The present invention relates to a liquid ejection head and a method of manufacturing the same.
In a liquid ejection head that ejects a liquid such as ink, the liquid in a flow path to an ejection orifice that ejects the liquid often thickens due to evaporation from the ejection orifice of a volatile component in the liquid. In this case, ejection speed of liquid droplets may change, or failure in ejection of liquid droplets may be caused. As a countermeasure to solve such liquid thickening phenomenon as mentioned above, a method of flowing a fresh liquid, that has not thickened, in the flow path to the ejection orifice is known. For flowing such a fresh liquid in a flow path, a method of using a micro-pumping phenomenon such as alternating-current electro-osmotic flow (ACEO) is known (International Publication No. WO2013/130039).
The method of manufacturing a liquid ejection head of the present invention includes steps of:
A liquid ejection head of the present invention includes a substrate, an energy generating element provided on the substrate for ejecting a liquid, an integrated circuit provided on the substrate for driving the energy generating element, a flow path forming member which has an ejection orifice for ejecting the liquid and is provided such that a flow path for the liquid is formed between the substrate and the flow path forming member, and an electrode for generating a flow of the liquid in the flow path, wherein the electrode is formed over high and low of a stepped shape formed by the integrated circuit on the substrate.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings.
In a method utilizing a micro-pump function as described in the International Publication No. WO2013/130039, liquid circulation (liquid transfer) efficiency is improved by providing a stepped shape to the electrode for generating a liquid flow. As a result, the reliability of liquid ejection can be improved.
However, in this method, since a step of forming a member for providing a stepped shape to the electrode is performed separately, the manufacturing cost of the liquid ejection head is increased.
In contrast, the method of manufacturing a liquid ejection head of the present invention does not need a separate step of forming a member for providing a stepped shape to an electrode for generating a liquid flow, hence capable of providing a liquid ejection head at low cost.
The method of manufacturing a liquid ejection head of the present invention includes steps of: forming an energy generating element for ejecting a liquid (hereinafter referred to as “the step of forming the energy generating element”) on a substrate; forming an integrated circuit for driving the energy generating element (hereinafter referred to as “the step of forming the integrated circuit”) on the substrate; forming a supply port for the liquid (hereinafter referred to as “the step of forming a supply port”) such that the supply port penetrates through the substrate; forming an electrode for generating a liquid flow (hereinafter referred to as “the step of forming the electrode)”; and forming a flow path forming member having an ejection orifice for ejecting the liquid (hereinafter referred as “the step of forming the flow path forming member”) such that a flow path for the liquid is formed between the substrate and the flow path forming member, wherein, in the step of forming the electrode, the electrode is formed over high and low of a stepped shape on the substrate, the stepped shape being formed in at least one step selected from the group consisting of the step of forming the energy generating element, the step of forming the integrated circuit and the step forming the supply port.
In the method of the present invention, the electrode is formed over high and low of a stepped shape on the substrate. The stepped shape is formed in at least one step selected from the group consisting of the step of forming the energy generating element, the step of forming the integrated circuit and the step of forming the supply port. Since the electrode is formed by utilizing a stepped shape which is formed in a step to be performed necessarily for manufacturing a liquid ejection head, the manufacturing cost can be reduced.
The liquid ejection head according to the present invention includes a substrate, an energy generating element, an integrated circuit, a flow path forming member and an electrode. The energy generating element is formed on the substrate and utilized for ejecting a liquid. The integrated circuit is formed on the substrate to drive the energy generating element. The flow path forming member has an ejection orifice for ejecting the liquid and forms a flow path for the liquid between the substrate and the flow path forming member. The electrode generates a flow of the liquid and is formed over high and low of a stepped shape formed by the integrated circuit on the substrate.
The electrode in the liquid ejection head according to the present invention is formed by utilizing a stepped shape formed by the integrated circuit on the substrate. Therefore, in the liquid ejection head of the present invention, a special member for providing a stepped shape to the electrode is not used. Therefore, in the above method of manufacturing a liquid ejection head, it is not required to separately form an additional member utilized for forming a stepped shape, and hence a liquid ejection head of the present invention can be manufactured with low cost.
Now, the liquid ejection head according to an embodiments of the present invention is described with reference to the attached drawings. Explained specifically in each of the embodiments in the below are a number of structures for an inkjet recording head from which ink as a liquid is ejected. An inkjet recording head mentioned as one embodiment of the present invention can be used for an apparatus such as a printer, a copying machine, a facsimile machine having a communication system, a word processor having a printer unit and the like and an industrial recording apparatus incorporated into various processing apparatuses. However, the present invention is not limited to a liquid ejection head using ink as a liquid. The liquid ejection head of the present invention may be used in performing, for example, biochip fabrication and electronic circuit printing.
