JP7183049B2 - LIQUID EJECTION HEAD SUBSTRATE AND LIQUID EJECTION HEAD - Google Patents

Description

The present invention relates to a liquid ejection head substrate and a liquid ejection head used in a liquid ejection head that ejects liquid.

At present, a liquid ejecting head equipped with a liquid ejecting head that ejects liquid droplets from an ejection port by heating a liquid inside a liquid chamber by energizing a heat-generating resistance element to cause film boiling in the liquid and using this bubbling energy. Many devices are used. When recording is performed by such a liquid ejecting apparatus, a physical action such as impact due to cavitation generated when the liquid foams, contracts, or disappears in the area on the heating element is exerted on the area on the heating element. may be In addition, since the temperature of the heat generating resistor element is high when the liquid is discharged, the liquid components are thermally decomposed and attached to the surface of the heat generating resistor element, causing a chemical action such as sticking and depositing on the surface of the heat generating resistor element. may be affected. In order to protect the heat-generating resistor elements from physical or chemical action on these heat-generating resistor elements, a protective layer is arranged on the heat-generating resistor elements as a cover to cover the heat-generating resistor elements.

Usually, the protective layer is arranged at a position in contact with the liquid. Therefore, when electricity flows through the protective layer, an electrochemical reaction occurs between the protective layer and the liquid, which may impair the function of the protective layer. Therefore, an insulating layer is arranged between the heating resistor element and the protective layer so that 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 will flow directly from the heating resistance element or wiring to the protective layer. If part of the electricity supplied to the heating resistor element flows through the protective layer, an electrochemical reaction may occur between the protective layer and the liquid, resulting in deterioration of the protective layer. If the protective layer deteriorates, the durability of the protective layer may decrease. Furthermore, when protective layers covering different heat generating resistor elements are electrically connected to each other, a current flows through a protective layer other than the protective layer that is electrically connected to the heat generating resistor element, resulting in a liquid ejection head. There is a risk that the effects of alteration will spread within.

In order to prevent such an influence, it is effective to separate the protective layers individually, but depending on the liquid ejection head, it may be preferable to connect the protective layers to each other without separating them individually. For example, when performing cleaning to remove kogation deposited on the protective layer by eluting the protective layer into a liquid using an electrochemical reaction, a plurality of protective layers are electrically connected in order to apply a voltage to the protective layers. A configuration in which the terminals are directly connected is preferable. In addition, by applying a potential that repels the potential of the particles contained in the liquid that cause burnt deposits to the protective layer, the particles are repelled from the protective layer to suppress the occurrence of burnt deposits. A configuration in which a plurality of protective layers are electrically connected in order to apply a voltage to is preferred.

Here, Patent Document 1 describes a configuration in which each protective layer is connected via a fuse portion to a common wiring electrically connected to a plurality of protective layers. In such a configuration, when the above-described conduction occurs and a current flows through one protective layer, the current cuts the fuse section, thereby disconnecting the electrical connection with the other protective layers. As a result, it is possible to suppress the spread of the influence of deterioration of the protective layer.

JP 2014-124920 A

As for the position of the fuse portion, it is preferable to arrange the fuse portion in the vicinity of the covering portion that covers the heating resistor element in order to suppress the spread of the influence of deterioration of the covering portion. On the other hand, if 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 decrease.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to prevent the fuse portion from being degraded by a liquid while suppressing the spread of the influence of deterioration of the covering portion when the heating resistor element and the covering portion are electrically connected.

A substrate for a liquid ejection head according to the present invention comprises a substrate including a first heating resistor element and a second heating resistor element that generate heat to eject a liquid, and a conductive first heating resistor element covering the first heating resistor element. a covering portion, a second covering portion covering the second heating resistance element and having conductivity, and between the first heating resistance element and the first covering portion and between the second heating resistance element and the second covering a fuse portion provided on a side of the substrate on which the first covering portion is provided; and an insulating layer electrically connected to the first covering portion via the fuse portion. a common wiring for electrically connecting the first covering portion and the second covering portion; 2. A substrate for a liquid ejection head having individual wirings provided in the same layer as the fuse portion, and a first opening and a second opening provided adjacent to each other for flowing liquid, wherein at least silicon and carbon are used. and has a covering layer covering the fuse portion, and the second One heating resistor element, the first opening, and the common wiring are arranged in this order, and the individual wiring is arranged through a region between the first opening and the second opening, and the fuse The substrate for a liquid ejection head , wherein the part is located closer to the common wiring than the area .

