Method for manufacturing a liquid dispensing head, and liquid dispensing head

Abstract

To provide a method for manufacturing a liquid dispensing head that can suppress a decrease in dispensing performance, and to provide a liquid dispensing head. [Solution] A method for manufacturing a liquid discharge head includes an insulating film formation step of forming an insulating film on a first surface of a substrate made of single-crystal silicon, a step of forming a first layer made of polycrystalline silicon on the insulating film by film deposition, and a first recess formation step of forming a first recess in the first layer which will be a first nozzle, the bottom surface of which is the insulating film. The liquid discharge head also has a first layer made of polycrystalline silicon, a second layer made of single-crystal silicon, and an insulating film provided between the first layer and the second layer, the first layer has a first nozzle, and the second layer has a second nozzle that penetrates the first nozzle through an opening in the insulating film.

Description

Technical Field

[0001] The present invention relates to a method of manufacturing a liquid discharge head and a liquid discharge head.

Background Art

[0002] Conventionally, there have been proposed liquid discharge apparatuses including a liquid discharge head that discharges a liquid such as ink onto a medium such as printing paper. The liquid discharge head generally includes a nozzle plate formed with a plurality of nozzle holes for discharging ink droplets, a pressure chamber communicating with the nozzle plate, and a driving element that applies pressure to the pressure chamber. Driving of the driving element changes the pressure in the pressure chamber, and ink droplets are discharged from the nozzle holes.

[0003] The nozzle described in Patent Document 1 is configured as a so-called two-stage nozzle having a first nozzle on a liquid discharge side and a second nozzle on a liquid supply side. In manufacturing the nozzle, after the first nozzle is formed on one surface of a silicon substrate by dry etching, the second nozzle is formed from the other surface side of the silicon substrate by dry etching.

Prior Art Literature

Patent Literature

[0004]

Patent Literature 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] In said document, one silicon substrate is used, the first nozzle is formed from one surface thereof, and the second nozzle is formed from the other surface. In this case, for example, an error between the predicted etching rate and the actual etching rate may cause the length of the first nozzle to deviate from an ideal value, or may cause individual variations in the length of the first nozzle. The length of the first nozzle is greatly related to discharge performance. Therefore, if the length of the first nozzle greatly deviates from the ideal value, there is a risk that discharge performance may deteriorate. [Means for solving the problem]

[0006] A method for manufacturing a liquid discharge head according to a preferred embodiment of the present invention includes an insulating film formation step of forming an insulating film on a first surface of a substrate made of single-crystal silicon; a step of forming a first layer made of polycrystalline silicon on the insulating film by film deposition; and a first recess formation step of forming a first recess in the first layer, which is to be a first nozzle and whose bottom surface is the insulating film.

[0007] A liquid dispensing head according to a preferred embodiment of the present invention comprises a first layer made of polycrystalline silicon, a second layer made of single-crystal silicon, and an insulating film provided between the first layer and the second layer, wherein the first layer has a first nozzle, and the second layer has a second nozzle that penetrates the first nozzle through an opening in the insulating film. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram illustrating the configuration of a liquid dispensing device according to the first embodiment. [Figure 2] Figure 1 is an exploded perspective view of the liquid dispensing head. [Figure 3] This is a cross-sectional view of a portion of the liquid dispensing head shown in Figure 1. [Figure 4] Figure 3 is a magnified view of the diaphragm and piezoelectric element shown. [Figure 5] Figure 3 is a magnified view of the nozzle of the nozzle plate shown. [Figure 6] This diagram shows the flow of the manufacturing method for the nozzle plate according to the first embodiment. [Figure 7] This is a diagram illustrating the manufacturing method of the nozzle plate shown in Figure 6. [Figure 8] This is a diagram illustrating the manufacturing method of the nozzle plate shown in Figure 6. [Figure 9] This is a cross-sectional view showing the nozzle of the nozzle plate of the second embodiment. [Figure 10]This is a cross-sectional view showing the nozzle of the nozzle plate according to the third embodiment. [Modes for carrying out the invention]

[0009] Preferred embodiments of the present invention will be described below with reference to the attached drawings. Note that the dimensions or scale of each part in the drawings may differ from the actual dimensions as appropriate, and some parts are shown schematically for ease of understanding. Furthermore, the scope of the present invention is not limited to these embodiments unless otherwise stated in the following description. Also, "element β on element γ" is not limited to a configuration in which element γ and element β are in direct contact, but also includes configurations in which element γ and element β are not in direct contact. Furthermore, "element α and element β are stacked" means that element α and element β are aligned in the vertical direction, and it is not required that element α and element β are in direct contact.

[0010] 1. First Embodiment 1-1. Overall configuration of the liquid dispensing device 100 Figure 1 is a schematic diagram illustrating the configuration of the liquid dispensing device 100 according to the first embodiment. For the sake of explanation, the X, Y, and Z axes, which are orthogonal to each other, will be used as appropriate below. Also, one direction along the X axis will be denoted as the X1 direction, and the direction opposite to the X1 direction will be denoted as the X2 direction. Similarly, one direction along the Y axis will be denoted as the Y1 direction, and the direction opposite to the Y1 direction will be denoted as the Y2 direction. One direction along the Z axis will be denoted as the Z1 direction, and the direction opposite to the Z1 direction will be denoted as the Z2 direction. Viewing along the Z axis is called a "plan view". The Z axis is typically a vertical axis. The Z2 direction is upward, and the Z1 direction is downward. However, the Z axis does not have to be a vertical axis. Also, the X, Y, and Z axes are typically orthogonal to each other, but are not limited to this, and may intersect at an angle within the range of 80° to 100°.

[0011] The liquid ejection apparatus 100 illustrated in FIG. 1 is an inkjet-type printing apparatus that ejects ink, which is an example of liquid, onto a medium 90. The medium 90 is typically printing paper, but any printing target of any material such as a resin film or fabric may be used as the medium 90. As illustrated in FIG. 1, the liquid ejection apparatus 100 is provided with a liquid container 9 that stores ink. For example, a cartridge attachable to and detachable from the liquid ejection apparatus 100, a bag-shaped ink pack formed of a flexible film, or an ink tank capable of being refilled with ink is used as the liquid container 9.

