JP2017052111A - Electromechanical transduction member, droplet discharging member, image formation device, and manufacturing method of electromechanical transduction member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably suppress various kinds of problems which occur when an adhesive or underfill flows to a plurality of electromechanical transduction element sides.SOLUTION: An electromechanical transduction member includes a substrate equipped with a plurality of electromechanical transduction element 101 and a plurality of wirings 108 connected electrically to each of the plurality of electromechanical transduction elements, and a bonded member which is bonded, using an adhesive, to a bonding region present across the plurality of wirings. An inter-wiring structure 131 is provided between the wirings in the bonding region.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an electromechanical conversion member, a droplet discharge member, an image forming apparatus, and a method for manufacturing an electromechanical conversion member.

  As this type of electromechanical conversion member, for example, a member that pressurizes a pressurized liquid chamber of a droplet discharge member in order to discharge a droplet from a nozzle hole of a droplet discharge member of an image forming apparatus such as an ink jet recording apparatus. Are known.

  For example, Patent Document 1 discloses an electromechanical conversion member including a piezoelectric element substrate in which each of a plurality of piezoelectric elements (electromechanical conversion elements) is electrically connected to a drive IC (connection destination member) via a lead wiring. A droplet discharge head (droplet discharge member) is disclosed. On the piezoelectric element substrate, a holding substrate (a member to be bonded) having a recess in a portion facing the piezoelectric element is bonded with an adhesive.

  Conventionally, in an electromechanical conversion member having a substrate in which each of a plurality of electromechanical conversion elements is connected to an electronic component (connection destination member) such as a drive IC via wiring, liquid curable properties used when mounting the electronic component Resin (underfill) may flow into the electromechanical conversion element side. In this case, underfill adheres to the electromechanical conversion element or its surrounding members, causing various problems. For example, when an underfill adheres to the electromechanical conversion element, deformation of the electromechanical conversion element is hindered, and normal operation of the electromechanical conversion member becomes difficult. Moreover, when an underfill adheres to the contact terminal etc. which are arrange | positioned around an electromechanical conversion element, the electrical contact with respect to the contact terminal will be inhibited, and normal operation of the electromechanical conversion member will become difficult.

  The electromechanical conversion member described in Patent Document 1 includes an adhesive region on a piezoelectric element substrate in which a leg portion of a holding substrate having a recess is positioned between a piezoelectric element region where a plurality of piezoelectric elements are arranged and a driving IC. Are adhered to each other by an adhesive. Therefore, if the gap between the piezoelectric element region and the driving IC can be appropriately blocked by the legs of the holding substrate and the adhesive, the underfill of the driving IC can be stably suppressed from flowing into the piezoelectric element region.

  However, there are a plurality of lead-out wirings that electrically connect each piezoelectric element and the drive IC in the bonding region where the legs of the holding substrate are bonded. Depending on the thickness of the lead-out wiring (the height of the lead-out wiring from the surface of the piezoelectric element substrate), a space is formed between the adhesive surface of the holding substrate leg and the surface of the piezoelectric element substrate. In general, since the amount of adhesive attached is somewhat uneven, if there is a shortage of adhesive as a whole, the adhesive will not be filled into the space in areas where the amount of adhesive attached is relatively small. , A gap is generated in the separated space, and the inflow of underfill cannot be suppressed. On the other hand, if a large amount of adhesive is used so that the space is filled with the adhesive even in a portion where the adhesive amount is relatively small, the adhesive becomes excessive in the portion where the adhesive amount is relatively large. The excess adhesive flows into the piezoelectric element region and causes the same problem as the inflow of the underfill.

  In order to solve the above-described problem, the present invention provides a substrate including a plurality of electromechanical transducers and a plurality of wires electrically connected to each of the plurality of electromechanical transducers, and the plurality of wires. An electromechanical conversion member having a bonding target member bonded to an adhesive region existing over the adhesive region by using an adhesive includes an inter-wiring structure between the wirings in the adhesive region.

  According to the present invention, it is possible to stably suppress various problems that may occur when an adhesive, underfill, or the like flows into a plurality of electromechanical transducer elements (piezoelectric element regions). The

1 is a perspective view illustrating a configuration of an ink jet recording apparatus according to an embodiment. It is a side view of the mechanism part of the ink jet recording apparatus. It is a perspective view showing an example of a cartridge in which a droplet discharge head and an ink cartridge are integrated. FIG. 2 is a partially broken perspective view showing an internal configuration of a droplet discharge head in the ink jet recording apparatus. It is a top view of an actuator substrate constituting the droplet discharge head. FIG. 6 is a cross-sectional view of the droplet discharge head taken along A-A ′ in FIG. 5. FIG. 6 is a cross-sectional view of the droplet discharge head 50 taken along C-C ′ in FIG. 5. It is sectional drawing which shows the modification of the piezoelectric element which made the lower electrode the individual electrode layer 101-2, and made the upper electrode the common electrode layer 101-1. (A)-(d) is sectional drawing which shows the cross section orthogonal to the row direction of a nozzle hole, in order to demonstrate the front | former stage part of the manufacturing process of the droplet discharge head. (A)-(c) is sectional drawing which shows the cross section orthogonal to the arrangement direction of a nozzle hole, in order to demonstrate the middle step part of the manufacturing process of the droplet discharge head. (A)-(c) is sectional drawing which shows the cross section orthogonal to the arrangement direction of a nozzle hole, in order to demonstrate the back | latter stage part of the manufacturing process of the droplet discharge head. It is a top view of the holding substrate bonded to the actuator substrate. (A) is explanatory drawing which shows the adhesion part of the state which lacked the adhesive agent which adhere | attaches the holding substrate on the actuator substrate. (B) is explanatory drawing which shows the adhesion part of the state in which sufficient quantity of adhesives have adhered. It is explanatory drawing which shows the inflow path | route of the underfill to the piezoelectric element side. It is a top view which shows the state in which the actuator board | substrate was formed on siliconware. It is explanatory drawing for demonstrating the size of two piezoelectric elements adjacent to the row direction of a piezoelectric element row | line | column, and a structure between wiring. It is explanatory drawing for demonstrating the size of two piezoelectric elements adjacent in the row direction of a piezoelectric element row | line | column, its extraction wiring, and the structure between wiring. It is sectional drawing of an actuator board | substrate before a holding board | substrate is connected. 6 is a top view of an actuator substrate in Embodiment 2. FIG. FIG. 10 is an explanatory diagram for explaining the sizes of two piezoelectric elements adjacent to each other in the column direction of the piezoelectric element row, the lead-out wiring, and the interwiring structure on the actuator substrate in Example 2. It is a top view of an actuator substrate in a comparative example. FIG. 10 is an explanatory diagram for explaining the size of two piezoelectric elements adjacent to each other in the column direction of the piezoelectric element row on the actuator substrate in Example 2 and the size of the lead wiring. It is the graph which put together the result of the effect confirmation test.

Hereinafter, an embodiment in which a droplet discharge head as a liquid discharge member having an electromechanical conversion member according to the present invention is applied to an ink jet recording apparatus as an image forming apparatus will be described.
In this embodiment, ink is ejected. However, the liquid to be ejected is not limited to ink, and is not particularly limited as long as it becomes liquid when ejected. For example, Also included are DNA samples, resists, pattern materials, and the like.

FIG. 1 is a perspective view showing the configuration of the ink jet recording apparatus of this embodiment.
FIG. 2 is a side view of a mechanism portion of the ink jet recording apparatus according to the present embodiment.
The ink jet recording apparatus shown in FIGS. 1 and 2 includes a carriage 1 that can move in the main scanning direction inside the apparatus main body. The carriage 1 is equipped with a droplet discharge head 50 and an ink cartridge 2 that supplies ink to the droplet discharge head 50.

  As shown in FIG. 3, the droplet discharge head 50 and the ink cartridge 2 may have a configuration in which these are integrated. Thus, with the configuration in which the droplet discharge head 50 and the ink cartridge 2 are integrated, it becomes easy to increase the accuracy, density, and reliability of the actuator substrate of the droplet discharge head 50. Thus, yield and reliability can be improved, and cost can be reduced.

