JP2006123212A - Process for manufacturing liquid ejection head and liquid ejection head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for manufacturing a liquid ejection head capable of protecting a piezoelectric element against breakage surely over a long term, and to provide a liquid ejection head. <P>SOLUTION: The process for manufacturing a liquid ejection head comprises a step for forming a piezoelectric element consisting of a lower electrode 60, a piezoelectric layer 70 and an upper electrode 80 through a vibrating plate on one side of a channel forming substrate in which a pressure generating chamber communicating with nozzle openings for ejecting a liquid drop is formed, and a step for forming the protective film 100 composed of an inorganic insulating material at least in a region opposing the piezoelectric element. In the step for forming the protective film, a protective film 100 of a predetermined thickness is formed by repeating a step for forming an inorganic insulating material layer 101 by coating the surface of the channel forming substrate with an inorganic insulating material, and a step for cleaning the surface of the inorganic insulating material layer 101 to remove foreign substances 105 adhered during the film formation step alternately a plurality of times. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a liquid ejecting head and a liquid ejecting head, and in particular, a part of a pressure generating chamber communicating with a nozzle opening for ejecting ink droplets is configured by a diaphragm, and a piezoelectric element is provided on the surface of the diaphragm. The present invention relates to a method for manufacturing an ink jet recording head that is formed and ejects ink droplets by displacement of a piezoelectric element, and an ink jet recording head.

  A part of the pressure generation chamber communicating with the nozzle opening for discharging ink droplets is constituted by a vibration plate, and the vibration plate is deformed by a piezoelectric element to pressurize the ink in the pressure generation chamber to discharge ink droplets from the nozzle opening. Two types of ink jet recording heads have been put into practical use: those using a longitudinal vibration mode piezoelectric actuator that extends and contracts in the axial direction of the piezoelectric element, and those using a flexural vibration mode piezoelectric actuator.

  The former can change the volume of the pressure generation chamber by bringing the end face of the piezoelectric element into contact with the diaphragm, and it is possible to manufacture a head suitable for high-density printing, while the piezoelectric element is arranged in an array of nozzle openings. There is a problem that the manufacturing process is complicated because a difficult process of matching the pitch into a comb-like shape and an operation of positioning and fixing the cut piezoelectric element in the pressure generating chamber are necessary.

  On the other hand, the latter can flexibly vibrate, although a piezoelectric element can be built on the diaphragm by a relatively simple process of sticking a green sheet of piezoelectric material according to the shape of the pressure generation chamber and firing it. There is a problem that a certain amount of area is required for the use of, and high-density arrangement is difficult.

  On the other hand, in order to eliminate the disadvantages of the latter recording head, 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 shaped to correspond to the pressure generating chamber by lithography. In some cases, the piezoelectric element is formed so as to be independent for each pressure generating chamber. Further, such a piezoelectric element has a problem that it is easily destroyed due to an external environment such as moisture. In order to solve this problem, a sealing substrate (reservoir forming substrate) having a piezoelectric element holding portion is bonded to a flow path forming substrate in which a pressure generating chamber is formed, and the piezoelectric element is sealed in the piezoelectric element holding portion. There is something like that (see, for example, Patent Document 1).

  However, even if the piezoelectric element is sealed in this way, moisture in the piezoelectric element holding portion gradually increases due to, for example, moisture entering the piezoelectric element holding portion from the bonded portion between the sealing substrate and the flow path forming substrate. However, there is a problem that the piezoelectric element is eventually destroyed by the moisture. Such a problem exists not only in an ink jet recording head that ejects ink droplets, but also in other liquid ejecting heads that eject droplets other than ink.

JP 2003-136734 A (FIGS. 1, 2 and 5)

  In view of such circumstances, it is an object of the present invention to provide a method of manufacturing a liquid ejecting head and a liquid ejecting head that can reliably prevent destruction of a piezoelectric element over a long period of time.

