Nozzle plate, droplet dispensing head, droplet dispensing device, and method for manufacturing the nozzle plate

Abstract

This nozzle plate 110 comprises, on a first surface Ba of a single crystal silicon substrate B, a plurality of nozzle flow paths 111 each having a nozzle opening N formed for discharging droplets. The nozzle flow paths 111 each comprise: a nozzle tapered part 1112, of which the flow path area, i.e., the cross-sectional area orthogonal to the droplet discharge direction, gradually widens from the first surface Ba toward a second surface Bb facing the first surface Ba; and a straight communication part 1113 continuing from an end of the nozzle tapered part 1112 on the second surface Bb side, and having one pair of facing surfaces that are substantially parallel. Among sides of surfaces which constitute the straight communication part 1113 and intersect with the second surface Bb, the length of the side of the one pair of facing surfaces is greater than the lengths of the sides of other surfaces, and the crystal plane of the nozzle tapered part 1112 includes four planes of substantially (111)-planes.

Description

Technical Field

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[0001] The present invention relates to a nozzle plate, a droplet discharge head, a droplet discharge device, and a method for manufacturing a nozzle plate.

Background Art

[0002] Conventionally, as a method for manufacturing a nozzle plate of a droplet discharge head of a droplet discharge device, a method of forming a nozzle flow path by performing anisotropic wet etching on a single crystal silicon substrate is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when performing anisotropic wet etching on a single crystal silicon substrate whose crystal orientation on the surface is the {100} plane, the corrosion action proceeds in a certain direction. Therefore, only a nozzle flow path in which the opening of the surface facing the droplet discharge surface has a square shape can be formed. When such a nozzle plate is joined to another plate in which the cross-sectional shape of the ink flow path is, for example, rectangular, due to the shape mismatch at the joint between the ink flow path and the nozzle flow path, the resistance during ink injection becomes strong. Therefore, the injection characteristics deteriorate, such as the need to increase the driving voltage or the meniscus becoming unstable and injection defects occurring. Further, when the opening of the surface facing the droplet discharge surface has a square shape, the number of nozzle flow paths provided in the single crystal silicon substrate decreases.

[0005] The present invention has been made in view of these circumstances, and its purpose is to provide a nozzle plate, a droplet ejection head, a droplet ejection device, and a method for manufacturing a nozzle plate that can achieve both high density of the nozzle opening and suitable injection characteristics. [Means for solving the problem]

[0006] To solve the above problems, the invention described in claim 1 is: A nozzle plate comprising a single-crystal silicon substrate with a first surface having a plurality of nozzle channels in which nozzle openings for ejecting liquid droplets are formed, The nozzle flow path has a nozzle tapered section in which the flow path area, which is the cross-sectional area perpendicular to the droplet discharge direction, gradually widens as you move from the first surface toward the second surface opposite the first surface, The nozzle tapered portion is provided with a straight connecting portion that is continuous with the end on the second surface side and has a pair of opposing surfaces that are substantially parallel, Of the sides of the surfaces constituting the straight connecting portion that intersect with the second surface, the length of the sides of one pair of opposing surfaces is longer than the length of the sides of the other surfaces. The nozzle tapered portion includes four faces with approximately {111} crystal planes. fruit, Of the edges where the plane constituting the straight connecting portion intersects the second plane, the crystal planes of the pair of opposing planes where the length of the edges is longer than the length of the edges of the other planes are composed of approximately {100} planes. . Furthermore, in order to solve the above problems, the invention described in claim 2 is: A nozzle plate comprising a single-crystal silicon substrate with a first surface having a plurality of nozzle channels in which nozzle openings for ejecting liquid droplets are formed, The nozzle flow path has a nozzle tapered section in which the flow path area, which is the cross-sectional area perpendicular to the droplet discharge direction, gradually widens as you move from the first surface toward the second surface opposite the first surface, The nozzle tapered portion is provided with a straight connecting portion that is continuous with the end on the second surface side and has a pair of opposing surfaces that are substantially parallel, Of the sides of the surfaces constituting the straight connecting portion that intersect with the second surface, the length of the sides of one pair of opposing surfaces is longer than the length of the sides of the other surfaces. The nozzle tapered portion includes four faces with approximately {111} crystal planes. A side wall mask layer is provided in at least a portion of the area between the point where the nozzle tapered portion and the straight connecting portion intersect and the first surface.

[0007] Furthermore, in order to solve the above problems, 3 The invention described is A nozzle plate comprising a single-crystal silicon substrate with a first surface having a plurality of nozzle channels in which nozzle openings for ejecting liquid droplets are formed, The nozzle flow path includes a nozzle taper portion in which the flow path area, which is the cross-sectional area orthogonal to the droplet ejection direction, gradually widens as it goes from the first surface toward the second surface facing the first surface. It includes a straight communication portion that is continuous with the end portion on the second surface side of the nozzle taper portion and in which a pair of opposing surfaces are substantially parallel. Among the sides where the surfaces constituting the straight communication portion intersect the second surface, the length of the side of the pair of opposing surfaces is longer than the length of the sides of the other surfaces. The nozzle taper portion is composed of four surfaces whose crystal planes are substantially {111} planes. 、 Of the edges where the plane constituting the straight connecting portion intersects the second plane, the crystal planes of the pair of opposing planes where the length of the edges is longer than the length of the edges of the other planes are composed of approximately {100} planes. Nozzle plate. Furthermore, in order to solve the above problems, the invention described in claim 4 is: A nozzle plate comprising a single-crystal silicon substrate with a first surface having a plurality of nozzle channels in which nozzle openings for ejecting liquid droplets are formed, The nozzle flow path has a nozzle tapered section in which the flow path area, which is the cross-sectional area perpendicular to the droplet discharge direction, gradually widens as you move from the first surface toward the second surface opposite the first surface, The nozzle tapered portion is provided with a straight connecting portion that is continuous with the end on the second surface side and has a pair of opposing surfaces that are substantially parallel, Of the sides of the surfaces constituting the straight connecting portion that intersect with the second surface, the length of the sides of one pair of opposing surfaces is longer than the length of the sides of the other surfaces. The nozzle tapered portion is composed of four faces with approximately {111} crystal planes. A side wall mask layer is provided in at least a portion of the area between the point where the nozzle tapered portion and the straight connecting portion intersect and the first surface.

[0008] Also, the invention according to claim 5 is the nozzle plate according to claim 2 or 4 wherein, among the sides where the surfaces constituting the straight communication portion intersect the second surface, the crystal plane of the surface where the length of the side of the pair of opposing surfaces is longer than the length of the sides of the other surfaces is substantially composed of {101} planes.

[0011] Also, in order to solve the above problems, the invention according to claim 6 is a nozzle plate having a plurality of nozzle flow paths in which nozzle openings for ejecting droplets are formed on a first surface of a single crystal silicon substrate, where the nozzle flow path includes a nozzle taper portion in which the flow path area, which is the cross-sectional area orthogonal to the droplet ejection direction, gradually widens as it goes from the first surface toward the second surface facing the first surface, and a straight communication portion provided continuously from the end portion on the second surface side of the nozzle taper portion to the second surface. A sidewall mask layer is provided in at least a part between the portion where the nozzle taper portion and the straight communication portion intersect and the first surface. The nozzle taper portion includes four surfaces with a crystal plane substantially being the {111} plane.

[0012] Also, in order to solve the above problems, the invention according to claim 7 is A nozzle plate provided with a plurality of nozzle flow paths in which nozzle openings for discharging droplets are formed on a first surface of a single crystal silicon substrate, The nozzle flow path includes a nozzle taper portion in which a flow path area, which is a cross-sectional area orthogonal to the droplet discharge direction, gradually widens as it goes from the first surface toward a second surface facing the first surface, and a straight communication portion provided continuously to the second surface side end of the nozzle taper portion up to the second surface. A sidewall mask layer is provided in at least a part between the portion where the nozzle taper portion and the straight communication portion intersect and the first surface. The nozzle taper portion is composed of four surfaces with a crystal plane substantially being the {111} plane.

[0013] Also, the invention according to claim 8 is the nozzle plate according to any one of claims 6 or 7 wherein the sidewall mask layer has a shape that gradually becomes narrower as it goes from the first surface toward the second surface or from the second surface toward the first surface. <0,000,109>

[0014] Also, the invention according to claim 9 is the nozzle plate according to any one of claims 1 From 4, 6 or 7, wherein the nozzle flow path includes a nozzle straight portion continuous with the first surface side end of the nozzle taper portion.

[0015] Also, the invention according to claim 10 is the nozzle plate according to claim 9, wherein the maximum portion of the flow path area of the nozzle straight portion is not more than the flow path area of the first surface side end of the nozzle taper portion.

[0016] Furthermore, the invention described in claim 11 is the same as claim 1 From 4, A nozzle plate according to either item 6 or 7, The maximum length of the taper height from the first surface to the end of the nozzle taper portion on the second surface side is 20 μm or more.

[0017] Furthermore, the invention described in claim 12 is, A droplet dispensing head mounted on a droplet dispensing device, Claim 1 From 4, The nozzle plate is provided as described in either item 6 or 7.

[0018] Furthermore, the invention described in claim 13 is, A droplet dispensing device, The device is equipped with the droplet dispensing head described in claim 12.

[0019] Furthermore, the invention described in claim 14 is, A method for manufacturing a nozzle plate of a droplet dispensing head, A first step involves forming a surface mask layer on the first surface of a single-crystal silicon substrate whose surface crystal orientation is {100} plane, The second step involves forming a slit pattern on the surface mask layer, A third step involves forming the slits in the single-crystal silicon substrate located beneath the slit pattern by dry etching from the surface, either through-etching or partially deep-etching; The fourth step involves forming a side wall mask layer in the aforementioned slit, A fifth step involves forming a circular or polygonal opening pattern, which will serve as a nozzle opening, on the surface mask layer. A sixth step involves forming through-holes in the single-crystal silicon substrate located beneath the aforementioned opening pattern by dry etching from the surface, The seventh step includes enlarging the through-hole by anisotropic wet etching of the single-crystal silicon substrate, thereby forming a nozzle tapered portion and a straight connecting portion continuous with the end of the nozzle tapered portion on the second surface side facing the first surface.

