U.S. patent application number 11/063816 was filed with the patent office on 2005-08-25 for fluid actuating apparatus and method for manufacturing a fluid actuating apparatus, and electrostatically-actuated fluid discharge apparatus and process for producing an electrostatically-actuated fluid discharge apparatus.
This patent application is currently assigned to Sony Corporation. Invention is credited to Yamaguchi, Masanari.
Application Number | 20050183950 11/063816 |
Document ID | / |
Family ID | 34858232 |
Filed Date | 2005-08-25 |
United States Patent
Application |
20050183950 |
Kind Code |
A1 |
Yamaguchi, Masanari |
August 25, 2005 |
Fluid actuating apparatus and method for manufacturing a fluid
actuating apparatus, and electrostatically-actuated fluid discharge
apparatus and process for producing an electrostatically-actuated
fluid discharge apparatus
Abstract
A fluid actuating apparatus is proposed, which includes: a
diaphragm for providing a pressure change in fluid; a
diaphragm-side electrode, formed for the diaphragm, for actuating
the diaphragm; a substrate-side electrode formed so that it faces
the diaphragm-side electrode; a space formed between the
diaphragm-side electrode and the substrate-side electrode; and a
support post, formed on the substrate-side electrode, for
supporting the diaphragm-side electrode through the space. where
the diaphragm-side electrode is formed so that it passes through
the support post and extends to and covers part of the bottom of
the support post.
Inventors: |
Yamaguchi, Masanari;
(Kanagawa, JP) |
Correspondence
Address: |
SONNENSCHEIN NATH & ROSENTHAL LLP
P.O. BOX 061080
WACKER DRIVE STATION, SEARS TOWER
CHICAGO
IL
60606-1080
US
|
Assignee: |
Sony Corporation
|
Family ID: |
34858232 |
Appl. No.: |
11/063816 |
Filed: |
February 23, 2005 |
Current U.S.
Class: |
204/252 |
Current CPC
Class: |
B41J 2/14314
20130101 |
Class at
Publication: |
204/252 |
International
Class: |
C25B 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2004 |
JP |
P2004-049131 |
Claims
What is claimed is:
1. A fluid actuating apparatus comprising: a diaphragm for
providing a pressure change in fluid; a diaphragm-side electrode,
formed for said diaphragm, for actuating said diaphragm; a
substrate-side electrode formed so that it faces said
diaphragm-side electrode; a space formed between said
diaphragm-side electrode and said substrate-side electrode; and a
support post, formed on said substrate-side electrode, for
supporting said diaphragm-side electrode through said space;
wherein said diaphragm-side electrode is formed so that it passes
through said support post and extends to and covers part of the
bottom of said support post.
2. A method for manufacturing a fluid actuating apparatus, said
method comprising the steps of: forming a substrate-side electrode
on a substrate; forming a first insulating film on said
substrate-side electrode; forming a sacrifice layer pattern for
forming a space in a region above said first insulating film,
excluding a support post-forming region; forming a second
insulating film for covering said sacrifice layer pattern; forming
a diaphragm-side electrode through said second insulating film on
the upper surface of said sacrifice layer pattern, the sidewall of
said sacrifice layer pattern, and part of the bottom of said
support post-forming region; forming a third insulating film for
covering said diaphragm-side electrode; forming, on said third
insulating film, a diaphragm for providing a pressure change in
fluid; and removing said sacrifice layer pattern to form a space in
a region formed by removing said sacrifice layer pattern, and
further forming, in said support post-forming region formed at the
side portion of said space, a support post from said second
insulating film, said diaphragm-side electrode, said third
insulating film, and said diaphragm.
3. An electrostatically-actuated fluid discharge apparatus
comprising: a diaphragm for providing a pressure change in fluid; a
diaphragm-side electrode, formed for said diaphragm, for actuating
said diaphragm; a substrate-side electrode formed so that it faces
said diaphragm-side electrode; a space formed between said
diaphragm-side electrode and said substrate-side electrode; and a
support post, formed on said substrate-side electrode, for
supporting said diaphragm-side electrode through said space;
wherein said diaphragm-side electrode is formed so that it passes
through said support post and extends to and covers part of the
bottom of said support post, and said diaphragm has formed thereon
a pressure chamber having a fluid feed section and a fluid
discharge section.
4. A method for manufacturing an electrostatically-actuated fluid
discharge apparatus, said method comprising the steps of: forming a
substrate-side electrode on a substrate; forming a first insulating
film on said substrate-side electrode; forming a sacrifice layer
pattern for forming a space in a region above said first insulating
film, excluding a support post-forming region; forming a second
insulating film for covering said sacrifice layer pattern; forming
a diaphragm-side electrode through said second insulating film on
the upper surface of said sacrifice layer pattern, the sidewall of
said sacrifice layer pattern, and part of the bottom of said
support post-forming region; forming a third insulating film for
covering said diaphragm-side electrode; forming, on said third
insulating film, a diaphragm for providing a pressure change in
fluid; removing said sacrifice layer pattern to form a space in a
region formed by removing said sacrifice layer pattern, and further
forming, in said support post-forming region formed at the side
portion of said space, a support post from said second insulating
film, said diaphragm-side electrode, said third insulating film,
and said diaphragm; and forming, on said diaphragm through said
third insulating film, a pressure chamber having a fluid feed
section and a fluid discharge section.
5. A fluid actuating apparatus comprising: a diaphragm for
providing a pressure change in a fluid; a diaphragm-side electrode,
formed for said diaphragm, for actuating said diaphragm; a
substrate-side electrode formed so that it faces said
diaphragm-side electrode; a space formed between said
diaphragm-side electrode and said substrate-side electrode; and a
support post, formed on said substrate-side electrode, for
supporting said diaphragm-side electrode through said space;
wherein said diaphragm-side electrode is formed so that it extends
from said support post to another.
6. A method for manufacturing a fluid actuating apparatus, said
method comprising the steps of: forming a substrate-side electrode
on a substrate; forming a first insulating film on said
substrate-side electrode; forming a sacrifice layer pattern for
forming a space in a region above said first insulating film,
excluding a support post-forming region; forming a second
insulating film for covering said sacrifice layer pattern; forming
a diaphragm-side electrode through said second insulating film on
said sacrifice layer pattern including a portion between said
support post-forming regions; forming a third insulating film for
covering said diaphragm-side electrode; forming, on said third
insulating film, a diaphragm for providing a pressure change in
fluid; and removing said sacrifice layer pattern to form a space in
a region formed by removing said sacrifice layer pattern, and
further forming, in said support post-forming region formed at the
side portion of said space, a support post from said second
insulating film, said third insulating film, and said
diaphragm.
7. An electrostatically-actuated fluid discharge apparatus
comprising: a diaphragm for providing a pressure change in fluid; a
diaphragm-side electrode, formed for said diaphragm through an
insulating film, for actuating said diaphragm; a substrate-side
electrode formed so that it faces said diaphragm-side electrode; a
space formed between said diaphragm-side electrode and said
substrate-side electrode; and a support post, formed on said
substrate-side electrode, for supporting said diaphragm-side
electrode through said space, wherein said diaphragm-side electrode
is formed so that it extends from said support post to another, and
said diaphragm has formed thereon a pressure chamber having a fluid
feed section and a fluid discharge section.
8. A method for manufacturing an electrostatically-actuated fluid
discharge apparatus, said method comprising the steps of: forming a
substrate-side electrode on a substrate; forming a first insulating
film on said substrate-side electrode; forming a sacrifice layer
pattern for forming a space in a region above said first insulating
film, excluding a support post-forming region; forming a second
insulating film for covering said sacrifice layer pattern; forming
a diaphragm-side electrode through said second insulating film on
said sacrifice layer pattern including a portion between said
support post-forming regions; forming a third insulating film for
covering said diaphragm-side electrode; forming, on said third
insulating film, a diaphragm for providing a pressure change in
fluid; removing said sacrifice layer pattern to form a space in a
region formed by removing said sacrifice layer pattern, and further
forming, in said support post-forming region formed at the side
portion of said space, a support post from said second insulating
film, said third insulating film, and said diaphragm; and forming,
on said diaphragm through said third insulating film, a pressure
chamber having a fluid feed section and a fluid discharge section.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present invention contains subject mater related to
Japanese Patent Application JP2004-049131 filed in the Japanese
Patent Office on Feb. 25, 2004, the entire contents of which being
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a fluid actuating
apparatus, which can prevent a stress from concentrating on a
portion between an electrode and a support post wherein the stress
is caused due to deformation of a diaphragm when a voltage is
applied to the electrode for vibrating the diaphragm, while
securing repulsion force of the diaphragm, and a method for
manufacturing the fluid actuating apparatus, and an
electrostatically-actuated fluid discharge apparatus using the
fluid actuating apparatus and a method for manufacturing the
electrostatically-actuated fluid discharge apparatus.
[0004] 2. Description of Related Art
[0005] In a printer which meets the demands of printing images
having quality as high as photography at high speed and with high
resolution, an ink-jet printer head for discharging an ink in a
very small volume at a level of pl (picolitter) is widely used. For
meeting the demands of printing higher-quality images at high speed
and with high resolution, it is desired that nozzles are arranged
with higher density in future without increasing the power
consumption and without sacrificing the discharge performance.
[0006] Conventionally, the method for actuating a chemical agent in
a very small volume employed in the ink-jet printer head includes,
in respect of a fluid in a very small volume (ink in a very small
volume) held in an ink holding space (so-called cavity), a
resistance heating method and a diaphragm method. The resistance
heating method is a method in which a fluid in a cavity is
discharged through a nozzle by gas (bubbles) generated by
resistance heating. The diaphragm method is a method in which a
fluid is discharged through a nozzle by a pressure application
means (so-called diaphragm) using a piezoelectric element or the
like.
[0007] The resistance heating method can be prepared by a
semiconductor process and hence the cost is low, and a resistance
heating element having a very small size can be produced, and
therefore nozzles with high density are advantageously formed, but
the use of Joule heat generated by an electric current increases
both the number of nozzles and the power consumption, and further
the resistance heating element must be cooled, making it difficult
to increase the discharge frequency.
[0008] On the other hand, the diaphragm method using a
piezoelectric effect is classified into a laminate piezoelectric
type and a single-layer piezoelectric type, and, in the laminate
piezoelectric type, a piezoelectric actuator and a diaphragm are
laminated together and then subjected to isolation by cutting, and
therefore a semiconductor process cannot be used, and the process
for fabrication is complicated, thus increasing the cost. In
addition, the actuation distance is small, and hence there is a
need to increase the actuation area to a length at a level of
millimeter (mm) to secure the actuation capacity, thus making it
difficult to increase the density. Further, there is a problem in
that a change of the design is not easy.
[0009] The ink-jet head using a conventional electrostatic
actuation method is prepared by forming a diaphragm from a Si
substrate which is shaped to be thin by etching, and laminating
together the diaphragm and a substrate of glass or the like having
a lower electrode formed thereon. In this method, it is difficult
to control the thickness of the diaphragm and its uniformity. In
addition, the diaphragm is formed from a Si substrate by etching
and hence almost all the thickness of the Si substrate is removed,
and therefore the productivity is poor, and a diaphragm having a
uniform thickness as small as several .mu.m or less cannot be
formed and therefore, for achieving actuation with a low voltage,
the short side of the diaphragm is required to be longer, thus
making it difficult to increase the density. Further, in lamination
of the substrates, the joint surface is required to be smooth with
high precision to secure a joint area for the lamination, and a
lamination accuracy of .+-.several .mu.m is needed, thus making it
impossible to increase the density. Furthermore, there is a problem
in that handling of a substrate having a thickness of about 0.1 to
0.2 mm is not easy.
[0010] For this reason, there is desired a fluid actuating
apparatus using an electrostatic method, which is advantageous in
that the diaphragm is formed by a semiconductor fabrication process
and hence the thickness of the diaphragm can be easily controlled,
no lamination of substrates is required, the density of the
actuating portions can be increased, high fluid actuating force can
be obtained, and the yield is high and a change of the design is
easy, thus improving the productivity.
[0011] In the single-layer piezoelectric type, a semiconductor
process can be almost always used, and the cost is low, as compared
to that for the laminate type, and the power consumption can be
lowered. However, warpage is caused during the sintering of the
piezoelectric element, and it is difficult to prepare a large-size
head having an increased number of nozzles. On the other hand, in
the diaphragm method using electrostatic actuation, the power
consumption is very low, as compared to that for the resistance
heating method and the piezoelectric method, and high-speed
actuation is possible (see, for example, patent documents 1 and
2).
[0012] [Patent document 1] Unexamined Japanese Patent Application
Publication No. Hei 10-86362
[0013] [Patent document 2] Japanese Domestic Re-Publication of PCT
International Patent Application No. WO99/34979
SUMMARY OF THE INVENTION
[0014] With respect to the diaphragm method using electrostatic
actuation, the present inventors have proposed a fluid actuating
apparatus which includes a diaphragm for providing a pressure
change in fluid, a diaphragm-side electrode, formed for the
diaphragm through an insulating film, for actuating the diaphragm,
a substrate-side electrode formed so that it faces the
diaphragm-side electrode through a space, and a support post,
formed on the substrate-side electrode, for supporting the
diaphragm-side electrode through the space.
