JP2019142216A - Substrate of liquid ejection head and liquid ejection head - Google Patents

Abstract

To prevent a fuse part from being changed in quality by a liquid while preventing influence of a change in the quality of a covering part from increasing when a heat generation resistance element and the covering part conduct.SOLUTION: A substrate for a liquid ejection head comprises: a first covering part that covers a first heat generation resistance element and is conductive; a second covering part that covers a second heat generation resistance element and is conductive; insulation layers respectively disposed between the first heat generation resistance element and the first covering part and between the second heat generation resistance element and the second covering part; a fuse part provided on a side where the first covering part for a base material is provided; and a common wire electrically connected to the first covering part via the fuse part and provided for electrically connecting the first covering part and the second covering part. In addition, the substrate for the liquid ejection head includes at least silicon and carbon and has a covering layer that covers the fuse part.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a liquid discharge head substrate and a liquid discharge head used in a liquid discharge head that discharges liquid.

  Currently, a liquid discharge head equipped with a liquid discharge head that heats the liquid inside the liquid chamber by energizing the heating resistor element, causes film boiling in the liquid, and discharges liquid droplets from the discharge port using this foaming energy. Many devices are used. When recording is performed by such a liquid ejecting apparatus, physical effects such as impact caused by cavitation that occurs when the liquid foams, contracts, or disappears in the region on the heating resistor element are exerted on the region on the heating resistor element. May be. In addition, since the heating resistor element becomes high temperature when liquid is discharged, the chemical action of the liquid component thermally decomposing and adhering to the surface of the heating resistor element and sticking / depositing may occur. May be affected. In order to protect the heating resistor element from physical action or chemical action on the heating resistor element, a protective layer as a covering portion covering the heating resistor element is disposed on the heating resistor element.

  Usually, a protective layer is arrange | positioned in the position which contact | connects a liquid. Therefore, when electricity flows through the protective layer, an electrochemical reaction occurs between the protective layer and the liquid, and the function as the protective layer may be impaired. For this reason, an insulating layer is disposed between the heating resistor element and the protective layer so that a part of the electricity supplied to the heating resistor element does not flow to the protective layer.

  However, for some reason, the function of the insulating layer is impaired (accidental failure), and there is a possibility that electricity flows directly from the heating resistor element or the wiring to the protective layer. When a part of the electricity supplied to the heating resistor element flows to the protective layer, an electrochemical reaction may occur between the protective layer and the liquid, and the protective layer may be altered. If the protective layer is altered, the durability of the protective layer may be reduced. Furthermore, when protective layers covering different heating resistance elements are electrically connected to each other, current flows in a protective layer other than the protective layer that is electrically connected to the heating resistance elements, and the liquid discharge head There is a risk that the effects of alteration will spread within.

  In order to prevent such an influence, a configuration in which the protective layers are individually separated is effective. However, in some liquid ejection heads, a configuration in which the protective layers are not separated individually but connected to each other is preferable. For example, when cleaning is performed to remove kogation deposited on a protective layer by eluting the protective layer into a liquid using an electrochemical reaction, a plurality of protective layers are electrically connected to apply a voltage to the protective layer. A configuration in which connection is made is preferable. In addition, when applying a potential that repels the potential of the particles causing the kogation contained in the liquid to the protective layer, the protective layer also prevents the generation of kogation by repelling the particles from the protective layer. A structure in which a plurality of protective layers are electrically connected in order to apply a voltage to is preferable.

  Here, Patent Document 1 describes a configuration in which each protective layer is connected to a common wiring electrically connected to a plurality of protective layers via a fuse portion. In such a configuration, when the above-described conduction occurs and a current flows in one protective layer, the fuse portion is cut by this current, whereby the electrical connection with the other protective layer is cut. Thereby, it can suppress that the influence of quality change of a protective layer spreads.

JP 2014-124920 A

  As a position where the fuse portion is provided, a configuration in which the fuse portion is disposed in the vicinity of the covering portion that covers the heating resistance element is preferable in order to suppress the influence of the deterioration of the covering portion. On the other hand, when the fuse portion is provided at a position in contact with the liquid as in Patent Document 1, the fuse portion may be deteriorated by the liquid, and the reliability of the fuse portion may be reduced.

  Therefore, an object of the present invention is to suppress the possibility that the fuse portion is deteriorated by the liquid while suppressing the influence of the deterioration of the covering portion when the heating resistance element and the covering portion are conducted.

  The substrate for a liquid discharge head according to the present invention includes a base material including a first heat generation resistance element and a second heat generation resistance element that generate heat to discharge a liquid, and a first electrode that covers the first heat generation resistance element and has conductivity. A covering portion; a second covering portion that covers the second heating resistance element and has conductivity; and a space between the first heating resistance element and the first covering portion; and the second heating resistance element and the second covering. Electrically connected to the first covering portion via the fuse portion, an insulating layer disposed between the base portion, a fuse portion provided on the side where the first covering portion of the base material is provided, and a fuse portion. A liquid discharge head substrate having a common wiring for electrically connecting the first covering portion and the second covering portion, the covering layer including at least silicon and carbon and covering the fuse portion It is characterized by having.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to suppress the possibility that a fuse part will be deteriorated with a liquid, suppressing that the influence of the deterioration of a coating | coated part at the time of a heating resistive element and a coating | coated part spreading | conducting.

