JP2009081262A - Method for manufacturing actuator device, and method for manufacturing liquid spray head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an actuator device capable of preventing decrease in amount of displacement of a piezoelectric element even though the piezoelectric element is repeatedly driven, and to provide a method for manufacturing a liquid spraying head. <P>SOLUTION: The actuator device has: the piezoelectric element including a lower electrode film, a piezoelectric-substance layer, and an upper electrode film provided on the substrate; and a tension film formed on the piezoelectric-substance layer and including the upper electrode for giving a tension stress to the piezoelectric-substance layer. The actuator causes the piezoelectric element to flexibly deform by varying the voltage applied between the lower electrode film and the upper electrode film in the range from the minimum voltage higher than the anti-electric field to the maximum voltage. The method for manufacturing the actuator device includes the steps of: preliminarily estimating a shift amount of a voltage-displacement-characteristic-curve of the piezoelectric element caused by the repeated drive of the piezoelectric element; and forming the tension film so that the stress is determined by the shift amount. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a manufacturing method of an actuator device including a piezoelectric element including a lower electrode film, a piezoelectric layer, and an upper electrode film provided on a substrate in a displaceable manner, and a manufacturing method of a liquid ejecting head including the actuator device.

  The piezoelectric element used in the actuator device includes a piezoelectric material exhibiting an electromechanical conversion function, for example, a piezoelectric layer made of a crystallized dielectric material sandwiched between two electrodes, a lower electrode and an upper electrode There is. An actuator device having such a piezoelectric element is generally called a flexural vibration mode actuator device, and is used by being mounted on, for example, a liquid ejecting head. As a typical example of a liquid ejecting head, for example, a part of a pressure generation chamber communicating with a nozzle opening for ejecting ink droplets is configured by a vibration plate, and the vibration plate is deformed by a piezoelectric element so that ink in the pressure generation chamber is discharged. There are ink jet recording heads that pressurize and eject ink droplets from nozzle openings. In such an actuator device (piezoelectric element) of an ink jet recording head, for example, a uniform piezoelectric material layer is formed over the entire surface of the diaphragm by a film forming technique, and this piezoelectric material layer is formed by a lithography method into a pressure generating chamber. Are formed so as to be independent for each pressure generating chamber (see, for example, Patent Document 1).

JP 2003-127366 A

  In such an actuator device, there is a problem that when the piezoelectric element is repeatedly driven, the amount of displacement gradually decreases.

  One cause of the decrease in the amount of displacement of the piezoelectric element is that the displacement characteristics with respect to the voltage applied to the piezoelectric element change with so-called imprinting. That is, the voltage vs. displacement characteristic curve showing the relationship between the voltage and the displacement characteristic is slightly shifted to the negative voltage side. Note that “imprint” is a phenomenon in which polarization inversion becomes difficult with repeated driving of a piezoelectric element.

  When the voltage versus displacement characteristic curve shifts in this way, the amount of change in the displacement characteristic at the highest voltage of the drive signal for driving the piezoelectric element becomes smaller than the amount of change in the displacement characteristic at the lowest voltage. As a result, the amount of displacement of the piezoelectric element is reduced.

  Such a problem exists not only in an actuator device mounted on a liquid ejecting head but also in an actuator device mounted on another device.

  The present invention has been made in view of such circumstances, and provides a method of manufacturing an actuator device and a method of manufacturing a liquid ejecting head that can prevent a decrease in displacement of the piezoelectric element even when the piezoelectric element is repeatedly driven. The purpose is to provide.

