JP2015217584A - Base substance for liquid discharge head, liquid discharge head, liquid discharge device, and manufacturing method of base substance for liquid discharge head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base substance for a liquid discharge head which achieves excellent durability and long life while forming a high density structure of an electrothermal transducer and electrode wiring, and to provide the liquid discharge head, a liquid discharge device, and a manufacturing method of the base substance for the liquid discharge head.SOLUTION: At one side of an insulation layer 15, first electrode wiring 13 for connecting a heater 21 positioned at the other side of the insulation layer 15 with a drive circuit is formed. A space 14 serving as a heat insulation part, which inhibits heat conduction from the heater 21 to the first electrode wiring 13, is formed in a portion in the insulation layer 15 at which the heater 21 faces the first electrode wiring 13.

Description

  The present invention relates to a liquid discharge head substrate provided in a liquid discharge head capable of discharging a liquid such as ink using an electrothermal conversion element, a liquid discharge head including the liquid discharge head substrate, a liquid discharge apparatus, and a liquid discharge head The present invention relates to a method for manufacturing a substrate for an automobile.

  As a liquid ejection head capable of ejecting liquid using an electrothermal conversion element, there is an ink jet recording head capable of ejecting ink. This recording head foams ink by the heat generated by the electrothermal conversion element, and uses the foaming energy to eject ink from the ejection port at the tip of the ink flow path. A recording head substrate (liquid discharge head substrate) provided in such a recording head includes an electrothermal conversion element and an electrode wiring for connecting the electrothermal conversion element to a drive circuit. A nozzle capable of discharging ink is configured by the flow path, the discharge port, and the like.

  In Patent Document 1, in order to form a plurality of nozzles with high density, the electrothermal conversion element and the electrode wiring are formed separately on one side and the other side of the insulating layer, and the electrothermal conversion element and the electrode wiring are formed. An electrode wiring structure for increasing the density is described.

Japanese Patent No. 3311198

  However, in the electrode wiring structure described in Patent Document 1, since the electrothermal conversion element and the electrode wiring are opposed to each other through the insulating layer, a current for driving the electrothermal conversion element flows through the electrode wiring. The heat generated by the electrothermal transducer is easily transferred to the electrode wiring. Therefore, electromigration may occur in the electrode wiring. For example, when a hillock (protrusion) generated in Al constituting the electrode wiring grows toward the electrothermal conversion element, a convex portion is generated on the surface of the electrothermal conversion element, and cavitation is concentrated on that part, Durability may be impaired. When a refractory metal such as Ta, W, Cr, Ti, Mo, or an alloy thereof is laminated as a barrier metal on an Al electrode wiring, hillock growth due to electromigration can be suppressed. However, the generation of voids (voids) that occur in the electrode wiring cannot be suppressed, and there is a risk of failure of the electric circuit.

  An object of the present invention is to provide a long-life liquid discharge head substrate, a liquid discharge head, a liquid discharge device, and a liquid discharge head substrate that are excellent in durability while increasing the density of electrothermal conversion elements and electrode wirings. It is to provide a manufacturing method.

  The substrate for a liquid discharge head of the present invention is a substrate for a liquid discharge head provided in a liquid discharge head capable of discharging a liquid by heat generation of an electrothermal conversion element, and is provided on one side of the insulating layer and on the other side of the insulating layer. A first electrode wiring for connecting the electrothermal conversion element positioned to a drive circuit is formed, and the electrothermal conversion is provided in a portion of the insulating layer facing the electrothermal conversion element and the first electrode wiring. A heat insulating portion that suppresses heat conduction from the element to the first electrode wiring is provided.

  According to the present invention, the electrothermal conversion element and the electrode wiring are divided into one side and the other side of the insulating layer to increase the density thereof, and the heat insulating portion is provided at the facing portion between the electrothermal conversion element and the electrode wiring. By providing, the influence on the electrode wiring due to the heat generation of the electrothermal conversion element can be suppressed. As a result, it is possible to provide a long-life base for a liquid discharge head, a liquid discharge head, a liquid discharge apparatus, and a method for manufacturing a liquid discharge head base having excellent durability.