[0015] In the electrostatically-actuated fluid discharge apparatus,
the strength (repulsion force) of the diaphragm and the power
consumption are important factors. For example, with respect to the
diaphragm method using electrostatic actuation, the present
inventors have proposed a fluid actuating apparatus which includes
a diaphragm for providing a pressure change in fluid, a
diaphragm-side electrode, formed for the diaphragm through an
insulating film, for actuating the diaphragm, a substrate-side
electrode formed so that it faces the diaphragm-side electrode
through a space, and a support post, formed on the substrate-side
electrode, for supporting the diaphragm-side electrode through the
space. In this fluid actuating apparatus having a construction in
which the diaphragm-side electrode separately formed has a
rectangular form having such a size that the diaphragm-side
electrode does not extend to the support post, when a voltage is
applied, a stress due to deformation of the diaphragm concentrates
on a portion between the electrode and the support post to weaken
the diaphragm, leading to a problem in that there is a lack of the
repulsion force.
[0016] According to an embodiment of the present invention, there
is provided a fluid actuating apparatus which includes a diaphragm
for providing a pressure change in fluid; a diaphragm-side
electrode, formed for the diaphragm, for actuating the diaphragm; a
substrate-side electrode formed so that it faces the diaphragm-side
electrode; a space formed between the diaphragm-side electrode and
the substrate-side electrode; and a support post, formed on the
substrate-side electrode, for supporting the diaphragm-side
electrode through the space, wherein the diaphragm-side electrode
is formed so that it passes through the support post and extends to
and covers part of the bottom of the support post.
[0017] According to another embodiment of the present invention,
there is provided a fluid actuating apparatus which includes: a
diaphragm for providing a pressure change in a fluid; a
diaphragm-side electrode, formed for the diaphragm, for actuating
the diaphragm; a substrate-side electrode formed so that it faces
the diaphragm-side electrode; a space formed between the
diaphragm-side electrode and the substrate-side electrode; and a
support post, formed on the substrate-side electrode, for
supporting the diaphragm-side electrode through the space, wherein
the diaphragm-side electrode is formed so that it extends from the
support post to another.
[0018] According to further another embodiment of the present
invention, there is provided a method for manufacturing a fluid
actuating apparatus, which method includes the steps of forming a
substrate-side electrode on a substrate; forming a first insulating
film on the substrate-side electrode; forming a sacrifice layer
pattern for forming a space in a region above the first insulating
film, excluding a support post-forming region; forming a second
insulating film for covering the sacrifice layer pattern; forming a
diaphragm-side electrode through the second insulating film on the
upper surface of the sacrifice layer pattern, the sidewall of the
sacrifice layer pattern, and part of the bottom of the support
post-forming region; forming a third insulating film for covering
the diaphragm-side electrode; forming, on the third insulating
film, a diaphragm for providing a pressure change in fluid; and
removing the sacrifice layer pattern to form a space in a region
formed by removing the sacrifice layer pattern, and further
forming, in the support post-forming region formed at the side
portion of the space, a support post from the second insulating
film, the diaphragm-side electrode, the third insulating film, and
the diaphragm.
[0019] According to further another embodiment of the present
invention, there is provided a method for manufacturing a fluid
actuating apparatus, which method includes the steps of: forming a
substrate-side electrode on a substrate; forming a first insulating
film on the substrate-side electrode; forming a sacrifice layer
pattern for forming a space in a region above the first insulating
film, excluding a support post-forming region; forming a second
insulating film for covering the sacrifice layer pattern; forming a
diaphragm-side electrode through the second insulating film on the
sacrifice layer pattern including a portion between the support
post-forming regions; forming a third insulating film for covering
the diaphragm-side electrode; forming, on the third insulating
film, a diaphragm for providing a pressure change in fluid; and
removing the sacrifice layer pattern to form a space in a region
formed by removing the sacrifice layer pattern, and further
forming, in the support post-forming region formed at the side
portion of the space, a support post from the second insulating
film, the third insulating film, and the diaphragm.
[0020] According to further another embodiment of the present
invention, there is provided an electrostatically-actuated fluid
discharge apparatus, which includes: a diaphragm for providing a
pressure change in fluid; a diaphragm-side electrode, formed for
the diaphragm, for actuating the diaphragm; a substrate-side
electrode formed so that it faces the diaphragm-side electrode; a
space formed between the diaphragm-side electrode and the
substrate-side electrode; and a support post, formed on the
substrate-side electrode, for supporting the diaphragm-side
electrode through the space, wherein the diaphragm-side electrode
is formed so that it passes through the support post and extends to
and covers part of the bottom of the support post, wherein the
diaphragm has formed thereon a pressure chamber having a fluid feed
section and a fluid discharge section.
[0021] According to further another embodiment of the present
invention, there is provided an electrostatically-actuated fluid
discharge apparatus which includes: a diaphragm for providing a
pressure change in fluid; a diaphragm-side electrode, formed for
the diaphragm through an insulating film, for actuating the
diaphragm; a substrate-side electrode formed so that it faces the
diaphragm-side electrode; a space formed between the diaphragm-side
electrode and the substrate-side electrode; and a support post,
formed on the substrate-side electrode, for supporting the
diaphragm-side electrode through the space, wherein the
diaphragm-side electrode is formed so that it extends from the
support post to another, wherein the diaphragm has formed thereon a
pressure chamber having a fluid feed section and a fluid discharge
section.
[0022] According to further another embodiment of the present
invention, there is provided a method for manufacturing an
electrostatically-actuate- d fluid discharge apparatus, which
method includes the steps of: forming a substrate-side electrode on
a substrate; forming a first insulating film on the substrate-side
electrode; forming a sacrifice layer pattern for forming a space in
a region above the first insulating film, excluding a support
post-forming region; forming a second insulating film for covering
the sacrifice layer pattern; forming a diaphragm-side electrode
through the second insulating film on the upper surface of the
sacrifice layer pattern, the sidewall of the sacrifice layer
pattern, and part of the bottom of the support post-forming region;
forming a third insulating film for covering the diaphragm-side
electrode; forming, on the third insulating film, a diaphragm for
providing a pressure change in fluid; removing the sacrifice layer
pattern to form a space in a region formed by removing the
sacrifice layer pattern, and further forming, in the support
post-forming region formed at the side portion of the space, a
support post from the second insulating film, the diaphragm-side
electrode, the third insulating film, and the diaphragm; and
forming, on the diaphragm through the third insulating film, a
pressure chamber having a fluid feed section and a fluid discharge
section.
[0023] According to further another embodiment of the present
invention, there is provided a method for manufacturing an
electrostatically-actuate- d fluid discharge apparatus, which
method includes the steps of: forming a substrate-side electrode on
a substrate; forming a first insulating film on the substrate-side
electrode; forming a sacrifice layer pattern for forming a space in
a region above the first insulating film, excluding a support
post-forming region; forming a second insulating film for covering
the sacrifice layer pattern; forming a diaphragm-side electrode
through the second insulating film on the sacrifice layer pattern
including a portion between the support post-forming regions;
forming a third insulating film for covering the diaphragm-side
electrode; forming, on the third insulating film, a diaphragm for
providing a pressure change in fluid; removing the sacrifice layer
pattern to form a space in a region formed by removing the
sacrifice layer pattern, and further forming, in the support
post-forming region formed at the side portion of the space, a
support post from the second insulating film, the third insulating
film, and the diaphragm; and forming, on the diaphragm through the
third insulating film, a pressure chamber having a fluid feed
section and a fluid discharge section.
[0024] In the fluid actuating apparatus according to an embodiment
of the present invention, the diaphragm-side electrode is formed so
that it passes through the support post and extends to and covers
part of the bottom of the support post, or it extends from the
support post to another, and therefore, as compared to the
construction in which the diaphragm-side electrode is formed so
that it covers the whole of the bottom of the support post, the
amount of the charge, which does not contribute to deformation of
the diaphragm and which is stored on the bottom of the support
post, is small, thus suppressing a waste of the power consumption.
In addition, in the construction in which the diaphragm-side
electrode is formed so that it passes through the support post and
extends to and covers part of the bottom of the support post, with
respect to the strength of the diaphragm, there is an advantage in
that the support post has a larger thickness by the thickness of
the diaphragm-side electrode than that in the construction in which
the diaphragm-side electrode is formed so that it does not extend
to the support post, and thus the support post gets stronger.
[0025] The method for manufacturing a fluid actuating apparatus
according to another embodiment of the present invention, includes
the step for forming a diaphragm-side electrode through the second
insulating film on the upper surface of the sacrifice layer
pattern, the sidewall of the sacrifice layer pattern, and part of
the bottom of the support post-forming region, and hence the
diaphragm-side electrode is formed so that it passes through the
support post and extends to and covers part of the bottom of the
support post. Therefore, there can be produced a fluid actuating
apparatus having a construction such that, as compared to the
construction in which the diaphragm -side electrode is formed so
that it covers the whole of the bottom of the support post, the
amount of the charge, which does not contribute to deformation of
the diaphragm and which is stored on the bottom of the support
post, is small, thus suppressing a waste of the power consumption.
In addition, with respect to the strength of the diaphragm, there
is an advantage in that the fluid actuating apparatus can be
produced so that the support post has a larger thickness by the
thickness of the diaphragm-side electrode than that in the
construction in which the diaphragm-side electrode is formed so
that it does not extend to the support post, and thus the support
post is stronger.
[0026] The method for manufacturing a fluid actuating apparatus
according to an embodiment of the present invention includes the
steps of forming a diaphragm-side electrode through the second
insulating film on the sacrifice layer pattern including a portion
between the support post-forming regions. Therefore, there can be
produced a fluid actuating apparatus having a construction such
that, as compared to the construction in which the diaphragm-side
electrode is formed so that it covers the whole of the bottom of
the support post, the amount of the charge, which does not
contribute to deformation of the diaphragm and which is stored on
the bottom of the support post, is small, thus suppressing a waste
of the power consumption.
[0027] The electrostatically-actuated fluid discharge apparatus
according to an embodiment of the present invention includes the
fluid actuating apparatus according to an embodiment of the present
invention, and therefore has not only the above-mentioned
advantages obtained by the fluid actuating apparatus according to
an embodiment of the present invention, but also an advantage in
that there can be provided the electrostatically-actuated fluid
discharge apparatus having high fluid actuating force and having an
increased density of fluid discharge sections, e.g., nozzles for
liquid, or discharge outlets for gas.
[0028] The method for manufacturing an electrostatically-actuated
fluid discharge apparatus according to an embodiment of the present
invention includes the method for manufacturing a fluid actuating
apparatus according to an embodiment of the present invention, and
therefore has not only the above-mentioned advantages obtained by
the method for manufacturing a fluid actuating apparatus according
to an embodiment of the present invention, but also an advantage in
that the electrostatically-actuated fluid discharge apparatus can
be produced easily with high precision. Further, there is an
advantage in that the electrostatically-actuated fluid discharge
apparatus, for example, an ink-jet printer head having a diaphragm,
a pressure chamber, a discharge section (nozzle or discharge
outlet), and the like can be produced by, e.g., surface
micromachining without using lamination.
[0029] A task of reducing a waste of the power consumption to
suppress the power consumption while achieving a diaphragm having
satisfactory repulsion force for actuation of a fluid, and
preventing the stress concentration on the diaphragm-side electrode
and the support post is achieved by employing a structure in which
the diaphragm-side electrode is formed so that it extends to and
passes through the support post or a structure in which the
diaphragm-side electrode is formed so that it extends from the
support post to another without complicating the process for
production.
[0030] The fluid actuating apparatus and the method for
manufacturing a fluid actuating apparatus, and the
electrostatically-actuated fluid discharge apparatus and the method
for manufacturing an electrostatically-actuated fluid discharge
apparatus according to the embodiments of the present invention can
be generally applied to the uses in which liquid in a very small
volume (volume with a unit of picolitter or smaller) is fed or
discharged. For example, in the civil use, for example, an ink-jet
printer head, and, in the commercial use, for example, a high
molecular-weight or low molecular-weight organic material coating
apparatus for organic EL or the like, a printing apparatus for
printed wiring board, a printing apparatus for solder bump, a
three-dimensional modeling apparatus, and a .mu.TAS (micro total
analysis system), the present invention can be applied to a feed
head for feeding a chemical agent or another liquid with a unit as
small as pl (picolitter) or less while controlling it with high
accuracy and a feed head for feeding gas in a very small volume
while controlling it with high accuracy. Further, the fluid
actuating apparatus 10 can be applied to an actuator of, for
example, a fluid pump for use in cooling a central processing unit
(CPU) in a computer.