The present invention for solving the above-described problems has a piezoelectric element comprising a lower electrode film, a piezoelectric layer, and an upper electrode film provided on a substrate, and is formed on the piezoelectric layer and applies tensile stress to the piezoelectric layer. The piezoelectric element is bent by changing a voltage applied between the lower electrode film and the upper electrode film in a range from the lowest voltage higher than the coercive electric field to the highest voltage. A method of manufacturing an actuator device to be deformed, wherein a shift amount of a voltage-displacement characteristic curve of the piezoelectric element associated with repeated driving of the piezoelectric element is estimated in advance so that a stress determined according to the shift amount is obtained. The tensile film is formed on the actuator device.
In the present invention, a predetermined tensile stress is applied to the piezoelectric layer by the tensile film, and the voltage versus displacement characteristic curve is substantially shifted to the positive voltage side. Thereby, even when the voltage-displacement characteristic curve is shifted to the negative voltage side by so-called imprinting, a decrease in the displacement amount of the piezoelectric element is prevented.

  Here, it is preferable to adjust the stress of the tensile film according to the thickness of the upper electrode film. Thereby, the stress of the tensile film can be adjusted relatively easily.

  The actuator device further includes a protective film provided on the upper electrode film so as to cover the piezoelectric layer of each piezoelectric element, and the tensile film is composed of the upper electrode film and the protective film. It is preferable that the stress of the tensile film is adjusted by the thicknesses of the upper electrode film and the protective film. Thereby, the stress of the tensile film can be adjusted relatively easily.

  Further, the stress of the tensile film is adjusted by forming an opening in a region of the protective film facing the upper electrode film and removing a part of the opening in the thickness direction of the upper electrode film. It is preferable to do. Thereby, the stress of the tensile film can be adjusted well without significantly changing the electrical characteristics of the upper electrode film.

  Further, the change amount of the displacement characteristic of the piezoelectric element at the highest voltage due to the shift of the voltage-displacement characteristic curve is equal to the change amount of the displacement characteristic at the lowest voltage of the voltage-displacement characteristic curve of the piezoelectric element. It is preferable to adjust the stress of the tensile film. Thereby, the fall of the displacement amount by the repeated drive of a piezoelectric element can be prevented more reliably.

  Further, according to the present invention, the actuator device is formed on one surface of a flow path forming substrate provided with a pressure generating chamber communicating with a nozzle opening for ejecting droplets by such a manufacturing method. It is in the manufacturing method of an ejection head. According to the present invention, it is possible to realize a liquid ejecting head that can eject liquid droplets over a long period of time.

Hereinafter, the present invention will be described in detail based on embodiments.
FIG. 1 is an exploded perspective view showing a schematic configuration of an ink jet recording head which is an example of a liquid ejecting head, and FIG. 2 is a plan view of FIG. FIG. 3 is a cross-sectional view in the width direction of the pressure generating chamber showing the main part of the ink jet recording head.

  As shown in the figure, the flow path forming substrate 10 is made of a silicon single crystal substrate having a plane orientation (110) in this embodiment, and an elastic film 50 made of silicon dioxide is previously formed on one surface thereof by thermal oxidation. Yes. In the flow path forming substrate 10, pressure generation chambers 12 partitioned by a plurality of partition walls 11 are arranged in parallel in the width direction (short direction). In addition, an ink supply path 14 and a communication path 15 are partitioned by a partition wall 11 on one end side in the longitudinal direction of the pressure generating chamber 12 of the flow path forming substrate 10. In addition, a communication portion 13 constituting a part of the reservoir 100 serving as an ink chamber (liquid chamber) common to the pressure generation chambers 12 is formed at one end of the communication passage 15.

  On the opening surface side of the flow path forming substrate 10, a nozzle plate 20 having a nozzle opening 21 communicating with each pressure generating chamber 12 is fixed by an adhesive, a heat welding film, or the like. The nozzle plate 20 is formed of, for example, glass ceramics, a silicon single crystal substrate, stainless steel, or the like.

