° C. it can.

As shown in FIG. 5, the second layer 36a is formed on the upper surface 34a of the first layer 32a. The second layer 36a is formed by sputtering. The sputtering power density for forming the second layer 36a is larger than the sputtering power density for forming the first layer 32a, and is, for example, 20 kW / cm ² or more and 80 kW / cm ² or less. The sputtering power density may be constant while the second layer 36a is formed, or may be changed so as to increase gradually. The other conditions for forming the second layer 36a are the same as the conditions for forming the first layer 32a.

  The film formation of the first layer 32a and the film formation of the second layer 36a may be performed continuously. That is, after forming the first layer 32a, the second layer 36a may be continuously formed without carrying out the object to be processed (the object to be processed on which the first layer 32a or the like is formed) from the sputtering apparatus. Good. For example, when the first layer 32a and the second layer 36a are continuously formed, the density of the second electrode layer 30 gradually decreases as it goes upward by gradually increasing the sputtering power density. It can have such a distribution.

  Although not shown, for example, a third layer is formed above the second layer 36a, and a fourth layer is formed above the third layer. For example, a single layer is formed above the second layer 36a. A layer or a plurality of layers may be formed. Each layer is formed by a sputtering method, and is formed at a higher sputtering power density as it goes upward.

  As shown in FIG. 1, the first layer 32 a, the second layer 36 a, and the piezoelectric layer 20 a are patterned to form the second electrode layer 30 having the first layer 32 and the second layer 36, and the piezoelectric layer 20. Form. The patterning is performed by, for example, a photolithography technique and an etching technique.

  The first layer 32a, the second layer 36a, and the piezoelectric layer 20a may be patterned at once or may be patterned separately. Although not shown, the second electrode layer 30 may be formed by patterning the piezoelectric layer 20a and then forming the first layer 32a and the second layer 36a and patterning them.

  Next, the protective layer 40 is formed on the second electrode layer 30 and on the side (side surface 24) of the piezoelectric layer 20. The protective layer 40 is formed by, for example, a sputtering method or a CVD (Chemical Vapor Deposition) method. Next, the protective layer 40 is patterned to form the opening 42.

  Through the above steps, the piezoelectric element 100 according to this embodiment can be manufactured.

  The method for manufacturing the piezoelectric element 100 according to the present embodiment has the following features, for example.

  According to the method for manufacturing the piezoelectric element 100, the sputtering power density for forming the second layer 36a can be made larger than the sputtering power density for forming the first layer 32a. Thereby, as described above, the second layer 36 has a smaller density than the first layer 32. That is, the first layer 32 in contact with the piezoelectric layer 20 has a higher density than the second layer 36. Therefore, the first layer 32 having a high density can improve the interface state between the piezoelectric layer 20 and the second electrode layer 30 to ensure high reliability, and the second layer 36 having a low density can secure the reliability. In addition, it is possible to obtain a piezoelectric element 100 that can have a good displacement characteristic by reducing the restraining force on the piezoelectric layer 20.

  According to the method for manufacturing the piezoelectric element 100, the first layer 32a and the second layer 36a can be continuously formed. That is, after forming the first layer 32a, the second layer 36a can be continuously formed without carrying out the object to be processed from the sputtering apparatus. Thereby, manufacturing time can be shortened and the efficiency of a manufacturing process can be improved.

According to the manufacturing method of the piezoelectric element 100, the sputter power density for forming the first layer 32, a 0.2 kW / ^{m 2} or more 10 kW / ^{m 2} or less, the sputtering for forming the second layer 36 The power density can be 20 kW / m ² or more and 80 kW / m ² or less. Thereby, the density of the second layer 36 can be surely made smaller than the density of the first layer 32.

3. Next, a piezoelectric element according to a modification of the present embodiment will be described with reference to the drawings. FIG. 6 is a cross-sectional view schematically showing a piezoelectric element 200 according to a modification of the present embodiment. Hereinafter, in the piezoelectric element 200 according to the modification of the present embodiment, members having the same functions as those of the constituent members of the piezoelectric element 100 according to the present embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the example of the piezoelectric element 100, the second layer 36 is formed on the upper surface 34 of the first layer 32 as shown in FIG. 1. On the other hand, in the piezoelectric element 200, as shown in FIG. 6, the second layer 36 is formed on the upper surface 34 of the first layer 32 and the side surface 24 of the piezoelectric layer 20. In the illustrated example, the second layer 36 is formed to cover the side surface 24 of the piezoelectric layer 20. In the illustrated example, the second layer 36 is also formed on the substrate 1. In the piezoelectric element 200, the piezoelectric layer 20 is formed so as to cover the first electrode layer 10 (covering the upper surface and side surfaces of the first electrode layer 10).

