Substrate and liquid dispensing head for liquid dispensing head

Abstract

We provide electrically reliable liquid dispensing heads. [Solution] A substrate for a liquid dispensing head, comprising a dispensing element used for dispensing liquid, and an electrode pad electrically connected to the dispensing element via wiring and provided on the wiring, wherein at least a portion of the side surface of the electrode pad is covered with an inorganic film.

Description

Technical Field

[0006] ,

[0007] ,

[0001] The present invention relates to a substrate for a liquid ejection head and a liquid ejection head.

Background Art

[0002] In a liquid ejection head of a liquid ejection device, a liquid such as ink is vibrated using ejection energy generated by energizing an energy element, and the liquid is ejected from a discharge port using the pressure generated thereby to perform a recording operation or the like.

[0003] In a liquid ejection head, an electrical connection portion between a terminal on a liquid ejection substrate having a discharge port and a wiring portion of a wiring substrate is sealed with a sealing agent mainly composed of resin. However, if the sealing with the sealing agent is not sufficient, there is a risk that ink may penetrate into the electrical connection portion and the terminal portion may be corroded. For this reason, various countermeasures are taken in the liquid ejection head to prevent corrosion of the electrical connection portion.

[0004] For example, Patent Document 1 discloses a configuration in which the side surface of a terminal portion is coated with a resin material so that the side surface of the terminal is not corroded by ink. In Patent Document 1, by covering the side surface of the terminal with a resin member, it is made difficult for the terminal and the sealing agent to peel off.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0008] One embodiment of the present invention that solves the above problems is a substrate for a liquid dispensing head, having a dispensing element used for dispensing liquid and an electrode pad electrically connected to the dispensing element via wiring and provided on the wiring, wherein at least a portion of the side surface of the electrode pad is covered with an inorganic film. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an electrically reliable liquid dispensing head. [Brief explanation of the drawing]

[0010] [Figure 1] A perspective view showing an example of a liquid dispensing device. [Figure 2] A perspective view showing an example of a liquid dispensing head. [Figure 3] A perspective view showing an example of a liquid dispensing unit. [Figure 4] An exploded perspective view showing an example of a liquid dispensing unit. [Figure 5] A plan view of the discharge tip in the first embodiment. [Figure 6] An enlarged plan view of the discharge tip in the first embodiment. [Figure 7] A cross-sectional view of the discharge tip in the first embodiment. [Figure 8] A cross-sectional view of the electrode pad in the first embodiment. [Figure 9] A cross-sectional view of the discharge tip connected to the wiring in the first embodiment. [Figure 10] A cross-sectional view of the discharge tip connected to the wiring in the first embodiment. [Figure 11] A diagram showing part of the manufacturing process of the discharge tip in the first embodiment. [Figure 12]Cross-sectional view of the electrode pad in the second embodiment. [Figure 13] Diagram showing part of the manufacturing process of the ejection chip in the third embodiment. [Figure 14] Cross-sectional view of the electrode pad in Example 2.

Mode for Carrying Out the Invention

[0011] The mode for carrying out the present invention will be described with reference to the drawings. Configurations having the same function are given the same reference numerals, and repeated descriptions may be omitted. Hereinafter, an example in which the present invention is applied to a liquid ejection head provided in a liquid ejection device as an inkjet printer will be described. However, the present invention is not limited to the embodiments shown below, and can be changed within the scope that those skilled in the art can conceive, such as other embodiments, additions, modifications, deletions, etc. In any aspect, as long as the effects and functions of the present invention are exhibited, it is included in the scope of the present invention.

[0012] Note that the components described below are merely examples, and the scope of the present invention is not intended to be limited only to them. The present invention will be described with specific examples using a liquid ejection recording head, but it is not limited to these examples, and various modifications and changes are possible within the scope of the gist.

[0013] <First Embodiment> (Configuration of the Liquid Ejection Device) FIG. 1 is a schematic perspective view for explaining the schematic configuration of a liquid ejection device 1000 according to an embodiment of a liquid ejection device to which the present disclosure is applicable. The liquid ejection device 1000 of the present embodiment is a one-pass type that records an image on the recording medium 200 by moving the recording medium 200 once, and ejection ports for ejecting liquid are arranged so as to correspond to the entire width of the recording medium 200. The liquid ejection device 1000 is provided with the liquid ejection head 100 of the present invention, for example, detachably.

[0014] The recording medium 200 is conveyed in the direction of arrow A by the conveying unit 300, and recording is performed by the liquid ejection head 100. The liquid ejection head 100 is a liquid ejection head disposed on a support member and having a liquid ejection unit 21 having a discharge tip 20 capable of discharging liquid (described later). The liquid ejection head 100 is positioned within the liquid ejection device 1000 by a reference member. In FIG. 1, a liquid ejection device 1000 is shown which is equipped with a total of eight liquid ejection heads 100 (100Ka, 100Kb, 100Ya, 100Yb, 100Ma, 100Mb, 100Ca, 100Cb), with two liquid ejection heads 100 capable of ejecting each of the four colors of black, yellow, magenta, and cyan ink.

[0015] In this specification, the direction parallel and opposite to the conveyance direction A of the recording medium 200 is the Y direction, the direction from the liquid ejection head 100 toward the recording medium 200 is the Z direction, and the direction perpendicular to both the Y direction and the Z direction and perpendicular to the conveyance direction of the recording medium 200 is the X direction.

