Silicon substrate, liquid dispensing head, and method for manufacturing a silicon substrate

Abstract

To prevent a silicon substrate that is in use joined to another member from peeling off from the other member.SOLUTION: A silicon substrate 20 includes one of substrate surfaces that is configured to be a joining surface 20b on a side to be bonded to another member 30. The joining surface 20b includes recesses that are through holes 22 or grooves 23 each including a side wall or an inclined surface provided extending in a recess direction intersecting the joining surface 20b. The joining surface 20b is formed with a plurality of holes each having a diameter of 1 nm to 500 nm, inclusive, in at least a part of a non-forming region 208 in which no recesses.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] Conventionally, various silicon substrates have been used. Such silicon substrates are preferably used in various liquid ejection heads, such as an inkjet head that ejects ink as a liquid. As a liquid ejection head including such a silicon substrate, for example, Patent Document 1 discloses a liquid ejection head including a discharge element substrate that is a silicon substrate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Silicon substrates used in liquid ejection heads and the like are often bonded to other components. For example, in the liquid ejection head described in Patent Document 1, the ejection element substrate is bonded to a support. In this way, if a silicon substrate used while bonded to another component peels off from the other component to which it is bonded, it may not be able to perform as intended. Therefore, in silicon substrates used while bonded to other components, it is necessary to suppress peeling from the other component. In the liquid ejection head described in Patent Document 1, the ejection element substrate is provided with multiple pit-shaped portions, which are square pyramidal recesses for accommodating adhesive at the bonding surface with the support, thereby preventing the ejection element substrate from peeling off from the support through an anchoring effect. However, it is thought that these pit-shaped portions are formed by anisotropic etching together with the ink supply port provided on the ejection element substrate, and the individual pit-shaped portions are large, which may result in an insufficient anchoring effect. [Means for solving the problem]

[0005] Therefore, the silicon substrate according to the present invention, which solves the above problems, is a silicon substrate that is joined to another member via a bonding surface on the substrate surface, and has a recess on the bonding surface which is a through hole or groove having a side wall or inclined surface extending in a recessed direction intersecting the bonding surface, and is characterized in that a plurality of holes with a diameter of 1 nm or more and 500 nm or less are formed in at least a part of the non-formed area on the bonding surface where the recess is not formed.

[0006] Furthermore, the present invention provides a method for manufacturing a silicon substrate to solve the above problems, comprising the steps of: forming a catalyst film in an etching target region of the bonding surface; forming a metal film with metal on a non-etching target region of the bonding surface where the catalyst film is not formed and on the catalyst film; anodizing the metal film to form an anodic oxide film and forming a plurality of depressions on the anodic oxide film; removing at least a portion of the anodic oxide film and forming holes with a diameter of 1 nm to 500 nm at positions corresponding to the depressions on the catalyst film in the etching target region and on the bonding surface in the non-etching target region; and bringing the bonding surface into contact with an etching solution to etch the etching target region and form a recess which is a through hole or groove having a side wall or inclined surface extending in a recess direction intersecting the bonding surface. [Brief explanation of the drawing]

[0007] [Figure 1] A bottom view and an enlarged view of a portion of region X thereof of a liquid dispensing head having a sealing plate as a silicon substrate according to Embodiment 1 of the present invention. [Figure 2] Figure 1 shows a side cross-sectional view of the liquid dispensing head. [Figure 3] Figure 1 shows a perspective view of the liquid dispensing head. [Figure 4] Figure 1 shows the manufacturing process of the sealing plate for the liquid dispensing head. [Figure 5] A flowchart illustrating the manufacturing method of the sealing plate for the liquid discharge head shown in Figure 1. [Figure 6] A schematic diagram illustrating the anodic oxidation and reverse sputtering of the metal film deposition on the sealing plate of the liquid discharge head shown in Figure 1. [Figure 7] Figure 1 is a photograph showing the surface condition of the sealing plate of the liquid discharge head after reverse sputtering. [Figure 8] A flowchart illustrating the manufacturing method of the entire liquid dispensing head shown in Figure 1. [Figure 9] A side cross-sectional view of a silicon substrate according to Embodiment 2 of the present invention. [Modes for carrying out the invention]

[0008] First, the present invention will be described in general terms. A silicon substrate according to a first aspect of the present invention for solving the above problems is a silicon substrate in which one of the substrate surfaces is a bonding surface to be joined to another member, wherein the bonding surface has a recess which is a through hole or groove having a side wall or inclined surface extending in a recess direction intersecting the bonding surface, and a plurality of holes with a diameter of 1 nm to 500 nm are formed in at least a part of the non-formed area of ​​the bonding surface in which the recess is not formed.

[0009] According to this embodiment, multiple holes with a diameter of 1 nm to 500 nm are formed in at least a portion of the non-formed area of ​​the bonding surface. That is, multiple dense holes with a diameter of 1 nm to 500 nm and a high anchoring effect are formed on the bonding surface with other members. Therefore, when a silicon substrate is used in conjunction with other members, delamination from the other members can be suppressed.

