JP2018024227A - Inkjet print head and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet print head which can improve the joint strength between an actuator substrate and a nozzle substrate.SOLUTION: An inkjet print head 1 includes: an actuator substrate 2 having an ink passage 5 including a pressure chamber 7; a movable film forming layer 10 disposed on the pressure chamber 7 and including a movable film 10A which divides a top surface part of the pressure chamber 7; a piezoelectric element 9 formed on the movable film 10A; and a nozzle substrate 3 joined to a second surface 2b opposite to a first surface 2a that is a movable film 10A side surface of the actuator substrate 2 by an adhesive, dividing a bottom surface part of the pressure chamber 7, and having a nozzle hole 20 communicating with the pressure chamber 7. First joint pressure increase recessed parts 61 are formed at a periphery part of the second surface 2b of the actuator substrate 2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an ink jet print head and a method for manufacturing the same.

  Patent Document 1 discloses an ink jet print head. The ink jet print head of Patent Document 1 is provided with an actuator substrate (substrate) having a pressure chamber (pressure generation chamber) as an ink flow path, a movable film (elastic film) formed on the actuator substrate, and the movable film. Piezoelectric element. The ink jet print head disclosed in Patent Document 1 further includes a nozzle substrate (nozzle plate) bonded to the lower surface of the actuator substrate and having a nozzle opening communicating with the pressure chamber, and a protective substrate bonded to the upper surface of the actuator substrate and covering the piezoelectric element. And.

  An individual ink supply path communicating with the pressure chamber and a common ink supply path (communication portion) communicating with the individual ink supply path are formed on the actuator substrate. That is, the actuator substrate is formed with an ink flow path including a common ink supply path, an individual ink supply path, and a pressure chamber. An accommodation recess (piezoelectric element holding portion) for accommodating a piezoelectric element is formed on the lower surface of the protective substrate. In addition, the protective substrate is formed with an ink supply path (reservoir portion) communicating with the common ink supply path of the actuator substrate at a distance from the housing recess in plan view. Ink is supplied from the ink tank to the pressure chamber through the ink supply path of the protective substrate, the common ink supply path of the actuator substrate, and the individual ink supply path.

JP2015-91668A

In an ink jet print head as described in Patent Document 1, generally, a nozzle substrate is bonded to an actuator substrate with an adhesive. At this time, the nozzle substrate is bonded to the actuator substrate while being pressed against the actuator substrate. However, if the bonding pressure between the two is weak, the bonding strength between the two is reduced.
In an ink jet print head as described in Patent Document 1, generally, a protective substrate is bonded to an actuator substrate with an adhesive. At this time, the protective substrate is bonded to the actuator substrate while being pressed against the actuator substrate. However, if the bonding pressure between the two is weak, the bonding strength between the two decreases.

An object of the present invention is to provide an ink jet print head and a method for manufacturing the same, which can increase the bonding strength between an actuator substrate and a nozzle substrate.
An object of the present invention is to provide an ink jet print head that can increase the bonding strength between an actuator substrate and a protective substrate.

  An ink jet print head according to the present invention includes an actuator substrate having an ink flow path including a pressure chamber, a movable film forming layer including a movable film disposed on the pressure chamber and defining a top surface portion of the pressure chamber, and the movable A piezoelectric element formed on the film and bonded to the second surface opposite to the first surface, which is the surface of the actuator substrate on the movable film side, by an adhesive, and defines a bottom surface portion of the pressure chamber; And a nozzle substrate having a nozzle hole communicating with the pressure chamber. A bonding pressure increasing recess is formed at the peripheral edge of the second surface of the actuator substrate.

In this configuration, since the concave portion for increasing the bonding pressure is formed in the peripheral portion of the second surface of the actuator substrate, the bonding pressure between the two is increased when the nozzle substrate is bonded to the second surface of the actuator substrate. Can do. Thereby, the joint strength between the actuator substrate and the nozzle substrate can be increased.
In one embodiment of the present invention, the bonding pressure increasing recess includes a plurality of bonding pressure increasing recesses formed so as to be scattered in a peripheral portion of the second surface of the actuator substrate.

In one embodiment of the present invention, the bonding pressure increasing recesses are formed in a quadrangular shape in plan view, and a plurality of quadrangular bonding pressure increasing recesses are arranged in a matrix with gaps therebetween.
In one embodiment of the present invention, the bonding pressure increasing recesses are formed in a regular hexagonal shape in plan view, and a plurality of regular hexagonal bonding pressure increasing recesses are arranged in a honeycomb shape.
In one embodiment of the present invention, the semiconductor device further includes a protective substrate bonded to the actuator substrate with an adhesive so as to cover the piezoelectric element. The protective substrate is formed toward the actuator substrate side and is formed outside a housing recess that houses the piezoelectric element and one end of the housing recess in plan view, and is formed at one end of the ink flow path. And an ink supply path communicating therewith.

In one embodiment of the present invention, the nozzle substrate includes a main substrate made of a Si substrate, a SiO ₂ film formed on the main substrate, and a water repellent film formed on the SiO ₂ film. A surface of the main substrate opposite to the SiO ₂ film is bonded to the second surface of the actuator substrate.
In one embodiment of the present invention, the actuator substrate comprises a Si substrate.

In one embodiment of the present invention, the movable film forming layer is made of a single SiO ₂ film.
In one embodiment of the present invention, the movable film forming layer includes an Si film formed on the actuator substrate, an SiO ₂ film formed on the Si film, and an SiN film formed on the SiO ₂ film. And a laminated film.
In one embodiment of the present invention, the piezoelectric element includes a lower electrode formed on the movable film, a piezoelectric film formed on the lower electrode, and an upper electrode formed on the piezoelectric film. including.

In one embodiment of the present invention, the upper electrode has a peripheral edge recessed inward of the pressure chamber from the movable film in a plan view, and one end portion is an upper surface of the upper electrode in the plan view. The upper wiring further includes an upper wiring that is connected to the other end of the pressure chamber and is extended outside the periphery of the pressure chamber.
In one embodiment of the present invention, a hydrogen barrier film covering at least the entire side surface of the upper electrode and the piezoelectric film and an upper surface of the lower electrode, and formed on the hydrogen barrier film, the hydrogen barrier film and the And an insulating film disposed between the upper wiring and the upper wiring. A contact hole for exposing a part of the upper electrode is formed in the hydrogen barrier film and the insulating film, and one end of the upper wiring is connected to the upper electrode through the contact hole.

In one embodiment of the present invention, the semiconductor device further includes a passivation film formed on the insulating film and covering the wiring.
In one embodiment of the present invention, the piezoelectric film is a PZT film.
In one embodiment of the present invention, the upper electrode is made of a single Pt film.
In one embodiment of the present invention, the upper electrode is formed of the piezoelectric body and Ir0 ₂ film formed on the film, laminated film of Ir film formed on the Ir0 ₂ film.

In one embodiment of the present invention, the lower electrode is a laminated film of a Ti film formed on the movable film side and a Pt film formed on the Ti film.
An inkjet printhead manufacturing method according to the present invention includes a step of forming a movable film forming layer including a movable film forming region on an actuator substrate, a lower electrode on the movable film forming region of the movable film forming layer, Forming a piezoelectric element including an upper electrode disposed on a side opposite to the movable film forming layer with respect to the lower electrode, and a piezoelectric film sandwiched between the upper electrode, and the actuator so as to cover the piezoelectric element A step of bonding a protective substrate to the substrate, and a step of forming a concave for increasing the bonding pressure on the peripheral portion of the second surface opposite to the first surface, which is the surface on the movable film forming layer side of the actuator substrate, Etching the actuator substrate from the second surface side to form an ink flow path including a pressure chamber facing the movable film forming region; and The second surface of the chromatography data substrate, defines a bottom portion of the pressure chamber, and a step of bonding a nozzle substrate having a nozzle hole communicating with the pressure chamber.

In this method, since the concave portion for increasing the bonding pressure is formed on the peripheral portion of the second surface of the actuator substrate, the bonding pressure between the two can be increased when the nozzle substrate is bonded to the second surface of the actuator substrate. it can. Thereby, the joint strength between the actuator substrate and the nozzle substrate can be increased.
In one embodiment of the present invention, in the step of forming the bonding pressure increasing recesses, a plurality of bonding pressure increasing recesses are formed at the periphery of the second surface of the actuator substrate.

  A second ink jet print head according to the present invention includes an actuator substrate having an ink flow path including a pressure chamber, a movable film forming layer including a movable film disposed on the pressure chamber and defining a top surface portion of the pressure chamber. A piezoelectric element formed on the movable film, and a protective substrate bonded to the actuator substrate with an adhesive so as to cover the piezoelectric element, and a peripheral edge of a surface facing the actuator substrate in the protective substrate A recess for increasing the bonding pressure is formed in the portion.

In this configuration, since the concave portion for increasing the bonding pressure is formed at the peripheral portion of the protective substrate facing the actuator substrate, the bonding pressure between the two is increased when the protective substrate is bonded to the actuator substrate. Can do. Thereby, the joint strength between the actuator substrate and the protective substrate can be increased.
In one embodiment of the present invention, the junction pressure increasing recesses include a plurality of junction pressure increasing recesses formed so as to be scattered on the peripheral edge portion of the facing surface of the protective substrate facing the actuator substrate.