[0016] (Overall configuration of the liquid ejection head) FIG. 2 shows a perspective view of the liquid ejection head 100, and FIG. 3 shows a perspective view of the liquid ejection unit 21. In the liquid ejection head 100 according to the present embodiment, a plurality of liquid ejection units 21 each having a discharge tip 20 for discharging liquid are fixed on a support member 40. The liquid ejection unit 21 has a cover member 16 on the surface opposite to the support member 40 of the discharge tip 20 (see FIGS. 3 and 4). Further, the liquid ejection head 100 has a housing for accommodating an electric substrate or the like. Note that the liquid ejection head to which the present invention is applicable can be implemented in any form including the example of FIG. 2, and other forms are not limited either.

[0017] Figure 4 shows an exploded perspective view of the liquid discharge unit 21, viewed from the side opposite to the surface (front) of the discharge tip 20 where the discharge port 13 is located. The liquid discharge unit 21 comprises a discharge tip 20, an electrical wiring member (wiring board) 12, and a flow path member 23. The discharge tip 20 includes a discharge port 13 for discharging liquid, an actuator (see Figure 5) for discharging liquid from the discharge port 13, and a terminal 27 (see Figure 5) electrically connected to the actuator. The electrical wiring member 12 is connected to the terminal 27 and supplies power to drive the actuator from outside the discharge tip 20 to the pressure generating element of the actuator. The flow path member 23 has a flow path for supplying liquid to the discharge port 13 and is positioned adjacent to the discharge tip 20 on the back surface, which is the side opposite to the front surface of the discharge tip 20. The electrical wiring member 12 is connected to the terminal 27 of the discharge tip 20 on the back side of the discharge tip 20, forming an electrical connection. In this embodiment, the liquid discharge unit 21 further includes a cover member 16 for protecting the surface of the discharge tip 20. In this embodiment, as an example, alumina is used for the flow path member 23 and titanium is used for the cover member 16.

[0018] Figure 5 is a plan view of the discharge tip 20 (liquid discharge substrate) as seen from the side where the terminal portion is provided, and shows the state before it is electrically connected to the electrical wiring member 12. Figure 6 is an enlarged view of part A in Figure 5. Figure 7 is a cross-sectional view of VII-VII in Figure 6.

[0019] Figure 7 is a schematic cross-sectional view of a discharge tip 20, which is a substrate for a liquid discharge head according to an embodiment of the present invention. The discharge tip 20 includes a first substrate 101, a second substrate 102, and a third substrate 103.

[0020] The first substrate 101 is made of, for example, a silicon substrate and has a structure in which an ejection element 15 is formed on a diaphragm 14. The second substrate 102 has an opening formed to form a pressure chamber 11. The diaphragm 14 forms the top wall of the pressure chamber 11 and partitions multiple pressure chambers 11. Furthermore, the first substrate has a housing for the piezoelectric element which is the ejection element 15 and individual flow channels 10 for introducing liquid into the pressure chamber. In the configuration of this embodiment shown in Figure 7, two individual flow channels 10 are connected to one pressure chamber 11, and liquid such as ink can circulate inside and outside the pressure chamber 11.

[0021] In this embodiment, the upper part of the bonded substrate is formed by joining a first substrate 101 and a second substrate 102 via an adhesive 9. Here, a piezoelectric element housing and an ink channel are formed in the first substrate, and a pressure chamber is formed in the second substrate. Furthermore, multiple piezoelectric elements are housed within the piezoelectric element housing, each corresponding to one of the multiple pressure chambers.

[0022] The third substrate 103 is made of, for example, a silicon substrate and has a discharge port 13 for discharging liquid. The discharge port 13 penetrates the third substrate and is a discharge port substrate having the discharge port 13 on the opposite side from the pressure chamber 11. Therefore, when a volume change occurs in the pressure chamber 11, the liquid accumulated in the pressure chamber 11 is discharged from the discharge port 13.

[0023] (Electrode pad configuration) In this embodiment, the liquid dispensing substrate consists of a first substrate 101, a second substrate 102, and a third substrate 103, stacked in that order. The first to third substrates in this embodiment are all formed from silicon substrates. Each substrate is joined together via an adhesive 9.

[0024] The third substrate 103 is a discharge port substrate equipped with a discharge port 13. The second substrate 102 is an actuator substrate having a pressure chamber 11 communicating with the discharge port 13, a diaphragm 14, and a discharge element 15 provided on the side of the diaphragm 14 opposite to the pressure chamber 11. Note that the discharge element 15 in this embodiment shown in Figure 7 is a piezoelectric element. The second substrate 102 further has a wiring layer 5 that supplies drive signals and voltage to the discharge element 15. The wiring layer 5 is electrically connected to the discharge element 15 by wiring (not shown). The wiring layer 5 is covered with a wiring covering layer 6 made of an insulating material such as a silicon compound such as SiN. The first substrate 101 is equipped with individual flow paths 10 that supply liquid to each pressure chamber 11.

[0025] Figure 8 shows a cross-sectional view of section VIII-VIII in Figure 6, specifically an enlarged cross-sectional view of the area around the electrode pad 1 and the wiring layer 5. An opening is provided in the wiring covering layer 6 on the wiring layer 5, and the wiring layer 5 and the electrode pad 1, which is made of gold (Au), are electrically connected through this opening. The electrode pad 1 is provided on the wiring layer (on the wiring). Furthermore, to prevent the gold constituting the electrode pad 1 from diffusing into the wiring layer 5, which is made of aluminum or the like, the wiring layer 5 and the electrode pad 1 are electrically connected via a titanium tungsten (TiW) layer acting as a diffusion prevention layer 4. A layer with a composition other than TiW may be used for the diffusion prevention layer 4. As described above, the wiring layer 5, the diffusion prevention layer 4, and the electrode pad 1 are stacked on the substrate in this order, thereby forming a terminal portion through which the ejection chip 20 is electrically connected to the electrical wiring member 12.