[0010] A silicon substrate according to a second embodiment of the present invention is characterized in that, in the first embodiment, the silicon substrate is a single-crystal silicon substrate, the recess is formed by metal-assisted chemical etching, and the direction of the recess is at an angle of 90° plus or minus 2° or less with respect to the substrate surface.

[0011] According to this embodiment, the recess is formed by metal-assisted chemical etching, and the recess direction of the recess is configured with side walls that are perpendicular to the substrate surface at an angle of 90° ± 2° or less. Therefore, the expansion of the substrate surface can be suppressed, and the single-crystal silicon substrate can be miniaturized.

[0012] A third embodiment of the silicon substrate according to the present invention is characterized in that, in the first embodiment, the holes have a diameter of 10 nm or more and 100 nm or less.

[0013] According to this aspect, the hole has a diameter of 10 nm or more and 100 nm or less. By making the hole such a size, the anchor effect becomes particularly effective, and it is possible to particularly effectively suppress the separation of the silicon substrate from other members.

[0014] The liquid ejection head according to the fourth aspect of the present invention includes any one of the single crystal silicon substrates of the first to third aspects, and as the other member, at least a part of a flow path that is connected to the through hole and can supply liquid when joined to the silicon substrate, and a cavity substrate capable of applying pressure to a pressure chamber connected to the flow path.

[0015] According to this aspect, the silicon substrate and the cavity substrate can suppress the separation of the silicon substrate from the cavity substrate as another member.

[0016] The method for manufacturing a silicon substrate according to the fifth aspect of the present invention is a method for manufacturing a silicon substrate that is joined to another member through a joining surface on the substrate surface, and includes a step of forming a catalyst film in an etching target region of the joining surface, a step of forming a metal film on the non-etching target region where the catalyst film is not formed and on the catalyst film on the joining surface, a step of anodizing the metal film to form the metal film into an anodic oxide film and forming a plurality of depressions on the anodic oxide film, a step of removing at least a part of the anodic oxide film and forming holes with a diameter of 1 nm or more and 500 nm or less at positions corresponding to the depressions on the catalyst film in the etching target region and on the joining surface in the non-etching target region, and a step of contacting the joining surface with an etching solution to etch the etching target region and forming a recess having a side wall or an inclined surface extending in a recess direction intersecting the joining surface, the recess being a through hole or a groove.

[0017] According to this aspect, a metal film is formed on the bonding surface of the silicon substrate with other members, for example, made of aluminum or the like. The metal film is used as an anodic oxidation film, a plurality of depressions are formed on the anodic oxidation film, and by removing the anodic oxidation film, holes with a diameter of 1 nm or more and 500 nm or less are formed. That is, a plurality of dense holes with a diameter of 1 nm or more and 500 nm or less and a high anchor effect are formed on the bonding surface with other members. Therefore, in the silicon substrate joined and used with other members, peeling from the other members can be suppressed.

[0018] The method for manufacturing a silicon substrate according to the sixth aspect of the present invention is characterized in that, in the fifth aspect, the step of forming the metal film forms a metal film with aluminum, and the step of forming the holes is performed by reverse sputtering with argon.

[0019] According to this aspect, a metal film is formed with aluminum, and holes are formed by reverse sputtering with argon. Therefore, a plurality of dense holes with a diameter of 1 nm or more and 500 nm or less and a high anchor effect can be easily formed.

[0020] The method for manufacturing a silicon substrate according to the seventh aspect of the present invention is characterized in that, in the fifth or sixth aspect, the thickness of the anodic oxidation film in the step of forming the depressions is 50 nm or more and 200 nm or less, the diameter of the depressions in the step of forming the depressions is 20 nm or more and 100 nm or less, and the diameter of the holes is 10 nm or more and 200 nm or less.

[0021] According to this aspect, the thickness of the anodic oxidation film is 50 nm or more and 200 nm or less, and the diameter of the depressions is 20 nm or more and 100 nm or less. By configuring the thickness of the anodic oxidation film and the diameter of the depressions within such ranges, dense holes with a diameter of 10 nm or more and 100 nm or less, for which the anchor effect is particularly effective, can be preferably formed.

[0022] An eighth aspect of the present invention is a method for manufacturing a silicon substrate, characterized in that, in the fifth or sixth aspect, it comprises the step of forming an inclined through-hole having an inclined sidewall that is inclined more inclined than the sidewall with respect to the substrate surface by crystal anisotropic etching of a region of the substrate surface to be etched.

[0023] According to this embodiment, a gradient through-hole is formed by crystal anisotropic etching of the region of the substrate surface to be etched. By employing crystal anisotropic etching, a gradient through-hole can be easily formed.

[0024] A ninth aspect of the present invention is a method for manufacturing a silicon substrate, characterized in that, in the eighth aspect, an alkaline aqueous solution is used as an etching solution in the step of forming the inclined through-holes, and in the step of forming the recesses, the recesses are formed by metal-assisted chemical etching.

[0025] According to this embodiment, when forming inclined through holes, an alkaline aqueous solution is used as the etching solution to perform crystal anisotropic etching, and when forming recesses, metal-assisted chemical etching is employed. By employing such methods, inclined through holes can be easily formed, and recesses can be formed precisely.

