The present invention relates to an element substrate, a liquid discharge head, and a printing apparatus, and particularly to, for example, a printing apparatus using, as a printhead, a liquid discharge head incorporating an element substrate that suppresses dissolution by ink to perform printing in accordance with an inkjet method.
There are known inkjet printheads (to be referred to as printheads hereinafter) that form ink droplets discharged by various methods. In particular, a printhead that uses a method of using heat from a heater for ink discharge can relatively easily implement multi-nozzles of high density, and can perform high-speed printing with a high resolution and high image quality.
It is known that when concurrently driving a plurality of heaters to perform printing, a voltage drop caused by wirings changes depending on the number of concurrently driven heaters, energy supplied to the heaters varies depending on the number of concurrently driven heaters, and discharge stability lowers. To solve this, a printhead described in Japanese Patent Laid-Open No. 2016-137705 uses a common wiring that makes a wiring layer connected to a heater thick and also makes the wiring layer wide as much as possible for the purpose of reducing the resistance of the wiring that causes a voltage drop.
In the printhead, an overcurrent may flow to the heater due to generation of an abnormal pulse such as noise, and an unexpected wire break may occur in the heater in the element substrate. Since the periphery of the heater in the element substrate is exposed to ink, the wiring connected to the heater is exposed to the ink at the time of a wire break. To drive remaining normal heaters, a voltage is supplied to the common wiring. As a result, electric erosion of the wiring occurs from the portion where the wire break has occurred in the heater. If this state continues, the electric erosion occurs even in the wirings of other heaters adjacent to the heater with the wire break, and the heaters may malfunction collectively from the heater with the wire break. In some printheads, recently, a technique of detecting a heater with a wire break and complementing printing by remaining normal heaters is introduced. However, if electric erosion of a wiring element spreads in the element substrate, complementary printing using remaining normal heaters is also difficult. As a result, image quality lowers.
Accordingly, the present invention is conceived as a response to the above-described disadvantages of the conventional art.
For example, an element substrate, a liquid discharge head, and a printing apparatus according to this invention are capable of suppressing spread of electric erosion of a wiring connected to a heater.
According to one aspect of the present invention, there is provided a multilayer structured element substrate including a heater layer in which a plurality of heaters are formed, and a first wiring layer in which a first common wiring configured to supply, from an outside, a voltage to the plurality of heaters is formed, comprising: an individual wiring formed in the first wiring layer and individually connected to each of the plurality of heaters; a first conductive plug provided between the heater layer and the first wiring layer and filling an interior of a first through-hole penetrating a first insulation layer that covers the first wiring layer; a second wiring layer formed in a layer under the first wiring layer; and a second conductive plug provided between the first wiring layer and the second wiring layer and filling an interior of a second through-hole penetrating a second insulation layer that covers the second wiring layer, wherein each of the plurality of heaters is connected to the individual wiring via the first conductive plug, and the individual wiring is connected to the first common wiring via the second conductive plug and a wiring of the second wiring layer, and an aspect ratio of the second through-hole is lower than an aspect ratio of the first through-hole.
According to another aspect of the present invention, there is provided a liquid discharge head using a multilayer structured element substrate including a heater layer in which a plurality of heaters are formed, and a first wiring layer in which a first common wiring configured to supply, from an outside, a voltage to the plurality of heaters is formed, comprising: a plurality of orifices configured to discharge a liquid, wherein the element substrate comprises: an individual wiring formed in the first wiring layer and individually connected to each of the plurality of heaters; a first conductive plug provided between the heater layer and the first wiring layer and filling an interior of a first through-hole penetrating a first insulation layer that covers the first wiring layer; a second wiring layer formed in a layer under the first wiring layer; and a second conductive plug provided between the first wiring layer and the second wiring layer and filling an interior of a second through-hole penetrating a second insulation layer that covers the second wiring layer, wherein each of the plurality of heaters is connected to the individual wiring via the first conductive plug, and the individual wiring is connected to the first common wiring via the second conductive plug and a wiring of the second wiring layer, and an aspect ratio of the second through-hole is lower than an aspect ratio of the first through-hole.