[0026] As shown in Figure 9, the ejection tip 20 is electrically connected to the liquid ejection device by its terminal portion being connected to the wiring 7 of the electrical wiring member 12. Here, Figure 9 is a cross-sectional view showing the state in which the wiring 7 is electrically connected to the electrode pad 1, and shows the position corresponding to Figure 8. The connection between the terminal portion (electrode pad 1) and the wiring 7 can be made using any method, such as wire bonding or a type of electrode sealing method for flip-chip bonding such as NCP (Non Conductive Paste). An electrical signal (drive signal) that determines the timing for driving the ejection element 15 and a voltage for driving the ejection element 15 are supplied from the liquid ejection device via the terminal portion. The wiring 7 and the terminal portion including the electrode pad 1 are sealed with a sealant 8 such as epoxy resin to protect them from ink, moisture, etc.

[0027] As shown in Figure 8, when viewed from a direction perpendicular to the surface of the ejection tip 20, an adhesion layer 3 is provided near the electrode pad 1, around the side surface of the electrode pad 1 and the diffusion prevention layer 4. The adhesion layer 3 is a laminated film of an inorganic film containing a metal oxide or silicon, or both, and is provided so as to surround the side surface of the electrode pad 1. In this disclosure, "side surface of the electrode pad 1" refers to the surface extending in a direction intersecting the surface of the ejection tip. The adhesion layer 3 is not present at the connection portion between the electrode pad 1 and the wiring 7, but is provided on the side surface of the electrode pad 1, and plays the role of a layer that improves the adhesion between the resin layer, which is the sealant 8, and the electrode pad 1. For this reason, the adhesion layer 3 does not necessarily need to be formed over the entire surface of the side surface of the electrode pad 1; it may be interrupted in some places, and it is sufficient if it is formed in a part between the side surface of the electrode pad and the sealant. Even if the adhesion between the wiring coating layer 6 and the sealant 8 is poor and ink penetrates from their interface, the adhesion layer 3 ensures the adhesion between the sealant 8 and the electrode pad 1, so the sealant 8 will not peel off. Therefore, ink is prevented from penetrating into the wiring layer 5, which is the wiring layer.

[0028] Furthermore, regarding the adhesion between each component, it is desirable that the adhesion between the adhesive layer 3 and the sealant 8 be higher than the adhesion between the electrode pad 1 and the sealant 8. Moreover, it is desirable that the adhesion between the electrode pad 1 and the adhesive layer 3 be higher than the adhesion between the sealant 8 and the adhesive layer 3.

[0029] The adhesion layer 3 should preferably have an ink-resistant composition. Specifically, SiC, SiOC, SiCN, SiCN, TiO, TaO, HfO, ZrO, etc., can be suitably used. These materials improve adhesion to organic resin materials such as sealants 8 and adhesives 9, and can also serve as a protective film against ink. Among these, TaO is the most suitable to use as a protective film because it also has excellent adhesion to adhesives.

[0030] Figure 10 shows a configuration in which the electrode pad 1 and wiring 7 are connected by NCP bonding. The location in Figure 10 corresponds to the cross-section at XX in Figure 6. The procedure for electrical connection in this case will be explained. First, an organic material, NCP agent (non-conductive resin) 81, is applied to the area where the electrode pad 1 is formed. Then, after aligning the electrode pad 1 and wiring 7, a load is applied from above the wiring 7 using a bonding tool or the like to bring the electrode pad 1 and wiring 7 into contact. At this time, it is desirable that the NCP agent 81 is pushed out from the contact surface so that the electrode pad 1 and wiring 7 are in direct contact. Next, with the contact position fixed by applying a load, the NCP agent 81 is heated to cure. The curing shrinkage force of the NCP agent maintains the electrical connection between the electrode pad 1 and wiring 7.

[0031] In the case of NCP connection as described above, the adhesion between the electrode pad 1 and the organic material NCP agent 81 is important. The adhesion between the organic material NCP agent 81 and the metal electrode pad 1 is low, and if the NCP agent peels off from the electrode pad, it may cause a connection failure. Therefore, as in the configuration of the present invention, by forming an adhesion layer 3 on the side surface of the electrode pad 1, it is possible to maintain high adhesion between the NCP agent 81 and the electrode pad 1.

[0032] Furthermore, when electrode pads 1 are densely arranged on a liquid discharge substrate and the contact area between the electrode pads 1 and the sealant 8 or NCP agent 81 is small, the present invention can be suitably used to improve the adhesion between the electrode pads 1 and the sealant 8 or NCP agent 81.

[0033] (Method of manufacturing electrode pads) The manufacturing process of a liquid discharge substrate, including the step of forming an adhesion layer 3 on the side surface of the electrode pad 1, will be described sequentially using Figures 11(a) to 11(i).

[0034] First, a second substrate 102 is prepared in which the ejection element 15, wiring layer, and electrode pad 1 are formed on the surface layer 1021 on the side of the surface (first surface) 102a. If the first substrate is a silicon substrate, examples of the surface of the surface layer 1021 include Si-based materials such as Si, SiN, SiC, SiO, SiOC, SiON, SiCN, and SiCN, which are typically used in semiconductor devices and MEMS devices. Examples of materials for the electrode pad 1 include Al, Cu, Au, Ir, and Ta.

