Manufacturing method of actuator device, and liquid jetting device

The present invention relates to a method for manufacturing an actuator device and a liquid injection device.

An actuator device including a piezoelectric element that is displaced by applying a voltage is mounted on, for example, a liquid injection head that injects droplets. As such a liquid injection head, for example, a part of the pressure generating chamber communicating with the nozzle opening is formed of a vibrating plate, and the vibrating plate is deformed by a piezoelectric element to pressurize the ink in the pressure generating chamber to open the nozzle. An inkjet recording head that ejects ink droplets from the ink jet is known. Two types of inkjet recording heads have been put into practical use: one equipped with a piezoelectric actuator device in a longitudinal vibration mode that expands and contracts in the axial direction of the piezoelectric element, and one equipped with a piezoelectric actuator device in a flexible vibration mode. There is. Then, as an actuator using a deflection vibration mode, for example, a uniform piezoelectric film is formed over the entire surface of the vibrating plate by a film forming technique, and this piezoelectric layer is placed in a pressure generation chamber by a lithography method. Some piezoelectric elements are formed independently for each pressure generating chamber by cutting them into corresponding shapes.

As the piezoelectric layer (piezoelectric thin film), for example, a ferroelectric substance such as lead zirconate titanate (PZT) is used. Then, in such a piezoelectric thin film, for example, a titanium crystal is formed on the lower electrode by a sputtering method or the like, a piezoelectric precursor film is formed on the titanium crystal by a sol-gel method, and the piezoelectric precursor is formed. It is formed by firing a film (see, for example, Patent Document 1).

When the piezoelectric layer is formed by such a method, the crystals of the piezoelectric layer grow around the titanium crystals as nuclei, and relatively dense and columnar crystals can be obtained. However, it is difficult to control the crystallinity of the piezoelectric layer, and the electrical or mechanical characteristics of the piezoelectric layer cannot be made uniform, so that there is a problem that the displacement characteristics of the piezoelectric element vary. .. It should be noted that such a problem exists not only at the time of manufacturing an actuator device mounted on a liquid injection head such as an inkjet recording head, but also at the time of manufacturing an actuator device mounted on another device.

<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2001-274472 (page 5)</text></patcit>

<p> In view of such circumstances, it is an object of the present invention to provide a method for manufacturing an actuator device and a liquid injection device capable of improving the characteristics of the piezoelectric layer constituting the piezoelectric element and stabilizing the characteristics of the piezoelectric layer. And.</p>

<p> The first aspect of the present invention for solving the above problems is a step of forming a diaphragm on one surface of a substrate and a step of forming a piezoelectric element composed of a lower electrode, a piezoelectric layer and an upper electrode on the diaphragm. A method of manufacturing an actuator device comprising the above, wherein the step of forming the diaphragm is made of zirconium oxide by forming a zirconium layer and thermally oxidizing the zirconium layer at a predetermined temperature to form the outermost layer of the diaphragm. The step of forming the constituent insulator film so that its surface roughness Ra is within the range of 1 to 3 nm, and the step of forming the piezoelectric element is a step of forming titanium (Ti) on the lower electrode by a sputtering method. To form a seed titanium layer by applying the above, and by applying a piezoelectric material on the seed titanium layer to form a piezoelectric precursor film and firing the piezoelectric precursor film to crystallize the above. A method of manufacturing an actuator device, which comprises a step of forming a piezoelectric layer. In the first aspect, the characteristics of the piezoelectric layer can be improved by controlling the surface roughness of the insulator film, which is the base of the piezoelectric layer, to be equal to or less than a predetermined value.</p><p> A second aspect of the present invention is the actuator device according to the first aspect, wherein in the step of forming the insulator film, the surface roughness Ra of the insulator film is made larger than 2 nm. It is in the manufacturing method. In such a second aspect, the characteristics of the piezoelectric layer can be further improved.</p><p> A third aspect of the present invention is characterized in that, in the first or second aspect, the degree of (002) plane orientation of the zirconium layer is 80% or more in the step of forming the insulator film. It is in the manufacturing method of the actuator device. In such a third aspect, by controlling the crystal orientation of the zirconium layer, it is possible to form an insulator film having excellent crystallinity and a desired surface roughness.</p><p> A fourth aspect of the present invention is a method for manufacturing an actuator device according to any one of the first to third aspects, wherein the heating temperature of the zirconium layer is set to 900 ° C. or lower when the zirconium layer is thermally oxidized. is there. In the fourth aspect, since the surface roughness of the zirconium layer can be controlled to be large, the crystallinity of the piezoelectric layer can be easily controlled.</p><p> A fifth aspect of the present invention is an actuator characterized in that, in any one of the first to fourth aspects, the seed titanium layer is formed with a thickness of 1 to 8 nm in the step of forming the seed titanium layer. It is in the manufacturing method of the device. In the fifth aspect, the crystallinity of the piezoelectric layer is more reliably improved by forming the seed titanium layer with a predetermined thickness.</p><p> In the sixth aspect of the present invention, in any one of the first to fifth aspects, the power density when forming the seed titanium layer is 1 to 4 kW / m.²It is in the manufacturing method of the actuator device characterized by the above. In the sixth aspect, the crystallinity of the piezoelectric layer is further improved because more titanium seeds, which are the cores of the crystals of the piezoelectric layer, are formed.</p><p> A seventh aspect of the present invention is characterized in that, in any one of the first to sixth aspects, titanium (Ti) is applied to the lower electrode at least twice or more in the step of forming the seed titanium layer. It is in the manufacturing method of the actuator device. In the seventh aspect, the crystallinity of the piezoelectric layer is further improved because more titanium seeds, which are the cores of the crystals of the piezoelectric layer, are formed.</p><p> An eighth aspect of the present invention is a liquid injection device including a head using an actuator device manufactured by any of the first to seventh manufacturing methods as a liquid discharge means. In the eighth aspect, the displacement characteristic of the piezoelectric element is improved, and a liquid injection device having improved liquid injection characteristics can be manufactured relatively easily and reliably.</p>