According to the present invention, it is possible to prevent the fuse from being degraded by the liquid while suppressing the influence of deterioration of the covering when the heating resistor element and the covering are electrically connected.

Schematic diagram of recording device Perspective view of recording head FIG. 2 is a perspective view conceptually showing a recording element substrate; Schematic plan view of recording element substrate Circuit diagram related to the operation of the fuse section Cross-sectional view of recording element substrate Cross-sectional view showing the manufacturing process of the recording element substrate

Hereinafter, examples of 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.

Although this embodiment is an inkjet recording apparatus (recording apparatus) in which liquid such as ink is circulated between a tank and a liquid ejection device, other modes may be used. For example, two tanks may be provided on the upstream side and the downstream side of the liquid ejection device without circulating the ink, and the ink in the pressure chamber may be caused to flow by flowing the ink from one tank to the other tank. .

Although this embodiment is a so-called line type head having a length corresponding to the width of the recording medium, the present invention can also be applied to a so-called serial type liquid ejection apparatus that performs recording while scanning the recording medium. can be applied. As a serial type liquid ejection device, for example, there is a configuration in which one recording element substrate for black ink and one recording element substrate for color ink are mounted. Not limited to this, a short line head shorter than the width of the recording medium is prepared by arranging several recording element substrates so that the ejection openings overlap in the ejection opening array direction, and it is attached to the recording medium. It may be of a form in which it is scanned against.

(Inkjet recording device)
FIG. 1 shows a schematic configuration of a liquid ejection apparatus according to the present embodiment, particularly an inkjet printing apparatus 1000 (hereinafter also referred to as a printing apparatus) that ejects ink to perform printing. The recording apparatus 1000 includes a transport unit 1 that transports a recording medium 2 and a line-type liquid ejection head 3 that is arranged substantially perpendicular to the transport direction of the recording medium. Alternatively, it is a line-type recording apparatus that performs continuous recording in one pass while intermittently conveying the recording medium. The recording medium 2 is not limited to cut paper, and may be continuous roll paper. The printing apparatus 1000 includes four single-color liquid ejection heads 3 corresponding to four types of ink, CMYK (cyan, magenta, yellow, and black). The printing apparatus 1000 also includes a cap 1007. By covering the ejection opening surface side of the liquid ejection head 3 with the cap 1007 during non-printing, evaporation of ink from the ejection openings can be prevented.

(liquid ejection 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 ejection head 3 according to this embodiment. The liquid ejection head 3 is a line-type liquid ejection head in which 16 recording element substrates 10 each capable of ejecting ink of one color are linearly arranged (arranged in-line). The liquid ejection heads 3 for ejecting each color ink have the same configuration.

As shown in FIGS. 2A and 2B, the liquid ejection head 3 includes a recording element substrate 10, a flexible wiring substrate 40, and an electric wiring substrate 90 provided with signal input terminals 91 and power supply terminals 92. , provided. A signal input terminal 91 and a power supply terminal 92 are electrically connected to a control section of the printing apparatus 1000, and supply an ejection driving signal and electric power required for ejection to the printing element substrate 10, respectively. By consolidating the wiring by the electric circuit in the electric wiring board 90 , the number of the signal input terminals 91 and the power supply terminals 92 can be reduced compared to the number of the recording element boards 10 . This reduces the number of electrical connections that need to be removed when assembling the liquid ejection head 3 to the printing apparatus 1000 or when replacing the liquid ejection head. Connecting portions 93 provided at both ends of the liquid ejection head 3 are connected to an ink supply system of the printing apparatus 1000 . Ink is supplied from the supply system of the printing apparatus 1000 to the liquid ejection head 3 through one connection portion 93, and the ink that has passed through the liquid ejection head 3 is sent through the other connection portion 93 to the supply system of the printing apparatus 1000. It is designed to be collected. In this manner, the liquid ejection head 3 has a configuration in which 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 a printing element substrate (the printing element substrate is also called a liquid ejection head) of this embodiment.

