JP2008060599A - Ferroelectric element and actuator using the same, ink jet head, ink jet record device, and method of manufacturing ferroelectric element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a ferroelectric element capable of improving the insulation property of a ferroelectric film, reliability, and the withstand voltage. <P>SOLUTION: A ferroelectric element has a first electrode (used as a vibrating plate 11 at the same time), a ferroelectric function film 10 formed on the first electrode 11, and second electrode 3 formed on the ferroelectric function film 10. The ferroelectric function film 10 includes a ferroelectric film 10a and at least one kind of element constituting the ferroelectric film 10a and composed of an insulation enhancement film 10b having lower crystallinity than the ferroelectric film 10a. When a half width of a diffraction peak of the ferroelectric film 10a by an X-ray analysis method is "a0", that of the ferroelectric function film 10 being "a", and a rate of increase of the half width being p=(a-a0)/a0, 1<p≤2.5. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a ferroelectric element, an actuator using the same, an ink jet head, an ink jet recording apparatus, and a method for manufacturing a ferroelectric element.

  An ink jet head of a conventional ink jet recording apparatus includes a pressure chamber part having a pressure chamber for storing ink liquid, and a ferroelectric element as an actuator unit for discharging ink droplets from the pressure chamber. . A ferroelectric element includes a ferroelectric film, and individual electrodes and a common electrode that contract and expand by applying a voltage to the ferroelectric film, and vibration that is displaced by the piezoelectric effect of the ferroelectric film. The plate was configured to eject ink droplets from the nozzle holes of the pressure chamber.

  For example, JP-A-2-49471 discloses a lower electrode, a polysilicon oxide film formed on the lower electrode, a ferroelectric film formed on the polysilicon oxide film, and a ferroelectric film. A semiconductor device comprising an upper electrode formed in the above is disclosed.

  Japanese Patent No. 311416 discloses a technique for forming an insulating film composed mainly of SiN between an active element such as a transistor formed on a semiconductor and a capacitor made of a ferroelectric. Yes.

Japanese Patent No. 3139491 discloses a ferroelectric element having a structure in which a ferroelectric is sandwiched between two electrodes, and includes a SiO ₂ film between at least one electrode peripheral portion and the ferroelectric film. A technique for forming a paraelectric layer is disclosed.
JP-A-2-49471 Japanese Patent No. 311416 Japanese Patent No. 3139491

  However, in the conventional ferroelectric element, when a ferroelectric film is formed, crystal structure defects and abnormal growth of crystal grains occur due to contamination of foreign matters, and the ferroelectric film and abnormally grown grains are generated. Defects such as gaps and pinholes occur at the interface. When a ferroelectric element is formed using such a ferroelectric film, a voltage lower than the intrinsic breakdown voltage of the film between the individual electrode and the common electrode can be applied from the defect. Dielectric breakdown may occur.

  In addition, when moisture enters the above defects, there is a problem that the insulating properties of the film are remarkably deteriorated, and the adhesion between the ferroelectric film and the insulating film is deteriorated.

  SUMMARY OF THE INVENTION Accordingly, the present invention relates to a ferroelectric element capable of improving reliability and pressure resistance as well as improving the insulation properties of a ferroelectric film, and an actuator, an ink jet head, an ink jet recording apparatus, and a ferroelectric element using the same. It aims at providing the manufacturing method of.

  In order to solve this problem, a ferroelectric element of the present invention is formed on a first electrode, a ferroelectric functional film formed on the first electrode, and the ferroelectric functional film. The ferroelectric functional film includes a ferroelectric film and at least one element of constituent elements of the ferroelectric film, and is more crystalline than the ferroelectric film. A half-width of the diffraction peak by the X-ray analysis of the ferroelectric film is a0, the half-width of the diffraction peak by the X-ray analysis of the ferroelectric functional film is a, When the increase rate is p = (a−a0) / a0, it is composed of a ferroelectric element in which 1 <p ≦ 2.5.

