JP6815125B2 - Inkjet printhead and its manufacturing method - Google Patents

Description

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

Patent Document 1 discloses an inkjet print head. The inkjet printhead of Patent Document 1 is provided on an actuator substrate (board) having a pressure chamber (pressure generation chamber) as an ink flow path, a movable film (elastic film) formed on the actuator substrate, and a movable film. Includes the generated piezoelectric element. The inkjet printhead of 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 have. The piezoelectric element is composed of a first electrode film, a second electrode film, and a piezoelectric film (piezoelectric layer) sandwiched between them.

JP-A-2015-91668

Since the inkjet printhead contains a piezoelectric film, the polarization process for aligning the direction of spontaneous polarization of the crystal grains of the piezoelectric film in one direction during the manufacturing process and the amount of displacement of the piezoelectric film with respect to a predetermined drive voltage are stable. Aging is performed to make it. When the polarization process is performed, a voltage is applied to the piezoelectric film. In addition, aging may also be performed by applying a high frequency voltage higher than the normal voltage to the piezoelectric film.

An object of the present invention is to provide an inkjet printhead and a method for manufacturing the same, which facilitates applying a voltage to the piezoelectric film in the manufacturing process.

One embodiment of the present invention is an inkjet printhead, which is an actuator substrate having a plurality of pressure chambers, and a plurality of movable films arranged on the plurality of pressure chambers and partitioning a top surface portion of the plurality of pressure chambers. A plurality of piezoelectric films including a movable film forming layer including the above, a piezoelectric film formed on the plurality of movable films, a lower electrode, a piezoelectric film formed on the lower electrode, and an upper electrode formed on the piezoelectric film. The plurality of upper wirings include an element and a plurality of upper wirings connected to the upper electrodes of the plurality of piezoelectric elements, and the plurality of upper wirings provide an inkjet printhead extending to a side surface of the inkjet printhead.

In this configuration, common wiring connected to a plurality of upper wirings can be formed in the scribe region in the manufacturing process of the inkjet printhead. By using this common wiring, a voltage can be applied to a plurality of piezoelectric elements at the same time, so that it becomes easy to apply a voltage to the piezoelectric film in the manufacturing process.
In one embodiment of the invention, one or more piezoelectric upper electrode pads that are not connected to either the lower electrode or the upper electrode and are used as common pads for the upper electrodes in the manufacturing process. The piezoelectric body processing upper wiring includes the piezoelectric body processing upper electrode connected to the piezoelectric body processing upper electrode pad, and the piezoelectric body processing upper wiring extends to the side surface of the inkjet printhead.

In this configuration, in the manufacturing process of the inkjet print head, a common wiring connected to a plurality of upper wirings and connected to the piezoelectric material processing upper wiring can be formed in the scribe region. As a result, the voltage can be applied to the plurality of piezoelectric elements at the same time by using the upper electrode pad for piezoelectric processing, so that it becomes easy to apply the voltage to the piezoelectric film in the manufacturing process.

In one embodiment of the present invention, an inkjet printhead including a plurality of inkjet printheads is an inkjet printhead manufactured by dying along a piezo region set in the inkjet printhead aggregate. In the state before dying, all the plurality of upper wirings or the plurality of upper wirings in each set in which these are divided into a plurality of sets are the wiring formed in the scribing region and the piezoelectric body treatment. It is connected to any one of the upper electrode pads for processing the piezoelectric body via the upper wiring.

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 the upper surface of the lower electrode, and the hydrogen barrier film formed on the hydrogen barrier film and the hydrogen barrier film and the above. Further includes an insulating film arranged between the upper wiring and the insulating film. A contact hole for exposing a part of the upper electrode is formed in the hydrogen barrier film and the insulating film. One end of the upper wiring is connected to the upper electrode via the contact hole.

In one embodiment of the present invention, the upper wiring includes a first upper wiring having one end connected to the upper electrode and a second upper wiring having one end connected to the other end of the first upper wiring. The other end of the second upper wiring , including the upper wiring , extends to the side surface of the inkjet printhead.
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, the upper surface of the lower electrode, and the upper surface of the second upper wiring , and the hydrogen barrier film. Further includes an insulating film formed on the surface of the hydrogen barrier film and arranged between the hydrogen barrier film and the first upper wiring. The hydrogen barrier film and the insulating film are formed with a first contact hole for exposing a part of the upper electrode and a second contact hole for exposing a part of the second upper wiring . One end of the first upper wiring is connected to the upper electrode via the first contact hole. The other end of the first upper wiring is connected to the second upper wiring through the second contact hole.

One embodiment of the present invention further includes a protective substrate that is bonded to the actuator substrate by an adhesive so as to cover the piezoelectric element. The protective substrate is formed in a housing recess that opens toward the actuator board side and accommodates the piezoelectric element, and outside one end of the housing recess in a plan view, and is formed in one end of the ink flow path. It has an ink supply path that communicates with it.

In one embodiment of the present invention, a nozzle hole is joined to the surface of the actuator substrate on the side opposite to the surface on the movable membrane side by an adhesive to partition the bottom surface of the pressure chamber and communicate with the pressure chamber. Further includes a nozzle substrate having.
One embodiment of the present invention includes an actuator substrate having a plurality of pressure chambers, a plurality of movable membranes for partitioning top surfaces of the plurality of pressure chambers, and a substrate having a plurality of piezoelectric elements formed on the plurality of movable membranes. A method of manufacturing an inkjet printhead including an assembly and a nozzle substrate joined to the substrate assembly and having a plurality of nozzle holes communicating with each of the plurality of pressure chambers, which is the original substrate and surroundings of the actuator substrate. A step of forming a substrate assembly assembly including a plurality of substrate assemblies by using a semiconductor wafer having a plurality of functional element forming regions surrounded by a piezoelectric region, and the substrate assembly assembly includes a plurality of nozzle substrates. A step of forming an inkjet printhead aggregate by joining nozzle substrate aggregates and a step of manufacturing a plurality of inkjet printheads by dying the inkjet printhead aggregate along the piezoelectric region. Including.

The steps of forming the substrate assembly assembly include a first step of forming a movable film forming layer including a plurality of movable film forming regions for each functional element forming region on the semiconductor wafer, and the movable film forming. A plurality of layers including a lower electrode, an upper electrode arranged on the side opposite to the movable film forming layer with respect to the lower electrode, and a piezoelectric film sandwiched therein, on each of the movable film forming regions of the layer. A second step of forming the piezoelectric element of the above, a third step of forming an upper wiring in which one end is connected to each upper electrode included in the movable film forming region, and the functional element forming region. Each includes a fourth step of forming one or more top electrode pads for piezoelectric processing.

In the third step, all the plurality of upper wirings in the functional element forming region or the plurality of upper wirings in each set in which these are divided into a plurality of sets cross the functional element forming region and scribe around the plurality of upper wirings. It extends into the region and is formed so as to be commonly connected by common wiring in the scribe region, and one end of the common wiring is formed so as to extend across the scribe region and into the functional element forming region. Ru. In the fourth step, the piezoelectric material processing upper electrode pad is formed so as to be connected to one end of the common wiring.