According to still another aspect of the present invention, there is provided a printing apparatus for performing printing on a print medium using a liquid discharge head configured to discharge a liquid as a printhead configured to discharge ink as the liquid, wherein the liquid discharge head comprises: a plurality of orifices configured to discharge the liquid; and a multilayer structured element substrate including a heater layer in which a plurality of heaters are formed, and a first wiring layer in which a first common wiring configured to supply, from an outside, a voltage to the plurality of heaters is formed, wherein the element substrate comprises: an individual wiring formed in the first wiring layer and individually connected to each of the plurality of heaters; a first conductive plug provided between the heater layer and the first wiring layer and filling an interior of a first through-hole penetrating a first insulation layer that covers the first wiring layer; a second wiring layer formed in a layer under the first wiring layer; and a second conductive plug provided between the first wiring layer and the second wiring layer and filling an interior of a second through-hole penetrating a second insulation layer that covers the second wiring layer, wherein each of the plurality of heaters is connected to the individual wiring via the first conductive plug, and the individual wiring is connected to the first common wiring via the second conductive plug and a wiring of the second wiring layer, and an aspect ratio of the second through-hole is lower than an aspect ratio of the first through-hole.
The invention is particularly advantageous since connection from a heater to a common wiring is made via the individual wiring of each heater. Hence, even if the individual wiring breaks, spread of electric erosion to the common wiring caused by the wire break is suppressed.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
Hereinafter, embodiments will be described in detail with reference to the attached drawings. Note, the following embodiments are not intended to limit the scope of the claimed invention. Multiple features are described in the embodiments, but limitation is not made an invention that requires all such features, and multiple such features may be combined as appropriate. Furthermore, in the attached drawings, the same reference numerals are given to the same or similar configurations, and redundant description thereof is omitted.
In this specification, the terms “print” and “printing” not only include the formation of significant information such as characters and graphics, but also broadly includes the formation of images, figures, patterns, and the like on a print medium, or the processing of the medium, regardless of whether they are significant or insignificant and whether they are so visualized as to be visually perceivable by humans.
Also, the term “print medium” not only includes a paper sheet used in common printing apparatuses, but also broadly includes materials, such as cloth, a plastic film, a metal plate, glass, ceramics, wood, and leather, capable of accepting ink.
Furthermore, the term “ink” (to be also referred to as a “liquid” hereinafter) should be broadly interpreted to be similar to the definition of “print” described above. That is, “ink” includes a liquid which, when applied onto a print medium, can form images, figures, patterns, and the like, can process the print medium, and can process ink. The process of ink includes, for example, solidifying or insolubilizing a coloring agent contained in ink applied to the print medium.
Further, a “nozzle” (to be also referred to as “print element” hereinafter) generically means an ink orifice or a liquid channel communicating with it, and an element for generating energy used to discharge ink, unless otherwise specified.
An element substrate for a printhead (head substrate) used below means not merely a base made of a silicon semiconductor, but an arrangement in which elements, wirings, and the like are arranged.
Further, “on the substrate” means not merely “on an element substrate”, but even “the surface of the element substrate” and “inside the element substrate near the surface”. In the present invention, “built-in” means not merely arranging respective elements as separate members on the base surface, but integrally forming and manufacturing respective elements on an element substrate by a semiconductor circuit manufacturing process or the like.
<Description of Outline of Printing Apparatus (
As shown in
In addition to the printhead 3, an ink tank 6 storing ink to be supplied to the printhead 3 is attached to the carriage 2 of the printing apparatus 1. The ink tank 6 is detachable from the carriage 2.
A printing apparatus 1 shown in
The printhead 3 according to this embodiment employs an inkjet method of discharging ink using thermal energy. Hence, the printhead 3 includes an electrothermal transducer (heater). The electrothermal transducer is provided in correspondence with each orifice. A pulse voltage is applied to a corresponding electrothermal transducer in accordance with a print signal, thereby discharging ink from a corresponding orifice. Note that the printing apparatus is not limited to the above-described serial type printing apparatus, and the embodiment can also be applied to a so-called full line type printing apparatus in which a printhead (line head) with orifices arrayed in the widthwise direction of a print medium is arranged in the conveyance direction of the print medium.
As shown in
Additionally, referring to
Reference numeral 620 denotes a switch group which is formed by a power switch 621, a print switch 622, a recovery switch 623, and the like.
