U.S. patent application number 11/473842 was filed with the patent office on 2006-10-26 for method for fabricating a monolithic fluid injection device.
This patent application is currently assigned to BENQ CORPORATION. Invention is credited to Wei-Lin Chen, Hung-Sheng Hu, In-Yao Lee.
Application Number | 20060236537 11/473842 |
Document ID | / |
Family ID | 32924645 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060236537 |
Kind Code |
A1 |
Chen; Wei-Lin ; et
al. |
October 26, 2006 |
Method for fabricating a monolithic fluid injection device
Abstract
A method for fabricating a monolithic fluid injection device.
The method includes providing a substrate with a patterned
sacrificial layer thereon. Next, a patterned support layer and a
patterned resistive layer, as a heating element, are formed on the
substrate sequentially. A patterned insulating layer having a
heating element contact via and a first opening is formed on the
support layer. A patterned conductive layer is formed on the
support layer and fills the heating element contact via as a signal
transmitting circuit. A patterned protective layer having a signal
transmitting circuit contact via and a second opening corresponding
to the first opening is formed on the substrate. A manifold is
formed by wet etching the back of the substrate to expose the
sacrificial layer. A chamber is formed by removing the sacrificial
layer in the wet etching process. Finally, an opening connecting
the chamber is formed by etching the support layer along the second
opening.
Inventors: |
Chen; Wei-Lin; (Taipei,
TW) ; Hu; Hung-Sheng; (Kaohsiung, TW) ; Lee;
In-Yao; (Taipei, TW) |
Correspondence
Address: |
QUINTERO LAW OFFICE
1617 BROADWAY, 3RD FLOOR
SANTA MONICA
CA
90404
US
|
Assignee: |
BENQ CORPORATION
TAOYUAN
TW
|
Family ID: |
32924645 |
Appl. No.: |
11/473842 |
Filed: |
June 22, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10868605 |
Jun 15, 2004 |
7089665 |
|
|
11473842 |
Jun 22, 2006 |
|
|
|
Current U.S.
Class: |
29/890.01 ;
29/25.35; 347/44; 347/65 |
Current CPC
Class: |
B41J 2/1639 20130101;
Y10T 29/49128 20150115; B41J 2/1628 20130101; Y10T 29/49401
20150115; B41J 2/1629 20130101; Y10T 29/49346 20150115; B41J 2/1601
20130101; B41J 2/14137 20130101; Y10T 29/49169 20150115; Y10T 29/42
20150115; B41J 2/1631 20130101; Y10T 29/49126 20150115; B41J 2/1642
20130101; Y10T 29/4913 20150115; B41J 2/1646 20130101 |
Class at
Publication: |
029/890.01 ;
347/044; 029/025.35; 347/065 |
International
Class: |
H04R 17/00 20060101
H04R017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 16, 2003 |
TW |
TW92116226 |
Claims
1-13. (canceled)
14. A method for fabricating a monolithic fluid injection device,
comprising the steps of: providing a substrate having a first
surface and a second surface; forming a patterned sacrificial layer
on the first surface of the substrate; forming a patterned
structure layer on the first surface of the substrate and covering
the patterned sacrificial layer; forming a patterned resistive
layer on the structure layer as a heater; forming a patterned
insulating layer on the structure layer, the patterned insulating
layer having a heater contact opening, wherein the heater contact
opening exposing at least part of the heater; forming a patterned
conductive layer overlying the structure layer and connecting the
heater via the heater contact opening to form a signal transmitting
circuit; forming a patterned protective layer overlying the
substrate and covering the insulating layer and the conductive
layer; forming a fluid channel in the second surface of the
substrate, opposing the first surface, and exposing the sacrificial
layer; removing the sacrificial layer to form a fluid chamber; and
etching the protective layer, the insulating layer, and the
structure layer to form an orifice connecting the fluid
chamber.
15. The method as claimed in claim 14, wherein the patterned
protective layer further comprises a signal transmitting circuit
contact opening, the signal transmitting circuit contact opening
exposing at least part of the signal transmitting circuit.
16. The method as claimed in claim 15, wherein the signal
transmitting circuit contact opening and the orifice are formed
simultaneously.