In this manufacturing method, a voltage can be applied to a plurality of piezoelectric elements at the same time by using the upper electrode pad for processing the piezoelectric body, so that it becomes easy to apply a voltage to the piezoelectric film in the manufacturing process.

FIG. 1 is a schematic plan view for explaining a configuration of an inkjet print head according to an embodiment of the present invention. FIG. 2 is a schematic partially enlarged plan view showing an enlarged portion A of FIG. 1, and is a plan view including a protective substrate. FIG. 3 is a schematic partially enlarged plan view showing an enlarged portion A of FIG. 1, and is a plan view in which the protective substrate is omitted. FIG. 4 is a schematic cross-sectional view taken along line IV-IV of FIG. FIG. 5 is a schematic cross-sectional view taken along the line VV of FIG. FIG. 6 is a schematic cross-sectional view taken along the line VI-VI of FIG. FIG. 7 is a schematic cross-sectional view taken along the line VII-VII of FIG. FIG. 8 is a schematic plan view showing an example of a pattern of the insulating film of the inkjet print head. FIG. 9 is a schematic plan view showing a pattern example of the passivation film of the inkjet print head. FIG. 10 is a bottom view of the region shown in FIG. 2 of the protective substrate. FIG. 11 is a plan view of the semiconductor wafer as the original substrate of the actuator substrate. FIG. 12 is a schematic plan view showing an assembly of inkjet printheads. FIG. 13 is an enlarged plan view showing a portion B of FIG. 12. FIG. 14 is a schematic cross-sectional view taken along line XIV-XIV of FIG. FIG. 15A is a cross-sectional view showing an example of the manufacturing process of the inkjet print head, and is a cross-sectional view corresponding to the cut surface of FIG. FIG. 15B is a cross-sectional view showing the next step of FIG. 15A. FIG. 15C is a cross-sectional view showing the next step of FIG. 15B. FIG. 15D is a cross-sectional view showing the next step of FIG. 15C. FIG. 15E is a cross-sectional view showing the next step of FIG. 15D. FIG. 15F is a cross-sectional view showing the next step of FIG. 15E. FIG. 15G is a cross-sectional view showing the next step of FIG. 15F. FIG. 15H is a cross-sectional view showing the next step of FIG. 15G. FIG. 15I is a cross-sectional view showing the next step of FIG. 15H. FIG. 15J is a cross-sectional view showing the next step of FIG. 15I. FIG. 15K is a cross-sectional view showing the next step of FIG. 15J. FIG. 15L is a cross-sectional view showing the next step of FIG. 15K. FIG. 15M is a cross-sectional view showing the next step of FIG. 15L. FIG. 16A is a cross-sectional view showing an example of the manufacturing process of the inkjet print head, and is a cross-sectional view corresponding to the cut surface of FIG. FIG. 16B is a cross-sectional view showing the next step of FIG. 16A. FIG. 16C is a cross-sectional view showing the next step of FIG. 16B. FIG. 16D is a cross-sectional view showing the next step of FIG. 16C. FIG. 16E is a cross-sectional view showing the next step of FIG. 16D. FIG. 16F is a cross-sectional view showing the next step of FIG. 16E. FIG. 16G is a cross-sectional view showing the next step of FIG. 16F. FIG. 16H is a cross-sectional view showing the next step of FIG. 16G. FIG. 16I is a cross-sectional view showing the next step of FIG. 16H. FIG. 16J is a cross-sectional view showing the next step of FIG. 16I. FIG. 16K is a cross-sectional view showing the next step of FIG. 16J. FIG. 16L is a cross-sectional view showing the next step of FIG. 16K. FIG. 17 is a cross-sectional view showing a modified example of the upper wiring and the upper wiring for piezoelectric processing, and is a cross-sectional view corresponding to FIG.

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

The configuration of the inkjet print head 1 will be schematically described with reference to FIG.
The inkjet 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. In the following, the actuator board assembly SA will be referred to as a board assembly SA.

The movable film forming layer 10 is laminated on the surface 2a of the actuator substrate 2. An ink flow path (ink pool) 5 is formed on the actuator substrate 2. In this embodiment, the ink flow path 5 is formed so as to penetrate the actuator substrate 2. The ink flow path 5 is formed so as to be elongated along the ink flow direction 41 indicated by the arrow in FIG. The ink flow path 5 is composed of an ink inflow portion 6 at the upstream end (left end in FIG. 4) in the ink flow direction 41 and a pressure chamber 7 communicating with the ink inflow portion 6. In FIG. 4, the boundary between the ink inflow portion 6 and the pressure chamber 7 is indicated by a chain double-dashed line.

The nozzle substrate 3 includes, for example, a silicon (Si) substrate 30, a silicon oxide (SiO ₂ ) film 31 formed on the front surface (back surface) of the silicon substrate 30 opposite to the pressure chamber 7, and a silicon oxide film 31. It is composed of a water-repellent film 32 formed on the surface 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 film thickness of the silicon oxide film 31 is about 0.1 μm, and the film thickness of the water repellent film 32 is about 0.1 μm.

The nozzle substrate 3 is attached to the back surface 2b of the actuator substrate 2 with the front surface of the silicon substrate 30 facing the back surface 2b 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 partitions the bottom surface portion of the ink flow path 5.
A nozzle hole 20 is formed in the nozzle substrate 3. The nozzle hole 20 includes a recess 20a facing the pressure chamber 7 and an ink ejection passage 20b formed on the bottom surface of the recess 20a. The ink ejection passage 20b penetrates the bottom wall of the recess 20a and has an ink ejection port 20c on the side opposite to the pressure chamber 7. Therefore, when the volume of the pressure chamber 7 changes, 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 recess 20a is formed in a truncated cone shape in which the cross section gradually decreases from the surface of the silicon substrate 30 toward the silicon oxide film 31 side. The ink ejection passage 20b is composed of straight holes having a circular cross section. In this embodiment, the recess 20a is formed halfway through the thickness of the silicon substrate 30, and the ink ejection 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 that 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) is, for example, on 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. It may be composed of a laminated film with a silicon nitride (SiN) film to be formed. In this specification, the movable film 10A means a top wall portion of the movable film forming layer 10 that partitions the top surface portion of the pressure chamber 7. Therefore, the portion of the movable film forming layer 10 other than the top wall portion of the pressure chamber 7 does not form the movable film 10A.

The thickness of the movable membrane 10A is, for example, 0.4 μm to 2 μm. When the movable film 10A is composed 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 each about 0.4 μm. May be good.

The pressure chamber 7 is partitioned by a movable film 10A, an actuator substrate 2, and a nozzle substrate 3, and in this embodiment, the pressure chamber 7 is formed in a substantially rectangular parallelepiped shape. The length of the pressure chamber 7 may be, for example, about 800 μm, and the width thereof may be about 55 μm. The ink inflow portion 6 communicates with one end of the pressure chamber 7 in the longitudinal direction.
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, the piezoelectric element 9 is arranged 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 between the upper electrode 13 and the lower electrode 11 from above and below.

