U.S. patent application number 09/290409 was filed with the patent office on 2002-01-17 for method of producing micro structure, method of producing liquid discharge head.
Invention is credited to HIROKI, TOMOYUKI, KUBOTA, MASAHIKO, OZAKI, TERUO, YAGI, TAKAYUKI.
Application Number | 20020006584 09/290409 |
Document ID | / |
Family ID | 26446417 |
Filed Date | 2002-01-17 |
United States Patent
Application |
20020006584 |
Kind Code |
A1 |
YAGI, TAKAYUKI ; et
al. |
January 17, 2002 |
METHOD OF PRODUCING MICRO STRUCTURE, METHOD OF PRODUCING LIQUID
DISCHARGE HEAD
Abstract
A method of producing a micro structure on a substrate which has
a support portion and a plate-like portion supported thereby at a
distance from the substrate, comprising the steps of forming a
spacer layer consisting of an insulating material on a substrate
having an electrically conductive layer formed on its surface,
forming a latent image layer consisting of an electrically
conductive material on the spacer layer at a site where the
plate-like portion of an intended structure is to be formed,
producing an aperture, where a part of the electrically conductive
layer is exposed, on the spacer layer at a site where the
supporting portion of an intended structure is to be formed,
forming a structure layer consisting of plating film inside of the
aperture and on the latent image layer by electroplating the
electrically conductive layer as a cathode, and removing the spacer
layer.
Inventors: |
YAGI, TAKAYUKI;
(YOKOHAMA-SHI, JP) ; HIROKI, TOMOYUKI; (ZAMA-SHI,
JP) ; OZAKI, TERUO; (YOKOHAMA-SHI, JP) ;
KUBOTA, MASAHIKO; (TOKYO, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Family ID: |
26446417 |
Appl. No.: |
09/290409 |
Filed: |
April 13, 1999 |
Current U.S.
Class: |
430/313 ;
430/314; 430/316; 430/317; 430/318 |
Current CPC
Class: |
B41J 2/1629 20130101;
B41J 2/14048 20130101; B41J 2/1645 20130101; B41J 2/1639 20130101;
B41J 2/1643 20130101; B41J 2/1628 20130101; B41J 2/1646 20130101;
B41J 2/1604 20130101; B41J 2/1642 20130101; B41J 2/1631 20130101;
B41J 2202/13 20130101 |
Class at
Publication: |
430/313 ;
430/314; 430/316; 430/317; 430/318 |
International
Class: |
G03F 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 16, 1998 |
JP |
10-106295 |
Apr 16, 1998 |
JP |
10-106298 |
Claims
What is claimed is:
1. A method of producing a micro structure on a substrate which has
a support portion and a plate-like portion supported thereby at a
distance from said substrate, comprising the steps of: forming a
spacer layer consisting of an insulating material on a substrate
having an electrically conductive layer formed on its surface,
forming a latent image layer consisting of an electrically
conductive material on said spacer layer at a site where said
plate-like portion of a structure is to be formed, producing an
aperture, where a part of said electrically conductive layer is
exposed, on said spacer layer at a site where said supporting
portion of a structure is to be formed, forming a structure layer
consisting of plating film inside of said aperture and on said
latent image layer by electroplating said electrically conductive
layer as a cathode, and removing said spacer layer.
2. The method of producing a micro structure according to claim 1
further comprising the step of: forming a second spacer layer on
one site of said latent image layer, wherein said metal plating
film is developed to such a height that it can surround said second
spacer layer.
3. The method of producing a micro structure according to claim 2,
wherein said aperture is provided in an area surrounding said
latent image layer.
4. The method of producing a micro structure according to claim 3
further comprising the step of: removing a site of said substrate
from the back side thereof so as to expose a site of the spacer
layer formed on said electrically conductive layer.
5. The method of producing a micro structure according to claim 1,
wherein a plurality of said latent image layers are formed leaving
a space between them.
6. The method of producing a micro structure according to claim 1
further comprising the step of: removing said latent image layer
after said structure layer is formed.
7. The method of producing a micro structure according to claim 1,
wherein said spacer layer consists of a high polymer resin.
8. The method of producing a micro structure according to claim 7,
wherein said spacer layer is removed using oxygen plasma.
9. The method of producing a micro structure according to claim 1,
wherein said structure has at least a discharge port for
discharging liquid, a liquid flow path in communication with said
discharge port for supplying said liquid to said discharge port, a
substrate provided with a heating element for allowing said liquid
filled in said liquid flow path to generate bubble, and a movable
member supported by and fixed to said substrate at a position apart
from said substrate and opposite to said heating element with its
free end toward said discharge port, and said structure is a
movable member of the liquid discharge head for discharging said
liquid from said discharge port whose free end is displaced toward
said discharge port around a supporting point constructed in the
neighborhood of the portion where said movable member is supported
by and fixed to said substrate by pressure generated by said bubble
generation.
10. The method of producing a micro structure according to claim 9,
wherein said latent image layer is formed on said spacer layer at a
distance therefrom along the liquid flow of said liquid flow
path.
11. The method of producing a micro structure according to claim 9,
wherein the step of providing an aperture, where a part of said
electrically conductive layer is exposed, at a site of said spacer
layer, where a support portion of the structure to be produced is
formed, comprises at least the steps of: forming an etching mask on
said spacer layer leaving the portion of said spacer layer
corresponding to said support portion of said structure, and
removing the portion of said spacer layer corresponding to the
support portion of said structure by etching, wherein said latent
image layer is used as a part of said etching mask.
12. The method of producing a micro structure according to claim 9,
wherein the step of forming a structure layer consisting of a metal
plating film in said aperture as well as on said latent image layer
by electroplating using said electrically conductive layer as a
cathode comprises the steps of: forming a support portion of said
structure by developing said metal plating layer in said aperture,
and forming a metal plating layer constituting said movable member
on said electrically conductive layer as well as on said latent
image layer by further developing said metal plating layer to allow
said electrically conductive layer and said latent image layer to
be electrically connected.
13. A method of producing a liquid discharge head for discharging
liquid from a discharge port, wherein said liquid discharge head
has at least a discharge port for discharging liquid, a liquid flow
path in communication with said discharge port for supplying said
liquid to said discharge port, a substrate provided with a heating
element for allowing said liquid filled in said liquid flow path to
generate bubble, and a movable member supported by and fixed to
said substrate at a position apart from said substrate and opposite
to said heating elements with its free end toward said discharge
port, and said liquid discharge head discharges said liquid from
said discharge port by having the free end of said movable member
displaced toward said discharge port around a supporting point
constructed in the neighborhood of the portion where said movable
member is supported by and fixed to said substrate by pressure
generated by said bubble generation, characterized in that the
method comprises the steps of: forming an electrically conductive
layer consisting of an electrically conductive material on the top
layer of said substrate, forming a spacer layer for making said
void on said electrically conductive layer, forming a latent image
layer consisting of an electrically conductive material on said
spacer layer so that said latent image layer can have almost the
same shape as said movable member, removing a portion of said
spacer layer corresponding to the portion where said movable member
is supported and fixed, so as to expose a part of said electrically
conductive layer so as to form an aperture on the more upstream
side of said liquid flow path, in terms of liquid flow direction,
relative to said latent image layer, forming a metal plating layer
constituting said movable member on said electrically conductive
layer as well as on said latent image layer by electroplating using
said electrically conductive layer as a cathode, and forming said
movable member by removing said spacer layer.
14. The method of producing a liquid discharge head according to
claim 13, wherein the step of forming a latent image layer
consisting of an electrically conductive material on said spacer
layer so that the latent image layer can have almost the same shape
as said movable member consists of the step of forming said latent
image layer on said spacer layer at a distance therefrom along said
liquid flow path in terms of liquid flow direction.
15. The method of producing a liquid discharge head according to
claim 13, wherein the step of removing a portion of said spacer
layer corresponding to the portion where said movable member is
supported and fixed, so as to expose a part of said electrically
conductive layer so as to form an aperture on the more upstream
side of said liquid flow path, in terms of liquid flow direction,
relative to said latent image layer comprises at least the steps
of: forming an etching mask on said spacer layer leaving the
portion of said spacer layer corresponding to said portion where
said movable member is supported and fixed, and removing the
portion of said spacer layer corresponding to said portion where
said movable member is supported and fixed by etching, wherein said
latent image layer is used as a part of said etching mask.
16. The method of producing a liquid discharge head according to
claim 13, wherein the step of forming a metal plating layer
constituting said movable member on said electrically conductive
layer as well as on said latent image layer by electroplating using
said electrically conductive layer as a cathode comprises the steps
of: forming said portion where said movable member is supported and
fixed by developing said metal plating layer in said aperture, and
forming a metal plating layer constituting said movable member on
said electrically conductive layer as well as on said latent image
layer by further developing said metal plating layer to allow said
electrically conductive layer and said latent image layer to be
electrically connected.