[0020] Furthermore, the invention described in claim 15 is a method for manufacturing a nozzle plate as described in claim 14, The eighth step involves forming a nozzle straight section by dry etching partway through the single-crystal silicon substrate located beneath the opening pattern, A ninth step of forming a nozzle mask layer along the inner surface of the nozzle straight portion is performed between the fifth and sixth steps.

[0021] Furthermore, the invention described in claim 16 is, A method for manufacturing a nozzle plate of a droplet dispensing head, A first step involves forming a surface mask layer on the first surface of a single-crystal silicon substrate whose surface crystal orientation is {100} plane, A second step involves simultaneously forming a circular or polygonal opening pattern, which will serve as a nozzle opening, and a slit pattern, which will serve as a slit, on the surface mask layer. A third step involves forming a slit in the single-crystal silicon substrate located beneath the slit pattern by dry etching from the surface, either through-etching or partially deep-etching. A fourth step involves forming a side wall mask layer in the slit, A fifth step involves forming through-holes in the single-crystal silicon substrate located beneath the aforementioned opening pattern by dry etching from the surface, The sixth step includes enlarging the through-hole by anisotropic wet etching of the single-crystal silicon substrate to form a nozzle tapered portion and a straight connecting portion continuous with the end of the nozzle tapered portion on the second surface side facing the first surface.

[0022] Furthermore, the invention described in claim 17 is a method for manufacturing a nozzle plate as described in claim 16, A seventh step involves forming a nozzle straight section by dry etching partway through the single-crystal silicon substrate located beneath the opening pattern, An eighth step of forming a nozzle mask layer along the inner surface of the nozzle straight portion is performed between the third step and the fifth step. [Effects of the Invention]

[0023] According to the nozzle plate, droplet ejection head, droplet ejection device, and method for manufacturing the nozzle plate of the present invention, it is possible to achieve both high density of the nozzle opening and suitable injection characteristics. [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic perspective view of the droplet dispensing device according to this embodiment. [Figure 2] This is an exploded perspective view showing the main part of the droplet dispensing head according to this embodiment. [Figure 3A] This is an enlarged plan view of the nozzle plate showing the nozzle flow path according to this embodiment. [Figure 3B] Figure 3A is a cross-sectional view of the nozzle plate along the line IIIB-IIIB. [Figure 4] This is a cross-sectional view of a modified nozzle plate. [Figure 5A] This is an enlarged plan view of a nozzle plate showing a nozzle flow path according to another embodiment. [Figure 5B] This is an enlarged plan view of a nozzle plate showing a nozzle flow path according to another embodiment. [Figure 5C] This is an enlarged plan view of a nozzle plate showing a nozzle flow path according to another embodiment. [Figure 6] This is a cross-sectional view of a nozzle plate showing a nozzle flow path according to another embodiment. [Figure 7] This is a cross-sectional view of a nozzle plate showing a nozzle flow path according to another embodiment. [Figure 8]This is a cross-sectional view of a nozzle plate showing the main steps of the manufacturing method of the nozzle plate according to the first embodiment. [Figure 9] This is a cross-sectional view of a nozzle plate showing the main steps of the manufacturing method of the nozzle plate according to the second embodiment. [Figure 10] This is a cross-sectional view of a nozzle plate showing the main steps of the manufacturing method of a nozzle plate according to the third embodiment. [Figure 11] This is a cross-sectional view of a nozzle plate showing a modified example of the main steps of the method for manufacturing a nozzle plate according to the third embodiment. [Figure 12] This is a cross-sectional view of a nozzle plate showing a modified example of the main steps of the method for manufacturing a nozzle plate according to the third embodiment. [Figure 13] This is a cross-sectional view of a nozzle plate showing the manufacturing process of a modified nozzle plate. [Figure 14] This is a cross-sectional view of a nozzle plate showing the manufacturing process of a modified nozzle plate. [Figure 15] This is an enlarged plan view showing one of the ink channels in a piezoelectric plate. [Figure 16A] This is an enlarged plan view showing the nozzle flow path of a nozzle plate relating to a comparative example. [Figure 16B] This is a cross-sectional view of an inkjet head to which a nozzle plate relating to a comparative example is attached, showing a plane perpendicular to the front-to-back direction. [Figure 17A] This is an enlarged plan view showing the nozzle flow path of a nozzle plate relating to a comparative example. [Figure 17B] This is a cross-sectional view of an inkjet head to which a nozzle plate relating to a comparative example is attached, showing a plane perpendicular to the front-to-back direction. [Figure 17C] This is a cross-sectional view of an inkjet head to which a nozzle plate relating to a comparative example is attached, showing a plane perpendicular to the left-right direction. [Figure 18A] This is an enlarged plan view showing the nozzle flow path of a nozzle plate relating to a comparative example. [Figure 18B] This is a cross-sectional view of an inkjet head to which a nozzle plate relating to a comparative example is attached, showing a plane perpendicular to the front-to-back direction. [Figure 18C] This is a cross-sectional view of an inkjet head to which a nozzle plate relating to a comparative example is attached, showing a plane perpendicular to the left-right direction. [Modes for carrying out the invention]

[0025] Preferred embodiments of the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In the following description, components having the same function and configuration will be denoted by the same reference numerals, and their descriptions will be omitted.

[0026] [Inkjet recording device] First, as a droplet ejection device according to this embodiment, we disclose an example configuration of an inkjet recording device 1 equipped with an inkjet head 10, which is a droplet ejection head. In the following explanation, as shown in each figure, the transport direction of the recording medium P in the inkjet recording device 1 will be described as the front-to-back direction, the direction perpendicular to the transport direction on the transport surface of the recording medium P will be described as the left-to-right direction, and the direction perpendicular to the front-to-back and left-to-right directions (ink ejection direction) will be described as the up-and-down direction. The inkjet head 10 will also be described in terms of the direction relative to its state when mounted in the inkjet recording device 1.

[0027] Figure 1 is a schematic perspective view showing an inkjet recording apparatus 1 according to this embodiment. The inkjet recording apparatus 1 transports a recording medium P, such as paper, in the forward and backward direction by a transport unit T, which includes, for example, a transport belt T1 and transport rollers T2, passing through a plurality of units U. Each unit U is equipped with a plurality of inkjet heads 10, and ink of each color is ejected from each inkjet head 10 to print on the recording medium P.

[0028] [Inkjet head] Figure 2 is an exploded perspective view showing the main components of one inkjet head 10. Specifically, Figure 2 shows a head chip 100 having a nozzle plate 110, a flow path plate 120, a piezoelectric plate 130, and a wiring plate 140. Figure 2 also shows an FPC 200 (Flexible Printed Circuit). The FPC 200 is electrically connected to the wiring plate 140. Note that in Figure 2, the nozzle opening N is positioned at the top, meaning that the image is inverted vertically compared to Figure 1.

[0029] [Head Tip] As shown in Figure 2, the head chip 100 has a structure in which each plate is stacked. The nozzle plate 110, the flow path plate 120, the piezoelectric plate 130, and the wiring plate 140 are all plate-like members that are elongated in the left-right direction and are roughly rectangular prism-shaped.

[0030] (Nozzle plate) The nozzle plate 110 is a substrate on which nozzle channels 111 (see Figure 3A), which are holes that penetrate in the vertical direction, are arranged in a row along the left-right direction.

[0031] A nozzle opening N, which is the opening of the nozzle flow path 111, is provided on the lower side of the nozzle plate 110. In other words, the lower side of the nozzle plate 110 forms the ejection surface (first surface) Ba of the inkjet head 10. Ink is ejected from the nozzle opening N approximately perpendicular to the ejection surface Ba. Details of the nozzle plate 110 and the nozzle flow path 111 will be described later.

[0032] (Flow channel plate) The flow path plate 120 is a rectangular parallelepiped plate-like member whose shape, when viewed from above or below, is almost identical to that of the nozzle plate 110. The flow path plate 120 is provided with a through-flow channel 121 and individual discharge channels 122. The through-flow channel 121 is a channel that communicates with the nozzle flow channel 111. The individual discharge channel 122 is a channel that branches off from the through-flow channel 121.

[0033] The lower surface of the flow path plate 120 is bonded (fixed) via adhesive to the adhesive surface (second surface) Bb (see Figure 3A), which is the surface facing the discharge surface Ba of the nozzle plate 110. The lower surface of the piezoelectric plate 130 is also bonded (fixed) via adhesive to the upper surface of the flow path plate 120. The flow channel plate 120 is made of, for example, a silicon substrate.

[0034] (Piezoelectric plate) The piezoelectric plate 130 is a rectangular parallelepiped plate-like member whose shape, when viewed from above or below, is almost identical to that of the nozzle plate 110. The piezoelectric plate 130 is provided with a pressure chamber 131, a common discharge channel 132, and a vertical discharge channel 133. The pressure chamber 131 communicates with the through-flow channel 121. The common discharge channel 132 communicates with the individual discharge channels 122. The vertical discharge channel 133 also communicates with the common discharge channel 132.

[0035] The piezoelectric plate 130 is made of a ceramic piezoelectric material (a component that deforms in response to the application of voltage). Examples of such piezoelectric materials include PZT (lead zirconate titanate), lithium niobate, barium titanate, lead titanate, and lead metaniobate.

