JP6921564B2 - Manufacturing method of liquid discharge head - Google Patents

Description

The present invention relates to a method for manufacturing a liquid discharge head.

A prior art of a water-repellent liquid discharge head is disclosed in Patent Document 1. According to this, after forming an organic film containing no fluorine group on the surface of the base material (nozzle plate) on which the pores are formed and the inner wall surface of the pores, a protective member is formed on the surface. At this time, since the organic film does not contain fluorine, the organic film and the protective member are in close contact with each other without any gap. Then, the organic film on the inner wall of the pore is removed, the protective member is further removed, and then the organic film on the surface of the base material is fluorinated. As a result, when the organic film on the inner wall of the pore is removed, only the surface of the base material can be treated with water repellent without damaging the organic film on the surface of the base material.

Patent No. 5426200

The method described in Patent Document 1 requires a complicated step such as a step of removing the organic film in the pore (discharge port) and a fluorination treatment of the organic film. Therefore, in order to simplify the process, a method of forming a discharge port after water-repellent treatment on the surface of the nozzle plate can be considered.

However, it is difficult to uniformly form an etching mask layer for forming a discharge port on the surface of a water-repellent nozzle plate, and an abnormality occurs in the shape of the discharge port due to variations in the film thickness of the etching mask layer. There was a case.

An object of the present invention is to provide a manufacturing method for suppressing variations in the film thickness of an etching mask layer formed on the surface of a water-repellent nozzle plate in a liquid discharge head and reducing abnormalities in the shape of the discharge port.

In the method for manufacturing a liquid discharge head of the present invention, the following means are used. That is, in a method for manufacturing a liquid discharge head having a nozzle plate having a discharge port for discharging droplets, a step of forming a water-repellent layer containing a photocatalyst on the surface of a nozzle plate material for forming the discharge port. A step of irradiating a first light other than the planned discharge port forming portion of the water-repellent layer to change it into a hydrophilic layer, and a step of forming a material layer of an etching mask on the hydrophilic layer to form an etching mask. including the, the etching mask as a mask, forming a discharge port by etching, removing the etching mask, and a step of returning to the water-repellent layer by irradiating a second light to said hydrophilic layer A method for manufacturing a liquid discharge head.

According to the above manufacturing method, by including a photocatalyst in the water-repellent layer, the surface state can be easily changed by light irradiation. As a result, it becomes hydrophilic when the etching mask layer is formed, the film thickness variation is suppressed, and the water repellency can be restored after the etching mask layer is removed, which simplifies the process.

It is a schematic perspective view of the liquid discharge head manufactured by this invention. It is a schematic cross-sectional view of the liquid discharge head manufactured by this invention. It is a schematic cross-sectional view of the manufacturing process of the liquid discharge head which concerns on one Embodiment of this invention. It is a schematic cross-sectional view of the manufacturing process of the liquid discharge head which concerns on other embodiment of this invention.

Hereinafter, the details of the present invention will be described in detail with reference to the drawings while explaining the embodiments. However, the following embodiments do not limit the scope of the invention and are provided to fully explain the invention to those who have conventional knowledge in the art.

FIG. 1 is a schematic perspective view of a liquid discharge head manufactured by the present invention. FIG. 2 is a schematic cross-sectional view showing the configuration of the liquid discharge head when the XX'part of FIG. 1 is viewed from the cross-sectional direction. FIG. 3 is a schematic view showing one embodiment of a method for manufacturing a liquid discharge head when the XX'part of FIG. 1 is viewed from the cross-sectional direction in the order of steps. FIG. 4 is a schematic view showing another embodiment of the method for manufacturing a liquid discharge head in order of steps.

Hereinafter, the configuration of the liquid discharge head to which the present invention is applied will be described with reference to FIGS. 1 and 2.
First, as shown in FIGS. 1 and 2, the liquid discharge head is placed on a liquid discharge head substrate 1 (also simply referred to as a substrate) having a liquid discharge energy generating element 2 that generates energy for discharging liquid. A nozzle plate 4 having a discharge port 7 is provided. Further, a liquid foaming chamber 8 communicating with the discharge port 7 is provided facing the substrate surface on which the liquid discharge energy generating element is formed, and a liquid supply port 9 for supplying the liquid to the liquid foaming chamber 8 is provided. The liquid supply port 9 penetrates the substrate 1 and supplies the liquid from the surface opposite to the surface on which the nozzle plate 4 is formed. As shown in FIG. 2, a water-repellent layer 5 is provided on the outer surface of the nozzle plate 4, and by reducing the wettability of the periphery of the discharge port to the liquid, the size and discharge direction of the droplets can be determined. It is possible to stabilize the ejection speed and perform high-quality printing. In the present invention, the nozzle plate before forming the discharge port is referred to as a "nozzle plate material" and will be described with the same reference numerals.