[0035] Subsequently, as shown in Figure 11(a), a sacrificial layer 2 is formed on the surface 102a of the second substrate 102. The sacrificial layer 2 is a layer that will be removed in a later process. It is difficult to perform a process that etches the ink-resistant film without damaging the substrate material or electrode material. Therefore, a sacrificial layer is needed that can selectively remove the ink-resistant film without damaging the substrate material or electrode material when etching it. With this in mind, TiW, W, Cr, etc. can be suitably used for the sacrificial layer 2. If there are no components containing Al or SiO on the first substrate, Al or SiO may be used as the sacrificial layer 2. It is particularly preferable when using TiO, TaO, HfO, ZrO, etc. as the material for the ink-resistant film.

[0036] Next, a resist material is applied to the surface 102a of the second substrate 102, and the resist 17 is patterned using photolithography as shown in Figure 11(b). This process covers the sacrificial layer 2 in the areas where the electrode pads 1 and ejection elements 15 are provided with the resist 17. Subsequently, the sacrificial layer 2 exposed from the resist 17 is removed using wet etching or the like, and then the resist 17 is removed by etching. This process leaves the sacrificial layer 2 on the sides of the electrode pads 1, the sides of the diffusion prevention layer 4, and the area of ​​the ejection elements 15 (see Figure 11(c)).

[0037] Next, as shown in Figure 11(c), an adhesion layer 3 is deposited on the entire surface 102a of the second substrate 102, including the sides of the electrode pad 1 and spacer 112. The adhesion layer 3, which also serves as an ink-resistant film, can be made from materials such as TiO, TaO, HfO, or ZrO. Methods for depositing the adhesion layer 3 include atomic layer deposition (ALD) and chemical vapor deposition (CVD). For example, ALD can be used when depositing TaO as the adhesion layer 3. ALD is the most suitable method for depositing the adhesion layer 3 because it deposits the film isotropically across the entire surface. CVD can also be used when depositing SiC as the adhesion layer 3.

[0038] Subsequently, a resist material is applied, and the resist 18 is patterned using photolithography as shown in Figure 11(d). This process ensures that the resist 18 is not formed in the areas of the electrode pad 1 and the ejection element 15.

[0039] Next, as shown in Figure 11(e), the adhesion layer 3 exposed from the resist 18 is etched, and then the resist 18 is removed. For etching the adhesion layer 3, anisotropic dry etching can be suitably used, for example. Etching the adhesion layer 3 leaves it behind the pattern of the resist 18. In the areas that were exposed from the resist 18, the adhesion layer on the upper surface of the electrode pad 1 and the ejection element 15 (the side opposite to the second substrate 102) is removed. On the other hand, the adhesion layer 3 remains on the side surface of the electrode pad 1, the side surface of the diffusion prevention layer 4, and in areas that are not affected by dry etching due to the presence of the electrode pad 1.

[0040] To function as an adhesion layer, the thickness of the adhesion layer 3 remaining on the side surface of the electrode pad 1 is preferably 2 nm or more. Furthermore, the side surface of the electrode pad 1 does not need to be completely covered with the adhesion layer 3, as long as the adhesion layer 3 works to improve the adhesion between the electrode pad 1 and the sealant 8. The thickness of the adhesion layer 3 may not be uniform, and there may be a mixture of thin and thick areas.

[0041] To explain the state of the side surface of electrode pad 1 in the pad row direction, Figure 11 shows a cross-sectional view of XI-XI in Figure 6. Between adjacent electrode pads 1, as shown in Figure 11, the adhesion layer 3 is separated, and the side surface of each electrode pad 1 is covered with the adhesion layer 3. If isotropic etching is used to etch the adhesion layer 3, the adhesion layer 3 deposited on the side surface of electrode pad 1 will also be removed, so as mentioned above, it is desirable to use anisotropic dry etching or the like. As a result of this process, in pad row 111, the adhesion layer 3 is not connected between adjacent electrode pads (see Figure 10).

[0042] Next, as shown in Figure 11(f), the sacrificial layer 2 is removed. When removing the sacrificial layer 2, it is desirable to appropriately select a combination of materials and a removal method so that only the sacrificial layer 2 can be selectively removed without damaging the wiring layer 5, ejection element 15, and adhesion layer 3 formed on the substrate. Examples of methods for removing the sacrificial layer 2 include wet etching and isotropic dry etching. Through the above series of steps, an electrode pad 1 with its sides covered by the adhesion layer 3 can be formed.

[0043] Furthermore, the ratio of the thickness of the adhesion layer 3 to the thickness of the sacrificial layer 2 before etching the adhesion layer 3 should be set in the range of approximately 0.2 to 5. Regarding this ratio of the thickness of the adhesion layer 3 to the sacrificial layer 2, if the performance of the sacrificial layer 2 as a stopper during etching of the adhesion layer 3 is high, the ratio of the thickness of the adhesion layer 3 to the thickness of the sacrificial layer 2 may be increased.

[0044] Subsequently, as shown in Figure 11(g), a recess that will become a pressure chamber 11 and through holes that will become individual flow channels 10 are formed in the second substrate 102.

[0045] Next, as shown in Figure 11(h), a layer of organic resin material was formed on the substrate created by processing the silicon substrate. Then, the first substrate 101 and the second substrate 102 were joined together via adhesive 9. As the adhesive 9, for example, one mainly composed of benzocyclobutene resin can be used.

[0046] Subsequently, as shown in Figure 11(i), a third substrate 103, which has an ejection port 13 processed on a silicon substrate, is bonded to the second substrate 102 via an adhesive. Through the above series of steps, a liquid ejection substrate can be formed.

[0047] <Second Embodiment> This explanation will focus on the differences from the first embodiment described above, and will omit explanations of parts that are the same as those described above. Figure 12 is a cross-sectional view of the electrode pad 1 in the second embodiment, and corresponds to Figure 8 of the first embodiment.