[0036] (Wiring plate) The wiring plate 140 is a flat substrate having a larger area than the piezoelectric plate 130. The wiring plate 140 is provided with an ink supply channel 141 and an ink discharge hole 142. The ink supply channel 141 communicates with an ink chamber (not shown) via a first opening 1411 on the upper side. The ink supply channel 141 also communicates with a pressure chamber 131 via a second opening 1412 on the lower side. The discharge hole 142 communicates with a vertical discharge channel 133.

[0037] The wiring plate 140 is bonded to the upper surface of the piezoelectric plate 130 via adhesive on its lower surface. For the wiring plate 140, a substrate such as glass, ceramics, silicon, or plastic can be used.

[0038] Multiple wires are provided on the bonding surface of the wiring plate 140 with the piezoelectric plate 130, each connected to an electrode of an ink channel, which will be described later. Furthermore, the FPC 200 is connected to the end of the wiring plate 140 where the wires are provided, for example, via an ACF (Anisotropic Conductive Film). The drive signal output from the drive circuit (not shown) is supplied to the electrodes of the ink channel via the wiring 210 on the FPC200 and the wiring on the wiring plate 140.

[0039] {ink channel} When the flow path plate 120, piezoelectric plate 130, and wiring plate 140 are joined together, the through-flow path 121, pressure chamber 131, and ink supply flow path 141 are connected to form an ink channel. The ink channel is positioned to overlap with the nozzle flow path 111 when viewed from above and below, and is in communication with the nozzle flow path 111. In this way, the ink channel and the nozzle flow path 111 each constitute an ink channel.

[0040] Electrodes (not shown) are formed on the inner wall surface of the ink channel. Depending on the potential difference of the drive signal applied to the electrodes of adjacent ink channels, the piezoelectric portion of the piezoelectric plate 130 on the wall surface between the ink channels is displaced. As this wall surface repeatedly undergoes shear mode displacement, the pressure of the ink in the ink channel fluctuates. Then, in response to this pressure fluctuation, the volume of the pressure chamber 131 changes, and the ink in the ink channel is ejected from the nozzle opening N. In other words, the inkjet head 10 of this embodiment performs shear mode ink ejection.

[0041] {ink discharge channel} Furthermore, the ink discharge channel is formed by the individual discharge channel 122, the common discharge channel 132, the vertical discharge channel 133, and the discharge hole 142. A portion of the ink supplied from the ink chamber to the ink channel can be discharged to the outside of the inkjet head 10 through this ink discharge channel. This allows air bubbles and foreign matter in the ink channel to be discharged to the outside of the head chip 100 along with the ink.

[0042] In the inkjet head 10 according to the present invention, the flow path plate 120 is not an essential component. That is, the nozzle plate 110 and the piezoelectric plate 130 may be directly bonded together.

[0043] Furthermore, as described above, it is preferable that the openings of the ink flow paths on the bonding surfaces of each plate of the head tip 100 have similar shapes, and it is even more preferable that they have the same shape. Furthermore, while Figure 2 shows a nozzle plate 110 with only one row of nozzle openings N arranged in the left-right direction, it is not limited to this. In other words, multiple rows of nozzle openings N may be provided in the front-back direction.

[0044] [Nozzle Plate] Figure 3A is an enlarged plan view showing one nozzle channel 111 as seen from the adhesive surface Bb side of the nozzle plate 110. Figure 3B is a cross-sectional view showing one nozzle channel 111 along the line IIIB-IIIB in Figure 3A. The nozzle plate 110 is made of a single-crystal silicon substrate B.

[0045] (Single-crystal silicon substrate) The single-crystal silicon substrate B is a plate-like member made of single-crystal silicon (Si) with a thickness of approximately 100 μm to 725 μm. By using the single-crystal silicon substrate B as the base material for the nozzle plate 110, the nozzle channel 111 can be processed with high precision during the manufacturing process. Therefore, it is possible to form nozzle channel 111 with less positional error and less variation in shape.

[0046] (Nozzle flow path) The nozzle channel 111 is a through-hole that penetrates from the discharge surface Ba to the bonding surface Bb of the single-crystal silicon substrate B. As shown in Figure 3B, extending from the discharge surface Ba to the bonding surface Bb, it comprises, for example, a nozzle opening N, a nozzle straight section 1111, a nozzle tapered section 1112, and a straight connecting section 1113.

[0047] <Nozzle opening> The nozzle opening N is a circular or polygonal hole. The nozzle openings N are arranged in a matrix on the discharge surface Ba side of the single-crystal silicon substrate B, and the adhesive surface Bb side is in communication with the nozzle straight section 1111. For example, if the shape of the nozzle opening N is circular, its diameter can be approximately 15 μm to 45 μm.

[0048] <Nozzle straight section> As shown in Figure 3B, the nozzle straight section 1111 is formed continuously with the end of the nozzle tapered section 1112 on the discharge surface Ba side. The presence of the nozzle straight section 1111 increases the resistance when ejecting ink from the nozzle opening N, suppressing meniscus vibration and thus stabilizing the meniscus shape.

[0049] In Figure 3B, the flow path area, which is the cross-sectional area in the direction perpendicular to the ink ejection direction (left-right direction in Figure 3B) of the nozzle straight section 1111, is shown as an example where it is approximately constant in the vertical direction, but this is not the only example.

[0050] For example, the angle that the nozzle straight section 1111 makes with an axis parallel to the nozzle central axis is not limited to 0°, and it may be tapered if the angle is less than 15°. Also, as shown in Figure 4, the nozzle straight section 1111 may have multiple surfaces 1111a, 1111b, each with a different angle that it makes with an axis parallel to the nozzle central axis. However, from the viewpoint of further enhancing the effect of improving meniscus stability, it is preferable that the maximum flow area of ​​the nozzle straight section 1111 is less than or equal to the flow area of ​​the end of the nozzle tapered section 1112 on the discharge surface Ba side.

[0051] Furthermore, the vertical length of the nozzle straight section 1111 (the height of the nozzle straight section 1111) is preferably about 5 μm to 50 μm. Having the height of the nozzle straight section 1111 within this range ensures that appropriate resistance is applied when ejecting the ink.

[0052] <Nozzle tapered section> The nozzle tapered section 1112 includes four {111} crystal planes, and the flow path area gradually widens from the discharge surface Ba towards the adhesion surface Bb. It has a tapered section with a substantially constant angle, where the angle it makes with the axis parallel to the nozzle central axis is 15° or more. By providing the nozzle tapered section 1112 in the nozzle flow path 111, the meniscus shape and ink ejection can be stabilized even when the ink meniscus retracts to the back of the nozzle flow path 111 due to high-speed driving.

[0053] In the nozzle flow path 111, there are at least locations where the taper height h, which is the height from the discharge surface Ba to the end of the nozzle tapered portion 1112 on the adhesive surface Bb side, is 20 μm or more, as shown in Figure 3B. In other words, it is preferable that the maximum length of the taper height h is 20 μm or more. By having a maximum length of taper height h of 20 μm or more, a sufficient effect of stabilizing the ink meniscus shape of the nozzle tapered portion 1112 can be obtained. Furthermore, as shown in Figure 3B, if the nozzle flow path 111 includes a nozzle straight section 1111, the taper height h includes the height of the nozzle straight section 1111.

[0054] Furthermore, the nozzle tapered portion 1112 only needs to include the four {111} crystal planes. The nozzle tapered portion 1112 may also include other planes, for example, that have crystal planes different from the {111} planes and that have different angles with the axis parallel to the nozzle central axis.

[0055] On the other hand, the nozzle tapered portion 1112 may consist only of four faces with {111} crystal planes. Specifically, if there is a plane (terrace plane) that is substantially parallel to the discharge surface Ba at the connection between the nozzle tapered portion 1112 and the straight connecting portion 1113, then the nozzle tapered portion 1112 can satisfy both the configuration in which it consists only of four faces with {111} crystal planes and the configuration of the straight connecting portion 1113 described later.

[0056] <Straight connection section> The straight connecting section 1113 is continuous with the end of the nozzle tapered section 1112 on the adhesive surface Bb side and extends to the adhesive surface Bb.

[0057] As shown in Figure 3A, the straight connecting section 1113 has a pair of opposing surfaces that are approximately parallel. Furthermore, the surfaces constituting the straight connecting section 1113 are configured such that the length of the sides of one pair of opposing surfaces intersecting the adhesive surface Bb is longer than the lengths of the sides of the other surfaces. The shape of the opening in the adhesive surface Bb is elongated. Thus, by having an elongated cross-sectional shape on the surface perpendicular to the vertical direction of the straight connecting portion 1113, the density of nozzle openings N in the nozzle plate 110 can be further increased.

[0058] (Sidewall mask layer) The sidewall mask layer 112 blocks the through-holes (slits S described later) that are formed adjacent to the nozzle channel 111 during the nozzle channel formation process described later. It then plays a role in preventing ink from leaking out through these through-holes when the nozzle plate 110 is in use. As shown in Figure 3B, the sidewall mask layer 112 is provided along the inner surface of the straight communication portion 1113 at the point where the nozzle tapered portion 1112 and the straight communication portion 1113 intersect.

[0059] There are no particular restrictions on the material used to form the sidewall mask layer 112. For example, oxides such as SiO2 (silicon oxide), metal plating with Al (aluminum) or Cr (chromium), or resin can be used.

[0060] Furthermore, the width of the sidewall mask layer 112 is preferably 0.1 μm to 50 μm. In particular, the width of the sidewall mask layer 112 is preferably 0.5 μm to 20 μm. If the width of the sidewall mask layer 112 is 0.5 μm or more, the effect of stopping the progress of anisotropic wet etching (WE) in the straight communication portion 1113 formation process described later is enhanced. Also, if the width of the sidewall mask layer 112 is 20 μm or less, the formation becomes easier. In particular, when the sidewall mask layer 112 is made of an oxide, its width is preferably 0.5 μm to 5 μm. This is because if the width of the sidewall mask layer 112 is 5 μm or less, it can be formed by thermal oxidation in a short time and at low cost.