[0031] Further features of the invention, and the advantages
offered thereby, are explained in detail hereinafter, in reference
to specific embodiments of the invention illustrated in the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIGS. 1A-1C are views showing the fluid actuating apparatus
according to the first embodiment of the present invention, wherein
FIG. 1A is a plan view of the layout, FIG. 1B shows a diagrammatic
cross-sectional structure taken along the line A-A of FIG. 1A, and
FIG. 1C shows a diagrammatic cross-sectional structure taken along
the line B-B of FIG. 1A;
[0033] FIGS. 2A-2B are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the first
embodiment of the present invention;
[0034] FIGS. 3A-3B are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the first
embodiment of the present invention;
[0035] FIGS. 4A-4C are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the first
embodiment of the present invention;
[0036] FIGS. 5A-5B are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the first
embodiment of the present invention;
[0037] FIGS. 6A-6B are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the first
embodiment of the present invention;
[0038] FIGS. 7A-7B are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the first
embodiment of the present invention;
[0039] FIGS. 8A-8B are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the first
embodiment of the present invention;
[0040] FIGS. 9A-9B are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the first
embodiment of the present invention;
[0041] FIGS. 10A-10B are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the first
embodiment of the present invention;
[0042] FIGS. 11A-11B are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the first
embodiment of the present invention;
[0043] FIGS. 12A-12B are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the first
embodiment of the present invention;
[0044] FIG. 13 are diagrammatic perspective view showing the
construction of the electrostatically-actuated fluid discharge
apparatus according to the first embodiment of the present
invention;
[0045] FIGS. 14A-14B are diagrammatic cross-sectional views showing
the construction of the electrostatically-actuated fluid discharge
apparatus according to the first embodiment of the present
invention;
[0046] FIGS. 15A-15B are views for explaining the operation of the
electrostatically-actuated fluid discharge apparatus;
[0047] FIGS. 16A-16B are views showing the steps in the method for
manufacturing an electrostatically-actuated fluid discharge
apparatus according to the first embodiment of the present
invention;
[0048] FIGS. 17A-17B are views showing the steps in the method for
manufacturing an electrostatically-actuated fluid discharge
apparatus according to the first embodiment of the present
invention;
[0049] FIGS. 18A-18D are views showing the
electrostatically-actuated fluid discharge apparatus according to
the first embodiment of the present invention;
[0050] FIG. 19 are plan view showing one form of opening sections
formed when removing the sacrifice layer pattern;
[0051] FIGS. 20A-20C are views showing the fluid actuating
apparatus according to the second embodiment of the present
invention, wherein FIG. 20A is a plan view of the layout, FIG. 20B
shows a diagrammatic cross-sectional structure taken along the line
A-A of FIG. 20A, and FIG. 20C shows a diagrammatic cross-sectional
structure taken along the line B-B of FIG. 20A;
[0052] FIGS. 21A-21B are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the second
embodiment of the present invention;
[0053] FIGS. 22A-22B are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the second
embodiment of the present invention;
[0054] FIGS. 23A-23C are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the second
embodiment of the present invention;
[0055] FIGS. 24A-24B are views showing the steps in the method for
manufacturing a fluid actuating apparatus according to the second
embodiment of the present invention;
[0056] FIGS. 25A-25B are views showing the steps in the method for
producing a fluid actuating apparatus according to the second
embodiment of the present invention;
[0057] FIGS. 26A-26B are views showing the steps in the method for
producing a fluid actuating apparatus according to the second
embodiment of the present invention;
[0058] FIGS. 27A-27B are views showing the steps in the method for
producing a fluid actuating apparatus according to the second
embodiment of the present invention;
[0059] FIGS. 28A-28B are views showing the steps in the method for
producing a fluid actuating apparatus according to the second
embodiment of the present invention;
[0060] FIGS. 29A-29B are views showing the steps in the method for
producing a fluid actuating apparatus according to the second
embodiment of the present invention;
[0061] FIGS. 30A-30B are views showing the steps in the method for
producing a fluid actuating apparatus according to the second
embodiment of the present invention;
[0062] FIGS. 31A-31B are views showing the steps in the method for
producing a fluid actuating apparatus according to the second
embodiment of the present invention;
[0063] FIG. 32 are diagrammatic perspective view showing the
construction of the electrostatically-actuated fluid discharge
apparatus according to the second embodiment of the present
invention;
[0064] FIGS. 33A-33B are diagrammatic cross-sectional views showing
the construction of the electrostatically-actuated fluid discharge
apparatus according to the second embodiment of the present
invention;
[0065] FIGS. 34A-34B are views showing the steps in the method for
producing an electrostatically-actuated fluid discharge apparatus
according to the second embodiment of the present invention;
and
[0066] FIGS. 35A-35B are views showing the steps in the method for
producing an electrostatically-actuated fluid discharge apparatus
according to the second embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
EXAMPLE 1
[0067] The fluid actuating apparatus according to the first
embodiment of the present invention will be described with
reference to FIGS. 1A-1C. FIG. 1A shows part of a plan view of the
layout, FIG. 1B shows a diagrammatic cross-sectional structure
taken along the line A-A of FIG. 1A, and FIG. 1C shows a
diagrammatic cross-sectional structure taken along the line B-B of
FIG. 1A. The scale of FIG. 1A and that of FIG. 1B, FIG. 1C are not
the same. Fluid actuating apparatuses are actually arranged in a
line, but the figures show a single fluid actuating apparatus,
which is described below.
[0068] As shown in FIGS. 1A-1C, a substrate-side electrode 12,
which includes a conductor thin film and which is common to another
fluid actuating apparatus (not shown), is formed on a substrate 11
having at least a surface formed from an insulating layer. A first
insulating film 13 is formed on the substrate-side electrode 12. A
second insulating film 14 is formed on the first insulating film 13
so that a space 31 is formed. Accordingly, the space 31 is a
substantially rectangular parallelepiped space defined by the
two-dimensional first insulating film and the three-dimensional
second insulating film 14, and a support post 21 including the
second insulating film 14 is formed so that the support post
intrudes into the side portion of the space 31 and has a comb
teeth-like form. The first insulating film 13 and the second
insulating film 14 are insulating films for preventing the
below-described diaphragm-side electrode from being brought into
contact with the substrate-side electrode 12 when the
diaphragm-side electrode is deflected.
[0069] On the second insulating film 14 is formed a diaphragm-side
electrode 15 which is independently actuated with respect to the
space 31 through the second insulating film 14. The diaphragm-side
electrode 15 is rectangular (square or rectangular) as viewed from
the top (as viewed from the top of the plan view of the layout)
and, in the support post-forming region, the diaphragm-side
electrode is formed along the sidewall of the comb teeth-like form
support post 21 formed along the sidewall of the space, and may be
formed so that it extends to and covers part of the bottom of the
support post 21, but it is not preferred that the diaphragm-side
electrode is formed so as to cover the whole of the bottom of the
support post 21 since an increase of the electrostatic capacity is
caused to increase the power consumption. Thus, the diaphragm-side
electrode 15 is basically a rectangular electrode, and formed so
that it extends into the comb teeth-like form support post formed
along the side portion of the space 31. For preventing the
occurrence of leakage between the adjacent diaphragm-side
electrodes 15, the diaphragm-side electrodes 15 are formed
independently of each other.
[0070] A third insulating film 16 for covering the diaphragm-side
electrode 15 is formed on the second insulating film 14. Further,
on the third insulating film 16, a plurality of diaphragms 17 for
providing a pressure change in fluid, integrally having the
diaphragm-side electrode 15 actuated independently, are arranged in
a line, and the support post 21 is formed on the substrate 11,
substantially on the first insulating film 13 in such a way that
the support post supports the individual diaphragms 17 on both
sides by a beam. Further, a fourth insulating film 18 is formed on
the third insulating film 16 so as to cover the diaphragm 17. The
third insulating film 16 is formed for the purpose of relaxing the
stress applied to the diaphragm-side electrode 15 by the diaphragm
17, and, when the stress relaxation is not required, it can be
omitted. As described above, in the support post-forming region
which is formed so that it intrudes into the side portion of the
space 31 and has a comb teeth-like form, the support post 21 is
formed from the second insulating film 14, the diaphragm-side
electrode 15, the third insulating film 16, the diaphragm 17, and
the fourth insulating film 18.
[0071] The diaphragm 17 formed in the example shown in the figures
has a strip form, and a plurality of support posts 21 are formed
along the side portion of the diaphragm 17 at predetermined
intervals (pitch between the support posts). The predetermined
interval (pitch between the support posts) is preferably 2 to 10
.mu.m, most preferably 5 .mu.m. The adjacent diaphragms 17 are
formed continuously through the support post 21, and the support
post 21 including the diaphragm 17 is formed. Therefore, the space
31 defined by the diaphragm 17 and the substrate-side electrode 12
forms a hollow portion between a plurality of diaphragms 17
arranged in a line. The space 31 forming a hollow portion between
the diaphragms 17 is formed so that it is an enclosed space as a
whole.
[0072] Near the support post 21 of each diaphragm 17, in the
present Example, between the support posts 21 along the side
portion of the single diaphragm 17, an opening section (not shown)
for introducing gas or liquid used for removing a sacrifice layer
by etching in the production process described below is formed.
After removing the sacrifice layer by etching, the opening section
is sealed up by a predetermined member.
[0073] As the substrate 11, a semiconductor substrate comprised of
silicon (Si), gallium arsenide (GaAs), or the like, which has an
insulating film (not shown) formed thereon, can be used. Therefore,
as the substrate 11, an insulating substrate, such as a glass
substrate including a quartz substrate, can be used. In this case,
there is no need to form an insulating film on the surface of the
substrate. In the present Example, as the substrate 11, a silicon
substrate having an insulating film comprised of, e.g., a silicon
oxide film formed on the surface is used.
[0074] The substrate-side electrode 12 is formed from an
impurity-doped polycrystalline silicon film, metal film {e.g.,
platinum (Pt), titanium (Ti), aluminum (Al), gold (Au), chromium
(Cr), nickel (Ni), or copper (Cu)}, ITO (indium tin oxide) film, or
the like. As a method for forming the film, various film formation
methods, such as an evaporation method, a vapor deposition method,
and a sputtering method, can be used. An n.sup.+ diffused layer
electrode can be formed by a method in which a substrate-side
electrode pattern is formed by selective oxidation, and then
implanted with B.sup.+, P.sup.+, and B.sup.+, and a channel stopper
layer is formed on the p-Well, followed by arsenic (As)
implantation. Similarly, a p.sup.+ diffused layer electrode can be
formed on the n-Well. In the present Example, the substrate-side
electrode 12 is formed from an impurity -doped polycrystalline
silicon film.
[0075] The diaphragm-side electrode 15 can be formed from a
material similar to the material for the substrate-side electrode
12 by a method similar to the method for forming the substrate-side
electrode 12. Specifically, the diaphragm-side electrode 15 can be
formed from an impurity-doped polycrystalline silicon film, metal
film {e.g., platinum (Pt), titanium (Ti), aluminum (Al), gold (Au),
chromium (Cr), nickel (Ni), or copper (Cu)}, ITO (indium tin oxide)
film, or the like. As a method for forming the film, various film
formation methods, such as an evaporation method, a vapor
deposition method, and a sputtering method, can be used. In the
present Example, the diaphragm-side electrode 15 is formed from an
impurity-doped polycrystalline silicon film.
[0076] The diaphragm-side electrode 15 is connected to the
diaphragm 17 through the third insulating film 16, and formed so
that it is inserted into the lower surface concave portion formed
by the bent diaphragm 17 and extends to the side of the sidewall of
the space 31. The diaphragm 17 is formed from, for example, an
insulating film, especially preferably a silicon nitride film (SiN
film) which generates a tension stress and high repulsion force as
a diaphragm. A fourth insulating film 18 is formed on the upper
surface of the diaphragm 17, and the fourth insulating film 18 is
formed from, e.g., a silicon oxide film. Each of the second
insulating film 14 and the third insulating film 16 can be formed
from, e.g., a silicon oxide film. Therefore, in the present
Example, the diaphragm is comprised of substantially the second
insulating film 14, the diaphragm-side electrode 15, the third
insulating film 16, the diaphragm 17, and the fourth insulating
film 18.
[0077] The fluid actuating apparatus 1 having the above
construction vibrates the diaphragm 17 by applying a voltage
between the substrate-side electrode 12 and the diaphragm-side
electrode 15 to change a fluid on the diaphragm 17 in pressure,
allowing the fluid to move.
