JP2010005900A - Ink-jet recording head, ink-jet recorder, and manufacturing method of ink-jet recording head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink-jet recording head, an ink-jet recorder and the manufacturing method of the ink-jet recording head which enable the miniaturization and cost reduction of the recording head to be progressed further. <P>SOLUTION: An ink-jet recording head is equipped with: a conduit formation substrate 1; a pressure generation chamber 3 formed in the surface of the conduit formation substrate 1; a nozzle opening part 5 which is formed in the conduit formation substrate 1 and communicates with the pressure generation chamber 3; an oscillating diaphragm 7 which is formed in the surface side of the conduit formation substrate 1 and covers the pressure generation chamber 3; a piezoelectric element 10 formed in the area opposite to the pressure generation chamber 3 across the oscillating diaphragm 7; a driver circuit 9 formed in the area which is the surface of the conduit formation substrate 1 and is located in a line with the pressure generation chamber 3; and a wiring layer 25 which is formed in the surface side of the conduit formation substrate 1 and connects the piezoelectric element 10 to the driver circuit 9. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink jet recording head, an ink jet recording apparatus, and a method for manufacturing an ink jet recording head.

Conventionally, in an ink jet recording head, a circuit for driving a piezoelectric element (hereinafter referred to as a driver circuit) is manufactured on a separate substrate as an IC element and mounted on the recording head. This connection has been performed by wire bonding (see, for example, Patent Document 1).
JP 2002-254639 A

In recent years, in order to reduce the size and performance of an ink jet recording head, the density of nozzle openings and the pitch of piezoelectric elements have been reduced.
However, when connecting the output terminal of the IC element and the piezoelectric element by wire bonding, it is necessary to keep the wires at least 50 μm apart (that is, the distance between the wires should be 50 μm or more), so a large area is secured. There is a need to. In addition, it is necessary to secure a certain space above the bonded area of the wire and bend the wire. For this reason, it is difficult to further advance the reduction in area and height of the recording head, the reduction in the pitch of the piezoelectric elements, and the increase in the density of the nozzle openings, and the connection by wire bonding is approaching its limit.

In addition, according to the technique disclosed in Patent Document 1, since the substrate having the driver circuit, the substrate having the pressure generating chamber, and the substrate having the nozzle are configured as separate substrates, respectively, the number of components is large and the cost is reduced. There was a problem that was difficult.
Therefore, the present invention has been made in view of such circumstances, and there is provided an ink jet recording head, an ink jet recording apparatus, and an ink jet recording head that can further advance the downsizing and cost reduction of the recording head. The purpose is to provide a manufacturing method.

[Invention 1] In order to achieve the above object, an ink jet recording head of Invention 1 is formed on a first substrate, a pressure generating chamber formed on one surface of the first substrate, and the first substrate. A nozzle opening communicating with the pressure generation chamber, a vibration film formed on one surface side of the first substrate and covering the pressure generation chamber, and facing the pressure generation chamber across the vibration film A piezoelectric element formed in a region, an integrated circuit formed in one region of the first substrate and aligned with the pressure generating chamber, and formed on one surface side of the first substrate, And a wiring layer for connecting the integrated circuit and the piezoelectric element. Here, the “integrated circuit” of the present invention is a driver circuit for driving an ink jet recording head, for example.
With such a configuration, since the integrated circuit, the pressure generation chamber, and the nozzle opening are all formed in the first substrate, the number of components can be reduced. As a result, the assembly process can be simplified, and the cost of the ink jet recording head can be reduced.

[Invention 2] The inkjet recording head of Invention 2 is the inkjet recording head of Invention 1, wherein the second substrate joined to one surface side of the first substrate across the vibration film, and the second And a reservoir formed on the substrate and communicating with the pressure generating chamber.
With such a configuration, the displacement of the piezoelectric element can be directly transmitted to the vibrating membrane, and the ink liquid supplied from the reservoir to the pressure generating chamber can be discharged from the nozzle opening.

[Invention 3] The inkjet recording head of Invention 3 is the inkjet recording head of Invention 2, further comprising an opening formed in the second substrate, wherein the opening has the vibration film as a bottom surface and the piezoelectric recording head. The element is arranged in the opening having the vibration film as a bottom surface.
With such a configuration, a space for extending and reducing the piezoelectric element on the second substrate can be secured, and a space necessary for connecting the integrated circuit and the piezoelectric element is reduced. The recording head can be reduced in height and area, the pitch of the piezoelectric elements can be reduced, and the density of the nozzle openings can be increased.

