Manufacturing method of substrate for liquid discharge head and substrate for liquid discharge head

Abstract

To suppress quality degradation of a substrate for a liquid discharge head and efficiently manufacture the substrate for the liquid discharge head.SOLUTION: A manufacturing method of a substrate for a liquid discharge head includes: a drilling process for forming a hole 2 on a first surface 23a of a substrate 23; a hydrophobic layer formation process for forming a hydrophobic layer 3 on the first surface 23a so as to cover an edge of the hole 2; a joining process for joining a protective member 4 to the first surface 23a through the hydrophobic layer 3; a grinding process for grinding a second surface 23b on an opposite side of the first surface 23a of the substrate 23 and forming a through hole 5 by exposing the hole 2 to the second surface side; a cleaning process for jetting cleaning fluid toward the ground surface 23c ground in the grinding process and the through hole 5; and a peeling process for peeling the protective member 4.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a substrate for a liquid ejection head. [Background technology]

[0002] Silicon microfabricated structures are widely used in the field of MEMS and functional devices for electromechanical devices. One example is a liquid ejection head that ejects liquid such as ink. A liquid ejection head is provided with a liquid ejection head substrate, which is made of a silicon substrate on which ejection ports and flow paths communicating with the ejection ports are formed. Liquid is ejected from the ejection ports of the substrate by energy generated by energy generating elements provided in the substrate.

[0003] One example of a method for manufacturing a substrate for a liquid ejection head is a thin-through process in which a bottomed hole is formed in the surface of a silicon substrate (base material), a protective member is bonded to the surface of the base material, and the surface opposite to the protective member bonding surface is then ground to expose the hole and form a through-hole. The through-hole formed in the base material constitutes a flow path for liquid ejected from the ejection port. If fragments of the base material generated in the grinding process for thin-through process penetrate into the interface between the base material and the protective member, it can contaminate the surface of the base material and reduce the quality of the substrate for a liquid ejection head.

[0004] Patent Document 1 discloses a method of filling an interference prevention material when thinning and penetrating in the manufacture of a substrate for a liquid ejection head. In the above-mentioned manufacturing method, a bottomed cut groove is formed in a substrate, and then the cut groove is filled with an interference prevention material, and the substrate is ground to expose the cut groove, thereby dividing the substrate into multiple substrates. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2001-176822 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the above-mentioned manufacturing method is applied to thinning through-holes for forming flow paths in a substrate for a liquid ejection head, a process of removing the interference prevention member from the through-holes after thinning through-holes is required. Furthermore, when the aspect ratio of the through-holes is large, it is difficult to fill or remove the interference prevention member without gaps, and residues of the interference prevention member may occur inside the through-holes, which may lead to a deterioration in the quality of the substrate for a liquid ejection head.

[0007] In view of the above-mentioned problems, an object of the present invention is to suppress deterioration in the quality of liquid ejection head substrates and efficiently manufacture liquid ejection head substrates. [Means for solving the problem]

[0008] In order to achieve the above object, a method for manufacturing a substrate for a liquid ejection head according to the present invention comprises the steps of: A method for manufacturing a substrate for a liquid ejection head having an ejection port for ejecting liquid, comprising the steps of: a drilling step of forming holes in a first surface of the substrate; a hydrophobic layer forming step of forming a hydrophobic layer on the first surface so as to cover edges of the holes; a bonding step of bonding a protective member to the first surface via the hydrophobic layer; a grinding step of grinding a second surface of the base material opposite to the first surface to expose the hole on the second surface side to form a through hole; a cleaning step of spraying a cleaning liquid toward the ground surface and the through hole; a peeling step of peeling off the protective member; The present invention is characterized by comprising: In order to achieve the above object, the liquid ejection head substrate of the present invention comprises: a discharge port forming member in which a discharge port for discharging liquid is formed; a first substrate having a first surface and a second surface opposite to the first surface, the first substrate having a through hole formed therein, the through hole penetrating from the first surface to the second surface; a second substrate bonded to the first substrate and having a liquid flow path formed therein that connects the through hole and the ejection port; Equipped with The first substrate has a hydrophobic layer formed on the first surface thereof so as to cover an edge of the through hole. Effect of the Invention

[0009] According to the present invention, deterioration in the quality of the liquid discharge head substrate can be suppressed, and the liquid discharge head substrate can be efficiently manufactured. [Brief description of the drawings]

[0010] [Figure 1] 1A and 1B are diagrams showing a configuration of a liquid ejection head substrate according to a first embodiment. [Diagram 2] 3A to 3C are explanatory diagrams of a method for manufacturing a first substrate according to the first embodiment. [Diagram 3] 10A to 10C are explanatory diagrams of a method for manufacturing a first substrate according to a modified example. [Figure 4] 10A to 10C are explanatory diagrams of a process for removing adhesive material residue. [Diagram 5] FIG. 11 is a top view of a first substrate according to a second embodiment. [Figure 6] 1A to 1C are explanatory diagrams of a method for forming a hydrophobic region and a hydrophilic region. [Figure 7] FIG. 4 is an explanatory diagram of a step of drilling a hole in a first substrate according to the embodiment. [Figure 8] 5A to 5C are explanatory views of a substrate bonding process for a first substrate and a second substrate according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings. Note that the dimensions, materials, shapes, and relative positions of the components described in the embodiment may be changed as appropriate depending on the configuration of the device to which the invention is applied and various conditions. In other words, the scope of the present invention is not limited to the following embodiment.