Schematic configuration diagram of recording device Perspective view of recording head A perspective view conceptually showing a recording element substrate Schematic plan view of recording element substrate Circuit diagram related to fuse operation Cross section of recording element substrate Sectional drawing showing manufacturing process of recording element substrate

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the following description does not limit the scope of the present invention.

  The present embodiment is an ink jet recording apparatus (recording apparatus) configured to circulate a liquid such as ink between a tank and a liquid ejecting apparatus, but may be in other forms. For example, the ink in the pressure chamber may be flowed by providing two tanks on the upstream side and the downstream side of the liquid ejection device without circulating the ink and flowing the ink from one tank to the other tank. .

  The present embodiment is a so-called line type head having a length corresponding to the width of the recording medium. However, the present invention is also applied to a so-called serial type liquid ejecting apparatus that performs recording while scanning the recording medium. Can be applied. As a serial type liquid ejection device, for example, a configuration in which one recording element substrate for black ink and one for color ink are mounted. Not limited to this, a short line head shorter than the width of the recording medium, in which several recording element substrates are arranged so that the ejection openings overlap in the direction of the ejection opening array, is formed on the recording medium. Alternatively, it may be scanned.

(Inkjet recording device)
FIG. 1 shows a schematic configuration of a liquid ejection apparatus according to the present embodiment, in particular, an inkjet recording apparatus 1000 (hereinafter also referred to as a recording apparatus) that performs recording by ejecting ink. The recording apparatus 1000 includes a transport unit 1 that transports the recording medium 2 and a line-type liquid ejection head 3 that is disposed substantially orthogonal to the transport direction of the recording medium, and continuously records the plurality of recording media 2. Alternatively, it is a line type recording apparatus that performs continuous recording in one pass while intermittently conveying. The recording medium 2 is not limited to cut paper but may be continuous roll paper. The recording apparatus 1000 includes four monochromatic liquid ejection heads 3 respectively corresponding to four types of inks of CMYK (cyan, magenta, yellow, and black). In addition, the recording apparatus 1000 includes a cap 1007. By covering the ejection port surface side of the liquid ejection head 3 with the cap 1007 during non-recording, ink evaporation from the ejection port can be prevented.

(Liquid discharge head)
The configuration of the liquid ejection head 3 according to this embodiment will be described. 2A and 2B are perspective views of the liquid discharge head 3 according to the present embodiment. The liquid ejection head 3 is a line type liquid ejection head in which 16 recording element substrates 10 capable of ejecting one color of ink with one recording element substrate 10 are arranged in a straight line (arranged inline). The liquid ejection head 3 that ejects ink of each color has the same configuration.

  2A and 2B, the liquid ejection head 3 includes a recording element substrate 10, a flexible wiring substrate 40, an electric wiring substrate 90 provided with a signal input terminal 91 and a power supply terminal 92, and . The signal input terminal 91 and the power supply terminal 92 are electrically connected to the control unit of the recording apparatus 1000, and supply an ejection drive signal and electric power necessary for ejection to the recording element substrate 10, respectively. By consolidating the wiring by the electric circuit in the electric wiring board 90, the number of signal input terminals 91 and power supply terminals 92 can be reduced as compared with the number of recording element boards 10. Thus, the number of electrical connection portions that need to be removed when the liquid discharge head 3 is assembled to the recording apparatus 1000 or when the liquid discharge head is replaced can be reduced. Connection portions 93 provided at both ends of the liquid ejection head 3 are connected to the ink supply system of the recording apparatus 1000. Ink is supplied from the supply system of the recording apparatus 1000 to the liquid discharge head 3 via one connection portion 93, and the ink that has passed through the liquid discharge head 3 is supplied to the supply system of the recording apparatus 1000 via the other connection portion 93. It has come to be collected. As described above, the liquid ejection head 3 is configured such that ink can circulate through the path of the recording apparatus 1000 and the path of the liquid ejection head 3.

(Recording element substrate)
FIG. 3 is a perspective view conceptually showing the recording element substrate of this embodiment (the recording element substrate is also referred to as a liquid discharge head).

  The recording element substrate 10 includes a substrate 11 (liquid ejection head substrate) on which a liquid supply path 18 and a liquid recovery path 19 are formed, a flow path forming member 120 on the front side of the substrate 11, and a cover plate on the back side of the substrate 11. 20 is formed. On the flow path forming member 120 of the recording element substrate 10, four ejection port arrays corresponding to the respective ink colors are formed. The liquid supply path 18 and the liquid recovery path 19 provided in the substrate 11 extend along the direction of the discharge port array. The substrate 11 is provided with a plurality of supply ports 17a communicating with the liquid supply path 18 along the discharge port array direction, and a plurality of recovery ports 17b communicating with the liquid recovery path 19 are also formed along the discharge port array direction. Is provided.

