U.S. patent application number 11/826705 was filed with the patent office on 2008-02-14 for manufacturing method of actuator device and liquid jet apparatus provided wirth actuator device formed by manufacturing method of the same.
This patent application is currently assigned to Seiko Epson Corporation. Invention is credited to Maki Ito, Hironobu Kazama, Masami Murai, Koji Sumi, Li Xin-Shan, Toshiaki Yokouchi.
Application Number | 20080034563 11/826705 |
Document ID | / |
Family ID | 34797415 |
Filed Date | 2008-02-14 |
United States Patent
Application |
20080034563 |
Kind Code |
A1 |
Xin-Shan; Li ; et
al. |
February 14, 2008 |
Manufacturing method of actuator device and liquid jet apparatus
provided wirth actuator device formed by manufacturing method of
the same
Abstract
A manufacturing method of a liquid jet head having increased the
durability and reliability thereof by preventing delamination of a
vibration plate is provided. At least the following two steps are
included: a vibration plate forming step which includes at least a
step of forming a zirconium layer on one side of a passage-forming
substrate by sputtering so that a degrees of orientation to a (002)
plane of the surface becomes equal to 80% or more, as well as
forming an insulation film made of zirconium oxide and constituting
a part of the vibration plate by subjecting the zirconium layer to
thermal oxidation; and a piezoelectric element forming step of
forming piezoelectric elements on the vibration plate.
Inventors: |
Xin-Shan; Li; (Nagano-ken,
JP) ; Kazama; Hironobu; (Nagano-ken, JP) ;
Murai; Masami; (Nagano-ken, JP) ; Sumi; Koji;
(Nagano-ken, JP) ; Ito; Maki; (Nagano-ken, JP)
; Yokouchi; Toshiaki; (Nagano-ken, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
Seiko Epson Corporation
Nagano-ken
JP
|
Family ID: |
34797415 |
Appl. No.: |
11/826705 |
Filed: |
July 18, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10995945 |
Nov 24, 2004 |
|
|
|
11826705 |
Jul 18, 2007 |
|
|
|
Current U.S.
Class: |
29/25.35 ;
29/890.1; 347/40 |
Current CPC
Class: |
B41J 2/1635 20130101;
B41J 2002/14241 20130101; Y10T 29/42 20150115; Y10T 29/49401
20150115; H01L 41/1876 20130101; H01L 41/0973 20130101; B41J 2/1629
20130101; H01L 41/319 20130101; B41J 2/161 20130101; B41J 2/1646
20130101; B41J 2/1632 20130101; B41J 2/1623 20130101; H01L 41/314
20130101 |
Class at
Publication: |
029/025.35 ;
029/890.1; 347/040 |
International
Class: |
H01L 41/22 20060101
H01L041/22; B44C 1/22 20060101 B44C001/22 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2003 |
JP |
2003-399846 |
Aug 12, 2003 |
JP |
2003-409629 |
Claims
1. A manufacturing method of an actuator device including a
vibration plate, and piezoelectric elements formed of a lower
electrode, a piezoelectric layer, and an upper electrode, which are
formed on the vibration plate, the manufacturing method comprising
at least: a vibration plate forming step of forming a vibration
plate, which includes at least a step of forming a zirconium layer
on one side of a substrate by sputtering so that a degrees of
orientation to a (002) plane of a surface becomes equal to 80% or
more as well as forming an insulation film made of zirconium oxide
and constituting a part of the vibration plate by subjecting the
zirconium layer to thermal oxidation; and a piezoelectric element
forming step of forming piezoelectric elements on the vibration
plate.
2. The manufacturing method of an actuator device according to
claim 1, wherein the vibration plate forming step further comprises
a step of forming an elastic film made of silicon dioxide
(SiO.sub.2) and constituting a part of the vibration plate on one
side of the substrate made of a single crystal silicon substrate,
and wherein the insulation film is formed on the elastic film.