[0012] In addition, not all of the combinations of features described in the following embodiments are necessarily essential to the solving means of the present invention. Note that the same components in each embodiment will be described with the same reference numerals.

[0013] The present invention relates to a liquid ejection head that ejects liquid onto a recording medium to perform recording or the like, and a substrate for the liquid ejection head that is provided in the liquid ejection head. The present invention can be desirably applied to, for example, an inkjet head of an inkjet recording method that performs recording by foaming liquid such as ink using thermal energy. Below, an example in which the present invention is applied to an inkjet head will be described, but the liquid ejection head of the present invention is not limited to this, and can be applied to various liquid ejection heads and substrates for liquid ejection heads that eject liquid using thermal energy. In addition, a piezoelectric element may be used as a generating element for generating energy to eject liquid in the liquid ejection head.

[0014] (First embodiment) <Liquid ejection head substrate> First, the configuration of a substrate 100 for a liquid ejection head according to the first embodiment will be described. In the substrate 100 for a liquid ejection head, a plurality of ejection ports 19 for ejecting liquid are arranged in the ejection port array direction so as to form a plurality of ejection port arrays. FIGS. 1(a) and (b) show the substrate 100 for a liquid ejection head according to the first embodiment. 1A is a schematic top view of the liquid ejection head substrate 100, as viewed in a direction perpendicular to the ejection port formation surface on which ejection ports 19 are formed. FIG. 1B is a schematic cross-sectional view of the liquid ejection head substrate 100, as viewed from the ejection ports 19 in the ejection port array direction.

[0015] The liquid ejection head substrate 100 is a recording element substrate having a plurality of ejection ports 19 and energy generating elements 12 that generate energy for ejecting liquid from the ejection ports 19. The energy generating elements 12 are provided at positions corresponding to the respective ejection ports 19. The liquid ejection head substrate 100 is composed of a first substrate 101 in which a through hole 5 that constitutes a flow path communicating with the ejection ports 19 is formed, and a second substrate 102 in which a flow path communicating with the ejection ports 19 and the through hole 5 is formed. The first substrate 101 and the second substrate 102 are joined to each other by an adhesive 15.

[0016] Inside the second substrate 102, a common flow path 13 and an individual flow path 14 are formed, which communicate with the discharge port 19 via the liquid flow path 20. A flow path forming member 18 constituting the liquid flow path 20 and a discharge port forming member 17 constituting the discharge port 19 are provided on the surface of the second substrate 102 on the side where the individual flow path 14 is open. The first substrate 101 is bonded to the surface of the second substrate 102 on the side where the common flow path 13 is open, and the common flow path 13 of the second substrate 102 is connected to the through hole 5 of the first substrate 101. The liquid is discharged from the discharge port 19 through the through hole 5, the common flow path 13, the individual flow path 14, and the liquid flow path 20 in this order inside the substrate 100 for liquid discharge head.

[0017] <Method for manufacturing the first substrate> Next, a method for manufacturing the first substrate 101 constituting the substrate 100 for a liquid ejection head will be described. Fig. 2(a) to (g) are explanatory diagrams of the method for manufacturing the first substrate 101. Fig. 2(a) is a top view of the first substrate 101 as seen in the penetrating direction of the through-hole 5. In Fig. 2(a), the hydrophobic layer 3 is filled in with a dashed line in order to distinguish between the through-hole 5 and the hydrophobic layer 3. Figs. 2(b) to (g) are cross-sectional views taken along the line AA of Fig. 2(a) showing each step of the method for manufacturing the first substrate 101.

[0018] 2(a), a row of through holes 5 corresponding to each of the ejection port rows is formed in the first substrate 101. The row of through holes is configured such that through holes 5 located at first positions in a direction perpendicular to the ejection port row direction and through holes 5 located at second positions shifted from the first positions are alternately arranged.

[0019] The method for manufacturing the first substrate 101 according to the first embodiment includes the following steps (1) to (5). (1) A drilling step for forming holes of a predetermined depth from a first surface of a substrate (2) A hydrophobic layer forming step of forming a hydrophobic layer on a first surface of a substrate. (3) A bonding process in which a protective material is attached onto the hydrophobic layer (4) A grinding step of grinding and polishing the second surface of the substrate to form a through hole. (5) A cleaning process for cleaning the inside of the through-holes and the thinned surface of the substrate.

[0020] (1) A drilling step for forming holes of a predetermined depth from a first surface of a substrate 2(b) is a schematic cross-sectional view showing the hole drilling step. In the hole drilling step, a hole drilling process is performed on the first surface 23a of the substrate 23, and a plurality of holes 2 are formed in the substrate 23. The holes 2 are formed to a predetermined depth from the first surface 23a of the substrate 23. In the first embodiment, the depth of the holes 2 is set so that the distance from the bottom surface 2a of the holes 2 to the second surface 23b opposite to the first surface 23a of the substrate 23 is smaller than the grinding depth in the subsequent grinding step. The holes 2 that become the through holes 5 can be used as liquid flow paths.

