Method for ejecting liquid from a liquid ejection device and method for manufacturing a liquid ejection device

Abstract

To achieve both rapid nozzle refilling and sufficiently high nozzle pressure.SOLUTION: A method of liquid ejection comprises: ejecting liquid from a nozzle 22 of a liquid ejector; and refilling the nozzle 22 with liquid from a flow path. A membrane 300 formed across the flow path provides the flow path with a first impedance when fluid is being ejected from the nozzle 22, and provides the flow path with a second impedance when fluid is not being ejected from the nozzle, where the first impedance is greater than the second impedance.SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure generally relates to methods for ejecting liquid from a liquid ejector and methods for manufacturing a liquid ejector. [Background technology]

[0002] In some liquid ejection devices, droplets are ejected onto a medium from one or more nozzles. The nozzles are fluidly connected to a flow path that includes a fluid pumping chamber. The fluid pumping chamber can be actuated by an actuator, causing the ejection of droplets. The medium can be moved relative to the liquid ejection device. The ejection of droplets from a particular nozzle is timed to coincide with the movement of the medium to position the droplets at desired locations on the medium. The ejection of droplets of uniform size and velocity and in the same direction allows for uniform deposition of the droplets on the medium. Summary of the Invention [Problem to be solved by the invention]

[0003] When fluid is ejected from a nozzle of a liquid ejection device, the nozzle may become at least partially depleted of liquid, leaving the nozzle unready for further droplet ejection. Fluid circulation through a “leak” flow path to the nozzle can refill the depleted nozzle. If these leakage paths have a large cross-sectional area, the depleted nozzle can refill quickly after liquid is ejected from the nozzle and become more quickly ready for subsequent liquid ejection. However, a large leakage flow path can make it difficult to achieve a sufficiently high pressure at the nozzle opening for efficient liquid ejection. To achieve both rapid nozzle refill and sufficiently high nozzle pressure, impedance features can be placed in the flow path. The impedance feature provides a higher fluid impedance in the leakage flow path than other frequencies at or around the jet resonant frequency. The jet resonant frequency is a frequency at which the nozzle has high fluid flow, such as during fluid ejection from the nozzle. As a result of the high fluid impedance at the jet resonant frequency provided by the impedance feature, the fluid impedance in the flow path is higher during liquid ejection than at other times, such as during refilling, thereby allowing for a sufficiently high pressure to be achieved during ejection while still providing for rapid refilling of starved nozzles when liquid is not being ejected. The impedance feature can be a membrane with an aperture located in the liquid supply or return path.

[0004] Another problem is that the fluid may contain contaminants, such as impurities, that can clog or damage the nozzle. It is useful to have a filter to prevent such contaminants from reaching the nozzle or being released onto the surface. The impedance feature may be an apertured membrane placed in the liquid supply path. [Means for solving the problem]

[0005] In a first aspect, a liquid ejection device includes a nozzle layer, a body, an actuator, and a membrane. The nozzle layer has an outer surface, an inner surface, and a nozzle extending between the inner surface and the outer surface. The nozzle has an inlet on the inner surface for receiving liquid and an outlet opening on the outer surface for ejecting liquid. The inner surface of the nozzle layer is fixed to the body. The body includes a pumping chamber, a return channel, and a first passage fluidly connecting the pumping chamber to the nozzle inlet. A second passage fluidly connects the nozzle inlet to the return channel. The actuator is configured to force liquid out of the pumping chamber, such that actuation of the actuator causes liquid to be ejected from the nozzle. The membrane is formed to straddle and partially block at least one of the first passage, the second passage, or the nozzle inlet. The membrane has at least one hole therethrough, such that, upon actuation of the liquid ejection device, fluid flows through the at least one hole in the membrane.

[0006] Implementations may include one or more of the following features.

[0007] The membrane and holes may be configured so that the first flow path has a first impedance when fluid is being ejected from the nozzle and a second impedance when fluid is not being ejected from the nozzle. The first impedance may be greater than the second impedance. The membrane may be configured so that the second flow path has a maximum impedance at or around a resonant frequency of the nozzle.

[0008] The membrane may extend substantially parallel to the outer surface.

[0009] The membrane may be formed across the second passage. The second passage may include a first portion between the inlet to the nozzle and the membrane and a second portion between the membrane and the return channel. The first and second portions may be separated by a membrane, and a hole through the membrane may fluidly connect the first portion to the second portion. The first portion may be provided on a side of the membrane away from the outer surface, and the second portion may be provided on a side of the membrane closer to the outer surface. The first portion may be provided on the body, and the second portion may be provided on the nozzle layer. The first portion may be provided on a side of the membrane closer to the outer surface, and the second portion may be provided on a side of the membrane farther from the outer surface.

[0010] The second channel and the return channel can be separated by the membrane, and a hole through the membrane can fluidly connect the second channel to the return channel. The surface of the membrane distal to the exterior can be flush with the bottom surface of the return channel.

[0011] The membrane may be formed over the nozzle.

[0012] The membrane may have a plurality of holes therethrough, which may be uniformly spaced across the membrane, and which may be configured to provide a filter.

[0013] A membrane layer may extend parallel to the outer surface and may span across the liquid ejection device, and a membrane may be provided by a portion of the membrane layer. The membrane layer may be embedded within the body. The membrane layer may be provided between the body and the nozzle layer. A cavity may be disposed adjacent to a return channel or a supply channel fluidly connected to a pumping chamber and fluidly separated therefrom by the membrane layer. The cavity and the portion of the layer above the cavity may provide a compliant microstructure to reduce crosstalk.

[0014] A wafer of a first material can be bonded to a side of the membrane layer away from the outer surface, and a device layer of the first material can be bonded to a side of the layer closer to the outer surface. The membrane can be a second material of a different material composition than the first material. The first material can be single crystal silicon. The second material can be silicon dioxide.

[0015] The membrane may extend substantially parallel to the outer surface. The hole may be spaced apart from the wall of the first passage, the second passage, or the nozzle on all sides of the hole. The membrane may project inwardly substantially perpendicular to the wall of the first passage, the second passage, or the nozzle. The membrane may be formed of a material having a lower modulus of elasticity than the material forming the wall of the first passage, the second passage, or the nozzle. The membrane may be more flexible than the wall of the first passage, the second passage, or the nozzle. The hole through the membrane may be narrower than the outlet opening of the nozzle.

[0016] The membrane may be formed of an oxide and may have a thickness between about 0.5 μm and about 5 μm. The membrane may be formed of a polymer and may have a thickness between about 10 μm and about 30 μm.

[0017] In another aspect, a liquid ejection device includes a substrate and a membrane. The substrate includes a nozzle having an opening in an outer surface of the substrate, a flow path including a first portion from a pumping chamber to the nozzle and a second portion from the nozzle to a return channel, and an actuator configured to eject liquid from the pumping chamber, such that actuation of the actuator causes liquid to be ejected from the nozzle. The membrane spans the second portion of the flow path and is configured to provide an impedance to the flow path responsive to an oscillation frequency of the liquid in the flow path. The membrane has at least one hole therethrough, and upon actuation, liquid flows through the at least one hole in the membrane.

[0018] Implementations may include one or more of the following features.

[0019] The membrane may be configured to provide a first impedance when fluid is ejected from the nozzle and a second impedance when fluid is not ejected from the nozzle, the first impedance being greater than the second impedance, and the membrane may be configured to provide a maximum impedance to the flow path at or around a resonant frequency of the nozzle.

[0020] The first impedance is greater than the second impedance. A membrane is formed across a second portion of the flow path. The membrane is configured to provide an impedance to the flow path in response to an oscillation frequency of fluid in the flow path. The membrane may be more flexible than the walls of the flow path. The membrane may extend substantially parallel to an outer surface. The membrane may protrude inwardly substantially perpendicular to the walls of the flow path.

[0021] The compliant microstructure may be adjacent to a return channel or a supply channel fluidly connected to the pumping chamber, and a membrane layer providing the membrane may separate the cavity from the return channel or the supply channel, respectively.

[0022] In another aspect, a method of ejecting liquid includes ejecting liquid from a nozzle of a liquid ejection device and refilling the nozzle with liquid from a flow path, the membrane being formed across the flow path and providing a first impedance to the flow path when fluid is being ejected from the nozzle and a second impedance when fluid is not being ejected from the nozzle, the membrane having at least one hole therethrough.

[0023] Implementations may include one or more of the following features.

[0024] Refilling the nozzle can include flowing fluid through at least one hole defined by the membrane and into a flow path. The flow path can fluidly connect the nozzle to a return channel. The flow path can fluidly connect the nozzle to a pumping chamber. Ejecting liquid from the nozzle can include actuating an actuator to eject liquid from a pumping chamber fluidly connected to the nozzle.

[0025] In another aspect, a method for manufacturing a liquid ejection device includes forming a nozzle in a nozzle layer, the nozzle layer having a first surface, the nozzle having an outlet opening in the first surface for ejecting liquid; forming a membrane on a second surface of the nozzle layer on a side of the nozzle layer remote from the first surface; forming at least one hole through the membrane; and attaching the side of the membrane remote from the nozzle layer to a wafer having a pumping chamber and a return channel such that the at least one hole in the membrane provides a constriction in the passage between the pumping chamber and the nozzle or the second passage between the nozzle and the return channel.

[0026] Implementations may include one or more of the following features.

[0027] An actuator may be formed on the wafer. The actuator may be configured to force liquid out of a pumping chamber, such that actuation of the actuator may cause liquid to be ejected from the nozzle. The membrane and at least one hole may be formed to have a maximum impedance at or around a resonant frequency of the nozzle. Forming the at least one hole may include etching the membrane. Multiple holes may be formed in the membrane. The membrane may be formed of an oxide or a polymer. The nozzle layer may be disposed on a handle layer, and the membrane may be formed on a side of the nozzle layer opposite the handle layer. The handle layer may be removed.

[0028] The approach described herein may have one or more of the following advantages.

[0029] The impedance feature allows for rapid refilling of a dry nozzle while still allowing for a sufficiently high pressure to be achieved during liquid ejection. The impedance feature can be fabricated with few additional steps using existing fabrication techniques and can therefore be easily integrated into current process flows.

[0030] The filter features can prevent impurities from reaching and clogging the nozzle or from being expelled onto a surface. The filters can be fabricated in conjunction with compliant features in the supply or return channels without significantly increasing fabrication complexity.