The upper electrode 13 may be a single film of platinum (Pt), and for example, a conductive oxide film (for example, IrO ₂ (iridium oxide) film) and a metal film (for example, Ir (iridium) film) are laminated. It may have a laminated structure. 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 a metal oxide crystal. The piezoelectric film 12 is formed to have the same shape as the upper electrode 13 in a plan view. The thickness of the piezoelectric film 12 is about 1 μm. The total thickness of the movable film 10A 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 metal barrier film 8 described above mainly prevents metal elements (Pb, Zr, Ti when the piezoelectric film 12 is PZT) from coming out from the piezoelectric film 12, and improves the piezoelectric characteristics of the piezoelectric film 12. At the same time, it 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 deterioration of the characteristics of the piezoelectric film 12 due to hydrogen reduction.

The lower electrode 11 has, for example, a two-layer structure in which a Ti (titanium) film and a Pt (platinum) film are laminated in order from the metal barrier film 8 side. In addition to this, the lower electrode 11 can also 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 in contact with the lower surface of the piezoelectric film 12 and an extension portion 11B extending to an outer region of the piezoelectric film 12. The thickness of the lower electrode 11 may be, for example, about 0.2 μm.

A hydrogen barrier film 14 is formed on the piezoelectric element 9, the extension portion 11B 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 to prevent deterioration of the characteristics of the piezoelectric film 12 due to hydrogen reduction.
The insulating film 15 is laminated on the hydrogen barrier film 14. The insulating film 15 is made of, for example, SiO ₂ , low hydrogen SiN, or the like. The thickness of the insulating film 15 is about 500 nm. On the insulating film 15, the lower wiring 16 (see FIGS. 2 and 6), the upper wiring 17, the lower wiring for piezoelectric processing 18 (see FIGS. 2 and 7), and the upper wiring 19 for piezoelectric processing (FIG. 2, FIG. (See FIG. 7) is 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 arranged above one end of the upper electrode 13 (downstream end in the ink distribution direction 41). A contact hole 27 is formed between the upper wiring 17 and the upper electrode 13 so as to continuously penetrate the hydrogen barrier film 14 and the insulating film 15. One end of the upper wiring 17 enters the contact hole 27 and is connected to the upper electrode 13 in the contact hole 27. The upper wiring 17 extends from above the upper electrode 13 to the outside of the pressure chamber 7 across the outer edge of the pressure chamber 7. The other end of the upper wiring 17 reaches the side surface of the inkjet print head 1. The lower wiring 16, the lower wiring 18 for piezoelectric processing, and the upper wiring 19 for piezoelectric processing will be described later.

On the insulating film 15, a lower wiring 16, an upper wiring 17, a lower wiring 18 for piezoelectric processing, an upper wiring 19 for piezoelectric processing, and a passivation film 21 covering the insulating film 15 are formed. The passivation film 21 is made of, for example, SiN (silicon nitride). The thickness of the passivation film 21 may be, for example, about 800 nm.
The passivation film 21 is formed with a pad opening 37 that exposes a part of the upper wiring 17. The pad opening 37 is formed in the outer region of the pressure chamber 7, for example, in the middle portion of the length of the upper wiring 17. An upper electrode pad 47 covering the pad opening 37 is formed on the passivation film 21. The upper electrode pad 47 enters the pad opening 37 and is connected to the upper wiring 17 in the pad opening 37.

For the lower wiring 16, the lower wiring 18 for piezoelectric processing, and the upper wiring 19 for piezoelectric processing, the lower electrode pad 46, the lower electrode pad 48 for piezoelectric processing, and the upper electrode pad 49 for piezoelectric processing are also shown (FIG. 2) is provided, but those pads will be described later.
Ink penetrating 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 positions corresponding to the ends of the ink flow path 5 on the ink inflow portion 6 side. A through hole 22 for supply 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 has entered 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 arranged 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 a housing recess 52 on a facing surface 51 facing the substrate assembly SA. The piezoelectric element 9 is housed in the storage recess 52. Further, 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 46 to 49. The ink supply path 53 and the opening 54 penetrate the protective substrate 4. An ink tank (not shown) for storing ink is arranged 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 so as to be in contact with the surface of the metal barrier film 8 opposite to the pressure chamber 7. The pressure chamber 7 is filled with ink 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 movable film 10A partitions the top surface of the pressure chamber 7 and faces the pressure chamber 7. The movable membrane 10A is supported by a portion of the actuator substrate 2 around the pressure chamber 7, and has flexibility that can be deformed in the direction facing the pressure chamber 7 (in other words, the thickness direction of the movable membrane 10A). doing.

The lower wiring 16 (see FIGS. 2 and 6) and the upper wiring 17 are connected to a drive circuit (not shown). Specifically, the upper electrode pad 47 and the drive circuit are connected via a connecting metal member (not shown). The lower electrode pad 46 (see FIGS. 2 and 6) and the drive circuit are connected via a connecting 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, which causes a change in the volume of the pressure chamber 7 and pressurizes the ink in the pressure chamber 7. The pressurized ink passes through the ink ejection passage 20b and is ejected as fine droplets from the ink ejection port 20c.

The configuration of the inkjet print head 1 will be described in more detail with reference to FIGS. 1 to 7. In the following description, the left side of FIG. 1 is referred to as “left”, the right side of FIG. 1 is referred to as “right”, the lower side of FIG. 1 is referred to as “front”, and the upper side of FIG. 1 is referred to as “rear”.
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 at intervals in the front-rear direction are arranged at intervals in the left-right direction in a plan view. There are rows. In this embodiment, for convenience of explanation, it is assumed that two rows of piezoelectric elements are provided.
As shown in FIGS. 2 and 3, an ink flow path 5 (pressure chamber 7) is formed on the actuator substrate 2 for each piezoelectric element. Therefore, in the plan view, the actuator substrate 2 has ink flow path rows (pressure chamber rows) composed of a plurality of ink flow paths 5 (pressure chambers 7) arranged in stripes at intervals in the front-rear direction. Two rows are provided with an interval in the direction.

The pattern of the ink flow path row corresponding to the piezoelectric element row on the left side of FIG. 1 and the pattern of the ink flow path row corresponding to the piezoelectric element row on the right side are symmetrical with respect to the line segment connecting the centers between the rows. It is a pattern of. Therefore, in the ink flow path 5 included in the ink flow path row on the left side, 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 ink flow path row on the right side is included. The ink inflow portion 6 is on the left side with respect to the pressure chamber 7. Therefore, in the ink flow path row on the left side and the ink flow path row on the right side, the ink flow directions 41 are opposite to each other.

Ink supply through holes 22 are provided for each of the plurality of ink flow paths 5 in each ink flow path row. The ink supply through hole 22 is arranged on the ink inflow portion 6. Therefore, the ink supply through hole 22 for the ink flow path 5 included in the ink flow path row on the left side is arranged on the right end portion of the ink flow path 5, and is provided for the ink flow path 5 included in the ink flow path row on the right side. The ink supply through hole 22 is arranged 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 extends elongated along the ink flow 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 along the ink flow direction 41 in a plan view. That is, the top surface portion of the pressure chamber 7 has two side edges along the ink flow direction 41 and two edge edges along the direction orthogonal to the ink flow direction 41. The ink inflow portion 6 has substantially the same width as the pressure chamber 7 in a 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 a plan view. The ink supply through hole 22 has a circular shape in a plan view (see particularly FIG. 3).