[0021] The processing method of the hole 2 is not particularly limited as long as the hole 2 can be processed to a desired depth. For example, dry etching can be used as the processing method of the hole 2. Dry etching is preferable because the hole 2 can be processed vertically and with a high aspect ratio using an etching mask pattern, and the processing depth can be easily controlled. Dry etching is performed while generating high frequency waves to apply a bias to the substrate 23, and it is possible to use, for example, general RIE dry etching using ECR, ICP, or the like as a plasma source. In addition, for example, laser processing, crystal anisotropic etching, or the like can be used for the hole drilling processing.

[0022] (2) A hydrophobic layer forming step of forming a hydrophobic layer on a first surface of a substrate. 2(c) is a schematic cross-sectional view showing a hydrophobic layer forming step. In the hydrophobic layer forming step, a hydrophobic layer 3 is formed on the first surface 23a of the substrate 1. The hydrophobic layer 3 is formed at least around the hole 2 on the first surface 23a of the base material 23.

[0023] The hydrophobic layer 3 is a layer that reduces the surface energy of the substrate 23. By forming the hydrophobic layer 3 between the substrate 23 and the protective member 4 that will be joined in a later protective member joining step, it is possible to prevent liquids such as water and chemical solutions from penetrating the interface between the substrate 23 and the protective member 4. The larger the contact angle of the hydrophobic layer 3, the greater the effect of preventing the penetration of aqueous liquids. It has been experimentally confirmed that a contact angle of the hydrophobic layer 3 of 60 degrees or more prevents the penetration of aqueous liquids, and a contact angle of 70 degrees or more is more preferable.

[0024] The hydrophobic layer 3 can be formed by subjecting the substrate surface to a hydrophobic treatment using a hydrophobic material, or by forming the hydrophobic layer 3 as a hydrophobic film. As the hydrophobic material for forming the hydrophobic layer 3, long-chain alkylsilanes such as hexamethyldisilazane (HMDS), octyltrichlorosilane, decyltrichlorosilane, and octadecyltrichlorosilane can be used. As the hydrophobic material, fluoroalkylsilanes such as fluorinated octyltrichlorosilane, and silane coupling agents such as beta-phenethyltrichlorosilane can also be used. As the hydrophobic material, polystyrene, polyethylene, parylene, polyimide, fluorinated polymers, and polymers without hydroxyl groups such as divinyl-tetramethylsiloxane-bisbenzocyclobutene (BCB) can also be used.

[0025] As the hydrophobic treatment, for example, a silane coupling treatment can be used. The silane coupling treatment using a silane coupling agent has the effect of reducing the polar components of the substrate surface. In other words, hydrophilic groups such as hydroxyl groups present on the substrate surface are replaced with hydrophobic groups (lipophilic groups). In addition, since the silane coupling treatment does not require a vacuum system, the equipment is relatively simple, and it is a highly versatile surface modification treatment. The surface stability after the silane coupling treatment is also high, making it preferable for permeation control in a wet process. Specifically, by using hexamethyldisilazane (HMDS) as a silane coupling agent for the hydrophobic treatment, the hydroxyl groups on the substrate surface are replaced with trimethylsilyl groups. This replacement reaction can reduce the surface energy of the substrate surface.

[0026] The hydrophobic layer 3 may also be formed on the inner wall surface of the hole 2. FIG. 3(a) is a schematic cross-sectional view showing a modified example of the hydrophobic layer forming step. By forming the hydrophobic layer 3 on the inner wall surface near the first surface 23a of the hole 2 in continuity with the substrate surface, the hydrophobic layer region is expanded, and water and chemicals are less likely to penetrate into the interface between the first surface 23a of the substrate 23 and the protective member 4. Therefore, in order to prevent the intrusion of water and chemicals, it is more preferable to form the hydrophobic layer 3 so as to extend to the inner wall surface of the hole 2. Even when such a hydrophobic layer 3 is formed, the subsequent bonding step and grinding step can be performed in the same manner. FIG. 3(b) is a schematic cross-sectional view showing the bonding step according to the modified example, and FIG. 3(c) is a schematic cross-sectional view showing the grinding step according to the modified example. The details of the bonding step and grinding step will be described later.

[0027] The hydrophobic layer 3 as shown in FIG. 3(a) is formed by applying a hydrophobic material to a substrate 23 by spin coating. The hydrophobic layer 3 can be formed by exposing the substrate 23 to an atmosphere of the hydrophobic material in the form of a cloth, vapor, or gas. If the hydrophobic material is used when holes are formed in the substrate surface, there is a risk that the hydrophobic material will not spread well by spin coating. Therefore, exposure to the vapor or gas of the hydrophobic material is preferable because it allows the hydrophobic layer 3 to be formed stably and also promotes the coupling reaction. The higher the bake temperature and the longer the bake time, the higher the contact angle, so a bake temperature of 120°C or higher and a bake time of 2 minutes or more are preferable.