17. The method of producing a liquid discharge head according to
claim 13, wherein high polymer resins are used as a material for
said spacer layer.
18. The method of producing a liquid discharge head according to
claim 13, wherein the step of removing said spacer layer consists
of the step of removing said spacer layer by oxygen plasma.
19. A liquid discharge head, wherein said liquid discharge head has
at least a discharge port for discharging liquid, a liquid flow
path in communication with said discharge port for supplying said
liquid to said discharge port, a substrate provided with a heating
element for allowing said liquid filled in said liquid flow path to
generate bubble, and a movable member supported by and fixed to
said substrate at a position apart from said substrate and opposite
to said heating element with its free end toward said discharge
port, and said liquid discharge head discharges said liquid from
said discharge port by having the free end of said movable member
displaced toward said discharge port around a supporting point
constructed in the neighborhood of the portion where said movable
member is supported by and fixed to said substrate by pressure
generated by said bubble generation, characterized in that said
liquid discharge head is produced by the method comprises the steps
of: forming an electrically conductive layer consisting of an
electrically conductive material on the top layer of said
substrate, forming a spacer layer for making said void on said
electrically conductive layer, forming a latent image layer
consisting of an electrically conductive material on said spacer
layer so that said latent image layer can have almost the same
shape as said movable member, removing a portion of said spacer
layer corresponding to the portion where said movable member is
supported and fixed, so as to expose a part of said electrically
conductive layer so as to form an aperture on the more upstream
side of said liquid flow path, in terms of liquid flow direction,
relative to said latent image layer, forming a metal plating layer
constituting said movable member on said electrically conductive
layer as well as on said latent image layer by electroplating using
said electrically conductive layer as a cathode, and forming said
movable member by removing said spacer layer.
20. The liquid discharge head according to claim 19, wherein the
step of forming a latent image layer consisting of an electrically
conductive material on said spacer layer so that said latent image
layer can have almost the same shape as said movable member
consists of the step of forming said latent image layer on said
spacer layer at a distance therefrom along said liquid flow path in
terms of liquid flow direction, and said movable member is formed
in such a manner that the thickness is thinner near said free end
than near said supporting point along said liquid flow path in
terms of liquid flow direction.
21. The liquid discharge head according to claim 19, wherein the
step of removing a portion of said spacer layer corresponding to
the portion where said movable member is supported and fixed, so as
to expose a part of said electrically conductive layer so as to
form an aperture on the more upstream side of said liquid flow
path, in terms of liquid flow direction, relative to said latent
image layer comprises at least the steps of: forming an etching
mask on said spacer layer leaving the portion of said spacer layer
corresponding to said support portion of said movable member, and
removing the portion of said spacer layer corresponding to the
support portion of said movable member by etching, wherein said
latent image layer is used as a part of said etching mask.
22. The liquid discharge head according to claim 19, wherein the
step of forming a metal plating layer constituting said movable
member on said electrically conductive layer as well as on said
latent image layer by electroplating using said electrically
conductive layer as a cathode comprises the steps of: forming a
support portion of said structure by developing said metal plating
layer in said aperture, and forming a metal plating layer
constituting said movable member on said electrically conductive
layer as well as on said latent image layer by further developing
said metal plating layer to allow said electrically conductive
layer and said latent image layer to be electrically connected.
23. The liquid discharge head according to claim 19, wherein said
spacer layer consists of high polymer resins.
24. The liquid discharge head according to claim 19, wherein the
step of removing said spacer layer comprises the step of removing
said spacer layer by oxygen plasma.
25. A head cartridge having the liquid discharge head according to
any one of claims 19 to 24 and a container housing liquid supplied
to said liquid discharge head.
26. A liquid discharge device having the liquid discharge head
according to any one of claims 19 to 24 and a drive signal
supplying means for supplying a drive signal to discharge liquid
from said liquid discharge head.
27. A liquid discharge device having the liquid discharge head
according to any one of claims 19 to 24 and a recording medium
conveying means for conveying a recording medium for receiving
liquid discharged from said liquid discharge head.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method of producing a
micro structure using a micro mechanics, particularly to a method
of producing a micro structure using electroplating, a method of
producing a liquid discharge head, a liquid discharge head produced
thereby, a head cartridge loaded with said liquid discharge head,
and a device for discharging liquid produced therewith.
[0003] 2. Related Background Art
[0004] In recent years, a micro machine having a small movable
mechanism has been investigated by using micro mechanics
techniques. Especially, a micro structure produced by using a
semiconductor integrated circuit production technique
(semiconductor photo lithography process) makes it possible to
produce on a substrate a plurality of micro machine parts which are
more miniaturized and highly reproductive. Accordingly, this
provides relatively easier arraying and lower production costs, in
addition, with such miniaturization, and more rapid responsibility
can be expected as compared with conventional mechanical
structures.
[0005] Of the micro mechanics techniques using a semiconductor
photo lithography process, surface micro-machining which uses a
sacrifice layer is a method in which micro structures such as a
micro cantilever, a linear actuator or the like can be easily made
on a substrate, and various devices have been developed using this
process.
[0006] Two typical surface micro-machining methods which use a
sacrifice layer will be described below.
[0007] A first surface micro-machining method is such that a poly
silicon film or an SOI (Si on Insulator) film, formed into a thin
layer through a silicon dioxide film on a silicon substrate, which
is to become a micro structure is patterned in a desired shape and
then the oxidizing film of silicon dioxide is removed with an
aqueous solution of hydrofluoric acid. With this method, a linear
actuator (D. Kobayashi et al., "An Integrated Lateral Tunneling
Unit," Proceedings of IEEE Micro Electro Mechanical Systems
Workshop 1992, pp.214-219) or the like can be manufactured. In this
method, a sacrifice layer for use in producing micro structures is
a single layer common to all of the structures.
[0008] FIGS. 5A to 5E are diagrammatic illustrations of the
production process of micro structures using this method. First, a
silicon dioxide film 511 as a sacrifice layer, a poly silicon film
513 as a structure layer and a nickel mask layer 514 are formed on
a substrate 512 in this order (FIG. 5A). The nickel mask layer 514
is then patterned, and using this as a mask, the poly silicon film
513 is etched to produce micro structures A, B and C comprising the
poly silicon film 513 (FIG. 5B). After this, the nickel mask layer
514 is removed to allow the poly silicon film 513 to be exposed
(FIG. 5C), then the silicon dioxide film 511 is etched with an
aqueous solution of hydrofluoric acid. This produces a void below
the central micro structure B, as shown in FIG. 5D. And in the
micro structures A and C on both sides of the micro structure B,
the silicon dioxide film 511 which supports both A and C is
side-etched to have a cantilever shape. Lastly, a metal film 515
which is a laminate of Cr and Au in this order is deposited on the
surface of each of the structures A, B and C so as to produce
electrically conductive micro structures A, B and C (FIG. 5E).
[0009] A second surface micro-machining method is such that micro
structures are produced on the sacrifice layer, which has been
formed into a desired pattern, by the thin-film formation process.
With this method, a wharve micro motor (M. Mehregany et al.,
"Operation of microfabricated harmonic and ordinary side-drive
motors," Proceedings IEEE Micro Electro Mechanical Systems Workshop
1990, pp.1 to 8), a cantilever (L. C. Kong et al., Integrated
electrostatically resonant scan tip for an atomic force microscope"
J. Vac. Sci. Technol. B11(3), p.634, 1993) or the like can be
produced.
[0010] FIGS. 6A to 6D illustrate the production process of a
cantilever using this method. First, a sacrifice film layer 611 is
formed on a silicon substrate 612 having a passivation layer 614
formed on it, after which the sacrifice layer 611 is patterned by
using semiconductor photo lithography techniques and etching (FIG.
6A). A structure layer 613, which is to become micro structures, is
then formed on the substrate 612 (FIG. 6B), and the structure layer
613 is patterned to have a desired shape using semiconductor photo
lithography techniques and etching (FIG. 6C). Then the sacrifice
layer 611 is etched with an etchant capable of removing the
sacrifice layer 611 alone so as to produce a cantilever 612 shown
in FIG. 6D. With this method, more complicated structures can be
produced by forming a plurality of sacrifice layers and structure
layers. (L. Y. Lin et al., "Micromachined Integrated Optics for
Free-Space Interconnections," Proceedings of IEEE Micro Electro
Mechanical Systems Workshop 1995, pp. 77 to 82).
SUMMARY OF THE INVENTION
[0011] The conventional methods of producing a micro structure
mentioned above, however, have problems as follows.
