JP7423967B2 - Electro-mechanical conversion element, liquid ejection head, liquid ejection unit, and liquid ejection device - Google Patents

Description

The present invention relates to an electro-mechanical conversion element, a liquid ejection head, a liquid ejection unit, and a device for ejecting liquid.

In a liquid ejection head, in order to improve the ejection efficiency of the head, it is required to improve the displacement characteristics of the electro-mechanical conversion element. One way to improve the displacement characteristics of an electro-mechanical transducer is to reduce the thickness of the electro-mechanical transducer film to reduce the electric field strength (voltage/electrical-mechanical transducer film) applied to the electro-mechanical transducer film. It is possible to increase the film thickness).

However, as the film thickness of the electro-mechanical transducer becomes thinner, the amount of displacement increases, but the stiffness of the electro-mechanical transducer becomes weaker, so sufficient force cannot be transmitted to the liquid to be ejected (for example, ink). As a result, the ejection efficiency does not increase.

On the other hand, Patent Document 1 discloses that an electro-mechanical conversion film and an electrode layer are alternately formed on a lower electrode. According to Patent Document 1, after ensuring sufficient rigidity as an electro-mechanical conversion film, by providing several electrode layers on the electro-mechanical conversion film, the electric field strength is increased and the ejection efficiency of the head is increased. It is also possible to do so.

However, when thin electro-mechanical transducer films and electrode layers are alternately laminated, a problem arises in controlling the crystal orientation of the electro-mechanical transducer film on the electrode layer. For example, PZT (lead zirconate titanate) is used as the electro-mechanical conversion film to ensure a high piezoelectric constant and aim to control the (100) orientation of PZT, but the (100) orientation control of PZT on the electrode layer There is a problem that it is difficult to obtain sufficient piezoelectric performance. Therefore, sufficient displacement characteristics are not obtained, and the ejection efficiency of the head cannot be improved. Furthermore, in the prior art, other crystal peaks such as PZT (110) orientation are also observed, and a perfect PZT (100) crystal film is not obtained. For this reason, there was a problem in that sufficient piezoelectric performance was not obtained, and sufficient displacement characteristics were not obtained.

Therefore, an object of the present invention is to provide an electro-mechanical transducer element in which an electro-mechanical transducer film having good crystal orientation can be obtained and high displacement characteristics can be obtained.

In order to solve the above problems, the electro-mechanical transducer of the present invention has electro-mechanical transducer films and internal electrode films alternately laminated on a lower electrode, and the electro-mechanical transducer film formed on the top. An electro-mechanical conversion element having an upper electrode formed thereon, wherein the internal electrode film is not formed between the lower electrode and the electro-mechanical conversion film closest to the lower electrode, The electro-mechanical conversion film closest to the lower electrode has a (100) orientation rate of 95% or more, a first interlayer film is formed on the lower electrode and the upper electrode, and the electro-mechanical conversion film is The area of the conversion film and the internal electrode film gradually decreases from the lower electrode side to the upper electrode side when comparing each layer. and a wiring drawn out from the upper electrode, and these wirings are drawn out through the first interlayer film, and the wiring drawn out from the lower electrode, the wiring drawn out from the internal electrode film, and the upper electrode. A part of the wiring drawn out from the electrode is present on the first interlayer film .

According to the present invention, an electro-mechanical transducer film having good crystal orientation can be obtained, and an electro-mechanical transducer element with high displacement characteristics can be provided.

1 is a schematic cross-sectional view (A) of an example of an electro-mechanical conversion element according to the present invention, and a schematic cross-sectional view (B) of an electro-mechanical conversion element in a conventional example. FIG. 3 is a diagram showing an example of the relationship between the (100) orientation ratio of the first layer electro-mechanical conversion film and the (100) orientation ratio of the total electro-mechanical conversion film. 2 is a graph showing the diffraction peak position for the (200) plane of the electromechanical transducer film obtained by θ-2θ measurement using X-ray diffraction. FIG. 3 is a schematic cross-sectional view of another example of the electro-mechanical conversion element according to the present invention. FIG. 3 is a schematic cross-sectional view of another example of the electro-mechanical conversion element according to the present invention. FIG. 3 is a schematic cross-sectional view of another example of the electro-mechanical conversion element according to the present invention. FIG. 3 is a schematic plan view of another example of the electro-mechanical conversion element according to the present invention. FIG. 3 is a schematic cross-sectional view of another example of the electro-mechanical conversion element according to the present invention. FIG. 3 is a schematic plan view of another example of the electro-mechanical conversion element according to the present invention. 1 is a schematic cross-sectional view of an example of a liquid ejection head according to the present invention. FIG. 7 is a schematic cross-sectional view of another example of the liquid ejection head according to the present invention. 1 is an explanatory plan view of a main part of an example of a device for discharging liquid according to the present invention; FIG. FIG. 2 is a side view illustrating a main part of an example of a device for discharging liquid according to the present invention. FIG. 1 is a schematic diagram showing an example of a liquid ejection unit according to the present invention. FIG. 7 is a schematic diagram showing another example of the liquid ejection unit according to the present invention. FIG. 1 is a perspective view showing an example of a device that discharges liquid. FIG. 2 is a side view showing an example of a device that discharges liquid.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electro-mechanical transducer, a liquid ejection head, a liquid ejection unit, and a liquid ejection device according to the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the embodiments shown below, and may be modified within the scope of those skilled in the art, such as other embodiments, additions, modifications, deletions, etc. These are also included within the scope of the present invention as long as they exhibit the functions and effects of the present invention.

(Electro-mechanical conversion element)
In the electro-mechanical conversion element of the present invention, electro-mechanical conversion films and internal electrode films are alternately laminated on a lower electrode, and an upper electrode is formed on the electro-mechanical conversion film formed at the top. In the electro-mechanical conversion element, the internal electrode film is not formed between the lower electrode and the electro-mechanical conversion film closest to the lower electrode, and the internal electrode film is not formed between the lower electrode and the electro-mechanical conversion film closest to the lower electrode. - The mechanical transducer film is characterized by a (100) orientation rate of 95% or more.

FIG. 1 shows an example of a cross-sectional view of an electro-mechanical conversion element in this embodiment and an example of a cross-sectional view of a conventional electro-mechanical conversion element. In FIG. 1, a substrate 10, a diaphragm 12, a lower electrode 14, an electro-mechanical conversion film 16, an internal electrode 18, and an upper electrode 20 are illustrated.

FIG. 1(A) shows an example of the electro-mechanical transducer of this embodiment, in which electro-mechanical transducer films 16 and internal electrode films 18 are alternately laminated on the lower electrode 14, and an electro-mechanical transducer film 18 is formed on the top. An upper electrode 20 is formed on the electro-mechanical conversion film 16. Here, each layer of the electro-mechanical conversion film 16 is represented as an electro-mechanical conversion film 16a, 16b, . . . 16x, and each layer of the internal electrode film is represented as an internal electrode film 18a, 18b, . Note that when each layer of the electro-mechanical conversion film is not distinguished, it may be simply referred to as the electro-mechanical conversion film 16, and when each layer of the internal electrode film is not distinguished, it may be simply referred to as the internal electrode film 18.

On the other hand, in the conventional electro-mechanical conversion element, no internal electrode film is formed, but an electro-mechanical conversion film 16 is formed on the lower electrode 14, and an upper electrode 20 is further formed on the outermost surface.

Even if the same electro-mechanical conversion film is formed in the present embodiment (FIG. 1(A)) and the conventional example (FIG. 1(B)) when the same voltage is applied, the present embodiment By sandwiching the internal electrode films as shown in the figure, the thickness of the electro-mechanical conversion film between the electrodes becomes thinner, and the electric field strength increases. Therefore, the amount of deformation of the electro-mechanical transducer film is larger in this embodiment.

