Single crystal silicon substrate, liquid discharge head, and method for manufacturing single crystal silicon substrate

Abstract

To improve a liquid flow in a through hole formed in a silicon substrate.SOLUTION: A single crystal silicon substrate 40 at least a part of which constitutes a liquid channel 51 includes a through hole N which constitutes a part of the channel 51 and penetrates through the single crystal silicon substrate 40 in a direction crossing the substrate surface of the single crystal silicon substrate 40, wherein the through hole N is formed by metal assist chemical etching and has a streak-like part L where at least one of a recess and a projection in a liquid flowing direction extends.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a single crystal silicon substrate, a liquid ejection head, and a method for manufacturing a single crystal 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. Among such silicon substrates, there are those in which through-holes for flowing a liquid are formed. For example, Non-Patent Document 1 discloses a method of forming through-holes for flowing a liquid in a silicon substrate using Si-Deep-RIE.

Prior Art Documents

Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since Si-Deep-RIE of Non-Patent Document 1 is an etching method in which formation of a sidewall protective film and etching are repeated every about 1 μm, irregularities called scallops are formed on the sidewalls of the formed through-holes in a direction intersecting the depth direction of the through-holes. Since the irregularities are formed along a direction intersecting the depth direction, which is the direction in which the liquid flows, when the liquid flows through the through-holes, turbulent flow may occur and disrupt the flow of the liquid, and bubbles, foreign substances, etc. may stay in the irregularities and be difficult to remove, which may affect the flow of the liquid.

Means for Solving the Problems

[0005] Therefore, the single-crystal silicon substrate according to the present invention for solving the above problems is a single-crystal silicon substrate in which at least a part constitutes a liquid channel, and is provided with through holes that constitute a part of the channel and penetrate the single-crystal silicon substrate in a direction intersecting the substrate surface of the single-crystal silicon substrate, wherein the through holes are formed by metal-assisted chemical etching and have streak-like portions in which at least one of a recess and a protrusion extends along the direction in which the liquid flows.

[0006] Furthermore, the present invention provides a method for manufacturing a single-crystal silicon substrate to solve the above problems, comprising the steps of: forming a catalyst film in an etching target region of the catalyst film formation surface on the substrate surface of the single-crystal silicon substrate; and bringing the single-crystal silicon substrate with the catalyst film formed on it into contact with an etching solution to etch the etching target region, thereby forming through holes that penetrate the single-crystal silicon substrate in a direction intersecting the substrate surface, wherein the step of forming the through holes is characterized in that at least one of a recess and a protrusion extending along the penetrating direction of the through holes is formed. [Brief explanation of the drawing]

[0007] [Figure 1] A bottom view of a liquid discharge head according to one embodiment of the present invention and an enlarged view of a portion of region X thereof. [Figure 2] Figure 1 shows a side cross-sectional view of the liquid dispensing head. [Figure 3] Figure 1 is a perspective view of the flow path substrate of the liquid discharge head, taken from the bottom side. [Figure 4] This diagram shows the manufacturing process of the flow channel substrate for the liquid discharge head in Figure 1. [Figure 5] A flowchart illustrating the manufacturing method of the flow path substrate and sealing plate of the liquid discharge head shown in Figure 1. [Figure 6] A photograph showing the irregularities formed on the edges of the catalyst film. [Figure 7] Figure 1 is a photograph of the inside of the nozzle of the flow path substrate of the liquid discharge head. [Figure 8] Figure 1 shows a perspective view of the sealing plate of the liquid discharge head. [Figure 9]Figure 1 shows the manufacturing process of the sealing plate for the liquid dispensing head. [Figure 10] A flowchart illustrating the manufacturing method of the entire liquid dispensing head shown in Figure 1. [Modes for carrying out the invention]

[0008] First, the present invention will be described in general terms. A single-crystal silicon substrate according to a first aspect of the present invention for solving the above problems is a single-crystal silicon substrate in which at least a portion constitutes a liquid channel, and is provided with through holes that constitute a portion of the channel and penetrate the single-crystal silicon substrate in a direction intersecting the substrate surface of the single-crystal silicon substrate, wherein the through holes are formed by metal-assisted chemical etching and have streak-like portions in which at least one of a recess and a protrusion extends along the direction in which the liquid flows.