[0012] First, in the first method shown in FIGS. 5A to 5E, the
length of the micro structures A and C on both sides depends on the
etching conditions of the silicon dioxide film 511, therefore the
varying concentration, temperature and agitation of etching reagent
may cause its variation. The variation of the length of a micro
structure results in variation of mechanical properties, such as
spring constant, resonance frequency, etc., of the cantilever and
joist or the like which are connected to the structure. Thus, this
method leads to a reduction in reproductivity of micro
structures.
[0013] On the other hand, when the displacement of a cantilever is
caused by external force, the stress typically concentrates on the
base of the cantilever. In case of the cantilever 621 produced in
the manner shown in FIGS. 6A to 6D, the stress concentrates on an
inflection portion 622. The substrate bottom side of such an
inflection portion becomes a concentration part of the stress D
which is excessively strained, therefore deterioration in its
mechanical strength with time tends to occur at that portion, which
allows its breaking due to mechanical metal fatigue to easily
occur.
[0014] The present invention has been made in light of such
difficulties the foregoing prior arts have, and therefore, the
object of the present invention is to provide a method of producing
a micro structure of which
[0015] (1) variation in mechanical properties is small, and
[0016] (2) deterioration in its mechanical strength with time due
to the stress concentration at the inflection portion can be
controlled.
[0017] In order to attain the above object, one aspect of the
present invention provides a method of producing a micro structure
on a substrate which has a support portion and a plate-like portion
supported thereby at a distance from the substrate, comprising the
steps of:
[0018] forming a spacer layer consisting of an insulating material
on a substrate having an electrically conductive layer formed on
its surface,
[0019] forming a latent image layer consisting of an electrically
conductive material on the spacer layer at a site where the
plate-like portion of a structure is to be formed,
[0020] producing an aperture, where a part of the electrically
conductive layer is exposed, on the spacer layer at a site where
the supporting portion of a structure is to be formed, forming a
structure layer consisting of plating film inside of the aperture
and on the latent image layer by electroplating the electrically
conductive layer as a cathode, and
[0021] removing the spacer layer.
[0022] Another aspect of the present invention provides a method of
producing a liquid discharge head for discharging liquid from a
discharge port, wherein the liquid discharge head has at least a
discharge port for discharging liquid, a liquid flow path in
communication with the discharge port for supplying the liquid to
the discharge port, a substrate provided with a heating element for
allowing the liquid filled in the liquid flow path to generate
bubble, and a movable member supported by and fixed to the
substrate at a position apart from the substrate and opposite to
the heating elements with its free end toward the discharge port,
and the liquid discharge head discharges the liquid from the
discharge port by having the free end of the movable member
displaced toward the discharge port around a supporting point
constructed in the neighborhood of the portion where the movable
member is supported by and fixed to the substrate by pressure
generated by the bubble generation, characterized in that the
method comprises the steps of:
[0023] forming an electrically conductive layer consisting of an
electrically conductive material on the top layer of the
substrate,
[0024] forming a spacer layer for making the void on the
electrically conductive layer,
[0025] forming a latent image layer consisting of an electrically
conductive material on the spacer layer so that the latent image
layer can have almost the same shape as the movable member,
[0026] removing a portion of the spacer layer corresponding to the
portion where the movable member is supported and fixed, so as to
expose a part of the electrically conductive layer so as to form an
aperture on the more upstream side of the liquid flow path, in
terms of liquid flow direction, relative to the latent image
layer,
[0027] forming a metal plating layer constituting the movable
member on the electrically conductive layer as well as on the
latent image layer by electroplating using the electrically
conductive layer as a cathode, and
[0028] forming the movable member by removing the spacer layer.
[0029] Further, another aspect of the invention provides a liquid
discharge head, wherein the liquid discharge head has at least a
discharge port for discharging liquid, a liquid flow path in
communication with the discharge port for supplying the liquid to
the discharge port, a substrate provided with a heating element for
allowing the liquid filled in the liquid flow path to generate
bubble, and a movable member supported by and fixed to the
substrate at a position apart from the substrate and opposite to
the heating element with its free end toward the discharge port,
and the liquid discharge head discharges the liquid from the
discharge port by having the free end of the movable member
displaced toward the discharge port around a supporting point
constructed in the neighborhood of the portion where the movable
member is supported by and fixed to the substrate by pressure
generated by the bubble generation, characterized in that the
liquid discharge head is produced by the method comprises the steps
of:
[0030] forming an electrically conductive layer consisting of an
electrically conductive material on the top layer of the
substrate,
[0031] forming a spacer layer for making the void on the
electrically conductive layer,
[0032] forming a latent image layer consisting of an electrically
conductive material on the spacer layer so that the latent image
layer can have almost the same shape as the movable member,
[0033] removing a portion of the spacer layer corresponding to the
portion where the movable member is supported and fixed, so as to
expose a part of the electrically conductive layer so as to form an
aperture on the more upstream side of the liquid flow path, in
terms of liquid flow direction, relative to the latent image
layer,
[0034] forming a metal plating layer constituting the movable
member on the electrically conductive layer as well as on the
latent image layer by electroplating using the electrically
conductive layer as a cathode, and
[0035] forming the movable member by removing the spacer layer.
[0036] According to the present invention, as described above, a
structure having a supporting portion and a plate-like portion is
formed of a plating film deposited and developed on an electrode
and a latent image layer, wherein, since the plate-like portion of
the micro structure is formed of the plating film deposited and
developed on the latent image layer, and after forming a structure
layer of the plating film, the entire spacer layer is removed, the
size of the plate-like portion is defined by the size of the latent
image layer. Accordingly, unlike the conventional methods in which
a plate-like portion is formed by etching and removing a structure
layer immediately under the member which is to become the
plate-like portion, the length of the plate-like portion does not
vary with the etching conditions. In addition, since the supporting
portion of the micro structure is formed of a metal plating layer
deposited and developed within the aperture provided on the spacer
layer, the size of the supporting portion can be set independent of
the thickness of the plate-like portion. As a result, if the size
of the aperture portion is allowed to be larger relative to the
thickness of the plate-like portion of a structure to be made, the
stress concentration applied to the base of the plate-like portion
will be relieved. The simplest structure made according to the
present invention is, for example, a cantilever which is supported
on a substrate by a supporting portion.
[0037] Further, a micro structure provided with an aperture in its
plate-like portion can be also made by adding to the method a step
of forming a second spacer layer at one site of the latent image
layer to produce a structural layer, wherein a plating film is
developed to a height with which it can surround the second spacer
layer. In this case, if an opening is provided for the first spacer
layer in the zone surrounding the latent image layer, a hollow
micro structure having an opening provided on its top surface can
be made. Still further, if another step is added to the above
method at which one site of the substrate is removed from its
bottom side so as to expose one site of the first spacer layer
formed on the electrode, a nozzle structure can be made which is
provided with a site removed from the substrate as a liquid supply
opening and an opening on its top surface as an injection
opening.
[0038] Further, if a plurality of latent image layers are formed
leaving a space between each other, a plating film is deposited and
developed on the layers in the order of increasing distance from
the opening portion of the spacer layer. This provides a plate-like
portion of which thickness changes in multiple different levels.
Although the micro structure made still has a latent image layer on
the back of the plate-like portion, the latent image can be removed
after making a structural layer, if it is unnecessary.
[0039] The above spacer layer can be formed of high polymer resin.
In this case, preferably oxygen plasma is used to remove the spacer
layer, since it can easily peel the layer.
