# Patent

## Title
Ink jet printhead with glass nozzle chambers

## Abstract

An ink jet printhead is provided. The printhead comprises: a silicon substrate; a CMOS layer comprising drive and control circuitry, the CMOS layer being formed on the silicon substrate; a passivation layer covering the CMOS layer; and a plurality of nozzles mounted on the passivation layer. Each nozzle comprises a chamber adapted to contain an ejectable liquid; and a droplet ejection actuator associated with each of the chambers respectively, the droplet ejection actuator being electrically connected to the drive circuitry and adapted to eject a droplet of the ejectable liquid from the nozzle. The chambers are comprised of a glass material.

## Background
CROSS REFERENCES TO RELATED APPLICATIONS
The present application is a continuation of U.S. application Ser. No. 10/407,212 filed on Apr. 7, 2003, now issued as U.S. Pat. No. 7,416,280, which is a continuation-in-part of U.S. application Ser. No. 09/113,122 filed on Jul. 10, 1998, now issued as U.S. Pat. No. 6,557,977, the entire contents of which are herein incorporated by reference.
The following Australian provisional patent applications are hereby incorporated by reference. For the purposes of location and identification, US patents/patent applications identified by their US patent/patent application serial numbers are listed alongside the Australian applications from which the US patents/patent applications claim the right of priority.













US PATENT/PATENT



CROSS-REFERENCED
APPLICATION (CLAIMING


AUSTRALIAN
RIGHT OF PRIORITY FROM


PROVISIONAL PATENT
AUSTRALIAN PROVISIONAL
DOCKET


APPLICATION NO.
APPLICATION)
NO.







