JP2018144385A - Method for manufacturing liquid discharge head - Google Patents

Abstract

It is difficult to uniformly form a material layer of an etching mask on the surface of a nozzle plate that has been subjected to water repellent treatment, and an abnormality may occur in the discharge port shape due to variations in the thickness of the etching mask. In a method of manufacturing a liquid discharge head having a nozzle plate having a discharge port for discharging droplets, a water repellent layer containing a photocatalyst is formed on the surface of a nozzle plate material for forming the discharge port. A step of irradiating the water repellent layer with a first light to change the layer to a hydrophilic layer, a step of forming an etching mask for discharge on the hydrophilic layer, and an etching port by etching using the etching mask as a mask. A step of removing the etching mask, and a step of irradiating the hydrophilic layer with a second light to return it to the water repellent layer. [Selection] Figure 3

Description

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

  The prior art of a liquid discharge head subjected to water repellent treatment is disclosed in Patent Document 1. According to this, after forming the organic film which does not contain a fluorine group on the surface of the base material (nozzle plate) in which the hole is formed and the inner wall surface of the hole, the protective member is formed on the surface. At this time, since the organic film contains no fluorine, the organic film and the protective member are in close contact with each other without any gap. Thereafter, the organic film on the inner wall of the hole is removed, the protective member is further removed, and then the organic film on the surface of the substrate is fluorinated. As a result, when removing the organic film on the inner wall portion of the hole, only the substrate surface can be subjected to water repellent treatment without causing damage to the organic film on the substrate surface.

Patent 5426200

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

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

  SUMMARY OF THE INVENTION An object of the present invention is to provide a manufacturing method that suppresses variations in the thickness of an etching mask layer formed on the surface of a water-repellent nozzle plate in a liquid discharge head and reduces abnormalities of the discharge port shape.

  In the method for manufacturing a liquid discharge head of the present invention, the following means are used. That is, in a method of manufacturing a liquid discharge head including 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 Irradiating the water repellent layer with a first light to change it to a hydrophilic layer, forming a discharge port etching mask on the hydrophilic layer, and using the etching mask as a mask to discharge by etching. A method of manufacturing a liquid discharge head, comprising: a step of forming an outlet; a step of removing the etching mask; and a step of returning the hydrophilic layer to a water repellent layer by irradiating a second light.

  According to the above manufacturing method, the surface state can be easily changed by light irradiation by including the photocatalyst in the water repellent layer. As a result, it becomes hydrophilic during the formation of the etching mask layer, suppresses variations in film thickness, can be returned to water repellency after removal of the etching mask layer, and the process is simplified.

It is a typical perspective view of the liquid discharge head manufactured by this invention. It is a typical sectional view of a liquid discharge head manufactured by the present invention. It is a typical sectional view of a manufacturing process of a liquid discharge head concerning one embodiment of the present invention. It is a typical sectional view of a manufacturing process of a liquid discharge head concerning other embodiments of the present invention.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, details of the present invention will be described in detail with reference to the drawings while describing embodiments. However, the following embodiments are not intended to limit the scope of the present invention, but are provided to fully explain the present invention to those having ordinary knowledge in the art.

  FIG. 1 is a schematic perspective view of a liquid discharge head manufactured according to the present invention. FIG. 2 is a schematic cross-sectional view showing the configuration of the liquid discharge head when the X-X ′ portion of FIG. 1 is viewed from the cross-sectional direction. FIG. 3 is a schematic view showing one embodiment of a method of manufacturing a liquid discharge head as viewed from the cross-sectional direction of the X-X ′ portion of FIG. 1 in the order of steps. FIG. 4 is a schematic view showing another embodiment of the method of manufacturing the liquid discharge head in the order of steps.