  A paper feed cassette (or a paper feed tray) 4 on which a large number of recording materials 30 can be stacked from the front side (left side in FIG. 2) is detachably attached to the lower part of the apparatus main body. Further, it also has a manual feed tray 5 that is opened to manually feed the recording material 30. The recording material 30 fed from the paper feed cassette 4 or the manual feed tray 5 records a required image by the printing mechanism unit 3 and then is discharged to a paper discharge tray 6 mounted on the rear side. The recording material 30 includes a medium made of a material such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics.

  The printing mechanism unit 3 holds the carriage 1 slidably in the main scanning direction by a main guide rod 7 and a sub guide rod 8 which are guide members horizontally mounted on left and right side plates (not shown). In the carriage 1, a plurality of ink discharge ports (nozzle holes) are arranged in a sub-scanning direction orthogonal to the main scanning direction, and yellow (Y), cyan (C), A droplet discharge head 50 for discharging ink droplets (droplets) of each color of magenta (M) and black (Bk) is mounted. In addition, each ink cartridge 2 for supplying ink of each color to the droplet discharge head 50 is mounted on the carriage 1 in a replaceable manner.

  The ink cartridge 2 is provided with an air opening communicating with the atmosphere above, and a supply opening supplying ink to the droplet discharge head 50 below. A porous body filled with ink is contained inside, and the ink supplied to the droplet discharge head 50 is maintained at a slight negative pressure by the capillary force of the porous body. Further, as the droplet discharge head 50, a different droplet discharge head is used for each color, but a single droplet discharge head having nozzles for discharging ink droplets of each color may be used.

  The carriage 1 is slidably fitted to the main guide rod 7 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the secondary guide rod 8 on the front side (upstream side in the paper conveyance direction). Yes. In order to move and scan the carriage 1 in the main scanning direction, a timing belt 12 is stretched between a driving pulley 10 and a driven pulley 11 that are rotationally driven by a main scanning motor 9a. The timing belt 12 is fixed to the carriage 1, and the carriage 1 is reciprocally scanned by forward and reverse rotation of the main scanning motor 9a.

  The ink jet recording apparatus also reverses the paper feed roller 13 and the friction pad 14 for separating and feeding the recording material 30 from the paper feed cassette 4, the guide member 15 for guiding the recording material 30, and the fed recording material 30. And a transporting roller 16 for transporting. Further, a conveyance roller 17 that is pressed against the peripheral surface of the conveyance roller 16 and a leading end roller 18 that defines the feeding angle of the recording material 30 from the conveyance roller 16 are also provided. The conveyance roller 16 is rotationally driven through a gear train by the sub-scanning motor 9b.

  Further, in order to guide the recording material 30 fed from the conveying roller 16 corresponding to the moving range of the carriage 1 in the main scanning direction on the lower side of the droplet discharge head 50, the printing receiving member 19 which is a paper guide member is also provided. Have. A conveyance roller 20 and a spur 21 which are rotationally driven to send the recording material 30 in the paper discharge direction are provided on the downstream side of the printing receiving member 19 in the paper conveyance direction, and the recording material 30 is further sent to the paper discharge tray 6. A paper discharge roller 23, a spur 24, and guide members 25 and 26 that form a paper discharge path are disposed.

  When an image is recorded by the ink jet recording apparatus, by moving the carriage 1 and driving the droplet discharge head 50 according to the image signal, the ink is discharged onto the recording material 30 that has stopped, and one line is left. After recording, the recording material 30 is conveyed by a predetermined amount, and then the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the recording material 30 reaches the recording area, the recording operation is terminated and the recording material 30 is discharged.

  Further, a recovery device 27 for recovering the ejection failure of the droplet ejection head 50 is disposed at a position outside the recording area on one end side in the moving direction of the carriage 1. The recovery device 27 has a cap unit, a suction unit, and a cleaning unit, which are not shown. The carriage 1 is moved to the recovery device 27 side during printing standby and capping the droplet discharge head 50 by the capping unit to keep the nozzle hole wet, thereby preventing discharge failure due to ink drying. Further, by ejecting ink not related to recording during recording or the like, the viscosity of ink in all nozzle holes is made constant, and stable ejection performance is maintained.

  Further, when a discharge failure occurs, the nozzle hole of the droplet discharge head 50 is sealed with a capping unit, and bubbles and the like are sucked out from the nozzle hole with the suction unit through the tube. As a result, ink or dust adhering to the nozzle surface is removed by the cleaning means, and the ejection failure is recovered. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.

Next, the configuration of the droplet discharge head 50 will be described.
FIG. 4 is a partially broken perspective view showing the internal configuration of the droplet discharge head 50 of the present embodiment.
FIG. 5 is a top view of the actuator substrate constituting the droplet discharge head 50.
6 is a cross-sectional view of the droplet discharge head 50 taken along line AA ′ in FIG.
FIG. 7 is a cross-sectional view of the droplet discharge head 50 taken along the line CC ′ in FIG.
In FIG. 5, for the sake of explanation, the holding substrate 200, which is a member to be bonded to the actuator substrate, is removed.

  The droplet discharge head 50 of this embodiment is mainly composed of an actuator substrate 100, a holding substrate 200, and a nozzle substrate 300. The actuator substrate 100 includes a piezoelectric element 101 as an electromechanical conversion element that generates liquid discharge energy on an element mounting surface (upper surface in the drawing) of a vibration plate 102 as a displacement plate. In the piezoelectric element 101 according to the present embodiment, as shown in FIG. 6, a piezoelectric layer 101-3 is sandwiched between a common electrode layer 101-1 that is a lower electrode and an individual electrode layer 101-2 that is an upper electrode. It becomes the composition. However, as shown in FIG. 8, a piezoelectric element in which the lower electrode is the individual electrode layer 101-2 and the upper electrode is the common electrode layer 101-1.

  In addition, the actuator substrate 100 includes a partition wall 103 on the surface (lower surface in the drawing) opposite to the element mounting surface of the diaphragm 102. A space surrounded by the diaphragm 102, the partition wall 103, and the nozzle substrate 300 is a pressurized liquid chamber 104. In addition, the fluid resistance portion 105 and the common liquid chamber 106 are also formed by the actuator substrate 100.

  The holding substrate 200 includes an ink supply port that supplies ink from the ink cartridge 2, and is bonded to the actuator substrate 100, whereby the common ink flow path 202 and the vibration plate 102 of the actuator substrate 100 are bent and displaced. And a recess 203 that forms a space that can be formed. The holding substrate 200 can be formed by silicon etching, plastic molding, or the like.

  In the nozzle substrate 300, nozzle holes 301 are formed at positions corresponding to the individual pressurized liquid chambers 104. As the nozzle substrate 300, for example, a plate formed of SUS by punching, etching, silicon etching, nickel electroforming, resin laser processing, or the like can be used.

  In the liquid droplet ejection head 50 of the present embodiment, each pressure liquid chamber 104 is filled with ink, and under the control of a control unit (not shown), a drive voltage signal is sent from the drive IC 120 to each individual electrode layer 101-. 2 is applied. As this drive voltage signal, a pulse voltage of 20 [V] generated by an oscillation circuit can be used. By applying such a voltage pulse, the piezoelectric layer 101-3 contracts in the direction parallel to the diaphragm 102 due to the piezoelectric effect. As a result, the vibration plate 102 is bent so as to protrude toward the pressurizing liquid chamber 104, and as a result, the pressure in the pressurizing liquid chamber 104 increases rapidly, and ink is ejected from the nozzle hole 301 communicating with the pressurizing liquid chamber 104. Is discharged.

  After the pulse voltage is applied, the contracted piezoelectric layer 101-3 returns to its original position, and the vibration plate 102 bent along with this returns to its original position. For this reason, the pressurized liquid chamber 104 has a negative pressure compared to the common liquid chamber 106, and the ink supplied from the ink cartridge 2 through the ink supply port is fluidized from the common ink flow path 202 and the common liquid chamber 106. It is supplied to the pressurized liquid chamber 104 through the resistance unit 105. By repeating this, ink droplets can be ejected continuously, and an image is formed on a recording material disposed facing the droplet ejection head 50.