  As described above, since the ferroelectric functional film composed of the ferroelectric film and the insulating reinforcing film containing at least one element of the constituent elements of the ferroelectric film is formed between the electrodes, the ferroelectric film Defects (such as gaps and pinholes generated at the interface between the ferroelectric film and abnormally grown grains) that cause a decrease in insulation properties are completely covered by the insulation enhancement film, improving the insulation of the ferroelectric film, The adhesion between the ferroelectric film and the insulation enhancement film is good, and the dielectric constant of the insulation enhancement film is close to the dielectric constant of the ferroelectric film, thereby improving the reliability and pressure resistance of the ferroelectric film. Since the increase rate of the half width of the diffraction peak by the X-ray analysis method of the ferroelectric film and the ferroelectric functional film is 1 <p ≦ 2.5, the driving voltage is set. The increase in the resistance is suppressed to within 30%, and the reliability and pressure resistance of the ferroelectric film are improved.

  As described above, according to the present invention, the ferroelectric functional film composed of the ferroelectric film and the insulating reinforcing film containing at least one element of the constituent elements of the ferroelectric film is formed between the electrodes. Therefore, defects that cause a decrease in the insulation properties of the ferroelectric film are completely covered by the insulation enhancement film, improving the insulation properties of the ferroelectric film and improving the adhesion between the ferroelectric film and the insulation enhancement film. As a result, the dielectric constant of the insulating enhancement film is close to the dielectric constant of the ferroelectric film, and an effective effect that the driving voltage can be reduced is obtained. Since the increase rate of the half width of the diffraction peak by the X-ray analysis method of the ferroelectric film and the ferroelectric functional film is 1 <p ≦ 2.5, the driving voltage is set. The increase in the resistance is suppressed to within 30%, and the reliability and pressure resistance of the ferroelectric film are improved.

  Further, if the Pb content of the insulation enhancement film is made larger than the Pb content of the ferroelectric film, the Pb concentration on the surface of the ferroelectric film becomes higher, the crystallinity is lowered, and the insulation property of the insulation enhancement film is further increased. An effective effect of strengthening is obtained.

  If the oxygen content of the insulation enhancement film is made larger than the oxygen content of the ferroelectric film, an effective effect that the insulation of the insulation reinforcement film can be enhanced can be obtained.

  If the crystallinity of the insulation enhancement film is made lower than the crystallinity of the ferroelectric film, an effective effect that the insulation of the insulation enhancement film can be enhanced can be obtained.

  According to the actuator using such a ferroelectric element, an effective effect that a stable displacement operation can be performed is obtained.

  According to the ink jet head using such an actuator, it is possible to obtain an effective effect of enabling stable ink discharge.

  In addition, according to the ink jet recording apparatus including such an ink jet head, an effective effect that high quality printing can be performed by stable ink ejection is obtained.

  According to a first aspect of the present invention, there is provided a first electrode, a ferroelectric functional film formed on the first electrode, and a second electrode formed on the ferroelectric functional film. The ferroelectric functional film includes a ferroelectric film and at least one element of constituent elements of the ferroelectric film, and is composed of an insulating reinforcing film having lower crystallinity than the ferroelectric film. The full width at half maximum of the diffraction peak by X-ray analysis of the dielectric film is a0, the full width at half maximum of the diffraction peak by X-ray analysis of the ferroelectric functional film is a, and the increase rate of the full width at half maximum is p = (a−a0) / When a0, it is a ferroelectric element in which 1 <p ≦ 2.5, and the defect of the ferroelectric film is covered with the insulating reinforcing film so that the insulating property of the ferroelectric film is improved, and the ferroelectric The adhesion between the film and the insulation enhancement film is good, and the dielectric constant of the insulation enhancement film is close to the dielectric constant of the ferroelectric film, resulting in an increase in driving voltage of 3 Reliability and pressure resistance of the suppressed and the ferroelectric film within% has the effect of improving.

  The invention according to claim 2 of the present invention is the ferroelectric element according to claim 1, wherein the diffraction peak of the ferroelectric film by the X-ray analysis method is based on the (001) orientation plane. In addition, the insulation of the ferroelectric functional film is improved and the drive voltage is reduced.