Arranged on a substrate 1 are energy generating elements 5 and an integrated circuit including transistors (not shown) for driving the energy generating elements 5, wiring lines 10 and an insulating film 13, etc. The substrate 1 may be made of silicon. The wiring lines 10 may be power lines or signal lines of the integrated circuit. The wiring lines 10 may comprise Al, Cu, W, Ta, Ir, Au, compounds thereof, polysilicon, etc. The wiring lines 10 may comprise one thereof or two or more thereof. In this embodiment, the wiring lines 10 are made of Al. The wiring lines 10 in this embodiment constitute an uppermost wiring layer, and therefore the insulating film 13 formed on the wiring lines 10 is not flattened by CMP or like others. The insulating film 13 may be a passivation film, an SiO film, a BPSG (Boro-Phospho Silicate Glass) film, an SOG (Spin On Glass) film or a field oxide film. The insulating film 13 in this embodiment is a passivation film formed of a SiN film or like others. The energy generating elements 5 and the integrated circuit can be formed by a common semiconductor process.
The electrodes 9 for generating a flow of ink are formed over high and low of a stepped shape formed by the wiring lines 10 on the substrate 1. The electrodes 9 may be composed of a metal material such as Au, Pt, Ta, Ir, Ti, W, compounds thereof, etc. The electrodes 9 are connected to an AC power source 15 which supplies an electric power required for generating a flow of ink from the AC power source 15 to the electrodes 9. The electrodes 9 are formed according to the following steps. For example, after forming a layer to become the electrodes 9 over the whole surface of the substrate 1, a resist is applied onto the layer. Then, after removing the resist on areas other than the portions for forming the electrodes 9, the electrodes are is formed over high and low of a stepped shape on the substrate 1 by pattering the layer by means of wet etching.
In the substrate 1, supply ports 7 for ink are formed such that each of them penetrates through the substrate 1 and communicates with a flow path 6. The supply ports 7 can be formed by performing dry etching from the surface of the substrate 1 on the side on which the insulating film 13 is formed. The supply port 7 may be formed to penetrate through the substrate 1 by performing dry etching also from the side opposite to the side on which the insulating film 13 is formed.
On the substrate 1 is formed a flow path forming member 4 having ejection orifices 2 for ejecting ink such that flow paths 6 for the ink are formed between the substrate 1 and the flow path forming member 4. Ink supplied into the flow paths 6 from the supply ports 7 is ejected from the ejection orifices 2 by an energy generated by the energy generating elements 5 to a recording medium onto which recording is performed. The area between each energy generating element 5 and the corresponding ejection orifice 2 functions as a pressure chamber. Each pressure chamber communicates with a corresponding flow path 6 and an energy generating element 5 is provided in the pressure chamber. The flow path forming member 4 can be formed, for example, by the following steps. The flow path forming member 4 is formed by laminating a photosensitive resin film to the substrate 1 and the insulating film 13, followed by exposure and development, and by repeating these steps.
The electrodes 9 generate a flow of ink flow by alternating-current electro-osmotic flow to circulate the ink in the flow paths 6. As shown in
In the method of manufacturing an inkjet recording head according to this embodiment, the electrodes 9 are formed over high and low of a stepped shape formed in the step of forming the integrated circuit. Specifically, the electrodes 9 are formed by utilizing stepped shapes of wiring lines 10 formed in the integrated circuit forming step. Therefore, since it is not required to separately perform an additional step for forming a stepped shape for the electrodes 9, an inkjet recording head with a high performance micro-pump can be manufactured at low cost.
In this embodiment, the electrodes 9 are formed by utilizing stepped shapes of the wiring lines 10. However, electrodes 9 may be formed by utilizing not only stepped shapes of the wiring lines 10, but any other stepped shapes formed in the step of forming an integrated circuit can be utilized. For example, it is possible to use a stepped shape formed in opening the insulating film 13 formed on the substrate 1. For example, it is possible to use a stepped shape formed in opening a field oxide film for forming a transistor. Further, it is possible to use a stepped shape formed in forming a through hole for connecting wiring lines 10 or for connecting a wiring line 10 and the substrate 1.
