JP2012245675A - Liquid ejection head, substrate for liquid ejection head, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problems: sufficient amount of ink cannot be refilled due to steps in a channel and high-speed ejection frequencies required recently cannot be achieved.SOLUTION: An energy generation element to be used for ejecting liquid is driven to heat a protective layer. A potential difference is applied to between liquid in contact with the protective layer and the protective layer, to form an oxidation layer on a surface of the protective layer.

Description

  The present invention relates to a liquid discharge head, a substrate for a liquid discharge head, and methods for manufacturing the same.

  A typical liquid discharge head used in a liquid discharge apparatus includes a liquid discharge head substrate having a plurality of energy generating elements that generate thermal energy used for discharging a liquid, and a liquid discharge port. And a discharge port member. The energy generating element is provided with a heat generating resistor layer that generates heat when energized and a pair of electrodes used to energize the heat generating resistor layer. A voltage is applied to the pair of electrodes to generate heat by the heat generating resistive layer generating heat, and a recording operation is performed by discharging the liquid from the discharge port with the pressure of the bubbles.

  Such an energy generating element is covered with an insulating layer made of an insulating material. Furthermore, it is known that a protective layer or an oxide layer made of tantalum or the like is provided on the insulating layer in order to protect the energy generating element from cavitation impact accompanying the disappearance of bubbles and chemical action by liquid.

  A manufacturing method of such a liquid discharge head is disclosed in Patent Document 1, and a cross-sectional view of the liquid discharge head disclosed in Patent Document 1 is shown in FIG. In the manufacturing method disclosed in Patent Document 1, tantalum is formed on an insulating layer 106 that protects a heating resistor layer 104 and a pair of electrodes 105 that form an energy generation element 108 that is first provided on a substrate 101. A protective layer 107 is provided. Further, by energizing between the protective layer 107 and the electrode 124 in contact with the ink 110 using the electrode 123 connected to the protective layer 107, the surface of the protective layer 107 made of tantalum or the like in contact with the ink is made of tantalum oxide or the like. An oxide layer 122 is formed.

Japanese Patent Laid-Open No. 7-309909

  However, since the liquid discharge head provided by the manufacturing method of Patent Document 1 has the oxide layer 122 uniformly formed on the surface of the protective layer 107 in contact with the ink, the step caused by the pair of electrodes 105 generates energy as it is. It appears on the surface of the element 108. Since such a step becomes a flow resistance when the ink is filled in the flow path, the ink cannot be sufficiently refilled in the flow path, and there is a concern that a high-speed ejection frequency as required in recent years cannot be achieved. is there.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a liquid discharge head that can reduce the level difference on the surface of the energy generating element that contacts the ink.

The heating resistor layer made of a material that generates heat when energized according to the present invention, the pair of electrodes used for energization provided to be in contact with the heating resistor layer, the heating resistor layer, and the pair of electrodes are covered and insulated. An insulating layer made of a conductive material, a protective layer made of a metal material on the insulating layer, and covering at least a region of the heating resistor layer corresponding to the pair of electrodes, and the protective layer A liquid discharge head substrate serving as an energy generating element for generating energy for discharging the liquid from the discharge port, and a flow path wall communicating with the discharge port. A liquid discharge head manufacturing method having a flow path member,
The base having the heating resistance layer, the pair of electrodes, the insulating layer, and the protective layer, and the flow path forming the flow path by being provided so as to be in contact with the base with the wall inside. A step of preparing a member;
Supplying a liquid having conductivity to the flow path;
By energizing between the pair of electrodes, the portion of the protective layer corresponding to the energy generating element is heated to a temperature at which the liquid does not boil, and in parallel with the heating, the liquid in the flow path A step of oxidizing a part of the protective layer on the flow path side by applying a potential difference with the protective layer to form the oxide layer.

  By providing as described above, a thick oxide layer can be selectively provided between the pair of electrodes, and a step on the surface of the energy generating element in contact with ink can be reduced. As a result, the ink flow resistance can be reduced, and a recording operation can be performed at a high ejection frequency.