[0028] (3) A bonding process in which a protective material is attached onto the hydrophobic layer 2(d) is a schematic cross-sectional view showing a bonding step of the protective member 4. In the bonding step, the protective member 4 is attached and bonded onto the hydrophobic layer 3. The protective member 4 has functions such as protecting the first surface 23a of the substrate 23 and mitigating the pressing force applied to the substrate 23 in the subsequent grinding step and cleaning step. As the protective member 4, for example, a backgrind tape such as a general protective tape for grinding is preferably used.

[0029] The protective member 4 is composed of at least a base layer and an adhesive layer. The protective member 4 may have an intermediate layer between the base layer and the adhesive layer. The adhesive layer of the protective member 4 is preferably made of a material having high adhesion to the substrate 23. Since an acrylic adhesive has high adhesion to the surface of a silicon substrate that has been hydrophobized with HMDS, the intrusion of aqueous chemicals can be further reduced by using an acrylic adhesive as the adhesive layer. By using a material whose adhesive strength changes with ultraviolet light or heat for the adhesive layer, attachment and removal can be easily controlled. In addition, the protective member 4 is preferably attached under a vacuum so that no air bubbles or the like are trapped between the protective member 4 and the substrate 23.

[0030] (4) A grinding step of grinding and polishing the second surface of the substrate to form a through hole. Fig. 2(e) is a schematic cross-sectional view showing the grinding step of the base material 23. The grinding step is a step of grinding and polishing the base material 23 from the second surface side until the hole 2 is exposed on the second surface side, thereby forming the through hole 5. As shown in Fig. 2(e), the base material 23 is ground from the second surface 23b opposite to the first surface 23a in which the hole 2 is formed, so that the base material 23 is formed to a predetermined thickness, and the bottom portion of the hole 2 is removed. As a result, the through hole 5 is formed which penetrates the base material 23 in the thickness direction and opens on both sides of the first substrate 101.

[0031] Grinding of the substrate 23 can be performed using a general back grinding device. If high flatness is required for the thinned surface 23c, which is the ground surface, a smooth surface with low surface roughness can be obtained by polishing after grinding. For example, chemical mechanical polishing (CMP) can be performed as the polishing, which simultaneously performs chemical processing using components contained in an abrasive (slurry) and mechanical polishing. At this time, the hydrophobic layer 3 suppresses the infiltration of the slurry during polishing by CMP after the through-holes are formed.

[0032] (5) A cleaning process for cleaning the inside of the through-holes and the thinned surface of the substrate. Fig. 2(f) is a schematic cross-sectional view showing a cleaning step. In the cleaning step, chemicals or water is sprayed from the thinned surface 23c side onto the substrate 1 having the through-holes 5 and the protective member 4, thereby cleaning the insides of the through-holes 5 and the thinned surface 23c. In Fig. 2(f), the spray direction of the chemicals or water sprayed in the cleaning step is indicated by a dotted line with an arrow.

[0033] After the grinding step, fragments of the base material 23 generated during grinding, abrasive grains from the grinding wheel, and slurry residue generated during polishing may adhere to the inside of the through-hole 5 and the surface layer of the thinned surface 23c. Since the through-hole 5 constitutes a flow path through which the liquid discharged from the discharge port 19 of the liquid discharge head substrate 100 passes, a particularly high degree of cleanliness is required so that no impurities remain on the inner wall surface of the through-hole 5. For this reason, it is preferable to use buffered hydrofluoric acid, which can dissolve silica, the main component of the slurry, as the cleaning liquid used in the cleaning step.

[0034] In the cleaning step according to the first embodiment, the substrate 23 with the protective member 4 attached thereto is cleaned with buffered hydrofluoric acid, and rinsed with pure water to remove debris and slurry residue from within the through-holes 5. If cleaning is performed after the protective member 4 is peeled off from the substrate 23, the chemical solution moves to both sides of the substrate 23 through the through-holes 5, and the chemical solution in which the slurry is dissolved adheres and dries, which may leave stain-like residues. Therefore, a highly clean surface can be obtained by protecting the first surface 23a from the cleaning solution or rinsing water with the protective member 4, and applying the cleaning solution or water to the thinned surface 23c side to clean it. The cleaning step may be performed using a general batch-type cleaning device, or a cleaning device capable of spin rotation on a sheet basis may be used to improve the discharge of the chemical solution and water from within the through-holes.

[0035] 2(g) is a schematic cross-sectional view showing a step of peeling off the protective member 4. After cleaning, the protective member 4, which is no longer needed, is peeled off. When the protective member 4 is peeled off, an adhesive material such as an adhesive layer of the protective member 4 may remain as a residue 9 on the first substrate 101. Therefore, it is preferable to carry out a step of removing the adhesive material residue 9 after the peeling step.

[0036] 4(a) to 4(c) are explanatory diagrams of the step of removing the adhesive material residue 9. Fig. 4(a) is a schematic cross-sectional view showing the state in which the adhesive material residue 9 is attached on the hydrophobic layer 3 after the peeling step. Fig. 4(b) is a schematic cross-sectional view showing the step of removing the residue 9. Fig. 4(c) is a schematic cross-sectional view showing the first substrate 101 after the removal step.