Reference numeral 630 denotes a sensor group configured to detect an apparatus state and formed by a position sensor 631, a temperature sensor 632, and the like.
Reference numeral 640 denotes a carriage motor driver that drives the carriage motor M1 configured to reciprocally scan the carriage 2 in the direction of the arrow A; and 642, a conveyance motor driver that drives the conveyance motor M2 configured to convey the print medium P.
The ASIC 603 transfers data used to drive a heating element (a heater for ink discharge) to the printhead while directly accessing the storage area of the RAM 604 at the time of print scan by the printhead 3. In addition, the printing apparatus includes a display unit formed by an LCD or an LED as a user interface.
The plane of the element substrate 700 shown in
In the example shown in
As shown in
As shown in
Embodiments of the element substrate integrated on the printhead of the printing apparatus with the above-described arrangement will be described next.
Here, an element substrate having a conventional arrangement will be described first as a comparative example, and then, the features of an element substrate according to this embodiment will be described.
As shown in
Hence, to connect the VH common wiring 131 as shown in
Note that in the element substrate 700, a plurality of heaters 350 are formed in the same layer, and the layer in which the plurality of heaters are formed is also called a heater layer. Additionally, a plurality of switching elements 510 are formed in the same layer different from the heater layer, and the layer in which the plurality of switching elements are formed is also called a switching layer.
The other connecting portion 342 of the heater 350 is connected to one terminal of the switching element via the through-hole 340, the wiring layer 140, the through-hole 330, the wiring layer 130, the through-hole 320, the wiring layer 120, the through-hole 310, the wiring layer 110, and the through-hole 300. The other terminal of the switching element is connected to the GND common wiring 141 formed by the wiring layer 140 via the through-hole 300, the wiring layer 110, the through-hole 310, the wiring layer 120, the through-hole 320, the wiring layer 130, and the through-hole 330.
An ink chamber 410 is provided on the heater 350. When the switching element 510 is turned on by data supplied from the outside, a current flows to the heater 350. As the heater generates heat, the ink foams and is discharged from the orifice 420 formed by a top plate 400 of the element substrate.
As is apparent from
As shown in
Referring back to
The three through-holes shown in
The through-hole 330 shown in
In the element substrate 700, an overcurrent may flow to the heater 350 due to generation of an abnormal pulse such as noise, and an unexpected wire break may occur in the heater in the element substrate.
When a wire break occurs, the ink-tolerant anti-cavitation layer 360 is partially lost in the heater, the plug made of tungsten is exposed to the ink. In tungsten, metal dissolution by the ink progresses even if an electric potential is not applied. In addition, since the connecting portion 341 is connected to a high potential (VH) in fact, the dissolution of tungsten may further progress.
As shown in
The ink that has broken through the barrier metal layer dissolves an aluminum wiring (wiring 142) in the wiring layer 140, and dissolution similarly progresses in the through-hole 330 as well.
As shown in
As a result, the adjacent heater also malfunctions due to the wire break in one heater. The dissolution of the VH common wiring of Al may further progress, and the heaters may collectively malfunction.
<Structure of Element Substrate According to First Embodiment>
As shown in
As shown in
The detailed structure of the through-hole 320 will be described here with reference to
As shown in
On the other hand, the through-hole 330 shown in
Note that the through-hole 330 is not limited to a through-hole formed and arranged in a columnar shape as shown in
The aspect ratio at this time can be represented by the ratio of a narrow portion having an influence on the coatability to the height. For example, if the slit width is 0.6 μm, the slit length is 6.6 μm, and the height is 1.4 μm, the aspect ratio is 1.4/0.6=2.333 (independently of the slit length).
As shown in
The through-hole 320 and the through-hole 330 will be compared here. In the through-hole 330, the aspect ratio is high, the film thickness of the barrier metal layer 336 readily becomes small at the corner portion 337, and the coatability is relatively poor. Note that in the through-hole 340 as well, the aspect ratio is higher than the through-hole 320, and the coatability of the barrier metal layer 346 is relatively poor, like the through-hole 330. On the other hand, in the through-hole 320, the aspect ratio is low, and the coatability of the barrier metal layer 326 is high even at a corner portion 327. To obtain a high coatability of the barrier metal at the corner portion of the through-hole, the aspect ratio of the through-hole is preferably 2 or less.