[0026] A method for manufacturing a silicon substrate according to a tenth embodiment of the present invention is characterized in that, in the fifth or sixth embodiment, in the step of forming the catalyst film, the catalyst film is formed by an electroless plating method or a vapor deposition method.

[0027] According to this embodiment, the catalyst film is formed by electroless plating or vapor deposition. By manufacturing the single-crystal silicon substrate in this manner, it is possible to manufacture the single-crystal silicon substrate in a particularly simple and highly accurate manner.

[0028] A method for manufacturing a silicon substrate according to an eleventh aspect of the present invention, in the fifth or sixth aspect, is characterized in that, in the step of forming the through hole as the recess, the through hole is made to penetrate from the bonding surface to the surface opposite to the bonding surface, and an inclined surface toward the opposite surface is provided at the opening of the through hole on the opposite side, which widens toward the opposite surface.

[0029] According to this embodiment, the opening on the opposite side of the through hole, which serves as a recess, is provided with an inclined surface that widens towards the opposite side. This prevents burrs and other debris from remaining in the opening. Furthermore, by using such an opening, for example, when a liquid is flowed from the opening into the through hole, the liquid can flow in smoothly.

[0030] [Example 1] Next, the liquid discharge head 1 of Embodiment 1 of the present invention will be described in detail with reference to Figures 1 to 8. In the following figures, some components have been simplified, some components omitted, and the aspect ratio of some components has been changed in order to make the structure of the liquid discharge head 1 easier to understand.

[0031] The liquid ejection head 1 of this embodiment, shown in Figure 1, is a bottom view of an inkjet head capable of forming an image by ejecting liquid ink from nozzles N onto a medium by transporting the medium in the direction of movement A, or by moving the liquid ejection head 1 itself in the direction of movement A relative to a stationary medium. The liquid ejection head 1 of this embodiment is a so-called line head in which nozzles N are provided corresponding to the entire medium in the width direction B intersecting the direction of movement A.

[0032] When arranging multiple nozzles N on the nozzle forming surface 11, which is the bottom surface of the line head, arranging the nozzles N in the width direction B is the simplest way to arrange the nozzles N. However, arranging the nozzles N in this way results in a wide pitch between adjacent nozzles N in the width direction B. A wide pitch between adjacent nozzles N reduces resolution. Therefore, in this embodiment, the liquid discharge head 1 has multiple nozzle rows 12 in which the nozzles N are arranged in a straight line, and these rows are arranged at an angle to the direction of movement A.

[0033] As shown in the enlarged view of region X in Figure 1, in the liquid ejection head 1 of this embodiment, the spacing between nozzles N in the width direction B of each nozzle row 12 is the pitch P1. Furthermore, by configuring adjacent nozzle rows 12 to eject the same ink, and by arranging the nozzles N in adjacent nozzle rows 12 in the width direction B to be offset by half the pitch P1 for each nozzle row 12, the spacing between nozzles N in the width direction B of the liquid ejection head 1 is half the pitch P1, which is pitch P0. By arranging the nozzle rows 12 in this way, the liquid ejection head 1 of this embodiment achieves a high resolution of 1200 dpi (dots per inch) with a pitch P0.

[0034] In addition to arranging the nozzle row 12 at an angle to the direction of movement A, further resolution can be achieved by narrowing the spacing between adjacent nozzles N. The liquid ejection head 1 of this embodiment has the configuration shown in Figure 2, which narrows the spacing between adjacent nozzles N. Figure 2 is a cross-sectional view taken in a direction roughly aligned with the direction of movement A. In the liquid ejection head 1 of this embodiment, the same ink is supplied from an ink cartridge (not shown) to both nozzle row 12A and nozzle row 12B of the nozzle row 12, and the same ink can be ejected from the nozzles N of nozzle row 12A and nozzles N of nozzle row 12B. Furthermore, the liquid ejection head 1 of this embodiment is configured to allow the ink to circulate, and the ink flows in the flow direction F inside the liquid ejection head 1. In detail, in both nozzle row 12A and nozzle row 12B, the ink flowing from the ink cartridge in the flow direction F returns to the circulation channel 51D via the following channels, which form part of the channel 51: channel 51A corresponding to the second through-hole 22 of the sealing plate 20 (described later), channel 51B corresponding to the through-hole of the cavity substrate 30 (described later), and channel 51C composed of the cavity substrate 30 and the channel substrate 40 (described later). By making the circulation channel 51D common to the two nozzle rows 12 in this way, the distance between adjacent nozzle rows 12 is narrowed. The ink that returns to the circulation channel 51D then flows again in the flow direction F through channel 51 and is reused.

[0035] The detailed configuration of the liquid discharge head 1 of this embodiment will be described below with reference to Figures 2 and 3. Figure 3 shows a part of the nozzle row 12A side of the liquid discharge head 1 of this embodiment. The liquid discharge head 1 of this embodiment comprises a sealing plate 20, a cavity substrate 30, and a flow path substrate 40.