The water-repellent layer 5 of the liquid discharge head according to the present invention contains a photocatalyst. The photocatalyst preferably contains titanium oxide. Further, the photocatalyst can further contain a metal element. As the metal element, at least one of chromium and vanadium can be preferably used. By adding these metal elements, the time required for switching the water-repellent / hydrophilic state can be shortened. The amount of the metal element added is not particularly limited as long as it exhibits predetermined water repellency / hydrophilicity, but it is preferably 10% by mass or less from the viewpoint of exhibiting hydrophilicity.

The water-repellent layer 5 can switch the water-repellent / hydrophilic state at the wavelength of the irradiation light, if required. The water-repellent layer 5 has a water repellency of pure water contact angle of 90 ° or more, but by irradiating with the first light, the water-repellent layer 5 becomes a hydrophilic layer 5a having a contact angle of 60 ° or less. Therefore, when forming the etching mask for the discharge port, the material of the etching mask can be formed without being repelled. That is, since the variation in film thickness can be suppressed, the abnormality in the shape of the discharge port can be reduced. Further, after the etching mask is removed, the hydrophilic layer 5a returns to the water-repellent layer 5 having a pure water contact angle of 90 ° or more by the second light, so that high-quality printing can be performed as described above.

Subsequently, with reference to FIG. 3, the first embodiment of the manufacturing method of the present invention will be described in order of steps.
First, as shown in FIG. 3A, a substrate 1 on which a plurality of liquid discharge energy generating elements 2 are formed is prepared. It is preferable that the substrate 1 is a silicon single crystal substrate in which a drive circuit or a wiring connecting the drive circuit and the liquid discharge energy generating element can be easily formed. As the liquid discharge energy generating element 2, a heater type that generates heat by passing electricity through a resistor can be applied, and any other element that can convert electricity into foaming energy can be applied. Further, in order to suppress corrosion of the liquid discharge energy generating element 2 due to the discharged liquid and improve the electrical insulation property, a protective film (not shown) such as SiO, SiN, or tantalum can be provided on the substrate 1. At this time, a protective layer may be formed over the entire surface of the substrate 1. The reason why the liquid discharge energy generating element 2 is displayed as being embedded in the substrate 1 in FIG. 2 and the like is because the substrate 1 includes such a protective layer.

Next, in FIG. 3B, a mold material 3 that can be removed later is formed in a region to be a liquid foam chamber on the liquid discharge energy generating element 2 forming surface side of the substrate 1. The mold material is selected in consideration of the surrounding materials, and is selected from organic resin materials and metal materials. If it is an organic resin material, polyimide can be preferably used in consideration of heat resistance, and if it is a metal material, aluminum or an aluminum alloy can be preferably used in consideration of removability. As for the method of forming the mold material 3, if it is an organic resin material, a film can be formed by using a general coating technique such as spin coating. If the mold material itself is photosensitive, it can be patterned by exposure development. When the mold material is a metal material, film formation can be performed by a physical vapor deposition method (PVD) such as sputtering. For patterning of a metal material, a mask is formed with a photoresist, and patterning is possible by reactive ion etching (RIE) or the like using a gas corresponding to the selected metal material. If the metal material is, for example, aluminum, chlorine can be applied to the etching gas.

Subsequently, as shown in FIG. 3C, the nozzle plate material 4 is formed so as to cover the substrate 1 and the mold material 3. Both an organic material and an inorganic material can be applied to the nozzle plate material, but the inorganic material is preferable in consideration of the formability and adhesion of the water-repellent layer according to the present invention. A compound consisting of silicon and any one or more of oxygen, nitrogen or carbon can be applied to the inorganic material. PECVD (Plasma Enhanced CVD) is preferably used as a method for forming an inorganic material.

