U.S. patent application number 13/296111 was filed with the patent office on 2012-03-29 for method of forming a nozzle chamber incorporating an ink ejection paddle and nozzle chamber rim.
This patent application is currently assigned to Silverbrook Research Pty Ltd. Invention is credited to Kia Silverbrook.
Application Number | 20120073135 13/296111 |
Document ID | / |
Family ID | 39112980 |
Filed Date | 2012-03-29 |
United States Patent
Application |
20120073135 |
Kind Code |
A1 |
Silverbrook; Kia |
March 29, 2012 |
METHOD OF FORMING A NOZZLE CHAMBER INCORPORATING AN INK EJECTION
PADDLE AND NOZZLE CHAMBER RIM
Abstract
A method of forming a printhead nozzle chamber includes steps of
forming a first laminate of sacrificial layers on a substrate, the
first laminate of sacrificial layers being formed as a ring on the
substrate; hard-baking the first laminate of sacrificial layers to
cause a shrinkage in the first laminate of sacrificial layers, the
shrinkage further causing edges of the first laminate of
sacrificial layers to angle inwards and form an approximate
trapezoidal cross-section; depositing a TiN layer over the first
laminate of sacrificial layer and the substrate, the TiN layer
being inclined at portions deposited over the inwardly angled
edges; etching the TiN layer to form a paddle and a nozzle chamber
rim, the paddle incorporating an inner inclined portion and the
nozzle chamber rim incorporating a complementary outer inclined
portion, the paddle and nozzle rim defining an aperture
therebetween; and removing the first laminate of sacrificial
layers
Inventors: |
Silverbrook; Kia; (Balmain,
AU) |
Assignee: |
Silverbrook Research Pty
Ltd
|
Family ID: |
39112980 |
Appl. No.: |
13/296111 |
Filed: |
November 14, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12704465 |
Feb 11, 2010 |
8069565 |
|
|
13296111 |
|
|
|
|
11923602 |
Oct 24, 2007 |
7669979 |
|
|
12704465 |
|
|
|
|
11058238 |
Feb 16, 2005 |
7287839 |
|
|
11923602 |
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|
10637679 |
Aug 11, 2003 |
7007859 |
|
|
11058238 |
|
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10204211 |
Aug 19, 2002 |
6659593 |
|
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PCT/AU00/00333 |
Apr 18, 2000 |
|
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|
10637679 |
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Current U.S.
Class: |
29/890.1 |
Current CPC
Class: |
B41J 2/14427 20130101;
Y10T 29/49401 20150115; B41J 2202/11 20130101 |
Class at
Publication: |
29/890.1 |
International
Class: |
B21D 53/76 20060101
B21D053/76 |
Claims
1. A method of forming a nozzle chamber of a printhead, the method
comprising the steps of: forming a first laminate of sacrificial
layers on a substrate, the first laminate of sacrificial layers
being formed as a ring on the substrate; hard-baking the first
laminate of sacrificial layers to cause a shrinkage in the first
laminate of sacrificial layers, the shrinkage further causing edges
of the first laminate of sacrificial layers to angle inwards and
form an approximate trapezoidal cross-section; depositing a TiN
layer over the first laminate of sacrificial layer and the
substrate, the TiN layer being inclined at portions deposited over
the inwardly angled edges; etching the TiN layer to form a paddle
and a nozzle chamber rim, the paddle incorporating an inner
inclined portion and the nozzle chamber rim incorporating a
complementary outer inclined portion, the paddle and nozzle rim
defining an aperture therebetween; and removing the first laminate
of sacrificial layers.
2. The method according to claim 1, further comprising a step of
forming one or more second laminates of sacrificial layers within
the ring of the first laminate of sacrificial layers.
3. The method according to claim 2, wherein the one or more second
laminates of sacrificial layers are photoimaged to cause edges
thereof to angle inwards and form an approximate trapezoidal
cross-section, and the TiN layer is deposited over the one or more
second laminates of sacrificial layers, thereby forming truncated
pyramidal protrusions on the paddle.
4. The method according to claim 2, wherein the one or more second
laminates of sacrificial layers are formed proximal a centre of the
ring of the first laminate of sacrificial layers.