3. The manufacturing method of an actuator device according to
claim 1, wherein the piezoelectric element forming step comprises
at least a step of forming a piezoelectric layer made of lead
zirconate titanate (PZT).
4. The manufacturing method of an actuator device according to
claim 1, wherein the zirconium layer is formed by use of a DC
sputtering method in a step of forming the insulation film.
5. The manufacturing method of an actuator device according to
claim 4, wherein sputtering output in forming the zirconium layer
is set to 500 W or below.
6. The manufacturing method of an actuator device according to
claim 4, wherein a heating temperature in forming the zirconium
layer is set to 100 degrees C. or more.
7. The manufacturing method of an actuator device according to
claim 4, wherein sputtering pressure in forming the zirconium layer
is set to 0.5 Pa or below.
8. The manufacturing of an actuator device according to claim 1,
wherein a temperature of thermal oxidation is set to 850 to
1000.degree. C., and a load speed is set to 300 mm/min or more.
9. A liquid jet apparatus comprising: the liquid jet head having
the actuator device formed by the manufacturing method according to
claim 1.
Description
[0001] This is a divisional of application Ser. No. 10/995,945
filed Nov. 24, 2004. The entire disclosure of the prior
application, application Ser. No. 10/995,945 is considered part of
the disclosure of the accompanying divisional application and is
hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a manufacturing method of
an actuator device, in which a vibration plate is provided on a
surface of a passage-forming substrate including pressure
generating chambers and in which piezoelectric elements are formed
on the vibration plate, and relates to a liquid jet apparatus, in
which droplets such as ink are ejected by displacement of the
actuator device formed by the manufacturing method.
[0004] 2. Description of the Related Art
[0005] An actuator device including piezoelectric elements which
undergo displacement by being applied with voltage is applied to,
for example, a liquid jet head ejecting droplets and the like. As
the liquid jet head as described above, an inkjet recording head is
known, for example. In the inkjet recording head, a part of
pressure generating chambers communicating with nozzle orifices is
formed by a vibration plate, and this vibration plate is deformed
by piezoelectric elements to eject ink droplets from the nozzle
orifices by pressurizing ink in the pressure generating chambers.
There are two types of inkjet recording heads which have been put
to practical use, which include: one applying a piezoelectric
actuator device of a longitudinal vibration mode configured to
expand and contract in an axial direction of the piezoelectric
element; and one applying a piezoelectric actuator device of a
flexural vibration mode.
[0006] In the former, volume of the generating chambers can be
varied by making an end face of the piezoelectric elements abut on
the vibration plate, and a head suitable for high-density printing
can be manufactured. However, there arise the following problems: A
troublesome process of making the piezoelectric elements correspond
with an arrangement pitch of the nozzle orifices and cutting them
into comb-like shapes becomes necessary; an operation of specifying
and fixing the piezoelectric elements cut as described above for
the pressure generating chambers also becomes necessary; and
accordingly, the manufacturing process is complicated. Meanwhile,
in the latter, the piezoelectric elements can be formed on the
vibration plate by a relatively simple process, in which a green
sheet as a piezoelectric material is attached in conformity to the
shape of the pressure generating chambers and baked. However, there
arises a problem that a high-density arrangement of the
piezoelectric elements is difficult to perform since a certain area
becomes necessary in applying the flexural vibration mode.
Moreover, in order to eliminate the disadvantage of the latter,
there is a type of head in which a uniform piezoelectric material
layer is formed over an entire surface of a vibration plate by use
of a deposition technique, this piezoelectric material layer is cut
into shapes corresponding to the pressure generating chambers by
use of a lithography method, and piezoelectric elements are formed
so as to be independent for each of the pressure generating
chambers.