[0036] The sealing plate 20 is a single-crystal silicon substrate, at least a portion of which constitutes the liquid flow path 51. However, it is not limited to being a single-crystal silicon substrate. The sealing plate 20 also has a first surface 20a and a second surface 20b opposite to the first surface 20a as substrate surfaces, and is provided with a first through-hole 21 having an inclined side wall 21a that is inclined with respect to the first surface 20a and the second surface 20b. The sealing plate 20 also has a second through-hole 22 that constitutes the flow path 51 and has a side wall formed by a vertical side wall 22a that is closer to perpendicular to the first surface 20a and the second surface 20b than the inclined side wall 21a. The second through-hole 22 is part of the flow path 51 and acts as an increte reservoir. In this way, by making the second through-hole 22, whose side wall is formed by a nearly vertical side wall 22a, act as an increte reservoir, it is possible to suppress the size of the sealing plate 20 in the direction in which the substrate surface expands, and thus enable miniaturization of the liquid discharge head 1.

[0037] The cavity substrate 30 has a third surface 30a and a fourth surface 30b opposite to the third surface 30a, and is joined to the sealing plate 20 by the third surface 30a being joined to the second surface 20b. The cavity substrate 30 in this embodiment is a single-crystal silicon substrate, similar to the sealing plate 20, but is not limited to being a single-crystal silicon substrate. Furthermore, a piezoelectric element 32 and electrode films 33 and 34 that conduct to the piezoelectric element 32 are formed on the third surface 30a as an electrode portion 31, and at least a part of the fourth surface 30b constitutes a flow channel 51. A piezoelectric element housing chamber 23 is provided in the region of the sealing plate 20 corresponding to the formation position of the electrode portion 31. The electrode film 33 extends from the piezoelectric element housing chamber 23 to the first through hole 21. From another perspective, a TCP (tape carrier package) is mounted in COF (chip-on-flex) at the first through hole 21. In COF mounting, a special tool is used to heat-press the TCP. However, by making the first surface 20a wider and the second surface 20b narrower during COF mounting, it is possible to suppress the enlargement of the sealing plate 20 and cavity substrate 30 in the planar direction, thereby enabling miniaturization of the liquid discharge head 1.

[0038] The flow channel substrate 40 in this embodiment is a single-crystal silicon substrate, similar to the sealing plate 20 and the cavity substrate 30, but is not limited to being a single-crystal silicon substrate. The flow channel substrate 40 has a pressure chamber 41 positioned opposite the electrode portion 31 via the cavity substrate 30, and a nozzle N is provided in the pressure chamber 41 to discharge ink in the discharge direction D. The pressure chamber 41 forms part of the flow channel 51 and is connected to the circulation flow channel 51D, allowing ink that cannot be discharged from the nozzle N to flow into the circulation flow channel 51D. When the electrode portion 31 is energized, the piezoelectric element 32 deforms and the cavity substrate 30 vibrates, applying pressure to the pressure chamber 41, and the ink in the pressure chamber 41 is discharged from the nozzle N in the discharge direction D.

[0039] In this embodiment, the sealing plate 20 is formed by crystal anisotropic etching, and the second through hole 22 is formed by metal-assisted chemical etching (MACE). By forming the through hole with MACE, it is possible to create a through hole with a side wall that is closer to vertical than when the through hole is formed by crystal anisotropic etching. As a result, the side wall of the second through hole 22 can be constructed with a vertical side wall 22a that is substantially perpendicular to the substrate surfaces, the first surface 20a and the second surface 20b. By configuring the sealing plate 20 in this way, a dense single-crystal silicon substrate can be manufactured, and a small, high-resolution liquid discharge head 1 can be manufactured. Furthermore, by forming the first through hole 21 with crystal anisotropic etching and the second through hole 22 with metal-assisted chemical etching, etching can be performed in an all-wet state without using dry etching, which uses a large amount of greenhouse gases. As a result, by configuring the sealing plate 20 in this way, productivity can be improved, and the amount of electricity and greenhouse gases used in manufacturing can be reduced.

[0040] Here, it is preferable that the angle that the vertical side wall 22a of the second through-hole 22 formed by MACE makes with respect to the substrate surface, or in other words, the angle that the recessed second through-hole 22 makes with respect to the substrate surface in the direction of concavity, is 90° plus or minus 2° or less. This is because, by using a single-crystal silicon wafer with a Miller index (surface index) of (100) of the substrate surface as the sealing plate 20, and by devising the etching solution composition, it is possible to control the vertical etching by MACE, for example, within a range of about 400 μm for the thickness of the sealing plate 20, and ensure perpendicularity. Furthermore, by adopting such a configuration, the expansion of the substrate surface can be suppressed, and the sealing plate 20, which is a single-crystal silicon substrate, can be miniaturized.

[0041] Furthermore, the angle made by the inclined side wall 21a with respect to the substrate surface is preferably 45.0° or more and 54.7° or less. 54.7° is the angle made between the surface portion of the first surface 20a of the sealing plate 20, which has a Miller index (plane index) of (100), and the crystal plane, which has a Miller index (plane index) of (111), where etching progresses most slowly. In calculations, COS -1 (1 / 3 1 / 2 This is the value of ). Also, 45° is the angle that the next most stable Miller index (plane index) makes with the crystal plane of (110) COS -1 (1 / 2 1 / 2 This is the value of ). Furthermore, when the angle is set to 54.7°, the etching surface is more stable compared to when the angle is set to 45°, and the overall size of the sealing plate 20 can also be reduced.