[0031] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, drawings, and claims. [Brief explanation of the drawings]

[0032] [Figure 1] FIG. 1 is a schematic, partially cut-away perspective view of a printhead. [Figure 2] FIG. 2 is a schematic cross-sectional view of a portion of a printhead. [Figure 3A] FIG. 3A is a schematic cross-sectional view of three implementations of a liquid ejection device. [Figure 3B] FIG. 3B is a schematic cross-sectional view of three implementations of a liquid ejection device. [Figure 3C] FIG. 3C is a schematic cross-sectional view of three implementations of a liquid ejection device. [Figure 3D] FIG. 3D is a schematic cross-sectional view of three implementations of a liquid ejection device. [Figure 4A] FIG. 4A is a schematic cross-sectional view of a portion of the printhead taken along line BB in FIG. [Figure 4B] FIG. 4B is a schematic cross-sectional view of a portion of the printhead taken along line CC in FIG. [Figure 5A] FIG. 5A is a schematic top view of the membrane. [Figure 5B] FIG. 5B is a schematic side view of the membrane. [Figure 6] FIG. 6 is a schematic cross-sectional view of the liquid ejection device. [Figure 7A] FIG. 7A is a schematic top view of a feed channel having a recess. [Figure 7B] FIG. 7B is a schematic side view of a feed channel having a recess. [Figure 8A] FIG. 8A is a schematic cross-sectional view illustrating a method of fabricating a liquid ejector having a filter feature. [Figure 8B] FIG. 8B is a schematic cross-sectional view illustrating a method of fabricating a liquid ejector having filter features. [Figure 8C] FIG. 8C is a schematic cross-sectional view illustrating a method of fabricating a liquid ejector having filter features. [Figure 8D] FIG. 8D is a schematic cross-sectional view illustrating a method of fabricating a liquid ejector having filter features. [Figure 8E] FIG. 8E is a schematic cross-sectional view illustrating a method of fabricating a liquid ejector having filter features. [Figure 8F] FIG. 8F is a schematic cross-sectional view illustrating a method of fabricating a liquid ejector having filter features. [Figure 8G] FIG. 8G is a schematic cross-sectional view illustrating a method of fabricating a liquid ejector having filter features. [Figure 9] FIG. 9 is a flowchart of the method illustrated by FIGS. 8A through 8G. [Figure 10] FIG. 10 is a top view of the mask. [Figure 11A] FIG. 11A is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejector having filter features. [Figure 11B] FIG. 11B is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejector having filter features. [Figure 11C]FIG. 11C is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejection device having a filter feature. [Figure 11D] FIG. 11D is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejection device having a filter feature. [Figure 11E] FIG. 11E is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejector having filter features. [Figure 11F] FIG. 11F is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejector having filter features. [Figure 11G] FIG. 11G is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejector having filter features. [Figure 12] FIG. 12 is a flowchart of the method illustrated by FIGS. 11A through 11G. [Figure 13A] FIG. 13A is a schematic cross-sectional view illustrating a method of fabricating an embodiment of a liquid ejector having impedance features. [Figure 13B] FIG. 13B is a schematic cross-sectional view illustrating a method of fabricating an embodiment of a liquid ejector having impedance features. [Figure 13C] FIG. 13C is a schematic cross-sectional view illustrating a method of fabricating an embodiment of a liquid ejector having impedance features. [Figure 13D] FIG. 13D is a schematic cross-sectional view illustrating a method of fabricating an embodiment of a liquid ejector having impedance features. [Figure 13E] FIG. 13E is a schematic cross-sectional view illustrating a method of fabricating an embodiment of a liquid ejector having impedance features. [Figure 14A] FIG. 14A is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejector having impedance features. [Figure 14B] FIG. 14B is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejector having impedance features. [Figure 14C]FIG. 14C is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejector having impedance features. [Figure 14D] FIG. 14D is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejector having impedance features. [Figure 14E] FIG. 14E is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejector having impedance features. [Figure 14F] FIG. 14F is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejector having impedance features. [Figure 14G] FIG. 14G is a schematic cross-sectional view illustrating a method of fabricating another embodiment of a liquid ejector having impedance features. [Figure 15] FIG. 15 is a flowchart of the method illustrated by FIGS. 14A through 14G. [Figure 16A] FIG. 16A is a schematic cross-sectional view illustrating a method of fabricating yet another embodiment of a liquid ejector having impedance features. [Figure 16B] FIG. 16B is a schematic cross-sectional view illustrating a method of fabricating yet another embodiment of a liquid ejector having impedance features. [Figure 16C] FIG. 16C is a schematic cross-sectional view illustrating a method of fabricating yet another embodiment of a liquid ejector having impedance features. [Figure 17A] FIG. 17A is a schematic cross-sectional view showing a further implementation (in construction) of a liquid ejector having impedance features. [Figure 17B] FIG. 17B is a schematic cross-sectional view showing a further implementation (in construction) of a liquid ejector having impedance features. [Figure 18A] FIG. 18A is a schematic cross-sectional view illustrating a method of fabricating yet another embodiment of a liquid ejector having impedance features. [Figure 18B] FIG. 18B is a schematic cross-sectional view illustrating a method of fabricating yet another embodiment of a liquid ejector having impedance features. [Figure 18C] FIG. 18C is a schematic cross-sectional view illustrating a method of fabricating yet another embodiment of a liquid ejector having impedance features. [Figure 18D] FIG. 18D is a schematic cross-sectional view illustrating a method of fabricating yet another embodiment of a liquid ejector having impedance features. [Figure 18E] FIG. 18E is a schematic cross-sectional view illustrating a method of fabricating yet another embodiment of a liquid ejector having impedance features. [Figure 18F] FIG. 18F is a schematic cross-sectional view illustrating a method of fabricating yet another embodiment of a liquid ejector having impedance features. [Figure 18G] FIG. 18G is a schematic cross-sectional view illustrating a method of fabricating yet another embodiment of a liquid ejector having impedance features. [Figure 18H] FIG. 18H is a schematic cross-sectional view illustrating a method of fabricating yet another embodiment of a liquid ejector having impedance features.

[0033] Like reference numbers and designations in the various drawings indicate like elements. DETAILED DESCRIPTION OF THE INVENTION

[0034] Referring to FIG. 1 , a print head 100 can be used to eject droplets of a fluid, such as ink, a biological fluid, a polymer, a liquid for forming electronic components, or other types of liquid, onto a surface. The print head 100 can include a housing 130 that provides a chamber for holding the fluid, a substrate 110 having nozzles and actuators for ejecting the fluid from the nozzles, and an interposer 120 that transports the fluid from the chamber to the substrate 110. While one implementation of the housing and interposer for the print head is described below, other configurations for the print head are possible, and in fact, the housing and interposer are optional. For example, flexible tubing could connect inlets and outlets on the top surface of the substrate 110 to a liquid reservoir.

[0035] The housing 130 has an interior volume divided into a liquid supply chamber 132 and a liquid return chamber 136 by, for example, a partition 134 .

[0036] The bottom of the liquid supply chamber 132 and the liquid return chamber 136 may be defined by the top surface of the interposer assembly 120. The interposer assembly 120 may be attached to the housing 130, such as on the bottom surface of the housing 130, such as by bonding, friction, or other attachment mechanisms. The interposer assembly may include an upper interposer 122 and a lower interposer 124 disposed between the upper interposer 122 and the substrate 110. In some implementations, the interposer assembly consists of a single interposer body.

[0037] The passages formed in the interposer assembly 120 and the substrate 110 define a flow path 400 for fluid flow. The interposer assembly 120 includes a liquid supply inlet opening 402 and a liquid return outlet opening 408. For example, the liquid supply inlet opening 402 and the liquid return outlet opening 408 can be formed as apertures in the upper interposer 122. Fluid can flow along the flow path 400 from the supply chamber 132, through the fluid supply inlet 402, to one or more liquid ejectors 150 (described in more detail below) in the substrate 110. The actuators 30 in the liquid ejectors 150 can eject a portion of the liquid through the nozzles 22. The remaining liquid that is not ejected can flow from the one or more liquid ejectors 150 in the substrate 110 along the flow path 400, through the liquid return outlet opening 408, to the return chamber 136.

[0038] 1, a single flow path 400 is shown as a straight passage for illustrative purposes, however, the print head 100 may have multiple flow paths 400, and the flow paths 400 may be somewhat more geometrically complex, e.g., the flow paths need not be straight.

[0039] 2 and 3A-3D, the substrate 110 may include a body 10 in which various passages of the fluid path, such as pumping chambers, are formed, a nozzle layer 11 in which the nozzles 22 are formed, and an actuator 30 for the liquid ejection device 150. The substrate 110 may be formed by a semiconductor chip fabrication process.

[0040] The passage through the substrate 110 defines a flow path 400 for fluid to pass through the substrate 110. In particular, the substrate inlet 12 receives fluid, for example, from a supply chamber 132 via a liquid supply inlet 402 in the interposer assembly. The substrate inlet 12 extends through the membrane layer 66 (described in more detail below) and supplies the fluid to one or more input feed channels 14, also referred to as supply channels. Each input feed channel 14 supplies fluid to multiple liquid ejectors 150 through corresponding input passages (not shown). The fluid can be selectively ejected from the nozzles 22 of each liquid ejector 150 onto a surface. For simplicity, only one liquid ejector 150 is shown in FIGS. 2 and 3A-3D. Possible locations of descenders for other liquid ejectors are indicated by dotted lines in FIG. 2.

[0041] The body 10 may be a monolithic body, for example a monolithic semiconductor body such as a silicon substrate. For example, the body 10 may be single crystal silicon.

[0042] Each liquid ejector includes a nozzle 22 formed in a nozzle layer 11 disposed on the bottom surface of a substrate 110. In some implementations, the nozzle layer 11 is an integral part of the substrate 110, e.g., the nozzle layer 11 is formed of the same material and crystalline structure as the body 10, such as single crystal silicon. In some implementations, the nozzle layer 11 is a layer of a different material, such as silicon oxide, deposited on the surface of the body 10 to form the substrate 110. In some implementations, the nozzle layer 11 includes multiple layers, such as a silicon layer and one or more oxide layers.

[0043] Fluid flows through each liquid ejector 150 along an ejector flow path 475. The ejector flow path 475 may include a pumping chamber inlet passage 16, a pumping chamber 18, a descender portion 20, and an outlet passage 26. The pumping chamber inlet passage 16 fluidly connects the pumping chamber 18 to the inlet supply channel 14 and may include an ascender portion extending vertically from the inlet supply channel 14 and a pumping chamber inlet extending horizontally from the ascender portion to the pumping chamber. The descender portion 20 is fluidly connected to a corresponding nozzle 22, for example, at the bottom of the descender portion. The outlet passage 26 connects the descender portion 20 to an outlet supply channel 28, which is fluidly connected to a return channel through a substrate outlet and a fluid supply outlet 408 (see FIG. 1 ). The outlet supply channel 28 is also referred to as a return channel.

[0044] The descender section 20 is fluidly connected to a corresponding nozzle 22, such as at the bottom of the descender section 20. Generally, the nozzle 22 can be considered to be part of the flow path after the intersection of the outlet passage 26 with the descender section.

[0045] 2 and 3A-3D, passages such as substrate inlet 12, input feed channel 14, and output feed channel 28 are shown in the same plane. However, in some implementations (e.g., in the embodiments of FIGS. 4A and 4B), one or more of substrate inlet 12, input feed channel 14, and output feed channel 28 are not in the same plane as other passages.

