Nozzle plate, fluid ejection head, fluid ejection device, and method for modifying nozzle plate

Abstract

To provide an ejection head having features that inhibit flooding or that redirect flooding away from adjacent nozzles when the ejection head is operated in a nonstandard orientation.SOLUTION: A nozzle plate configured for a fluid ejection head, a fluid ejection head comprising the nozzle plate and a method for modifying a nozzle plate to reduce fluid flooding thereon are provided. The nozzle plate includes a plurality of nozzle holes attached to a flow feature layer on a semiconductor substrate, and includes a first hydrophobic region surrounding each of the nozzle holes, where the first hydrophobic region is configured to reduce flooding of the nozzle plate.SELECTED DRAWING: Figure 17

Description

[Technical field]

[0001] The present invention relates to an improved imageable nozzle member for fluid ejection devices, and to methods and structures for reducing fluid overflow into adjacent nozzle holes during fluid ejection. [Background technology]

[0002] Flooding, weeping, and drooling are common phenomena in fluid ejection devices, particularly those devices associated with fluid distribution where the meniscus of the ejected fluid breaks away from the confines of the nozzle hole and spreads across the face of the nozzle plate. For purposes of the present invention, "overflow" is defined as the undesirable accumulation of fluid on the surface of the ejection head. Overflow can cause cross-contamination between ejected fluids, reducing device performance and even rendering the device inoperable without intervention. Summary of the Invention [Problem to be solved by the invention]

[0003] Overflow typically occurs due to a suboptimal device design for the particular fluid characteristics or inappropriate dispensing parameters, causing dispensing instability. A desirable characteristic of an ejection head for hydrophilic fluids such as ink is to have a hydrophobic ejection surface, thereby preventing overflow and minimizing the spreading of fluid across the face of the nozzle plate if overflow does occur. If the fluid ejection device is operated to eject only in short bursts, overflow may self-correct once a steady state is recovered and the fluid is able to return to the nozzles from which it is ejected. However, if overflow is cascaded across multiple nozzles, the device will not self-correct even after recovery to a steady state, and the overflow must be mechanically removed, typically by wiping the face of the nozzle plate.

[0004] The potential for overflow must be considered during the design of standard horizontal ejection heads, which typically have nozzles pointing down. The potential for cascading overflows increases when the ejection head is turned so that the nozzle plate is horizontal and the nozzles point up, when the nozzle plate is not horizontal, and when the nozzle plate is vertical and the nozzles are perpendicular to gravity. In the vertical orientation, overflow is exacerbated because gravity pulls the unstable meniscus towards the adjacent nozzle directly below the nozzle from which the fluid is ejected.

[0005] Therefore, there is a need for a dispensing head with features that prevent overflow or divert overflow away from adjacent nozzles, especially when the dispensing head is operated in a non-standard orientation. [Means for solving the problem]

[0006] In view of the above, embodiments of the present invention provide a nozzle plate configured for a fluid ejection head, a fluid ejection head including the nozzle plate, and a method of modifying the nozzle plate to reduce overflow of fluid thereon, the nozzle plate including a plurality of nozzle holes attached to a flow feature layer on a semiconductor substrate, the nozzle plate including a first hydrophobic region surrounding each of the plurality of nozzle holes, the first hydrophobic region configured to reduce overflow of the nozzle plate.

[0007] In some embodiments, the nozzle plate has a second hydrophobic layer disposed on an exposed surface thereof, the second hydrophobic layer having raised hydrophobic regions relative to the first hydrophobic regions.

[0008] In some embodiments, the nozzle plate includes a hydrophilic region adjacent to a first hydrophobic region.

[0009] In some embodiments, the nozzle plate has a raised second hydrophobic region above the hydrophilic region, the raised second hydrophobic region having a channel disposed therein in fluid communication with the first hydrophobic region surrounding each of the plurality of nozzle holes, the channel being configured to direct fluid out of each of the plurality of nozzle holes through the raised second hydrophobic region, hi other embodiments, the channel is wedge-shaped.

[0010] In some embodiments, a fluid ejection head is arranged including a semiconductor substrate including a plurality of fluid ejectors, a flow feature layer attached to the semiconductor substrate, and a nozzle plate including a plurality of nozzle holes attached to the flow feature layer on the semiconductor substrate, the nozzle plate including a first hydrophobic region surrounding each of the plurality of nozzle holes, the first hydrophobic region configured to reduce overflow of the nozzle plate.