[0042] To further explain the sealing plate 20 of this embodiment, as described above, the sealing plate 20 of this embodiment is a silicon substrate in which the second surface 20b, which is one of the substrate surfaces, is the bonding surface to the cavity substrate 30, which is another component. The second surface 20b has a second through-hole 22 and a piezoelectric element housing chamber 23, which is a groove, as recesses having side walls or inclined surfaces that extend in a recessed direction intersecting the second surface 20b. In this way, a silicon substrate that has at least one of a through-hole and a groove as recesses on the bonding surface and is bonded to another component via the bonding surface may have a reduced contact area with the other component due to the presence of the recesses, and may be prone to peeling from the bonded other component. Therefore, in order to suppress peeling from the bonded cavity substrate 30, the sealing plate 20 of this embodiment has multiple holes 207 with a diameter of 1 nm to 500 nm formed in a non-formed region 208, as shown in Figure 6, on the second surface 20b, which is the bonding surface, where the second through-hole 22 and the piezoelectric element housing chamber 23 are not formed. In this way, by forming multiple holes 207 with a diameter of 1 nm to 500 nm in at least a part of the non-formed region 208, multiple dense holes 207 with a high anchoring effect are formed, thereby suppressing the delamination of the silicon substrate, which is bonded to other components, from those components.

[0043] Furthermore, it is particularly preferable that the hole portion 207 has a diameter of 10 nm or more and 100 nm or less. This is because making the hole portion 207 of this size makes the anchoring effect particularly effective, and it is possible to particularly effectively suppress the delamination of the silicon substrate from other components.

[0044] Next, the manufacturing method of the sealing plate 20 of this embodiment, including the specific method for forming the holes 207, will be described with reference to Figures 4 to 7. As shown in Figure 5, in the manufacturing method of the sealing plate 20 of this embodiment, the catalyst film formation step S10 is performed first. In the catalyst film formation step S10, an oxide film 202 represented by SiO2 is first formed on the single crystal silicon substrate 201 shown in the top figure of Figure 4, as shown in the second figure from the top of Figure 4. Then, the film is patterned with a resist by photolithography to form an Au film 204, which is a gold film that will serve as the catalyst film for MACE, as shown in the third figure from the top of Figure 4. Here, in the third figure from the top of Figure 4, the Au film 204 has an annular shape when viewed from below, and in this embodiment, it is formed by depositing Au.

[0045] Next, the metal film formation process of step S20, shown in Figure 5, is performed. In the metal film formation process of step S20, as shown in the fourth figure from the top in Figure 4, a sputtered aluminum film 205 is formed on the second surface 20b, which is the bonding surface, under an argon environment. Here, the top figure in Figure 6 shows the state in which the sputtered film 205 has been formed on the single crystal silicon substrate 201 in the non-formation region 208 on the second surface 20b. Note that in Figure 6, the oxide film 202 is omitted to make the state of the sputtered film 205 easier to see.

[0046] Then, the anodizing process of step S30, shown in Figure 5, is performed. By performing the anodizing process of step S30, multiple fine depressions 206 are formed in the sputtered film 205, as shown by progressing from the top diagram in Figure 6 to the middle diagram in Figure 6. The depressions 206 are formed in both the sputtered film 205, on the Au film 204 in the non-formed region 208 on the second surface 20b side, and on the surface of the single-crystal silicon substrate 201 where the Au film 204 is not formed in the non-formed region 208 on the second surface 20b side.

[0047] Then, the hole formation process of step S40, shown in Figure 5, is performed. In this embodiment, the hole formation process of step S40 is performed by reverse sputtering with argon. As shown in the lower part of Figure 6, by performing reverse sputtering with argon, the argon strikes the surface of the sputtered film 205 and the inside of the depression 206, and the sputtered film 205 becomes thinner as the struck areas are abraded, and a hole 207 is formed at the bottom of the depression 206.

[0048] Then, the etching process to form recesses, step S50, shown in Figure 5, is performed. Specifically, first, the sputtered film 205 and oxide film 202 are removed, as shown in the fifth figure from the top in Figure 4. Figure 7 is a photograph showing an example of the hole 207, and is a photograph showing the area around the boundary between the surface of the Au film 204 and the surface of the single-crystal silicon substrate 201 where the Au film 204 has not been formed, after the sputtered film 205 and oxide film 202 have been removed.

[0049] Performing MACE from the state shown in the fifth figure from the top of Figure 4 results in the state shown in the sixth figure from the top of Figure 4. The sixth figure from the top of Figure 4 shows the state in which cylindrical holes have been formed in the single-crystal silicon substrate 201 by MACE. As shown in the photograph in Figure 7, multiple holes 207 are also formed on the surface of the Au film 204, which allows the etching solution to circulate more easily around the Au film 204 during MACE, thereby increasing the etching rate of the single-crystal silicon substrate 201. After etching the Au film 204, the state shown in the seventh figure from the top of Figure 4 is achieved. Furthermore, the formation of multiple holes 207 on the surface of the Au film 204 also increases the etching rate when etching the Au film 204.

