Manufacturing method and liquid ejection head

Abstract

To suppress variation in shape among a plurality of channels.SOLUTION: A manufacturing method for forming a flow path in a liquid ejection head includes a first etching step of forming, in a substrate including a first layer and a second layer that are made of silicon, an insulating layer that is located between the first layer and the second layer and has an insulating property, and a void portion in the insulating layer, a through hole that penetrates the second layer from the first layer through the void portion.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to a manufacturing method and a liquid ejection head. [Background technology]

[0002] A liquid ejection head, such as an inkjet head, is generally provided with a flow path for a liquid such as ink. For example, Patent Document 1 describes a method for forming a continuous substrate by etching a silicon single crystal substrate from both sides thereof. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-103515 Summary of the Invention [Problem to be solved by the invention]

[0004] When forming multiple flow paths on one substrate, it is preferable that the shapes of the multiple flow paths are the same in order to make the discharge performance of the multiple flow paths, such as flow rate or inertance, uniform. However, with the method described in Patent Document 1, it is difficult to suppress the variation in shape among the multiple flow paths. [Means for solving the problem]

[0005] In order to solve the above problems, a manufacturing method according to a preferred embodiment of the present disclosure is a manufacturing method for forming a flow path in a liquid ejection head, which includes a first etching step of forming a through hole that passes from the first layer through the void and penetrates the second layer in a substrate having a first layer and a second layer made of silicon, and an insulating layer that is located between the first layer and the second layer and has insulating properties, and in which the insulating layer has a void.

[0006] A liquid ejection head according to a preferred embodiment of the present disclosure comprises a substrate having a first layer and a second layer made of silicon, and an insulating layer located between the first layer and the second layer and having insulating properties, and the substrate is provided with a first flow path made of a hole penetrating the first layer, and a second flow path connected to the first flow path, which penetrates the second layer and the insulating layer and includes a recess with the first layer as its bottom surface. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of the configuration of a liquid ejection device. [Figure 2] FIG. 1 is an exploded perspective view of a liquid ejection head according to a first embodiment. [Figure 3] 1 is a cross-sectional view of a liquid ejection head according to a first embodiment. [Figure 4] FIG. 2 is an explanatory diagram of a flow path of the liquid ejection head according to the first embodiment. [Figure 5] FIG. 2 is a plan view of a communication substrate in the first embodiment. [Figure 6] 1 is a diagram showing a flow of a manufacturing method according to a first embodiment. [Figure 7] 3A to 3C are explanatory views of a substrate preparation step, a mask formation step, and a pilot hole formation step in the first embodiment. [Figure 8] FIG. 4 is an explanatory diagram of a protective film in a mask formation step in the first embodiment. [Figure 9] 5A to 5C are explanatory views of a silicon etching step and an oxide film etching step in the first embodiment. [Figure 10] FIG. 10 is a diagram showing the flow of a manufacturing method according to a second embodiment. [Figure 11] 10A to 10C are explanatory views of a substrate preparation step, a mask formation step, and a pilot hole formation step in the second embodiment. [Figure 12] 10A to 10C are explanatory views of a silicon etching step and an oxide film etching step in the second embodiment. [Figure 13] FIG. 10 is an explanatory diagram of a flow path of a liquid ejection head according to a third embodiment. [Figure 14]FIG. 11 is a plan view of a communication substrate in a third embodiment. [Figure 15] 10A and 10B are explanatory views of a protective film in a mask forming step in the third embodiment. [Figure 16] FIG. 10 is an explanatory view of a silicon etching step in the third embodiment. [Figure 17] FIG. 10 is an explanatory diagram of a flow path of a liquid ejection head according to a fourth embodiment. [Figure 18] FIG. 10 is a plan view of a communication substrate in a fourth embodiment. [Figure 19] 10A and 10B are explanatory views of a protective film in a mask formation step in the fourth embodiment. [Figure 20] FIG. 10 is an explanatory view of a silicon etching step in the fourth embodiment. [Figure 21] FIG. 10 is an explanatory diagram of a flow path of a liquid ejection head according to a fifth embodiment. [Figure 22] FIG. 11 is a plan view of a communication substrate in the fifth embodiment. [Figure 23] 13A and 13B are explanatory views of a protective film in a mask forming step in the fifth embodiment. [Figure 24] FIG. 13 is an explanatory view of a silicon etching step in the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments of the present disclosure will be described below with reference to the accompanying drawings. Note that the dimensions and scale of each part in the drawings may differ from the actual dimensions and are shown schematically to facilitate understanding. Furthermore, the scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0009] For convenience, the following description will use the mutually intersecting X-axis, Y-axis, and Z-axis as appropriate. In the following, one direction along the X-axis is the X1 direction, and the direction opposite the X1 direction is the X2 direction. Similarly, the opposite directions along the Y-axis are the Y1 direction and the Y2 direction. Furthermore, the opposite directions along the Z-axis are the Z1 direction and the Z2 direction. In the following, viewing in the Z1 direction or the Z2 direction may be referred to as "planar view."

[0010] Typically, the Z axis is a vertical axis, and the Z2 direction corresponds to the downward direction in the vertical direction. However, the Z axis does not have to be a vertical axis. Furthermore, the X axis, Y axis, and Z axis are typically perpendicular to each other, but are not limited to this. For example, they may intersect at an angle between 80° and 100°.

[0011] A: First embodiment A1: Overall configuration of the liquid ejection device 1 is a schematic diagram showing an example of the configuration of a liquid ejection device 100. The liquid ejection device 100 is an inkjet printing device that ejects ink, which is an example of a "liquid," in the form of droplets toward a recording medium M. The recording medium M is, for example, printing paper. Note that the recording medium M is not limited to printing paper, and may be a printing target made of any material, such as a resin film or fabric.

[0012] As shown in FIG. 1, the liquid ejection device 100 includes a liquid container 10, a control module 20, a transport mechanism 30, a moving mechanism 40, and a plurality of liquid ejection heads 50.

[0013] The liquid container 10 stores ink. Specific examples of the liquid container 10 include a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack made of flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the liquid container 10 is arbitrary.

[0014] The control module 20 controls the operation of each element of the liquid ejection device 100. The control module 20 includes, for example, a processing circuit such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and a storage circuit such as a semiconductor memory. Here, the control module 20 outputs a drive signal Com for driving the liquid ejection head 50, and a control signal SI for controlling the driving of the liquid ejection head 50.

[0015] The transport mechanism 30 transports the recording medium M along the Y axis under the control of the control module 20.

[0016] The movement mechanism 40 reciprocates the liquid ejection head 50 along the X axis under the control of the control module 20. The movement mechanism 40 has a substantially box-shaped transport body 41 called a carriage that houses the liquid ejection head 50, and an endless transport belt 42 to which the transport body 41 is fixed. The number of liquid ejection heads 50 mounted on the transport body 41 is not limited to one, and may be multiple. In addition to the liquid ejection head 50, the transport body 41 may also be equipped with the aforementioned liquid container 10.

[0017] Each of the plurality of liquid ejection heads 50 ejects ink supplied from the liquid container 10 from each of the plurality of nozzles N onto the recording medium M under the control of the control module 20. This ejection is performed in parallel with the transport of the recording medium M by the transport mechanism 30 and the reciprocating movement of the liquid ejection head 50 by the movement mechanism 40, thereby forming an ink image on the surface of the recording medium M.

[0018] In the example shown in Fig. 1, the number of liquid ejection heads 50 is four. The number of liquid ejection heads 50 is not limited to the example shown in Fig. 1 and may be any number, and may be one, or a plurality of three or less, or five or more. The arrangement of the plurality of liquid ejection heads 50 is also not limited to the example shown in Fig. 1 and may be any arrangement.

[0019] A2: Liquid ejection head Fig. 2 is an exploded perspective view of the liquid ejection head 50 according to the first embodiment. Fig. 3 is a cross-sectional view of the liquid ejection head 50 according to the first embodiment. Fig. 3 is a cross-sectional view taken along line AA in Fig. 2. An example of the configuration of the liquid ejection head 50 will now be described.