[0040] According to the present invention, on the spacer layer, a
latent image layer is formed of an electrically conductive material
in the shape of a movable member, and on the latent image layer, a
metal plating layer which is to be the movable member is deposited
and formed by electroplating. This allows to form a movable member
with a high accuracy and high density, and consequently, to produce
a liquid discharge head or the like which is stable in its
discharge property in discharging liquid and highly reliable.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIGS. 1A, 1B, 1C, 1D and 1E show sectional views of a micro
structure in different steps of the process to illustrate one
embodiment of the method of the present invention, employed for
producing micro structures;
[0042] FIGS. 2A, 2B, 2C and 2D illustrate the process by steps of
producing a nozzle according to the method of the present
invention, employed for producing micro structures;
[0043] FIGS. 3E, 3F and 3G illustrate the process by steps of
producing a nozzle according to the method of the present
invention, employed for producing micro structures;
[0044] FIGS. 4A, 4B, 4C, 4D and 4E illustrate the process by steps
of producing a cantilever, of which thickness changes in multiple
different levels, according to the method of the present invention,
employed for producing micro structures;
[0045] FIGS. 4A, 5B, 5C, 5D and 5E illustrate one example of the
process by steps of producing a micro structure according to the
method of the prior art;
[0046] FIGS. 6A, 6B, 6C and 6D illustrate another example of the
process by steps of producing a micro structure according to the
method of the prior art;
[0047] FIG. 7 is a sectional view of the liquid discharge head
according to the example 4 of the present invention, taken along
the liquid flow path direction to illustrate the basic construction
of one embodiment of the method of the present invention for
producing thereof;
[0048] FIG. 8 is a partially cutaway view in perspective of the
liquid discharge head shown in FIG. 7;
[0049] FIG. 9 is sectional view showing the elemental substrate, in
the neighborhood of a heating element, of the liquid discharge head
shown in FIG. 7;
[0050] FIG. 10 is a vertically cutaway schematic view in section
showing each of the main elements of the elemental substrate;
[0051] FIGS. 11A, 11B, 11C, 11D and 11E illustrate sectional views
showing a producing method of a movable member of the liquid
discharge head shown in FIG. 7;
[0052] FIGS. 12A, 12B, 12C, 12D and 12E show sectional views of a
movable member according to the example 5 of the present invention
which is in the liquid discharge head shown in FIG. 7, to
illustrate the second embodiment of the method of the present
invention for producing thereof;
[0053] FIG. 13 is a schematic sectional view showing the motion of
the movable member produced according to the second embodiment of
the method of the present invention, employed for producing a
movable member and described with reference to FIGS. 12A, 12B, 12C,
12D and 12E;
[0054] FIGS. 14A, 14B, 14C, 14D and 14E illustrate sectional views
of a movable member according to the example 6 of the present
invention which is in the liquid discharge head shown in FIG. 7, to
illustrate the third embodiment of the method of the present
invention for producing thereof;
[0055] FIG. 15 is a perspective view of a liquid discharge head
cartridge loaded with a liquid discharge head of the present
invention;
[0056] FIG. 16 is a perspective view showing a schematic
construction of a liquid discharge device loaded with a liquid
discharge head of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0057] Embodiments of the present invention will be described
referring to drawings as below.
[0058] FIGS. 1A to 1E show sectional views of a micro structure in
different steps of the process to illustrate one embodiment of the
method of the present invention, employed for producing micro
structures. Now, this embodiment will be described in further
detail by way of example of the production process of a cantilever
10a supported by a support pillar 10b on a substrate 11, with
reference to FIGS. 1A to 1E.
[0059] First, a spacer layer 13 comprising an insulating material
is formed on a substrate 11 having an electrode 12 formed on its
surface (FIG. 1A). A latent image layer 18 comprising an
electrically conductive material is then formed on the surface of
the spacer layer 13 at a predetermined zone (FIG. 1B), followed by
providing an aperture 15 of a prescribed size in the spacer layer
13 at a position adjacent to the latent image layer 18 so as to
expose the electrode 12 in the aperture 15. The latent image layer
18 is electrically insulated from the electrode 12. Then the
electrode 12 as a cathode is electroplated to allow metal plating
to be deposited on the surface of the electrode 12 exposed within
the aperture 15. With its development, the metal plating deposited
on the surface of the electrode 12 becomes closer to the latent
image layer 18, and is deposited thereon just like on the electrode
12 to form a metal plating layer 17 having a hook-shaped section
(FIG. 1D). Finally, after removing the spacer layer 13, a
cantilever 10a is produced which consists of a metal plating layer
17.
[0060] As compared with the method described with reference to
FIGS. 5A to 5E, according to this embodiment of the method of the
present invention, the size of the cantilever 10a is determined by
the size of the latent image layer 18 on the surface of the spacer
layer 13; therefore the cantilever 10a does not undergo a change in
length due to, for example, a side etching.
[0061] Also, as compared with the method described with reference
to FIGS. 6A to 6D, according to this embodiment, the size of the
aperture 15 is allowed to be larger relative to the film thickness
of the cantilever 10a; therefore, the cantilever 10a has no
inflection portion as shown in FIGS. 6A to 6D, which makes possible
a relief of the stress concentration applied to the base of the
cantilever 10a. As a result, even if the cantilever 10a is
subjected to displacement by external force, the strain arising at
its base will be decreased, which will control the age-based
deterioration of its mechanical strength as well as breaking caused
by mechanical metal fatigue.
[0062] In addition, in the production of the cantilever 10a of the
present invention, the size of the metal plating layer 17 is
determined by the size of the latent image layer 18, while, in the
conventional method, it is formed into a desired pattern by
photolithography process and etching. With the conventional method
in which a metal thin film is patterned by wet etching, if the film
is relatively thick, it is usually difficult to achieve a desired
accuracy because it gives rise to a side etching. On the other
hand, if the like metal is allowed to be formed by metal plating,
patterning is not needed, and a micro structure having a desired
pattern can be obtained.
[0063] Further, the film formed by a thin-film formation process
usually contains clusters of particles, and in the structure
produced by the thin-film formation process as shown in FIGS. 6A to
6D, the film formed on the inflection portion of the spacer layer
is highly affected by such clusters, and its strength tends to be
deteriorated. On the other hand, in the structure produced by the
method of the present invention, a support pillar 10b and a
cantilever 10a are formed at a time by metal plating, therefore the
structure is less affected by the clusters of particles.
[0064] Now, the characteristics of each of the foregoing layer will
be described below.
[0065] The electrode 12 is used as a cathode in electroplating.
Accordingly, its surface is kept electrically conductive.
[0066] Once having formed the structure layer (the metal plating
layer 17 in this embodiment) which is to become a micro structure,
the spacer layer 13 is removed in the last step of the method, and
it becomes a void between the micro structure and the substrate 11.
For the spacer layer 13, used is a material which does not corrode
in the metal plating bath used for producing a micro structure and
is highly electrically insulating. As a material, organic high
polymer resins, oxide materials such as SiO.sub.2, TiO.sub.2,
Al.sub.2O.sub.3 and MgO, nitride materials such as Si.sub.3N.sub.4
and TiN, carbide materials such as SiC, TiC and C can be utilized.
When removing the spacer layer 13, as a material constituting the
spacer layer 13, selected are the materials such that the ratio of
their etching selection to the etching selection of the materials
constituting the structure layer will be sufficiently high.
Preferable is organic high polymer resins such that they can be
diluted with an organic solvent and subjected to the spinner,
dipping or spray film-formation method to form a film, since they
can be easily peeled by oxygen plasma ashing. Photo resist formed
of such a resin material and containing less impurities such as
sodium ion, etc. is particularly preferable as a material for the
spacer layer 13, and with the spacer layer 13 formed of such a
material, Si substrate with a circuit integrated on it can be used
as a substrate 11.
[0067] The metal plating is deposited and developed not only on the
electrode 12, but on the latent image layer 18. Therefore, the
surface of the latent image layer 18 is kept electrically
conductive. Although the latent image layer 18 is electrically
insulated from the electrode 12 via the spacer layer 13, once the
metal portion deposited through the aperture 15 provided in the
spacer layer 13 comes into contact with the latent image layer 18,
the electrical potential of the latent image layer 18 becomes the
same as that of the electrode 12; thus, a structure layer is formed
on the latent image layer 18 by electroplating. Typically, the
latent image layer 18 is formed on the spacer layer 13 by metal
thin-film forming process, and is patterned into a desirable shape
applying the photo lithography process and etching. For thin-film
formation, already known techniques, for example, resistance
heating depositing, sputter depositing, and electron beam
depositing can be used. The latent image layer 18 may consist of a
plurality of patterns electrically insulated from each other on the
spacer layer 13.
[0068] The structure layer of the present invention is formed by
electroplating, that is, by depositing metal ion in a metal plating
bath on the electrode 12 and the latent image layer 18 on the
spacer layer 13 through electrochemical reaction. The micro
structure of the present invention can be formed not only of the
metal plating bath used, but of metals deposited from various kinds
of metal salts such as a single salt, double salt and complex salt.
The metals used in plating include, for example, Ni, Au, Pt, Cr,
Cu, Ag, Zn as a single metal, and Cu--Zn, Sn--Co, Ni--Fe, Zn--Ni as
an alloy, and the other materials may be also used as long as
electroplating can be performed with them. Dispersed metal plating
in which dispersed particles such as Al.sub.2O.sub.3, TiO.sub.2 and
PTFE are added to a metal plating bath can be also used as a
structure layer.
EXAMPLES
[0069] The method of producing a micro structure of the present
invention will be described in detail in terms of its concrete
embodiments.
Example 1
[0070] Example 1 of the present invention will be described with
reference to FIGS. 1A to 1E.
[0071] As a substrate 11, a silicon wafer was used. On the
substrate 11, a film of Cr was formed to 50 nm thickness by
electron beam deposition and subsequently a film of Au was formed
to 100 nm thickness in the same vacuum, so as to produce an
electrode 12. The substrate 11 having the electrode 12 formed on
its surface was then subjected to spin-application of the whole
aromatic polyamide acid solution, followed by heat treatment, so as
to form a spacer layer 13 comprising a polyimide film (FIG.