[0012] The liquid ejection apparatus 100 includes a control unit 20, a medium conveyance mechanism 22, a movement mechanism 24, and a liquid ejection head 3. The control unit 20 includes, for example, one or more processing circuits such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and one or more storage circuits such as a semiconductor memory, and collectively controls each element of the liquid ejection apparatus 100.

[0013] The medium conveyance mechanism 22 conveys the medium 90 in a direction along the Y-axis under the control of the control unit 20. Further, the movement mechanism 24 reciprocates the liquid ejection head 3 along the X-axis under the control of the control unit 20. The movement mechanism 24 includes a substantially box-shaped carriage 242 that accommodates the liquid ejection head 3, and a conveyance belt 244 to which the carriage 242 is fixed. Note that a configuration in which a plurality of liquid ejection heads 3 are mounted on the carriage 242, or a configuration in which the liquid container 9 is mounted on the carriage 242 together with the liquid ejection head 3 may also be employed.

[0014] The liquid ejection head 3 ejects ink supplied from the liquid container 9 onto the medium 90 from a plurality of nozzles under the control of the control unit 20. An image is formed on the surface of the medium 90 by each liquid ejection head 3 ejecting ink droplets onto the medium 90 in parallel with the conveyance of the medium 90 by the medium conveyance mechanism 22 and the repeated reciprocation of the carriage 242.

[0015] The liquid ejecting apparatus 100 is of a serial head type in which the liquid ejecting head 3 reciprocates over the medium 90. However, the liquid ejecting apparatus 100 may also be of a line head type in which the liquid ejecting head 3 is fixed.

[0016] 1-2. Overall Configuration of Liquid Ejecting Head 3 Figure 2 is an exploded perspective view of the liquid ejecting head 3 illustrated in Figure 1. Figure 3 is a partial cross-sectional view of the liquid ejecting head 3 illustrated in Figure 1, which is taken along line a-a in Figure 2. The cross-section illustrated in Figure 3 is a cross-section parallel to the X-Z plane. Furthermore, the Z-axis is along the ink ejection direction of the liquid ejecting head 3.

[0017] As illustrated in Figure 2, the liquid ejecting head 3 includes a plurality of nozzles N arranged along the Y-axis. The plurality of nozzles N of the first embodiment are divided into a first row La and a second row Lb arranged side-by-side spaced apart from each other along the X-axis. Each of the first row La and the second row Lb is an assembly of a plurality of nozzles N linearly arranged along the Y-axis. The liquid ejecting head 3 has a structure in which elements associated with each nozzle N in the first row La and elements associated with each nozzle N in the second row Lb are arranged substantially in plane symmetry. In the following description, elements corresponding to the first row La will be mainly described, and descriptions of elements corresponding to the second row Lb will be omitted as appropriate.

[0018] As illustrated in Figures 2 and 3, the liquid ejecting head 3 includes a flow path forming substrate 31, a pressure chamber substrate 32, a vibration plate 33, a nozzle plate 37, a vibration absorbing member 38, a plurality of piezoelectric elements 5, a sealing member 35, a housing portion 36, and a wiring substrate 40. Each of the flow path forming substrate 31, the pressure chamber substrate 32, the vibration plate 33, the nozzle plate 37, the vibration absorbing member 38, the sealing member 35, and the housing portion 36 is an elongated plate-shaped member along the Y-axis. Furthermore, the nozzle plate 37, the flow path forming substrate 31, the pressure chamber substrate 32, the vibration plate 33, and the sealing member 35 are arranged in this order in the Z2 direction.

[0019] The nozzle plate 37 is a plate-shaped member on which a plurality of nozzles N are formed. Each of the plurality of nozzles N is a through-hole for ejecting ink. The nozzle plate 37 is bonded to the surface of the flow path forming substrate 31 in the Z1 direction, for example, by adhesive.

[0020] The channel-forming substrate 31 forms channels through which the ink flows. Specifically, the channel-forming substrate 31 has a space Ra, an intermediate liquid chamber Rb, a plurality of supply channels 312, and a plurality of communication channels 314. Space Ra is an elongated opening formed along the Y-axis. Each of the supply channels 312 and communication channels 314 is a through-hole formed for each nozzle N. Each communication channel 314 overlaps a corresponding nozzle N in a plan view from the Z1 direction. The intermediate liquid chamber Rb is an elongated space formed along the Y-axis across multiple nozzles N, and connects space Ra and the plurality of supply channels 312 to each other. A pressure chamber substrate 32 is bonded to the Z2 direction surface of the channel-forming substrate 31 with adhesive.

[0021] Multiple pressure chambers C1 are formed in the pressure chamber substrate 32. Ink ejected from the nozzle N is stored in the pressure chamber C1. The pressure chamber C1 is located between the nozzle plate 37 and the diaphragm 33 and is a space formed by the inner wall surface 32a of the pressure chamber substrate 32. A pressure chamber C1 is formed for each nozzle N. The pressure chamber C1 is an elongated space and extends in the X1 direction. Multiple pressure chambers C1 are arranged along the Y axis. Each pressure chamber C1 communicates with the communication channel 314 and the supply channel 312. Therefore, the pressure chamber C1 communicates with the nozzle N via the communication channel 314 and with the space Ra via the supply channel 312 and the intermediate liquid chamber Rb.

[0022] The channel-forming substrate 31 and the pressure chamber substrate 32 are manufactured by processing a silicon (Si) substrate using semiconductor manufacturing technologies such as photolithography and etching. However, known materials and manufacturing methods can be arbitrarily used for the manufacture of the channel-forming substrate 31 and the pressure chamber substrate 32.

[0023] The diaphragm 33 is connected to the surface of the pressure chamber substrate 32 opposite to the flow path forming substrate 31. The diaphragm 33 is positioned on the pressure chamber C1 and is elastically deformable. The diaphragm 33 is a plate-like member formed in a long rectangular shape along the Y-axis in a plan view. The diaphragm 33 and the pressure chamber substrate 32 may be an integral part of the structure, or they may be separate parts joined together with an adhesive or the like.

[0024] A piezoelectric element 5 is formed on the surface of the diaphragm 33 opposite to the pressure chamber C1. A piezoelectric element 5 is provided for each pressure chamber C1. The piezoelectric element 5 is elongated in length along the X-axis in a plan view. The piezoelectric element 5 is a driving element that applies pressure to the ink in the pressure chamber C1.

