Process for producing liquid ejection head and process for producing substrate for liquid ejection head including repeated metal layer, Si layer, N layer laminations

The invention provides a liquid ejection head including a member in which an ejection orifice for ejecting a liquid is formed, and a substrate to which the member is joined. The substrate has a heat storage layer containing a silicon compound and an energy-generating element provided at a position corresponding to the ejection orifice for generating heat by electrification to eject the liquid from the ejection orifice. The energy-generating element has a laminate having a metal layer formed of tantalum or tungsten, an Si layer laminated on the metal layer and formed of silicon and an N layer laminated on the Si layer and formed of nitrogen, and the metal layer is in contact with the heat storage layer.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid ejection head from which a liquid is ejected to conduct recording on a recording medium, a recording apparatus provided with the liquid ejection head, a process for producing the liquid ejection head, a substrate for a liquid ejection head and a process for producing the substrate for the liquid ejection head.

2. Description of the Related Art

Ink jet recording apparatus include such a type that a liquid ejection head provided with an energy-generating element for generating energy for ejecting a liquid is installed. In this type of ink jet recording apparatus, it is necessary to use an energy-generating element which is resistant to thermal stress for conducting high-speed recording. Japanese Patent No. 3554148 proposes a TaSiN film deposited by a sputtering method as an energy-generating element which is excellent in thermal responsiveness and has a high sheet resistance.

Such an ink jet recording apparatus as described above has heretofore been used as a consumer device. Specifically, it has been used as an output terminal of an information processing device such as a word processor or a computer. However, the ink jet recording apparatus has been considered to be used as an industrial device in recent years because it has such a feature that a high-definition image is recorded at a high speed.

When the application of the ink jet recording apparatus is an industrial device, the capacity of recording increases compared with the consumer device. As a result, thermal stress applied to an energy-generating element increases. When the thermal stress increases, a resistance change by structural relaxation and oxidation tends to occur, and there is a possibility that the energy-generating element may be disconnected. Therefore, when the application of the ink jet recording apparatus is an industrial device, the energy-generating element is required to have still higher thermal stress resistance.

It is an object of the present invention to provide a liquid ejection head capable of improving the thermal stress resistance of an energy-generating element, a recording apparatus provided with such a liquid ejection head, a process for producing the liquid ejection head, a substrate for a liquid ejection head and a process for producing the substrate for the liquid ejection head.

SUMMARY OF THE INVENTION

The above object can be achieved by the present invention described below.

According to the present invention, there is thus provided a liquid ejection head having a member in which an ejection orifice for ejecting a liquid is formed, and a substrate to which the member is joined, wherein the substrate has a heat storage layer containing a silicon compound and an energy-generating element provided at a position corresponding to the ejection orifice for generating heat by electrification to eject the liquid from the ejection orifice, the energy-generating element has a laminate having a metal layer formed of tantalum or tungsten, an Si layer laminated on the metal layer and formed of silicon and an N layer laminated on the Si layer and formed of nitrogen, and the metal layer is in contact with the heat storage layer.

According to the present invention, there is also provided a recording apparatus comprising the above-described liquid ejection head.

According to the present invention, there is further provided a process for producing a liquid ejection head having a member in which an ejection orifice for ejecting a liquid is formed, and a substrate to which the member is joined and on which a heat storage layer containing a silicon compound is formed, the process including the steps of laminating a metal layer formed of tantalum or tungsten on a surface of the heat storage layer, laminating an Si layer formed of silicon on a surface of the metal layer, and laminating an N layer formed of nitrogen on the Si layer.

According to the present invention, there is still further provided a substrate for a liquid ejection head, including a base on which a heat storage layer containing a silicon compound is formed, and an energy-generating element provided on the side of the heat storage layer for generating energy for ejecting a liquid by electrification, wherein the energy-generating element has a laminate having a metal layer formed of tantalum or tungsten, an Si layer laminated on the metal layer and formed of silicon and an N layer laminated on the Si layer and formed of nitrogen, and the metal layer is in contact with the heat storage layer.

According to the present invention, there is yet still further provided a process for producing a substrate for a liquid ejection head, including the steps of laminating a metal layer formed of tantalum or tungsten on a surface of a heat storage layer containing a silicon compound and formed on a substrate, laminating an Si layer formed of silicon on a surface of the metal layer, and laminating an N layer formed of nitrogen on the Si layer.