[0061] Furthermore, as shown in Figure 3B, the sidewall mask layer 112 is preferably formed such that its width gradually narrows from one of the discharge surface Ba and adhesive surface Bb to the other. Specifically, it is preferable that the width of the tip on the other surface is 20% or more narrower than the width of the tip on the other surface. The shape of the sidewall mask layer 112 makes it easier for the sidewall mask layer 112 to be filled without voids during the sidewall mask layer 112 formation process described later.

[0062] Furthermore, if the cross-sectional shape of the plane perpendicular to the vertical direction of the straight connecting portion 1113 is elongated, it is preferable that the crystal plane of the plane where the plane constituting the straight connecting portion 1113 intersects with the adhesive surface Bb, where the length of one pair of opposing planes is longer than the length of the other planes, is composed of approximately {101} planes of the single crystal silicon substrate B, as shown in Figure 3A, or approximately {100} planes of the single crystal silicon substrate B, as shown in Figure 5A. With this configuration, the nozzle tapered portion 1112 becomes symmetrical, as shown in Figures 3A and 5A. As a result, the symmetry of the ink flow in the nozzle channel 111 is maintained, and the injection angle becomes more stable. Furthermore, the straight connecting portion 1113 is not limited to a configuration in which the crystal plane is composed of approximately {101} planes or approximately {100} planes of the single-crystal silicon substrate B.

[0063] Furthermore, while Figure 3A illustrates a configuration in which a pair of approximately {101} faces of the straight connecting section 1113 are approximately parallel and the cross-sectional shape of the face perpendicular to the vertical direction of the straight connecting section 1113 is elongated, the configuration is not limited to this. For example, as shown in Figure 5B, neither of the opposing faces may be approximately parallel, and the cross-sectional shape of the face perpendicular to the vertical direction of the straight connecting section 1113 may be circular. Also, as shown in Figure 5C, all opposing faces may be approximately parallel, and the cross-sectional shape of the face perpendicular to the vertical direction of the straight connecting section 1113 may be rectangular.

[0064] Furthermore, as shown in Figure 6, the side wall mask layer 112 of the nozzle plate 110 may be removed in the portion adjacent to the straight communication portion 1113. Ink leakage can be suppressed as long as the side wall mask layer 112 remains in at least a portion between the point where the nozzle tapered portion 1112 and the straight communication portion 1113 intersect and the discharge surface Ba. Furthermore, while Figures 3B and 4 illustrate the case where the sidewall mask layer 112 is formed to penetrate the single-crystal silicon substrate B, the invention is not limited to this case.

[0065] Furthermore, while Figures 3A and 5A to 5C illustrate the case where the nozzle opening N is approximately square in shape, it is not limited to this. If the nozzle flow path 111 includes a nozzle straight section 1111, the nozzle opening N may be any shape, such as a circle or a polygon.

[0066] Furthermore, as shown in Figure 7, the nozzle flow path 111 only needs to include at least a nozzle opening N, a nozzle tapered portion 1112, and a straight connecting portion 1113.

[0067] Furthermore, although the above example illustrates a nozzle plate 110 attached to the inkjet head 10 and ejecting ink, the liquid ejected from the nozzle plate 110 is not limited to ink.

[0068] [Effects of the invention] As described above, the nozzle plate 110 according to this embodiment is a nozzle plate 110 having a plurality of nozzle channels 111 formed on the first surface Ba of a single crystal silicon substrate B, wherein the nozzle channels 111 include a nozzle tapered section 1112 in which the channel area, which is the cross-sectional area perpendicular to the droplet discharge direction, gradually widens from the first surface Ba toward the second surface Bb opposite the first surface Ba, and a straight connecting section 1113 that is continuous with the end of the nozzle tapered section 1112 on the second surface Bb side, and in which a pair of opposing surfaces are substantially parallel, wherein the length of the side of one pair of opposing surfaces that make up the straight connecting section 1113 intersects with the second surface Bb is longer than the length of the side of the other surfaces, and the nozzle tapered section 1112 includes four surfaces whose crystal planes are substantially {111} planes. According to this configuration, the cross-sectional shape of the surface perpendicular to the vertical direction of the straight connecting portion 1113 becomes elongated, which increases the density of nozzle openings N in the nozzle plate 110. Furthermore, when joined with another plate having an ink channel with a rectangular cross-sectional shape of the surface perpendicular to the vertical direction, the shapes of the joint between the ink channel and the nozzle channel 111 are substantially the same, thus improving the injection characteristics.

[0069] Furthermore, among the edges of the planes constituting the straight connecting portion 1113 that intersect with the second plane Bb, the crystal planes of the pair of opposing planes whose edge lengths are longer than the edge lengths of the other planes are approximately {101} planes or approximately {100} planes. With this configuration, the nozzle tapered portion 1112 is symmetrical, maintaining the symmetry of the liquid flow, and thus the injection angle becomes more stable.

[0070] Furthermore, the nozzle plate 110 according to this embodiment is a nozzle plate 110 having a plurality of nozzle channels 111 formed on the first surface Ba of a single crystal silicon substrate B, wherein the nozzle channels 111 include a nozzle tapered portion 1112 in which the channel area, which is a cross-sectional area perpendicular to the droplet discharge direction, gradually widens from the first surface Ba toward the second surface Bb opposite the first surface Ba, and a straight connecting portion 1113 that is provided continuously from the end of the nozzle tapered portion 1112 on the second surface Bb side to the second surface Bb, wherein a side wall mask layer 112 is provided in at least a part between the portion where the nozzle tapered portion 1112 and the straight connecting portion 1113 intersect and the first surface Ba, and the nozzle tapered portion 1112 includes four surfaces whose crystal planes are approximately {111} planes. According to this configuration, it is possible to block the through-hole formed adjacent to the nozzle flow path 111 and prevent liquid from flowing out of the through-hole.

[0071] Furthermore, the sidewall mask layer 112 has a shape that gradually narrows as it moves from the first surface Ba to the second surface Bb or from the second surface Bb to the first surface Ba. With this configuration, the sidewall mask layer 112 is more easily filled without voids, which makes it possible to better prevent liquid from flowing out from through holes formed adjacent to the nozzle flow path 111.

[0072] Furthermore, the nozzle flow path 111 includes a nozzle straight section 1111 that is continuous with the end of the first surface side Ba of the nozzle tapered section 1112. This configuration increases resistance during droplet ejection, suppresses meniscus vibration, stabilizes the meniscus shape, and improves injection stability.

[0073] Furthermore, the nozzle straight section 1111 has a maximum flow path area that is less than or equal to the flow path area at the end of the first surface Ba side of the nozzle tapered section 1112. According to this configuration, the effect of improving meniscus stability by providing the nozzle straight section 1111 can be further enhanced.

[0074] Furthermore, the maximum length of the taper height h from the first surface Ba to the end of the second surface Bb of the nozzle taper portion 1112 is 20 μm or more. This configuration increases resistance during droplet ejection, suppresses meniscus vibration, stabilizes the meniscus shape, and improves injection stability.

[0075] [Method for manufacturing nozzle plates] [First Embodiment] Next, a manufacturing method for the nozzle plate 110 according to the first embodiment described above will be explained with reference to Figure 8. The method for manufacturing a nozzle plate according to the first embodiment is a method for manufacturing a nozzle plate 110 of a droplet discharge head 10, and includes steps A-1 to A-7 shown in Figure 8. The method manufactures a nozzle plate 110 having at least a nozzle opening N and a nozzle flow path 111 having a nozzle tapered portion 1112 and a straight connecting portion 1113.

[0076] (A-1 process) First, as step A-1 (first step), a surface mask layer 113 is uniformly formed on the ejection surface (first surface) Ba of a single-crystal silicon substrate B whose surface crystal orientation is {100} plane.

[0077] <Surface mask layer> As the material for forming the surface mask layer 113, similar to the sidewall mask layer 112, for example, SiO2, Al, Cr, or resin can be used.

[0078] As for the method of forming the surface mask layer 113, for example, for the formation of a mask layer composed of SiO2, thermal oxidation or CVD (Chemical Vapor Deposition) can be applied. Preferably, SiO2 is formed by thermal oxidation. This is because SiO2 has good adhesion to the single-crystal silicon substrate B and has the effect of preventing side etching during anisotropic wet etching (WE), which will be described later.

[0079] The surface mask layer 113 may be a single layer or a multilayer structure, as shown in Figure 8.

[0080] (A-2 process) Next, in step A-2 (second step), a slit pattern 115, which will become the slit S described later, is formed on the surface mask layer 113. Specifically, a resist pattern is first formed on the surface mask layer 113 using a well-known photolithography technique.

[0081] <Resistance Pattern> Positive or negative photoresists can be used to form the resist pattern. Known materials can be used as positive and negative photoresists. For example, ZPN-1150-90 manufactured by Nippon Zeon Co., Ltd. can be used as a negative photoresist. OFPR-800LB and OEBR-CAP112PM manufactured by Tokyo Ohka Kogyo Co., Ltd. can be used as positive photoresists.

[0082] The resist layer is formed by coating it to a predetermined thickness using a spin coater or similar device. Afterward, a pre-baking process is performed at 110°C for 90 seconds.

[0083] To improve adhesion, HMDS (hexamethyldisilazane) treatment may be applied before resist coating. HMDS treatment involves an organic material called hexamethyldisilazane; for example, OAP (hexamethyldisilazane, manufactured by Tokyo Ohka Kogyo Co., Ltd.) can be used. Similar to resist coating, it may be applied using a spin coater, or exposure to hexamethyldisilazane vapor can also be expected to improve adhesion.