Hereinafter, the present invention will be described in detail based on the embodiments. (Embodiment 1) FIG. 1 is an exploded perspective view showing an inkjet recording head according to a first embodiment of the present invention, and FIG. 2 is a plan view and a cross-sectional view of FIG. As shown in the figure, in the present embodiment, the flow path forming substrate 10 is made of a silicon single crystal substrate having a plane orientation (110), and one surface thereof is made of silicon dioxide previously formed by thermal oxidation, and has a thickness of 0.5 to A 2 μm elastic film 50 is formed. A plurality of pressure generating chambers 12 formed by anisotropic etching from the other direction side and partitioned by the partition wall 11 are arranged side by side in the width direction of the flow path forming substrate 10. Further, a communication portion 13 is formed in a region outside the pressure generation chamber 12 of the flow path forming substrate 10 in the longitudinal direction, and the communication portion 13 and each pressure generation chamber 12 are provided with ink for each pressure generation chamber 12. It communicates through the supply channel 14. The communication unit 13 constitutes a part of the reservoir that communicates with the reservoir unit of the protective substrate, which will be described later, and serves as a common ink chamber of each pressure generating chamber 12. The ink supply path 14 is formed to have a width narrower than that of the pressure generating chamber 12, and keeps the flow path resistance of the ink flowing from the communication portion 13 into the pressure generating chamber 12 constant.

Further, a nozzle plate 20 having a nozzle opening 21 communicating with the vicinity of the end opposite to the ink supply path 14 of each pressure generating chamber 12 is bored on the opening surface side of the flow path forming substrate 10, which will be described later. It is fixed by an adhesive, a heat welding film, or the like via a mask film. The nozzle plate 20 has a thickness of, for example, 0.01 to 1 mm and a coefficient of linear expansion of 300 ° C or less, for example, 2.5 to 4.5 [× 10].^-6/ ° C] made of glass ceramics, silicon single crystal substrate, stainless steel, etc.