[0007] As a material of the piezoelectric material layer
constituting piezoelectric elements as described above, for
example, lead zirconate titanate (PZT) is used. In this case, when
the piezoelectric material layer is baked, lead components of the
piezoelectric material layer diffuse in a silicon dioxide
(SiO.sub.2) film which is formed on a surface of the
passage-forming substrate made of silicon (Si) and constitutes the
vibration plate. Thus, there arises a problem that a melting point
of silicon dioxide decreases due to the diffusion of the lead
components and thereby the silicon dioxide film melts due to the
heat generated in baking the piezoelectric material layer. In order
to solve the problems as described above, for example, there is one
in which the zirconium oxide film constituting the vibration plate
is formed on the silicon dioxide film and the piezoelectric
material layer is formed on this zirconium oxide film to prevent
the lead components from diffusing from the piezoelectric material
layer to the silicon dioxide film (for example, see Japanese
Unexamined Patent Publication No. 11 (1999)-204849).
[0008] However, the zirconium oxide film has low adhesion
properties with silicon dioxide film and therefore there arises a
problem that delamination of the vibration plate or the like
occurs. Namely, the zirconium oxide film is formed by forming a
zirconium film by sputtering and thereafter subjecting the
zirconium film to thermal oxidation. The zirconium film formed as
described above takes the form of polycrystalline structure, but
the crystals are likely to be formed into ball-shaped ones.
Accordingly, even if there are column-shaped crystals, the rate of
existence thereof is low, and therefore there arises a problem that
the zirconium oxide film has low adhesion properties with silicon
dioxide film and the delamination of the zirconium oxide film or
the like occurs. Note that such problems as described above
similarly arise not only in the actuator device applied to the
liquid jet head such as the inkjet recording head but also in
actuator devices applied to other apparatus.
SUMMARY OF THE INVENTION
[0009] In consideration of the circumstances as described above, an
object of the present invention is to provide a manufacturing
method of an actuator device having increased the durability and
reliability thereof by preventing delamination of the vibration
plate and a liquid jet apparatus provided with an actuator device
formed by the manufacturing method.
[0010] To attain the object, a first aspect of the present
invention provides a manufacturing method of an actuator device
including a vibration plate provided on one side of a
passage-forming substrate in which pressure generating chambers are
arranged, and piezoelectric elements formed of a lower electrode, a
piezoelectric layer, and an upper electrode, which are formed on
the vibration plate. The manufacturing method includes at least: a
vibration plate forming step which includes at least a step of
forming a zirconium layer on one side of the passage-forming
substrate by sputtering so that a degrees of orientation to a (002)
plane of a surface becomes equal to 80% or more as well as forming
an insulation film made of zirconium oxide and constituting a part
of the vibration plate by subjecting the zirconium layer to thermal
oxidation; and piezoelectric element forming step of forming
piezoelectric elements on the vibration plate.
[0011] In the first aspect, a zirconium layer having excellent
crystallinity can be formed, and an insulation film having
excellent adhesion properties with a film under the insulation film
can be formed by subjecting the zirconium layer formed as described
above to thermal oxidation.
[0012] A second aspect of the present invention provides a
manufacturing method of an actuator device according to the first
aspect, in which the vibration plate forming step further includes
a step of forming an elastic film made of silicon dioxide
(SiO.sub.2) and constituting a part of the vibration plate on one
side of the passage-forming substrate made of a single crystal
silicon substrate, and in which the insulation film is formed on
the elastic film.
[0013] In the second aspect, even if a film under the insulation
film is the elastic film made of silicon dioxide, the adhesion
properties therebetween are increased.
[0014] A third aspect of the present invention provides a
manufacturing method of an actuator device according to any one of
the first and second aspects, in which the piezoelectric element
forming step includes at least a step of forming a piezoelectric
layer made of lead zirconate titanate (PZT).
[0015] In the third aspect, diffusion of lead components of the
piezoelectric layer in a vibration plate can be prevented, and the
vibration plate and the piezoelectric elements can be formed
favorably.
[0016] A fourth aspect of the present invention provides a
manufacturing method of an actuator device according to any one of
the first to third aspects, in which the zirconium layer is formed
by use of a DC sputtering method in the step of forming the
insulation film.