  On the other hand, the elastic film 50 is formed on the side opposite to the opening surface of the flow path forming substrate 10 as described above, and the insulator film 55 is formed on the elastic film 50. Further, a piezoelectric element 300 composed of a lower electrode film 60, a piezoelectric layer 70, and an upper electrode film 80 is formed on the insulator film 55. In the present embodiment, the lower electrode film 60 is used as a common electrode of the piezoelectric element 300 and the upper electrode film 80 is used as an individual electrode of the piezoelectric element 300. However, there is no problem even if this is reversed for convenience of a drive circuit and wiring. In addition, here, the piezoelectric element 300 and the diaphragm that is displaced by driving the piezoelectric element 300 are collectively referred to as an actuator device. In this embodiment, the elastic film 50, the insulator film 55, and the lower electrode film 60 function as a vibration plate. However, the present invention is not limited to this. For example, the elastic film 50 and the insulator film 55 are provided. Instead, only the lower electrode film 60 may act as a diaphragm. Further, the piezoelectric element 300 itself may substantially serve as a diaphragm.

  The piezoelectric element 300 is covered with a protective film 200 made of an insulating material having moisture resistance. Thereby, destruction of the piezoelectric element 300 caused by moisture in the atmosphere can be prevented. Here, the film formed on the piezoelectric layer 70, in this embodiment, the upper electrode film 80 and the protective film 200 function as a tensile film that applies a tensile stress to the piezoelectric layer 70.

  As described above, as shown in FIG. 3, the piezoelectric layer 70 and the diaphragm are in an initial state by applying tensile stress to the piezoelectric layer 70 by the upper electrode film 80 and the protective film 200 that function as a tensile film. The side opposite to the pressure generating chamber 12 is deformed so as to be slightly convex.

  In the present embodiment, the protective film 200 covers the side surface of the piezoelectric layer 70, the side surface of the upper electrode film 80, and the peripheral edge of the upper surface, and is continuously provided across the plurality of piezoelectric elements 300. That is, the protective film 200 on the upper electrode film 80 is provided with an opening 201 at a substantially central portion of the upper electrode film 80, and the main part of the upper electrode film 80 is exposed. Further, the thickness of the upper electrode film 80 in the region facing the opening 201 of the protective film 200 is thinner than the thickness of other regions. That is, a thin portion 81 having a smaller film thickness than other regions is formed in a region facing the opening 201 of the upper electrode film 80. As will be described in detail later, the tensile stress applied to the piezoelectric layer 70 is adjusted by changing the size of the opening 201 and the thickness of the upper electrode film 80 in the region facing the opening 201.

  On the protective film 200, for example, a lead electrode 90 made of gold (Au) or the like is provided. The lead electrode 90 has one end connected to the upper electrode film 80 through a connection hole 202 provided in the protective film 200 and the other end extended to the ink supply path 14 side of the flow path forming substrate 10. The extended tip is connected to a drive circuit 120 (described later) via a connection wiring 121.

  On the flow path forming substrate 10 on which such a piezoelectric element 300 is formed, that is, on the lower electrode film 60, the elastic film 50, and the lead electrode 90, a protection having a reservoir portion 31 constituting at least a part of the reservoir 100. The substrate 30 is bonded via an adhesive 35. A piezoelectric element holding portion 32 having a space that does not hinder the movement of the piezoelectric element 300 is provided in a region of the protective substrate 30 that faces the piezoelectric element 300. The protective substrate 30 is provided with a through hole 33 that penetrates the protective substrate 30 in the thickness direction. The vicinity of the end of the lead electrode 90 drawn from each piezoelectric element 300 is exposed in the through hole 33.

  A driving circuit 120 for driving each piezoelectric element 300 is fixed on the protective substrate 30. For example, a circuit board or a semiconductor integrated circuit (IC) can be used as the drive circuit 120. The drive circuit 120 and the lead electrode 90 are electrically connected by a connection wiring 121 made of a conductive wire such as a bonding wire.