[0025] The seal 35 is bonded to the diaphragm 33, for example, by adhesive. The seal 35 is a structure that protects the multiple piezoelectric elements 5 and reinforces the mechanical strength of the pressure chamber substrate 32 and the diaphragm 33. A recess is formed in the seal 35 on the surface facing the diaphragm 33. The multiple piezoelectric elements 5 are housed inside this recess. The seal 35 also has a space 353 through which the wiring board 40 is inserted.

[0026] The housing portion 36 is joined to the flow channel forming substrate 31, for example, by adhesive. The housing portion 36 is a case for storing ink supplied to a plurality of pressure chambers C1. The housing portion 36 is formed, for example, by injection molding of a resin material. The housing portion 36 has a space Rc, a supply port 361, and a space 362. The supply port 361 is a conduit through which ink is supplied from the liquid container 9 and communicates with space Rc. Space Rc communicates with space Ra of the flow channel forming substrate 31. The space composed of space Rc and space Ra functions as a liquid storage chamber R for storing ink supplied to the plurality of pressure chambers C1. Ink supplied from the liquid container 9 and passing through the supply port 361 is stored in the liquid storage chamber R. The ink stored in the liquid storage chamber R branches from the relay liquid chamber Rb to each supply flow channel 312 and is supplied in parallel to the plurality of pressure chambers C1. Also, space 362 overlaps with space 353 of the sealing body 35 in a plan view. The wiring board 40 is inserted through spaces 353 and 362.

[0027] The wiring board 40 is connected to the diaphragm 33. The wiring board 40 is a mounting component on which multiple wires are formed for electrically connecting the control unit 20 and the liquid discharge head 3. For example, a flexible substrate such as an FPC (Flexible Printed Circuit) or FFC (Flexible Flat Cable) is preferably used for the wiring board 40. A drive voltage and a reference voltage for driving the piezoelectric elements 5 are supplied from the wiring board 40 to each piezoelectric element 5.

[0028] Furthermore, a vibration absorber 38 is bonded to the Z1-direction surface of the channel-forming substrate 31, for example, by an adhesive. The vibration absorber 38 is a flexible film that constitutes the wall surface of the space Ra and supplies pressure fluctuations to the ink in the liquid storage chamber R.

[0029] In this liquid ejection head 3, when the piezoelectric element 5 is deflected and deformed by the application of voltage, the diaphragm 33 deflects and deforms, i.e., vibrates, in a direction that reduces the volume of the pressure chamber C1. As a result, the pressure in the pressure chamber C1 changes, and the ink in the pressure chamber C1 is ejected from the nozzle N. After the ink is ejected, the piezoelectric element 5 returns to its original position.

[0030] Furthermore, although the liquid discharge head 3 includes all the elements shown in Figure 3, the components of the liquid discharge head 3 do not necessarily have to include all of these elements, and may also include additional elements.

[0031] 1-3. Diaphragm 33 and piezoelectric element 5 Figure 4 is an enlarged view showing the diaphragm 33 and piezoelectric element 5 in Figure 3. The cross-section shown in Figure 4 is parallel to the YZ plane.

[0032] As shown in Figure 4, the piezoelectric element 5 mainly consists of a lower electrode 51, a piezoelectric layer 53, and an upper electrode 52. The lower electrode 51, the piezoelectric layer 53, and the upper electrode 52 are stacked in a direction along the Z-axis, which is the stacking direction.

[0033] The lower electrode 51 is provided above the diaphragm 33. The lower electrode 51 is an individual electrode provided for each piezoelectric element 5. A driving voltage with fluctuating voltage is applied to the lower electrode 51. The lower electrode 51 is elongated along the X-axis. Multiple lower electrodes 51 are arranged along the Y-axis with spacing between them. The lower electrode 51 contains a conductive material such as platinum (Pt). The thickness of the lower electrode 51 along the Z-axis is not particularly limited, but is, for example, 50 nm to 120 nm.

[0034] The piezoelectric layer 53 is provided above the lower electrode 51. The piezoelectric layer 53 is, for example, a strip-shaped dielectric film that is continuous along the Y-axis across multiple piezoelectric elements 5, and is separated for each piezoelectric element 5 by the formation of multiple notches. The piezoelectric layer 53 is composed of a piezoelectric material having a perovskite crystal structure. Examples of such piezoelectric materials include lead titanate (PbTiO3), lead zirconate titanate (PZT:Pb(Zr,Ti)O3), lead zirconate (PbZrO3), lead lanthanum titanate ((Pb,La),TiO3), lead lanthanum zirconate titanate ((Pb,La)(Zr,Ti)O3), lead zirconium niobate titanate (Pb(Zr,Ti,Nb)O3), lead zirconium magnesium niobate titanate (Pb(Zr,Ti)(Mg,Nb)O3), and potassium sodium niobate (KNN). The piezoelectric layer 53 may contain small amounts of other elements, such as impurities. Furthermore, the thickness of the piezoelectric layer 53 along the Z-axis is not particularly limited, but is, for example, between 300 nm and 1500 nm.

[0035] The upper electrode 52 is provided above the piezoelectric layer 53. The upper electrode 52 is a strip-shaped common electrode that extends along the Y-axis so as to be continuous across multiple piezoelectric elements 5. A constant reference voltage is applied to the upper electrode 52. The upper electrode 52 contains a conductive material such as iridium (Ir). The thickness of the upper electrode 52 along the Z-axis is not particularly limited, but is, for example, 50 nm to 120 nm.

[0036] A voltage equivalent to the difference between the reference voltage applied to the upper electrode 52 and the driving voltage applied to the lower electrode 51 is applied to the piezoelectric layer 53. The piezoelectric layer 53 deforms as a result of the voltage applied between the lower electrode 51 and the upper electrode 52, causing the piezoelectric element 5 to bend, i.e., vibrate.

[0037] The diaphragm 33 vibrates when driven by the piezoelectric element 5. In the illustrated example, the diaphragm 33 is composed of a laminate including a first vibrating body layer 331 and a second vibrating body layer 332. The first vibrating body layer 331 is in contact with the pressure chamber substrate 32. The second vibrating body layer 332 is positioned above the first vibrating body layer 331. The first vibrating body layer 331 is made of silicon oxide (SiO₂). x The second vibrating body layer 332 is made of an elastic material such as zirconium oxide (ZrO). x It is formed of an insulating material such as ). The first vibrating body layer 331 is formed, for example, by thermal oxidation of a part of the pressure chamber substrate 32. The second vibrating body layer 332 is formed, for example, by known film deposition techniques such as sputtering. The diaphragm 33 may consist of one layer or three or more layers.