[0020] As shown in FIGS. 2 and 3, the liquid ejection head 50 has a plurality of nozzles N arranged in a direction along the Y axis.

[0021] The multiple nozzles N of the liquid ejection head 50 are divided into a first nozzle row Ln1 and a second nozzle row Ln2 that are arranged at intervals along the X-axis. Each of the first nozzle row Ln1 and the second nozzle row Ln2 is a collection of multiple nozzles N that are linearly arranged along the Y-axis.

[0022] The liquid ejection heads 50 are configured to be substantially symmetrical with respect to each other in the direction along the X-axis. However, the positions of the multiple nozzles N of the first nozzle row Ln1 and the multiple nozzles N of the second nozzle row Ln2 in the direction along the Y-axis may or may not match. 2 and 3 illustrate a configuration in which the positions of the multiple nozzles N of the first nozzle row Ln1 and the multiple nozzles N of the second nozzle row Ln2 in the direction along the Y-axis match each other.

[0023] 2 and 3, the liquid ejection head 50 has a communication substrate 510, a pressure chamber substrate 520, a nozzle plate 530, a vibration absorber 540, a vibration plate 550, a plurality of piezoelectric elements 560, a protective substrate 570, a case 580, and a wiring substrate 590. The communication substrate 510 is an example of a "substrate."

[0024] The communication substrate 510 and the pressure chamber substrate 520 are stacked in this order in the Z1 direction to form a flow path for supplying ink to the multiple nozzles N. A vibration plate 550, multiple piezoelectric elements 560, a protective substrate 570, a case 580, a wiring substrate 590, and a drive circuit 600 are installed in an area positioned in the Z1 direction from the stack consisting of the communication substrate 510 and the pressure chamber substrate 520. On the other hand, a nozzle plate 530 and a vibration absorber 540 are installed in an area positioned in the Z2 direction from the stack. Each element of the liquid ejection head 50 is roughly a plate-like member elongated in the Y direction and is joined to each other, for example, by an adhesive. Each element of the liquid ejection head 50 will be described in order below.

[0025] The nozzle plate 530 is a plate-like member provided with a plurality of nozzles N of each of the first nozzle row Ln1 and the second nozzle row Ln2. Each of the plurality of nozzles N is a through-hole that allows ink to pass through. Here, the surface of the nozzle plate 530 facing the Z2 direction is the nozzle surface FN. The nozzle plate 530 is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing techniques such as dry etching or wet etching. However, other known methods and materials may also be used as appropriate to manufacture the nozzle plate 530. Furthermore, the cross-sectional shape of the nozzle N is typically circular, but is not limited thereto and may be a non-circular shape such as a polygonal or elliptical shape.

[0026] The communication substrate 510 is provided with a flow path R1, a plurality of supply flow paths Ra, and a plurality of communication flow paths Na for each of the first nozzle row Ln1 and the second nozzle row Ln2. The supply flow path Ra is an example of a "first flow path." The flow path R1 is an example of a "second flow path" and is connected to the supply flow path Ra. The flow path R1 is a flow path provided in common to a plurality of nozzles N, communicates with the plurality of nozzles N, and is a flow path upstream of the nozzles N, and is configured as an elongated hole extending in the direction along the Y axis in a plan view seen in the direction along the Z axis. Each of the supply flow path Ra and the communication flow path Na is a flow path configured as a through-hole formed for each nozzle N. Each supply flow path Ra is connected to the flow path R1.

[0027] The continuous substrate 510 has a first layer 511, a second layer 512, and an insulating layer 513. These are stacked in the order of the first layer 511, the insulating layer 513, and the second layer 512 in the Z2 direction. That is, the first layer 511 is disposed in the Z1 direction relative to the insulating layer 513, while the second layer 512 is disposed in the Z2 direction. In this manner, the insulating layer 513 is located between the first layer 511 and the second layer 512. The continuous substrate 510 is manufactured, for example, by processing an SOI (Silicon on Insulator) substrate using semiconductor manufacturing technology, as will be described in detail later.

[0028] The pressure chamber substrate 520 is a plate-like member in which a plurality of pressure chambers C, called cavities, are provided for each of the first nozzle row Ln1 and the second nozzle row Ln2. The pressure chambers C are arranged in a direction along the Y axis. Each pressure chamber C is formed for each nozzle N and is an elongated space extending in a direction along the X axis in a plan view.

[0029] The pressure chamber substrate 520 is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing technology, for example, in the same way as the nozzle plate 530. However, other known methods and materials may also be used appropriately to manufacture the pressure chamber substrate 520.

[0030] The pressure chambers C are located between the communication substrate 510 and the vibration plate 550. A plurality of pressure chambers C are arranged in the direction along the Y axis for each of the first nozzle row Ln1 and the second nozzle row Ln2. The pressure chambers C are also in communication with the communication flow path Na and the supply flow path Ra. Therefore, the pressure chambers C are in communication with the nozzles N via the communication flow path Na, and are in communication with the flow path R1 via the supply flow path Ra.

[0031] A diaphragm 550 is disposed on the surface of the pressure chamber substrate 520 facing the Z1 direction. The diaphragm 550 is a plate-like member that can vibrate elastically. Although not shown, the diaphragm 550 has, for example, an elastic film and an insulating film, which are laminated in this order in the Z1 direction. The elastic film is made of, for example, silicon oxide (SiO2), and is formed by thermally oxidizing one surface of a silicon single crystal substrate. The insulating film is made of, for example, zirconium oxide (ZrO2), and is formed by forming a zirconium layer by sputtering and then thermally oxidizing the layer.

[0032] Note that diaphragm 550 is not limited to the configuration of a laminate of the elastic film and insulating film described above, and may be configured, for example, as a single layer, or as three or more layers. Furthermore, the material of each layer constituting diaphragm 550 is not limited to the materials described above, and may be, for example, silicon, silicon nitride, or the like.

[0033] On the surface of the vibration plate 550 facing the Z1 direction, a plurality of piezoelectric elements 560 corresponding to the nozzles N of each of the first nozzle row Ln1 and the second nozzle row Ln2 are arranged. Each piezoelectric element 560 is a passive element that deforms when supplied with a potential according to the drive signal Com, and causes pressure fluctuations in the ink within the pressure chambers C. Each piezoelectric element 560 has an elongated shape extending in the direction along the X-axis in a plan view. The plurality of piezoelectric elements 560 are arranged in the direction along the Y-axis so as to correspond to the plurality of pressure chambers C. The piezoelectric elements 560 overlap the pressure chambers C in a plan view.

[0034] Although not shown, each piezoelectric element 560 has a first electrode, a piezoelectric body, and a second electrode, which are stacked in this order in the Z1 direction. The first electrodes are individual electrodes spaced apart from one another for each piezoelectric element 560. A potential corresponding to a drive signal Com is supplied to the first electrode. The second electrode is a strip-shaped common electrode extending continuously along the Y-axis across the plurality of piezoelectric elements 560. A constant potential, for example, is supplied to the second electrode. Examples of metal materials for these electrodes include platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), and copper (Cu). One of these metals can be used alone, or two or more can be combined in the form of an alloy or laminate. The piezoelectric body is made of a piezoelectric material such as lead zirconate titanate (Pb(Zr,Ti)O3). In the piezoelectric element 560, when a voltage is applied between the first electrode and the second electrode, the piezoelectric body is deformed by the inverse piezoelectric effect. When the vibration plate 550 vibrates in conjunction with this deformation, the pressure in the pressure chamber C fluctuates, causing ink to be ejected from the nozzle N.

[0035] Protective substrate 570 is a plate-like member placed on the surface of diaphragm 550 facing the Z1 direction, and protects multiple piezoelectric elements 560 and reinforces the mechanical strength of diaphragm 550. Here, multiple piezoelectric elements 560 are housed in space S between protective substrate 570 and diaphragm 550. Protective substrate 570 is made of, for example, a resin material or silicon.