[0048] In this embodiment, as shown in Figure 12, the side surface of the electrode pad 1 is covered with an adhesion layer 31, and the adhesion layer (first layer) 31 is further covered with an adhesion layer (second layer) 32. That is, the adhesion layer 3 in the first embodiment has a multilayer structure. The materials for the adhesion layer 31 and adhesion layer 32 can be the same as those used for the adhesion layer 31 described in the first embodiment, and it is sufficient that the adhesion to the sealant 8 is higher than the adhesion between the electrode pad 1 and the sealant 8.

[0049] Regarding the combination of materials for the adhesion layer 31 and the adhesion layer 32, it is preferable that the adhesion layer 32 has higher adhesion to the sealant 8 covering the electrode pad 1 than the adhesion layer 31. Also, it is preferable that the adhesion layer 31 has higher adhesion to the electrode pad 1 than the adhesion layer 32.

[0050] The preferred relationship of adhesion strength between the electrode pad 1, the sealant 8, the adhesion layer 31, and the adhesion layer 32 is summarized below. The order of adhesion strength with the electrode pad 1 is adhesion layer 31 > adhesion layer 32 > sealant 8, and the order of adhesion strength with the sealant 8 is most desirable as follows: adhesion layer 32 > adhesion layer 31 > sealant 8. In other words, in the laminated configuration of the adhesion layer 3, it is most desirable to place the layer with higher adhesion to the electrode pad 1 on the electrode pad 1 side and the layer with higher adhesion to the sealant 8 on the sealant 8 side.

[0051] By using such a combination of adhesion layers 31 and 32, the adhesion between the electrode pad 1 and the sealant 8 can be further improved. This prevents ink from entering the electrode pad 1 and improves the electrical reliability of the liquid ejection head. As for specific material combinations for adhesion layers 31 and 32, for example, a combination using TaO for adhesion layer 31 and SiC, which has higher adhesion to resin than TaO, for adhesion layer 32 can be suitably adopted. Here, as mentioned above, TaO as adhesion layer 31 can be fabricated using ALD, and SiC as adhesion layer 32 can be fabricated using CVD.

[0052] Furthermore, in order to function as an adhesion layer, it is preferable that the total thickness of the adhesion layers 31 and 32 remaining on the side surface of the electrode pad 1 be 2 nm or more.

[0053] In the manufacturing process shown in Figure 11(c), the adhesion layer 31 is first formed, followed by the formation of the adhesion layer 32.

[0054] Although Figure 12 and the above description show an example configuration in which two adhesion layers, adhesion layers 31 and 32, are formed on the side surface of electrode pad 1, the effects of the present invention can also be suitably obtained in a configuration in which three or more laminated adhesion layers are formed on the side surface of electrode pad 1.

[0055] <Third Embodiment> This explanation will focus on the differences from the embodiments described above, and will omit explanations of parts that are similar to the configuration described above.

[0056] (Spacer part) As shown in Figure 7, the surface of the second substrate 102 facing the first substrate 101 has wiring for electrically connecting the ejection element 15 and the electrode pad 1, a wiring covering layer 6 covering the wiring, and a spacer 112. When joining the first substrate 101 and the second substrate 102, by providing a spacer 112 that is higher than the wiring at a different location from the wiring layer, the first substrate 101 and the spacer 112 come into contact, and the thickness of the adhesive 9 on the wiring covering layer 6 can be ensured.

[0057] The spacer 112 has the same configuration as the electrode pad 1, with the spacer 112 as a gold structure formed on the diffusion prevention layer 4. The sides of the spacer 112 and the sides of the diffusion prevention layer 4 are surrounded by an adhesion layer 3 containing an inorganic film containing metal oxide or silicon, or both, in a laminated state. Since the adhesion between the spacer 112 and the adhesive 9 is related to the adhesive strength of the substrate bonding surface, the presence of the adhesion layer 3 further ensures the adhesion of the spacer sides that come into contact with the adhesive 9.

[0058] Figure 7 shows an example in which a spacer 112 is placed on the bonding surface between the first substrate 101 and the second substrate 102, but this embodiment is not limited to this. For example, in a configuration in which a spacer 112 is placed on the bonding surface between the second substrate 102 and the third substrate 103, an adhesion layer 3 may be provided on the side surface of the spacer 112.

[0059] The manufacturing process of the liquid discharge substrate, including the step of forming an adhesion layer 3 on the side surface of the spacer 112, will be explained sequentially using Figures 13(a) to 13(i). In the following explanation, an adhesion layer 3 will also be formed on the side surface of the electrode pad 1.

[0060] First, a second substrate 102 is prepared in which the ejection element 15, wiring layer, electrode pad 1, and spacer 112 are formed on the surface layer 1021 on the side of surface 102a. The spacer 112 can be formed simultaneously in the same process as the electrode pad 1, and both are formed on the diffusion prevention layer 4. As an example, TiW is selected as the diffusion prevention layer 4. The height of the spacer 112 (the size in the direction perpendicular to the surface 102a of the second substrate 102) is greater than the sum of the thickness of the wiring layer and its covering portion.

[0061] Subsequently, as shown in Figure 13(a), a sacrificial layer 2 is deposited on the surface 102a side of the second substrate 102. In this embodiment, as an example, a TiW with a thickness of 50 nm is deposited as the sacrificial layer 2.