Next, as shown in FIG. 3D, titanium oxide containing a metal element such as chromium is formed into a film by a sputtering method so as to cover the nozzle plate material 4, and the water repellent layer 5 is formed. In order to form a titanium oxide film to which a metal element is added by a sputtering method, a method using a titanium oxide target containing a metal element, a method of co-sputtering using a titanium oxide target and a metal target, and the like can be mentioned. The pure water contact angle of the water repellent layer 5 is 90 ° or more at this time. The contact angle is preferably 100 ° or more.

Next, as shown in FIG. 3 (e), the first light 10 is applied to the entire surface of the water repellent layer 5. As the first light, light having a peak wavelength of 450 nm or less (for example, ultraviolet rays having a peak wavelength of 400 nm or less) is preferable. As a result, the water-repellent layer 5 has a reduced pure water contact angle and becomes a hydrophilic layer 5a. When the pure water contact angle of the hydrophilic layer 5a is 60 ° or less, the film can be formed without repelling the resist material serving as the etching mask, and the film thickness variation can be suppressed. The pure water contact angle of the hydrophilic layer 5a is more preferably 30 ° or less.

Next, as shown in FIG. 3 (f), a material layer (resist material 6) serving as an etching mask for forming a discharge port is formed on the hydrophilic layer. The forming method is selected from a coating method such as spin coating. The resist material 6 is preferably liquid and can be applied. Further, more preferably, the resist material 6 is photosensitive. In the present invention, the layer of the resist material serving as the etching mask may be referred to as an etching mask layer.

Next, as shown in FIG. 3 (g), the resist material 6 is patterned to obtain an etching mask 6M. Photosensitive resist materials can be patterned by photolithography. As a result, only the upper part of the hydrophilic layer 5a forming the discharge port has no etching mask.

Next, as shown in FIG. 3 (h), the discharge port 7 is formed. As a forming method, an etching mask 6M is used as a mask, and for example, the hydrophilic layer 5a and the nozzle plate material 4 are continuously etched by RIE mainly composed of fluorine. Etching may be performed under conditions suitable for each material. As a result, a nozzle plate having a discharge port for discharging droplets is formed.

Next, as shown in FIG. 3 (i), the liquid foam chamber 8 is formed by removing the mold material 3. Isotropic etching can be applied to the method of removing the mold material 3. If the mold material is an organic resin material, it can be removed by chemical dry etching (CDE) mainly containing oxygen. At this time, a part of the etching mask 6M is also removed at the same time. If the mold material is a metal material, the selected metal material can be removed by wet etching using a soluble chemical solution. When the metal material is, for example, aluminum, an etching solution containing a mixed solution of nitric acid and phosphoric acid as a main component is preferably used.

Next, as shown in FIG. 3 (j), the etching mask 6M is removed. The etching mask 6M can be removed by using a chemical solution (stripping solution) suitable for the material to be used.
Next, as shown in FIG. 3 (k), the hydrophilic layer 5a is entirely irradiated with light having a peak wavelength longer than that of the first light (for example, visible light) as the second light 11. As a result, the hydrophilic layer 5a returns to the water-repellent layer 5 having a pure water contact angle of 90 ° or more. The peak wavelength of the second light 11 is preferably in the range of, for example, 550 nm or more and 780 nm or less.

According to the above manufacturing method, since the water-repellent layer irradiated with the first light changes to a hydrophilic layer, it becomes easy to form the etching mask layer uniformly, and the shape of the discharge port due to the variation in the thickness of the etching mask layer. Abnormalities can be reduced. Further, when returning from the hydrophilic layer to the water-repellent layer, it is only necessary to irradiate the second light, so that it can be easily carried out.

Further, FIGS. 4A to 4K show another embodiment (second embodiment) of the manufacturing method of the present invention. 4 (a) to (d) and (h) to (k) are the same steps as in FIGS. 3 (a) to (d) and (h) to (k). Therefore, the features of the present embodiment will be described with reference to FIGS. 4 (e') and 4 (g').

As shown in FIG. 4 (e'), the photomask 12 is used to irradiate a portion other than the discharge port of the water-repellent layer 5 with the first light. As a result, the water-repellent layer 5 remains directly above the planned discharge port formation portion, and the other layers become the hydrophilic layer 5a.