In one embodiment of the present invention, the bonding pressure increasing recesses are formed in a quadrangular shape in plan view, and a plurality of quadrangular bonding pressure increasing recesses are arranged in a matrix with gaps therebetween.
In one embodiment of the present invention, the bonding pressure increasing recesses are formed in a regular hexagonal shape in plan view, and a plurality of regular hexagonal bonding pressure increasing recesses are arranged in a honeycomb shape.
In one embodiment of the present invention, the protective substrate is formed toward the actuator substrate side and is formed outside the housing recess that houses the piezoelectric element, and at one end of the housing recess in plan view. An ink supply path communicating with one end of the ink flow path.

  In an embodiment of the present invention, the actuator substrate is bonded to the second surface opposite to the first surface, which is the surface on the movable film side, of the actuator substrate by an adhesive, and defines a bottom surface portion of the pressure chamber. It further includes a nozzle substrate having a nozzle hole communicating with the chamber.

FIG. 1 is an illustrative plan view for explaining the configuration of an ink jet print head according to an embodiment of the present invention. FIG. 2 is a bottom view showing the back surface of the actuator substrate. FIG. 3 is a bottom view showing the back surface of the protective substrate. FIG. 4 is an illustrative partial enlarged plan view showing a portion A of FIG. 1 in an enlarged manner, and is a plan view including a protective substrate. FIG. 5 is an illustrative partial enlarged plan view showing an enlarged portion A of FIG. 1 and is a plan view in which a protective substrate is omitted. 6 is a schematic cross-sectional view taken along line VI-VI in FIG. FIG. 7 is a schematic sectional view taken along line VII-VII in FIG. FIG. 8 is a schematic plan view showing a pattern example of the insulating film of the ink jet print head. FIG. 9 is a schematic plan view showing a pattern example of a passivation film of the ink jet print head. FIG. 10 is a bottom view of the region shown in FIG. 4 of the protective substrate. FIG. 11 is a plan view of a semiconductor wafer as an original substrate of the actuator substrate. FIG. 12A is a cross-sectional view illustrating an example of the manufacturing process of the inkjet print head. FIG. 12B is a cross-sectional view showing a step subsequent to FIG. 12A. FIG. 12C is a cross-sectional view showing a step subsequent to FIG. 12B. FIG. 12D is a cross-sectional view showing a step subsequent to FIG. 12C. FIG. 12E is a cross-sectional view showing a step subsequent to FIG. 12D. FIG. 12F is a cross-sectional view showing a step subsequent to FIG. 12E. FIG. 12G is a cross-sectional view showing a step subsequent to FIG. 12F. FIG. 12H is a cross-sectional view showing a step subsequent to FIG. 12G. FIG. 12I is a cross-sectional view showing a step subsequent to FIG. 12H. FIG. 12J is a cross-sectional view showing a step subsequent to FIG. 12I. FIG. 12K is a cross-sectional view showing a step subsequent to FIG. 12J. FIG. 12L is a cross-sectional view showing a step subsequent to FIG. 12K. 12M is a cross-sectional view showing a step subsequent to FIG. 12L. 12N is a cross-sectional view showing a step subsequent to FIG. 12M. FIG. 13A is a cross-sectional view schematically showing a manufacturing process of the nozzle substrate assembly, and is a cross-sectional view taken along a cutting line that is orthogonal to the ink flow direction and passes through the center of the nozzle hole. FIG. 13B is a cross-sectional view showing a step subsequent to FIG. 13A. FIG. 13C is a cross-sectional view showing a step subsequent to FIG. 13B. FIG. 13D is a cross-sectional view showing a step subsequent to FIG. 13C. FIG. 13E is a cross-sectional view showing a step subsequent to FIG. 13D. FIG. 13F is a cross-sectional view showing a step subsequent to FIG. 13E. FIG. 14A is a schematic cross-sectional view for explaining a process of joining the nozzle substrate assembly to the substrate assembly assembly, and shows a cutting line orthogonal to the ink flow direction and passing through the center of the nozzle hole. FIG. FIG. 14B is a cross-sectional view showing a step subsequent to FIG. 14A. FIG. 14C is a cross-sectional view showing a step subsequent to FIG. 14B. FIG. 15A is an illustrative sectional view showing a modified example of the nozzle hole. FIG. 15B is an illustrative sectional view showing another modified example of the nozzle hole. FIG. 15C is an illustrative sectional view showing still another modified example of the nozzle hole. FIG. 16 is a partially enlarged bottom view showing a modified example of the first bonding pressure increasing recess. FIG. 17 is a partially enlarged bottom view showing a modification of the second bonding pressure increasing recess.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an illustrative plan view for explaining the configuration of an ink jet print head according to an embodiment of the present invention. FIG. 2 is a bottom view showing the back surface of the actuator substrate. FIG. 3 is a bottom view showing the back surface of the protective substrate. FIG. 4 is an illustrative partial enlarged plan view showing a portion A of FIG. 1 in an enlarged manner, and is a plan view including a protective substrate. FIG. 5 is an illustrative partial enlarged plan view showing an enlarged portion A of FIG. 1 and is a plan view in which a protective substrate is omitted. 6 is a schematic cross-sectional view taken along line VI-VI in FIG. FIG. 7 is a schematic sectional view taken along line VII-VII in FIG.

With reference to FIG. 6, the structure of the inkjet print head 1 is demonstrated roughly.
The ink jet print head 1 includes an actuator substrate assembly SA including an actuator substrate 2 and a piezoelectric element 9, a nozzle substrate 3, and a protective substrate 4. Hereinafter, the actuator substrate assembly SA is referred to as a substrate assembly SA.

A movable film forming layer 10 is laminated on the surface 2 a of the actuator substrate 2. An ink flow path (ink reservoir) 5 is formed on the actuator substrate 2. In this embodiment, the ink flow path 5 is formed through the actuator substrate 2. The ink flow path 5 is formed to be elongated along the ink flow direction 41 indicated by an arrow in FIG. The ink flow path 5 includes an ink inflow portion 6 at an upstream end portion (left end portion in FIG. 6) in the ink circulation direction 41 and a pressure chamber 7 communicating with the ink inflow portion 6. In FIG. 6, the boundary between the ink inflow portion 6 and the pressure chamber 7 is indicated by a two-dot chain line. A plurality of first bonding pressure increasing recesses 61 are formed on the peripheral edge of the back surface 2 b of the actuator substrate 2. The nozzle substrate 3 includes, for example, a silicon (Si) substrate (main substrate) 30, a silicon oxide (SiO ₂ ) film 31 formed on the surface (back surface) of the silicon substrate 30 opposite to the pressure chamber 7, and an oxidation substrate It consists of a water repellent film 32 formed on the surface of the silicon film 31 opposite to the silicon substrate 30. In this embodiment, the water repellent film 32 is made of an organic film such as a fluorine-based polymer. In this embodiment, the thickness of the silicon substrate 30 is about 40 μm, the thickness of the silicon oxide film 31 is about 0.1 μm, and the thickness of the water repellent film 32 is about 0.1 μm.

  The nozzle substrate 3 is bonded to the back surface 2 b of the actuator substrate 2 with the surface on the silicon substrate 30 side facing the back surface 2 b of the actuator substrate 2. The nozzle substrate 3 partitions the ink flow path 5 together with the actuator substrate 2 and the movable film forming layer 10. More specifically, the nozzle substrate 3 defines the bottom surface of the ink flow path 5. The first bonding pressure increasing recess 61 is formed to increase the bonding pressure between the two when the nozzle substrate 3 is bonded to the actuator substrate 2.

  Nozzle holes 20 are formed in the nozzle substrate 3. The nozzle hole 20 includes a recess 20a facing the pressure chamber 7 and an ink discharge passage 20b formed on the bottom surface of the recess 20a. The ink discharge passage 20 b passes through the bottom wall of the recess 20 a and has an ink discharge port 20 c on the side opposite to the pressure chamber 7. Therefore, when the volume change of the pressure chamber 7 occurs, the ink stored in the pressure chamber 7 passes through the ink discharge passage 20b and is discharged from the discharge port 20c.

  In this embodiment, the concave portion 20a is formed in a truncated cone shape whose cross section gradually decreases from the surface of the silicon substrate 30 toward the silicon oxide film 31 side. The ink discharge passage 20b is constituted by a straight hole having a circular cross section. In this embodiment, the recess 20a is formed partway through the thickness of the silicon substrate 30, and the ink discharge passage 20b is formed in the portion formed in the silicon substrate 30, the silicon oxide film 31 and the water repellent film 32. It consists of the part which was made.

The top wall portion of the pressure chamber 7 in the movable film forming layer 10 constitutes the movable film 10A. The movable film 10A (movable film forming layer 10) is made of, for example, a silicon oxide (SiO ₂ ) film formed on the actuator substrate 2. The movable film 10A (movable film forming layer 10) includes, for example, a silicon (Si) film formed on the actuator substrate 2, a silicon oxide (SiO ₂ ) film formed on the silicon film, and a silicon oxide film. You may be comprised from the laminated film with the silicon nitride (SiN) film | membrane formed. In this specification, the movable film 10 </ b> A means a top wall portion that partitions the top surface portion of the pressure chamber 7 in the movable film forming layer 10. Therefore, portions of the movable film forming layer 10 other than the top wall portion of the pressure chamber 7 do not constitute the movable film 10A.