[0078] In the fluid actuating apparatus 1 of the present invention,
the diaphragm-side electrode 15 is formed so that it passes through
the support post 21 and extends to and covers part of the bottom of
the support post 21, and therefore, as compared to the construction
in which the diaphragm-side electrode 15 is formed so that it
covers the whole of the bottom of the support post 21, the amount
of the charge, which does not contribute to deformation of the
diaphragm 17 and which is stored on the bottom of the support post
21, is small, thus suppressing a waste of the power consumption. In
addition, with respect to the strength of the diaphragm 17, there
is an advantage in that the support post 21 has a larger thickness
by the thickness of the diaphragm-side electrode 15 than that in
the construction in which the diaphragm-side electrode 15 is formed
so that it does not extend to the support post 21, and thus the
support post 21 is stronger. The charge density was measured when
30 V was applied to the electrode of the fluid actuating apparatus
1 having the above construction, and the deflection was measured
when a distribution load of 61 kPa was applied. As a result, the
charge density was 4.4 fF, and the deflection was 13 nm. On the
other hand, in the conventional construction in which the
diaphragm-side electrode is formed outside of the support post, the
charge density was as small as 1.7 fF, but the deflection was as
very large as 186 nm, and hence the diaphragm was too soft and the
repulsion force was unsatisfactory. Further, in the construction in
which the diaphragm-side electrode is formed so that it extends to
and covers the whole of the bottom of the support post, the charge
density was as very large as 5.1 fF to cause a waste of the power
consumption, but the deflection was as small as 13 nm. Thus, in the
fluid actuating apparatus 1 of the present invention, small
deflection could be achieved without considerably increasing the
charge density.
EXAMPLE 2
[0079] The method for producing a fluid actuating apparatus
according to the first embodiment of the present invention will be
described with reference to the views of FIGS. 2A to 12B showing
the steps in the production process. The views of FIGS. 2A to 12B
showing the steps in the production process mainly show
cross-sectional structures at positions similar to the positions of
the cross-section taken along the line A-A and the cross-section
taken along the line B-B shown in the plan view of the layout of
FIG. 1A. In FIGS. 4A-4C, a plan view of the layout of the sacrifice
layer pattern is also shown.
[0080] As shown in FIGS. 2A-2B, a substrate 11 having at least an
insulating surface is prepared. As the substrate 11, for example,
in the present Example, a substrate comprising an insulating film,
e.g., a silicon oxide film formed on a silicon substrate is used. A
common substrate-side electrode 12 is formed on the substrate 11.
In the present Example, the substrate-side electrode 12 is formed
as follows. An amorphous silicon film is deposited by, e.g., a
chemical vapor deposition (CVD) method, and then doped with an
impurity, e.g., phosphorus (P). Then, the impurity as dopant is
activated by a heat treatment so that the electrode has conduction
properties, thus forming the substrate-side electrode 12 comprised
of polycrystalline silicon.
[0081] The substrate-side electrode 12 is formed from an
impurity-doped polycrystalline silicon film, but it can be also
formed from an impurity-doped metal film {e.g., platinum (Pt),
titanium (Ti), aluminum (Al), gold (Au), chromium (Cr), nickel
(Ni), or copper (Cu)}, ITO (indium tin oxide) film, or the like. As
a method for forming the film, various film formation methods, such
as an evaporation method, a vapor deposition method, and a
sputtering method, can be used. An n.sup.+ diffused layer electrode
can be formed by a method in which a substrate-side electrode
pattern is formed by selective oxidation, and then implanted with
B.sup.+, P.sup.+, and B.sup.+, and a channel stopper layer is
formed on the p-Well, followed by arsenic (As) implantation.
Similarly, a p.sup.+ diffused layer electrode can be formed on the
n-Well.
[0082] Next, as shown in FIGS. 3A-3B, a first insulating film 13 is
formed on the surface of the substrate-side electrode 12. The first
insulating film 13 can be formed by a reduced pressure CVD method
at a temperature as high as, e.g., about 1,000.degree. C. or a
thermal oxidation method. The first insulating film 13 is required
to be a protective film for the substrate-side electrode 12 and to
be a film having a resistance to the etching liquid or etching gas
used for etching the below-mentioned sacrifice layer, and further
required to prevent discharge caused when the diaphragm and the
substrate-side electrode are close to each other and to prevent
short-circuiting caused when the diaphragm is in contact with the
substrate-side electrode 12. As the first insulating film 13, a
silicon oxide (SiO.sub.2) film can be used when using etching gas
comprised of, e.g., sulfur hexafluoride (SF.sub.6), carbon
tetrafluoride (CF.sub.4), or xenon difluoride (XeF.sub.2), or a
silicon nitride (SiN) film can be used when using etching liquid
comprised of, e.g., hydrofluoric acid. Subsequently, a sacrifice
layer 41 is formed on the entire surface of the first insulating
film 13. In the present Example, as the sacrifice layer 41, a
polycrystalline silicon film is deposited by a CVD method.
[0083] Then, as shown in FIGS. 4A-4C, using general lithography
technique and etching technique, the sacrifice layer 41 in the
portion, in which a support post (so-called anchor) to be formed
later for supporting the diaphragm is formed (when a not shown
auxiliary support post is formed, a portion corresponding to the
auxiliary support post is included), is selectively removed by
etching to form an opening section 42, thus forming a sacrifice
layer pattern 43. That is, the single sacrifice layer pattern 43 is
basically formed in a rectangular parallelepiped form, the region
in which the support post is formed is removed to have a comb
teeth-like form, the removed portion constitutes the opening
section 42, and the region in communication with the sacrifice
layer pattern 43 for forming the space in the adjacent fluid
actuating apparatus has a comb teeth-like form by the sacrifice
layer 41. The etching for the sacrifice layer 41 is preferably dry
etching by which processing with high precision can be achieved
since there is a portion which must be processed into a comb
teeth-like form.
[0084] Then, as shown in FIGS. 5A-5B, a second insulating film 14
for covering the surface of the sacrifice layer pattern 43 is
formed on the first insulating film 13. Like the first insulating
film 13, the second insulating film 14 is formed from a film having
a resistance to the etching liquid or etching gas used for etching
the sacrifice layer 41. In the present Example, the sacrifice layer
41 comprised of a polycrystalline silicon film is removed by
etching using, e.g., sulfur hexafluoride (SF.sub.6), carbon
tetrafluoride (CF.sub.4), or xenon difluoride (XeF.sub.2), and
therefore the second insulating film 14 is formed from a silicon
oxide film (SiO.sub.2 film) by thermal oxidation or CVD. Each of
the first and second insulating films 13, 14 is required to protect
the diaphragm-side electrode, and to prevent discharge caused when
the diaphragm and the substrate-side electrode 12 are close to each
other and to prevent short-circuiting caused when the diaphragm is
in contact with the substrate-side electrode 12. When the
substrate-side electrode is not etched by the etchant for the
sacrifice layer, e.g., hydrofluoric acid used for etching the
silicon oxide (SiO.sub.2 film) sacrifice layer, and further a
satisfactory pressure resistance can be secured only by the second
insulating film 14, the first insulating film can be omitted.
[0085] Next, as shown in FIGS. 6A-6B, an independent diaphragm-side
electrode 15 is formed on the second insulating film 14. In the
present Example, the diaphragm-side electrode 15 is formed as
follows. An amorphous silicon film is deposited by, e.g., a
chemical vapor deposition (CVD) method, and then doped with an
impurity, e.g., phosphorus (P). Then, the impurity as dopant is
activated by a heat treatment so that the electrode has conduction
properties, thus forming the diaphragm-side electrode 15 comprised
of polycrystalline silicon. The diaphragm-side electrode 15 is
formed in the support post, and hence formed through the second
insulating film 14 on the upper surface of the sacrifice layer
pattern 43, the sidewall of the sacrifice layer pattern 43, and
part of the bottom of the support post-forming region. In the
present Example, the diaphragm-side electrode 15 is formed so that
it extends to part of the bottom of the support post, but it may be
formed so that it extends to only the sidewall portion.
[0086] The diaphragm-side electrode 15 is formed from an
impurity-doped polycrystalline silicon film, but it can be also
formed from an impurity-doped metal film {e.g., platinum (Pt),
titanium (Ti), aluminum (Al), gold (Au), chromium (Cr), nickel
(Ni), or copper (Cu)}, ITO (indium tin oxide) film, or the like. As
a method for forming the film, various film formation methods, such
as an evaporation method, a vapor deposition method, and a
sputtering method, can be used.
[0087] Next, as shown in FIGS. 7A-7B, a third insulating film 16
for covering the diaphragm-side electrode 15 is formed. The third
insulating film 16 may be formed from either a silicon oxide
(SiO.sub.2) film obtained by, for example, subjecting the surface
of the diaphragm-side electrode 15 to thermal oxidation, or silicon
oxide deposited by a chemical vapor deposition (CVD) method or the
like. The third insulating film 16 is formed for the purpose of
relaxing the stress applied to the diaphragm-side electrode 15 by a
diaphragm 17 to be formed later, and, when the stress relaxation is
not required, it can be omitted.
[0088] Then, as shown in FIGS. 8A-8B, a diaphragm 17 for providing
a pressure change in fluid is formed on the entire surface of the
third insulating film 16. The diaphragm 17 is formed from, for
example, an insulating film, especially preferably formed from a
silicon nitride film (SiN film) which generates a tension stress
and high repulsion force as a diaphragm. As an example of a method
for forming the film, there can be mentioned a reduced pressure CVD
method. When the diaphragm 17 is formed from a silicon nitride film
(SiN film) as mentioned above, the diaphragm 17 has a tension
stress and high repulsion force which are advantageous to the
diaphragm.
[0089] Next, as shown in FIGS. 9A-9B, a fourth insulating film 18
for covering the diaphragm 17 is formed. The fourth insulating film
18 is formed from, e.g., a silicon oxide film. With respect to the
insulating film 18, for example, when an ink, a chemical agent, or
another liquid is used as a fluid, the hydrophilic insulating film
18 is formed as the liquid contacting surface. When gas is used as
a fluid, the insulating film 18 having a resistance to the gas is
formed. When sulfur hexafluoride (SF.sub.6), carbon tetrafluoride
(CF.sub.4), or xenon difluoride (XeF.sub.2) gas is used for etching
of the sacrifice layer pattern 43, it is preferred that the
insulating film 18 is formed from an oxide film (e.g., silicon
oxide film) having a resistance to the etching gas.
[0090] The diaphragm 17 comprised of a silicon nitride film has a
construction such that it is disposed between the third insulating
film 16 and the fourth insulating film 18, and this construction is
effective in preventing warpage of the diaphragm when a stacked
structure of the silicon nitride film having a tension stress and
the silicon oxide film having a compression stress is formed. In
the stacked structure of the silicon nitride film and the silicon
oxide film, the diaphragm is markedly bent downwards due to the
synergetic effect of the tension stress and the compression stress,
lacking in the deflection of the diaphragm. By covering the both
sides of the silicon nitride film with a silicon oxide film, the
warpage can be relaxed. Therefore, in the present Example, the
diaphragm is comprised of substantially the second insulating film
14, the diaphragm-side electrode 15, the third insulating film 16,
the diaphragm 17, and the fourth insulating film 18.
[0091] In the support post-forming region which is formed so that
it intrudes into the side portion of the sacrifice layer pattern 43
and has a comb teeth-like form, the support post 21 is formed from
the second insulating film 14, the diaphragm-side electrode 15, the
third insulating film 16, the diaphragm 17, and the fourth
insulating film 18.
[0092] Next, as shown in FIGS. 10A-10B, near the support post 21,
an opening section 44 which penetrates the fourth insulating film
18, the diaphragm 17, the third insulating film 16, the second
insulating film 14, and the like is formed so that the sacrifice
layer pattern 43 is exposed. The opening section 44 serves as a
vent hole in the removal of the sacrifice layer pattern 43 by
etching, and it can be formed by anisotropic dry etching, e.g.,
reactive ion etching (RIE). The opening section may have a size as
small as 2 .mu.m square or less, and, the smaller the size of the
opening section, the more easily the opening section can be sealed
up. It has been confirmed that a 0.5 .mu.m square of the opening
section is satisfactory in dry etching for the sacrifice layer.
Further, in the present Example, when the diaphragm 17 used is
thin, for improving the repulsion force of the diaphragm 17 itself,
an auxiliary support post (so-called post)(not shown) can be formed
immediately under the middle of the diaphragm 17 simultaneously
with the support post 21.
[0093] Then, as shown in FIGS. 11A-11B, etching liquid or etching
gas is introduced through the opening section 44. In the present
Example, sulfur hexafluoride (SF.sub.6), carbon tetrafluoride
(CF.sub.4), or xenon difluoride (XeF.sub.2) gas is introduced and
the sacrifice layer pattern 43 (see FIG. 10) is removed by etching
to form a space 31 between the diaphragm 17 and the substrate-side
electrode 12 integrally having the diaphragm-side electrode 15. In
this case, a plurality of opening sections 44 are formed along the
long side of the diaphragm 17 and etching proceeds in the direction
along the short side of the diaphragm 17 through the opening
sections 44, so that the etching can be done in a short time. When
silicon, such as polycrystalline silicon, is used in the sacrifice
layer pattern 43, it can be removed by etching using sulfur
hexafluoride (SF.sub.6), carbon tetrafluoride (CF.sub.4), or xenon
difluoride (XeF.sub.2) gas. When a silicon oxide film (SiO.sub.2
film) is used in the sacrifice layer pattern 43, it can be removed
by etching using etching liquid comprised of hydrofluoric acid.