DESCRIPTION OF THE EMBODIMENTS

A liquid ejection head according to the present invention can be installed in an apparatus such as a printer, a copying machine, a facsimile having a communication system or a word processor having a printer section, and further in an industrial recording apparatus integrally combined with various processors. When the liquid ejection head according to the present invention is used, recording can be performed on various recording media such as paper, thread, fiber, fabric, leather, a metal, a plastic, glass, wood and ceramic.

The term “recording” used in the present specification means not only applying an image having a meaning such as a letter or a figure to a recording medium, but also applying an image having no meaning such as a pattern.

The term “liquid” should be widely interpreted and means a liquid used in formation of, for example, an image, a design or a pattern, processing of a recording medium, or treatment of an ink or a recording medium by applying it on to the recording medium. The treatment of the ink or the recording medium means, for example, a treatment for improving the fixing ability of the ink by solidification or insolubilization of a coloring material in the ink applied to the recording medium, or improving recording quality, color developability or image durability. In addition, such “liquid” as used in a liquid ejection device according to the present invention generally contains a large amount of an electrolyte and has conductivity.

The recording apparatus according to the present invention is first described.

FIG. 1Ais a perspective view of a recording apparatus according to the present invention. When a drive motor11is rotated in a recording apparatus1illustrated inFIG. 1A, power is transmitted to a lead screw14through driving force transmitting gears12and13, whereby the lead screw14is also rotated in conjunction with the rotation of the drive motor11. A spiral groove15is formed in the lead screw14. A carriage16is engaged with the spiral groove15. When the lead screw14is rotated, the carriage16is reciprocatingly moved in a widthwise direction (see arrows ‘a’ and ‘b’ inFIG. 1A) of a recording medium P. A head unit2is mounted on the carriage16.

FIG. 1Bis a perspective views of a head unit mounted in the recording apparatus illustrated inFIG. 1A. As illustrated inFIG. 1B, a liquid ejection head21is in conduction with a contact pad24through a flexible film wiring substrate23. The contact pad24is electrically connected to an apparatus body. In this embodiment, the liquid ejection head21is integrated with an ink tank22. However, in the present invention, the ink tank22may have a structure separated from the liquid ejection head21.

The liquid ejection head21will hereinafter be described.

FIG. 2is a perspective view of a liquid ejection head constituting the head unit illustrated inFIG. 1B. The liquid ejection head21illustrated inFIG. 2has a substrate3(a substrate for the liquid ejection head) provided with energy-generating elements32aand a flow path forming member4joined to the substrate3and mainly formed of a thermosetting resin such as an epoxy resin. The energy-generating elements32aare arranged at predetermined intervals along a long side direction of a supply port36passing through the substrate3. Plural ejection orifices41for ejecting a liquid, plural flow paths42communicating with the respective ejection orifices41, and walls43partitioning the respective flow paths42are formed in the flow path forming member4. The ejection orifice41is provided at a position corresponding to the energy-generating element32aacross the flow path42. Plural terminals35are provided at an end portion of the substrate3. Electric power for driving the energy-generating element32aand a logic signal for controlling a drive element (not illustrated) such as a transistor are sent to the respective terminals35from the apparatus body.

In the liquid ejection head21constituted in the above-described manner, liquid is sent to the flow path42from the supply port36. Thereafter, when the energy-generating element generates heat by electrification, the liquid causes film-boiling to produce a bubble. The liquid is ejected from the ejection orifice41by a pressure of the bubble, whereby a recording operation is performed.

FIG. 3Ais a sectional view taken along a cutting plane line3A-3A inFIG. 2. As illustrated inFIG. 3A, a heat storage layer31is laminated on the surface of a base30formed of silicon. The heat storage layer31is constituted by a thermal oxidation layer formed by thermally oxidizing a part of the base30and a silicon compound formed by using, for example, a CVD (chemical vapor deposition) method. Examples of the silicon compound include SiO, SiN, SiON, SiOC and SiCN. The heat storage layer31not only stores heat, but also functions as an insulating layer.