On the other hand, as described above, silicon dioxide (SiO) having a thickness of, for example, about 1.0 μm is on the side of the flow path forming substrate 10 opposite to the opening surface side.₂) Is formed, and zirconium oxide (ZrO) having a thickness of, for example, about 0.4 μm is formed on the elastic film 50.₂) Is formed. Further, on the insulator film 55, a lower electrode film 60 having a thickness of, for example, about 0.1 to 0.2 μm, a piezoelectric layer 70 having a thickness of, for example, about 1.0 μm, and a piezoelectric layer 70 having a thickness of, for example, about 0.05. The μm upper electrode film 80 is laminated and formed by a process described later to form the piezoelectric element 300. Here, the piezoelectric element 300 refers to a portion including a lower electrode film 60, a piezoelectric layer 70, and an upper electrode film 80. Generally, one electrode of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each pressure generating chamber 12. Here, a portion composed of one of the patterned electrodes and the piezoelectric layer 70 and in which piezoelectric strain is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion. In the present embodiment, the lower electrode film 60 is used as the common electrode of the piezoelectric element 300, and the upper electrode film 80 is used as the individual electrode of the piezoelectric element 300, but there is no problem even if this is reversed due to the convenience of the drive circuit and wiring. In any case, the piezoelectric active portion is formed in each pressure generating chamber. Further, here, the piezoelectric element 300 and the diaphragm that is displaced by driving the piezoelectric element 300 are collectively referred to as a piezoelectric actuator. In the above-mentioned example, the elastic film 50, the insulator film 55, and the lower electrode film 60 play a role as a diaphragm.

Further, a lead electrode 90 is connected to the upper electrode film 80 of each of the piezoelectric elements 300, and a voltage is selectively applied to each of the piezoelectric elements 300 via the lead electrode 90. ..

Here, in the present invention, the surface roughness (arithmetic mean roughness Ra) of the insulator film 55 forming the outermost layer of the diaphragm which is the base of the piezoelectric layer 70 constituting the piezoelectric element 300 is in the range of 1 to 3 nm. It is inside, preferably 1.5 nm or more, and particularly preferably larger than 2 nm. The surface roughness Ra of the lower electrode film 60 formed on the insulator film 55 is also 1 to 3 nm or less. As will be described in detail later, by increasing the surface roughness Ra of the insulator film 55 in this way, the characteristics of the piezoelectric layer 70 formed on the insulator film 55 can be improved.

Further, a protective substrate 30 having a piezoelectric element holding portion 31 in a region facing the piezoelectric element 300 is bonded to the surface of the flow path forming substrate 10 on the piezoelectric element 300 side via an adhesive. Since the piezoelectric element 300 is formed in the piezoelectric element holding portion 31, it is protected in a state where it is hardly affected by the external environment. Further, the protective substrate 30 is provided with a reservoir portion 32 in a region corresponding to the communication portion 13 of the flow path forming substrate 10. In the present embodiment, the reservoir portion 32 is provided so as to penetrate the protective substrate 30 in the thickness direction and along the parallel arrangement direction of the pressure generating chambers 12, and as described above, the communication portion of the flow path forming substrate 10. It constitutes a reservoir 100 that communicates with 13 and serves as a common ink chamber for each pressure generating chamber 12.

Further, in the region between the piezoelectric element holding portion 31 and the reservoir portion 32 of the protective substrate 30, a through hole 33 that penetrates the protective substrate 30 in the thickness direction is provided, and the lower electrode film 60 is provided in the through hole 33. A part of the lead electrode 90 and the tip of the lead electrode 90 are exposed, and the lower electrode film 60 and the lead electrode 90 are connected to the other end of the connection wiring whose one end is connected to the drive IC, although not shown.

As the material of the protective substrate 30, for example, glass, ceramic materials, metals, resins, and the like, the flow is more preferably formed by having substantially the same thermal expansion coefficient as the material of the channel substrate 10, In this embodiment, it is formed by using a silicon single crystal substrate made of the same material as the flow path forming substrate 10.

Further, a compliance substrate 40 composed of a sealing film 41 and a fixing plate 42 is bonded onto the protective substrate 30. The sealing film 41 is made of a material having low rigidity and flexibility (for example, a polyphenylene sulfide (PPS) film having a thickness of 6 μm), and one surface of the reservoir portion 32 is sealed by the sealing film 41. There is. Further, the fixing plate 42 is formed of a hard material such as metal (for example, stainless steel (SUS) having a thickness of 30 μm or the like). Since the region of the fixing plate 42 facing the reservoir 100 is an opening 43 completely removed in the thickness direction, one surface of the reservoir 100 is sealed only with the flexible sealing film 41. Has been done.