5. The method according to claim 1, wherein the one or more second
laminates of sacrificial layers are formed as one or more
concentric rings within and concentric with the ring of the first
laminate of sacrificial layers.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] This is a Continuation of U.S. application Ser. No. 12704465
filed Feb. 11, 2010 of U.S. application Ser. No. 11/923602 filed
Oct. 24, 2007, now issued as U.S. Pat. No. 7,669,979, which is a
Continuation Application of U.S. Ser. No. 11/058,238 filed 16 Feb.
2005, now issued as U.S. Pat. No. 7,287,839, which is a
continuation of U.S. Ser. No. 10/637,679 filed Aug. 11, 2003, now
issued as U.S. Pat. No. 7,007,859, which is a Continuation
Application of U.S. Ser. No. 10/204,211 filed Aug. 19, 2002, now
issued as U.S. Pat. No. 6,659,593, which is a 371 of PCT/AU00/00333
filed Apr. 18, 2000, all of which are herein incorporated by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of Micro Electro
Mechanical Systems (MEMS), and specifically inkjet printheads
formed using MEMS technology.
BACKGROUND OF THE INVENTION
[0003] MEMS devices are becoming increasingly popular and normally
involve the creation of devices on the micron scale utilising
semiconductor fabrication techniques. For a recent review on MEMS
devices, reference is made to the article "The Broad Sweep of
Integrated Micro Systems" by S. Tom Picraux and Paul J. McWhorter
published December 1998 in IEEE Spectrum at pages 24 to 33.
[0004] MEMS manufacturing techniques are suitable for a wide range
of devices, one class of which is inkjet printheads. One form of
MEMS devices in popular use are inkjet printing devices in which
ink is ejected from an ink ejection nozzle chamber. Many forms of
inkjet devices are known.
[0005] Many different techniques on inkjet printing and associated
devices have been invented. For a survey of the field, reference is
made to an article by J Moore, "Non-Impact Printing: Introduction
and Historical Perspective", Output Hard Copy Devices, Editors R
Dubeck and S Sherr, pages 207 to 220 (1988).
[0006] Recently, a new form of inkjet printing has been developed
by the present applicant, which is referred to as Micro Electro
Mechanical Inkjet (MEMJET) technology. In one form of the MEMJET
technology, ink is ejected from an ink ejection nozzle chamber
utilizing an electro mechanical actuator connected to a paddle or
plunger which moves towards the ejection nozzle of the chamber for
ejection of drops of ink from the ejection nozzle chamber.
[0007] The present invention concerns modifications to the
structure of the paddle and/or the walls of the chamber to improve
the efficiency of ejection of fluid from the chamber and subsequent
refill.
SUMMARY OF THE INVENTION
[0008] According to an aspect of the present disclosure, a method
of forming a nozzle chamber of a printhead, the method comprising
the steps of: forming a first laminate of sacrificial layers on a
substrate, the first laminate of sacrificial layers being formed as
a ring on the substrate; hard-baking the first laminate of
sacrificial layers to cause a shrinkage in the first laminate of
sacrificial layers, the shrinkage further causing edges of the
first laminate of sacrificial layers to angle inwards and form an
approximate trapezoidal cross-section; depositing a TiN layer over
the first laminate of sacrificial layer and the substrate, the TiN
layer being inclined at portions deposited over the inwardly angled
edges; etching the TiN layer to form a paddle and a nozzle chamber
rim, the paddle incorporating an inner inclined portion and the
nozzle chamber rim incorporating a complementary outer inclined
portion, the paddle and nozzle rim defining an aperture
therebetween; and removing the first laminate of sacrificial
layers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Notwithstanding any other forms which may fall within the
scope of the present invention, preferred forms of the invention
will now be described, by way of example only, with reference to
the accompanying drawings, in which:
[0010] FIG. 1 illustrates schematically a sectional view of a
thermal bend actuator type ink injection device;
[0011] FIG. 2 illustrates a sectional view though a nozzle chamber
of a first embodiment with the paddle in a quiescent state;
[0012] FIG. 3 illustrates the fluid flow in the nozzle chamber of
the first embodiment during a forward stroke;
[0013] FIG. 4 illustrates the fluid flow in the nozzle chamber of
the first embodiment during mid-term stroke;
[0014] FIG. 5 illustrates the manufacturing process in the
construction of a first embodiment of the invention;
[0015] FIG. 6 is a sectional view through a second embodiment of
the invention;
[0016] FIG. 7 is a sectional plan view of the embodiment of FIG. 6;
and
[0017] FIG. 8 illustrates the manufacturing process in construction
of the second embodiment of the invention.
DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS
[0018] In the preferred embodiment, a compact form of liquid
ejection device is provided which utilises a thermal bend actuator
to eject ink from a nozzle chamber.
[0019] As shown in FIG. 1, there is provided an ink ejection
arrangement 1 which comprises a nozzle chamber 2 which is normally
filled with ink so as to form a meniscus 10 around an ink ejection
nozzle 11 having a raised rim. The ink within the nozzle chamber 2
is resupplied by means of ink supply channel 3.
[0020] The ink is ejected from a nozzle chamber 2 by means of a
thermal actuator 7 which is rigidly interconnected to a nozzle
paddle 5. The thermal actuator 7 comprises two arms 8, 9 with the
bottom arm 9 being interconnected to an electrical current source
so as to provide conductive heating of the bottom arm 9. When it is
desired to eject a drop from the nozzle chamber 2, the bottom arm 9
is heated so as to cause rapid expansion of this arm 9 relative to
the top arm 8. The rapid expansion in turn causes a rapid upward
movement of the paddle 5 within the nozzle chamber 2. This initial
movement causes a substantial increase in pressure within the
nozzle chamber 2 which in turn causes ink to flow out of the nozzle
11 causing the meniscus 10 to bulge. Subsequently, the current to
the heater 9 is turned off so as to cause the paddle 5 to begin to
return to its original position. This results in a substantial
decrease in the pressure within the nozzle chamber 2. The forward
momentum of the ink outside the nozzle rim 11 results in a necking
and breaking of the meniscus so as to form a meniscus and a droplet
of ink 18 (see FIG. 4). The droplet 18 continues forward onto the
ink print medium as the paddle returns toward its rest state. The
meniscus then returns to the position shown in FIG. 1, drawing ink
past the paddle 5 in to the chamber 2. The wall of the chamber 2
forms an aperture in which the paddle 5 sits with a small gap there
between.
[0021] FIG. 2 illustrates a sectional view through the nozzle
chamber 2 of a first embodiment of the invention when in an idle
state. The nozzle chamber paddle 5 includes an upturned edge
surface 12 which cooperates with the nozzle paddle rim edge 13.
There is an aperture 16 between the paddle 5 and the rim 13.
Initially, when it is desired to eject a drop of ink, the actuator
(not shown) is activated so as to cause the paddle 5 to move
rapidly in an upward (or forward) direction, indicated by arrow A
in FIG. 3. As a result, the pressure within the nozzle chamber 2
substantially increases and ink begins to flow out of the nozzle
chamber, as illustrated in FIG. 3, with the meniscus 10 rapid
bulging. The movement of the paddle 5 and increased pressure also
cause fluid to flow from the centre of the paddle 5 outwards toward
the paddle's peripheral edge as indicated by arrows 15. The fluid
flow across the paddle is diverted by the upturned edge portion 12
so as to tend to flow over the aperture 16 between the paddle 5 and
the wall 13 rather than through the aperture. There is still a
leakage flow through the aperture 16, but this is reduced compared
to devices in which one or both of the paddle 5 and wall 13 are
planar. The profiling of the edges 12 and 13 thus results in a
substantial reduction in the amount of fluid flowing around the
surface of the paddle upon upward movement. Higher pressure is
achieved in the nozzle chamber 2 for a given paddle deflection,
resulting in greater efficiency of the nozzle. A greater volume of
ink may be ejected for the same paddle stroke or a reduced paddle
stroke (and actuator power consumption) may be used to eject the
same volume of ink, compared to a planar paddle device.
[0022] Whilst the peripheral portion 13 of the chamber wall
defining the inlet port is also angled upwards, it will be
appreciated that this is not essential.
[0023] Subsequently, the thermal actuator is deactivated and the
nozzle paddle rapidly starts returning to its rest position as
illustrated in FIG. 4. This results in a general reduction in the
pressure within the nozzle chamber 2 which in turn results in a
general necking and breaking of a drop 18. The meniscus 10 is drawn
into the chamber 2 and then returns to the position shown in FIG.
