METHOD OF MANUFACTURING INKJET PRINTHEAD USING CROSSLINKED POLYMER
Provided is a method of manufacturing an inkjet printhead. The method includes: preparing a substrate having thereon a heater for heating ink and an electrode for supplying current to the heater; applying a negative photoresist composition to the substrate having thereon the heater and the electrode and patterning the same to form a passage forming layer that surrounds an ink passage; patterning the substrate having thereon the passage forming layer by photolithography at least twice to form a sacrificial layer having a planarized upper surface in a space surrounded by the passage forming layer; applying the negative photoresist composition to the passage forming layer and the sacrificial layer and patterning the same to form a nozzle layer having a nozzle; etching the substrate from the rear surface thereof to be perforated to form an ink supply hole; and removing the sacrificial layer, wherein the negative photoresist composition includes a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone. The sacrificial layer may be planarized using a chemical mechanical polishing process. Therefore, an upper surface of the sacrificial layer can be planarized, and thus, it is possible to easily control a shape and dimension of an ink passage, thereby improving uniformity of the ink passage.
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The present application is a continuation-in-part application of co-pending U.S. patent application Ser. No. 11/415,198, entitled, “METHOD OF MANUFACTURING INKJET PRINTHEAD USING CROSSLINKED POLYMER”, which was filed on May 2, 2006 and claims priority under 35 U.S.C. §119(a) from Korean Patent Application No. 2005-39712, filed on May 12, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present general inventive concept relates to a method of manufacturing an inkjet printhead, and more particularly, to a method of manufacturing an inkjet resist composition printhead by photolithography using a crosslinked polymer.
2. Description of the Related Art
In general, inkjet printheads are devices for printing a predetermined color image by ejecting small droplets of printing ink at a desired position on a recording sheet. Ink ejection mechanisms of an inkjet printer are generally categorized into two different types: a thermally driven type (bubble-jet type), in which a heat source is employed to form bubbles in ink thereby causing an ink droplet to be ejected, and an piezoelectrically driven type, in which an ink droplet is ejected by a change in ink volume due to deformation of a piezoelectric element.
A typical structure of a conventional thermally-driven inkjet printhead is illustrated in
The ink ejection mechanism of the conventional thermally-driven inkjet printhead having the above-described configuration will now be described. Ink is supplied from an ink reservoir (not illustrated) to the ink chamber 53 through the ink supply hole 51 and the restrictor 52. The ink filling the ink chamber 53 is heated by a heater 41 consisting of resistive heating elements. The ink boils to form bubbles and the bubbles expand so that the ink in the ink chamber 53 is ejected by a bubble pressure. Accordingly, the ink in the ink chamber 53 is ejected outside the ink chamber 53 through the nozzle 54 in the form of ink droplets.
The conventional thermally-driven inkjet printhead having the above-described configuration can be monolithically manufactured by photolithography, and the photolithography manufacturing process thereof is illustrated in
Referring to
As illustrated in
As illustrated in
As illustrated in
Subsequently, as illustrated in
Referring back to
As described above, according to the conventional manufacturing method of an inkjet printhead, since the shape and dimension of an ink passage are not easily controlled, it is difficult to attain uniformity of the ink passage, and an ink ejection performance of the printhead may deteriorate. Further, since the passage forming layer 20 and the nozzle layer 30 are not suitably adhered to each other, the durability of the inkjet printhead is lowered.
Referring back to
The present general inventive concept provides a method of manufacturing an inkjet printhead that can easily control a shape and dimension of an ink passage by planarizing a top surface of a sacrificial layer, thereby improving uniformity of the ink passage, and an inkjet printhead manufactured by the method.
The present general inventive concept provides an inkjet printhead having a planarized surface of a sacrificial layer to control a shape and a dimension of an ink passage, thereby improving uniformity of the ink passage and preventing deformation of a nozzle layer due to gas generated in the sacrificial layer.
Additional aspects and advantages of the present general inventive concept will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the general inventive concept.
The foregoing and/or other aspects and utilities of the present general inventive concept may be achieved by providing a method of manufacturing an inkjet printhead, the method including: preparing a substrate having thereon a heater for heating ink and an electrode for supplying current to the heater; applying a negative photoresist composition to the substrate having thereon the heater and the electrode and patterning the negative photoresist composition to form a passage forming layer that surrounds an ink passage; patterning the substrate having thereon the passage forming layer by photolithography at least twice to form a sacrificial layer having a planarized upper surface in a space surrounded by the passage forming layer; applying the negative photoresist composition to the passage forming layer and the sacrificial layer and patterning the negative photoresist composition to form a nozzle layer having a nozzle; etching a rear surface of the substrate to form an ink supply hole; and removing the sacrificial layer, wherein the negative photoresist composition includes a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone.
The monomers in the prepolymer can all have an identical formula. The monomers in the prepolymer can all have different formulas. The monomers in the prepolymer can include a mixture of some of the monomers having an identical formula and others of the monomers having different formulas.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an inkjet printhead manufactured by the method.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing a method of manufacturing an inkjet printhead, the method including: applying a first negative photoresist composition to a substrate having thereon a heater and an electrode; patterning the first negative photoresist composition to form a passage forming layer that surrounds an ink passage; patterning the substrate having thereon the passage forming layer by photolithography at least twice to form a sacrificial layer having a planarized upper surface in a space surrounded by the passage forming layer; applying a second negative photoresist composition including a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone to the passage forming layer and the sacrificial layer; patterning the second negative photoresist composition to form a nozzle layer having a nozzle; and removing the sacrificial layer.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing a method of manufacturing an inkjet printhead, the method including: applying to a substrate a negative photoresist composition including a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone; exposing the negative photoresist composition applied to the substrate to ultraviolet light to form a first crosslinked polymer; developing the first crosslinked polymer; applying a positive photoresist composition to the substrate and the first crosslinked polymer; exposing the positive photoresist composition applied to the substrate and the first crosslinked polymer to ultraviolet light to form a first sacrificial layer; developing the first sacrificial layer; applying the positive photoresist composition to the substrate, the first crosslinked polymer, and the first sacrificial layer; exposing the positive photoresist composition applied to the substrate, the first crosslinked polymer, and the first sacrificial layer to ultraviolet light to form a second sacrificial layer having a planarized upper surface; and developing the second sacrificial layer.