[Invention 4] The inkjet recording head according to Invention 4 is the inkjet recording head according to any one of Inventions 1 to 3, wherein the nozzle opening is opened on the other surface of the first substrate. It is a feature.
With such a configuration, the ink liquid can be discharged toward the other surface of the first substrate.

[Invention 5] The inkjet recording head of Invention 5 is the inkjet recording head according to any one of Inventions 2 to 4, further comprising a bonding layer for bonding the first substrate and the second substrate, Each of the one substrate and the second substrate is made of silicon, and the bonding layer is made of a silicon oxide film.
With such a configuration, the bonding layer can be formed thin by, for example, a CVD method or a coating method, which can contribute to a further reduction in the height of the ink jet recording head. In addition, since the adhesive layer can be formed with high purity so as not to contain organic substances, it is possible to perform a treatment with a high temperature even after the adhesive layer is formed, and the tolerance for the heat history can be increased. .

[Invention 6] The ink jet recording head of Invention 6 is the ink jet recording head according to any one of Inventions 1 to 5, wherein the wiring layer is made of a refractory metal. Here, as the high melting point metal, for example, a single metal such as tungsten (W), titanium (Ti), platinum (Pt), nickel (Ni), chromium (Cr), copper (Cu), or the like was used. Examples include alloys and silicide metals.
With such a configuration, it is possible to perform a process with a high temperature even after the wiring layer is formed, and the tolerance for the thermal history can be increased.
[Invention 7] An ink jet recording apparatus according to an invention 7 includes the ink jet recording head according to any one of the inventions 1 to 6.
With such a configuration, since the ink jet recording heads of the invention 1 to the invention 6 are applied, it is possible to reduce the size and cost of the ink jet recording apparatus.

[Invention 8] A method of manufacturing an ink jet recording head according to Invention 8 includes a step of forming a pressure generation chamber on one surface of a first substrate, and a nozzle opening communicating with the pressure generation chamber on the first substrate. A step of forming an integrated circuit in a region parallel to the pressure generation chamber on one surface of the first substrate, and a vibration film covering the pressure generation chamber on the one surface side of the first substrate. Forming a piezoelectric element in a region facing the pressure generating chamber across the vibration film, and forming a wiring layer connecting the integrated circuit and the piezoelectric element on one side of the first substrate And a step of forming on the surface side.
With such a method, the number of parts can be reduced and the assembly process can be simplified. Thereby, the cost of the ink jet recording head can be reduced.

[Invention 9] The method for manufacturing an ink jet recording head according to invention 9 is the method for manufacturing the ink jet recording head according to invention 8, wherein the step of forming the vibration film forms a vibration film on one surface of the second substrate. And a step of bonding one surface of the second substrate on which the vibration film is formed to the one surface side of the first substrate.
With such a method, the first substrate and the second substrate can be easily joined, and the connection between the integrated circuit and the piezoelectric element can be realized without depending on wire bonding, and the recording head can be reduced. The height reduction, area reduction, piezoelectric element pitch reduction, and nozzle opening density increase can be promoted. In addition, the number of parts can be reduced, and the assembly process can be simplified. Thereby, the cost of the ink jet recording head can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that, in each drawing described below, parts having the same configuration are denoted by the same reference numerals, and redundant description thereof is omitted.
FIG. 1 is a cross-sectional view illustrating a configuration example of an ink jet recording head 100 according to an embodiment of the present invention. FIG. 2 is a bottom view showing a configuration example of the ink jet recording head 100. As shown in FIGS. 1 and 2, the ink jet recording head 100 includes, for example, a flow path forming substrate 1 and a pressure generating chamber 3 formed on one surface (for example, the surface) of the flow path forming substrate 1. A nozzle opening 5 formed on the surface of the flow path forming substrate 1 and communicating with the pressure generating chamber 3, a vibrating film 7 formed on the surface side of the flow path forming substrate 1 and covering the pressure generating chamber 3, A driver circuit 9 formed in a region on the surface of the path forming substrate 1 and aligned with the pressure generation chamber 3, a piezoelectric element 10 disposed in a region facing the pressure generation chamber 3 with the vibration film 7 interposed therebetween, and a flow path The wiring layers 21, 23 and 25 arranged on the surface side of the formation substrate 1, the elastic film formation substrate 51 bonded to the surface side of the flow path formation substrate 1 with the vibration film 7 interposed therebetween, and the elastic film formation substrate 51 And a reservoir 30 that is formed and communicates with the pressure generating chamber 3.