  As shown in FIG. 3, thermal action portions 130 for foaming the liquid with thermal energy are arranged at positions corresponding to the respective discharge ports 13. The thermal action unit 130 is a recording element for performing recording by discharging a liquid. Further, the heat acting part 130 is also used as an upper electrode 131 described later. The flow path forming member 120 defines a pressure chamber 23 having a heat acting portion 130 as a recording element. The heating resistor element 108 (FIG. 6) provided corresponding to the heat acting part 130 is electrically connected to the terminal 16 by electrical wiring (not shown) provided on the substrate 11. Heat is generated based on a pulse signal input via an external wiring board (not shown), and the liquid in the pressure chamber 23 is boiled. The liquid is discharged from the discharge port 13 by the foaming force due to the boiling.

  Further, the cover plate 20 is provided with an opening 21 that communicates with the liquid supply path 18 and an opening 21 that communicates with the liquid recovery path. Ink passes through the opening 21, the liquid supply path 18, and the supply port 17 a in order and is pressure It is supplied to the chamber 23. The ink supplied to the pressure chamber 23 is recovered through the recovery port 17b, the liquid recovery path 19, and the opening 21.

  FIG. 4 is a plan view showing a case where the substrate 11 according to the embodiment of the present invention is viewed in plan. FIG. 4A shows a schematic plan view of the substrate 11 according to the embodiment of the present invention. FIG. 4B is a schematic plan view showing an enlarged area A indicated by a dotted line in FIG.

  Between the substrate 11 and the flow path forming member 120, a liquid chamber 121 (flow path) is formed that includes the pressure chamber 23 and is a space through which liquid flows. In the liquid chamber 121, an upper electrode 131 and a counter electrode 132 that are stacked so as to cover the heating resistor element 108 are disposed. Each electrode is connected to the terminal 16 via the common wiring 114 for the upper electrode and the common wiring 134 for the counter electrode, and a potential is applied to both electrodes from the outside through the terminal 16 to thereby form a liquid in the liquid chamber 121. The voltage can be applied between both electrodes via the liquid (ink). Both electrodes are made of a conductive material. Note that a portion of the protective layer 111 that protects the heating resistor element 108 that has a surface exposed to the liquid functions as the upper electrode 131. The protective layer 111 is also referred to as a covering portion 111.

  The upper electrode 131 is required to have a role of protecting the heating resistance element 108 from physical and chemical impacts and thermal conductivity that instantaneously transfers heat generated by the heating resistance element 108 to the ink. It is required that the material does not form a strong oxide film. Further, the upper electrode 131 can function as a negative electrode by setting the potential relatively low with respect to the counter electrode 132 during the recording operation. As a result, when negatively charged particles are mainly contained in the liquid (ink), the particles are electrically repelled from the upper electrode 131 so as not to come close thereto, and the kogation adheres to the upper electrode 131. Can be suppressed. Furthermore, the upper electrode 131 may have a relatively high potential with respect to the counter electrode 132, thereby performing a role of performing cleaning for removing the kog attached during the recording operation together with the upper electrode 131. .

  As the material of the upper electrode 131, it is preferable to use iridium (Ir) or ruthenium (Ru) alone, an alloy of Ir and another metal, or an alloy of Ru and another metal. For example, when the upper electrode 131 is configured using Ir, Ir can be eluted into the liquid by applying a voltage of +2.5 V or more to the upper electrode 131.

  The counter electrode 132 functions as a positive electrode when negatively charged particles in the ink are moved away from the upper electrode 131 during the recording operation. In order to stably maintain the electric field between the counter electrode 132 and the upper electrode 131, it is preferable that the counter electrode 132 be a material containing a metal that has low conductivity, is unlikely to form an oxide film, and does not easily elute due to an electrochemical reaction.

  As the material of the counter electrode 132, it is preferable to use Ir or Ru alone, an alloy of Ir and another metal, an alloy of Ru and another metal, or the like. For example, when the counter electrode 132 is configured using Ir, a voltage of +2.0 V or less is applied to the counter electrode 132 in order to repel charged particles. Thereby, an electric field can be stably formed between the upper electrode 131 without eluting Ir, and the charged particles can be moved away from the upper electrode 131.

  As shown in FIG. 4A, the substrate 11 is provided with a plurality of heating resistance elements 108 including a first heating resistance element 108a and a second heating resistance element 108b. The substrate 11 is provided with a first covering portion 111a that covers the first heating resistor element 108a and a second covering portion 111b that covers the second heating resistor element 108b. The plurality of covering portions 111 including the first covering portion 111 a and the second covering portion 111 b are electrically connected through a common wiring 114. That is, the plurality of upper electrodes 131 are electrically connected through the common wiring 114. The individual covering portions 111 (upper electrodes 131) are electrically connected to the common wiring 114 via the individual wiring 113 and the fuse portion 112 formed in a part of the individual wiring 113. The fuse portion 112 is partially narrowed in wiring width. As a result, when current flows, the current density increases and the temperature rises easily due to Joule heat, and the fuse portion 112 is stably cut. Note that the margin for cutting is further improved by setting the width of the fuse portion 112 to several μm or less, preferably 3 μm or less. In the present embodiment, as an example, the fuse portion 112 has a length of 10 μm and a width of 2 μm.