The recording element substrate 10 includes a substrate 11 (liquid ejection head substrate) in 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 are formed. The flow path forming member 120 of the recording element substrate 10 is formed with four ejection port arrays corresponding to each ink color. A liquid supply path 18 and a liquid recovery path 19 provided in the substrate 11 extend along the direction of the ejection port array. Further, the substrate 11 is provided with a plurality of supply ports 17a communicating with the liquid supply path 18 along the direction of the ejection port array, and a plurality of recovery ports 17b communicating with the liquid recovery path 19 along the direction of the ejection port array. is provided.

As shown in FIG. 3, a heat acting portion 130 is arranged at a position corresponding to each ejection port 13 to foam the liquid with thermal energy. The heat acting portion 130 is a printing element for printing by ejecting liquid. Moreover, the heat acting portion 130 is also used as an upper electrode 131, which will be described later. A pressure chamber 23 having therein a heat acting portion 130 as a recording element is defined by the flow path forming member 120 . A heating resistor element 108 ( FIG. 6 ) provided corresponding to the heat acting portion 130 is electrically connected to the terminal 16 by an electric wiring (not shown) provided on the substrate 11 . Based on a pulse signal input via an external wiring board (not shown), heat is generated to boil the liquid in the pressure chamber 23 . The liquid is discharged from the discharge port 13 by the power of bubbling caused by this boiling.

The cover plate 20 is provided with an opening 21 communicating with the liquid supply path 18 and an opening 21 communicating with the liquid recovery path. The chamber 23 is supplied. 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.

FIG. 4 is a plan view showing a case where the substrate 11 according to the embodiment of the present invention is viewed from above. FIG. 4A shows a schematic plan view of the substrate 11 according to the embodiment of the present invention. FIG. 4(b) shows a schematic plan view in which the region A indicated by the dotted line in FIG. 4(a) is enlarged.

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

The upper electrode 131 is required to have a function of protecting the heat generating resistor element 108 from physical and chemical impacts and to have thermal conductivity to instantaneously transfer the heat generated by the heat generating resistor element 108 to the ink. A material that does not form a strong oxide film is required. Also, the upper electrode 131 can function as a negative electrode by making 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), they are electrically repulsed from the upper electrode 131 to keep them away, thereby preventing adhesion of burnt deposits on the upper electrode 131 . can be suppressed. Furthermore, by making the potential of the upper electrode 131 relatively high with respect to the counter electrode 132, it may play a role of performing cleaning to remove kogation adhered during the recording operation together with the upper electrode 131. .

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

The counter electrode 132 functions as a positive electrode when keeping negatively charged particles in the ink away from the upper electrode 131 during the printing 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 is made of a material containing a metal that has low electrical conductivity, does not easily form an oxide film, and is less likely to be eluted by an electrochemical reaction.