In such an inkjet recording head of the present embodiment, ink is taken in from an external ink supply means (not shown), the inside from the reservoir 100 to the nozzle opening 21 is filled with ink, and then according to a recording signal from a drive IC (not shown). , A voltage is applied between the lower electrode film 60 and the upper electrode film 80 corresponding to the pressure generating chamber 12, and the elastic film 50, the insulator film 55, the lower electrode film 60 and the piezoelectric layer 70 are flexed and deformed. As a result, the pressure in each pressure generating chamber 12 increases, and ink is ejected from the nozzle opening 21.

Here, a method for manufacturing such an inkjet recording head will be described with reference to FIGS. 3 to 6. 3 to 6 are cross-sectional views of the pressure generating chamber 12 in the longitudinal direction. First, as shown in FIG. 3 (a), a wafer 110 for a flow path forming substrate, which is a silicon wafer, is thermally oxidized in a diffusion furnace at about 1100 ° C., and a silicon dioxide film 51 constituting an elastic film 50 is formed on the surface thereof. Form. In this embodiment, a silicon wafer having a relatively thick film thickness of about 625 μm and high rigidity is used as the flow path forming substrate 10.

Next, as shown in FIG. 3 (b), an insulator film 55 made of zirconium oxide is formed on the elastic film 50 (silicon dioxide film 51). Specifically, a zirconium (Zr) layer is formed on the elastic film 50 (silicon dioxide film 51) by a DC sputtering method, an RF sputtering method, or the like. At this time, the surface roughness (arithmetic mean roughness Ra) of the zirconium layer is controlled to be 1 to 3 nm, preferably 1.5 nm or more, and more preferably 2.0 nm or more.

Further, the zirconium layer preferably has a (002) plane orientation of 80% or more on its surface. The "degree of orientation" referred to here refers to the ratio of the diffraction intensity generated when the zirconium layer is measured by the X-ray diffraction wide-angle method. Specifically, when the zirconium layer is measured by the X-ray diffraction wide-angle method, peaks of diffraction intensity corresponding to the (100) plane, the (002) plane, and the (101) plane are generated. The "(002) plane orientation" means the ratio of the peak intensity corresponding to the (002) plane to the sum of the peak intensities corresponding to each of these planes.

In order to keep the surface roughness Ra of the zirconium layer within the range of 1 to 3 nm, it is preferable that the sputtering output when forming the zirconium layer is 500 W or less. The sputtering temperature is preferably normal temperature (about 23 to 25 ° C). Further, the sputtering pressure is preferably 0.5 Pa or more. Further, the target spacing (distance between the target and the substrate) is preferably 100 mm or less. By forming the zirconium layer by appropriately selecting the film forming conditions in this way, the surface roughness Ra of the zirconium layer can be controlled within the range of 1 to 3 nm, and at the same time, the degree of (002) plane orientation is 80. It can be% or more.

After the zirconium layer is formed in this way, the zirconium layer is thermally oxidized to form an insulator film 55 made of zirconium oxide. The heating temperature at this time is preferably 900 ° C. or lower, preferably 700 to 900 ° C. By adjusting the heating temperature during thermal oxidation in this way, the insulator film 55 is formed so that the surface roughness Ra is within the range of 1 to 3 nm. For example, in the present embodiment, the wafer 110 for the flow path forming substrate is inserted into the diffusion furnace in an oxygen atmosphere heated to about 700 to 900 ° C. at a speed of 300 mm / min or more, preferably 500 mm / min or more. The zirconium layer was thermally oxidized for about 15 to 60 minutes.

As a result, an insulator film 55 having a good crystal state is obtained, and the surface roughness Ra of the insulator film 55 is within the range of 1 to 3 nm. That is, the zirconium oxide crystals constituting the insulator film 55 grow substantially uniformly to form continuous columnar crystals from the lower surface to the upper surface, so that the surface roughness Ra becomes relatively coarse within the range of 1 to 3 nm. ..

Next, as shown in FIG. 3C, for example, a lower electrode film 60 composed of at least platinum and iridium is formed on the entire surface of the insulator film 55 by a sputtering method or the like, and then the lower electrode film 60 is patterned into a predetermined shape. .. Since the surface roughness Ra of the lower electrode film 60 depends on the surface roughness Ra of the insulator film 55, if the surface roughness Ra of the insulator film 55 is within the range of 1 to 3 nm, the lower electrode The surface roughness Ra of the film 60 is also within the range of 1 to 3 nm.

