JP2005209898A - Piezoelectric material element, manufacturing method thereof, and liquid injection head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric material element which does not easily generate breakdown of the element by dispersing stress generated, and also to provide a liquid injection head using the same and a manufacturing method thereof. <P>SOLUTION: A lower electrode 33 including a part of different thickness is provided and a region in the alignment of 111 and a region in the alignment of 100 in different piezoelectric characteristics are formed to a piezoelectric material film 43. Accordingly, a large stain is attained at the area in which a large strain is necessary, while a small strain is attained at the area where is likely to result in breakdown of the element with the large strain. Particularly, stress is alleviated and breakdown of element is prevented by reducing the strain at the circumference of a pressure generating chamber 12 of the liquid injection head 220. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a piezoelectric element having an electromechanical conversion function, a liquid ejecting head using the same, and a liquid ejecting apparatus.

  Conventionally, there is an ink jet recording head as an example of a liquid ejecting head. This ink jet recording head uses a piezoelectric actuator as a drive source for ink ejection of a printer. The piezoelectric actuator generally includes a pressure generation chamber that communicates with a nozzle opening (discharge port) that discharges ink droplets, a vibration plate that defines one surface of the pressure generation chamber, a lower electrode formed on the vibration plate, And a piezoelectric element having a piezoelectric film and an upper electrode. In such an ink jet recording head, various improvements have been made for the purpose of obtaining stable droplet discharge characteristics and improving reliability.

For example, Japanese Patent Laid-Open No. 2000-198197 discloses an ink jet recording head having a piezoelectric active portion and a piezoelectric inactive portion in a region facing a pressure generating chamber. By this piezoelectric body inactive portion, displacement at the boundary between the pressure generating chamber and the peripheral wall is suppressed, and peeling of the piezoelectric layer, generation of cracks, and the like are prevented.
JP 2000-198197 A

  However, the piezoelectric non-active portion cannot be provided along the entire circumference of the pressure generating chamber, and it is inevitable that a portion where stress is concentrated is generated.

  It is an object of the present invention to provide a liquid ejecting head using the same and a method of manufacturing the same by dispersing stress generated by a piezoelectric actuator including a piezoelectric element so that the element is hardly damaged.

  In order to achieve this object, a piezoelectric element of the present invention includes a lower electrode supported on a substrate, a piezoelectric film formed on the lower electrode, and an upper electrode formed on the piezoelectric film. The orientation of the crystal structure of the piezoelectric film formed on the lower electrode varies depending on the thickness of the lower electrode. Accordingly, the piezoelectric characteristics are different between a portion where a large strain is required and a portion where the large strain may cause the device to be damaged, thereby preventing the device from being damaged.

  In the piezoelectric element, the piezoelectric film is formed by laminating a plurality of layers, and the piezoelectric film formed on the plurality of layers by making a difference in thickness of a layer in contact with the lower electrode. The crystal orientation can be made different. By making the layer in contact with the lower electrode a piezoelectric film having a desired crystal structure, the upper piezoelectric film can have the same crystal structure.

  In the piezoelectric element, a surface of the lower electrode that is in contact with the piezoelectric film has a predetermined pattern height distribution, and the piezoelectric film has a thickness of a portion on a lower portion than a portion on a high portion of the lower electrode. It is desirable to form it thickly. By providing a height distribution on the surface of the lower electrode, the thickness of each part of the piezoelectric film can be easily set to a desired thickness.

  In the piezoelectric element, the substrate-side surface of the lower electrode has a predetermined pattern height distribution, and the surface of the lower electrode in contact with the piezoelectric film corresponds to the height distribution of the substrate-side surface. You may have. By providing the surface on the substrate side with a height distribution, the surface of the lower electrode can be easily provided with a height distribution.

  In the piezoelectric element, the thin portion of the piezoelectric film is tetragonal and preferably has 100 orientation. Since the strain is relatively small, the stress can be relaxed.

  In the piezoelectric element, the thick portion of the piezoelectric film is tetragonal and preferably has 111 orientation. A large displacement can be obtained by increasing the distortion.

  In the piezoelectric element, the thickness of the piezoelectric film is preferably such that a portion supported by the substrate is formed thicker than other portions. Since the portion supported by the substrate becomes a clamp portion of the piezoelectric element, the strain can be reduced and the stress can be relaxed.