[0062] Next, a resist material is applied to the surface 102a of the second substrate 102, and the resist 17 is patterned using photolithography as shown in Figure 13(b). This process covers the sacrificial layer 2 in the area where the electrode pads 1, spacers 112, and ejection elements 15 are provided with the resist 17. Subsequently, the sacrificial layer 2 exposed from the resist 17 is removed using wet etching or the like, and then the resist 17 is removed by etching. Etching of the TiW as the sacrificial layer 2 is performed using hydrogen peroxide, which allows for selective etching of only the TiW without etching the SiN on the outermost surface of the Al of the wiring. Furthermore, even if the ejection element 15 is a heat-generating resistor element using Ta, only the TiW can be selectively etched without etching the Ta. This process leaves the sacrificial layer 2 on the side of the electrode pads 1, the side of the diffusion prevention layer 4, and the area of ​​the ejection element 15 (see Figure 13(c)).

[0063] Next, as shown in Figure 13(c), an adhesion layer 3 is formed on the entire surface 102a of the second substrate 102, including the sides of the electrode pad 1 and spacer 112. In Figure 13(c), the adhesion layer 3 is constructed as a two-layer laminate, with adhesion layer 31 being 20 nm thick TaO and adhesion layer 32 being 25 nm thick SiC.

[0064] Subsequently, a resist material is applied, and the resist 18 is patterned using photolithography as shown in Figure 13(d). This process ensures that the resist 18 is not formed in the areas of the electrode pad 1, spacer 112, and ejection element 15.

[0065] Next, as shown in Figure 13(e), the adhesion layer 3 exposed from the resist 18 is etched, and then the resist 18 is removed. For etching the adhesion layer 3, for example, anisotropic dry etching using a fluorocarbon-based gas can be suitably used, and the adhesion layer 31 and adhesion layer 32 can be etched simultaneously. By using the TiW, which is the diffusion prevention layer 4, as a stopper, the adhesion layer 3 can be processed without damaging the SiN on the outermost surface of the Al of the wiring or the ejection element 15.

[0066] Etching of the adhesion layer 3 leaves it behind the pattern of the resist 18. In the areas exposed from the resist 18, the adhesion layer on the electrode pad 1, spacer 112, and the upper surface of the ejection element 15 (the side opposite to the second substrate 102) is removed. On the other hand, the adhesion layer 3 remains on the sides of the electrode pad 1, the sides of the spacer 112, and the sides of the diffusion prevention layer 4 beneath the electrode pad 1 and spacer 112. As a result, a layer with high adhesion to the organic resin film containing the encapsulant 8 and adhesive 9 can be formed on the sides of the electrode pad 1 and spacer 112.

[0067] Next, as shown in Figure 13(f), the sacrificial layer 2 is removed. The TiW acting as the sacrificial layer 2 can be dissolved and removed with hydrogen peroxide. As mentioned above, the treatment with hydrogen peroxide does not damage the SiN on the outermost surface of the Al of the wiring or the outermost surface of the ejection element 15, and similarly, the treatment with hydrogen peroxide does not damage the adhesion layer 3.

[0068] However, when TiW is used for both the diffusion prevention layer 4 and the sacrificial layer 2, the diffusion prevention layer 4 directly beneath the electrode pad 1 and spacer 112 may be etched during the TiW etching process shown in Figures 13(b) and 13(e). In this case, the electrode pad 1 and spacer 112 may peel off. Therefore, it is desirable to adjust the processing time of the TiW so that the diffusion prevention layer 4 is not etched too much. For example, in a configuration like that of this embodiment, the horizontal dimension of the electrode pad 1 (in the direction horizontal to surface 102a) is expected to be several tens of micrometers to several hundreds of micrometers. In this case, the amount of etching of the diffusion prevention layer 4 is relatively small compared to its dimensions, so it will not have a significant impact on the electrode pad 1.

[0069] Subsequently, as shown in Figure 13(g), a recess that will become a pressure chamber 11 and through holes that will become individual flow channels 10 are formed in the second substrate 102.

[0070] Next, as shown in Figure 13(h), the first substrate 101 and the second substrate 102 are joined together via adhesive 9. As the adhesive 9, for example, one mainly composed of benzocyclobutene resin can be used.

[0071] Subsequently, as shown in Figure 13(i), a third substrate 103, which has been processed with an extrusion port 13 on a silicon substrate, is joined to the second substrate 102 via a layer of adhesive 9. Through the above series of steps, a liquid discharge substrate can be formed in which an adhesion layer is formed on the side surface of the electrode pad, with higher adhesion to the resin than to the electrode pad and higher adhesion to the electrode pad than to the adhesion layer between the resin and the adhesion layer.

[0072] <Other Embodiments> The present invention is not limited to the embodiments described above or the examples described later, and many modifications are possible within the technical concept of the present invention. For example, different embodiments or examples may be combined or implemented in combination.

[0073] This disclosure includes the following components:

[0074] (Composition 1) Discharge element used for dispensing liquid, The discharge element is electrically connected via wiring, and an electrode pad is provided on the wiring, A substrate for a liquid dispensing head having, A substrate for a liquid dispensing head, wherein at least a portion of the side surface of the electrode pad is covered with an inorganic film.

[0075] (Configuration 2) The electrode pad is a substrate for a liquid discharge head according to configuration 1, comprising Au.

[0076] (Composition 3) The inorganic film comprises a metal oxide, and is a substrate for a liquid dispensing head according to configuration 1 or 2.

[0077] (Composition 4) The inorganic film comprises at least one compound selected from the group consisting of TaO, TiO, SiOC, HfO, and ZrO, as described in configuration 3, for a liquid dispensing head substrate.