[0050] Subsequently, when an oxide film 202 represented by SiO2 is formed over the entire single-crystal silicon substrate 201, the state shown in the eighth figure from the top of Figure 4 is obtained. Then, the surface is patterned with a resist using photolithography, and the resist is removed by etching, resulting in the state shown in the ninth figure from the top of Figure 4. Here, the first surface 20a side corresponding to the second through-hole 22 is also assumed to be free of the oxide film 202. Subsequently, when crystal anisotropic etching of silicon (Si) forming the single-crystal silicon substrate 201 is performed using an alkaline aqueous solution such as potassium hydroxide (KOH), the state shown in the tenth figure from the top of Figure 4 is obtained. In this embodiment, in addition to the region corresponding to the first through-hole 21 and the region corresponding to the piezoelectric element housing chamber 23, recesses are also formed on the first surface 20a side corresponding to the second through-hole 22. Finally, when the oxide film 202 is removed, the state shown in the bottom figure of Figure 4 is obtained. In the above, etching by MACE is stopped by the oxide film 202, and the removal of the oxide film 202 opens the first through-hole 21 and the second through-hole 22, while crystal anisotropic etching is stopped at the crystal plane of the single crystal silicon substrate 201 with Miller index (plane index) of (111).

[0051] As described above, the manufacturing method of the sealing plate 20 in this embodiment as a method for manufacturing a silicon substrate is a method for manufacturing a silicon substrate that is bonded to a cavity substrate 30 via a second surface 20b. Step S10 is a catalyst film formation step, which includes a step of forming an Au film 204 in the etching target area of ​​the second surface 20b. Step S20 is a metal film formation step, which includes a step of forming a sputtered film 205 of aluminum, which is a metal, on the entire second surface 20b, that is, on the non-etching target area of ​​the second surface 20b where the Au film 204 has not been formed, and on the Au film 204. Step S30 is an anodizing step, which includes anodizing the sputtered film 205 to make it an anodic oxide film, and forming a plurality of depressions 206 on the anodic oxide film. Furthermore, as a hole formation step in step S40, at least a portion of the anodic oxide film is removed, and holes 207 with a diameter of 1 nm to 500 nm are formed at positions corresponding to depressions 206 on the Au film 204 in the etching target area and on the second surface 20b in the non-etching target area. Furthermore, as a recess formation step in step S50, the second surface 20b is brought into contact with an etching solution to etch the etching target area, thereby forming a second through-hole 22 and a piezoelectric element housing chamber 23, which are recesses having side walls or inclined surfaces extending in a recess direction intersecting the second surface 20b. By performing such a silicon substrate manufacturing method, multiple dense holes 207 with a diameter of 1 nm to 500 nm and a high anchoring effect can be formed on the bonding surface with other members such as the cavity substrate 30. Therefore, when a silicon substrate is used bonded to other members, delamination from those other members can be suppressed.

[0052] In this embodiment, the manufacturing method for the sealing plate 20 involves forming a metal film with aluminum in step S20, and performing the hole formation step in step S40 by reverse sputtering with argon. By employing this method, multiple dense holes 207 with a diameter of 1 nm to 500 nm and a high anchoring effect can be easily formed.

[0053] Here, it is preferable to set the thickness of the anodic oxide film to 50 nm or more and 200 nm or less, and the diameter of the depression 206 to 20 nm or more and 100 nm or less in the anodic oxidation process of step S30, so that the diameter of the hole 207 in the hole formation process of step S40 is 10 nm or more and 200 nm or less. This is because by setting the thickness of the anodic oxide film and the diameter of the depression 206 within this range, it is possible to suitably form dense holes 207 with a diameter of 10 nm or more and 100 nm or less, in which the anchoring effect is particularly effective.

[0054] Furthermore, if the anodized film is thin, there is a risk that the depressions in the anodized film may disappear due to the barrier film when reverse sputtering with argon. On the other hand, if the anodized film is thick, there is a risk that the depressions in the anodized film will not be formed perpendicular to the substrate surface, preventing the argon from reaching the bottom of the depressions and making reverse sputtering impossible. The thickness of the anodized film can be controlled by adjusting various conditions, such as setting the phosphoric acid concentration during anodizing to 0.1 to 0.5 mol / l, the electrolysis voltage to 20 to 40 V, and the processing time to 5 to 40 minutes. Also, the diameter of the hole 207 will be smaller than the diameter of the anodized depression 206. This is because the angle of incidence of argon during sputtering is not perfectly perpendicular, and consequently, the depression 206 in the anodized film is not formed perfectly perpendicular to the substrate surface.

[0055] Furthermore, as described above, in the manufacturing method of the sealing plate 20 of this embodiment, in the recess formation step S50, a first through hole 21 is formed in addition to the second through hole 22. In other words, the manufacturing method of the sealing plate 20 of this embodiment includes a step of forming a first through hole 21, which is an inclined through hole having an inclined side wall 21a that is inclined more inclined than the vertical side wall 22a, which is the side wall of the second through hole 22, with respect to the substrate surface, by crystal anisotropic etching of the region of the substrate surface to be etched. By employing crystal anisotropic etching, as in the manufacturing method of the sealing plate 20 of this embodiment, inclined through holes can be easily formed.