1A).
[0072] Then films of Cr and Au were formed on the spacer layer 13
in the same manner that the electrode 12 was formed, and said Cr
and Au films were patterned by the photo lithography process and
etching so as to form a latent image layer 18 (FIG. 1B). Au and Cr
were etched using a mixed aqueous solution of iodine and potassium
iodide and a mixed aqueous solution of diammonium cerium(IV)
nitrate and perchloric acid, respectively.
[0073] A part of the spacer layer 13 was then removed by the photo
lithography process and reactive ion etching with oxygen to provide
an aperture 15 in the neighborhood of the latent image layer 18, so
as to expose a part of the electrode 12 under the spacer layer 13
(FIG. 1C).
[0074] Then Ni plating was performed using the electrode 12 as a
cathode in Ni plating bath consisting of nickel sulfate, nickel
chloride and boric acid at a bath temperature of 50.degree. C. and
a cathode current density of 5 A/dm.sup.2. The deposition and
development of Ni plating first occurred in the aperture 15, and
once said Ni plating reached the latent image layer 18, the latent
image layer 18 began to be plated, and finally a metal plating
layer 17 was formed as shown in FIG. 1D.
[0075] Lastly, the spacer layer 13 was removed by oxygen plasma
etching using ECR, and produced was a cantilever 10a supported by a
support pillar 10b as shown in FIG. 1E.
Example 2
[0076] Example 2 of the present invention will be described with
reference to FIGS. 2A to 2D and 3E to 3G where a nozzle consisting
of a liquid supply opening 20c, a passage 20a and an orifice 20b is
shown as a micro structure.
[0077] As a substrate 21, used was a n-type silicon wafer of which
crystal orientation plane was (1 0 0). On both sides of the
substrate 21, 1 .mu.m thick silicon dioxide (SiO.sub.2) films 26a
and 26b were formed, respectively, through thermal oxidation of the
substrate using oxidizing gas. Then a part of the silicon dioxide
film 26b on the back side of the substrate 21 was removed to expose
the substrate 21 so as to provide a window 29 for etching. On the
other hand, on the silicon dioxide film 26a on the front side of
the substrate 21, a Ti film of 10 nm thickness was formed by
sputtering and subsequently a Pt film of 100 nm thickness was
formed in the same vacuum, so as to form a electrode 22. The
substrate 21 having the electrode 22 formed on it was then
subjected to spin-application of a photoresist for semiconductor,
AZ4620, from Hechst so as to form a first spacer layer 23. Then a
10 nm thick film of Cr was formed on the first spacer layer 23 by
electron beam deposition and subsequently a 100 nm thick film of Au
was formed in the same vacuum, after which said Cr and Au films
were patterned by the photo lithography process and etching, so as
to form a latent image layer 28 on the middle layer of the
substrate 21 (FIG. 2A). Au and Cr were etched using a mixed aqueous
solution of iodine and potassium iodide and a mixed aqueous
solution of diammonium cerium(IV) nitrate and perchloric acid,
respectively.
[0078] Then the first spacer layer 23 was patterned by reactive ion
etching with oxygen using the latent image layer 28 as an etching
mask to expose a part of the electrode 22, so as to provide an
aperture 25 (FIG. 2B).
[0079] Then, using the same process as was used for forming the
first spacer layer 23, the latent image layer 28 was subjected to
spin-application of a photoresist AZ4620, and the photoresist was
exposed to light and developed by the photo lithography process so
as to form a second spacer layer 24 on the latent image layer 28.
The second spacer layer 24 covers a part of the latent image layer
28 (FIG. 2C).
[0080] Then Ni plating was performed using the electrode 22 as a
cathode in Ni plating bath consisting of nickel sulfate, nickel
chloride and boric acid at a bath temperature of 50.degree. C. and
a cathode electric current density of 5 A/dm.sup.2. The deposition
and development of Ni plating first occurred in the aperture 25,
and once said Ni plating reached the latent image layer 28, it
began to deposit and develop on the latent image layer 28
surrounding the second spacer layer 24, and finally a metal plating
layer 27 was formed (FIG. 2D).
[0081] Here, particularly noteworthy is that the plating was
developed in such a manner that it offsets the irregularity
generated by the first and the second spacer layers 23 and 24 on
the substrate 21 and allowed the surface of the metal plating layer
27 to become almost level. The metal plating layer 27 finally
becomes an aperture surface of a nozzle 20b, as described bellow.
Thus, allowing the aperture surface of the nozzle 20b to be level
makes easier its surface treatment such as water repellent
finishing, etc..
[0082] Then, the back side of the substrate 21 was subjected to
crystal axis anisotropic etching with 22% TMAH
(Tetramethylammoniumhydroxide) aqueous solution at 80.degree. C.
through the window 29, and a recessed portion 21a surrounded by the
crystal surfaces of (1 1 1) was formed on the substrate 21 (FIG.
3E). The recessed portion 21a provided on the substrate 21 became a
liquid supply opening 20c of the nozzle in the last step of the
this method.
[0083] Further, the site of the silicon dioxide film 26b and the
electrode 22 exposed through the recessed portion 21a was etched
from the back side of the substrate 21 so as to expose a part of
the first spacer layer 23 (FIG. 3F). The silicon dioxide film 26b
was removed using BHF (buffered hydrofluoric acid) and Ti and Pt
removed by milling using Ar.
[0084] After that, the first and second spacer layers 23, 24 were
etched and removed using acetone, and for the latent image layer
28, Au and Cr were etched and removed using a mixed aqueous
solution of iodine and potassium iodide and a mixed aqueous
solution of diammonium cerium(IV) nitrate and perchloric acid,
respectively. As a result, produced was a nozzle having a liquid
supply opening 20c, a passage 20a and an orifice 20b in which
liquid supplied from the liquid supply opening 20c was jetted from
the orifice 20b through the passage 20a, as shown in FIGS. 3E to
3G. The shape of the passage 20a and that of the orifice 20b are
determined by the pattern of the first spacer layer 23 and that of
the second spacer layer 24, respectively.
Example 3
[0085] In Example 3, a cantilever consisting of a film with two
different thicknesses was produced using the method of producing a
micro structure according to the present invention. Now Example 3
of the present invention will be described with reference to FIGS.
4A to 4E.
[0086] As a substrate 31, a glass substrate was used. On the
substrate 31, a film of Cr was formed to 50 nm thickness by
electron beam deposition and subsequently a film of Au was formed
to 100 nm thickness in the same vacuum, so as to produce an
electrode 32. The substrate 31 having the electrode 32 formed on
its surface was then subjected to spin-application of the whole
aromatic polyamide acid solution, followed by heat treatment, so as
to form a spacer layer 33 comprising a polyimide film. Then films
of Cr and Au were formed on the spacer layer 33 in the same manner
that the electrode 32 was formed, and said Cr and Au films were
patterned by the photo lithography process and etching so as to
form a first and a second latent image layers 38, 39 arranged
longitudinally along the cantilever 30a to be produced (FIG. 4A).
In patterning the first and second latent image layers 38, 39, Au
and Cr were etched using a mixed aqueous solution of iodine and
potassium iodide and a mixed aqueous solution of diammonium
cerium(IV) nitrate and perchloric acid, respectively.
[0087] A part of the spacer layer 33 was then removed by the photo
lithography process and reactive ion etching with oxygen to provide
an aperture 35 in the neighborhood of the first latent image layer
38, so as to expose a part of the electrode 32 under the spacer
layer 33 (FIG. 4B).
[0088] Then Ni plating was performed using the electrode 32 as a
cathode in Ni plating bath consisting of nickel sulfate, nickel
chloride and boric acid at a bath temperature of 50.degree. C. and
a cathode current density of 5 A/dm.sup.2. The Ni plating was first
deposited and developed in the aperture 35, and after the aperture
35 was completely plated, it began to develop on the surface of the
spacer layer 33 spreading laterally. Once said Ni plating reached
the first latent image layer 38, the latent image layer 38 began to
be plated, and finally a metal plating layer 37 was formed (FIG.
4C). Further continuing this plating, the plating layer was
developed in the direction of the thickness of the substrate 31,
while spreading on the surface of the spacer layer 33, and once the
Ni plating reached the second latent image layer 39, the metal
plating layer was formed on the second latent image layer 39 (FIG.
4D).
[0089] Lastly, the spacer layer 33 was removed by oxygen plasma
etching using ECR, and produced was a cantilever 30a which was
supported via a support pillar 30b on the substrate 31 and of which
thickness was reduced halfway to its end.
[0090] While, in Example 3, a cantilever consisting of a film with
two different thicknesses was produced using two latent image
layers, it goes without saying that use of an increased number of
latent image layers makes it possible to produce a micro structure
consisting of a film with an increased number of thickness.
