JP2009272329A - Method for manufacturing actuator device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an actuator device which controls deformation of a substrate, being formed in the initial stage of a manufacturing process and having a significant impact on the subsequent process, such that the impact on the process for forming a piezoelectric element is minimized. <P>SOLUTION: An insulator film 55 consisting of zirconium oxide is formed on an elastic layer 50 (silicon dioxide film 51) by carrying out thermal oxidation of a zirconium layer, and then annealing of the insulator film 55 is carried out at a temperature below the highest temperature when thermal oxidation of the zirconium layer is carrier out. Deformation of a wafer 110 for a channel formation substrate is regulated in the initial process by changing the conditions in annealing such as the temperature, time period, or the like, thus guiding or minimizing deformation of the wafer 110 for a channel formation substrate to a desired range in a process for forming a piezoelectric element. At the same time, deformation of the wafer 110 for a channel formation substrate is guided or minimized to a desired range in a process for etching an ink channel by regulating deformation of the wafer 110 for a channel formation substrate in the initial process. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an actuator device that deforms a vibrating member by displacement of a piezoelectric element.

  An actuator device including a piezoelectric element that is displaced by applying a voltage is used as, for example, a liquid ejecting unit of a liquid ejecting head mounted on a liquid ejecting apparatus that ejects droplets. As a liquid ejecting apparatus, for example, a part of a pressure generation chamber communicating with a nozzle opening is configured by a vibration plate, and the vibration plate is deformed by a piezoelectric element so as to pressurize ink in the pressure generation chamber and eject ink droplets from the nozzle opening. 2. Description of the Related Art An ink jet recording apparatus provided with an ink jet recording head to be ejected is known.

  As an ink jet recording head, for example, a uniform piezoelectric film is formed over the entire surface of the diaphragm by a film forming technique, and the piezoelectric layer is separated into shapes corresponding to pressure generation chambers by a lithography method. 2. Description of the Related Art An actuator device in a flexural vibration mode in which a piezoelectric element is independently formed in a generation chamber is known (see, for example, Patent Document 1).

  In the actuator device, an elastic film is formed on the surface of a flow path forming substrate, and a ferroelectric film sandwiched between upper and lower electrodes is formed as a piezoelectric element. The ferroelectric film is formed, for example, by applying and sintering an organic metal sol, and after the ferroelectric film is formed as a piezoelectric element, a pressure chamber is etched on the other surface of the flow path forming substrate. It is formed.

  In a generally known actuator device, it is important to apply the organometallic sol for generating a ferroelectric film to a flat substrate in order to improve the in-plane distribution of the ferroelectric film. In the process of etching the pressure chamber on the other surface of the flow path forming substrate by anisotropic etching or the like, the flatness of the substrate is important for forming the pressure chamber pattern.

  In the process of laminating and forming an elastic film or a ferroelectric film on a substrate, it is inevitable that the substrate is somewhat deformed (warped) due to internal stress of each generated film. For this reason, the warp formed on the substrate in the initial stage has a great influence on the formation process of the ferroelectric film and the etching process of the pressure chamber. The actual situation is that warpage is not specifically considered.

JP 2007-329285 A

  The present invention has been made in view of the above situation, and controls the deformation of the substrate that is formed in the early stage of the manufacturing process and has a great influence on the subsequent process to a state in which the influence in the piezoelectric element forming process is suppressed to a minimum. It is an object of the present invention to provide a method for manufacturing an actuator device that can be used.

  The manufacturing method of the actuator device of the present invention for achieving the above object has a step of forming a piezoelectric element comprising a lower electrode, a piezoelectric layer and an upper electrode on one surface of a substrate, and the state of formation of the piezoelectric element An annealing treatment setting step for setting the state of the preceding annealing treatment for forming the piezoelectric element based on the annealing treatment is controlled, and the annealing treatment is controlled based on the setting of the annealing treatment setting step.

  In the present invention, by controlling the annealing process based on the setting of the annealing process setting process, the deformation of the substrate in the initial process is adjusted so that the deformation of the substrate in the process of forming the piezoelectric element can be suppressed to a desired range. can do.