The piezoelectric element 9 has a rectangular shape that is long in the longitudinal direction of the pressure chamber 7 (movable membrane 10A) in a plan view. The length of the piezoelectric element 9 in the longitudinal direction is shorter than the length of the pressure chamber 7 (movable membrane 10A) in the longitudinal direction. As shown in FIG. 3, both end edges of the piezoelectric element 9 along the lateral direction are arranged inside the movable film 10A at predetermined intervals with respect to the corresponding end edges. Further, the width of the piezoelectric element 9 in the lateral direction is narrower than the width of the movable film 10A in the lateral direction. Both side edges of the piezoelectric element 9 along the longitudinal direction are arranged inside the movable film 10A at predetermined intervals with respect to the corresponding side edges.

The lower electrode 11 is formed on almost the entire surface of the movable film forming layer 10 except for the peripheral edge of the surface of the movable film forming layer 10. The lower electrode 11 is a common electrode shared by a plurality of piezoelectric elements 9. The lower electrode 11 is drawn out from the main electrode portion 11A having a rectangular shape in a plan view and the main electrode portion 11A constituting the piezoelectric element 9 in the direction along the surface of the movable film forming layer 10, and is located on the peripheral edge of the top surface portion of the pressure chamber 7. It includes an extension 11B extending outward.

The length of the main electrode portion 11A in the longitudinal direction is shorter than the length of the movable film 10A in the longitudinal direction. Both end edges of the main electrode portion 11A are arranged inside the movable film 10A at predetermined intervals with respect to the corresponding end edges. Further, the width of the main electrode portion 11A in the lateral direction is narrower than the width of the movable film 10A in the lateral direction. Both side edges of the main electrode portion 11A are arranged inside the movable film 10A at predetermined intervals with respect to the corresponding side edges. The extension portion 11B is a region of the entire region of the lower electrode 11 excluding the main electrode portion 11A.

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

The piezoelectric film 12 is formed in a rectangular shape having the same pattern as the upper electrode 13 in a plan view. That is, the length of the piezoelectric film 12 in the longitudinal direction is shorter than the length of the movable membrane 10A in the longitudinal direction. Both end edges of the piezoelectric film 12 are arranged inside the movable film 10A at predetermined intervals with respect to the corresponding end edges. Further, the width of the piezoelectric film 12 in the lateral direction is narrower than the width of the movable membrane 10A in the lateral direction. Both side edges of the piezoelectric film 12 are arranged inside the movable film 10A at predetermined intervals with respect to the corresponding side edges. The lower surface of the piezoelectric film 12 is in contact with the upper surface of the main electrode portion 11A 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 (the end on the downstream side in the ink flow direction 41) along the end face of the piezoelectric element 9 connected thereto, and further along the surface of the extension 11B of the lower electrode 11. Therefore, it extends in the direction along the ink flow direction 41. Regarding the piezoelectric element 9 in the piezoelectric element row on the left side of FIG. 1, one end of the upper wiring 17 is connected to the left end portion of the piezoelectric element 9, and the other end portion extends to the left side surface of the inkjet print head 1 and is on the left side. It is exposed on the surface. On the other hand, regarding the piezoelectric element 9 in the piezoelectric element row on the right side of FIG. 1, one end of the upper wiring 17 is connected to the right end portion of the piezoelectric element 9, and the other end portion extends to the right side surface of the inkjet print head 1. Is exposed on the right side.

The passivation film 21 is formed with a pad opening 37 that exposes the central portion of the surface of the intermediate portion of the length of the upper wiring 17. An upper electrode pad 47 is provided on the passivation film 21 so as to cover the pad opening 37. The upper electrode pad 47 is connected to the upper wiring 17 in the pad opening 37. As shown in FIG. 1, the plurality of upper electrode pads 47 corresponding to the plurality of piezoelectric elements 9 in the left piezoelectric element row are arranged in a row in the front-rear direction on the left side of the left piezoelectric element row in a plan view. They are arranged side by side. Further, the plurality of upper electrode pads 47 corresponding to the plurality of piezoelectric elements 9 in the right piezoelectric element row are arranged in a row in the front-rear direction on the right side of the right piezoelectric element row in a plan view. There is.

With reference to FIGS. 1, 2, 3 and 6, the lower wiring 16 is arranged at the rear position of the left upper electrode pad row and the rear position of the right upper electrode pad row in a plan view, respectively. ing. The lower wiring 16 has a rectangular shape in a plan view. Below the lower wiring 16, there is an extension portion 11B of the lower electrode 11. A contact hole 26 that continuously penetrates the hydrogen barrier film 14 and the insulating film 15 is formed between the lower wiring 16 and the extension portion 11B of the lower electrode 11. The lower wiring 16 enters the contact hole 26 and is connected to the extension portion 11B of the lower electrode 11 in the contact hole 26.

The passivation film 21 is formed with a pad opening 36 that exposes the central portion of the surface of the lower wiring 16. On the passivation film 21, a lower electrode pad 46 covering the pad opening 36 is formed. The lower electrode pad 46 enters the pad opening 36 and is connected to the lower wiring 16 in the pad opening 36.
With reference to FIGS. 1, 2, 3 and 7, the piezoelectric processing lower wiring 18 is located at the rear position of the left lower electrode pad 46 and the rear position of the right lower electrode pad 46 in a plan view. It is arranged in each. The lower wiring 18 for piezoelectric processing has a rectangular shape in a plan view. An extension portion 11B of the lower electrode 11 exists below the lower wiring 18 for piezoelectric processing. A contact hole 28 that continuously penetrates the hydrogen barrier film 14 and the insulating film 15 is formed between the piezoelectric material processing lower wiring 18 and the extension portion 11B of the lower electrode 11. The piezoelectric material processing lower wiring 18 enters the contact hole 28 and is connected to the extension portion 11B of the lower electrode 11 in the contact hole 28.

The passivation film 21 is formed with a pad opening 38 that exposes the central portion of the surface of the piezoelectric material processing lower wiring 18. On the passivation film 21, a lower electrode pad 48 for piezoelectric treatment that covers the pad opening 38 is formed. The lower electrode pad 48 for processing the piezoelectric material enters the pad opening 38 and is connected to the lower wiring 18 for processing the piezoelectric material in the pad opening 38.

With reference to FIGS. 1, 2, 3 and 7, the piezoelectric processing upper wiring 19 is the left position of the piezoelectric processing lower electrode pad 48 on the left side and the piezoelectric material processing lower portion on the right side in a plan view. They are arranged at the right positions of the electrode pads 48, respectively. The upper wiring 19 for piezoelectric processing on the right side is an inkjet print head from the intermediate portion between the pad portion 19a having a rectangular shape in a plan view arranged to the right of the lower electrode pad 48 for piezoelectric processing on the right side and the right side of the pad portion 19a. 1 includes a wiring portion 19b that extends to the right side surface and is exposed on the right side surface. Similarly, the upper wiring 19 for piezoelectric processing on the left side is inkjet printed from a rectangular pad portion in a plan view arranged to the left of the lower electrode pad 48 for piezoelectric processing on the left side and an intermediate portion on the left side of the pad portion. Includes a wiring portion that extends to the left side surface of the head 1 and is exposed on the left side surface.