According to a first aspect of the present invention for solving the above-described problems, a lower electrode and a piezoelectric element are disposed on one surface side of a flow path forming substrate in which pressure generating chambers communicating with nozzle openings for discharging droplets are formed via a diaphragm. A piezoelectric element forming step of forming a piezoelectric element comprising a body layer and an upper electrode; and a protective film forming step of forming a protective film made of an inorganic insulating material at least in a region facing the piezoelectric element, and the protective film In the forming step, a film forming step in which an inorganic insulating material is applied to the surface of the flow path forming substrate to form an inorganic insulating material layer, and a foreign matter adhered in the film forming step by cleaning the surface of the inorganic insulating material layer. In the method of manufacturing a liquid ejecting head, the protective film is formed to have a predetermined thickness by alternately repeating a cleaning process to be removed a plurality of times.
In the first aspect, formation defects such as pinholes are prevented, and a highly moisture-resistant protective film is formed. Therefore, it is possible to reliably prevent the destruction of the piezoelectric element due to moisture. In addition, since the piezoelectric element can be prevented from being destroyed even if the protective film is relatively thin, a decrease in the displacement amount of the piezoelectric element due to the protective film can be suppressed to a low level.

According to a second aspect of the present invention, in the first aspect, in the protective film forming step, the protective film is formed to a predetermined thickness by stacking four or more inorganic insulating material layers. A method of manufacturing a liquid jet head.
In the second aspect, a protective film having high moisture resistance can be more reliably formed.

According to a third aspect of the present invention, in the first or second aspect, the thickness of the laminated protective film is 100 nm or less.
In the third aspect, it is possible to manufacture a head having good ejection characteristics while preventing the piezoelectric element from being destroyed and suppressing a decrease in the displacement amount of the piezoelectric element.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the inorganic insulating material is aluminum oxide.
In the fourth aspect, by using aluminum oxide, a protective film having high moisture resistance can be reliably formed.

According to a fifth aspect of the present invention, in the liquid jet head manufacturing method according to any one of the first to fourth aspects, the inorganic insulating material layer is formed by a CVD method.
In the fifth aspect, the protective film can be formed relatively easily and satisfactorily.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, in the cleaning step, the foreign matter is removed by cleaning a surface of the inorganic insulating material layer with a predetermined cleaning liquid. A method of manufacturing a liquid jet head.
In the sixth aspect, the foreign matter adhered in the film forming process can be reliably removed.

According to a seventh aspect of the present invention, in the sixth aspect, the liquid jet head manufacturing method is characterized in that ultrasonic vibration is applied to the cleaning liquid.
In the seventh aspect, foreign matter adhering in the film forming process can be more reliably removed.

According to an eighth aspect of the present invention, in the sixth or seventh aspect, the liquid jet head manufacturing method is characterized in that the cleaning liquid is pure water or water containing a predetermined gas.
In the eighth aspect, the surface of the inorganic insulating material layer can be cleaned well.

According to a ninth aspect of the present invention, in any one of the first to fifth aspects, the cleaning step includes removing the foreign matter by scrub cleaning the surface of the inorganic insulating material layer with a predetermined brush. A method of manufacturing a liquid jet head.
In the ninth aspect, the foreign matter adhering in the film forming process can be reliably removed.

According to a tenth aspect of the present invention, there is provided a liquid jet head formed by the manufacturing method according to any one of the first to ninth aspects.
In the tenth aspect, it is possible to realize a liquid jet head that is excellent in durability and reliability.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
1 is an exploded perspective view showing an ink jet recording head according to Embodiment 1 of the present invention, FIG. 2 is a plan view and a cross-sectional view of FIG. 1, and FIG. 3 is a plan view showing a main part. . As shown in the drawing, 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. An elastic film 50 of 5 to 2 μm is formed. A plurality of pressure generating chambers 12 are arranged in parallel in the width direction of the flow path forming substrate 10. In addition, 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 supply 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.