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

As shown in FIG. 4A, the substrate 11 is provided with a plurality of heating resistor elements 108 including first heating resistor elements 108a and second heating resistor elements 108b. The substrate 11 is provided with a first covering portion 111a covering the first heat generating resistance element 108a and a second covering portion 111b covering the second heat generating resistance element 108b. A plurality of covering portions 111 including the first covering portion 111 a and the second covering portion 111 b are electrically connected via a common wiring 114 . That is, the multiple upper electrodes 131 are electrically connected via the common wiring 114 . Each covering portion 111 (upper electrode 131 ) is electrically connected to a common wiring 114 via an individual wiring 113 and a fuse portion 112 formed in a part of the individual wiring 113 . The wiring width of the fuse portion 112 is partially narrowed. As a result, when current flows, the current density increases and the temperature rise due to Joule heat is likely to occur, so that the fuse portion 112 is cut stably. By setting the width of the fuse portion 112 to several μm or less, preferably 3 μm or less, the margin for disconnection is further improved. In this 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 has a plurality of supply ports 17a (first and second openings), which are openings provided in the substrate 11 and for supplying liquid to the heating resistor elements . is provided. In addition, the heating resistor element 108, the supply ports 17a, and the common wiring 114 are arranged in this order in the direction intersecting 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 extending in the ejection port row direction through the region between the supply ports 17a adjacent to each other. The fuse part 112 is provided closer to the common wiring 114 than the area between the supply ports 17 a and is arranged outside the area of the liquid chamber 121 .

Note that the fuse portion 112 is preferably arranged near the heating resistor element 108 in order to suppress the spread of the influence of the 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 set to 130 μm in the direction along the plane shown in FIG. 4B. In order to suppress the spread of the effect of conduction between the heating resistor element 108 and the upper electrode 131, the fuse is arranged 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. A portion 112 is preferably provided.

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

Thus, in this embodiment, the fuse portion 112 is arranged at a position close to the liquid chamber 121 . As a result, it is possible to separate the heat generating resistor elements 108 that are electrically connected to the upper electrode 131 into as few groups as possible, thereby preventing the influence of the electrical connection from reaching other heat generating resistor elements over a wide range.

In this embodiment, the protective layer 111 is patterned so as to cover a plurality of heat generating resistor elements 108 (two heat generating resistor elements 108 in this embodiment). It may be configured to cover the resistance element 108 . In addition, in this embodiment, the fuse portions 112 are provided such that one fuse portion 112 corresponds to two heating resistor elements 108 . However, one fuse portion 112 may be provided for one heating resistor element 108 . In addition, one fuse section 112 is provided for a plurality of three or more heat generating resistor elements 108 as long as the heat generating resistor elements 108 in which electrical continuity does not occur can be complemented when conduction occurs. good too.

FIG. 5 is a circuit diagram regarding the operation of the fuse. By keeping the common wiring 114 connected to the upper electrode 131 always at 0V, when the heating resistor element 108 and the upper electrode 131 are electrically connected, a potential difference is generated between both ends of the fuse portion 112 and the fuse portion 112 is broken. As a result, the heat-generating resistor element 108 that is electrically connected can be electrically separated from the common wiring 114 .

Note that if the resistance between the heating resistor element 108 and the upper electrode 131 is large, the potential applied to the upper electrode 131 is low, and it is assumed that a sufficient current does not flow through the fuse portion 112 . In preparation for such a case, there is provided a detection means for detecting conduction and the effect associated therewith, and a mechanism is provided for supplying a current to the fuse portion to assist in cutting the fuse portion 112 when the detection means detects conduction. Alternatively, a current may be supplied to the fuse portion 112 periodically.

FIG. 6 schematically shows a laminated structure around the heating resistor element 108 and the fuse portion 112. As shown in FIG. FIG. 6 shows a cross-sectional view of the liquid ejection head (printing element substrate) in which the flow path forming member 120 is joined to the substrate 11 shown in FIG. 4A, taken along the line XX. Although circuits and wiring are omitted for simplicity, the heating resistor element 108 and the fuse section 112 provided on the substrate 101 are electrically connected to wiring for obtaining power necessary for heat generation and disconnection. It is