Hereinafter, the configuration of the liquid ejection 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 disposed 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 the liquid. And a nozzle plate 4 having discharge ports 7. Further, a liquid foaming chamber 8 that communicates with the ejection port 7 is provided facing the substrate surface on which the liquid ejection energy generating element is formed, and a liquid supply port 9 that supplies liquid to the liquid foaming chamber 8 is further provided. The liquid supply port 9 penetrates the substrate 1 and supplies 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 with respect to the liquid around the discharge port, the size of the droplet, the discharge direction, High-quality printing can be performed by stabilizing the discharge speed. In the present invention, the nozzle plate before forming the discharge port is referred to as a “nozzle plate material” and is 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. The photocatalyst may further contain a metal element. Preferably, at least one of chromium and vanadium can be used as the metal element. By adding these metal elements, the time required for switching between the water repellent / hydrophilic state can be shortened. The addition amount of the metal element is not particularly limited as long as it exhibits a predetermined water repellency / hydrophilicity, but it is preferably 10% by mass or less from the viewpoint of developing hydrophilicity.

  The water repellent layer 5 can switch the water repellent / hydrophilic state with the wavelength of the irradiation light as required. The water repellent layer 5 has a water repellency with a pure water contact angle of 90 ° or more, but when irradiated with the first light, the water repellent layer 5 becomes a hydrophilic layer 5a with a contact angle of 60 ° or less. For this reason, when forming the etching mask for discharge ports, the etching mask material can be formed without being repelled. That is, since variations in film thickness can be suppressed, abnormalities in the discharge port shape can be reduced. Furthermore, since the hydrophilic layer 5a returns to the water-repellent layer 5 having a pure water contact angle of 90 ° or more after the etching mask is removed, high-quality printing can be performed as described above.

Subsequently, the first embodiment of the production method of the present invention will be described in the order of steps with reference to FIG.
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 that can easily form a drive circuit or a wiring that connects the drive circuit and the liquid discharge energy generating element. The liquid discharge energy generating element 2 can be a heater type that generates heat through electricity through a resistor, and can be applied to any element that can convert electricity into foaming energy. In addition, a protective film (not shown) such as SiO, SiN, or tantalum can be provided on the substrate 1 in order to suppress corrosion due to the discharge liquid of the liquid discharge energy generating element 2 and improve electrical insulation. 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 embedded in the substrate 1 in FIG. 2 and the like is that the substrate 1 including such a protective layer is referred to.

  Next, in FIG. 3B, a mold material 3 that can be removed later is formed on the surface of the substrate 1 where the liquid discharge energy generating element 2 is formed, in a region that becomes a liquid foaming chamber. 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 a method for forming the mold material 3, an organic resin material can be used to form a film using a general coating technique such as spin coating. If the mold material itself has photosensitivity, it can be patterned by exposure and development. When the mold material is a metal material, it can be formed by physical vapor deposition (PVD) such as sputtering. The patterning of the metal material can be performed by forming a mask with a photoresist and patterning by reactive ion etching (RIE) using a gas corresponding to the selected metal material. When the metal material is, for example, aluminum, chlorine can be applied as an etching gas.

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

  Next, as shown in FIG. 3 (d), titanium oxide containing a metal element such as chromium is deposited by sputtering so as to cover the nozzle plate material 4, thereby forming the water repellent layer 5. In order to form a titanium oxide film to which a metal element is added by sputtering, 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 given. 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. 3E, the entire surface of the water repellent layer 5 is irradiated with the first light 10. As the first light, light having a peak wavelength of 450 nm or less (for example, ultraviolet light having a peak wavelength of 400 nm or less) is preferable. Thereby, the pure water contact angle of the water repellent layer 5 is lowered to become the hydrophilic layer 5a. If the contact angle of pure water of the hydrophilic layer 5a is 60 ° or less, it is possible to form a film without repelling a resist material serving as an etching mask, and to suppress film thickness variation. The pure water contact angle of the hydrophilic layer 5a is more preferably 30 ° or less.

  Next, as shown in FIG. 3F, a material layer (resist material 6) serving as an etching mask for forming discharge ports 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. More preferably, the resist material 6 is photosensitive. In the present invention, a layer of a resist material that serves as an etching mask is sometimes referred to as an etching mask layer.