[0017] In the fourth aspect, a zirconium layer having a degrees of
orientation to a (002) plane of the surface equal to 80% or more
can be formed relatively easily.
[0018] A fifth aspect of the present invention provides a
manufacturing method of an actuator device according to the fourth
aspect, in which sputtering output in forming the zirconium layer
is set to 500 W or below.
[0019] In the fifth aspect, a zirconium layer having excellent
crystallinity can be formed by controlling the sputtering
output.
[0020] A sixth aspect of the present invention provides a
manufacturing method of an actuator device according to any one of
the fourth and fifth aspects, in which a heating temperature in
forming the zirconium layer is set to 100 degrees C. or more.
[0021] In the sixth aspect, a zirconium layer having excellent
crystallinity can be formed by controlling the heating temperature
in sputtering.
[0022] A seventh aspect of the present invention provides a
manufacturing method of an actuator device according to any one of
the fourth to sixth aspects, in which sputtering pressure in
forming the zirconium layer is set to 0.5 Pa or below.
[0023] In the seventh aspect, a zirconium layer having excellent
crystallinity can be formed by controlling the sputtering
pressure.
[0024] An eighth aspect of the present invention provides the
manufacturing of an actuator device according to any one of the
first to seventh aspects, in which a temperature of thermal
oxidation is set to 850 to 1000.degree. C., and a load speed is set
to 300 mm/min or more.
[0025] In the eighth aspect, the insulation film which is subjected
to priority orientation to the (-111) plane and in which
crystalline state is favorable, can be obtained.
[0026] A ninth aspect of the present invention provides an actuator
device including a vibration plate, and piezoelectric elements
formed of a lower electrode, a piezoelectric layer, and an upper
electrode which are formed on the vibration plate, in which the
vibration plate includes at least an insulation film made of
zirconium oxide (ZrO.sub.2), and crystals of the insulation film
are subjected to priority orientation to a (-111) plane.
[0027] In the ninth aspect, quality of the insulation film is
increased, and delamination of the vibration plate is prevented.
Moreover, quality of the respective layers such as the
piezoelectric layer and the like which are formed on this
insulation film is stabilized by the increase in the quality of the
insulation film.
[0028] A tenth aspect of the present invention provides an actuator
device according to the ninth aspect, in which crystals of the
insulation film are column-shaped.
[0029] In the tenth aspect, the crystals of the insulation film are
formed into column-shaped ones continuously from an undersurface to
a top surface, and thereby adhesion properties between the
undersurface and the top surface are increased.
[0030] An eleventh aspect of the present invention provides an
actuator device according to any one of the ninth and tenth
aspects, in which the crystals of the insulation film are
monoclinic.
[0031] In the eleventh aspect, the crystals of the insulation film
are orientated to a (-111) plane favorably.
[0032] A twelfth aspect of the present invention provides an
actuator device according to any one of the ninth to eleventh
aspects, in which film thickness of the insulation film is 200 nm
or more, and grain size is 20 to 100 nm.
[0033] In the twelfth aspect, adhesion properties between the
insulation film and layers sandwiching the insulation film are
surely increased.
[0034] A thirteenth aspect of the present invention provides an
actuator device according to any one of the ninth to twelfth
aspects, in which a stress of the insulation film is in a range of
-150 to -300 [MPa].
[0035] In the thirteenth aspect, delamination of the insulation
film can be surely prevented. Moreover, displacement of a vibration
plate due to drive of piezoelectric elements can be prevented from
decreasing.
[0036] A fourteenth aspect of the present invention provides an
actuator device according to any one of the ninth to thirteenth
aspects, in which the vibration plate includes an elastic film made
of silicon dioxide (SiO.sub.2), and the insulation film is formed
on the elastic film.
[0037] In the fourteenth aspect, even if a film under the
insulation film is the elastic film made of silicon dioxide, the
adhesion properties therebetween are increased.