  The invention according to claim 3 of the present invention is the method according to claim 1, wherein the diffraction peak of the first electrode or the second electrode by the X-ray analysis method is an X-ray analysis method of the ferroelectric functional film. The ferroelectric element is based on the same orientation plane as the diffraction peak due to the above, and has the effect of improving the insulation of the ferroelectric functional film and reducing the driving voltage.

  According to a fourth aspect of the present invention, in the first aspect, the diffraction peak of the first electrode or the second electrode by the X-ray analysis method is based on a (001) orientation plane. This is a ferroelectric element, which has the effect of improving the insulation of the ferroelectric functional film and reducing the driving voltage.

  The invention according to claim 5 of the present invention is the ferroelectric material according to claim 1, wherein the ferroelectric film is a perovskite oxide containing at least one element of Pb, La, Zr, and Ti. The ferroelectric element is coated with defects in the ferroelectric film to improve the insulating property of the ferroelectric film, and the adhesion between the ferroelectric film and the insulating reinforcing film is good and the insulating reinforcing film The dielectric constant of the ferroelectric film becomes close to the dielectric constant of the ferroelectric film, thereby improving the reliability and pressure resistance of the ferroelectric film.

  The invention described in claim 6 of the present invention is the ferroelectric element according to claim 5, wherein the Pb content of the insulation enhancement film is larger than the Pb content of the ferroelectric film, and the ferroelectric film The surface Pb concentration is increased, the crystallinity is lowered, and the insulating property of the insulating reinforcing film is further enhanced.

  The invention according to claim 7 of the present invention is the ferroelectric element according to claim 5 or 6, wherein the oxygen content of the insulating reinforcing film is larger than the oxygen content of the ferroelectric film, and the insulating reinforcing film It has the effect | action that reinforcement | strengthening of can be aimed at.

  According to an eighth aspect of the present invention, in the first aspect of the present invention, the insulation reinforcing film is a polycrystalline film or an amorphous film containing at least one of a pyrochlore type oxide and a perovskite type oxide. It is a ferroelectric element, and the defects of the ferroelectric film are covered with the insulation enhancement film, so that the insulation property of the ferroelectric film is improved, and the adhesion between the ferroelectric film and the insulation enhancement film is good and insulation is achieved. The dielectric constant of the reinforced film is close to the dielectric constant of the ferroelectric film, so that the reliability and pressure resistance of the ferroelectric film are improved.

  The invention according to claim 9 of the present invention is an actuator in which the ferroelectric element according to any one of claims 1 to 8 is used, and can perform a stable displacement operation. Has an effect.

  According to a tenth aspect of the present invention, there is provided an ink jet head comprising the actuator according to the ninth aspect and a plurality of pressure chambers in which ink liquid is accommodated and the displacement of the actuator acts. It has the effect that it becomes possible to perform.

  The invention according to an eleventh aspect of the present invention is an ink jet recording apparatus including the ink jet head according to the tenth aspect, and has an effect that high-quality printing can be performed by stable ink ejection.

  According to a twelfth aspect of the present invention, there is provided a step of forming a first electrode, a step of forming a ferroelectric functional film on the first electrode, and a second step on the ferroelectric functional film. A method of manufacturing a ferroelectric element comprising the step of forming a ferroelectric functional film and a step of forming a ferroelectric film and an insulation enhancement film, Is an amorphous film containing at least one element of the constituent elements of the ferroelectric film, and this amorphous film is at least using the same film forming apparatus as that for forming the ferroelectric film. This is a method for manufacturing a ferroelectric element in which the film formation temperature is changed, and the ferroelectric film is covered with defects in the ferroelectric film to improve the insulation property of the ferroelectric film, and also in ferroelectric The adhesion between the body film and the insulation reinforcement film is good and the dielectric constant of the insulation reinforcement film is strong With reliability is improved and the withstand voltage of the ferroelectric film becomes close to the dielectric constant of the conductor film, has the effect of additional film-forming apparatus is not required, readily produce the desired film.