Furthermore, whether the same crystal orientation film is obtained in both cases is not the case. It has been found that the crystal orientation of the subsequent electro-mechanical conversion film, that is, the upper layer, changes depending on the material. The electro-mechanical conversion film preferably has a (100) crystal orientation, and in this case, high displacement characteristics can be obtained. A detailed study revealed that the crystal orientation of the electro-mechanical conversion film 16a can be controlled to the (100) crystal orientation by having a (100) orientation rate of 95% or more. I understand.

FIG. 2 shows the relationship between the orientation rate (also referred to as crystal orientation rate, degree of orientation, etc.) of the first layer electro-mechanical conversion film and the total orientation rate of the electro-mechanical conversion film. In Figure 2, the (100) orientation rate of the first layer electro-mechanical conversion film (PZT is taken as an example here) is taken as the horizontal axis, and the vertical axis is the (100) orientation rate of the total electro-mechanical conversion film. I have to. Moreover, in FIG. 2, the material of the internal electrode film is changed and plotted. Note that the total orientation ratio of the electro-mechanical conversion film is a value obtained by calculating an average value using the orientation ratio of the electro-mechanical conversion film of each layer.

As shown in the figure, it can be seen that if the (100) orientation rate is low at the time of the first layer, the (100) orientation rate of the PZT formed thereafter is low. Although it depends on the material of the internal electrode film, in order to increase the total (100) orientation ratio of PZT, it is preferable that the (100) orientation ratio of the first layer PZT is 95% or more.

As a result of detailed studies by the present inventors, the electro-mechanical transducer films and internal electrode films are alternately laminated on the lower electrode, and the electro-mechanical transducer film closest to the lower electrode is oriented in (100) orientation. By setting the ratio to 95% or more, an electro-mechanical transducer film having good crystal orientation can be obtained, and an electro-mechanical transducer element with high displacement characteristics can be provided.
The details of the electro-mechanical conversion element in this embodiment will be explained below.

<Substrate>
As the substrate, it is preferable to use a silicon single crystal substrate, and it is usually preferable to have a thickness of 100 to 600 μm. There are three types of plane orientation: (100), (110), and (111), but (100) and (111) are generally widely used in the semiconductor industry, and (100) is also mainly used in liquid ejection heads. ) can be used.

Further, when manufacturing a pressure chamber, a silicon single crystal substrate is processed using etching, and anisotropic etching is generally used as the etching method in this case. Note that anisotropic etching utilizes the property that the etching rate differs depending on the plane orientation of the crystal structure.

For example, in anisotropic etching performed by immersion in an alkaline solution such as KOH, the etching rate for the (111) plane is about 1/400 of that for the (100) plane. Therefore, with the (100) plane orientation, a structure with an inclination of about 54° can be produced, whereas with the (110) plane direction, a deep groove can be dug. Therefore, since the arrangement density can be increased while maintaining rigidity, a single crystal substrate having a (110) plane orientation may be used in this embodiment as well. However, in this case, it should be noted that the mask material SiO ₂ is also etched.

<Vibration version>
The diaphragm is deformed and displaced by the force generated by an electro-mechanical transducer film (for example, PZT (lead zirconate titanate)), thereby ejecting ink droplets within the pressure chamber. Therefore, it is preferable that the diaphragm has a predetermined strength. Specifically, examples include those made of Si, SiO ₂ , Si ₃ N ₄ , etc., by a CVD method or the like. Further, as the material of the diaphragm, it is preferable to select a material whose linear expansion coefficient is close to that of the lower electrode and the electro-mechanical conversion film.

In particular, when using PZT as an electro-mechanical conversion membrane, the linear expansion coefficient of PZT is 5×10 ^-6 (1/K) ~ 5×10 ^-6 (1/K), which is close to PZT's 8×10 -6 (1/K). Preferably, a material with a coefficient of linear expansion of 10×10 ⁻⁶ (1/K) is selected. It is more preferable to select a material having a linear expansion coefficient of 7×10 ⁻⁶ (1/K) to 9×10 ⁻⁶ (1/K).

Specific materials for the diaphragm include aluminum oxide, zirconium oxide, iridium oxide, ruthenium oxide, tantalum oxide, hafnium oxide, osmium oxide, rhenium oxide, rhodium oxide, palladium oxide, and compounds thereof. These can be manufactured using a spin coater using a sputtering method or a Sol-gel method.

The thickness of the diaphragm is preferably 0.1 to 10 μm, more preferably 0.5 to 3 μm. If it is within this range, the pressure chamber will be easier to process and the diaphragm will be more likely to be deformed and displaced.

<Lower electrode>
As the lower electrode, platinum, which has high heat resistance and low reactivity as a metal material, can be used. However, platinum may not have sufficient barrier properties against lead, and in that case, platinum group elements such as iridium or platinum-rhodium, or alloy films of these may be used. .

Furthermore, when platinum is used as the lower _{electrode ,} the adhesion to _the underlying diaphragm ₍ particularly SiO ₂ ) may _deteriorate; It is preferable to laminate them first. As a manufacturing method, a vacuum film formation method such as a sputtering method or a vacuum evaporation method is generally used. The film thickness is preferably 0.05 to 1 μm, more preferably 0.1 to 0.5 μm.

Further, it is preferable to form a seed layer of SrRuO ₃ , LaNiO ₃ , PbTiO ₃ or PZT on the lower electrode as a seed material for controlling the crystal orientation of the electro-mechanical conversion film. Among these, it is preferable to use PbTiO ₃ because it facilitates making the electro-mechanical conversion film (100) oriented.

<Electro-mechanical conversion film, internal electrode film and seed layer>
As the electromechanical conversion film, lead zirconate titanate (PZT) can be suitably used. PZT is a solid solution of lead zirconate (PbZrO ₃ ) and lead titanate (PbTiO ₃ ), and the characteristics of PZT vary depending on the ratio of PbZrO ₃ and PbTiO ₃ . A composition that generally exhibits excellent piezoelectric properties is, for example, a ratio of PbZrO ₃ and PbTiO ₃ of 53:47, which is represented by the chemical formula: Pb(Zr _0.53 , Ti _0.47 )O ₃ It can be expressed as PZT (53/47) and is generally indicated as PZT (53/47).

Examples of complex oxides other than PZT include barium titanate, and in this case, it is also possible to prepare a barium titanate precursor solution by using barium alkoxide and titanium alkoxide compounds as starting materials and dissolving them in a common solvent. be.

The composition ratio of Pb/(Zr+Ti) is preferably 0.9 or more and 1.3 or less, more preferably 1.0 or more and 1.2 or less. If it is 0.9 or more, a shortage of Pb can be prevented and a sufficient amount of displacement can be ensured. Moreover, when it is 1.3 or less, it is possible to prevent Pb from becoming excessive and prevent dielectric breakdown.

Regarding the composition ratio of Zr/Ti, when expressed as Ti/(Zr+Ti), it is preferably 0.40 or more and 0.55 or less, and more preferably 0.45 or more and 0.53 or less. By adjusting these composition ratios, the peak position and peak asymmetry of the PZT (200) plane differ in the θ-2θ measurement as shown in FIG. 3.
When Ti/(Zr+Ti) is 0.40 or more, it is possible to prevent the amount of displacement accompanied by rotational strain from decreasing. When Ti/(Zr+Ti) is 0.55 or less, the amount of displacement due to piezoelectric strain can be prevented from decreasing, and the amount of displacement can be easily ensured.

Examples of the method for producing the electro-mechanical conversion film include the Sol-gel method. For example, when producing PZT by the Sol-gel method, lead acetate, zirconium alkoxide, and titanium alkoxide compounds are first used as starting materials. Then, a PZT precursor solution can be prepared by dissolving it in methoxyethanol, which is a common solvent, to obtain a homogeneous solution. Since metal alkoxide compounds are easily hydrolyzed by moisture in the atmosphere, an appropriate amount of acetylacetone, acetic acid, diethanolamine, etc. may be added to the precursor solution as a stabilizer.