[0084] After the resist layer is formed, the resist layer is exposed using a predetermined mask and an aligner or the like. For example, in the case of a contact aligner, this is done with a light intensity of approximately 50 mJ / cm2. Then, it is immersed in a developer (for example, NMD-3 manufactured by Tokyo Ohka Kogyo Co., Ltd. for 60 to 90 seconds) to remove the photosensitive portion of the resist layer, thereby forming a resist pattern on the surface mask layer 113.

[0085] After the resist pattern is formed, the slit pattern 115 is formed by dry etching (DE1) the surface mask layer 113 using the resist pattern as a mask. After the slit pattern 115 is formed, the resist pattern is removed.

[0086] <Dry etching> Dry etching (DE1) can be performed using dry etching equipment such as RIE (Reactive Ion Etching) equipment or ICP (Inductively Coupled Plasma)-RIE etching equipment, which employs an inductively coupled discharge method. Process gases such as CHF3 (trifluoromethane) and CF4 (tetrafluoride methane) can also be used.

[0087] For example, using the RIE-100C dry etching system manufactured by Samco Corporation, a slit pattern 115 can be formed by etching for a predetermined time under the conditions of a CHF3 gas flow rate of 80 sccm, a pressure of 3 Pa, and an RF power of 90 W.

[0088] <Removal of resist pattern> Furthermore, the resist pattern can be removed by methods such as a wet process using acetone or an acid solution, or a dry process using oxygen plasma.

[0089] (A-3 process, A-4 process) Next, in step A-3 (third step), a slit S is formed by dry etching (DE2) through the single-crystal silicon substrate B located beneath the slit pattern 115 from the surface. Then, in step A-4 (fourth step), a sidewall mask layer 112 is formed in the slit S.

[0090] In this case, dry etching (DE2) can be performed using an ICP-RIE etching apparatus that employs an inductively coupled plasma discharge method.

[0091] <Bosch Process> Furthermore, by using the Bosch process, which involves cyclically repeating film deposition and etching using process gases such as SF6 (sulfur hexafluoride), C4F8 (cyclobutane octafluoride), and O2 (oxygen), it is possible to form highly accurate, vertical slits S.

[0092] In addition, the slit S may be formed such that the width of the cross-section of the plane perpendicular to the vertical direction is equal at any location. However, in this case, when forming the sidewall mask layer 112, the slit S is more likely to be blocked by the mask on the front side, and there is a risk that a void will be formed on the back side. Therefore, as shown in Figure 8, forming the slit S so that it gradually narrows from one side to the other of the single crystal silicon substrate B makes it easier to form a sidewall mask layer 112 without voids. Furthermore, this is preferable because it allows for the formation of a more precise straight connecting section 1113 during the anisotropic wet etching (WE) in step A-7 described later.

[0093] Furthermore, as a method for forming the sidewall mask layer 112, for example, a thermal oxidation method using SiO2 can be applied.

[0094] (A-5 process) Next, in step A-5 (the fifth step), a circular or polygonal opening pattern 114, which will become the nozzle opening N, is formed on the surface mask layer 113. The method for forming the opening pattern 114 is the same as the method for forming the slit pattern 115 in step A-2.

[0095] (A-6 process) Next, in step A-6 (the sixth step), through holes are formed in the single-crystal silicon substrate B located beneath the opening pattern 114 by dry etching (DE2) from the surface.

[0096] (A-7 process) Finally, in step A-7 (the seventh step), the through hole is enlarged by anisotropic wet etching (WE). This forms a nozzle tapered portion 1112 and a straight connecting portion 1113 that communicates with the nozzle tapered portion 1112.

[0097] <Anisotropic wet etching> In anisotropic wet etching (WE), alkaline aqueous solutions such as KOH (potassium hydroxide), TMAH (tetramethylammonium hydroxide), and EDP (ethylenediamine pyrocatechol) are used. In single-crystal silicon substrate B, the nozzle tapered portion 1112 becomes a {111} plane with an extremely slow etching rate. Therefore, a nozzle tapered portion 1112 is formed with an angle of 35.3° with an axis parallel to the nozzle central axis.

[0098] As etching progresses and the nozzle tapered portion 1112 is formed to the point where it contacts the sidewall mask layer 112, the sidewall mask layer 112 controls the progress of etching and suppresses the expansion of the nozzle flow path 111. As a result, a straight communication portion 1113 is formed on the inner surface F2 along the sidewall mask layer 112 from the point where surface F1 contacts the sidewall mask layer 112.

[0099] [Effects of the invention] According to the manufacturing method of the nozzle plate 110 according to the first embodiment of the present invention as described above, the expansion of the nozzle flow path 111 by anisotropic wet etching (WE) on the single crystal silicon substrate B can be controlled by the side wall mask layer 112 formed in the slit S. That is, the shape of the cross-section of the plane perpendicular to the vertical direction of the straight communication portion 1113 can be any shape depending on the formation location of the slit S and the side wall mask layer 112.

[0100] Therefore, for example, if the cross-sectional shape of the surface perpendicular to the vertical direction of the ink flow path of the flow path plate 120 is rectangular, the slit S and side wall mask layer 112 can be formed in such a way that the length of one pair of opposing surfaces that intersect the surfaces constituting the straight communication portion 1113 with the adhesive surface (second surface) Bb is longer than the length of the other surfaces, thereby making the shape of the opening on the adhesive surface Bb side of the nozzle flow path 111 elongated. Therefore, when bonded to other plates, it is possible to prevent deterioration of injection characteristics due to mismatch in shape between the ink flow path of the other plate and the nozzle flow path 111 of the nozzle plate 110. In addition, it is possible to increase the density of nozzle openings N in the nozzle plate 110.

[0101] [Second Embodiment] Next, the manufacturing method of the nozzle plate 110 according to the second embodiment will be explained with reference to Figure 9. The manufacturing method for the nozzle plate 110 according to the second embodiment includes steps B-1 to B-6 shown in Figure 9. In the following description, detailed explanations of the parts that overlap with the manufacturing process of the nozzle plate according to the first embodiment will be omitted.

[0102] (B-1 process, B-2 process) In step B-1 (first step), a surface mask layer 113 is uniformly formed on the surface of a single-crystal silicon substrate B whose surface crystal orientation is {100} plane. After step B-1, in step B-2 (second step), an opening pattern 114 and a slit pattern 115 are simultaneously formed on the surface mask layer 113. The method for forming the opening pattern 114 and the slit pattern 115 is the same as in steps A-2 and A-5. In step B-2, by simultaneously performing patterning for the nozzle opening N and the slit S, it becomes easier to maintain the positional relationship between the nozzle opening N and the slit S.

[0103] (B-3 process) Next, in step B-3 (the third step), the slit S is formed. The method for forming the slit S is the same as in step A-3. However, when dry etching (DE2) the single-crystal silicon substrate B beneath the slit pattern 115 from the surface, there is a risk that etching may also occur on the single-crystal silicon substrate B beneath the aperture pattern 114. Therefore, it is preferable to protect the aperture pattern 114 in advance with a resist layer or the like, and remove the resist layer after the slit S is formed.

[0104] (B-4 process) Next, in step B-4 (the fourth step), a sidewall mask layer 112 is formed in the slit S. The material and formation method of the sidewall mask layer 112 are the same as in step A-4. If a mask layer is also formed on the opening pattern 114 during the formation of the sidewall mask layer 112, it can be removed by etching using an RIE apparatus or the like.

[0105] (B-5 process, B-6 process) Next, in the same way as in step A-6, as step B-5 (the fifth step), a through-hole is formed by dry etching (DE2) through the single-crystal silicon substrate B beneath the opening pattern 114. Then, in the same way as in step A-7, as step B-6 (the sixth step), the through-hole is anisotropically wet etched (WE) to form a nozzle channel 111, which consists of a nozzle opening N, a nozzle tapered portion 1112, and a straight communication portion 1113 formed on the inner surface F2 along the sidewall mask layer 112 from the point where surface F1 contacts the sidewall mask layer 112.

[0106] [Effects of the invention] In the manufacturing method of the nozzle plate 110 according to the second embodiment described above, the opening pattern 114 and the slit pattern 115 are formed simultaneously in step B-2. As a result, the nozzle opening N and the slit S are more likely to maintain symmetry, and a nozzle flow path 111 with a more stable injection angle can be formed.

[0107] [Third Embodiment] Next, a method for manufacturing a nozzle plate according to the third embodiment of the present invention and a nozzle plate manufactured thereby will be described with reference to Figure 10. The manufacturing method for the nozzle plate 110 according to the third embodiment involves performing steps A-8 and A-9 between steps A-5 and A-6 of the manufacturing method for the nozzle plate 110 according to the first embodiment. Therefore, a detailed explanation of steps A-1 to A-7 will be omitted.

[0108] (A-8 process) The main steps of the method for manufacturing a nozzle plate according to the third embodiment are shown in Figure 10. After forming the opening pattern 114 in step A-5, in step A-8 (the eighth step), the nozzle straight section 1111 is formed by dry etching (DE2) the single crystal silicon substrate B beneath the opening pattern 114 from the surface to the length of the planned nozzle straight section 1111.

[0109] (A-9 process) Next, in step A-9 (the ninth step), a nozzle mask layer 116 is formed along the inner surface of the nozzle straight section 1111. The material and formation method of the nozzle mask layer 116 are the same as those of the surface mask layer 113 in step A-1. Subsequently, the nozzle mask layer 116 formed at the bottom of the nozzle straight section 1111 is removed. The nozzle mask layer 116 at the bottom of the nozzle straight section 1111 can be removed by etching using an RIE apparatus or the like. At this time, since the nozzle mask layer 116 on the side walls of the nozzle straight section 1111 is difficult to remove by dry etching, the nozzle mask layer 116 at the bottom is etched first. Furthermore, by using low pressure and high bias as dry etching conditions, it is possible to make it more difficult for the nozzle mask layer 116 on the sidewall to be etched.