Example 4
[0091] Now Example 4 of the present invention in which a liquid
discharge head was produced as a micro structure will be described
with reference to the attached drawings.
[0092] FIG. 7 is a sectional view of the liquid discharge head
according to one embodiment of the present invention, taken along
the liquid flow path direction to illustrate the basic construction
thereof, and FIG. 8 is a partially cutaway view in perspective of
the liquid discharge head shown in FIG. 7.
[0093] As shown in FIG. 7, this liquid discharge head has an
elemental substrate 1 provided with a plurality of (in FIG. 7, only
one) heating elements 2 in parallel to give a liquid heat energy
for generating bubbles, a top board 3 joined to the elemental
substrate 1, and an orifice plate 4 joined to both of the front end
surfaces of the elemental substrate 1 and the top board 3.
[0094] The elemental substrate 1 is such that a silicon oxide film
or a silicon nitride film for insulation and heat accumulation is
formed on the substrate of silicon, etc., and an electric
resistance layer constituting the heating elements 2 and a wiring
electrode are patterned thereon. The heating elements 2 generate
heat when voltage is applied to the electric resistance layer from
the wiring electrode to allow a current to pass through the
electric resistance layer.
[0095] The top board 3 is provided in order to constitute a
plurality of liquid flow paths 7 corresponding to each heating
element 2 and a common liquid chamber 8 for supplying a liquid to
each liquid flow path 7, and it is integrally provided with a
passage sidewall 9 extending from its ceiling portion to between
the heating elements 2. The top board 3 consists of silicon series
materials, on which patterns of the liquid flow paths 7 and the
common liquid chamber 8 can be formed by etching or, after
depositing materials such as silicon nitride and silicon oxide used
for passage sidewall 9 on the silicon substrate by a known
film-forming process such as CVD, the portion of the liquid flow
paths 7 can be formed by etching.
[0096] On the orifice plate 4, formed are a plurality of discharge
ports 5 (refer to FIG. 8) which are corresponding to each liquid
flow path 7 and in communication with the common liquid chamber 8
therethrough. The orifice plate 4 also consists of a silicon-based
material, and it is formed by, for example, planing the silicon
substrate, on which the discharge ports 5 have been formed, to
about 10 to 150 .mu.m thickness. The orifice plate 4 is not always
necessary for the present invention, and the top board 3 can be
used instead of the orifice plate 4 in such a manner that, when
forming liquid flow paths 7 on the top board 3, a wall whose
thickness corresponds to that of the orifice plate 4 is left on the
end surface of the top board 3, and discharge ports 5 are formed on
the portion to give a top board with discharge ports.
[0097] The liquid discharge head is also provided with a
cantilever-like movable member 6 disposed opposite to the heating
elements 2 so that it will divide the liquid flow path 7 into a
first liquid flow path 7a in communication with the discharge ports
5 and a second liquid flow path 7b having the heating elements 2.
The movable member 6 is a thin film formed of silicon-based
materials such as silicon nitride and silicon oxide, or of nickel
or the like excellent in elasticity.
[0098] This movable member 6 has a supporting point 6a on the
upstream side of a big liquid stream, which flows from the common
liquid chamber 8, above the movable member 6, to the discharge
ports 5, generated by the discharge motion of the liquid, in the
neighborhood of the portion where it is supported by and fixed to
the elemental substrate 1. And the movable member 6 is disposed at
the position facing the heating elements 2 at a given distance
therefrom in such a manner that it has a free end 6b on the
downstream side relative to the supporting point 6a and it covers
the heating elements 2. The space between the heating elements 2
and the movable member 6 becomes a bubble generating area 110.
[0099] When the heating elements 2 is allowed to generate heat, on
the basis of the above construction, the heat generated affects the
liquid in the bubble generating area 110 between the movable member
6 and the heating elements 2, which leads to a film boiling
phenomenon and consequently causes bubbles to generate and grow on
the heating elements 2. A pressure accompanying the growth of the
bubbles acts over the movable member 6 in preference to the others,
and the free end 6b of the movable member 6 undergoes displacement
in such a manner that it widely opens toward the discharge port 5
around the supporting point 6a as shown with the dashed line in
FIGS. 1A to 1E. The displacement of the movable member 6 or the
state in which the movable member 6 has undergone displacement
directs the propagation of the pressure caused by bubble generation
and the growth of bubbles themselves toward the discharge port 5,
and consequently the liquid is discharged from the discharge port
5.
[0100] In other words, providing a movable member 6, having a
supporting point 6a on the upstream side (the common liquid chamber
8 side) of the liquid flow in the liquid flow path 7 and a free end
6b on the downstream side (the discharge port side), in the bubble
generating area 110 allows to direct the propagation of bubble
pressure toward the downstream side, which in turn makes the bubble
pressure to contribute directly and efficiently to the discharge of
liquid. And like the propagation of bubble pressure, the growth of
bubbles itself is also directed toward the downstream side, that
is, bubbles grow more highly in the downstream than in the
upstream. Thus, controlling the growth of bubbles itself as well as
the propagation direction of bubble pressure by the movable member
6 makes possible improvement in the fundamental discharge
properties such as discharge efficiency, discharge force, or
discharge speed etc.
[0101] The terms "upstream" and "downstream" used herein refer to
the direction in terms of a liquid flow from a liquid supply, above
the bubble generating area 110 (or the movable member 6), toward
the discharge port 5, and the direction in connection with the
construction of the structure.
[0102] On the other hand, in the step of stopping the bubble
formation, bubbles rapidly disappear due to the synergistic effect
of the elasticity of the movable member 6, and finally the movable
member 6 is reset at its initial position as shown with the solid
line in FIG. 7. At this time, the liquid flow path 7 is refilled
with the liquid flowing from the upstream side, that is, the common
liquid chamber 8, so that the liquid will compensate shrinkage of
the volume of bubbles in the bubble generating area 110, as well as
reduction of the volume of liquid due to the above liquid
discharge, and this refill is performed efficiently, rationally and
stably with the reset action of the movable member 6.
[0103] Now the elemental substrate 1 of the liquid discharge head
shown in FIG. 7 will be described. FIG. 9 is a partially cutaway
view in section showing the elemental substrate, in the
neighborhood of a heating element, of the liquid discharge head
shown in FIG. 7.
[0104] In FIG. 9, the reference numerals 111 and 112 indicate a
silicon substrate and a thermally oxidized film which is a heat
accumulating layer, respectively. The reference numeral 113
indicates a SiO.sub.2 or Si.sub.3N.sub.4 film which is an
interlayer film also serving as a heat accumulating layer, the
reference numeral 114 a resistance layer, the reference numeral 115
an Al alloy wiring of, for example, Al, Al--Si, Al--Cu, etc., and
the reference numeral 116 a SiO.sub.2 or Si.sub.3N.sub.4 film which
is a protective film. The reference numeral 117 indicates a
cavitation resistant film for protecting the protective film 116
from physical and chemical impacts caused by heat generation of the
resistance layer 114. Lastly, the reference numeral 118 indicates a
heat applying portion of the resistance layer 114 in the zone where
the wiring 115 is not formed.
[0105] These driving elements are formed on the Si substrate using
semiconductor technologies, and the heat applying portion is also
formed on the same substrate.
[0106] FIG. 10 is a vertically cutaway schematic view in section
showing each of the main elements of the elemental substrate.
[0107] A Si substrate 121 which is a P-conductor consists of P-MOS
123 and N-MOS 125 constructed in a N-type well area 122 and in a
P-type well area 124, respectively, by a process of introducing and
diffusing impurities, such as ion implantation method which is a
common MOS process. Each of P-MOS 123 and N-MOS 125 consists of a
gate wiring 127 of poly-Si deposited to a thickness within the
range of 4000 .ANG. to 5000 .ANG. by CVD method via a gate
insulation film 126 with thickness several hundreds .ANG., a source
area 128 into which p-type impurities are introduced, and a drain
area 129. And C-MOS logic consists of the P-MOS 123 and N-MOS
125.
[0108] And a N-MOS transistor for driving elements consists of a
drain area 130, a source area 131, and a gate wiring 132 which are
constructed in a p-well substrate also by a process of, for
example, introducing and diffusing impurities.
[0109] While this embodiment is described in terms of a
construction using a N-MOS transistor, the transistor to be used is
not limited to this, as long as it is capable of driving a
plurality of heating elements separately and has a function of
achieving a micro structure as described above.
[0110] Each element is separated from each other by an oxide
separation area 133 formed to a thickness within the range of 5000
.ANG. to 10000 .ANG. by a process of field oxidation. The field
oxidation film serves as a first heat accumulating layer 134 below
the heat applying portion 118.