[0046] 4A and 4B, the substrate 110 includes a plurality of input feed channels 14 formed therein and extending parallel to one another to the plane of the bottom surface 112 (see FIG. 2) of the substrate 110. Each input feed channel 14 is in fluid communication with at least one substrate inlet 12 extending perpendicular to the input feed channel 14, e.g., perpendicular to the plane of the bottom surface 112 of the substrate 110. The substrate 110 also includes a plurality of output feed channels 28 formed therein and extending parallel to one another to the plane of the bottom surface 112 of the substrate 110. Each output feed channel 28 is in fluid communication with at least one substrate outlet (not shown) extending perpendicular to the output feed channel 28, e.g., perpendicular to the plane of the bottom surface 112 of the substrate 110. In some embodiments, the input feed channels 14 and the output feed channels 28 are arranged in alternating rows.

[0047] The outlet supply channel 28 may have a larger cross-sectional area than the outlet passage 26, for example, to accommodate multiple combined outlet supply channels 28. For example, as shown in Figures 3A-3D, the outlet supply channel 28 may have a height (measured perpendicular to surface 11a) that is greater than the height of the outlet passage 26. Similarly, as shown in Figure 4B, the outlet supply channel 28 may have a width (measured parallel to surface 11a) that is greater than the width of the outlet passage 26.

[0048] 4A and 4B, the substrate includes a plurality of liquid ejectors 150. Fluid flows through each liquid ejector 150 along a corresponding ejector flow path 475, which includes a pumping chamber inlet passage 16 (including an ascender portion 16a and a horizontal pumping chamber inlet 16b), a pumping chamber 18, and a descender portion 20. Each ascender portion 16a is fluidly connected to the input feed channel 14. Each ascender portion 16a is also fluidly connected to a corresponding pumping chamber 18 through a pumping chamber inlet 16b. The pumping chamber 18 is fluidly connected to a corresponding descender portion 20, which leads to an associated nozzle 22. Each descender portion 20 is also connected to one of the output feed channels 28 through a corresponding output passage 26. For example, the cross-sectional view of the liquid ejection device of Figures 3A-3D can be taken along line 2-2 of Figure 4A.

[0049] In some embodiments, the printhead 100 includes a plurality of nozzles 22 arranged in parallel rows 23 (see FIG. 4B). All of the nozzles 22 in a given row 23 may be fluidly connected to the same input supply channel 14 and the same output channel 28. That is, for example, all of the ascender sections 16 in a given row may be connected to the same input supply channel 14, and all of the descender sections 20 in a given row may be connected to the same output supply channel 28.

[0050] In some implementations, all of the nozzles 22 in adjacent rows may be fluidly connected to the same inlet supply channel 14 or the same outlet supply channel 28, but not both. For example, in the example of Figure 4A, each nozzle 22 in row 23a is fluidly connected to an inlet supply channel 14a and an outlet supply channel 28a. Each nozzle 22 in adjacent row 23b is also connected to an inlet supply channel 14a, but to an outlet supply channel 28b.

[0051] In some implementations, rows of nozzles 22 can be connected in an alternating pattern to the same inlet feed channel 14 or the same outlet feed channel 28. In some implementations, rows of nozzles 22 can be connected in an alternating pattern to the same inlet feed channel 14 or the same outlet feed channel 28. In some implementations, the walls 14a of the inlet feed channels 14 have a jagged shape, for example, forming a scalloped, wavy, or zigzag pattern, to disrupt crosstalk. Further details of the printhead 100 can be found in U.S. Pat. No. 7,566,118, which is incorporated herein by reference in its entirety.

[0052] 2, each liquid ejection device 150 includes a corresponding actuator 30, such as a piezoelectric transducer or a resistive heater. The pumping chamber 18 of each liquid ejection device 150 is proximate to a corresponding actuator 30. Each actuator 30 can be selectively actuated to pressurize the corresponding pumping chamber 18, resulting in the ejection of liquid from a nozzle 22 connected to the pressurized pumping chamber.

[0053] In some embodiments, actuator 30 can include a piezoelectric layer 31, such as a layer of lead zirconate titanate (PZT). Piezoelectric layer 31 can have a thickness of about 50 μm or less, such as about 1 μm to about 25 μm, such as about 2 μm to about 5 μm. In the embodiment of FIG. 2, piezoelectric layer 31 is continuous. In some embodiments, piezoelectric layer 31 can be made discontinuous, such as by an etching or cutting process during fabrication. Discontinuous piezoelectric layer 31 can cover at least pumping chamber 18, but not the entire body 10.

[0054] The piezoelectric layer 31 is sandwiched between a drive electrode 64 and a ground electrode 65. The drive electrode 64 and ground electrode 65 can be metal, such as copper, gold, tungsten, titanium, platinum, or a combination of metals, or other conductive materials, such as indium tin oxide (ITO). The drive electrode 64 and ground electrode 65 can have a thickness of, for example, about 2 μm or less, such as about 0.5 μm.

[0055] The membrane 66 is disposed between the actuator 30 and the pumping chamber 18 and separates the actuator 30, e.g., the ground electrode 65, from the fluid in the pumping chamber 18. In some implementations, the membrane 66 is a layer separate from the body 10, e.g., a layer of silicon oxide. In some implementations, the membrane is integral with the body 10; e.g., the nozzle layer 11 is formed of the same material and crystalline structure as the body 10, e.g., single-crystal silicon. In some implementations, two or more of the substrate 110, the nozzle layer 11, and the membrane 66 may be formed as a unitary body. In some implementations, the actuator 30 does not include the membrane 66, and the ground electrode 65 is formed on the back side of the piezoelectric layer 31, such that the ground electrode 65 is directly exposed to the fluid in the pumping chamber 18.

[0056] To operate the piezoelectric actuator 30, a voltage can be applied between the drive electrode 64 and the ground electrode 65, thereby applying a voltage to the piezoelectric layer 31. The applied voltage causes the piezoelectric layer 31 to deflect, which in turn deflects the membrane 66. The deflection of the membrane 66 changes the volume of the pumping chamber 18, which generates a pressure pulse (also called an ejection pulse) in the pumping chamber 18. The pressure pulse propagates down the descender portion 20 to the corresponding nozzle 22, resulting in the ejection of a droplet from the nozzle 22.

[0057] Membrane 66 may be a single layer of silicon (e.g., single crystal silicon), another semiconductor material, or one or more layers of an oxide, such as aluminum oxide (AlO), zirconium oxide (ZrO), or silicon oxide (SiO), aluminum nitride, silicon carbide, or other material. For example, membrane 66 may be formed of a compliant, inert material such that actuation of actuator 30 causes membrane 66 to bend sufficiently to eject a droplet.

[0058] In some implementations, membrane 66 may be secured to actuator 30 by adhesive layer 67. In some implementations, the layers of actuator 30 are deposited directly onto membrane 66.

[0059] When liquid is ejected from a nozzle 22 of a liquid ejection device 150, the nozzle 22 may become at least partially depleted of liquid. Fluid circulation through the inlet supply channel 14 and the outlet supply channel 28 (sometimes collectively referred to as supply channels) can provide liquid to refill the depleted nozzle 22. Without being limited to any particular theory, liquid may flow through the outlet passage 26 to the outlet supply channel 28 during droplet ejection, but it is also possible to flow liquid back through the outlet passage 26 to the nozzle 22 when the nozzle 22 is depleted after ejection to refill the nozzle 22.

[0060] If the depleted nozzle 22 can be quickly refilled after ejection, the nozzle can be prepared for a subsequent ejection more quickly, thus improving the response time of the liquid ejection device 150. For example, the rate at which the nozzle 22 can be refilled can be increased by increasing the cross-sectional area of one or more fluid flow paths supplying liquid to the nozzle 22, such as the descender portion 20, the outlet passage 26, or another fluid flow path. However, having a large fluid flow path to supply liquid to the nozzle 22 can sometimes make it difficult to achieve a sufficiently high pressure at the nozzle opening 24 for efficient liquid ejection (sometimes referred to as jetting). Conversely, a smaller fluid flow path to supply liquid to the nozzle 22 may make it easier to achieve sufficient pressure for efficient jetting, but may also limit the rate at which the nozzle 22 can be refilled.

[0061] 3A, 5A, and 5B, in some cases, to achieve both rapid nozzle refill and sufficiently high nozzle pressure during jetting, an impedance structure 310, such as a membrane 300, can be placed in the fluid flow path near the nozzle. The membrane 300 can have one or more holes 302 through its thickness. The membrane 300 is positioned in the flow path such that the fluid flows through the holes 302 in the membrane 300.

[0062] In the embodiment of Figure 3A, membrane 300 is disposed in outlet passage 26 to provide impedance structure 310. In this embodiment, outlet passage 26 includes upper portion 32a of membrane 300 and lower portion 32b of membrane 300. In the embodiment of Figure 3B, impedance structure 310 includes membrane 300 disposed between outlet passage 26 and return channel 28. In this case, the membrane may form the bottom surface of return channel 28; for example, the top surface of membrane 300 may be flush with the bottom surface of return channel 28.

[0063] However, membranes 300 may be alternately positioned at other locations in the inlet flow path, outlet flow path, or both, as well as serving other functions.

[0064] 3C, 5A, and 5B, a filter feature 320 can optionally be placed in the fluid flow path near the nozzle to prevent contaminants from reaching the nozzle or being expelled from the nozzle. The filter feature 320 can be provided by a membrane 300 having one or more holes 302 through the thickness of the membrane.

[0065] As shown in Figure 3C, a membrane 300 may be positioned across the nozzle 22 after the intersection between the descender portion 20 and the outlet passage 26 (i.e., closer to the nozzle opening 24 than the intersection). For example, the membrane 300 may be positioned immediately after the intersection, e.g., the top surface of the membrane may be flush with the bottom surface of the outlet passage 26. As shown in Figure 3D, the membrane 300 may be positioned across the descender portion 20 before the intersection between the descender portion 20 and the outlet passage 26 (i.e., further from the nozzle opening 24 than the intersection). For example, the membrane may be positioned immediately before the intersection, e.g., the bottom surface of the membrane may be flush with the top surface of the outlet passage 26.

[0066] 3A to 3D, the membrane 300 lies in a plane parallel to the surface 11a of the nozzle layer 11. The holes may therefore extend perpendicular to the surface 11a of the nozzle layer 11.

[0067] Referring again to FIGS. 3A and 3B and 5A and 5B, the membrane 300 can be configured as an impedance structure 310 to introduce a fluid impedance into a flow path in which the impedance membrane is disposed, such as the fluid flow path between the descender section and the return channel. The value of the fluid impedance introduced by the impedance membrane 300 can be frequency-dependent. For example, the fluid in the flow path may experience oscillations. The impedance membrane can introduce a higher fluid impedance at or around a particular frequency of fluid oscillation than at other frequencies of fluid oscillation. For example, the impedance membrane 300 can provide a high impedance at or around a jet resonant frequency, which is the frequency at which the nozzle 22 has high fluid flow during jetting. In some implementations of the liquid ejector 150, the jet resonant frequency is between approximately 40 kHz and 10 MHz. In some implementations, the impedance is approximately 20 dB, or 10 times higher.

[0068] Thus, at or near the jet resonant frequency (e.g., when the nozzle 22 is ejecting liquid), the impedance membrane 300 introduces a sufficiently high fluid impedance into the fluid flow path near the nozzle 22 to induce and pressurize the fluid flow through the nozzle, thereby providing efficient jetting. At other frequencies (e.g., frequencies not at or near the jet resonant frequency, such as when the nozzle 22 is not ejecting liquid), the impedance membrane introduces a low fluid impedance, thereby allowing for rapid refilling of a depleted nozzle.