  A thirteenth aspect of the present invention is a method of manufacturing a ferroelectric element according to the twelfth aspect of the present invention, wherein the film formation temperature when forming the amorphous film is room temperature, and temperature control is easy. Therefore, the desired thin film can be produced.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In these drawings, the same members are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a perspective view showing an overall schematic configuration of an inkjet recording apparatus using a ferroelectric element according to an embodiment of the present invention, and FIG. 2 shows an overall configuration of an inkjet head in the inkjet recording apparatus of FIG. 3 is a perspective view showing the main part of FIG. 2, FIG. 4 is a cross-sectional view showing the configuration of the actuator part of the ink jet head of FIG. 2, and FIG. 5 is a ferroelectric substance according to an embodiment of the present invention. FIG. 6 is a cross-sectional view showing an element, FIG. 6 is an explanatory view showing the configuration of a cantilever for measuring piezoelectric displacement, and FIG. 7 is a cross-sectional view showing a method for manufacturing an actuator.

  An ink jet recording apparatus 40 shown in FIG. 1 includes an ink jet head 41 of the present invention that performs recording using the piezoelectric effect of a ferroelectric element, and ink droplets ejected from the ink jet head 41 are recorded on a recording medium 42 such as paper. Is recorded on the recording medium 42. The inkjet head 41 is mounted on a carriage 44 provided on a carriage shaft 43 arranged in the main scanning direction X, and reciprocates in the main scanning direction X as the carriage 44 reciprocates along the carriage shaft 43. Move. Further, the ink jet recording apparatus 40 includes a plurality of rollers (moving means) 45 for moving the recording medium 42 in the sub scanning direction Y substantially perpendicular to the width direction of the ink jet head 41 (that is, the main scanning direction X). .

  FIG. 2 shows the overall configuration of the inkjet head 41 according to the embodiment of the present invention, and FIG. 3 shows the configuration of the main part thereof.

  2 and 3, A is a pressure chamber part, and the pressure chamber opening 1 is formed. B is an actuator portion arranged to cover the upper end opening surface of the pressure chamber opening 1, and C is an ink liquid flow path component arranged to cover the lower end opening surface of the pressure chamber opening 1. The pressure chamber opening 1 of the pressure chamber part A is partitioned by an actuator part B and an ink liquid flow path part C positioned above and below to become a pressure chamber 2. In the actuator part B, an individual electrode (second electrode) 3 located above the pressure chamber 2 is arranged. As can be seen from FIG. 2, a large number of these pressure chambers 2 and individual electrodes 3 are arranged in a staggered manner. The ink liquid flow path component C includes a common liquid chamber 5 shared between the pressure chambers 2 arranged in the ink liquid supply direction, a supply port 6 that communicates the common liquid chamber 5 with the pressure chamber 2, An ink flow path 7 through which the ink liquid flows is formed. D is a nozzle plate, in which a nozzle hole 8 communicating with the ink flow path 7 is formed. In FIG. 2, E is an IC chip, which supplies a voltage to a large number of individual electrodes 3 via bonding wires BW.

  Next, the structure of the actuator part B is demonstrated based on FIG.

  In the figure, the actuator part B shows a cross-sectional view in a direction orthogonal to the ink liquid supply direction shown in FIG. In the drawing, a pressure chamber part A having four pressure chambers 2 arranged in the orthogonal direction is drawn for reference.

  The actuator portion B is displaced and vibrated by the individual electrode 3 positioned above each pressure chamber 2, the ferroelectric function film 10 positioned immediately below the individual electrode 3, and the piezoelectric effect of the ferroelectric function film 10. And a diaphragm 11. The diaphragm 11 is made of a conductive material and also serves as a common electrode (first electrode) common to the pressure chambers 2. Furthermore, the actuator part B has the vertical wall 13 located above the division wall 2a which divides each pressure chamber 2 mutually. In the figure, reference numeral 14 denotes an adhesive for bonding the pressure chamber part A and the actuator part B together. Each vertical wall 13 does not adhere to the diaphragm 11 even when a part of the adhesive 14 protrudes to the outside of the partition wall 2a at the time of adhesion using the adhesive 14, and the diaphragm 14 It has the role of increasing the distance between the upper surface of the pressure chamber 2 and the lower surface of the diaphragm 11 so that 11 will cause the desired displacement and vibration. However, the diaphragm and the common electrode may be separate.