The thickness of one layer of the electro-mechanical conversion film is preferably 0.2 to 3 μm, more preferably 0.5 to 2 μm. When the thickness is 0.2 μm or more, the electric field strength is prevented from becoming too large and the withstand voltage is easily ensured, so that problems such as dielectric withstand voltage can be prevented. When it is 3 μm or less, the electric field strength is prevented from becoming too small, and it becomes easier to ensure sufficient displacement.

Note that the film thickness of one layer means the thickness of a film when the electro-mechanical conversion film is continuously formed without forming any other layer. For example, when an electro-mechanical conversion film is formed in three consecutive layers, the three consecutively formed layers are collectively considered as the film thickness of one layer.

In the electro-mechanical conversion element of this embodiment, electro-mechanical conversion films and internal electrode films are alternately laminated, and the total thickness of the electro-mechanical conversion films is preferably 1 to 10 μm, and 2 to 2 μm. More preferably, the thickness is 5 μm. When the thickness is 1 μm or more, it becomes easier to ensure sufficient rigidity and ejection force. When the thickness is 10 μm or less, film stress can be prevented from becoming too large, and reliability problems such as cracks can be suppressed.

In this embodiment, electro-mechanical conversion films and internal electrode films are alternately laminated on the lower electrode, and the internal electrode film is formed between the lower electrode and the electro-mechanical conversion film closest to the lower electrode. First, the (100) orientation rate of the electro-mechanical conversion film closest to the lower electrode is set to 95% or more. As a result, an electro-mechanical transducer film having good crystal orientation can be obtained, and an electro-mechanical transducer element with high displacement characteristics can be provided.

In this embodiment, the (100) orientation ratio of the electro-mechanical conversion film is determined using the EBSD (Electron Back Scattered Diffraction Pattern) method. For the cross section of the electro-mechanical conversion element on which the electro-mechanical conversion film is formed, backscattered electron diffraction is analyzed using the EBSD method to perform orientation analysis for each crystal grain and calculate the orientation rate. By the above measurement, an image having regions with (100) orientation and regions other than (100) orientation was obtained, and the (100) orientation rate was
(100) Orientation rate [%] = (100) Area of oriented crystal grain region/Area of total region x 100
Calculated by By performing such measurements on the first electro-mechanical conversion film and other electro-mechanical conversion films, the (100) orientation rate of each layer is determined.

As described above, the electro-mechanical conversion film closest to the lower electrode is, for example, the first electro-mechanical conversion film 16a in FIG. 1(A). When the (100) orientation rate of the electro-mechanical transducer film closest to the lower electrode is 95% or more, the crystal orientation of the entire electro-mechanical transducer film can be easily controlled to the (100) crystal orientation. As a result, an electro-mechanical transducer film having good crystal orientation can be obtained, and an electro-mechanical transducer element with high displacement characteristics can be provided.

Note that the electro-mechanical conversion film closest to the lower electrode is sometimes referred to as the first layer electro-mechanical conversion film. The term "first layer" refers to the electro-mechanical conversion film closest to the lower electrode, which is a layer in which the electro-mechanical conversion film is continuously formed without forming any other layer.

In order to make the (100) orientation rate of the electro-mechanical transducer film closest to the lower electrode 95% or more, it is possible to change it as appropriate, but for example, it is possible to form a layer having the role of a seed on the lower electrode. is preferred. In particular, a layer made of PbTiO ₃ (also referred to as a PT seed layer) is formed between the lower electrode and the electro-mechanical conversion film closest to the lower electrode, and the layer made of PbTiO ₃ is - It is preferable to form it in contact with the mechanical conversion film. In this case, the (100) orientation rate of the electro-mechanical conversion film formed on the PT seed layer can be further increased. In particular, when Pt is used as the lower electrode, the (100) orientation rate of the electro-mechanical conversion film can be further increased by providing a PT seed layer on the lower electrode layer. Further, the PT seed layer is particularly effective even when using a structure in which TiO ₂ is laminated as the lower electrode and Pt is further laminated thereon.

As for the overall (100) orientation rate of the electro-mechanical conversion film, it is preferable that the average value of the (100) orientation rate determined using the (100) orientation rate of each layer is 75% or more, and 90% or more. It is more preferably at least 95%, even more preferably at least 99%. When it is 75% or more, particularly 90% or more, good piezoelectric strain can be obtained and the amount of displacement can be easily secured. Further, variations in crystal orientation within the chip can be suppressed, and variations in ejection can also be suppressed when a head is formed.

As the internal electrode film, for example, Pt, SrRuO, PbTiO ₃ or the like can be used. Among these, it is preferable to use SrRuO. It is also preferable to form an internal electrode film by laminating SrRuO and Pt in order from the lower electrode side. In this case, the (100) orientation rate of the electro-mechanical conversion film laminated thereon can be further increased.
Note that the case where SrRuO and Pt are laminated in order from the lower electrode side is sometimes expressed as "SrRuO/Pt".

By using SrRuO (or SrRuO/Pt), which has a very small difference in lattice constant from PZT, as the internal electrode film, SrRuO becomes (100) oriented, and Pt originally has a (111) preferential orientation, but It is possible to make Pt prepared in a (100) crystal orientation. Therefore, the electro-mechanical conversion film formed on the internal electrode film also inherits the crystal information, making it possible to further increase the (100) orientation rate.

Note that the same can be said for PbTiO ₃ , and since the difference in lattice constant between Pt and PZT is slightly large, providing SrRuO or PbTiO ₃ in between makes it easier for the underlying crystal information to be carried over. The lattice constants are as follows: PZT<PbTiO ₃ and SrRuO<Pt.

In FIG. 2 described above, the relationship between the orientation ratio of the first-layer electro-mechanical conversion film and the total orientation ratio of the electro-mechanical conversion film is plotted by changing the material of the internal electrode film. As shown in the figure, the tendency differs depending on the material of the internal electrode layer, and the total electromechanical conversion film (100 ) The orientation rate is high.

The thickness of one layer of the internal electrode film is preferably 10 nm to 200 nm, more preferably 20 nm to 100 nm.

In this way, it is preferable to change the structure of the internal electrode film as appropriate, and improve the (100) orientation ratio of the first layer electro-mechanical conversion film and the overall (100) orientation ratio of the electro-mechanical conversion film. Can be done.

In this embodiment, it is preferable that a seed layer is formed on the internal electrode film. As the seed layer, SrRuO, PbTiO ₃ or the like can be used. By using the seed layer, it becomes easier to control the (100) orientation of the electro-mechanical conversion film formed thereon.

FIG. 4 shows a schematic cross-sectional view of an example in which a seed layer is formed. As illustrated, since a plurality of internal electrode films 18 are formed in this embodiment, a plurality of seed layers 22 may also be formed.

In addition, in FIG. 2 described above, the relationship between the orientation rate of the first layer electro-mechanical conversion film and the total orientation rate of the electro-mechanical conversion film is plotted by changing the presence or absence and type of the seed layer. ing. As shown in the figure, the tendency differs depending on the presence or absence of the seed layer and the material, and when the seed layer is formed, the total (100) orientation rate of the electro-mechanical conversion film is high. For example, when comparing SrRuO/Pt (without seed layer) and SrRuO/Pt/SrRuO (with seed layer), SrRuO/Pt/SrRuO with a seed layer has a total electromechanical conversion film (100 ) The orientation rate is high.

In the example shown here, the total (100) orientation ratio of the electro-mechanical conversion film is different depending on whether SrRuO is used as the seed layer or PbTiO ₃ is used as the seed layer. Therefore, it is preferable to appropriately select the type of seed layer.