[0037] When the adhesive material is an organic substance, the residue 9 can be removed by performing O2 plasma ashing as a removal process. At this time, if the hydrophobic layer 3 is made of a hydrophobic material that can be removed by ashing, the entire surface of the hydrophobic layer 3 may be ashed to remove the hydrophobic layer 3, as shown in FIG. 4(b).

[0038] As described above, according to the manufacturing method of the first embodiment, by performing the hydrophobic layer forming step and the cleaning step, the quality deterioration of the first substrate 101 caused by the debris and slurry generated in the grinding step can be suppressed. For example, when the hole 2 is filled with a curable liquid resin as an interference prevention member in order to suppress the quality deterioration, if the aspect ratio (hole depth / hole diameter) of the hole 2 is large, it is difficult to fill the hole 2 with the interference prevention member. In addition, when the interference prevention member is ground during the grinding step, the resin may adhere to the grindstone, and the flatness of the thinned surface (ground surface) 23c may deteriorate. On the other hand, according to the first embodiment, since it is not necessary to fill the hole 2 with an interference prevention member, etc., the quality deterioration of the first substrate 101 can be suppressed while solving the above-mentioned problem, and further, the quality deterioration of the liquid discharge head substrate 100 can be suppressed. In addition, unlike the interference member, the hydrophobic layer 3 does not necessarily need to be removed from the first substrate 101, so the first substrate 101 and the liquid discharge head substrate 100 can be efficiently manufactured.

[0039] Second embodiment Next, a second embodiment of the present invention will be described. The second embodiment differs from the first embodiment in the region where the hydrophobic layer 3 is formed. Hereinafter, only the configuration of the second embodiment that differs from the configuration of the first embodiment will be described. In the configuration of the second embodiment, the same reference numerals will be used for the same components as those in the first embodiment, and the description will be omitted.

[0040] 5 is a top view of the first substrate 101 according to the second embodiment when viewed in the penetrating direction of the through-hole 5. As shown in FIG. 2(a), in the first embodiment, the hydrophobic layer 3 is formed on the entire surface of the first surface 23a of the base material 23 of the first substrate 101. On the other hand, in the second embodiment, the hydrophobic layer 3 is formed only around the opening of the through-hole 5 on the first surface 23a of the base material 23 of the first substrate 101.

[0041] By forming the hydrophobic layer 3 in the vicinity of the through-hole 5 (hole 2), in the same manner as in the first embodiment, the intrusion of an aqueous chemical into the interface between the base material 23 and the protective member 4 during the manufacturing process of the first substrate 101 is suppressed. On the other hand, the portion where the hydrophobic layer 3 is not formed is made hydrophilic compared to the portion where the hydrophobic layer is formed. This manufacturing method for forming a hydrophilic region is particularly suitable for the case where another member is bonded to the first surface 23a of the first substrate 101.

[0042] When another member is bonded to the first surface 23a via an adhesive, the adhesive bonding area 6 to which the adhesive is bonded is preferably hydrophilic so that the adhesive can be bonded accurately. In such a case, it is desirable to perform pattern formation on the first surface 23a by distinguishing between hydrophobic areas and hydrophilic areas.

[0043] 6(a) to 6(d) are explanatory diagrams of a method for forming the hydrophobic region and the hydrophilic region. For example, the method for forming the hydrophobic region and the hydrophilic region may include a mask setting step prior to the hydrophobic layer forming step, in which a mask member 7 having mask openings 8 is set on the substrate 23, and the hydrophobic layer 3 is formed with the mask member 7 set.

[0044] Fig. 6(a) is a top view showing the state where the mask member 7 is placed on the first surface 23a of the substrate 23, and Fig. 6(b) is a cross-sectional view thereof. In the second embodiment, in order to form hydrophobic regions and hydrophilic regions on the surface of the substrate 23, the mask member 7 is placed on the first surface 23a of the substrate 23 after the hole making step and before the hydrophobic layer forming step. The mask opening 8 of the mask member 7 is disposed at a position overlapping with the hole 2 when viewed in the depth direction of the hole 2, and the periphery of the opening of the hole 2 is exposed and not covered by the mask member 7.

[0045] Fig. 6(c) is a schematic cross-sectional view showing a hydrophobic layer forming step according to the second embodiment. In the second embodiment, the hydrophobic layer 3 is formed around the opening of the hole 2 and on the mask member 7. Thereafter, in a mask removing step, the mask member 7 is removed and the hydrophobic layer 3 formed in contact with the mask member 7 is lifted off. Fig. 6(d) is a schematic cross-sectional view showing the mask removing step.

[0046] Through the above steps, a hydrophobic region where the hydrophobic layer 3 is formed and a hydrophilic region where the hydrophobic layer 3 is not formed are formed on the first surface 23a of the base material 23. Then, an adhesive is applied to the hydrophilic region of the first surface 23a, and other members can be bonded onto the first surface 23a.

[0047] (Example) Next, a specific method for manufacturing the liquid ejection head substrate 100 according to the first embodiment will be described by way of example. First, the hole making step (1) will be described. Figures 7(a) to (d) are explanatory diagrams of the hole making step for the first substrate 101 according to the example.