Among these, the flow path forming substrate 1 is, for example, a bulk silicon substrate having a plane orientation (100). The flow path forming substrate 1 has a thickness of 50 μm to 500 μm, for example, and is formed with a plurality of individually divided pressure generating chambers 3 (also referred to as pressure chambers or ink cavities). . Ink liquid is supplied from the reservoir 30 to the pressure generating chamber 3. The depth of the pressure generation chamber 3 (that is, the distance from the surface of the flow path forming substrate 1 to the bottom surface of the pressure generation chamber 3) is, for example, about 10 μm to 50 μm.
The vibration film 7 is an elastic film and is disposed on the surface side of the flow path forming substrate 1 to cover the pressure generation chamber 3. The vibration film 7 is made of, for example, a silicon oxide (SiO ₂ ) film, a silicon nitride (Si ₃ N ₄ ) film, or a film in which these are laminated. The thickness of the vibration film 7 is, for example, about 100 nm to 10 μm. In FIG. 1, as an example of the vibration film 7, a film having a laminated structure including the first elastic film 6 and the second elastic film 8 is illustrated. The thickness of the first elastic film 6 is, for example, about 1 nm to 10 μm. The thickness of the second elastic film 8 is, for example, about 1 nm to 10 μm.

  The nozzle opening 5 is formed so as to penetrate the flow path forming substrate 1, and one end of the nozzle opening 5 opens on the other surface (for example, the back surface) of the flow path forming substrate 1. In the ink jet recording head 100, when the vibration film 7 vibrates in a state where the ink liquid is supplied to the pressure generation chamber 3, the pressure in the pressure generation chamber 3 changes and the pressure generation chamber 3 moves to the nozzle opening 5. Ink liquid is sent. Then, the sent ink liquid is discharged from the nozzle opening 5 to the outside (above the nozzle opening 5 in FIG. 1). The volume of the pressure generating chamber 3 that applies pressure to the ink liquid and the size of the nozzle opening 5 are optimized in accordance with the discharge amount of the ink liquid, the discharge speed, the discharge frequency, and the like.

The driver circuit 9 is a circuit for driving the piezoelectric element 10 and is an integrated circuit formed by a so-called CMOS process.
As shown in FIG. 3, the driver circuit 9 includes a plurality of switch elements 9a made of, for example, MOS transistors. These switch elements 9a correspond to the piezoelectric elements 10 for example 1: 1. The driver circuit 9 has a function of selectively applying a voltage to each piezoelectric element 10 by turning on and off the switch element 9a. That is, the driver circuit 9 can control ON / OFF of the voltage applied to each piezoelectric element 10, and thereby, each nozzle (that is, one pressure generating chamber 3 and a nozzle communicating with the nozzle) can be controlled. Whether or not the ink liquid is discharged can be controlled with respect to the opening 5). As shown in FIG. 1, the driver circuit 9 having such a control function is formed on the surface of the flow path forming substrate 1 and in an area adjacent to the pressure generating chamber 3 (that is, the pressure in a cross-sectional view). It is formed to be side by side with the generation chamber 3). A plurality of external connection terminals (that is, bump electrodes) 9b are formed on the active surface (that is, the circuit formation surface) of the driver circuit 9.

  The piezoelectric element 10 includes, for example, a lower electrode 11 in contact with the vibration film 7, a piezoelectric body 13 formed on the lower electrode 11, and an upper electrode 15 formed on the piezoelectric body 13. Here, the lower electrode 11 is, for example, a common electrode across a plurality of piezoelectric elements 10. The piezoelectric body 13 is a dielectric that expands, contracts, or is distorted when a voltage is applied, and is, for example, lead zirconate titanate (PZT). Further, the upper electrode 15 is not a common electrode, unlike the lower electrode 11, but is an individual electrode corresponding to each piezoelectric body 13 in a 1: 1 ratio. The piezoelectric element 10 having such a configuration is provided in a region facing each pressure generation chamber 3.