Note that, for example, "SrRuO/Pt/PbTiO ₃ " means a structure in which SrRuO and Pt are laminated as an internal electrode film from the lower electrode side, and PbTiO ₃ is further laminated thereon as a seed layer.

The thickness of one seed layer is preferably 1 nm to 20 nm, more preferably 3 nm to 10 nm.

In this embodiment, it is preferable that the (100) orientation rate of the electro-mechanical conversion film closest to the upper electrode is 95% or more. In this case, the overall (100) orientation ratio of the electro-mechanical transducer film is large, good piezoelectric strain can be obtained, and the amount of displacement can be easily ensured.

<Top electrode>
As the upper electrode, for example, Pt, SrRuO, LaNiO ₃ or the like can be used. Among these, preferred is a configuration in which an oxide electrode layer and a layer made of Pt are laminated in order from the bottom layer, such as a configuration in which SrRuO and Pt are laminated or a configuration in which LaNiO ₃ and Pt are laminated. Since the adhesion of Pt itself is low, it is necessary to add an oxide electrode layer in between to improve the adhesion and to also have the function of suppressing the performance deterioration during continuous operation due to oxygen vacancies in PZT. can.

The thickness of the upper electrode is preferably 10 nm to 200 nm, more preferably 20 nm to 100 nm.

<Other configuration examples>
Next, other configuration examples of the electro-mechanical transducer of this embodiment will be described together with wiring, interlayer films, and the like. This example will be explained using FIG. 5. Similar to FIG. 1, FIG. 5 shows a schematic cross-sectional view of the electro-mechanical conversion element.

The area of the electro-mechanical conversion film and the internal electrode film may gradually decrease from the lower electrode side to the upper electrode side when comparing each layer, as shown in FIG. 5, for example. This makes it easier to form wiring drawn out from the lower electrode, internal electrode film, and upper electrode.

The method of forming the area so that it gradually decreases can be changed as appropriate, but for example, after fabricating up to the upper electrode, etching is performed from the upper electrode to produce the shape shown in the figure. can do. In this case, the contact hole after the interlayer film has been formed can be formed by a single etching process, thereby simplifying the process.

In this example, examples in which wiring is formed are shown in FIGS. 6 and 7. FIG. 6 is a cross-sectional view when wiring is formed in FIG. 5, and FIG. 7 is a schematic plan view in FIG. 6. 6 and 7 show a wiring 26a drawn out from the lower electrode 14, a wiring 26b drawn out from the internal electrode film 18, and a wiring 26c drawn out from the upper electrode 20, and in FIG. 32 is shown.

Reference numerals 28a', 28b', and 28c' indicate locations corresponding to contact hole portions in the wiring. Symbols 28a', 28b', and 28c' correspond to wirings 26a, 26b, and 26c, respectively.

In addition, in FIGS. 6 and 7, two internal electrode films 18 (internal electrode film 18a, internal electrode film 18b) are shown as an example, and wiring is formed on each, but only one of the wirings is marked with a symbol ( 26b), and the reference numeral is omitted for the other wiring.

In this way, the area of the electro-mechanical conversion film 16 and internal electrode film 18 gradually decreases from the lower electrode 14 side to the upper electrode 20 side, so that the wiring drawn out from the lower electrode, internal electrode film, and upper electrode It becomes easier to form 26a, 26b, and 26c.

In FIG. 7, it is shown that the electro-mechanical conversion film has a longitudinal direction and a transverse direction in a direction ( plane direction) perpendicular to the stacking direction (the same applies to the internal electrode film). In the example shown here, the wirings 26a, 26b, and 26c are drawn out to either the left or right along the longitudinal direction.

Further, as shown in the figure, a portion of the wiring 26a drawn out from the lower electrode 14, the wiring 26b drawn out from the internal electrode film 18, and the wiring 26c drawn out from the upper electrode 20 exist on the same plane. Here, it is formed on the first interlayer film 32. This provides advantages such as simplifying the wiring layout and preventing short circuits.

The wiring is preferably made of a metal electrode material made of, for example, Ag alloy, Cu, Al, Au, Pt, or Ir. As a manufacturing method, for example, a sputtering method or a spin coating method is used for manufacturing, and then a desired pattern is obtained by photolithography etching or the like.
The thickness of the wiring is preferably 0.1 to 20 μm, more preferably 0.2 to 10 μm. Setting the thickness to 0.1 μm or more prevents the resistance from becoming too large and makes it easier to flow a sufficient current through the electrode. Thereby, the ejection stability of the head can be improved. By setting the thickness to 20 μm or less, it is possible to prevent the process time from becoming too long.

The contact resistance at the contact hole portion (for example, 10 μm x 10 μm) is preferably 10 Ω or less for the common electrode, and 1 Ω or less for the individual electrodes and internal electrode films. More preferably, the common electrode is more preferably 5Ω or less, and the individual electrodes and internal electrode layers are more preferably 0.5Ω or less. When the current is within the above range, sufficient current can be supplied, making it easier to prevent problems when ejecting ink.
In this embodiment, the upper electrode may be an individual electrode and the lower electrode may be a common electrode, or the upper electrode may be a common electrode and the lower electrode may be an individual electrode (see FIG. 11 described below).

The first interlayer film (also referred to as the first insulating film) is preferably made of a material that prevents damage to the electro-mechanical transducer due to film formation and etching processes, and that is difficult for atmospheric moisture to pass through. , is preferably a dense inorganic material. With organic materials, it is necessary to increase the film thickness in order to obtain sufficient protection performance. If the film is thick, the vibration displacement of the diaphragm will be significantly inhibited, resulting in an inkjet head with poor ejection performance.

In order to obtain high protective performance with a thin film, it is preferable to use an oxide, nitride, or carbide film. At this time, it is preferable to select a material that has high adhesion to the electrode material, the electro-mechanical conversion film material, and the diaphragm material, which are the base of the first interlayer film.

Furthermore, it is preferable to select a film forming method that does not damage the electro-mechanical transducer. The plasma CVD method, in which a reactive gas is turned into plasma and deposited on a substrate, and the sputtering method, in which a film is formed by colliding plasma with a target material to form a film, may cause damage, so care should be taken. Preferred film-forming methods include vapor deposition, ALD (Atomic Layer Deposition), and the like, with ALD being preferred because it allows for a wide selection of usable materials.

Preferred materials for the first interlayer film include, for example, oxide films used in ceramic materials such as Al ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ , Ta ₂ O ₃ , and TiO ₂ . In particular, by using these materials and the ALD method, a thin film with extremely high film density can be produced and damage during the process can be suppressed.

The thickness of the first interlayer film is preferably thin enough to ensure the protection performance of the electro-mechanical conversion element, and preferably as thin as possible so as not to inhibit the displacement of the diaphragm. For example, the film thickness is preferably 20 nm to 100 nm. When the thickness is 20 nm or more, the function as a protective layer can be ensured, and the performance of the electro-mechanical conversion element can be prevented from deteriorating. When the thickness is 100 nm or less, it is possible to prevent the displacement of the diaphragm from decreasing and improve the ejection efficiency.

In the process of manufacturing the element, the contact hole can be created by one etching after the first interlayer film is created, so the process can be simplified. After that, wiring is produced on the interlayer film.

In this embodiment, a second interlayer film (also referred to as a second insulating film) may be formed. A diagram for explaining this example is shown in FIG. FIG. 8 shows an example in which the second interlayer film 34 is formed in FIG. 6. Also shown here are contact holes 28a, 28b, and 28c.

Note that the second interlayer film on the electro-mechanical transducer and the diaphragm around it may be opened. In this case, it is possible to prevent the vibration displacement of the diaphragm from being significantly inhibited, and to improve discharge efficiency and reliability.