  As shown in FIG. 4B, the substrate 11 is an opening provided in the substrate 11, and a plurality of supply ports 17a (first opening and second opening) for supplying liquid to the heating resistor element 108. Is provided. Further, the heating resistance element 108, the supply port 17a, and the common wiring 114 are arranged in this order in a direction intersecting with the direction in which the plurality of supply ports 17a are adjacent to each other. Here, the individual wiring 113 is connected to the upper electrode 131, and is connected to a common wiring 114 provided so as to extend in the discharge port array direction through a region between the supply ports 17 a adjacent to each other. The fuse portion 112 is provided closer to the common wiring 114 than the region between the supply ports 17a, and is disposed outside the region of the liquid chamber 121.

  Note that the fuse portion 112 is preferably disposed in the vicinity of the heating resistor element 108 in order to suppress the influence of conduction between the heating resistor element 108 and the upper electrode 131. Therefore, in the present embodiment, the distance from the center of gravity of the heating resistor element 108 to the center of gravity of the fuse portion 112 is 130 μm in the direction along the plane shown in FIG. In order to suppress the spread of the influence of conduction between the heating resistor element 108 and the upper electrode 131, the fuse is set so that the distance between the center of gravity of the heating resistor element 108 (discharge port 13) and the center of gravity of the fuse portion 112 is 150 μm or less. It is preferable to provide the portion 112.

  A modification corresponding to FIG. 4B is shown in FIG. In this modification, the planar shape of the individual wiring 113 and the protective layer 111 is different from the configuration of FIG. Specifically, the individual wiring 113 and the protective layer 111 extending from the fuse portion 112 to the upper side of the heating resistor element 108 have a planar shape such as a T shape. Compared with the configuration of FIG. 4B, this modification can suppress an increase in wiring resistance between the common wiring 114 and the upper electrode 131.

  Thus, in this embodiment, the fuse part 112 is arrange | positioned in the position near the liquid chamber 121. FIG. As a result, the heat resistance elements 108 that are electrically connected to the upper electrode 131 can be separated by as few groups as possible, and the influence of the conduction is prevented from reaching other heat resistance elements over a wide range.

  In the present embodiment, the protective layer 111 is patterned so as to cover a plurality of heating resistance elements 108 (two heating resistance elements 108 in this embodiment), but one protection layer 111 generates one heat generation. The structure which covers the resistive element 108 may be sufficient. In the present embodiment, the fuse portion 112 is provided so that one fuse portion 112 corresponds to the two heating resistance elements 108. However, the configuration may be such that one fuse portion 112 is provided for one heating resistance element 108. In addition, when conduction is generated, one fuse portion 112 is provided for three or more heating resistance elements 108 within a range that can be complemented by the heating resistance elements 108 that are not conducting. Also good.

  FIG. 5 is a circuit diagram relating to the operation of the fuse. When the common wiring 114 connected to the upper electrode 131 is always set to 0 V, when the heating resistor 108 and the upper electrode 131 are electrically connected, a potential difference is generated between both ends of the fuse portion 112, so that the fuse portion 112 is broken. As a result, the heat generating resistance element 108 in which conduction has occurred can be electrically isolated from the common wiring 114.

  When the resistance between the heating resistance element 108 and the upper electrode 131 is large, it is assumed that the potential applied to the upper electrode 131 is low and sufficient current does not flow through the fuse portion 112. In order to prepare for such a case, a detecting means for detecting conduction and its influence is provided, and a mechanism for assisting the cutting of the fuse part 112 by supplying a current to the fuse part when detecting the conduction by the detecting means is provided. Alternatively, a current to the fuse unit 112 may be periodically passed.

  FIG. 6 schematically shows a laminated configuration around the heating resistor element 108 and the fuse portion 112. FIG. 6 is a sectional view taken along line XX of the liquid discharge head (recording element substrate) in which the flow path forming member 120 is joined to the substrate 11 shown in FIG. For simplicity, circuits and wirings are omitted, but the heating resistor element 108 and the fuse portion 112 provided on the substrate 101 are electrically connected to wirings for obtaining power necessary for heat generation and cutting, respectively. Has been.

  Hereinafter, although the laminated structure of a liquid discharge head is demonstrated, the structure and material given below are examples, and are not limited to the following.

  An insulating layer 103 made of SiO or the like is provided on the upper side of a silicon base material 101 as a base material on which a driving element and wiring for driving the driving element (not shown) are formed. Furthermore, a wiring pattern 104 made of an alloy of aluminum and copper is provided on the insulating layer 103. Since the wiring pattern 104 is a wiring for supplying a voltage to the heating resistance element 108, it is desirable that the wiring pattern 104 has a low resistance. In particular, the wiring pattern 104 is preferably formed with a thickness of 0.5 μm or more. In the present embodiment, the wiring pattern 104 is formed with a thickness of 1 μm, for example.

  The wiring pattern 104 is covered with an insulating layer 105 made of SiO or the like. The insulating layer 105 is provided with a plug 106 for connecting the wiring pattern 104 and the heating resistor layer 107, and the plug 106 can be made of tungsten or the like. The surface of the insulating layer 105 is a flattened surface using a CMP method or the like.