A heating resistor layer32is laminated on the surface of the heat storage layer31. FIGS.3B and3BP are enlarged views of a part ofFIG. 3A. As illustrated in FIG.3BP, the heating resistor layer32is constituted by plural laminates321. Each laminate321is constituted by a metal layer321a, an Si layer321blaminated on the metal layer321aand an N layer321claminated on the Si layer321b. The material of the metal layer321ais tantalum (Ta) or tungsten (W). The metal layer321athat is an undermost layer is in contact with the heat storage layer31. Each laminate321is deposited by stacking atoms respectively constituting the metal layer321a, the Si layer321band the N layer321cone layer after another by an atomic layer deposition (ALD) method.

A pair of electrodes33are laminated on the surface (uppermost N layer321c) of the heating resistor layer32. The material of the pair of electrodes33is a material with an electric resistance lower than that of the metal layer321a(for example, aluminum). When a voltage is applied to the pair of electrodes33, the energy-generating element32athat is a portion located between the pair of electrodes33of the heating resistor layer32generates heat. In order to insulate the energy-generating element32aand the pair of electrodes33from the liquid, an insulating layer34is formed. The material of the insulating layer34is an insulating material containing a silicon compound such as SiN.

In this embodiment, the flow path forming member4is directly joined to the insulating layer34. However, an adhesion layer formed of, for example, a polyether amide resin may also be formed between the insulating layer34and the flow path forming member4. The use of this adhesion layer improves the adhesion of the insulating layer34to the flow path forming member4.

Examples of the present invention will hereinafter be described.

In this example, a deposition device5according to an atomic layer deposition method as illustrated inFIG. 4is used to form a heating resistor layer32.

(1) Deposition Process for Metal Layer

In the deposition device5, TaCl5(tantalum pentachloride) gas is introduced into a gas introduction port501from a valve511. The TaCl5gas is generated by heating a container containing TaCl5and is then discharged with a carrier gas. The TaCl5gas is fed at a rate of 0.05 to 0.5 g/cycle by setting the introduction time of the carrier gas within a range of 0.5 seconds or more and 8.0 seconds or less. The introduction time of the TaCl5gas is set within a range of 0.5 seconds or more and 8.0 seconds or less. The TaCl5gas introduced into the gas introduction port501passes through a quartz tube507. A high frequency power source508electrifies a high frequency applying coil502upon the passage through the quartz tube507. The TaCl5gas is thereby activated. The activated TaCl5gas is ejected from plural holes506formed in a shower plate503. Thus, TaCl5is deposited on a substrate504. The substrate504is a member obtained by forming a heat storage layer31on the surface of a base30. In this example, the heat storage layer31contains silicon oxide (SiO) deposited by plasma CVD. The substrate504is mounted on a stage505. The stage505is heated to 200° C. or more and 400° C. or less. As illustrated inFIG. 4, the shower plate503and the stage505are arranged within a chamber510.

After TaCl5is deposited on the substrate504, the TaCl5gas remaining in the chamber510is exhausted under reduced pressure from an exhaust port509. In order to remove Cl (chlorine) constituting TaCl5, hydrogen gas is then introduced into the gas introduction port501from the valve511. The flow rate of the hydrogen gas is controlled to 500 sccm or more and 3,000 sccm or less by the mass flow meter512. The introduction time of the hydrogen gas is set to 6 seconds or more. The hydrogen gas introduced into the gas introduction port501passes through the quartz tube507. The high frequency power source508electrifies the high frequency applying coil502upon the passage through the quartz tube507. The hydrogen gas is thereby activated. The activated hydrogen gas is ejected from the holes506. Thereupon, the hydrogen reacts with the TaCl5deposited on the substrate504. The chlorine (Cl) is removed by this reaction. Thereafter, the hydrogen gas remaining in the chamber510is exhausted under reduced pressure from the exhaust port509. As a result, a metal layer321aformed of tantalum (Ta) is deposited on the surface of the heat storage layer31. In this example, the thickness of the metal layer321ais 2×10−10m.