1 is an example of a liquid discharge apparatus and a liquid discharge head unit that can use the liquid discharge head of the present invention. FIG. 2 schematically shows a perspective view and a sectional view of a liquid discharge head according to the present invention. It is a figure explaining the manufacturing method of the liquid discharge head which concerns on 1st Embodiment. It is a figure explaining the manufacturing method of the liquid discharge head which concerns on 2nd Embodiment. FIG. 6 is a schematic top view of a part of a liquid ejection head according to a second embodiment. FIG. 2 schematically shows a cross-sectional view of a conventional liquid discharge head.

  The liquid discharge head can be mounted on an apparatus such as a printer, a copying machine, a facsimile having a communication system, a word processor having a printer unit, or an industrial recording apparatus combined with various processing apparatuses. By using this liquid discharge head, recording can be performed on various recording media such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, and ceramics.

  “Recording” used in this specification means not only giving an image having a meaning such as a character or a figure to a recording medium but also giving an image having no meaning such as a pattern. I decided to.

  Furthermore, the term “ink” should be widely interpreted and applied to a recording medium to form an image, pattern, pattern, etc., process the recording medium, or process the ink or recording medium. It shall refer to the liquid provided. Here, as the treatment of the ink or the recording medium, for example, the fixing property is improved by coagulation or insolubilization of the coloring material in the ink applied to the recording medium, the recording quality or coloring property is improved, and the image durability is improved. Say things like improvement.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, components having the same function may be given the same reference numerals in the drawings, and the description thereof may be omitted.

(Liquid discharge device)
FIG. 1A is a schematic view showing a liquid discharge apparatus capable of mounting a liquid discharge head according to the present invention.
As shown in FIG. 1A, the lead screw 5004 rotates via the driving force transmission gears 5011 and 5009 in conjunction with the forward and reverse rotation of the driving motor 5013. The carriage HC can mount a head unit, and has a pin (not shown) that engages with the spiral groove 5005 of the lead screw 5004. The lead screw 5004 rotates to reciprocate in the directions of arrows a and b. Is done. A head unit 40 is mounted on the carriage HC.

(Head unit)
FIG. 1B is a perspective view of a head unit 40 that can be mounted on the liquid ejection apparatus as shown in FIG. A liquid discharge head 41 (hereinafter also referred to as a head) is electrically connected to a contact pad 44 connected to the liquid discharge device by a flexible film wiring substrate 43. The head 41 is integrated with the ink tank 42 to constitute a head unit 40. The head unit 40 shown as an example here is one in which the ink tank 42 and the head 41 are integrated, but may be a separation type that can separate the ink tank.

(Liquid discharge head)
FIG. 2A is a perspective view of the liquid discharge head 41 according to the present invention. 2B is a cross-sectional view schematically showing a state of a cut surface when the liquid discharge head 41 is cut perpendicularly to the substrate 5 along AA ′ in FIG.

  The liquid discharge head 41 includes a liquid discharge head substrate 5 including an energy generation element 12 that generates thermal energy used for discharging a liquid, and a flow path formed on the liquid discharge head substrate 5. And a member 14. The arrangement density of the energy generating elements is about 1200 dpi. The flow path forming member 14 can be provided by a cured product of a thermosetting resin such as an epoxy resin, and has a discharge port 13 for discharging a liquid and a wall 14 a of the flow path 46 communicating with the discharge port 13. is doing. With the wall 14 a inside, the flow path forming member 14 is in contact with the liquid discharge head substrate 5, thereby providing the flow path 46. The discharge ports 13 provided in the flow path forming member 14 are provided so as to form a line at a predetermined pitch along the supply port 45. The liquid supplied from the supply port 45 is conveyed to the flow path 46, and bubbles are generated by the film boiling of the liquid by the thermal energy generated by the energy generating element 12. The recording operation is performed by discharging the liquid from the discharge port 13 by the pressure generated at this time. Further, the liquid discharge head 41 is a terminal 17 that makes an electrical connection between a supply port 45 provided through the liquid discharge head substrate 5 in order to send the liquid to the flow path 46 and the outside, for example, a liquid discharge device. And have. By applying a voltage to the terminal 17 from the outside, the energy generating element 12 can be energized to discharge the liquid.