  The thickness of the movable film 10A is, for example, 0.4 μm to 2 μm. When the movable film 10A is made of a silicon oxide film, the thickness of the silicon oxide film may be about 1.2 μm. When the movable film 10A is composed of a laminated film of a silicon film, a silicon oxide film, and a silicon nitride film, the thicknesses of the silicon film, the silicon oxide film, and the silicon nitride film are about 0.4 μm, respectively. Also good.

The pressure chamber 7 is partitioned by the movable film 10A, the actuator substrate 2, and the nozzle substrate 3, and in this embodiment, is formed in a substantially rectangular parallelepiped shape. For example, the pressure chamber 7 may have a length of about 800 μm and a width of about 55 μm. The ink inflow portion 6 communicates with one end portion in the longitudinal direction of the pressure chamber 7.
A metal barrier film 8 is formed on the surface of the movable film forming layer 10. The metal barrier film 8 is made of, for example, Al ₂ O ₃ (alumina). The thickness of the metal barrier film 8 is about 50 nm to 100 nm. On the surface of the metal barrier film 8, a piezoelectric element 9 is disposed above the movable film 10A. The piezoelectric element 9 includes a lower electrode 11 formed on the metal barrier film 8, a piezoelectric film 12 formed on the lower electrode 11, and an upper electrode 13 formed on the piezoelectric film 12. . In other words, the piezoelectric element 9 is configured by sandwiching the piezoelectric film 12 from above and below by the upper electrode 13 and the lower electrode 11.

The upper electrode 13 may be a single film of platinum (Pt), for example, a conductive oxide film (for example, IrO ₂ (iridium oxide) film) and a metal film (for example, Ir (iridium) film) are laminated. You may have the laminated structure made. The thickness of the upper electrode 13 may be, for example, about 0.2 μm.
As the piezoelectric film 12, for example, a PZT (PbZr _x Ti _1-x O ₃ : lead zirconate titanate) film formed by a sol-gel method or a sputtering method can be applied. Such a piezoelectric film 12 is made of a sintered body of metal oxide crystals. The piezoelectric film 12 is formed in the same shape as the upper electrode 13 in plan view. The thickness of the piezoelectric film 12 is about 1 μm. The total thickness of the movable film 10 </ b> A is preferably about the same as the thickness of the piezoelectric film 12 or about 2/3 of the thickness of the piezoelectric film 12. The above-described metal barrier film 8 mainly prevents the metal element (Pb, Zr, Ti when the piezoelectric film 12 is PZT) from escaping from the piezoelectric film 12, and the piezoelectric characteristics of the piezoelectric film 12 are good. And prevents the metal from diffusing into the movable film 10A when the piezoelectric film 12 is formed. The metal barrier film 8 also has a function of preventing characteristic deterioration due to hydrogen reduction of the piezoelectric film 12.

  The lower electrode 11 has, for example, a two-layer structure in which a Ti (titanium) film and a Pt (platinum) film are sequentially stacked from the metal barrier film 8 side. In addition, the lower electrode 11 can be formed of a single film such as an Au (gold) film, a Cr (chromium) layer, or a Ni (nickel) layer. The lower electrode 11 has a main electrode portion 11A that is in contact with the lower surface of the piezoelectric film 12 and an extension portion 11B that extends to a region outside the piezoelectric film 12. The thickness of the lower electrode 11 may be about 0.2 μm, for example.

A hydrogen barrier film 14 is formed on the piezoelectric element 9, the extension 11 </ b> B of the lower electrode 11, and the metal barrier film 8. The hydrogen barrier film 14 is made of, for example, Al ₂ O ₃ (alumina). The thickness of the hydrogen barrier film 14 is about 50 nm to 100 nm. The hydrogen barrier film 14 is provided in order to prevent characteristic deterioration due to hydrogen reduction of the piezoelectric film 12.
An insulating film 15 is stacked on the hydrogen barrier film 14. The insulating film 15 is made of, for example, SiO ₂ , low hydrogen SiN, or the like. The insulating film 15 has a thickness of about 500 nm. On the insulating film 15, an upper wiring 17 and a lower wiring (not shown) are formed. These wirings may be made of a metal material containing Al (aluminum). The thickness of these wirings is, for example, about 1000 nm (1 μm).

  One end of the upper wiring 17 is disposed above one end of the upper electrode 13 (downstream end in the ink flow direction 41). Between the upper wiring 17 and the upper electrode 13, an upper electrode contact hole 33 that continuously penetrates the hydrogen barrier film 14 and the insulating film 15 is formed. One end of the upper wiring 17 enters the upper electrode contact hole 33 and is connected to the upper electrode 13 in the upper electrode contact hole 33. The upper wiring 17 extends outward from the pressure chamber 7 across the outer edge of the pressure chamber 7 from above the upper electrode 13.

  Although not shown, the lower wiring is disposed above the extension portion 11B of the lower electrode 11 at a predetermined position. A lower electrode contact hole (not shown) that continuously penetrates the hydrogen barrier film 14 and the insulating film 15 is formed between the lower wiring and the extended portion 11B of the lower electrode 11. The lower wiring enters the lower electrode contact hole and is connected to the extension portion 11B of the lower electrode 11 in the lower electrode contact hole.

On the insulating film 15, a passivation film 21 that covers the upper wiring 17, the lower wiring, and the insulating film 15 is formed. The passivation film 21 is made of, for example, SiN (silicon nitride). The thickness of the passivation film 21 may be about 800 nm, for example.
An upper electrode pad opening 35 is formed in the passivation film 21 to expose a part of the upper wiring 17. The upper electrode pad opening 35 is formed in the outer region of the pressure chamber 7, and is formed, for example, at the tip of the upper wiring 17 (the end opposite to the contact with the upper electrode 13). An upper electrode pad 42 that covers the upper electrode pad opening 35 is formed on the passivation film 21. The upper electrode pad 42 enters the upper electrode pad opening 35 and is connected to the upper wiring 17 in the upper electrode pad opening 35.

  The passivation film 21 has a lower electrode pad opening (not shown) for exposing a part of the lower wiring. A lower electrode pad 43 (see FIG. 1) is formed on the passivation film 21 to cover the lower electrode pad opening. The lower electrode pad 43 enters the lower electrode pad opening and is connected to the lower wiring within the lower electrode pad opening.

  Ink that penetrates the passivation film 21, the insulating film 15, the hydrogen barrier film 14, the lower electrode 11, the metal barrier film 8, and the movable film forming layer 10 at a position corresponding to the end of the ink flow path 5 on the ink inflow portion 6 side. A supply through hole 22 is formed. The lower electrode 11 includes an ink supply through hole 22, and a through hole 23 larger than the ink supply through hole 22 is formed. The hydrogen barrier film 14 enters the gap between the through hole 23 of the lower electrode 11 and the ink supply through hole 22. The ink supply through hole 22 communicates with the ink inflow portion 6.

  The protective substrate 4 is made of, for example, a silicon substrate. The protective substrate 4 is disposed on the substrate assembly SA so as to cover the piezoelectric element 9. The protective substrate 4 is bonded to the substrate assembly SA via an adhesive 50. The protective substrate 4 has an accommodation recess 52 in the facing surface 51 facing the substrate assembly SA. The piezoelectric element 9 is housed in the housing recess 52. The protective substrate 4 is formed with an ink supply path 53 communicating with the ink supply through hole 22 and an opening 54 for exposing the pads 42 and 43. The ink supply path 53 and the opening 54 penetrate the protective substrate 4. A plurality of second bonding pressure increasing recesses 62 are formed on the periphery of the facing surface 51 of the protective substrate 4 facing the substrate assembly SA. The second bonding pressure increasing recess 62 is formed to increase the bonding pressure between the two when the protective substrate 4 is bonded to the actuator substrate 2. An ink tank (not shown) that stores ink is disposed on the protective substrate 4.

  The piezoelectric element 9 is formed at a position facing the pressure chamber 7 with the movable film 10A and the metal barrier film 8 interposed therebetween. That is, the piezoelectric element 9 is formed in contact with the surface of the metal barrier film 8 opposite to the pressure chamber 7. By supplying ink from the ink tank to the pressure chamber 7 through the ink supply path 53, the ink supply through hole 22, and the ink inflow portion 6, the pressure chamber 7 is filled with ink. The movable film 10 </ b> A partitions the top surface portion of the pressure chamber 7 and faces the pressure chamber 7. The movable film 10A is supported by a portion around the pressure chamber 7 in the actuator substrate 2, and has flexibility capable of being deformed in a direction facing the pressure chamber 7 (in other words, the thickness direction of the movable film 10A). doing.

  The upper wiring 17 and the lower wiring are connected to a drive circuit (not shown). Specifically, the upper electrode pad 42 and the drive circuit are connected via a connection metal member (not shown). The lower electrode pad 43 and the drive circuit are connected via a connection metal member (not shown). When a drive voltage is applied to the piezoelectric element 9 from the drive circuit, the piezoelectric film 12 is deformed by the inverse piezoelectric effect. As a result, the movable film 10A is deformed together with the piezoelectric element 9, whereby the volume of the pressure chamber 7 is changed, and the ink in the pressure chamber 7 is pressurized. The pressurized ink passes through the ink discharge passage 20b and is discharged as fine droplets from the ink discharge port 20c.