[0009] According to this embodiment, the through-hole is formed by metal-assisted chemical etching and has a streak-like portion in which at least one of a recess and a protrusion extends along the direction of liquid flow. Therefore, the streak-like portion along the direction of liquid flow can be formed with a narrow formation pitch by metal-assisted chemical etching, and the liquid flow in the through-hole can be improved by the streak-like portion along the direction of liquid flow with a narrow formation pitch.

[0010] A single-crystal silicon substrate according to a second embodiment of the present invention is characterized in that, in the first embodiment, a plurality of at least one of the recesses and protrusions are arranged in a row in the through hole when viewed from the direction of penetration of the through hole, and the formation pitch between adjacent recesses or between adjacent protrusions is 10 nm or more and 300 nm or less.

[0011] According to this embodiment, the formation pitch of the streaks is 10 nm to 300 nm. If the formation pitch of the streaks is too large, turbulence may occur in the recesses or protrusions, or bubbles or foreign matter may accumulate. If the formation pitch of the streaks is too small, the formation effect of the streaks may be insufficient. However, by setting the formation pitch of the streaks to 10 nm to 300 nm, the liquid flow in the through-hole can be suitably improved.

[0012] A liquid discharge head according to a third aspect of the present invention comprises a first or second single-crystal silicon substrate, a cavity substrate having a conductive portion forming surface on which a piezoelectric element and a conductive portion that conducts to the piezoelectric element are formed, and a flow path forming surface on the opposite side of the conductive portion forming surface, wherein the conductive portion forming surface or the flow path forming surface is joined to the substrate surface so that the flow path on the flow path forming surface communicates with the through hole.

[0013] According to this embodiment, by joining the single-crystal silicon substrate and the cavity substrate to the substrate surface, the flow path of the flow path forming surface communicates with the through hole, thereby enabling the manufacture of a liquid discharge head with improved liquid flow in the through hole.

[0014] A fourth aspect of the present invention provides a method for manufacturing a single-crystal silicon substrate, comprising the steps of: forming a catalyst film in an etching target region of the catalyst film formation surface on the substrate surface of the single-crystal silicon substrate; and bringing the single-crystal silicon substrate with the catalyst film formed thereon into contact with an etching solution to etch the etching target region, thereby forming through holes that penetrate the single-crystal silicon substrate in a direction intersecting the substrate surface, wherein the step of forming the through holes is characterized in that at least one of a recess and a protrusion extending along the penetrating direction of the through holes is formed.

[0015] According to this aspect, a catalyst film is formed on an etching target region of a catalyst film formation surface, and the etching target region of a single crystal silicon substrate in a state where the catalyst film is formed is etched to form a through hole, and a streak-shaped portion along the through direction is formed as the through hole is formed. For this reason, a dense streak-shaped portion along the through direction with a narrow formation pitch can be formed in the through hole. Therefore, the flow of liquid in the through hole can be improved.

[0016] In the manufacturing method of the single crystal silicon substrate according to the fifth aspect of the present invention, in the fourth aspect, in the step of forming the through hole, the through hole is formed by metal-assisted chemical etching.

[0017] According to this aspect, the through hole is formed by metal-assisted chemical etching. For this reason, a dense streak-shaped portion along the through direction with a narrow formation pitch can be suitably formed in the through hole. Therefore, the flow of liquid in the through hole can be improved.

[0018] In the manufacturing method of the single crystal silicon substrate according to the sixth aspect of the present invention, in the fifth aspect, in the step of forming the catalyst film, the catalyst film is formed by electroless plating or vapor deposition.

[0019] According to this aspect, the catalyst film is formed by electroless plating or vapor deposition. By manufacturing the single crystal silicon substrate in this way, the single crystal silicon substrate can be manufactured particularly easily and with high precision.

[0020] In the manufacturing method of the single crystal silicon substrate according to the seventh aspect of the present invention, in any one of the fourth to sixth aspects, it is a step executed before the step of forming the catalyst film, which is a step of forming a pattern with a resist, and a step executed after the step of forming the catalyst film, which is a step of removing the resist.