[0038] 1-4. Nozzle plate 37 Figure 5 is an enlarged view of the nozzle N of the nozzle plate 37 shown in Figure 3.

[0039] The nozzle plate 37 shown in Figure 5 has a first layer 371, a substrate 372, and an insulating film 373. The first layer 371, the insulating film 373, and the substrate 372 are stacked in this order in the Z2 direction.

[0040] The first layer 371 is made of a different material from the substrate 372. In this embodiment, the first layer 371 is made of polycrystalline silicon. The first layer 371 may also contain components other than silicon. The first layer 371 may also be made of, for example, amorphous silicon, aluminum oxide (Al2O3), silicon carbide (SiC), gallium nitride (GaN), or polyimide. The thickness of the first layer 371 along the Z axis is greater than the thickness of the insulating film 373 along the Z axis. The thickness of the first layer 371 is, for example, 5 μm or more and 20 μm or less. The first layer 371 also has a nozzle surface 3710. The nozzle surface 3710 is the lower surface of the nozzle plate 37 and is the ejection surface from which ink droplets are ejected from the nozzle N.

[0041] The substrate 372 corresponds to the "second layer". The substrate 372 is made of silicon. Specifically, the substrate 372 is made of single-crystal silicon. The substrate 372 may or may not contain impurities, and may be n-type silicon or p-type silicon. The thickness of the substrate 372 along the Z axis is greater than the thickness of the insulating film 373 along the Z axis. The thickness of the substrate 372 along the Z axis is greater than the thickness of the first layer 371 along the Z axis, but may be less than or equal to the thickness of the first layer 371 along the Z axis. The thickness of the substrate 372 is, for example, 30 μm or more and 80 μm or less. The substrate 372 also has a first surface 3721 and a second surface 3722 on the opposite side. The first surface 3721 and the second surface 3722 are each main surfaces along the XY plane. The first surface 3721 is in contact with the insulating film 373. The second surface 3722 is the upper surface of the nozzle plate 37 and is the surface that contacts the flow path forming substrate 31.

[0042] The insulating film 373 is provided between the first layer 371 and the substrate 372. The insulating film 373 has insulating properties and is composed of a different material from the substrate 372 and the first layer 371. The insulating film 373 is composed of, for example, silicon oxide. The insulating film 373 may also be composed of silicon oxynitride, silicon nitride, etc. The thickness of the insulating film 373 is, for example, 0.2 μm or more and 0.8 μm or less.

[0043] Multiple nozzles N are formed on the nozzle plate 37. In Figure 5, any one of the multiple nozzles N is shown.

[0044] Nozzle N is a through-hole formed in the nozzle plate 37. Nozzle N has a first nozzle N1, a second nozzle N2, and a boundary portion N3. The first nozzle N1 is a through-hole formed in the first layer 371. The second nozzle N2 is a through-hole formed in the substrate 372. The boundary portion N3 is a through-hole formed in the insulating film 373.

[0045] Nozzle N is a so-called two-stage nozzle. The first nozzle N1 and the second nozzle N2 are arranged in this order in the Z2 direction and are connected to each other via a boundary portion N3. Each of the first nozzle N1 and the second nozzle N2 extends along the Z axis. Note that the boundary portion N3 may be considered as a part of the first nozzle N1 or a part of the second nozzle N2.

[0046] The cross-sectional shapes of the first nozzle N1, the second nozzle N2, and the boundary portion N3 are circular. Each of the first nozzle N1, the second nozzle N2, and the boundary portion N3 is cylindrical with axis A0 as its central axis and is arranged coaxially. In the illustrated example, the length L1 of the first nozzle N1 along the Z-axis is smaller than the length L2 of the second nozzle N2 along the Z-axis, but it may be greater than or equal to the length L2 of the second nozzle N2 along the Z-axis.

[0047] The cross-sectional area of ​​the first nozzle N1 is smaller than that of the second nozzle N2. In other words, the diameter of the second nozzle N2 is larger than that of the first nozzle N1. Therefore, compared to the case where the diameter of nozzle N is constant, it is possible to eject finer ink droplets and improve the accuracy of ink droplet placement.

[0048] The first nozzle N1 is a through hole formed by the inner wall surface 3713. The first nozzle N1 has an ejection-side opening Na for ejecting ink droplets. The ejection-side opening Na is an open end that opens to the nozzle surface 3710. The second nozzle N2 is a through hole formed by the inner wall surface 3723. The second nozzle N2 has a supply-side opening Nb for supplying ink to nozzle N. The supply-side opening Nb is an open end that opens to the second surface 3722. The supply-side opening Nb is also the boundary between the communication channel 314 of the aforementioned channel-forming substrate 31 and nozzle N. The length along the Z-axis from the supply-side opening Nb to the ejection-side opening Na is the total length of nozzle N. The boundary N3 is a through hole formed by the inner wall surface 3733. The boundary N3 communicates with both the first nozzle N1 and the second nozzle N2. The length L3 along the Z-axis of the boundary N3 is shorter than both lengths L1 and L2.

[0049] In this embodiment, the cross-sectional areas of the first nozzle N1, the second nozzle N2, and the boundary portion N3 are constant. The cross-sectional area of ​​the first nozzle N1 is the smallest, and the cross-sectional areas of the first nozzle N1, the second nozzle N2, and the boundary portion N3 are in that order of increasing size. The diameter of the first nozzle N1 is, for example, 20 μm or more and 30 μm or less. The diameter of the second nozzle N2 is, for example, 30 μm or more and 50 μm or less.

[0050] As described above, the nozzle plate 37 includes a first layer 371 made of polycrystalline silicon, a substrate 372 as a "second layer" made of silicon, and an insulating film 373 provided between the first layer 371 and the substrate 372. The first layer 371 has a first nozzle N1. The substrate 372 has a second nozzle N2 that penetrates the first nozzle N1. The second nozzle N2 penetrates the first nozzle N1 through a boundary portion N3 which is an opening in the insulating film 373.