The configuration of the inkjet print head 1 will be described in more detail with reference to FIGS. In the following description, the left side of FIG. 1 is called “left”, the right side of FIG. 1 is called “right”, the lower side of FIG. 1 is called “front”, and the upper side of FIG.
As shown in FIG. 1, the plan view shape of the inkjet print head 1 is a rectangular shape that is long in the front-rear direction. In this embodiment, the planar shape and size of the actuator substrate 2, the protective substrate 4, and the nozzle substrate 3 are substantially the same as the planar shape and size of the inkjet print head 1.

On the actuator substrate 2, a plurality of rows of piezoelectric elements 9 (hereinafter referred to as “piezoelectric element rows”) arranged in stripes in the front-rear direction in a plan view are arranged at intervals in the left-right direction. There are columns. In this embodiment, for convenience of explanation, it is assumed that two piezoelectric element rows are provided.
As shown in FIGS. 1 to 7, an ink flow path 5 (pressure chamber 7) is formed on the actuator substrate 2 for each piezoelectric element of each piezoelectric element array. Therefore, in the plan view, the actuator substrate 2 has an ink flow path row (pressure chamber row) composed of a plurality of ink flow passages 5 (pressure chambers 7) arranged in stripes at intervals in the front-rear direction. Two rows are provided at intervals in the direction.

  The left ink flow path array pattern and the right ink flow path array pattern in FIG. 1 are symmetrical with respect to a line segment that connects the centers of these lines. Accordingly, in the ink flow path 5 included in the left ink flow path array, the ink inflow portion 6 is on the right side with respect to the pressure chamber 7, whereas the ink flow path 5 included in the right ink flow path array. , The ink inflow portion 6 is on the left side with respect to the pressure chamber 7. Therefore, the ink flow direction 41 is opposite to each other in the left ink channel row and the right ink channel row.

  An ink supply through-hole 22 is provided for each of the plurality of ink flow paths 5 in each ink flow path row. The ink supply through hole 22 is disposed on the ink inflow portion 6. Therefore, the ink supply through hole 22 for the ink flow path 5 included in the left ink flow path row is disposed on the right end portion of the ink flow path 5 and is connected to the ink flow path 5 included in the right ink flow path row. The ink supply through hole 22 is disposed on the left end portion of the ink flow path 5.

  In each ink flow path row, the plurality of ink flow paths 5 are formed at equal intervals with a minute interval (for example, about 30 μm to 350 μm) in the width direction thereof. Each ink flow path 5 is elongated along the ink circulation direction 41. The ink flow path 5 includes an ink inflow portion 6 communicating with the ink supply through hole 22 and a pressure chamber 7 communicating with the ink inflow portion 6. The pressure chamber 7 has a rectangular shape elongated in the ink circulation direction 41 in plan view. That is, the top surface portion of the pressure chamber 7 has two side edges along the ink circulation direction 41 and two end edges along a direction orthogonal to the ink circulation direction 41. The ink inflow portion 6 has substantially the same width as the pressure chamber 7 in plan view. The inner surface of the end portion of the ink inflow portion 6 opposite to the pressure chamber 7 is formed in a semicircular shape in plan view. The ink supply through-hole 22 has a circular shape in plan view (see particularly FIG. 5).

  The piezoelectric element 9 has a rectangular shape that is long in the longitudinal direction of the pressure chamber 7 (movable film 10A) in plan view. The longitudinal length of the piezoelectric element 9 is shorter than the longitudinal length of the pressure chamber 7 (movable film 10A). As shown in FIG. 5, both end edges along the short direction of the piezoelectric element 9 are arranged on the inner side with a predetermined distance from each corresponding end edge of the movable film 10 </ b> A. Further, the width of the piezoelectric element 9 in the short direction is narrower than the width of the movable film 10A in the short direction. Both side edges along the longitudinal direction of the piezoelectric element 9 are arranged on the inner side with a predetermined interval with respect to corresponding side edges of the movable film 10A.

  The lower electrode 11 is formed over almost the entire surface of the movable film forming layer 10. The lower electrode 11 is a common electrode shared for the plurality of piezoelectric elements 9. The lower electrode 11 is drawn from the main electrode portion 11A in a direction along the surface of the movable film forming layer 10 in a rectangular shape in plan view, which constitutes the piezoelectric element 9, and at the periphery of the top surface portion of the pressure chamber 7. And an extension portion 11B extending outward.

  The length in the longitudinal direction of the main electrode portion 11A is shorter than the length in the longitudinal direction of the movable film 10A. Both end edges of the main electrode portion 11A are arranged on the inner side with a predetermined interval from the corresponding both end edges of the movable film 10A. Further, the width of the main electrode portion 11A in the short direction is narrower than the width of the movable film 10A in the short direction. Both side edges of the main electrode portion 11A are arranged on the inner side with a predetermined interval with respect to corresponding side edges of the movable film 10A. The extension portion 11B is a region excluding the main electrode portion 11A out of the entire region of the lower electrode 11.

  The upper electrode 13 is formed in a rectangular shape with the same pattern as the main electrode portion 11A of the lower electrode 11 in plan view. That is, the length of the upper electrode 13 in the longitudinal direction is shorter than the length of the movable film 10A in the longitudinal direction. Both end edges of the upper electrode 13 are arranged on the inner side with a predetermined interval from the corresponding both end edges of the movable film 10A. Further, the width of the upper electrode 13 in the short direction is narrower than the width of the movable film 10A in the short direction. Both side edges of the upper electrode 13 are arranged on the inner side with a predetermined interval with respect to corresponding side edges of the movable film 10A.

  The piezoelectric film 12 is formed in a rectangular shape having the same pattern as that of the upper electrode 13 in plan view. That is, the length in the longitudinal direction of the piezoelectric film 12 is shorter than the length in the longitudinal direction of the movable film 10A. Both end edges of the piezoelectric film 12 are arranged on the inner side with a predetermined interval from the corresponding both end edges of the movable film 10A. Further, the width of the piezoelectric film 12 in the short direction is narrower than the width of the movable film 10A in the short direction. Both side edges of the piezoelectric film 12 are arranged on the inner side with a predetermined interval with respect to corresponding side edges of the movable film 10A. The lower surface of the piezoelectric film 12 is in contact with the upper surface of the main electrode portion 11 </ b> A of the lower electrode 11, and the upper surface of the piezoelectric film 12 is in contact with the lower surface of the upper electrode 13.

  The upper wiring 17 extends from the upper surface of one end of the piezoelectric element 9 (end on the downstream side in the ink flow direction 41) along the end surface of the piezoelectric element 9 connected thereto, and further along the surface of the extension 11B of the lower electrode 11. And extending in a direction along the ink circulation direction 41. The tip end portion of the upper wiring 17 is disposed in the opening 54 of the protective substrate 4. An upper electrode pad opening 35 is formed in the passivation film 21 to expose the central portion of the surface of the tip end portion of the upper wiring 17. An upper electrode pad 42 is provided on the passivation film 21 so as to cover the upper electrode pad opening 35. The upper electrode pad 42 is connected to the upper wiring 17 in the upper electrode pad opening 35.

Referring to FIG. 1, the lower electrode pad 43 includes a rear position of the upper electrode pad row corresponding to the left piezoelectric element row and an upper electrode pad row corresponding to the right piezoelectric element row in plan view. It is arranged in the rear position. Each lower electrode pad 43 is connected to the extension portion 11 </ b> B of the lower electrode 11 via a lower wiring disposed below the lower electrode pad 43.
As shown in FIGS. 1, 3, 4, and 6, the protective substrate 4 includes a plurality of ink supply paths 53 (hereinafter, “ A plurality of ink supply passages 53 (hereinafter referred to as “second ink supply passages 53”). Is sometimes formed). The first ink supply paths 53 are arranged in a line at intervals in the front-rear direction at a position closer to the left side than the width central portion of the protective substrate 4 in plan view. The second ink supply paths 53 are arranged in a line at intervals in the front-rear direction at a position on the right side of the width center of the protective substrate 4 in plan view. The ink supply path 53 of the protective substrate 4 has a circular shape with the same pattern as the ink supply through hole 22 on the actuator substrate 2 side in plan view. The ink supply path 53 is aligned with the ink supply through hole 22 in plan view.

  Further, the protective substrate 4 has openings 54 for exposing all the upper electrode pads 42 corresponding to the left piezoelectric element array and the left lower electrode pad 43, and all corresponding to the right piezoelectric element array. The upper electrode pad 42 and the opening 54 for exposing the lower electrode pad 43 on the right side are formed. These openings 54 have a rectangular shape that is long in the front-rear direction in plan view.

FIG. 10 is a bottom view of the region shown in FIG. 4 of the protective substrate.
As shown in FIGS. 6, 7, and 10, on the facing surface 51 of the protective substrate 4, receiving recesses 52 are formed at positions facing the piezoelectric elements 9 in each piezoelectric element row. An ink supply path 53 is disposed on the upstream side in the ink flow direction 41 with respect to each housing recess 52, and an opening 54 is disposed on the downstream side. Each receiving recess 52 is formed in a rectangular shape that is slightly larger than the pattern of the upper electrode 13 of the corresponding piezoelectric element 9 in plan view. And the corresponding piezoelectric element 9 is accommodated in each accommodation recess 52.