  Another piezoelectric element of the present invention includes a lower electrode supported by a substrate, a piezoelectric film formed on the lower electrode, and an upper electrode formed on the piezoelectric film, and the piezoelectric film Is tetragonal and has a 100 orientation and a tetragonal and 111 orientation. Accordingly, the piezoelectric characteristics are different between a portion where a large strain is required and a portion where the large strain may cause the device to be damaged, thereby preventing the device from being damaged.

  In the piezoelectric element, the piezoelectric film preferably has a portion supported by the substrate having a 100 orientation and the other portion having a 111 orientation. Since the portion supported by the substrate becomes a clamp portion of the piezoelectric element, the strain can be reduced and the stress can be relaxed.

  According to another aspect of the invention, there is provided a liquid jet head including a piezoelectric actuator including the piezoelectric element and a diaphragm formed between the piezoelectric element and the substrate. A pressure generation chamber whose internal volume changes due to mechanical displacement, and a discharge port that communicates with the pressure generation chamber and discharges droplets are provided. Therefore, the liquid ejecting head is highly reliable with less element damage.

  In the liquid ejecting head, it is preferable that the thick portion of the piezoelectric film is formed in a region facing a peripheral portion of the pressure generating chamber. Since the region facing the peripheral edge of the pressure generating chamber is a clamp portion of the piezoelectric element, the stress can be reduced by reducing the strain.

  Another liquid ejecting head according to the present invention includes a piezoelectric actuator including the piezoelectric element described above and a diaphragm formed between the piezoelectric element and the substrate, and the piezoelectric actuator formed on the substrate. A pressure generation chamber whose internal volume changes due to mechanical displacement of and a discharge port that discharges droplets in communication with the pressure generation chamber.The portion that is tetragonal and has a 111 orientation is A portion that is formed in a region facing the central portion of the pressure generating chamber and has the tetragonal system and 100 orientation is formed in a region that faces the peripheral portion of the pressure generating chamber. Since the region facing the peripheral edge of the pressure generating chamber serves as a clamp portion of the piezoelectric element, the strain can be reduced to relieve the stress, and a large strain can be obtained in the region facing the central portion of the pressure generating chamber. it can.

  A liquid ejecting apparatus according to an aspect of the invention includes the above-described liquid ejecting head and a driving device that drives the liquid ejecting head. Therefore, the liquid ejecting apparatus is highly reliable because the element is hardly damaged.

  The method for manufacturing a piezoelectric element of the present invention includes a step of forming a lower electrode on a substrate, a step of forming a piezoelectric film on the lower electrode, and a step of forming an upper electrode on the piezoelectric film, The step of forming the lower electrode is a step of forming the lower electrode such that a predetermined pattern height distribution is formed on the piezoelectric film forming surface of the lower electrode, and the step of forming the piezoelectric film includes the step of forming the piezoelectric film. In this process, a sol containing a constituent metal element of a piezoelectric body is applied onto the lower electrode by a spin coating method, and the sol is gelled and crystallized. Thereby, the thickness of each part of a piezoelectric film can be easily made into desired thickness.

  In the manufacturing method, the step of forming the lower electrode includes forming a conductive layer to be the lower electrode so that the surface is flat, and removing the conductive material near the surface of the conductive layer in a predetermined pattern. A height distribution may be formed on the piezoelectric film forming surface of the lower electrode. Thereby, it is possible to easily form a process distribution of a predetermined pattern on the surface of the lower electrode.

  Next, a piezoelectric element and a piezoelectric actuator according to a preferred embodiment of the present invention, a liquid jet head using the same, and a manufacturing method thereof will be described with reference to the drawings.

  Note that in this embodiment, an ink jet recording head that ejects ink droplets as a liquid ejecting head and a printer that includes an ink jet recording head as a liquid ejecting apparatus will be described as an example. The embodiments described below are examples for explaining the present invention, and the present invention is not limited only to these embodiments. Therefore, the present invention can be implemented in various forms without departing from the gist thereof.

  1 is a perspective view showing a printer according to the present embodiment, FIG. 2 is an exploded perspective view of an ink jet recording head used in the printer shown in FIG. 1, and FIG. 3 is an ink jet recording head shown in FIG. FIG. 4 is a cross-sectional view taken along line ii shown in FIG. 3, FIG. 5 is a cross-sectional view taken along line ii-ii shown in FIG. 3, and FIGS. FIG. 7 is a process diagram illustrating a method for manufacturing the piezoelectric actuator and the ink jet recording head according to the present embodiment.