The wiring layer 25 connects the driver circuit 9 and the piezoelectric element 10. As shown in FIG. 1, one end of the wiring layer 25 is joined to the bump electrode 9 b included in the driver circuit 9, and the other end of the wiring layer 25 is connected to the upper electrode 15 of the piezoelectric element 10. As a result, a voltage can be applied from the driver circuit 9 to the piezoelectric element 10.
Also, the wiring layers 21 and 23 shown in FIG. 1 connect the driver circuit 9 and an integrated circuit on a main board (not shown). Here, the main board is a substrate other than the recording head 100 provided in the ink jet recording apparatus. On the main board, integrated circuits such as a drive waveform generator and a base driver are formed. These integrated circuits have a function of generating a signal (that is, a driving waveform) for driving the piezoelectric element 10 and amplifying the signal as necessary.

  The elastic film forming substrate 51 is made of, for example, a bulk silicon substrate having a plane orientation (100) or (111). As shown in FIGS. 1 and 2, the elastic film forming substrate 51 is formed with a reservoir 30 that receives supply of ink liquid from the outside. The reservoir 30 is formed of a through-hole formed from the front surface to the back surface of the elastic film forming substrate 51 and is formed to have a volume sufficiently larger than the volumes of all the pressure generating chambers 3 described above. The elastic film forming substrate 51 is also formed with an opening 33 for accommodating the piezoelectric element 10 described above. The opening 33 is formed from the front surface to the back surface of the elastic film forming substrate 51, and part or all of the bottom surface is the vibration film 7. The elastic film forming substrate 51 is used as a base for forming the elastic films 6 and 8 as the name indicates, and a specific example thereof will be described later.

  The ink jet recording head 100 having such a configuration takes ink liquid from an external ink supply unit (not shown) into the reservoir 30 and fills the area from the reservoir 30 to the nozzle opening 5 with the ink liquid. Then, the driver circuit 9 applies a voltage between the upper electrode 15 and the lower electrode 11 of the piezoelectric element 10 to expand and contract the piezoelectric body 13 or cause distortion. Thereby, the vibration film 7 is deformed to increase the pressure in the pressure generating chamber 3, and the ink liquid is discharged from the nozzle opening 5. Next, a method for manufacturing the ink jet recording head 100 will be described.

  4 to 20 are cross-sectional views illustrating a method of manufacturing the ink jet recording head 100 according to the embodiment of the present invention. This manufacturing method is roughly divided into a manufacturing process on the flow path forming substrate 1 side, a manufacturing process on the elastic film forming substrate 51 side, and a process of bonding and integrating these two substrates. Here, the manufacturing process on the flow path forming substrate 1 side will be described first with reference to FIGS. 4 to 8, and the manufacturing process on the elastic film forming substrate 51 side will be described with reference to FIGS. 9 to 13. . Then, the process etc. which adhere | attach and integrate the surfaces of both these board | substrates 1 and 51 are demonstrated, referring FIGS. 14-20.

First, in the manufacturing process on the flow path forming substrate 1 side, the driver circuit 9 is formed on the surface of the flow path forming substrate 1 as shown in FIG. The driver circuit 9 is formed by, for example, a normal CMOS process. Although not shown, the wiring formed inside the driver circuit 9 (that is, the internal wiring) is formed using a material having at least a melting point of 700 ° C. or more. For example, high melting point materials such as single metals such as tungsten (W), titanium (Ti), platinum (Pt), nickel (Ni), chromium (Cr), copper (Cu), and alloys and silicide metals using these metals Is used to form internal wiring. Thereby, melting of the internal wiring can be prevented in subsequent processes involving heat treatment (for example, a process of sintering the piezoelectric body 13 and the like).
Next, the insulating film 2 is formed on the surface of the flow path forming substrate 1 on which the driver circuit 9 is formed. The insulating film 2 is, for example, a SiO ₂ film or a Si ₃ N ₄ film, or a film in which these are laminated. The insulating film is formed by, for example, a CVD method or a coating method.

  Next, the insulating film is partially etched by photolithography and etching techniques to form a contact hole in which the pad electrode on the surface of the driver circuit 9 is exposed on the bottom surface. Then, a conductive film is formed on the surface of the flow path forming substrate 1 so as to fill this contact hole. Here, for the same reason as the internal wiring, the conductive film includes, for example, a single metal such as W, Ti, Pt, Ni, Cr, Cu, or a high melting point material such as an alloy or a silicide metal using the same. Is used. The high melting point material is formed by sputtering, for example. Subsequently, the conductive film is partially etched by photolithography and etching techniques to remove the conductive film from regions other than the contact holes. Thus, as shown in FIG. 5, bump electrodes 9b made of a conductive film are formed in the contact holes. The bump electrode 9b is connected to a pad electrode on the surface of the driver circuit 9, and the driver circuit 9 can send and receive signals through the bump electrode 9b.