The second interlayer film can be used, for example, as a passivation layer that functions as a protective layer that protects the wiring of the lower electrode and the wiring of the upper electrode. As shown in the figure, the electrodes are covered except for the wiring portions. By using the second interlayer film, for example, inexpensive Al or an alloy material containing Al as a main component can be used as the electrode material.

Any inorganic or organic material can be used as the second interlayer film, but it is preferable to use a material with low moisture permeability. Examples of inorganic materials include oxides, nitrides, carbides, etc., and examples of organic materials include polyimide, acrylic resin, urethane resin, etc. In the case of organic materials, it is necessary to form a thick film, which may not be suitable for patterning. Therefore, it is preferable to use an inorganic material that can exhibit a wiring protection function in a thin film, and it is particularly preferable to use Si ₃ N ₄ on Al wiring because it is a proven technology in semiconductor devices.

Any method can be used for film formation, such as CVD and sputtering. Considering step coverage of pattern forming areas such as electrode forming areas, it is preferable to use CVD, which allows for isotropic film formation.

The thickness of the second interlayer film is preferably such that it does not cause dielectric breakdown due to the voltage applied to the wiring between the lower electrode and the upper electrode, and the electric field strength applied to the second interlayer film does not cause dielectric breakdown. It is preferable to set it within a range. Further, in consideration of the surface properties of the base of the second interlayer film, pinholes, etc., the film thickness is preferably 200 nm or more, more preferably 500 nm or more. When the thickness is 200 nm or more, a sufficient passivation function can be exhibited, and disconnection due to corrosion of the wiring material can be prevented, and reliability of inkjet can be prevented from decreasing.

Next, still another configuration example in this embodiment will be described using FIG. 9. Similar to FIG. 7, FIG. 9 shows a plan view of the electro-mechanical conversion element in this embodiment.
In this example, the wires are drawn out to the left and right along the longitudinal direction of the electro-mechanical conversion film (or internal electrode film), and when the wires are numbered from the lower electrode side to the upper electrode side, odd numbered wires are The even-numbered wires are pulled out in the same direction, and the even-numbered wires are pulled out in a different direction than the odd-numbered wires.

In FIG. 9, the wiring 26a drawn out from the lower electrode 14, the wiring 26b drawn out from the internal electrode film 18 (here, 26b1 and 26b2), and the wiring 26c drawn out from the upper electrode 20 are numbered. In the example shown in FIG. 9, the numbers of the wirings 26a, 26b1, 26b2, and 26c are 1, 2, 3, and 4, respectively. Then, the odd-numbered wirings 1 and 3 are drawn out in the same direction, and the even-numbered wirings 2 and 4 are drawn out in a different direction from the odd-numbered wirings. In other words, when counting from the lower electrode, the wires are divided into odd-numbered wires (n+1) and even-numbered wires (2n), and the odd-numbered wires and even-numbered wires are combined into one wire in the middle, as shown in FIG. There is.

In this way, by drawing out (routing) the wiring from the left and right along the longitudinal direction of the electro-mechanical conversion film, it is possible to simplify the wiring layout.

In the above example, wiring and interlayer films were illustrated and explained in an example in which the areas of the electro-mechanical conversion film and the internal electrode film were gradually reduced, but the present invention is not limited to this. In other words, the configuration in which the wiring, the first interlayer film, and the second interlayer film are formed is limited to the case where the areas of the electro-mechanical conversion film and the internal electrode film are gradually reduced, as shown in FIG. Instead, it is also applicable to the configuration shown in FIG.

(Liquid ejection head, liquid ejection unit, and device that ejects liquid)
Next, a liquid ejection head, a liquid ejection unit, and a device for ejecting liquid according to the present invention will be described.

The liquid ejection head of the present invention includes a nozzle for ejecting liquid, a pressurizing chamber communicating with the nozzle, and a pressure generating means for generating pressure in the liquid in the pressurizing chamber. The electro-mechanical conversion element of the invention is used.

The liquid ejection unit of the invention includes the liquid ejection head of the invention. Further, a head tank that stores liquid to be supplied to the liquid ejection head, a carriage that mounts the liquid ejection head, a supply mechanism that supplies liquid to the liquid ejection head, a maintenance recovery mechanism that maintains and recovers the liquid ejection head, The liquid ejection head may be integrated with at least one of the main scanning movement mechanisms that move the liquid ejection head in the main scanning direction.

A device for discharging a liquid according to the present invention includes a liquid discharge head according to the present invention or a liquid discharge unit according to the present invention.

First, an example of the liquid ejection head of the present invention is shown in FIGS. 10 and 11. FIG. 10 shows a nozzle 11, a pressurizing chamber 41 communicating with the nozzle 11, and a nozzle plate 43 having the nozzle 11. Further, FIG. 11 is an example in which the liquid ejection heads shown in FIG. 10 are connected. In this embodiment, the upper electrode 20 may be an individual electrode and the lower electrode 14 may be a common electrode as shown in FIG. 11(A), or the upper electrode 20 may be a common electrode as shown in FIG. 11(B). , the lower electrode 14 may be an individual electrode.

Next, an example of a device for discharging liquid according to the present invention will be described with reference to FIGS. 12 and 13. FIG. 12 is a plan view of the main part of the device, and FIG. 13 is a side view of the main part of the device.

This device is a serial type device, and a carriage 403 is reciprocated in the main scanning direction by a main scanning movement mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, and the like. The guide member 401 spans between the left and right side plates 491A and 491B, and movably holds the carriage 403. Then, the carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via a timing belt 408 stretched between a driving pulley 406 and a driven pulley 407 .

This carriage 403 is equipped with a liquid ejection unit 440 that integrates a liquid ejection head 404 and a head tank 441 according to the present invention. The liquid ejection head 404 of the liquid ejection unit 440 ejects liquid of each color, for example, yellow (Y), cyan (C), magenta (M), and black (K). Further, the liquid ejection head 404 has a nozzle array made up of a plurality of nozzles 11 arranged in a sub-scanning direction perpendicular to the main scanning direction, and is mounted with the ejection direction facing downward.

A supply mechanism 494 for supplying liquid stored outside the liquid ejection head 404 to the liquid ejection head 404 supplies the liquid stored in the liquid cartridge 450 to the head tank 441 .

The supply mechanism 494 includes a cartridge holder 451, which is a filling section into which the liquid cartridge 450 is mounted, a tube 456, a liquid feeding unit 452 including a liquid feeding pump, and the like. Liquid cartridge 450 is removably attached to cartridge holder 451. Liquid is fed from the liquid cartridge 450 to the head tank 441 by a liquid feeding unit 452 via a tube 456 .

This device includes a transport mechanism 495 for transporting paper 410. The conveyance mechanism 495 includes a conveyance belt 412 that is a conveyance means, and a sub-scanning motor 416 for driving the conveyance belt 412.

The conveyance belt 412 attracts the paper 410 and conveys it to a position facing the liquid ejection head 404 . This conveyance belt 412 is an endless belt, and is stretched between a conveyance roller 413 and a tension roller 414. Adsorption can be performed by electrostatic adsorption, air suction, or the like.

The conveyance belt 412 rotates in the sub-scanning direction by rotationally driving the conveyance roller 413 via the timing belt 417 and timing pulley 418 by the sub-scanning motor 416.

Further, a maintenance and recovery mechanism 420 that maintains and recovers the liquid ejection head 404 is arranged on one side of the carriage 403 in the main scanning direction and on the side of the conveyor belt 412.

The maintenance and recovery mechanism 420 includes, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzles 11 are formed) of the liquid ejection head 404, a wiper member 422 that wipes the nozzle surface, and the like.

The main scanning movement mechanism 493, the supply mechanism 494, the maintenance and recovery mechanism 420, and the transport mechanism 495 are attached to a housing including side plates 491A, 491B and a back plate 491C.

In this apparatus configured in this manner, the paper 410 is fed onto the conveyor belt 412 and adsorbed, and the paper 410 is conveyed in the sub-scanning direction by the rotational movement of the conveyor belt 412.