  As shown in FIG. 1, the printer 1 according to this embodiment includes a head unit 200 having a plurality of ink jet recording heads 220 (see FIG. 2), and the head unit 200 constitutes an ink supply unit. Cartridges 1A and 1B are detachably provided. In the present embodiment, the cartridge 1A has one chamber and contains a black ink composition. The cartridge 1B is partitioned into, for example, three rooms, and each room contains a cyan ink composition, a magenta ink composition, and a yellow ink composition. A head unit 200 on which these cartridges 1A and 1B are detachably mounted is mounted on a carriage 3. The carriage 3 is provided on a carriage shaft 5 attached to a printer body 4 so as to be movable in the axial direction. Yes.

  The printer body 4 is provided with a drive motor 6 for driving the carriage 3, and the driving force of the drive motor 6 is transmitted to the carriage 3 through a plurality of gears and a timing belt 7 (not shown). Thus, the carriage 3 on which the head unit 200 is mounted is moved along the carriage shaft 5.

  Further, the printer body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S that is a recording medium such as paper fed by a paper feed roller (not shown) is conveyed on the platen 8. It has become so. A desired ink composition is ejected from the head unit 200 onto the recording sheet S at a desired timing, so that characters, images, and the like are printed.

  As shown in FIGS. 2 to 5, the ink jet recording head 220 according to the present embodiment includes a flow path forming substrate 10 in which a pressure generating chamber 12 communicating with the nozzle openings 21 is formed, and one of the flow path forming substrates 10. The piezoelectric element 300 is provided on the direction side with a diaphragm 50 interposed therebetween. The diaphragm 50 and the piezoelectric element 300 constitute a piezoelectric actuator as a drive source for increasing the pressure in the pressure generating chamber 12 and ejecting ink droplets from the nozzle openings 21.

The flow path forming substrate 10 is composed of a silicon single crystal substrate, and a vibration plate 50 formed on one side of the flow path forming substrate 10 is formed by previously oxidizing the flow path forming substrate 10 by thermal oxidation. It is composed of an oxide film 51 made of silicon (SiO ₂ ) and a diffusion prevention film 52 formed on the oxide film 51. (See FIGS. 4 and 5). In this embodiment, the diffusion prevention film 52 is composed of a zirconium oxide (ZrO ₂ ) film, and lead (Pb) contained in a piezoelectric film 43 described later is diffused into the oxide film 51. It has a function to prevent this.

  The flow path forming substrate 10 is formed with a plurality of pressure generating chambers 12 partitioned by a plurality of partition walls 22 by anisotropic etching from the other side. A reservoir 100 serving as a common ink chamber for each pressure generating chamber 12 is communicated with a reservoir portion 31 provided on a reservoir forming substrate 30 described later on the outside in the direction in which the nozzle openings of the pressure generating chambers 12 are arranged. A communicating portion 13 is formed. The communication portion 13 is in communication with one end portion in the direction in which the nozzle openings of the pressure generating chambers 12 are arranged in a row via the ink supply path 14.

  On the opening surface side of the flow path forming substrate 10, a nozzle plate 20 having a nozzle opening 21 communicating with the side opposite to the ink supply path 14 of each pressure generating chamber 12 is provided via an adhesive, a heat welding film, or the like. It is fixed. That is, in the present embodiment, two rows of nozzle rows 21 </ b> A in which the nozzle openings 21 are arranged in parallel are provided in one ink jet recording head 220.

  A piezoelectric element 300 including a lower electrode 33 patterned in a predetermined shape, a piezoelectric film 43 made of lead zirconate titanate (PZT), and an upper electrode 44 is formed on the diaphragm 50. ing.

  As shown in FIG. 4, in a region facing the peripheral edge of the pressure generation chamber 12, a recess 33 c is formed on the surface of the lower electrode 33, and the piezoelectric film 43 on the recess 33 c is located at the center of the pressure generation chamber 12. It is thicker than the piezoelectric film 43 in the region facing the part. The thick portion of the piezoelectric film 43 is tetragonal and has 100 orientation, and the other thin portion of the piezoelectric film 43 is tetragonal and has 111 orientation.