  As shown in FIG. 2B, the liquid discharge head 41 has a cross section in which a heat storage layer 4 made of a silicon compound is provided on a substrate 1 made of silicon provided with a driving element (not shown) such as a transistor. It has been. On the heat storage layer 4, a heat generating resistance layer 6 made of a material that generates heat when energized (for example, TaSiN, WSiN, etc.) is provided, and aluminum having a lower resistance than the heat generating resistance layer 6 is in contact with the heat generating resistance layer 6. A pair of electrodes 7 made of a material containing as a main component is provided. A voltage is supplied between the pair of electrodes 7 to generate heat in a portion located between the pair of electrodes 7 of the heating resistor layer 6, so that the portion of the heating resistor layer 6 is used as the energy generating element 12. The heat generating resistance layer 6 and the pair of electrodes 7 are covered with an insulating layer 8 made of an insulating material such as a silicon compound such as SiN in order to insulate from a liquid used for discharging ink or the like. Further, in order to protect the energy generating element 12 from cavitation impact caused by foaming and contraction of liquid for ejection, the protective layer 10 used as an anti-cavitation layer on the insulating layer 8 corresponding to the energy generating element 12 portion. Is provided. Specifically, a metal material such as tantalum can be used for the protective layer 10. Further, an oxide layer 11 made of an oxide of a material used for the protective layer is provided on the portion of the energy generating element 12 that is in contact with the ink. When the protective layer 10 made of tantalum is provided, it is preferable to provide the oxide layer 11 made of tantalum oxide in order to ensure adhesion. Since the portion where the pair of electrodes 7 is provided is convex with respect to the surface of the substrate, there is a large step between the portion where the pair of electrodes 7 is provided and the portion where the pair of electrodes 7 are not provided. Therefore, by providing the oxide layer 11 thicker in the region of the energy generating element 12 between the pair of electrodes 7 than on the pair of electrodes 7, it is possible to reduce the level difference on the surface of the energy generating element that contacts the ink. it can. By reducing the step around the energy generating element 12 in this way, the ink flow resistance in the flow path 46 can be reduced, ink can be supplied at high speed, and a recording operation can be performed at a high ejection frequency. it can.

  Hereinafter, the manufacturing process of the manufacturing method of such a liquid discharge head will be specifically described with reference to the drawings.

(First embodiment)
FIG. 3 is a cross-sectional view schematically showing the state of the cut surface in each step when the liquid ejection head 41 is cut perpendicularly to the substrate 5 along AA ′ in FIG.
A substrate 1 made of silicon provided with a drive element (not shown) such as a MOS transistor used for driving the energy generating element 12 is prepared. Further, a heat storage layer 4 made of silicon oxide (SiO 2) having a film thickness of about 500 nm to 1 μm is provided on the substrate 1 by using a CVD method or the like. On the heat storage layer 4, a heating resistance layer 6 made of a material that generates heat when energized, such as TaSiN or WSiN having a film thickness of about 10 nm to 50 nm, and aluminum having a film thickness of about 100 nm to 1 μm to be a pair of electrodes 7 are main components. A conductive layer is formed by a sputtering method. Further, the heating resistor layer 6 and the conductive layer are processed into a pattern shape using a dry etching technique such as RIE, and a part of the conductive layer is removed using a wet etching technique to provide a pair of electrodes 7. The heating resistor layer 6 corresponding to the portion from which the conductive layer has been removed is used as the energy generating element 12 (FIG. 3A).

  Next, an insulating layer 8 having a film thickness of about 100 nm to 1 μm made of silicon nitride (SiN) or the like is provided on the entire surface of the substrate by CVD or the like so as to cover the heating resistance layer 6 and the pair of electrodes 7 ( FIG. 3 (b)).

  Next, a conductive layer having a film thickness of 50 nm to 500 nm is sputtered on the insulating layer 8 using a metal material that has conductivity and can be protected from cavitation impact caused by foaming and contraction of liquid. Form using the method. Further, using a dry etching technique, patterning is performed to form the protective layer 10 at a position corresponding to the energy generating element 12 (FIG. 3C). Here, a case where a metal material containing tantalum as a main component is formed to a thickness of 300 nm will be described.