[0048] The substrate 23 is a silicon substrate having a substrate thickness of 725 μm. In the hole forming step, first, the positive resist 10 is applied to the first surface 23a of the substrate 23. Fig. 7(a) is a schematic cross-sectional view showing the step of applying the positive resist 10.

[0049] Next, photolithography is used to pattern the opening shape of the hole 2. Fig. 7(b) is a schematic cross-sectional view showing the patterning step. In this embodiment, the cross-sectional shape of the hole 2 is a rectangle with a length of 1000 µm and a width of 300 µm.

[0050] Thereafter, holes 2 are formed to a depth of 320 μm using the Bosch process with the patterned positive resist 10 as an etching mask. FIG. 7(c) is a schematic cross-sectional view showing the step of forming holes 2.

[0051] After etching, the etching mask (positive resist 10) is removed by wet processing using a stripping solution. FIG. 7(d) is a schematic cross-sectional view showing the etching mask removal step. Through the above steps, holes 2 of a desired shape are formed so as to open on the first surface 23a of the base material 23.

[0052] The hydrophobic layer formation step (2) shown in Fig. 2(c) will be described. The first surface 23a of the substrate 23 is exposed to HMDS vapor while heating the substrate 23 to 150°C, thereby forming the hydrophobic layer 3. Pure water was dropped onto the hydrophobic layer 3 formed by this procedure, and the contact angle of the droplet was measured to be 72 degrees.

[0053] The bonding process of the protective member 4 (3) shown in Fig. 2(d) will be described. In the bonding process, after the hydrophobic layer 3 is formed, the protective member 4 is mounted on the hydrophobic layer 3. The protective member 4 is a backgrind tape whose adhesive layer is an acrylic adhesive. The tape mounting was performed in a vacuum of 80 Pa or less while heating the substrate 23 to 50°C.

[0054] The grinding step (4) shown in Fig. 2(e) will now be described. In the grinding step, the substrate 23 was ground by a grinding / polishing device until the substrate thickness was 305 µm, and then chemical mechanical polishing was performed using a slurry until the substrate thickness was 300 µm. Through this grinding step, the bottom of the hole 2 was thinned and penetrated, forming a through hole 5.

[0055] 2(f), the cleaning step (5) will be described. In the cleaning step, a spin-type cleaning device is used, and the inside of the through-hole 5 and the thinned surface 23c are cleaned with buffered hydrofluoric acid, and then rinsed with pure water.

[0056] The peeling process of the protective member 4 shown in FIG. 2(g) will be described. After cleaning, the protective member 4, which is a back-grind tape, was peeled off while being heated at 50° C. Then, as a process for removing the adhesive material residue 9, the adhesive of the tape remaining on the surface was removed by ashing. The first substrate 101 was produced through the above-mentioned drilling process, hydrophobic layer forming process, bonding process, grinding process, cleaning process, peeling process, and removal process in this order. Note that the hydrophobic layer 3 does not necessarily need to be completely removed in the removal process, and the next substrate bonding process may be performed in a state in which the hydrophobic layer 3 is formed on the first surface 23a of the first substrate 101.

[0057] After the first substrate 101 is produced, the first substrate 101 and the second substrate 102 are bonded together in a substrate bonding process. Figures 8(a) to 8(c) are explanatory views of the substrate bonding process of the first substrate 101 and the second substrate 102. The second substrate 102 has energy generating elements 12 made of TaSiN and used to eject liquid, an electric circuit (not shown) that drives the energy generating elements 12, and an electric connection part (not shown) that is electrically connected to an electric connection board.

[0058] In the second substrate 102, a common flow path 13 and individual flow paths 14 are formed in advance by a processing method similar to the processing method of the holes 2 shown in Figs. 7(a) to (d). The common flow path 13 opens on one end face of the second substrate 102, and the individual flow paths 14 open on the other end face of the second substrate 102, and the common flow path 13 and the individual flow paths 14 communicate with the through holes 5 and the discharge ports 19. The second substrate 102 is a silicon substrate, and is thinned by a grinding device so that the substrate thickness is 625 µm. The manufacturing method of the second substrate 102 is not limited to the above, and any known substrate manufacturing method can be adopted.

[0059] When bonding the first substrate 101 and the second substrate 102, first, an adhesive is applied to a transfer substrate for transferring the adhesive. A benzocyclobutene solution is used as the adhesive, and the benzocyclobutene solution is spin-coated to a thickness of 3 μm on the transfer substrate. A PET film was used as the transfer substrate. After spin-coating, a baking process is performed at 100° C. for 5 minutes to volatilize the solvent. Then, the adhesive 15 formed on the transfer substrate is transferred to the bonding surface of the second substrate 102 (the surface on which the common flow path 13 is open) while applying heat. By bringing them into contact with each other, the adhesive 15 is transferred to the joining surface of the second substrate 102 .

[0060] 8(a) is a schematic cross-sectional view showing a state immediately before bonding the first substrate 101 and the second substrate 102. A bonding alignment device is used for bonding the first substrate 101 and the second substrate 102, and the first substrate 101 and the second substrate 102 are heated in a vacuum while being aligned and bonded. The bonding conditions were a degree of vacuum of 100 Pa or less and a temperature of 150°C.