Next, as shown in FIG. 4 (g'), the resist material 6 for forming the discharge port is applied to the entire surface. The coating method is selected from a method of coating a liquid substance such as spin coating. Since the water-repellent layer 5 repels the resist material, the resist material is not formed immediately above the planned discharge port formation portion, and is in a patterned state as an etching mask 6M. According to the manufacturing method according to the second embodiment described above, in addition to the effect of the first embodiment, the patterning step of the etching mask becomes unnecessary, and the step is further simplified. In addition, the choice of resist material will be widened.

Hereinafter, a method for manufacturing a liquid discharge head using the present invention will be described in more detail by way of examples.

Example 1
The manufacturing method of this example will be described with reference to FIGS. 3A to 3K.
First, as shown in FIG. 3A, the liquid discharge energy generating element 2 and the wiring for driving the liquid discharge energy generating element 2 and the wiring for driving the liquid discharge energy generating element 2 on one side of a silicon single crystal substrate having a substrate thickness of 725 μm and an ingot withdrawal direction of <100> (not shown). The substrate 1 for the liquid discharge head in which the above was formed was prepared.

Next, in FIG. 3B, a mold material 3 that can be removed later was formed in a region that becomes a liquid foam chamber corresponding to each liquid discharge energy generating element 2. Aluminum was used as the mold material. Aluminum was deposited by a physical vapor deposition (PVD) method. The film thickness was 5 μm. The patterning of aluminum was performed by a photolithography method. First, a positive resist (trade name: OFPR Tokyo Ohka Kogyo Co., Ltd.) is applied by spin coating, and then exposed at an exposure amount of 1 J / cm ² , and a developing solution (trade name: NMD-3 Tokyo Ohka Kogyo Co., Ltd.) is applied. The product was developed for 3 minutes to form an etching mask for a mold material. Next, using an etching mask for a mold material, the mold material 3 was formed by RIE using chlorine as an etching gas.

Subsequently, as shown in FIG. 3C, SiN was formed by PECVD so as to cover the substrate 1 and the mold material 3, and the nozzle plate material 4 was formed.

Next, as shown in FIG. 3D, a water repellent layer 5 was formed on the upper surface of the nozzle plate material 4. The film thickness was 0.5 μm. At this time, a titanium oxide layer to which chromium was added was formed as the water repellent layer 5 by a sputtering method using titanium oxide in which 1% by mass of chromium was added to the sputtering target. The pure water contact angle of the water repellent layer 5 is 110 ° at this time.

Next, as shown in FIG. 3 (e), the water-repellent layer 5 was entirely irradiated with ultraviolet rays (first light 10). The wavelength was 400 nm and the exposure was 1 mW / cm ² . As a result, the water-repellent layer 5 became a hydrophilic layer 5a having a pure water contact angle of 10 °.

Next, as shown in FIG. 3 (f), a resist material 6 for forming a discharge port was spin-coated on the entire surface. A positive resist (trade name: OFPR Tokyo Ohka Kogyo Co., Ltd.) was used as the resist material 6.

Next, as shown in FIG. 3 (g), an etching mask 6M having a thickness of 5 μm is formed by exposing the planned discharge port formation portion of the resist material 6 at an exposure amount of ^{2 J / cm 2 and developing for 3 minutes.} bottom.

Next, as shown in FIG. 3H, a discharge port 7 was formed so as to penetrate the hydrophilic layer 5a and the nozzle plate material 4 to expose the mold material 3. The forming method was carried out by using an etching mask 6M as a mask and using a fluorine-based RIE. After etching, the etching mask 6M was left unremoved. Next, in order to form the liquid supply port 9 shown in FIG. 1, an etching protective film that protects the nozzle plate was formed on the etching mask 6M. A resist resistant to alkaline solvents (trade name: manufactured by OBC Tokyo Ohka Kogyo Co., Ltd.) was used as the etching protective film. Then, silicon etching was performed from the side where the nozzle plate of the substrate 1 was not formed with an alkaline solvent (tetramethylammonium hydride solution manufactured by Tokyo Ohka Kogyo Co., Ltd.). Further, the protective layer of the substrate 1 on the nozzle plate side was etched to form a through hole penetrating the substrate 1. As a result, a liquid supply port for supplying the liquid to the liquid foam chamber 8 was formed (not shown). Further, the etching protective film was removed. The etching protective film may be removed after the formation of the next liquid foam chamber.

Next, as shown in FIG. 3 (i), the mold material 3 was removed to form the liquid foam chamber 8. Since the mold material 3 is aluminum, it was dissolved and removed using a mixed solution of nitric acid and phosphoric acid.