Next, a method for manufacturing the droplet discharge head 50 in the present embodiment will be described.
9 to 11 are cross-sectional views showing a cross section orthogonal to the arrangement direction of the nozzle holes in order to explain the manufacturing process of the droplet discharge head 50 of the present embodiment.

As a base material of the actuator substrate 100, it is preferable to use a silicon single crystal substrate, and it is preferable to have a thickness of usually 100 to 600 μm. There are three types of plane orientations, (100), (110), and (111), but (100) and (111) are generally widely used in the semiconductor industry. A single crystal substrate having a plane orientation of 100) is used. Further, in the stage of producing the pressurized liquid chamber 104, the silicon single crystal substrate is processed using etching. In this case, anisotropic etching is generally used as an etching method. Anisotropic etching utilizes the property that the etching rate differs with respect to the plane orientation of the crystal structure. For example, in anisotropic etching immersed in an alkaline solution such as KOH, the (111) plane has an etching rate of about 1/400 compared to the (100) plane. Accordingly, a structure having an inclination of about 54 ° can be produced in the plane orientation (100), whereas a deep groove can be removed in the plane orientation (110), and the arrangement density is increased while maintaining rigidity. be able to. Therefore, it is also possible to use a single crystal substrate having a (110) plane orientation. However, in this case, SiO ₂ which is a mask material is also etched, so this point needs to be noted.

First, as shown in FIG. 9A, a film to be the vibration plate 102 is formed on the silicon single crystal substrate. Since the vibration plate 102 is repeatedly deformed by receiving the force generated by the piezoelectric element 101, it is preferable that the vibration plate 102 has sufficient strength to withstand this. Examples of the material include Si, SiO ₂ , and Si ₃ N ₄ produced by the CVD method. Moreover, it is preferable to select a material close to the linear expansion coefficient of the individual electrode layer 101-2 and the piezoelectric layer 101-3 to be bonded to the diaphragm 102. In particular, in the present embodiment, since PZT is used as the piezoelectric layer 101-3, the linear expansion coefficient close to 8 × 10 ⁻⁶ [1 / K], which is the linear expansion coefficient, is 5 × 10 ^−6. A material having a linear expansion coefficient of [1 / K] to 10 × 10 ⁻⁶ [1 / K] is preferable, and further 7 × 10 ⁻⁶ [1 / K] to 9 × 10 ⁻⁶ [1 / K]. A material having a linear expansion coefficient of is more preferable. Specific examples of the material include aluminum oxide, zirconium oxide, iridium oxide, ruthenium oxide, tantalum oxide, hafnium oxide, osmium oxide, rhenium oxide, rhodium oxide, palladium oxide, and compounds thereof. It can be produced by a spin coater using a Sol-gel method. As a film thickness, 0.1-10 micrometers is preferable and 0.5-3 micrometers is more preferable. If it is smaller than this range, the processing of the pressurized liquid chamber 104 becomes difficult, and if it is larger than this range, the vibration plate 102 is difficult to be deformed and displaced, and ink droplet ejection tends to become unstable.

  Next, the common electrode layer 101-1 is formed on the diaphragm 102 thus formed. The common electrode layer 101-1 is preferably a single metal film or a plurality of layers made of a metal film and an oxide film. In any case, an adhesive layer is inserted between the diaphragm 102 and the metal film. It is preferable to suppress peeling and the like.

As the adhesion layer, after Ti is sputtered, the titanium film is thermally oxidized in an O ₂ atmosphere at 650 to 800 ° C. for 1 to 30 minutes using an RTA (rapid thermal annealing) apparatus, and the titanium film is converted into a titanium oxide film. To. Reactive sputtering may be used to form the titanium oxide film, but thermal oxidation at a high temperature of the titanium film is desirable. The production by reactive sputtering requires a special sputtering chamber configuration because the silicon substrate needs to be heated at a high temperature. Furthermore, the crystallinity of the titanium oxide film is better in the oxidation by the RTA apparatus than in the oxidation by a general furnace. This is because, according to oxidation in a normal heating furnace, a titanium film that is easily oxidized forms several crystal structures at a low temperature, and thus it is necessary to break it once. Therefore, oxidation by RTA having a high temperature rising rate is advantageous in order to form better crystals. As materials other than Ti, materials such as Ta, Ir, and Ru are also preferable. The film thickness is preferably 10 nm to 50 nm, and more preferably 15 nm to 30 nm. If it is below this range, there is a concern about the adhesion, and if it exceeds this range, the crystal quality of the electrode film produced thereon will be affected.

In addition, as a metal film for forming the common electrode layer 101-1, platinum having high heat resistance and low reactivity has been used conventionally, but it has sufficient barrier properties against lead. In some cases, a platinum group element such as iridium or platinum-rhodium, or an alloy film thereof may be used. Also, when using platinum, is poor adhesion to the underlying (in particular SiO _2), it is preferable to laminate the adhesion layer described above previously. As a manufacturing method, vacuum film formation such as sputtering or vacuum deposition is generally used. The film thickness is preferably 80 to 200 nm, and more preferably 100 to 150 nm. If the thickness is smaller than this range, a sufficient current cannot be supplied as a common electrode, and a problem occurs when ink is ejected. If the thickness is larger than this range, the cost increases when using an expensive platinum group material, and the surface roughness increases when the film thickness is increased when platinum is used. However, a problem arises in that the oxide electrode film or PZT formed thereon has an influence on the surface roughness and crystal orientation, and sufficient displacement for ink ejection cannot be obtained.

As a metal oxide film for forming the common electrode layer 101-1, it is preferable to use SrRuO ₃ as a material. Other than this, materials such as those described by Sr _x A _(1-x) Ru _y B _(1-y) are also included (A = Ba, Ca, B = Co, Ni, x, y = 0 to 0). .5). A sputtering method can be adopted as the film forming method. The film quality of the SrRuO ₃ thin film varies depending on the sputtering conditions. In particular, the crystal orientation is emphasized, and the SrRuO ₃ film is also oriented at (111) following the Pt (111) used in the metal film. It is preferable to form a film by heating the substrate at 500 ° C. or higher. As for the film forming conditions, the film is formed at room temperature and then thermally oxidized at the crystallization temperature (650 ° C.) by RTA treatment. In this case, the SrRuO ₃ thin film is sufficiently crystallized, and a sufficient value can be obtained as a specific resistance as an electrode. However, (110) tends to be preferentially oriented as the crystal orientation of the film, and a film is formed thereon. The (110) orientation is also facilitated for PZT.

Regarding the crystallinity of the SrRuO ₃ thin film formed on Pt (111), the lattice constants of Pt and SrRuO ₃ are close to each other. Therefore, in the normal 2θ / θ measurement, the 2θ positions of SrRuO ₃ (111) and Pt (111). Are difficult to distinguish. With respect to Pt, due to the extinction rule, diffraction lines cancel each other at a position where 2θ inclined by 35 ° in the Psi direction is about 32 °, and no diffraction intensity is observed. Therefore, it is possible to confirm whether SrRuO ₃ is preferentially oriented to (111) by inclining the Psi direction by about 35 ° and judging from the peak intensity of 2θ around 32 °. When Psi is shaken with 2θ = 32 ° fixed, almost no diffraction intensity is observed with SrRuO ₃ (110) when Psi = 0 °, and diffraction intensity is observed near Psi = 35 °. It was confirmed that SrRuO ₃ was orientated by (111) for those fabricated under the film forming conditions of the embodiment. In addition, regarding the SrRuO ₃ film fabricated in this way, the diffraction intensity of SrRuO ₃ (110) is observed when Psi = 0 °.