Although the layered structure of the liquid ejection head will be described below, the structures and materials listed 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 substrate 101 as a substrate on which drive elements and wiring (not shown) for driving the drive elements are formed. Furthermore, a wiring pattern 104 made of an aluminum-copper alloy or the like is provided on the insulating layer 103 . Since the wiring pattern 104 is wiring for supplying voltage to the heating resistor element 108, it is desirable that the wiring pattern 104 has a low resistance. In particular, it is preferable to form the wiring pattern 104 with a thickness of 0.5 μm or more. In this 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. A plug 106 for connecting the wiring pattern 104 and the heating resistor layer 107 is provided in the insulating layer 105, and the material of the plug 106 can be tungsten or the like. The surface of the insulating layer 105 is planarized using the 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 , it is formed thicker than the wiring pattern 104 . Moreover, the insulating layer 105 made of SiO, which has 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, in order to improve the energy efficiency when driving the heat generating resistor element 108 during liquid ejection and to improve the disconnectability of the fuse portion 112, it is preferable that the insulating layer 105 is thick. 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 with a thickness of 1 μm or more so as to overlap the fuse portion 112 when the substrate 11 is viewed from above. . In this embodiment, the insulating layer 105 is formed with a thickness of 2 μm, for example, in order to cover the wiring pattern 104 and facilitate disconnection of the fuse portion 112 .

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 through plugs 106 connected to both ends functions as a heating resistor element 108 . The heating resistor layer 107 is covered with an insulating layer 110 made of, for example, SiN and having a thickness of 200 nm. Further thereon, a protective layer 111 is provided as a covering portion that covers the heating resistor element 108 . In this 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 is in contact with the liquid functions as the upper electrode 131 described above. In addition, the Ta layer has a role of enhancing adhesion between the insulating layer 110 and the Ir layer. The heating resistor element 108 and the protective layer 111 are electrically insulated by the insulating layer 110 .

A fuse portion 112 , an individual wiring 113 and a common wiring 114 are provided on the upper side of the insulating layer 110 . In this embodiment, the fuse section 112, the individual wiring 113, and the common wiring 114 are formed as the same layer in the stacking direction using the same material in order to reduce the process cost. Specifically, the fuse portion 112, the individual wiring 113, and the common wiring 114 are configured as a three-layer laminate. It has a layered structure. Of these layers, the two layers of the Ta layer and the Ir layer on the side of the insulating layer 110 are formed from the same layer as the protective layer 111 in the stacking direction, thereby further suppressing the process cost.

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

Here, the fuse portion 112 is covered with a coating layer 115 that is an insulating layer with high liquid resistance (ink resistance). Effects associated with this configuration will be described.

If the fuse portion 112 is configured to be in contact with liquid, there is a risk that the liquid may cause deterioration. Even if the fuse portion 112 is provided outside the liquid chamber 121, there is a possibility that the liquid may enter through the ejection port surface during printing or wiping of the ejection port surface. As a result, the fuse portion 112 may come into contact with the liquid and deteriorate. Specifically, when the fuse portion 112 containing Ta is in contact with liquid, the application of a positive potential may cause an electrochemical reaction with the liquid, resulting in anodic oxidation. In addition, hydrogen is generated by applying a negative potential, and the fuse portion 112 absorbs this hydrogen, which may cause embrittlement of the material forming the fuse portion 112 .

When the fuse portion 112 is degraded in this manner, the fuse portion 112 is cut to electrically separate the conductive upper electrode 131 from the common wiring 114 when the heating resistor element 108 and the upper electrode 131 are electrically connected. The function of the part 112 may be impaired.

Here, the fuse section 112 applies the potential supplied from the common wiring 114 to the upper electrode 131 when performing cleaning for suppressing adhesion of kogation to the upper electrode 131 and removing kogation adhering to the upper electrode 131 as described above. It also functions as a wiring for applying to . Therefore, if the fuse portion 112 is degraded, the potential applied to the upper electrode 131 may become unstable, making it difficult to stably suppress the adhesion of burnt deposits over a long period of time and perform cleaning. There is also a fear that

Therefore, by providing the highly liquid-resistant coating layer 115 that covers the fuse portion 112 as described above, it is possible to prevent the fuse portion 112 from being degraded by the liquid. This maintains the function of the fuse portion 112, which disconnects the fuse portion 112 and electrically isolates the conductive upper electrode 131 from the common wiring 114 when the heating resistor element 108 and the upper electrode 131 are electrically connected. be able to. In addition, it is possible to stably suppress the adhesion of burnt deposits and perform cleaning over a long period of time.