[0078] (Composition 5) The substrate for a liquid discharge head according to configuration 1 or 2, wherein the composition of the inorganic film is a silicon-containing compound.

[0079] (Composition 6) The inorganic film comprises at least one compound selected from the group consisting of SiOC, SiC, and SiCN, as described in configuration 5, for a liquid discharge head substrate.

[0080] (Composition 7) The substrate for a liquid discharge head according to any one of configurations 1 to 6, wherein the inorganic film has a multilayer structure including a first layer in contact with the side surface of the electrode pad and a second layer exposed on the opposite side of the first layer.

[0081] (Composition 8) A substrate for a liquid discharge head according to configuration 7, wherein the first layer is TaO and the second layer is SiC.

[0082] (Composition 9) The substrate for the liquid discharge head has wiring that electrically connects the discharge element and the electrode pad, The electrode pad is electrically connected to the wiring via a diffusion prevention layer. The inorganic film covers at least a portion of the side surface of the diffusion prevention layer, as described in any one of configurations 1 to 8, for a substrate for a liquid discharge head.

[0083] (Composition 10) The substrate for a liquid discharge head according to any one of configurations 1 to 9, wherein the discharge element is a piezoelectric element.

[0084] (Composition 11) Having a pad row in which multiple electrode pads are arranged, A substrate for a liquid discharge head according to any one of configurations 1 to 10, wherein in the pad row, the inorganic film is not connected between adjacent electrode pads.

[0085] (Composition 12) The aforementioned substrate for the liquid dispensing head is A second substrate having the electrode pads on the first surface, A wiring is provided on the first surface for electrically connecting the discharge element and the electrode pad, A first substrate bonded to the first surface via an adhesive, It has, and further, A substrate for a liquid discharge head according to any one of configurations 1 to 11, wherein a spacer is provided between the first substrate and the second substrate at a position that does not overlap with the wiring when viewed from a direction perpendicular to the first surface.

[0086] (Composition 13) Discharge element used for dispensing liquid, An electrode pad electrically connected to the discharge element, A substrate for a liquid dispensing head having, A second substrate having the electrode pads on the first surface, A wiring is provided on the first surface for electrically connecting the discharge element and the electrode pad, A first substrate bonded to the first surface via an adhesive, It has, and further, A spacer is provided between the first substrate and the second substrate, in a position that does not overlap with the wiring when viewed from a direction perpendicular to the first surface. The substrate for a liquid discharge head according to configuration 1, wherein at least a portion of the side surface of the spacer is covered with an inorganic film.

[0087] (Composition 14) The spacer is a substrate for a liquid discharge head according to configuration 13, which includes Au.

[0088] (Composition 15) A substrate for a liquid discharge head as described in any one of configurations 1 to 14, A wiring board having wiring that is electrically connected to the electrode pads, A sealant covering the connection between the electrode pad and the wiring, A liquid dispensing head having a liquid dispensing head.

[0089] (Composition 16) The liquid dispensing head according to configuration 15, wherein the connecting portion is formed by NCP bonding and the sealing agent is a non-conductive resin. [Examples]

[0090] Examples and comparative examples of the present invention are shown below, and the present invention will be described in more detail. However, the present invention is not limited to the following examples.

[0091] (Example 1) The liquid dispensing head is manufactured according to the process shown in Figure 11.

[0092] First, a silicon substrate with a wiring layer and electrode pads 1 formed on it is prepared, as shown in Figure 11(a). The electrode pads 1 are made of Au and are formed on TiW as a diffusion prevention layer 4. Then, a 50 nm thick TiW film is deposited on the surface of the silicon substrate as a sacrificial layer 2.

[0093] Next, as shown in Figure 11(b), a pattern of resist 17 is formed on the substrate, and the TiW, which serves as the sacrificial layer 2, is etched using the resist 17 as a mask. Hydrogen peroxide is used for etching the TiW.

[0094] Subsequently, as shown in Figure 11(c), a 45 nm thick layer of TaO is deposited as the adhesion layer 3.

[0095] Next, as shown in Figure 11(d), a pattern of resist 18 is formed on the substrate, and the TaO as the adhesion layer 3 is etched using the resist 18 as a mask (see Figure 11(e)). At this time, the area of ​​the electrode pad 1 is not covered by the resist 18. The etching of the TaO as the adhesion layer 3 is performed by anisotropic dry etching using a fluorocarbon-based gas. The sacrificial layer 2 (TiW) is used as a stopper, allowing the adhesion layer 3 to be processed without damaging the wiring or ejection element 15. As a result of this etching of the adhesion layer 3, the adhesion layer 3 on the upper surface (the side opposite to the first substrate 101) of the electrode pad 1 and ejection element 15 in the areas exposed from the resist 18 is removed, while the adhesion layer 3 remains deposited on the side of the electrode pad 1. After that, the resist 18 is removed as shown in Figure 11(e).

[0096] Subsequently, as shown in Figure 11(f), the sacrificial layer 2, TiW, is dissolved and removed with hydrogen peroxide. As mentioned above, the treatment with hydrogen peroxide does not damage the SiN on the outermost surface of the Al of the wiring, the outermost surface of the ejection element 15, or the TaO adhesion layer.

[0097] Subsequently, as shown in Figure 11(g), recesses that will become pressure chambers 11 and through holes that will become individual flow channels 10 are formed in the first substrate 101. A common flow channel and supply channel are formed in the substrate. The first substrate 101 is thus formed.

[0098] Next, as shown in Figure 11(h), the first substrate 101 and the second substrate 102 are joined together via an adhesive 9 mainly composed of benzocyclobutene resin. Then, as shown in Figure 11(i), the third substrate 103, which has an ejection port 13 processed into a silicon substrate, is joined to the first substrate 101 via an adhesive mainly composed of benzocyclobutene resin. Through the above series of steps, a liquid ejection substrate is formed.