The passivation film 21 is formed with a pad opening 39 that exposes the central portion of the surface of the pad portion 19a of the piezoelectric material processing upper wiring 19. On the passivation film 21, an upper electrode pad 49 for processing a piezoelectric material that covers the pad opening 39 is formed. The piezoelectric material processing upper electrode pad 49 enters the pad opening 39 and is connected to the piezoelectric material processing upper wiring 19 in the pad opening 39.

As shown in FIGS. 1, 2 and 4, the protective substrate 4 has a plurality of ink supply paths 53 (hereinafter, "first") communicating with a plurality of ink supply through holes 22 for the ink flow path row on the left side. Ink supply path 53 ”) and a plurality of ink supply paths 53 (hereinafter referred to as“ second ink supply path 53 ”” communicating with a plurality of ink supply through holes 22 for the ink flow path row on the right side. There is) and is formed. The first ink supply passages 53 are arranged in a row at positions shifted to the left with respect to the center of the width of the protective substrate 4 in the front-rear direction at intervals in the front-rear direction. The second ink supply passages 53 are arranged in a row at positions shifted to the right with respect to the center of the width of the protective substrate 4 in the front-rear direction at intervals in the front-rear direction. The ink supply path 53 has a circular shape having the same pattern as the ink supply through hole 22 on the actuator substrate 2 side in a plan view. The ink supply path 53 is aligned with the ink supply through hole 22 in a plan view.

Further, on the protective substrate 4, all the upper electrode pads 47 corresponding to the piezoelectric element row on the left side, the lower electrode pad 46 on the left side, the lower electrode pad 48 for piezoelectric material processing, and the upper electrode pad 49 for piezoelectric material processing are provided. An opening 54 for exposing is formed. Further, on the protective substrate 4, all the upper electrode pads 47 corresponding to the right piezoelectric element row, the right lower electrode pad 46, the piezoelectric lower electrode pad 48, and the piezoelectric upper electrode pad 49 are provided. An opening 54 for exposing is formed. These openings 54 have a rectangular shape that is long in the front-rear direction in a plan view.

FIG. 10 is a bottom view of the region shown in FIG. 2 of the protective substrate.
As shown in FIGS. 4, 5 and 10, the accommodating recess 52 is formed on the facing surface 51 of the protective substrate 4 at a position facing the piezoelectric element 9 in each piezoelectric element row. An ink supply path 53 is arranged on the upstream side of the ink distribution direction 41 and an opening 54 is arranged on the downstream side of each storage recess 52. Each accommodation recess 52 is formed in a rectangular shape slightly larger than the pattern of the upper electrode 13 of the corresponding piezoelectric element 9 in a plan view. The corresponding piezoelectric element 9 is accommodated in each accommodating recess 52.

FIG. 8 is a schematic plan view showing an example of a pattern of the insulating film of the inkjet print head. FIG. 9 is a schematic plan view showing a pattern example of the passivation film of the inkjet print head.
In this embodiment, the insulating film 15 and the passivation film 21 are formed on the actuator substrate 2 in substantially the entire outer region of the accommodating recess 52 of the protective substrate 4 in a plan view. However, in this region, the insulating film 15 is formed with ink supply through holes 22 and contact holes 26, 28. In this region, the passivation film 21 is formed with ink supply through holes 22 and pad openings 36 to 39.

In the inner region of the accommodating 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 insulating film 15 and the passivation film 21 are formed with an opening 40 in the inner region of the accommodating recess 52 in a plan view, excluding the upper wiring region. A contact hole 27 is further formed in the insulating film 15.

The outline of the manufacturing method of the inkjet print head 1 will be described.
FIG. 11 is a plan view of the semiconductor wafer as the original substrate of the actuator substrate, and a part of the region is enlarged and shown.
The semiconductor wafer (actuator wafer) 100 as the original substrate of the actuator substrate 2 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. A plurality of functional element forming regions 101 are arranged and set in a matrix on the surface 100a of the actuator wafer 100. A scribe region (boundary region) 102 is provided between the adjacent functional element forming regions 101. The scribe region 102 is a strip-shaped region having a substantially constant width, and extends in two orthogonal directions and is formed in a grid pattern. The planned cutting line 103 is set in the scribe area 102. Although the ink flow path 5 is not formed by performing the necessary steps on the actuator wafer 100, the substrate assembly assembly (SA assembly) in which the configuration of the substrate assembly SA is formed on each functional element forming region 101. ) 110 is created.

A protective substrate assembly 130 (see FIGS. 15K and 16J) including a plurality of protective substrates 4 integrally corresponding to each functional element forming region 101 of the substrate assembly assembly 110 is prepared in advance. The protective substrate assembly 130 is created by performing necessary steps on a semiconductor wafer (wafer for a protective substrate) as the original substrate of the protective substrate 4. The wafer for the protective substrate is made of, for example, a silicon wafer.

Further, a nozzle substrate assembly 150 (see FIGS. 15M and 16L) including a plurality of nozzle substrates 3 integrally corresponding to each functional element forming region 101 of the substrate assembly assembly 110 is prepared in advance. The nozzle substrate assembly 150 is created by performing necessary steps on a semiconductor wafer (nozzle wafer) as a source substrate of the nozzle substrate 3. The nozzle wafer is made of, for example, a silicon wafer. As shown in FIGS. 15M and 16L, the nozzle substrate assembly 150 was formed on the surface of the nozzle wafer 140, the silicon oxide (SiO ₂ ) film 142 formed on one surface of the nozzle wafer 140, and the silicon oxide film 142. It is composed of a water repellent film 143.

When the substrate assembly assembly 110 is created, the protective substrate assembly 130 is joined to the substrate assembly assembly 110. Next, the ink flow path 5 is formed in the substrate assembly assembly 110. Next, the nozzle substrate assembly 150 is joined to the substrate assembly assembly 110. As a result, an inkjet printhead assembly 170 including a substrate assembly assembly 110, a protective substrate assembly 130, and a nozzle substrate assembly 150 can be obtained. After that, the inkjet printhead assembly 170 is cut (diced) by a dicing blade along the planned cutting line 103. As a result, each inkjet printhead (chip) 1 including the functional element forming region 101 is cut out. The inkjet print head 1 has a scribe region 102 at the peripheral edge portion, and has a functional element forming region 101 in a central region surrounded by the scribe region 102.

FIG. 12 is a partial plan view illustrating a part of the assembly of the inkjet print heads.
As described above, the inkjet printhead assembly 170 is formed on the substrate assembly assembly 110 including the actuator wafer 100, the protective substrate assembly 130 joined to the front surface of the substrate assembly assembly 110, and the back surface of the substrate assembly assembly 110. It is composed of a bonded nozzle substrate assembly 150.

Although not shown in FIG. 12, each functional element forming region 101 of the actuator wafer 100 is formed with the movable film forming layer 10, the piezoelectric element 9, wirings 16 to 19, and the like described above. On the other hand, wiring and the like are formed in the scribe region 102 of the actuator wafer 100, although not shown in FIG.
FIG. 13 is an enlarged plan view showing a portion B of FIG. 12. FIG. 14 is a schematic cross-sectional view taken along line XIV-XIV of FIG.