  In the manufacturing method of the actuator device, the state of formation of the piezoelectric element is a state of formation of a precursor of the piezoelectric layer. Thereby, the deformation | transformation of the board | substrate by the internal stress of the production | generation film | membrane of a piezoelectric material layer can be suppressed to a desired range.

  In the method for manufacturing an actuator device, the annealing treatment setting step may determine conditions for the annealing treatment and perform the annealing treatment based on the decided conditions. In the method for manufacturing the actuator device, the annealing process condition includes whether or not the annealing process is performed.

  FIG. 1 is an exploded perspective view showing an ink jet recording head having an actuator device manufactured by a manufacturing method according to an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. In FIGS. 4 to 6, steps of the manufacturing method according to the embodiment of the present invention are shown.

The ink jet recording head will be described with reference to FIGS.
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 one surface thereof is made of silicon dioxide previously formed by thermal oxidation. Is formed. A plurality of pressure generating chambers 12 are arranged in parallel in the width direction of the flow path forming substrate 10. Further, a communication portion 13 is formed in a region outside the longitudinal direction of the pressure generation chamber 12 of the flow path forming substrate 10, and the communication portion 13 and each pressure generation chamber 12 are provided for each pressure generation chamber 12. Communication is made via a path 14. The communication part 13 constitutes a part of a reservoir that communicates with a reservoir part of a protective substrate, which will be described later, and serves as a common ink chamber for the pressure generating chambers 12. The ink supply path 14 is formed with a narrower width than the pressure generation chamber 12, and maintains a constant flow path resistance of ink flowing into the pressure generation chamber 12 from the communication portion 13.

  On the opening surface side of the flow path forming substrate 10, a nozzle plate 20 having a nozzle opening 21 communicating with the vicinity of the end portion of each pressure generating chamber 12 on the side opposite to the ink supply path 14 is bonded with adhesive or heat. It is fixed via a film or the like. The nozzle plate 20 is made of, for example, glass ceramics, a silicon single crystal substrate, stainless steel, or the like.

An elastic film 50 made of silicon dioxide (SiO ₂ ) is formed on the side opposite to the opening surface of the flow path forming substrate 10, and an insulator film 55 made of zirconium oxide (ZrO ₂ ) is formed on the elastic film 50. Is formed. A lower electrode film 60, a piezoelectric layer 70, and an upper electrode film 80 are laminated on the insulator film 55 by a process described later to constitute the piezoelectric element 300. The piezoelectric element 300 refers to a portion including the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80.

  In general, one electrode of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each pressure generating chamber 12. A portion that is composed of any one of the patterned electrodes and the piezoelectric layer 70 and in which piezoelectric distortion is generated by applying a voltage to both electrodes is a piezoelectric active portion. In this embodiment, the lower electrode film 60 is a common electrode of the piezoelectric element 300, and the upper electrode film 80 is an individual electrode of the piezoelectric element 300. However, there is no problem even if this is reversed for the convenience of the drive circuit and wiring. In any case, a piezoelectric active part is formed for each pressure generating chamber 12.

  The piezoelectric element 300 and a diaphragm that is displaced by driving the piezoelectric element 300 are combined to form a piezoelectric actuator. A lead electrode 90 made of, for example, gold (Au) or the like is connected to the upper electrode film 80 of each piezoelectric element 300, and a voltage is selectively applied to each piezoelectric element 300 via the lead electrode 90.

  A protective substrate 30 having a piezoelectric element holding portion 31 capable of securing a space that does not hinder its movement in a region facing the piezoelectric element 300 is bonded to the surface on the piezoelectric element 300 side on the flow path forming substrate 10. Yes. Since the piezoelectric element 300 is formed inside the piezoelectric element holding part 31, it is protected in a state where it is hardly affected by the external environment. Furthermore, the protective substrate 30 is provided with a reservoir portion 32 in a region corresponding to the communication portion 13 of the flow path forming substrate 10. The reservoir portion 32 is provided along the direction in which the pressure generation chambers 12 are arranged so as to penetrate the protective substrate 30 in the thickness direction, and is connected to the communication portion 13 of the flow path forming substrate 10 to be shared by the pressure generation chambers 12. A reservoir 100 serving as an ink chamber is configured.