Therefore, by driving the liquid ejection head 404 according to the image signal while moving the carriage 403 in the main scanning direction, liquid is ejected onto the stationary paper 410 to form an image.

In this manner, since this apparatus includes the liquid ejection head according to the present invention, it is possible to stably form high-quality images.

Next, another example of the liquid ejection unit according to the present invention will be described with reference to FIG. 14. FIG. 14 is an explanatory plan view of the main parts of the unit.

This liquid ejection unit includes, among the members constituting the liquid ejecting device, a housing portion composed of side plates 491A, 491B and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and a liquid ejection unit. It is composed of a discharge head 404.

Note that it is also possible to configure a liquid ejection unit in which at least one of the above-mentioned maintenance and recovery mechanism 420 and supply mechanism 494 is further attached to, for example, the side plate 491B of this liquid ejection unit.

Next, still another example of the liquid ejection unit according to the present invention will be described with reference to FIG. 15. FIG. 15 is an explanatory front view of the unit.

This liquid ejection unit includes a liquid ejection head 404 to which a channel component 444 is attached, and a tube 456 connected to the channel component 444.

Note that the channel component 444 is arranged inside the cover 442. A head tank 441 can also be included instead of the flow path component 444. Further, a connector 443 for electrically connecting with the liquid ejection head 404 is provided on the upper part of the flow path component 444.

In the present application, a "device for ejecting liquid" is a device that includes a liquid ejection head or a liquid ejection unit and drives the liquid ejection head to eject liquid. Devices that eject liquid include not only devices that are capable of ejecting liquid onto objects to which liquid can adhere, but also devices that eject liquid into air or into liquid.

The "device for discharging liquid" may include means for feeding, transporting, and discharging objects to which liquid can adhere, as well as pre-processing devices, post-processing devices, and the like.

For example, an image forming device is a device that ejects ink to form an image on paper as a “device that ejects liquid,” and an image forming device that forms layers of powder to form three-dimensional objects (three-dimensional objects). There is a three-dimensional modeling device (three-dimensional modeling device) that discharges a modeling liquid onto a powder layer.

Further, the "device for ejecting liquid" is not limited to a device that can visualize significant images such as characters and figures using ejected liquid. For example, it includes those that form patterns that have no meaning in themselves, and those that form three-dimensional images.

The above-mentioned "something to which a liquid can adhere" refers to something to which a liquid can adhere at least temporarily, such as something that adheres and sticks, something that adheres and penetrates. Specific examples include recording media such as paper, recording paper, recording paper, film, and cloth, electronic components such as electronic boards, piezoelectric elements, powder layers, organ models, and test cells. Unless otherwise specified, it includes everything to which liquid adheres.

The above-mentioned "materials to which liquids can adhere" include paper, thread, fibers, fabrics, leather, metals, plastics, glass, wood, ceramics, building materials such as wallpaper and flooring, and textiles for clothing. However, it is fine as long as it can be attached.

Furthermore, "liquid" includes ink, processing liquid, DNA sample, resist, pattern material, binder, modeling liquid, and solutions and dispersions containing amino acids, proteins, and calcium.

Further, the "device for discharging liquid" includes a device in which a liquid discharging head and an object to which liquid can be attached move relative to each other, but the present invention is not limited to this. Specific examples include a serial type device that moves a liquid ejection head, a line type device that does not move a liquid ejection head, and the like.

In addition, "devices that discharge liquid" include processing liquid coating devices that discharge processing liquid onto paper in order to apply processing liquid to the surface of paper for purposes such as modifying the surface of the paper, and raw materials. There is an injection granulation device that granulates fine particles of a raw material by injecting a composition liquid dispersed in a solution through a nozzle.

A "liquid ejection unit" is a liquid ejection head with functional parts and mechanisms integrated, and is an assembly of parts related to liquid ejection. For example, the "liquid ejection unit" includes a combination of a liquid ejection head and at least one of the following structures: a head tank, a carriage, a supply mechanism, a maintenance recovery mechanism, and a main scanning movement mechanism.

Here, integration refers to, for example, a liquid ejection head, a functional component, or a mechanism fixed to each other by fastening, adhesion, engagement, etc., or one in which one is held movably relative to the other. include. Further, the liquid ejection head, the functional parts, and the mechanism may be configured to be detachable from each other.

For example, there is a liquid ejection unit in which a liquid ejection head and a head tank are integrated, such as a liquid ejection unit 440 shown in FIG. 13. In addition, there are devices in which a liquid ejection head and a head tank are integrated by being connected to each other with a tube or the like. Here, a unit including a filter may be added between the head tank and the liquid ejection head of these liquid ejection units.

Further, some liquid ejection units have a liquid ejection head and a carriage integrated.

Further, some liquid ejection units have the liquid ejection head movably held by a guide member that constitutes a part of the scanning movement mechanism, so that the liquid ejection head and the scanning movement mechanism are integrated. Furthermore, as shown in FIG. 14, there is a liquid ejection unit in which a liquid ejection head, a carriage, and a main scanning movement mechanism are integrated.

Furthermore, some liquid ejection units have a cap member, which is part of the maintenance recovery mechanism, fixed to the carriage to which the liquid ejection head is attached, so that the liquid ejection head, the carriage, and the maintenance recovery mechanism are integrated. .

Furthermore, as shown in FIG. 15, some liquid ejection units have a tube connected to a liquid ejection head to which a head tank or flow path components are attached, so that the liquid ejection head and supply mechanism are integrated. .

The main scanning movement mechanism also includes a single guide member. Further, the supply mechanism includes a single tube and a single loading section.

Furthermore, the pressure generating means used in the "liquid ejection head" is not limited. For example, in addition to the piezoelectric actuator (which may use a laminated piezoelectric element) as explained in the above embodiment, there is also a thermal actuator that uses an electrothermal transducer such as a heating resistor, and a thermal actuator that uses a diaphragm and a counter electrode. An electrostatic actuator or the like may also be used.

Further, in the terms of this application, image formation, recording, printing, imprinting, printing, modeling, etc. are all synonymous.

Next, an example of a liquid ejecting device equipped with a liquid ejecting head according to the present invention will be described with reference to FIGS. 16 and 17. 16 is a perspective view of the recording apparatus, and FIG. 17 is a side view of the mechanism of the recording apparatus.

Here, an example of an inkjet recording apparatus will be described as an apparatus for ejecting liquid. This inkjet recording device includes a carriage that is movable in the main scanning direction inside a recording device main body 81, a recording head that is an inkjet head that implements the present invention mounted on the carriage, an ink cartridge that supplies ink to the recording head, and the like. It houses the printing mechanism section 82 and the like. A paper feed cassette (or paper feed tray may be used) 84 that can load a large number of sheets of paper 83 from the front side can be detachably attached to the lower part of the apparatus main body 81. Moreover, the manual feed tray 85 for manually feeding paper 83 can be opened and folded, and the paper 83 fed from the paper feed cassette 84 or the manual feed tray 85 can be taken in, and the desired image can be printed by the printing mechanism section 82. After recording, the paper is ejected to a paper ejection tray 86 mounted on the rear side.

The printing mechanism section 82 holds a carriage 93 slidably in the main scanning direction by a main guide rod 91 and a subordinate guide rod 92, which are guide members that are horizontally suspended between left and right side plates. This carriage 93 is equipped with a head 94 consisting of an inkjet head that ejects ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). They are arranged in a direction that intersects with the direction of the ink droplets, and are mounted with the ink droplet ejection direction facing downward.