17. A method for fabricating a monolithic fluid injection device,
comprising the steps of: providing a substrate having a first
surface and a second surface; forming a patterned sacrificial layer
on the first surface of the substrate; forming a patterned
structure layer on the first surface of the substrate and covering
the patterned sacrificial layer; forming a patterned resistive
layer on the structure layer as a heater; forming a patterned
insulating layer on the structure layer, the patterned insulating
layer having a heater contact opening, wherein the heater contact
opening exposing at least part of the heater; forming a patterned
conductive layer overlying the structure layer and filling the
heater contact opening to form a signal transmitting circuit;
forming a patterned protective layer overlying the substrate and
covering the insulating layer and the conductive layer; etching at
least the protective layer and the insulating layer to form an
opening; forming a fluid channel in the second surface of the
substrate, opposing the first surface, and exposing the sacrificial
layer; removing the sacrificial layer to form a fluid chamber; and
etching the structure layer along the opening to form an orifice
connecting the fluid chamber.
18. The method as claimed in claim 17, wherein the patterned
protective layer further comprises a signal transmitting circuit
contact opening, wherein the signal transmitting circuit contact
opening exposing at least part of the signal transmitting
circuit.
19. The method as claimed in claim 18, wherein the signal
transmitting circuit contact opening and the second opening are
formed simultaneously.
20. The method as claimed in claim 17, wherein forming the opening
includes etching part of the structure layer.
21. A method for fabricating a monolithic fluid injection device,
comprising the steps of: providing a substrate having a first
surface and a second surface; forming a patterned sacrificial layer
on the first surface of the substrate; forming a patterned
structure layer on the first surface of the substrate and covering
the patterned sacrificial layer; forming a conductive layer on the
structure layer; forming a patterned resistive layer on the
conductive layer as a heater; patterning the conductive layer to
form a signal transmitting circuit; forming a protective layer
overlying the substrate and covering the structure layer, the
conductive layer, and the resistive layer; etching the protective
layer to form an opening; forming a fluid channel in the second
surface of the substrate, opposing the first surface, and exposing
the sacrificial layer; removing the sacrificial layer to form a
fluid chamber; and etching the structure layer along the opening to
form an orifice connecting the fluid chamber.
22. The method as claimed in claim 21, wherein the patterned
protective layer further comprises a signal transmitting circuit
contact opening, the signal transmitting circuit contact opening
exposing at least part of the signal transmitting circuit.
23. The method as claimed in claim 22, wherein the signal
transmitting circuit contact opening and the opening are formed
simultaneously.
24. A method for fabricating a monolithic fluid injection device,
comprising the steps of: providing a substrate having a first
surface and a second surface; forming a patterned sacrificial layer
on the first surface of the substrate; forming a patterned
structure layer on the first surface of the substrate and covering
the patterned sacrificial layer; forming a conductive layer on the
structure layer; forming a patterned resistive layer on the
conductive layer as a heater; patterning the conductive layer to
form a signal transmitting circuit; forming a protective layer
overlying the substrate and covering the structure layer, the
conductive layer, and the resistive layer; forming a fluid channel
on a second surface of the substrate, opposing the first surface,
and exposing the sacrificial layer; removing the sacrificial layer
to form a fluid chamber; and etching the protective layer and the
structure layer sequentially to form an orifice connecting the
fluid chamber.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to thermal ink-jet (TIJ)
technology, and more particularly, to a method for fabricating a
monolithic fluid injection device.
[0003] 2. Description of the Related Art
[0004] The conventional fabrication technique of a monolithic fluid
injection device typically includes standard integrated circuit
(IC) technology and micro-electro-mechanical system (MEMS)
technology for both front-end and back-end processes. The front-end
process comprises formation of wafer driving circuits and heating
elements in an IC foundry. The subsequent back-end process forms
fluid chambers and orifices on said wafer in a MEMS foundry.
[0005] Both the IC and MEMS processes require one or several
thin-film processing techniques, such as metal deposition,
dielectric deposition, or etching of dielectric openings.
Production costs and the probability of defects, however, increase
with repeated thin-film processes.
[0006] Conventionally, a monolithic fluid injection device with
various components, such as a fluid chamber, a heater, a driving
circuit, and an orifice, is formed on a silicon wafer using a MEMS
process without requiring packaging and thus results in higher
yield and lower cost.