[0036] The case 580 is a case for storing ink to be supplied to the multiple pressure chambers C. The case 580 is made of, for example, a resin material. The case 580 is provided with a flow path R2 for each of the first nozzle row Ln1 and the second nozzle row Ln2. The flow path R2 is a space connected to the aforementioned flow path R1 and is formed as an elongated hole extending in the direction along the Y axis in a plan view seen in the direction along the Z axis. The flow path R2 communicates with the nozzles N and, together with the flow path R1, functions as a reservoir R for storing ink to be supplied to the multiple pressure chambers C. The case 580 is provided with an inlet HL for supplying ink to each reservoir R. The ink in each reservoir R is supplied to the pressure chambers C via each supply flow path Ra. Note that the position and number of the inlet HL for each reservoir R are not limited to the examples shown in FIGS. 2 and 3 and may be any.

[0037] The vibration absorber 540, also called a compliance substrate, is a flexible resin film that forms the wall surface of the reservoir R and absorbs pressure fluctuations of the ink inside the reservoir R. The vibration absorber 540 may also be a flexible thin metal plate. The surface of the vibration absorber 540 facing the Z1 direction is bonded to the communication substrate 510 with an adhesive or the like.

[0038] The wiring board 590 is mounted on the surface of the diaphragm 550 facing the Z1 direction and is a mounting component for electrically connecting the control module 20 and the liquid ejection head 50. The wiring board 590 is a flexible wiring board such as a COF (Chip On Film), an FPC (Flexible Printed Circuit), or an FFC (Flexible Flat Cable). A drive circuit 600 is mounted on the wiring board 590 of this embodiment. Under the control of the control module 20, the drive circuit 600 switches whether or not to supply pulses included in the drive signal Com output from the control module 20 to each of the multiple piezoelectric elements 560 of the liquid ejection head 50. Note that the wiring board 590 may be a rigid board. In this case, the drive circuit 600 is mounted on the rigid board or on a flexible board connected to the rigid board.

[0039] A3: Flow path of liquid ejection head Fig. 4 is an explanatory diagram of the flow paths of the liquid ejection head 50 according to the first embodiment. Fig. 5 is a plan view of the communication substrate 510 according to the first embodiment. For ease of explanation, narrowed portions T1a, T1b, T1c, T2a, T2b, and T2c, which will be described later, are omitted from Fig. 5.

[0040] As shown in FIG. 4, the communication flow path Na is made up of a hole 511a, a hole 512a, and a gap portion 513a.

[0041] Hole 511a is a through-hole that penetrates first layer 511 in the thickness direction. In the example shown in Fig. 4, hole 511a has a narrowed portion T1a. Narrowed portion T1a is shaped to narrow the width of hole 511a toward the end of hole 511a in the Z1 direction. However, the width of hole 511a excluding narrowed portion T1a is constant throughout the entire area in the direction along the Z axis.

[0042] Hole 512a is a through-hole that penetrates second layer 512 in the thickness direction. In the example shown in Fig. 4, hole 512a has narrowed portion T2a. Narrowed portion T2a is shaped to narrow the width of hole 512a toward the end of hole 512a in the Z2 direction. However, the width of hole 512a excluding narrowed portion T2a is constant throughout the entire area in the direction along the Z axis.

[0043] The void portion 513a is a through-hole that penetrates the insulating layer 513 in the thickness direction.

[0044] As shown in Fig. 5, the shapes and sizes of hole 511a, hole 512a, and void 513a are substantially the same as one another when viewed in the direction along the Z axis. In the example shown in Fig. 5, hole 511a, hole 512a, and void 513a each have a parallelogram shape in plan view. Although not shown in Fig. 5, hole 511a has narrowed portion T1a, so the shape of hole 511a in plan view is not a strict parallelogram but is roughly a parallelogram. Similarly, hole 512a has narrowed portion T2a, so the shape of hole 512a in plan view is not a strict parallelogram but is roughly a parallelogram.

[0045] As shown in FIG. 4, the supply flow path Ra is formed by a hole 511b.

[0046] Hole 511b is a through-hole that penetrates first layer 511 in the thickness direction. In the example shown in Fig. 4, hole 511b has narrowed portion T1b. Narrowed portion T1b is shaped to narrow the width of hole 511b toward the end of hole 511b in the Z1 direction. However, the width of hole 511b excluding narrowed portion T1b is constant throughout the entire area in the direction along the Z axis.

[0047] In the example shown in Fig. 5, the shape of hole 511b in a plan view is a parallelogram. Note that although not shown in Fig. 5, hole 511b has narrowed portion T1b, so the shape of hole 511b in a plan view is not a strict parallelogram but is roughly a parallelogram.

[0048] As shown in FIG. 4, the flow path R1 is composed of a hole 511c, a hole 512d, and a gap portion 513d.

[0049] Hole 511c is a through-hole that penetrates first layer 511 in the thickness direction. In the example shown in Fig. 4, hole 511c has narrowed portion T1c. Narrowed portion T1c is shaped to narrow the width of hole 511c toward the end of hole 511c in the Z1 direction. However, the width of hole 511c excluding narrowed portion T1c is constant throughout the entire area in the direction along the Z axis.

[0050] Hole 512d is a through-hole that penetrates second layer 512 in the thickness direction. In the example shown in Fig. 4, hole 512d has narrowed portions T2b and T2c. Narrowed portions T2b and T2c are shaped to narrow the width of hole 512d toward the ends of hole 512d in the Z2 direction. However, the width of hole 512d excluding narrowed portions T2b and T2c is constant throughout the entire area in the direction along the Z axis.

[0051] The void portion 513d is a through-hole that penetrates the insulating layer 513 in the thickness direction.

[0052] 5, hole 512d and void 513d each encompass hole 511c when viewed in the direction along the Z axis. Note that the planar shapes of hole 512d and void 513d are not limited to the example shown in FIG.

[0053] As described above, supply flow path Ra is formed by hole 511b penetrating first layer 511, while flow path R1 includes a recess that penetrates second layer 512 and insulating layer 513 and has first layer 511 as its bottom surface. Here, as will be described later, first layer 511 and second layer 512 are each formed by silicon, while insulating layer 513 has insulating properties. Here, as will be described later, formation of a sagging shape between hole 511b constituting supply flow path Ra and the bottom surface of the recess included in flow path R1 is suppressed.

[0054] A4: Manufacturing method 6 is a diagram showing the flow of the manufacturing method according to the first embodiment. As shown in FIG. 6, the manufacturing method according to this embodiment includes a substrate preparation step ST1, a mask formation step ST2, a pilot hole formation step ST3, a silicon etching step ST4, an oxide film etching step ST5, a silicon etching step ST6, and an oxide film etching step ST7, in this order. The silicon etching step ST4 is an example of a "first etching step." The oxide film etching step ST7 is an example of a "second etching step."

[0055] Hereinafter, the steps of the manufacturing method of this embodiment will be described in order, taking the case of manufacturing the communication substrate 510 as an example.

[0056] Fig. 7 is an explanatory diagram of the substrate preparation step ST1, the mask formation step ST2, and the pilot hole formation step ST3 in the first embodiment. Fig. 8 is an explanatory diagram of the protective films M1A and M2A in the mask formation step ST2 in the first embodiment.

[0057] 7, first, in a substrate preparation step ST1, a substrate 5 is prepared. The substrate 5 is a substrate for forming a continuous substrate 510. Specifically, the substrate 5 is an SOI substrate having a cavity structure, a so-called cavity SOI substrate, and has a first layer 511, a second layer 512, and an insulating layer 513. The substrate 5 may be a wafer for forming a plurality of continuous substrates 510.

[0058] Each of the first layer 511 and the second layer 512 is made of silicon. In this embodiment, the first layer 511 and the second layer 512 are each a (110) silicon single crystal substrate. Note that each of the first layer 511 and the second layer 512 is not limited to being a (110) silicon single crystal substrate, and may be, for example, a single crystal silicon substrate other than a (110) silicon substrate.