(2) Deposition Process for Si Layer

After the metal layer321ais deposited, SiH4gas is introduced into the gas introduction port501from the valve511. The flow rate of the SiH4gas is controlled to 80 sccm or more and 500 sccm or less by the mass flow meter512. The introduction time of the SiH4gas is set within a range of 2 seconds or more and 30 seconds or less. The SiH4gas introduced into the gas introduction port501passes through the quartz tube507. The high frequency power source508electrifies the high frequency applying coil502upon the passage through the quartz tube507. The SiH4gas is thereby activated. The activated SiH4gas is ejected from the holes506. Thus, Si (silicon) is deposited on the surface of the metal layer321adeposited on the substrate504. At this time, the stage505on which the substrate504is mounted is heated to 200° C. or more and 400° C. or less. Thereafter, the SiH4gas remaining in the chamber510is exhausted under reduced pressure from the exhaust port509. As a result, an Si layer321bformed of silicon is deposited on the surface of the metal layer321a. In this example, the thickness of the Si layer321bis 2×10−10m.

(3) Deposition Process for N Layer

After the Si layer321bis deposited, a mixed gas of nitrogen and hydrogen is introduced into the gas introduction port501from the valve511. The flow rate of the mixed gas is controlled to 150 sccm or more and 3,000 sccm or less by the mass flow meter512. The introduction time of the mixed gas is set within a range of 10 seconds or more and 30 seconds or less. The mixed gas introduced into the gas introduction port501passes through the quartz tube507. The high frequency power source508electrifies the high frequency applying coil502upon the passage through the quartz tube507. The mixed gas is thereby activated. The activated mixed gas is ejected from the holes506. Thus, nitrogen is deposited on the surface of the Si layer321bformed on the substrate504. At this time, the stage505on which the substrate504is mounted is heated to 200° C. or more and 400° C. or less. Thereafter, the mixed gas remaining in the chamber510is exhausted under reduced pressure from the exhaust port509. As a result, an N layer321cformed of nitrogen is deposited on the surface of the Si layer321b. In this example, the thickness of the N layer321cis 1.4×10−10m.

The above-described deposition processes (1), (2) and (3) are performed repeatedly 32 times, thereby completing the heating resistor layer32of Example 1. In this example, the thickness of the heating resistor layer32is about 200×10−10m. The specific resistance of the heating resistor layer32is 400 μΩ·cm.

In this example, the deposition device5is used in the same manner as in Example 1 to form a heating resistor layer32. Incidentally, regarding the same contents as in Example 1, the description thereof is omitted.

(1) Deposition Process for Metal Layer

In the deposition device5, WF6gas is introduced into the gas introduction port501from the valve511. The flow rate of the WF6gas is controlled to 100 sccm or more and 1,500 sccm or less by the mass flow meter512. The introduction time of the WF6gas is set within a range of 1 second or more and 5 seconds or less. The WF6gas introduced into the gas introduction port501passes through the quartz tube507. The high frequency power source508electrifies the high frequency applying coil502upon the passage through the quartz tube507. The WF6gas is thereby activated. The activated WF6gas is ejected from the holes506. Thus, WF6is deposited on the substrate504. The substrate504is mounted on the stage505. The stage505is heated to 200° C. or more and 400° C. or less.

After WF6is deposited on the substrate504, the WF6gas remaining in the chamber510is exhausted under reduced pressure from the exhaust port509. In order to remove F (fluorine) constituting WF6, hydrogen gas is then introduced into the gas introduction port501from the valve511. The flow rate of the hydrogen gas is controlled to 500 sccm or more and 3,000 sccm or less by the mass flow meter512. The introduction time of the hydrogen gas is set to 6 seconds or more. The hydrogen gas introduced into the gas introduction port501passes through the quartz tube507. The high frequency power source508electrifies the high frequency applying coil502upon the passage through the quartz tube507. The hydrogen gas is thereby activated. The activated hydrogen gas is ejected from the holes506. Thereupon, the hydrogen reacts with the WF6deposited on the substrate504. The fluorine is removed by this reaction. Thereafter, the hydrogen gas remaining in the chamber510is exhausted under reduced pressure from the exhaust port509. As a result, a metal layer321aformed of tungsten (W) is deposited on the surface of the heat storage layer31. In this example, the thickness of the metal layer321ais 2.8×10−10m.

(2) Deposition Process for Si Layer

An Si layer321bformed of silicon is deposited on the surface of the metal layer321aaccording to the same process as the process (2) of Example 1.