  Next, a soluble resin is formed on the surface of the liquid discharge head substrate 5 by using a spin coating method, and patterning is performed by using a photolithography technique to form a mold material in a portion that becomes the flow path 46 (not shown). . Furthermore, the flow path forming member 14 is formed by forming a cationic polymerization type epoxy resin on the mold material using a spin coating method, and then baking and curing using a hot plate. Thereafter, the flow path forming member 14 in a portion that becomes the discharge port 13 is removed by using a photolithography technique. Next, from the back surface of the surface of the substrate 1 on which the energy generating element 12 is provided, the silicon substrate 1 is etched using a tetramethylammonium hydroxide solution (TMAH solution) or the like to form a through-hole serving as the supply port 45. Form. The substrate 1 can be provided with the supply port 45 by crystal anisotropic etching using an alkaline solution (for example, TMAH solution) by using a silicon single crystal substrate having a (100) crystal orientation on the surface. In such a base, since the etching rate of the (111) plane is very slow compared to the etching rate of other crystal planes, a supply port 45 that forms an angle of about 54.7 degrees with respect to the silicon substrate plane can be provided. . Thereafter, the mold material is removed to complete a flow path forming member having the discharge port 13 and the wall 14a of the flow channel 46 on the liquid discharge head substrate 5 provided with the energy generating element 12 and the supply port 45. (FIG. 3 (d)). As a method for forming the supply port 45, not only a wet etching method but also a dry etching method may be used.

  Next, a liquid having conductivity is supplied from the supply port 45 of the substrate 1, and the liquid 22 is filled in the flow path (FIG. 3E). The liquid filled in the flow path may be any liquid having conductivity, and ink can be used. At this time, the liquid may be filled by suction from the discharge port 13. The liquid 22 is provided in contact with the base 1 made of silicon exposed at the supply port 45. Since the substrate 1 made of silicon is grounded via the terminal 17 and the like, it has a ground potential (also referred to as a GND potential), so the liquid 22 filled in the flow path is also at the GND potential.

  Next, the pair of electrodes 7 is energized and heated using conditions that prevent the liquid from boiling the film so that the temperature of the surface of the energy generating element 12 facing the ink (flow path) is 200 ° C. or higher. The energy generating element 12 can be heated up to 600 ° C.

  Further, while heating the portion of the energy generating element 12 facing the liquid 22, a voltage of about 20 V is applied to the terminal 23 so that the protective layer 10 becomes an anode with respect to the liquid 22. By heating the protective layer 10 to 200 ° C. or higher and applying a voltage so that the protective layer 10 becomes an anode, the oxidation rate of the protective layer can be significantly increased compared to room temperature.

  As a result, oxidation proceeds and a thick oxide layer 11 is formed in the region 11a (first position) at 200 ° C. or higher, and oxidation does not proceed in the region 11b (second position) where heat is not directly applied, compared to the region 11a. A thin oxide layer 11 is formed (FIG. 3 (f) oxidation reaction). If the oxidation rate of tantalum, which is the material of the protective layer 10 at room temperature, is 1, it is about 20 times when the temperature is 400 ° C., and the film thickness is about 2.5 times when it becomes tantalum oxide. I know it.

  Using a substrate provided with a tantalum protective layer 10 of about 300 nm by sputtering, heating of the energy generating element 12 and application of voltage to the terminal 23 and the terminal 24 are performed for a certain time. went. In the region 11a, when the protective layer 10 made of tantalum remains about 100 nm and the oxide layer 11 is formed about 500 nm, in the region 11b, the protective layer 10 remains about 290 nm and the oxide layer 11 is formed about 25 nm. .

  Since the energy generating element 12 is a region corresponding to the stepped recesses of the pair of electrodes 7, by heating with the energy generating element 12 and selectively providing the thick oxide layer 11 in the region 11 a, the pair of electrodes 7 can be reduced. Furthermore, by providing in this way, the flow resistance of the ink in the flow path 46 can be reduced, and the ink can be refilled at a high speed. Accordingly, it is possible to provide a liquid discharge head that can perform a recording operation at a high discharge frequency.

(Second embodiment)
In the first embodiment, after the flow path forming member 14 is formed, the flow path 46 is filled with a conductive liquid such as ink, and a voltage is applied to the protective layer 10 to cause an oxidation reaction, thereby forming the oxide layer 11. Provided. On the other hand, this embodiment is a manufacturing method in which the oxide layer 11 is provided on the surface of the energy generating element 12 before the flow path forming member 14 is provided.