FIG. 8 is a schematic plan view showing a pattern example of the insulating film of the ink jet print head. FIG. 9 is a schematic plan view showing a pattern example of a passivation film of the ink jet print head.
In this embodiment, the insulating film 15 and the passivation film 21 are formed on the actuator substrate 2 in almost the entire outer region of the housing recess 52 of the protective substrate 4 in plan view. However, in this region, the insulating film 15 is formed with an ink supply through hole 22 and a lower electrode contact hole. In this region, the passivation film 21 has an ink supply through hole 22, an upper electrode pad opening 35, and a lower electrode pad opening.

  In the inner region of the housing recess 52 of the protective substrate 4, the insulating film 15 and the passivation film 21 are formed only at one end (upper wiring region) where the upper wiring 17 exists. In this region, the passivation film 21 is formed so as to cover the upper surface and the side surface of the upper wiring 17 on the insulating film 15. In other words, the opening 37 is formed in the insulating film 15 and the passivation film 21 in a region excluding the upper wiring region in the inner region of the accommodation recess 52 in plan view. An upper electrode contact hole 33 is further formed in the insulating film 15.

  Referring to FIG. 2, a plurality of first bonding pressure increasing recesses 61 are formed on the periphery of back surface 2 b of actuator substrate 2 in a dotted manner. The first bonding pressure increasing recess 61 has a quadrangular shape in plan view. Specifically, in the peripheral portion of the back surface 2b of the actuator substrate 2, the plurality of first bonding pressure increasing recesses 61 are arranged in a matrix at intervals. The plurality of first bonding pressure increasing recesses 61 may be arranged in a staggered pattern on the peripheral edge of the back surface 2 b of the actuator substrate 2. In addition, the plurality of first bonding pressure increasing recesses 61 may be arranged randomly at the peripheral edge of the back surface 2 b of the actuator substrate 2.

  In this embodiment, the shape of the first bonding pressure increasing recess 61 in plan view is a square shape, but may be an arbitrary shape such as a circle, an ellipse, or a polygon other than a rectangle. For example, as shown in FIG. 16, the planar shape of the first bonding pressure increasing recess 61 may be a regular hexagon. FIG. 16 is an enlarged bottom view of a part of the bottom surface corresponding to FIG. At this time, the arrangement pattern of the plurality of first bonding pressure increasing recesses 61 is such that the first bonding pressure increasing recesses 61 are arranged so that one side of the adjacent first bonding pressure increasing recesses 61 is parallel to each other. It has a honeycomb shape. Thus, when the plurality of first bonding pressure increasing recesses 61 having a regular hexagonal shape in plan view are arranged in a honeycomb shape, the plurality of first bonding pressure increasing recesses 61 having a square shape in plan view are spaced apart from each other. There are the following advantages compared to the case of arranging in a matrix. That is, when the plurality of first joining pressure increasing recesses 61 having a regular hexagonal shape in plan view are arranged in a honeycomb shape, the first joining pressure increasing recesses 61 are arranged in a zigzag shape, so that the nozzle substrate 3 is connected to the actuator. When bonded to the substrate 2, it becomes difficult for the adhesive to flow into the ink flow path 5.

  Referring to FIG. 3, a plurality of second bonding pressure increasing recesses 62 are formed on the periphery of the facing surface 51 of the protective substrate 4 so as to be scattered. The second bonding pressure increasing recess 62 has a quadrangular shape in plan view. Specifically, in the peripheral portion of the facing surface 51 of the protective substrate 4, the plurality of second bonding pressure increasing recesses 62 are arranged in a matrix at intervals. The plurality of second bonding pressure increasing recesses 62 may be arranged in a staggered pattern at the peripheral edge of the facing surface 51 of the protective substrate 4. In addition, the plurality of second bonding pressure increasing recesses 62 may be arranged randomly at the peripheral edge portion of the facing surface 51 of the protective substrate 4.

  In this embodiment, the planar shape of the second bonding pressure increasing concave portion 62 is a square shape, but may be an arbitrary shape such as a circle, an ellipse, or a polygon other than a rectangle. For example, as shown in FIG. 17, the planar view shape of the second bonding pressure increasing recess 62 may be a regular hexagon. FIG. 17 is a bottom view in which a part of the bottom surface corresponding to FIG. 3 is enlarged. At this time, in the arrangement pattern of the plurality of second bonding pressure increasing recesses 62, the second bonding pressure increasing recesses 62 are arranged so that the sides of the adjacent second bonding pressure increasing recesses 62 are parallel to each other. It has a honeycomb shape. As described above, when the plurality of second bonding pressure increasing recesses 62 having a regular hexagonal shape in plan view are arranged in a honeycomb shape, the plurality of second bonding pressure increasing recesses 62 having a square shape in plan view are spaced apart from each other. There are the following advantages compared to the case of arranging in a matrix. In other words, when the plurality of second joining pressure increasing recesses 62 having a regular hexagonal shape in plan view are arranged in a honeycomb shape, the second joining pressure increasing recesses 62 are arranged in a zigzag shape. When bonded to the substrate 2, it becomes difficult for the adhesive to flow into the accommodation recess 52, the ink supply path 53, and the opening 54. An outline of a method for manufacturing the ink jet print head 1 will be described.

FIG. 11 is a plan view of a semiconductor wafer as an original substrate of the actuator substrate, and shows a partial area in an enlarged manner.
A semiconductor wafer (actuator wafer) 100 is prepared as an original substrate of the actuator substrate 2. The actuator wafer 100 is made of, for example, a silicon wafer. The surface 100a of the actuator wafer 100 corresponds to the surface 2a of the actuator substrate. On the surface 100a of the actuator wafer 100, a plurality of functional element formation regions 101 are arranged in a matrix. A scribe region (boundary region) 102 is provided between adjacent functional element formation regions 101. The scribe region 102 is a belt-like region having a substantially constant width, and is formed in a lattice shape extending in two orthogonal directions. In the scribe area 102, a planned cutting line 103 is set. By performing necessary steps on the actuator wafer 100, the ink flow path 5 and the first bonding pressure increasing recess 61 are not formed, but the configuration of the substrate assembly SA is formed on each functional element formation region 101. A substrate assembly assembly (SA assembly) 110 is created.

  A protective substrate assembly 130 (see FIG. 12K) that integrally includes a plurality of protective substrates 4 corresponding to the respective functional element formation regions 101 of the substrate assembly assembly 110 is prepared in advance. The protective substrate assembly 130 is created by performing necessary processes on a semiconductor wafer (protective substrate wafer) as an original substrate of the protective substrate 4. The protective substrate wafer is made of, for example, a silicon wafer.

In addition, a nozzle substrate assembly 150 (see FIG. 13F) that includes a plurality of nozzle substrates 3 corresponding to each functional element formation region 101 of the substrate assembly assembly 110 is prepared in advance. The nozzle substrate assembly 150 is created by performing necessary processes on a semiconductor wafer (nozzle wafer) as an original substrate of the nozzle substrate 3. The nozzle wafer is made of, for example, a silicon wafer. As shown in FIG. 13F, the nozzle substrate assembly 150 includes a nozzle wafer 140, a silicon oxide (SiO ₂ ) film 142 formed on one surface of the nozzle wafer 140, and a water repellent film formed on the surface of the silicon oxide film 142. 143.

  When the substrate assembly assembly 110 is created, the protective substrate assembly 130 is bonded to the substrate assembly assembly 110. Next, the first bonding pressure increasing recess 61 and the ink flow path 5 are formed in the substrate assembly assembly 110. Next, the nozzle substrate assembly 150 is bonded to the substrate assembly assembly 110. As a result, an inkjet printhead assembly 170 (see FIG. 12N) including the substrate assembly assembly 110, the protective substrate assembly 130, and the nozzle substrate assembly 150 is obtained. Thereafter, the inkjet print head assembly 170 is cut (diced) by a dicing blade along the planned cutting line 103. Thereby, individual inkjet print heads (chips) 1 including the functional element formation regions 101 are cut out. The ink jet print head 1 has a scribe region 102 at the periphery, and has a functional element formation region 101 in a central region surrounded by the scribe region 102.

Hereinafter, the manufacturing method of the inkjet print head 1 will be described more specifically.
12A to 12N are cross-sectional views illustrating the manufacturing process of the inkjet print head 1, and are cross-sectional views corresponding to the cut surface of FIG.
First, as shown in FIG. 12A, an actuator wafer 100 is prepared. However, the actuator wafer 100 is thicker than the final thickness of the actuator substrate 2. Then, the movable film forming layer 10 is formed on the surface 100 a of the actuator wafer 100. Specifically, a silicon oxide film (for example, 1.2 μm thick) is formed on the surface 100 a of the actuator wafer 100. When the movable film forming layer 10 is composed of a laminated film of a silicon film, a silicon oxide film, and a silicon nitride film, a silicon film (for example, 0.4 μm thick) is formed on the surface of the actuator substrate 2, A silicon oxide film (for example, 0.4 μm thickness) is formed thereon, and a silicon nitride film (for example, 0.4 μm thickness) is formed on the silicon oxide film.