  Since the insulating layer 105 is a layer for insulating the wiring pattern 104 and the heating resistor layer 107, the insulating layer 105 is formed thicker than the wiring pattern 104. In addition, the insulating layer 105 formed of SiO having a high heat storage property also serves as a heat storage layer, and affects heat dissipation by the heating resistor element 108 and the fuse portion 112. Therefore, it is preferable that the insulating layer 105 is thicker in order to improve the energy efficiency when driving the heating resistor element 108 during liquid ejection or to improve the cutting performance of the fuse portion 112. In particular, in order to easily reach the temperature at which the fuse portion 112 is melted, it is preferable to form the insulating layer 105 having a thickness of 1 μm or more so as to overlap the fuse portion 112 when the substrate 11 is viewed in plan. . In the present embodiment, the insulating layer 105 is formed with a thickness of, for example, 2 μm so as to easily cut the fuse portion 112 while covering the wiring pattern 104.

  A heating resistor layer 107 made of TaSiN or the like is provided on the surface of the insulating layer 105. A portion of the heating resistor layer 107 through which current flows via the plugs 106 connected to both ends functions as the heating resistor element 108. The heating resistor layer 107 is covered with an insulating layer 110 made of SiN and having a thickness of 200 nm, for example. Further thereon, a protective layer 111 is provided as a covering portion that covers the heating resistor element 108. In the present embodiment, as an example, the protective layer 111 is configured by laminating two layers of 30 nm tantalum (Ta) and 60 nm Ir in order from the insulating layer 110 side. Of these, the portion of the Ir layer that contacts the liquid functions as the above-described upper electrode 131. Further, the Ta layer has a role of improving the adhesion between the insulating layer 110 and the Ir layer. The heating resistance element 108 and the protective layer 111 are electrically insulated by the insulating layer 110.

  In addition, a fuse portion 112, an individual wiring 113, and a common wiring 114 are provided above the insulating layer 110. In this embodiment, in order to reduce process costs, the fuse part 112, the individual wiring 113, and the common wiring 114 are formed as the same layer in the stacking direction using the same material. Specifically, the fuse portion 112, the individual wiring 113, and the common wiring 114 are configured as a three-layered laminated body. For example, 30 nm Ta, 60 nm Ir, and 70 nm Ta 3 are formed from the insulating layer 110 side. It has a layer structure. Of these, the two layers of the side Ta layer and the Ir layer of the insulating layer 110 are formed of the same layer in the stacking direction as the protective layer 111, and the process cost is further suppressed.

  Further, as described above, the fuse portion 112 is located at a position away from the region outside the liquid chamber 121, that is, the wall 120 a forming the liquid chamber 121 of the flow path forming member 120 on the side opposite to the liquid chamber 121. (FIG. 4B).

  Here, the fuse portion 112 is covered with a covering layer 115 which is an insulating layer having high liquid resistance (ink resistance). The effects associated with this configuration will be described.

  If the fuse portion 112 is in contact with the liquid, the liquid may be altered. Even when the fuse unit 112 is provided outside the liquid chamber 121, there is a possibility that the liquid may enter the discharge port surface during printing or when the discharge port surface is wiped. As a result, there is a possibility that the fuse part 112 contacts the liquid and changes its quality. Specifically, when the fuse portion 112 containing Ta is in contact with the liquid, a positive potential is applied, so that an electrochemical reaction with the liquid may occur and anodic oxidation may occur. Further, when a negative potential is applied, hydrogen is generated, and the fuse portion 112 may occlude this hydrogen, and the material constituting the fuse portion 112 may become brittle.

  When the fuse portion 112 is altered in this way, when the heating resistance element 108 and the upper electrode 131 become conductive, the fuse portion 112 is cut to electrically isolate the conductive upper electrode 131 from the common wiring 114. The function of the unit 112 may be impaired.

  Here, the fuse portion 112 applies the potential supplied from the common wiring 114 to the upper electrode 131 when performing the above-described cleaning for removing the kogation on the upper electrode 131 or removing the kogation attached to the upper electrode 131. It also functions as a wiring for applying to. Therefore, when the fuse portion 112 is altered, the potential application to the upper electrode 131 may become unstable, and it is difficult to stably suppress the adhesion of kogation or perform cleaning over a long period of time. There is also a fear.

  Therefore, by providing the highly liquid-resistant covering layer 115 that covers the fuse portion 112 as described above, the possibility that the fuse portion 112 is altered by the liquid can be suppressed. Accordingly, the function of the fuse portion 112 is maintained such that when the heating resistor 108 and the upper electrode 131 are electrically connected, the fuse portion 112 is disconnected and the electrically conductive upper electrode 131 is electrically separated from the common wiring 114. be able to. Further, it is possible to stably suppress the adhesion of kogation or perform cleaning over a long period of time.

  Note that the individual wiring 113 and the common wiring 114 also function as wirings for applying a potential to the upper electrode 131 when suppressing the adhesion of the kogation and cleaning, and thus the individual wiring 113 and the common wiring 114 are also covered with the covering layer 115. It may be broken. In the configuration shown in FIG. 6, of the layers constituting the individual wiring 113, the side end portion in the liquid chamber 121 of the Ta layer on the coating layer 115 side is in contact with the liquid. Thus, even if the side edge of the Ta layer, which is a thin film of about several tens of nanometers, is in contact with the liquid, there is little influence of alteration by the liquid, and the function as the wiring can be maintained for a long time. Further, with such a configuration, the covering layer 115 and the Ta layer in contact with the covering layer 115 can be removed in the same process (FIG. 7G), so that the load on the manufacturing process can be suppressed.