PO7991
09/113,060
ART01


PO8505
6,476,863
ART02


PO7988
09/113,073
ART03


PO9395
6,322,181
ART04


PO8017
09/112,747
ART06


PO8014
6,227,648
ART07


PO8025
09/112,750
ART08


PO8032
09/112,746
ART09


PO7999
09/112,743
ART10


PO7998
09/112,742
ART11


PO8031
09/112,741
ART12


PO8030
6,196,541
ART13


PO7997
6,195,150
ART15


PO7979
6,362,868
ART16


PO8015
09/112,738
ART17


PO7978
09/113,067
ART18


PO7982
6,431,669
ART19


PO7989
6,362,869
ART20


PO8019
6,472,052
ART21


PO7980
6,356,715
ART22


PO8018
09/112,777
ART24


PO7938
09/113,224
ART25


PO8016
6,366,693
ART26


PO8024
6,329,990
ART27


PO7940
09/113,072
ART28


PO7939
6,459,495
ART29


PO8501
6,137,500
ART30


PO8500
09/112,796
ART31


PO7987
09/113,071
ART32


PO8022
6,398,328
ART33


PO8497
09/113,090
ART34


PO8020
6,431,704
ART38


PO8023
09/113,222
ART39


PO8504
09/112,786
ART42


PO8000
6,415,054
ART43


PO7977
09/112,782
ART44


PO7934
09/113,056
ART45


PO7990
09/113,059
ART46


PO8499
6,486,886
ART47


PO8502
6,381,361
ART48


PO7981
6,317,192
ART50


PO7986
09/113,057
ART51


PO7983
09/113,054
ART52


PO8026
09/112,752
ART53


PO8027
09/112,759
ART54


PO8028
09/112,757
ART56


PO9394
6,357,135
ART57


PO9396
09/113,107
ART58


PO9397
6,271,931
ART59


PO9398
6,353,772
ART60


PO9399
6,106,147
ART61


PO9400
09/112,790
ART62


PO9401
6,304,291
ART63


PO9402
09/112,788
ART64


PO9403
6,305,770
ART65


PO9405
6,289,262
ART66


PP0959
6,315,200
ART68


PP1397
6,217,165
ART69


PP2370
09/112,781
DOT01


PP2371
09/113,052
DOT02


PO8003
6,350,023
Fluid01


PO8005
6,318,849
Fluid02


PO9404
09/113,101
Fluid03


PO8066
6,227,652
IJ01


PO8072
6,213,588
IJ02


PO8040
6,213,589
IJ03


PO8071
6,231,163
IJ04


PO8047
6,247,795
IJ05


PO8035
6,394,581
IJ06


PO8044
6,244,691
IJ07


PO8063
6,257,704
IJ08


PO8057
6,416,168
IJ09


PO8056
6,220,694
IJ10


PO8069
6,257,705
IJ11


PO8049
6,247,794
IJ12


PO8036
6,234,610
IJ13


PO8048
6,247,793
IJ14


PO8070
6,264,306
IJ15


PO8067
6,241,342
IJ16


PO8001
6,247,792
IJ17


PO8038
6,264,307
IJ18


PO8033
6,254,220
IJ19


PO8002
6,234,611
IJ20


PO8068
6,302,528
IJ21


PO8062
6,283,582
IJ22


PO8034
6,239,821
IJ23


PO8039
6,338,547
IJ24


PO8041
6,247,796
IJ25


PO8004
09/113,122
IJ26


PO8037
6,390,603
IJ27


PO8043
6,362,843
IJ28


PO8042
6,293,653
IJ29


PO8064
6,312,107
IJ30


PO9389
6,227,653
IJ31


PO9391
6,234,609
IJ32


PP0888
6,238,040
IJ33


PP0891
6,188,415
IJ34


PP0890
6,227,654
IJ35


PP0873
6,209,989
IJ36


PP0993
6,247,791
IJ37


PP0890
6,336,710
IJ38


PP1398
6,217,153
IJ39


PP2592
6,416,167
IJ40


PP2593
6,243,113
IJ41


PP3991
6,283,581
IJ42


PP3987
6,247,790
IJ43


PP3985
6,260,953
IJ44


PP3983
6,267,469
IJ45


PO7935
6,224,780
IJM01


PO7936
6,235,212
IJM02


PO7937
6,280,643
IJM03


PO8061
6,284,147
IJM04


PO8054
6,214,244
IJM05


PO8065
6,071,750
IJM06


PO8055
6,267,905
IJM07


PO8053
6,251,298
IJM08


PO8078
6,258,285
IJM09


PO7933
6,225,138
IJM10


PO7950
6,241,904
IJM11


PO7949
6,299,786
IJM12


PO8060
09/113,124
IJM13


PO8059
6,231,773
IJM14


PO8073
6,190,931
IJM15


PO8076
6,248,249
IJM16


PO8075
09/113,120
IJM17


PO8079
6,241,906
IJM18


PO8050
09/113,116
IJM19


PO8052
6,241,905
IJM20


PO7948
09/113,117
IJM21


PO7951
6,231,772
IJM22


PO8074
6,274,056
IJM23


PO7941
6,290,861
IJM24


PO8077
6,248,248
IJM25


PO8058
6,306,671
IJM26


PO8051
6,331,258
IJM27


PO8045
6,110,754
IJM28


PO7952
6,294,101
IJM29


PO8046
6,416,679
IJM30


PO9390
6,264,849
IJM31


PO9392
6,254,793
IJM32


PP0889
6,235,211
IJM35


PP0887
6,491,833
IJM36


PP0882
6,264,850
IJM37


PP0874
6,258,284
IJM38


PP1396
6,312,615
IJM39


PP3989
6,228,668
IJM40


PP2591
6,180,427
IJM41


PP3990
6,171,875
IJM42


PP3986
6,267,904
IJM43


PP3984
6,245,247
IJM44


PP3982
6,315,914
IJM45


PP0895
6,231,148
IR01


PP0870
09/113,106
IR02


PP0869
6,293,658
IR04


PP0887
09/113,104
IR05


PP0885
6,238,033
IR06


PP0884
6,312,070
IR10


PP0886
6,238,111
IR12


PP0871
09/113,086
IR13


PP0876
09/113,094
IR14


PP0877
6,378,970
IR16


PP0878
6,196,739
IR17


PP0879
09/112,774
IR18


PP0883
6,270,182
IR19


PP0880
6,152,619
IR20


PP0881
09/113,092
IR21


PO8006
6,087,638
MEMS02


PO8007
6,340,222
MEMS03


PO8008
09/113,062
MEMS04


PO8010
6,041,600
MEMS05


PO8011
6,299,300
MEMS06


PO7947
6,067,797
MEMS07


PO7944
6,286,935
MEMS09


PO7946
6,044,646
MEMS10


PO9393
09/113,065
MEMS11


PP0875
09/113,078
MEMS12


PP0894
6,382,769
MEMS13











STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