  A through hole 33 penetrating the protective substrate 30 in the thickness direction is provided in a region between the piezoelectric element holding portion 31 and the reservoir portion 32 of the protective substrate 30, and one of the lower electrode films 60 is provided in the through hole 33. And the tip of the lead electrode 90 are exposed, and one end of a connection wiring extending from the driving IC is connected to the lower electrode film 60 and the lead electrode 90, although not shown.

  The protective substrate 30 is formed using a silicon single crystal substrate made of substantially the same material as the thermal expansion coefficient of the flow path forming substrate 10. For example, the protective substrate 30 can be formed of glass, ceramic material, metal, resin, or the like.

  A compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the protective substrate 30. The sealing film 41 is made of a material having low rigidity and flexibility (for example, a polyphenylene sulfide (PPS) film), and one surface of the reservoir portion 32 is sealed by the sealing film 41. The fixing plate 42 is made of a hard material such as metal (for example, stainless steel (SUS)). A region of the fixing plate 42 facing the reservoir 100 is an opening 43 that is completely removed in the thickness direction, and one surface of the reservoir 100 is sealed only by a flexible sealing film 41. Yes.

  In the above-described ink jet recording head, ink is taken in from an external ink supply means (not shown), filled with ink from the reservoir 100 to the nozzle opening 21, and then the pressure generating chamber 12 according to a recording signal from a driving IC (not shown). A voltage is applied between the lower electrode film 60 and the upper electrode film 80 corresponding to. By applying a voltage, the elastic film 50, the insulator film 55, the lower electrode film 60, and the piezoelectric layer 70 are bent and deformed, and the pressure in each pressure generation chamber 12 is increased and ink droplets are ejected from the nozzle openings 21. .

  A method for manufacturing the above-described ink jet recording head will be described with reference to FIGS. 4 to 6 are sectional views of the pressure generating chamber 12 in the longitudinal direction.

  As shown in FIG. 4A, a flow path forming substrate wafer 110, which is a silicon wafer, is thermally oxidized in a diffusion furnace at about 1100 ° C. to form a silicon dioxide film 51 constituting an elastic film 50 on the surface (step). A).

  As shown in FIG. 4B, an insulator film 55 made of zirconium oxide is formed on the elastic film 50 (silicon dioxide film 51). Specifically, a zirconium layer having a predetermined thickness is formed on the elastic film 50 by DC sputtering, for example (step B). Then, the flow path forming substrate wafer 110 on which the zirconium layer is formed is thermally oxidized using, for example, an RTA (Rapid Thermal Annealing) method to form an insulator film 55 made of zirconium oxide (Step C).

  After forming the insulator film 55, the insulator film 55 is annealed at a temperature equal to or lower than the maximum temperature when the zirconium layer is thermally oxidized (step D). By changing conditions such as temperature and time in the annealing process, the deformation of the flow path forming substrate wafer 110 in the initial process from the process A to the process C is adjusted, and the flow in the process of forming a piezoelectric element to be described later is performed. The deformation of the path forming substrate wafer 110 is guided (suppressed) to a desired range. Further, the deformation of the flow path forming substrate wafer 110 in the initial process is adjusted, and the deformation of the flow path forming substrate wafer 110 in the ink flow path etching process to be described later is guided (suppressed) to a desired range.

  Conditions such as the temperature and time of the annealing process performed after the initial process from the process A to the process C depend on the etching conditions in the process of forming the piezoelectric element described later and the etching conditions in the etching process of the ink flow path. Thus, the deformation of the flow path forming substrate wafer 110 is set to be induced (suppressed) within a desired range (annealing setting step). Depending on the state of deformation of the flow path forming substrate wafer 110 in the initial process from process A to process C, the etching conditions in the process of forming a piezoelectric element described later, and the etching conditions in the ink flow path etching process, In some cases, annealing is not performed. That is, the annealing process is controlled based on the setting of the annealing process setting process.