[0061] After the bonding is completed, the first substrate 101 and the second substrate 102 are cooled and then removed from the apparatus. Then, the first substrate 101 and the second substrate 102 are heat-treated in an oven in a nitrogen atmosphere at 250° C. for 1 hour to harden the adhesive. FIG. 8(b) is a schematic cross-sectional view showing the first substrate 101 and the second substrate 102 bonded to each other via the adhesive 15.

[0062] After bonding the first substrate 101 and the second substrate 102, a liquid flow path 20 connected to the individual flow path 14 and a discharge port 19 connected to the liquid flow path 20 are formed in the second substrate 102 as a discharge port forming process. First, a negative photosensitive resin dissolved in a PGMEA (propylene glycol methyl ether acetate) solvent is spin-coated on a PET film, and dried at 100°C in an oven to form a dry film. The dry film is then transferred to the surface of the second substrate 102 on which the energy generating elements 12 are formed, and the dry film is laminated. The PET film is then peeled off. After the dry film is formed, exposure and PEB (post-exposure bake) are performed to form a flow path pattern of the liquid flow path 20, and the dry film is made into a latent image state.

[0063] Next, a dry film is laminated in the same manner as for the liquid flow path 20, and exposure and PEB are performed to form a flow path pattern of the ejection port 19, and the dry film is put into a latent image state. Then, the liquid flow path 20 and the ejection port 19 are developed together, and the liquid ejection head substrate 100 is produced.

[0064] The disclosure of this embodiment includes the following configuration. (Configuration 1) A method for manufacturing a substrate for a liquid ejection head having an ejection port for ejecting liquid, comprising the steps of: a drilling step of forming holes in a first surface of the substrate; a hydrophobic layer forming step of forming a hydrophobic layer on the first surface so as to cover edges of the holes; a bonding step of bonding a protective member to the first surface via the hydrophobic layer; a grinding step of grinding a second surface of the base material opposite to the first surface to expose the hole on the second surface side to form a through hole; a cleaning step of spraying a cleaning liquid toward the ground surface and the through hole; a peeling step of peeling off the protective member; 2. A method for manufacturing a substrate for a liquid ejection head, comprising: (Configuration 2) 2. The method for manufacturing a substrate for a liquid ejection head according to configuration 1, wherein in the hydrophobic layer forming step, the hydrophobic layer is formed on the entire surface of the first surface. (Configuration 3) A method for manufacturing a substrate for a liquid ejection head, as described in configuration 1, characterized in that in the hydrophobic layer forming process, a hydrophobic layer is formed on the inner wall surface of the hole formed in the hole drilling process, continuous with the hydrophobic layer formed on the first surface. (Configuration 4) 4. The method for producing a substrate for a liquid ejection head according to any one of configurations 1 to 3, wherein the contact angle of the hydrophobic layer is 60 degrees or more. (Configuration 5) a mask setting step of setting a mask member having openings corresponding to the holes on the first surface after the hole making step and before the hydrophobic layer forming step; a mask removing step of removing the mask member after the hydrophobic layer forming step and before the bonding step; Including, A method for manufacturing a substrate for a liquid ejection head, described in any one of configurations 1 to 4, characterized in that in the hydrophobic layer formation process, a hydrophobic region in which the hydrophobic layer is formed on the first surface and a hydrophilic region that is hydrophilic relative to the hydrophobic region are formed. (Configuration 6) A method for manufacturing a substrate for a liquid ejection head, described in any one of configurations 1 to 5, characterized in that in the hydrophobic layer formation process, the hydrophobic layer is formed by exposing the base material to vapor or gas of a hydrophobic material. (Configuration 7) In the hydrophobic layer forming step, hexamethyldisilazane is used as a hydrophobic material for forming the hydrophobic layer, 7. The method for producing a substrate for a liquid ejection head according to any one of configurations 1 to 6, wherein the protective member has an adhesive layer made of an acrylic adhesive. (Configuration 8) 8. The method for producing a substrate for a liquid ejection head according to any one of configurations 1 to 7, wherein the cleaning step is carried out before the peeling step. (Configuration 9) The method for manufacturing a substrate for a liquid ejection head according to any one of configurations 1 to 8, further comprising, after the peeling step, a removing step of removing residue of the protective material remaining on the hydrophobic layer. (Configuration 10) 10. The method of manufacturing a substrate for a liquid ejection head according to configuration 9, wherein in the removing step, the hydrophobic layer is removed together with the residue of the protective member. (Configuration 11) The cleaning solution is buffered hydrofluoric acid, 11. A method for manufacturing a substrate for a liquid ejection head according to any one of configurations 1 to 10, characterized in that in the cleaning step, after cleaning the ground surface and the through hole with buffered hydrofluoric acid, the ground surface and the through hole are rinsed with pure water. (Configuration 12) 12. The method for producing a liquid ejection head substrate according to any one of configurations 1 to 11, wherein in the hole making step, the holes are formed by etching. (Configuration 13) A method for manufacturing a substrate for a liquid ejection head according to any one of configurations 1 to 12, characterized in that the method includes a substrate bonding process of bonding the first substrate to a second substrate having a flow path formed therein that connects the through hole and the ejection port, where the base material having the through hole formed therein is a first substrate. (Configuration 14) 14. The method of manufacturing a substrate for a liquid ejection head according to configuration 13, further comprising, after the substrate bonding step, a step of forming the ejection port. (Configuration 15) a discharge port forming member in which a discharge port for discharging liquid is formed; a first substrate having a first surface and a second surface opposite to the first surface, the first substrate having a through hole formed therein, the through hole penetrating from the first surface to the second surface; a second substrate bonded to the first substrate and having a liquid flow path formed therein that connects the through hole and the ejection port; Equipped with The liquid ejection head substrate, wherein a hydrophobic layer is formed on the first surface of the first substrate so as to cover edges of the through holes. [Explanation of symbols]