The exposing of the negative photoresist composition applied to the substrate may include exposing the negative photoresist composition through a first photomask having a passage forming layer pattern to ultraviolet light to form the first crosslinked polymer. The exposing of the positive photoresist composition applied to the substrate and the first crosslinked polymer may include exposing the positive photoresist composition through a second photomask having an ink chamber pattern to ultraviolet light to form the first sacrificial layer. The exposing of the positive photoresist composition applied to the substrate, the first crosslinked polymer, and the first sacrificial layer may include exposing the positive photoresist composition through a second photomask having an ink chamber pattern to ultraviolet light to form the second sacrificial layer having a planarized upper surface.
The method may further include repeatedly blank exposing the second sacrificial layer having the planarized upper surface until a height of the second sacrificial layer is substantially equal to a height of the passage forming layer, developing the blank exposed second sacrificial layer, applying a negative photoresist composition including a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone to the substrate and the second sacrificial layer, exposing the negative photoresist composition applied to the substrate and the second sacrificial layer to ultraviolet light to form a second crosslinked polymer, and developing the second crosslinked polymer. The exposing of the negative photoresist composition applied to the substrate and the second sacrificial layer may include exposing the negative photoresist composition through a third photomask having a nozzle layer pattern to ultraviolet light to form the second crosslinked polymer. The method may further include applying a negative photoresist composition including a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic backbone to the substrate and the second sacrificial layer, exposing the negative photoresist composition applied to the substrate and the second sacrificial layer to ultraviolet light to form a second crosslinked polymer, and developing the second crosslinked polymer, in which the positive photoresist composition is an imide-based positive photoresist composition. The exposing of the negative photoresist composition applied to the substrate and the second sacrificial layer can include exposing the negative photoresist composition through a third photomask having a nozzle layer pattern to ultraviolet light to form the second crosslinked polymer.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing a photolithography method, including applying a first negative photoresist composition to a substrate having a heater and an electrode formed thereon, patterning the negative photoresist composition to form a passage forming layer, applying a positive photoresist composition to a location on the substrate surrounded by the passage forming layer, patterning the positive photoresist composition to form a sacrificial layer, applying a second negative photoresist composition including a prepolymer that a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone to the passage forming layer and the sacrificial layer, patterning the second negative photoresist composition to form a nozzle having a nozzle layer, and removing the sacrificial layer. The first negative photoresist composition may include a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone. The positive photoresist composition can be an imide-based positive photoresist composition.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an inkjet printhead including: a substrate having thereon at least one heater and at least one electrode and having an ink passage; a passage forming layer, disposed on the substrate, defining an ink chamber; and a nozzle layer, disposed on the passage forming layer, including a crosslinked product of a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone.
A height of the ink chamber can be substantially equal to a height of the passage forming layer. A height of the ink chamber can be greater than a height of the passage forming layer. The passage forming layer can include a crosslinked product of a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an inkjet printhead intermediate useable to make an inkjet printhead, including: a substrate having thereon at least one heater and at least one electrode and having an ink passage; and a first crosslinked polymer resist layer, disposed on the substrate, including a crosslinked product of a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenol novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an inkjet printhead intermediate useable to make an inkjet printhead, including: a substrate having thereon at least one heater and at least one electrode and having an ink passage; a passage forming layer, disposed on the substrate, defining an ink chamber; and a sacrificial layer having a planarized upper surface disposed on a portion of the substrate substantially surrounded by the passage forming layer.
The passage forming layer can include a crosslinked product of a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone. The sacrificial layer can include an imide-based positive photoresist composition. A height of the sacrificial layer can be substantially equal to a height of the passage forming layer. A height of the sacrificial layer can be greater than a height of the passage forming layer. The inkjet printhead intermediate can further include a polymer layer, disposed on the sacrificial layer, including a crosslinked product of a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an inkjet printhead including: a substrate having a passage, at least one heater formed on a first portion of the substrate, at least one electrode formed on a second portion of the substrate, a passage forming layer formed on a third portion of the substrate, and a nozzle layer formed on the passage forming layer, having a planarized surface facing the substrate. The surface of the nozzle layer and a surface of the passage forming layer can form an angle without a cavity on at least one of the surfaces of the nozzle layer and the passage forming layer.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing a method of manufacturing an inkjet printhead, including forming a substrate having a passage, forming at least one heater on a first portion of the substrate, forming at least one electrode on a second portion of the substrate, forming a passage forming layer on a third portion of the substrate, and forming a nozzle layer having a planarized surface facing the substrate on the passage forming layer. The forming of the nozzle layer having the planarized surface facing the substrate on the passage forming layer can include forming an angle without a cavity between the surface of the nozzle layer and a surface of the passage forming layer.