[0051] Since the first layer 371 corresponding to the first nozzle N1 is made of polycrystalline silicon, the first layer 371 can be formed by film deposition, and the thickness of the first layer 371 can be controlled with high precision. Therefore, the length L1, or stroke length, of the first nozzle N1 can be controlled with high precision. Compared to the conventional method of forming the first nozzle N1 and the second nozzle N2 from a single silicon substrate, the length L1 of the first nozzle N1 can be controlled with high precision. In addition, as will be described later, by using the insulating film 373 as an etching stopper layer, the length L1 of the first nozzle N1 can be controlled with high precision. As a result, it is easier to achieve the ideal length L1 of the first nozzle N1, and individual differences in the length L1 of the first nozzle N1 can be reduced. And because the ideal length L1 of the first nozzle N1 can be achieved, a decrease in ejection performance can be suppressed.

[0052] 1-5. Manufacturing method of nozzle plate 37 Figure 6 is a diagram showing the flow of the manufacturing method of the nozzle plate 37 according to the first embodiment. Figures 7 and 8 are diagrams illustrating the manufacturing method of the nozzle plate 37 in Figure 6.

[0053] As shown in Figure 6, the method for manufacturing the nozzle plate 37 includes an insulating film formation step S1, a first layer deposition step S2, a first recess formation step S3, a second recess formation step S4, and an insulating film removal step S5.

[0054] Before each step, first prepare the substrate 372. Specifically, prepare a substrate 372 made of silicon. More specifically, prepare a substrate 372 made of single-crystal silicon.

[0055] As shown in Figure 7(a), in the insulating film formation step S1, an insulating film 373 is formed on the first surface 3721 of the substrate 372. The insulating film 373 is formed on the first surface 3721 by atomic layer deposition (ALD) using an insulating material such as silicon oxide.

[0056] Furthermore, in the insulating film formation step S1, the insulating film 373 may be formed by thermal oxidation of a portion of the substrate 372. Forming the insulating film 373 by thermal oxidation simplifies the process compared to forming the insulating film 373 by film deposition. Even when the insulating film 373 is formed by thermal oxidation of a portion of the substrate 372, it is still referred to as forming the insulating film 373 on the first surface 3721.

[0057] As shown in Figure 7(b), in the first layer deposition step S2, the first layer 371 is formed on the insulating film 373 by deposition. Film deposition is a technique for forming a thin film on an insulating layer by depositing atoms or molecules. Examples of film deposition methods include chemical vapor deposition (CVD) including ALD, vacuum deposition, or sputtering. The first layer 371 is made of a different material from the material that makes up the substrate 372.

[0058] As shown in Figure 7(c), in the first recess formation step S3, a first recess N10, which will become the first nozzle N1, is formed. The first recess N10 is a wall surface constituting a hole formed in the first layer 371, its bottom surface is the insulating film 373, and its side surface is the inner wall surface 3713 of the first layer 371. The first recess N10 is cylindrical. For example, the first recess N10 is formed by isotropic etching using the Bosch process. For this etching, for example, a fluorine-based etching agent is used.

[0059] As shown in Figure 8(a), in the second recess formation step S4, a second recess N20, which will become the second nozzle N2, is formed in the substrate 372. The second recess N20 is formed by etching from the second surface 3722 opposite to the first surface 3721 of the substrate 372. The second recess N20 is formed by isotropic etching. For example, a fluorine-based etching agent is used for this etching. The second recess N20 is a wall surface constituting a hole formed in the substrate 372, its bottom surface is the insulating film 373, and its side surface is the inner wall surface 3723 of the substrate 372. The second recess N20 is cylindrical. The diameter of the second recess N20 is larger than the diameter of the first recess N10. Before forming the second recess N20, the substrate 372 may be processed to a thickness corresponding to the length L2 of the second nozzle N2 by polishing or the like.

[0060] As shown in Figure 8(b), in the insulating film removal step S5, a portion of the insulating film 373 located at the bottom surface of the first recess N10 and the bottom surface of the second recess N20 is removed, thereby penetrating the first recess N10 and the second recess N20. The removal of a portion of the insulating film 373 is performed by etching. For example, a fluorine-based etching agent is used for this etching. Due to over-etching in this etching process, the diameter of the insulating film 373 becomes larger than the diameter of the first recess N10 and the diameter of the second recess N20. However, the diameter of the insulating film 373 may be the same as the diameter of either the second recess N20 or the diameter of the first recess N10.

[0061] Through the above process, a nozzle N is formed which comprises a first nozzle N1 consisting of a first recess N10, a second nozzle N2 consisting of a second recess N20, and a nozzle N including a boundary portion N3.

[0062] As described above, the method for manufacturing the liquid discharge head 3 includes an insulating film formation step S1, a first layer deposition step S2, and a first recess formation step S3. In the insulating film formation step S1, an insulating film 373 is formed. In the first layer deposition step S2, a first layer 371 is formed on the insulating film 373 by deposition, the first layer 371 being made of a material different from the material constituting the substrate 372. In the first recess formation step S3, a first recess N10 is formed in the first layer 371, which will become the first nozzle N1, and whose bottom surface is the insulating film 373.

[0063] In the first layer deposition process S2, the first layer 371 corresponding to the first nozzle N1 is formed on the insulating film 373 by deposition, allowing for high-precision control of the film thickness of the first layer 371. Therefore, compared to the conventional method of forming the first nozzle N1 and the second nozzle N2 from a single silicon substrate, the depth of the first recess N10 can be controlled with higher precision. In addition, in the first recess formation process S3, the insulating film 373 can be used as an etching stopper layer when forming the first recess N10. This allows for high-precision control of the depth of the first recess N10. As a result, it is easier to achieve the ideal length L1 of the first nozzle N1, and individual differences in the length L1 of the first nozzle N1 can be reduced. Since the ideal length L1 of the first nozzle N1 can be achieved, a decrease in ejection performance can be suppressed.

[0064] Furthermore, it is preferable that the first layer 371 be made of polycrystalline silicon. By making the first layer 371 of polycrystalline silicon, the coefficient of linear expansion of the first layer 371 and the substrate 372 can be made the same or close to the same. This makes it possible to suppress the delamination of the first layer 371 and the substrate 372 when a temperature change occurs in the nozzle plate 37. In addition, since polycrystalline silicon can be deposited with high precision compared to other materials, individual differences in the film thickness of the first layer 371 can be easily suppressed.