When the sacrifice layer pattern 43 is removed using etching
liquid, a drying treatment is carried out. Thus, the space 31 is
formed in a region formed by removing the sacrifice layer pattern
43, and further, in the support post-forming region formed at the
side portion of the space 31, the support post 21 is formed from
the second insulating film 14, the diaphragm-side electrode 15, the
third insulating film 16, the diaphragm 17, and the fourth
insulating film 18.
[0094] Next, as shown in FIGS. 12A-12B, the opening section 44 is
sealed up with a sealing member 45. The sealing can be made by a
metal sputtering method of aluminum (Al) or the like, but the space
31 as a vibration chamber is under a reduced pressure and hence the
diaphragm 17 is bent downwards, so that a stress is always applied
to the vicinity of the support post 21 (or auxiliary support post)
of the diaphragm 17. In addition, when the diaphragm 17 is bent
downwards, the deformable range of the diaphragm 17 is narrow.
Considering this point, a method can be employed in which, for
example, a boron phosphorus silicate glass (BPSG) film is formed,
followed by reflow, to seal the opening section 44 up. By
conducting the reflow in an atmosphere of nitrogen gas (N.sub.2)
under pressure, the pressure of the space 31 as a vibration chamber
can be controlled to be a desired value. Alternatively, the opening
section 44 can be sealed up utilizing the viscosity of the member
forming the below-mentioned pressure chamber. Thus, the fluid
actuating apparatus 1 is produced.
[0095] The method for producing the fluid actuating apparatus 1 of
the present invention comprises the step for forming the
diaphragm-side electrode 15 through the second insulating film 14
on the upper surface of the sacrifice layer pattern 43, the
sidewall of the sacrifice layer pattern 43, and part of the bottom
of the support post-forming region, and hence the diaphragm-side
electrode 15 is formed so that it passes through the support post
21 and extends to and covers part of the bottom of the support post
21. Therefore, there can be produced a fluid actuating apparatus
having a construction such that, as compared to the construction in
which the diaphragm-side electrode is formed so that it covers the
whole of the bottom of the support post 21, the amount of the
charge, which does not contribute to deformation of the diaphragm
17 and which is stored on the bottom of the support post 21, is
small, thus suppressing a waste of the power consumption. In
addition, with respect to the strength of the diaphragm 17, there
is an advantage in that the fluid actuating apparatus can be
produced so that the support post 21 has a larger thickness by the
thickness of the diaphragm-side electrode 15 than that in the
construction in which the diaphragm -side electrode is formed so
that it does not extend to the support post 21, and thus the
support post 21 is stronger.
EXAMPLE 3
[0096] Next, the electrostatically-actuated fluid discharge
apparatus according to the first embodiment of the present
invention will be described with reference to the diagrammatic
perspective view of FIG. 13 and the diagrammatic cross-sectional
views of FIGS. 14A-14B. In this Example, an electrostatic head is
described as an example of the electrostatically-actuated fluid
discharge apparatus using the fluid actuating apparatus of the
present invention.
[0097] First, as shown in FIG. 13, an electrostatically-actuated
fluid discharge apparatus (electrostatic head) 1 according to the
present embodiment comprises a fluid actuating apparatus 2
comprising a plurality of diaphragms 17 actuated (vibrated) by
electrostatic force, which diaphragms are arranged in a line with
high density, and a so-called fluid feed zone 55 comprising a
partition structure 54 which is disposed above the diaphragms 17 at
the corresponding position, and which has formed therein a pressure
chamber (so-called cavity) 51 for storing a fluid 61 (indicated by
an arrow) and a discharge section 53 for discharging the fluid 61,
a nozzle in the present Example (since liquid is used as a fluid).
The figure shows a construction in which auxiliary support posts
(posts) 23 are formed between the support posts (anchors) 21.
[0098] As shown in FIGS. 14A-14B, in the fluid actuating apparatus
1 of the present invention is formed a partition structure having
the pressure chamber 51 and the nozzle 53 so that a partition 52 of
the fluid feed zone 55 is formed at the position corresponding to
the support post 21 for supporting the diaphragm 17. That is, the
fluid feed zone 55 is arranged. The pressure chamber 51 is in
communication with a fluid feed channel (not shown).
[0099] Next, the operation of the electrostatically-actuated fluid
discharge apparatus 2is described with reference to FIGS. 15A-15B.
In the following description of FIGS. 15A-15B and in FIGS. 1A-1C,
FIG. 13, and FIGS. 14A-14B, like parts or portions are indicated by
like reference numerals.
[0100] As shown in FIG. 15A, in the fluid actuating apparatus 1,
when a predetermined voltage between the substrate-side electrode
12 and the diaphragm-side electrode 15 is applied, electrostatic
attraction force is generated, so that the diaphragm 17 having the
diaphragm-side electrode 15 is deflected to the side of the
substrate-side electrode 12. Conversely, when the application of
the voltage between the substrate-side electrode 12 and the
diaphragm-side electrode 15 is removed, as shown in FIG. 15B, the
diaphragm 17 is released from the electrostatic force and undergoes
damping vibration by its restoring force. The up-and-down motion of
the diaphragm 17 changes the capacity of the pressure chamber 51,
so that the fluid 61 contained in the pressure chamber 51 is
discharged through the nozzle 53, or the fluid 61 is fed to the
pressure chamber 51. When the diaphragm 17 is deflected to the side
of the substrate-side electrode 12 and the space 31 is a closed
space, air between the diaphragm 17 and the substrate-side
electrode 12 is compressed to prevent the diaphragm 17 from being
deflected, but the support structure comprised of the support post
21 (auxiliary support post 23) permits the compressed air to escape
to the space 31 under the adjacent diaphragm 17, so that the
diaphragm 17 can be satisfactorily deflected.
EXAMPLE 4
[0101] Next, the method for producing an electrostatically-actuated
fluid discharge apparatus according to the first embodiment of the
present invention will be described with reference to the views of
FIGS. 16A to 17B showing the steps in the production process. The
views of FIGS. 16A to 17B showing the steps in the production
process show cross-sectional structures at positions similar to the
positions of the cross-section taken along the line A-A and the
cross-section taken along the line B-B shown in the plan view of
the layout of FIG. 1A.
[0102] A fluid actuating apparatus 1 is produced by the process
described above with reference to FIGS. 2A to 12B, and then, as
shown in FIGS. 16A-16B, a partition-forming film is deposited on
the fluid actuating apparatus 1. The partition-forming film can be
formed from, e.g., a photo-curing resin material, such as an epoxy
resin material having photosensitive properties. Then, the
partition-forming film is patterned using a lithography technique
and an etching technique to form a partition 52 (52A) constituting
a pressure chamber (so-called chamber) 51 for storing a fluid and a
fluid feed channel (not shown) in communication with the pressure
chamber 51. Specifically, the pressure chamber 51 is formed on the
diaphragm 17, and the partition 52 constituting the pressure
chamber 51 is formed, for example, on and between the support posts
21 of the adjacent fluid actuating apparatus 1.
[0103] Then, as shown in FIGS. 17A-17B, the partition 52 (52B)
having a discharge section (e.g., nozzle) 53 is joined or bonded to
the upper edge faces of the partition 52A so that each pressure
chamber 51 is closed at the upper portion. The partition 52B is
comprised of, for example, a sheet material (so-called a nozzle
sheet), and can be formed from a predetermined material, e.g., a
metal, such as nickel or stainless steel, or a Si wafer. The
electrostatically-actuated fluid discharge apparatus 2 of the
present invention is obtained through the steps described
above.
[0104] The opening section 44 in the diaphragm 17 described above
with reference to FIGS. 12A-12B can be sealed up not by forming a
sealing member 45 by metal sputtering but by forming the sealing
member 45 using a photo-curing resin and controlling the viscosity
of the photo-curing resin.
[0105] In the fluid actuating apparatus 1 in the present Example,
the diaphragm 17 is deflected by electrostatic force and the
restoring force is used as actuating force, and therefore a fluid
in a very small volume can be fed while controlling it with high
precision. By forming an auxiliary support post 23 immediately
under the middle of the diaphragm 17, even when the diaphragm 17 is
thin or the short side width of the diaphragm 17 is long, the
length of the diaphragm 17 between the support posts 21 appears to
be short, so that the repulsion force of the diaphragm 17 can be
increased, thus obtaining required actuating force.
[0106] By virtue of the construction in which the diaphragm 17 is
supported by a plurality of support posts 21 which are integrated
with the diaphragm, and the opening section 44 for introducing an
etchant used for etching of the sacrifice layer pattern 43 is
formed near the support post 21, with respect to the formation of
the space 31 between the diaphragm 17 having a long side of about
0.5 to 3 mm and a short side of about 15 to 100 .mu.m and the
substrate-side electrode 12, the space 31 to be formed by removing
the sacrifice layer pattern 43 under the diaphragm 17 can be formed
by performing etching in the direction of the short side, and
hence, not only can the etching be done in a short time, but also
the space 31 under the adjacent diaphragm 17 can be simultaneously
formed with high precision. Therefore, there can be provided the
fluid actuating apparatus 1 which can secure actuating force for
the fluid and achieve high density.
[0107] When the substrate-side electrode 12 on the lower side is
formed as a common electrode and the diaphragm-side electrode 15 on
the upper side is formed in the form of a plurality of independent
electrodes, the lower surface of the diaphragm 17 can be flattened.
When the substrate-side electrode 12 on the lower side is in a
separate form, the step due to the thickness of the electrode
appears as a step of the diaphragm 17, and hence the tension stress
of the diaphragm 17 is relaxed by the step, so that the tension
stress does not effectively act. On the other hand, the diaphragm
17 comprised of a silicon nitride (SiN) film and the diaphragm-side
electrode 15 comprised of polycrystalline silicon (Si) are disposed
so that the diaphragm-side electrode 15 closely adheres to the side
of the lower surface of the diaphragm 17 formed by the step portion
through the third insulating film 16, and therefore, even when the
diaphragm 17 has a step portion, the tension of the diaphragm 17 is
not absorbed by the step portion.
[0108] When the positions of the diaphragm 17 comprised of a
silicon nitride (SiN) film and the diaphragm-side electrode 15
comprised of polycrystalline silicon (Si) are switched, that is,
when the diaphragm 17 comprised of a silicon nitride film is first
formed and the diaphragm-side electrode 15 comprised of
polycrystalline silicon is formed on the diaphragm, the diaphragm
17 can be flattened, but the voltage between the substrate-side
electrode 12 and the diaphragm-side electrode 15 is also
distributed to the SiN film having a higher specific permittivity,
and therefore the effective voltage applied to the space 31 between
the lower surface of the diaphragm 17 and the upper surface of the
substrate-side electrode 12 is lowered and thus the electrostatic
attraction force is lowered, so that the deflection of the
diaphragm 17 is reduced, which is disadvantageous to the actuation
with low power consumption.
[0109] When the fluid 61 fed to the pressure chamber 51 is liquid
and the portion in contact with the liquid is comprised of a
conductor, air bubbles may be formed in the liquid 61 at the
conductor surface or the conductor surface may suffer corrosion,
but, in the present Example, the diaphragm 17 is disposed on the
diaphragm-side electrode 15 and the surface of the diaphragm 17 is
covered with the fourth insulating film 18, and hence the above
problem does not occur.
[0110] When the fluid 61 is liquid, by forming on the surface of
the diaphragm 17 the fourth insulating film 18 from a hydrophilic
film, flowing of the liquid 61 into the pressure chamber 51 can be
facilitated. On the other hand, when the fluid 61 is gas, by
forming on the surface of the diaphragm 17 the fourth insulating
film 18 having a resistance to the gas, the diaphragm 17 is
prevented from suffering corrosion due to the gas.
[0111] In the method for producing the fluid actuating apparatus 1
in the present Example, when the sacrifice layer 41 and the
diaphragm 17 are formed by vapor deposition, the following effects
can be obtained. The interval between the electrodes and the
thickness of the diaphragm 17 are uniform, so that the dispersion
of the actuation voltage between the diaphragms 17 is reduced. The
flatness of the surface of the diaphragm 17 is improved. The
control of the electrode interval and the thickness of the
diaphragm 17 is easy, and hence the diaphragm 17 having a desired
thickness can be easily formed by controlling the time or
temperature for deposition. The sacrifice layer and diaphragm can
be easily formed by a general semiconductor process, which is
advantageous to mass production.
[0112] The opening section 44 is formed near the support post 21
and the sacrifice layer pattern 43 is removed by etching through
the opening section 44, and therefore the space 31 between the
diaphragm 17 and the substrate-side electrode 12 can be formed with
high precision. A plurality of opening sections 44 are formed along
the longitudinal direction of the diaphragm 17, and hence etching
of the sacrifice layer pattern 43 proceeds in the direction of the
short side of the diaphragm 17, thus making it possible to reduce
the time for the etching.