[0059] The insulating layer 513 is located between the first layer 511 and the second layer 512, has insulating properties, and is made of, for example, silicon oxide (SiO 2 ). The insulating layer 513 has gaps 513a, 513b, and 513c.

[0060] As described above, the void 513a is a through-hole that penetrates the insulating layer 513 in the thickness direction, and is disposed at a position where the communication flow path Na is to be formed in plan view. In this embodiment, the size and shape of the void 513a are equal to the size and shape of the communication flow path Na to be formed in plan view, and form a parallelogram.

[0061] As described above, the void 513b is a through-hole that penetrates the insulating layer 513 in the thickness direction, and is disposed at a position where the supply flow path Ra is to be formed in plan view. In this embodiment, the size and shape of the void 513b are equal to the size and shape of the supply flow path Ra to be formed in plan view, and form a parallelogram.

[0062] As described above, the void portion 513c is a through-hole that penetrates the insulating layer 513 in the thickness direction, and is arranged at a position where the hole 511c is to be formed in plan view. In this embodiment, the size and shape of the void portion 513c are approximately equal to the size and shape of the hole 511c to be formed in plan view.

[0063] After the substrate preparation step ST1, protective films M1A and M2A are formed on the substrate 5 in the mask formation step ST2. As a result, protective films M1A and M2A are formed on the substrate 5 in the silicon etching step ST4. Each of the protective films M1A and M2A is an etching mask used in the silicon etching step ST4. The protective films M1A and M2A are made of, for example, a silicon oxide film and are formed by thermal oxidation of silicon. The protective film M1A is provided on the surface of the first layer 511, and openings O1a, O1b, and O1c are formed in the protective film M1A to expose the surface of the first layer 511. The protective film M2A is provided on the surface of the second layer 512, and openings O2a, O2b, and O2c are formed in the protective film M2A to expose the surface of the second layer 512. In this embodiment, the protective film M2A has a thin film portion MT that is thinner than other portions. The thin film portion MT is provided over a range corresponding to the region where the flow path R1 and the first layer 511 overlap each other in a plan view of the liquid ejection head 50, and disappears when removed in the oxide film etching step ST.

[0064] As shown in FIG. 8, when the substrate 5 is viewed from the direction from the first layer 511 toward the second layer 512, each of the openings O1a and O2a is contained within the void 513a. This allows wet etching using the protective films M1A and M2A as a mask to define the size and shape of the through-hole H1 based on the size and shape of the void 513a. In the example shown in FIG. 8, the planar shape of each of the openings O1a and O2a is a parallelogram similar to the planar shape of the void 513a. The planar shapes of each of the openings O1a and O2a are not limited to the example shown in FIG. 8 and may be, for example, different from the planar shape of the void 513a.

[0065] When substrate 5 is viewed from the direction from first layer 511 toward second layer 512, void 513a before silicon etching step ST4 has the same shape as through hole H1 formed in silicon etching step ST4. This makes it possible to prevent narrowed portions from being formed between void 513a and first layer 511 and second layer 512 in silicon etching step ST4.

[0066] When the substrate 5 is viewed from the direction from the first layer 511 toward the second layer 512, each of the openings O1b and O2b is contained within the void 513b. This allows the size and shape of the through-hole H2 to be determined by the size and shape of the void 513b by performing wet etching using the protective films M1A and M2A as a mask. In the example shown in FIG. 8, the planar shape of each of the openings O1b and O2b is a parallelogram similar to the planar shape of the void 513b. Note that the planar shapes of each of the openings O1b and O2b are not limited to the example shown in FIG. 8 and may be, for example, different from the planar shape of the void 513b.

[0067] When substrate 5 is viewed from the direction from first layer 511 toward second layer 512, void 513b before silicon etching step ST4 has the same shape as through hole H2 formed in silicon etching step ST4. This makes it possible to prevent narrowed portions from being formed between void 513b and first layer 511 and second layer 512 in silicon etching step ST4.

[0068] When the substrate 5 is viewed from the direction from the first layer 511 toward the second layer 512, each of the openings O1c and O2c is contained within the void 513c. This allows the size and shape of the through-hole H3 to be determined by the size and shape of the void 513c by performing wet etching using the protective films M1A and M2A as a mask. In the example shown in FIG. 8, the planar shapes of each of the openings O1c and O2c are shapes that conform to the planar shape of the void 513c. Note that the planar shapes of each of the openings O1c and O2c are not limited to the example shown in FIG. 8.

[0069] When substrate 5 is viewed from the direction from first layer 511 toward second layer 512, void 513c before silicon etching step ST4 has the same shape as through hole H3 formed in silicon etching step ST4. This makes it possible to prevent narrowed portions from being formed between void 513c and first layer 511 and second layer 512 in silicon etching step ST4.

[0070] After the mask formation step ST2, as shown in FIG. 7, in a pre-hole formation step ST3, pre-holes H1a, H1b, H2a, and H2b are formed in the substrate 5. The pre-holes H1a and H2a are pre-holes for a through-hole H1, which will be described later, and are provided at positions where the through-hole H1 will be formed. The widths of the pre-holes H1a and H2a are smaller than the width of the through-hole H1. The pre-holes H1b and H2b are pre-holes for a through-hole H2, which will be described later, and are provided at positions where the through-hole H2 will be formed. The widths of the pre-holes H1b and H2b are smaller than the width of the through-hole H2.

[0071] The method for forming the pilot holes H1a, H1b, H2a, and H2b is not particularly limited, but examples thereof include laser processing and dry etching such as ICP (Inductively Coupled Plasma), and one of these can be used alone or two or more can be used in combination.

[0072] In this way, by forming the pilot holes H1a and H2a in the pilot hole forming step ST3 before the silicon etching step ST4, it is possible to reduce misalignment of the through hole H1. Furthermore, the through hole H1 with a high aspect ratio can be formed by anisotropic etching. Similarly, by forming the pilot holes H1b and H2b in the pilot hole forming step ST3 before the silicon etching step ST4, it is possible to reduce misalignment of the through hole H2. Furthermore, the through hole H2 with a high aspect ratio can be formed by anisotropic etching.

[0073] FIG. 9 is an explanatory diagram of the silicon etching steps ST4 and ST6 and the oxide film etching steps ST5 and ST7 in the first embodiment.

[0074] 9, after the above-described pilot hole forming step ST3, in a silicon etching step ST4, through holes H1, H2, and H3 are formed in the substrate 5. The through hole H1 is a hole for forming the communication flow path Na, and passes through the first layer 511, the gap 513a, and the second layer 512. The through hole H2 is a hole for forming the supply flow path Ra, and passes through the first layer 511, the gap 513b, and the second layer 512. The through hole H3 is a hole for forming a part of the flow path R1, and passes through the first layer 511, the gap 513c, and the second layer 512.

[0075] Through hole H1 is composed of hole 511a, hole 512a, and gap 513a. Through hole H2 is composed of hole 511b, hole 512b, and gap 513b. Through hole H3 is composed of hole 511c, hole 512c, and gap 513c. Holes 511a, 511b, and 511c are holes that penetrate first layer 511. Holes 512a, 512b, and 512c are holes that penetrate second layer 512.

[0076] In the silicon etching step ST4, the through holes H1, H2, and H3 are formed by anisotropic etching. For the anisotropic etching, an etching solution such as KOH or TMAH is used. Here, as described above, each of the voids 513a and 513b has a parallelogram shape when the substrate 5 is viewed from the direction from the first layer 511 toward the second layer 512. As a result, when the first layer 511 and the second layer 512 are each a (110) silicon single crystal substrate, the anisotropic etching can form the through holes H1, H2, and H3 with high accuracy, which are made of the silicon (111) plane.