[0065] Furthermore, it is preferable that the coefficient of thermal expansion X of the first layer 371 satisfies the following equation (1), where Y is the coefficient of thermal expansion of the substrate 372. |XY|<1.0×10-6 ...(1)

[0066] By satisfying the above relationship between the coefficients of linear expansion X and Y, it is possible to effectively suppress the delamination of the first layer 371 and the substrate 372 when a temperature change occurs. However, the coefficients of linear expansion X and Y do not necessarily have to satisfy the above relationship.

[0067] Furthermore, each first layer 371, composed of polycrystalline silicon, amorphous silicon, aluminum oxide (Al2O3), silicon carbide (SiC), gallium nitride (GaN), and polyimide, satisfies the above formula (1). The coefficient of linear expansion of the silicon substrate 372 is 2.6 × 10⁻⁶. -6 It is approximately 2.6 × 10⁻⁶. When the first layer 371 is composed of polycrystalline silicon, the coefficient of linear expansion of the first layer 371 is 2.6 × 10⁻⁶. -6 It is to that extent.

[0068] Furthermore, the coefficient of thermal expansion of the first layer 371 can be adjusted, for example, by adjusting the grain boundaries according to the conditions of the CVD method when the first layer 371 is formed by the CVD method. For this reason, from the viewpoint of controlling the film thickness with high precision, it is particularly preferable that the first layer 371 be formed by the CVD method.

[0069] Furthermore, it is preferable that the Vickers hardness of the first layer 371 is higher than that of the substrate 372. A higher Vickers hardness for the first layer 371 than that of the substrate 372 improves the abrasion resistance of the nozzle surface 3710. This extends the lifespan of the nozzle plate 37. However, the Vickers hardness of the first layer 371 may be less than or equal to that of the substrate 372.

[0070] It is preferable that the Young's modulus of the first layer 371 is higher than that of the substrate 372. A higher Young's modulus of the first layer 371 than that of the substrate 372 can suppress the occurrence of crosstalk.

[0071] The Young's modulus of the first layer 371 may be less than or equal to that of the substrate 372. Furthermore, the Young's modulus of the silicon substrate 372 is approximately 130 GPa to 185 GPa. If the first layer 371 is made of polycrystalline silicon, its Young's modulus is approximately 150 GPa to 170 GPa.

[0072] Furthermore, in the first recess formation step S3, it is preferable to form the first recess N10 using the Bosch process. By forming the first recess N10 using the Bosch process, the length L1 of the first nozzle N1 can be controlled with high precision.

[0073] Furthermore, the manufacturing method for the liquid discharge head 3 includes a second recess formation step S4 and an insulating film removal step S5. By including these steps, a so-called two-stage nozzle can be formed. As a result, the discharge performance of the nozzle N can be improved compared to a single-stage nozzle. Furthermore, in conventional designs that do not have an insulating film 373, when the second nozzle N2 is formed after the first nozzle N1, there was a risk that the first nozzle N1 would be etched more than necessary due to errors in the etching rate of the second nozzle N2. In this manufacturing method, since an insulating film 373 is present, the first nozzle N1 is not etched more than necessary, and the length L1 of the first nozzle N1 can be controlled with high precision.

[0074] 2. Second Embodiment A second embodiment will now be described. In the following examples, for elements whose function is the same as in the first embodiment, the same reference numerals used in the description of the first embodiment will be reused, and detailed explanations of each will be omitted as appropriate.

[0075] Figure 9 is a cross-sectional view showing the nozzle N of the nozzle plate 37A of the second embodiment. As shown in Figure 9, the bottom surface portion 371T, which is the end of the inner wall surface 3713B of the first layer 371 constituting the first nozzle N1 on the insulating film 373 side, has a rounded shape in which the cross-sectional area asymptotically increases toward the second nozzle N2. Therefore, in the first nozzle N1, when the position closer to the insulating film 373 is called the first position P1 and the position further away from the insulating film 373 than the first position P1 is called the second position P2, the diameter at the first position P1 is larger than the diameter at the second position P2. In the illustrated example, the first position P1 is the end of the first nozzle N1 that is on the insulating film 373 side, and the second position P2 is the end of the first nozzle N1 that is on the opposite side of the insulating film 373 side.

[0076] By having a larger diameter at the first position P1 than at the second position P2, the ease with which bubbles are drawn in at the end of the first nozzle N1 on the insulating film 373 side can be reduced due to the inertance ratio between the first nozzle N1 and the second nozzle N2.

[0077] In this embodiment, in the first recess formation step S3, the bottom surface 371T of the first recess N10 is over-etched. As a result, the bottom surface 371T has a rounded shape in which the cross-sectional area asymptotically increases toward the second nozzle N2. Therefore, the diameter at the first position P1 can be made larger than the diameter at the second position P2. Thus, at the bottom surface 371T of the first nozzle N1, the ease with which air bubbles are drawn into the ink of the first nozzle N1 due to the inertance ratio between the first nozzle N1 and the second nozzle N2 can be reduced.

[0078] 3. Third Embodiment A third embodiment will now be described. In the following examples, for elements whose function is the same as in the second embodiment, the same reference numerals used in the description of the second embodiment will be reused, and detailed explanations of each will be omitted as appropriate.

[0079] Figure 10 is a cross-sectional view showing the nozzle N of the nozzle plate 37B of the third embodiment. As shown in Figure 10, in the substrate 372B of the nozzle plate 37B, the diameter of the second nozzle N2 decreases toward the first nozzle N1. In other words, the second nozzle N2 has a tapered shape that narrows toward the first nozzle N1. Because the second nozzle N2 is tapered, the ease with which bubbles are drawn in due to the inertance ratio of the first nozzle N1 and the second nozzle N2 can be reduced compared to the case where the second nozzle N2 is cylindrical.

[0080] In this embodiment, in the second recess formation step S4, a tapered shape is formed on the inner wall surface 3723B of the second recess N20, with the diameter decreasing toward the first recess N10. As a result, as described above, the second nozzle N2 is formed in a tapered shape. Therefore, the ease with which bubbles are drawn in due to the inertance ratio of the first nozzle N1 and the second nozzle N2 can be reduced. In this case, the inner wall surface 3733B of the insulating film 373B is also formed in a tapered shape, although the inner wall surface 3733B may be cylindrical.