Further, on the opening surface side of the flow path forming substrate 10, an insulating film 51 used as a mask when forming the pressure generating chambers 12 is interposed on the side opposite to the ink supply path 14 of each pressure generating chamber 12. A nozzle plate 20 having a nozzle opening 21 communicating in the vicinity of the end is fixed through an adhesive, a heat-welded film, or the like. The nozzle plate 20 has a thickness of, for example, 0.01 to 1 mm, a linear expansion coefficient of 300 ° C. or less, for example, 2.5 to 4.5 [× 10 ⁻⁶ / ° C.], glass ceramics, silicon It consists of a single crystal substrate or non-rust steel.

  On the other hand, as described above, the elastic film 50 having a thickness of, for example, about 1.0 μm is formed on the side opposite to the opening surface of the flow path forming substrate 10. For example, an insulator film 55 having a thickness of about 0.4 μm is formed. Further, on the insulator film 55, a lower electrode film 60 having a thickness of, for example, about 0.2 μm, a piezoelectric layer 70 having a thickness of, for example, about 1.0 μm, and a thickness of, for example, about 0 The upper electrode film 80 having a thickness of 0.05 μm is laminated by a process described later to constitute the piezoelectric element 300. Here, 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. In addition, here, a portion that is configured by 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 referred to as 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 either case, a piezoelectric active part is formed for each pressure generating chamber. Further, here, the piezoelectric element 300 and the vibration plate that is displaced by driving the piezoelectric element 300 are collectively referred to as a piezoelectric actuator.

  For example, in the present embodiment, as shown in FIG. 3, the lower electrode film 60 is formed in a region facing the pressure generation chamber 12 in the longitudinal direction of the pressure generation chamber 12, and corresponds to the plurality of pressure generation chambers 12. It is provided continuously in the area. Further, the lower electrode film 60 extends from the outside of the row of the pressure generating chambers 12 and between the arranged piezoelectric elements 300 to the vicinity of the communication portion 13, and the tip portion thereof extends from a drive IC 200 described later. The connection portion 60a is connected to the connection wiring 210. The piezoelectric layer 70 and the upper electrode film 80 are basically provided in a region facing the pressure generation chamber 12, but in the longitudinal direction of the pressure generation chamber 12, the piezoelectric layer 70 and the upper electrode film 80 are outside the end portion of the lower electrode film 60. The end surface of the lower electrode film 60 is covered with the piezoelectric layer 70. In the vicinity of the longitudinal end of the pressure generation chamber 12, a piezoelectric inactive portion 330 having a piezoelectric layer but not substantially driven is formed. A lead electrode 90 is connected to the vicinity of one end of the upper electrode film 80. In this embodiment, the lead electrode 90 extends from the piezoelectric inactive portion 330 outside the pressure generating chamber 12 to the vicinity of the communicating portion 13, and the tip thereof is the same as the lower electrode film 60. A connection portion 90a is connected to the connection wiring 210.

  Then, at least each layer constituting the piezoelectric element 300, in this embodiment, each layer constituting the piezoelectric element 300 and the pattern region of the lead electrode 90 are opposed to the connection portion 60a of the lower electrode film 60 and the connection portion 90a of the lead electrode 90. Except for the region to be covered, it is covered with the protective film 100. That is, the surfaces (upper surface and end surface) of the lower electrode film 60, the piezoelectric layer 70, the upper electrode film 80, and the lead electrode 90 in the pattern region are covered with the protective film 100 made of an inorganic insulating material.

  Since the protective film 100 made of such an inorganic insulating material has a very low moisture permeability even in a thin film, the protective film 100 covers at least the surfaces of the lower electrode film 60, the piezoelectric layer 70, and the upper electrode film 80 with the protective film 100. In addition, it is possible to prevent the piezoelectric layer 70 from being damaged due to moisture (humidity). Further, in the present embodiment, since the surfaces of the layers constituting the piezoelectric element 300 and the lead electrode 90 are covered except for the connection portions 60a and 90a, moisture is absorbed from between these layers and the protective film 100. Even when it penetrates, it is possible to prevent moisture from reaching the piezoelectric layer 70 and to more reliably prevent breakage of the piezoelectric layer 70 due to moisture.