  The individual electrode 3, the ferroelectric functional film 10, and the common electrode 11 constitute a ferroelectric element.

  The individual electrode 3 is made of, for example, Pt (platinum), and the diaphragm 11 is made of, for example, Cr (chromium), Cu (copper), Mo (molybdenum), or Ta (tantalum). The individual electrode 3 is formed to a thickness of 0.1 to 1.0 μm, the ferroelectric functional film 10 is formed to a thickness of 2 to 6 μm, and the diaphragm 11 is formed to a thickness of 3 to 10 μm.

  As shown in FIG. 5, the ferroelectric functional film 10 includes a ferroelectric film 10a that is a perovskite oxide made of, for example, lead zirconate titanate (PZT), and at least constituent elements of the ferroelectric film 10a. The insulating reinforcement film 10b contains one kind of element (in this case, at least one kind of element of Pb, Zr, Ti).

Note that a PLT film {for example (Pb _0.9 La _0.1 ) TiO ₃ } or a PLZT film {for example (Pb _0.9 La _0.1 ) (Zr _0.52 Ti _0.48 ) O ₃ } may be applied to the ferroelectric film 10a. Therefore, in this case, the insulating reinforcing film 10b contains at least one element of Pb, La, and Ti.

  Further, FIG. 5 shows the actuator portion B. Since the common electrode 11, the ferroelectric film 10a, the insulation reinforcing film 10b, and the individual electrode 3 are sequentially formed on the substrate corresponding to the vertical wall 13, the insulation reinforcement is performed. The film 10b is located between the ferroelectric film 10a and the individual electrode 3. For example, an individual electrode, a ferroelectric film, an insulating reinforcement film, and a common electrode are formed on an MgO substrate, and this is formed on the vertical wall. In the case where the MgO substrate is removed by etching after bonding to the corresponding substrate, the insulating reinforcing film is located between the ferroelectric film and the common electrode. Therefore, in FIG. 5, the ferroelectric film 10 a is formed on the vibration plate 11 side and the insulation reinforcing film 10 b is formed on the individual electrode 3 side, but the reverse is also possible. Furthermore, the insulation reinforcing film 10b may not be a single layer, and may be formed on both sides of the ferroelectric film 10a. Further, it may be a repeating structure in which the ferroelectric film 10a and the insulating reinforcement film 10b are laminated.

  If a PLT film is formed in advance and a ferroelectric film 10a such as a PZT film is formed thereon, the crystallinity of the ferroelectric film 10a is improved.

  Here, the insulating enhancement film 10b is a low crystalline film such as a polycrystalline film of a pyrochlore type oxide film, a polycrystalline film of a perovskite type oxide, or an amorphous film having no crystallinity. The insulating enhancement film 10b may be formed of a pyrochlore oxide polycrystalline film and a perovskite oxide polycrystalline film.

  Such a low crystalline film is produced, for example, under any of the following conditions or in combination.

  That is, the first condition is that the deposition temperature is lower than that at the time of manufacturing the ferroelectric film (500 to 600 ° C.). Thereby, an amorphous film is produced at room temperature, for example, a pyrochlore film at 350 to 450 ° C. Note that the first condition is advantageous in that a desired thin film can be easily manufactured because a separate sputtering apparatus is not required and only the film forming conditions are changed.

  The second condition is that the pressure during sputtering is higher than that during production of the ferroelectric film (0.1 to 0.3 Pa), for example, 2 to 3 Pa.

The third condition is that the oxygen partial pressure (O ₂ / Ar flow rate ratio) is increased from that at the time of manufacturing the ferroelectric film (2 to 10%), for example, 30 to 50%.

  However, the film formation is not limited to the sputtering method, and other film formation techniques such as an MO-CVD method using an organic metal or a sol-gel method can be applied.