  The steps up to the step of providing the protective layer 10 (FIGS. 3A to 3C) are the same as those in the first embodiment, and are therefore omitted.

  A material made of a resist material having photosensitivity is applied on a substrate 1 provided with a protective layer 10 as shown in FIG. 3C, and the energy generating element 12 is surrounded by using a photolithography technique. Thus, the member 60 is provided (FIG. 4A). FIG. 5 shows a schematic top view of the substrate 1 provided with the member 60 as shown in FIG. Here, a state in which one member 60 is provided for one energy generating element 12 is shown, but a plurality of energy generating elements 12 may be provided so as to be surrounded.

  Next, the region 22 surrounded by the member 60 is filled with the conductive liquid 22 so as to be in contact with the protective layer 10 (FIG. 4B). At this time, ink used for the recording operation may be used.

  Next, a terminal 23 is provided so as to be connected to the protective layer 10, and a terminal 24 is provided so as to be connected to the liquid 22. Next, the pair of electrodes 7 is energized using a pulse such that the temperature of the surface of the energy generating element 12 in contact with the liquid is 300 ° C. or higher and 400 ° C. or lower.

  While the portion of the energy generating element 12 facing the liquid 22 is heated, a potential difference of about 20 V is applied to the terminal 23 and the terminal 24 so that the protective layer 10 becomes an anode. By heating the protective layer 10 to 300 ° C. or higher and applying a voltage so that the protective layer 10 serves as an anode, the oxidation rate of the protective layer can be significantly increased compared to room temperature.

  As a result, in the region 11a where the temperature is 300 ° C. or higher and 400 ° C. or lower, oxidation proceeds and a thick oxide layer 11 is formed. In the region 11b where heat is not directly applied, oxidation hardly progresses and a thin oxide layer 11 is formed ( FIG. 4 (c) oxidation reaction).

  Using a substrate provided with a tantalum protective layer 10 of about 300 nm by sputtering, heating of the energy generating element 12 and application of voltage to the terminal 23 and the terminal 24 are performed for a certain time. went. In the region 11a, when the protective layer 10 made of tantalum remains about 100 nm and the oxide layer 11 is formed about 500 nm, in the region 11b, the protective layer 10 remains about 290 nm and the oxide layer 11 is formed about 25 nm. .

  Since the energy generating element 12 is a region corresponding to the stepped recesses of the pair of electrodes 7, by heating with the energy generating element 12 and selectively providing the thick oxide layer 11 in the region 11 a, the pair of electrodes 7 can be reduced.

  Next, the liquid 22 and the member 60 are removed, a soluble resin is formed on the surface of the liquid discharge head substrate 5 by using a spin coating method, and patterning is performed by using a photolithography technique to form the flow path 46. A mold material is formed on the portion (not shown). Furthermore, the flow path forming member 14 is formed by forming a cationic polymerization type epoxy resin on the mold material using a spin coating method, and then baking and curing using a hot plate. Thereafter, the flow path forming member 14 in a portion that becomes the discharge port 13 is removed by using a photolithography technique. Next, from the back surface of the surface of the substrate 1 on which the energy generating element 12 is provided, the silicon substrate 1 is etched using a tetramethylammonium hydroxide solution (TMAH solution) or the like to form a through-hole serving as the supply port 45. Form. Thereafter, the mold material is removed to complete the liquid discharge head (FIG. 2B).

  By providing as described above, it is possible to provide a liquid discharge head that can reduce the flow resistance of ink in the flow path 46 and can perform a recording operation at a high discharge frequency.

  In addition, by providing the step of oxidizing the protective layer 10 before the flow path forming member 14 is provided, the step on the surface of the energy generating element 12 in contact with the ink can be reduced in advance. Accordingly, it is possible to provide a highly reliable liquid discharge head that can form the flow paths and the shapes of the discharge ports without variations and can reduce variations in the discharge amount.