[0069] To achieve high fluid impedance at certain frequencies (e.g., at or around the jet resonance frequency) and low fluid impedance at other frequencies, the impedance membrane 300 can act as a capacitor in parallel with an inductor along the fluid flow path. For example, the membrane 300 itself can be a compliant membrane that acts as a capacitive element in the fluid flow path, and the holes 302 act as inductor elements. In this case, when the volume on one side of the membrane is pressurized, the membrane will move and, as a result, there will be some viscous resistance. However, without being limited to any particular theory, the impedance effect due to the holes may be dominant.

[0070] In some cases, the compliance of membrane 300 may also provide resistance that may help to dampen oscillations of the fluid flow path, for example, as described below.

[0071] As a filter feature 320, the membrane 300 can also function as a filter to prevent foreign objects, such as impurities in the fluid, from reaching and clogging the nozzles 22. For example, the membrane 300 shown in Figures 3C and 3D may function primarily as a filter rather than adjusting fluid impedance to affect the rate at which a depleted nozzle is refilled.

[0072] Membrane 300 can be formed of a material that is compatible with fabrication processes (e.g., microelectromechanical systems (MEMS) fabrication processes, etc.) used to fabricate other components of liquid ejector 150. For example, membrane 300 can optionally be formed of an oxide (e.g., SiO), a nitride (e.g., SiN), or another insulating material. Optionally, membrane 300 can be formed of silicon. Optionally, membrane 300 can be formed of a metal, such as a sputtered metal layer. Optionally, membrane 300 can be formed of a relatively soft, compliant material, such as a polyimide or polymer (e.g., poly(methyl methacrylate) (PMMA), polydimethylsiloxane (PDMS), or another polymer). Optionally, membrane 300 can be formed of a material that is more flexible or softer than the material forming the walls of the fluid flow paths, such as a material having a lower modulus of elasticity than the material forming the walls of the fluid flow paths. In some cases, the thickness of the membrane 300 can make the membrane 300 more flexible than the walls of the fluid flow path.

[0073] Generally, when functioning as an impedance feature, membrane 300 may be thin enough to allow it to flex slightly to function as a capacitive element in the fluid flow path. Membrane 300 is also thick enough to withstand expected pressure fluctuations or fluid flow oscillations. The thickness t of impedance membrane 300 appropriate to provide this functionality is i varies depending on the properties of the membrane material, for example, the elastic modulus of the membrane material.

[0074] As either a filter feature or an impedance feature, a membrane 300 formed of SiO2 can have a thickness of between about 0.5 μm and about 5 μm, e.g., about 1 μm, about 2 μm, or about 3 μm. A membrane 300 formed of a compliant polymer can have a thickness of between about 10 μm and about 30 μm, e.g., about 20 μm, about 25 μm, or about 30 μm, depending, for example, on the modulus of the polymer. The size of the membrane 300 is determined by the size of the flow channel in which it will be placed, e.g., the lateral dimension of the membrane corresponds to the cross-sectional width or depth of the flow channel.

[0075] The characteristics of the holes 302 in the membrane 300, such as the number, size, shape, and / or arrangement of the holes 302, can be selected to maximize the impedance of the flow path provided by the membrane 300 at a desired frequency (e.g., at or around the jet resonant frequency). For example, the impedance membrane 300 may have between 1 and 10 holes 302, such as two holes, four holes, six holes, eight holes, or another number of holes. The holes 302 may have a lateral dimension (e.g., radius r) of between about 1 μm and about 10 μm, such as about 2 μm, 4 μm, 6 μm, or 8 μm. The holes 302 may be circular, oval, elliptical, or other shapes. For example, the holes 302 may be shaped without sharp corners that could concentrate mechanical stress. The holes 302 may be arranged in a regular pattern, such as a rectangular or hexagonal array, or may be randomly distributed.

[0076] In some cases, when the actuator 30 of one of the liquid ejectors 150 is actuated, pressure fluctuations may propagate through the ascender portion 16 of the liquid ejector 150 to the inlet feed channel 14. Similarly, energy from the pressure fluctuations may propagate through the descender portion 20 and outlet passage 26 of the liquid ejector 150 to the outlet feed channel 28. In some cases, the inlet feed channel 14 and the outlet feed channel 28 are generally referred to as feed channels 14, 28 in this application. As a result, pressure fluctuations may occur in one or more of the feed channels 14, 28 connected to the actuated liquid ejector 150. In some cases, these pressure fluctuations may propagate into the ejector flow paths 475 of other liquid ejectors 150 connected to the same feed channel 14, 28. These pressure fluctuations may adversely affect the drop volume and / or drop velocity of droplets ejected from those liquid ejectors 150, resulting in reduced print quality. For example, variations in drop volume can change the amount of ejected liquid, and variations in drop velocity can change the location where an ejected drop is deposited on the printing surface. Inducing pressure variations in a liquid ejection device is also referred to as fluidic crosstalk.

[0077] Fluidic crosstalk can be reduced by providing liquid ejectors with greater compliance, thereby damping pressure fluctuations. Increasing the available compliance at the liquid ejectors can damp the energy from pressure fluctuations occurring at one of the liquid ejectors, thereby reducing the impact of pressure fluctuations on adjacent liquid ejectors.

[0078] 6, compliance can be imparted to the inlet feed channel 14, the outlet feed channel 28, or both, by forming a compliant microstructure 50 on one or more surfaces of the inlet feed channel 14 and / or the outlet feed channel 28. The compliant microstructure 50 can be, for example, a membrane laid across a recess, and thus can deflect in response to pressure fluctuations.

[0079] For example, in the embodiment of Figure 6, the compliant microstructures 50 are formed on the bottom surface 52 of the inlet feed channel 14 and the bottom surface 54 of the outlet feed channel. In this embodiment, the bottom surfaces 52, 54 are provided by the top surface of the nozzle layer 11. In some embodiments, the compliant microstructures 50 can be formed on the top surface of the feed channels 14, 28 or on the sidewalls of the feed channels 14, 28. The additional compliance provided by the compliant microstructures 50 in the feed channels 14, 28 attenuates energy from pressure fluctuations in a particular liquid ejector 150 connected to that feed channel 14, 28. As a result, the effect of those pressure fluctuations on other liquid ejectors 150 connected to the same feed channel 14, 28 can be reduced.

[0080] 7A and 7B, in some embodiments, the compliant microstructures 50 formed in the nozzle layer 11 of the inlet feed channel 14 and / or outlet feed channel 28 may be depressions 506 in the nozzle layer 11 covered by a membrane 502 to provide the cavity 500. In some implementations, the membrane 502 is provided by the same layer that provides the membrane 300.

[0081] The membrane 502 is positioned over the recess 506 so that the inner surface 504 of the nozzle layer 11 facing the feed channels 14, 28 is substantially flat. In some cases, the membrane 502 may flex slightly into the cavity 500, for example, when a vacuum is present in the cavity 500.

[0082] Optionally, the recess 506 can be formed in the nozzle layer 11, also referred to as the bottom wall of the inlet feed channel 14 or outlet feed channel 28. Optionally, the recess 506 can be formed in the top wall of the inlet feed channel or outlet feed channel, which is the wall opposite the bottom wall. Optionally, the recess 506 can be formed in one or more side walls of the inlet feed channel 14 or outlet feed channel 28, where the side wall is the wall that intersects the top and bottom walls.

[0083] Without being limited to any particular theory, it is believed that when pressure fluctuations propagate into the feed channels 14, 28, the membrane 502 can deflect in or out of the recesses 506, thereby dampening the pressure fluctuations and mitigating fluidic crosstalk between adjacent liquid ejectors 150 connected to that feed channel 14, 28. The deflection of the membrane 502 is reversible, such that the membrane 502 returns to its original configuration when the fluid pressure in the feed channels 14, 28 decreases. Further details regarding these compliant microstructures 50 can be found in U.S. Patent Application No. 14 / 695,525, the contents of which are incorporated herein by reference in their entirety.

[0084] 8A-8G show an exemplary approach to fabricating the body 10 and nozzle layer 11 of the substrate 110. In this embodiment, the substrate is fabricated to have a liquid ejector 150 with a membrane 300 in the liquid flow path prior to the intersection between the outlet passage 26 and the descender portion 20. The membrane 300 may provide a filter 320. Additionally, the substrate may be fabricated to have a compliant microstructure that includes one or more cavities 500 formed in the nozzle layer 11.

[0085] Liquid ejector 150 having only membrane 300 or only cavity 500 can be fabricated following a similar approach. For example, to fabricate a liquid ejector without cavity 500, one can simply omit the portion of the process associated with forming recess 506 shown in FIG. 8B.

[0086] In this embodiment, the substrate is fabricated with a liquid ejector 150 having a membrane 300 in the liquid flow path prior to the intersection between the outlet passage 26 and the descender portion. Additionally, the substrate can be fabricated with one or more cavities 500 formed in the nozzle layer 11 to provide a compliant microstructure.

[0087] 8A and 9, a first wafer 80 (e.g., a silicon wafer or a silicon-on-insulator (SOI) wafer, etc.) provides a nozzle wafer. The first wafer 80 includes a mask layer 81 (e.g., an oxide or nitride mask layer, such as SiO2 or Si3N4), a device layer 82 (e.g., a silicon device layer 82), an etch stop layer 84 (e.g., an oxide or nitride etch stop layer), and a handle layer 85 (e.g., a silicon handle layer). In some embodiments, the first wafer 80 does not include the etch stop layer 84. In some embodiments, for example, when the first wafer 80 is an SOI wafer, the insulating layer of the SOI wafer 80 functions as the etch stop layer 84.

[0088] To define nozzle locations, the mask layer 81 is patterned, and openings that will provide the nozzles 22 of the liquid ejector 150 are formed through the device layer 82 (step 900), such as using standard microfabrication techniques, including, for example, lithography and etching. For example, a first layer of resist may be deposited on the unpatterned mask layer 81 and patterned by lithography. The mask layer 81 may be etched to form openings therethrough. The device layer 82 may then be etched using the mask layer 81 as a mask, such as by deep reactive ion etching (DRIE), potassium hydroxide (KOH) etching, or another type of etch, to form the nozzles 22. The resist may be stripped before or after etching the device layer 82.

[0089] 8B and 9, second wafer 86 (e.g., a silicon wafer or an SOI wafer) includes a mask layer 87 (e.g., an oxide or nitride mask layer), a device layer 88 (e.g., a silicon device layer 88), an etch stop layer 90 (e.g., an oxide or nitride etch stop layer 90), and a handle layer 92 (e.g., a silicon handle layer 92). The device layer 88 of second wafer 86 can be formed of the same material as the device layer 82 of first wafer 80. In some embodiments, for example, when second wafer 86 is an SOI wafer, an insulating layer of the SOI wafer 86 functions as the etch stop layer 90.