  In the piezoelectric film 43, the 111-oriented portion has a large piezoelectric constant and a large displacement when a voltage is applied, whereas the 100-oriented portion has a smaller piezoelectric constant than the 111-oriented portion and a small displacement when a voltage is applied. Since the 100-oriented portion is formed in a region facing the peripheral portion of the pressure generating chamber 12, stress is not concentrated on the region functioning as a clamp portion that supports the piezoelectric element, and damage to the element is prevented. be able to. Further, since the 111-oriented portion is formed in a region facing the central portion of the pressure generating chamber 12, a large displacement can be obtained.

  The recess 33c is preferably inclined gently from a region facing the peripheral edge of the pressure generating chamber 12 to a region facing the central portion of the pressure generating chamber 12, and the angle thereof is 5 degrees to 20 with respect to the substrate surface. It is preferable that it is about a degree. When the inclination angle exceeds 20 degrees, the lattice discontinuity between the piezoelectric film on the region facing the peripheral edge of the pressure generating chamber 12 and the piezoelectric film on the region facing the central portion of the pressure generating chamber 12 This is because, if the angle is less than 5 degrees, a recess having a sufficient depth may not be formed.

  In this embodiment, the diaphragm 50 is formed flat, and the surface of the lower electrode 33 is recessed by reducing the thickness of the lower electrode 33 in the region facing the peripheral edge of the pressure generating chamber. The shape corresponding to the depression of the diaphragm 50 is not limited by reducing the thickness of the diaphragm 50 in the region facing the peripheral edge of the pressure generating chamber and forming the lower electrode 33 with a uniform thickness thereon. In addition, a depression on the surface of the lower electrode 33 may be formed.

  A reservoir forming substrate 30 having a reservoir portion 31 constituting at least a part of the reservoir 100 is joined on the flow path forming substrate 10 on which such a piezoelectric element 300 is formed. In the present embodiment, the reservoir portion 31 is formed across the reservoir forming substrate 30 in the thickness direction and across the width direction of the pressure generating chamber 12. A reservoir 100 that is in communication with the unit 13 and serves as an ink chamber common to the pressure generation chambers 12 is configured.

  Examples of the reservoir forming substrate 30 include glass, ceramic, metal, plastic, and the like. However, it is preferable to use a material that is substantially the same as the coefficient of thermal expansion of the flow path forming substrate 10. Then, the silicon single crystal substrate made of the same material as the flow path forming substrate 10 was used.

  Furthermore, a drive IC 110 for driving each piezoelectric element 300 is provided on the reservoir forming substrate 30. Each terminal of the drive IC 110 is connected to a lead wiring drawn from an individual electrode of each piezoelectric element 300 via a bonding wire or the like (not shown). Each terminal of the driving IC 110 is connected to the outside via an external wiring 111 such as a flexible printed cable (FPC), and receives various signals such as a print signal from the outside via the external wiring 111. .

  A compliance substrate 40 is bonded on the reservoir forming substrate 30. In the region of the compliance substrate 40 facing the reservoir 100, an ink introduction port 45 for supplying ink to the reservoir 100 is formed by penetrating in the thickness direction. Further, the region other than the ink inlet 45 in the region facing the reservoir 100 of the compliance substrate 40 is a flexible portion 46 formed thin in the thickness direction, and the reservoir 100 is sealed by the flexible portion 46. Has been. The flexible portion 46 provides compliance within the reservoir 100.

  As described above, the ink jet recording head 220 according to the present embodiment includes the four substrates of the nozzle plate 20, the flow path forming substrate 10, the reservoir forming substrate 30, and the compliance substrate 40. On the compliance substrate 40 of the ink jet recording head 220, the ink introduction port 45 communicates with an ink communication path of a cartridge case (not shown), and ink from the cartridge case is supplied to the ink introduction port 45. A head case 230 is provided in which an ink supply communication path 231 is provided. The head case 230 is provided with a recess (not shown) in a region facing the flexible portion 46 so that the flexible portion 46 is flexibly deformed. The head case 230 is provided with a drive IC holding part 233 penetrating in the thickness direction in a region facing the drive IC 110 provided on the reservoir forming substrate 30, and the external wiring 111 is connected to the drive IC holding part. The drive IC 110 is connected through the H.233.

  Such an ink jet recording head 220 takes in ink supplied from the ink cartridge from the ink introduction port 45, fills the interior from the reservoir 100 to the nozzle opening 21, and then in accordance with a recording signal from the drive IC 110, A voltage is applied to each piezoelectric element 300 corresponding to the pressure generating chamber 12 to cause the diaphragm 50 to bend and deform, thereby increasing the pressure in each pressure generating chamber 12 and ejecting ink droplets from the nozzle openings 21.