It should be noted that the individual wirings 113 and the common wirings 114 also function as wirings for applying a potential to the upper electrode 131 when suppressing adhesion of burnt deposits and cleaning, so that the individual wirings 113 and the common wirings 114 are also covered with the coating layer 115 . It may be In the structure shown in FIG. 6, among the layers constituting the individual wiring 113, the side end of the Ta layer on the coating layer 115 side in the liquid chamber 121 is in contact with the liquid. Thus, even if the side edges of the Ta layer, which is a thin film of several tens of nanometers, are in contact with the liquid, there is little influence of deterioration due to the liquid, and the wiring function can be maintained for a long period of time. Moreover, with such a configuration, the coating layer 115 and the Ta layer in contact therewith can be removed in the same process (FIG. 7(g)), so the load in the manufacturing process can be reduced.

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

The coating layer 115 may be made of any material as long as it has liquid resistance (ink resistance). The flow path forming members 120 are laminated. Therefore, it is preferable that the coating layer 115 is made of a material that has liquid resistance and also has excellent adhesion to the flow path forming member 120 . For example, when using the flow path forming member 120 containing an organic material, it is preferable to use the coating layer 115 containing at least silicon and carbon, such as SiC or SiCN, which has high adhesion to this and excellent liquid resistance. In particular, in order to protect the fuse portion 112 from liquid, the thickness of the coating layer 115 is preferably 50 nm or more. In addition, since the coating layer 115 containing SiCN has a higher insulating property than the coating layer 115 made of SiC, anodic oxidation is suppressed when the heating resistor element 108 and the upper electrode 131 are electrically connected to each other, thereby forming a flow path. This is more preferable because there is less concern about peeling of the member 120 . In this embodiment, the coating layer 115 is formed using SiCN.

Further, a through hole 120 b may be formed in the flow path forming member 120 positioned above the fuse portion 112 . That is, the through-hole 120b may be formed in the flow path forming member 120 at a position overlapping the fuse portion 112 when the recording element substrate 10 is viewed from above. As a result, when the heating resistor element 108 and the upper electrode 131 are electrically connected, the heat radiation to the flow path forming member 120 side can be suppressed compared to the case where the through hole 120b is not formed, and the temperature of the fuse portion 112 can be reduced. is likely to rise, and the fuse portion 112 is likely to be disconnected. If such a through-hole 120b is formed, there is a risk that liquid will enter from the ejection port side and accumulate there. It is possible to suppress the possibility that the fuse part 112 is altered by the liquid. As for the positional relationship between the fuse portion 112 and the through hole 120b, when the recording element substrate 10 is viewed from above, at least a part of the two may overlap each other. In order to enhance the disconnectability of the fuse portion 112, it is more preferable that the fuse portion 112 is provided so that the entire fuse portion 112 is included within the range of the through hole 120b when the recording element substrate 10 is viewed from above.

Note that when the covering layer 115 is provided on the fuse portion 112, heat is more easily dissipated than in a configuration in which the covering layer 115 and the flow path forming member 120 are not provided, and the fuse portion 112 is less likely to be disconnected. Therefore, it is preferable to set the thickness of the coating layer 115 to 300 nm or less in order to suppress the influence of heat dissipation. Further, as described above, by providing the insulating layer 105 made of SiO having high heat storage property and having a thickness of 1 μm or more on the substrate 101 side of the fuse portion 112 , the disconnectability of the fuse portion 112 can be ensured.

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

(Manufacturing method of recording element substrate)
Next, the manufacturing process of the recording element substrate (liquid discharge head) according to this embodiment will be described with reference to FIGS. 7(a) to 7(i). FIG. 7 is a diagram corresponding to the cross-sectional view shown in FIG.

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

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

Next, a through hole is formed in the insulating layer 105, and a film of a plug material is formed by the CVD method so as to fill at least the through hole. Further, the surface of the insulating layer 105 is flattened by CMP to form plugs 106 (FIG. 7(c)).