[0021] According to this embodiment, a pattern is formed with a resist before forming the catalyst film, and the resist is removed after the catalyst film is formed. By employing this method, a single-crystal silicon substrate can be easily manufactured.

[0022] An eighth embodiment of the present invention is a method for manufacturing a single-crystal silicon substrate, characterized in that, in any one of the fourth to sixth embodiments, the through-hole has side walls formed by vertical side walls with an angle of 90° plus or minus 2° or less with respect to the substrate surface.

[0023] According to this embodiment, the through-hole is constructed 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.

[0024] A method for manufacturing a single-crystal silicon substrate according to a ninth aspect of the present invention is characterized in that, in any one of the fourth to sixth aspects, in the step of forming the through-hole, the catalyst film is removed before the single-crystal silicon substrate penetrates, and a portion of the substrate surface on the side opposite to the catalyst film formation surface is removed up to the position where the single-crystal silicon substrate penetrates, thereby forming the through-hole.

[0025] According to this embodiment, the catalyst film is removed before the single-crystal silicon substrate penetrates, and a portion of the substrate surface on the side opposite to the catalyst film formation surface is removed up to the point where the single-crystal silicon substrate penetrates. By employing such a method, a single-crystal silicon substrate can be easily manufactured.

[0026] A method for manufacturing a single-crystal silicon substrate according to a tenth aspect of the present invention is characterized in that, in any one of the fourth to sixth aspects, the method comprises the step of forming an inclined through-hole having an inclined sidewall that is inclined more inclined than the sidewall of the through-hole with respect to the substrate surface by crystal anisotropic etching of a region to be etched on the substrate surface.

[0027] According to this embodiment, by performing crystal anisotropic etching on the substrate surface, an inclined through-hole is formed having an inclined sidewall that is more inclined than the sidewall of the through-hole with respect to the substrate surface. For example, when arranging a component in the through-hole, the component can be suitably arranged in the inclined through-hole by forming an inclined through-hole that widens towards the end.

[0028] A method for manufacturing a single-crystal silicon substrate according to the eleventh aspect of the present invention is characterized in that, in the tenth aspect, an alkaline aqueous solution is used as an etching solution in the step of forming the inclined through-holes.

[0029] According to this embodiment, an alkaline aqueous solution is used as the etching solution when forming inclined through holes. Therefore, inclined through holes can be easily formed.

[0030] Next, a liquid discharge head 1 according to one embodiment of the present invention will be described in detail with reference to Figures 1 to 10. 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 rows 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. Inside the liquid ejection head 1, the ink flows in the flow direction F. Specifically, in both nozzle row 12A and nozzle row 12B, the ink that has flowed from the ink cartridge in the flow direction F is supplied to the pressure chamber 41 equipped with nozzles N via a flow path 51A corresponding to the second through-hole 22 of the sealing plate 20 (described later), which forms part of the flow path 51, and a flow path 51B corresponding to the through-hole of the cavity substrate 30 (described later). Then, when pressure is applied to the pressure chamber 41, ink is ejected from the nozzle N in the ejection direction D.

[0035] The detailed configuration of the liquid discharge head 1 of this embodiment will be described below with reference to Figure 2. As shown in Figure 2, 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 a liquid flow path 51. 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 which constitutes the flow path 51 and has a side wall formed by a vertical side wall 22a that is closer to perpendicular than the inclined side wall 21a with respect to the first surface 20a and the second surface 20b. 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 expansion 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 control IC 28 is provided on the sealing plate 20, and the electrode film 33 is connected to the control IC (integrated circuit) 28 via an FPC (flexible flat cable) 29. 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, the TCP (tape carrier package) is mounted in the first through-hole 21 using COF (chip-on-flex) mounting. In COF mounting, a special tool is used to heat-press the TCP, but 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, making it possible to miniaturize the liquid discharge head 1.