  Next, a method for manufacturing the ink jet recording head 220 according to the present embodiment will be described with reference to FIGS.

(Diaphragm forming step: S1)
A flow path forming substrate 10 made of a silicon single crystal substrate (for example, a thickness of about 200 μm) is treated at a high temperature in an oxidizing atmosphere containing oxygen or water vapor, and an oxide film 51 made of a silicon dioxide film is formed on the flow path forming substrate 10. (For example, a thickness of about 1 μm) is formed. In this step, the CVD method can be used in addition to the thermal oxidation method that is usually used.

  Next, a diffusion prevention film 52 (for example, a thickness of about 200 nm to 400 nm) made of a zirconium oxide film is formed on the oxide film 51. The diffusion prevention film 52 is obtained by forming a zirconium layer by, for example, a sputtering method or a vacuum deposition method and performing a high temperature treatment in an oxygen atmosphere. Alternatively, zirconium oxide may be directly formed by performing RF sputtering using a zirconium oxide target. In this way, the diaphragm 50 composed of the oxide film 51 and the diffusion preventing film 52 is formed.

(Process for forming lower electrode forming film: S2)
Next, a lower electrode forming film 33a for later forming the lower electrode 33 is formed on the diffusion preventing film 52 by patterning. In the present embodiment, the lower electrode forming film 33a includes, for example, a step of forming a layer containing iridium (Ir) by sputtering or the like, and platinum (Pt) by sputtering or the like on the Ir layer. It was formed by performing a step of forming a layer and a step of forming a layer containing iridium on the Pt layer by sputtering or the like. Note that an adhesion layer (not shown) made of titanium may be formed on the diffusion preventing film 52 by sputtering or vacuum deposition prior to the formation of the lower electrode forming film 33a.

  In the lower electrode forming film 33 a, a recess 33 c is formed in a region facing the peripheral portion of the pressure generating chamber 12. The recess 33c is formed by scraping the surface of the lower electrode forming film 33a by ion milling, dry etching, or wet etching. For example, if the thickness of the lower electrode formation film 33a is 200 nm, about 40 nm is removed, and the thickness of the lower electrode formation film 33a in this portion is about 160 nm.

  The present invention is not limited to this, and the lower electrode forming film 33a may be formed by sputtering after the diaphragm 50 is shaved by ion milling, dry etching, or wet etching. When film formation by sputtering is performed on the uneven surface of the vibration plate 50, an uneven surface corresponding to the uneven surface of the vibration plate 50 is also formed on the lower electrode forming film 33a.

  After forming the lower electrode forming film 33a, a titanium (Ti) layer (not shown) is formed on the lower electrode forming film 33a continuously. This titanium layer has a function as a nucleus for crystallizing the piezoelectric precursor film 43a to be formed later. By crystallizing the piezoelectric precursor film 43a using the titanium crystal as a nucleus, Growth occurs from the lower electrode forming film 33a side, and a dense columnar crystal can be obtained. This titanium layer is preferably formed by, for example, sputtering.

(Formation process of piezoelectric film first layer: S3 and S4)
Next, the piezoelectric precursor film 43a is formed on the lower electrode forming film 33a with a thickness not more than a desired thickness of the piezoelectric film 43 to be finally formed, preferably not more than half of the desired thickness. Form. For example, when the entire piezoelectric film 43 having a film thickness of 1500 nm is composed of seven layers, in this first step, the piezoelectric precursor film 43a composed of at least one layer of 90 nm in the thick part and 50 nm in the thin part is formed. (See S3).

  Specifically, a sol made of an organometallic alkoxide solution is applied onto the lower electrode forming film 33a by a sol-gel method by a coating method such as spin coating. Then, it is dried at a constant temperature for a certain time, and the solvent is evaporated. After drying, the product is further degreased at a predetermined high temperature for a certain period of time in an air atmosphere to thermally decompose the organic ligand coordinated to the metal to obtain a metal oxide. The piezoelectric precursor film 43a is laminated by repeating the coating, drying, and degreasing steps a predetermined number of times, for example, twice. By these drying and degreasing treatments, the metal alkoxide and acetate in the solution form a metal, oxygen, and metal network through thermal decomposition of the ligand.