Next, as shown in FIG. 6, the bonding insulating film 4 is formed on the surface side of the flow path forming substrate 1 on which the bump electrodes 9b are formed. The bonding insulating film 4 is, for example, a SiO ₂ film, and is formed by, for example, a CVD method or a coating method. The thickness of the bonding insulating film 4 is, for example, about 10 nm to 10 μm.
Next, the bonding insulating film 4 is partially etched by photolithography and etching techniques to form an opening 16 in which the surface of the bump electrode 9b is exposed on the bottom surface. Further, as shown in FIG. 7, the pressure generating chamber 3 is formed at the timing before and after the step of forming the opening 16. Here, the surface of the bonding insulating film 4 in the formation region of the pressure generating chamber 3, the insulating film 2, and the flow path forming substrate 1 is partially etched in order by photolithography and etching techniques, so that the pressure generating chamber 3 Form. Next, as shown in FIG. 8, the nozzle opening 5 is formed on the bottom surface of the pressure generating chamber 3 by photolithography and etching techniques. Here, the tip of the nozzle opening 5 (that is, the upper end in FIG. 8) is not allowed to reach the back surface side of the flow path forming substrate 1. Above, the process by the side of the flow path formation board | substrate 1 is complete | finished.

Next, in the manufacturing process on the elastic film forming substrate 51 side, the elastic film 6 is formed on the surface of the elastic film forming substrate 51 as shown in FIG. The elastic film 6 is made of, for example, a SiO ₂ film, a Si ₃ N ₄ film, or a film in which these are laminated. Here, a base film (for example, a Si ₃ N ₄ film) may be formed on the surface of the elastic film forming substrate 51, and the elastic film 6 may be formed on the base film.

Next, as shown in FIG. 10, a wiring layer 23 connected to the main board or the like is formed on the vibration film 7. Here, on the elastic film 6, for example, a film made of a single metal such as W, Ti, Pt, Ni, Cr, or Cu, an alloy using these, or a high melting point material such as a silicide metal is formed by sputtering. Next, this refractory material film is partially etched by photolithography and etching techniques. By such partial etching (that is, patterning), the wiring layer 23 made of a high melting point material is formed. Next, as shown in FIG. 11, an elastic film (hereinafter also referred to as a bonding insulating film) 8 is formed on the surface side of the elastic film forming substrate 51 on which the wiring layer 23 is formed. The bonding insulating film 8 is, for example, a SiO ₂ film, and is formed by, for example, a CVD method or a coating method. Here, the junction insulating film is formed thicker than the wiring layer 23. Further, as the material of the bonding insulating film 8, it is preferable to use the same material as that of the bonding insulating film 4 (see FIG. 6). For example, when the bonding insulating film 4 is a SiO ₂ film, it is preferable to form a SiO ₂ film as the bonding insulating film 8. Accordingly, the bonding insulating films 4 and 8 can be bonded with high adhesion in a later step. In this embodiment, the vibration film 7 is configured by the bonding insulating film (that is, the elastic film) 8 and the elastic film 6.

Next, as shown in FIG. 12, the surface of the bonding insulating film 8 is ground by, for example, CMP to expose the surface of the wiring layer 23 from below the bonding insulating film 8. Then, as shown in FIG. 13, the wiring layer 21 is formed at the end of the wiring layer 23 (that is, the position overlapping the pad electrode of the driver circuit 9). This completes the manufacturing process on the elastic film forming substrate 51 side.
Next, as shown in FIG. 14, the surface of the flow path forming substrate 1 and the surface of the elastic film forming substrate 51 are opposed to each other, and the flow path forming substrate 1 and the elastic film forming substrate 51 are bonded together in this state. Let That is, the surface of the flow path forming substrate 1 and the surface of the elastic film forming substrate 51 are joined. This bonding is performed, for example, by heating both substrates in a state where the surface of the bonding insulating film 4 and the surface of the bonding insulating film 8 are in contact with each other. When the junction insulating films 4 and 8 are both composed of SiO ₂ films, the heating temperature is, for example, 900 ° C. or higher. By the heat treatment at 900 ° C. or higher, the SiO ₂ film softens and adheres at the contact interface between the bonding insulating films 4 and 8. Thereby, a high bonding strength can be provided between the bonding insulating films 4 and 8. The atmosphere for heating may be in an atmosphere containing an oxidizing species such as oxygen (O ₂ ) or O ₂ + hydrogen (H ₂ ), or a non-existing atmosphere such as nitrogen (N ₂ ) or argon (Ar). It may be performed in an active gas atmosphere.