[0038] The flow channel substrate 40 has a fifth surface 40a and a sixth surface 40b opposite to the fifth surface 40a as substrate surfaces, and is joined to the cavity substrate 30 by the fifth surface 40a being joined to the fourth surface 30b. The flow channel substrate 40 in this embodiment is also a single-crystal silicon substrate, similar to the sealing plate 20 and the cavity substrate 30. Furthermore, the flow channel substrate 40 has a pressure chamber 41 located opposite the electrode section 31 via the cavity substrate 30, and as described above, the pressure chamber 41 is provided with a nozzle N that discharges ink in the discharge direction D. When the electrode section 31 is energized, the piezoelectric element 32 deforms, causing the cavity substrate 30 to vibrate, which applies 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] The flow channel substrate 40 will be described in more detail below with reference to Figure 3. As described above, the flow channel substrate 40 of this embodiment is a single-crystal silicon substrate on which nozzles N constituting the ink flow channel 51 are provided in at least a portion of it. The nozzles N constitute a part of the flow channel 51 and, as shown in Figure 3, are through holes that penetrate the flow channel substrate 40 in a direction intersecting the fifth surface 40a and the sixth surface 40b, which are substrate surfaces. Here, the nozzles N as through holes are formed by metal-assisted chemical etching (MACE) and have streaky portions L with recesses and protrusions extending along the ink flow direction F, as shown in Figure 3. In this way, the flow channel substrate 40 of this embodiment forms streaky portions L along the ink flow direction F with a narrow formation pitch by MACE, and the liquid flow in the nozzles N can be improved by the streaky portions L with a narrow formation pitch along the ink flow direction F. In this embodiment, the streaky portion L is composed of both recesses and protrusions, corresponding to the unevenness R shown in Figure 6, which will be described later. However, the streaky portion L only needs to be composed of at least one of the recesses and protrusions that are aligned with the ink flow direction F.

[0040] Here, each nozzle N is provided with a streaky section L, which consists of multiple recesses and protrusions arranged in a row when viewed from the discharge direction D corresponding to the penetration direction of the nozzle N. Preferably, the formation pitch between adjacent recesses or adjacent protrusions is 10 nm to 300 nm. If the formation pitch of the streaky section L is too large, turbulence may occur in the recesses or protrusions, or bubbles or foreign matter may accumulate. If the formation pitch of the streaky section L is too small, the formation effect of the streaky section L may be insufficient. By setting the formation pitch of the streaky section L to 10 nm to 300 nm, the ink flow in the nozzle N can be suitably improved. In other words, setting the formation pitch of the streaky section L to 10 nm to 300 nm means that the irregularities R in Figure 6 are irregularities of 10 nm to 300 nm, which corresponds to the particle size of the Au film 204.

[0041] Next, the manufacturing method of the flow channel substrate 40 of this embodiment 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 etching preparation step S10 is performed first. In the etching preparation step S10, the single crystal silicon substrate 201 shown in the top figure of Figure 4 is first patterned with a resist 203 by photolithography, as shown in the second figure from the top of Figure 4. Then, an Au film 204, which is a gold film that will serve as a catalyst film for MACE, is formed as shown in the third figure from the top of Figure 4, and lift-off formation is performed as shown in the fourth figure from the top of Figure 4. In this embodiment, the Au film 204 was formed by depositing Au over the entire bottom surface shown in the figure, but the formation of the Au film 204 is not limited to this method. Here, when forming the Au film 204, the deposition conditions such as the ultimate vacuum level of the vacuum device used and the deposition rate are adjusted, and heat treatment is performed, etc., so that a desired size of unevenness R of 10 nm to 300 nm is formed on the edge portion 204e of the Au film 204, as shown in Figure 6. Furthermore, if larger irregularities (R) are to be formed, the irregularities can be formed along the pattern shape of the resist 203 by photolithography, so there is no particular upper limit to the irregularities. This completes the etching preparation process of S10.

[0042] Next, the through-hole formation process of step S20 in Figure 5 is performed. Specifically, a hydrogen fluoride aqueous solution, which is a solution of hydrogen fluoride and hydrogen peroxide, is used by MACE to form through-holes corresponding to the nozzle N, as shown in the fifth figure from the top in Figure 4. Then, the Au film 204 is etched to the state shown in the sixth figure from the top in Figure 4. This is then thinned by removing the lower surface in the figure by grinding or polishing, as shown in the seventh figure from the top in Figure 4, and the flow channel substrate 40 of this embodiment is completed as shown in the bottom figure in Figure 4. Note that Figure 7 is a photograph corresponding to the fifth figure from the top in Figure 4. As shown in Figure 6, by forming irregularities R on the edge portion 204e of the Au film 204, when MACE is performed, streaky portions L are formed on the nozzle N along the ink flow direction F.