  A compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the protective substrate 30. Here, the sealing film 41 is made of a material having low rigidity and flexibility, and one surface of the reservoir portion 31 is sealed by the sealing film 41. The fixing plate 42 is made of a hard material such as metal. Since the region of the fixing plate 42 facing the reservoir 100 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir 100 is sealed only with a flexible sealing film 41. Has been.

  In the ink jet recording head manufactured by the manufacturing method of this embodiment, ink is taken in from an ink introduction port connected to an external ink supply means (not shown), and the interior from the reservoir 100 to the nozzle opening 21 is filled with ink. After that, according to the recording signal from the drive circuit 120, a voltage is applied between the lower electrode film 60 and the upper electrode film 80 corresponding to each pressure generating chamber 12 to bend the piezoelectric element (actuator device). By deforming, the pressure in each pressure generating chamber 12 is increased and ink droplets are ejected from the nozzle openings 21.

  By the way, as shown in FIG. 4, the drive signal 400 applied to the piezoelectric element 300 constituting such an actuator device is expanded from the state in which the intermediate voltage VM is maintained to the lowest voltage VL to expand the pressure generation chamber 12. A first expansion step 401 for maintaining the minimum voltage VL for a certain period of time, and an ink droplet is ejected by increasing the minimum voltage VL to the maximum voltage VH to contract the pressure generating chamber 12. A contraction process 403, a second hold process 404 that maintains the maximum voltage VH for a certain period of time, and a second expansion process 405 that lowers the maximum voltage VH from the intermediate voltage VM.

  The piezoelectric element 300 is formed of a thin film and is subjected to polarization treatment. As shown in FIG. 5, when the voltage applied to the piezoelectric element 300 is changed, the vicinity of the voltage Vc that generates the coercive electric field Ec is used as a boundary. The displacement direction is reversed. The lowest voltage VL applied by the drive signal 400 is set to a voltage higher than the voltage Vc that generates the coercive electric field Ec. That is, the piezoelectric element 300 is driven by changing the voltage applied to the piezoelectric element 300 in a range higher than the voltage Vc.

  Here, the amount of displacement of the piezoelectric element 300 increases gradually when it exceeds the voltage Vc that generates the coercive electric field Ec, then increases linearly, and gradually increases when the voltage exceeds a certain level. It has the characteristic that it falls. That is, as shown in FIG. 5, the voltage-displacement characteristic curve showing the relationship with the displacement characteristic with respect to the voltage gradually increases in inclination angle when the voltage Vc is exceeded, and thereafter changes linearly, and the applied voltage changes to some extent. As the height increases, the inclination angle gradually decreases. The maximum voltage VH of the drive signal 400 is set to a relatively high voltage in order to ensure the amount of displacement of the piezoelectric element 300.

  Further, as shown by the dotted line in FIG. 5, when the voltage versus displacement characteristic curve is shifted to the negative voltage side by so-called imprinting, the displacement of the piezoelectric element 300 at the lowest voltage VL and the highest voltage VH applied by the drive signal. Each amount will increase. However, the amount of increase is different. Specifically, the maximum voltage VH of the drive signal 400 is set to a relatively high voltage in order to ensure the amount of displacement of the piezoelectric element 300. That is, the maximum voltage VH is set in a portion where the amount of change in displacement of the piezoelectric element 300 is reduced in the voltage versus displacement characteristic curve. Therefore, the displacement change amount ΔDH at the highest voltage VH is smaller than the displacement change amount ΔDL at the lowest voltage VL.

  Therefore, when the voltage vs. displacement characteristic curve shifts to the minus voltage side in this way, the deflection displacement amount D1 of the piezoelectric element 300 when the voltage is changed from the lowest voltage VL to the highest voltage VH is the voltage vs. displacement characteristic in the initial state. It becomes smaller than the displacement amount D2 in the curve.