[0081] Similar to the first embodiment, in this embodiment, it is preferable to form the first recess N10 by the Bosch process in the first recess formation step S3. In contrast, in this embodiment, it is preferable to form the second recess N20 by anisotropic etching in the second recess formation step S4.

[0082] By forming the first recess N10 using a Bosch process, the length L1 of the first nozzle N1 can be controlled with high precision, similar to the first embodiment. Furthermore, in this embodiment, the second nozzle N2 can be formed in a tapered shape by forming the second recess N20 using anisotropic etching. Therefore, the ease with which bubbles are drawn in due to the inertance ratio between the first nozzle N1 and the second nozzle N2 can be reduced.

[0083] 4. Variations The embodiments illustrated above can be modified in various ways. Specific examples of modifications that can be applied to the aforementioned embodiments are given below. Two or more embodiments arbitrarily selected from the following examples can be combined as appropriate, to the extent that they do not contradict each other.

[0084] The "liquid dispensing head" may be a circulating type head having a so-called circulation channel.

[0085] Liquid dispensing devices can be used in various types of equipment, including not only printing equipment but also facsimile machines and photocopiers. The applications of liquid dispensing devices are not limited to printing. For example, liquid dispensing devices that dispense colorant solutions are used as manufacturing equipment to form color filters for display devices such as liquid crystal display panels. Liquid dispensing devices that dispense conductive material solutions are used as manufacturing equipment to form wiring and electrodes on wiring boards. Furthermore, liquid dispensing devices that dispense solutions of organic substances related to living organisms are used, for example, as manufacturing equipment to produce biochips.

[0086] The "second recess N20" may be provided not to form the "second nozzle N2," but to form a communication passage connecting the first nozzle N1 and the pressure chamber C1, or to form a part of the pressure chamber C1.

[0087] Although the present invention has been described above based on preferred embodiments, the present invention is not limited to the embodiments described above. Furthermore, the configuration of each part of the present invention can be replaced with any configuration that performs a similar function to the embodiments described above, and any configuration can be added.

[0088] 5. Addendum From the above embodiments or modifications, for example, the following embodiments can be understood.

[0089] A method for manufacturing a liquid discharge head according to a first embodiment, which is a preferred example of the present disclosure, includes an insulating film forming step of forming an insulating film on a first surface of a substrate made of single-crystal silicon; a step of forming a first layer made of polycrystalline silicon on the insulating film by film deposition; and a first recess forming step of forming a first recess in the first layer, which is to be a first nozzle, and the bottom surface of the first recess is the insulating film.

[0090] According to this first embodiment, by forming a first layer corresponding to the first nozzle on an insulating film, the thickness of the first layer can be controlled with high precision. Therefore, the first nozzle length, i.e., the stroke length, can be controlled with high precision. In addition, by using the insulating layer as an etching stopper layer, the first nozzle length can be controlled with high precision. Furthermore, since the coefficient of thermal expansion can be made the same or close to that of the first layer and the substrate, delamination between the first layer and the substrate can be suppressed when temperature changes occur. In addition, polycrystalline silicon can be deposited with high precision compared to other materials, so variations in film thickness can be suppressed more easily.

[0091] In the method for manufacturing a liquid discharge head according to the second embodiment, which is a preferred example of the first embodiment, the coefficient of linear expansion X of the first layer satisfies the following equation (1), where Y is the coefficient of linear expansion of the substrate. |XY|<1.0×10 -6 ...(1)

[0092] According to the second embodiment, it is possible to effectively suppress the delamination of the first layer and the substrate when a temperature change occurs.

[0093] In a third embodiment of a method for manufacturing a liquid dispensing head, which is a preferred example of the first or second embodiment, the Vickers hardness of the first layer is higher than the Vickers hardness of the substrate.

[0094] The surface of the first layer is in a position that is rubbed during wiping. According to the third embodiment, abrasion resistance can be improved, thereby extending the lifespan of the nozzle plate.

[0095] In a method for manufacturing a liquid dispensing head according to a fourth embodiment, which is a preferred example of any of the first to third embodiments, the Young's modulus of the first layer is higher than the Young's modulus of the substrate.

[0096] According to the fourth embodiment, the occurrence of crosstalk can be suppressed.

[0097] In a fifth embodiment of a method for manufacturing a liquid discharge head, which is a preferred example of any of the first to fourth embodiments, the insulating film is formed in the insulating film formation step by thermal oxidation of the first surface of the substrate.

[0098] According to the fifth embodiment, the process can be simplified compared to the case in which an insulating layer is formed.

[0099] In a method for manufacturing a liquid discharge head according to a sixth embodiment, which is a preferred example of any of the first to fifth embodiments, the bottom surface of the first recess is over-etched in the first recess forming step.

[0100] According to the sixth embodiment, by over-etching, a shape with a larger diameter can be formed at the bottom surface of the first recess. Therefore, at the bottom surface of the first nozzle, the ease with which bubbles are drawn in due to the inertance ratio between the first nozzle and the second nozzle can be reduced.

[0101] A method for manufacturing a liquid discharge head according to a seventh embodiment, which is a preferred example of any of the first to sixth embodiments, comprising: a second recess forming step of forming a second recess on a second surface of the substrate opposite to the first surface, which becomes a second nozzle having a larger diameter than the first nozzle, and the bottom surface of the second recess being the insulating film; and an insulating film removal step of removing the insulating film located on the bottom surface of the first recess and the bottom surface of the second recess to penetrate the first recess and the second recess.

[0102] According to the seventh embodiment, a so-called two-stage nozzle can be formed. Therefore, the discharge performance can be improved compared to a single-stage nozzle.

[0103] In the method for manufacturing a liquid discharge head according to the eighth embodiment, which is a preferred example of the seventh embodiment, in the second recess formation step, a tapered shape is formed on the inner wall surface of the second recess, with the diameter decreasing toward the first recess.

[0104] According to the eighth aspect, the ease with which bubbles are drawn in due to the inertance ratio of the first nozzle and the second nozzle can be reduced.

[0105] In the method for manufacturing a liquid discharge head according to the ninth embodiment, which is a preferred example of the eighth embodiment, the first recess is formed by a Bosch process in the first recess formation step, and the second recess is formed by anisotropic etching in the second recess formation step.