The inkjet recording head according to this embodiment can be manufactured by, for example, the method mentioned below. A laminated film comprised of an energy generating element film 5a and a film made of Al or like others which is to form wiring lines is formed on the substrate 1 on which an insulating film 13 is formed. Next, wiring lines 10 are patterned at a time by dry etching. After that, a resist is applied onto the laminated film, then an opening is formed only on portions for forming the energy generating elements 5, and only the film layer to form the wiring lines 10 of the laminated film is removed by wet etching. In this step, etching can proceed in a direction parallel to the substrate 1 by gradually peeling off the end portions of each resist opening from a film layer to form a wiring line 10, and the wiring line 10 is tapered on both the ends of each energy generating element 5. By providing tapers as mentioned above, current concentration is mitigated in the interface between the energy generating elements 5 and the wiring lines 10, and occurrence of disconnection is suppressed. Further, covering property of the insulating film 13 on the energy generating elements 5 is improved, and insulation reliability is improved. After that, in the same manner as in the first embodiment, the electrodes 9 are formed over high and low of stepped shapes formed by the wiring lines 10, while supply ports 7 and a flow path forming member 4 are formed.
In this embodiment, as in the first embodiment, while each of the electrodes 9 is formed with a stepped shape formed by utilizing a stepped shape formed by a wiring line 10, the stepped shape is formed at the same time as in forming the energy generating elements 5. Therefore, the stepped portions of the electrodes 9 can be also tapered. Since the stepped shapes are tapered, the electrodes 9 are easily patterned and short-circuiting between the electrodes 9 caused by etching failure is prevented. In the same manner as for the energy generating elements 5, since covering property of the insulating film 13 on the wiring lines 10 is improved, insulation reliability between the wiring lines 10 and the electrodes 9 is secured. As mentioned above, by forming the electrodes 9 by utilizing the stepped shapes in forming the energy generating elements 5, a liquid ejection head, in which a micro-pump is provided, and which has a higher electrical reliability can be manufactured.
The inkjet recording head of this embodiment can be manufactured by, for example, the method as mentioned below. As shown in
Next, as shown in
In this embodiment, the hollows 17 are formed at a time when the openings on the PAD electrodes 16 are formed in the insulating film 13, and the stepped shapes of the electrodes 9 are formed by utilizing the stepped shapes of the hollows 17. However, stepped shapes formed in forming the supply ports 7 may alternatively be utilized. For example, the hollows 17 are formed in the surface of the insulating film 13 at a time in the step of forming the supply ports 7 by forming openings through the substrate 1 by dry etching. The stepped shapes of the electrodes 9 may be formed by utilizing these hollows 17.
Further, in this embodiment, hollows 17 forming the stepped shapes are etched at a time when openings are formed in the insulating film 13 on the PAD electrodes 16 by using the wiring lines 10 as an etch stop layer. By performing etching using the wiring lines 10 as an etch stop layer, the depth of the hollows 17 can be controlled with high precision.
The inkjet recording head according to this embodiment can be manufactured by, for example, the method mentioned as follows. First, as shown in
Next, as shown
In this embodiment, the electrodes 9 can be made of a metal, and the flow path forming member 4 can be made of a resin. In this case, when the electrodes 9 above the substrate 1 come into contact with the flow path forming member 4, since adhesion strength between a resin and a metal is low, there is a possibility that the flow path forming member 4 peels off from the substrate 1 by the stress due to a difference in linear thermal expansion coefficient. However, in this embodiment, as shown in
As mentioned above, in the structure of this embodiment, the electrodes 9 can be formed with high accuracy, and further, the desired AC voltage waveform can be applied to the electrodes 9 by suppressing a voltage drop. Further, while adhesion between the flow path forming member 4 and the substrate 1 is ensured, it is possible to manufacture an inkjet recording head provided with a micro-pump with high performance and high reliability, at low cost.
In this embodiment, when openings are formed in the insulating film 13 on the PAD electrodes 16, hollows 17 are formed at a time using wiring lines 10 as an etch stop layer, and stepped shapes of the electrodes 9 are formed by utilizing stepped shapes of the hollows 17, or by utilizing stepped shapes formed in the step of forming the supply ports 7. For example, in the step of forming the supply ports 7, when openings are formed in the substrate 1 by dry etching, hollows 17 can be formed at the same time, using wiring lines 10 as an etch stop layer in the surface of the insulating film 13, and stepped shapes of the electrodes 9 can be formed by utilizing stepped shapes of the hollows 17.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2017-186671, filed Sep. 27, 2017, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
---|---|---|---|
2017-186671 | Sep 2017 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
20150109371 | Ishida | Apr 2015 | A1 |
20180154635 | Nakakubo | Jun 2018 | A1 |
Number | Date | Country |
---|---|---|
2013130039 | Sep 2013 | WO |
Entry |
---|
U.S. Appl. No. 16/136,550, filed Sep. 20, 2018, Kudo et al. |
Number | Date | Country | |
---|---|---|---|
20190092019 A1 | Mar 2019 | US |