  Therefore, in the present invention, the shift amount of the potential displacement characteristic curve due to imprinting is estimated in advance, and the tensile film is formed so as to have a stress determined according to the estimated shift amount. That is, the strength of the tensile stress applied to the piezoelectric layer 70 is adjusted based on the shift amount of the potential displacement characteristic curve. As will be described in detail later, it is possible to prevent the displacement of the piezoelectric element 300 from decreasing even if the potential displacement characteristic curve is shifted to the negative voltage side.

  Hereinafter, a method for manufacturing an ink jet recording head, in particular, a method for manufacturing an actuator device will be described with reference to FIGS. 6 to 9 are cross-sectional views in the longitudinal direction of the pressure generating chamber of the ink jet recording head.

First, as shown in FIG. 6A, a silicon dioxide film 51 made of silicon dioxide (SiO ₂ ) constituting the elastic film 50 is formed on the surface of a flow path forming substrate wafer 110 which is a silicon wafer. Next, as shown in FIG. 6B, an insulator film 55 made of zirconium oxide is formed on the elastic film 50 (silicon dioxide film 51). Specifically, after forming a zirconium (Zr) layer on the elastic film 50 (silicon dioxide film 51) by, for example, sputtering, the zirconium layer is thermally oxidized in a diffusion furnace at 500 to 1200 ° C., for example. Thus, the insulator film 55 made of zirconium oxide (ZrO ₂ ) is formed.

  Next, as shown in FIG. 6C, for example, after the lower electrode film 60 is formed by laminating platinum and iridium on the insulator film 55, the lower electrode film 60 is patterned into a predetermined shape. The lower electrode film 60 is not limited to a laminate of platinum (Pt) and iridium (Ir), and an alloy of these may be used. Further, the lower electrode film 60 may be used as a single layer of any one of platinum (Pt) and iridium (Ir), and a metal or a metal oxide other than these materials may be used. Also good.

  Next, as shown in FIG. 6D, a piezoelectric layer 70 made of, for example, lead zirconate titanate (PZT) or the like is formed. As a material of the piezoelectric layer 70 constituting the piezoelectric element 300, for example, a ferroelectric piezoelectric material such as lead zirconate titanate (PZT) or a metal such as niobium, nickel, magnesium, bismuth or yttrium is used. An added relaxor ferroelectric or the like is used. In the present embodiment, the piezoelectric layer 70 is formed by applying a so-called sol in which a metal organic material is dissolved and dispersed in a solvent, drying it to gel, and baking it at a high temperature to form a piezoelectric layer made of a metal oxide. The piezoelectric layer 70 was formed using a so-called sol-gel method for obtaining 70. The method for forming the piezoelectric layer 70 is not particularly limited, and for example, a MOD method or a sputtering method may be used.

  Next, as shown in FIG. 7A, for example, an upper electrode film 80 made of iridium is formed on the entire surface of the flow path forming substrate 10. At this time, the shift amount of the voltage versus displacement characteristic curve described above is estimated in advance, and the upper electrode film 80 is formed so as to have a predetermined stress corresponding to the shift amount. That is, the stress of the upper electrode film 80 is adjusted so that the tensile film including the upper electrode film 80 applies a predetermined tensile stress to the piezoelectric layer 70. Note that the shift amount of the voltage versus displacement characteristic curve can be easily estimated from the characteristics of the piezoelectric layer 70. For example, the capacitance of the piezoelectric layer 70 is measured, and the shift amount can be easily estimated from the result. Of course, it is also possible to make a test head and actually drive the piezoelectric element 300 to measure the shift amount.

  Since the stress of the upper electrode film 80 is determined by the Young's modulus and residual strain of the upper electrode film 80, it can be adjusted by the material, shape, or film forming conditions of the upper electrode film 80. In this embodiment, since the upper electrode film 80 is formed by the sputtering method, for example, the upper electrode film 80 having a desired stress can be formed by appropriately adjusting the film formation conditions such as the sputtering temperature. .