[0090] The mask layer 87 is patterned to define the recess 506, and the recess 506 is formed in the device layer 88 of the second wafer 86 (step 902), using standard microfabrication techniques including, for example, lithography and etching. For example, a layer of resist may be deposited on the unpatterned mask layer 87 and patterned by lithography. The mask layer 87 may be etched to form an opening through the mask layer 87. The device layer 88 may then be etched using the mask layer 87 as a mask. While FIG. 8B shows the recess 506 as extending completely through the device layer 88, this is not necessary; the recess 506 may extend only partially through the device layer 88.

[0091] 8C and 9, second wafer 86 is bonded to first wafer 80 (step 904), such as using a thermal bond or another wafer bonding technique, to form assembly 96. In particular, second wafer 86 is bonded to first wafer 80 such that the mask layer side of first wafer 80 contacts the mask layer side of second wafer 86. Opening 200 may be aligned with the opening that provides nozzle 22. Thus, mask layer 81 may be bonded to mask layer 87. In some implementations, mask layer 81 and / or mask layer 87 are removed before second wafer 86 is bonded to first wafer 80.

[0092] Etch stop layer 90 covers recess 506. Thus, etch stop layer 90 can provide membrane 502 and define cavity 500. Although only one recess 506 is shown in FIG. 8B, multiple recesses may be present to form multiple cavities. Furthermore, although cavity 500 shown in FIGS. 8F and 8G is shown below return channel 28, a similar cavity can additionally or alternatively be formed below supply channel 24 by forming a recess in an appropriate location.

[0093] Similarly, an opening 200 is formed through mask layer 87 and device layer 88 to provide a portion of descender portion 20, such as using standard microfabrication techniques including, for example, lithography and etching.

[0094] 8D and 9, the handle layer 92 of the second wafer 86 is removed (step 906), such as by grinding and polishing, wet etching, plasma etching, or other removal process.

[0095] 8E and 9, holes 302 are etched through the etch stop layer 90 to form a membrane 300, for example for a filtering structure 320, which is located near the nozzle 22 and in the flow path of the fluid to the nozzle (see FIG. 3B) (step 908).

[0096] 8A-8E, device layer 82, mask layers 81, 87 (if present), and device layer 88 may together form nozzle layer 11. The approach of Figures 8A-8E provides a thick, robust nozzle layer 11 that is not thinned by the fabrication of membrane 300.

[0097] The resulting assembly 96 with the recess 500, membrane 300, or both formed can be further processed (step 910) to form the printhead liquid ejector 150, for example, as described below and in U.S. Pat. No. 7,566,118, the contents of which are incorporated herein by reference in their entirety.

[0098] 8F and 8G, the top surface 74 of the assembly 96, such as the exposed surface of the etch stop layer 90, may be bonded (960) to the flow channel wafer 76. For example, the top surface 74 of the first wafer 60 may be bonded to the flow channel wafer 76 using low temperature bonding, such as bonding with an epoxy (e.g., benzocyclobutene (BCB)), or using low temperature plasma activated bonding.

[0099] The flow path wafer 76 can be fabricated prior to bonding to include flow paths 475, such as supply channels 14, chamber inlet passages 16, pumping chambers 18, descender sections 20, outlet passages 26, and outlet supply channels 28. Other elements, such as actuators (not shown), can be formed before or after the assembly 96 is bonded to the flow path wafer 76.

[0100] 8G, after bonding, the handle layer 85 and the etch stop layer 84 can be removed, such as by grinding and polishing, wet etching, plasma etching, or other removal process, to expose the nozzle 22. In some implementations, the etch stop layer 84 is not removed, but an aperture is formed through the etch stop layer 84 to complete the nozzle. After the actuator is formed or attached, the resulting substrate generally corresponds to the substrate 110 shown in FIG. 3C.

[0101] As shown in Figure 8G, the same layer 90 may provide membrane 502 for the compliant microstructure (if present) and membrane 300. As further shown in Figure 8G, with outlet passage 26 formed as a recess in the bottom of channel wafer 76, top surface 74 of first and second wafer assembly 96 may provide the lower surface of outlet passage 26. Furthermore, the upper surface of membrane 300 may be flush with the lower surface of outlet passage 26.

[0102] 11A-11G show another exemplary approach to fabricating the body 10 and nozzle layer 11 of the substrate 110. In this embodiment, the substrate is fabricated to include a liquid ejector 150 having a membrane 300 in the liquid flow path prior to the intersection between the outlet passage 26 and the descender portion 20. The membrane 300 may provide a filter 320.

[0103] Additionally, the substrate can be fabricated with one or more cavities 500 formed in the nozzle layer 11 to provide a compliant microstructure. A liquid ejector 150 having only a membrane 300 or only a cavity 500 can be fabricated following a similar approach. For example, to fabricate a liquid ejector without a cavity 500, one can simply start with a substrate as shown in FIG. 11A, but without the recess 506.

[0104] 11A and 12 , a first wafer 80 (e.g., a silicon wafer or an SOI wafer) includes a mask layer 81 (e.g., an oxide or nitride mask layer), a device layer 82 (e.g., a silicon nozzle layer 11), an etch stop layer 84 (e.g., an oxide or nitride etch stop layer), and a handle layer 85 (e.g., a silicon handle layer). The first wafer 80 may also be referred to as a nozzle wafer. In some embodiments, the first wafer 80 does not include the etch stop layer 84. In some embodiments, for example, when the first wafer 80 is an SOI wafer, an insulating layer of the SOI wafer functions as the etch stop layer 84.

[0105] To define nozzle locations, the mask layer 81 is patterned, and openings that will provide the nozzles 22 of the liquid ejector 150 are formed through the device layer 82 (step 920), such as using standard microfabrication techniques including, for example, lithography and etching. For example, a first layer of resist may be deposited on the unpatterned mask layer 81 and patterned by lithography. The mask layer 81 may be etched to form openings through the mask layer 81. The device layer 82 may then be etched using the mask layer 81 as a mask, such as by deep reactive ion etching (DRIE), potassium hydroxide (KOH) etching, or another type of etch, to form the nozzles 22. The first layer of resist may be stripped.

[0106] Optionally, recesses 506 extending partially but not completely through device layer 82 are also formed (step 922), such as using standard micro-fabrication techniques. To form recesses 506, a second layer of resist may be deposited over mask layer 81 and lithographically patterned. Mask layer 81 and device layer 82 may be etched according to the patterned resist, such as using wet or dry etching, to form recesses 506.

[0107] 11B and 12, a second wafer 86 (e.g., a silicon wafer or an SOI wafer) has a handle layer 92, an etch stop layer 90 (e.g., an oxide or nitride etch stop layer), and a device layer 88. In some embodiments, for example, when second wafer 86 is an SOI wafer, an insulating layer of the SOI wafer 86 functions as the etch stop layer 90.

[0108] To provide a portion of descender portion 20, an opening 200 is formed through mask layer 87 and device layer 88, such as using standard microfabrication techniques including lithography and etching. To define opening 200, mask layer 87 is patterned, and opening 200 is formed in device layer 88 of second wafer 86, such as using standard microfabrication techniques including lithography and etching. For example, a layer of resist may be deposited on unpatterned mask layer 87 and patterned by lithography. Mask layer 87 may be etched to form an opening through mask layer 87. Device layer 88 may then be etched using mask layer 87 as a mask.

[0109] An opening 510 may be formed through the mask layer 87 and the device layer 88 by a similar or identical process to provide a portion of the return channel 28 (step 924).

[0110] Additionally, recessed area 202 may be formed in the upper surface of device layer 88 between opening 200 and opening 510 to provide outlet passageway 26 (step 924). Recessed area 202 may extend partially into, but not through, device layer 88, thereby leaving a portion 88a of device layer 88 below recessed area 202. As a result, openings 200 and 510 may be deeper than recessed area 202. Alternatively, recessed area 202 may extend entirely through device layer 88.

[0111] 11C and 12, second wafer 86 is bonded to first wafer 80 (step 926), such as using thermal bonding or another wafer bonding technique, to form assembly 96. In particular, second wafer 86 is bonded to first wafer 80 such that the mask layer side of first wafer 80 contacts the mask layer side of second wafer 86. Opening 200 may be aligned with the opening that provides nozzle 22. Thus, mask layer 81 may be bonded to mask layer 87. In some implementations, mask layer 81 and / or mask layer 87 are removed before second wafer 86 is bonded to first wafer 80.

[0112] A recessed area 202 with a passageway formed therein between the top of the second wafer 86 and a portion 88 a of the device layer 88 provides the outlet passageway 26 .

[0113] The etch stop layer 90 covers the recess 506. Thus, the etch stop layer 90 can provide a membrane 502 and define the cavity 500. Although only one recess 506 is shown in FIG. 11B, multiple recesses may be present to form multiple cavities 500. Furthermore, although the cavity 500 shown in FIGS. 11F and 11G is shown below the return channel 28, a similar cavity can additionally or alternatively be formed below the supply channel 24 by forming a recess in an appropriate location.

[0114] 11D and 12, the handle layer 92 of the second wafer 86 is removed (step 928), such as by grinding and polishing, wet etching, plasma etching, or other removal process, thereby leaving behind the etch stop layer 90 and the device layer 88.

[0115] 11E and 12, a hole 302 is etched through the etch stop layer 90 (step 930). As a result, the portion of the etch stop layer 90 with the hole 302 forms a filter feature near the nozzle 22 and located in the fluid flow path to the nozzle. Additionally, a hole is etched through the etch stop layer 90 above the opening 510. This exposes the opening 510, which will become the lower portion of the return channel 28.

[0116] 11A-11E allows some control over the relative thicknesses of films 300 and 502. That is, films 300 and 502 do not necessarily have to have the same thickness and / or the same composition, and thus the thickness and / or composition of each film can be selected for different purposes.

[0117] The wafer assembly 96 having the nozzles 22, optional recesses 500 formed in the device layer 88, and membranes 300 disposed near the nozzles can be further processed to form the liquid ejectors 150 of the print head 100, for example, as described in U.S. Pat. No. 7,566,118, the contents of which are incorporated herein by reference in their entirety.

[0118] 11F and 12, in some embodiments, the top surface 74 of the assembly 96, such as the exposed surface of the etch stop layer 90, may be bonded to the flow channel wafer 76 (step 932). For example, the top surface 74 of the first wafer 60 may be bonded to the flow channel wafer 76 using low temperature bonding, such as bonding with an epoxy (benzocyclobutene (BCB)), or using low temperature plasma activated bonding.

[0119] The flow path wafer 76 can be fabricated prior to bonding to include portions of the flow path 475, such as the supply channel 14, the chamber inlet passage 16, the pumping chamber 18, a portion of the descender section 20 (the remainder of which is provided by opening 200), and a portion of the outlet supply channel 28 (the remainder of which is provided by opening 510). Other elements, such as actuators (not shown), can be formed before or after the assembly 96 is bonded to the flow path wafer 76.

[0120] 11G and 12, the handle layer 85 may then be removed (step 934), such as by grinding and polishing, wet etching, plasma etching, or other removal process. If an etch stop layer 84 is present, it is either removed (as shown in FIG. 11F) or masked and etched (step 936), such as by standard microfabrication techniques including, for example, lithography and etching, to expose the nozzle.