  Further, as will be described later in detail, the protective film 100 is formed by applying an inorganic insulating material on the flow path forming substrate 10 to form an inorganic insulating material layer, and cleaning the surface of the inorganic insulating material layer. In this way, the cleaning process for removing the foreign matter attached in the film forming process is alternately repeated a plurality of times. Thereby, when forming the protective film 100, it is possible to prevent, for example, formation defects such as pinholes. Therefore, the protective film 100 with high moisture resistance can be formed.

The material of the protective film 100 is not particularly limited as long as it is an inorganic insulating material. Examples thereof include aluminum oxide (Al ₂ O ₃ ) and tantalum pentoxide (Ta ₂ O ₅ ). It is preferable to use (Al ₂ O ₃ ). When aluminum oxide is used as the material of the protective film 100, moisture permeation in a high humidity environment can be sufficiently prevented even if the protective film 100 is formed as thin as 100 nm or less. is there.

  Further, a protective substrate 30 having a piezoelectric element holding portion 31 capable of securing a space that does not hinder the movement of the region facing the piezoelectric element 300 is bonded to the surface of the flow path forming substrate 10 on the piezoelectric element 300 side. It is joined via the agent 35. Since the piezoelectric element 300 is formed in the piezoelectric element holding part 31, it is protected in a state hardly affected by the external environment. The piezoelectric element holding part 31 may be sealed or may not be sealed.

  The protective substrate 30 is provided with a reservoir portion 32 in a region corresponding to the communication portion 13 of the flow path forming substrate 10. In this embodiment, the reservoir portion 32 is provided along the direction in which the pressure generating chambers 12 are arranged so as to penetrate the protective substrate 30 in the thickness direction, and as described above, the communication portion of the flow path forming substrate 10. The reservoir 33 is connected to the pressure generation chamber 12 and serves as an ink chamber common to the pressure generation chambers 12.

  Furthermore, a through hole 34 that penetrates 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 the above-described lower electrode is provided in the through hole 34. The connection portion 60a of the film 60 and the connection portion 90a of the lead electrode 90 are exposed. One end of a connection wiring 210 extending from the drive IC 200 mounted on the protective substrate 30 is connected to the connection portion 60 a of the lower electrode film 60 and the connection portion 90 a of the lead electrode 90. The through hole 34 in which the connection wiring 210 is extended is filled with an organic insulating material, for example, a sealing material 220 as a potting material in the present embodiment, and the connection portion 60a of the lower electrode film 60 is filled. The connecting portion 90 a of the lead electrode 90 and the connection wiring 210 are completely covered with the sealing material 220.

  In addition, examples of the material of the protective substrate 30 include glass, ceramic material, metal, resin, and the like, but it is more preferable that the material is substantially the same as the coefficient of thermal expansion of the flow path forming substrate 10. In this embodiment, the silicon single crystal substrate made of the same material as the flow path forming substrate 10 is used.

  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 having a thickness of 6 μm). Yes. The fixing plate 42 is made of a hard material such as metal (for example, stainless steel (SUS) having a thickness of 30 μm). Since the region of the fixing plate 42 facing the reservoir 33 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir 33 is sealed only with a flexible sealing film 41. Has been.

  In such an ink jet recording head of this embodiment, after taking ink from an external ink supply means (not shown) and filling the interior from the reservoir 33 to the nozzle opening 21, the pressure is applied according to the recording signal from the drive IC 200. By applying a voltage between each of the lower electrode film 60 and the upper electrode film 80 corresponding to the generation chamber 12, the elastic film 50, the insulator film 55, the lower electrode film 60, and the piezoelectric layer 70 are bent and deformed. The pressure in each pressure generating chamber 12 is increased, and ink droplets are ejected from the nozzle openings 21.