1 is a front view of a recording apparatus incorporating a recording head according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view of the recording head in FIG. 1. FIG. 3 is an enlarged perspective view of a partial cutout of the discharge element in FIG. 2. FIG. 4 is a schematic plan view of a recording head substrate in the ejection element of FIG. 3. It is sectional drawing which follows the VV line of FIG. It is sectional drawing which follows the VI-VI line of FIG. It is sectional drawing of the base for recording heads in the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are application examples as a recording head that ejects ink as a liquid and an inkjet recording apparatus that records an image using the recording head.

(First embodiment)
FIG. 1 is a front view schematically showing a full-line type inkjet recording apparatus (liquid ejection apparatus) 120 capable of recording an image using a recording head (liquid ejection head) 110.

  The recording apparatus 120 includes a transport unit 121 for transporting a recording medium W such as paper in the direction of arrow Y, and a feeding unit 122 for supplying the recording medium W to the transport unit 121. . In addition, six recording heads 110 (110Y, 110LM, 110M, 110LC, 110C, and 110K) are attached to the recording apparatus 120 of the present embodiment in a replaceable manner. These recording heads use yellow (Y), light magenta (LM), magenta (M), light cyan (LC), cyan (C), and black (K) ink from the corresponding ink cartridge (liquid storage container) 123. (Liquid) is supplied. The six recording heads 110 are arranged at regular intervals along the conveyance direction of the recording medium W, and each of the recording heads 110 has a plurality of ejection ports capable of ejecting ink in the conveyance direction of the recording medium W. They are arranged in the intersecting direction (in the present embodiment, the orthogonal direction).

  Further, the recording apparatus 120 is provided with a recovery unit 124 that performs a recovery process for maintaining a good ink discharge state of the recording head 110. The recovery process includes a process of sucking or discharging ink that does not contribute to recording from the discharge port, a preliminary discharge that discharges ink that does not contribute to recording from the discharge port, and the discharge port surface of the recording head 110 (the discharge port is formed). Wiping process). The recording device 120 is provided with an operation panel unit 125 for operating the recording device 120.

  FIG. 2 is an exploded perspective view of the recording head 110.

  The bottom of the recording head 110 is constituted by a ceramic plate 100. On the ceramic plate 100, as will be described later, a discharge element 101 having a plurality of heaters (electrothermal conversion elements), a common liquid chamber, a flow path, a discharge port, and the like, and an electric wiring board 102 are arranged. Has been. The discharge element 101 and the electric wiring board 102 are electrically connected by wire bonding. Hereinafter, a portion including an ink (liquid) discharge port and a flow path communicating with the discharge port is also referred to as a “nozzle”. Each nozzle is provided with a heater (electrothermal conversion element) as a discharge energy generating element for generating discharge energy used for ink discharge. Ink is supplied from the ink cartridge 123 into the common liquid chamber formed in the recording head 110 through the liquid introduction path provided in the flow path forming member 103. By causing the heater as a discharge energy generating element to generate heat and causing the ink to foam, the ink can be discharged from the discharge port using the foaming energy.

  FIG. 3 is a partially cutaway perspective view of a portion in the vicinity of the nozzle in the discharge element 101.

  The recording head substrate (liquid discharge head substrate) 30 is provided with a plurality of layers and electrode wirings, which will be described later. In addition, the substrate 30 is provided with a plurality of heaters (electrothermal conversion elements) 21 for heating and foaming the ink, and electrode wiring for energizing the heaters 21 is connected to the heater 21. . A drive circuit (not shown) including a switching transistor for controlling energization to the heater 21 is connected to one of the electrode wirings. The switching transistor is driven and controlled by an IC composed of a circuit such as a control gate element, and controls the heater 21 in accordance with a signal from the recording device 120.

  The heater 21 is formed so as to correspond to each of the plurality of flow paths 23. One end of each flow path 23 communicates with the corresponding discharge port 24, and the other end of each flow path 23 communicates with the common liquid chamber 25. The flow path 23 is surrounded by the base body 30, the flow path wall 20, and the top plate 22 and has a tubular shape.