[0056] In the recess formation step S50, when forming the first through-hole 21, which is an inclined through-hole, an alkaline aqueous solution is used as the etching solution for crystal anisotropic etching, and when forming the second through-hole 22, which is a recess, MACE is employed. By employing this method, the first through-hole 21 can be easily formed, and the second through-hole 22 can be precisely formed. As the alkaline aqueous solution used as the etching solution, in addition to the potassium hydroxide aqueous solution used in this embodiment, an aqueous solution of tetramethylammonium hydroxide (THAM) can be preferably used, but there are no particular limitations. Since potassium hydroxide aqueous solution is inexpensive, it can be used, for example, for silicon substrate processing without semiconductors. On the other hand, since THAM aqueous solution does not contain mobile ions such as Na and K, it can be used, for example, for crystal anisotropic etching of silicon substrate processing with semiconductors. For etching by MACE, an aqueous solution of hydrogen fluoride can be used as the etching solution.

[0057] In step S10, the catalyst film formation step is not particularly limited in terms of method, but it is preferable that the catalyst film be formed by electroless plating or vapor deposition. This is because forming the catalyst film by electroless plating or vapor deposition and then manufacturing the sealing plate 20 allows for the simple and highly accurate production of the sealing plate 20.

[0058] In step S50, the process of forming the second through-hole 22 as a recess in the recess formation process, the second through-hole 22 is made to penetrate from the second surface 20b to the first surface 20a, which is the opposite surface to the second surface 20b. As shown in the bottom diagram of Figure 4, the opening 24 on the first surface 20a side of the second through-hole 22 is provided with an inclined surface toward the first surface 20a that widens as it approaches the first surface 20a. This prevents burrs and other debris from remaining in the opening 24. Furthermore, by making the opening 24 in this way, ink can be suitably introduced into the second through-hole 22 from the opening 24.

[0059] Next, a method for manufacturing the entire liquid discharge head 1 using the sealing plate 20 formed as described above will be explained with reference to the flowchart in Figure 8. First, in step S110, the sealing plate 20 is formed. The formation of the sealing plate 20 is as described above. Next, in step S120, the cavity substrate 30 is formed using a conventional manufacturing method, and in step S130, the sealing plate 20 and the cavity substrate 30 are joined together. Note that the order of steps S110 and S120 may be reversed or performed simultaneously.

[0060] Subsequently, in step S140, an ink protective film such as titanium oxide (TiOx) or hafnium oxide (HfOx) is formed by deposition using CVD (Chemical Vapor Deposition) or the like. In step S150, the flow channel substrate 40 is formed using conventional manufacturing methods, although step S150 may be performed before step S140. Then, in step S160, the flow channel substrate 40 is bonded to the substrate to which the sealing plate 20 and the cavity substrate 30 are joined. Then, in step S170, this is cut into chips using a laser scribe or the like, and in step S180, the TCP constituting the conductive part is mounted using COF. Finally, in step S190, the case components are attached to complete the manufacturing of the liquid ejection head 1. With this method, the chip of the liquid ejection head 1 can be assembled in wafer form, which stabilizes quality and facilitates mass production.

[0061] As described above, the liquid discharge head 1 of this embodiment includes the sealing plate 20 and a cavity substrate 30 that, when joined with the sealing plate 20, forms at least a part of a flow path 51 that connects to the second through hole 22 and can supply ink, and can apply pressure to a pressure chamber 41 connected to the flow path 51. With this configuration, the sealing plate 20 and the cavity substrate 30 can suppress the sealing plate 20 from peeling off from the cavity substrate 30.

[0062] [Example 2] The silicon substrate 200 of Example 2 will be described below with reference to Figure 9. The silicon substrate 200 of this example can also be used as a component of a liquid discharge head, similar to the sealing plate 20 of Example 1. In Figure 9, components common to the sealing plate 20 of Example 1 are indicated by the same reference numerals. The silicon substrate 200 of this example also has a second through-hole 22 penetrating the substrate surface and a groove corresponding to the piezoelectric element housing chamber 23, similar to the sealing plate 20 of Example 1. However, the silicon substrate 200 of this example is bonded to other components via a first surface 20a, which serves as a bonding surface on the substrate surface. For this reason, the hole 207 is provided on the first surface 20a. The configuration of the hole 207 of the silicon substrate 200 of this example is the same as the configuration of the hole 207 of the sealing plate 20 of Example 1. The second through-hole 22 and the groove corresponding to the piezoelectric element housing chamber 23 can be formed by crystal anisotropic etching using an aqueous potassium hydroxide solution as the etching solution, but they can also be formed by RIE (reactive ion etching).