  Here, a method of manufacturing such an ink jet recording head will be described with reference to FIGS. 4 to 7 are cross-sectional views of the pressure generation chamber 12 in the longitudinal direction. First, as shown in FIG. 4A, a flow path forming substrate wafer 110 made of a silicon wafer and integrally formed with a plurality of flow path forming substrates 10 is thermally oxidized in a diffusion furnace at about 1100 ° C. A silicon dioxide film 52 constituting the elastic film 50 is formed on the surface. In this embodiment, a silicon wafer having a relatively thick film thickness of about 625 μm and a high rigidity is used as the flow path forming substrate wafer 110.

Next, as shown in FIG. 4B, an insulator film 55 made of zirconium oxide is formed on the elastic film 50 (silicon dioxide film 52). Specifically, after a zirconium (Zr) layer is formed on the elastic film 50 (silicon dioxide film 52) 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 obtained.

  Next, as shown in FIG. 4C, 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. Next, as shown in FIG. 4D, for example, a piezoelectric layer 70 made of a ferroelectric piezoelectric material such as lead zirconate titanate (PZT) and an upper electrode film 80 made of, for example, iridium are formed. It is formed on the entire surface of the flow path forming substrate wafer 110. Thereafter, as shown in FIG. 5A, the piezoelectric layer 70 and the upper electrode film 80 are patterned in a region facing each pressure generating chamber 12 to form the piezoelectric element 300.

In addition to the ferroelectric piezoelectric material such as lead zirconate titanate (PZT), for example, niobium, nickel, magnesium, bismuth or yttrium may be used as the material of the piezoelectric layer 70 constituting the piezoelectric element 300. It is also possible to use a relaxor ferroelectric or the like to which a metal such as is added. The composition may be appropriately selected in consideration of the characteristics, application, etc. of the piezoelectric element 300. For example, PbTiO ₃ (PT), PbZrO ₃ (PZ), Pb (Zr _x Ti _1-x ) O ₃ (PZT) ), Pb (Mg _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ (PMN-PT), Pb (Zn _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ (PZN-PT), Pb (Ni ₁ ) _{/ 3 Nb 2/3) O 3 -PbTiO} 3 (PNN-PT), Pb (In 1/2 Nb 1/2) O 3 -PbTiO 3 (PIN-PT), Pb (Sc 1/3 Ta 2/3 ) O ₃ —PbTiO ₃ (PST-PT), Pb (Sc _1/3 Nb _2/3 ) O ₃ —PbTiO ₃ (PSN-PT), BiScO ₃ —PbTiO ₃ (BS-PT), BiYbO ₃ —PbTiO ₃ (BY PT), and the like.

  Next, as shown in FIG. 5B, lead electrodes 90 drawn from the upper electrode film 80 of each piezoelectric element 300 are formed. Specifically, 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, and this metal layer 91 is made of a mask pattern (for example, made of resist or the like). The patterning is performed for each piezoelectric element 300. Note that an adhesion layer made of, for example, titanium tungsten (TiW) may be formed below the metal layer 91 constituting the lead electrode 90.

Next, as shown in FIG. 5C, for example, a protective film 100 made of aluminum oxide (Al ₂ O ₃ ) is formed and patterned into a predetermined shape. As described below, in the present invention, a film forming process for forming an inorganic insulating material layer 101 by applying an inorganic insulating material on the flow path forming substrate wafer 110, and cleaning the surface of the inorganic insulating material layer 101. Then, the protective film 100 is formed by alternately repeating a cleaning process for removing the foreign matter 105 attached in the film forming process a plurality of times.

  Specifically, first, as shown in FIG. 6A, aluminum oxide, which is an inorganic insulating material, is applied to the entire surface of the flow path forming substrate wafer 110, so that the inorganic insulating material layer 101 (101a) has a predetermined thickness. For example, in this embodiment, it is formed to a thickness of about 25 nm. A method for forming the inorganic insulating material layer 101 is not particularly limited. For example, by employing a CVD method, the inorganic insulating material layer 101 having a good film quality can be formed relatively easily.