[0011] In another embodiment, a method is provided for modifying a nozzle plate of a fluid ejection device to reduce overflow of fluid thereon. The method includes: applying a sacrificial layer to an exposed surface of the nozzle plate, the exposed surface of the nozzle plate being hydrophobic; imaging and developing the sacrificial layer and disposing a protective cap over each nozzle hole in the nozzle plate, the protective cap having a diameter greater than a diameter of the nozzle hole covered by the protective cap; treating an uncapped surface of the nozzle plate to dispose an uncapped hydrophilic surface region of the nozzle plate; and then removing the protective cap from each nozzle hole of the nozzle plate to dispose a nozzle plate having a first hydrophobic region surrounding each nozzle hole and a hydrophilic region adjacent the first hydrophobic region. In another embodiment, the sacrificial layer is a layer of positive photoresist material.

[0012] In some embodiments, a negative photoresist material is applied to the exposed surface of the nozzle plate, and the negative photoresist material is imaged and developed to position a raised second hydrophobic region above the hydrophilic region adjacent to the first hydrophobic region surrounding each nozzle hole, while in other embodiments, a channel in the raised second hydrophobic region that extends down to the hydrophilic region to direct fluid away from each nozzle hole is imaged and developed. Effect of the Invention

[0013] The above-described embodiments provide a fluid ejection head having features that include a fluid boundary region and a fluid runoff region on the exposed surface of the nozzle plate to improve retention or redirection of fluid that may accumulate on the nozzle plate surface, thereby facilitating self-correction of overflowed nozzles and inhibiting bridging overflow of the nozzles. [Brief description of the drawings]

[0014] [Figure 1] 1 is a perspective view (not to scale) of a fluid ejection device according to the present invention. [Diagram 2] FIG. 1 is a cross-sectional view (not to scale) of a portion of a dispensing head according to the present invention. [Diagram 3] FIG. 1 is a cross-sectional view (not to scale) of a dispensing head manufactured in accordance with a first embodiment of the present invention. [Figure 4] FIG. 1 is a cross-sectional view (not to scale) of a dispensing head manufactured in accordance with a first embodiment of the present invention. [Diagram 5] FIG. 1 is a cross-sectional view (not to scale) of a dispensing head manufactured in accordance with a first embodiment of the present invention. [Figure 6] FIG. 1 is a cross-sectional view (not to scale) of a dispensing head manufactured in accordance with a first embodiment of the present invention. [Figure 7] FIG. 7 is a plan view of the dispensing head of FIG. 6 (not to scale). [Figure 8] FIG. 4 is a cross-sectional view (not to scale) of a portion of a dispensing head manufactured in accordance with a second embodiment of the present invention. [Figure 9] FIG. 9 is a plan view (not to scale) of the dispensing head of FIG. 8. [Figure 10] FIG. 2 is a cross-sectional view (not to scale) of a completed dispensing head according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a plan view (not to scale) of the dispensing head of FIG. 10. [Figure 12] FIG. 9 is a plan view (not to scale) of the dispensing head of FIG. 8 with the protective cap removed. [Figure 13] FIG. 11 is a cross-sectional view (not to scale) of a dispensing head manufactured in accordance with a third embodiment of the present invention. [Figure 14] FIG. 11 is a cross-sectional view (not to scale) of a dispensing head manufactured in accordance with a third embodiment of the present invention. [Figure 15] FIG. 15 is a plan view (not to scale) of a discharge head according to a fourth embodiment of the present invention using the discharge head shown in FIG. [Figure 16] FIG. 15 is a plan view (not to scale) of a discharge head according to a fourth embodiment of the present invention using the discharge head shown in FIG. [Figure 17] FIG. 11 is a cross-sectional view (not to scale) of a dispensing head according to a fifth embodiment of the present invention. [Figure 18] FIG. 11 is a cross-sectional view (not to scale) of a dispensing head according to a sixth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention relates to an improved fluid ejection head, and in particular to improvements relating to nozzle plates of fluid ejection heads for fluid dispensing devices. The fluid ejection heads can be used in a variety of fluid ejection devices, including but not limited to printers, a nasal spray device 100 (FIG. 1) for delivering medication to a patient, devices for depositing one or more fluids onto wells of a microwell plate or a glass slide, or similar devices. Devices such as the nasal spray device 100 require the delivery of a precise amount of medication to a patient through a nozzle 102 using a fluid ejection head attached to a fluid cartridge within the body 104 of the device. A power button 106 and a power indicator LED 108 are positioned to indicate when the device is ready to start. A dose button 110 can be activated by the patient to deliver a predetermined dose of fluid from the ejection head, as indicated by LED 112. However, if liquid accumulates in the ejection head, improper delivery of the medication can occur. This is particularly problematic in the device 100, where the fluid ejection head cannot be used in a horizontal downward fluid ejection sequence. Such devices 100 typically do not include a wiper blade to remove excess fluid from the surface of the nozzle plate. Thus, the improved nozzle plate and fluid ejection head described herein provide a means to reduce or prevent fluid buildup on the nozzle plate surface adjacent the nozzle holes in the nozzle plate. The devices and methods described herein can also reduce or avoid cross-contamination of fluids on the nozzle plate surface when the ejection head is configured to eject multiple different fluids.