[0043] As described above, in the manufacturing method of the channel substrate 40, which is a single-crystal silicon substrate in this embodiment, in the etching preparation step of step S10, an Au film 204, which is a catalyst film, is formed on the etching target area of ​​the fifth surface 40a, which is the catalyst film formation surface, of the substrate surface of the channel substrate 40. Then, in the through-hole formation step of step S20, the channel substrate 40 with the Au film 204 formed is brought into contact with an aqueous hydrogen fluoride solution as an etching solution to etch the etching target area and form a nozzle N as a through-hole that penetrates the channel substrate 40 in a direction intersecting the substrate surface. Here, as described above, in the through-hole formation step of step S20, a streak-like portion L is formed in which at least one of a recess and a convex portion extends along the through-hole direction of the nozzle N corresponding to the ink flow direction F. By performing this manufacturing method of the channel substrate 40, a dense streak-like portion L along the through-hole direction with a narrow formation pitch can be formed on the nozzle N. Therefore, by performing the manufacturing method of the channel substrate 40 in this embodiment, the ink flow in the nozzle N can be improved.

[0044] Furthermore, as described above, in the manufacturing method of the flow channel substrate 40 of this embodiment, the nozzle N is formed by MACE in the through-hole formation step S20. Therefore, dense streaky portions L along the through-hole direction with a narrow formation pitch can be suitably formed on the nozzle N. Consequently, the flow of ink in the nozzle N can be improved.

[0045] Here, in the etching preparation step of step S10, the step of forming the Au film 204 is not particularly limited in terms of method, but it is preferable that the Au film 204 be formed by electroless plating or vapor deposition. This is because forming the Au film 204 by electroless plating or vapor deposition allows for the production of the channel substrate 40 in a particularly simple and highly accurate manner.

[0046] Furthermore, in the manufacturing method of the channel substrate 40 of this embodiment, the etching preparation step S10 includes a step of forming a pattern with a resist shown in the second figure from the top of Figure 4 before the step of forming the Au film 204 shown in the third figure from the top of Figure 4, and a step of removing the resist shown in the fourth figure from the top of Figure 4 after the step of forming the Au film 204 shown in the third figure from the top of Figure 4. By adopting such a method, the channel substrate 40 can be easily manufactured.

[0047] Furthermore, in the manufacturing method of the flow channel substrate 40 of this embodiment, in the through-hole formation step S20, as shown in the sixth figure from the top of Figure 4, the Au film 204 is removed before the single crystal silicon substrate 201 penetrates, and as shown in the seventh figure from the top of Figure 4, a portion of the substrate surface on the sixth surface 40b side, opposite to the catalyst film formation surface (fifth surface 40a), is removed up to the position where the single crystal silicon substrate 201 penetrates, thereby forming the nozzle N. By adopting such a method, the flow channel substrate 40 can be easily manufactured.

[0048] Furthermore, in the through-hole formation step S20 of the manufacturing method of the flow channel substrate 40 in this embodiment, it is preferable that the nozzle N has a side wall composed of a vertical side wall 22a with an angle of 90° ± 2° or less with respect to the substrate surface of the flow channel substrate 40. This configuration suppresses the expansion of the substrate surface and allows for miniaturization of the flow channel substrate 40.

[0049] Next, the sealing plate 20 will be described in more detail with reference to Figure 8. As described above, the sealing plate 20 in this embodiment is a single-crystal silicon substrate on which a second through-hole 22 constituting the ink flow path 51 is provided in at least a portion of it. The second through-hole 22 constitutes a part of the flow path 51 and, as shown in Figure 8, is a through-hole that penetrates the sealing plate 20 in a direction intersecting the first surface 20a and the second surface 20b, which are substrate surfaces. Here, the second through-hole 22 is formed by MACE and, as shown in Figure 8, has streaky portions L with recesses and protrusions extending along the ink flow direction F. The formation pitch of the streaky portions L of the second through-hole 22 is the same as the formation pitch of the streaky portions L of the nozzle N. That is, the description of the nozzle N, which is a through-hole in the flow path substrate 40, can be applied to the sealing plate 20 by substituting the nozzle N for the second through-hole 22.