  Next, a method for manufacturing a piezoelectric element according to a modification of the present embodiment will be described with reference to the drawings. FIG. 7 is a cross-sectional view schematically showing a method for manufacturing the piezoelectric element 200 according to a modification of the present embodiment.

  In the method for manufacturing the piezoelectric element 200, the steps up to the step of forming the first layer 32a are basically the same as the method for manufacturing the piezoelectric element 100, and will not be described. However, in the method for manufacturing the piezoelectric element 200, the first electrode layer 10 is formed so as to be covered with the piezoelectric layer 20a.

  In the method of manufacturing the piezoelectric element 200, as shown in FIG. 7, before the second layer 36a is formed, the first layer 32a and the piezoelectric layer 20a are patterned, and the first layer 32 and the piezoelectric layer 20 are formed. Form. Next, as shown in FIG. 6, the second layer 36 is formed. The second layer 36 is patterned as necessary. The film forming conditions for the second layer 36 are the same as the method for manufacturing the piezoelectric element 100.

  The piezoelectric element 200 according to the modification of the present embodiment has, for example, the following characteristics.

  According to the piezoelectric element 200, the second layer 36 is formed on the side surface 24 of the piezoelectric layer 20. Therefore, the second layer 36 can prevent moisture and the like from entering the piezoelectric layer 20. That is, the second layer 36 has a function of protecting the piezoelectric layer 20. Therefore, the piezoelectric element 200 can protect the piezoelectric layer 20 without forming the protective layer 40 as in the piezoelectric element 100 (see FIG. 1). Therefore, the process can be simplified.

  According to the piezoelectric element 200, as described above, the second layer 36 having a density lower than that of the first layer 32 is formed on the side surface 24 of the piezoelectric layer 20. If a layer having a high density is formed on the side surface of the piezoelectric layer, the deformation of the piezoelectric layer may be restricted by the layer, and the displacement characteristics of the piezoelectric element may deteriorate. Compared to such a configuration, the piezoelectric element 200 can have better displacement characteristics.

4). Liquid Ejecting Head Next, the liquid ejecting head according to the present embodiment will be described with reference to the drawings. FIG. 8 is a cross-sectional view schematically showing the main part of the liquid jet head 600. FIG. 9 is an exploded perspective view of the liquid ejecting head 600, which is shown upside down from a state in which it is normally used.

  The liquid ejecting head 600 includes the piezoelectric element according to the present invention. Below, the example using the piezoelectric element 100 is demonstrated as a piezoelectric element which concerns on this invention.

  As shown in FIGS. 8 and 9, the liquid ejecting head 600 includes, for example, a vibration plate 1 a, a nozzle plate 610, a flow path forming substrate 620, a piezoelectric element 100, and a housing 630. In FIG. 9, the piezoelectric element 100 is illustrated in a simplified manner.

  As shown in FIGS. 8 and 9, the nozzle plate 610 has nozzle holes 612. Ink is ejected from the nozzle holes 612. The nozzle plate 610 is provided with a plurality of nozzle holes 612, for example. In the example shown in FIG. 9, the plurality of nozzle holes 612 are formed in a line. Examples of the material of the nozzle plate 610 include silicon and stainless steel (SUS).

  The flow path forming substrate 620 is provided on the nozzle plate 610 (below in the example of FIG. 9). Examples of the material of the flow path forming substrate 620 include silicon. As the flow path forming substrate 620 partitions the space between the nozzle plate 610 and the vibration plate 1a, as shown in FIG. 9, a reservoir (liquid storage portion) 624, a supply port 626 communicating with the reservoir 624, A pressure generation chamber 622 communicating with the supply port 626 is provided. In the example shown in FIG. 9, the reservoir 624, the supply port 626, and the pressure generation chamber 622 are distinguished, but these are all liquid flow paths (for example, manifolds), Such a flow path may be designed in any way. For example, although the supply port 626 has a shape in which a part of the flow path is narrowed in the illustrated example, it can be arbitrarily formed according to the design and is not necessarily an essential configuration.