  Further, the stress of the upper electrode film 80 may be completely adjusted at the time of film formation, but it is not always necessary to adjust it completely at the time of film formation. In the present embodiment, the stress of the upper electrode film 80 is adjusted by the thickness (shape) of the upper electrode film 80 as will be described later, while the stress of the upper electrode film 80 is adjusted by the film forming conditions.

  Next, as shown in FIG. 7B, the upper electrode film 80 and the piezoelectric layer 70 are patterned in a region facing each pressure generating chamber 12 to form the piezoelectric element 300.

Next, as shown in FIG. 7C, a protective film 200 is formed on the entire surface of the flow path forming substrate wafer 110. The protective film 200 functions as a tensile film together with the upper electrode film 80 as described above. Therefore, the material of the protective film 200 needs to be a material having moisture resistance and to be able to apply tensile stress to the piezoelectric layer 70. Specifically, for example, silicon oxide _(SiO x), tantalum oxide _(TaO x), it is preferable to use an inorganic insulating material such as aluminum oxide (AlO _x), in particular, aluminum oxide is an inorganic amorphous material (AlO _x ), For example, it is preferable to use alumina (Al ₂ O ₃ ). In the case where aluminum oxide is used as the material of the protective film 200, moisture permeation in a high humidity environment can be sufficiently prevented even if the protective film 200 has a relatively thin film thickness of about 100 nm. Further, the stress of the protective film 200 can be adjusted according to the shape and film forming conditions, similarly to the upper electrode film 80. Incidentally, the stress of the protective film 200 is smaller than the stress of the upper electrode film 80 which varies depending on the material and the film forming conditions. That is, the protective film 200 also functions as a tensile film, but the upper electrode film 80 mainly functions as a tensile film.

  Next, as shown in FIG. 7D, the opening 201 and the connection hole 202 are formed by etching the region corresponding to each piezoelectric element 300 of the protective film 200. The protective film 200 can be etched by dry etching such as ion milling or reactive dry etching (RIE). At this time, the thin portion 81 is formed by removing a part of the upper electrode film 80 in the thickness direction as necessary. That is, by reducing the thickness of a part of the upper electrode film 80, the magnitude of the tensile stress applied to the piezoelectric layer 70 by the tensile film is adjusted. Thus, a tensile stress having a desired magnitude is applied to the piezoelectric layer 70 by the upper electrode film 80 and the protective film 200 which are tensile films.

  Next, the lead electrode 90 is formed. Specifically, as shown in FIG. 8A, after forming a metal film 91 made of, for example, gold (Au) over the entire surface of the flow path forming substrate wafer 110, it is made of, for example, a resist or the like. The metal film 91 is patterned for each piezoelectric element 300 through a mask pattern (not shown). Next, as shown in FIG. 8 (b), a protective substrate wafer 130 that is a silicon wafer and serves as a plurality of protective substrates 30 is placed on the side of the piezoelectric element 300 of the flow path forming substrate wafer 110 through an adhesive 35. Join. Next, as shown in FIG. 8C, the flow path forming substrate wafer 110 is processed to have a predetermined thickness.

  Next, as shown in FIG. 9A, an insulating film 52 is newly formed on the flow path forming substrate wafer 110 and patterned into a predetermined shape. Then, as shown in FIG. 9B, the pressure generating chamber 12 corresponding to the piezoelectric element 300 is obtained by anisotropically etching (wet etching) the flow path forming substrate wafer 110 using the insulating film 52 as a mask. A communication part 13, an ink supply path 14, a communication path 15 and the like are formed.

  At this time, since the upper electrode film 80 and the protective film 200 function as a tensile film and a predetermined tensile stress is applied to the piezoelectric layer 70, the piezoelectric element 300 and the vibration are generated when the pressure generation chamber 12 is formed. The plate is slightly bent so that the side opposite to the pressure generating chamber 12 is convex (see FIG. 3). Thus, by making the piezoelectric element 300 in the initial state bend in a convex shape on the side opposite to the pressure generating chamber 12, the voltage versus displacement characteristic curve is as shown in FIG. The voltage vs. displacement characteristic curve (dotted line in the figure) of the piezoelectric element that is not bent is substantially shifted to the positive voltage side. That is, both the minimum voltage VL and the maximum voltage VH of the drive signal are set in a portion where the voltage vs. displacement characteristic curve changes almost linearly.