  As described above, by applying the sol containing the constituent metal elements of the piezoelectric body by the spin coating method, the sol and the piezoelectric obtained by drying and degreasing the sol regardless of the unevenness of the surface of the lower electrode forming film 33a. The body precursor film 43a has a flat surface. Accordingly, the piezoelectric precursor film 43a on the depression 33c is thicker than the other portions. For example, when the depression 33c is 40 nm deeper than the other part of the surface of the lower electrode forming film 33a, the piezoelectric precursor film 43a on the depression 33c is 40 nm thicker than the other part.

  Next, the piezoelectric precursor film 43a is fired and crystallized. By this firing, the piezoelectric precursor film 43a changes from an amorphous state to a tetragonal crystal structure and changes to a film exhibiting an electromechanical conversion action. The first layer 43b of the first piezoelectric film is formed by performing the steps of forming and firing the piezoelectric precursor film 43a described above once. (See S4).

  When the orientation of the first layer 43b of the piezoelectric film thus formed is measured by the X-ray diffraction wide angle method, the portion on the depression 33c has a (100) plane orientation degree of about 90%, and the other portions are (111). ) The degree of plane orientation is about 90%. Here, (100) plane orientation or (111) plane orientation is (100) plane or (111) when the sum of diffraction intensities of (100) plane, (110) plane, and (111) plane is taken as 100. ) The ratio of the diffraction intensity of the surface. The orientation of the piezoelectric film first layer 43b is considered to depend on the film thickness when the piezoelectric film is formed. That is, when the film thickness of the piezoelectric film is 90 nm or more, the orientation is 100, and when the film thickness of the piezoelectric film is 50 nm or less, the orientation is 111.

  In a preferred embodiment, the recess 33 c on the surface of the lower electrode has a gentle slope over a region facing the central portion of the pressure generating chamber 12. For this reason, the piezoelectric film first layer 43b gradually increases in the degree of orientation of the 111 plane from the 100 orientation from the region facing the peripheral portion of the pressure generating chamber 12 to the region facing the central portion of the pressure generating chamber 12. Therefore, discontinuity of the lattice of the piezoelectric film hardly occurs, and a highly reliable piezoelectric film can be obtained.

  With the firing, the lower electrode forming film 33a is also partially oxidized, and the film thickness is increased by partly diffusing the components of the piezoelectric film. Here, in the method of forming the piezoelectric film after patterning the lower electrode formation film, the increase in the film thickness in the vicinity of the patterning boundary of the lower electrode formation film is smaller than in the other portions, resulting in non-uniform film thickness. However, according to the method of the present embodiment, since the piezoelectric film first layer 43b is formed before the lower electrode forming film 33a is patterned, the film thickness of the lower electrode forming film 33a increases as a whole. It will not be uneven.

  Next, a mask having a desired shape is formed on the piezoelectric film first layer 43b, and the piezoelectric film first layer 43b and the lower electrode forming film 33a are patterned by etching other than the mask region, so that the lower electrode 33 and wiring electrode 33b are formed. Specifically, first, a resist material having a uniform thickness is applied onto the piezoelectric film first layer 43b by a spinner method, a spray method, or the like (not shown), and then the resist material is patterned into a predetermined shape. Then, exposure and development are performed to form a resist pattern (not shown), and using this as a mask, the piezoelectric film first layer 43b and the lower electrode forming film 33a are removed by etching by a commonly used ion milling or dry etching method or the like. Then, the diffusion prevention film 52 is exposed.

(Piezoelectric film second layer forming step: S5)
Next, a piezoelectric film second layer is formed on the piezoelectric film first layer 43b and the exposed diffusion prevention film 52 by a process similar to the process of forming the piezoelectric film first layer, and this is performed a plurality of times. The piezoelectric film 43 composed of a plurality of layers is formed repeatedly. The piezoelectric films of the second layer and the third and subsequent layers are, for example, 200 nm per layer and are stacked until a predetermined film thickness is obtained. Note that before the formation of the second piezoelectric film, a titanium layer may be formed again on the piezoelectric film first layer 43b and the exposed diffusion prevention film 52 by sputtering or the like.

  The piezoelectric film second layer thus formed grows under the influence of the piezoelectric film first layer. As a result, the region on the depression 33c facing the peripheral edge of the pressure generating chamber 12 is 100-oriented like the piezoelectric film first layer, and the region facing the central portion of the pressure generating chamber 12 is also the piezoelectric film first layer. Similarly, the orientation becomes 111.

(Upper electrode forming film forming step: S6)
Next, an upper electrode forming film 44a is formed on the piezoelectric film 43 by electron beam evaporation or sputtering. The upper electrode forming film 44a is formed with a film thickness of about 50 nm using platinum, iridium, or other metal.