[0113] In the electrostatically-actuated fluid discharge apparatus
2 in the present Example, by virtue of having the above-described
fluid actuating apparatus 1, not only can the discharge sections 53
for the fluid 61, nozzles in the present Example be arranged with
high density, but also the fluid 61 in a very small volume can be
fed by high actuating force while controlling it with high
accuracy.
[0114] The electrostatically-actuated fluid discharge apparatus 2
involves an apparatus having a construction such that the pressure
chamber 51 is comprised of a plurality of high pressure chamber,
intermediate pressure chamber, and low pressure chamber and the
pressure chambers 51 are connected to one another, and a back-flow
valve is disposed between the pressure chambers 51 and a pressure
difference is utilized to permit the fluid to flow. One example is
described with reference to FIGS. 18A-18D. In FIGS. 18A-18D, FIG.
18A shows a plan view, FIG. 18B shows a cross-sectional view, and
FIGS. 18C and 18D show cross-sectional views for explaining the
operation.
[0115] As shown in FIGS. 18A and 18B, the
electrostatically-actuated fluid discharge apparatus 2 comprises
the fluid actuating apparatus 1 of the present invention, and the
pressure chamber 51 is formed above the fluid actuating apparatus 1
and a plurality of sets of them are formed. The pressure chamber 51
is comprised of, for example a high pressure chamber, an
intermediate pressure chamber, and a low pressure chamber, and the
individual pressure chambers 51 are connected to one another
through flow channels 71, 72, and back-flow valves 75, 76 are
disposed between the pressure chambers 51. The back-flow valves 75,
76 are opened or closed based on the downstream side. Arrows in the
figures indicate the direction of the flow of the fluid.
[0116] In the electrostatically-actuated fluid discharge apparatus
2, as shown in FIG. 18C, in the fluid actuating apparatus 1, when a
predetermined voltage between the substrate-side electrode 12 and
the diaphragm-side electrode 15 is applied, electrostatic
attraction force is generated, so that the diaphragm 17 having the
diaphragm-side electrode 15 is deflected to the side of the
substrate-side electrode 12. Conversely, when the application of
the voltage between the substrate-side electrode 12 and the
diaphragm-side electrode 15 is removed, as shown in FIG. 18D, the
diaphragm 17 is released from the electrostatic force and undergoes
damping vibration by its restoring force. The up-and-down motion of
the diaphragm 17 changes the capacity of the pressure chamber 51.
As shown in FIG. 18C, when the capacity of the pressure chamber 51
is increased, the pressure chamber 51 is under a reduced pressure
and hence under a lower pressure relative to the downstream side,
so that the back-flow valve 75 is opened. On the other hand, the
pressure chamber is under a lower pressure relative to the upstream
side, so that the back-flow valve 76 is closed. Then, as shown in
FIG. 18D, when the capacity of the pressure chamber 51 is reduced,
the pressure chamber 51 is under pressure and hence under a higher
pressure relative to the downstream side, so that the back-flow
valve 75 is closed. On the other hand, the pressure chamber is
under a higher pressure relative to the upstream side, so that the
back-flow valve 76 is opened. By causing a pressure difference
between before and after the pressure chamber 51 in this way, the
fluid 61 can be fed in the direction indicated by an arrow.
[0117] When gas is used as a fluid, the electrostatically-actuated
fluid discharge apparatus 2 can be produced so that a not shown
valve is basically provided at the discharge outlet of the pressure
chamber 51.
[0118] In the present invention, the electrostatically-actuated
fluid discharge apparatus 2 comprising the fluid actuating
apparatus 1 including the diaphragm 17, and the partition structure
54 having the pressure chamber 51 and the discharge section (e.g.,
nozzle) 53 for a fluid can be produced by surface micromachining
without using lamination. In the step for removing by etching the
sacrifice layer pattern 43 through the opening section 44 formed
near the support post 21 and other steps, a generally used
semiconductor process can be utilized, thus lowering the cost for
the fluid actuating apparatus 1 and the electrostatically-actuated
fluid discharge apparatus 2.
[0119] The electrostatically-actuated fluid discharge apparatus 2
can also be produced by stacking on the fluid actuating apparatus 1
the separately formed partition structure 54 having the discharge
section (e.g., nozzle) 53, the pressure chamber 51, and a fluid
feed channel (not shown). Further, for example, as shown in FIG.
19, a plurality of opening sections 44 can be formed near the
single support post 21. In the figure, two opening sections are
formed respectively on the both sides of the support post 21 as
viewed in the longitudinal direction of the support post, and one
opening section is formed respectively on the both sides as viewed
in the lateral direction of the support post, but the number of the
opening sections can be appropriately selected. In addition, the
positions of the opening sections to be formed can be appropriately
selected. The support post 21 and the auxiliary support post 23 can
be formed from part of the materials constituting the diaphragm 17,
the diaphragm-side electrode 15, the second insulating film 14, the
third insulating film 16, and the fourth insulating film 18.
EXAMPLE 5
[0120] Next, the fluid actuating apparatus according to the second
embodiment of the present invention will be described with
reference to FIGS. 20A-20C. The fluid actuating apparatus according
to the second embodiment has substantially the same construction as
that of the above-described fluid actuating apparatus according to
the first embodiment, except for the construction in connection
with the diaphragm-side electrode. Therefore, in the following
description and in the first embodiment, like parts or portions are
indicated by like reference numerals. FIG. 20A shows part of a plan
view of the layout, FIG. 20B shows a diagrammatic cross-sectional
structure taken along the line A-A of FIG. 20A, and FIG. 20C shows
a diagrammatic cross-sectional structure taken along the line B-B
of FIG. 20A. The scale of FIG. 20A and that of FIGS. 20B-20C are
not the same. Fluid actuating apparatuses are actually arranged in
a line, but the figures show a single fluid actuating apparatus,
which is described below.
[0121] As shown in FIGS. 20A-20C, a substrate-side electrode 12,
which is comprised of a conductor thin film and which is common to
another fluid actuating apparatus (not shown), is formed on a
substrate 11 having at least a surface formed from an insulating
layer. A first insulating film 13 is formed on the substrate-side
electrode 12. A second insulating film 14 is formed on the first
insulating film 13 so that a space 31 is formed. Accordingly, the
space 31 is a substantially rectangular parallelepiped space
defined by the two-dimensional first insulating film and the
three-dimensional second insulating film 14, and a support post 21
including the second insulating film 14 is formed so that the
support post intrudes into the side portion of the space 31 and has
a comb teeth-like form. The first insulating film 13 and the second
insulating film 14 are insulating films for preventing the
below-described diaphragm-side electrode from being brought into
contact with the substrate-side electrode 12 when the
diaphragm-side electrode is deflected.
[0122] On the second insulating film 14 is formed a diaphragm-side
electrode 15 which is independently actuated with respect to the
space 31 through the second insulating film 14. The diaphragm-side
electrode 15 is rectangular (square or rectangular) as viewed from
the top (as viewed from the top of the plan view of the layout),
and is formed so that it extends from a support post-forming region
to another. That is, the diaphragm-side electrode 15 is formed
between support post-forming regions so as to have a comb
teeth-like form. Thus, the diaphragm-side electrode 15 is basically
a rectangular electrode, and is formed so that it extends from a
support post-forming region to another and has a comb teeth-like
form. For preventing the occurrence of leakage between the adjacent
diaphragm-side electrodes 15, the diaphragm-side electrodes 15 are
formed independently of each other.
[0123] A third insulating film 16 for covering the diaphragm-side
electrode 15 is formed on the second insulating film 14. Further,
on the third insulating film 16, a plurality of diaphragms 17 for
providing a pressure change in fluid, integrally having the
diaphragm-side electrode 15 actuated independently, are arranged in
a line, and the support post 21 is formed on the substrate 11,
substantially on the first insulating film 13 in such a way that
the support post supports the individual diaphragms 17 on both
sides by a beam. Further, a fourth insulating film 18 is formed on
the third insulating film 16 so as to cover the diaphragm 17. The
third insulating film 16 is formed for the purpose of relaxing the
stress applied to the diaphragm-side electrode 15 by the diaphragm
17, and, when the stress relaxation is not required, it can be
omitted. As described above, in the support post-forming region
which is formed so that it intrudes into the side portion of the
space 31 and has a comb teeth-like form, the support post 21 is
formed from the second insulating film 14, the diaphragm-side
electrode 15, the third insulating film 16, the diaphragm 17, and
the fourth insulating film 18.
[0124] The diaphragm 17 formed in the example shown in the figures
has a strip form, and a plurality of support posts 21 are formed
along the side portion of the diaphragm 17 at predetermined
intervals (pitch between the support posts). The predetermined
interval (pitch between the support posts) is preferably 2 to 10
.mu.m, most preferably 5 .mu.m. The adjacent diaphragms 17 are
formed continuously through the support post 21, and the support
post 21 including the diaphragm 17 is formed. Therefore, the space
31 defined by the diaphragm 17 and the substrate-side electrode 12
forms a hollow portion between a plurality of diaphragms 17
arranged in a line. The space 31 forming a hollow portion between
the diaphragms 17 is formed so that it is an enclosed space as a
whole.
[0125] Near the support post 21 of each diaphragm 17, in the
present Example, between the support posts 21 along the side
portion of the single diaphragm 17, an opening section (not shown)
for introducing gas or liquid used for removing a sacrifice layer
by etching in the production process described below is formed.
After removing the sacrifice layer by etching, the opening section
is sealed up by a predetermined member.
[0126] As the substrate 11, a semiconductor substrate comprised of
silicon (Si), gallium arsenide (GaAs), or the like, which has an
insulating film (not shown) formed thereon, can be used. Therefore,
as the substrate 11, an insulating substrate, such as a glass
substrate including a quartz substrate, can be used. In this case,
there is no need to form an insulating film on the surface of the
substrate. In the present Example, as the substrate 11, a silicon
substrate having an insulating film comprised of, e.g., a silicon
oxide film formed on the surface is used.
[0127] The substrate-side electrode 12 is formed from an
impurity-doped polycrystalline silicon film, metal film {e.g.,
platinum (Pt), titanium (Ti), aluminum (Al), gold (Au), chromium
(Cr), nickel (Ni), or copper (Cu)}, ITO (indium tin oxide) film, or
the like. As a method for forming the film, various film formation
methods, such as an evaporation method, a vapor deposition method,
and a sputtering method, can be used. An n.sup.+ diffused layer
electrode can be formed by a method in which a substrate-side
electrode pattern is formed by selective oxidation, and then
implanted with B.sup.+, P.sup.+, and B.sup.+, and a channel stopper
layer is formed on the p-Well, followed by arsenic (As)
implantation. Similarly, a p.sup.+ diffused layer electrode can be
formed on the n-Well. In the present Example, the substrate-side
electrode 12 is formed from an impurity-doped polycrystalline
silicon film.
[0128] The diaphragm-side electrode 15 can be formed from a
material similar to the material for the substrate-side electrode
12 by a method similar to the method for forming the substrate-side
electrode 12. Specifically, the diaphragm-side electrode 15 can be
formed from an impurity-doped polycrystalline silicon film, metal
film {e.g., platinum (Pt), titanium (Ti), aluminum (Al), gold (Au),
chromium (Cr), nickel (Ni), or copper (Cu)}, ITO (indium tin oxide)
film, or the like. As a method for forming the film, various film
formation methods, such as an evaporation method, a vapor
deposition method, and a sputtering method, can be used. In the
present Example, the diaphragm-side electrode 15 is formed from an
impurity-doped polycrystalline silicon film.
[0129] The diaphragm-side electrode 15 is connected to the
diaphragm 17 through the third insulating film 16, and formed so
that it is inserted into the lower surface concave portion formed
by the bent diaphragm 17 and extends to the side of the sidewall of
the space 31. The diaphragm 17 is formed from, for example, an
insulating film, especially preferably a silicon nitride film (SiN
film) which generates a tension stress and high repulsion force as
a diaphragm. A fourth insulating film 18 is formed on the upper
surface of the diaphragm 17, and the fourth insulating film 18 is
formed from, e.g., a silicon oxide film. Each of the second
insulating film 14 and the third insulating film 16 can be formed
from, e.g., a silicon oxide film. Therefore, in the present
Example, the diaphragm is comprised of substantially the second
insulating film 14, the diaphragm-side electrode 15, the third
insulating film 16, the diaphragm 17, and the fourth insulating
film 18.
[0130] The fluid actuating apparatus 3 having the above
construction vibrates the diaphragm 17 by applying a voltage
between the substrate-side electrode 12 and the diaphragm-side
electrode 15 to change a fluid on the diaphragm 17 in pressure,
allowing the fluid to move.