[0007] FIGS. 1A and 1B are schematic illustrations of a
conventional monolithic fluid injection device fabrication process,
wherein FIG. 1A shows the front-end IC process and FIG. 1B shows
the back-end MEMS process. Referring to FIG. 1A, a substrate 10
(e.g., silicon wafer) having a first surface and a second surface
is provided, and a monolithic fluid injection device is formed
thereon. In a typical processing sequence, a patterned sacrificial
layer 20 is formed on the first surface of the substrate 10. A
patterned structure layer 30 is formed on the first surface of the
substrate 10 and covers the patterned sacrificial layer 20. A
patterned resistive layer 40 is formed on the structure layer 30 as
a heater. A patterned insulating layer 50 having a heater contact
opening 45 is formed over the structure layer 30. A patterned
conductive layer 60 is formed overlying the structure layer 30 and
fills the heater contact opening 45 as a signal transmitting
circuit 62. A patterned protective layer 70, having a signal
transmitting circuit contact opening and covering the insulating
layer 50 and the conductive layer 60, is formed overlying the
substrate 10.
[0008] Referring to FIG. 1B, the IC processed wafer is then
subjected to wet etching. A fluid channel 80 is formed in the
second surface of the substrate 10 and exposes the sacrificial
layer 20. The sacrificial layer 20 is then removed to form a fluid
chamber 90. Thereafter the protective layer 70, the insulating
layer 50, the structure layer 30, an orifice 90 connecting the
fluid chamber 95 are formed sequentially by lithographic etching.
Thus, formation of a monolithic fluid injection device is
complete.
[0009] The above described formation of the orifice 90 minimally
requires etching of the protective layer 70, the insulating layer
50, and the structure layer 30. The front-end process, however,
also requires etching of the protective layer 70 and the insulating
layer 50 to form an electrical connection between the signal
transmitting circuit 62 and the heater 40 to form a signal
transmitting contact.
[0010] A monolithic fluid injection device combining IC and MEMS
processes is disclosed in U.S. Pat. No. 6,102,530. In this method,
a structure layer is suspended over the fluid chamber; hence, the
process must be precisely controlled to improve production yield
and reliability.
SUMMARY OF THE INVENTION
[0011] An object of the present invention is to provide a less
complex method of fabricating a monolithic fluid injection device.
By merging part of back-end MEMS process with the front-end IC
process, overall process efficiency is improved.
[0012] According to the object mentioned above, the present
invention provides a method for fabricating a monolithic fluid
injection device. A substrate having a first surface and a second
surface is provided. A patterned sacrificial layer is formed on the
first surface of the substrate. A patterned structure layer is
formed on the first surface of the substrate and covers the
patterned sacrificial layer. A patterned resistive layer is formed
on the structure layer as a heater. A patterned insulating layer
having a heater contact opening and a first opening is formed on
the structure layer, wherein at least a portion of the heater is
exposed through the heater contact opening. A patterned conductive
layer is formed overlying the structure layer and connecting the
heater via the heater contact opening to form a signal transmitting
circuit. A patterned protective layer having a signal transmitting
circuit contact opening and a second opening corresponding to the
first opening is formed overlying the substrate and covers the
insulating layer and the conductive layer. A fluid channel in the
second surface of the substrate, opposing the first surface, is
formed and exposes the sacrificial layer. The sacrificial layer is
removed to form a fluid chamber. The structure layer is etched
along the second and the first opening to form an orifice
connecting the fluid chamber.
[0013] According to the object mentioned above, the present
invention provides another method for fabricating a monolithic
fluid injection device. A substrate having a first surface and a
second surface is provided. A patterned sacrificial layer is formed
on the first surface of the substrate. A patterned structure layer
is formed on the first surface of the substrate and covers the
patterned sacrificial layer. A patterned resistive layer is formed
on the structure layer as a heater. A patterned insulating layer
having a heater contact opening is formed on the structure layer,
wherein at least a portion of the heater is exposed through the
heater contact opening. A patterned conductive layer is formed
overlying the structure layer and connecting the heater via the
heater contact opening to form a signal transmitting circuit. A
patterned protective layer is formed overlying the substrate and
covers the insulating layer and the conductive layer. A fluid
channel in the second surface of the substrate, opposing the first
surface, is formed and exposes the sacrificial layer. The
sacrificial layer is removed to form a fluid chamber. The
protective layer, the insulating layer, and the structure layer are
etched to form an orifice connecting the fluid chamber
[0014] The present invention provides still another method for
fabricating a monolithic fluid injection device. A substrate having
a first surface and a second surface is provided. A patterned
sacrificial layer is formed on the first surface of the substrate.