When the piezoelectric element 101 was continuously displaced, the amount of displacement after a constant drive was estimated as much as compared with the initial displacement, and the orientation of the PZT had a great influence. (110) Insufficient displacement suppression is insufficient. Furthermore, when looking at the surface roughness of the SrRuO ₃ film, the film formation temperature has an effect, and the surface roughness is very small from room temperature to 300 ° C. and becomes 2 nm or less. In this case, the surface roughness of the SrRuO ₃ film is very flat, but the crystallinity is not sufficient, and the initial displacement amount of the piezoelectric element 101 formed thereafter and the deterioration of the displacement amount after continuous driving are as follows. Sufficient characteristics cannot be obtained. The surface roughness is preferably 4 nm to 15 nm, and more preferably 6 nm to 10 nm. If this range is exceeded, the dielectric breakdown voltage of the PZT deposited thereafter is very poor and leaks easily. Therefore, in order to obtain good crystallinity and surface roughness, the film formation temperature is 500 ° C. to 700 ° C., preferably 520 ° C. to 600 ° C. The surface roughness is an index of surface roughness (average roughness) measured by an atomic force microscope (AFM).

Regarding the composition ratio of Sr and Ru after the formation of the SrRuO ₃ film, Sr / Ru is preferably 0.82 or more and 1.22 or less. If it is out of this range, the specific resistance increases and sufficient conductivity as the common electrode layer 101-1 cannot be obtained. The film thickness of the SrRuO ₃ film is preferably 40 nm to 150 nm, and more preferably 50 nm to 80 nm. If the thickness is smaller than this range, sufficient characteristics cannot be obtained for initial displacement and displacement deterioration after continuous driving, and it is difficult to obtain a function as a stop etching layer for suppressing overetching of PZT. There is a problem at this point. On the other hand, if it is thicker than this film thickness range, the dielectric strength of PZT formed thereafter is very poor and leaks easily. The specific resistance of the SrRuO ₃ film is preferably 5 × 10 ⁻³ Ω · cm or less, more preferably 1 × 10 ⁻³ Ω · cm or less. If it is larger than this range, the contact resistance of the common electrode layer 101-1 with the electrode in contact with the common electrode layer 101-1 increases, and sufficient current cannot be supplied as the common electrode layer 101-1, so that the ink discharge Trouble occurs when doing.

Next, as shown in FIG. 9B, a piezoelectric layer 101-3 is formed on the common electrode layer 101-1. In this embodiment, PZT is used as the material for the piezoelectric layer 101-3. PZT is a solid solution of lead zirconate (PbZrO ₃ ) and titanic acid (PbTiO ₃ ), and the characteristics differ depending on the ratio. In general, the composition exhibiting excellent piezoelectric characteristics has a ratio of PbZrO ₃ and PbTiO ₃ of 53:47, and is expressed as Pb (Zr _0.53 , Ti _0.47 ) O ₃ in the chemical formula. Examples of composite oxides other than PZT include barium titanate. In this case, it is also possible to prepare a barium titanate precursor solution by dissolving barium alkoxide and a titanium alkoxide compound in a common solvent. It is. These materials are described by the general formula ABO ₃ and include composite oxides mainly composed of A = Pb, Ba, Sr, B = Ti, Zr, Sn, Ni, Zn, Mg, and Nb. Such descriptions are, for example, (Pb _1-x , Ba) (Zr, Ti) O ₃ , (Pb _1-x , Sr) (Zr, Ti) O ₃ . These mean the case where Pb of the A site is partially substituted with Ba or Sr. Such substitution is possible with a divalent element, and the effect thereof has an effect of reducing characteristic deterioration due to evaporation of lead during heat treatment.

  As a manufacturing method of the piezoelectric layer 101-3, it can be manufactured by a spin coater using a sputtering method or a Sol-gel method. In that case, since patterning is required, a desired pattern is obtained by photolithography etching or the like. When PZT is produced by the Sol-gel method, a PZT precursor solution can be produced by using lead acetate, zirconium alkoxide, and titanium alkoxide compound as starting materials and dissolving them in methoxyethanol as a common solvent to obtain a uniform solution. Since the metal alkoxide compound is easily hydrolyzed by moisture in the atmosphere, an appropriate amount of a stabilizer such as acetylacetone, acetic acid or diethanolamine may be added to the precursor solution as a stabilizer.

  When a PZT film is obtained on the entire surface of the base substrate, it is obtained by forming a coating film by a solution coating method such as spin coating and performing heat treatments such as solvent drying, thermal decomposition, and crystallization. Since the transformation from the coating film to the crystallized film involves volume shrinkage, it is necessary to adjust the precursor concentration so that a film thickness of 100 nm or less can be obtained in one step in order to obtain a crack-free film. The layer thickness of the piezoelectric layer 101-3 is preferably 0.5 to 5 μm, and more preferably 1 to 2 μm. If it is smaller than this range, it will not be possible to generate a sufficient displacement, and if it is larger than this range, many layers will be laminated, resulting in an increase in the number of steps and a longer process time.

  The relative dielectric constant of the piezoelectric layer 101-3 is preferably 600 or more and 2000 or less, and more preferably 1200 or more and 1600 or less. If it is smaller than this range, it is difficult to obtain sufficient displacement characteristics, and if it is larger than this range, the polarization treatment is not sufficiently performed, and it is difficult to obtain sufficient characteristics due to displacement deterioration after continuous driving.

After the piezoelectric layer 101-3 is formed, the individual electrode layer 101-2 is formed next. Similarly to the common electrode layer 101-1, the individual electrode layer 101-2 is preferably a single metal film layer or a plurality of layers composed of a metal film and an oxide film. As the oxide film, the oxide film described in the common electrode layer 101-1 can be used. At this time, the film thickness of the SrRuO ₃ film is preferably 20 nm to 80 nm, and more preferably 40 nm to 60 nm. As the metal film, the metal film described in the common electrode layer 101-1 can be used. At this time, the film thickness is preferably 30 to 200 nm, and more preferably 50 to 120 nm.

  Next, as shown in FIG. 9C, an interlayer insulating film 110 is formed to insulate the common electrode layer 101-1 and the piezoelectric element 101 from the lead wiring 108 to be formed later. In addition, the interlayer insulating film 110 needs to be a dense inorganic material because it is necessary to select a material that prevents moisture in the atmosphere from passing through while preventing damage to the piezoelectric element 101 due to film formation and etching processes. is there. Organic materials are not suitable because it is necessary to increase the film thickness in order to obtain sufficient protection performance. This is because if the interlayer insulating film 110 is a thick film, deformation of the diaphragm 102 is hindered, resulting in an inkjet head with low ejection performance.

In order to obtain high protection performance with a thin film for the interlayer insulating film 110, it is preferable to use oxides, nitrides, and carbides. It is necessary to select a material with high adhesion. Also, it is necessary to select a film forming method that does not damage the piezoelectric element 101. That is, a plasma CVD method in which a reactive gas is turned into plasma and deposited on a substrate, or a sputtering method in which a film is formed by causing plasma to collide with a target material and flying is not preferable. Examples of a preferable film forming method include a vapor deposition method and an ALD method, but an ALD method with a wide choice of usable materials is preferable. Preferable materials include oxide films used for ceramic materials such as Al ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ , Ta ₂ O ₃ , and TiO ₂ . In particular, by using the ALD method, a thin film having a very high film density can be produced and damage in the process can be suppressed.

  The film thickness of the interlayer insulating film 110 needs to be a thin film enough to ensure the protection performance of the piezoelectric element 101, and at the same time needs to be as thin as possible so as not to inhibit the deformation of the diaphragm 102. Therefore, a preferable range of the film thickness of the interlayer insulating film 110 is 20 nm to 100 nm. When the thickness is greater than 100 nm, the deformation amount of the diaphragm 102 is reduced, and the ink jet head has low ejection efficiency. On the other hand, when the thickness is smaller than 20 nm, the function of the piezoelectric element 101 as a protective layer is insufficient, and the performance of the piezoelectric element 101 is deteriorated.

The interlayer insulating film 110 may have a two-layer structure. In this case, as shown in FIG. 7, the second-layer insulating protective film 110b is thickened, and the second-layer insulating protective film is formed in the vicinity of the piezoelectric element 101 so as not to hinder the deformation of the diaphragm 102. A configuration may be adopted in which only the first insulating protective film 110a is removed. At this time, as the second insulating protective film 110b, any oxide, nitride, carbide, or a composite compound thereof can be used, but SiO ₂ generally used in semiconductor devices can be used. . Arbitrary methods can be used for the film formation, and a CVD method and a sputtering method can be exemplified, and considering the step coverage, it is preferable to use a CVD method capable of forming an isotropic film. The film thickness of the interlayer insulating film 110 needs to be a film thickness that does not cause dielectric breakdown by a voltage applied between the common electrode layer 101-1 and the individual electrode layer 101-2. That is, it is necessary to set the electric field strength applied to the insulating protective film within a range not causing dielectric breakdown. Furthermore, considering the surface properties of the base of the interlayer insulating film 110, pinholes, and the like, the thickness of the interlayer insulating film 110 is preferably 200 nm or more, and more preferably 500 nm or more.