Further, each ink cartridge 95 for supplying ink of each color to the head 94 is replaceably mounted on the carriage 93. The ink cartridge 95 has an air port communicating with the atmosphere at the top, a supply port for supplying ink to the inkjet head at the bottom, and a porous body filled with ink inside, and the capillary force of the porous body This maintains the ink supplied to the inkjet head at a slight negative pressure. Further, although heads 94 of each color are used as recording heads here, a single head having nozzles for ejecting ink droplets of each color may be used.

Here, the carriage 93 is slidably fitted on the main guide rod 91 on the rear side (downstream side in the paper conveyance direction), and slidably placed on the slave guide rod 92 on the front side (upstream side in the paper conveyance direction). are doing. In order to move and scan the carriage 93 in the main scanning direction, a timing belt 100 is stretched between a driving pulley 98 and a driven pulley 99 which are rotationally driven by a main scanning motor 97. The carriage 93 is driven back and forth by the forward and reverse rotation of the main scanning motor 97.

On the other hand, in order to convey the paper 83 set in the paper feed cassette 84 to the lower side of the head 94, a paper feed roller 101 and a friction pad 102, which separate and feed the paper 83 from the paper feed cassette 84, and a friction pad 102 are used to guide the paper 83. A guide member 103, a conveyance roller 104 that reverses and conveys the fed paper 83, a conveyance roller 105 that is pressed against the circumferential surface of the conveyance roller 104, and a tip that defines the feeding angle of the paper 83 from the conveyance roller 104. A roller 106 is provided. The conveyance roller 104 is rotationally driven by a sub-scanning motor 107 via a gear train.

An impression receiving member 109 is provided as a paper guide member that guides the paper 83 sent out from the conveyance roller 104 below the recording head 94 in accordance with the movement range of the carriage 93 in the main scanning direction. On the downstream side of the print receiving member 109 in the paper transport direction, a transport roller 111 and a spur 112 which are rotatably driven to send out the paper 83 in the paper ejection direction are provided, and a paper ejection roller 112 is provided to send out the paper 83 to the paper ejection tray 86. A roller 113, a spur 114, and guide members 115 and 116 forming a paper ejection path are provided.

During recording, by driving the recording head 94 according to the image signal while moving the carriage 93, ink is ejected onto the stationary paper 83 to record one line, and after conveying the paper 83 a predetermined amount, the next Record the line. By receiving a recording end signal or a signal indicating that the trailing edge of the paper 83 has reached the recording area, the recording operation is completed and the paper 83 is ejected.

Further, a recovery device 117 for recovering from an ejection failure of the head 94 is arranged at a position outside the recording area on the right end side in the moving direction of the carriage 93. The recovery device 117 has a cap means, a suction means, and a cleaning means. During printing standby, the carriage 93 is moved to the recovery device 117 side, and the head 94 is capped by a capping means to keep the ejection opening in a moist state to prevent ejection failure due to ink drying. Furthermore, by ejecting ink unrelated to printing during printing, the ink viscosity of all ejection ports is made constant, and stable ejection performance is maintained.

If an ejection failure occurs, the ejection port (nozzle) of the head 94 is sealed with a capping means, and air bubbles, etc., are sucked out together with the ink from the ejection port by a suction means through a tube, and ink, dust, etc. attached to the ejection port surface are removed. is removed by the cleaning means, and the ejection failure is recovered. Further, the sucked ink is discharged to a waste ink reservoir installed at the bottom of the main body, and is absorbed and retained by an ink absorber inside the waste ink reservoir.

As described above, since the liquid ejection head and the device for ejecting liquid of the present invention are equipped with the electro-mechanical conversion element of the present invention, the piezoelectric characteristics and dielectric strength are good, and failures are less likely to occur. In addition, it is possible to prevent ink droplet ejection failure due to poor driving of the diaphragm and to suppress fluctuations in displacement, resulting in stable ink droplet ejection characteristics and improved image quality.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

(Example 1)
A SiO ₂ film (film thickness: about 2.5 μm) was formed as a diaphragm on a 6-inch silicon wafer as a substrate. A Ti film (approximately 20 nm thick) was formed on this SiO ₂ film at 350° C. by sputtering, and thermally oxidized at 750° C. by RTA (rapid thermal treatment). Subsequently, a Pt film (about 160 nm thick) was formed as a lower electrode by sputtering at about 300°C. Note that the TiO ₂ film obtained by thermally oxidizing the Ti film serves as an adhesion layer between the SiO ₂ film and the Pt film.

Next, in order to form a PbTiO ₃ layer (also referred to as a PT seed layer) on the Pt film, a solution adjusted to Pb:Ti=1:1 was prepared. A 6 nm PT seed layer was formed using the prepared solution (PT coating solution below). The PT seed layer has a role as a seed.

Next, an electro-mechanical conversion film (PZT film) is formed.
A PZT precursor coating liquid prepared at a composition ratio of Pb:Zr:Ti=115:49:51 was prepared as a material for the PZT film. A specific PZT precursor coating solution was synthesized as follows. First, lead acetate trihydrate, titanium isopropoxide, and zirconium isopropoxide were used as starting materials. Crystal water of lead acetate was dissolved in methoxyethanol and then dehydrated. The amount of lead is excessive compared to the stoichiometric composition. This is to prevent a decrease in crystallinity due to so-called lead removal during heat treatment.
A PZT precursor coating liquid was synthesized by dissolving isopropoxide titanium and isopropoxide zirconium in methoxyethanol, proceeding with alcohol exchange reaction and esterification reaction, and mixing with the above methoxyethanol solution in which lead acetate was dissolved. . This PZT concentration was set to 0.5 mol/l.

Note that the PT coating liquid for forming the PT layer was also synthesized in the same manner as the PZT precursor coating liquid. The PT coating liquid is synthesized without using zirconium isopropoxide.

Using these coating solutions, a PT seed layer was first formed by spin coating, and then dried at 120° C. using a hot plate.
Next, a PZT precursor coating liquid was formed into a film by spin coating, dried at 120°C, and then thermally decomposed at 380°C. Note that thermal decomposition is also referred to as calcination. Furthermore, coating, drying, and calcination were repeated to form a total of three layers of PZT film. After the thermal decomposition treatment of the third layer, heat treatment (temperature 730° C.) for crystallization was performed by RTA (rapid thermal treatment). The thickness of the PZT film when this heat treatment for crystallization was completed was 240 nm. The heat treatment steps of applying this PZT precursor solution, drying, thermal decomposition, and crystallization were performed a total of four times to obtain a PZT film with a thickness of about 1 μm. That is, the PZT film had three layers before the crystallization heat treatment, and a total of 12 layers were formed in four times.

Next, a SrRuO film (40 nm thick) was formed as an internal electrode film, and a Pt film (125 nm thick) was further formed thereon by sputtering. Next, a SrRuO film (thickness: 20 nm) was formed as a seed layer.

Next, in the same manner as above, a PZT film with a thickness of about 1 μm was formed, an internal electrode film and a seed layer were formed, and a PZT film with a thickness of about 1 μm was further formed. Therefore, the total thickness of the PZT film is approximately 3 μm.

Next, a SrRuO film (40 nm thick) was formed as an upper electrode on the PZT film, and a Pt film (125 nm thick) was further formed thereon by sputtering.

After that, a film of photoresist (TSMR8800) manufactured by Tokyo Ohka Co., Ltd. was formed by spin coating, and a resist pattern was formed by ordinary photolithography, and then a pattern as shown in FIG. 5 was formed using an ICP etching device (manufactured by Samco). Created.
Next, as a first interlayer film, an Al ₂ O ₃ film was formed to a thickness of 50 nm using the ALD method. At this time, as raw materials, TMA (Sigma-Aldrich) was used for Al and O ₃ generated by an ozone generator was used for O, and film formation was proceeded by alternately stacking them.
Thereafter, as shown in FIG. 8, a contact hole portion is formed by etching.
Next, as shown in FIG. 9, an Al film was formed by sputtering as a wiring electrode, patterned by etching, and a 500 nm thick film of Si ₃ N ₄ was formed as a second interlayer film by plasma CVD. In this manner, the electro-mechanical transducer of this example was produced.