[0121] 3D, except that the bottom surface of membrane 300 is spaced slightly above (by the thickness of portion 88a) the intersection between descender portion 20 and outlet passage 26. On the other hand, if recess 202 extends all the way through device layer 88, the bottom surface of membrane 300 will be flush with the top surface of outlet passage 26.

[0122] 11A-11G, the outlet passage 26 is provided by a recess 202 in the device layer 88 rather than a recess in the wafer 76. Alternatively, the outlet passage 26 can be provided by a recess in the bottom surface of the channel wafer 76 rather than in the device layer 88. In this case, similar to FIGS. 8F and 8G, the top surface of the etch stop layer 90 provides the bottom surface of the outlet passage 26.

[0123] Figures 13A to 13G show a similar process to Figures 8A to 8G for fabricating the body 10 and nozzle layer 11 of the substrate 110. However, in this example, holes 302 may extend through some or all of the device layer 88. Fabrication may generally proceed as described above for Figures 11A to 11G, except as noted below.

[0124] 13B, rather than creating an aperture 200 through the device layer 88, a recessed area 204 is formed where the nozzle 22 will be located. This recessed area 204 may be the same depth as or deeper than the recessed area 202 that will provide the outlet passage 26. As shown by Figures 13C and 13D, this leaves a thin portion 88b in the device layer 88 that will overlie the nozzle 22 when the first wafer is bonded to the second wafer.

[0125] 13E, after the openings are formed in the etch stop layer 90, the etch stop layer 90 can be used as a mask, and openings can be etched through the thinned portions 88b of the device layer 88, such as by reactive ion etching, until the recesses 204 are exposed. The resulting openings through both the etch stop layer 90 and the thinned portions 88b of the device layer 88 provide holes 302 through the membrane. Fabrication can proceed as shown in FIGS. 11F and 11G. An advantage of this approach is that it allows for selection of the thickness of the membrane 300.

[0126] After the actuators are formed or attached, the resulting substrate generally corresponds to the substrate shown in Figure 3D. If recessed area 204 has the same depth as recessed area 202, the bottom surface of membrane 300 will be flush with the top surface of outlet passage 26.

[0127] 14A-14G illustrate another exemplary approach to fabricating the body 10 and nozzle layer 11 of the substrate 110. In this embodiment, the substrate is fabricated to include a liquid ejection device 150 with a membrane 300 in the outlet passage 26. In particular, the membrane 300 may be provided in the outlet passage 26 at a location spaced apart from both the descender portion 20 and the return channel 28. The membrane may provide an impedance structure 310.

[0128] The substrate may also include a compliant microstructure, including one or more cavities 500 formed in the nozzle layer 11. A liquid ejector 150 having only a membrane 300 can be fabricated following a similar approach. For example, to fabricate a liquid ejector without cavities 500, one can simply omit the portion of the process associated with forming the recesses 506 shown in Figure 14B.

[0129] 14A and 15, a first wafer 80 (e.g., a silicon wafer or a silicon-on-insulator (SOI) wafer, etc.) provides a nozzle wafer. The first wafer 80 includes a mask layer 81 (e.g., an oxide or nitride mask layer, such as SiO2 or Si3N4), a device layer 82 (e.g., a silicon device layer 82), an etch stop layer 84 (e.g., an oxide or nitride etch stop layer), and a handle layer 85 (e.g., a silicon handle layer). In some embodiments, the first wafer 80 does not include the etch stop layer 84. In some embodiments, for example, when the first wafer 80 is an SOI wafer, the insulating layer of the SOI wafer 80 functions as the etch stop layer 84.

[0130] To define nozzle locations, the mask layer 81 is patterned, and openings that will provide the nozzles 22 of the liquid ejector 150 are formed through the device layer 82 (step 940), such as using standard microfabrication techniques, including, for example, lithography and etching. For example, a first layer of resist may be deposited on the unpatterned mask layer 81 and patterned by lithography. The mask layer 81 may be etched to form openings therethrough. The device layer 82 may then be etched using the mask layer 81 as a mask, such as by deep reactive ion etching (DRIE), potassium hydroxide (KOH) etching, or another type of etch, to form the nozzles 22. The resist may be stripped before or after etching the device layer 82.

[0131] 14B and 15 , second wafer 86 (e.g., a silicon wafer or an SOI wafer) includes a mask layer 87 (e.g., an oxide or nitride mask layer), a device layer 88 (e.g., a silicon device layer 88), an etch stop layer 90 (e.g., an oxide or nitride etch stop layer 90), and a handle layer 92 (e.g., a silicon handle layer 92). The device layer 88 of second wafer 86 can be formed of the same material as the device layer 82 of first wafer 80. In some embodiments, for example, when second wafer 86 is an SOI wafer, an insulating layer of the SOI wafer 86 functions as the etch stop layer 90.

[0132] To define cavity 500, mask layer 87 is patterned and recesses 506 are formed in device layer 88 of second wafer 86 (step 942), such as using standard microfabrication techniques including, for example, lithography and etching. Although Figure 14B shows recesses 506 as extending completely through device layer 88, this is not necessary; recesses 506 may extend only partially through device layer 88.

[0133] Using, for example, standard microfabrication techniques including lithography and etching, an opening is formed in mask layer 87, and optionally, a recess 200 is formed at least partially through device layer 88. This recess 200 is positioned below outlet passage 26 and can be thought of as providing part of descender portion 20 or nozzle 22. While Figure 14B shows recess 200 as an opening that extends completely through device layer 88, this is not necessary, and recess 200 may extend only partially through device layer 88.

[0134] Similarly, an opening is formed in mask layer 87 such that recess 208 is formed at least partially through device layer 88 (step 944). This recess provides a portion of outlet passage 26. While Figure 14B shows recess 208 as extending entirely through device layer 88, this is not necessary; recess 208 may extend only partially through device layer 88. However, recess 200 should be at least as deep as recess 208.

[0135] Recess 506 (if present), opening 200, and recess 208 can be formed simultaneously by a single etching step. In this case, recess 510 (if present), opening 200, and recess 208 will all have the same depth. For example, a layer of resist may be deposited on unpatterned mask layer 87 and patterned by lithography. Mask layer 87 can be etched to form openings through mask layer 87. Device layer 88 can then be etched using mask layer 87 as a mask.

[0136] Alternatively, multiple etching steps can be used to provide different depths of recesses 510 (if present), openings 200, and recesses 208. For example, for each feature, a layer of resist can be deposited and lithographically patterned, and then the substrate can be subjected to an etching step (the resist can cover previously defined features to protect them from subsequent etching steps). In some implementations, the photoresist itself can be used as a mask.

[0137] 14C and 15 , second wafer 86 is bonded to first wafer 80 (step 946), such as using thermal bonding or another wafer bonding technique, to form assembly 96. In particular, second wafer 86 is bonded to first wafer 80 such that the mask layer side of first wafer 80 contacts the mask layer side of second wafer 86. Thus, mask layer 81 can be bonded to mask layer 87. In some implementations, mask layer 81 and / or mask layer 87 are removed before second wafer 86 is bonded to first wafer 80. Opening 200 can be aligned with the opening that provides nozzle 22. When this recess 510 is covered by etch stop layer 90, it forms cavity 500.

[0138] The etch stop layer 90 covers the recess 506. Thus, the etch stop layer 90 can provide a membrane 502 and define the cavity 500. Although only one recess 506 is shown in FIG. 14B, multiple recesses may be present to form multiple cavities 500. Furthermore, although the cavity 500 shown in FIGS. 14F and 14G is shown below the return channel 28, a similar cavity can additionally or alternatively be formed below the supply channel 24 by forming a recess in an appropriate location.

[0139] 14D and 15, the handle layer 92 of the second wafer 86 is removed (step 948), such as by grinding and polishing, wet etching, plasma etching, or other removal process.

[0140] 14E and 15, holes 302 are etched through etch stop layer 90 until they reach recesses 208 to form impedance features 310 (step 950). Holes 302 may be formed by an etching process such as wet etching or plasma etching. In particular, holes 302 may be formed by anisotropic etching, such as reactive ion etching.

[0141] Additionally, an aperture 340 may be formed through the etch stop layer 90 up to the recess 208 to provide an opening between the outlet passage 26 and the return channel 28 (step 950).

[0142] Additionally, an aperture 342 may be formed through the etch stop layer 90 up to the recess 200 to provide an opening between the descender portion 20 and the nozzle 22 .

[0143] Opening 302, opening 340, and opening 342 can be formed simultaneously in a single etching step. In particular, the openings can be formed by anisotropic etching, such as reactive ion etching.

[0144] 16A-16C , if recess 208 does not extend completely through device layer 88, a further etching step can be performed, for example, using etch stop layer 90 as a mask. Openings 302 and 340 can be etched through thinned portion 88c of device layer 88 above recess 208, such as by reactive ion etching, until recess 208 is exposed. An advantage of this approach is that it allows for selection of the thickness of membrane 300, such as by selecting the depth of recess 208. The embodiments shown in FIGS. 16A-16C can be combined with various alternatives.

[0145] 14E, if recess 208 extends completely through device layer 88, the portion of etch stop layer 90 that lies across channel 26 provides membrane 300. On the other hand, if recess 208 extends only partially through device layer 88, as in FIG. 16B, the combination of etch stop layer 90 and the thinned portion 88c of device layer 88 provides membrane 300.

[0146] 14A-14E, device layer 82, mask layers 81, 87 (if present), device layer 88, and etch stop layer 90 may form nozzle layer 11. The approach of Figures 14A-14E provides a thick, robust nozzle layer 11 that is not thinned by the fabrication of membrane 304. The resulting assembly 96 with cavity 500 and / or membrane 300 can be further processed to form printhead liquid ejector 150.

[0147] 14F and 14G, the top surface 74 of the assembly 96, such as the exposed surface of the etch stop layer 90, may be bonded to the flow path wafer 76 (step 952). The flow path wafer 76 may be fabricated prior to bonding to include flow paths 475, such as the supply channels 14, the chamber inlet passages 16, the pumping chambers 18, the descender sections 20, portions of the outlet passages 26, and the outlet supply channels 28. For example, the top surface 74 of the first wafer 60 may be bonded to the flow path wafer 76 using low-temperature bonding, such as bonding with an epoxy (benzocyclobutene (BCB)) or low-temperature plasma activated bonding. Other elements, such as actuators (not shown), may be formed before or after the assembly 96 is bonded to the flow path wafer 76.

[0148] 14A-14G, a portion of the outlet passageway 26 is provided by a recess 208 in the device layer 88, and another portion of the outlet passageway 26 is provided by a recess 27 in the bottom of the channel wafer 76. The recess 27 in the bottom may extend from the descender portion 20. The recess 208 and the recess 27 overlap across the hole 302, such that the resulting membrane 300 divides the outlet passageway 26 into a first region 26a above the membrane 304 and a second region 26b below the membrane.