  Or you may perform said joining by normal temperature joining by the surface activation method. In the surface activation method, for example, the flow path forming substrate 1 and the elastic film forming substrate 51 are arranged in a chamber evacuated to a high vacuum, and the surface of each substrate is roughened by sputtering, for example, Ar on the surface of each substrate. Face. Then, the surfaces of both the substrates are bonded by bringing the roughened surfaces of both the substrates into contact in a chamber maintained at a high vacuum. This surface activation method has an advantage that no thermal history is added to the driver circuit 9 because both substrates can be bonded at room temperature.

  Next, as shown in FIG. 15, the elastic film forming substrate 51 is partially etched from the back surface side by photolithography and etching techniques to expose the back surface side of the vibration film 7. Thereby, an opening 33 having the vibration film 7 as a bottom surface is formed in the piezoelectric element forming region of the elastic film forming substrate 51. Further, the reservoir 30 is formed on the elastic film forming substrate 51 before, after, or in parallel with the step of forming the opening 33. That is, the elastic film forming substrate 51 is partially etched from the back side thereof by photolithography and etching techniques to form the reservoir 30 having a through-hole in the ink liquid supply region of the elastic film forming substrate 51. In the formation process of the reservoir 30, the ink supply region of the elastic film forming substrate 51 is completely penetrated to the pressure generation chamber 3.

In the step of forming the opening 33 and the step of forming the reservoir 30, the elastic film forming substrate 51 may be etched by dry etching or wet etching. When the elastic film forming substrate 51 is made of silicon, for example, the elastic film forming substrate 51 can be wet-etched using a potassium hydroxide (KOH) aqueous solution.
When etching the elastic film forming substrate 51 by wet etching, a bulk silicon substrate having a plane orientation (110) is suitable for the elastic film forming substrate 51. Further, when the elastic film forming substrate 51 is etched by dry etching, a bulk silicon substrate having a plane orientation (100) is suitable for the elastic film forming substrate 51.

  Next, as shown in FIG. 16, the vibration film 7 and the bonding insulating film 4 are sequentially and partially etched by photolithography and etching techniques to expose the surface of the bump electrode 9 b on the bottom surface. Form. In the subsequent steps, the piezoelectric element 10 is formed on the back surface side of the vibration film 7 (that is, the region facing the pressure generation chamber 3 with the vibration film 7 interposed) corresponding to each pressure generation chamber 3. .

  Specifically, as shown in FIG. 17, first, the lower electrode 11 and the wiring layer 25 are formed. Here, first, a lower electrode film is formed on the back surface side of the vibration film 7. The lower electrode film is formed by sputtering, for example. As a material for the lower electrode film, platinum (Pt), iridium (Ir), or the like is suitable. The reason is that a piezoelectric film described later formed by sputtering or sol-gel method needs to be crystallized by baking at a temperature of about 600 to 1000 ° C. in an air atmosphere or an oxygen atmosphere after the film formation. Because. For the material of the lower electrode film, it is necessary to select and use a material that can maintain conductivity under such high temperature and oxidizing atmosphere. In particular, when lead zirconate titanate (PZT) is used as the piezoelectric film, it is desirable to select and use a material that exhibits little change in conductivity due to diffusion of lead oxide. Pt, Ir, etc. are suitable as materials that satisfy such conditions. Next, the lower electrode film is partially etched by photolithography and etching techniques, and the lower electrode 11 having a shape as a common electrode is embedded in the opening 35 (see FIG. 16) and the bump electrode. And a wiring layer 25 connected to 9b. As shown in FIG. 17, the lower electrode 11 and the wiring layer 25 are separated from each other and are not connected. That is, the lower electrode 11 and the wiring layer 25 are electrically independent from each other.