[0110] (A-6 process, A-7 process) Then, steps A-6 and A-7 are carried out in the same manner as in the first embodiment described above. In step A-6, through holes are formed in the single-crystal silicon substrate B below the nozzle straight section 1111 by dry etching (DE2) from the surface. In step A-7, the through-hole is enlarged by anisotropic wet etching (WE). At this time, the nozzle straight section 1111 is protected by the nozzle mask layer 116, which suppresses the progress of etching. As a result, the nozzle straight section 1111 remains unetched, and a nozzle channel 111 comprising the nozzle straight section 1111 is formed.

[0111] [Effects of the invention] As described above, according to the manufacturing method of the nozzle plate 110 according to the third embodiment, the nozzle mask layer 116 formed in the nozzle channel 111 suppresses the progress of etching during anisotropic wet etching (WE). Therefore, a nozzle straight section 1111 of a desired length can be formed in the nozzle channel 111.

[0112] In the third embodiment, by performing dry etching (DE2) in step A-8 while changing the processing conditions (e.g., time, power, pressure, gas flow rate, etc.), a nozzle straight section 1111 can be provided, which is composed of multiple surfaces having different angles with respect to an axis parallel to the nozzle central axis.

[0113] Furthermore, in the third embodiment, steps A-8 and A-9 were performed between steps A-5 and A-6 to form a nozzle flow path 111 with a nozzle straight section 1111, but the embodiment is not limited to this. For example, as shown in Figure 11, between steps B-4 and B-5, a B-7 step (seventh step) may be performed to form the nozzle straight section 1111 by dry etching (DE2) for the length of the planned nozzle straight section 1111, and a B-8 step (eighth step) may be performed to form a nozzle mask layer 116 along the inner surface of the nozzle straight section 1111, thereby forming a nozzle channel 111 with the nozzle straight section 1111.

[0114] Furthermore, as shown in Figure 12, step B-7 may be performed between steps B-3 and B-4. By doing so, the sidewall mask layer 112 and the nozzle mask layer 116 can be formed simultaneously in step B-4, and step B-8 can be simplified. If the shape of slit S is adversely affected during the dry etching (DE2) in step B-7, thermal oxidation of slit S to a thickness of 0.1 μm may be performed after step B-3, followed by step B-7.

[0115] Furthermore, in each of the above embodiments, the slit S is provided by dry etching (DE2) through the single-crystal silicon substrate B beneath the slit pattern 115, but this is not limited to this. The slit S may also be an elongated hole created by deep etching partway through.

[0116] Furthermore, on the side of the nozzle channel 111 where the sidewall mask layer 112 is not formed, the nozzle tapered portion 1112 and the straight connecting portion 1113 may be formed by controlling the time to stop the anisotropic wet etching (WE) midway through. Alternatively, only the nozzle tapered portion 1112 may be formed by continuing the anisotropic wet etching (WE) until the end.

[0117] Alternatively, after forming the straight communication section 1113 by anisotropic wet etching (WE), a step may be performed to remove the mask layer, including the side wall mask layer 112 and the nozzle mask layer 116 within the nozzle channel 111. For example, if the mask layer is made of SiO2, it can be removed with hydrofluoric acid. When the mask layer is removed, the portion of the sidewall mask layer 112 adjacent to the inner surface of the straight communication section 1113 is completely removed. However, only the surface portion of the sidewall mask layer 112 between the intersection of the straight communication section 1113 and the nozzle tapered section 1112 and the discharge surface Ba is removed. Therefore, even if the mask layer removal process is performed, ink will not leak out from, for example, the through-hole slit S.

[0118] Furthermore, while Figures 8 to 11 illustrate the case where the slit S is formed from the discharge surface Ba side, the case is not limited to this. The slit S may also be formed from the adhesive surface Bb side.

[0119] However, when forming the slit S by deep etching rather than through etching, it is necessary to perform dry etching (DE2) up to the area where you want to form the straight communication portion 1113, and to form the sidewall mask layer 112 up to the area where you want to stop the anisotropic wet etching (WE). This is the same regardless of whether you form the slit S from the ejection surface Ba or the bonding surface Bb of the single crystal silicon substrate B.

[0120] Furthermore, the method of forming the slit S by through-machining is not limited to a method of performing through-machining in one step from either the discharge surface Ba side or the adhesive surface Bb side. For example, as shown in Figure 13, a slit S, which is a through hole, may be formed by deep-drilling from the discharge surface Ba side and deep-drilling from the adhesive surface Bb side, and then a side wall mask layer 112 may be formed in the slit S. Also, as shown in Figure 14, the portion that will become the straight connecting portion 1113 may be machined in advance on the adhesive surface Bb side.

[0121] Furthermore, a protective film may be formed on the nozzle plate 110 for long-term use in ink ejection. In this case, after step A-7 or step B-6, a step is performed to form a protective film that covers the surface, including the inside of the nozzle channel 111.

[0122] As the protective film, materials that do not dissolve upon contact with the ink can be selected and used, such as metal oxide films (tantalum pentoxide, hafnium oxide, niobium oxide, titanium oxide, zirconium oxide, etc.), metal silicate films containing silicon in the metal oxide film (tantalum silicate, hafnium silicate, niobium silicate, titanium silicate, zirconium silicate, etc.), or the materials used to form the mask layer. Alternatively, organic films such as polyimide, polyamide, and parylene may be used as the protective film. The thickness of the protective film is not particularly limited, but can be, for example, 0.05 μm to 20 μm. [Examples]

[0123] Next, the results of evaluating preferred configurations for examples and comparative examples of the present invention will be described. The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0124] [Create a sample] A nozzle plate 110 having 1000 nozzle channels 111 formed according to each of the following examples and comparative examples was manufactured. Then, each nozzle plate 110 was ground down to a thickness of 175 μm. Then, an inkjet head 10 was formed by joining it with a piezoelectric plate 130 having a rectangular cross-section of 50 μm × 250 μm on the surface perpendicular to the vertical direction of the ink channels, as shown in Figure 15, and the inkjet head 10 was mounted in the inkjet recording device 1.

[0125] (Example 1) The nozzle channel 111 was formed by the following steps A-1 to A-7. Step A-1: ​​A surface mask layer 113 was formed on the extrusion surface Ba of a single-crystal silicon substrate B, which has a crystal orientation of {100} plane and a thickness of 400 μm, by thermal oxidation. Step A-2: A slit pattern 115 was formed on the surface mask layer 113. Step A-3: Slit S was formed by dry etching (DE2) the single-crystal silicon substrate B beneath the slit pattern 115. Step A-4: A sidewall mask layer 112 was formed in the slit S. In steps A-2 to A-4, two parallel sidewall mask layers 112 with a width of 2 μm were formed so that the cross-sectional shape of the surface perpendicular to the vertical direction of the straight connecting portion 1113 becomes an elongated shape of 50 μm × 250 μm as shown in Figure 3A. The slit S was formed using a Bosch process with a Si deep drilling apparatus. Step A-5: A 30 μm × 30 μm square-shaped opening pattern 114 was formed on the single-crystal silicon substrate B beneath the surface mask layer 113 by dry etching (DE1) from the surface using an RIE apparatus. CHF3 was used as the etching gas. Step A-6: Through holes were formed in the single-crystal silicon substrate B beneath the aperture pattern 114 by dry etching (DE2) from the surface using a Si deep etching apparatus. Step A-7: Anisotropic wet etching (WE) with a KOH solution was performed on the through-holes to form four nozzle tapered portions 1112 with {111} crystal planes and a straight connecting portion 1113 consisting of a {101} crystal plane that is continuous with the end of the nozzle tapered portion 1112 on the adhesive surface Bb side.

[0126] (Example 2) In steps A-2 to A-4, as shown in Figure 5C, the slit S and sidewall mask layer 112 were formed such that the cross-sectional shape of the surface perpendicular to the vertical direction of the straight connecting portion 1113 was a rectangle of 50 μm × 250 μm. Other conditions are the same as in Example 1.

[0127] (Example 3) Between steps A-5 and A-6, steps A-8 and A-9 described below were performed to form a nozzle flow path 111 with a nozzle straight section 1111. Other conditions were the same as in Example 2. Step A-8: The single-crystal silicon substrate B beneath the aperture pattern 114 was dry-etched from the surface (DE2) using a Si deep etching apparatus to form a nozzle straight section 1111 with a depth of 20 μm. Step A-9: After thermal oxidation of the single-crystal silicon substrate B, only the oxide film at the bottom of the nozzle straight section 1111 was removed using an RIE apparatus.

[0128] (Example 4) In steps A-2 to A-4, the single-crystal silicon substrate B was rotated by 45° with the discharge surface Ba and adhesive surface Bb fixed, and then the slit S and sidewall mask layer 112 were formed, creating a straight connecting section 1113 composed of {100} planes, as shown in Figure 5A. Other conditions are the same as in Example 2.

[0129] (Example 5) In steps A-3 and A-4, the slit S and sidewall mask layer 112 were formed such that they gradually narrow from the discharge surface Ba towards the bonding surface Bb. Specifically, during the formation of the slit S, dry etching (DE2) was performed so that the width on the discharge surface Ba side was 3 μm and the width on the bonding surface Bb side was 1 μm. Other conditions are the same as in Example 2.

[0130] (Example 6) In step A-7, the crystal plane of the straight connecting portion 1113 was not made to be either the {100} plane or the {101} plane of the single-crystal silicon substrate B, and the nozzle flow path 111 was formed such that the nozzle tapered portion 1112 was asymmetrical. Other conditions are the same as in Example 2.