  As described above, the ferroelectric element according to the present embodiment includes the ferroelectric functional film 10 including the ferroelectric film 10a and the insulating enhancement film 10b including at least one element of the constituent elements of the ferroelectric film 10a. Is formed between the electrode 3 and the diaphragm (common electrode) 11, which causes a decrease in insulating properties of the ferroelectric film 10 a such as gaps and pinholes formed at the interface between the ferroelectric film 10 a and abnormally grown grains. Thus, the defect is completely covered by the insulating reinforcing film 10b, and the insulating property of the ferroelectric film 10a is improved.

  Further, as described above, since the insulating reinforcing film 10b is a film containing at least one element of the constituent elements of the ferroelectric film 10a, the adhesion with the ferroelectric film 10a is improved and strong. The reliability of the dielectric film 10a is improved.

  Furthermore, since the insulating enhancement film 10b is a film containing at least one element of the constituent elements of the ferroelectric film 10a, the dielectric constant of the insulation enhancement film 10b is close to the dielectric constant of the ferroelectric film 10a. This makes it possible to reduce the drive voltage.

  Here, at the time of film formation, if the Pb content of the insulating enhancement film 10b is made larger than the Pb content of the ferroelectric film 10a, the Pb concentration on the surface of the ferroelectric film 10a increases and the crystallinity decreases. Thus, the abnormal growth of crystal grains inside the ferroelectric film 10a can be stopped, and further, since the defect portion is covered, the insulating property of the insulating reinforcing film 10b is further strengthened.

  Further, at the time of film formation, if the oxygen content of the insulation enhancement film 10b is made larger than the oxygen content of the ferroelectric film 10a, the insulation of the insulation enhancement film 10b can be enhanced.

  Furthermore, if the crystallinity of the insulating enhancement film 10b is made lower than the crystallinity of the ferroelectric film 10a, the insulation of the insulation enhancement film 10b can be similarly enhanced.

  Here, the crystallinity is measured by an X-ray diffraction method or an electron beam diffraction method. For example, when the ferroelectric film is an epitaxial single crystal film, the electron diffraction pattern shows a spot pattern, but when the low crystalline film is polycrystalline, it becomes a ring pattern. Further, in the case of an amorphous film, the ring shape becomes unclear and a halo pattern is formed. In the case of the X-ray diffraction method, the crystallinity is determined by the half width of a specific diffraction peak obtained from the ferroelectric film. A case where perovskite PZT is used for the ferroelectric film will be described. For example, the half width of the (001) diffraction peak diffracted from the PZT film represents the crystallinity of the PZT film. When a low crystalline film is formed as an insulation enhancement film on this PZT film, the diffraction line from the PZT film is scattered from the low crystal film formation, and the half width of the PZT (001) diffraction peak increases. When the half-width increase rate when the half-width of the PZT (001) diffraction peak increases from a0 to a is defined as p = (a−a0) / a0, 1 <p ≦ 2.5 is desirable. Furthermore, 1.2 <p ≦ 2.5 is desirable, and 1.5 <p ≦ 2.5 is further desirable. When p> 2.5, the characteristics of the ferroelectric film are remarkably deteriorated and the driving voltage is increased, which is not desirable. In order to suppress the increase in driving voltage within 30%, it is necessary that 1 <p ≦ 2.5. 1.2 <p ≦ 2.5 is necessary to improve the withstand voltage by 20% or more, and 1.5 <p ≦ 2.5 is necessary to further improve it by 50% or more.

Here, as an embodiment, in FIG. 5, an MgO substrate is used for the vertical wall 13, Pt is used for the diaphragm 11, and PZT {Pb (Zr _0.53 Ti _0.47 ) O ₃ is used for the ferroelectric film 10 a. }, Pt was used for the individual electrode 3 and various films were used for the insulation reinforcing film 10b to evaluate the piezoelectric characteristics and insulating characteristics of the films.

  First, a 0.2 μm Pt film and a 2.7 μm PZT film were successively formed on a (100) oriented MgO single crystal substrate. An RF magnetron sputtering apparatus was used as the film forming apparatus. The Pt film was formed at an Ar gas, 0.3 Pa, and a substrate temperature of 650 ° C., and the PZT film was formed at an Ar mixed gas of 10% oxygen partial pressure, 0.3 Pa, at a substrate temperature of 620 ° C. When the crystal structure of the film was analyzed using a powder X-ray diffractometer, both the Pt film and the PZT film were epitaxial films aligned in the (001) direction of the MgO single crystal substrate.