A patterned structure layer is formed on the first surface of the
substrate and covers the patterned sacrificial layer. A patterned
resistive layer is formed on the structure layer as a heater. A
patterned insulating layer having a heater contact opening is
formed on the structure layer, wherein at least a portion of the
heater is exposed through the heater contact opening. A patterned
conductive layer is formed overlying the structure layer and fills
the heater contact opening to form a signal transmitting circuit. A
patterned protective layer is formed overlying the substrate and
covers the insulating layer and the conductive layer. The
protective layer and the insulating layer are etched to form an
opening. A fluid channel is formed in the second surface of the
substrate, opposing the first surface, and exposes the sacrificial
layer. The sacrificial layer is removed to form a fluid chamber.
The structure layer is etched along the opening to form an orifice
connecting the fluid chamber
[0015] The present invention further provides another method for
fabricating a monolithic fluid injection device. A substrate having
a first surface and a second surface is provided. A patterned
sacrificial layer is formed on the first surface of the substrate.
A patterned structure layer is formed on the first surface of the
substrate and covers the patterned sacrificial layer. A conductive
layer is formed on the structure layer. A patterned resistive layer
is formed on the conductive layer as a heater. The conductive layer
is patterned to form a signal transmitting circuit. A protective
layer is formed overlying the substrate and covers the structure
layer, the conductive layer, and the resistive layer. The
protective layer is etched to form an opening. A fluid channel is
formed in the second surface of the substrate, opposing the first
surface, and exposes the sacrificial layer. The sacrificial layer
is removed to form a fluid chamber. The structure layer is etched
along the opening to form an orifice connecting the fluid
chamber.
[0016] The present invention provides yet another method for
fabricating a monolithic fluid injection device. A substrate having
a first surface and a second surface is provided. A patterned
sacrificial layer is formed on the first surface of the substrate.
A patterned structure layer is formed on the first surface of the
substrate and covers the patterned sacrificial layer. A conductive
layer is formed on the structure layer. A patterned resistive layer
is formed on the conductive layer as a heater. The conductive layer
is patterned to form a signal transmitting circuit. A protective
layer is formed overlying the substrate and covers the structure
layer, the conductive layer, and the resistive layer. A fluid
channel is formed on a second surface of the substrate, opposing
the first surface, and exposing the sacrificial layer. The
sacrificial layer is removed to form a fluid chamber. The
protective layer and the structure layer is etched sequentially to
form an orifice connecting the fluid chamber
[0017] The advantage of the present invention is providing a hybrid
integrated process for fabricating the orifice of a monolithic
fluid injection device. More specifically, integrating portions of
the back-end MEMS and front-end IC processes, reduces process cost
improves yield.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The present invention can be more fully understood by
reading the subsequent detailed description in conjunction with the
examples and references made to the accompanying drawings,
wherein:
[0019] FIGS. 1A and 1B are schematic illustrations of the
conventional monolithic fluid injection device fabrication process,
wherein FIG. 1A shows the front-end IC process and FIG. 1B shows
the back-end MEMS process;
[0020] FIGS. 2A to 2F are cross-sections illustrating the
manufacture of a monolithic fluid injection device according to the
first embodiment of the invention, wherein FIGS. 2A to 2D show the
front-end IC process and FIGS. 2E to 2F show the back-end MEMS
process;
[0021] FIGS. 3A to 3C are cross-sections illustrating the
manufacture of a monolithic fluid injection device according to the
second embodiment of the invention, wherein FIG. 3A shows the
front-end IC process and FIGS. 3B and 2C show the back-end MEMS
process;
[0022] FIGS. 4A to 4C are cross-sections illustrating the
manufacture of a monolithic fluid injection device according to the
third embodiment of the invention, wherein FIG. 4A shows the
front-end IC process and FIGS. 4B and 4C show the back-end MEMS
process; and
[0023] FIGS. 5A to 5D are cross-sections illustrating the
manufacture of a monolithic fluid injection device according to the
fourth embodiment of the invention, wherein FIGS. 5A and 5B show
the front-end IC process and FIGS. 5C and 5D show the back-end MEMS
process.