[0111] After forming each element, a layer-to-layer insulation film
135 is formed by depositing a PSG (Phospho-Silicate Glass) film,
BPSG (Boron-doped Phospho-Silicate Glass) film or the like to a
thickness of about 7000 .ANG. by CVD method, then flattened by heat
treatment, after which wiring is performed via a contact hole at an
Al electrode 136 which is to be a first wiring layer. Then, a
layer-to-layer insulation film 137 is formed by depositing a
SiO.sub.2 film or the like to a thickness within the range of 10000
.ANG. to 15000 .ANG. by plasma CVD method, and a TaN.sub.0.8, hex
film of about 1000 .ANG. thickness, as a resistance layer 114, is
formed by DC sputter method via a through hole. Then, formed is an
Al electrode which is to be a second wiring layer for each heating
element.
[0112] A protective film 116 is formed by depositing a
Si.sub.3N.sub.4 film to a thickness of about 10000 .ANG. by plasma
CVD. And the top layer is an electrically conductive layer
consisting of an electrically conductive material, that is, a
cavitation resistant film 117 which functions as a cathode in metal
plating, as described below, is formed by depositing, for example,
Ta to a thickness of about 2800 .ANG..
[0113] Now, a method of producing a movable member which is a
feature of the liquid discharge head of this embodiment will be
described in more detail with reference to FIGS. 11A to 11E. FIGS.
11A to 11E illustrate sectional views of a movable member of the
liquid discharge head shown in FIG. 7, which are in different steps
of the production process.
[0114] First, the cavitation resistant film 117 of the elemental
substrate 1 was subjected to spin-application of the whole aromatic
polyamide solution, followed by heat treatment, so as to form a
spacer layer 41 comprising a polyimide thin-film, as shown in FIG.
11A. For the spacer layer 41, used were materials which do not
corrode in a metal plating bath and are highly insulating. As a
material, organic high polymer resins, oxide materials such as
SiO.sub.2, TiO.sub.2, Al.sub.2O.sub.3 and MgO, nitride materials
such as Si.sub.3N.sub.4 and TiN, carbide materials such as SiC, TiC
and C can be utilized.
[0115] Then, a film of Cr was formed to 50 nm thickness in vacuum
by electron beam deposition and subsequently a film of Au was
formed to 100 nm thickness in the same vacuum, after that the film
was patterned by the photo lithography process and etching, so as
to form a latent image layer 42 consisting of an electrically
conductive material on the spacer layer 41 (Refer to FIG. 11B). The
Au and Cr were etched using a mixed aqueous solution of iodine and
potassium iodide and a mixed aqueous solution of diammonium
cerium(IV) nitrate and perchloric acid, respectively. As a result,
the latent image layer 42 was patterned into almost the same shape
as the movable member 6.
[0116] Then, a part of the spacer layer 41 corresponding to the
portion supporting and fixing the movable member 6 was removed by
the photo lithography process and reactive ion etching by oxygen to
provide an aperture 43 in the neighborhood of the latent image
layer 42, so as to expose a part of the cavitation resistant film
117 under the spacer layer 41, as shown in FIG. 11C. This aperture
43 was formed on the upstream side of the liquid flow path 7 (Refer
to FIG. 7), in terms of its liquid flow, in the liquid discharge
head. When forming an etching mask on the spacer layer 41 in the
photo lithography process, it was formed in such a manner that at
least the portion of the spacer layer 41 above the aperture 43
corresponding to the portion supported by and fixed to the movable
member 6 is left. And the portion of the spacer layer 41 which is
to become the aperture 43 is removed by etching afterward. At this
time, the latent image layer 42 functions as a part of an etching
mask, which allows to perform registering between the latent image
layer 42 and the aperture 43 with high accuracy.
[0117] Then Ni electroplating was performed using the cavitation
resistant film 117 as a cathode in Ni plating bath consisting of
nickel sulfate, nickel chloride and boric acid at a bath
temperature of 50.degree. C. and a cathode current density of 5
A/cm.sup.2, so as to deposit and develop the metal plating in the
aperture 43 on the cavitation resistant film 117. The metal plating
deposited on the cavitation resistant film 117 was further
developed to eventually come into contact with the latent image
layer 42, and once the cavitation resistant film 117 and the latent
image layer 42 became electrically connected, the metal plating was
deposited on the latent image layer 42 as well, and a metal plating
layer 44 was formed (Refer to FIG. 11D).
[0118] Lastly, the spacer layer 41 was removed by oxygen plasma
etching using ECR, and produced on the substrate 1 was a movable
member 6 composed of the metal plating layer 44 (Refer to FIG.
11E).
[0119] As a material constituting the spacer layer 41, selected are
the materials such that the ratio of their etching selection to the
etching selection of the materials constituting the metal plating
layer 44 (the movable member 6) will be sufficiently high. As a
material constituting the spacer layer 41, preferable is organic
high polymer resins such that they can be diluted with an organic
solvent and subjected to the spinner, dipping or spray
film-formation method so as to form a film, since they can be
easily peeled by oxygen plasma ashing. Photo resist made of such a
resin material and containing less impurities such as sodium ion,
etc. is particularly preferable as a material for the spacer layer
41, and with the spacer layer 41 formed of such a material, the
circuit formed on the elemental substrate 1 can be less
affected.
[0120] The metal plating is developed not only on the cavitation
resistant film 117 which is an electrically conductive layer, but
on the latent image layer 42. Therefore, the surface of the latent
image layer 42 is kept electrically conductive. Although the latent
image layer 42 is electrically insulated from the electrically
conductive layer (the cavitation resistant film 117) via the spacer
layer 41, once the metal plating deposited in the aperture 43
provided on the spacer layer 41 comes into contact with the latent
image layer 42, the electrical potential of the latent image layer
42 becomes the same as that of the cavitation resistant film 117;
thus, a metal plating layer 44 is also formed on the latent image
layer 42 by electroplating.
[0121] Typically, the latent image layer 42 is formed on the spacer
layer 41 by metal thin-film formation method, and is patterned into
a desirable shape (the shape of the movable member 6) by applying
the photo lithography process and etching. For thin-film formation,
already known techniques, for example, resistance heating
deposition, spatter deposition, and electron beam deposition can be
used. The latent image layer 42 may consist of a plurality of
patterns electrically insulated from each other on the spacer layer
41.
[0122] The movable member 6 of the present invention is formed by
electroplating, that is, by depositing metal ion in a metal plating
bath on the electrically conductive layer (the cavitation resistant
film 117) and the latent image layer 42 on the spacer layer 41
through electrochemical reaction. The movable member 6 of the
present invention can be formed not only using metal plating bath,
but also of metals deposited from various kinds of metal salts such
as a single salt, double salt and complex salt. The main metals
used in plating include, for example, Ni, Au, Pt, Cr, Cu, Ag, Zn as
a single metal, and Cu--Zn, Sn--Co, Ni--Fe, Ni--Cr, Ni--Co, Zn--Ni
as an alloy, and the other materials may be also used as long as
electroplating can be performed with them. Dispersed metal plating
in which dispersed particles such as Al.sub.2O.sub.3, TiO.sub.2 and
PTFE are added to a metal plating bath can be also used for the
movable member 6 of the present invention.
[0123] As described above, according to the present invention, the
movable member 6 is formed by, first, forming on the spacer layer
41 the latent image layer 42 consisting of an electrically
conductive material patterned into almost the same shape of the
movable member 6 and then metal plating the latent image layer 42;
and therefore, the dimensions of the movable member 6 is determined
by the dimensions of the latent image layer 42, which makes it
possible to decrease the variations in the mechanical properties of
the movable member 6 caused by the variations in the dimensions
thereof. Thus the movable member 6 can be produced with a high
accuracy and high density, and consequently, a liquid discharge
head can be produced which is stable in its discharge properties in
discharging liquid and is highly reliable.
Example 5
[0124] FIGS. 12A to 12E show sectional views of a movable member in
the liquid discharge head shown in FIG. 7 to illustrate the Example
2 of the method of the present invention for producing thereof.
[0125] First, the cavitation resistant film 117 of the elemental
substrate 1 was subjected to spin-application of the whole aromatic
polyamide acid solution, followed by heat treatment, so as to form
a spacer layer 51 consisting of a polyimide thin-film, as shown in
FIG. 12A. For the spacer layer 51, used were materials which do not
corrode in a metal plating bath and are highly insulating. As a
material, organic high polymer resins, oxide materials such as
SiO.sub.2, TiO.sub.2, Al.sub.2O.sub.3 and MgO, nitride materials
such as Si.sub.3N.sub.4 and TiN, carbide materials such as SiC, TiC
and C can be utilized.