  Next, using the same PZT target, an insulation reinforcing film of 0.3 μm was formed by an RF magnetron sputtering apparatus.

  Sample A was deposited at a substrate temperature of 400 ° C. Other sputtering conditions were the same as those for the PZT film.

  Sample B was deposited at a sputtering pressure of 2 Pa. Other sputtering conditions were the same as those for the PZT film.

  Sample C was formed with an oxygen partial pressure of 50%. Other sputtering conditions were the same as those for the PZT film.

In Comparative Example D, as a comparative example, a SiO ₂ film was formed by sputtering.

  In Comparative Example E, PZT of 3 μm was formed as a comparative example, and no insulation reinforcing film was formed.

  Analyzing the crystal structure of the samples A, B, and C using a powder X-ray diffractometer, the structure of the insulation enhancement film is amorphous, pyrochlore polycrystal, perovskite polycrystal, or a mixture of these crystal phases I understood. Further, the compositions of the ferroelectric film and the insulation reinforcing film were measured by EPMA analysis, and the results shown in Table 1 were obtained. The insulating reinforcing film has a higher Pb content (Pb / (Zr + Ti) atomic ratio) or oxygen content (O / (Zr + Ti) atomic ratio) than the ferroelectric film.

A Pt film was formed on the above sample by sputtering at room temperature to form an upper electrode. The relative values of the breakdown voltage of each sample and the voltage (drive voltage) applied to the upper and lower electrodes to obtain the same piezoelectric displacement are summarized in Table 2. The dielectric breakdown voltage was defined as a voltage at which the leakage current density of the device was 1 μA / cm ² or more. For the piezoelectric displacement, a plate-shaped cantilever having a length of 15 mm and a width of 2 mm shown in FIG. 6 was prepared, and the displacement at the other end when a voltage was applied with one end fixed was measured with a laser Doppler displacement meter.

  As described above, by using the present invention, high insulation can be obtained and the driving voltage can be reduced.

  In this embodiment, a ferroelectric film epitaxially grown on a (100) -oriented MgO single crystal substrate is used. For example, a Pt polycrystalline film or a ferroelectric polycrystalline film is formed on a Si substrate or a quartz substrate. However, the effect of the present invention is not impaired.

  Next, the production of the actuator of the ink jet head will be described with reference to FIG. FIG. 7A shows the configuration of Sample A, 71 is an MgO single crystal substrate, 72 is a Pt film that is a diaphragm and a common electrode, 73 is a PZT epitaxial film that is a ferroelectric film, and 74 is an insulation enhancement film. A low crystal film 75 is a Pt film which is an individual electrode. Next, a desired portion of the MgO substrate is removed by etching to form the structure shown in FIG. For the etching of the MgO substrate, an aqueous phosphoric acid solution heated to 80 ° C. was used. What is necessary is just to apply | coat a resist to the part which wants to leave MgO, and to stop the etching by phosphoric acid. Since the Pt film is not dissolved by phosphoric acid, the MgO etching does not proceed any further when it reaches the Pt film. Further, a part of MgO may be left as a diaphragm. Further, a resist or polyimide is formed as an ink blocking layer 76 on the surface of the MgO substrate. With such a construction method, an actuator corresponding to the actuator portion B of FIG. 5 can be manufactured, and further, the ink jet head shown in FIG. 4 can be manufactured.

  In the present embodiment described above, the case where the ferroelectric element of the present invention is applied to an actuator used for ink ejection of an ink jet recording apparatus has been described. However, a temperature sensor using the pyroelectric property, The present invention can be applied to various other uses such as a light modulation device utilizing an optical effect, an optical actuator utilizing a photoelastic effect, and a SAW device.

  In the present embodiment, for convenience of explanation, the individual electrode 3 is the second electrode and the common electrode 11 is the first electrode. However, the individual electrode 3 is the first electrode and the common electrode (the diaphragm 11). ) May be used as the second electrode.