According to the arrangement of the above-described embodiment, one terminal of the heater is connected to the VH common wiring via the through-hole whose barrier metal layer has a high coatability. Hence, even if the wiring between the heater and the VH common wiring breaks, and the plug made of tungsten is dissolved by ink, the progress of dissolution can be suppressed by the barrier metal layer of the high coatability.
That is, in this embodiment, the individual wiring 131, the through-hole 320, and the wiring layer 120, which are unnecessary as an electrical path, are provided on purpose between the heater and the VH common wiring, and the heater and the VH common wiring are electrically connected via these, thereby suppressing spread of electric erosion to the VH common wiring. In addition, since the insulation layer 220 in which the through-hole 320 is formed covers the wiring layer 120 whose film thickness is relatively small, the film thickness of the insulation layer 220 is smaller than the insulation layer 230 that covers the wiring layer 130 whose film thickness is relatively large. Hence, the aspect ratio of the through-hole 320 formed in the insulation layer 220 can easily be made low as compared to the through-hole 330 formed in the insulation layer 230, and a barrier metal layer having a high coatability can readily be formed in the through-hole 320.
As shown in
In this example, a connecting portion 341 of a heater 350 is connected to a VH common wiring 131 formed in a wiring layer 130 via a through-hole 330, a wiring 132 formed in the wiring layer 130, a through-hole 320, a wiring 121 formed in a wiring layer 120, and the through-hole 320.
As described above, the VH common wiring 131 is connected to a part of a pad 450 of the element substrate, and a voltage is supplied from the outside. The other connecting portion 342 of the heater is connected to one terminal of a switching element 510 via the through-hole 330, the wiring layer 130, the through-hole 320, the wiring layer 120, a through-hole 310, a wiring layer 110, and a through-hole 300. The other terminal of the switching element 510 is connected to a GND common wiring 133 formed in the wiring layer 130 via the through-hole 300, the wiring layer 110, the through-hole 310, the wiring layer 120, and the through-hole 320. Here, the VH common wiring 131 and the GND common wiring 133 are formed in the same wiring layer 130.
According to the above-described embodiment, the VH common wiring and the GND common wiring are formed in the same wiring layer, unlike the first embodiment. In this arrangement as well, as in the first embodiment, even if the wiring between the heater and the switching element breaks, and the plug made of tungsten is dissolved by ink, the progress of dissolution can be suppressed by the barrier metal layer of the high coatability.
In this example, through-holes 321 and 322 having different diameters and penetrating an insulation layer 220 are formed. A connecting portion 341 of a heater 350 is connected to a through-hole 330, a wiring 132 formed in a wiring layer 130, the through-hole 322, and a wiring 121 formed in a wiring layer 120. The connecting portion 341 is further connected from the wiring 121 to a VH common wiring 131 formed in the wiring layer 130 via the through-hole 322. The VH common wiring 131 is connected to a part of a pad 450 of the element substrate, and a voltage is supplied from the outside.
The other connecting portion 342 of the heater 350 is connected to one terminal of a switching element 510 via the through-hole 330, the wiring layer 130, the through-hole 322, the wiring layer 120, a through-hole 310, a wiring layer 110, and a through-hole 300. The other terminal of the switching element 510 is connected to a GND common wiring 133 formed in the wiring layer 130 via the through-hole 300, the wiring layer 110, the through-hole 310, the wiring layer 120, and the through-hole 321.
As is apparent from
Hence, according to the above-described embodiment, since the aspect ratio of the through-hole becomes lower as compared to the first embodiment, the coatability of the barrier metal layer can be made higher even at the corner portion of the through-hole.
Note that in the above-described embodiments, the printhead that discharges ink and the printing apparatus have been described as an example. However, the present invention is not limited to this. The present invention can be applied to an apparatus such as a printer, a copying machine, a facsimile including a communication system, or a word processor including a printer unit, and an industrial printing apparatus complexly combined with various kinds of processing apparatuses. In addition, the present invention can also be used for the purpose of, for example, biochip manufacture, electronic circuit printing, color filter manufacture, or the like.
The printhead described in the above embodiments can also be considered as a liquid discharge head in general. The substance discharged from the head is not limited to ink, and can be considered as a liquid in general.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2019-082198, filed Apr. 23, 2019, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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