  After the interlayer insulating film 110 is formed, a connection hole 111 for connecting the individual electrode layer 101-2 and the lead wiring 108 is formed by a lithoetch method. Further, when the common electrode layer 101-1 is connected to another lead wiring, a connection hole is similarly formed in the interlayer insulating film 110. Thereafter, as shown in FIG. 9D, the lead wiring 108 is formed.

  The material of the lead-out wiring 108 is preferably a metal electrode material made of any one of an Ag alloy, Cu, Al, Au, Pt, and Ir. As a manufacturing method, a sputtering method or a spin coating method is used, and then a desired pattern is obtained by photolithography etching or the like. The film thickness of the lead-out wiring 108 is preferably 0.1 to 20 μm, and more preferably 0.2 to 10 μm. If it is smaller than this range, the resistance will increase, and it will not be possible to pass a sufficient current through the individual electrode layer 101-2, resulting in unstable head ejection. If it is larger than this range, the process time becomes longer. Further, the contact resistance with the individual electrode layer 101-2 in the connection hole 111 is preferably 1Ω or less, and more preferably 0.5Ω or less. The contact resistance with the common electrode layer 101-1 in the connection hole is preferably 10Ω or less, more preferably 5Ω or less. If these ranges are exceeded, sufficient current cannot be supplied, and problems occur when ink is ejected.

  Further, as will be described later, the lead wiring 108 is also interposed in the adhesion region of the holding substrate 200. Therefore, in the present embodiment, in order to ensure the height uniformity in the adhesion region of the holding substrate 200, as shown in FIG. In the bonding region 109 to which the holding substrate 200 is bonded on the side), the same layer configuration as that of the bonding region on the lead wiring 108 side is left, and the reliability of bonding of the holding substrate 200 is enhanced.

Next, as shown in FIG. 10A, a passivation film 112 that functions as a protective layer for the lead-out wiring 108 is formed. By providing such a passivation film 112, inexpensive Al or an alloy material containing Al as a main component can be used as the material of the lead-out wiring 108. As a result, a low-cost and highly reliable ink jet head can be obtained. As a material of the passivation film 112, any inorganic material or organic material can be used, but it is necessary to use a material with low moisture permeability. Examples of the inorganic material include oxides, nitrides, and carbides, and examples of the organic material include polyimide, acrylic resin, and urethane resin. However, in the case of an organic material, it is necessary to form a thick film, which is not suitable for patterning described later. Therefore, it is preferable to use an inorganic material in that a thin film can exhibit a wiring protection function. In particular, the use of the Si ₃ N ₄ passivation film 112 for the Al lead-out wiring 108 is a technique that has been proven in semiconductor devices and is suitable. Further, the thickness of the passivation film 112 is preferably 200 nm or more, and more preferably 500 nm or more. When the film thickness is thin, a sufficient passivation function cannot be exhibited, so that disconnection due to corrosion of the lead-out wiring 108 occurs, thereby reducing the reliability of the ink jet.

  Further, it is preferable that the passivation film 112 removes the piezoelectric element 101 and a portion overlapping therewith so as not to hinder the deformation of the vibration plate 102. This makes it possible to obtain a highly efficient and highly reliable ink jet head. Specifically, as shown in FIG. 10B, the end portion of the lead-out wiring 108 serving as the individual electrode pad 107 connected to the driving IC 120 and the piezoelectric element 101 are formed by using a photolithography method or a dry etching method. The passivation film 112 and the interlayer insulating film 110 at a portion of the upper surface and the common ink flow path 202 are removed. Then, as shown in FIG. 10C, the vibration plate 102 at a place where the common ink flow path 202 and the common liquid chamber 106 communicate with each other is removed by a lithoetch method.

  An individual electrode pad 107 made of a bump electrode for connecting the driving IC 120 is formed at the end of the lead wiring 108. Examples of the method for forming the individual electrode pad 107 include an electrolytic plating method, an electroless plating method, and a stud bump method. Examples of the material of the individual electrode pad 107 include Au, Ag, Cu, Ni, and solder. As a method of connecting the driving IC 120 to the individual electrode pad 107, for example, an ACF (Anisotropic Conductive Film) bonding using FPC (Flexible Printed Circuits), solder bonding, wire bonding bonding, or a flip directly bonding to the output terminal of the driving IC 120 Chip bonding or the like can be selectively used. However, if FPC is used, FPC component costs are incurred, so wire bonding and flip chip bonding are more cost effective. In addition, wire bonding bonding has a slower tact than flip chip bonding, and thus has poor productivity and is disadvantageous for narrowing the pitch. Therefore, in this embodiment, the drive IC 120 is connected to the individual electrode pad 107 by flip-chip bonding, and the drive IC 120 is flip-chip mounted.

Next, as shown in FIG. 11A, the leg portion 200a of the holding substrate 200 in which the concave portion 203 is formed at a position corresponding to the diaphragm displacement region 113 and the adhesive region 109 on the actuator substrate 100 are bonded to the adhesive. Adhere at 114. If the actuator substrate 100 has a thickness of about 20 to 100 μm for forming the pressurized liquid chamber 104 and the like, sufficient rigidity cannot be ensured, so the holding substrate 200 is adhered to ensure rigidity. Therefore, the holding substrate 200 is preferably not a low-rigidity material such as resin but a high-rigidity material such as silicon. In order to prevent the actuator substrate 100 from warping, it is necessary to select a material having a thermal expansion coefficient close to that of the actuator substrate 100. Therefore, it is preferable to use ceramic materials such as glass, silicon, SiO ₂ , ZrO ₂ , and Al ₂ O ₃ .

  A recess 203 is formed at a position corresponding to the diaphragm displacement region 113 facing the piezoelectric element 101 of the holding substrate 200. The recess 203 secures a space for the piezoelectric element 101 to deform. Each recess 203 of the holding substrate 200 is partitioned for each piezoelectric element 101 as shown in FIG. Accordingly, sufficient rigidity can be ensured even with the actuator substrate 100 having a thin plate thickness, and mutual interference between the adjacent pressurized liquid chambers 104 can be reduced when each piezoelectric element 101 is driven. . Further, as shown in FIG. 12, since the concave portion 203 of the holding substrate 200 is partitioned for each piezoelectric element 101, a high processing accuracy is required to increase the density of the piezoelectric element 101, for example, 300 dpi. In the case of realizing a liquid droplet ejection head capable of image recording, the width of the partition wall defining the concave portion 203 of the holding substrate 200 is preferably 5 to 20 μm.

  Next, as shown in FIG. 11B, the partition wall portion 103 other than the pressurized liquid chamber 104, the common liquid chamber 106, and the fluid resistance portion 105 is coated with a resist by a litho method, and then an alkaline solution (KOH solution or An anisotropic wet etching is performed with a TMHA solution) to form a pressurized liquid chamber 104, a common liquid chamber 106, and a fluid resistance portion 105. In addition to anisotropic etching with an alkaline solution, the pressurized liquid chamber 104, the common liquid chamber 106, and the fluid resistance portion 105 may be formed by dry etching using, for example, an ICP etcher. After that, as shown in FIG. 11C, the nozzle substrate 300 having the nozzle holes 301 opened at positions corresponding to the pressurized liquid chambers 104 is bonded.

  The above description is an example of a method for manufacturing the droplet discharge head 50, and is not limited thereto.