Next, a heating resistor layer 107 and then a metal layer 109 made of an alloy of aluminum and copper, for example, are formed by sputtering, and this metal layer 109 is patterned. After that, 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. 7(d)).

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

Furthermore, a metal laminated film 118 of three layers, a Ta layer, an Ir layer, and a Ta layer, is formed thereon from the insulating layer 110 side by sputtering, and patterning is performed. 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)).

After that, a covering layer 115 made of SiCN is formed, and in order to expose the upper electrode 131 and the counter electrode 132, the covering layer 115 located thereon and the tantalum on the outermost surface of the three-layered metal laminated film 118 are deposited. The film is removed by dry etching (FIG. 7(g)).

After that, in order to form the terminals 16, openings are formed in the covering layer 115 and the insulating layer 110 located on the metal layer 109, and are electrically connected to the metal layer 109. A pad forming member 117 laminated with TiW is provided on the lower side (FIG. 7(h)).

Finally, as shown in FIG. 7(i), a flow path forming member 120 for forming a liquid chamber 121 for introducing liquid above the heating resistor element 108 is produced. For example, a photosensitive organic material is applied to a thickness of 5 μm by a spin coating method, and only predetermined portions are exposed. Finally, the two photosensitive organic materials are collectively developed and thermally cured to form a channel with a hollow structure.

Further, when forming the through-hole 120b located above the fuse portion 112 in the flow path forming member 120, forming the through-hole 120b in accordance with the formation of the liquid chamber 121 and the ejection port 13 is a manufacturing process. It is preferable because the load can be suppressed.

(verification test)
A plurality of verification tests conducted to confirm the effects of the present invention will be described below.

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

<Discharge durability test>
The printing element substrate of this example was filled with pigment cyan ink, and an ejection durability test was conducted. First, in order to suppress adhesion of negatively charged particles to the upper electrode 131 to suppress kogation, 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 potential for ejection was applied to the heating resistor element 108 to cause the recording element substrate to perform the ejection operation (10̂9) times.

Thereafter, when the inside of the liquid chamber 121 was replaced with clear ink and the surface condition 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 the anode, and a voltage is applied between the upper electrode 131 and the counter electrode 132 to perform cleaning processing. did At this time, in order to prevent the ink from sticking, the treatment was performed while repeatedly reversing the polarity between the upper electrode 131 and the counter electrode 132 .

Subsequently, using the same recording element substrate, five cycles were performed, each cycle including (10̂9) ejection operations and cleaning processing.

After five cycles were completed, a normal printing operation was performed according to the image data, and an output image of good quality was confirmed.

When the inside of the liquid chamber 121 was again replaced with clear ink and observed, no lifting of the flow path forming member 120 from the substrate 11 and no discoloration or cracking of the individual wiring 113 were observed. Furthermore, when the surroundings of the fuse portion 112 were observed, it was found that the covering layer 115 made of SiCN covered the surroundings of the fuse portion without floating or peeling off, and the fuse portion maintained the same state as the initial state. .

<Breaking Experiment of Fuse Portion in TEG Mode>
The relationship between the film thickness of SiO on the lower side of the fuse portion 112, that is, the side of the substrate 101, and the current value capable of disconnecting the fuse portion 112 was verified in the form of TEG.

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

As a sample 2, a TEG having a thickness of 1 μm was prepared from the 2 μm-thick SiO formed by PECVD of the sample 1. FIG. Other than that, the configuration was the same as that of the sample 1.

As a sample 3, a TEG having the same structure as the sample 1 except that the 2 μm-thick SiO formed by PECVD of the sample 1 was not provided was manufactured. That is, the sample 3 had a structure in which SiO having a thickness of 100 nm was formed on the silicon substrate side of the fuse portion 112 .

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

<Disconnection test>
Using the recording element substrate of the example used in the ejection durability test, a pulse voltage five times the voltage during normal ejection was applied to an arbitrary heating resistor element 108 to intentionally cause disconnection. The fuse portion 112 connected to the upper electrode 131 on the broken heating resistor element 108 was melted. An electrical test confirmed that the upper electrode 131 on the broken heating resistor element 108 was electrically separated from the other heating resistor elements 108 .