Next, as shown in FIG. 3D, titanium (Ti) is applied onto the lower electrode film 60 and the insulator film 55 twice or more by a sputtering method, for example, a DC sputtering method, or twice in this embodiment. By doing so, a continuous seed titanium layer 65 having a predetermined thickness is formed. The film thickness of this kind of titanium layer 65 is preferably formed so as to be within the range of 1 nm to 8 nm. This is because by forming the seed titanium layer 65 with such a thickness, the crystallinity of the piezoelectric layer 70 formed in the step described later can be improved.

Here, the sputtering conditions for forming the seed titanium layer 65 are not particularly limited, but the sputtering pressure is preferably in the range of 0.4 to 4.0 Pa. The sputtering output is preferably 50 to 100 W, and the sputtering temperature is preferably in the range of normal temperature (about 23 to 25 ° C) to 200 ° C. In addition, the power density is 1-4kW / m²It is preferable to set the degree. Further, as described above, here, by applying titanium twice, it is possible to form a large number of seed titanium which is the core of the crystal of the piezoelectric layer 70 to be formed in the next step.

Next, on the seed titanium layer 65 thus formed, for example, a piezoelectric layer 70 made of lead zirconate titanate (PZT) is formed. In this embodiment, a so-called sol-gel method is used in which a so-called sol in which a metal organic substance is dissolved and dispersed in a catalyst is applied, dried, gelled, and then calcined at a high temperature to obtain a piezoelectric layer 70 made of a metal oxide. A piezoelectric layer 70 made of PZT was formed.

As a procedure for forming the piezoelectric layer 70, first, as shown in FIG. 4A, a piezoelectric precursor film 71, which is a PZT precursor film, is formed on the seed titanium layer 65. That is, a sol (solution) containing a metal-organic compound is applied onto the flow path forming substrate wafer 110. Next, the piezoelectric precursor membrane 71 is heated to a predetermined temperature and dried for a certain period of time, and the sol solvent is evaporated to dry the piezoelectric precursor membrane 71. Further, the piezoelectric precursor membrane 71 is degreased at a constant temperature for a certain period of time in an atmospheric atmosphere. Note that degreasing here refers to the organic component contained in the piezoelectric precursor membrane 71, for example, NO.₂, CO₂, H₂It is to leave as O etc.

Then, by repeating such steps of coating, drying, and degreasing a predetermined number of times, for example, twice in this embodiment, the piezoelectric precursor film 71 is made to a predetermined thickness as shown in FIG. 4 (b). The piezoelectric precursor film 71 is formed and crystallized by heat-treating the piezoelectric precursor film 71 in a diffusion furnace to form the piezoelectric film 72. That is, by firing the piezoelectric precursor film 71, crystals grow around the seed titanium layer 65 to form the piezoelectric film 72. For example, in the present embodiment, the piezoelectric precursor film 71 is fired by heating at about 700 ° C. for 30 minutes to form the piezoelectric film 72. The crystals of the piezoelectric film 72 formed in this way are preferentially oriented toward the (100) plane.

Further, by repeating the above-mentioned steps of coating, drying, degreasing, and firing a plurality of times, as shown in FIG. 4 (c), a predetermined thickness consisting of a plurality of layers, in this embodiment, a five-layer piezoelectric film 72. The piezoelectric layer 70 is formed. For example, when the film thickness per application of the sol is about 0.1 μm, the film thickness of the entire piezoelectric layer 70 is about 1 μm.

By forming the piezoelectric layer 70 by the above steps, the characteristics of the piezoelectric layer 70 can be improved and the characteristics can be stabilized. That is, the crystallinity of the piezoelectric layer 70, for example, the degree of orientation, strength, particle size, etc., is easily affected by the substrate, and the surface roughness Ra of the lower electrode film 60 and the insulator film 55, which are the substrates, is compared. The coarser the target, the more the crystallinity tends to improve, but if it is too coarse, the crystallinity deteriorates. In the present invention, the surface roughness Ra of the insulator film 55, which is the outermost layer constituting the vibrating plate underlying the piezoelectric layer 70, is controlled within the range of 1 to 3 nm, so that the surface roughness of the lower electrode film 60 is roughened. The Ra is controlled within the range of 1 to 3 nm, and the crystallinity of the piezoelectric layer 70 formed on the lower electrode film 60 is improved. As a result, the piezoelectric layer 70 having excellent electrical and mechanical properties can be formed. Further, the variation in the characteristics of the piezoelectric layer 70 within the same wafer can be suppressed to be extremely small.