In FIG. 13, reference numeral 104 indicates a planned removal area set in the scribe area 102. The planned removal region 104 is a region to be removed by dicing, and is a region having a predetermined width at the center of the width of the scribe region 102. The portion surrounded by the area to be removed 104 becomes the inkjet print head 1 after dicing.
The left half (left side) of the planned removal region 104 along the right side of the functional element forming region 101 is connected to the right end of a plurality of upper wirings 17 corresponding to the right piezoelectric element trains on the functional element forming region 101. A plurality of first upper extension wirings 17-1 and one first common wiring 17-2 to which the tip portions (right end portions) of the first upper extension wirings 17-1 are connected are formed. The first upper extension wiring 17-1 extends in the left-right direction, and the first common wiring 17-2 extends in the front-rear direction. The rear end portion of the first common wiring 17-2 extends to the right side of the piezoelectric body processing upper electrode pad 48 corresponding to the piezoelectric element row, and bends to the left from there to correspond to the piezoelectric element row. It is connected to the right end of the upper wiring 19 for piezoelectric processing. The first upper extension wiring 17-1 and the first common wiring 17-2 are integrally formed with a plurality of upper wirings 17 to which they are connected and an upper wiring 19 for processing a piezoelectric material.

The right half (right side) of the planned removal region 104 along the left side of the functional element forming region 101 is connected to the left end of a plurality of upper wirings 17 corresponding to the left piezoelectric element trains on the functional element forming region 101. A plurality of second upper extension wirings 17-1 and one second common wiring 17-2 to which the tip end portion (left end portion) of the second upper extension wiring 17-1 is connected are formed. The second upper extension wiring 17-1 extends in the left-right direction, and the second common wiring 17-2 extends in the front-rear direction. The rear end portion of the second common wiring 17-2 extends to the left of the piezoelectric body processing upper electrode pad 48 corresponding to the piezoelectric element row, and bends to the right from there to correspond to the piezoelectric element row. It is connected to the upper wiring 19 for piezoelectric processing. The second upper extension wiring 17-1 and the second common wiring 17-2 are integrally formed with a plurality of upper wirings 17 to which they are connected.

In the inkjet printhead assembly 170, the upper electrodes 13 of all the piezoelectric elements 9 in the right piezoelectric element row formed on each functional element forming region 101 are the upper wiring 17 and the first upper extension wiring 17-1. , Is connected to the right upper electrode pad 49 for piezoelectric processing via the first common wiring 17-2 and the upper wiring 19 for piezoelectric processing on the right side. Further, the lower electrodes 11 (main electrode portions 11A) of all the piezoelectric elements 9 in the right piezoelectric element row are connected to the right piezoelectric processing lower electrode pad 48 via the right piezoelectric processing lower wiring 18. It is connected.

On the other hand, the upper electrodes 13 of all the piezoelectric elements 9 in the left piezoelectric element row formed on each functional element forming region 101 are the upper wiring 17, the second upper extension wiring 17-1, and the second common wiring 17-. It is connected to the upper electrode pad 49 for piezoelectric processing on the left side via 2 and the upper wiring 19 for piezoelectric processing on the left side. Further, the lower electrodes 11 (main electrode portion 11A) of all the piezoelectric elements 9 in the piezoelectric element row on the left side are connected to the lower electrode pad 48 for piezoelectric processing on the left side via the lower wiring 18 for piezoelectric processing on the left side. It is connected.

In this embodiment, before the inkjet printhead assembly 170 is individually processed by dicing, a polarization treatment for aligning the spontaneous polarization direction of the crystal grains of the piezoelectric film in one direction, or a polarizing body film is performed. Aging is performed to stabilize the amount of displacement of the above with respect to a predetermined drive voltage. In this embodiment, the polarization treatment and aging are performed by applying a voltage to the piezoelectric membrane. The voltage is applied to the piezoelectric film as follows. That is, with respect to the piezoelectric film 12 of the piezoelectric element 9 in the piezoelectric element row on the left side formed on each functional element forming region 101, the upper electrode pad 49 for piezoelectric processing and the lower electrode for piezoelectric processing on the left side. The voltage is applied using the pad 48. Further, with respect to the piezoelectric film 12 of the piezoelectric element 9 in the piezoelectric element row on the right side formed on each functional element forming region 101, the upper electrode pad 49 for piezoelectric processing and the lower electrode for piezoelectric processing on the right side The voltage is applied using the pad 48. Since a voltage can be applied to a set of a plurality of piezoelectric elements 9 (a row of piezoelectric elements in this embodiment) by using a pair of electrode pads, it becomes easy to apply a voltage to the piezoelectric film in the manufacturing process.

Hereinafter, the manufacturing method of the inkjet print head 1 will be specifically described.
15A to 15M are cross-sectional views showing a manufacturing process of the inkjet printhead 1, and are cross-sectional views corresponding to the cut surface of FIG. 16A to 16L are cross-sectional views showing a manufacturing process of the inkjet printhead 1, and are cross-sectional views corresponding to the cut surface of FIG.
First, as shown in FIGS. 15A and 16A, the actuator wafer 100 is prepared. However, as the actuator wafer 100, a wafer thicker than the thickness of the final actuator substrate 2 is used. Then, the movable film forming layer 10 is formed on the surface 100a of the actuator wafer 100. Specifically, a silicon oxide film (for example, 1.2 μm thickness) is formed on the surface 100a 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 thickness) is formed on the surface of the actuator substrate 2, and the silicon film is formed. A silicon oxide film (for example, 0.4 μm thickness) is formed on the silicon oxide film, 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, a thickness of 50 nm to 100 nm). The metal barrier film 8 prevents metal atoms from coming out of the piezoelectric film 12 which is formed later. If the metal electrons escape, the piezoelectric characteristics of the piezoelectric film 12 may deteriorate. Further, if the escaped metal atoms are mixed in the silicon layer constituting the movable film 10A, the durability of the movable film 10A may deteriorate.

Next, as shown in FIGS. 15B and 16B, the lower electrode film 71, which is the material layer of the lower electrode 11, is formed on the metal barrier film 8. The lower electrode film 71 is composed of, for example, a Pt / Ti laminated film having a Ti film (for example, 10 nm to 40 nm thick) as a lower layer and a Pt film (for example, 10 nm to 400 nm thick) as an upper layer. Such a lower electrode film 71 may be formed by a sputtering method.

Next, the 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 the sol-gel method. Such a piezoelectric material film 72 is made of a sintered body of metal oxide crystal grains.
Next, the upper electrode film 73, which is the 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, for example, a single film of platinum (Pt). The upper electrode film 73 is, for example, on the lower layer IrO ₂ film (e.g. 40nm~160nm thick), may be _Ir0 2 / Ir laminated film of the Ir film (e.g. 40nm~160nm thickness) as an upper layer. Such an upper electrode film 73 may be formed by a sputtering method.