  4 is a plan view of the main part of the substrate 30, FIG. 5 is a cross-sectional view taken along the line VV of FIG. 4 located on the heater 21, and FIG. It is sectional drawing which follows the -VI line.

  In the present embodiment, the recording head substrate 30 includes a heat storage layer 12, a lower layer (wiring portion) 13 a of the first electrode wiring 13, an upper layer (barrier metal) 13 b of the first electrode wiring 13 on the silicon substrate 11, and It has a laminated structure in which the heating resistor layer 16a is formed. The heat storage layer 12 is made of a thermal oxide film, the lower layer 13a is made of Al, Al-Si, Al-Cu, etc., the upper layer 13b is made of a refractory metal such as Ta, W, Cr, Ti, Mo, and the insulating layer 15 is made of SiO. It consists of a film or a SiN film. The heating resistance layer 16a is made of a TaSiN film or the like, and a part thereof forms the heater 21. A space 14 located on the first electrode wiring 13 side is formed in the portion of the insulating layer 15 corresponding to the heater 21 as shown in FIG. Further, the upper layer 16b of the second electrode wiring made of Al, Al—Si, Al—Cu or the like is laminated on the portion of the heating resistance layer 16a other than the region corresponding to the heater 21, as shown in FIG. The second electrode wiring 16 is formed together with the heating resistance layer 16a. Further, a protective film 17 made of an SiO film or an SiN film, and an anti-cavitation film 18 for protecting the protective film 17 from chemical and physical impacts accompanying the heat generated by the heater 21 are formed.

  A flow path wall 20 is disposed on the surface of the recording head substrate 30 thus configured, that is, on the upper surface of the anti-cavitation film 18. Furthermore, a top plate 22 is provided on the upper surface of the flow path wall 20, whereby a plurality of flow paths 23 are formed adjacent to each other at high density. One or more heaters 21 are formed for each flow path 23. In this example, one heater 21 is formed for each flow path 23.

  Next, an example of a method for manufacturing the recording head substrate 30 will be described.

  First, a heat storage layer 12 made of a 1.12 μm thermal oxide film is formed on a Si (silicon) substrate 11 made of single crystal silicon by a thermal oxide film method, a CVD method or the like. Next, an AlSi layer having a thickness of 1 μm is formed on the heat storage layer 12 by sputtering. Thereafter, a refractory metal made of Ti (titanium) or the like is laminated as a barrier metal, and the first electrode wiring 13 (13a, 13b) is formed by photolithography and etching. Next, a 0.9 μm-thick insulating layer 15 made of SiO or the like is formed by plasma CVD or the like, and through holes (not shown) are formed in the insulating layer 15 by etching.

  For the portion of the insulating layer 15 corresponding to the heater 21, the space 14 is formed as follows. That is, first, a 0.5 μm-thick SiO layer is formed by plasma CVD. Next, the SiO layer in the portion forming the space 14 is removed by photolithography and etching. Thereafter, a SiN film serving as a removable sacrificial layer is formed by plasma CVD so as to fill a portion corresponding to the space 14 formed by etching. Next, the SiO layer is cut to 0.45 μm by etch back or CMP (chemical mechanical polishing). Further, a 0.45 μm SiO layer corresponding to the remaining film thickness is formed thereon by plasma CVD. Thereafter, the space 14 is formed in the remaining SiO layer by removing only the sacrificial SiN film with hot phosphoric acid. In order to remove this sacrificial layer, it is necessary to connect all the spaces 14 to the outer periphery. The form for connecting the space 14 and the space 14 and connecting the space 14 and the outer periphery is arbitrary. For example, the space 14 and the space 14 may be connected as they are, or the structural strength may be increased by leaving an insulating layer in a columnar shape between the space 14 and the space 14.

Next, the heating resistor layer 16a made of TaSiN is formed by a reactive sputtering method using N ₂ gas on the Ta—Si alloy target. Further, an AlCu film 16b having a film thickness of 0.4 μm is formed on the heating resistance layer 16a by a sputtering method, and the second electrode wiring 16 is formed by using a photolithography method and etching.