[0149] 14A-14G have an upper portion 26a of the outlet passage 26 connected to the descender portion 20 and a lower portion 26b of the outlet passage connected to the return channel 28, this can also be reversed, as shown in FIG. 17A. For example, the recess 27 in the bottom of the flow path wafer 76 could extend from the return channel 28 to the opening 302, rather than from the descender portion 20. Furthermore, the recess 208 could be connected to the opening 200 (and could be considered part of the opening 200). Thus, the recess 208 could extend from the descender portion 20 to the opening 302.

[0150] 17A can be combined with various other embodiments. For example, as shown in FIG. 17B, recess 208 can be formed to extend only partially through device layer 88, and a further etching step can be performed, for example, using etch stop layer 90 as a mask. Accordingly, opening 302 is etched through thin portion 88d of device layer 88 above recess 208, such as by reactive ion etching, until recess 208 is exposed. As a result, the combination of etch stop layer 90 and thin portion 88d of device layer 88 provides membrane 300 of impedance feature 310.

[0151] 14G and 15, after bonding, the handle layer 85 and the etch stop layer 84 can be removed (step 954), such as by grinding and polishing, wet etching, plasma etching, or other removal process, to expose the nozzle 22. In some implementations, the etch stop layer 84 is not removed, but an aperture is formed through the etch stop layer 84 to complete the nozzle (step 956). After the actuator is formed or attached, the resulting substrate generally corresponds to the substrate shown in FIG.

[0152] As shown in Figure 14G, the same layer 90 may provide membrane 502 for the compliant microstructure (if present) and membrane 300. As further shown in Figure 14G, with outlet passage 26 formed as a recess in the bottom of channel wafer 76, upper surface 74 of first and second wafer assembly 96 may provide the lower surface of outlet passage 26. Furthermore, the upper surface of membrane 300 may be flush with the lower surface of outlet passage 26. Similarly, the upper surface of the membrane 300 may be flush with the lower surface of the return channel 28 .

[0153] Figures 18A to 18H show a similar process to Figures 14A to 14G for fabricating the body 10 and nozzle layer 11 of the substrate 110. However, in this embodiment, the opening 302 is located directly below the return channel 28 rather than in the outlet passage 26. Fabrication may generally proceed as described above for Figures 14A to 14G and 17A, except as noted below.

[0154] 18B, a first recess 200 is formed in device layer 88 in an area corresponding to nozzle 22. This recess 200 is located below outlet passage 26 and can be thought of as providing part of descender portion 20 or nozzle 22. A second recess 220 is formed in device layer 88 in an area lying below part of return channel 28. These recesses 200 and 220 can be formed by patterning mask layer 87 and using it as a mask to etch device layer 88.

[0155] 18C , a third recess 222 in device layer 88 connects first recess 200 and second recess 220. A portion 88e of device layer 88 may remain below recess 222. Recess 222 may be formed by patterning mask layer 87 and using it as a mask to etch device layer 88. Optionally, mask layer 87 may be stripped from the entire wafer 86.

[0156] 18B and 18C depict recess 200 and recess 220 as openings that extend entirely through device layer 88, but this is not required. Recess 200 and / or recess 220 may extend only partially through device layer 88. However, recess 220 should be at least as deep as recess 222 (i.e., the same or a greater depth). Similarly, while FIG. 18B depicts recess 222 as extending only partially through device layer 88, this is not required. Recess 222 may extend entirely through device layer 88. If recesses 200, 220, and 222 are the same depth, they can be formed simultaneously in a single etching step. The relative depths of the recesses can be selected based on the needs for the height of outlet passage 26 and the thickness of membrane 300, for example, based on the desired resistance to fluid flow.

[0157] Figure 18D proceeds similarly to Figure 14C, with first wafer 80 bonded to second wafer 86 to form assembly 96, with opening 200 aligned with nozzle 22. Figure 18E proceeds similarly to Figure 14D, with handle layer 92 removed.

[0158] 18F, to form impedance feature 310, hole 302 is etched through etch stop layer 90 down to recess 220. Hole 302 may be formed by an etching process such as wet etching or plasma etching. In particular, hole 302 may be formed by anisotropic etching such as reactive ion etching.

[0159] Additionally, an aperture 342 may be formed through the etch stop layer 90 up to the recess 200 to provide an opening between the descender portion 20 and the nozzle 22 .

[0160] Opening 302 and opening 342 can be formed simultaneously in a single etching step. In particular, the openings can be formed by anisotropic etching, such as reactive ion etching.

[0161] If recess 220 does not extend completely through device layer 88, then a further etching step can be performed, for example, using etch stop layer 90 as a mask. Similarly, if recess 200 does not extend completely through device layer 88, then a further etching step can be performed, for example, using etch stop layer 90 as a mask. Thus, openings 302 and 342 can be etched through thin portion 88e of device layer 88, such as by reactive ion etching, until recess 208 is exposed.

[0162] 18F, if recess 220 extends completely through device layer 88, then the portion of etch stop layer 90 between outlet passage 26 and return channel 28 provides membrane 300. On the other hand, if recess 220 extends only partially through device layer 88 (e.g., in a manner equivalent to that shown in FIG. 16C), then the combination of etch stop layer 90 and thinned portion 88e in device layer 88 provides membrane 300.

[0163] 18G, the top surface 74 of the assembly 96, such as the exposed surface of the etch stop layer 90, may be bonded to the flow channel wafer 76. FIG. 18G proceeds similarly to FIG. 14F, except that the flow channel wafer 76 does not have recesses that define the outlet passages 26 because the outlet passages 26 are defined entirely in the device layer 88.

[0164] Figure 18H proceeds similarly to Figure 14G, in this case the nozzle is completed by removing the handle layer 85 and the etch stop layer 84, or alternatively, by removing the handle layer 85 and forming an aperture through the etch stop layer 84. After the actuator is formed or attached, the resulting substrate generally corresponds to the substrate shown in Figure 3B.

[0165] 10 , in some implementations, holes 302 of a desired size can be defined in a membrane 300 by using a mask 40 including a plurality of openings 42, such as rectangular openings. Each opening 42 corresponds to a cell region 44 defined by the corners of the opening 42, and the size and orientation of the openings 42 cause adjacent cell regions 44 to overlap. The area of each cell region 44 is approximately the square of the length of the long side l of the corresponding opening 42. An anisotropic etching process (e.g., a potassium hydroxide etching process) can be used to define terminating crystal planes (e.g., <111> By continuing the anisotropic etching until the corners of each opening 42 are reached, precise sized holes can be produced. <111> The openings 42 can be positioned to expose a surface, such that each opening 42 etches the area defined by its corresponding cell region 44. Because adjacent cell regions 44 overlap, the entire area can become an opening through this etching process.

[0166] In some embodiments, a thick layer 82 can be used (e.g., 30 μm, 50 μm, or 100 μm thick). The use of a thick nozzle wafer minimizes the risk that the nozzle fabrication process will thin the nozzle wafer to the point where it becomes weak.

[0167] The particular flow path configuration of the channel 14, inlet passage 16, and pumping chamber 18 common to various implementations is merely one example of a flow path configuration. The approaches to filter or impedance features described below can be used in many other flow path configurations. For example, if the supply channel 14 is located at the same level as the pumping chamber 18, the ascender section 16a is not necessary. As another example, an additional horizontal passage can be located between the pumping chamber 18 and the nozzle 22. In general, the description of the descender section can be generalized to a first passage connecting the pumping chamber to the inlet of the nozzle, and the description of the outlet passage can be generalized to a second passage connecting the inlet of the nozzle to the return channel.

[0168] The designation of various elements as first or second, e.g., first wafer and second wafer, does not necessarily indicate the order in which the elements are fabricated. Although positioning terms such as "above" and "below" are used, these terms are used to indicate the relative positioning of elements within a system, and do not necessarily indicate position relative to gravity.

[0169] While specific embodiments have been described, other embodiments are within the scope of the following claims.

[0170] Preferred embodiments of the present invention will be described below in detail.

[0171] Embodiment 1 a nozzle layer having an outer surface, an inner surface, and a nozzle extending between the inner surface and the outer surface, the nozzle having an inlet on the inner surface for receiving a liquid and an outlet opening on the outer surface for dispensing the liquid; a body to which the inner surface of the nozzle layer is secured, the body including a pumping chamber, a return channel, and a first passageway fluidly connecting the pumping chamber to the inlet of the nozzle; a second passageway fluidly connecting the inlet of the nozzle to the return channel; an actuator configured to force liquid out of the pumping chamber, the actuator causing liquid to be expelled from the nozzle upon actuation; and a membrane formed across and partially blocking at least one of the first passage, the second passage, or the inlet of the nozzle, the membrane having at least one hole therethrough, such that fluid flows through the at least one hole in the membrane upon actuation of the liquid ejection device; and A liquid ejection device comprising:

[0172] Embodiment 2 2. A liquid ejection device as described in embodiment 1, wherein the membrane and the hole are configured so that the first flow path has a first impedance when fluid is ejected from the nozzle and a second impedance when fluid is not ejected from the nozzle.

[0173] Embodiment 3 3. The liquid ejector of embodiment 2, wherein the first impedance is greater than the second impedance.

[0174] Embodiment 4 3. A liquid ejector according to embodiment 2, wherein the membrane is configured so that the second passage has a maximum impedance at or around a resonant frequency of the nozzle.

[0175] Embodiment 5 2. A liquid ejection device according to embodiment 1, wherein the membrane extends substantially parallel to the outer surface.

[0176] Embodiment 6 2. The liquid ejector of embodiment 1, wherein the membrane is formed across the second passage.

[0177] Embodiment 7 A liquid ejection device as described in embodiment 6, wherein the second passage includes a first portion between the inlet to the nozzle and the membrane and a second portion between the membrane and the return channel, the first portion and the second portion being separated by the membrane, and the hole penetrating the membrane fluidly connecting the first portion to the second portion.

[0178] Embodiment 8 8. The liquid ejection device of embodiment 7, wherein the first portion is provided on a side of the membrane away from the outer surface, and the second portion is provided on a side of the membrane closer to the outer surface.

[0179] Embodiment 9 9. The liquid ejection device of embodiment 8, wherein the first portion is provided on the body and the second portion is provided on the nozzle layer.

[0180] Embodiment 10 8. The liquid ejection device according to embodiment 7, wherein the first portion is provided on a side of the membrane closer to the outer surface, and the second portion is provided on a side of the membrane farther from the outer surface.

[0181] Embodiment 11 7. The liquid ejector of embodiment 6, wherein the second passageway and the return channel are separated by the membrane, and the hole through the membrane fluidly connects the second passageway to the return channel.

[0182] Embodiment 12 12. A liquid ejection device according to embodiment 11, wherein the surface of the membrane remote from the outer surface is flush with the bottom surface of the return channel.

[0183] Embodiment 13 2. A liquid ejection device as recited in embodiment 1, wherein the membrane has a plurality of holes therethrough.

[0184] Embodiment 14 14. The liquid ejection device of embodiment 13, wherein the plurality of holes are uniformly spaced across the membrane.

[0185] Embodiment 15 14. The liquid ejection device of embodiment 13, wherein the plurality of holes is configured to provide a filter.

[0186] Embodiment 16 2. The liquid ejector of embodiment 1, wherein the membrane is formed across the nozzle.