(3) Deposition Process for N Layer

An N layer321cformed of nitrogen is deposited on the surface of the Si layer321baccording to the same process as the process (3) of Example 1.

The above-described deposition processes (1), (2) and (3) are performed repeatedly 33 times, thereby completing the heating resistor layer32of Example 2. In this example, the thickness of the heating resistor layer32is about 200×10−10m. The specific resistance of the heating resistor layer32is 360 μΩ·cm.

COMPARATIVE EXAMPLE 1

In this comparative example, a heating resistor layer was deposited by performing the deposition processes of Example 1 in the order of (2), (1) and (3). That is to say, the heating resistor layer of Comparative Example 1 is a laminate of the order of the Si layer321b, the metal layer321aformed of tantalum and the N layer321c. The deposition processes are performed repeatedly 32 cycles in the above-described order, thereby completing the heating resistor layer of Comparative Example 1. In this comparative example, the thickness of the heating resistor layer is about 200×10−10m. The specific resistance of the heating resistor layer is 360 μΩ·cm.

COMPARATIVE EXAMPLE 2

In this comparative example, a heating resistor layer was deposited by performing the deposition processes of Example 1 in the order of (3), (1) and (2). That is to say, the heating resistor layer of Comparative Example 2 is a laminate of the order of the N layer321c, the metal layer321aformed of tantalum and the Si layer321b. The deposition processes are performed repeatedly 32 cycles in the above-described order, thereby completing the heating resistor layer of Comparative Example 2. In this comparative example, the thickness of the heating resistor layer is about 200×10−10m.

COMPARATIVE EXAMPLE 3

In this comparative example, a heating resistor layer was deposited by performing the deposition processes of Example 2 in the order of (2), (1) and (3). That is to say, the heating resistor layer of Comparative Example 3 is a laminate of the order of the Si layer321b, the metal layer321aformed of tungsten and the N layer321c. The deposition processes are performed repeatedly 32 cycles in the above-described order, thereby completing the heating resistor layer of Comparative Example 3. In this comparative example, the thickness of the heating resistor layer is about 200×10−10m. The specific resistance of the heating resistor layer is 360 μΩ·cm.

COMPARATIVE EXAMPLE 4

In this comparative example, a heating resistor layer was deposited by performing the deposition processes of Example 2 in the order of (3), (1) and (2). That is to say, the heating resistor layer of Comparative Example 4 is a laminate of the order of the N layer321c, the metal layer321aformed of tungsten and the Si layer321b. The deposition processes are performed repeatedly 32 cycles in the above-described order, thereby completing the heating resistor layer of Comparative Example 4. In this comparative example, the thickness of the heating resistor layer is about 200×10−10m.

COMPARATIVE EXAMPLE 5

In this comparative example, a heating resistor layer formed of Ta33.3Si33.3N33.4was deposited by means of a binary sputtering method. Specific deposition conditions are such that the substrate temperature is 150° C., gas flow rate ratio of N/Ar+N is 10%, applied electric power to an Si target is 700 W, and applied electric power to a Ta target is 480 W. In this comparative example, the specific resistance of the heating resistor layer is 410 μΩ·cm.

COMPARATIVE EXAMPLE 6

In this comparative example, a heating resistor layer formed of Ta35Si19.4N45.6was deposited by means of the binary sputtering method. Specific deposition conditions are such that the substrate temperature is 150° C., gas flow rate ratio of N/Ar+N is 18%, applied electric power to an Si target is 650 W, and applied electric power to a Ta target is 480 W. In this comparative example, the specific resistance of the heating resistor layer is 410 μΩ·cm.

COMPARATIVE EXAMPLE 7

In this comparative example, a heating resistor layer formed of W33.3Si33.3N33.4was deposited by means of the binary sputtering method. Specific deposition conditions are such that the substrate temperature is 150° C., gas flow rate ratio of N/Ar+N is 15%, applied electric power to an Si target is 700 W, and applied electric power to a tungsten (W) target is 410 W. In this comparative example, the specific resistance of the heating resistor layer is 650 μΩ·cm.