[0131] In the fluid actuating apparatus 3 of the present invention,
the diaphragm-side electrode 15 is formed so that it passes through
the support post 21 and extends to and covers part of the bottom of
the support post 21, and therefore, as compared to the construction
in which the diaphragm-side electrode 15 is formed so that it
covers the whole of the bottom of the support post 21, the amount
of the charge, which does not contribute to deformation of the
diaphragm 17 and which is stored on the bottom of the support post
21, is small, thus suppressing a waste of the power consumption. In
addition, there is an advantage in that the strength of the
diaphragm 17 is larger than that in the construction in which the
diaphragm-side electrode is formed so that it does not extend to
the support post 21. Further, the charge density was measured when
30 V was applied to the electrode of the fluid actuating apparatus
3 having the above construction, and the deflection was measured
when a distribution load of 61 kPa was applied. As a result, the
charge density was 2.7 fF, and the deflection was 88 nm. On the
other hand, in a conventional structure such that the
diaphragm-side electrode was not formed in the support post, the
charge density was as small as 1.7 fF, but the deflection was as
very large as 186 nm, and hence the diaphragm was in contact with
the surface beneath the diaphragm when the diaphragm was vibrated,
so that the vibration did not smoothly proceed. Thus, in the fluid
actuating apparatus 3 of the present invention, small deflection
could be achieved without considerably increasing the charge
density.
EXAMPLE 6
[0132] The method for producing a fluid actuating apparatus
according to the second embodiment of the present invention will be
described with reference to the views of FIGS. 21 to 31 showing the
steps in the production process. The views of FIGS. 21 to 31
showing the steps in the production process mainly show
cross-sectional structures at positions similar to the positions of
the cross-section taken along the line A-A and the cross-section
taken along the line B-B shown in the plan view of the layout of
FIG. 20A. In FIGS. 23A-23C, a plan view of the layout of the
sacrifice layer pattern is also shown.
[0133] As shown in FIGS. 21A-21B, a substrate 11 having at least an
insulating surface is prepared. As the substrate 11, for example,
in the present Example, a substrate comprising an insulating film,
e.g., a silicon oxide film formed on a silicon substrate is used. A
common substrate-side electrode 12 is formed on the substrate 11.
In the present Example, the substrate-side electrode 12 is formed
as follows. An amorphous silicon film is deposited by, e.g., a
chemical vapor deposition (CVD) method, and then doped with an
impurity, e.g., phosphorus (P). Then, the impurity as dopant is
activated by a heat treatment so that the electrode has conduction
properties, thus forming the substrate-side electrode 12 comprised
of polycrystalline silicon.
[0134] The substrate-side electrode 12 is formed from an
impurity-doped polycrystalline silicon film, but it can be also
formed from an impurity-doped metal film {e.g., platinum (Pt),
titanium (Ti), aluminum (Al), gold (Au), chromium (Cr), nickel
(Ni), or copper (Cu)}, ITO (indium tin oxide) film, or the like. As
a method for forming the film, various film formation methods, such
as an evaporation method, a vapor deposition method, and a
sputtering method, can be used. An n.sup.+ diffused layer electrode
can be formed by a method in which a substrate-side electrode
pattern is formed by selective oxidation, and then implanted with
B.sup.+, P.sup.+, and B.sup.+, and a channel stopper layer is
formed on the p-Well, followed by arsenic (As) implantation.
Similarly, a p.sup.+ diffused layer electrode can be formed on the
n-Well.
[0135] Next, as shown in FIGS. 22A-22B, a first insulating film 13
is formed on the surface of the substrate-side electrode 12. The
first insulating film 13 can be formed by a reduced pressure CVD
method at a temperature as high as, e.g., about 1,000.degree. C. or
a thermal oxidation method. The first insulating film 13 is
required to be a protective film for the substrate-side electrode
12 and to be a film having a resistance to the etching liquid or
etching gas used for etching the below-mentioned sacrifice layer,
and further required to prevent discharge caused when the diaphragm
and the substrate-side electrode are close to each other and to
prevent short-circuiting caused when the diaphragm is in contact
with the substrate-side electrode 12. As the first insulating film
13, a silicon oxide (SiO.sub.2) film can be used when using etching
gas comprised of, e.g., sulfur hexafluoride (SF.sub.6), carbon
tetrafluoride (CF.sub.4), or xenon difluoride (XeF.sub.2), or a
silicon nitride (SiN) film can be used when using etching liquid
comprised of, e.g., hydrofluoric acid. Subsequently, a sacrifice
layer 41 is formed on the entire surface of the first insulating
film 13. In the present Example, as the sacrifice layer 41, a
polycrystalline silicon film is deposited by a CVD method.
[0136] Then, as shown in FIGS. 23A-23C, using general lithography
technique and etching technique, the sacrifice layer 41 in the
portion, in which a support post (so-called anchor) to be formed
later for supporting the diaphragm is formed (when a not shown
auxiliary support post is formed, a portion corresponding to the
auxiliary support post is included), is selectively removed by
etching to form an opening section 42, thus forming a sacrifice
layer pattern 43. That is, the single sacrifice layer pattern 43 is
basically formed in a rectangular parallelepiped form, the region
in which the support post is formed is removed to have a comb
teeth-like form, the removed portion constitutes the opening
section 42, and the region in communication with the sacrifice
layer pattern 43 for forming the space in the adjacent fluid
actuating apparatus has a comb teeth-like form by the sacrifice
layer 41. The etching for the sacrifice layer 41 is preferably dry
etching by which processing with high precision can be achieved
since there is a portion which must be processed into a comb
teeth-like form.
[0137] Then, as shown in FIGS. 24A-24B, a second insulating film 14
for covering the surface of the sacrifice layer pattern 43 is
formed on the first insulating film 13. Like the first insulating
film 13, the second insulating film 14 is formed from a film having
a resistance to the etching liquid or etching gas used for etching
the sacrifice layer 41. In the present Example, the sacrifice layer
41 comprised of a polycrystalline silicon film is removed by
etching using, e.g., sulfur hexafluoride (SF.sub.6), carbon
tetrafluoride (CF.sub.4), or xenon difluoride (XeF.sub.2), and
therefore the second insulating film 14 is formed from a silicon
oxide film (SiO.sub.2 film) by, e.g., thermal oxidation or CVD so
that the second insulating film serves as an etching stopper. In
addition, the second insulating film 14 is required to protect the
diaphragm-side electrode, and to prevent discharge caused when the
diaphragm and the substrate-side electrode 12 are close to each
other and to prevent short-circuiting caused when the diaphragm is
in contact with the substrate-side electrode 12. When the
substrate-side electrode is not etched by the etchant for the
sacrifice layer, e.g., hydrofluoric acid used for etching the
silicon oxide (SiO.sub.2 film) sacrifice layer, and further a
satisfactory pressure resistance can be secured only by the second
insulating film 14, the first insulating film can be omitted.
[0138] Next, as shown in FIGS. 25A-25B, an independent
diaphragm-side electrode 15 is formed on the second insulating film
14. In the present Example, the diaphragm-side electrode 15 is
formed as follows. An amorphous silicon film is deposited by, e.g.,
a chemical vapor deposition (CVD) method, and then doped with an
impurity, e.g., phosphorus (P). Then, the impurity as dopant is
activated by a heat treatment so that the electrode has conduction
properties, thus forming the diaphragm-side electrode 15 comprised
of polycrystalline silicon. The diaphragm-side electrode 15 is
formed through the second insulating film 14 on the sacrifice layer
pattern 43 including a portion between the support post-forming
regions.
[0139] The diaphragm-side electrode 15 is formed from an
impurity-doped polycrystalline silicon film, but it can be also
formed from an impurity-doped metal film {e.g., platinum (Pt),
titanium (Ti), aluminum (Al), gold (Au), chromium (Cr), nickel
(Ni), or copper (Cu)}, ITO (indium tin oxide) film, or the like. As
a method for forming the film, various film formation methods, such
as an evaporation method, a vapor deposition method, and a
sputtering method, can be used.
[0140] Next, as shown in FIGS. 26A-26B, a third insulating film 16
for covering the diaphragm-side electrode 15 is formed. The third
insulating film 16 may be formed from either a silicon oxide
(SiO.sub.2) film obtained by, for example, subjecting the surface
of the diaphragm-side electrode 15 to thermal oxidation, or silicon
oxide deposited by a chemical vapor deposition (CVD) method or the
like. The third insulating film 16 is formed for the purpose of
relaxing the stress applied to the diaphragm-side electrode 15 by a
diaphragm 17, and, when the stress relaxation is not required, it
can be omitted.
[0141] Then, as shown in FIGS. 27A-27B, a diaphragm 17 for
providing a pressure change in fluid is formed on the entire
surface of the third insulating film 16. The diaphragm 17 is formed
from, for example, an insulating film, especially preferably formed
from a silicon nitride film (SiN film) which generates a tension
stress and high repulsion force as a diaphragm. As an example of a
method for forming the film, there can be mentioned a reduced
pressure CVD method. When the diaphragm 17 is formed from a silicon
nitride film (SiN film) as mentioned above, the diaphragm 17 has a
tension stress and high repulsion force which are advantageous to
the diaphragm.
[0142] Next, as shown in FIGS. 28A-28B, a fourth insulating film 18
for covering the diaphragm 17 is formed. The fourth insulating film
18 is formed from, e.g., a silicon oxide film. With respect to the
insulating film 18, for example, when an ink, a chemical agent, or
another liquid is used as a fluid, the hydrophilic insulating film
18 is formed as the liquid contacting surface. When gas is used as
a fluid, the insulating film 18 having a resistance to the gas is
formed. When sulfur hexafluoride (SF.sub.6), carbon tetrafluoride
(CF.sub.4), or xenon difluoride (XeF.sub.2) gas is used for etching
of the sacrifice layer pattern 43, it is preferred that the
insulating film 18 is formed from an oxide film (e.g., silicon
oxide film) having a resistance to the etching gas.
[0143] The diaphragm 17 comprised of a silicon nitride film has a
construction such that it is disposed between the third insulating
film 16 and the fourth insulating film 18, and this construction is
effective in preventing warpage of the diaphragm when a stacked
structure of the silicon nitride film having a tension stress and
the silicon oxide film having a compression stress is formed. In
the stacked structure of the silicon nitride film and the silicon
oxide film, the diaphragm is markedly bent downwards due to the
synergetic effect of the tension stress and the compression stress,
lacking in the deflection of the diaphragm. By covering the both
sides of the silicon nitride film with a silicon oxide film, the
warpage can be relaxed. Therefore, in the present Example, the
diaphragm is comprised of substantially the second insulating film
14, the diaphragm-side electrode 15, the third insulating film 16,
the diaphragm 17, and the fourth insulating film 18.
[0144] In the support post-forming region which is formed so that
it intrudes into the side portion of the sacrifice layer pattern 43
and has a comb teeth-like form, the support post 21 is formed from
the second insulating film 14, the third insulating film 16, the
diaphragm 17, and the fourth insulating film 18.
[0145] Next, as shown in FIGS. 29A-29B, near the support post 21,
an opening section 44 which penetrates the fourth insulating film
18, the diaphragm 17, the third insulating film 16, the second
insulating film 14, and the like is formed so that the sacrifice
layer pattern 43 is exposed. The opening section 44 serves as a
vent hole in the removal of the sacrifice layer pattern 43 by
etching, and it can be formed by anisotropic dry etching, e.g.,
reactive ion etching (RIE). The opening section may have a size as
small as 2 .mu.m square or less, and, the smaller the size of the
opening section, the more easily the opening section can be sealed
up. It has been confirmed that a 0.5 .mu.m square of the opening
section is satisfactory in dry etching for the sacrifice layer.
Further, in the present Example, when the diaphragm 17 used is
thin, for improving the repulsion force of the diaphragm 17 itself,
an auxiliary support post (so-called post)(not shown) can be formed
immediately under the middle of the diaphragm 17 simultaneously
with the support post 21.
[0146] Then, as shown in FIGS. 30A-30B, etching liquid or etching
gas is introduced through the opening section 44. In the present
Example, sulfur hexafluoride (SF.sub.6), carbon tetrafluoride
(CF.sub.4), or xenon difluoride (XeF.sub.2) gas is introduced and
the sacrifice layer pattern 43 (see FIGS. 29A-29B) is removed by
etching to form a space 31 between the diaphragm 17 and the
substrate-side electrode 12 integrally having the diaphragm-side
electrode 15. In this case, a plurality of opening sections 44 are
formed along the long side of the diaphragm 17 and etching proceeds
in the direction along the short side of the diaphragm 17 through
the opening sections 44, so that the etching can be done in a short
time. When silicon, such as polycrystalline silicon, is used in the
sacrifice layer pattern 43, it can be removed by etching using
sulfur hexafluoride (SF.sub.6), carbon tetrafluoride (CF.sub.4), or
xenon difluoride (XeF.sub.2) gas. When a silicon oxide film
(SiO.sub.2 film) is used in the sacrifice layer pattern 43, it can
be removed by etching using etching liquid comprised of
hydrofluoric acid. When the sacrifice layer pattern 43 is removed
using etching liquid, a drying treatment is carried out. Thus, the
space 31 is formed in a region formed by removing the sacrifice
layer pattern 43, and further, in the support post-forming region
formed at the side portion of the space 31, the support post 21 is
formed from the second insulating film 14, the third insulating
film 16, the diaphragm 17, and the fourth insulating film 18.