Next, as shown in FIG. 3 (j), the etching mask 6M was removed.
Finally, as shown in FIG. 3 (k), the hydrophilic layer 5a was entirely irradiated with the second light 11. The second light was visible light with a peak wavelength of 600 nm, and the exposure amount was 1 mW / cm ² . As a result, the hydrophilic layer 5a returned to the water-repellent layer 5 having a pure water contact angle of 110 °.

Example 2
The method for manufacturing the liquid discharge head according to the second embodiment will be described in more detail with reference to the process diagrams shown in FIGS. 4A to 4K. 4 (a) to (d) and (h) to (k) are the same as those in FIGS. 3 (a) to 3 (d) and (h) to (k) of Example 1. Therefore, the production method of this example will be described with reference to FIGS. 4 (e') and 4 (g').

As shown in FIG. 4 (e'), the photomask 12 was used to irradiate the water-repellent layer 5 with ultraviolet rays 10 other than the planned discharge port formation portion. The wavelength was 400 nm and the exposure was 1 mW / cm ² . As a result, the planned discharge port formation portion remains the water-repellent layer 5 having a pure water contact angle of 110 °, and the rest becomes a hydrophilic layer 5a having a pure water contact angle of 10 °. Next, as shown in FIG. 4 (g'), a resist material to be an etching mask 6M was spin-coated on the entire surface. A positive resist (trade name: OFPR Tokyo Ohka Kogyo Co., Ltd.) was used as the resist material. Since the planned discharge port formation portion is a water-repellent layer having a pure water contact angle of 110 °, the resist material is not coated. That is, an etching mask 6M having a discharge port pattern could be formed. Compared with Example 1, the exposure / development step for forming the etching mask 6M became unnecessary, and the step was further simplified.

The liquid discharge head according to the present invention can be mounted on a device such as a printer, a copying machine, a facsimile having a communication system, a word processor having a printer unit, and an industrial recording device complexly combined with various processing devices. Then, by using the device equipped with this liquid discharge head, recording can be performed on various recorded objects such as paper, thread, fiber, leather, metal, plastic, glass, wood, and ceramic. It can also be applied as a head for discharging liquids for biochip manufacturing and electronic circuit printing. Among them, the liquid ejection head according to the present invention is suitable as an inkjet head or the like using water-based ink or the like.

1 Substrate for liquid discharge head (board)
2 Liquid discharge energy generating element 3 Mold material 4 Nozzle plate (material)
5 Water-repellent layer 5a Hydrophilic layer 6 Resist material 6M Etching mask 7 Discharge port 8 Liquid foam chamber 9 Liquid supply port 10 First light 11 Second light 12 Photomask

Claims (8)

In a method of manufacturing a liquid discharge head provided with a nozzle plate having a discharge port for discharging droplets.
A step of forming a water-repellent layer containing a photocatalyst on the surface of the nozzle plate material for forming the discharge port, and
A step of irradiating a first light other than the planned discharge port forming portion of the water-repellent layer to change it into a hydrophilic layer,
A step of forming a material layer of an etching mask on the hydrophilic layer to form an etching mask, and
A process of forming a discharge port by etching using the etching mask as a mask,
The step of removing the etching mask and
A method for manufacturing a liquid discharge head, which comprises a step of returning the hydrophilic layer to a water-repellent layer by irradiating the hydrophilic layer with a second light. The first aspect of the present invention, wherein the entire surface of the water-repellent layer is irradiated with the first light to change it into a hydrophilic layer to form a material layer of the etching mask, and then patterning is performed to form an etching mask. How to manufacture a liquid discharge head. The method for manufacturing a liquid discharge head according to claim 1 or 2, wherein the peak wavelength of the first light is 450 nm or less. The method for manufacturing a liquid discharge head according to any one of claims 1 to 3 , wherein the peak wavelength of the second light is longer than the peak wavelength of the first light. The method for manufacturing a liquid discharge head according to any one of claims 1 to 4 , wherein the material layer of the etching mask is formed by a coating method. The method for manufacturing a liquid discharge head according to any one of claims 1 to 5 , wherein the photocatalyst contains titanium oxide. The method for manufacturing a liquid discharge head according to claim 6 , wherein the photocatalyst further contains a metal element. The method for manufacturing a liquid discharge head according to claim 7 , wherein the metal element is at least one of chromium and vanadium.

Images