  Next, as shown in FIG. 3G, the resist material 6 is patterned to form an etching mask 6M. A photosensitive resist material can be patterned by photolithography. As a result, there is no etching mask only on the upper part of the hydrophilic layer 5a forming the discharge port.

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

  Next, as shown in FIG. 3 (i), the liquid foaming chamber 8 is formed by removing the mold material 3. Isotropic etching can be applied as a 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 composed of 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, it can be removed by wet etching using a chemical that can dissolve the selected metal material. For example, when the metal material is aluminum, an etching solution mainly composed of a mixed solution of nitric acid and phosphoric acid is preferably used.

Next, as shown in FIG. 3J, the etching mask 6M is removed. The etching mask 6M can be removed using a chemical solution (stripping solution) suitable for the material to be used.
Next, as shown in FIG. 3K, the entire surface of the hydrophilic layer 5a is irradiated with light (for example, visible light) having a longer peak wavelength than the first light as the second light 11. Thereby, 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 550 nm to 780 nm, for example.

  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 is increased. Abnormality can be reduced. Moreover, since it only irradiates 2nd light also when returning from a hydrophilic layer to a water repellent layer, it can implement simply.

  Furthermore, Fig.4 (a)-(k) shows another embodiment (2nd embodiment) of the manufacturing method of this invention. 4 (a) to (d) and (h) to (k) are the same steps as FIGS. 3 (a) to (d) and (h) to (k). Therefore, features of the present embodiment will be described with reference to FIGS. 4 (e ′) and (g ′).

  As shown in FIG. 4 (e ′), the first light is irradiated to a portion other than the discharge port of the water repellent layer 5 using a photomask 12. Thereby, the water-repellent layer 5 remains just above the discharge port formation scheduled portion, and the others become the hydrophilic layer 5a.

  Next, as shown in FIG. 4G ', a resist material 6 for forming discharge ports is applied to the entire surface. The application method is selected from methods of applying a liquid substance such as spin coating. Since the water repellent layer 5 repels the resist material, the resist material is not formed directly above the portion where the ejection port is to be formed, and is patterned as an etching mask 6M. According to the manufacturing method of the second embodiment described above, in addition to the effects of the first embodiment, the etching mask patterning step is not required, and the steps are further simplified. In addition, the choice of resist material is widened.

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

Example 1
The manufacturing method of a present Example is demonstrated using Fig.3 (a)-(k).
First, as shown in FIG. 3A, the liquid discharge energy generating element 2 and wiring for driving it (not shown) on one side of a silicon single crystal substrate having a substrate thickness of 725 μm and an ingot drawing orientation of <100> A liquid discharge head substrate 1 on which was formed was prepared.

Next, in FIG. 3B, a mold material 3 that can be removed later was formed in a region corresponding to each liquid discharge energy generating element 2 to be a liquid foaming chamber. Aluminum was used as the mold material. Aluminum was formed into a film by physical vapor deposition (PVD: Physical Vapor Deposition). The film thickness was 5 μm. The patterning of aluminum was performed by a photolithography method. First, a positive resist (trade name: OFPR, manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied by spin coating, followed by exposure with an exposure amount of 1 J / cm ² , and a developer (trade name: NMD-3 Tokyo Ohka Kogyo Co., Ltd.). The product was developed for 3 minutes to form a mold material etching mask. Next, using the mold material etching mask, 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 to 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. 3E, the entire surface of the water repellent layer 5 was irradiated with ultraviolet rays (first light 10). The wavelength was 400 nm and the exposure amount 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. 3F, a resist material 6 for forming discharge ports was spin-coated on the entire surface. As the resist material 6, a positive resist (trade name: OFPR, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was used.

Next, as shown in FIG. 3 (g), the discharge port formation scheduled portion of the resist material 6 is exposed at an exposure amount of ² J / cm ² and developed for 3 minutes to form an etching mask 6M having a thickness of 5 μm. did.