[0147] Next, as shown in FIGS. 31A-31B, the opening section 44 is
sealed up with a sealing member 45. The sealing can be made by a
metal sputtering method of aluminum (Al) or the like, but the space
31 as a vibration chamber is under a reduced pressure and hence the
diaphragm 17 is bent downwards, so that a stress is always applied
to the vicinity of the support post 21 (or auxiliary support post)
of the diaphragm 17. In addition, when the diaphragm 17 is bent
downwards, the deformable range of the diaphragm 17 is narrow.
Considering this point, a method can be employed in which, for
example, a boron phosphorus silicate glass (BPSG) film is formed,
followed by reflow, to seal the opening section 44 up. By
conducting the reflow in an atmosphere of nitrogen gas (N.sub.2)
under pressure, the pressure of the space 31 as a vibration chamber
can be controlled to be a desired value. Alternatively, the opening
section 44 can be sealed up utilizing the viscosity of the member
forming the below-mentioned pressure chamber. Thus, the fluid
actuating apparatus 3 is produced.
[0148] The method for producing the fluid actuating apparatus 3 of
the present invention comprises the step for forming the
diaphragm-side electrode 15 through the second insulating film 14
on the sacrifice layer pattern 43 including a portion between the
support post-forming regions, and therefore, there can be produced
a fluid actuating apparatus having a construction such that, as
compared to the construction in which the diaphragm-side electrode
is formed so that it covers the whole of the bottom of the support
post 21, the amount of the charge, which does not contribute to
deformation of the diaphragm 17 and which is stored on the bottom
of the support post 21, is small, thus suppressing a waste of the
power consumption. In addition, there is an advantage in that the
strength of the diaphragm 17 is larger than that in the
construction in which the diaphragm-side electrode is formed so
that it does not extend to the support post 21.
EXAMPLE 7
[0149] Next, the electrostatically-actuated fluid discharge
apparatus according to the second embodiment of the present
invention will be described with reference to the diagrammatic
perspective view of FIG. 32 and the diagrammatic cross-sectional
views of FIGS. 33A-33B. In this Example, an electrostatic head is
described as an example of the electrostatically-actuated fluid
discharge apparatus using the fluid actuating apparatus of the
present invention.
[0150] First, as shown in FIG. 32, an electrostatically-actuated
fluid discharge apparatus (electrostatic head) 4 according to the
present embodiment comprises a fluid actuating apparatus 3
comprising a plurality of diaphragms 17 actuated (vibrated) by
electrostatic force, which diaphragms are arranged in a line with
high density, and a so-called fluid feed zone 55 comprising a
partition structure 54 which is disposed above the diaphragms 17 at
the corresponding position, and which has formed therein a pressure
chamber (so-called cavity) 51 for storing a fluid 61 (indicated by
an arrow) and a discharge section 53 for discharging the fluid 61,
a nozzle in the present Example (since liquid is used as a fluid).
The figure shows a construction in which auxiliary support posts
(posts) 23 are formed between the support posts (anchors) 21.
[0151] As shown in FIGS. 33A-33B, in the fluid actuating apparatus
3 of the present invention is formed a partition structure having
the pressure chamber 51 and the nozzle 53 so that a partition 52 of
the fluid feed zone 55 is formed at the position corresponding to
the support post 21 for supporting the diaphragm 17. That is, the
fluid feed zone 55 is arranged. The pressure chamber 51 is in
communication with a fluid feed channel (not shown).
[0152] The operation of the electrostatically-actuated fluid
discharge apparatus 4 is similar to the above-described operation
of the electrostatically-actuated fluid discharge apparatus 2.
EXAMPLE 8
[0153] Next, the method for producing an electrostatically-actuated
fluid discharge apparatus according to the second embodiment of the
present invention will be described with reference to the views of
FIGS. 34 and 35 showing the steps in the production process. The
views of FIGS. 34 and 35 showing the steps in the production
process show cross-sectional structures at positions similar to the
positions of the cross-section taken along the line A-A and the
cross-section taken along the line B-B shown in the plan view of
the layout of FIG. 20A.
[0154] A fluid actuating apparatus 3 is produced by the process
described above with reference to FIGS. 21 to 31, and then, as
shown in FIGS. 35A-35B, a partition-forming film is deposited on
the fluid actuating apparatus 3. The partition-forming film can be
formed from, e.g., a photo-curing resin material, such as an epoxy
resin material having photosensitive properties. Then, the
partition-forming film is patterned using a lithography technique
and an etching technique to form a partition 52 (52A) constituting
a pressure chamber (so-called chamber) 51 for storing a fluid and a
fluid feed channel (not shown) in communication with the pressure
chamber 51. Specifically, the pressure chamber 51 is formed on the
diaphragm 17, and the partition 52 constituting the pressure
chamber 51 is formed, for example, on and between the support posts
21 of the adjacent fluid actuating apparatus 3.
[0155] Then, as shown in FIGS. 35A-35B, the partition 52 (52B)
having a discharge section (e.g., nozzle) 53 is joined or bonded to
the upper edge faces of the partition 52A so that each pressure
chamber 51 is closed at the upper portion. The partition 52B is
comprised of, for example, a sheet material (so-called a nozzle
sheet), and can be formed from a predetermined material, e.g., a
metal, such as nickel or stainless steel, or a Si wafer. The
electrostatically-actuated fluid discharge apparatus 4 of the
present invention is obtained through the steps described
above.
[0156] The opening section 44 in the diaphragm 17 described above
with reference to FIGS. 31A-31B can be sealed up not by forming a
sealing member 45 by metal sputtering but by forming the sealing
member 45 using a photo-curing resin and controlling the viscosity
of the photo-curing resin.
[0157] In the fluid actuating apparatus 3 in the present Example,
the diaphragm 17 is deflected by electrostatic force and the
restoring force is used as actuating force, and therefore a fluid
in a very small volume can be fed while controlling it with high
precision. By forming an auxiliary support post 23 immediately
under the middle of the diaphragm 17, even when the diaphragm 17 is
thin or the short side width of the diaphragm 17 is long, the
length of the diaphragm 17 between the support posts 21 appears to
be short, so that the repulsion force of the diaphragm 17 can be
increased, thus obtaining required actuating force.
[0158] By virtue of the construction in which the diaphragm 17 is
supported by a plurality of support posts 21 which are integrated
with the diaphragm, and the opening section 44 for introducing an
etchant used for etching of the sacrifice layer pattern 43 is
formed near the support post 21, with respect to the formation of
the space 31 between the diaphragm 17 having a long side of about
0.5 to 3 mm and a short side of about 15 to 100 .mu.m and the
substrate-side electrode 12, the space 31 to be formed by removing
the sacrifice layer pattern 43 under the diaphragm 17 can be formed
by performing etching in the direction of the short side, and
hence, not only can the etching be done in a short time, but also
the space 31 under the adjacent diaphragm 17 can be simultaneously
formed with high precision. Therefore, there can be provided the
fluid actuating apparatus 3 which can secure actuating force for
the fluid and achieve high density.
[0159] When the substrate-side electrode 12 on the lower side is
formed as a common electrode and the diaphragm-side electrode 15 on
the upper side is formed in the form of a plurality of independent
electrodes, the lower surface of the diaphragm 17 can be flattened.
When the substrate-side electrode 12 on the lower side is in a
separate form, the step due to the thickness of the electrode
appears as a step of the diaphragm 17, and hence the tension stress
of the diaphragm 17 is relaxed by the step, so that the tension
stress does not effectively act. On the other hand, the diaphragm
17 comprised of a silicon nitride (SiN) film and the diaphragm-side
electrode 15 comprised of polycrystalline silicon (Si) are disposed
so that the diaphragm-side electrode 15 closely adheres to the side
of the lower surface of the diaphragm 17 formed by the step portion
through the third insulating film 16, and therefore, even when the
diaphragm 17 has a step portion, the tension of the diaphragm 17 is
not absorbed by the step portion.
[0160] When the positions of the diaphragm 17 comprised of a
silicon nitride (SiN) film and the diaphragm-side electrode 15
comprised of polycrystalline silicon (Si) are switched, that is,
when the diaphragm 17 comprised of a silicon nitride film is first
formed and the diaphragm-side electrode 15 comprised of
polycrystalline silicon is formed on the diaphragm, the diaphragm
17 can be flattened, but the voltage between the substrate-side
electrode 12 and the diaphragm-side electrode 15 is also
distributed to the SiN film having a higher specific permittivity,
and therefore the effective voltage applied to the space 31 between
the lower surface of the diaphragm 17 and the upper surface of the
substrate-side electrode 12 is lowered and thus the electrostatic
attraction force is lowered, so that the deflection of the
diaphragm 17 is reduced, which is disadvantageous to the actuation
with low power consumption.
[0161] When the fluid 61 fed to the pressure chamber 51 is liquid
and the portion in contact with the liquid is comprised of a
conductor, air bubbles may be formed in the liquid 61 at the
conductor surface or the conductor surface may suffer corrosion,
but, in the present Example, the diaphragm 17 is disposed on the
diaphragm-side electrode 15 and the surface of the diaphragm 17 is
covered with the fourth insulating film 18, and hence the above
problem does not occur.
[0162] When the fluid 61 is liquid, by forming on the surface of
the diaphragm 17 the fourth insulating film 18 from a hydrophilic
film, flowing of the liquid 61 into the pressure chamber 51 can be
facilitated. On the other hand, when the fluid 61 is gas, by
forming on the surface of the diaphragm 17 the fourth insulating
film 18 having a resistance to the gas, the diaphragm 17 is
prevented from suffering corrosion due to the gas.
[0163] In the method for producing the fluid actuating apparatus 3
in the present Example, when the sacrifice layer 41 and the
diaphragm 17 are formed by vapor deposition, the following effects
can be obtained. The interval between the electrodes and the
thickness of the diaphragm 17 are uniform, so that the dispersion
of the actuation voltage between the diaphragms 17 is reduced. The
flatness of the surface of the diaphragm 17 is improved. The
control of the electrode interval and the thickness of the
diaphragm 17 is easy, and hence the diaphragm 17 having a desired
thickness can be easily formed by controlling the time or
temperature for deposition. The sacrifice layer and diaphragm can
be easily formed by a general semiconductor process, which is
advantageous to mass production.
[0164] The opening section 44 is formed near the support post 21
and the sacrifice layer pattern 43 is removed by etching through
the opening section 44, and therefore the space 31 between the
diaphragm 17 and the substrate-side electrode 12 can be formed with
high precision. A plurality of opening sections 44 are formed along
the longitudinal direction of the diaphragm 17, and hence etching
of the sacrifice layer pattern 43 proceeds in the direction of the
short side of the diaphragm 17, thus making it possible to reduce
the time for the etching.
[0165] In the electrostatically-actuated fluid discharge apparatus
4 in the present Example, by virtue of having the above-described
fluid actuating apparatus 3, not only can the discharge sections 53
for the fluid 61, nozzles in the present Example be arranged with
high density, but also the fluid in a very small volume can be fed
by high actuating force while controlling it with high
accuracy.
[0166] The electrostatically-actuated fluid discharge apparatus 4
involves an apparatus having a construction such that the pressure
chamber 51 is comprised of a plurality of high pressure chamber,
intermediate pressure chamber, and low pressure chamber and the
pressure chambers 51 are connected to one another, and a back-flow
valve is disposed between the pressure chambers 51 and a pressure
difference is utilized to permit the fluid to flow. As an example,
there can be mentioned an apparatus having a construction similar
to that of the electrostatically-actuated fluid discharge apparatus
1 described above with reference to FIG. 18.
[0167] When gas is used as a fluid, the electrostatically-actuated
fluid discharge apparatus 4 can be produced so that a not shown
valve is basically provided at the discharge outlet of the pressure
chamber 51.
[0168] In the present invention, the electrostatically-actuated
fluid discharge apparatus 4 comprising the fluid actuating
apparatus 3 including the diaphragm 17, and the partition structure
54 having the pressure chamber 51 and the discharge section (e.g.,
nozzle) 53 for a fluid can be produced by surface micromachining
without using lamination. In the step for removing by etching the
sacrifice layer pattern 43 through the opening section 44 formed
near the support post 21 and other steps, a generally used
semiconductor process can be utilized, thus lowering the cost for
the fluid actuating apparatus 3 and the electrostatically-actuated
fluid discharge apparatus 4.
[0169] The electrostatically-actuated fluid discharge apparatus 4
can also be produced by stacking on the fluid actuating apparatus 3
the separately formed partition structure 54 having the discharge
section (e.g., nozzle) 53, the pressure chamber 51, and a fluid
feed channel (not shown). Further, for example, as described above
with reference to FIG. 19, a plurality of opening sections 44 can
be formed near the single support post 21.
[0170] It should be understood by those skilled in the art that
various modifications, combinations, sub-combinations and
alterations may occur depending on design requirements and other
factors insofar as they are within the scope of the appended claims
or the equivalents thereof.
* * * * *