  In addition, when the insulating layer 105 and the insulating layer 110 around the fuse portion 112 are also covered with the covering layer 115, elution of the insulating layer 105 and the insulating layer 110 into the liquid can be suppressed.

  The covering layer 115 may be made of any material as long as it has liquid resistance (ink resistance), but the liquid layer 121 is formed above the individual wiring 113 and the common wiring 114. The flow path forming member 120 is laminated. Therefore, the covering layer 115 is preferably formed of a material that has liquid resistance and also has excellent adhesion to the flow path forming member 120. For example, when the flow path forming member 120 containing an organic material is used, it is preferable to use a coating layer 115 containing at least silicon and carbon, such as SiC or SiCN, which has high adhesion and excellent liquid resistance. In particular, in order to protect the fuse portion 112 from the liquid, the thickness of the covering layer 115 is preferably 50 nm or more. In addition, since the coating layer 115 containing SiCN is higher in insulation than the coating layer 115 made of SiC, anodization when the heating resistance element 108 and the upper electrode 131 are conducted is suppressed, and a flow path is formed. Since there is also little fear of peeling of the member 120, it is more preferable. In the present embodiment, the covering layer 115 is formed using SiCN.

  In addition, the through hole 120 b may be formed in the flow path forming member 120 located above the fuse portion 112. That is, when the recording element substrate 10 is viewed in plan, the through hole 120 b may be formed in the flow path forming member 120 at a position overlapping the fuse portion 112. Thereby, when the heating resistor element 108 and the upper electrode 131 are electrically connected, heat radiation to the flow path forming member 120 side can be suppressed as compared with the case where the through hole 120b is not formed, and the temperature of the fuse portion 112 is reduced. Is likely to rise, and the fuse portion 112 is likely to be cut. If such a through-hole 120b is formed, liquid may enter from the discharge port surface side and the liquid may accumulate, but the fuse portion 112 is covered with a highly liquid-resistant coating layer 115. The fear of deterioration due to the liquid of the fuse portion 112 can be suppressed. Note that the positional relationship between the fuse portion 112 and the through hole 120b may be such that at least a part of both overlaps each other when the recording element substrate 10 is viewed in plan. In order to improve the cutting performance of the fuse portion 112, it is more preferable that the fuse portion 112 is provided so as to be included in the range of the through hole 120b when the recording element substrate 10 is viewed in plan.

  Note that if the cover layer 115 is provided on the fuse portion 112, heat dissipation is likely to occur compared to a configuration in which the cover layer 115 and the flow path forming member 120 are not provided, and the fuse portion 112 is less likely to be cut. Therefore, in order to suppress the influence of heat dissipation, it is preferable that the covering layer 115 has a thickness of 300 nm or less. Further, as described above, by providing the insulating layer 105 having a thickness of 1 μm or more made of highly heat-storable SiO on the base material 101 side of the fuse portion 112, the cutability of the fuse portion 112 can be ensured.

  Further, as in this embodiment, the covering layer 115 may cover the common wiring 114 and the insulating layer 110. Thereby, the deterioration of the common wiring 114 and the elution of the insulating layer 110 into the liquid can be suppressed.

(Method for manufacturing recording element substrate)
Next, the manufacturing process of the recording element substrate (liquid discharge head) in the present embodiment will be described with reference to FIGS. FIG. 7 corresponds to the cross-sectional view shown in FIG.

  First, the insulating layer 103 is formed on the upper side of the silicon base material 101 on which the driving elements and wiring for driving the driving elements (not shown) are formed, and the wiring pattern 104 is formed thereon (FIG. 7A). .

  Next, an insulating layer 105 is formed, and the surface of the insulating layer 105 is planarized by CMP (FIG. 7B).

  Next, a through hole is formed in the insulating layer 105, and a plug material is formed by a CVD method so that at least the through hole is filled. Further, the plug 106 is formed by planarizing the surface of the insulating layer 105 by CMP (FIG. 7C).

  Next, the heating resistor layer 107 and then a metal layer 109 made of, for example, an alloy of aluminum and copper are formed by sputtering, and the metal layer 109 is patterned. Thereafter, the heating resistor layer 107 is patterned using the metal layer 109 as a mask. Subsequently, the portion of the metal layer used as a mask for patterning the heating resistor layer 107 is removed by wet etching (FIG. 7D).

  Next, an insulating layer 110 is provided so as to cover the heating resistor layer 107 and the metal layer 109 (FIG. 7E).

  Further thereon, from the insulating layer 110 side, three layers of the metal laminated film 118 of Ta layer, Ir layer, and Ta layer are formed by sputtering and patterned. Thereby, the upper electrode 131, the individual wiring 113, the fuse portion 112, the common wiring 114, the counter electrode 132 (FIG. 4B), and the common wiring 134 for the counter electrode (FIG. 4B) are formed (FIG. 7). (F)).