The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing a method of manufacturing an inkjet printhead, the method including: preparing a substrate having thereon a heater for heating ink and an electrode for supplying current to the heater; coating a negative photoresist composition on the substrate having thereon the heater and the electrode and patterning the negative photoresist composition using a photolithography process to form a passage forming layer that defines an ink passage; forming a sacrificial layer on the substrate having thereon the passage forming layer so as to cover the passage forming layer; planarizing upper surfaces of the passage forming layer and the sacrificial layer using a polishing process; coating a negative photoresist composition on the passage forming layer and the sacrificial layer and patterning the negative photoresist composition using a photolithography process to form a nozzle layer having a nozzle; forming an ink feed hole in the substrate; and removing the sacrificial layer, wherein the negative photoresist composition includes a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone.
The polishing process may be a chemical mechanical polishing (CMP) process. The substrate may be a silicon wafer.
According to the present invention, an upper surface of a sacrificial layer can be planarized, and thus, it is possible to easily control the shape and dimension of an ink passage, thereby improving uniformity of the ink passage. Moreover, no gas is generated in the sacrificial layer, thereby avoiding deformation of a nozzle layer.
BRIEF DESCRIPTION OF THE DRAWINGSThese and/or other aspects and advantages of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
Korean Patent Application No. 2005-39712, filed on May 12, 2005, in the Korean Intellectual Property Office, and entitled: “METHOD OF MANUFACTURING INKJET PRINTHEAD USING CROSSLINKED POLYMER” is incorporated by reference herein in their entirety.
Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present general inventive concept by referring to the figures.
The present general inventive concept provides a method of manufacturing an inkjet printhead, the method including: preparing a substrate having thereon a heater for heating ink and an electrode for supplying current to the heater; applying a negative photoresist composition to the substrate having thereon the heater and the electrode and patterning the negative photoresist composition to form a passage forming layer that surrounds an ink passage; patterning the substrate having thereon the passage forming layer by photolithography at least twice to form a sacrificial layer having a planarized upper surface in a space surrounded by the passage forming layer; applying the negative photoresist composition to the passage forming layer and the sacrificial layer and patterning the negative photoresist composition to form a nozzle layer having a nozzle; etching a rear surface of the substrate to form an ink supply hole; and removing the sacrificial layer, wherein the negative photoresist composition includes a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group (hereinafter, referred to as simply “glycidyl ether functional group”) on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone.
In embodiments, the negative photoresist composition may include the prepolymer, a cationic photoinitiator, and a solvent.
The prepolymer of the negative photoresist composition may form a crosslinked polymer by exposing the prepolymer to an actinic radiation.
The prepolymer may be prepared from a backbone monomer unit selected from the group consisting of phenol, o-cresol, p-cresol, bisphenol-A, an alicyclic compound, and mixtures thereof.
The prepolymer may include at least one represented by Formulas 1-7 below:
In each of the above structural Formulas 1-7, m is an integer ranging from 1 to 20, and n is an integer ranging from 1 to 20. The prepolymer may also be addition products of 1-2-epoxy-4(2-oxiranyl)-cyclohexane of 2,2-bis(hydroxy methyl)-1-butanol (which are commercially available under the trade name of EHPH-3150).
The cationic photoinitiator can be, for example, a sulfonium salt or an iodonium salt.
The solvent may be at least one compound selected from the group consisting of -butyrolactone, propylene glycol methyl ether acetate (PGMEA), tetrahydrofuran (THF), methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and mixtures thereof.
According to an embodiment of the present general inventive concept, an inkjet printhead can be manufactured by a method including applying a first crosslinked polymer resist composition to a substrate having a heater and an electrode and patterning the first crosslinked polymer resist composition to form a passage forming layer that surrounds an ink passage, patterning the substrate having the passage forming layer by photolithography at least twice, forming a sacrificial layer having a planarized upper surface in a space surrounded by the passage forming layer, applying a second crosslinked polymer resist composition to the passage forming layer and the sacrificial layer and patterning the second crosslinked polymer resist composition to form a nozzle layer having a nozzle, and removing the sacrificial layer.
In embodiments, a step difference between a chamber layer of the inkjet printhead and the sacrificial layer is not greater than about 3 μm.
Monomers forming the prepolymer can all have an identical formula. The monomers forming the prepolymer can all have different formulas. The monomers forming the prepolymer can include a mixture of some of monomers having an identical formula and others of monomers having different formulae.
The present general inventive concept also provides a method of manufacturing an inkjet printhead, the method including: applying to a substrate a negative photoresist composition including a prepolymer that has a glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone; exposing the negative photoresist composition applied to the substrate to ultraviolet (UV) light to form a first crosslinked polymer; developing the first crosslinked polymer; applying a positive photoresist composition to the substrate and the first crosslinked polymer; exposing the positive photoresist composition applied to the substrate and the first crosslinked polymer to UV light to form a first sacrificial layer; developing the first sacrificial layer; applying the positive photoresist composition to the substrate, the first crosslinked polymer, the first sacrificial layer; exposing the positive photoresist composition applied to the substrate, the first crosslinked polymer, and the first sacrificial layer to UV light to form a second sacrificial layer having a planarized upper surface; and developing the second sacrificial layer.
The exposing of the negative photoresist composition applied to the substrate may include exposing the negative photoresist composition to UV light using a first photomask having a passage forming layer pattern to form the first crosslinked polymer.
The exposing of the positive photoresist composition applied to the substrate and the first crosslinked polymer may include exposing the positive photoresist composition to UV light using a second photomask having an ink chamber pattern to form the first sacrificial layer.