[0131] (Example 7) The nozzle channel 111 was formed by the following steps B-1 to B-6. Other conditions were the same as in Example 2. Step B-1: A surface mask layer 113 was formed on the surface of the single-crystal silicon substrate B by thermal oxidation. Step B-2: The single-crystal silicon substrate B beneath the surface mask layer 113 was dry-etched (DE1) from the surface using an RIE apparatus to simultaneously form an aperture pattern 114 and a slit pattern 115. Step B-3: After covering the opening pattern 114 with a resist layer, the single-crystal silicon substrate B beneath the slit pattern 115 was dry-etched (DE2) from the surface using a Si deep etching apparatus to a depth of 180 μm to form the slit S. Then the resist layer covering the opening pattern 114 was removed. Step B-4: A sidewall mask layer 112 was formed by thermal oxidation of the slit S. At this time, an oxide film was also formed on the opening pattern 114, but it was removed by etching with an RIE apparatus. Step B-5: Through-holes were formed by dry etching (DE2) from the surface of the single-crystal silicon substrate B under the aperture pattern 114. Step B-6: Anisotropic wet etching (WE) with a KOH solution was performed on the through-holes to form four nozzle tapered portions 1112 with {111} crystal planes and a straight connecting portion 1113 consisting of a {101} crystal plane that is continuous with the end of the nozzle tapered portion 1112 on the adhesive surface Bb side.

[0132] (Example 8-1) Between steps B-4 and B-5, steps B-7 and B-8 described below were performed to form a nozzle channel 111 with a nozzle straight section 1111. Other conditions were the same as in Example 7. Step B-7: The single-crystal silicon substrate B beneath the aperture pattern 114 was subjected to a 20 μm deep etching process from the surface using a Si deep etching apparatus by dry etching (DE2) to form the nozzle straight section 1111. Step B-8: A nozzle mask layer 116 was formed on the nozzle straight section 1111 by thermal oxidation of the single-crystal silicon substrate B, and only the oxide film on the bottom surface of the nozzle straight section 1111 was removed using a RIE apparatus. (Example 8-2) By performing step B-7 between steps B-3 and B-4, and step B-8 between steps B-4 and B-5, the sidewall mask layer 112 and the nozzle mask layer 116 were formed simultaneously in step B-4, creating a nozzle channel 111 with a nozzle straight section 1111. Other conditions were the same as in Example 7. Step B-7: The single-crystal silicon substrate B beneath the aperture pattern 114 was subjected to a 20 μm deep etching process from the surface using a Si deep etching apparatus by dry etching (DE2) to form the nozzle straight section 1111. Step B-8: Using the RIE apparatus, only the oxide film on the bottom surface of the nozzle straight section 1111 was removed.

[0133] (Example 9) After step A-7, without grinding, the thickness of the single-crystal silicon substrate B was reduced from 400 μm to 175 μm by anisotropic wet etching (WE) with KOH. Then, as shown in Figure 6, the sidewall mask layer 112 adjacent to the inner surface of the straight connecting portion 1113 was removed with hydrofluoric acid. Other conditions are the same as in Example 4.

[0134] (Example 10) In steps A-2 to A-4, a sidewall mask layer 112 was formed such that the cross-sectional shape of the surface perpendicular to the vertical direction of the straight communication section 1113 was 50 μm × 59 μm. Then, a nozzle channel 111 was formed with a maximum length of tapered height h of 20 μm. Other conditions are the same as in Example 2.

[0135] (Comparative Example 1) Anisotropic wet etching (WE) was performed on a single-crystal silicon substrate B with a surface crystal orientation of {100} plane and a thickness of 400 μm to form a nozzle channel 111 such that the cross-sectional shape of the plane perpendicular to the vertical direction was a square shape of 250 μm × 250 μm. In Comparative Example 1, the thickness of the nozzle plate 110 was ground down from 400 μm to 250 μm. Figure 16A shows an enlarged plan view of the nozzle plate 110 equipped with the nozzle channel 111 in this modified example. Figure 16B shows a cross-sectional view of the inkjet head 10 perpendicular to the front-to-back direction, in which the nozzle plate 110 according to this modified example is joined to the piezoelectric plate 130 of Figure 15.

[0136] (Comparative Example 2) Anisotropic wet etching (WE) was performed on a single-crystal silicon substrate B with a surface crystal orientation of {100} plane and a thickness of 400 μm to form a nozzle channel 111 such that the cross-sectional shape of the plane perpendicular to the vertical direction is a square of 50 μm × 50 μm. Figure 17A shows an enlarged plan view of the nozzle plate 110 equipped with the nozzle channel 111 in this modified example. Figure 17B shows a cross-sectional view of the inkjet head 10 perpendicular to the front-to-back direction, in which the nozzle plate 110 according to this modified example is joined to the piezoelectric plate 130 of Figure 15. Figure 17C shows a cross-sectional view perpendicular to the left-to-right direction.

[0137] (Comparative Example 3) Anisotropic wet etching (WE) was performed on a single-crystal silicon substrate B with a surface crystal orientation of {100} plane and a thickness of 400 μm to form a nozzle channel 111 such that the cross-sectional shape of the plane perpendicular to the vertical direction is a rhombus with diagonals of 50 μm × 50 μm. Figure 18A shows an enlarged plan view of the nozzle plate 110 equipped with the nozzle channel 111 in this modified example. Figure 18B shows a cross-sectional view of the inkjet head 10 perpendicular to the front-to-back direction, in which the nozzle plate 110 according to this modified example is joined to the piezoelectric plate 130 of Figure 15. Figure 18C shows a cross-sectional view perpendicular to the left-to-right direction.

[0138] The following tests 1-2 were performed using an inkjet recording device 1 equipped with an inkjet head 10 having the nozzle plates 110 of the above Examples 1-9 and Comparative Examples 1-3.

[0139] [Test 1. Injection Angle Test] We evaluated the ±° range of the ejection angle for 1000 nozzle openings N when UV ink, heated to a viscosity of 8 cP, was ejected at a driving voltage that resulted in an average droplet velocity of approximately 6 m / s. Here, the ejection angle refers to the angle of the ejected UV ink with respect to the nozzle's central axis.

[0140] [Test 2. Upper Speed ​​Limit Test] At a drive frequency of 40 kHz, the UV ink, heated to a viscosity of 8 cP, was ejected at a speed starting from 5 m / s, and the ejection speed at which ejection defects occurred in 5 or more of the 100 nozzle openings N was measured. The ejection speed was evaluated as follows: "◎" for 11 m / s or higher, "〇" for 9 m / s or higher, "△" for 8 m / s or higher, and "×" for 7 m / s or lower.

[0141] The results of Test 1-2 are shown in Table I.

[0142] [Table 1]

[0143] In Comparative Example 1, the meniscus shape became unstable, resulting in injection defects so severe that normal injection was not possible. In Comparative Example 2, the resistance during ink ejection was high, making it easy for bubbles to form, and ink could not be ejected unless the drive voltage was increased to 30V. In Comparative Example 3, the maximum length of the taper height h was reduced, resulting in poor meniscus stability. Furthermore, the resistance during ink ejection increased, making it easier for bubbles to form, and ink could not be ejected unless the drive voltage was increased to 30V.

[0144] [evaluation] Comparing Examples 1-10 with Comparative Examples 1-3, it can be seen that by forming a sidewall mask layer 112 when manufacturing the nozzle channel 111, and matching the cross-sectional shape of the vertically perpendicular surface of the straight communication section 1113 to the cross-sectional shape of the vertically perpendicular surface of the ink channel of the piezoelectric plate 130, the meniscus shape becomes stable, and suitable injection characteristics can be obtained.

[0145] In particular, comparing Examples 3, 8-1, and 8-2 with the other examples, the formation of the nozzle straight section 1111 in the nozzle flow path 111 increased the resistance during ink ejection, resulting in a slight increase in the drive voltage. However, the maximum length of the taper height h also increased, leading to a more stable meniscus shape.

[0146] Furthermore, in both Examples 1 and 2, the cross-sectional shape of the plane perpendicular to the vertical direction of the straight communication section 1113 matches the cross-sectional shape of the plane perpendicular to the vertical direction of the ink flow path of the piezoelectric plate 130. Therefore, a suitable injection angle and meniscus stability could be achieved. In particular, in Example 2, all the ink entered the nozzle flow path 111 from the piezoelectric plate 130, resulting in less resistance and a slightly lower drive voltage.

[0147] Furthermore, comparing Examples 2 and 4 with Example 6, it can be seen that forming a straight connecting section 1113 where the crystal plane is composed of the {100} plane or {101} plane of the single-crystal silicon substrate B results in a more stable injection angle. This is because the nozzle tapered section 1112 becomes symmetrical, resulting in a symmetrical ink flow.

[0148] Furthermore, comparing Example 5 with other examples, it can be seen that forming the slit S and the sidewall mask layer 112 so that they gradually narrow from the first surface towards the second surface facing the first surface makes the injection angle more stable. This is because the sidewall mask layer 112 is more easily filled without voids, and the accuracy of the straight connecting portion 1113 can be improved.

[0149] Furthermore, comparing Example 2 with Example 7, or Example 3 with Examples 8-1 and 8-2, it can be seen that the injection angle becomes more stable by simultaneously forming the opening pattern 114 and the slit pattern 115. This is because it becomes easier to align the nozzle opening N and the slit S, and a more symmetrical nozzle flow path 111 can be formed.

[0150] Furthermore, comparing Example 4 and Example 9, it can be seen that removing the single-crystal silicon substrate B by anisotropic wet etching (WE) to reduce its thickness, or removing the sidewall mask layer 112 adjacent to the straight communication portion 1113, does not affect the injection characteristics.

[0151] Furthermore, comparing Example 8-1 and Example 8-2, it can be seen that forming the sidewall mask layer 112 and the nozzle mask layer 116 simultaneously or separately does not affect the injection characteristics.