2, resulting in ink being drawn into the chamber, as indicated by
arrows 19 in FIG. 4.
[0024] The profiling of the lower surfaces of the edge regions 12,
13 also assists in channelling fluid flow into the top portion of
the nozzle chamber compared to simple planar surfaces.
[0025] The rapid refill of the nozzle chamber in turn allows for
higher speed operation.
Process of Manufacture
[0026] The arrangement in FIG. 5 illustrates one-half of a nozzle
chamber, which is symmetrical around axis 22. The manufacturing
process can proceed as follows: [0027] 1. The starting substrate is
a CMOS wafer 20 which includes CMOS circuitry 21 formed thereon in
accordance with the required electrical drive and data storage
requirements for driving a thermal bend actuator 5. [0028] 2. The
next step is to deposit a 2 micron layer of photoimageable
polyimide 24. The layer 24 forms a first sacrificial layer which is
deposited by means of spinning on a polyimide layer; soft-baking
the layer, and exposing and developing the layer through a suitable
mask. A subsequent hard-bake of the layer 24 shrinks it to 1 micron
in height. [0029] 3. A second polyimide sacrificial layer is
photoimaged utilizing the method of step 2 so as to provide for a
second sacrificial layer 26. The shrinkage of the layer 26 causes
its edges to be angled inwards. [0030] 4. Subsequently, a third
sacrificial layer 27 is deposited and imaged again in accordance
with the process previously outlined in respect of step 2. This
layer forms a third sacrificial layer 27. Again the edges of layer
27 are angled inwards. It will be appreciated that the single layer
26 may be sufficient by itself and that layer 27 need not be
deposited. [0031] 5. The paddle 28 and bicuspid edges, e.g. 29, 30
are then formed, preferably from titanium nitride, through the
deposit of a 0.25 micron TiN layer. This TiN layer is deposited and
etched through an appropriate mask. [0032] 6. Subsequently, a
fourth sacrificial layer 32 is formed, which can comprise 6 microns
of resist, the resist being suitably patterned. [0033] 7. A 1
micron layer of dielectric material 33 is then deposited at a
temperature less than the decomposition temperature of resist layer
32. [0034] 8. Subsequently, a fifth resist layer 34 is also formed
and patterned. [0035] 9. A 0.1 micron layer of dielectric material,
not shown, is then deposited. [0036] 10. The dielectric material is
then etched anisotropically to a depth of 0.2 microns. [0037] 11. A
nozzle guard, not shown, if required, is then attached to the wafer
structure. [0038] 12. Subsequently the wafer is prepared for dicing
and packaging by mounting the wafer on an UV tape. [0039] 13. The
wafer is then back etched from the back surface of the wafer
utilizing a deep silicon etching process so as to provide for the
ink channel supply while simultaneously separating the printhead
wafer into individual printhead segments.
[0040] Referring to FIGS. 6 and 7 there is shown a second
embodiment having similar components to those of the first
embodiment, and so the same numbers are used as for the first
embodiment.
[0041] In the FIGS. 6 and 7 embodiment the paddle is formed with a
series of truncated pyramidal protrusions 40 in the central portion
of the paddle. These protrusions 40 aid in reducing fluid flow
outward from the centre of the paddle 5 as the paddle moves upward.
Whilst the FIGS. 6 and 7 embodiment is provided with a series of
discrete truncated pyramidal protrusions, a series of ridges may be
provided instead. Such ridges may be paralleling, concentric or
intersecting. The ridges may be elliptical, circular, arcuate or
any other shape.
[0042] FIG. 8 illustrates the manufacturing process of the
embodiment of FIGS. 6 and 7. The process is the same as that
described with reference to FIG. 5 except that at steps 3 and 4,
the sacrificial layers 26 and 27 are also deposited to be
underneath the as yet unformed central portion of the paddle layer
28, as indicated by the numerals 26B and 27A.
[0043] It would be appreciated by a person skilled in the art that
numerous variations and/or modifications may be made to the present
invention as shown in the specific embodiment without departing
from the spirit or scope of the invention as broadly described. The
present embodiments are, therefore, to be considered in all
respects to be illustrative and not restrictive.
* * * * *