The exposing of the positive photoresist composition applied to the substrate, the first crosslinked polymer, and the first sacrificial layer may include exposing the positive photoresist composition to UV light using a second photomask having an ink chamber pattern to form the second sacrificial layer having a planarized upper surface.
The method may further include repeatedly blank exposing the second sacrificial layer having the planarized upper surface until a height of the second sacrificial layer is substantially equal to a height of the passage forming layer; developing the blank exposed second sacrificial layer; applying a negative photoresist composition including a prepolymer that has a glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone to the substrate and the second sacrificial layer; exposing the negative photoresist composition applied to the substrate and the second sacrificial layer to UV light to form a second crosslinked polymer; and developing the second crosslinked polymer.
The exposing of the negative photoresist composition applied to the substrate and the second sacrificial layer may include exposing the negative photoresist composition to UV light using a third photomask having a nozzle layer pattern to form the second crosslinked polymer.
The method may further include applying a negative photoresist composition including a prepolymer that has a glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone to the substrate and the second sacrificial layer; exposing the negative photoresist composition applied to the substrate and the second sacrificial layer to UV light to form a second crosslinked polymer; and developing the second crosslinked polymer, wherein the positive photoresist composition is an imide-based positive photoresist composition.
The exposing of the negative photoresist composition applied to the substrate and the second sacrificial layer can include exposing the negative photoresist composition to UV light using a third photomask having a nozzle layer pattern to form the second crosslinked polymer.
The present general inventive concept also provides an inkjet printhead including: a substrate having thereon at least one heater and at least one electrode and having an ink passage; a passage forming layer, disposed on the substrate, defining an ink chamber; and a nozzle layer, disposed on the passage forming layer, including a crosslinked product of a prepolymer that has a glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone.
A height of the ink chamber can be substantially equal to a height of the passage forming layer. A height of the ink chamber can be greater than a height of the passage forming layer. The passage forming layer can include a crosslinked product of a prepolymer that has a glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone.
The present general inventive concept also provides an inkjet printhead intermediate useable to make an inkjet printhead, including: a substrate having thereon at least one heater and at least one electrode and having an ink passage; and a first polymer layer, disposed on the substrate, including a crosslinked product of a prepolymer that has a glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone.
The present general inventive concept also provides an inkjet printhead intermediate useable to make an inkjet printhead, including: a substrate having thereon at least one heater and at least one electrode and having an ink passage; a passage forming layer, disposed on the substrate, defining an ink chamber; and a sacrificial layer having a planarized upper surface disposed on a portion of the substrate substantially surrounded by the passage forming layer.
The passage forming layer may include a crosslinked product of a prepolymer that has a glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone.
The sacrificial layer may include an imide-based positive photoresist composition. A height of the sacrificial layer may be substantially equal to a height of the passage forming layer. A height of the sacrificial layer may be greater than a height of the passage forming layer.
The inkjet printhead intermediate may further include a polymer layer, disposed on the sacrificial layer, including a crosslinked product of a prepolymer that has a glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone.
The present general inventive concept also provides a method of manufacturing an inkjet printhead, the method including: preparing a substrate having thereon a heater for heating ink and an electrode for supplying current to the heater; coating a negative photoresist composition on the substrate having thereon the heater and the electrode and patterning the negative photoresist composition using a photolithography process to form a passage forming layer that defines an ink passage; forming a sacrificial layer on the substrate having thereon the passage forming layer so as to cover the passage forming layer; planarizing upper surfaces of the passage forming layer and the sacrificial layer using a polishing process; coating the negative photoresist composition on the passage forming layer and the sacrificial layer and patterning the negative photoresist composition using a photolithography process to form a nozzle layer having a nozzle; forming an ink feed hole in the substrate; and removing the sacrificial layer, wherein the negative photoresist composition includes a prepolymer that has a glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone
The polishing process may be a chemical mechanical polishing (CMP) process. The substrate may be a silicon wafer.
The formation of the passage forming layer may include forming a first photoresist layer by coating the negative photoresist composition on the entire surface of the substrate; exposing the first photoresist layer using a first photomask having an ink passage pattern; and forming the passage forming layer by developing the first photoresist layer to remove an unexposed portion of the first photoresist layer.
The sacrificial layer may include a positive photoresist or a non-photosensitive soluble polymer. The positive photoresist may be an imide-based positive photoresist. The non-photosensitive soluble polymer may be at least one selected from the group consisting of a phenolic resin, a polyurethane resin, an epoxy resin, a polyimide resin, an acrylic resin, a polyamide resin, an urea resin, a melamine resin, and a silicone resin. Here, the term “soluble” refers to characteristics that can be dissolved in a solvent.
In the formation of the sacrificial layer, the sacrificial layer may be formed to be higher than the passage forming layer. Here, the sacrificial layer may be formed using a spin coating process.
In the planarization of the upper surfaces of the passage forming layer and the sacrificial layer, the upper surfaces of the passage forming layer and the sacrificial layer may be polished using a polishing process such as a chemical mechanical polishing process to reach a desired height of the ink passage.
The formation of the nozzle layer may include forming a second photoresist layer by coating the negative photoresist composition on the passage forming layer and the sacrificial layer; exposing the second photoresist layer using a second photomask having a nozzle pattern; and forming the nozzle layer having the nozzle by developing the second photoresist layer to remove an unexposed portion of the second photoresist layer.