[0077] Here, as described above, since the void portion 513a encompasses the opening portion O1a in a plan view, a narrowed portion T1a that narrows the through hole H1 toward the opening portion O1a is formed in the first layer 511. Similarly, a narrowed portion T2a that narrows the through hole H1 toward the opening portion O2a is formed in the second layer 512. A narrowed portion T1b that narrows the through hole H2 toward the opening portion O1b is formed in the first layer 511. A narrowed portion T2b that narrows the through hole H2 toward the opening portion O2b is formed in the second layer 512. A narrowed portion T1c that narrows the through hole H3 toward the opening portion O1c is formed in the first layer 511. A narrowed portion T2c that narrows the through hole H3 toward the opening portion O2c is formed in the second layer 512. In this way, by providing the narrowed portions T1a, T1b, and T1c on the surface side of the first layer 511 and by providing the narrowed portions T2a, T2b, and T2c on the surface side of the second layer 512, the length of the inner wall surfaces of the through holes H1, H2, and H3 in the Z direction is increased, which makes it possible to prevent the adhesive from flowing out to unintended locations when another substrate is bonded to the communicating substrate 51 with an adhesive. Furthermore, since the length of the flow path through which the adhesive flows when the nozzle plate 530 is bonded to the communicating substrate 51 is increased, it is possible to prevent the adhesive from flowing from the pressure chamber substrate 520 to the vibration plate 550 and adversely affecting the vibration characteristics.

[0078] As described above, in the silicon etching step ST4, through holes H1, H2, and H3 are formed in the substrate 5. Here, as described above, since the insulating layer 513 has the voids 513a, 513b, and 513c, by using wet etching in the silicon etching step ST4, the size and shape of the through holes H1, H2, and H3 can be defined by the size and shape of the voids 513a, 513b, and 513c. This reduces variations in the size and shape of the flow paths, even when the supply flow path Ra and the communication flow path Na are each formed as a plurality of flow paths.

[0079] After the silicon etching step ST4, an oxide film etching step ST5 is performed to remove the thin film portion MT and thin the protective films M1A and M2A. This results in protective films M1B and M2B. For example, an etchant such as HF is used for this etching.

[0080] The protective film M1B is similar to the protective film M1A except that it is thinner than the protective film M1A. The protective film M2B is similar to the protective film M2A except that it is thinner than the protective film M2A and does not include the thin film portion MT.

[0081] After the oxide film etching step ST5, in the silicon etching step ST6, the portion of the second layer 512 exposed by the disappearance of the thin film portion MT is etched, thereby forming a recess RE that connects the through hole H1 and the through hole H2.

[0082] In the silicon etching step ST6, anisotropic etching is performed, similar to the silicon etching step ST4. Therefore, when the portion of the second layer 512 exposed by the disappearance of the thin film portion MT is etched, the insulating layer 513 functions as an etching stop layer. As a result, a recess RE is formed with the insulating layer 513 as its bottom surface.

[0083] After the silicon etching step ST6, an oxide film etching step ST7 is performed by etching to remove the protective films M1B and M2B, thereby obtaining the interconnected substrate 510. For example, an etching solution such as HF is used for this etching.

[0084] In this way, the oxide film etching step ST7 etches the insulating layer 513 after the silicon etching step ST4. This makes it possible to smooth the inner wall surfaces of the through holes H1, H2, and H3. Furthermore, when a flow path R1 including a recess RE communicating with the through hole H2 is formed, it is possible to prevent a sagging shape from being formed between the bottom surface of the recess RE and the through hole H2. Since the formation of a sagging shape can be prevented, it is possible to reduce variations in the length of each supply flow path Ra in the Z direction.

[0085] B: Second embodiment A second embodiment of the present disclosure will be described below. In the following exemplary embodiment, for elements whose actions and functions are similar to those of the first embodiment, the reference numerals used in the description of the first embodiment will be used, and detailed descriptions of each element will be omitted as appropriate.

[0086] 10 is a diagram showing the flow of the manufacturing method according to the second embodiment. The manufacturing method according to this embodiment is similar to the manufacturing method according to the first embodiment, except that it includes a mask formation step ST2A instead of the mask formation step ST2, and it omits the oxide film etching step ST5 and the silicon etching step ST6.

[0087] Each step of the manufacturing method of this embodiment will be described below in order.

[0088] FIG. 11 is an explanatory diagram of the substrate preparation step ST1, the mask formation step ST2A, and the pilot hole formation step ST3 in the second embodiment.

[0089] As shown in FIG. 11, first, in the substrate preparation step ST1, a substrate 5 is prepared, as in the first embodiment.

[0090] After the substrate preparation step ST1, protective films M1A and M2B are formed on the substrate 5 in the mask formation step ST2A. That is, the mask formation step ST2A is the same as the mask formation step ST2 of the first embodiment, except that the protective film M2B is formed instead of the protective film M2A. In this way, since the thin film portion MT of the first embodiment is removed in advance, the oxide film etching step ST5 of the first embodiment can be omitted. Furthermore, the silicon etching step ST4 also serves as the silicon etching step ST6 of the first embodiment. The thicknesses of the protective films M1A and M2B may be equal to or different from each other.

[0091] After the mask forming step ST2, in the pilot hole forming step ST3, pilot holes H1a, H1b, H2a, and H2b are formed in the substrate 5, similarly to the first embodiment.

[0092] FIG. 12 is an explanatory diagram of the silicon etching step ST4 and the oxide film etching step ST7 in the second embodiment.

[0093] 12, after the above-described pilot hole forming step ST3, in the silicon etching step ST4, through holes H1, H2, H3 and recesses RE are formed in the substrate 5. That is, the silicon etching step ST4 also serves as the silicon etching step ST6 in the first embodiment.

[0094] After the silicon etching step ST6, etching is performed to remove the protective films M1A and M2B in the oxide film etching step ST7, thereby obtaining the interconnected substrate 510. As in the first embodiment, the etching uses an etching solution such as HF.

[0095] According to the second embodiment described above, it is also possible to suppress variations in shape among a plurality of flow paths.

[0096] C: Third embodiment A third embodiment of the present disclosure will be described below. In the following exemplary embodiments, elements that have the same actions and functions as those in the first embodiment will be designated by the same reference numerals as those in the first embodiment, and detailed descriptions of each element will be omitted where appropriate.

[0097] Fig. 13 is an explanatory diagram of the flow path of a liquid ejection head 50A according to the third embodiment. Fig. 14 is a plan view of a communication substrate 510A according to the third embodiment. For ease of explanation, narrowed portions T1a, T1c, T2a, and T2c, which will be described later, are omitted from Fig. 14.

[0098] The liquid ejection head 50A is configured similarly to the liquid ejection head 50 of the first embodiment, except that it includes a communicating substrate 510A instead of the communicating substrate 510 of the first embodiment. The communicating substrate 510A is configured similarly to the communicating substrate 510 of the first embodiment, except that it includes a hole 511d instead of the hole 511b, and includes gaps 513c and 513e instead of the gap 513d.

[0099] The supply flow path Ra of this embodiment is composed of a hole 511d and a gap portion 513e.

[0100] Hole 511d is a through-hole that penetrates first layer 511 in the thickness direction. In the example shown in Fig. 13, hole 511d has narrowed portion T1d. Narrowed portion T1d has a shape that narrows the width of hole 511d toward the end of hole 511d in the Z2 direction, i.e., toward insulating layer 513. However, the width of hole 511d excluding narrowed portion T1d is constant over the entire area in the direction along the Z axis.

[0101] The void portion 513e is a through-hole that penetrates the insulating layer 513 in the thickness direction.

[0102] 14, the shape of the hole 511d in a plan view is a parallelogram. In contrast, the shape of the void 513e in a plan view is a circle. Furthermore, in a plan view, the void 513e is contained within the hole 511d. Note that in this embodiment, the narrowed portion T1b of the first embodiment is omitted. Furthermore, the shape of the void 513e in a plan view is not limited to a circle, and may be, for example, an ellipse or a polygon.

[0103] In this embodiment, a narrowed portion T2d is provided on the opposite side of the insulating layer 513 from the narrowed portion T1d. The narrowed portion T2d has a shape that narrows the width of the hole 512d toward the end of the hole 512d in the Z1 direction, i.e., toward the insulating layer 513.