  After the insulator film 55 is formed (after the insulator film 55 is annealed), a lower electrode film 60 is formed as shown in FIG. For example, platinum and iridium are stacked on the insulator film 55 by sputtering (process E), and patterned into a predetermined shape to form the lower electrode film 60 (process F).

  Next, as shown in FIG. 5A, for example, a piezoelectric layer 70 made of lead zirconate titanate (PZT) is formed on the flow path forming substrate wafer 110. That is, a so-called sol in which a metal organic substance is dissolved and dispersed in a solvent is applied, dried and gelled (step G), and baked at a high temperature to obtain the piezoelectric layer 70 made of a metal oxide. That is, the piezoelectric layer 70 made of lead zirconate titanate (PZT) is formed using a sol-gel method. Further, for example, an upper electrode film 80 made of iridium is laminated by sputtering (step H). As a result, the piezoelectric layer 70 and the upper electrode film 80 are formed on the entire surface of the flow path forming substrate wafer 110.

As shown in FIG. 5B, the piezoelectric element 300 is formed by patterning the piezoelectric layer 70 and the upper electrode film 80 in regions facing the pressure generating chambers 12 (step I). Then, as shown in FIG. 5C, a metal layer 91 made of, for example, gold (Au) or the like is formed over the entire surface of the flow path forming substrate wafer 110. Thereafter, for example, the lead electrode 90 is formed by patterning the metal layer 91 for each piezoelectric element 300 through a mask pattern (not shown) made of a resist or the like.
As a result, the piezoelectric element 300 is formed on the entire surface of the flow path forming substrate wafer 110.

  6A, a protective substrate wafer 130, which is a silicon wafer and serves as a plurality of protective substrates 30, is bonded to the flow path forming substrate wafer 110 on the piezoelectric element 300 side. As shown in FIG. 6B, after the flow path forming substrate wafer 110 is polished to a certain thickness, the flow path forming substrate wafer 110 is made to have a predetermined thickness by wet etching with fluorinated nitric acid. .

  Next, as shown in FIG. 6C, a mask film 52 made of, for example, silicon nitride (SiN) is newly formed on the flow path forming substrate wafer 110 and patterned into a predetermined shape. Then, by anisotropically etching the flow path forming substrate wafer 110 through the mask film 52, the pressure generating chamber 12 and the communication portion are formed in the flow path forming substrate wafer 110 as shown in FIG. 13 and the ink supply path 14 are formed.

  Thereafter, unnecessary portions of the outer peripheral edge portions of the flow path forming substrate wafer 110 and the protective substrate wafer 130 are removed by cutting, for example, by dicing. The nozzle plate 20 having the nozzle openings 21 is bonded to the surface of the flow path forming substrate wafer 110 opposite to the protective substrate wafer 130, and the compliance substrate 40 is bonded to the protective substrate wafer 130. The flow path forming substrate wafer 110 or the like is divided into a single chip size flow path forming substrate 10 or the like as shown in FIG. 1 to obtain an ink jet recording head.

  For example, three types of conditions for the annealing process in the process D described above are set. Condition 1 is a temperature of 850 ° C. and a time is 1 hour, condition 2 is a temperature of 700 ° C. and a time is 1 hour, and condition 3 is a condition in which annealing treatment is not performed. The annealing conditions can be set as appropriate depending on, for example, the processing time and the processing atmosphere (oxidation and inert atmosphere). By setting various conditions, the amount of warpage (in-film stress) can be varied. Can be controlled. In addition, optimum conditions can be selected according to the characteristics of the product.

  A step of adjusting the deformation of the flow path forming substrate wafer 110 in the initial steps from step A to step C by appropriately setting the conditions, and forming the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80. The deformation of the flow path forming substrate wafer 110 is guided (suppressed) to a desired range. Further, the deformation of the flow path forming substrate wafer 110 in the initial process from the process A to the process C is adjusted, the flow path forming substrate wafer 110 is anisotropically etched, and the pressure generating chamber 12, the communication portion 13, and the ink The deformation of the flow path forming substrate wafer 110 in the process of forming the supply path 14 and the like is guided (suppressed) to a desired range.