[0050] In this embodiment, the sealing plate 20 is formed by crystal anisotropic etching, and the second through hole 22 is formed by 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.

[0051] Here, the angle made by the vertical side wall 22a with respect to the substrate surface is preferably 90° plus or minus 2° or less, as described above. This is because, by using a single-crystal silicon wafer with a Miller index (surface index) of (100) on the substrate surface as the sealing plate 20, and by devising the etching solution composition, it is possible to control the vertical MACE etching, for example, within a range of about 400 μm for the thickness of the sealing plate 20, and ensure perpendicularity.

[0052] 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 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.

[0053] Next, the manufacturing method of the sealing plate 20 of this embodiment will be described with reference to Figures 5 and 9. That is, the flowchart for the manufacturing method of the sealing plate 20 of this embodiment is the same as the flowchart for the manufacturing method of the flow channel substrate 40 of this embodiment shown in Figure 5. In the manufacturing method of the sealing plate 20 of this embodiment, first, an oxide film 202 represented by SiO2 is formed on the single crystal silicon substrate 201 shown in the top figure of Figure 9, as shown in the second figure from the top of Figure 9. Then, as shown in the third figure from the top of Figure 9, a pattern is created using a resist by photolithography. Here, the pattern is created such that there is no oxide film 202 in the upper surface region of the single crystal silicon substrate 201 in the figure corresponding to the first through hole 21, and a thin oxide film 202 exists in the lower surface region of the single crystal silicon substrate 201 in the figure corresponding to the piezoelectric element housing chamber 23. Then, as shown in the fourth figure from the top of Figure 9, through holes corresponding to the first through hole 21 are formed by crystal anisotropic etching, which is wet etching using potassium hydroxide (KOH).

[0054] Next, as shown in the fifth figure from the top in Figure 9, the oxide film 202 in the lower surface region of the single-crystal silicon substrate 201 corresponding to the piezoelectric element housing chamber 23 is etched, and a recess corresponding to the piezoelectric element housing chamber 23 is formed by crystal anisotropic etching using KOH, as shown in the fifth figure from the top in Figure 9. Then, as shown in the seventh figure from the top in Figure 9, the entire oxide film 202 is etched and removed, and a pattern is created using resist 203 by photolithography, as shown in the eighth figure from the top in Figure 9. Here, the pattern is created so that there is no resist 203 in the upper surface region of the single-crystal silicon substrate 201 corresponding to the second through-hole 22. Then, as shown in the ninth figure from the top in Figure 9, an Au film 204, which is a gold film that will serve as a catalyst film for MACE, is formed in the upper surface region of the single-crystal silicon substrate 201 corresponding to the second through-hole 22. In the manufacturing method of the sealing plate 20 of this embodiment, the Au film 204 is processed in the same way as the Au film 204 in the manufacturing method of the flow channel substrate 40, so that irregularities R are formed on the edge portion 204e of the Au film 204. This corresponds to the etching preparation step of step S10.

[0055] Next, the through-hole formation process in step S20 of Figure 5 is performed. Specifically, a through-hole corresponding to the second through-hole 22 is formed by MACE using an aqueous hydrogen fluoride solution, as shown in the 10th figure from the top in Figure 9. Then, the Au film 204 is etched and the resist 203 is removed, completing the sealing plate 20 of this embodiment, as shown in the bottom figure in Figure 9.