[0104] 15 is an explanatory diagram of protective films M1C and M2C in mask formation step ST2 in the third embodiment. The manufacturing method of this embodiment is similar to the manufacturing method of the first embodiment, except that in substrate preparation step ST1, a substrate 5 having a void portion 513e is used instead of the void portion 513b, and in mask formation step ST2, protective film M1C is used instead of the protective film M1A of the first embodiment, and protective film M2C is used instead of the protective film M2A of the first embodiment. Note that the thin film portion MT may be omitted in protective film M2C, and in this case, appropriate steps may be omitted as in the manufacturing method of the second embodiment.

[0105] 15, the protective film M1C has the same configuration as the protective film M1A of the first embodiment except that it has an opening O1d instead of the opening O1b. The protective film M2C has the same configuration as the protective film M2A of the first embodiment except that it has an opening O2e instead of the opening O2b.

[0106] When the substrate 5 is viewed from the direction from the first layer 511 toward the second layer 512, each of the openings O1d and O2e encompasses the void 513e. This allows the size and shape of the through-hole H2 to be determined by the size and shape of the openings O1d and O2e by performing wet etching using the protective films M1C and M2C as a mask. Furthermore, the narrowed portions T1d and T2d can be formed. In the example shown in FIG. 15, the openings O1d and O2e each have a different shape in a plan view from the void 513e. This makes it easier to form the narrowed portions T1d and T2d.

[0107] 16 is an explanatory view of the silicon etching step ST4 in the third embodiment. The silicon etching step ST4 in the third embodiment is the same as the silicon etching step ST4 in the first embodiment, except that the protective films M1A and M2A are replaced with protective films M1C and M2C.

[0108] The through hole H2 formed in the silicon etching step ST4 of this embodiment is composed of a hole 511d, a hole 512m, and a gap 513e. The hole 511d is a hole that penetrates the first layer 511. The hole 512m is a hole that penetrates the second layer 512.

[0109] When substrate 5 is viewed from the direction from first layer 511 toward second layer 512, the shape of void 513e before silicon etching step ST4 is different from the shape of through-hole H2. By making the shape of void 513e different from the shape of through-hole H2 in this way, it is possible to reduce the flow resistance of supply flow path Ra and to prevent the adhesive from creeping up when bonding another substrate.

[0110] When the substrate 5 is viewed from the direction from the first layer 511 toward the second layer 512, the through-hole H2 encompasses the void 513e. This narrows the width of the formed supply flow path Ra at a position corresponding to the void 513e. Therefore, since the formed supply flow path Ra is an individual flow path that communicates with the pressure chamber C of the liquid ejection head 50, the presence of a narrowed portion in the supply flow path Ra can suppress the propagation of residual vibrations that occur in the supply flow path Ra.

[0111] In the silicon etching step ST4, a narrowed portion T1d is formed between the first layer 511 and the void 513e. This increases the contact area between the first layer 511 and the insulating layer 513 compared to a configuration in which the narrowed portion T1d is not provided, thereby suppressing bending of the insulating layer 513. For example, when the insulating layer 513 functions as a compliance layer due to residual stress, bending of the insulating layer 513 can be suppressed. In this embodiment, a narrowed portion T2d is formed between the second layer 512 and the void 513e. This also suppresses bending of the insulating layer 513.

[0112] According to the third embodiment described above, it is also possible to suppress variations in shape among a plurality of flow paths.

[0113] D: Fourth embodiment A fourth embodiment of the present disclosure will be described below. In the following exemplary embodiments, elements whose actions and functions are similar to those of the first embodiment will be designated by the same reference numerals as those used in the description of the first embodiment, and detailed descriptions of each element will be omitted where appropriate.

[0114] Fig. 17 is an explanatory diagram of the flow paths of a liquid ejection head 50B according to the fourth embodiment. Fig. 18 is a plan view of a communication substrate 510B according to the fourth embodiment. For ease of explanation, narrowed portions T1b, T1c, T2b, and T2c, which will be described later, are omitted from Fig. 18.

[0115] The liquid ejection head 50B is configured similarly to the liquid ejection head 50 of the first embodiment, except that it includes a communicating substrate 510B instead of the communicating substrate 510 of the first embodiment. The communicating substrate 510B is configured similarly to the communicating substrate 510 of the first embodiment, except that it includes a hole 511f instead of the hole 511a, a hole 512e instead of the hole 512a, and a gap 513f instead of the gap 513a.

[0116] The communication flow path Na in this embodiment is composed of a hole 511f, a hole 512e, and a gap portion 513f.

[0117] 17, hole 511f has a narrowed portion T1e. Narrowed portion T1e narrows the width of hole 511f toward the end of hole 511f in the Z2 direction, i.e., toward insulating layer 513. However, the width of hole 511f excluding narrowed portion T1e is constant throughout the entire area in the direction along the Z axis.

[0118] Hole 512e is a through-hole that penetrates second layer 512 in the thickness direction. The width of hole 512e is narrower than the width of hole 511f. In the example shown in Fig. 17, the width of hole 512e is constant throughout the entire area in the direction along the Z axis.

[0119] The void portion 513f is a through-hole that penetrates the insulating layer 513 in the thickness direction.

[0120] 18, hole 511f, hole 512e, and void 513f each have a parallelogram shape in plan view. Also, void 513f and hole 512e have the same shape in plan view. Furthermore, void 513f and hole 512e are each contained within hole 511f in plan view.

[0121] 19 is an explanatory diagram of protective films M1D and M2D in mask formation step ST2 in the fourth embodiment. The manufacturing method of this embodiment is similar to the manufacturing method of the first embodiment, except that in substrate preparation step ST1, a substrate 5 having a void portion 513f is used instead of the void portion 513a, and in mask formation step ST2, protective film M1D is used instead of the protective film M1A of the first embodiment, and protective film M2D is used instead of the protective film M2A of the first embodiment. Note that the thin film portion MT may be omitted in protective film M2D, and in this case, appropriate steps may be omitted as in the manufacturing method of the second embodiment.

[0122] 19, the protective film M1D has the same configuration as the protective film M1A of the first embodiment except that it has an opening O1e instead of the opening O1a. The protective film M2D has the same configuration as the protective film M2A of the first embodiment except that it has an opening O2f instead of the opening O2a.

[0123] When the substrate 5 is viewed from the direction from the first layer 511 toward the second layer 512, the opening O1e encompasses the void 513f, while the opening O2f coincides with the void 513f. This allows wet etching using the protective films M1D and M2D as a mask to define the size and shape of the hole 511f by the size and shape of the opening O1e, and to define the size and shape of the hole 512e by the size and shape of the opening O2f and the void 513f. Furthermore, a narrowed portion T1e can be formed. In the example shown in FIG. 19, the void 513f and the openings O1e and O2f each have a parallelogram shape in plan view.

[0124] 20 is an explanatory view of the silicon etching step ST4 in the fourth embodiment. The silicon etching step ST4 in the fourth embodiment is the same as the silicon etching step ST4 in the first embodiment, except that the protective films M1D and M2D are used instead of the protective films M1A and M2A.

[0125] The through hole H1 formed in the silicon etching step ST4 of this embodiment is composed of a hole 511f, a hole 512e, and a gap 513f.

[0126] According to the fourth embodiment described above, it is also possible to suppress variations in shape among a plurality of flow paths.

[0127] E: Fifth embodiment A fifth embodiment of the present disclosure will be described below. In the following exemplary embodiments, elements whose actions and functions are similar to those of the first embodiment will be designated by the same reference numerals as those used in the description of the first embodiment, and detailed descriptions thereof will be omitted where appropriate.

[0128] Fig. 21 is an explanatory diagram of the flow paths of a liquid ejection head 50C according to the fifth embodiment. Fig. 22 is a plan view of a communication substrate 510C according to the fifth embodiment. For ease of explanation, narrowed portions T1b, T1c, T2b, and T2c, which will be described later, are not shown in Fig. 22.