  Next, as shown in FIG. 18, the piezoelectric body 13 is formed. Here, for example, a so-called sol in which a metal organic substance is dissolved and dispersed in a catalyst is applied, dried and gelled, and further sintered at a high temperature (that is, a sol-gel method) to form a piezoelectric film. As the material of the piezoelectric film, a PZT material is suitable, and the sintering temperature in that case is about 700 ° C., for example. The method for forming the piezoelectric film is not limited to the sol-gel method, and for example, the film may be formed by a spin coating method such as a sputtering method or a MOD method (organic metal thermal coating decomposition method). Alternatively, a PZT precursor film may be formed by a sol-gel method, a sputtering method, a MOD method, or the like, and then formed by a method of crystal growth at a low temperature by a high-pressure treatment method in an alkaline aqueous solution. The thickness of the piezoelectric film formed by such a method is, for example, 0.2 to 5 μm. Next, the piezoelectric film is partially etched by photolithography and etching techniques, leaving the piezoelectric film in the lower electrode 11 and its peripheral region (that is, the region where the piezoelectric member 13 is formed), and from other regions. Remove the body membrane. Thereby, the piezoelectric body 13 is formed.

Next, as shown in FIG. 19, the upper electrode 15 is formed. Here, first, an upper electrode film is formed. The upper electrode film only needs to be a highly conductive material, and a metal film such as Al, gold (Au), nickel (Ni), or Pt, or a conductive oxide can be used. Next, the upper electrode film is partially etched by photolithography and etching techniques to form the upper electrode 15 connected to the wiring layer 25. Thereby, the piezoelectric element 10 including the lower electrode 11, the piezoelectric body 13, and the upper electrode 15 is completed in a region facing the pressure generating chamber 3 with the vibration film 7 interposed therebetween.
In the present embodiment, the lower electrode 11 is a common electrode of the piezoelectric element 10 and the upper electrode 15 is an individual electrode of the piezoelectric element 10, but this may be reversed for the convenience of the driver circuit 9 and wiring. That is, the lower electrode 11 may be an individual electrode and the upper electrode 15 may be a common electrode. In that case, the lower electrode film and the upper electrode film may be patterned so that the wiring layer 25 is connected to the lower electrode 11 and not to the upper electrode 15.

Thereafter, as shown in FIG. 20, the entire back surface of the flow path forming substrate 1 is ground, for example, several hundred μm, and the tip of the nozzle opening 5 is opened. Through the steps as described above, the ink jet recording head 100 shown in FIG. 1 is completed.
Thus, according to the embodiment of the present invention, the driver circuit 9 and the piezoelectric element 10 can be connected without depending on wire bonding. As a result, the space required for connecting the driver circuit 9 and the piezoelectric element 10 on the surface side of the flow path forming substrate is reduced, so that the recording head is reduced in height and area, and the piezoelectric element is narrow in pitch. And higher density of nozzle openings can be developed.

  For example, in the connection by wire bonding, it is necessary to keep the wires at least 50 μm apart (that is, the interval between the wires is 50 μm or more). Therefore, the density of the nozzle openings 5 is 360 dpi (dot per inch). Higher density than the number of nozzles per inch) was difficult. On the other hand, according to the embodiment of the present invention, the interval between the wiring layers 21, 23, and 25 can be 50 μm or less, so that the pitch of the piezoelectric elements 10 can be reduced and the density of the nozzle openings 5 can be increased. Therefore, it is possible to easily achieve a high density of 360 dpi or more with respect to the density of the nozzle openings 5. Moreover, since the opening 35 reaching the surface of the bump electrode 9b is formed by etching the bonding insulating film 4 or the vibration film 7 having a thickness of about several hundred nm to several μm, the pitch can be reduced. It is.

Furthermore, since the driver circuit 9, the pressure generating chamber 3, and the nozzle opening 5 are all formed in the flow path forming substrate 1, the number of components can be reduced. As a result, the assembly process can be simplified, and the cost of the ink jet recording head can be reduced.
Further, according to the ink jet recording apparatus provided with the ink jet recording head 100, the ink jet recording apparatus can be reduced in size and cost.
In this embodiment, the flow path forming substrate 1 corresponds to the “first substrate” of the present invention, and the back surface of the flow path forming substrate 1 corresponds to “one surface of the first substrate” of the present invention. The surface of the substrate 1 corresponds to “the other surface of the first substrate” of the present invention. Further, the driver circuit 9 corresponds to the “integrated circuit” of the present invention, and the vibration film including the first elastic film 6 and the second elastic film (that is, the bonding insulating film) 8 is the “vibration film” of the present invention. Is supported. Further, the elastic film forming substrate 51 corresponds to the “second substrate” of the present invention, and the bonding insulating films 4 and 8 correspond to the “bonding layer” of the present invention.