  Here, when the inorganic insulating material layer 101 is formed, for example, foreign matter 105 such as dust adheres to the surface of the flow path substrate wafer 110. For example, by forming the inorganic insulating material layer 101 in a clean room or the like, such adhesion of foreign matter can be prevented to some extent, but it is difficult to prevent it completely. The thickness of the inorganic insulating material layer 101 is about 25 nm, whereas the diameter of the foreign material 105 is extremely large, for example, about several μm to several tens of μm.

  Therefore, in the manufacturing method of the present invention, a cleaning process is performed after the film forming process to remove such foreign matter 105. In this embodiment, the surface of the inorganic insulating material layer 101a is cleaned with a predetermined cleaning liquid, thereby removing the foreign matter 105a attached when the inorganic insulating material layer 101a is formed (FIG. 6B). Note that a penetrating portion 102a that substantially penetrates the inorganic insulating material layer 101a is formed in the portion of the inorganic insulating material layer 101a from which the foreign matter 105a has been removed.

The cleaning liquid used in such a cleaning process is not particularly limited, but for example, pure water is preferably used. Alternatively, cleaning with a pure water mixed with, for example, CO ₂ gas makes it easier to remove foreign matters. Specifically, pure water is discharged from one nozzle and gas is jetted from one nozzle to create water in which gas is mixed into pure water, and this water is applied to the surface of the inorganic insulating material layer 101a. When sprayed, the water becomes fine droplets. As a result, the impact on the surface of the inorganic insulating material layer 101a is strengthened, and foreign matters are more easily removed. Further, when the cleaning liquid is sprayed on the surface of the inorganic insulating material layer 101a, ultrasonic vibration of about 1 MHz may be applied to the cleaning liquid, for example. Thereby, the foreign material 105a on the surface of the inorganic insulating material layer 101a can be reliably removed.

  Further, the cleaning method in the cleaning process is not limited to cleaning using a cleaning liquid, and may be, for example, so-called scrub cleaning in which the surface of the inorganic insulating material layer 101 is cleaned with a brush. Of course, even with such a cleaning method, the foreign matter 105 can be reliably removed. However, when using a brush, it is necessary to consider, for example, the material of the brush and various conditions during cleaning so as not to damage the surface of the inorganic insulating material layer 101.

  Next, as shown in FIG. 6C, the inorganic insulating material is applied again on the inorganic insulating material layer 101a to form the inorganic insulating material layer 101b with a thickness of about 25 nm. At this time, the through portion 102a of the inorganic insulating material layer 101a is closed by the inorganic insulating material layer 101b. Next, as described above, the surface of the inorganic insulating material layer 101b is washed with, for example, a cleaning liquid, thereby removing the foreign matter 105b attached when the inorganic insulating material layer 101b is formed (FIG. 6D). . Note that a through portion 102b is formed in the portion of the inorganic insulating material layer 101b from which the foreign matter 105b has been removed, as in the case of the inorganic insulating material layer 101a. It is only penetrating through.

  Then, the protective film 100 having a predetermined thickness is formed by laminating a plurality of inorganic insulating material layers 101 by alternately repeating the film forming process and the cleaning process a plurality of times (FIG. 5C). ). For example, in this embodiment, the protective film 100 having a thickness of about 100 nm is formed by stacking four layers of the inorganic insulating material layer 101.

  Thus, the protective film 100 having extremely high moisture resistance can be formed by alternately repeating the film forming process and the cleaning process a plurality of times. Specifically, when foreign matter remains in the protective film or when a through hole (pinhole) is formed in the protective film, moisture may enter from the portion and the piezoelectric element may be destroyed. There is. However, according to the manufacturing method of the present invention, the foreign material 105 does not exist in the protective film 100, and no pinhole is formed in the protective film 100.

  Here, as described above, in each inorganic insulating material layer 101, a through hole 102 that substantially penetrates the inorganic insulating material layer 101 may be formed in a portion where the foreign matter 105 is removed. However, by laminating a plurality of inorganic insulating material layers 101, each through hole 102 is blocked, and therefore, the possibility that a through hole (pin hole) is formed in the protective film 100 is extremely small.