  In addition, according to the actuator using the ferroelectric element described above, it is possible to perform a stable displacement operation, and according to the ink jet head using such an actuator, it is possible to perform stable ink discharge. It becomes possible. According to the ink jet recording apparatus provided with such an ink jet head, it is possible to perform high quality printing by stable ink ejection.

  As described above, the present invention can be suitably applied to an ink jet head and an ink jet recording apparatus equipped with the ink jet head.

1 is a perspective view showing an overall schematic configuration of an ink jet recording apparatus using a ferroelectric element according to an embodiment of the present invention. Sectional drawing which shows the whole structure of the inkjet head in the inkjet recording device of FIG. The perspective view which shows the principal part of FIG. Sectional drawing which shows the structure of the actuator part of the inkjet head of FIG. Sectional drawing which shows the ferroelectric element which is one embodiment of this invention Explanatory drawing showing the configuration of a cantilever that measures piezoelectric displacement Sectional view showing the manufacturing method of the actuator

Explanation of symbols

3 Individual electrode (second electrode)
DESCRIPTION OF SYMBOLS 10 Ferroelectric functional film 10a Ferroelectric film 10b Insulation reinforcement film 11 Diaphragm (also serves as common electrode (first electrode))
40 Inkjet recording device 41 Inkjet head

Claims (13)

A first electrode;
A ferroelectric functional film formed on the first electrode;
A second electrode formed on the ferroelectric functional film,
The ferroelectric functional film includes a ferroelectric film and at least one element of constituent elements of the ferroelectric film, and is composed of an insulating reinforcing film having lower crystallinity than the ferroelectric film,
The full width at half maximum of the diffraction peak by X-ray analysis of the ferroelectric film is a0,
The full width at half maximum of the diffraction peak by the X-ray analysis method of the ferroelectric functional film is a,
When the increase rate of the half width is p = (a−a0) / a0,
1. A ferroelectric element characterized by satisfying 1 <p ≦ 2.5. 2. The ferroelectric element according to claim 1, wherein a diffraction peak of the ferroelectric film by an X-ray analysis method is based on a (001) orientation plane. The diffraction peak of the first electrode or the second electrode by an X-ray analysis method is based on the same orientation plane as the diffraction peak of the ferroelectric film by an X-ray analysis method. Item 2. The ferroelectric element according to Item 1. 2. The ferroelectric element according to claim 1, wherein a diffraction peak of the first electrode or the second electrode by an X-ray analysis method is based on a (001) orientation plane. 2. The ferroelectric element according to claim 1, wherein the ferroelectric film is a perovskite oxide containing at least one element of Pb, La, Zr, and Ti. 6. The ferroelectric element according to claim 5, wherein the Pb content of the insulation enhancement film is greater than the Pb content of the ferroelectric film. 7. The ferroelectric element according to claim 5, wherein an oxygen content of the insulating reinforcing film is greater than an oxygen content of the ferroelectric film. 2. The ferroelectric element according to claim 1, wherein the insulation reinforcing film is a polycrystalline film or an amorphous film containing at least one of a pyrochlore oxide and a perovskite oxide. An actuator comprising the ferroelectric element according to claim 1. An actuator according to claim 9;
An ink-jet head comprising: a plurality of pressure chambers in which ink liquid is stored and the displacement of the actuator acts. An ink jet recording apparatus comprising the ink jet head according to claim 10. Forming a first electrode;
Forming a ferroelectric functional film on the first electrode;
Forming a second electrode on the ferroelectric functional film;
A method for manufacturing a ferroelectric element comprising:
The step of forming the ferroelectric functional film includes a step of forming a ferroelectric film and an insulation enhancement film,
The insulation enhancement film is an amorphous film containing at least one element of the constituent elements of the ferroelectric film,
The amorphous film is formed by changing the film forming temperature at least by using the same film forming apparatus as that for forming the ferroelectric film. Production method. 13. The method for manufacturing a ferroelectric element according to claim 12, wherein a film forming temperature for forming the amorphous film is set to room temperature.

Images