[0152] Furthermore, comparing Example 10 with Comparative Examples 2 and 3, it can be seen that a nozzle channel 111 such that the driving voltage at which the droplet velocity averages approximately 6 m / s is 29 V or less has meniscus stability that is suitable for use as an inkjet recording device 1. As in Example 10, when the maximum length of the taper height h is 20 μm or more, the cross-sectional area of ​​the surface perpendicular to the vertical direction of the straight communication portion 1113 becomes larger than that of Comparative Examples 2 and 3, and the resistance during ink injection is reduced. [Industrial applicability]

[0153] This invention can be used in a nozzle plate, droplet ejection head, droplet ejection device, and a method for manufacturing a nozzle plate that can achieve both high density of the nozzle opening and suitable injection characteristics. [Explanation of Symbols]

[0154] 1. Droplet ejection device (inkjet recording device) 10. Droplet ejection head (inkjet head) 110 Nozzle Plate 111 Nozzle flow path 1111 Nozzle Straight Section 1112 Nozzle tapered section 1113 Straight connecting section 112 Sidewall mask layer 113 Surface mask layer 114 Opening Patterns 115 Slit Pattern 116 Nozzle mask layer B Single-crystal silicon substrate Ba discharge surface (first surface) Bb Adhesive side (2nd side) h taper height N Nozzle opening S-slit DE1, DE2 dry etching WE Anisotropic Wet Etching

Claims

1. A nozzle plate comprising a single-crystal silicon substrate with a first surface having a plurality of nozzle channels, each having a nozzle opening for ejecting liquid droplets, The nozzle flow path has a nozzle tapered section in which the flow path area, which is the cross-sectional area perpendicular to the droplet discharge direction, gradually widens from the first surface toward the second surface opposite the first surface, The nozzle tapered portion is provided with a straight connecting portion that is continuous with the end on the second surface side and has a pair of opposing surfaces that are substantially parallel, Of the sides of the surfaces constituting the straight connecting portion that intersect with the second surface, the length of the sides of one pair of opposing surfaces is longer than the length of the sides of the other surfaces. The nozzle tapered portion includes four faces whose crystal planes are approximately {111} planes. A nozzle plate in which the surfaces constituting the straight communication portion intersect with the second surface, and the crystal planes of the faces where the length of one pair of opposing faces is longer than the length of the other faces are approximately {100} faces.

2. A nozzle plate comprising a plurality of nozzle channels on the first surface of a single-crystal silicon substrate, each having a nozzle opening for ejecting liquid droplets, The nozzle flow path has a nozzle tapered section in which the flow path area, which is the cross-sectional area perpendicular to the droplet discharge direction, gradually widens from the first surface toward the second surface opposite the first surface, The nozzle tapered portion is provided with a straight connecting portion that is continuous with the end on the second surface side and has a pair of opposing surfaces that are substantially parallel, Of the sides of the surfaces constituting the straight connecting portion that intersect with the second surface, the length of the sides of one pair of opposing surfaces is longer than the length of the sides of the other surfaces. The nozzle tapered portion includes four faces whose crystal planes are approximately {111} planes. A nozzle plate having a side wall mask layer in at least a portion between the point where the nozzle tapered portion and the straight connecting portion intersect and the first surface.

3. A nozzle plate comprising a single-crystal silicon substrate with a first surface having a plurality of nozzle channels, each having a nozzle opening for ejecting liquid droplets, The nozzle flow path has a nozzle tapered section in which the flow path area, which is the cross-sectional area perpendicular to the droplet discharge direction, gradually widens from the first surface toward the second surface opposite the first surface, The nozzle tapered portion is provided with a straight connecting portion that is continuous with the end on the second surface side and has a pair of opposing surfaces that are substantially parallel, Of the sides of the surfaces constituting the straight connecting portion that intersect with the second surface, the length of the sides of one pair of opposing surfaces is longer than the length of the sides of the other surfaces. The nozzle tapered portion is composed of four faces with approximately {111} crystal planes. A nozzle plate in which the surfaces constituting the straight communication portion intersect with the second surface, and the crystal planes of the faces where the length of one pair of opposing faces is longer than the length of the other faces are approximately {100} faces.

4. A nozzle plate comprising a plurality of nozzle channels on the first surface of a single-crystal silicon substrate, each having a nozzle opening for ejecting liquid droplets, The nozzle flow path has a nozzle tapered section in which the flow path area, which is the cross-sectional area perpendicular to the droplet discharge direction, gradually widens from the first surface toward the second surface opposite the first surface, The nozzle tapered portion is provided with a straight connecting portion that is continuous with the end on the second surface side and has a pair of opposing surfaces that are substantially parallel, Of the sides of the surfaces constituting the straight connecting portion that intersect with the second surface, the length of the sides of one pair of opposing surfaces is longer than the length of the sides of the other surfaces. The nozzle tapered portion is composed of four faces with approximately {111} crystal planes. A nozzle plate having a side wall mask layer in at least a portion between the point where the nozzle tapered portion and the straight connecting portion intersect and the first surface.

5. The nozzle plate according to claim 2 or 4, wherein, among the edges of the surface constituting the straight communication portion that intersect with the second surface, the crystal plane of the pair of opposing surfaces whose edge length is longer than the edge length of the other surface is composed of approximately {101} surfaces.

6. A nozzle plate comprising a single-crystal silicon substrate with a first surface having a plurality of nozzle channels, each having a nozzle opening for ejecting liquid droplets, The nozzle flow path has a nozzle tapered section in which the flow path area, which is the cross-sectional area perpendicular to the droplet discharge direction, gradually widens from the first surface toward the second surface opposite the first surface, The nozzle tapered portion includes a straight connecting portion that extends from the end on the second surface side to the second surface, A side wall mask layer is provided in at least a portion between the point where the nozzle tapered portion and the straight connecting portion intersect and the first surface. The nozzle tapered portion is a nozzle plate that includes four faces with approximately {111} crystal planes.

7. A nozzle plate comprising a single-crystal silicon substrate with a first surface having a plurality of nozzle channels, each having a nozzle opening for ejecting liquid droplets, The nozzle flow path has a nozzle tapered section in which the flow path area, which is the cross-sectional area perpendicular to the droplet discharge direction, gradually widens from the first surface toward the second surface opposite the first surface, The nozzle tapered portion includes a straight connecting portion that extends from the end on the second surface side to the second surface, A side wall mask layer is provided in at least a portion between the point where the nozzle tapered portion and the straight connecting portion intersect and the first surface. The nozzle tapered portion is a nozzle plate composed of four faces with approximately {111} crystal planes.

8. The nozzle plate according to claim 6 or 7, wherein the sidewall mask layer has a shape that gradually narrows from the first surface to the second surface or from the second surface to the first surface.

9. The nozzle plate according to any one of claims 1 to 4, 6, or 7, wherein the nozzle flow path comprises a nozzle straight portion continuous with the end of the first surface side of the nozzle tapered portion.

10. The nozzle plate according to claim 9, wherein the nozzle straight portion has a maximum flow path area that is less than or equal to the flow path area at the end of the first surface side of the nozzle tapered portion.

11. The nozzle plate according to any one of claims 1 to 4, 6, or 7, wherein the maximum length of the taper height from the first surface to the end of the nozzle taper portion on the second surface side is 20 μm or more.

12. A droplet dispensing head mounted on a droplet dispensing device, A droplet dispensing head comprising a nozzle plate according to any one of claims 1 to 4, 6, or 7.

13. A droplet dispensing device, A droplet dispensing device comprising the droplet dispensing head described in claim 12.

14. A method for manufacturing a nozzle plate of a droplet dispensing head, A first step is to form a surface mask layer on the first surface of a single-crystal silicon substrate whose surface crystal orientation is the {100} plane, The second step involves forming a slit pattern on the surface mask layer, A third step involves forming the slits in the single-crystal silicon substrate located beneath the slit pattern by dry etching from the surface, either through-etching or partially deep-etching; A fourth step involves forming a side wall mask layer in the aforementioned slit, A fifth step involves forming a circular or polygonal opening pattern, which will serve as a nozzle opening, on the surface mask layer. A sixth step involves forming through-holes in the single-crystal silicon substrate located beneath the aforementioned aperture pattern by dry etching from the surface, A method for manufacturing a nozzle plate, comprising a seventh step of enlarging the through-hole by anisotropic wet etching of the single-crystal silicon substrate, thereby forming a nozzle tapered portion and a straight connecting portion continuous with the end of the nozzle tapered portion on the second surface side facing the first surface.

15. The eighth step involves forming a nozzle straight section by dry etching partway through the single-crystal silicon substrate located beneath the opening pattern, A method for manufacturing a nozzle plate according to claim 14, wherein a ninth step of forming a nozzle mask layer along the inner surface of the nozzle straight portion is performed between the fifth step and the sixth step.

16. A method for manufacturing a nozzle plate of a droplet dispensing head, A first step is to form a surface mask layer on the first surface of a single-crystal silicon substrate whose surface crystal orientation is the {100} plane, A second step involves simultaneously forming a circular or polygonal opening pattern, which will serve as a nozzle opening, and a slit pattern, which will serve as a slit, on the surface mask layer. A third step involves forming a slit in the single-crystal silicon substrate located beneath the slit pattern by dry etching from the surface, either through-etching or partially deep-etching. A fourth step involves forming a side wall mask layer in the slit, A fifth step involves forming through-holes in the single-crystal silicon substrate located beneath the aforementioned opening pattern by dry etching from the surface, A method for manufacturing a nozzle plate, comprising a sixth step of enlarging the through-hole by anisotropic wet etching of the single-crystal silicon substrate, thereby forming a nozzle tapered portion and a straight connecting portion continuous with the end of the nozzle tapered portion on the second surface side facing the first surface.

17. A seventh step involves forming a nozzle straight section by dry etching partway through the single-crystal silicon substrate located beneath the opening pattern, A method for manufacturing a nozzle plate according to claim 16, wherein an eighth step of forming a nozzle mask layer along the inner surface of the nozzle straight portion is performed between the third step and the fifth step.

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