[0016] 2 shows a portion of a fluid ejection head 114. The fluid ejection head 114 includes a semiconductor substrate 116 on which a fluid ejector 118 is disposed. The fluid ejector 118 may be a heater resistor or a piezoelectric device. Fluid is provided to the fluid ejection head from a liquid cartridge in the device body 104 through a fluid via 120 etched through the semiconductor substrate 116. The fluid then flows into a fluid chamber 122 in a flow feature layer 124 and, upon actuation of the fluid ejector 118, the fluid is expelled through a nozzle hole 126 in a nozzle plate 128. The top layer of the nozzle plate 128 is a hydrophobic layer 130. Thus, the hydrophobic layer 130 may be formed of any of the following compounds: heptadecafluorodecyltrimethoxysilane, octadecyldimethylchlorosilane, octadecyltrichlorosilane, methyltrimethoxysilane, octyltriethoxysilane, phenyltrimethoxysilane, t-butylmethoxysilane, tetraethoxysilane, sodium methyl siliconate, vinyltrimethoxysilane, N-(3-(trimethoxylsilyl)propyl)ethylenediamine polymethylmethoxysilox ... The hydrophobizing agent may include a hydrophobizing agent such as polymethylmethoxysiloxane, polydimethylsiloxane, polyethylhydrogensiloxane, and dimethyl siloxane. The hydrophobizing agent may be included in the hydrophobic layer 130 or the hydrophobizing agent may be coated on the nozzle plate 128.The thickness of the hydrophobic layer 130 can range from about 3 micrometers to about 10 micrometers.

[0017] In a first embodiment of the present invention, as shown in FIG. 3, a sacrificial layer 132 (e.g., a positive photoresist layer) can be applied to the hydrophobic layer 130 of the nozzle plate 128 / 130 by spin-coating or laminating the sacrificial layer 132 to the hydrophobic layer 130. The thickness of the sacrificial layer is not particularly important as long as the sacrificial layer 132 has sufficient viscosity to cover the nozzle hole 126. Thus, the thickness of the sacrificial layer can range from about 5 micrometers to about 50 micrometers. The sacrificial layer 132 can then be imaged through a mask 134 that includes opaque areas 136 and transparent areas 138 using actinic radiation, such as ultraviolet light, as indicated by arrows 140. After developing the exposed portions of the sacrificial layer 132, a protective cap 142 remains over the nozzle hole 126, as shown in FIG. 4. The exposed surfaces 144 of the nozzle plates 128 / 130 are treated with an oxygen plasma, as indicated by arrows 146 (FIG. 5), to change the surface energy of the exposed regions and provide hydrophilic regions 148 surrounding capped hydrophobic regions 150 of the nozzle plates, as shown in cross section in FIG 6 and in plan view in FIG 7. As noted above, the hydrophilic regions can be the same thickness as the hydrophobic layer 130.

[0018] In a second embodiment shown in Figures 8-9, a fluid ejection head 114 has a hydrophilic nozzle plate 128 beneath hydrophobic regions 150 formed by a hydrophobic layer 130 (see Figure 5). Thus, exposed surface 144 (see Figure 5) of nozzle plate layer 128 / 130 can withstand biased heating and highly selective radio frequency (RF) plasma etching, and protective cap 142 masks hydrophobic regions 150 around each nozzle hole 126 (see Figure 2), while unmasked areas 152 of the nozzle plate are made hydrophilic by removing hydrophobic layer 130 (see Figure 5), as shown in Figure 8.