  The reservoir 624 can temporarily store ink supplied from the outside (for example, an ink cartridge) through a through hole 628 provided in the vibration plate 1a. The ink in the reservoir 624 can be supplied to the pressure generation chamber 622 via the supply port 626. The volume of the pressure generation chamber 622 changes due to the deformation of the diaphragm 1a. The pressure generation chamber 622 communicates with the nozzle hole 612, and ink or the like is discharged from the nozzle hole 612 when the volume of the pressure generation chamber 622 changes.

  Note that the reservoir 624 and the supply port 626 may be provided on a member (not shown) different from the flow path forming substrate 620 as long as the reservoir 624 and the supply port 626 communicate with the pressure generation chamber 622.

  The piezoelectric element 100 is provided on the flow path forming substrate 620 (lower in the example of FIG. 9). The piezoelectric element 100 is electrically connected to a drive circuit (not shown), and can operate (vibrate or deform) based on a signal from the drive circuit. The diaphragm 1 a can be deformed by the operation of the piezoelectric layer 30 to change the internal pressure of the pressure generation chamber 622 as appropriate.

  As shown in FIG. 9, the housing 630 can accommodate the nozzle plate 610, the flow path forming substrate 620, the vibration plate 1 a, and the piezoelectric element 100. Examples of the material of the housing 630 include resin and metal.

  The liquid ejecting head 600 includes the piezoelectric element 100 having good displacement characteristics and high reliability. Accordingly, the liquid ejecting head 600 can have good liquid ejection characteristics and high reliability.

  In the above example, the case where the liquid ejecting head 600 is an ink jet recording head has been described. However, the liquid ejecting head of the present embodiment is, for example, an electrode material ejecting head used for electrode formation such as a color material ejecting head, an organic EL display, and an FED (surface emitting display) used for manufacturing a color filter such as a liquid crystal display. It can also be used as a bio-organic matter ejecting head used for biochip manufacturing.

5. Next, the liquid ejecting apparatus according to the present embodiment will be described with reference to the drawings. FIG. 10 is a perspective view schematically showing the liquid ejecting apparatus 700 according to the present embodiment.

  The liquid ejecting apparatus 700 includes the liquid ejecting head according to the invention. Hereinafter, an example in which the liquid ejecting head 600 is used as the liquid ejecting head according to the invention will be described.

  As illustrated in FIG. 10, the liquid ejecting apparatus 700 includes a head unit 730, a driving unit 710, and a control unit 760. The liquid ejecting apparatus 700 further includes an apparatus main body 720, a paper feeding unit 750, a tray 721 on which the recording paper P is installed, a discharge port 722 for discharging the recording paper P, and an apparatus main body 720. And an operation panel 770 disposed on the upper surface.

  The head unit 730 includes an ink jet recording head (hereinafter, also simply referred to as “head”) configured from the liquid ejecting head 600 described above. The head unit 730 further includes an ink cartridge 731 that supplies ink to the head, and a transport unit (carriage) 732 on which the head and the ink cartridge 731 are mounted.

  The drive unit 710 can reciprocate the head unit 730. The drive unit 710 includes a carriage motor 741 serving as a drive source for the head unit 730, and a reciprocating mechanism 742 that receives the rotation of the carriage motor 741 and reciprocates the head unit 730.

  The reciprocating mechanism 742 includes a carriage guide shaft 744 supported at both ends by a frame (not shown), and a timing belt 743 extending in parallel with the carriage guide shaft 744. The carriage guide shaft 744 supports the carriage 732 while allowing the carriage 732 to freely reciprocate. Further, the carriage 732 is fixed to a part of the timing belt 743. When the timing belt 743 is caused to travel by the operation of the carriage motor 741, it is guided to the carriage guide shaft 744 and the head unit 730 reciprocates. During this reciprocation, ink is appropriately discharged from the head, and printing on the recording paper P is performed.

  In the present embodiment, an example of a liquid ejecting apparatus that performs printing while both the liquid ejecting head 600 and the recording paper P move is shown, but the liquid ejecting apparatus of the present invention includes the liquid ejecting head 600 and the recording. Any mechanism may be used as long as the paper P is printed on the recording paper P with its position relatively changed. Further, in the present embodiment, an example is shown in which printing is performed on the recording paper P. However, the recording medium that can be printed by the liquid ejecting apparatus of the present invention is not limited to paper, and may be cloth, film, A wide range of media such as metal can be used, and the configuration can be changed as appropriate.

  The control unit 760 can control the head unit 730, the drive unit 710, and the paper feed unit 750.