Next, as shown in FIGS. 15C and 16C and FIGS. 15D and 16D, the upper electrode film 73, the piezoelectric material film 72, and the lower electrode film 71 are patterned. First, photolithography forms a resist mask with a pattern of the upper electrode 13. Then, as shown in FIGS. 15C and 16C, the upper electrode film 73 and the piezoelectric material film 72 are continuously etched by using this resist mask as a mask, so that the upper electrode 13 and the piezoelectric film 12 having a predetermined pattern are continuously etched. Is formed.

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 FIGS. 15D and 16D, the lower electrode film 71 is etched using this resist mask as a mask to form the lower electrode 11 having a predetermined pattern. As a result, the lower electrode 11 including the main electrode portion 11A and the extension portion 11B having the through hole 23 is formed. In this way, 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 FIGS. 15E and 16E, after the resist mask is peeled off, 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. After that, the 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 thereof may be 200 nm to 300 nm. Subsequently, the insulating film 15 and the hydrogen barrier film 14 are continuously etched to form the contact holes 26, 27, 28.

Next, as shown in FIGS. 15F and 16F, the lower wiring 16, the upper wiring 17, the lower wiring 18 for piezoelectric processing, and the piezoelectric material are placed on the insulating film 15 including the contact holes 26, 27, and 28 by the sputtering method. A wiring film constituting the upper wiring 19 for body processing, the upper extension wiring 17-1 and the common wiring 17-2 is formed. After that, the wiring film is patterned by photolithography and etching, so that the lower wiring 16, the upper wiring 17, the lower wiring for piezoelectric processing 18, the upper wiring 19 for piezoelectric processing, and the upper extension wiring 17-1 are common. Wiring 17-2 is formed at the same time.

Next, as shown in FIGS. 15G and 16G, a passivation film 21 covering each of the wirings 16, 17, 18, 19, 17-1, and 17-2 is formed on the surface of the insulating film 15. The passivation film 21 is made of, for example, SiN. The passivation film 21 is formed by, for example, plasma CVD.
Next, a resist mask having openings corresponding to the pad openings 36 to 39 is formed by photolithography, and the passivation film 21 is etched using this resist mask as a mask. As a result, pad openings 36 to 39 are formed in the passivation film 21 as shown in FIGS. 15H and 16H. After the resist mask is peeled off, the lower electrode pad 46, the upper electrode pad 47, the piezoelectric material processing lower electrode pad 48, and the piezoelectric material are provided on the passivation film 21 via the pad openings 36, 37, 38, and 39, respectively. The upper electrode pad 49 for processing is formed.

Next, a resist mask having an opening corresponding to the opening 40 and the through hole 22 for ink supply is formed by photolithography, and the passivation film 21 and the insulating film 15 are continuously etched using this resist mask as a mask. As a result, as shown in FIGS. 15I and 16I, the opening 40 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 this resist mask as a mask. As a result, as shown in FIG. 15J, the ink supply through holes 22 are formed in the hydrogen barrier film 14, the metal barrier film 8, and the movable film forming layer 10. As a result, the board assembly assembly 110 is created.

Next, as shown in FIGS. 15K and 16J, 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 are aligned with each other. , The protective board assembly 130 is fixed to the board assembly assembly 110.
Next, as shown in FIGS. 15L and 16K, backside 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. After that, 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 is used as a mask. 100 is etched from the back surface 100b. As a result, the ink flow path 5 (ink inflow portion 6 and pressure chamber 7) is formed in the actuator wafer 100.

At the time of 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 coming out from the piezoelectric film 12, and the piezoelectric material. 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 forming the movable film 10A.
After that, as shown in FIGS. 15M and 16L, the nozzle substrate assembly 150 is attached to the back surface 100b of the actuator wafer 100. As a result, an inkjet printhead assembly 170 including a substrate assembly assembly 110, a protective substrate assembly 130, and a nozzle substrate assembly 150 can be obtained. After that, the inkjet printhead assembly 170 is cut by the dicing blade along the planned cutting line 103. That is, a step for individually cutting out the inkjet print head 1 is performed. As a result, the area 104 to be removed in the scribe area 102 is removed. Therefore, the upper extension wiring 17-1 and the common wiring 17-2 formed in the planned removal area 104 are removed.

When this step is completed, the actuator wafer 100 in the substrate assembly assembly 110 becomes the actuator substrate 2 of each inkjet printhead 1. Further, the protective substrate assembly 130 becomes a protective substrate 4 of each inkjet print head 1. Further, 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 inkjet printhead 1, respectively. .. In this way, individual pieces of the inkjet print head 1 having the structure shown in FIGS. 1 to 7 can be obtained.

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

In the method for manufacturing an inkjet printhead according to this embodiment, the inkjet printhead assembly 170 is created by joining the nozzle substrate assembly 150 to the substrate assembly assembly 110 to which the protective substrate assembly 130 is fixed. Then, the inkjet print head assembly 170 is diced, so that the inkjet print head 1 is individually cut out. Therefore, for example, the inkjet printhead 1 is manufactured more efficiently than the case where the nozzle substrate 3 is individually bonded to the individual substrate assembly SA after the individual substrate assembly SA is manufactured to manufacture the inkjet printhead. You will be able to do it.

FIG. 17 is a cross-sectional view showing a modified example of the upper extension wiring and the common wiring, and is a cross-sectional view corresponding to the cross-sectional view of FIG.
In this modification, the dummy lower electrode 211 and the dummy piezoelectric film 212 are formed in the vicinity of the boundary portion in the left-right direction of the two functional element forming regions 101 adjacent to each other in the left-right direction, straddling the planned removal region 104. .. The dummy lower electrode 211 is an electrode formed of the same material as the lower electrode 11 and in the same process, but is not connected to the lower electrode 11. Further, the dummy piezoelectric film 212 is a piezoelectric film formed by the same material and the same process as the piezoelectric film 12, but not connected to the piezoelectric film 12.

A second upper wiring 13-3, an upper extension wiring 13-1 and a common wiring 13-2 made of a dummy upper electrode are formed on the dummy piezoelectric film 212. The dummy upper electrode is an electrode formed of the same material as the upper electrode 13 and in the same process, but is not connected to the upper electrode 13. The plan view patterns of the upper extension wiring 13-1 and the common wiring 13-2 are the same as those of the upper extension wiring 17-1 and the common wiring 17-2 shown in FIG. 13, respectively.

In this modification, as shown in FIG. 17, in the right end portion of the functional element forming region 101, the right end portion of the upper wiring (first upper wiring) 17 does not reach the planned removal region 104, but the second It extends above the upper wiring 13-3. A hydrogen barrier film 14 and an insulating film 15 exist between the second upper wiring 13-3 and the upper wiring (first upper wiring) 17. A contact hole 227 that continuously penetrates the hydrogen barrier film 14 and the insulating film 15 is formed between the upper wiring 17 and the second upper wiring 13-3. One end of the upper wiring 17 enters the contact hole 227 and is connected to the second upper wiring 13-3 in the contact hole 227.

The right end of the second upper wiring 13-3 extends to the area 104 to be removed on the right side of the functional element forming region 101, and is integrally connected to the upper extension wiring 13-1. The common wiring 13-2 and the piezoelectric material processing upper wiring 19 (see FIG. 13) are connected by a connection form similar to the connection form of the upper wiring 17 and the second upper wiring 13-3.
Although not shown, the left side portion of the functional element forming region 101 and the scribe region 102 on the left side thereof (scheduled removal region 104) are not shown, but the right side portion of the functional element forming region 101 and the scribe region 102 on the right side thereof (scheduled removal) A wiring structure symmetrical with respect to the wiring structure of the region 104) is formed.