  The heater (electrothermal conversion element) 21 is formed as follows. That is, the heater 21 is formed by etching only the AlCu film 16b corresponding to the heater 21 in the second electrode wiring 16 (16a, 16b). Next, a protective film 17 made of SiN and having a thickness of 0.5 μm is formed by plasma CVD, and a cavitation-resistant film 18 made of a Ta film having a thickness of 0.23 μm is further formed by sputtering.

  Thus, the recording head substrate 30 is produced.

  In the present embodiment, the second electrode wirings 16 (16a, 16b) connected to the respective heaters 21 are the first electrode wirings 13 (13a, 13b) located below the insulating layer 15 through the through holes. Connected to. Therefore, the recording head substrate 30 according to the present embodiment is greatly different from the case where the first and second electrode wirings 13 (13a, 13b) and 16 (16a, 16b) are formed on the same plane. It is possible to increase the mounting density. This is suitable as a recording head mounted on a recording apparatus that requires high image quality.

  In the recording head substrate 30 of this embodiment, a space 14 is formed in the insulating layer 15 between the heater 21 and the first electrode wiring 13 (13a, 13b) immediately below the heater 21. . Therefore, the heat generated in the heater 21 is difficult to be transmitted to the first electrode wiring 13 (13a, 13b) that is energized. As a result, the occurrence of electromigration in the first electrode wiring 13 (13a, 13b) is suppressed, and the failure rate of the recording head substrate 30 can be reduced and the life can be greatly improved. Specifically, generation of both hillocks (projections) and voids (voids) due to electromigration can be suppressed.

  The average lifetime due to electromigration can be expressed by the following equation.

MTF: Average life A: Constant related to wiring material, structure, dimensions, etc. J: Current density n: Constant related to current density Ea: Activation energy k: Boltzmann constant T: Absolute temperature Current density as expressed by the above equation J and absolute temperature T are factors that shorten the average life MTF. As described above, in the present embodiment, the space 14 is formed between the heater 21 that generates heat and the first electrode wiring 13 (13a, 13b) immediately below the heater 21. Therefore, the heat from the heater 21 is not easily transmitted to the first electrode wiring 13 that is energized, and the average life FTM of the first electrode wiring 13 immediately below the heater 21 is improved as compared with the conventional case. It will be. When the space 14 is not formed in the insulating layer 15 between the heater 21 and the first electrode wiring 13 immediately below the heater 21 as in the prior art, the heater is turned on when the first electrode wiring 13 is energized. Heat from 21 is transmitted to the first electrode wiring 13 through the insulating layer 15. Therefore, the average life FTM of the first electrode wiring 13 may be reduced.

  In the present embodiment, an insulating film 15a which is a part of the insulating layer 15 is located between the heater 21 and the space 14 as shown in FIG. Thus, since the space 14 is formed on the first electrode wiring 13 (13a, 13b) side via the insulating film 15a, a stable structure is obtained. If the space 14 is formed immediately below the heater 21, the heater 21 floats on the space 14, resulting in an unstable structure.

  As described above, the heat of the heater 21 is hardly transmitted to the first electrode wiring 13, the occurrence of electromigration in the first electrode wiring 13 can be suppressed, and the lifetime can be increased. In addition, the generation of both hillocks (projections) and voids (voids) due to electromigration can be suppressed, so that the barrier metal of refractory metal laminated to suppress the generation of hillocks can be reduced, and manufacturing Costs can also be reduced. In order to form a plurality of nozzles with high density, the heater 21 and the first electrode wiring 13 are formed separately on one side and the other side of the insulating layer 15, so that the heater 21 and the first electrode wiring 13 are formed. Can be deployed in high density.

(Second Embodiment)
FIG. 7 is an explanatory view of the recording head substrate 30 according to the second embodiment of the present invention, and is a cross-sectional view of a portion located on the heater 21 as in FIG. 5 described above. In the first embodiment, the space 14 in the insulating layer 15 is formed on the first electrode wiring 13 side. In the present embodiment, the space 14 in the insulating layer 15 is formed between the heater 21 and the first electrode wiring 13 so as not to be in contact therewith.