(Patterning process of piezoelectric film and upper electrode: S7)
Next, the piezoelectric film 43 and the upper electrode forming film 44a are patterned into a predetermined shape of the piezoelectric element 300 to be formed. Specifically, after a resist material is spin-coated on the upper electrode formation film 44a, patterning is performed in accordance with a position where the pressure generation chamber 12 is to be formed. The upper electrode formation film 44a and the piezoelectric film 43 are etched by ion milling or the like using the remaining resist material as a mask. The piezoelectric element 300 is formed by the above process.

(Strip electrode forming step: S8)
Next, a narrow band electrode 55 that conducts the upper electrode 44 and the wiring electrode 33b is formed. The material of the thin strip electrode 55 is preferably made of gold having low rigidity and low electrical resistance, but aluminum, copper, etc. are also suitable. The thin strip electrode 55 is formed with a film thickness of about 0.2 μm, and then patterned so that the conductive portion between each upper electrode 44 and the wiring electrode 33b remains.

(Pressure generation chamber forming step: S9)
Next, anisotropic etching using an active gas such as anisotropic etching or parallel plate type reactive ion etching is performed on the other surface of the flow path forming substrate 10 on which the piezoelectric element 300 is formed to generate pressure. A chamber 12 is formed. A portion left without being etched becomes a partition wall 22 (see FIG. 5).

(Nozzle plate bonding step: S10)
Finally, the nozzle plate 20 is bonded to the channel forming substrate 10 after etching with an adhesive. At the time of bonding, the nozzle openings 21 are aligned so as to be arranged in the respective spaces of the pressure generating chambers 12. The flow path forming substrate 10 to which the nozzle plate 20 is bonded is attached to the head case 230 to complete the ink jet recording head 220.

  In the present embodiment, the case where the diffusion prevention film 52 is made of a zirconium oxide film has been described. Further, it may be composed of other materials such as titanium oxide, and an additive or the like may be added if desired.

In the present embodiment, the case where the piezoelectric film 43 is formed of lead zirconate titanate (PZT) has been described. However, the present invention is not limited to this, and the piezoelectric film 43 is a crystal of piezoelectric ceramics. In addition to a ferroelectric piezoelectric material such as lead zirconate titanate (PZT), a metal oxide such as niobium oxide, nickel oxide or magnesium oxide may be added thereto. In addition, the composition of the piezoelectric film 43 is appropriately selected in consideration of the characteristics, application, etc. of the piezoelectric element. Specifically, lead titanate (PbTiO ₃ ), lead zirconate titanate (Pb (Zr, Ti) O ₃ ), lead lanthanum titanate ((Pb, La), TiO ₃ ), lead lanthanum zirconate titanate ((Pb, La) (Zr, Ti) O ₃ ) or magnesium zirconium niobate lead zirconate titanate (Pb (Zr, Ti) (Mg, Nb) O ₃ ) is preferably used. In addition, a film having excellent piezoelectric characteristics can be obtained by appropriately adding niobium (Nb) to lead titanate or lead zirconate.

  In the present embodiment, an ink jet recording head is shown as an example of a piezoelectric element, but in addition to this, it is used for each device, for example, a microphone, a sounding body, various vibrators, an oscillator, and the like. Needless to say. In addition, the ink jet recording head that ejects ink droplets as the liquid ejecting head and the printer including the ink jet recording head as the liquid ejecting apparatus have been described as an example. It is intended for general injection devices. Examples of the liquid ejecting head include a recording head used in an image recording apparatus such as a printer, a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an organic EL display, and an electrode formation such as an FED (surface emitting display). Electrode material ejecting heads used in manufacturing, bioorganic matter ejecting heads used in biochip production, and the like.