[0019] Other surface treatments can be used to increase the hydrophilicity of the exposed nozzle plate surface 152. For example, a high bias plasma can be used on the surface to impart surface roughness through a sputtering effect, as well as modifying the surface energy of the exposed nozzle plate surface 152. The roughened surface can improve adhesion to subsequently applied layers of material. Plasma etching is suitable for forming permanent hydrophilic regions on the nozzle plate surface 152, while plasma treatments are typically used to improve adhesion to additional layers. Various gases, such as forming gas and oxygen gas, can be used in the process to modify the surface chemistry of the exposed nozzle plate surface 152.

[0020] Next, in the first and second embodiments, the protective cap 142 is stripped from the hydrophobic regions 150 (FIG. 10) to provide a nozzle plate having only the hydrophobic regions 150 surrounding each of the nozzle holes 126 and the hydrophilic regions 148 (FIG. 11) or hydrophilic regions 152 (FIG. 12) surrounding the hydrophobic regions 150. The protective cap 142 can be stripped using a conventional photoresist solvent bath and high or low pressure rinse, or a conventional deep reactive ion etch stripping process for photoresist materials.

[0021] In a third embodiment of the present invention, as shown in FIG. 13, a negative photoresist material 154 is applied to the release surface of the nozzle plate (FIG. 10) by spin coating, spray coating, or lamination to cover the hydrophobic regions 150 and the hydrophilic regions 148. The thickness of the negative photoresist material ranges from about 1 micrometer to about 5 micrometers, for example, about 1.5 micrometers to about 2.5 micrometers. As before, the negative photoresist material 154 is imaged using actinic radiation (indicated by arrows 140) through a mask 156 that includes opaque regions 158 and transparent regions 160. Upon development of the imaged negative photoresist layer 154, hydrophobic levees 162 are formed on the hydrophilic regions 148 (FIG. 14) to inhibit overflow from spreading across the nozzle plate surface into the nozzle holes 126. In some embodiments, the negative photoresist material 154 is hydrophobic. In other embodiments, the negative photoresist material is hydrophilic.

[0022] In a fourth embodiment, the negative photoresist material 154 can be imaged and developed to form a channel extending down to the hydrophilic region adjacent the hydrophobic region 150 around the nozzle hole 126 to facilitate flow of fluid out of the nozzle hole. In some embodiments, the channel 170 has a wedge shape in plan view, as shown in FIG. 15. In other embodiments, the channel 172 has a rectangular shape in plan view, as shown in FIG. 16. The rectangular channel 172 can be narrowed to a width sufficient to facilitate capillary action to force fluid out of the nozzle hole 126. A variety of other geometric shapes of channels can be used, so long as the channel can reach from the exposed surface of the hydrophobic bank 162 to the hydrophilic region 148 extending down the hydrophobic bank 162.

[0023] In a fifth embodiment, as previously described, a thick hydrophobic layer 174 applied to the nozzle plate 128 can be partially etched around the protective cap 142 to provide a hydrophobic ridge 176 around the nozzle hole 126, as shown in Figure 17. The thickness of the thick hydrophobic layer can be greater than 5 micrometers up to about 10 micrometers. An inner corner 178 of the hydrophobic ridge 176 acts as a first drop-pinning boundary, and an outer corner 180 of the hydrophobic ridge acts as a second drop-pinning boundary to prevent droplets of fluid from covering the nozzle hole 126.

[0024] In a sixth embodiment, a thick hydrophobic layer 174 as shown in Figure 17 may be sputtered or etched such that the hydrophobic surface is roughened but not completely removed in the uncapped areas 184 surrounding the capped areas 186 as shown in Figure 18. The above embodiments provide a nozzle plate having smooth hydrophobic areas 186 surrounding the nozzle holes 126 and rough hydrophobic areas 184 surrounding the smooth hydrophobic areas 186. Depending on capillary, gravity, viscous effects, and the surface energy of the nozzle plate and the surface tension of the fluid, it is believed that increasing the surface roughness of the nozzle plate reduces the wettability of some fluids and acts as a micro-levee around the nozzle holes.