  As a result, as shown by the dotted line in FIG. 10B, even if the voltage versus displacement characteristic curve is slightly shifted to the negative voltage side, the displacement change ΔDL at the lowest voltage VL and the displacement change at the highest voltage VH. ΔDH has almost the same size. That is, the voltage versus displacement characteristic curve between the lowest voltage VL and the highest voltage VH is substantially linear before and after the shift. Accordingly, the displacement amounts D1 and D2 of the piezoelectric element 300 by changing from the lowest voltage VL to the highest voltage VH are substantially the same. That is, even if the voltage versus displacement characteristic curve is shifted to the negative voltage side by so-called imprinting, the displacement amount of the piezoelectric element 300 does not decrease. Therefore, even when used for a long time, the ejection characteristics do not deteriorate, and ink droplets are always ejected from the nozzle openings 21 with good ejection characteristics.

  Further, the shift amount of the piezoelectric versus displacement characteristic curve, that is, the piezoelectric characteristics of the piezoelectric layer 70 may vary somewhat between the heads. For this reason, when the actuator device (piezoelectric element 300) of each head is driven by the same drive signal, there is a possibility that variations in ink ejection characteristics occur. However, as described above, a predetermined tensile stress is applied to the piezoelectric layer 70 by the tensile film in accordance with the shift amount, so that even if the actuator device of each head is driven with the same drive signal, the ink Drop ejection characteristics are made uniform.

  In the present embodiment, the upper electrode film 80 and the protective film 200 function as a tensile film, and the stress of the upper electrode film 80 and the protective film 200 is controlled by the thickness (shape) or the like. . Thereby, a desired tensile stress can be applied to the piezoelectric layer 70 by the tensile film.

  Furthermore, in this embodiment, the stress of the upper electrode film 80 is adjusted by reducing the thickness of a part of the upper electrode film 80 through the opening 201 of the protective film 200. Thereby, the stress of the upper electrode film 80 can be adjusted with certainty, and the resistance value of the upper electrode film 80 can be prevented from greatly increasing. That is, a desired tensile stress can be applied to the piezoelectric layer 70 without adversely affecting the driving of the piezoelectric element 300.

  After the pressure generating chamber 12 and the like are formed on the flow path forming substrate wafer 110, unnecessary portions of the outer peripheral edge portions of the flow path forming substrate wafer 110 and the protective substrate wafer 130 are cut by, for example, dicing. To remove. The nozzle plate 20 having the nozzle openings 21 formed on the surface of the flow path forming substrate wafer 110 opposite to the protective substrate wafer 130 is bonded, and the compliance substrate 40 is bonded to the protective substrate wafer 130. By dividing the flow path forming substrate wafer 110 and the like into the flow path forming substrate 10 and the like of one chip size as shown in FIG. 1, the ink jet recording head of this embodiment is obtained.

  As mentioned above, although one Embodiment of this invention was described, the basic composition of this invention is not limited to what was mentioned above. For example, in the present embodiment, an example in which the upper electrode film 80 and the protective film 200 function as a tensile film has been described. However, the present invention is not limited to this, and the protective film 200 is not necessarily provided. Good. Even in this case, the upper electrode film 80 functions sufficiently as a tensile film. Of course, a tensile film for applying a tensile stress to the piezoelectric layer 70 may be provided separately from the upper electrode film 80 and the protective film 200.

  In this embodiment, an example of the drive signal has been described. However, the shape of the drive signal is not particularly limited as long as the minimum voltage is a drive signal higher than the voltage that generates the coercive electric field.