[0056] As described above, in the manufacturing method of the sealing plate 20, which is a single-crystal silicon substrate in this embodiment, in the etching preparation step of step S10, an Au film 204, which is a catalyst film, is formed in the etching target area of ​​the first surface 20a, which is the catalyst film formation surface, of the substrate surface of the sealing plate 20. Then, in the through-hole formation step of step S20, the sealing plate 20 with the Au film 204 formed is brought into contact with an etching solution to etch the etching target area and form a second through-hole 22, which is a through-hole that penetrates the sealing plate 20 in a direction intersecting the substrate surface. Here, as described above, in the through-hole formation step of step S20, a streak-like portion L is formed in which at least one of a recess and a convex portion extends along the through-direction of the second through-hole 22. By performing this manufacturing method of the sealing plate 20, a dense streak-like portion L along the through-direction with a narrow formation pitch can be formed in the second through-hole 22. Therefore, by performing the manufacturing method of the sealing plate 20 in this embodiment, the flow of ink in the second through-hole 22 can be improved. In other words, the explanation of the method for forming the nozzle N, which is a through-hole in the manufacturing method of the flow channel substrate 40, can be made to correspond to the manufacturing method of the sealing plate 20 by replacing the nozzle N with the second through-hole 22.

[0057] Furthermore, the manufacturing method of the sealing plate 20 in 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 of the second through-hole 22 with respect to the substrate surface, by performing crystal anisotropic etching on the region of the substrate surface to be etched. For example, when arranging a component in the first through-hole 21, by making the first through-hole 21 an inclined through-hole that widens towards the end as in this embodiment, the component can be suitably arranged in the inclined through-hole.

[0058] In the step of forming the first through-hole 21 as an inclined through-hole, an alkaline aqueous solution can be used as the etching solution. By using an alkaline aqueous solution as the etching solution, an inclined through-hole can be easily formed. As the alkaline aqueous solution used as the etching solution, for example, 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 processing of silicon substrates with semiconductors.

[0059] Next, a method for manufacturing the entire liquid discharge head 1 using the sealing plate 20 and flow path substrate 40 formed as described above will be explained with reference to the flowchart in Figure 6. First, in step S110, the sealing plate 20 is formed. The sealing plate 20 is formed 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 CVD (Chemical Vapor Deposition) or the like. In step S150, the channel substrate 40 is formed. The formation of the channel substrate 40 is as described above. Here, step S150 may be performed before step S140. Then, in step S160, the 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 a chip by laser scribing or the like, and in step S180, the TCP constituting the conductive part is mounted on 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 state, so quality can be stabilized and mass production can be easily achieved.

[0061] As described above, the liquid discharge head 1 of this embodiment includes at least one of the sealing plate 20 and the flow channel substrate 40, which are single-crystal silicon substrates. It also includes a cavity substrate having a third surface 30a, which is a conductive portion forming surface on which a piezoelectric element 32 and electrode films 33 and 34, which are conductive portions that conduct to the piezoelectric element 32, are formed, and a fourth surface 30b, which is a flow channel forming surface on the opposite side of the third surface 30a, with at least a portion of which constitutes a flow channel 51. The third surface 30a or the fourth surface 30b is joined to at least one of the substrate surfaces of the sealing plate 20 and the flow channel substrate 40, so that the flow channel 51 of the fourth surface 30b communicates with the second through hole 22 or the nozzle N, which is a through hole. In this way, by joining the conductive portion forming surface to the substrate surface using at least one of the sealing plate 20 and the flow channel substrate 40 as single-crystal silicon substrates and the cavity substrate, the flow channel 51 of the flow channel forming surface communicates with the through hole, making it possible to manufacture a liquid discharge head 1 with improved ink flow in the through hole.

[0062] 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 the liquid discharge head. 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]

[0063] 1…Liquid discharge head, 11…Nozzle forming surface, 12…Nozzle row, 12A…Nozzle row, 12B…Nozzle row, 20…Sealing plate (single crystal silicon substrate), 20a…First surface (substrate surface, catalyst film forming surface), 20b…Second surface (substrate surface), 21…First through hole (inclined through hole), 21a…Inclined side wall, 22…Second through hole, 22a…Vertical side wall, 23…Piezoelectric element housing chamber, 24…Opening, 24a…Inclined surface, 28…Control IC, 29…FPC, 30…Cavity substrate, 30a…Third surface (substrate surface, conductive part forming surface), 30b…Fourth surface (substrate surface, flow path type) 31…Electrode part, 32…Piezoelectric element, 33…Electrode film (conductive part), 34…Electrode film (conductive part), 40…Flow channel substrate (single crystal silicon substrate), 40a…5th surface (substrate surface, catalyst film formation surface), 40b…6th surface (substrate surface), 41…Pressure chamber, 51…Flow channel, 51A…Flow channel, 51B…Flow channel, 51C…Flow channel, 51D…Circulation channel, 201…Single crystal silicon substrate, 202…Oxide film, 203…Resist, 204…Au film (catalyst film), 204e…Edge part, L…Streaky part, N…Nozzle (through hole), P0…Pitch, P1…Pitch, R…Roughness