Although the embodiments of the present invention have been described above, the present invention can also be implemented in other embodiments. For example, in the above-described embodiment, the actuator substrate 2 is provided with two rows of piezoelectric element rows (pressure chamber rows), but is provided with only one row of piezoelectric element rows (pressure chamber rows). It may be provided for three or more rows.
Further, 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 be formed on the entire surface of the hydrogen barrier film 14.

Further, 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.
Further, in the above-described embodiment, PZT is exemplified as the material of the piezoelectric film, but in addition, lead titanate (PbPO ₃ ), potassium niobate (KNbO ₃ ), lithium niobate (LiNbO3), lithium tantalate are used. A piezoelectric material made of a metal oxide represented by (LiTaO ₃ ) or the like may be applied.

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

1 Inject printhead 2 Actuator board 2a Front side 2b Back side 3 Nozzle board 4 Protective board 5 Ink flow path 6 Ink inflow part 7 Pressure chamber 8 Metal barrier film 9 Piezoelectric element 10 Movable film forming layer 10A Movable film 11 Lower electrode 11A Main electrode Part 11B Extension 12 Piezoelectric film 13 Upper electrode 13-1 Upper extension wiring 13-2 Common wiring 13-3 Second upper wiring 14 Hydrogen barrier film 15 Insulation film 16 Lower wiring 17 Upper wiring 17-1 Upper extension wiring 17 -2 Common wiring 18 Piezoelectric processing lower wiring 19 Piezoelectric processing upper wiring 20 Nozzle hole 20a Recess 20b Ink ejection passage 20c Discharge port 21 Passion film 22 Ink supply through hole 23 Through hole (lower electrode)
26 Contact hole (lower wiring)
27 Contact hole (upper wiring)
28 Contact hole (lower wiring for piezoelectric processing)
30 Silicon substrate 31 Silicon oxide film 32 Water repellent film 36 Pad opening (lower wiring)
37 Pad opening (upper wiring)
38 Pad opening (lower wiring for piezoelectric processing)
39 Pad opening (upper wiring for piezoelectric processing)
40 openings (insulating film and passivation film)
41 Ink flow direction 46 Lower electrode pad 47 Upper electrode pad 48 Piezoelectric treatment lower electrode pad 49 Piezoelectric treatment upper electrode pad 50 Adhesive 51 Opposite surface 52 Storage recess 53 Ink supply path 54 Opening 71 Lower electrode Film 72 Piezoelectric material film 73 Upper electrode film 100 Actuator wafer 100a Front surface 100b Back surface 101 Functional element formation area 102 Scribing area 103 Scheduled cutting line 104 Scheduled removal area 110 Board assembly assembly 130 Protective substrate assembly 150 Nozzle substrate assembly 170 Inkjet Printhead Assembly 211 Dummy Lower Electrode 212 Dummy Piezoelectric Film 227 Contact Hole SA Substrate Assembly

Claims (4)

It ’s an inkjet print head.
An actuator board with multiple pressure chambers and
A movable film cambium that is arranged on the plurality of pressure chambers and includes a plurality of movable films that partition the top surface of the plurality of pressure chambers.
A plurality of piezoelectric elements formed on the plurality of movable films, including a lower electrode, a piezoelectric film formed on the lower electrode, and an upper electrode formed on the piezoelectric film.
Including a plurality of upper wirings connected to the upper electrodes of the plurality of piezoelectric elements.
The upper wiring includes a first upper wiring having one end connected to the upper electrode and a second upper wiring having one end connected to the other end of the first upper wiring.
The other end of the second upper wiring extends to the side surface of the inkjet printhead.
A hydrogen barrier film that covers at least the entire side surface of the upper electrode and the piezoelectric film, the upper surface of the lower electrode, and the upper surface of the second upper wiring.
Further including an insulating film formed on the hydrogen barrier film and arranged between the hydrogen barrier film and the first upper wiring.
The hydrogen barrier film and the insulating film are formed with a first contact hole for exposing a part of the upper electrode and a second contact hole for exposing a part of the second upper wiring. One end of the upper wiring of 1 is connected to the upper electrode via the first contact hole, and the other end of the first upper wiring is connected to the second contact hole through the second contact hole. Inkjet printhead connected to the top wiring . A protective substrate that is bonded to the actuator substrate by an adhesive so as to cover the piezoelectric element is further included.
The protective substrate is formed in a housing recess that opens toward the actuator board side and accommodates the piezoelectric element, and outside one end of the housing recess in a plan view, and is formed at one end of the ink flow path. The inkjet print head according to any one of claims 1 to 6, which has an ink supply path that communicates with the ink supply path. A nozzle substrate that is bonded to a surface of the actuator substrate on the side opposite to the surface on the movable membrane side by an adhesive, partitions the bottom surface of the pressure chamber, and further includes a nozzle substrate having a nozzle hole communicating with the pressure chamber. Item 2. The inkjet print head according to Item 1 or 2 . An actuator substrate having a plurality of pressure chambers, a plurality of movable membranes for partitioning the top surface portions of the plurality of pressure chambers, and a substrate assembly having a plurality of piezoelectric elements formed on the plurality of movable membranes are joined to the substrate assembly. A method for manufacturing an inkjet print head, which includes a nozzle substrate having a plurality of nozzle holes communicating with each of the plurality of pressure chambers.
A step of forming a substrate assembly assembly including a plurality of substrate assemblies by using a semiconductor wafer which is the original substrate of the actuator substrate and has a plurality of functional element forming regions surrounded by a scribe region.
A step of forming an inkjet printhead aggregate by joining a nozzle substrate aggregate containing a plurality of nozzle substrates to the substrate assembly aggregate.
It includes a step of manufacturing a plurality of inkjet printheads by dicing the group of inkjet printheads along the scribe region.
The step of forming the substrate assembly assembly is
A first step of forming a movable film forming layer including a plurality of movable film forming regions for each functional element forming region on the semiconductor wafer,
On each of the movable film forming regions of the movable film forming layer, a lower electrode, an upper electrode arranged on the side opposite to the movable film forming layer with respect to the lower electrode, and a piezoelectric film sandwiched between them. The second step of forming a plurality of piezoelectric elements including and
In each of the movable film forming regions, a third step of forming an upper wiring in which one end is connected to each upper electrode included in the region, and
The fourth step of forming one or more upper electrode pads for piezoelectric processing for each functional element forming region is included.
In the third step, all the plurality of upper wirings in the functional element forming region or the plurality of upper wirings in each set in which these are divided into a plurality of sets cross the functional element forming region and scribe around the plurality of upper wirings. It extends into the region and is formed so as to be commonly connected by common wiring in the scribe region, and one end of the common wiring is formed so as to extend across the scribe region and into the functional element forming region. ,
In the fourth step, a method for manufacturing an inkjet print head, in which the piezoelectric material processing upper electrode pad is formed so as to be connected to one end of the common wiring.

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