DETAILED DESCRIPTION OF THE INVENTION
First Embodiment
[0024] FIGS. 2A to 2F are cross-sections illustrating the
manufacture of a monolithic fluid injection device according to the
first embodiment of the invention, wherein FIGS. 2A to 2D show the
front-end IC process and FIGS. 2E to 2F show the back-end MEMS
process. Referring to FIG. 2A, a patterned sacrificial layer 120 is
formed on a substrate 100 (e.g. a silicon wafer) having a first
surface and a second surface. The sacrificial layer 120 comprises
borophosphosilicate glass (BPSG), phosphosilicate glass (PSG), or
silicon oxide. The sacrificial layer 120 may be deposited using a
CVD or LPCVD process. In a typical processing sequence, a structure
layer 130 is conformally formed on the first surface of the
substrate 100 and covers the patterned sacrificial layer 120. The
structure layer 130 comprises silicon oxide. The structure layer
130 may be deposited using a CVD or a LPCVD process. A patterned
resistive layer 140 is formed on the structure layer 130 as a
heater. The resistive layer 140 comprises HfB.sub.2, TaAl, TaN, or
TiN. The resistive layer 140 may be deposited using a PVD process,
such as evaporation, sputtering, or reactive sputtering, A blanket
insulating layer 150 is formed on the structure layer 130.
[0025] Referring to FIG. 2B, lithographic etching is performed to
define the insulating layer 150 to form a heater contact opening
145 and a first opening 195a. The first opening 195a may be a
precursor of an orifice of a monolithic fluid injection device.
[0026] Referring to FIG. 2C, a patterned conductive layer 162,
comprising Al, Cu, or alloys thereof, is formed overlying the
structure layer 130 and fills the heater contact opening 145 to
form a signal transmitting circuit 162. The conductive layer 162
may be deposited using a PVD process, such as evaporation,
sputtering, or reactive sputtering.
[0027] Referring to FIG. 2D, a protective layer 170 is formed
overlying the substrate 100. Next, lithographic etching is
performed to define the protective layer 170. Therefore, a signal
transmitting circuit contact opening 175 is formed and exposes the
underlying conductive layer 162 for subsequent packaging. The
insulating layer 150 is etched along the first opening 195a and
transformed to a second opening 195b as a precursor of the orifice
of the monolithic fluid injection device.
[0028] Referring to FIG. 2E, a fluid channel 180 is formed in the
second surface of the substrate 100 and exposes the sacrificial
layer 120. The sacrificial layer 120 is then removed to form a
fluid chamber 190.
[0029] Referring to FIG. 2F, the structure layer 130 is etched by
lithography along the second opening 195b to form an orifice 190
connecting the fluid chamber 195. The lithographic etching
comprises plasma etching, chemical dry etching, reactive ion
etching, and laser etching. Thus, formation of a monolithic fluid
injection device is complete.
Second Embodiment
[0030] FIGS. 3A to 3C are cross-sections illustrating the
manufacture of a monolithic fluid injection device according to the
second embodiment of the invention, wherein FIG. 3A shows the
front-end IC process and FIGS. 3B and 2C show the back-end MEMS
process. Referring to FIG. 3A, a patterned sacrificial layer 120 is
formed on a substrate 100 (e.g. a silicon wafer) having a first
surface and a second surface. The sacrificial layer 120 comprises
borophosphosilicate glass (BPSG), phosphosilicate glass (PSG), or
silicon oxide. The sacrificial layer 120 may be deposited using a
CVD or LPCVD process. In a typical processing sequence, a structure
layer 130 is conformally formed on the first surface of the
substrate 100 and covers the patterned sacrificial layer 120. The
structure layer 130 comprises silicon oxide. The structure layer
130 may be deposited using a CVD or LPCVD process. A patterned
resistive layer 140 is formed on the structure layer 130 as a
heater. The resistive layer 140 comprises HfB.sub.2, TaAl, TaN, or
TiN. The resistive layer 140 may be deposited using a PVD process,
such as evaporation, sputtering, or reactive sputtering. A blanket
insulating layer 150 is formed on the structure layer 130.
[0031] Next, lithographic etching is performed to define a heater
contact opening 145. Thereafter, a patterned conductive layer 162,
comprising Al, Cu, or alloys thereof, is formed overlying the
structure layer 130 and fills the heater contact opening 145 to
form a signal transmitting circuit 162. The conductive layer 162
may be deposited using a PVD process, such as evaporation,
sputtering, or reactive sputtering. A protective layer 170 is
formed overlying the substrate 100 and covers the insulating layer
150 and the signal transmitting circuit 162.