Next, the metal barrier film 8 is formed on the movable film forming layer 10. The metal barrier film 8 is made of, for example, an Al ₂ O ₃ film (for example, 50 nm to 100 nm thick). The metal barrier film 8 prevents escape of metal atoms from the piezoelectric film 12 formed later. If metal electrons escape, the piezoelectric characteristics of the piezoelectric film 12 may deteriorate. Further, when the escaped metal atoms are mixed into the silicon layer constituting the movable film 10A, the durability of the movable film 10A may be deteriorated.

Next, as shown in FIG. 12B, a lower electrode film 71 that is a material layer of the lower electrode 11 is formed on the metal barrier film 8. The lower electrode film 71 is made of, for example, a Pt / Ti laminated film having a Ti film (for example, 10 nm to 40 nm thickness) as a lower layer and a Pt film (for example, 10 nm to 400 nm thickness) as an upper layer. Such a lower electrode film 71 may be formed by sputtering.
Next, a material film (piezoelectric material film) 72 of the piezoelectric film 12 is formed on the entire surface of the lower electrode film 71. Specifically, for example, the piezoelectric material film 72 having a thickness of 1 μm to 3 μm is formed by a sol-gel method. Such a piezoelectric material film 72 is made of a sintered body of metal oxide crystal grains.

Next, an upper electrode film 73 that is a material of the upper electrode 13 is formed on the entire surface of the piezoelectric material film 72. The upper electrode film 73 may be a single film of platinum (Pt), for example. Upper electrode film 73 may be, for example, an IrO ₂ / Ir laminated film having an IrO ₂ film (for example, 40 nm to 160 nm thickness) as a lower layer and an Ir film (for example, 40 nm to 160 nm thickness) as an upper layer. Such an upper electrode film 73 may be formed by sputtering.

  Next, as shown in FIGS. 12C and 12D, the upper electrode film 73, the piezoelectric material film 72, and the lower electrode film 71 are patterned. First, a resist mask having a pattern of the upper electrode 13 is formed by photolithography. Then, as shown in FIG. 12C, the upper electrode film 73 and the piezoelectric material film 72 are continuously etched using the resist mask as a mask, whereby the upper electrode 13 and the piezoelectric film 12 having a predetermined pattern are formed. The

  Next, after the resist mask is peeled off, a resist mask having a pattern of the lower electrode 11 is formed by photolithography. Then, as shown in FIG. 12D, the lower electrode film 71 is etched by using the resist mask as a mask, whereby the lower electrode 11 having a predetermined pattern is formed. Thereby, the lower electrode 11 including the main electrode portion 11 </ b> A and the extension portion 11 </ b> B having the through hole 23 is formed. In this manner, the piezoelectric element 9 including the main electrode portion 11A of the lower electrode 11, the piezoelectric film 12, and the upper electrode 13 is formed.

Next, as shown in FIG. 12E, after the resist mask is removed, a hydrogen barrier film 14 covering the entire surface is formed. The hydrogen barrier film 14 may be an Al ₂ O ₃ film formed by a sputtering method, and the film thickness may be 50 nm to 100 nm. Thereafter, an insulating film 15 is formed on the entire surface of the hydrogen barrier film 14. The insulating film 15 may be a SiO ₂ film, and the film thickness may be 200 nm to 300 nm. Subsequently, the insulating film 15 and the hydrogen barrier film 14 are continuously etched, whereby an upper electrode contact hole 33 and a lower electrode contact hole are formed.

Next, as shown in FIG. 12F, wiring films constituting the upper wiring 17 and the lower wiring are formed on the insulating film 15 including the upper electrode contact hole 33 and the lower electrode contact hole by sputtering. . Thereafter, the wiring film is patterned by photolithography and etching, whereby the upper wiring 17 and the lower wiring are formed simultaneously.
Next, as shown in FIG. 12G, a passivation film 21 is formed on the surface of the insulating film 15 to cover the upper wiring 17 and the lower wiring. The passivation film 21 is made of, for example, SiN. The passivation film 21 is formed by plasma CVD, for example.

  Next, a resist mask having openings corresponding to the upper electrode pad opening 35 and the lower electrode pad opening is formed by photolithography, and the passivation film 21 is etched using the resist mask as a mask. As a result, as shown in FIG. 12H, the upper electrode pad opening 35 and the lower electrode pad opening are formed in the passivation film 21. After the resist mask is peeled off, the upper electrode pad 42 and the lower electrode pad connected to the upper wiring 17 and the lower wiring through the upper electrode pad opening 35 and the lower electrode pad opening on the passivation film 21, respectively. 43 is formed.

  Next, a resist mask having openings 37 and openings corresponding to the ink supply through holes 22 is formed by photolithography, and the passivation film 21 and the insulating film 15 are continuously etched using the resist mask as a mask. Thereby, as shown in FIG. 12I, the opening 37 and the ink supply through hole 22 are formed in the passivation film 21 and the insulating film 15.

  Next, the resist mask is peeled off. Then, a resist mask having an opening corresponding to the ink supply through hole 22 is formed by photolithography, and the hydrogen barrier film 14, the metal barrier film 8, and the movable film forming layer 10 are etched using the resist mask as a mask. As a result, as shown in FIG. 12J, the ink supply through hole 22 is formed in the hydrogen barrier film 14, the metal barrier film 8, and the movable film forming layer 10. Thereby, the substrate assembly assembly 110 is created.

  Next, as shown in FIG. 12K, the adhesive 50 is applied to the facing surface 51 of the protective substrate assembly 130 so that the ink supply path 53 and the corresponding ink supply through hole 22 coincide with each other. A protective substrate assembly 130 is fixed to the assembly 110. Next, as shown in FIG. 12L, in order to improve the handling of the substrate assembly assembly 110 to which the protective substrate assembly 130 is fixed, the support wafer 75 is provided with a thermal peeling tape (not shown) on the upper surface of the protective substrate assembly 130. Attached through. Then, back surface grinding for thinning the actuator wafer 100 is performed. By polishing the actuator wafer 100 from the back surface 100b, the actuator wafer 100 is thinned. For example, the actuator wafer 100 having a thickness of about 670 μm in the initial state may be thinned to a thickness of about 300 μm.

  Next, a resist mask having an opening corresponding to the first bonding pressure increasing recess 61 is formed on the back surface 100b side of the actuator wafer 100 by photolithography, and the actuator wafer 100 is etched from the back surface 100b using this resist mask as a mask. Is done. As a result, a first bonding pressure increasing recess 61 is formed on the back surface 100 b of the actuator wafer 100. In this embodiment, the first bonding pressure increasing recess 61 is a functional element in the scribe region 102 in the back surface 100b and the functional element in the back surface 100b, in addition to the region corresponding to the peripheral portion of each functional element formation region 101 in the back surface 100b of the actuator wafer 100. It is also formed on the peripheral portion that does not include the formation region 101.

  Next, the resist mask is peeled off. Then, a resist mask having an opening corresponding to the ink flow path 5 (ink inflow portion 6 and pressure chamber 7) is formed on the back surface 100b side of the actuator wafer 100 by photolithography, and the actuator wafer 100 is formed using this resist mask as a mask. Is etched from the back surface 100b. As a result, as shown in FIG. 12M, the ink flow path 5 (the ink inflow portion 6 and the pressure chamber 7) is formed in the actuator wafer 100.

During this etching, the metal barrier film 8 formed on the surface of the movable film forming layer 10 prevents the metal elements (Pb, Zr, Ti in the case of PZT) from escaping from the piezoelectric film 12, and the piezoelectric body. The piezoelectric characteristics of the film 12 are kept good. Further, as described above, the metal barrier film 8 contributes to maintaining the durability of the silicon layer that forms the movable film 10A.
Thereafter, as shown in FIG. 12N, the nozzle substrate aggregate 150 is bonded to the back surface 100 b of the actuator wafer 100. As a result, an inkjet printhead assembly 170 including the substrate assembly assembly 110, the protective substrate assembly 130, and the nozzle substrate assembly 150 is obtained. Thereafter, the inkjet print head assembly 170 is cut by the dicing blade along the planned cutting line 103. That is, the process of cutting out the inkjet print head 1 individually is performed. When this step is completed, the actuator wafer 100 in the substrate assembly assembly 110 becomes the actuator substrate 2 of each ink jet print head 1. Further, the protective substrate aggregate 130 becomes the protective substrate 4 of each ink jet print head 1. In addition, the nozzle wafer 140, the silicon oxide film 142, and the water repellent film 143 in the nozzle substrate assembly 150 become the silicon substrate 30, the silicon oxide film 31, and the water repellent film 32 in the nozzle substrate 3 of each ink jet print head 1, respectively. . Thus, individual pieces of the ink jet print head 1 having the structure shown in FIGS. 1 to 7 are obtained.

  In the ink jet print head 1 obtained in this way, the side surface of the actuator substrate 2 and the side surface of the nozzle substrate 3 are flush with each other (planar over the entire circumference) in plan view. That is, in this embodiment, the ink jet print head 1 having no step between the actuator substrate 2 and the nozzle substrate 3 is obtained. In this embodiment, the side surface of the actuator substrate 2 and the side surface of the protective substrate 4 are also flush in all directions (planar over the entire circumference) in plan view. That is, in this embodiment, the ink jet print head 1 having no step between the actuator substrate 2 and the protective substrate 4 can be obtained.