Claims

1. A single crystal silicon substrate, at least a portion of which constitutes a liquid flow path, The single crystal silicon substrate constitutes a part of the flow path. a through hole penetrating in a direction intersecting the substrate surface; The through holes are formed by metal-assisted chemical etching, and the liquid flows through the through holes. The present invention is characterized in that the grooves and protrusions extending in the direction of the grooves are provided with stripes. A single crystal silicon substrate.

2. 2. The single crystal silicon substrate according to claim 1, The through hole has at least one of the recess and the protrusion as viewed from a penetrating direction of the through hole. There are several seats arranged side by side. The pitch between adjacent recesses or adjacent protrusions is 10 nm or more and 30 nm or more.

1. A single crystal silicon substrate, comprising: a first insulating layer having a thickness of 100 nm or less;

3. The single crystal silicon substrate according to claim 1 or 2, a conductive portion forming surface on which a piezoelectric element and a conductive portion electrically connected to the piezoelectric element are formed; a cavity having a flow passage forming surface on the opposite side to the conducting portion forming surface, the flow passage being partially formed therein; A tee board; Equipped with The conductive portion forming surface or the flow path forming surface is joined to the substrate surface, whereby the flow path is formed in a front surface. A liquid ejection head, characterized in that it communicates with the through hole.

4. forming a s on an etching target region of a substrate surface of a single crystal silicon substrate; The single crystal silicon substrate having the catalyst film formed thereon is brought into contact with an etching solution. The etching target area is etched to etch the single crystal silicon substrate so as to intersect with the substrate surface. forming a through hole penetrating in a direction having In the step of forming the through hole, at least a concave portion and a convex portion along a penetrating direction of the through hole are A method for manufacturing a single crystal silicon substrate, comprising forming a stripe-shaped portion having one end extending from the other end. 。

5. 5. The method for producing a single crystal silicon substrate according to claim 4, In the step of forming the through hole, the through hole is formed by metal-assisted chemical etching.

1. A method for producing a single crystal silicon substrate, comprising:

6. 6. The method for producing a single crystal silicon substrate according to claim 5, In the step of forming the catalyst film, the catalyst film is formed by electroless plating or vapor deposition.

4. A method for producing a single crystal silicon substrate, comprising:

7. 7. The method for producing a single crystal silicon substrate according to claim 4, A process to be performed before the process of forming the catalyst film, comprising forming a pattern with a resist. The process and A step of removing the resist, which is performed after the step of forming the catalyst film. and, 1. A method for producing a single crystal silicon substrate, comprising:

8. 7. The method for producing a single crystal silicon substrate according to claim 4, The through hole has a vertical side wall that is at an angle of 90° ±2° or less with respect to the substrate surface.

2. A method for producing a single crystal silicon substrate comprising the steps of:

9. 7. The method for producing a single crystal silicon substrate according to claim 4, In the step of forming the through hole, the catalyst film is removed before the single crystal silicon substrate is penetrated. A part of the surface opposite to the substrate surface is removed up to a position where the single crystal silicon substrate penetrates. a first insulating layer formed on the silicon substrate and a second insulating layer formed on the silicon substrate;

10. 7. The method for producing a single crystal silicon substrate according to claim 4, By subjecting the crystal anisotropic etching target region of the substrate surface to crystal anisotropic etching, Forming an inclined through hole having an inclined side wall that is more inclined with respect to the substrate surface than the side wall of the through hole 4. A method for producing a single crystal silicon substrate, comprising the steps of:

11. 11. The method for producing a single crystal silicon substrate according to claim 10, In the step of forming the inclined through hole, an alkaline aqueous solution is used as an etching solution.

2. A method for producing a single crystal silicon substrate comprising the steps of:

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