The formation of the ink feed hole may include coating a photoresist on a rear surface of the substrate; forming an etch mask for forming the ink feed hole by patterning the photoresist; and etching a rear surface portion of the substrate exposed through the etch mask to form the ink feed hole. Here, the rear surface of the substrate may be etched by a dry etching process using plasma or a wet etching process using tetramethylammonium hydroxide (TMAH) or KOH as an etchant.
The negative photoresist composition may further include a cationic photoinitiator and a solvent, in addition to the prepolymer having the glycidyl ether functional group. The prepolymer having the glycidyl ether functional group may be prepared from a backbone monomer unit selected from the group consisting of phenol, o-cresol, p-cresol, bisphenol-A, an alicyclic-based compound, and mixtures thereof.
The prepolymer having the glycidyl ether functional group may include at least one represented by Formulas 1-7 above. The prepolymer may also be addition products of 1-2-epoxy-4(2-oxiranyl)-cyclohexane of 2,2-bis(hydroxy methyl)-1-butanol (which are commercially available under the trade name of EHPH-3150).
The prepolymer having the glycidyl ether functional group in the negative photoresist composition may be crosslinked by exposure to radiation of actinic ray, e.g., UV light.
The cationic photoinitiator may be a sulfonium salt or an iodonium salt.
The solvent may be at least one selected from the group consisting of -butyrolactone, propylene glycol methyl ether acetate (PGMEA), tetrahydrofuran (THF), methyl ethyl ketone, methy isobutyl ketone, cyclopentanone, and mixtures thereof.
According to the present invention, an upper surface of a sacrificial layer can be planarized, and thus, it is possible to easily control the shape and dimension of an ink passage, thereby improving uniformity of the ink passage. A crosslinked polymer constituting a chamber and a nozzle layer according to the present invention is prepared by crosslinking of a prepolymer that has a plurality of glycidyl ether functional groups and a phenolic novolak resin-based backbone, a bisphenol-A backbone, or an alicyclic-based backbone. Generally, the glycidyl ether functional groups can be disposed on hydrogen positions of phenolic hydroxy groups.
A difunctional epoxy resin having two glycidyl ether groups may be represented by Formula 7 below:
wherein m is an integer ranging from 1 to 25, preferably an integer of 1 to 20.
The difunctional epoxy resin having two glycidyl ether groups can form a film with a low crosslinking density.
The content of the difunctional epoxy resin may range from about 5 to about 50% by weight, preferably from about 10 to about 20% by weight, based on the total weight of the negative photoresist composition.
Examples of the difunctional epoxy resin having two glycidyl ether groups include, but are not limited to, EPON 828, EPON 1004, EPON 1001F, and EPON 1010 (which are commercially obtainable from Shell Chemicals), DER-332, DER-331, and DER-164 (which are commercially obtainable from Dow Chemical Company), and ERL-4201 and ERL-4289 (which are commercially obtainable from Union Carbide Corporation).
A multifunctional epoxy resin having more than two glycidyl ether groups will now be described.
The multifunctional epoxy resin having more than two glycidyl ether group can form a film with a high crosslinking density, increasing a resolution and thereby preventing swelling with respect to ink or a solvent. The content of the multifunctional epoxy resin may range from about 0.5 to about 20% by weight, preferably from about 1 to about 5% by weight, based on the total weight of the negative photoresist composition.
Examples of the multifunctional epoxy resin having more than two glycidyl ether groups include, but are not limited to, EPON SU-8 and EPON DPS-164 (which are commercially obtainable from Shell Chemicals), DEN-431 and DEN-439 (which are commercially obtainable from Dow Chemical Company), and EHPE-3150 (which is commercially obtainable from Daicel Chemical Industries, Ltd.).
Examples of a prepolymer that has a glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone include compounds represented by Formula 1 below:
The prepolymer that has a glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone may also use o-cresol or p-cresol instead of phenol when designing a backbone structure, as represented by Formulas 2 and 3 below:
Examples of a prepolymer that has a glycidyl ether functional group on monomer repeating units thereof and a bisphenol-A-based backbone include compounds represented by Formulas 5 and 6 below:
The number n of the monomer repeating units can range from 1 to about 20, preferably from 1 to about 10.
Examples of a prepolymer that has a glycidyl ether functional group on monomer repeating units thereof and an alicyclic-based backbone include addition products of 1-2-epoxy-4(2-oxiranyl)-cyclohexane of 2,2-bis(hydroxy methyl)1-butanol (which are commercially available under the trade name of EHPH-3150).
Photoinitiators are compounds that can generate ions or free radicals that initiate polymerization upon exposure to light. The content of the photoinitiator may range from about 1.0 to about 10% by weight, preferably from about 1.5 to 5% by weight, based on the total weight of the negative photoresist composition. If the content of the photoinitiator is less than 1.0% by weight, unreacted prepolymers may be left due to insufficient photopolymerization. On the other hand, if the content of the photoinitiator exceeds 10% by weight, energy higher than the energy value corresponding to a film thickness may be needed, and the wall profile of a pattern may be changed.
Examples of suitable photoinitiators include, but are not limited to, aromatic halominum salts and aromatic onium salts of Group VA or VI elements. For example, suitable photoinitiators include, but are not limited to, UVI-6974 (which is commercially obtainable from Union Carbide Corporation), SP-172 (which is commercially obtainable from Asahi denka, Co., Ltd.), and on the like.
Specific examples of the aromatic sulfonium salt include, but are not limited to, triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate (UVI-6974), phenylmethylbenzylsulfonium hexafluoroantimonate, phenylmethylbenzylsulfonium hexafluorophosphate, triphenylsulfonium hexafluorophosphate, methyl diphenylsulfonium tetrafluoroborate, and dimethyl phenylsulfonium hexafluorophsophate.