[0187] Embodiment 17 2. The liquid ejector of embodiment 1, comprising a membrane layer extending parallel to the outer surface and transversely disposed across the liquid ejector, the membrane comprising a portion of the membrane layer.

[0188] Embodiment 18 18. The liquid ejector of embodiment 17, wherein the membrane layer is embedded within the body.

[0189] Embodiment 19 18. The liquid ejection device of embodiment 17, wherein the membrane layer is disposed between the body and the nozzle layer.

[0190] Embodiment 20 18. The liquid ejection device of embodiment 17, comprising a cavity positioned adjacent to and fluidly separated from the return or supply channel fluidly connected to the pumping chamber by the membrane layer.

[0191] Embodiment 21 21. The liquid ejection device of embodiment 20, wherein the cavity and a portion of the layer covering the cavity provide a compliant microstructure to reduce crosstalk.

[0192] Embodiment 22 a wafer of a first material bonded to the side of the membrane layer away from the outer surface; 20. The liquid ejector of embodiment 19, comprising: a device layer of the first material bonded to the side of the layer closest to the outer surface.

[0193] Embodiment 23 23. The liquid ejector of embodiment 22, wherein the membrane is a second material of a different material composition than the first material.

[0194] Embodiment 24 24. The liquid ejector of embodiment 23, wherein the first material is single crystal silicon.

[0195] Embodiment 25 25. The liquid ejection device of embodiment 24, wherein the second material is silicon dioxide.

[0196] Embodiment 26 2. A liquid ejection device according to embodiment 1, wherein the membrane extends substantially parallel to the outer surface.

[0197] Embodiment 27 2. A liquid ejection device according to embodiment 1, wherein the hole is spaced apart on all sides from the walls of the first passageway, the second passageway or the nozzle, respectively.

[0198] Embodiment 28 2. A liquid ejection device according to embodiment 1, wherein the membrane protrudes inwardly substantially perpendicular to the wall of the first passageway, the second passageway, or the nozzle, respectively.

[0199] Embodiment 29 2. A liquid ejection device according to embodiment 1, wherein the membrane is formed of a material having a modulus of elasticity lower than the modulus of elasticity of a material forming the walls of the first passage, the second passage, or the nozzle.

[0200] Embodiment 30 2. A liquid ejection device according to embodiment 1, wherein the membrane is more flexible than the walls of the first passageway, the second passageway, or the nozzle.

[0201] Embodiment 31 2. A liquid ejector as recited in embodiment 1, wherein the hole through the membrane is narrower than the outlet opening of the nozzle.

[0202] Embodiment 32 2. The liquid ejector according to embodiment 1, wherein the film is formed of an oxide.

[0203] Embodiment 33 33. The liquid ejection device of embodiment 32, wherein the membrane has a thickness of between about 0.5 μm and about 5 μm.

[0204] Embodiment 34 2. The liquid ejector of embodiment 1, wherein the membrane is formed of a polymer.

[0205] Embodiment 35 15. The liquid ejector of embodiment 14, wherein the membrane has a thickness of between about 10 μm and about 30 μm.

[0206] Embodiment 36 a substrate including: a nozzle having an opening in an exterior surface; a flow path including a first portion from a pumping chamber to the nozzle and a second portion from the nozzle to a return channel; and an actuator configured to cause liquid to flow from the pumping chamber, the actuator causing liquid to be ejected from the nozzle upon actuation; a membrane formed across the second portion of the flow path, the membrane having at least one hole therethrough, the membrane configured, in operation, to allow liquid to flow through the at least one hole and to provide an impedance to the flow path responsive to an oscillation frequency of fluid in the flow path; A liquid ejection device comprising:

[0207] Embodiment 37 37. A liquid ejection device according to embodiment 36, wherein the membrane is configured to provide a first impedance when fluid is ejected from the nozzle and a second impedance when fluid is not ejected from the nozzle.

[0208] Embodiment 38 38. The liquid ejector of embodiment 37, wherein the first impedance is greater than the second impedance.

[0209] Embodiment 39 37. A liquid ejection device as described in embodiment 36, wherein the membrane is configured to provide a maximum impedance to the flow path at or around the resonant frequency of the nozzle.

[0210] Embodiment 40 37. The liquid ejector of embodiment 36, wherein the membrane is more flexible than the walls of the channel.

[0211] Embodiment 41 37. The liquid ejection device of embodiment 36, wherein the membrane extends substantially parallel to the outer surface.

[0212] Embodiment 42 37. A liquid ejector according to embodiment 36, wherein the membrane protrudes inwardly substantially perpendicular to the walls of the channel.

[0213] Embodiment 43 A liquid ejection device as described in embodiment 36, comprising an extensible microstructure adjacent to the return channel or supply channel fluidly connected to the pumping chamber, and a membrane layer providing the membrane, separating a cavity from each of the return channel or supply channel.

[0214] EMBODIMENT 44 ejecting a liquid from a nozzle of a liquid ejection device; refilling the nozzle with liquid from a channel; Including, a membrane formed across the flow path, the membrane having at least one hole therethrough, providing a first impedance to the flow path when fluid is being ejected from the nozzle and a second impedance when fluid is not being ejected from the nozzle, the first impedance being greater than the second impedance; Liquid dispensing method.

[0215] Embodiment 45 45. The method of embodiment 44, wherein the refilling of the nozzle comprises flowing a liquid through the at least one hole defined by the membrane and into the flow path.

[0216] Embodiment 46 45. The method of embodiment 44, wherein the flow path comprises a flow path fluidly connecting the nozzle to a return channel.

[0217] Embodiment 47 45. The method of embodiment 44, wherein the flow path comprises a flow path fluidly connecting the nozzle to a pumping chamber.

[0218] Embodiment 48 45. The method of embodiment 44, wherein ejecting liquid from the nozzle comprises actuating an actuator to eject liquid from a pumping chamber fluidly connected to the nozzle.

[0219] Embodiment 49 forming a nozzle in a nozzle layer, the nozzle layer having a first surface, the nozzle having an outlet opening in the first surface for ejection of a liquid; forming a film on a second surface of the nozzle layer remote from the first surface; forming at least one hole through the membrane; attaching a side of the membrane away from the nozzle layer to a wafer having the pumping chamber and the return channel such that the at least one hole in the membrane provides a constriction in a passage between the pumping chamber and the nozzle or a second passage between the nozzle and the return channel; A method for manufacturing a liquid ejection device, comprising:

[0220] Embodiment 50 50. The method of claim 49, comprising forming an actuator on the wafer, the actuator configured to force liquid out of the pumping chamber, whereby actuation of the actuator causes liquid to be ejected from the nozzle.

[0221] Embodiment 51 50. The method of embodiment 49, wherein the membrane and the at least one hole are formed to have a maximum impedance at or around a resonant frequency of the nozzle.

[0222] Embodiment 52 50. The method of embodiment 49, wherein forming the at least one hole comprises etching the membrane.

[0223] Embodiment 53 50. The method of embodiment 49, comprising forming a plurality of holes in the membrane.

[0224] EMBODIMENT 54 50. The method of embodiment 49, wherein the film is formed of an oxide.

[0225] Embodiment 55 50. The method of embodiment 49, wherein the membrane is formed of a polymer.

[0226] Embodiment 56 50. The method of embodiment 49, wherein the nozzle layer is disposed on a handle layer, and the membrane is formed on the nozzle layer on a side opposite the handle layer.

[0227] Embodiment 57 57. The method of claim 56, comprising removing the handle layer. [Explanation of symbols]

[0228] 10 Main Unit 11 Nozzle Layer 11a surface 12 Substrate inlet 14, 14a Introduction supply channel 16. Pressure chamber introduction passage 16a Ascender 16b (horizontal) pumping chamber inlet 18 Pumping Chamber 20 Descenders 22 nozzles Columns 23, 23a, 23b 24 nozzle opening 26 Lead-out passage 26a First area 26b Second area 27, 208, 506 dents 28, 28a, 28b: Outlet supply channel (return channel) 30 Actuator 31 Piezoelectric layer 32a, 32b part 40 Mask 42 Opening 44 cell area 50 Microstructure 52, 54 bottom 60 First Wafer 64 Drive electrode 65 Ground electrode 66 Membrane (layer) 67 Adhesive layer 74 Top surface 76 Flow path wafer 80 First wafer 81, 87 Mask layer 82, 88 Device layer 84, 90 Etch stop layer 85, 92 handle layer 86 Second wafer 88a, 88b, 88c, 88d, 88e Part of the device layer 96 Assembly 100 printheads 110 Substrate 112 Bottom of the board 120 Interposer Assembly 122 Upper Interposer 124 bottom interposer 130 cabinet 132 Liquid Supply Chamber 134 Bulkhead 136 Return chamber 150 Liquid dispensing device 200, 510 opening 202, 204 recessed area 220 Second recess 222 Third recess 300, 304, 502 membrane 302 holes 310 Impedance Characteristics (Impedance Structure) 320 Filter features (filtration structure) 340, 342 Aperture (opening) 400 channels 402 Liquid supply inlet (inlet opening) 408 Liquid return outlet (exit opening) 475 Flow path of discharge device (flow path) 500 cavities 504 Interior

Claims

1. ejecting a liquid from a nozzle of a liquid ejection device; refilling the nozzle with liquid from a channel; Including, A method of ejecting liquid, wherein a compliant membrane is formed across the flow path, the membrane having at least one hole therethrough, the hole being narrower than the outlet opening of the nozzle, the compliant membrane with the at least one hole providing a maximum impedance to the flow path at or around a resonant frequency of the nozzle, the membrane providing a first impedance to the flow path when fluid is being ejected from the nozzle and a second impedance when fluid is not being ejected from the nozzle, and the first impedance is greater than the second impedance.

2. The method of claim 1 , wherein the step of refilling the nozzle comprises flowing a liquid through at least one hole in the membrane.

3. The method of claim 1 , wherein the step of refilling the nozzle comprises the step of flowing liquid along the flow path from a pumping chamber to the nozzle.

4. The method of claim 1 , wherein the step of refilling the nozzle comprises flowing liquid along the flow path from a return channel to the nozzle.

5. The method of claim 1 , wherein the step of ejecting liquid from the nozzle comprises the step of flowing liquid through at least one hole in the membrane.

6. The method of claim 1 , wherein ejecting liquid from the nozzle of the liquid ejection device comprises actuating an actuator to eject liquid from a pumping chamber fluidly connected to the nozzle.

7. The method of claim 6 , wherein the actuating an actuator comprises actuating a piezoelectric actuator.

8. 2. The method of claim 1, wherein the step of ejecting the liquid includes a step of flowing the liquid along a first portion of a flow path between a pumping chamber of the liquid ejection device and the nozzle, and the step of refilling the nozzle includes a step of refilling the nozzle with liquid from a second portion of the flow path between a return channel and the nozzle.

9. The method of claim 8 , wherein the compliant membrane is formed across and inside the second portion of the channel.

10. The method of claim 8 , further comprising the step of recirculating a portion of the liquid not ejected from the nozzle along the second portion of the flow path from the nozzle.

Images