(Examples 2 to 5, Comparative Example 1)
In Examples 2 and 3, the seed layer was changed as shown in Table 1.
In Example 4, the seed layer was changed as shown in Table 1, and the thickness of the PbTiO ₃ layer (PT seed layer) on the lower electrode was changed from 6 nm to 3 nm.
In Example 5, the internal electrode film and seed layer were changed as shown in Table 1.
As shown in Table 1, in Comparative Example 1, no internal electrode film was provided, and a PZT film was formed with a thickness of about 3 μm.
The configurations of the above examples and comparative examples are shown in Table 1 below.

(Measurement and evaluation)
<(100) orientation rate>
A cross section of the obtained electro-mechanical transducer was formed, and orientation analysis was performed for each crystal grain by analyzing the backscattered electron diffraction of each electro-mechanical transducer film using the EBSD method. As a result, an image having regions with (100) orientation and regions other than (100) orientation is obtained,
(100) Orientation rate [%] = (100) Area of oriented crystal grain region/Area of total region x 100
The (100) orientation rate was calculated. Note that the area of the total area is the area of the measurement area when measuring each electro-mechanical conversion film.

<Displacement amount>
Displacement characteristics were evaluated using the fabricated electro-mechanical transducer. Regarding the displacement evaluation, as shown in FIG. 10, digging was performed from the back side of the substrate (width in the transverse direction: 60 μm, width in the longitudinal direction: 900 μm), and vibration evaluation was performed. As shown in FIG. 9, the amount of displacement was determined by applying 30V to the even numbered wires with the odd numbered wires as a reference, and measuring the amount of deformation at that time with a laser Doppler vibrometer. The results are shown in Table 1.

<Discharge evaluation>
A liquid ejection head shown in FIG. 11(A) was manufactured using the electro-mechanical transducer elements manufactured in Examples 1 to 5, and liquid ejection was evaluated. Using ink whose viscosity was adjusted to 5 cp, we checked the ejection status when applying an applied voltage of -10 to -30V using a simple push waveform, and it was confirmed that all ink could be ejected from any nozzle hole.

Table 1 shows part of the structure and measurement and evaluation results of each example and comparative example.

In Examples 1 to 4, high values were obtained for the first layer and total (100) orientation ratios. From the results of Example 4, it was found that the total orientation rate decreased as the orientation rate of the first layer decreased. Furthermore, it was found that in the case where the internal electrode layer was made of Pt as in Example 5, although the (100) orientation ratio of the first layer was high, the total orientation ratio was low.

Regarding the amount of displacement, good results were obtained in Examples 1 to 5. On the other hand, in Comparative Example 1 in which no internal electrodes were provided, a good amount of displacement could not be obtained. Furthermore, it was confirmed that Example 5, which had a low total orientation rate, had a higher displacement amount than Comparative Example 1, but was inferior in performance compared to Examples 1 to 4.

10 Substrate 11 Nozzle 12 Vibration plate 14 Lower electrode 16 Electro-mechanical conversion film 18 Internal electrode film 20 Upper electrode 22 Seed layer 26 Wiring 28 Contact hole 32 First interlayer film 34 Second interlayer film 41 Pressure chamber 43 Nozzle plate 81 Recording device main body 82 Printing mechanism section 83 Paper 84 Paper feed cassette 85 Manual feed tray 86 Paper ejection tray 91 Main guide rod 92 Secondary guide rod 93 Carriage 94 Head 95 Ink cartridge 97 Main scanning motor 98 Drive pulley 99 Driven pulley 100 Timing belt 101 Paper feed roller 102 Friction pad 103 Guide member 104 Conveyance roller 105 Conveyance roller 106 Leading edge roller 107 Sub-scanning motor 109 Imprint receiving member 111 Conveyance roller 112, 114 Spur 113 Paper discharge roller 115, 116 Guide member 117 Recovery device

JP2013-080886A

Claims (13)

An electro-mechanical conversion element in which an electro-mechanical conversion film and an internal electrode film are alternately laminated on a lower electrode, and an upper electrode is formed on the electro-mechanical conversion film formed at the top,
The internal electrode film is not formed between the lower electrode and the electro-mechanical conversion film closest to the lower electrode,
The electro-mechanical conversion film closest to the lower electrode has a (100) orientation rate of 95% or more,
a first interlayer film is formed on the lower electrode and the upper electrode,
The area of the electro-mechanical conversion film and the internal electrode film gradually decreases from the lower electrode side to the upper electrode side when comparing each layer,
It has a wiring drawn out from the lower electrode, a wiring drawn out from the internal electrode film, and a wiring drawn out from the upper electrode, and these wirings are drawn out through the first interlayer film,
An electro-mechanical conversion element characterized in that a part of the wiring drawn out from the lower electrode, the wiring drawn out from the internal electrode film, and the wiring drawn out from the upper electrode exists on the first interlayer film . A layer made of PbTiO _{3 is formed between the lower electrode and the electro-mechanical conversion film closest to the lower electrode, and the layer made of PbTiO 3 is} formed between the electro-mechanical conversion film closest to the lower electrode. The electro-mechanical transducer according to claim 1, wherein the electro-mechanical transducer is formed in contact with a film. 3. The electro-mechanical transducer according to claim 1, wherein the internal electrode film is made of SrRuO, or is formed by laminating SrRuO and Pt in order from the lower electrode side. The electro-mechanical transducer according to claim 1, wherein SrRuO is formed on the internal electrode film. A plurality of contact holes are formed in the first interlayer film, and the wiring drawn out from the lower electrode, the wiring drawn out from the internal electrode film, and the wiring drawn out from the upper electrode are drawn out from each of the contact holes. The electro-mechanical transducer according to claim 1, wherein the electro-mechanical transducer is formed on the first interlayer film. 1. A second interlayer film is formed on the first interlayer film, and the second interlayer film protects wiring formed on the first interlayer film. 5. The electro-mechanical conversion element according to any one of 5 to 5. The electro-mechanical conversion film has a longitudinal direction and a transverse direction in a direction perpendicular to the stacking direction,
The wires are drawn out to the left and right along the longitudinal direction, and when the wires are numbered from the lower electrode side to the upper electrode side, the odd numbered wires are drawn out in the same direction, and the even numbered wires are drawn out in the same direction. 7. The electro-mechanical conversion element according to claim 1, wherein the wiring is drawn out in a direction different from that of the odd-numbered wiring. The electro-mechanical conversion film according to any one of claims 1 to 7, wherein the average value of the (100) orientation rate determined using the (100) orientation rate of each layer is 95% or more. Electrical-mechanical conversion element. A nozzle for discharging a liquid, a pressurizing chamber communicating with the nozzle, and a pressure generating means for generating pressure in the liquid in the pressurizing chamber,
A liquid ejection head characterized in that the electro-mechanical conversion element according to any one of claims 1 to 8 is used as the pressure generating means. 10. The liquid ejection head according to claim 9, wherein the electro-mechanical conversion film and the internal electrode film have an area that gradually decreases in a direction opposite to the nozzle side. A liquid ejection unit comprising the liquid ejection head according to claim 9 or 10 . A head tank that stores liquid to be supplied to the liquid ejection head, a carriage that mounts the liquid ejection head, a supply mechanism that supplies liquid to the liquid ejection head, a maintenance and recovery mechanism that maintains and recovers the liquid ejection head, and the liquid. 12. The liquid ejection unit according to claim 11 , wherein the liquid ejection head is integrated with at least one of a main scanning movement mechanism that moves the ejection head in the main scanning direction. An apparatus for ejecting liquid, comprising the liquid ejection head according to claim 9 or 10 or the liquid ejection unit according to claim 11 or 12 .

Images