[0025] In all the above embodiments, the photoresist material can be deposited by spin coating, spray coating, or lamination, although lamination may be most practical in some circumstances. For spin coating, the photoresist material must be sufficiently viscous and the casting speed must be sufficiently high so that the photoresist layer covers the top of the nozzle hole 126.

[0026] The photoresist materials described in the embodiments herein include a photoacid generator and can be formulated to include one or more of a multifunctional epoxy compound, a difunctional epoxy compound, a relatively high molecular weight polyhydroxy ether, an adhesion promoter, and an aliphatic ketone solvent. For purposes of the present invention, "difunctional epoxy" refers to epoxy compounds and materials that have only two epoxy functional groups in the molecule. "Multifunctional epoxy" refers to epoxy compounds and materials that have more than two epoxy functional groups in the molecule.

[0027] The epoxy component used to prepare the photoresist formulation according to the present invention can be selected from aromatic epoxides such as glycidyl ethers of polyphenols. An exemplary first multifunctional epoxy resin is a polyglycidyl ether of phenolformaldehyde novolac resin, e.g., a novolac epoxy resin having an epoxide gram equivalent weight of about 190 to about 250 and a viscosity at 130°C of about 10 to about 60 centipoise.

[0028] The multifunctional epoxy component may have a weight average molecular weight of about 3,000 to about 5,000 Daltons as measured by gel permeation chromatography, and an average epoxy group functionality of greater than 3, preferably about 6 to about 10. The amount of multifunctional epoxy resin in the photoresist formulation may range from about 30 to about 50 weight percent based on the weight of the dried photoresist layer.

[0029] The difunctional epoxy component may be selected from difunctional epoxy compounds including diglycidyl ethers of bisphenol-A, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclo-hexene carboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexene carboxylate, bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, and bis(2,3-epoxycyclopentyl) ether.

[0030] An exemplary difunctional epoxy component is a bisphenol A / epichlorohydrin epoxy resin with an epoxy equivalent weight greater than about 1000. "Epoxide equivalent" refers to the number of grams of resin that contain one gram equivalent of epoxy. The weight average molecular weight of the difunctional epoxy component is typically greater than 2500 Daltons, for example, a weight average molecular weight of about 2800 to about 3500 Daltons. The amount of the first difunctional epoxy component in the photoresist formulation may range from about 30 to about 50 weight percent based on the weight of the cured resin.

[0031] Exemplary photoacid generators include compounds or mixtures of compounds capable of generating cations, such as aromatic complex salts, which may be selected from, for example, onium salts of Group VA elements, onium salts of Group VIA elements, and aromatic halonium salts. The aromatic complex salts, when exposed to ultraviolet or electron beam radiation, can generate acid moieties that initiate a reaction with the epoxide. The photoacid generator may be present in the photoresist formulations described herein in an amount ranging from about 5 to about 15 weight percent based on the weight of the cured resin.

[0032] Compounds that generate a protonic acid upon irradiation with actinic rays can be used as photoacid generators, and include, but are not limited to, aromatic iodonium complex salts and aromatic sulfonium complex salts. Examples include di-(t-butylphenyl)iodonium triflate, diphenyliodonium tetrakis(pentafluorophenyl)borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di(4-nonylphenyl)iodonium hexafluorophosphate, [4-(octyloxy)phenyl]phenyliodonium hexafluoroantimonate, triphenylsulfonium triflate, triphenyl-sulfonium hexafluorophosphate, hexafluorophosphate), triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis(pentafluorophenyl)boratetetrakis(pentafluorophenyl)borate), 4,4'-bis[diphenylsulfonium]diphenylsulfide, bis-hexafluorophosphate, 4,4'-bis[di([beta]-hydroxyethoxy)phenylsulfonium]diphenylsulfide, bis-hexafluoroantimonate, 4,4'-bis[di([beta]-hydroxyethoxy)phenylsulfonium]diphenylsulfide bishexafluorophosphate sulfide-bishexafluoro-phosphate), 7-[di(p-tolyl)sulfonium]-2-isopropylthioxanthone hexafluorophosphate, 7-[di(p-tolyl)sulfonio-2-isopropylthioxanthone hexafluoroantimonate, 7-[di(p-tolyl)sulfonium]-2-isopropyl tetrakis(pentafluorophenyl)borate, phenylcarbonyl-4'-diphenylsulfonium diphenylsulfide hexafluorophosphate Diphenyl sulfidehexafluorophosphate), phenylcarbonyl-4'-diphenylsulfonium diphenylsulfide hexafluoroantimonate, 4-tert-butylphenylcarbonyl-4'-diphenylsulfonium diphenylsulfide hexafluorophosphate, 4-tert-butylphenylcarbonyl-4'-diphenylsulfonium diphenylsulfide hexafluoroantimonate, 4-tert-butylphenylcarbonyl-4'-diphenylsulfonium diphenylsulfide tetrakis(pentafluorophenyl)borate tetrakis(pentafluorophenyl)borate, diphenyl [4-(phenylthio)phenyl]sulfonium hexafluoro-antimonate, etc.