  In the ink jet print head manufacturing method according to this embodiment, the nozzle substrate assembly 150 is bonded to the substrate assembly assembly 110 to which the protective substrate assembly 130 is fixed, thereby creating the ink jet print head assembly 170. Then, the inkjet print head assembly 170 is diced to cut out the inkjet print head 1 individually. Therefore, for example, after the individual substrate assemblies SA are manufactured, the inkjet print head 1 is manufactured more efficiently than when the nozzle substrate 3 is individually joined to the individual substrate assemblies SA to manufacture the inkjet print head. Will be able to.

13A to 13F are cross-sectional views schematically showing the manufacturing process of the nozzle substrate assembly 150, and are cross-sectional views taken along a cutting line that is orthogonal to the ink flow direction and passes through the center of the nozzle hole.
First, as shown in FIG. 13A, a semiconductor wafer (nozzle wafer) 140 as an original substrate of the nozzle substrate 3 is prepared. However, as the nozzle wafer 140, a wafer thicker than the final nozzle substrate 3 is used. The nozzle wafer 140 is made of a silicon wafer. The nozzle wafer 140 has a surface 140a on the side facing the back surface 2b of the actuator substrate 2 and a back surface 140b on the opposite side. Silicon oxide (SiO ₂ ) films 141 and 142 are formed on both surfaces 140 a and 140 b of the nozzle wafer 140 by thermally oxidizing both surfaces 140 a and 140 b of the nozzle wafer 140.

Next, as shown in FIG. 13B, a water repellent film 143 is formed on the surface of the silicon oxide film 142 on the back surface 140b side of the nozzle wafer 140 by spin coating or vapor deposition.
Next, as shown in FIG. 13C, a support wafer 146 is attached to the surface of the water repellent film 143 via a protective tape 144 and a thermal peeling tape 145. The protective tape 144 is, for example, a Kapton (registered trademark) tape. The support wafer 146 is made of a silicon wafer.

Next, as shown in FIG. 13D, the nozzle wafer 140 is polished from the silicon oxide film 141 side (the nozzle wafer 140 surface 140a side), whereby the nozzle wafer 140 is thinned. For example, the nozzle wafer 140 having a thickness of about 625 μm in the initial state may be thinned to a thickness of about 40 μm.
Next, as shown in FIG. 13E, a resist mask 147 having an opening corresponding to the nozzle hole 20 is formed by photolithography, and the nozzle wafer 140 is dry-etched from the surface using the resist mask 147 as a mask. At this time, isotropic dry etching is performed first, and then anisotropic dry etching is performed. By the isotropic dry etching, a truncated cone-shaped concave portion (forward tapered concave portion) 20a having a smaller cross section toward the back surface 140b side of the nozzle wafer 140 is formed on the front surface 140a of the nozzle wafer 140. Then, the first straight hole 20b1 having a circular cross section reaching the silicon oxide film 142 is formed on the bottom surface of the forward tapered recess 20a in the nozzle wafer 140 by anisotropic dry etching. The cross-sectional area of the first straight hole 20b1 is substantially constant over the length direction.

  Next, as shown in FIG. 13F, after the resist mask is peeled off, the silicon oxide film 142 and the water repellent film 143 are etched using the nozzle wafer 140 as a hard mask. Thus, the second straight hole 20b2 communicating with the first straight hole 20b1 is formed in the silicon oxide film 142 and the water repellent film 143. The cross section of the second straight hole 20b2 has a circular shape that is approximately the same size as the first straight hole 20b1. The cross-sectional area of the second straight hole 20b2 is substantially constant over the length direction. The first straight hole 20b1 and the second straight hole 20b2 constitute an ink discharge passage 20b. Further, the nozzle hole 20 is constituted by the tapered recess 20a and the ink discharge passage 20b.

  In this way, the nozzle holes 20 are formed in the laminated film including the nozzle wafer 140, the silicon oxide film 142, and the water repellent film 143. The laminated film composed of the nozzle wafer 140, the silicon oxide film 142, and the water repellent film 143 constitutes a nozzle substrate assembly 150. Therefore, the nozzle substrate assembly 150 with the support wafer 146 is obtained, which includes the nozzle substrate assembly 150 and the support wafer 146 attached to the nozzle substrate assembly 150 via the protective tape 144 and the thermal peeling tape 145. .

14A to 14C are schematic cross-sectional views for explaining a process of joining the nozzle substrate assembly 150 to the substrate assembly assembly 110, and are orthogonal to the ink flow direction and pass through the center of the nozzle hole. It is sectional drawing which follows such a cutting line. 14A to 14C are cross-sectional views showing regions corresponding to the frontmost pressure chamber and the rearmost pressure chamber in the right pressure chamber row.
First, as shown in FIG. 14A, an adhesive 160 is applied to the back surface 100 b of the actuator wafer 100 of the substrate assembly assembly 110. Then, the front surface 140a of the nozzle wafer 140 of the nozzle substrate assembly 150 with the support wafer 146 is pressed against the back surface 100b of the actuator wafer 100 of the substrate assembly assembly 110, so that the front surface 140a of the nozzle wafer 140 is an actuator. Affixed to the back surface 100 b of the wafer 100.

  The first bonding pressure increasing recess 61 includes a region corresponding to the peripheral edge of each functional element formation region 101 on the back surface 100b of the actuator wafer 100, a scribe region 102 on the back surface 100b, and a functional element formation region 101 on the back surface 100b. There is no peripheral edge. For this reason, when the front surface 140a of the nozzle wafer 140 is pressed against the back surface 100b of the actuator wafer 100, the bonding pressure between the two can be increased. Thereby, the bonding strength between the nozzle substrate assembly 150 and the substrate assembly assembly 110 can be increased. In other words, the bonding strength between the nozzle substrate 3 and the actuator substrate 2 can be increased.

Next, as shown in FIG. 14B, the support wafer 146 is peeled off together with the thermal peeling tape 145 by peeling the thermal peeling tape 145 from the protective tape 144 affixed to the nozzle substrate assembly 150.
Finally, as shown in FIG. 14C, the protective tape 144 is peeled from the nozzle substrate assembly 150.

15A to 15C are cross-sectional views schematically showing modified examples of the nozzle holes, respectively.
The nozzle hole 20 shown in FIG. 15A includes a forward tapered recess 20 a formed in the silicon substrate 30, and an ink discharge passage 20 b formed in a laminated film including the silicon oxide film 31 and the water repellent film 32. An opening of the ink discharge passage 20b is an ink discharge port 20c. The forward tapered recess 20a is formed in a truncated cone shape whose cross section gradually decreases from the surface of the silicon substrate 30 toward the silicon oxide film 31 side. The forward tapered recess 20a can be formed by subjecting the silicon substrate 30 (nozzle wafer 140) to isotropic dry etching using a resist mask. The ink discharge passage 20b is a straight hole having a circular cross section. The ink discharge passage 20b is formed by anisotropically forming a laminated film composed of the silicon oxide film 31 (142) and the water repellent film 32 (143) using the silicon substrate 30 (nozzle wafer 140) with the forward tapered recess 20a formed as a hard mask. It can be formed by reactive dry etching.

  The nozzle hole 20 shown in FIG. 15B is a straight hole having a circular cross section formed in a laminated film including a silicon substrate 30, a silicon oxide film 31 and a water repellent film 32. Such a nozzle hole 20 is formed by anisotropically etching a laminated film composed of the silicon substrate 30 (nozzle wafer 140), the silicon oxide film 31 (142) and the water repellent film 32 (143) using a resist mask. Can be formed.

  The nozzle hole 20 shown in FIG. 15C includes a reverse tapered recess 20 a formed in the silicon substrate 30 and an ink discharge passage 20 b formed in a laminated film including the silicon oxide film 31 and the water repellent film 32. An opening of the ink discharge passage 20b is an ink discharge port 20c. The reverse tapered recess 20a is formed in a truncated cone shape whose cross section gradually increases from the surface of the silicon substrate 30 toward the silicon oxide film 31 side. The reverse tapered recess 20a can be formed by anisotropic dry etching the silicon substrate 30 (nozzle wafer 140) using a resist mask. The ink discharge passage 20b is a straight hole having a circular cross section. The ink discharge passage 20b is formed by anisotropically forming a laminated film composed of the silicon oxide film 31 (142) and the water repellent film 32 (143) using the silicon substrate 30 (nozzle wafer 140) on which the reverse tapered recess 20a is formed as a hard mask. It can be formed by reactive dry etching.

As mentioned above, although embodiment of this invention was described, this invention can also be implemented in another embodiment. For example, in the above-described embodiment, the actuator substrate 2 is provided with two piezoelectric element rows (pressure chamber rows), but only one piezoelectric element row (pressure chamber row) is provided. Alternatively, three or more rows may be provided.
In the above-described embodiment, the nozzle substrate 3 includes the silicon substrate 30, the silicon oxide film 31 formed on the silicon substrate 30, and the water repellent film 32 formed on the silicon oxide film 31. However, the silicon oxide film 31 may not be provided. That is, the nozzle substrate 3 may be composed of the silicon substrate 30 and the water repellent film 32 formed on the silicon substrate 30.