[0129] The liquid ejection head 50C is configured similarly to the liquid ejection head 50 of the first embodiment, except that it includes a communicating substrate 510C instead of the communicating substrate 510 of the first embodiment. The communicating substrate 510C is configured similarly to the communicating substrate 510 of the first embodiment, except that it includes a hole 511h instead of the hole 511a, a hole 512f instead of the hole 512a, and a gap 513f instead of the gap 513a.

[0130] The communication flow path Na in this embodiment is composed of a hole 511h, a hole 512f, and a gap portion 513f.

[0131] Hole 511h is a through-hole that penetrates first layer 511 in the thickness direction. Hole 511h has a width narrower than that of hole 512f. In the example shown in Fig. 21, hole 511h has a constant width over the entire area in the direction along the Z axis.

[0132] 21, the hole 512f has a narrowed portion T2e. The narrowed portion T2e narrows the width of the hole 512f toward the end of the hole 512f in the Z1 direction, i.e., toward the insulating layer 513. However, the width of the hole 512f excluding the narrowed portion T2e is constant throughout the entire area in the direction along the Z axis.

[0133] The width of the hole 512e is narrower than the width of the hole 511f. In the example shown in Fig. 21, the width of the hole 512e is constant over the entire area in the direction along the Z axis.

[0134] The void portion 513f is a through-hole that penetrates the insulating layer 513 in the thickness direction.

[0135] 22, hole 511h, hole 512f, and void 513f each have a parallelogram shape in plan view. Furthermore, void 513f and hole 511h have the same shape in plan view. Furthermore, void 513f and hole 511h are each contained within hole 512f in plan view.

[0136] 23 is an explanatory diagram of the protective film in the mask formation step ST2 in the fifth embodiment. The manufacturing method of this embodiment is similar to the manufacturing method of the first embodiment, except that in the substrate preparation step ST1, a substrate 5 having a void portion 513f is used instead of the void portion 513a, and in the mask formation step ST2, a protective film M1E is used instead of the protective film M1A of the first embodiment, and a protective film M2E is used instead of the protective film M2A of the first embodiment. Note that the thin film portion MT may be omitted in the protective film M2E, and in this case, appropriate steps may be omitted as in the manufacturing method of the second embodiment.

[0137] 23, the protective film M1E has the same configuration as the protective film M1A of the first embodiment except that it has an opening O1f instead of the opening O1a. The protective film M2E has the same configuration as the protective film M2A of the first embodiment except that it has an opening O2g instead of the opening O2a.

[0138] When the substrate 5 is viewed from the direction from the first layer 511 toward the second layer 512, the opening O2g encompasses the void 513f, while the opening O1f coincides with the void 513f. By performing wet etching using the protective films M1E and M2E as a mask, the size and shape of the hole 512f can be determined by the size and shape of the opening O2g, and the size and shape of the hole 511h can be determined by the size and shape of the opening O1f and the void 513f. Furthermore, a narrowed portion T2e can be formed. In the example shown in FIG. 23, the void 513f and the openings O1f and O2g each have a parallelogram shape in plan view.

[0139] 24 is an explanatory view of the silicon etching step ST4 in the fifth embodiment. The silicon etching step ST4 in the fifth embodiment is the same as the silicon etching step ST4 in the first embodiment, except that the protective films M1A and M2A are replaced with protective films M1E and M2E.

[0140] The through hole H1 formed in the silicon etching step ST4 of this embodiment is composed of a hole 511h, a hole 512f, and a void 513f.

[0141] According to the fifth embodiment described above, it is also possible to suppress variations in shape among a plurality of flow paths.

[0142] F: Variation The above-described embodiments can be modified in various ways. Specific modifications that can be applied to the above-described embodiments are exemplified below. Any of the following embodiments can be combined as desired within the scope of their mutual compatibility.

[0143] F1: Variation 1 In the first embodiment, the void 513a encompasses the opening O1a of the protective film M1A and the opening O2a of the protective film M2A in a plan view, but is not limited to this. For example, the void 513a may coincide with the opening O1a of the protective film M1A and the opening O2a of the protective film M2A in a plan view. In this case, the narrowed portions T1a and T2a are omitted.

[0144] Similarly, in the first embodiment, the gap 513b may coincide with the opening O1b of the protective film M1A and the opening O2b of the protective film M2A in a plan view. In this case, the narrowing portions T1b and T2b are omitted. Also, in the first embodiment, the gap 513c may coincide with the opening O1c of the protective film M1A and the opening O2c of the protective film M2A in a plan view. In this case, the narrowing portions T1c and T2c are omitted.

[0145] In this way, by matching the shapes and sizes of the openings O1a, O2b in the protective films M1A, M2A and the gap 513a, the narrowed portions T1a, T2a can be omitted. Similarly, in other embodiments, by matching the shapes and sizes of the openings in the protective films and the gap, the narrowed portions can be omitted.

[0146] F2: Variation 2 In the above-described embodiments, the method for manufacturing the flow paths of the liquid ejection head was described using the manufacturing of the communicating substrates 510, 510A, 510B, and 510C as an example, but the present disclosure is not limited to this example and can be applied to various manufacturing methods for forming through holes in a substrate. Furthermore, the configuration of the liquid ejection head is not limited to the above-described aspects and can be applied to liquid ejection heads of various known configurations having flow paths.

[0147] F3: Variation 3 In each of the above-described embodiments, a serial-type liquid ejection device 100 in which a transport body 41 equipped with a liquid ejection head 50 moves back and forth has been exemplified, but the present disclosure can also be applied to a line-type liquid ejection device in which multiple nozzles N are distributed across the entire width of the recording medium M.

[0148] F4: Variation 4 The liquid ejection device 100 exemplified in the above embodiment may be employed in various devices such as facsimile machines and copiers, in addition to devices dedicated to printing, and the applications of the present disclosure are not particularly limited. However, the applications of the liquid ejection device are not limited to printing. For example, a liquid ejection device that ejects a solution of a color material is used as a manufacturing device for forming color filters for display devices such as liquid crystal display panels. Furthermore, a liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes on a wiring board. Furthermore, a liquid ejection device that ejects a solution of an organic substance related to a living body is used as a manufacturing device for manufacturing biochips, for example.

[0149] G: Notes A summary of this disclosure is provided below.

[0150] (Appendix 1) A first aspect, which is a preferred example of the manufacturing method of the present disclosure, is a manufacturing method for forming a flow path in a liquid ejection head, and includes a first etching step of forming a through hole that passes from the first layer through the void and penetrates the second layer in a substrate having a first layer and a second layer made of silicon, and an insulating layer that is located between the first layer and the second layer and has insulating properties, and in which the insulating layer has a void.

[0151] In the above-described embodiment, since the insulating layer has a void, the size and shape of the through-hole can be determined by the size and shape of the void by using wet etching in the first etching step, which reduces variations in the size and shape of the flow paths even when multiple flow paths are formed.

[0152] (Supplementary Note 2) In the second aspect, which is a preferred example of the first aspect, a second etching step of etching the insulating layer is further included after the first etching step. In the above aspect, the inner wall surface of the through hole can be smoothed. Furthermore, when a flow path including a recess communicating with the through hole is formed, it is possible to prevent a sagging shape from being formed between the bottom surface of the recess and the through hole. Furthermore, when multiple flow paths are formed, it is possible to prevent a sagging shape from being formed, thereby reducing variation in the shape of the flow path.

[0153] (Note 3) In a third aspect, which is a preferred example of the first or second aspect, when the substrate is viewed from the direction from the first layer toward the second layer, the shape of the void before the first etching step is the same as the shape of the through hole formed in the first etching step. In this aspect, it is possible to prevent narrowed portions from being formed between the void and the first and second layers in the first etching step.

[0154] (Note 4) In a fourth aspect which is a preferred example of the third aspect, in the first etching step, the through-hole is formed by anisotropic etching, and the void has a parallelogram shape when the substrate is viewed from the direction from the first layer toward the second layer. In the above aspect, when the first layer and the second layer are each a (110) silicon single crystal substrate, a highly accurate through-hole constituted by a silicon (111) plane can be formed by anisotropic etching.