[0065] 2...hole, 3...hydrophobic layer, 4...protective member, 5...through hole, 23...base material, 23a...first surface, 23b...second surface, 10...liquid ejection head substrate

Claims

1. A method for manufacturing a substrate for a liquid ejection head having an ejection port for ejecting liquid, comprising the steps of: a drilling step for forming holes in a first surface of the substrate; a hydrophobic layer forming step of forming a hydrophobic layer on the first surface so as to cover edges of the holes; a bonding step of bonding a protective member to the first surface via the hydrophobic layer; a grinding step of grinding a second surface of the base material opposite to the first surface to expose the hole on the second surface side to form a through hole; a cleaning step of spraying a cleaning liquid toward the ground surface and the through hole; a peeling step of peeling off the protective member; 2. A method for manufacturing a substrate for a liquid ejection head, comprising:

2. 2. The method for manufacturing a substrate for a liquid ejection head according to claim 1, wherein the hydrophobic layer is formed on the entire surface of the first surface in the hydrophobic layer forming step.

3. 2. The method for manufacturing a substrate for a liquid ejection head according to claim 1, characterized in that in the hydrophobic layer forming process, a hydrophobic layer is formed on the inner wall surface of the hole formed in the hole drilling process, continuous with the hydrophobic layer formed on the first surface.

4. 2. The method for manufacturing a substrate for a liquid discharge head according to claim 1, wherein the contact angle of the hydrophobic layer is 60 degrees or more.

5. a mask setting step of setting a mask member having openings corresponding to the holes on the first surface after the hole making step and before the hydrophobic layer forming step; a mask removing step of removing the mask member after the hydrophobic layer forming step and before the bonding step; Including, A method for manufacturing a substrate for a liquid ejection head as described in claim 1, characterized in that, in the hydrophobic layer forming process, a hydrophobic region in which the hydrophobic layer is formed on the first surface and a hydrophilic region that is hydrophilic relative to the hydrophobic region are formed.

6. 2. The method for manufacturing a substrate for a liquid ejection head according to claim 1, wherein in the hydrophobic layer forming step, the hydrophobic layer is formed by exposing the base material to vapor or gas of a hydrophobic material.

7. In the hydrophobic layer forming step, hexamethyldisilazane is used as a hydrophobic material for forming the hydrophobic layer, 2. The method for manufacturing a substrate for a liquid ejection head according to claim 1, wherein the protective member has an adhesive layer made of an acrylic adhesive.

8. 2. The method for manufacturing a substrate for a liquid ejection head according to claim 1, wherein the cleaning step is carried out before the peeling step.

9. 2. The method for manufacturing a substrate for a liquid ejection head according to claim 1, further comprising, after the peeling step, a removing step of removing residue of the protective member remaining on the hydrophobic layer.

10. 10. The method for manufacturing a substrate for a liquid ejection head according to claim 9, wherein the hydrophobic layer is removed together with the residue of the protective member in the removing step.

11. The cleaning solution is buffered hydrofluoric acid, After the grinding surface and the through hole are cleaned with the buffered hydrofluoric acid in the cleaning step, 2. The method for manufacturing a substrate for a liquid discharge head according to claim 1, further comprising the step of rinsing the ground surface and the through hole with pure water.

12. 2. The method for manufacturing a substrate for a liquid discharge head according to claim 1, wherein in the hole making step, the holes are formed by etching.

13. A method for manufacturing a substrate for a liquid ejection head, as described in any one of claims 1 to 12, characterized in that it includes a substrate bonding process of bonding the first substrate, the base material having the through hole formed therein, to a second substrate having a flow path formed therein that connects the through hole and the ejection port, when the base material having the through hole formed therein is a first substrate.

14. 14. The method for manufacturing a substrate for a liquid discharge head according to claim 13, further comprising a discharge port forming step of forming the discharge port after the substrate bonding step.

15. a discharge port forming member in which a discharge port for discharging liquid is formed; a first substrate having a first surface and a second surface opposite to the first surface, the first substrate having a through hole formed therein and penetrating from the first surface to the second surface; a second substrate bonded to the first substrate and having a liquid flow path formed therein, the liquid flow path connecting the through hole and the ejection port; Equipped with A substrate for a liquid ejection head, comprising: a hydrophobic layer formed on the first surface of the first substrate so as to cover edges of the through holes.

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