Next, the configuration of the bonding region where the holding substrate 200 is bonded to the actuator substrate 100 will be described.
The connection between the driving IC 120 and the individual electrode pad 107 formed at the end of the lead-out wiring 108 is easily disconnected when an external force such as bending or impact is applied. Further, the connection between the driving IC 120 and the individual electrode pad 107 may be disconnected due to thermal stress. In addition, due to temperature and humidity changes, moisture may adhere to the connection portion between the drive IC 120 and the individual electrode pad 107 and the connection portion may be corroded. Therefore, the connection portion between the drive IC 120 and the individual electrode pad 107 needs to be sealed with a sealant such as a liquid curable resin (underfill).

  In the present embodiment, the holding substrate 200 is formed with an IC housing portion 201 for housing the drive IC 120 as shown in FIG. As shown in FIG. 7, the underfill 130 is placed in the IC accommodating portion 201 of the holding substrate 200, and the connection portion between the driving IC 120 and the individual electrode pad 107 is covered and sealed with the underfill 130.

  Since the underfill 130 is in a liquid state, the underfill 130 may flow out of the IC housing portion 201 if the lower portion of the IC housing portion 201 is not sealed. In the present embodiment, as shown in FIG. 7, an adhesive portion where the leg portion 200 a of the holding substrate 200 and the actuator substrate 100 are bonded with an adhesive 114 is present below the IC housing portion 201. For this reason, if the adhesive 114 is insufficient in the bonding portion, a gap is generated in the bonding portion, and the underfill 130 in the IC housing portion 201 may flow out from the gap. In this case, the overflowed underfill 130 may reach the piezoelectric element 101 and the surrounding diaphragm displacement region 113. The diaphragm displacement area 113 here is an area in which the diaphragm 102 bends (displaces) due to the expansion and contraction of the piezoelectric element 101. As shown in FIG. 11B or FIG. This corresponds to the portion of the diaphragm 102 constituting the wall surface 104. When the underfill 130 flows out to the diaphragm displacement region 113, the rigidity of the underfill 130 changes, and the amount of deflection (displacement) of the diaphragm 102 changes due to the expansion and contraction of the piezoelectric element 101. As a result, the diaphragm 102 cannot be flexed (displaced) as desired, and there is a risk of causing a discharge operation failure.

  In particular, as shown in FIGS. 13A and 13B, the bonding portion in the present embodiment is driven with each piezoelectric element 101 in the bonding region on the actuator substrate 100 to which the leg portion 200a of the holding substrate 200 is bonded. There are a plurality of lead wires 108 that connect the IC 120. For this reason, in the bonding portion, the thickness of the lead-out wiring 108 (the height of the lead-out wiring 108 from the substrate surface) is in a state where the adhesion surface and the substrate surface of the leg portion 200a of the holding substrate 200 are separated from each other. In general, some unevenness occurs in the adhesion amount of the adhesive 114. Therefore, when the adhesive 114 is insufficient as a whole, the adhesion amount of the adhesive 114 is relatively decreased as shown in FIG. With a small portion, the space between the bonding surface of the leg portion 200a and the substrate surface is not filled with the adhesive, and a gap through which the underfill can flow out from the IC housing portion 201 is formed. In this case, as indicated by the arrows in FIG. 14, the underfill flows into the diaphragm displacement region 113 in which the piezoelectric element 101 is disposed through the space between the lead wires 108.

  On the other hand, as shown in FIG. 13B, a large amount of adhesive 114 is filled in the space between the adhesion surface of the leg 200a and the substrate surface even in a portion where the adhesion amount of the adhesive 114 is relatively small. If the adhesive 114 is used, it is possible to prevent the underfill from flowing out from the IC housing portion 201. However, in this case, in a portion where the amount of adhesive 114 attached is relatively large, the amount of adhesive 114 becomes excessive, and instead of underfill 130, adhesive 114 flows into diaphragm displacement region 113 and is discharged. May cause defects.

  Therefore, in the present embodiment, as shown in FIG. 5, the inter-wiring structure 131 is provided between the lead-out wirings 108 in the adhesion region on the actuator substrate 100 to which the leg portion 200 a of the holding substrate 200 is adhered. When such an inter-wiring structure 131 exists between the lead-out wirings 108 in the adhesion region, the bonding surface of the leg portion 200a of the holding substrate 200 and the substrate surface are more than in the conventional configuration in which the inter-wiring structure 131 does not exist. Spacing space is reduced. As a result, even if a small amount of the adhesive 114 is used so that the adhesive 114 does not flow into the vibration plate displacement region 113 side even in a portion where the adhesive adhesion amount becomes relatively large due to uneven adhesion amount of the adhesive 114, It becomes possible to fill the space with a relatively small amount of agent adhesion with the adhesive 114. Therefore, inflow of both the adhesive 114 and the underfill 130 to the diaphragm displacement region 113 side can be stably suppressed, and can be caused by the adhesive 114 and the underfill 130 flowing into the diaphragm displacement region 113 side. Discharge operation failure can be stably suppressed.

  Note that as a method of reducing the space between the bonding surface of the leg portion 200a of the holding substrate 200 and the substrate surface, a method of shortening the distance between the lead-out wirings 108 is also conceivable. However, in this method, problems of electrical relationships (resistance component, capacitance component, inductive component, etc.) between the wirings such as current leakage between the lead-out wirings 108 are significant, and therefore there is a limit to shortening the distance between the wirings. Therefore, it is difficult to sufficiently reduce the space between the wirings without using the inter-wiring structure 131.

  In the present embodiment, if the distance between the inter-wiring structure 131 and the lead-out wiring 108 is too short, the electrical relationship between the two may be a problem. However, since the inter-wiring structure 131 only needs to have a function of reducing the space between the lead-out wirings 108, the electrical relationship between the inter-wiring structure 131 specialized for the function, that is, the lead-out wiring 108. Therefore, it is possible to use the inter-wiring structure 131 having a material and configuration that are less affected by the above. It is preferable that the inter-wiring structure 131 is substantially electrically independent from the wiring. For example, the inter-wiring structure 131 is preferably formed of an insulating material. There is no problem if there is little influence of the electrical relationship between them.

[Example 1]
Hereinafter, an example of the electromechanical conversion member including the actuator substrate 100 and the holding substrate 200 according to the above-described embodiment (hereinafter, this example is referred to as “Example 1”) will be described.
With respect to the actuator substrate 100, a thermal oxide film (film thickness: 1 μm) to be the vibration plate 102 is formed on a 6-inch silicon wafer, and then a common electrode layer 101-1 is formed (FIG. 9A). In the formation of the common electrode layer 101-1, first, a titanium film (thickness 30 nm) is formed as an adhesion layer by a sputtering apparatus, and then thermally oxidized at 750 ° C. using RTA, and subsequently platinum as a metal film. A SrRuO ₃ film (film thickness 60 nm) was formed by sputtering as a film (film thickness 100 nm) and an oxide film. The substrate heating temperature during sputtering film formation was 550 ° C.

  Next, as the piezoelectric layer 101-3, a solution (PZT precursor solution) adjusted to Pb: Zr: Ti = 114: 53: 47 is prepared, and a piezoelectric film is formed by spin coating. did. A specific PZT precursor solution used lead acetate trihydrate, isopropoxide titanium, and normal propoxide zirconium as starting materials. The crystal water of lead acetate was dehydrated after dissolving in methoxyethanol. The amount of lead is excessive with respect to the stoichiometric composition. This is to prevent crystallinity deterioration due to so-called lead loss during heat treatment. Isopropoxide titanium and normal oxide zirconium were dissolved in methoxyethanol, alcohol exchange reaction and esterification reaction proceeded, and mixed with the methoxyethanol solution in which the lead acetate was dissolved to synthesize a PZT precursor solution. The PZT concentration of this PZT precursor solution was 0.5 mol / L. Using this PZT precursor solution, a film was formed by spin coating. After film formation, the film was dried at 120 ° C. and then pyrolyzed at 500 ° C. After thermal decomposition treatment of the third layer, crystallization heat treatment (temperature 750 ° C.) was performed by RTA (rapid heat treatment). The film thickness at this time was 240 nm. This process was performed a total of 8 times (24 layers), and finally, a piezoelectric layer 101-3 having a thickness of about 2 μm was obtained.