Film Quality Evaluation

The film qualities of the heating resistor layers of the respective examples and the film qualities of the heating resistor layers of the respective comparative examples were evaluated by means of TEM (transmission electron microscope). Evaluation results are illustrated inFIG. 5. InFIG. 5, a heating resistor layer in which atoms (Ta or W, Si and N) are deposited layeredly one layer after another is evaluated as “A”. A heating resistor layer in which the atoms are partially layeredly deposited is evaluated as “B”. A heating resistor layer in which the atoms are not deposited layeredly is evaluated as “C”.

When referring toFIG. 5, Comparative Examples 2 and 4 are evaluated as “B”. In Comparative Examples 2 and 4, the nitrogen atom is unevenly deposited on silicon oxide (SiO) of the heat storage layer31, so that the film qualities thereof are poor compared with Examples 1 and 2. In Comparative Examples 5 to 7, the film quantities are evaluated as “C”. Since the sputtering method is employed in Comparative Examples 5 to 7, the respective atoms are arranged at random. That is to say, the heating resistor layers of Comparative Examples 5 to 7 are composed of a single layer in which the tantalum (or tungsten) atom, the silicon atom and the nitrogen atom are mixedly present.

Structure Evaluation

The structures of the heating resistor layers of the respective examples and the structures of the heating resistor layers of the respective comparative examples were evaluated by means of XRD (X-ray diffraction). Evaluation results are illustrated inFIG. 5. When referring toFIG. 5, a heating resistor layer in the case where the atom in contact with the heat storage layer31(silicon compound) is a metal (tantalum or tungsten) or nitrogen has an amorphous structure. On the other hand, a heating resistor layer in the case where the atom in contact with the heat storage layer31(silicon compound) is silicon has a crystalline structure.

Thermal Stress Evaluation

Liquid ejection heads respectively having the heating resistor layers of the respective examples and the respective comparative examples were prepared according to the above-described constitution to make thermal stress evaluation (constant stress test). In this thermal stress evaluation, a voltage pulse is applied to each energy-generating element at a predetermined frequency. The peak value of the voltage pulse is a value of 1.3 times as much as a threshold voltage (Vth) for ejecting an ink. The voltage pulse width is 0.8 μs. Such a voltage pulse is continuously applied until the energy-generating element is disconnected. Evaluation results are shown inFIG. 5. InFIG. 5, the thermal stress resistance is evaluated as “A” in the case where the number of pulses (referred to as “the number of pulses upon the disconnection”) when the energy-generating element caused disconnection exceeds 2×1010. The thermal stress resistance is evaluated as “B” in the case where the number of pulses upon the disconnection exceeds 5×109. The thermal stress resistance is evaluated as “C” in the case where the number of pulses upon the disconnection is 1×109or less. When referring toFIG. 5, the thermal stress resistance when the atoms are deposited layeredly is superior to the case where the atoms are partially layeredly deposited, or the atoms are not deposited layeredly, and the thermal stress resistance in the case where the heating resistor layer has the amorphous structure is superior to the case where the heating resistor layer has the crystalline structure.

As apparent from the evaluation results of the film quality, the metal layer321aor the Si layer321brequires to come into contact with the heat storage layer31containing the silicon compound in order to deposit the heating resistor layer layeredly on the surface of the heat storage layer31. When the metal layer321acomes into contact with the heat storage layer31, the heating resistor layer has an amorphous structure. When the Si layer321bcomes into contact with the heat storage layer on the other hand, the heating storage layer has a crystalline structure. The amorphous structure is excellent in thermal stress resistance compared with the crystalline structure because the amorphous structure has no grain boundary. In addition, the heating resistor layer deposited by stacking plural atoms layeredly is harder to cause structural relaxation by thermal stress than the heating resistor layer deposited by the sputtering method.

Accordingly, by bringing the metal layer321ainto contact with the surface of the heat storage layer31and depositing the metal layer321a, the Si layer321band the N layer321clayeredly, the thermal stress resistance can be improved. As a result, reliability against the thermal stress can be ensured even when the capacity of recording increases.

According to the present invention, the thermal stress resistance of the energy-generating element can be improved.

This application claims the benefit of Japanese Patent Application No. 2013-051814, filed Mar. 14, 2013, which is hereby incorporated by reference herein in its entirety.