  Thereafter, a coating layer 115 made of SiCN is formed, and the upper electrode 131 and the counter electrode 132 are exposed, so that the coating layer 115 positioned above these and tantalum on the outermost surface of the three layers of the metal laminated film 118 are formed. The film is removed by dry etching (FIG. 7G).

  Thereafter, in order to form the terminal 16, an opening is formed in the covering layer 115 and the insulating layer 110 located on the metal layer 109, and, for example, Au is formed on the upper side of the figure so as to be electrically connected to the metal layer 109. A pad forming member 117 in which TiW is laminated is provided on the lower side (FIG. 7 (h)).

  Finally, as shown in FIG. 7I, a flow path forming member 120 for forming a liquid chamber 121 for introducing a liquid to the upper side of the heating resistance element 108 is produced. For example, a photosensitive organic material is applied at a thickness of 5 μm by a spin coating method, only a predetermined portion is exposed, and then a photosensitive organic material is formed thereon after being formed at a thickness of 5 μm. Finally, the two photosensitive organic materials are collectively developed and thermally cured to form a flow path with a hollow structure.

  Further, in the case where the through hole 120b positioned above the fuse portion 112 is formed in the flow path forming member 120, the formation of the through hole 120b in accordance with the formation of the liquid chamber 121 and the discharge port 13 is a manufacturing process. This is preferable because the load can be suppressed.

(Verification test)
Hereinafter, a plurality of verification tests conducted for confirming the effects of the present invention will be described.

  As the recording element substrate (liquid ejection head) of the example, the above-described recording element substrate shown in FIG. 6 was manufactured through the steps shown in FIG.

<Discharge durability test>
The recording element substrate of this example was filled with pigment cyan ink, and an ejection durability test was conducted. First, in order to suppress kogation by suppressing adhesion of particles charged to a negative potential to the upper electrode 131, a potential of +1.0 V is applied to the counter electrode 132 so that the counter electrode 132 becomes an anode. A voltage was applied between 131 and the counter electrode 132. In this state, a discharge potential was applied to the heating resistor element 108 to cause the recording element substrate to perform (10 ^ 9) discharge operations.

  Thereafter, when the inside of the liquid chamber 121 was replaced with clear ink and the surface state was observed, kogation and deposits were confirmed on the surface of the upper electrode 131. Therefore, the pigment cyan ink is filled again, a potential of +5.0 V is applied to the upper electrode 131 so that the upper electrode 131 side becomes an anode, and a voltage is applied between the upper electrode 131 and the counter electrode 132 to perform the cleaning process. Went. At this time, in order to prevent ink sticking, the treatment was performed while repeatedly inverting the polarity between the upper electrode 131 and the counter electrode 132.

  Subsequently, using the same recording element substrate, the discharge operation (10 ^ 9) times and the cleaning process were performed for 5 cycles.

  After 5 cycles, a normal recording operation was performed according to the image data. As a result, an output image with good quality was confirmed.

  When the inside of the liquid chamber 121 was again replaced with clear ink and observed, the floating of the flow path forming member 120 from the substrate 11 and the discoloration or cracking of the individual wiring 113 were not observed. Furthermore, when the periphery of the fuse portion 112 was observed, it was found that the coating layer 115 made of SiCN covered the periphery of the fuse portion without being lifted or peeled off, and the fuse portion maintained the same state as the initial state. .

<Experiment for cutting the fuse in TEG mode>
The relationship between the SiO film thickness on the lower side of the fuse portion 112, that is, the base material 101 side, and the current value that can cut the fuse portion 112 was verified in the TEG form.

  As a sample 1, SiO was formed with a thickness of 2 μm by PECVD on a substrate on which a SiO was formed with a thickness of 100 nm on a silicon substrate, and then SiN was formed with a thickness of 200 nm. On top of that, Ta 30 nm, Ir 60 nm, and Ta 70 nm were successively formed by sputtering to form a laminated film. Further, the laminated film was covered with SiCN having a thickness of 150 nm. Further, the Ta / Ir / Ta laminated film was subjected to patterning for forming a fuse portion and a pad for applying a voltage to the fuse portion, and sample 1 was produced.

  As Sample 2, a TEG having a thickness of 1 μm made of 2 μm thick SiO formed by PECVD of Sample 1 was produced. Other configurations were the same as those of Sample 1.

  A TEG having the same configuration as that of Sample 1 except that SiO 2 having a thickness of 2 μm formed by PECVD of Sample 1 was not provided as Sample 3 was prepared. That is, Sample 3 has a structure in which SiO having a thickness of 100 nm is formed on the silicon substrate side of the fuse portion 112.

  For Sample 1, Sample 2, and Sample 3, the voltage applied to both ends of the fuse portion was changed using a power source, and the cutting characteristics of the fuse portion were examined. In Sample 1, the fuse portion was cut when a current of about 50 mA flowed through the fuse portion. In sample 2, the fuse portion was cut when a current of about 60 mA flowed through the fuse portion. Sample 3 was not cut at a current of about 60 mA, and the current value flowing through the fuse portion was about 100 mA, and the fuse portion was cut. From the cutability of the fuse part, it was found that the film thickness of SiO is preferably 1 μm or more.