Next, the individual electrode layer 101-2 is formed. In forming the individual electrode layer 101-2, first, an SrRuO ₃ film (film thickness of 40 nm) was formed as an oxide film, and a Pt film (film thickness of 125 nm) was formed as a metal film by sputtering. Thereafter, a photoresist made by Tokyo Ohka Co., Ltd. (TSMR8800) is formed by a spin coating method, a resist pattern is formed by a normal photolithography method, and then a Pt film and an oxide film are formed using an ICP etching apparatus (manufactured by Samco). After etching, the resist stripping apparatus manufactured by Semitool Co., Ltd. was subjected to a resist stripping process using an amine-based stripping solution for 30 minutes, and the ashing process manufactured by Canon Inc. for 3 minutes. Patterning 2 was performed (FIG. 9B).

  Similarly, after forming a resist pattern by a photolithography method, the piezoelectric layer 101-3 is etched, a resist peeling process and an ashing process are performed, and the piezoelectric layer 101-3 and the interwiring structure 131 are patterned ( FIG. 9B). That is, in Example 1, the interwiring structure 131 is formed of the same material as the piezoelectric layer 101-3.

In the first embodiment, a piezoelectric element array composed of 300 piezoelectric elements 101 is made into one chip in two sets, and as shown in FIG. 15, 64 chips are produced from one silicon wafer.
Also, as shown in FIG. 16, the arrangement pitch of the piezoelectric elements 101 (distance between the centers of the piezoelectric elements 101) is 85 μm, and the length of the piezoelectric elements 101 in the column direction of the piezoelectric element rows (the length in the short direction of the piezoelectric elements 101). ) Is 40 μm, and the inter-wiring structure 131 has a shape in which square corners of 70 μm × 70 μm are rounded.

Next, after the pattern of the common electrode layer 101-1 is formed by photolithography (FIG. 9B), resist stripping and ashing are performed, the common electrode layer 101-1 is patterned, and then two layers are formed. An interlayer insulating film 110 made of is formed (FIG. 9C). In the formation of the interlayer insulating film 110, first, an Al ₂ O ₃ film was formed at 50 nm using an ALD method, and then an SiO ₂ film was formed at 1 μm using a CVD method. The Al ₂ O ₃ film was formed by alternately stacking TMA (Sigma Aldrich), which is the raw material Al, and O ₃ generated by an ozone generator. After the formation of the interlayer insulating film 110, a connection hole 111 for connecting the individual electrode layer 101-2 and the lead wiring 108 was formed by etching (FIG. 9C).

  Next, Al was sputtered as the lead-out wiring 108 and the common electrode wiring, and was patterned by etching (FIG. 9D). In the first embodiment, as shown in FIG. 17, the lead-out wiring 108 for the individual electrode has an 8 μm wide wiring extending from a 75 μm square wiring portion located in the connection hole 111, and an individual electrode pad at the end thereof. A 20 μm square wiring portion 107 is formed. The distance between the inter-wiring structure 131 and the lead-out wiring 108 is 3.5 μm.

  In the first embodiment, as described above, the inter-wiring structure 131 is formed of the same material as the piezoelectric layer 101-3, and the inter-wiring structure 131 is also formed at the time of forming the piezoelectric layer 101-3. However, for example, the inter-wiring structure 131 may be formed of the same material as the lead-out wiring 108, and the inter-wiring structure 131 may be formed together when the lead-out wiring 108 is formed.

Next, a passivation film 112 is formed (FIG. 10A). In the formation of the passivation film 112, Si ₃ N ₄ was formed at a thickness of 500 nm by a plasma CVD method, and the portions where the individual electrode pads 107 were formed were etched (FIG. 10B). Next, the portion of the vibration plate 102 that becomes the common ink flow path 202 was removed by dry etching (FIG. 10C). After that, individual electrode pads 107 and the like for connection to the drive IC and the like are formed on the lead wiring 108 and the common electrode wiring with stud bumps 121 made of Au, and as shown in FIG. An actuator substrate 100 to be bonded was formed.

Next, creation of the holding substrate 200 will be described.
First, the wafer was polished to a thickness of 400 μm, and an oxide film was formed on the holding substrate 200 on the actuator substrate 100 side. Next, the recessed portions 203, the IC accommodating portions 201, and the oxide films at the portions that become the common ink flow paths 202 were removed by photolithography patterning. Thereafter, a resist was formed on the patterned oxide film, and the resist for forming a through-hole penetrating the holding substrate 200 such as the IC housing portion 201 and the common ink flow path 202 was subjected to photolithography patterning. Then, as shown in FIG. 12, through holes such as the IC accommodating portion 201 and the common ink flow path 202 were formed by ICP etching.

  Subsequently, only the resist on the actuator substrate 100 side of the holding substrate 200 was removed, and the recess 203 was formed by half-etching the actuator substrate 100 side by ICP etching using the first patterned oxide film pattern as a mask. Finally, by removing the oxide film, the holding substrate 200 in which the IC accommodating portion 201, the common ink flow path 202, and the recess 203 are formed is formed.

  After the epoxy adhesive 114 is applied to the adhesive surface (the surface of the leg portion 200a) of the holding substrate 200 formed in this way by a flexographic printing machine, the adhesive region on the actuator substrate 100 described above is applied, The holding substrate 200 was bonded to the actuator substrate 100 by curing the adhesive 114. Thereafter, the driving IC 120 was flip-chip mounted on the individual electrode pads 107 of the actuator substrate 100, and the underfill 130 was injected into the IC housing 201 from the gap between the IC housing 201 and the driving IC 120 and cured.

[Example 2]
Next, another example of the electromechanical conversion member including the actuator substrate 100 and the holding substrate 200 of the above-described embodiment (hereinafter, this example is referred to as “Example 2”) will be described.
In the second embodiment, as shown in FIGS. 19 and 20, the size of the inter-wiring structure 131 is a shape in which square corners of 65 μm × 65 μm are rounded, and the interval between the inter-wiring structure 131 and the lead-out wiring 108 is The same electromechanical conversion member as that of Example 1 was formed except that is 6.0 μm.

[Comparative Example]
Moreover, the electromechanical conversion member used as a comparative example was also formed for the effect confirmation test mentioned later.
In the comparative example, as shown in FIGS. 21 and 22, an electromechanical conversion member similar to that of Example 1 was formed except that the interwiring structure 131 was not provided.

[Effect confirmation test]
Using the electromechanical conversion member formed in Examples 1 and 2 and the comparative example and using an IR microscope, the inflow situation from the holding substrate 200 side to the piezoelectric element 101 side of the underfill 130, the holding substrate 200 and the actuator substrate 100 The inflow situation of the adhesive 114 to the piezoelectric element 101 side was inspected, and an effect confirmation test was performed in which the number of inflow locations was counted. In this effect confirmation test, with respect to the electromechanical conversion members formed in Examples 1 and 2 and the comparative example, the thickness when the adhesive 114 is applied to the adhesive surface of the holding substrate 200 by a flexographic printing machine is 1.0 μm, 1 Five sheets were formed on each of five levels of 0.5 μm, 2.0 μm, 2.5 μm, and 3.0 μm. As described above, since 64 chips are produced from one wafer, the number of electromechanical conversion members used in this effect confirmation test is 64 chips × 5 for each of Examples 1 and 2 and the comparative example. = 320. Then, the inflow state of the underfill 130 and the adhesive 114 to the piezoelectric element 101 side was calculated as the occurrence rate of the chips in which the inflow occurred (the number of inflow generated chips of the underfill or adhesive / 320).

FIG. 23 is a graph summarizing the results of this effect confirmation test.
First, regarding the inflow state of the underfill 130, a clear difference was confirmed between Examples 1 and 2 in which the interwiring structure 131 was provided and the comparative example in which the interwiring structure 131 was not provided. did it. It was also confirmed that the inflow state of the underfill 130 was improved as the size of the interwiring structure 131 was increased. This is because the space between the bonding surface of the holding substrate 200 and the substrate surface caused by the thickness of the lead-out wiring 108 decreases as the inter-wiring structure 131 increases, and the adhesive stabilizes in the space even if the adhesive 114 is small. This is because the inflow path of the underfill 130 is sealed.