[0033] Hydrophobing agents that can be used for positive or negative photoresist materials include silicon-containing materials such as silanes and siloxanes. Thus, the hydrophobizing agents are heptadecylfluorodecyltrimethoxysilane, octadecyldimethylchlorosilane, octadecyltrichlorosilane, methyltrimethoxysilane, octyltriethoxysilane, phenyltrimethoxysilane, t-butylmethoxysilane, tetraethoxysilane, sodium methyl siliconate, vinyltrimethoxysilane, N-(3-(trimethoxylsilyl)propyl)ethylenediamine polymethylmethoxysiloxane, The hydrophobizing agent may be selected from polymethylmethoxysiloxane, polydimethylsiloxane, polyethylhydrogensiloxane, and dimethyl siloxane. The amount of hydrophobizing agent in the hardened photoresist material may be from about 0.5 to about 2 weight percent, such as from about 1.0 to about 1.5 weight percent, including all ranges contained therein, based on the total weight of the hardened resin.

[0034] The solvent used in preparing the photoresist formulation is a non-photoreactive solvent. Non-photoreactive solvents include, but are not limited to, gamma butyrolactone, C1-6 acetate, tetrahydrofuran, low molecular weight ketones, mixtures thereof, and the like. The non-photoreactive solvent is present in the formulation mixture used to provide the photoresist material in an amount ranging from about 20 to about 90 weight percent, for example, from about 40 to about 60 weight percent, based on the total weight of the photoresist formulation. The non-photoreactive solvent is typically removed before or during the curing step of the photoresist layer, since it does not remain in the cured photoresist layer.

[0035] The photoresist formulation may optionally include an effective amount of an adhesion promoter, such as a silane compound. Silane compounds compatible with the components of the photoresist formulation typically have a functional group capable of reacting with at least one component selected from the group consisting of multifunctional epoxy compounds, difunctional epoxy compounds, and photoinitiators. Such adhesion promoters may be, for example, silanes having epoxy functional groups, such as glycidoxyalkyltrialkoxysilanes, such as 3-(guanidinyl)propyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane, and the like. When used, the adhesion promoter may be present in an amount ranging from about 0.5 to about 2 weight percent, such as from about 1.0 to about 1.5 weight percent, including all ranges contained therein, based on the total weight of the cured resin. As used herein, adhesion promoter is defined to mean an organic material that is soluble in the photoresist composition and contributes to the film forming and adhesive properties of the photoresist layer.

[0036] For purposes of this specification and the appended claims, unless otherwise indicated, all numerical values ​​and other values ​​expressing quantities, percentages or proportions used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless otherwise indicated, the numerical parameters set forth in the following specification and appended claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0037] While particular embodiments have been described, presently unforeseen or unforeseeable alternatives, modifications, variations, improvements, and substantial equivalents may occur to applicant or those skilled in the art, and it is accordingly intended that the appended claims, as filed and as amended, cover all such alternatives, modifications, variations, improvements, and substantial equivalents. [Industrial Applicability]

[0038] The nozzle plates, fluid ejection heads, fluid ejection devices, and methods of modifying nozzle plates of the present invention provide fluid boundary regions and fluid outflow regions on the exposed surface of the nozzle plate, which can promote self-correction of overflowed nozzles and inhibit bridging overflow of nozzles by improving the retention or redirection of fluid that may accumulate on the nozzle plate surface. [Explanation of symbols]