  The paper feeding unit 750 can feed the recording paper P from the tray 721 to the head unit 730 side. The paper feed unit 750 includes a paper feed motor 751 serving as a drive source thereof, and a paper feed roller 752 that rotates by the operation of the paper feed motor 751. The paper feed roller 752 includes a driven roller 752a and a drive roller 752b that face each other up and down across the feeding path of the recording paper P. The drive roller 752b is connected to the paper feed motor 751. When the paper supply unit 750 is driven by the control unit 760, the recording paper P is sent so as to pass below the head unit 730. The head unit 730, the drive unit 710, the control unit 760, and the paper feed unit 750 are provided inside the apparatus main body 720.

  The liquid ejecting apparatus 700 includes the liquid ejecting head 600 that has excellent liquid ejection characteristics and high reliability. Therefore, the liquid ejecting apparatus 700 can have good liquid ejection characteristics and high reliability.

  In addition, embodiment mentioned above and a modification are examples, Comprising: It is not necessarily limited to these. For example, it is possible to appropriately combine each embodiment and each modification.

  Although the embodiments of the present invention have been described in detail as described above, those skilled in the art will readily understand that many modifications are possible without substantially departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Base | substrate, 1a Diaphragm, 10 1st electrode layer, 20 Piezoelectric layer, 22 Upper surface of piezoelectric layer,
24 side surface of the piezoelectric layer, 30 second electrode layer, 32 first layer, 34 upper surface of the first layer,
36 second layer, 40 protective layer, 42 opening, 100 piezoelectric element, 200 piezoelectric element,
600 liquid ejecting head, 610 nozzle plate, 612 nozzle hole,
620 flow path forming substrate, 622 pressure generation chamber, 624 reservoir, 626 supply port,
628 through-hole, 630 housing, 700 liquid ejecting apparatus, 710 drive unit,
720 device main body, 721 tray, 722 discharge port, 730 head unit,
731 Ink cartridge, 732 carriage, 741 carriage motor,
742 reciprocating mechanism, 743 timing belt, 744 carriage guide shaft,
750 paper feed unit, 751 paper feed motor, 752 paper feed roller,
752a driven roller, 752b drive roller, 760 controller,
770 Operation panel

Claims (11)

A first electrode layer;
A piezoelectric layer formed above the first electrode layer;
A second electrode layer formed above the piezoelectric layer;
Including
The second electrode layer includes
A first layer formed on the upper surface of the piezoelectric layer;
A second layer formed on an upper surface of the first layer;
Have
The material of the second layer is the same as the material of the first layer,
The piezoelectric element, wherein the density of the second layer is smaller than the density of the first layer. In claim 1,
The thickness of the said 2nd layer is a piezoelectric element larger than the thickness of the said 1st layer. In claim 1 or 2,
The piezoelectric layer is formed to cover the first electrode layer,
The second layer is a piezoelectric element further formed on a side of the piezoelectric layer. In any one of Claims 1 thru | or 3,
The second electrode is a piezoelectric element whose density decreases as it goes upward.   A liquid ejecting head including the piezoelectric element according to claim 1.   A liquid ejecting apparatus including the liquid ejecting head according to claim 5. Forming a first electrode layer;
Forming a piezoelectric layer above the first electrode layer;
Forming a first layer constituting the second electrode layer on the upper surface of the piezoelectric layer by sputtering;
Forming a second layer constituting the second electrode layer on the upper surface of the first layer by sputtering;
Including
The second layer is formed of the same material as the first layer,
The method for manufacturing a piezoelectric element, wherein a sputtering power density for forming the second layer is higher than a sputtering power density for forming the first layer. In claim 7,
The method of manufacturing a piezoelectric element, wherein the step of forming the first layer and the step of forming the second layer are performed continuously. In claim 8,
In the step of forming the first layer and the step of forming the second layer,
A method for manufacturing a piezoelectric element, wherein the first layer and the second layer are formed by gradually increasing a sputtering power density. In claim 7,
Before the step of forming the second layer, further comprising the step of patterning the first layer and the piezoelectric layer,
In the step of forming the second layer,
Further, the method for manufacturing a piezoelectric element, wherein the second layer is formed on the side of the patterned piezoelectric layer. In any of claims 7 to 10,
Sputtering power density for forming the first layer is a 0.2 kW / ^{m 2} or more 10 kW / ^{m 2} or less,
The method for manufacturing a piezoelectric element, wherein a sputtering power density for forming the second layer is 20 kW / m ² or more and 80 kW / m ² or less.

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