  According to the present embodiment, as in the first embodiment, the heat generated when the heater 21 generates heat is less likely to be transmitted to the first electrode wiring 13, thereby realizing a longer life.

(Other embodiments)
In the above-described embodiment, the space 14 is formed in the insulating layer 15 at a portion where the heater 21 and the first electrode wiring 13 are opposed to each other as a heat insulating portion for suppressing heat conduction from the heater 21 to the first electrode wiring 13. Formed. However, the heat insulating portion is not specified only in the space 14, and may be formed by a member having a lower thermal conductivity than the insulating layer 15, for example. Further, an inert gas or the like may be put in the space 14. In short, it is only necessary that heat conduction from the heater 21 to the first electrode wiring 13 can be suppressed.

  Further, the present invention is widely used as a liquid discharge head substrate provided in a liquid discharge head capable of discharging various liquids, a liquid discharge head including the liquid discharge head substrate, a liquid discharge apparatus, and a method for manufacturing a liquid discharge head substrate. Can be applied. The present invention also provides a liquid ejection apparatus that performs various processes (recording, processing, application, irradiation, reading, inspection, etc.) on various media (sheets) using a liquid ejection head capable of ejecting liquid. It can also be applied to. The medium (including the recording medium) includes various media to which a liquid containing ink is applied regardless of the material, such as paper, plastic, film, fabric, metal, and flexible substrate.

DESCRIPTION OF SYMBOLS 11 Silicon substrate 13 1st electrode wiring 13a Wiring layer of 1st electrode wiring 13b Barrier metal layer 14 Space 15 Insulating layer 16 2nd electrode wiring 16a Heating resistance layer 16b Wiring layer of 2nd electrode wiring 21 Electrothermal conversion Element (heater)
24 discharge port 30 recording head substrate (liquid discharge head substrate)

Claims (10)

A base for a liquid discharge head provided in a liquid discharge head capable of discharging liquid by heat generation of an electrothermal conversion element,
A first electrode wiring for connecting the electrothermal conversion element located on the other side of the insulating layer to a drive circuit is formed on one side of the insulating layer,
A heat insulating part for suppressing heat conduction from the electrothermal conversion element to the first electrode wiring is provided in a portion of the insulating layer facing the electrothermal conversion element and the first electrode wiring. Substrate for liquid discharge head.   The substrate for a liquid discharge head according to claim 1, wherein the heat insulating portion is formed of a member having a lower thermal conductivity than the insulating layer.   The substrate for a liquid discharge head according to claim 1, wherein the heat insulating portion is a space.   The liquid discharge head substrate according to claim 3, wherein the space is in contact with the first electrode wiring.   The said 1st electrode wiring is connected to the said electrothermal conversion element through the 2nd electrode wiring formed in the other side of the said insulating layer, The any one of Claim 1 to 4 characterized by the above-mentioned. Liquid discharge head substrate.   6. The substrate for a liquid discharge head according to claim 5, wherein the first electrode wiring and the second electrode wiring are connected through a through hole formed in the insulating layer.   7. The liquid ejection head according to claim 5, wherein the heat insulating part is a space formed in the insulating layer so as not to contact the first electrode wiring and the second electrode wiring. 8. Substrate. A liquid discharge head substrate according to any one of claims 1 to 7,
A liquid discharge head, wherein the liquid can be discharged from the discharge port by heat generated by the electrothermal conversion element.   A liquid discharge apparatus comprising: the liquid discharge head according to claim 8; and a drive circuit that drives the liquid discharge head. A substrate for a liquid discharge head provided in a liquid discharge head capable of discharging a liquid by heat generation of an electrothermal conversion element, wherein the electrothermal conversion element positioned on the other side of the insulating layer is driven on one side of the insulating layer A method for manufacturing a substrate for a liquid discharge head in which a first electrode wiring for connection to a substrate is formed,
Forming a removable sacrificial layer at a portion of the insulating layer facing the electrothermal transducer and the first electrode wiring;
Removing the sacrificial layer and forming a space in a facing portion between the electrothermal transducer and the first electrode wiring;
A method for producing a substrate for a liquid discharge head, comprising:

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