[0039] 100: Nasal spray device 102: Nozzle 104: Main unit 106: Power button 108: Power indicator LED 110: Medication button 112: LED 114: Fluid ejection head 116: Semiconductor substrate 118: Fluid ejector 120: Fluid via 122: Fluid chamber 124: Fluid feature layer 126: Nozzle hole 128: Nozzle plate 130: Hydrophobic layer 132: Sacrificial Layer 134: Mask 136: Opaque area 138: Transparent area 140: Arrow 142: Protective cap 144: Exposed surface 146: Arrow 148:Hydrophilic region 150: Hydrophobic region 152: Unshielded area / exposed nozzle plate surface / hydrophilic area 154: Negative photoresist material / imaged negative photoresist layer 156: Mask 158: Opaque area 160: Transparent area 162: Hydrophobic embankment 170: Wedge-shaped channel 172: Rectangular channel 174: Thick hydrophobic layer 176: Hydrophobic ridge 178:Inner corner 180:Outer corner 184: Uncapped region / rough hydrophobic region 186: Capped region / smooth hydrophobic region

Claims

1. 1. A nozzle plate configured for a fluid ejection head, comprising: the nozzle plate includes a plurality of nozzle holes; the nozzle plate is attached to a flow feature layer on a semiconductor substrate; the nozzle plate further includes a first hydrophobic region surrounding each of the plurality of nozzle holes; Nozzle plate.

2. the nozzle plate further comprising a second hydrophobic layer on an exposed surface thereof; the second hydrophobic layer includes a hydrophobic region that is elevated relative to the first hydrophobic region; The nozzle plate of claim 1 .

3. further comprising a hydrophilic region adjacent to the first hydrophobic region; The nozzle plate of claim 1 .

4. a second hydrophobic region elevated above the hydrophilic region; the raised second hydrophobic region includes a channel in fluid communication with the first hydrophobic region surrounding each of the plurality of nozzle holes; the channel is configured to direct fluid out of each of the plurality of nozzle holes through the raised second hydrophobic region. The nozzle plate according to claim 3 .

5. the channel is wedge shaped; The nozzle plate according to claim 4 .

6. A fluid ejection head comprising the nozzle plate according to claim 1 .

7. a semiconductor substrate including a plurality of fluid ejectors; a flow feature layer attached to the semiconductor substrate; a nozzle plate attached to the flow feature layer on the semiconductor substrate, the nozzle plate including a plurality of nozzle holes; Including, the nozzle plate includes a first hydrophobic region surrounding each of the plurality of nozzle holes; Fluid ejection head.

8. the nozzle plate further comprising a second hydrophobic layer on an exposed surface thereof; the second hydrophobic layer includes a hydrophobic region that is elevated relative to the first hydrophobic region; The fluid ejection head of claim 7 .

9. further comprising a hydrophilic region adjacent to the first hydrophobic region; The fluid ejection head of claim 7 .

10. a second hydrophobic region elevated above the hydrophilic region; the raised second hydrophobic region includes a channel in fluid communication with the first hydrophobic region surrounding each of the plurality of nozzle holes; the channel is configured to direct fluid out of each of the plurality of nozzle holes through the raised second hydrophobic region. The fluid ejection head of claim 9.

11. the channel is wedge shaped; The fluid ejection head of claim 10.

12. A fluid ejection device comprising the fluid ejection head according to claim 7.

13. 1. A method of modifying a nozzle plate of a fluid ejection device to reduce overflow of fluid thereon, comprising: applying a sacrificial layer to an exposed surface of the nozzle plate, the exposed surface of the nozzle plate being hydrophobic; imaging and developing the sacrificial layer and placing a protective cap over each nozzle hole in the nozzle plate, the diameter of the protective cap being greater than the diameter of the nozzle hole covered by the protective cap; treating an uncapped surface of the nozzle plate to provide an uncapped hydrophilic surface region of the nozzle plate; removing the protective caps from each nozzle hole of the nozzle plate to provide a nozzle plate having a first hydrophobic region surrounding each nozzle hole and a hydrophilic region adjacent the first hydrophobic region; A method comprising:

14. the sacrificial layer comprises a layer of a positive photoresist material; The method of claim 13.

15. applying a negative photoresist material to the exposed surface of the nozzle plate. The method of claim 13.

16. imaging and developing a negative photoresist material to provide second hydrophobic regions elevated above the hydrophilic regions adjacent the first hydrophobic regions surrounding each nozzle hole. The method of claim 15.

17. imaging and developing a channel in the raised second hydrophobic region that extends down to the hydrophilic region to direct fluid away from each nozzle hole.

17. The method of claim 16.

18. the channel is wedge shaped; 20. The method of claim 17.

Images