[0126] Then, a film of Cr was formed to 50 nm thickness in vacuum
by electron beam deposition and subsequently a film of Au was
formed to 100 nm thickness in the same vacuum, after that the film
was patterned by the photo lithography process and etching, so as
to form a first latent image layer 52a and a second latent image
layer 52b consisting of an electrically conductive material on the
spacer layer 51 (Refer to FIG. 12B). The Au and Cr were etched
using a mixed aqueous solution of iodine and potassium iodide and a
mixed aqueous solution of diammonium cerium(IV) nitrate and
perchloric acid, respectively. As a result, the latent image layers
52a and 52b were patterned into almost the same shape as the
movable member 6.
[0127] Then, a part of the spacer layer 51 corresponding to the
portion supporting and fixing the movable member 55 was removed by
the photo lithography process and reactive ion etching by oxygen to
provide an aperture 53 in the neighborhood of the first latent
image layer 52a, so as to expose a part of the cavitation resistant
film 117 under the spacer layer 51, as shown in FIG. 12C. This
aperture 53 was formed on the upstream side of the liquid flow path
7 (Refer to FIG. 7), in terms of its liquid flow, in the liquid
discharge head.
[0128] Then Ni electroplating was performed using the cavitation
resistant film 117 as a cathode in Ni plating bath consisting of
nickel sulfate, nickel chloride and boric acid at a bath
temperature of 50.degree. C. and a cathode current density of 5
A/cm.sup.2. The Ni plating was first deposited in the aperture 53,
and after the aperture 53 was completely plated, it was developed
spreading isotropically on and above the spacer layer 51. Once the
Ni plating reached the first latent image layer 52a, a metal
plating layer 54 was formed thereon. After continuing the plating,
the plating began to spread on the spacer layer 51, and once the Ni
plating reached the second latent image layer 52b, the metal
plating layer 54 was also formed thereon (Refer to FIG. 12D). For
the metal plating layer 54 formed as described above, it has two
different levels of thickness, one on the first latent image layer
52a and the other on the second latent image layer 53b.
[0129] Lastly, the spacer layer 51 was removed by oxygen plasma
etching using ECR, and produced on the elemental substrate 1 was a
movable member 55 consisting of the metal plating layer 54 (Refer
to FIG. 12E).
[0130] As described above, according to this embodiment of the
method for producing a micro structure, formed was a movable member
55 having two different levels of thickness and different levels of
modulus elasticity along the liquid flow direction of the liquid
flow path. The movable member 55 was formed in such a manner that
the level of its thickness was lower near its free end than near
its supporting point and it could be inflected more near its free
end than near its supporting point. As a result, as shown in FIG.
13, when bubbles 56 are generated in the bubble generating area
above the heating element 2, with the growth of the bubbles 56, the
movable portion near the free end of the movable member 55 is
displaced more largely, which improves the efficiency in
discharging liquid.
[0131] Further, in order to improve the liquid discharging
efficiency, a movable member may be constructed such that it has
three or more different levels of thickness. The levels of the
thickness can be increased only by increasing the number of the
latent image layers formed on the spacer layer; therefore, even
when a movable member is constructed such that it has three or more
different levels of thickness, the number of the process steps of
producing a movable member is not increased.
Example 6
[0132] FIGS. 14A to 14E illustrate sectional views of a movable
member in the liquid discharge head shown in FIG. 7 to illustrate
the third embodiment of the method of the present invention for
producing thereof.
[0133] First, the cavitation resistant film 117 of the elemental
substrate 1 was subjected to spin-application of the whole aromatic
polyamide acid solution, followed by heat treatment, so as to form
a spacer layer 61 consisting of a polyimide thin-film, as shown in
FIG. 14A. For the spacer layer 61, used were materials described in
the examples 4 and 5.
[0134] Then, a part of the spacer layer 61 corresponding to the
portion supporting and fixing the movable member 65 was removed by
the photo lithography process and reactive ion etching by oxygen to
provide an aperture 63, so as to expose a part of the cavitation
resistant film 117 under the spacer layer 61, as shown in FIG. 14B.
This aperture 63 was formed on the upstream side of the liquid flow
path 7 (Refer to FIG. 7), in terms of its liquid flow, in the
liquid discharge head.
[0135] Then, a film of Cr was formed to 50 nm thickness in vacuum
by electron beam deposition and subsequently a film of Au was
formed to 100 nm thickness in the same vacuum, after that the film
was patterned by the photo lithography process and etching, so as
to form a latent image layer 62 consisting of an electrically
conductive material on the cavitation resistant film 117 and the
spacer layer 61 (Refer to FIG. 14C). As a result, the latent image
layer 62 was patterned into almost the same shape as the movable
member 6.
[0136] Then Ni electroplating was performed using the cavitation
resistant film 117 as a cathode in Ni plating bath consisting of
nickel sulfate, nickel chloride and boric acid at a bath
temperature of 50.degree. C. and a cathode current density of 5
A/cm.sup.2. The metal plating was deposited on the latent image
layer 62. Thus a metal plating layer 64 was formed on the latent
image layer 62 (Refer to FIG. 14D).
[0137] Lastly, the spacer layer 61 was removed by oxygen plasma
etching using ECR, and produced on the elemental substrate 1 was a
movable member 65 consisting of the metal plating layer 64 (Refer
to FIG. 14E).
[0138] Now, a liquid discharge head cartridge loaded with the
foregoing liquid discharge head will be described roughly with
reference to FIG. 15. FIG. 15 is a perspective view of a liquid
discharge head cartridge loaded with the foregoing liquid discharge
head of the present invention.
[0139] The liquid discharge head cartridge 71 of the present
embodiment has a liquid discharge head 72 described above and a
liquid container 73 containing a liquid, such as an ink, supplied
to the liquid discharge head 72. The liquid contained in the liquid
container 73 is supplied to a common liquid chamber 8 (Refer to
FIG. 7) of the liquid discharge head 72 via a liquid supply passage
which is not shown in Figures.
[0140] The liquid container 73 may be refilled after consuming the
liquid contained in it so as to be reused. For this purpose, it is
desirable that the liquid container 73 is provided with a liquid
injection opening. The liquid discharge head 72 and the liquid
container 73 may be constructed integrally or removably.
[0141] Then, a liquid discharge device loaded with a liquid
discharge head as described above will be described with reference
to FIG. 16. FIG. 16 is a perspective view showing a schematic
construction of a liquid discharge device loaded with a liquid
discharge head as described above.
[0142] The liquid discharge device 81 of the present embodiment has
a liquid discharge head cartridge 71, as described with reference
to FIG. 15, which is loaded on a carriage 87 engaged with a spiral
groove 86 of a lead screw 85 which rotates in connection with the
normal/reverse rotation of a driving motor 82 via drive transfer
gears 83, 84. The liquid discharge head cartridge 71 is moved back
and force in the direction of arrows a and b along a guide 88 with
the carriage 87 by power of the driving motor 82. A paper bracing
plate 90 bracing a recording medium P conveyed on a platen 89 by a
recording medium supply device, which is not shown in the figure,
presses the recording medium P against the platen 89 over the
entire moving area.
[0143] Photo couplers 91 and 92 are placed in the neighborhood of
the lead screw 85. These are means of detecting a home position for
confirming the presence of a lever 87a of the carriage 87 to switch
the rotational direction of the driving motor 82. In FIG. 16, the
reference numeral 93 indicates a support member for supporting a
cap member 94 covering the front surface, which is provided with
discharge ports, of the liquid discharge head of the liquid
discharge head cartridge 71. And the reference numeral 95 indicates
a means of suctioning the ink accumulated within the cap member 94
discharged from the liquid discharge head.
[0144] The reference numeral 96 indicates a cleaning blade, and the
reference numeral 97 indicates a movable member allowing the
cleaning blade 96 to move back and forth (vertical to the direction
that the above carriage 87 moves). The cleaning blade 96 and the
movable member 97 are supported by a body support 98. The form of
the cleaning blade 96 is not limited to that described above, but
the other known cleaning blades may be also used. The reference
numeral 99 indicates a lever for starting suctioning in
suction-recovery operation which moves with the movement of a cam
100 engaged with the carriage 87 and controls the movement of the
power from the driving motor 82 with a known means such as clutch
switching. In the body of the liquid discharge device 81, a
recording control portion (not shown in the figure) as a recording
signal supply means is provided which gives the heating elements 2
provided in the liquid discharge head (Refer to FIG. 7) a driving
signal for discharging liquid and controls the drive of each of the
mechanisms described above.
[0145] In the liquid discharge device 81, the liquid discharge head
discharges liquid against the recording medium P conveyed on the
platen 89 by a recording medium conveying device, which is not
shown in the figure, while it moves back and forth the entire width
of the recording medium P, and recording is achieved by sticking
the liquid discharged on the recording medium P.
* * * * *