[0032] Referring to FIG. 3B, a fluid channel 180 is formed in the
second surface of the substrate 100 and exposes the sacrificial
layer 120. The sacrificial layer 120 is then removed to form a
fluid chamber 190.
[0033] Referring to FIG. 3C, lithographic etching is performed to
sequentially penetrate the protective layer 170, insulating layer
150, and the structure layer 130, forming an orifice 190 to connect
the fluid chamber 195. Alternately, a signal transmitting circuit
contact opening 175 is simultaneously formed exposing the
underlying conductive layer 162 for subsequent packaging. The
lithographic etching comprises plasma etching, chemical dry
etching, reactive ion etching, or laser etching. Thus, formation of
a monolithic fluid injection device is complete.
Third Embodiment
[0034] FIGS. 4A to 4C are cross-sections illustrating the
manufacture of a monolithic fluid injection device according to the
third embodiment of the invention, wherein FIG. 4A shows the
front-end IC process and FIGS. 4B and 4C show the back-end MEMS
process. Referring to FIG. 2A, a patterned sacrificial layer 120 is
formed on a substrate 100 (e.g. a silicon wafer) having a first
surface and a second surface. The sacrificial layer 120 comprises
borophosphosilicate glass (BPSG), phosphosilicate glass (PSG), or
silicon oxide. The sacrificial layer 120 may be deposited using a
CVD or LPCVD process. In a typical processing sequence, a structure
layer 130 is conformally formed on the first surface of the
substrate 100 and covers the patterned sacrificial layer 120. The
structure layer 130 comprises a silicon nitride. The structure
layer 130 may be deposited using a CVD or LPCVD process. A
patterned resistive layer 140 is formed on the structure layer 130
as a heater. The resistive layer 140 comprises HfB.sub.2, TaAl,
TaN, or TiN. The resistive layer 140 may be deposited using a PVD
process, such as evaporation, sputtering, or reactive sputtering. A
blanket insulating layer 150 is formed on the structure layer 130.
Thereafter, lithographic etching is performed to define the
insulating layer 150 and form a heater contact opening 145.
[0035] Next, a patterned conductive layer 162, comprising Al, Cu,
or alloys thereof, is formed overlying the structure layer 130 and
fills the heater contact opening 145 to form a signal transmitting
circuit 162. The conductive layer 162 may be deposited using a PVD
process, such as evaporation, sputtering, or reactive sputtering. A
protective layer 170 is formed overlying the substrate 100.
Lithographic etching is then performed to define the protective
layer 170, thereby forming a signal transmitting circuit contact
opening 175 and exposing the underlying conductive layer 162 for
subsequent packaging. The protective layer 170 and the insulating
layer 150 are etched to form a second opening 195b as a precursor
of the orifice of the monolithic fluid injection device.
[0036] Referring to FIG. 4B, a fluid channel 180 is formed in the
second surface of the substrate 100 and exposes the sacrificial
layer 120. The sacrificial layer 120 is then removed to form a
fluid chamber 190.
[0037] Referring to FIG. 4C, the structure layer 130 is etched by
lithography along the second opening 195b to form an orifice 190
connecting the fluid chamber 195. Thus, formation of a monolithic
fluid injection device is complete.
Fourth Embodiment
[0038] FIGS. 5A to 5D are cross-sections illustrating the
manufacture of a monolithic fluid injection device according to the
fourth embodiment of the invention, wherein FIGS. 5A and 5B show
the front-end IC process and FIGS. 5C and 5D show the back-end MEMS
process. Referring to FIG. 5A, a patterned sacrificial layer 120 is
formed on a substrate 100 (e.g. a silicon wafer) having a first
surface and a second surface. The sacrificial layer 120 comprises
borophosphosilicate glass (BPSG), phosphosilicate glass (PSG), or
silicon oxide. The sacrificial layer 120 may be deposited using a
CVD or LPCVD process. In a typical processing sequence, a structure
layer 130 is conformally formed on the first surface of the
substrate 100 and covers the patterned sacrificial layer 120. The
structure layer 130 is composed of silicon oxide. The structure
layer 130 may be deposited using a CVD or LPCVD process. Next, a
conductive layer 162, comprising Al, Cu, or alloys thereof, is
formed overlying the structure layer 130. The conductive layer 162
may be deposited using a PVD process, such as evaporation,
sputtering, or reactive sputtering. A resistive layer 140 is formed
on the structure layer 130 as a heater. The resistive layer 140
comprises HfB.sub.2, TaAl, TaN, or TiN. The resistive layer 140 may
be deposited using a PVD process, such as evaporation, sputtering,
or reactive sputtering. The resistive layer 140 is patterned to
form a signal transmitting circuit 162. A blanket protective layer
170 is formed on the structure layer 130 and covers the resistive
layer 140 and the signal transmitting circuit 162.