  FIG. 7 shows the warpage amount of the flow path forming substrate wafer 110 in each process (process A to process I) when the annealing process in conditions 1 to 3 is performed.

  As shown in the figure, the process of approximating the warp amount to 0 μm is different for each of the conditions 1 to 3, for example, when the annealing process is set under the condition 2, for the flow path forming substrate in the process of forming the piezoelectric element The flatness of the wafer 110 is ensured. Further, when the annealing process is set under the condition 3 (the annealing process is not performed), the stage before the process of forming the pressure generation chamber 12, the communication portion 13, the ink supply path 14, and the like (the flow path forming substrate wafer 110). The flatness of the flow path forming substrate wafer 110 at the stage when the piezoelectric element is formed on the entire surface is ensured.

  The results under conditions 1 to 3 vary depending on the thickness of the film including the piezoelectric element, sputtering conditions, and the like, and are not specified in the situation shown in the drawing.

  Accordingly, by setting the annealing conditions so that the warpage amount of the flow path forming substrate wafer 110 in the step of forming the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80 is approximated to 0 μm, In the step of applying the metal sol, it is possible to suppress uneven film thickness and uneven drying due to warpage during coating and drying, and to improve the uniformity of the in-plane characteristic distribution of the ferroelectric film. Further, by setting the annealing conditions so that the flatness of the flow path forming substrate wafer 110 at the stage where the piezoelectric elements are formed on the entire surface of the flow path forming substrate wafer 110, the pressure generating chamber 12 is set. The pattern accuracy can be ensured by anisotropic etching that forms the communication portion 13 and the ink supply path 14.

  By using the manufacturing method described above, it is possible to control the deformation of the substrate that is formed in the early stage of the manufacturing process and has a great influence on the post-process so as to suppress the influence in the piezoelectric element forming process to a minimum. .

  In addition, the manufacturing method of this invention can be used for manufacture of a MEMS, an electronic device which laminates | stacks, processes, and forms a composite film on a board | substrate, for example.

FIG. 2 is an exploded perspective view illustrating a recording head according to an exemplary embodiment. It is a top view of FIG. It is the III-III arrow directional view in FIG. It is process explanatory drawing of the manufacturing method of the example of an embodiment. It is process explanatory drawing of the manufacturing method of the example of an embodiment. It is process explanatory drawing of the manufacturing method of the example of an embodiment. It is a graph showing the curvature amount of the board | substrate for every process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Flow path formation board | substrate, 12 Pressure generation chamber, 20 Nozzle plate, 21 Nozzle opening, 30 Protection board, 31 Piezoelectric element holding | maintenance part, 32 Reservoir part, 40 Compliance board | substrate, 50 Elastic film, 55 Insulator film, 60 Lower electrode film , 70 piezoelectric layer, 80 upper electrode film, 100 reservoir, 110 passage-forming substrate wafer, 300 piezoelectric element

Claims (4)

  It has a step of forming a piezoelectric element composed of a lower electrode, a piezoelectric layer and an upper electrode on one surface of the substrate, and sets the state of the previous annealing process for forming the piezoelectric element based on the state of formation of the piezoelectric element An actuator device manufacturing method comprising: an annealing treatment setting step for controlling the annealing treatment based on the setting of the annealing treatment setting step. In the manufacturing method of the actuator device according to claim 1,
The method of manufacturing an actuator device, wherein the state of formation of the piezoelectric element is a state of precursor formation of the piezoelectric layer. In the manufacturing method of the actuator device according to claim 1 or 2,
In the annealing treatment setting step, a condition for the annealing treatment is determined, and the annealing treatment is executed based on the determined condition. In the manufacturing method of the actuator device according to claim 3,
The method for manufacturing an actuator device, wherein the annealing treatment condition includes whether or not the annealing treatment is performed.

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