  Further, regarding the inflow state of the adhesive 114, a large difference is confirmed between the first and second embodiments in which the inter-wiring structure 131 is provided and the comparative example in which the inter-wiring structure 131 is not provided. There wasn't. On the other hand, it was confirmed that the inflow situation of the adhesive 114 worsened as the thickness of the adhesive 114 increased. Thereby, it is considered that the thickness (amount) of the adhesive 114 is more dominant than the presence or absence of the inter-wiring structure 131 with respect to the inflow of the adhesive 114.

  As described above, by providing the inter-wiring structure 131 between the lead wires 108 in the adhesion region as in the first and second embodiments, both the adhesive 114 and the underfill 130 are directed to the diaphragm displacement region 113 side. Inflow can be stably suppressed, and the number of chips taken can be increased.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
A substrate such as an actuator substrate 100 including electromechanical conversion elements such as a plurality of piezoelectric elements 101 and wirings such as a plurality of wirings 108 electrically connected to each of the plurality of electromechanical conversion elements; In an electromechanical conversion member having a bonding target member such as the holding substrate 200 bonded to the bonding region existing over the wiring by the adhesive 114, an inter-wiring structure 131 is provided between the wirings in the bonding region. It is characterized by that.
According to this aspect, since the inter-wiring structure exists between the wirings in the bonding region, a part of the separation space that can be generated between the bonding target member and the substrate surface is filled with the inter-wiring structure due to the thickness of the wiring. In addition, the separation space is reduced as compared with the conventional configuration in which no interwiring structure exists. As a result, even if a small amount of adhesive is used so that the adhesive does not flow into multiple electromechanical transducers even in areas where the adhesive adhesion is relatively large due to uneven adhesive adhesion, It becomes possible to fill the space with a relatively small amount with the adhesive. Therefore, for both the adhesive and the underfill, the inflow to the plurality of electromechanical conversion elements can be stably suppressed, and various problems that can occur when the adhesive and the underfill flow into the plurality of electromechanical conversion elements. Can be stably suppressed.

(Aspect B)
In the aspect A, the member to be bonded includes a recess 203 in a portion facing the electromechanical conversion element, and a leg portion 200a forming a side wall of the recess is bonded to an adhesion region on the substrate. It is characterized by that.
According to this, in the bonding region of the bonding target member to be bonded to the substrate for the purpose of ensuring the strength of the substrate without hindering the deformation of the electromechanical conversion element, a plurality of electric materials for both the adhesive and the underfill are used. Inflow to the mechanical conversion element side can be stably suppressed.

(Aspect C)
In the aspect A or B, a gap between the wiring and the inter-wiring structure is 6.0 μm or less.
According to this, it can suppress stably flowing into the several electromechanical conversion element side about both an adhesive agent and an underfill from the effect confirmation test mentioned above.

(Aspect D)
In any one of the aspects A to C, the inter-wiring structure is formed of the same material as the electromechanical transducer.
According to this, in the process of forming the electromechanical conversion element on the substrate, the inter-wiring structure can be formed together, and an electromechanical conversion member that is easy to manufacture can be provided.

(Aspect E)
In any one of the aspects A to C, the inter-wiring structure is formed of the same material as the wiring.
According to this, the inter-wiring structure can be formed together in the step of forming the wiring on the substrate, and an electromechanical conversion member that is easy to manufacture can be provided.

(Aspect F)
In any one of the aspects A to E, the electronic component such as the drive IC 120 that is flip-chip mounted on the plurality of wirings on the opposite side of the plurality of electromechanical conversion elements with respect to the adhesion region is provided. And
According to this, it is possible to stably suppress various problems that may be caused by the underfill filled in the connection part between the flip-chip mounted electronic component and the substrate flowing into the plurality of electromechanical transducer elements. .

(Aspect G)
In any one of the aspects A to F, the wiring has a thickness of 4.0 μm or less.
According to this, it is possible to satisfactorily shield the inflow path of the underfill to the plurality of electromechanical transducer elements with a small amount of adhesive that can suppress the inflow of the adhesive to the plurality of electromechanical transducer elements.

(Aspect H)
Droplet ejection by a droplet ejection head 50 or the like, wherein a droplet such as an ink droplet is ejected by deforming the electromechanical conversion element of the electromechanical conversion member according to any one of the aspects A to G Element.
According to this, it is possible to realize a droplet discharge member in which defective discharge operations that can be caused by the inflow of adhesive or underfill to the plurality of electromechanical transducer elements are suppressed.

(Aspect I)
In an image forming apparatus such as an ink jet recording apparatus that forms an image by ejecting droplets from a droplet ejection member such as the droplet ejection head 50, the droplet ejection member according to the aspect H is used as the droplet ejection member. It is characterized by that.
According to this, it is possible to realize an image forming apparatus in which defective ejection operation that may occur due to the inflow of adhesive or underfill to the plurality of electromechanical conversion element sides is suppressed.

(Aspect J)
An electromechanical conversion member manufacturing method according to any one of the aspects A to G, wherein the adhesive is attached to the substrate or the adhesion target member in an adhesion step of adhering the substrate and the adhesion target member. The thickness is 1.5 μm or more and 2.5 μm or less.
According to this, it can suppress stably flowing into the several electromechanical conversion element side about both an adhesive agent and an underfill from the effect confirmation test mentioned above.

DESCRIPTION OF SYMBOLS 1 Carriage 2 Ink cartridge 3 Printing mechanism part 4 Paper feed cassette 50 Droplet discharge head 100 Actuator board 101 Piezoelectric element 101-1 Common electrode layer 101-2 Individual electrode layer 101-3 Piezoelectric layer 102 Vibration plate 104 Pressurizing liquid chamber 106 Common liquid chamber 107 Individual electrode pad 108 Lead wire 110 Interlayer insulating film 111 Connection hole 112 Passivation film 113 Diaphragm displacement region 114 Adhesive 121 Stud bump 130 Underfill 131 Inter-wiring structure 200 Holding substrate 200a Leg portion 201 IC housing portion 202 Common ink flow path 203 Recess 300 Nozzle substrate 301 Nozzle hole

JP 2014-172281 A

Claims (10)

A substrate comprising a plurality of electromechanical transducers and a plurality of wires electrically connected to each of the plurality of electromechanical transducers;
In an electromechanical conversion member having a bonding target member bonded by an adhesive to an adhesive region existing across the plurality of wirings,
An electromechanical conversion member comprising an interwiring structure between the wirings in the adhesion region. The electromechanical conversion member according to claim 1,
The electrical machine is characterized in that the adhesion target member includes a recess in a portion facing the electromechanical conversion element, and a leg portion forming a side wall of the recess is bonded to an adhesion region on the substrate. Conversion member. The electromechanical conversion member according to claim 1 or 2,
The electromechanical conversion member, wherein a gap between the wiring and the inter-wiring structure is 6.0 μm or less. The electromechanical conversion member according to any one of claims 1 to 3,
The inter-wiring structure is formed of the same material as that of the electromechanical conversion element. The electromechanical conversion member according to any one of claims 1 to 3,
The electromechanical conversion member, wherein the inter-wiring structure is formed of the same material as the wiring. The electromechanical conversion member according to any one of claims 1 to 5,
An electromechanical conversion member comprising an electronic component flip-chip mounted on the plurality of wirings on the opposite side of the plurality of electromechanical conversion elements with respect to the adhesion region. The electromechanical conversion member according to any one of claims 1 to 6,
The electromechanical conversion member, wherein the wiring has a thickness of 4.0 μm or less.   A liquid droplet ejection member, wherein a liquid droplet is ejected by deforming the electromechanical conversion element of the electromechanical conversion member according to any one of claims 1 to 7. In an image forming apparatus that forms an image by discharging droplets from a droplet discharge member,
An image forming apparatus using the droplet discharge member according to claim 8 as the droplet discharge member. It is a manufacturing method of the electromechanical conversion member according to any one of claims 1 to 7,
An electromechanical conversion member having a thickness of 1.5 μm or more and 2.5 μm or less in an adhesive that adheres to the substrate or the member to be bonded in the bonding step of bonding the substrate and the member to be bonded. Production method.