  Therefore, it is possible to form the protective film 100 having extremely high moisture resistance, and it is possible to surely prevent the damage due to moisture of the piezoelectric element 300 and to greatly improve the durability of the piezoelectric element.

  Further, by improving the moisture resistance, even if the thickness of the protective film 100 is relatively thin, such as about 100 nm, it is possible to prevent breakage due to moisture of the piezoelectric element 300, thereby preventing the displacement of the piezoelectric element 300. The decrease can also be kept small. In the present embodiment, the protective film 100 is formed to have a thickness of about 100 nm. However, for example, even when the protective film 100 has a thickness of about 40 nm, the piezoelectric element 300 is destroyed due to moisture. It can be prevented.

  After the protective film 100 is formed on the entire surface of the flow path forming substrate wafer 110 as described above, the protective film 100 is patterned into a predetermined shape as shown in FIG. That is, the protective film 100 in the region facing the connection portion 60a of the lower electrode film 60 and the connection portion 90a of the lead electrode 90 is removed. In the present embodiment, the layers other than the layers constituting the piezoelectric element 300 and the pattern region of the lead electrode 90 are removed together with the regions facing the connection portions 60a and 90a. Of course, the protective film 100 may be removed only in a region facing the connection portions 60a and 90a. In any case, the protective film 100 may be formed so as to cover at least each layer constituting the piezoelectric element 300. The method for removing the protective film 100 is not particularly limited, but for example, dry etching such as ion milling is preferably used. Thereby, the protective film 100 can be selectively removed favorably.

  Next, as shown in FIG. 7B, a protective substrate wafer 130 in which a plurality of protective substrates 30 are integrally formed is bonded to the piezoelectric element 300 side of the flow path forming substrate wafer 110 by an adhesive 35. . The protective substrate wafer 130 is previously formed with a piezoelectric element holding portion 31, a reservoir portion 32, and the like. Further, the protective substrate wafer 130 is a silicon wafer having a thickness of about 400 μm, for example, and the rigidity of the flow path forming substrate wafer 110 is significantly improved by bonding the protective substrate wafer 130.

  Next, as shown in FIG. 7C, after the flow path forming substrate wafer 110 is polished to a certain thickness, it is further wet-etched with fluorinated nitric acid. Make it thick. For example, in this embodiment, the flow path forming substrate wafer 110 is processed to have a thickness of about 70 μm by polishing and wet etching.

  Next, as shown in FIG. 7D, an insulating film 51 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, the flow path forming substrate wafer 110 is anisotropically etched (wet etching) through the insulating film 51, and the pressure generating chamber 12, the communication portion 13, the ink supply path 14, etc. Form.

  After that, the drive IC 200 is mounted on the protective substrate wafer 130, and the drive IC 200 and the lead electrode 90 are connected by the drive wiring 210. Furthermore, 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 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. The flow path forming substrate wafer 110 and the like are divided into a single chip size flow path forming substrate 10 as shown in FIG. Thereby, the ink jet recording head having the above-described structure is manufactured.

(Other embodiments)
As mentioned above, although each embodiment of this invention was described, this invention is not limited to embodiment mentioned above. For example, in the embodiment described above, the protective film 100 is formed by laminating four layers of the inorganic insulating material layer 101. However, the inorganic insulating material layer 101 may be laminated in two or more layers. Three layers may be sufficient and five layers or more may be sufficient.

  Further, for example, in the above-described embodiment, the piezoelectric element 300 is formed in the piezoelectric element holding portion 31 of the protective substrate 30. However, the present invention is not limited to this, and the piezoelectric element 300 may be exposed. Even in this case, since the surfaces of the piezoelectric element 300 and the lead electrode 90 are covered with the protective film 100 made of an inorganic insulating material, the destruction of the piezoelectric layer 70 due to moisture (humidity) is reliably prevented. . Furthermore, in the above-described embodiment, the tip portion of the lower electrode film 60 extended to the vicinity of the communication portion 13 is the connection portion 60a with the connection wiring 210. For example, as in the case of the upper electrode film 80 The lead electrode may also be drawn out from the lower electrode film 60, and the tip thereof may be used as a connection portion with the connection wiring 210.