<Disconnection test>
Using the recording element substrate of the example used in the discharge endurance test, a pulse voltage 5 times the voltage at the time of normal discharge was applied to an arbitrary heating resistance element 108 to intentionally generate a disconnection. The fuse portion 112 connected to the upper electrode 131 on the disconnected heating element 108 was melted. As a result of electrical inspection, it was confirmed that the upper electrode 131 on the disconnected heating element 108 was electrically separated from the other heating elements 108.

  Thereafter, when normal printing was performed with another heating resistor element 108, it was possible to maintain a stable ejection operation.

11 Substrate (Liquid discharge head substrate)
108 Heating resistance element 101 Base material 110 Insulating layer 111 Protective layer (covering part)
112 Fuse part 113 Individual wiring 114 Common wiring 115 Insulating layer (covering layer)
120 channel forming member

Claims (17)

A substrate comprising a first heating resistor element and a second heating resistor element that generate heat to discharge liquid;
A first covering portion covering the first heating resistance element and having conductivity;
A second covering portion covering the second heating resistance element and having conductivity;
An insulating layer disposed between the first heating resistor element and the first covering portion and between the second heating resistor element and the second covering portion;
A fuse portion provided on a side of the base material on which the first covering portion is provided;
A common wiring electrically connected to the first covering portion via the fuse portion, and electrically connecting the first covering portion and the second covering portion;
In a liquid discharge head substrate having
A substrate for a liquid discharge head, comprising at least silicon and carbon and having a coating layer that covers the fuse portion.   The liquid discharge head substrate according to claim 1, wherein the coating layer includes SiCN.   3. The liquid discharge head according to claim 1, wherein the base material includes a layer containing SiO having a thickness of 1 μm or more at a position overlapping the fuse portion when the liquid discharge head substrate is viewed in plan. Substrate.   The liquid discharge head substrate according to claim 1, wherein the fuse portion includes tantalum. The common wiring and the fuse portion are provided as the same layer in the stacking direction in the liquid discharge head substrate,
The liquid discharge head substrate according to claim 1, wherein the coating layer covers the common wiring.   The liquid discharge head substrate according to claim 1, wherein the common wiring contains tantalum.   7. The liquid according to claim 1, wherein a surface of the first covering portion on a side opposite to the surface on the first heating resistance element side is configured by a layer containing iridium. Discharge head substrate. The fuse portion includes a laminate in which a layer containing iridium and a layer containing tantalum are laminated in this order from the base material side,
8. The liquid according to claim 7, wherein the iridium-containing layer of the fuse portion and the iridium-containing layer of the first covering portion are configured as the same layer in the stacking direction of the liquid discharge head substrate. Substrate for discharge head. The first covering portion and the fuse portion are electrically connected, and an individual wiring provided as the same layer as the fuse portion in the stacking direction of the liquid discharge head substrate;
A first opening and a second opening provided adjacent to each other for flowing liquid;
When the liquid discharge head substrate is viewed in plan, the first heating resistor element, the first opening, and the common wiring are arranged in a direction intersecting the direction in which the first opening and the second opening are adjacent to each other. Are arranged in order,
The individual wiring is disposed through a region between the first opening and the second opening,
The liquid discharge head substrate according to claim 1, wherein the fuse portion is located closer to the common wiring than the region.   10. The liquid discharge head substrate according to claim 1, wherein a potential can be applied to the first covering portion via the common wiring and the fuse portion. 11.   The distance between the center of gravity of the fuse portion and the center of gravity of the first heating resistor element is 150 μm or less when the liquid discharge head substrate is viewed in plan. The substrate for liquid discharge heads as described. A base material including a first heat generating resistor element and a second heat generating resistor element that generate heat to discharge a liquid, a first covering portion that covers the first heat generating resistor element and has conductivity, and the second heat generating resistor element And a second covering portion having conductivity, and an insulating layer disposed between the first heating resistor element and the first covering portion and between the second heating resistor element and the second covering portion. A fuse portion provided on the side of the base material on which the first covering portion is provided, and the first covering portion and the second covering portion electrically connected to the first covering portion via the fuse portion. A common wiring for electrically connecting the covering portion, and a liquid discharge head substrate,
A flow path forming member provided on the first covering portion side of the liquid discharge head substrate, and comprising a wall that forms a flow path;
In a liquid discharge head having
The liquid ejection head substrate is provided on the first coating portion side of the liquid ejection head substrate, and includes a coating layer that includes at least silicon and carbon and covers the fuse portion. Discharge head.   The liquid discharge head according to claim 12, wherein the coating layer includes SiCN.   The liquid discharge head according to claim 12, wherein the fuse portion includes tantalum.   The liquid discharge head according to claim 12, wherein the fuse portion is provided at a position away from the wall on a side opposite to the flow path side. The flow path forming member includes a through hole at a position overlapping the fuse portion when the liquid discharge head substrate is viewed in plan view,
The liquid discharge head according to claim 12, wherein the coating layer includes a surface exposed from the through hole. 17. The liquid ejection head according to claim 12, wherein a potential can be applied to the first covering portion via the common wiring and the fuse portion.

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