  Next, as shown in FIG. 3 (h), a discharge port 7 that penetrates the hydrophilic layer 5a and the nozzle plate material 4 and exposes the mold material 3 was formed. The forming method was performed by RIE mainly using fluorine using the etching mask 6M as a mask. After the etching, the etching mask 6M was not removed. Next, in order to form the liquid supply port 9 shown in FIG. 1, an etching protective film for protecting the nozzle plate was formed on the etching mask 6M. A resist (trade name: OBC manufactured by Tokyo Ohka Kogyo Co., Ltd.) resistant to an alkaline solvent was used for the etching protective film. Thereafter, silicon was etched from the side of the substrate 1 where the nozzle plate was not formed with an alkali solvent (tetramethylammonium hydride solution, manufactured by Tokyo Ohka Kogyo Co., Ltd.). Further, the protective layer and the like of the substrate 1 on the nozzle plate side were etched to form a through hole penetrating the substrate 1. Thereby, the liquid supply port for supplying a liquid to the liquid foaming chamber 8 was formed (not shown). Further, the etching protective film was removed. The etching protective film may be removed after the next liquid foaming chamber is formed.

  Next, as shown in FIG. 3 (i), the mold material 3 was removed to form a liquid foaming 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. 3J, the etching mask 6M was removed.
Finally, as shown in FIG. 3 (k), the entire surface of the hydrophilic layer 5a was irradiated with the second light 11. The second light was visible light having a peak wavelength of 600 nm, and the exposure amount was 1 mW / cm ² . Thereby, the hydrophilic layer 5a returned to the water repellent layer 5 having a pure water contact angle of 110 °.

Example 2
The manufacturing method of the liquid ejection head according to the second embodiment will be described in more detail with reference to the process charts shown in FIGS. 4 (a) to (d) and (h) to (k) are the same as FIGS. 3 (a) to (d) and (h) to (k) of the first embodiment. Therefore, the manufacturing method of this embodiment will be described with reference to FIGS. 4 (e ′) and (g ′).

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

  The liquid discharge head according to the present invention 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 an apparatus equipped with this liquid discharge head, it is possible to perform recording on various recording media such as paper, thread, fiber, leather, metal, plastic, glass, wood, and ceramic. Further, it can be applied as a head for ejecting a liquid for biochip manufacturing or electronic circuit printing. Among these, the liquid discharge head according to the present invention is suitable as an ink jet head using water-based ink or the like.

1 Liquid discharge head substrate (substrate)
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 foaming chamber 9 Liquid supply port 10 First light 11 Second light 12 Photomask

Claims (9)

In a method for manufacturing a liquid discharge head including a nozzle plate having a discharge port for discharging droplets,
Forming a water repellent layer containing a photocatalyst on the surface of the nozzle plate material for forming the discharge port;
Irradiating the water repellent layer with a first light to change to a hydrophilic layer;
Forming an etching mask for the discharge port on the hydrophilic layer;
Using the etching mask as a mask, forming a discharge port by etching;
Removing the etching mask;
And a step of returning the hydrophilic layer to the water repellent layer by irradiating the hydrophilic layer with second light.   2. The etching mask is formed by patterning after forming the material layer of the etching mask by irradiating the entire surface of the water repellent layer with a first light to change to a hydrophilic layer. Manufacturing method of the liquid discharge head.   Irradiating first light to a portion other than the discharge port formation scheduled portion of the water repellent layer to change to a hydrophilic layer, and forming an etching mask by forming a material layer of the etching mask on the hydrophilic layer. The method of manufacturing a liquid discharge head according to claim 1.   The method of manufacturing a liquid discharge head according to claim 1, wherein the peak wavelength of the first light is 450 nm or less.   5. The method of manufacturing a liquid ejection head according to claim 1, wherein a peak wavelength of the second light is longer than a peak wavelength of the first light.   6. The method of manufacturing a liquid discharge head according to claim 1, wherein the material layer of the etching mask is formed by a coating method.   The method of manufacturing a liquid discharge head according to claim 1, wherein the photocatalyst includes titanium oxide.   The method of manufacturing a liquid discharge head according to claim 7, wherein the photocatalyst further contains a metal element.   The method of manufacturing a liquid discharge head according to claim 8, wherein the metal element is at least one of chromium and vanadium.

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