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

11 substrate (substrate for liquid ejection head)
108 Heating resistance element 101 Base material 110 Insulating layer 111 Protective layer (coating portion)
112 fuse portion 113 individual wiring 114 common wiring 115 insulating layer (coating layer)
120 channel forming member

Claims (16)

a substrate comprising a first heating resistor element and a second heating resistor element that generate heat to eject a liquid;
a conductive first coating covering the first heating resistor element;
a conductive second coating covering the second heating resistor element;
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 substrate on which the first covering portion is provided;
a common wiring electrically connected to the first covering portion via the fuse portion and for electrically connecting the first covering portion and the second covering portion;
an individual wiring that electrically connects the first covering portion and the fuse portion and is provided in the same layer as the fuse portion in the stacking direction of the liquid ejection head substrate;
a first opening and a second opening adjacent to each other for liquid flow;
In a liquid ejection head substrate having
a covering layer containing at least silicon and carbon and covering the fuse portion ;
When the liquid ejection head substrate is viewed from above, the first heat generating 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 arranged through a region between the first opening and the second opening,
The liquid discharge head substrate, wherein the fuse portion is located closer to the common wiring than the region . 2. The liquid ejection head substrate according to claim 1, wherein said coating layer contains SiCN. 3. The liquid ejection 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 with the fuse portion when the liquid ejection head substrate is viewed from above. substrate. 4. The liquid ejection head substrate according to claim 1, wherein said fuse portion contains tantalum. The common wiring and the fuse section are provided as the same layer in the stacking direction of the liquid ejection head substrate,
5. The liquid ejection head substrate according to claim 1, wherein the covering layer covers the common wiring. 6. The liquid ejection head substrate according to claim 1, wherein the common wiring contains tantalum. 7. The liquid according to any one of claims 1 to 6, wherein the surface of the first covering portion opposite to the surface facing the first heating resistor element is composed of a layer containing iridium. Substrate for ejection head. the fuse part 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 ejection head substrate. Substrate for ejection head. 9. The liquid ejection head substrate according to claim 1 , wherein a potential can be applied to said first covering portion through said common wiring and said fuse portion. 10. The liquid ejection head substrate according to claim 1 , wherein a 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 ejection head substrate is viewed from above. A substrate for a liquid ejection head as described above. A substrate comprising a first heating resistor element and a second heating resistor element that generate heat to eject a liquid, a conductive first coating covering the first heating resistor element, and the second heating resistor element and an insulating layer disposed between the first heating resistor element and the first coating section and between the second heating resistor element and the second coating section, and a conductive second coating section covering the and a fuse portion provided on the side of the base material on which the first covering portion is provided, and electrically connected to the first covering portion via the fuse portion so that the first covering portion and the second covering portion are electrically connected to each other. a liquid ejection head substrate including a common wiring for electrically connecting the covering portion;
a channel forming member provided on the first covering portion side of the liquid ejection head substrate and having a wall forming a channel;
In a liquid ejection head having
A liquid characterized in that the liquid ejection head substrate has a coating layer provided on the first coating portion side of the liquid ejection head substrate, containing at least silicon and carbon, and covering the fuse portion. ejection head. 12. The liquid ejection head according to claim 11 , wherein said coating layer contains SiCN. 13. The liquid ejection head according to claim 11 , wherein said fuse portion contains tantalum. 14. The liquid ejection head according to any one of claims 11 to 13 , wherein the fuse portion is provided at a position away from the wall on the side opposite to the flow path. The flow path forming member has a through hole at a position overlapping the fuse portion when the liquid ejection head substrate is viewed from above,
15. The liquid ejection head according to any one of claims 11 to 14 , wherein said coating layer has a surface exposed from said through-hole. 16. The liquid ejection head according to any one of claims 11 to 15 , wherein a potential can be applied to said first covering portion via said common wiring and said fuse portion.

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