  In the above-described embodiment, the first bonding pressure increasing recess 61 is a region corresponding to the peripheral portion of each functional element formation region 101 on the back surface 100b of the actuator wafer 100, as well as the scribe region 102 and the back surface 100b on the back surface 100b. It is also formed on the peripheral portion not including the functional element formation region 101 in FIG. However, the first bonding pressure increasing recess 61 may not be formed on the peripheral edge of the actuator wafer 100 that does not include the functional element formation region 101 on the back surface 100b. Further, the first bonding pressure increasing recess 61 may not be formed in the scribe region 102 on the back surface 100 b of the actuator wafer 100. Further, the first bonding pressure increasing recess 61 may not be formed in the peripheral portion and the scribe region 102 not including the functional element formation region 101 on the back surface 100 b of the actuator wafer 100.

In the above-described embodiment, the insulating film 15 is formed on a part of the surface of the hydrogen barrier film 14. However, the insulating film 15 may be formed on the entire surface of the hydrogen barrier film 14.
In the above-described embodiment, the insulating film 15 is formed on a part of the surface of the hydrogen barrier film 14, but the insulating film 15 may not be provided.
In the above-described embodiment, PZT is exemplified as the material for the piezoelectric film. In addition, lead titanate (PbPO ₃ ), potassium niobate (KNbO ₃ ), niobium niobate (LiNbO ₃ ), lithium tantalate A piezoelectric material made of a metal oxide typified by (LiTaO ₃ ) or the like may be applied.

  In addition, various design changes can be made within the scope of matters described in the claims.

DESCRIPTION OF SYMBOLS 1 Init print head 2 Actuator board 3 Nozzle board 4 Protection board 5 Ink flow path 6 Ink inflow part 7 Pressure chamber 8 Metal barrier film 9 Piezoelectric element 10 Movable film formation layer 10A Movable film 11 Lower electrode 11A Main electrode part 11B Extension part DESCRIPTION OF SYMBOLS 12 Piezoelectric film 13 Upper electrode 14 Hydrogen barrier film 15 Insulating film 17 Upper wiring 20 Nozzle hole 20a Recess 20b Ink discharge passage 20b1 First straight hole 20b2 Second straight hole 20c Ink discharge port 21 Passivation film 22 Ink supply through hole 23 Through hole (lower electrode)
30 Silicon substrate (main substrate)
31 Silicon oxide film 32 Water repellent film 33 Upper electrode contact hole 35 Upper electrode pad opening 37 Opening 41 Ink flow direction 42 Upper electrode pad 43 Lower electrode pad 50 Adhesive 51 Opposing surface 52 Accommodating recess 53 Ink supply path 54 Openings 61 First Bonding Pressure Increasing Recesses 62 Second Bonding Pressure Increasing Recesses 71 Lower Electrode Film 72 Piezoelectric Material Film 73 Upper Electrode Film 75 Support Wafer 100 Actuator Wafer 100a Surface 100b Back Surface 101 Functional Element Forming Area 102 Scribe Area DESCRIPTION OF SYMBOLS 103 Cutting line 110 Substrate assembly assembly 130 Protection substrate assembly 140 Nozzle wafer 141, 142 Silicon oxide film 143 Water repellent film 144 Protection tape 145 Thermal peeling tape 146 Support wafer 147 Resist mask 150 Nozzle substrate assembly 160 Adhesive 170 Inkjet printhead assembly SA substrate assembly

Claims (21)

An actuator substrate having an ink flow path including a pressure chamber;
A movable film forming layer including a movable film disposed on the pressure chamber and defining a top surface portion of the pressure chamber;
A piezoelectric element formed on the movable film;
The actuator substrate is bonded to a second surface opposite to the first surface, which is the surface on the movable film side of the actuator substrate, and has a nozzle hole that defines a bottom surface of the pressure chamber and communicates with the pressure chamber. A nozzle substrate,
An ink jet print head, wherein a concave portion for increasing a bonding pressure is formed at a peripheral edge portion of the second surface of the actuator substrate.   2. The ink jet print head according to claim 1, wherein the bonding pressure increasing concave portions include a plurality of bonding pressure increasing concave portions formed so as to be scattered in a peripheral portion of the second surface of the actuator substrate.   The inkjet print head according to claim 2, wherein the bonding pressure increasing recesses are formed in a square shape in plan view, and the plurality of quadrangular bonding pressure increasing recesses are arranged in a matrix with a gap. .   The inkjet print head according to claim 2, wherein the bonding pressure increasing recesses are formed in a regular hexagonal shape in plan view, and the plurality of regular hexagonal recesses for increasing the bonding pressure are arranged in a honeycomb shape. A protective substrate bonded to the actuator substrate by an adhesive so as to cover the piezoelectric element;
The protective substrate is formed toward the actuator substrate side and is formed outside a housing recess that houses the piezoelectric element and one end of the housing recess in plan view, and is formed at one end of the ink flow path. The inkjet print head according to claim 1, further comprising an ink supply path that communicates with the inkjet print head. The nozzle substrate is composed of a main substrate made of Si substrate, a SiO ₂ film formed on the main substrate, which is formed on the SiO ₂ film on the water-repellent film, the SiO ₂ film in the main board The inkjet print head according to claim 1, wherein a surface opposite to the first surface is bonded to the second surface of the actuator substrate.   The ink jet print head according to claim 1, wherein the actuator substrate is made of a Si substrate. The ink jet print head according to claim 1, wherein the movable film forming layer is made of a single SiO ₂ film. The movable film forming layer includes a stacked film of a Si film formed on the actuator substrate, a SiO ₂ film formed on the Si film, and a SiN film formed on the SiO ₂ film. Item 10. The ink jet print head according to any one of Items 1 to 8.   The piezoelectric element includes a lower electrode formed on the movable film, a piezoelectric film formed on the lower electrode, and an upper electrode formed on the piezoelectric film. The inkjet print head as described in any one of these. In plan view, the upper electrode has a peripheral edge that is recessed inward of the pressure chamber from the movable film,
11. The inkjet print head according to claim 10, further comprising an upper wiring having one end connected to the upper surface of the upper electrode and the other end drawn outside the periphery of the pressure chamber in plan view. A hydrogen barrier film covering at least the entire side surface of the upper electrode and the piezoelectric film and the upper surface of the lower electrode;
An insulating film formed on the hydrogen barrier film and disposed between the hydrogen barrier film and the upper wiring;
A contact hole exposing a part of the upper electrode is formed in the hydrogen barrier film and the insulating film, and one end portion of the upper wiring is connected to the upper electrode through the contact hole. The ink jet print head according to claim 11.   The inkjet print head according to claim 12, further comprising a passivation film formed on the insulating film and covering the wiring. Forming a movable film forming layer including a movable film forming region on the actuator substrate;
On the movable film forming region of the movable film forming layer, a lower electrode, an upper electrode disposed on the opposite side of the lower electrode to the movable film forming layer, and a piezoelectric film sandwiched between them Forming a piezoelectric element including:
Bonding a protective substrate to the actuator substrate so as to cover the piezoelectric element;
Forming a bonding pressure increasing recess in a peripheral portion of the second surface opposite to the first surface which is the surface on the movable film forming layer side of the actuator substrate;
Forming an ink flow path including a pressure chamber facing the movable film forming region by etching from the second surface side of the actuator substrate;
And a step of joining a nozzle substrate having a nozzle hole communicating with the pressure chamber on the second surface of the actuator substrate.   The inkjet print according to claim 14, wherein in the step of forming the concave portion for increasing the bonding pressure, a plurality of concave portions for increasing the bonding pressure are scattered at a peripheral portion of the second surface of the actuator substrate. Manufacturing method of the head. An actuator substrate having an ink flow path including a pressure chamber;
A movable film forming layer including a movable film disposed on the pressure chamber and defining a top surface portion of the pressure chamber;
A piezoelectric element formed on the movable film;
A protective substrate bonded to the actuator substrate by an adhesive so as to cover the piezoelectric element,
An ink jet print head in which a concave portion for increasing a bonding pressure is formed in a peripheral edge portion of a surface of the protective substrate facing the actuator substrate.   The ink jet print according to claim 16, wherein the bonding pressure increasing recesses include a plurality of bonding pressure increasing recesses formed to be scattered on a peripheral edge portion of an opposing surface of the protective substrate facing the actuator substrate. head.   The inkjet print head according to claim 17, wherein the bonding pressure increasing recesses are formed in a quadrangular shape in plan view, and the plurality of quadrangular bonding pressure increasing recesses are arranged in a matrix with a gap. .   The inkjet print head according to claim 17, wherein the bonding pressure increasing concave portions are formed in a regular hexagonal shape in a plan view, and the plurality of regular hexagonal concave pressure increasing concave portions are arranged in a honeycomb shape.   The protective substrate is formed toward the actuator substrate side and is formed outside a housing recess that houses the piezoelectric element and one end of the housing recess in plan view, and is formed at one end of the ink flow path. The ink jet print head according to claim 16, further comprising an ink supply path communicating with the ink supply path.   The actuator substrate is bonded to a second surface opposite to the first surface, which is the surface on the movable film side of the actuator substrate, and has a nozzle hole that defines a bottom surface of the pressure chamber and communicates with the pressure chamber. The inkjet printhead of claim 20, further comprising a nozzle substrate.

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