Specific examples of the aromatic iodonium salt include, but are not limited to, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluoroantimonate, and butylphenyl iodonium hexafluoroantimonate (SP-172).
Examples of suitable solvents include, but are not limited to, -butyrolactone, propylene glycol methyl ether acetate (PGMEA), tetrahydrofuran (THF), methyl ethyl ketone, methy isobutyl ketone, and mixtures thereof. A suitable content of the solvent can range from about 20 to about 90% by weight, preferably from about 45 to 75% by weight, based on the total weight of the negative photoresist composition.
As additional additives, photosensitizers, silane coupling agents, fillers, viscosity modifiers, and the like, can be used.
Sensitizers absorb light energy and facilitate the transfer of energy to another compound, which can then form radical or ionic initiators. Sensitizers frequently expand a useful energy wavelength range for photoexposure, and typically are aromatic light absorbing chromophores. Sensitizers can also lead to the formation of photoinitiators, which can be free radical or ionic forms.
When present, the sensitizer can be present in an amount of from about 0.1 to about 20% by weight based on the total weight of the negative photoresist composition.
As illustrated in
A silicon wafer is used as the substrate 110 in
The heater 141 can be formed by depositing a resistive heating element, such as tantalum-nitride or a tantalum-aluminum alloy, on the substrate 110 by sputtering or chemical vapor deposition (CVD) and patterning the deposited resistive heating element. The electrode 142 can be formed by depositing a metal having good conductivity, such as aluminum or an aluminum alloy, on the substrate 110 by sputtering and patterning the deposited metal. Although not illustrated, a passivation layer made of, for example, silicon oxide or silicon nitride, may be formed on the heater 141 and the electrode 142.
As illustrated in
As illustrated in
Then, when the first negative photoresist layer 121 is developed, the unexposed portion is removed to form a space, and the exposed and cured portion is left to form a passage forming layer 120, as illustrated in
In more detail, as illustrated in
As illustrated in
As illustrated in
As illustrated in
While the foregoing description has described that the sacrificial layer S can be formed by applying, exposing, and developing the first sacrificial layer 123 (see
Alternatively, the sacrificial layer S may be formed as described below. After applying, exposing, and developing the first sacrificial layer 123 (see
While the foregoing description has described that the positive photoresist is applied twice in order to form a sacrificial layer S having a planarized upper surface, the positive photoresist may be applied three or more times until the sacrificial layer S has a desired thickness. In this case, the number of times of performing exposure and development increases according to the number of times of applying positive photoresist.
Next, as illustrated in
Since the sacrificial layer S is formed to have substantially the same height as the passage forming layer 120, that is, the upper surface of the sacrificial layer S is planarized, it is possible to overcome the deformation or melting problem that occurs in the prior art, as discussed above. In particular, the deformation or melting of edges of the sacrificial layer S due to a reaction between the positive photoresist forming the sacrificial layer S and the material forming the second negative photoresist layer 131 that occurs in the prior art is avoided. Thus, the second negative photoresist layer 131 can be suitably adhered to the passage forming layer 120.
As illustrated in
As described above, exposing by using light having a relatively short wavelength shortens a transmission length of light, so that the sacrificial layer S disposed under the second negative photoresist layer 131 is not affected by exposure. Thus, nitrogen gas is not generated in the sacrificial layer S formed of the positive photoresist, thereby avoiding deformation of the nozzle layer 130 due to nitrogen gas.
As illustrated in
Next, as illustrated in
Finally, the sacrificial layer S can be removed using a solvent, thereby forming an ink chamber 153 and a restrictor 152 surrounded by the passage forming layer 120 in a space without the sacrificial layer S, as illustrated in
In such a manner, an inkjet printhead having the structure illustrated in
A sacrificial layer S is formed on a substrate 210 in substantially the same manner as illustrated in
When forming the sacrificial layer S, an imide-based positive photoresist can be used as the positive photoresist, and blank exposure and development therefore do not need to be performed. In other words, if the imide-based positive photoresist is used as the positive photoresist, the height of the sacrificial layer S does not need to be made substantially equal to that of the passage forming layer 220. The imide-based positive photoresist should be subjected to hard baking at approximately 140° C. after being developed. However, the imide-based positive photoresist is not affected by a solvent contained in the negative photoresist composition and does not result in the generation of nitrogen gas even upon exposure, which will be described later in more detail.
As illustrated in
As illustrated in
Next, as illustrated in
Since the imide-based positive photoresist forming the sacrificial layer S does not produce nitrogen gas even upon exposure, the deformation problem of the nozzle layer 230 due to nitrogen gas in the prior art does not occur. Thus, radiation of an actinic ray can be used to expose the second negative photoresist layer 231. Specifically, a UV beam over a broadband, including I-line radiation (353 nm), H-line radiation (405 nm), and G-line radiation (436 nm), or e-beam or X-ray having wavelengths shorter than the broadband radiations, may be used.
As illustrated in
Finally, the sacrificial layer S can be removed using a solvent, thereby forming an ink chamber 253 and a restrictor 252 surrounded by the passage forming layer 220 in a space obtained by the removal of the sacrificial layer S, as illustrated in
In such a manner, an inkjet printhead having the structure illustrated in
First, as illustrated in
The heater 341 can be formed by depositing a resistive heating element, such as tantalum-nitride or a tantalum-aluminum alloy, on the substrate 310 by sputtering or chemical vapor deposition (CVD) and patterning the deposited resistive heating element. The electrode 342 can be formed by depositing a metal having good conductivity, such as aluminum or an aluminum alloy, on the substrate 310 by sputtering and patterning the deposited metal. Although not illustrated, a passivation layer made of silicon oxide or silicon nitride may be formed on the heater 341 and the electrode 342.