[0063] The present invention is not limited to the embodiments described above, and can be realized in various configurations without departing from its spirit. For example, a single-crystal silicon substrate such as the sealing plate 20 described above can be used in a micropump or other device other than a liquid discharge head. It is also possible to provide the hole 207 in the cavity substrate 30 or the flow channel substrate 40 instead of the sealing plate 20. Furthermore, the technical features in the embodiments corresponding to the technical features in each embodiment described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-described problems or to achieve some or all of the above-described effects. In addition, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of Symbols]

[0064] 1...Liquid discharge head, 11...Nozzle forming surface, 12...Nozzle row, 12A...Nozzle row, 12B...Nozzle row, 20...Sealing plate (silicon substrate), 20a...First surface (substrate surface, opposite side), 20b...Second surface (substrate surface, bonding surface), 21...First through hole, 21a...Inclined side wall, 22...Second through hole (recess), 22a...Vertical side wall, 23...Piezoelectric element housing chamber (recess), 24...Opening, 24a...Inclined surface, 30...Cavity substrate (other components), 30a...Third surface, 3 0b...Fourth surface, 31...Electrode part, 32...Piezoelectric element, 33...Electrode film, 34...Electrode film, 40...Flow channel substrate, 41...Pressure chamber, 51...Flow channel, 51A...Flow channel, 51B...Flow channel, 51C...Flow channel, 51D...Circulation channel, 200...Silicon substrate, 201...Single crystal silicon substrate, 202...Oxide film, 204...Au film (catalyst film), 205...Sputter deposition (metal deposition), 206...Depression, 207...Hole, 208...Non-formed area, N...Nozzle, P0...Pitch, P1...Pitch

Claims

1. A silicon substrate in which one of the substrate surfaces is the bonding surface to be joined to another component, A recess having a side wall or inclined surface extending in a recess direction intersecting the aforementioned joint surface The joint surface has, In at least a portion of the non-formed region of the joint surface where the recess is not formed, diameter A silicon substrate characterized by having multiple holes formed thereon, ranging in size from 1 nm to 500 nm.

2. In the silicon substrate according to claim 1, The silicon substrate is a single-crystal silicon substrate, The recess is formed by metal-assisted chemical etching. The recess direction shall form an angle of 90° plus or minus 2° or less with respect to the substrate surface. A silicon substrate characterized by the following.

3. In the silicon substrate according to claim 1, The silicon substrate is characterized in that the hole portion has a diameter of 10 nm or more and 100 nm or less.

4. A silicon substrate according to any one of claims 1 to 3, having a through hole as the recess, 、 As for the other components mentioned above, when bonded to the silicon substrate, they connect to the through-hole and supply liquid. It constitutes at least a portion of the supplyable flow path and provides pressure to the pressure chamber connected to the flow path. A cavity substrate to which force can be applied, A liquid dispensing head characterized by having the following features.

5. A method for manufacturing a silicon substrate that is joined to other components via a bonding surface on the substrate surface. 、 A step of forming a catalyst film in the etching target region of the bonding surface, On the non-etching target area of ​​the bonding surface that is not connected to the catalyst film and the contact A process of forming a metal film on a medium film, The metal film is anodized to form an anodized film, and a plurality of The process of forming a depression, At least a portion of the anodic oxide film is removed, and the catalyst film of the etching target region and And at the position corresponding to the recess on the bonding surface of the non-etching target area, a diameter 1 A step of forming a hole portion between nm and 500 nm, The bonding surface is brought into contact with the etching solution to etch the area to be etched, A recess is formed having a side wall or inclined surface that extends in a recess direction intersecting the aforementioned joint surface. The process and A method for manufacturing a silicon substrate, characterized by having the following features.

6. In the method for manufacturing a silicon substrate according to claim 5, The process of forming the metal film involves forming a metal film with aluminum, The process of forming the aforementioned hole is characterized by being carried out by reverse sputtering with argon. A method for manufacturing silicon substrates.

7. In the method for manufacturing a silicon substrate according to claim 5 or 6, The thickness of the anodic oxide film in the step of forming the depression is 50 nm or more and 200 nm or less. can be, The diameter of the depression in the step of forming the depression is 20 nm or more and 100 nm or less. The silicon substrate is characterized in that the diameter of the hole is between 10 nm and 200 nm. A method for manufacturing this product.

8. In the method for manufacturing a silicon substrate according to any one of claims 5 or 6, By performing crystal anisotropic etching on the substrate surface, A process for forming an inclined through-hole having an inclined side wall that is inclined more than the side wall with respect to the substrate surface. A method for manufacturing a silicon substrate, characterized by having the following features.

9. In the method for manufacturing a silicon substrate according to claim 8, In the process of forming the inclined through-hole, an alkaline aqueous solution is used as the etching solution. In the process of forming the recess, the recess is formed by metal-assisted chemical etching. A method for manufacturing a silicon substrate characterized by the following.

10. In the method for manufacturing a silicon substrate according to any one of claims 5 or 6, In the step of forming the catalyst film, the catalyst film is formed by electroless plating or vapor deposition. A method for manufacturing a silicon substrate, characterized by the following:

11. In the method for manufacturing a silicon substrate according to any one of claims 5 or 6, In the step of forming the recess, the recess is formed on the opposite side from the joining surface. By penetrating through to the surface, a through hole is formed. The opening on the opposite side of the through hole, the opposite side which widens towards the opposite side A method for manufacturing a silicon substrate, characterized by having a step of providing an inclined surface.

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