[0155] (Supplementary Note 5) In a fifth aspect which is a preferred example of any of the first to fourth aspects, when the substrate is viewed from the direction from the first layer toward the second layer, the shape of the void portion before the first etching step is different from the shape of the through hole. In the above aspect, by making the shape of the void portion and the shape of the through hole different, it is possible to reduce flow resistance and suppress creeping up of an adhesive when bonding substrates together.

[0156] (Supplementary Note 6) In the sixth aspect, which is a preferred example of the fifth aspect, when the substrate is viewed from the direction from the first layer toward the second layer, the through-hole encompasses the void portion. In the above aspect, the width of the formed flow path is narrowed at a position corresponding to the void portion. Therefore, for example, when the formed flow path is used as an individual flow path communicating with a pressure chamber of a liquid ejection head, the presence of a narrowed portion in the flow path can suppress the propagation of residual vibrations occurring in the flow path.

[0157] (Supplementary Note 7) In the seventh aspect, which is a preferred example of the sixth aspect, a narrowed portion is formed between the first layer and the void in the first etching step. In this aspect, the contact area between the first layer and the insulating layer is increased compared to a configuration in which a narrowed portion is not provided, thereby suppressing deflection of the insulating layer. For example, when the insulating layer functions as a compliance layer due to residual stress, deflection of the insulating layer can be suppressed.

[0158] (Appendix 8) In an eighth aspect which is a preferred example of any of the first to seventh aspects, a protective film is formed on the substrate in the first etching step, the protective film is formed with an opening that exposes the surface of the first layer, and the opening is included in the void when the substrate is viewed from the direction from the first layer toward the second layer. In the above aspects, by performing wet etching using the protective film as a mask, the size and shape of the through hole can be determined by the size and shape of the void.

[0159] (Appendix 9) In the ninth aspect, which is a preferred example of the eighth aspect, a narrowed portion that narrows the through hole toward the opening is formed in the first layer. In the above aspect, by providing the narrowed portion on the surface side of the first layer, the length of the inner wall surface of the through hole is increased, so that when other substrates are bonded with an adhesive, it is possible to prevent the adhesive from flowing to unintended locations. In addition, since the length of the flow path through which the adhesive flows when multiple substrates are bonded together is increased, it is possible to prevent the adhesive from flowing from a substrate bonded to one side of the substrate to a substrate bonded to the other side.

[0160] (Appendix 10) In the tenth aspect, which is a preferred example of any one of the first to ninth aspects, the method further includes, before the first etching step, a pilot hole forming step of forming a pilot hole having a width smaller than that of the through hole in the substrate at a position where the through hole is to be formed. In the above aspect, it is possible to reduce misalignment of the through hole. Furthermore, it is possible to form a through hole with a high aspect ratio by anisotropic etching.

[0161] (Appendix 11) An eleventh aspect, which is a preferred example of a liquid ejection head according to the present disclosure, includes a substrate having a first layer and a second layer made of silicon, and an insulating layer located between the first and second layers and having insulating properties. The substrate is provided with a first flow path formed by a hole penetrating the first layer, and a second flow path connected to the first flow path, the second flow path penetrating the second layer and the insulating layer and including a recess with the first layer as its bottom. This aspect can prevent sagging from occurring between the hole constituting the first flow path and the bottom of the recess included in the second flow path. This can reduce variation in the size and shape of the flow paths, even when multiple flow paths are formed. [Explanation of symbols]

[0162] 5...substrate, 10...liquid container, 20...control module, 30...transport mechanism, 40...movement mechanism, 41...transport body, 42...transport belt, 50...liquid ejection head, 50A...liquid ejection head, 50B...liquid ejection head, 50C...liquid ejection head, 51...communicating substrate, 100...liquid ejection device, 510...communicating substrate, 510A...communicating substrate, 510B...communicating substrate, 510C...communicating substrate, 511...first layer, 511a...hole, 511b...hole, 511c...hole, 511d...hole, 511f...hole, 511h...hole, 512...second layer, 512a...hole, 512b...hole, 512c...hole, 512d ...hole, 512e...hole, 512f...hole, 512m...hole, 513...insulating layer, 513a...gap, 513b...gap, 513c...gap, 513d...gap, 513e...gap, 513f...gap, 520...pressure chamber substrate, 530...nozzle plate, 540...vibration absorber, 550...diaphragm, 560...piezoelectric element, 570...protective substrate, 580...case, 590...wiring substrate, 600...drive circuit, C...pressure chamber, Com...drive signal, FN...nozzle surface, H1...through hole, H1a...preparation hole, H1b...preparation hole, H2a...preparation hole, H2b...preparation hole, H2...through hole, H3...through hole, HL...introduction opening, Ln1...first nozzle row, Ln2...second nozzle row, M...recording medium, M1A...protective film, M1B...protective film, M1C...protective film, M1D...protective film, M1E...protective film, M2A...protective film, M2B...protective film, M2C...protective film, M2D...protective film, M2E...protective film, MT...thin film portion, N...nozzle, Na...communicating flow path, O1a...opening, O1b...opening, O1c...opening, O1d...opening, O1e...opening, O1f...opening, O2a...opening, O2b...opening, O2c...opening, O2e...opening, O2f...opening, O2g...opening, R...reservoir, R1...flow path (second flow path) path), R2...flow path, RE...recess, Ra...supply flow path (first flow path), S...space, SI...control signal, ST...oxide film etching step, ST1...substrate preparation step, ST2...mask formation step, ST2A...mask formation step, ST3...pre-hole formation step, ST4...silicon etching step, ST5...oxide film etching step, ST6...silicon etching step, ST7...oxide film etching step, T1a...narrowed portion, T1b...narrowed portion, T1c...narrowed portion, T1d...narrowed portion, T1e...narrowed portion, T2a...narrowed portion, T2b...narrowed portion, T2c...narrowed portion, T2d...narrowed portion, T2e...narrowed portion.

Claims

1. A manufacturing method for forming a flow path in a liquid ejection head, comprising: a first etching step of forming a through hole that passes through the first layer, the first layer passing through the void, and the second layer in a substrate having a first layer and a second layer made of silicon, and an insulating layer that is located between the first layer and the second layer and has insulating properties, the insulating layer having a void; A manufacturing method characterized by:

2. The method further includes a second etching step of etching the insulating layer after the first etching step. The method according to claim 1 .

3. When the substrate is viewed from a direction from the first layer toward the second layer, the shape of the void portion before the first etching step is the same as the shape of the through hole formed in the first etching step. The method according to claim 1 or 2.

4. In the first etching step, the through-hole is formed by anisotropic etching, the void portion has a parallelogram shape when the substrate is viewed from a direction from the first layer toward the second layer; The method according to claim 3 .

5. when the substrate is viewed from a direction from the first layer toward the second layer, the shape of the void portion before the first etching step is different from the shape of the through hole; The method according to claim 1 or 2.

6. When the substrate is viewed from a direction from the first layer toward the second layer, the through hole encompasses the void portion. The method according to claim 5 .

7. In the first etching step, a narrowed portion is formed between the first layer and the gap portion. The method according to claim 6 .

8. a protective film provided on a surface of the first layer is formed on the substrate in the first etching step; an opening is formed in the protective film to expose a surface of the first layer; the opening is included in the gap when the substrate is viewed from a direction from the first layer toward the second layer. The method according to claim 1 or 2.

9. forming a narrowed portion in the first layer that narrows the through hole toward the opening; The method according to claim 8 .

10. a pilot hole forming step of forming a pilot hole having a width smaller than that of the through hole in the substrate at a position where the through hole is to be formed, before the first etching step; The method according to claim 1 or 2.

11. a substrate having a first layer and a second layer made of silicon, and an insulating layer located between the first layer and the second layer and having insulating properties; The substrate includes: a first flow path formed by a hole penetrating the first layer; a second flow path connected to the first flow path, the second flow path penetrating the second layer and the insulating layer and including a recess having the first layer as a bottom surface; A liquid ejection head characterized by:

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