Next, as illustrated in
Next, as illustrated in
Next, when the first negative photoresist layer 321 is developed to remove the unexposed portion, as illustrated in
Next, as illustrated in
Next, as illustrated in
Next, as illustrate in
Moreover, since the sacrificial layer S and the passage forming layer 320 are planarized to have the same heights, transformation or melting of an edge portion of the sacrificial layer S, which may be caused due to reaction between the material forming the second negative photoresist layer 331 and the material forming the sacrificial layer S, does not occur. Therefore, the second photoresist layer 331 can be closely adhered to the upper surface of the passage forming layer 320.
Next, as illustrated in
Next, as illustrated in
Next, as illustrated in
Finally, when the sacrificial layer S is removed using a solvent, an ink chamber 353 and a restrictor 352 surrounded by the passage forming layer 320 are formed, and the electrode 342 for supplying current to the heater 341 is exposed, as illustrated in
Preparation of Resist Composition 1
50 ml xylene (commercially available from Samchun Chemical Co.) and 10 ml SP-172 (commercially available from Asashi Denka Korea Chemical Co.) were added to a reactor. 90 g of an epoxy resin in the trade name of EHPH-3150 (commercially available from Daicel Chemical Industries. Ltd.) was then added to the reactor, and the resultant solution was stirred for 24 hours.
Preparation of Resist Composition 2
A commercial resist solution of EPON SU-8 was obtained from MicroChem. Corp., and was used as received. The commercial solution included -butyrolactone contained in an amount between 25 and 50% by weight, and a mixture of triarylsulfonium hexafluoroantimonate and p-thiophenoxyphenyldiphenysulfonium hexafluoroantimonate in propylene carbonate contained in an amount between 1 and 5% by weight.
Example 1 A tantalum nitride heater pattern and an electrode pattern made of AlSiCu alloy (the content of each of Si and Cu was 1% by weight or less) were each formed to a thickness of about 500 Å on a 6-inch silicon wafer using a sputtering process and a photolithography process commonly known in the art (see
Next, as illustrated in
An imide-based positive photoresist (trade name: PW-1270, manufactured by TORAY) was spin-coated on the entire surface of the wafer having thereon the passage forming layer pattern at a speed of 1000 rpm for 40 seconds, and baked at about 140° C. for 10 minutes to form a first sacrificial layer (see 123 of
The first sacrificial layer was exposed to UV light of I-line using a second photomask having predetermined pattern covering region between the passage forming layer pattern. At this time, the exposure dose was adjusted to 130 mJ/cm2. Then, the wafer was baked at 95° C. for three minutes, dipped in a developer (AZ300K, manufactured by Clariant) for one minute for development, and rinsed with isopropanol for 20 seconds. This completed first sacrificial layer (see 123 of
An imide-based positive photoresist was spin-coated on the entire surface of the wafer having thereon the passage forming layer pattern and the first sacrificial layer, baked, exposed to light, baked (post-exposure bake), developed, and rinsed in the same manner as in the formation of the first sacrificial layer to form second sacrificial layer (see 124 of
Next, the sacrificial layers were subjected to blank exposure to UV light of 1-line at an exposure dose of 260 mJ/cm2 such that the UV light reached a portion of the sacrificial layer that was the same level as the upper surface of the passage forming layer pattern. Then, the sacrificial layer was subjected to post-exposure bake, development, and rinsing to remove the exposed portion of the sacrificial layer so that the height of the sacrificial layer was equal to that of the passage forming layer pattern (see
A nozzle layer pattern was formed on the silicon wafer having thereon the passage forming layer pattern and the sacrificial layer using the resist composition 1 and a third photomask having a predetermined nozzle pattern under the same conditions as the formation of the passage forming layer pattern (see
As illustrated in
Finally, the wafer was dipped in a methyl lactate solvent for two hours to remove the sacrificial layer, thereby forming ink chamber and restrictor surrounded by the passage forming layer pattern in space obtained by the removal of the sacrificial layer, as illustrated in
This Example is intended to specifically describe a method of manufacturing an inkjet printhead, including forming a passage forming layer and a nozzle layer using a negative photoresist composition including a prepolymer as described above and planarizing a sacrificial layer using a CMP process.
A tantalum nitride heater pattern, an AlSiCu alloy electrode pattern, and a passage forming layer pattern were formed on a 6-inch silicon wafer in the same manner as in Example 1 (see
Next, as illustrated in
Next, upper surfaces of the passage forming layer pattern and the sacrificial layer were planarized using a CMP process, as illustrated in
Images of the passage forming layer pattern and the sacrificial layer after the CMP process are shown in
Next, formation of the nozzle layer, formation of the ink feed hole, and removal of the sacrificial layer were performed in the same manner as in Example 1 except that the resist composition 2 was used as a nozzle layer forming composition, instead of the resist composition 1 to thereby complete inkjet printhead having a structure as illustrated in
As described above, since a upper surface of a sacrificial layer is planarized in methods of manufacturing an inkjet printhead according to various embodiments of the present general inventive concept, it is possible to overcome the deformation or melting problem occurring in the prior art, that is, it is possible to avoid the deformation or melting of edges of the sacrificial layer due to a reaction between a positive photoresist composition and a negative resist composition. Thus, a shape and dimension of an ink passage can be easily controlled, thereby improving a uniformity of the ink passage, ultimately improving ink ejection performance of the inkjet printhead. Also, since a passage forming layer and a nozzle layer are suitably adhered to each other, durability of the printhead is enhanced. Further, since nitrogen gas is not generated in the sacrificial layer during photography to form a nozzle, deformation of the nozzle layer due to nitrogen gas can be avoided. Accordingly, uniformity of the ink passage can be further enhanced.