  In the above-described embodiment, the ink jet recording head has been described as an example of the liquid ejecting head. However, the present invention is widely applied to all liquid ejecting heads, and the liquid ejecting ejects a liquid other than ink. Of course, it can also be applied to the head. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (field emission displays). Examples thereof include an electrode material ejection head used for electrode formation, a bioorganic matter ejection head used for biochip production, and the like.

  The present invention is not limited to a method for manufacturing an actuator device mounted on a liquid ejecting head typified by an ink jet recording head, and can also be applied to a method for manufacturing an actuator device mounted on another device.

FIG. 2 is an exploded perspective view illustrating a schematic configuration of a recording head. FIG. 2 is a plan view of a recording head and a longitudinal sectional view of a pressure generating chamber. FIG. 3 is a cross-sectional view in the width direction of a pressure generation chamber of a recording head. It is a figure which shows the drive signal applied to a piezoelectric element. It is a graph which shows the voltage versus displacement characteristic of a piezoelectric element. FIG. 6 is a cross-sectional view illustrating a recording head manufacturing method according to an embodiment. FIG. 6 is a cross-sectional view illustrating a recording head manufacturing method according to an embodiment. FIG. 6 is a cross-sectional view illustrating a recording head manufacturing method according to an embodiment. FIG. 6 is a cross-sectional view illustrating a recording head manufacturing method according to an embodiment. It is a graph which shows the voltage-displacement characteristic explaining the change of the displacement amount of a piezoelectric element.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Flow path formation board | substrate, 20 Nozzle plate, 30 Protection board | substrate, 40 Compliance board | substrate, 50 Elastic film, 55 Insulator film | membrane, 60 Lower electrode film | membrane, 70 Piezoelectric body layer, 80 Upper electrode film | membrane, 81 Thin part, 90 Lead electrode, 200 protective film, 201 opening, 202 connection hole, 300 piezoelectric element

Claims (6)

A tensile film having a piezoelectric element including a lower electrode film, a piezoelectric layer, and an upper electrode film provided on a substrate, and including the upper electrode film formed on the piezoelectric layer and applying tensile stress to the piezoelectric layer And a method of manufacturing an actuator device that bends and deforms the piezoelectric element by changing a voltage applied between the lower electrode film and the upper electrode film in a range from a lowest voltage higher than a coercive electric field to a highest voltage. And
A shift amount of a voltage-displacement characteristic curve of the piezoelectric element that accompanies repeated driving of the piezoelectric element is estimated in advance, and the tensile film is formed to have a stress determined according to the shift amount. Method for manufacturing an actuator device.   The method of manufacturing an actuator device according to claim 1, wherein the stress of the tensile film is adjusted by the thickness of the upper electrode film. The actuator device further includes a protective film provided on the upper electrode film so as to cover the piezoelectric layer of each piezoelectric element, and the tensile film is composed of the upper electrode film and the protective film,
2. The method of manufacturing an actuator device according to claim 1, wherein the stress of the tensile film is adjusted by the thicknesses of the upper electrode film and the protective film.   Adjusting the stress of the tensile film by forming an opening in a region of the protective film facing the upper electrode film and removing a part of the upper electrode film in the thickness direction in the opening; The method of manufacturing an actuator device according to claim 3.   The amount of change in the displacement characteristic of the piezoelectric element at the highest voltage due to the shift of the voltage vs. displacement characteristic curve is such that the voltage vs. displacement characteristic curve of the piezoelectric element is equivalent to the amount of change in the displacement characteristic at the lowest voltage. The method for manufacturing an actuator device according to any one of claims 1 to 4, wherein a stress of the tensile film is adjusted.   The actuator device is formed on one surface of a flow path forming substrate provided with a pressure generating chamber communicating with a nozzle opening for ejecting liquid droplets by the manufacturing method according to claim 1. A method of manufacturing a liquid ejecting head.