[0039] Referring to FIG. 5B, lithographic etching is performed to
define the protective layer 170 to form a heater contact opening
145. During the etching process, the signal transmitting circuit
162 may be used as an etch stopper. Simultaneously, the protective
layer 170 is etched to form an opening 195b as a precursor of the
orifice of the monolithic fluid injection device.
[0040] Referring to FIG. 5C, a fluid channel 180 is formed in the
second surface of the substrate 100 and exposes the sacrificial
layer 120. The sacrificial layer 120 is then removed to form a
fluid chamber 190.
[0041] Referring to FIG. 5D, the structure layer 130 is etched by
lithography along the opening 195b to form an orifice 190
connecting the fluid chamber 195. The lithographic etching
comprises plasma etching, chemical dry etching, reactive ion
etching, and laser etching. Thus, formation of a monolithic fluid
injection device is complete.
Fifth Embodiment
[0042] Referring again to FIG. 5A, a patterned sacrificial layer
120 is formed on a substrate 100 (e.g. a silicon wafer) having a
first surface and a second surface. The sacrificial layer 120
comprises borophosphosilicate glass (BPSG), phosphosilicate glass
(PSG), or silicon oxide. The sacrificial layer 120 may be deposited
using a CVD or LPCVD process. In a typical processing sequence, a
structure layer 130 is conformally formed on the first surface of
the substrate 100 and covers the patterned sacrificial layer 120.
The structure layer 130 comprises silicon oxide. The structure
layer 130 may be deposited using a CVD or LPCVD process. Next, a
conductive layer 162, comprising Al, Cu, or alloys thereof, is
formed overlying the structure layer 130. The conductive layer 162
may be deposited using a PVD process, such as evaporation,
sputtering, or reactive sputtering. A resistive layer 140 is formed
on the structure layer 130 as a heater. The resistive layer 140
comprises HfB.sub.2, TaAl, TaN, or TiN. The resistive layer 140 may
be deposited using a PVD process, such as evaporation, sputtering,
or reactive sputtering. The resistive layer 140 is patterned to
form a signal transmitting circuit 162. A blanket protective layer
170 is formed on the structure layer 130 and covers the resistive
layer 140 and the signal transmitting circuit 162.
[0043] Referring again to FIG. 5C, a fluid channel 180 is formed in
the second surface of the substrate 100 and exposes the sacrificial
layer 120. The sacrificial layer 120 is then removed to form a
fluid chamber 190.
[0044] Next, lithographic etching is performed to define the
protective layer 170, and form a heater contact opening 145. During
the etching process, the signal transmitting circuit 162 may be
used as an etch stopper. The protective layer 170 and the structure
layer 130 are simultaneously etched to form an orifice 190
connecting the fluid chamber 195. The lithographic etching
comprises plasma etching, chemical dry etching, reactive ion
etching, and laser etching. Thus, formation of a monolithic fluid
injection device is complete.
[0045] The primary advantage of the described preferred embodiments
lies in the hybrid integrated process for fabricating the orifice
of a monolithic fluid injection device.
[0046] More specifically, the invention integrates portions of the
back-end MEMS and front-end IC processes, thus reducing overall
process costs and increasing yield. Additionally, the orifice of
the monolithic fluid injection device can also be improved.
[0047] Finally, while the invention has been described by way of
example and in terms of the above, it is to be understood that the
invention is not limited to the disclosed embodiments. On the
contrary, it is intended to cover various modifications and similar
arrangements as would be apparent to those skilled in the art.
Therefore, the scope of the appended claims should be accorded the
broadest interpretation so as to encompass all such modifications
and similar arrangements.
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