Although a few embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents.
Claims
1. A method of manufacturing an inkjet printhead, the method comprising:
- preparing a substrate having thereon a heater for heating ink and an electrode for supplying current to the heater;
- coating a negative photoresist composition on the substrate having thereon the heater and the electrode and patterning the negative photoresist composition using a photolithography process to form a passage forming layer that defines an ink passage;
- forming a sacrificial layer on the substrate having thereon the passage forming layer so as to cover the passage forming layer;
- planarizing upper surfaces of the passage forming layer and the sacrificial layer using a polishing process;
- coating a negative photoresist composition on the passage forming layer and the sacrificial layer and patterning the negative photoresist composition using a photolithography process to form a nozzle layer having a nozzle;
- forming an ink feed hole in the substrate; and
- removing the sacrificial layer,
- wherein the negative photoresist composition comprises a prepolymer that has a glycidyl ether functional group or a ring-opened glycidyl ether functional group on monomer repeating units thereof and a phenolic novolak resin-based backbone, a bisphenol A-based backbone, or an alicyclic-based backbone.
2. The method of claim 1, wherein the polishing process is a chemical mechanical polishing (CMP) process.
3. The method of claim 1, wherein the formation of the passage forming layer comprises:
- forming a first photoresist layer by coating the negative photoresist composition on the entire surface of the substrate;
- exposing the first photoresist layer using a first photomask having an ink passage pattern; and
- forming the passage forming layer by developing the first photoresist layer to remove an unexposed portion of the first photoresist layer.
4. The method of claim 1, wherein the sacrificial layer comprises a positive photoresist or a non-photosensitive soluble polymer.
5. The method of claim 4, wherein the positive photoresist is an imide-based positive photoresist.
6. The method of claim 4, wherein the non-photosensitive soluble polymer is at least one selected from the group consisting of a phenolic resin, a polyurethane resin, an epoxy resin, a polyimide resin, an acrylic resin, a polyamide resin, an urea resin, a melamine resin, and a silicone resin.
7. The method of claim 1, wherein in the formation of the sacrificial layer, the sacrificial layer is formed to be higher than the passage forming layer.
8. The method of claim 1, wherein in the formation of the sacrificial layer, the sacrificial layer is formed using a spin coating process.
9. The method of claim 1, wherein in the planariziation, the upper surfaces of the passage forming layer and the sacrificial layer are planarized by polishing the upper surfaces of the passage forming layer and the sacrificial layer using the polishing process to reach a desired height of the ink passage.
10. The method of claim 1, wherein the formation of the nozzle layer comprises:
- forming a second photoresist layer by coating the negative photoresist composition on the passage forming layer and the sacrificial layer;
- exposing the second photoresist layer using a second photomask having a nozzle pattern; and
- forming the nozzle layer having the nozzle by developing the second photoresist layer to remove an unexposed portion of the second photoresist layer.
11. The method of claim 1, wherein the formation of the ink feed hole comprises:
- coating a photoresist on a rear surface of the substrate;
- forming an etch mask for forming the ink feed hole by patterning the photoresist; and
- etching a rear surface portion of the substrate exposed through the etch mask to form the ink feed hole.
12. The method of claim 11, wherein the rear surface of the substrate is etched by a dry etching process using plasma.
13. The method of claim 11, wherein the rear surface of the substrate is etched by a wet etching process using tetramethylammonium hydroxide (TMAH) or KOH as an etchant.
14. The method of claim 1, wherein the negative photoresist composition further comprises a cationic photoinitiator and a solvent.
15. The method of claim 1, wherein the prepolymer is prepared from a backbone monomer unit selected from the group consisting of phenol, o-cresol, p-cresol, bisphenol-A, an alicyclic-based compound, and mixtures thereof.
16. The method of claim 1, wherein the prepolymer comprises at least one represented by Formulae 1 through 7 below:
- wherein m is an integer ranging from 1 to 25, and n is an integer ranging from 1 to 20.
17. The method of claim 1, wherein the prepolymer comprises addition products of 1-2-epoxy-4(2-oxiranyl)-cyclohexane of 2,2-bis(hydroxy methyl)-1-butanol.
18. The method of claim 1, wherein the prepolymer of the negative photoresist composition is crosslinked by exposure to radiation of actinic ray.
19. The method of claim 14, wherein the cationic photoinitiator is a sulfonium salt or an iodonium salt.
20. The method of claim 14, wherein the solvent is at least one selected from the group consisting of -butyrolactone, propylene glycol methyl ether acetate (PGMEA), tetrahydrofuran (THF), methyl ethyl ketone, methy isobutyl ketone, cyclopentanone, and mixtures thereof.
21. An inkjet printhead manufactured according to the method of any one of claims 1 through 20.
Type: Application
Filed: Jul 2, 2007
Publication Date: Nov 8, 2007
Applicant: Samsung Electronics Co., Ltd. (Suwon-si)
Inventors: Byung-ha PARK (Suwon-si), Young-ung Ha (Suwon-si), Sung-joon Park (Suwon-si), Jae-sik Min (Suwon-si), Kyong-il Kim (Seoul)
Application Number: 11/772,541
International Classification: B21D 53/78 (20060101);