FIG. 3 is a cross-sectional view illustrating a configuration example of the ink jet recording head 100 according to the embodiment. FIG. 2 is a bottom view illustrating a configuration example of an ink jet recording head 100 according to an embodiment. The figure which shows an example of the function of the driver circuit. FIG. 2 is a diagram illustrating a method for manufacturing an ink jet recording head 100 (part 1). FIG. 2 is a diagram illustrating a method for manufacturing the ink jet recording head 100 (part 2). FIG. 3 is a diagram illustrating a method for manufacturing the ink jet recording head 100 (No. 3). FIG. 4 illustrates a method for manufacturing the ink jet recording head 100 (No. 4). FIG. 5 illustrates a method for manufacturing the ink jet recording head 100 (part 5). FIG. 6 illustrates a method for manufacturing the ink jet recording head 100 (No. 6). FIG. 7 illustrates a method for manufacturing the ink jet recording head 100 (No. 7). FIG. 8 shows a method for manufacturing the ink jet recording head 100 (No. 8). FIG. 9 shows a method for manufacturing the ink jet recording head 100 (No. 9). FIG. 10 shows a method for manufacturing the ink jet recording head 100 (No. 10). FIG. 11 shows a method for manufacturing the ink jet recording head 100 (No. 11). FIG. 12 shows a method for manufacturing the ink jet recording head 100 (No. 12). FIG. 13 shows a method for manufacturing the ink jet recording head 100 (No. 13). FIG. 14 shows a method for manufacturing the ink jet recording head 100 (No. 14). FIG. 15 is a view showing a method for manufacturing the ink jet recording head 100 (No. 15). FIG. 16 is a diagram illustrating a method for manufacturing the ink jet recording head 100 (No. 16). FIG. 17 is a view showing a method for manufacturing the ink jet recording head 100 (No. 17).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Substrate, 2 Insulating film, 3 Pressure generating chamber, 4 Bonding insulating film, 5 Nozzle opening, 6 Elastic film, 7 Vibration film, 8 Elastic film (bonding insulating film), 9 Driver circuit, 9a Switch element, 9b Bump electrode DESCRIPTION OF SYMBOLS 10 Piezoelectric element, 11 Lower electrode, 13 Piezoelectric body, 15 Upper electrode, 16, 33, 35 Opening part, 21, 23, 25 Wiring layer, 30 Reservoir, 51 Flow path formation board, 100 Inkjet recording head

Claims (9)

A first substrate;
A pressure generating chamber formed on one surface of the first substrate;
A nozzle opening formed in the first substrate and communicating with the pressure generating chamber;
A vibrating membrane formed on one side of the first substrate and covering the pressure generating chamber;
A piezoelectric element formed in a region facing the pressure generation chamber across the vibration film;
An integrated circuit formed in a region on one side of the first substrate and aligned with the pressure generation chamber;
An ink jet recording head comprising: a wiring layer formed on one surface side of the first substrate and connecting the integrated circuit and the piezoelectric element. A second substrate bonded to one surface side of the first substrate across the vibration film;
The ink jet recording head according to claim 1, further comprising a reservoir formed on the second substrate and communicating with the pressure generating chamber. An opening formed in the second substrate,
The opening has the vibrating membrane as a bottom surface,
The ink jet recording head according to claim 2, wherein the piezoelectric element is disposed in the opening having the vibration film as a bottom surface.   4. The ink jet recording head according to claim 1, wherein the nozzle opening opens on the other surface of the first substrate. 5. A bonding layer for bonding the first substrate and the second substrate;
Each of the first substrate and the second substrate is made of silicon,
The inkjet recording head according to claim 2, wherein the bonding layer is made of a silicon oxide film.   6. The ink jet recording head according to claim 1, wherein the wiring layer is made of a refractory metal.   An ink jet recording apparatus comprising the ink jet recording head according to any one of claims 1 to 6. Forming a pressure generating chamber on one surface of the first substrate;
Forming a nozzle opening in the first substrate in communication with the pressure generating chamber;
Forming an integrated circuit in a region on one side of the first substrate along with the pressure generating chamber;
Forming a vibration film covering the pressure generating chamber on one surface side of the first substrate;
Forming a piezoelectric element in a region facing the pressure generating chamber across the vibration film;
Forming a wiring layer for connecting the integrated circuit and the piezoelectric element on one side of the first substrate. A method for manufacturing an ink jet recording head, comprising: The step of forming the vibration film includes:
Forming a vibration film on one surface of the second substrate;
The method of manufacturing an ink jet recording head according to claim 8, further comprising: bonding one surface of the second substrate on which the vibration film is formed to one surface side of the first substrate. Method.

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