[0099] (Example 2) In Example 1, TaO was used for the adhesion layer 3, whereas in Example 2, SiC is used for the adhesion layer 3. Except for the adhesion layer 3, everything else is the same as in Example 1. Figure 14 is a cross-sectional view of the electrode pad 1 in Example 2, and corresponds to Figure 8 of the first embodiment.

[0100] In the process of forming the adhesion layer 3 shown in Figure 11(c), a 50 nm thick SiC film is deposited. The SiC film is etched using anisotropic dry etching with a fluorocarbon-based gas.

[0101] (Example 3) In Example 1, TaO was used for the adhesion layer 3, and in Example 2, SiC was used for the adhesion layer 3. In contrast, Example 3 uses a laminated structure for the adhesion layer 3, consisting of an adhesion layer 31 made of TaO and an adhesion layer 32 made of SiC. In the process of forming the adhesion layer 3 shown in Figure 13(c), a 20 nm thick TaO film is formed, followed by a 25 nm thick SiC film.

[0102] The adhesion between the electrode pad 1, formed of Au, and the sealant 8 is in the order of TaO (adhesion layer 31) > SiC (adhesion layer 32) > sealant 8, and the adhesion between the sealant 8 and the electrode pad 1 is in the order of SiC (adhesion layer 32) > TaO (adhesion layer 31) > sealant 8. In other words, in the laminated structure of the adhesion layer 3, layers with higher adhesion to the electrode pad 1 are placed on the electrode pad 1 side, and layers with higher adhesion to the sealant 8 are placed on the sealant 8 side. By adopting this configuration, it is possible to achieve a high level of adhesion between the electrode pad 1 and the sealant 8, which leads to an improvement in the electrical reliability of the liquid ejection substrate. [Explanation of symbols]

[0103] 1 electrode pad 2 layers of victims 3. Adhesion layer 4. Diffusion prevention layer 5 wiring layer 6 Wiring cover layer 7 Wiring 8. Sealant 9 Adhesive 12 Spacers 13 Outlet 15 Discharge element 101 First substrate 102 Second substrate 103 Third substrate

Claims

1. Discharge element used for dispensing liquid, The discharge element is electrically connected via wiring, and an electrode pad is provided on the wiring, A substrate for a liquid dispensing head having, A substrate for a liquid dispensing head, wherein at least a portion of the side surface of the electrode pad is covered with an inorganic film.

2. The electrode pad comprises Au, as described in claim 1, for a substrate for a liquid discharge head.

3. The inorganic film comprises a metal oxide, as described in claim 1, for a substrate for a liquid dispensing head.

4. The substrate for a liquid discharge head according to claim 1, wherein the inorganic film comprises at least one compound selected from the group consisting of TaO, TiO, SiOC, HfO, and ZrO.

5. The substrate for a liquid discharge head according to claim 1, wherein the composition of the inorganic film is a silicon-containing compound.

6. The substrate for a liquid discharge head according to claim 1, wherein the inorganic film comprises at least one compound selected from the group consisting of SiOC, SiC, and SiCN.

7. The substrate for a liquid discharge head according to claim 1, wherein the inorganic film has a multilayer structure including a first layer in contact with the side surface of the electrode pad and a second layer exposed on the opposite side of the first layer.

8. The substrate for a liquid discharge head according to claim 7, wherein the first layer is TaO and the second layer is SiC.

9. The substrate for the liquid discharge head has wiring that electrically connects the discharge element and the electrode pad, The electrode pad is electrically connected to the wiring via a diffusion prevention layer. The substrate for a liquid discharge head according to claim 1, wherein the inorganic film covers at least a portion of the side surface of the diffusion prevention layer.

10. The substrate for a liquid discharge head according to claim 1, wherein the discharge element is a piezoelectric element.

11. Having a pad row in which multiple electrode pads are arranged, The substrate for a liquid discharge head according to claim 1, wherein in the pad row, the inorganic film is not connected between adjacent electrode pads.

12. The aforementioned substrate for the liquid dispensing head is A second substrate having the electrode pads on the first surface, A wiring is provided on the first surface for electrically connecting the discharge element and the electrode pad, A first substrate bonded to the first surface via an adhesive, It has, and further, A substrate for a liquid discharge head according to claim 1, further comprising a spacer provided between the first substrate and the second substrate at a position that does not overlap with the wiring when viewed from a direction perpendicular to the first surface.

13. Discharge element used for dispensing liquid, An electrode pad electrically connected to the discharge element, A substrate for a liquid dispensing head having, A second substrate having the electrode pads on the first surface, A wiring is provided on the first surface for electrically connecting the discharge element and the electrode pad, A first substrate bonded to the first surface via an adhesive, It has, and further, A spacer is provided between the first substrate and the second substrate, in a position that does not overlap with the wiring when viewed from a direction perpendicular to the first surface. A substrate for a liquid dispensing head, wherein at least a portion of the side surface of the spacer is covered with an inorganic film.

14. The spacer is a substrate for a liquid discharge head according to claim 13, comprising Au.

15. A substrate for a liquid discharge head according to any one of claims 1 to 14, A wiring board having wiring that is electrically connected to the electrode pads, A sealant covering the connection between the electrode pad and the wiring, A liquid dispensing head having a liquid dispensing head.

16. The liquid dispensing head according to claim 15, wherein the connecting portion is formed by NCP bonding, and the sealing agent is a non-conductive resin.

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