FIELD OF THE INVENTION
The present invention relates to an ink jet printer device.
BACKGROUND OF THE INVENTION
Many different types of printing have been invented, a large number of which are presently in use. The known forms of print have a variety of methods for marking the print media with a relevant marking media. Commonly used forms of printing include offset printing, laser printing and copying devices, dot matrix type impact printers, thermal paper printers, film recorders, thermal wax printers, dye sublimation printers and ink jet printers both of the drop on demand and continuous flow type. Each type of printer has its own advantages and problems when considering cost, speed, quality, reliability, simplicity of construction and operation etc.
In recent years, the field of ink jet printing, wherein each individual pixel of ink is derived from one or more ink nozzles has become increasingly popular primarily due to its inexpensive and versatile nature.
Many different techniques of ink jet printing 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 Hand Copy Device, Editors R Dubeck and S Sherr, pages 207-220 (1988).
Ink Jet printers themselves come in many different forms. The utilization of a continuous stream of ink in ink jet printing appears to date back to at least 1929 wherein U.S. Pat. No. 1,941,001 by Hansell discloses a simple form of continuous stream electrostatic ink jet printing.
U.S. Pat. No. 3,596,275 by Sweet also discloses a process of continuous ink jet printing including a step wherein the ink jet stream is modulated by a high frequency electro-static field so as to cause drop separation. This technique is still utilized by several manufacturers including Elmjet and Scitex (see also U.S. Pat. No. 3,373,437 by Sweet et al).
Piezoelectric ink jet printers are also one form of commonly utilized ink jet printing device. Piezoelectric systems are disclosed by Kyser et. al. in U.S. Pat. No. 3,946,398 (1970) which utilizes a diaphragm mode of operation, by Zolten in U.S. Pat. No. 3,683,212 (1970) which discloses a squeeze mode of operation of a piezoelectric crystal, Stemme in U.S. Pat. No. 3,747,120 (1972) discloses a bend mode of piezoelectric operation, Howkins in U.S. Pat. No. 4,459,601 discloses a piezoelectric push mode actuation of the ink jet stream and Fischbeck in U.S. Pat. No. 4,584,590 which discloses a shear mode type of piezoelectric transducer element.
Recently, thermal ink jet printing has become an extremely popular form of ink jet printing. The ink jet printing techniques include those disclosed by Endo et al in GB 2007162 (1979) and Vaught et al in U.S. Pat. No. 4,490,728. Both the aforementioned references disclose ink jet printing techniques which rely upon the activation of an electrothermal actuator which results in the creation of a bubble in a constricted space, such as a nozzle, which thereby causes the ejection of ink from an aperture connected to the confined space onto a relevant print media. Printing devices utilizing the electro-thermal actuator are manufactured by manufacturers such as Canon and Hewlett Packard.
As can be seen from the foregoing, many different types of printing technologies are available. Ideally, a printing technology should have a number of desirable attributes. These include inexpensive construction and operation, high speed operation, safe and continuous long term operation etc. Each technology may have its own advantages and disadvantages in the areas of cost, speed, quality, reliability, power usage, simplicity of construction operation, durability and consumables.
It would be desirable to create a more compact and efficient inkjet printer having an efficient and effective operation in addition to being as compact as possible.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective cross-sectional view of a single ink jet nozzle constructed in accordance with a preferred embodiment;
FIG. 2 is a close-up perspective cross-sectional view (portion A of FIG. 1), of a single ink jet nozzle constructed in accordance with a preferred embodiment;
FIG. 3 is an exploded perspective view illustrating the construction of a single ink jet nozzle in accordance with a preferred embodiment;
FIG. 4 provides a legend of the materials indicated in FIGS. 1 to 15; and
FIGS. 5 to 15 illustrate sectional views of the manufacturing steps in one form of construction of an ink jet printhead nozzle.



DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS
The ink jet designs shown here are suitable for a wide range of digital printing systems, from battery powered one-time use digital cameras, through to desktop and network printers, and through to commercial printing systems
For ease of manufacture using standard process equipment, the print head is designed to be a monolithic CMOS chip with MEMS post processing. For a general introduction to micro-electric mechanical systems (MEMS) reference is made to standard proceedings in this field including the proceedings of the SPIE (International Society for Optical Engineering), volumes 2642 and 2882 which contain the proceedings for recent advances and conferences in this field.
For color photographic applications, the print head is 100 mm long, with a width which depends upon the ink jet type.
IJ02
In a preferred embodiment, an ink jet print head is made up of a plurality of nozzle chambers each having an ink ejection port. Ink is ejected from the ink ejection port through the utilization of attraction between two parallel plates.
Turning initially to FIG. 1, there is illustrated a cross-sectional view of a single nozzle arrangement 210 as constructed in accordance with a preferred embodiment. The nozzle arrangement 210 includes a nozzle chamber 211 in which is stored ink to be ejected out of an ink ejection port 212. The nozzle arrangement 210 can be constructed on the top of a silicon wafer utilizing micro electro-mechanical systems construction techniques as will become more apparent hereinafter. The top of the nozzle plate also includes a series of regular spaced etchant holes, e.g. 213 which are provided for efficient sacrificial etching of lower layers of the nozzle arrangement 210 during construction. The size of the etchant holes 213 is signal enough that surface tension characteristics inhibit ejection from the holes 213 during operation.
Ink is supplied to the nozzle chamber 211 via an ink supply channel, e.g. 215.
Turning now to FIG. 2, there is illustrated a cross-sectional view of one side of the nozzle arrangement 210. A nozzle arrangement 210 is constructed on a silicon wafer base 217 on top of which is first constructed a standard CMOS two level metal layer 218 which includes the required drive and control circuitry for each nozzle arrangement. The layer 218, which includes two levels of aluminum, includes one level of aluminum 219 being utilized as a bottom electrode plate. Other portions 220 of this layer can comprise nitride passivation. On top of the layer 219 there is provided a thin polytetrafluoroethylene (PTFE) layer 221.
Next, an air gap 227 is provided between the top and bottom layers. This is followed by a further PTFE layer 228 which forms part of the top plate 222. The two PTFE layers 221, 228 are provided so as to reduce possible stiction effects between the upper and lower plates. Next, a top aluminum electrode layer 230 is provided followed by a nitride layer (not shown) which provides structural integrity to the top electro plate. The layers 228-230 are fabricated so as to include a corrugated portion 223 which concertinas upon movement of the top plate 222.
By placing a potential difference across the two aluminum layers 219 and 230, the top plate 222 is attracted to bottom aluminum layer 219 thereby resulting in a movement of the top plate 222 towards the bottom plate 219. This results in energy being stored in the concertinaed spring arrangement 223 in addition to air passing out of the side air holes, e.g. 233 and the ink, being sucked into the nozzle chamber as a result of the distortion of the meniscus over the ink ejection port 212 (FIG. 1). Subsequently, the potential across the plates is eliminated thereby causing the concertinaed spring portion 223 to rapidly return the plate 222 to its rest position. The rapid movement of the plate 222 causes the consequential ejection of ink from the nozzle chamber via the ink ejection port 212 (FIG. 1). Additionally, air flows in via air gap 233 underneath the plate 222.
The ink jet nozzles of a preferred embodiment can be formed from utilization of semi-conductor fabrication and MEMS techniques. Turning to FIG. 3, there is illustrated an exploded perspective view of the various layers in the final construction of a nozzle arrangement 210. At the lowest layer is the silicon wafer 217 upon which all other processing steps take place. On top of the silicon layer 217 is the CMOS circuitry layer 218 which primarily comprises glass. On top of this layer is a nitride passivation layer 220 which is primarily utilized to passivate and protect the lower glass layer from any sacrificial process that may be utilized in the building up of subsequent layers. Next there is provided the aluminum layer 219 which, in the alternative, can form part of the lower CMOS glass layer 218. This layer 219 forms the bottom plate. Next, two PTFE layers 226, 228 are provided between which is laid down a sacrificial layer, such as glass, which is subsequently etched away so as to release the plate 222 (FIG. 2). On top of the PTFE layer 228 is laid down the aluminum layer 230 and a subsequent thicker nitride layer (not shown) which provides structural support to the top electrode stopping it from sagging or deforming. After this comes the top nitride nozzle chamber layer 235 which forms the rest of the nozzle chamber and ink supply channel. The layer 235 can be formed from the depositing and etching of a sacrificial layer and then depositing the nitride layer, etching the nozzle and etchant holes utilizing an appropriate mask before etching away the sacrificial material.
Obviously, print heads can be formed from large arrays of nozzle arrangements 210 on a single wafer which is subsequently diced into separate print heads. Ink supply can be either from the side of the wafer or through the wafer utilizing deep anisotropic etching systems such as high density low pressure plasma etching systems available from surface technology systems. Further, the corrugated portion 223 can be formed through the utilization of a half tone mask process.