[0106] According to the ninth aspect, the length of the first nozzle can be controlled with high precision by forming the first recess using a Bosch process. Furthermore, a tapered shape can be formed on the second nozzle by forming the second recess using anisotropic etching. Thus, the ease with which bubbles are drawn in due to the inertance ratio between the first nozzle and the second nozzle can be reduced.

[0107] A liquid discharge head according to a tenth embodiment, which is a preferred example of the present disclosure, is a nozzle plate used in a liquid discharge head, comprising: a first layer made of polycrystalline silicon; a second layer made of single-crystal silicon; and an insulating film provided between the first layer and the second layer, wherein the first layer has a first nozzle, and the second layer has a second nozzle that penetrates the first nozzle through an opening in the insulating film.

[0108] According to the tenth embodiment, since the first layer corresponding to the first nozzle is polycrystalline silicon, the first nozzle length, i.e., the stroke length, can be controlled with high precision by the thickness of the deposited first layer. Compared to the conventional method of forming the first and second nozzles from a single silicon substrate, the first nozzle length can be controlled with high precision by using the deposited first layer. In addition, by using an insulating layer as an etching stopper layer, the first nozzle length can be controlled with high precision. As a result, it is easier to achieve the ideal first nozzle length and individual differences in the first nozzle length can be reduced. Therefore, the first nozzle length can be controlled with high precision.

[0109] In the liquid discharge head of the 11th embodiment, which is a preferred example of the 10th embodiment, when the position close to the insulating film is designated as the first position and the position further from the insulating film than the first position is designated as the second position, the diameter at the first position is larger than the diameter at the second position.

[0110] According to the eleventh embodiment, the ease with which bubbles are drawn in due to the inertance ratio between the first nozzle and the second nozzle can be reduced at the insulating film side end of the first nozzle.

[0111] In the liquid dispensing head of the twelfth embodiment, which is a preferred example of the tenth or eleventh embodiment, the diameter of the second nozzle decreases toward the first nozzle.

[0112] According to the twelfth embodiment, since the second nozzle has a tapered shape, the ease with which bubbles are drawn in due to the inertance ratio of the first nozzle and the second nozzle can be reduced. [Explanation of Symbols]

[0113] 3...Liquid discharge head, 5...Piezoelectric element, 31...Flow channel forming substrate, 32...Pressure chamber substrate, 33...Diaphragm, 37...Nozzle plate, 51...Lower electrode, 52...Upper electrode, 53...Piezoelectric layer, 100...Liquid discharge device, 371...First layer, 371T...Bottom surface, 372...Substrate, 373...Insulating film, 3710...Nozzle surface, 3713...Inner wall surface, 3721...First surface, 3722...Second surface, 3723...Inner wall surface, 3733...Inner wall surface, N...Nozzle, N1...First nozzle, N10...First recess, N2...Second nozzle, N20...Second recess, N3...Boundary, P1...First position, P2...Second position, S1...Insulating film formation process, S2...First layer deposition process, S3...First recess formation process, S4...Second recess formation process, S5...Insulating film removal process.

Claims

1. In a manufacturing method for producing a liquid dispensing head, An insulating film formation step in which an insulating film is formed on the first surface of a substrate made of single crystal silicon, A step of forming a first layer made of polycrystalline silicon on the insulating film by deposition, The first layer includes a first recess forming step of forming a first recess which is a first nozzle, the bottom surface of which is the insulating film, A method for manufacturing a liquid dispensing head, characterized by the following:

2. In the method for manufacturing a liquid discharge head according to claim 1, The coefficient of thermal expansion X of the first layer satisfies the following equation (1), where Y is the coefficient of thermal expansion of the substrate: |X-Y|<1.0×10^(-6)...(1) A method for manufacturing a liquid dispensing head, characterized by the following:

3. In the method for manufacturing a liquid discharge head according to claim 1, The Vickers hardness of the first layer is higher than that of the substrate. A method for manufacturing a liquid dispensing head, characterized by the following:

4. In the method for manufacturing a liquid discharge head according to claim 1, The Young's modulus of the first layer is higher than that of the substrate. A method for manufacturing a liquid dispensing head, characterized by the following:

5. In a method for manufacturing a liquid dispensing head according to any one of claims 1 to 4, In the insulating film formation step, the insulating film is formed by thermal oxidation of the first surface of the substrate. A method for manufacturing a liquid dispensing head, characterized by the following:

6. In a method for manufacturing a liquid dispensing head according to any one of claims 1 to 4, In the first recess formation step, the bottom surface of the first recess is over-etched. A method for manufacturing a liquid dispensing head, characterized by the following:

7. In a method for manufacturing a liquid dispensing head according to any one of claims 1 to 4, A second recess forming step is to form a second recess on the second surface of the substrate opposite to the first surface, which is a second nozzle with a larger diameter than the first nozzle, and the bottom surface of the second recess is the insulating film. The process includes removing the insulating film located on the bottom surface of the first recess and the bottom surface of the second recess, thereby removing the insulating film that penetrates the first recess and the second recess. A method for manufacturing a liquid dispensing head, characterized by the following:

8. In the method for manufacturing a liquid discharge head according to claim 7, In the second recess formation step, a tapered shape is formed on the inner wall surface of the second recess, with the diameter decreasing toward the first recess. A method for manufacturing a liquid dispensing head, characterized by the following:

9. In the method for manufacturing a liquid discharge head according to claim 8, In the first recess formation step, the first recess is formed by the Bosch process, In the second recess formation step, the second recess is formed by anisotropic etching. A method for manufacturing a liquid dispensing head, characterized by the following:

10. It comprises a first layer made of polycrystalline silicon, a second layer made of single-crystal silicon, and an insulating film provided between the first and second layers. The first layer has a first nozzle, The second layer has a second nozzle that penetrates the first nozzle through an opening in the insulating film, A liquid dispensing head characterized by the following features.

11. In the liquid dispensing head according to claim 10, In the first nozzle, when a position close to the insulating film is defined as the first position and a position further from the insulating film than the first position is defined as the second position, the diameter at the first position is larger than the diameter at the second position. A liquid dispensing head characterized by the following features.

12. In the liquid dispensing head according to claim 10 or claim 11, The diameter of the second nozzle decreases toward the first nozzle. A liquid dispensing head characterized by the following features.

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