  The ink jet recording head according to the above-described embodiment constitutes a part of a recording head unit including an ink flow path communicating with an ink cartridge or the like, and is mounted on the ink jet recording apparatus. FIG. 8 is a schematic view showing an example of the ink jet recording apparatus. As shown in FIG. 8, in the recording head units 1A and 1B having the ink jet recording head, cartridges 2A and 2B constituting ink supply means are detachably provided, and a carriage 3 on which the recording head units 1A and 1B are mounted. Is provided on a carriage shaft 5 attached to the apparatus body 4 so as to be movable in the axial direction. The recording head units 1A and 1B, for example, are configured to eject a black ink composition and a color ink composition, respectively. The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted is moved along the carriage shaft 5. The On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller (not shown), is conveyed on the platen 8. It is like that.

  In the above-described embodiment, the ink jet recording head has been described as an example of the liquid ejecting head of the present invention. However, the basic configuration of the liquid ejecting head is not limited to the above-described configuration. The present invention covers a wide range of liquid ejecting heads, and can naturally be applied to those ejecting liquids other than ink. 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 (surface emitting 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.

FIG. 3 is an exploded perspective view of the recording head according to the first embodiment. 2A and 2B are a plan view and a cross-sectional view of the recording head according to the first embodiment. FIG. 3 is a plan view illustrating a main part of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a manufacturing process of the recording head according to the first embodiment. 1 is a schematic diagram of a recording apparatus according to an embodiment.

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 | substrate, 31 Piezoelectric element holding | maintenance part 31 Reservoir part, 33 Reservoir, 34 Through-hole, 40 Compliance board | substrate, 50 Elastic film, 55 Insulator Film, 60 lower electrode film, 70 piezoelectric film, 80 upper electrode film, 100 protective film, 101 inorganic insulating material layer, 102 through portion, 200 driving IC, 210 connection wiring, 220 sealing material, 300 piezoelectric element

Claims (10)

Piezoelectric element for forming a piezoelectric element composed of a lower electrode, a piezoelectric layer and an upper electrode via a vibration plate on one side of a flow path forming substrate in which pressure generating chambers communicating with nozzle openings for discharging liquid droplets are formed A forming step, and a protective film forming step of forming a protective film made of an inorganic insulating material at least in a region facing the piezoelectric element,
In the protective film forming step, an inorganic insulating material is applied to the surface of the flow path forming substrate to form an inorganic insulating material layer, and the surface of the inorganic insulating material layer is washed and adhered in the film forming step. A method of manufacturing a liquid ejecting head, wherein the protective film is formed to a predetermined thickness by alternately repeating a cleaning step for removing the foreign matter performed a plurality of times. 2. The method of manufacturing a liquid jet head according to claim 1, wherein in the protective film forming step, the protective film is formed to have a predetermined thickness by stacking four or more inorganic insulating material layers. 3. The method of manufacturing a liquid jet head according to claim 1, wherein the thickness of the laminated protective film is 100 nm or less. The method of manufacturing a liquid jet head according to claim 1, wherein the inorganic insulating material is aluminum oxide. 5. The method of manufacturing a liquid jet head according to claim 1, wherein the inorganic insulating material layer is formed by a CVD method. 6. The method of manufacturing a liquid jet head according to claim 1, wherein, in the cleaning step, the foreign matter is removed by cleaning a surface of the inorganic insulating material layer with a predetermined cleaning liquid. The method of manufacturing a liquid jet head according to claim 6, wherein ultrasonic vibration is applied to the cleaning liquid. 8. The method of manufacturing a liquid jet head according to claim 6, wherein the cleaning liquid is pure water or water containing a predetermined gas. 6. The method of manufacturing a liquid jet head according to claim 1, wherein in the cleaning step, the foreign matter is removed by scrub cleaning the surface of the inorganic insulating material layer with a predetermined brush. A liquid jet head formed by the manufacturing method according to claim 1.

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