One form of detailed manufacturing process which can be used to fabricate monolithic ink jet print heads operating in accordance with the principles taught by the present embodiment can proceed utilizing the following steps:
1. Using a double sided polished wafer 240, complete a 0.5 micron, one poly, 2 metal CMOS process 242. This step is shown in FIG. 5. For clarity, these diagrams may not be to scale, and may not represent a cross section though any single plane of the nozzle. FIG. 4 is a key to representations of various materials in these manufacturing diagrams, and those of other cross referenced ink jet configurations.
2. Etch the passivation layers 246 to expose the bottom electrode 244, formed of second level metal. This etch is performed using Mask 1. This step is shown in FIG. 6.
3. Deposit 50 nm of PTFE or other highly hydrophobic material.
4. Deposit 0.5 microns of sacrificial material, e.g. polyimide 248.
5. Deposit 0.5 microns of (sacrificial) photosensitive polyimide.
6. Expose and develop the photosensitive polyimide using Mask 2. This mask is a gray-scale mask which defines the concertina edge 250 of the upper electrode. The result of the etch is a series of triangular ridges at the circumference of the electrode. This concertina edge is used to convert tensile stress into bend strain, and thereby allow the upper electrode to move when a voltage is applied across the electrodes. This step is shown in FIG. 7.
7. Etch the polyimide and passivation layers using Mask 3, which exposes the contacts for the upper electrode which are formed in second level metal.
8. Deposit 0.1 microns of tantalum 252, forming the upper electrode.
9. Deposit 0.5 microns of silicon nitride (Si3N4), which forms the movable membrane of the upper electrode.
10. Etch the nitride and tantalum using Mask 4. This mask defines the upper electrode, as well as the contacts to the upper electrode. This step is shown in FIG. 8.
11. Deposit 12 microns of (sacrificial) photosensitive polyimide 254.
12. Expose and develop the photosensitive polyimide using Mask 5. A proximity aligner can be used to obtain a large depth of focus, as the line-width for this step is greater than 2 microns, and can be 5 microns or more. This mask defines the nozzle chamber walls. This step is shown in FIG. 9.
13. Deposit 3 microns of PECVD glass 256. This step is shown in FIG. 10.
14. Etch to a depth of 1 micron using Mask 6. This mask defines the nozzle rim 258. This step is shown in FIG. 11.
15. Etch down to the sacrificial layer 254 using Mask 7. This mask defines the roof of the nozzle chamber, and the nozzle 260 itself. This step is shown in FIG. 12.
16. Back-etch completely through die silicon wafer 246 (with, for example, an ASE Advanced Silicon Etcher from Surface Technology Systems) using Mask 8. This mask defines the ink inlets 262 which are etched through the wafer 240. The wafer 240 is also diced by this etch.
17. Back-etch through the CMOS oxide layer through the holes in the wafer 240. This step is shown in FIG. 13.
18. Etch the sacrificial polyimide 254. The nozzle chambers 264 are cleared, a gap is formed between the electrodes and the chips are separated by this etch. To avoid stiction, a final rinse using supercooled carbon dioxide can be used. This step is shown in FIG. 14.
19. Mount the print heads in their packaging, which may be a molded plastic former incorporating ink channels which supply the appropriate color ink to the ink inlets at the back of the wafer.
20. Connect the print heads to their interconnect systems. For a low profile connection with minimum disruption of airflow, TAB may be used. Wire bonding may also be used if the printer is to be operated with sufficient clearance to the paper.
21. Hydrophobize the front surface of the print heads.
22. Fill the completed print heads with ink 266 and test them. A filled nozzle is shown in FIG. 15.
The presently disclosed ink jet printing technology is potentially suited to a wide range of printing system including: color and monochrome office printers, short run digital printers, high speed digital printers, offset press supplemental printers, low cost scanning printers high speed pagewidth printers, notebook computers with inbuilt pagewidth printers, portable color and monochrome printers, color and monochrome copiers, color and monochrome facsimile machines, combined printer, facsimile and copying machines, label printers, large format plotters, photograph copiers, printers for digital photographic “minilabs”, video printers, PHOTO CD (PHOTO CD is a registered trademark of the Eastman Kodak Company) printers, portable printers for PDAs, wallpaper printers, indoor sign printers, billboard printers, fabric printers, camera printers and fault tolerant commercial printer arrays.
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 embodiments 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.

## Claims

1. An ink jet printhead comprising:
a silicon substrate;
a CMOS layer comprising drive and control circuitry, said CMOS layer being formed on said silicon substrate;
a passivation layer covering said CMOS layer; and
a plurality of nozzles mounted on said passivation layer, each nozzle comprising:
a chamber adapted to contain an ejectable liquid; and,
at least one droplet ejection actuator associated with each of the chambers respectively, the droplet ejection actuator being electrically connected to the drive circuitry and adapted to eject a droplet of the ejectable liquid from the nozzle,


wherein each chamber comprises a roof and sidewalls extending from said passivation layer to said roof, wherein said roof and said sidewalls are both comprised of a glass material.

2. An ink jet printhead according to claim 1, wherein the glass material is silicon nitride.

3. An ink jet printhead according to claim 1, wherein the printhead is a pagewidth printhead.

4. An ink jet printhead according to claim 1, wherein the glass material is deposited by plasma enhanced chemical vapor deposition (PECVD).