Further, the crystallinity of the piezoelectric layer 70 can be easily controlled, the piezoelectric layer 70 having desired characteristics can be manufactured relatively easily, and mass productivity is greatly improved. That is, in the present invention, by controlling the surface roughness Ra of the insulator film 55 to be within the range of 1 to 3 nm, the sputter conditions for forming the seed titanium layer 65 on the insulator film 55 are strictly controlled. Even without it, the characteristics of the piezoelectric layer 70 formed on the insulator layer 70 can be relatively easily improved as compared with the case where the surface roughness Ra of the insulator layer is outside the predetermined range, and the piezoelectric layer can be improved. The characteristics of 70 can be stabilized relatively easily. As a result, the yield can be improved.

The material of the piezoelectric layer 70 is a relaxa ferroelectric material obtained by adding a metal such as niobium, nickel, magnesium, bismuth or yttrium to a ferroelectric piezoelectric material such as lead zirconate titanate (PZT). Etc. may be used. The composition may be appropriately selected in consideration of the characteristics, application, etc. of the piezoelectric element. For example, PbTiO.₃(PT), PbZrO₃(PZ), Pb (Zr)_xTi_1-x) O₃(PZT), Pb (Mg)_1/3Nb_2/3) O₃-PbTiO₃(PMN-PT), Pb (Zn)_1/3Nb_2/3) O₃-PbTiO₃(PZN-PT), Pb (Ni_1/3Nb_2/3) O₃-PbTiO₃(PNN-PT), Pb (In)_1/2Nb_1/2) O₃-PbTiO₃(PIN-PT), Pb (Sc)_1/3Ta_2/3) O₃-PbTiO₃(PST-PT), Pb (Sc)_1/3Nb_2/3) O₃-PbTiO₃(PSN-PT), BiScO₃-PbTiO₃(BS-PT), BiYbO₃-PbTiO₃(BY-PT) and the like. Further, the method for producing the piezoelectric layer 70 is not limited to the sol-gel method, and for example, a MOD (Metal-Organic Decomposition) method or the like may be used.

Further, after the piezoelectric layer 70 is formed in this way, as shown in FIG. 5A, for example, the upper electrode film 80 made of iridium is formed on the entire surface of the flow path forming substrate wafer 110. Next, as shown in FIG. 5B, the piezoelectric layer 70 and the upper electrode film 80 are patterned in a region facing each pressure generating chamber 12 to form the piezoelectric element 300. Next, the lead electrode 90 is formed. Specifically, as shown in FIG. 5C, a metal layer 91 made of, for example, gold (Au) is formed over the entire surface of the flow path forming substrate wafer 110. After that, for example, the lead electrode 90 is formed by patterning the metal layer 91 for each piezoelectric element 300 via a mask pattern (not shown) made of a resist or the like.

Next, as shown in FIG. 5D, the protective substrate wafer 130, which is a silicon wafer and serves as a plurality of protective substrates 30, is bonded to the piezoelectric element 300 side of the flow path forming substrate wafer 110. Since the protective substrate wafer 130 has a thickness of, for example, about 400 μm, the rigidity of the flow path forming substrate wafer 110 is significantly improved by joining the protective substrate wafer 130.

Next, as shown in FIG. 6A, the flow path forming substrate wafer 110 is polished to a certain thickness and then wet-etched with fluorine to obtain the flow path forming substrate wafer 110 to a predetermined thickness. To. For example, in the present embodiment, the wafer 110 for the flow path forming substrate is etched so as to have a thickness of about 70 μm. Next, as shown in FIG. 6B, a mask film 52 made of, for example, silicon nitride (SiN) is newly formed on the flow path forming substrate wafer 110 and patterned into a predetermined shape. Then, by anisotropically etching the flow path forming substrate wafer 110 through the mask film 52, as shown in FIG. 6C, the flow path forming substrate wafer 110 is connected to the pressure generating chamber 12 and the communication portion. 13 and the ink supply path 14 and the like are formed.