1 is a perspective view showing a printer according to an embodiment. FIG. 2 is an exploded perspective view of an ink jet recording head used in the printer shown in FIG. 1. FIG. 3 is an enlarged plan view of the vicinity of a piezoelectric actuator of the ink jet recording head shown in FIG. 2. It is sectional drawing along the ii line shown in FIG. It is sectional drawing along the ii-ii line | wire shown in FIG. It is process drawing which shows the manufacturing method of the piezoelectric actuator and inkjet recording head concerning this Embodiment. It is process drawing which shows the manufacturing method of the piezoelectric actuator and inkjet recording head concerning this Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Printer, 10 ... Channel formation board | substrate, 12 ... Pressure generation chamber, 33 ... Lower electrode, 33c ... Depression, 43 ... Piezoelectric film, 44 ... Upper electrode , 50 ... diaphragm, 51 ... oxide film, 52 ... diffusion prevention film, 53 ... adhesion region, 220 ... ink jet recording head, 300 ... piezoelectric element

Claims (15)

  A piezoelectric element comprising a lower electrode supported by a substrate, a piezoelectric film formed on the lower electrode, and an upper electrode formed on the piezoelectric film, wherein the thickness of the lower electrode is different The piezoelectric element is characterized in that the orientation of the crystal structure of the piezoelectric film formed on the lower electrode is different. In claim 1,
The piezoelectric film is formed by laminating a plurality of layers, and a thickness of a lowermost layer in contact with the lower electrode among the plurality of layers is different in a predetermined pattern. In claim 1 or claim 2,
A surface of the lower electrode in contact with the piezoelectric film has a predetermined height distribution, and the piezoelectric film is formed such that the thickness of the upper portion of the lower electrode is thicker than the upper portion of the lower electrode. Body element. In claim 3,
A piezoelectric element in which a surface of the lower electrode on the substrate side has a height distribution of a predetermined pattern, and a surface of the lower electrode in contact with the piezoelectric film has a height distribution corresponding to the height distribution of the surface on the substrate side . In any one of Claims 1 thru | or 4,
A piezoelectric element in which the thin part of the piezoelectric film is tetragonal and has 100 orientation. In any one of Claims 1 to 5,
A piezoelectric element in which the thick portion of the piezoelectric film is tetragonal and has 111 orientation. In any one of Claims 1 thru | or 6,
A thickness of the piezoelectric film is a piezoelectric element in which a portion supported by the substrate is formed thicker than other portions.   A piezoelectric element comprising a lower electrode supported by a substrate, a piezoelectric film formed on the lower electrode, and an upper electrode formed on the piezoelectric film, wherein the piezoelectric film is square A piezoelectric element comprising a part that is crystalline and has 100 orientation and a part that is tetragonal and has 111 orientation. In claim 8,
The piezoelectric film is a piezoelectric element in which a portion supported by the substrate has 100 orientation and the other portion has 111 orientation.   A piezoelectric actuator comprising the piezoelectric element according to any one of claims 1 to 7, a diaphragm formed between the piezoelectric element and the substrate, and formed on the substrate, A liquid ejecting head comprising: a pressure generating chamber whose internal volume changes due to mechanical displacement of a piezoelectric actuator; and an ejection port that communicates with the pressure generating chamber and ejects droplets. In claim 10,
The portion where the thickness of the piezoelectric film is thick is a liquid jet head formed in a region facing the peripheral edge of the pressure generating chamber. A piezoelectric actuator comprising the piezoelectric element according to claim 8 or 9, a diaphragm formed between the piezoelectric element and the substrate, and a machine for the piezoelectric actuator formed on the substrate. A pressure generating chamber whose internal volume changes due to a mechanical displacement, and a discharge port that communicates with the pressure generating chamber and discharges a droplet,
The tetragonal and 111-oriented portion is formed in a region facing the central portion of the pressure generating chamber,
The tetragonal and 100-oriented portion is a liquid jet head formed in a region facing the peripheral edge of the pressure generating chamber.   A liquid ejecting apparatus comprising: the liquid ejecting head according to any one of claims 10 to 12; and a driving device that drives the liquid ejecting head. A method for manufacturing a piezoelectric element, comprising: a step of forming a lower electrode on a substrate; a step of forming a piezoelectric film on the lower electrode; and a step of forming an upper electrode on the piezoelectric film,
The step of forming the lower electrode forms the lower electrode so that a predetermined pattern height distribution is formed on the piezoelectric film forming surface of the lower electrode,
The piezoelectric film forming step is a method of manufacturing a piezoelectric element in which a sol containing a constituent metal element of a piezoelectric body is applied on the lower electrode by a spin coating method, and the sol is gelled and crystallized. In claim 14,
The step of forming the lower electrode includes forming a conductive layer to be the lower electrode so that the surface is flat, and removing the conductive material in the vicinity of the surface of the conductive layer in a predetermined pattern to thereby form the piezoelectric body of the lower electrode A method for manufacturing a piezoelectric element, wherein a height distribution is formed on a film forming surface.

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