5 Liquid Discharge Head Substrate 6 Heating Resistance Layer 7 Pair of Electrodes 8 Insulating Layer 10 Protective Layer 11 Oxidation Layer 12 Energy Generating Element 13 Discharge Port 14 Channel Forming Member 22 Liquid 41 Liquid Discharge Head 46 Channel

Claims (10)

A heating resistor layer made of a material that generates heat when energized, a pair of electrodes used for energization, covering the heating resistor layer and the pair of electrodes, and made of an insulating material An insulating layer, a protective layer made of a metal material that covers at least a region corresponding to the region between the pair of electrodes, on the insulating layer, and provided on the protective layer. An oxide layer, and a liquid discharge head substrate serving as an energy generating element in which the region generates energy for discharging liquid from the discharge port;
A flow path member comprising a flow path wall communicating with the discharge port;
A method of manufacturing a liquid discharge head having
The base having the heating resistance layer, the pair of electrodes, the insulating layer, and the protective layer, and the flow path forming the flow path by being provided so as to be in contact with the base with the wall inside. A step of preparing a member;
Supplying a liquid having conductivity to the flow path;
By energizing between the pair of electrodes, a portion of the protective layer corresponding to the energy generating element is heated, and in parallel with the heating, a potential difference is generated between the liquid in the flow path and the protective layer. To oxidize a part of the protective layer on the flow path side to form the oxide layer;
A method of manufacturing a liquid discharge head, comprising:   2. The method of manufacturing a liquid discharge head according to claim 1, wherein in the step of providing the oxide layer, a potential difference is applied so that the protective layer becomes an anode.   The surface of the prepared substrate is more convex in the second position corresponding to the pair of electrodes than in the first position corresponding between the pair of electrodes in the direction perpendicular to the surface. The method for manufacturing a liquid discharge head according to claim 1, wherein:   The method for manufacturing a liquid discharge head according to claim 1, wherein the protective layer is made of a material mainly containing tantalum. A heating resistor layer made of a material that generates heat when energized, a pair of electrodes used for energization, covering the heating resistor layer and the pair of electrodes, and made of an insulating material An insulating layer, a protective layer made of a metal material that covers at least a region corresponding to the region between the pair of electrodes, on the insulating layer, and provided on the protective layer. And a manufacturing method of a substrate for a liquid discharge head that serves as an energy generating element that generates energy for discharging liquid.
Preparing a base including the heating resistance layer, the pair of electrodes, the insulating layer, and the protective layer;
Supplying a conductive liquid on at least a portion of the protective layer corresponding to the energy generating element;
By energizing between the pair of electrodes, a portion of the protective layer corresponding to the energy generating element is heated, and in parallel with the heating, a potential difference is provided between the provided liquid and the protective layer. To oxidize a part of the protective layer on the flow path side to form the oxide layer;
A method for manufacturing a substrate for a liquid discharge head, comprising:   6. The method of manufacturing a substrate for a liquid discharge head according to claim 5, wherein in the step of providing the oxide layer, a potential difference is applied so that the protective layer becomes an anode.   The surface of the prepared substrate is more convex in the second position corresponding to the pair of electrodes than in the first position corresponding between the pair of electrodes in the direction perpendicular to the surface. A method for manufacturing a substrate for a liquid discharge head according to claim 5 or 6.   The method for manufacturing a substrate for a liquid discharge head according to claim 5, wherein the protective layer is made of a material mainly composed of tantalum. A heating resistance layer made of a material that generates heat when energized;
A pair of electrodes provided in contact with the heating resistance layer and used for energization;
An insulating layer made of an insulating material, covering the heating resistance layer and the pair of electrodes;
A protective layer made of a metal material on the insulating layer and covering at least a region corresponding to the gap between the pair of electrodes on the heating resistor layer;
An oxide layer provided on the protective layer;
With
The region becomes an energy generating element that generates energy used for discharging the liquid,
The liquid discharge head substrate, wherein a thickness of a portion of the oxide layer corresponding to the energy generating element is larger than a thickness of a portion of the oxide layer corresponding to the pair of electrodes. A substrate for a liquid ejection head according to claim 9,
A flow path member comprising a flow path wall communicating with a discharge port for discharging a liquid, and forming the flow path by contacting the liquid discharge head substrate with the wall inside.
A liquid discharge head comprising:

Images