After that, unnecessary portions of the outer peripheral edges of the flow path forming substrate wafer 110 and the protective substrate wafer 130 are removed by cutting, for example, by dicing or the like. Then, the nozzle plate 20 having the nozzle opening 21 formed on the surface of the flow path forming substrate wafer 110 opposite to the protective substrate wafer 130 is joined, and the compliance substrate 40 is joined to the protective substrate wafer 130. By dividing the wafer 110 or the like for the flow path forming substrate into the flow path forming substrate 10 or the like having one chip size as shown in FIG. 1, the inkjet recording head of the present embodiment is obtained.

Here, a zirconium layer having a surface roughness Ra of about 2.2 nm was formed on the elastic film, with a sputter pressure of about 0.5 Pa, a sputter output of 500 W, and a target spacing (distance between the target and the substrate) of about 65 mm. Later, except that the insulator film was formed by thermal oxidation at about 700 to 900 ° C. for about 15 to 60 minutes, the one produced by the above-mentioned production method was used as the inkjet recording head of Example 1. The surface roughness Ra of the piezoelectric layer (PZT layer) of the head of Example 1 was about 2.1 nm. FIG. 7 (a) shows an SEM (scanning electron microscope) photograph of the surface of the piezoelectric layer of Example 1.

For comparison, Comparative Example 1 was prepared in the same manner as in Example 1 except that the sputtering conditions for forming the zirconium layer were a sputtering pressure of 0.3 Pa, a sputtering output of 1000 W, and a target spacing of 170 mm. It was an inkjet recording head. The surface roughness Ra of the piezoelectric layer (PZT) of the head of Comparative Example 1 was about 0.8 nm. FIG. 7 (b) shows an SEM photograph of the surface of the piezoelectric layer of Comparative Example 1.

As shown in FIGS. 7 (a) and 7 (b), it can be confirmed that the piezoelectric layer of Example 1 is a denser layer than the piezoelectric layer of Comparative Example 1. Then, when the characteristics of the piezoelectric element (piezoelectric layer) were compared with respect to the heads of Example 1 and Comparative Example 1, the head of Example 1 had higher characteristics of the piezoelectric layer than the head of Comparative Example 1. I found out.

(Other Embodiments) Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, an inkjet recording head has been exemplified as an example of a head used in a liquid injection device, but the present invention broadly covers a liquid injection head in general, and uses a liquid other than ink. Of course, it can also be applied to what is injected. Other liquid injection heads include, for example, various recording heads used in image recording devices such as printers, color material injection heads used in manufacturing color filters such as liquid crystal displays, organic EL displays, and FEDs (surface emitting displays). Examples thereof include an electrode material injection head used for forming an electrode, a bioorganic substance injection head used for producing a biochip, and the like. Further, the present invention can be applied not only to an actuator device mounted as a liquid ejection means on such a liquid injection head (inkjet recording head), but also to an actuator device mounted on any device. For example, the actuator device can be applied to a sensor or the like in addition to the head described above.

<figref num="1">It is an exploded perspective view of the recording head which concerns on Embodiment 1. FIG.</figref><figref num="2">FIG. 5 is a plan view and a cross-sectional view of the recording head according to the first embodiment.</figref><figref num="3">It is sectional drawing which shows the manufacturing process of the recording head which concerns on Embodiment 1. FIG.</figref><figref num="4">It is sectional drawing which shows the manufacturing process of the recording head which concerns on Embodiment 1. FIG.</figref><figref num="5">It is sectional drawing which shows the manufacturing process of the recording head which concerns on Embodiment 1. FIG.</figref><figref num="6">It is sectional drawing which shows the manufacturing process of the recording head which concerns on Embodiment 1. FIG.</figref><figref num="7">It is an SEM photograph of the surface of the piezoelectric layer of Example 1 and Comparative Example 1.</figref>

Code description

10 Flow path forming substrate, 12 Pressure generating chamber, 20 Nozzle plate, 21 Nozzle opening, 30 Protective substrate, 40 Compliance substrate, 50 Elastic film, 55 Insulation film, 60 Lower electrode film, 65 kinds of titanium layer, 70 Piezoelectric layer , 80 Upper electrode film, 300 Piezoelectric element