[0038] A fifteenth aspect of the present invention provides a
liquid jet apparatus, in which the liquid jet head having the
actuator device formed by the manufacturing method according to the
first aspect is provided.
[0039] In the fifteenth aspect, a liquid jet apparatus having
increased the durability and reliability thereof can be
achieved.
[0040] A sixteenth aspect of the present invention provides a
liquid jet apparatus, in which the liquid jet head having the
actuator device according to the ninth aspect is provided.
[0041] In the sixteenth aspect, a liquid jet apparatus having
increased the durability and reliability thereof can be
achieved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] FIG. 1 is an exploded perspective view of a recording head
according to Embodiment 1.
[0043] FIG. 2A is a plan view and FIG. 2B is a cross-sectional view
of the recording head according to Embodiment 1.
[0044] FIGS. 3A to 3D are cross-sectional views showing a
manufacturing process of the recording head according to Embodiment
1.
[0045] FIGS. 4A to 4D are cross-sectional views showing the
manufacturing process of the recording head according to Embodiment
1.
[0046] FIGS. 5A and 5B are cross-sectional views showing the
manufacturing process of the recording head according to Embodiment
1.
[0047] FIG. 6 is a graph showing an example of an X-ray diffraction
measurement result of a zirconium layer.
[0048] FIG. 7 is a graph showing an X-ray diffraction measurement
result of a zirconium layer according to Embodiment 1.
[0049] FIG. 8 is a graph showing an X-ray diffraction measurement
result of a zirconium oxide layer according to Embodiment 1.
[0050] FIGS. 9A to 9C are scanning electron microscopic images
showing cross-sections of zirconium oxide layers according to
Embodiment 1.
[0051] FIG. 10 is a scanning electron microscopic image showing a
surface of a zirconium oxide layer according to Embodiment 1.
[0052] FIG. 11 is a scanning electron microscopic image showing a
surface of another zirconium oxide layer according to Embodiment
1.
[0053] FIG. 12 is a schematic view of a recording apparatus
according to an embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0054] The present invention will be described in detail below
based on embodiments.
Embodiment 1
[0055] FIG. 1 is an exploded perspective view showing an inkjet
recording head provided with an actuator device according to
Embodiment 1 of the present invention. FIGS. 2 (a) and 2 (b) are a
plan and cross-sectional view of FIG. 1. As shown in FIG. 1, a
passage-forming substrate 10 is made of a single crystal silicon
substrate of plane orientation (110) in this embodiment, and on one
surface thereof, an elastic film 50 with a thickness of 1 to 2
.mu.m, which is made of silicon dioxide and previously formed by
thermal oxidation, is formed. In this passage-forming substrate 10,
a plurality of pressure generating chambers 12 are arranged in a
width direction thereof. Moreover, on the outside in a longitudinal
direction of the pressure generating chambers 12 in the
passage-forming substrate 10, a communicating portion 13 is formed.
The communicating portion 13 and the respective pressure generating
chambers 12 are communicated with each other through ink supply
paths 14, each of which is provided for each of the pressure
generating chambers 12. Note that the communicating portion 13
communicates with a reservoir portion in a protective plate to be
described later, and constitutes a part of a reservoir to be a
common ink chamber of the respective pressure generating chambers
12. Moreover, each of the ink supply paths 14 is formed to have a
width narrower than that of a pressure generating chamber 12.
Accordingly, a passage resistance of ink flowing into a pressure
generating chamber 12 from the communicating portion 13 is
maintained constant.
[0056] Moreover, on the opening surface side of the passage-forming
substrate 10, a nozzle plate 20 having nozzle orifices 21 drilled
therein is fixed by use of an adhesive agent, a thermowelding film
or the like, with a mask film to be described later interposed
therebetween. The nozzle orifices 21 communicate with the vicinity
of end portions of the pressure generating chambers 12 at the side
opposite to the ink supply paths 14. Note that the nozzle plate 20
is made of glass ceramics, single crystal silicon substrate,
stainless steel, or the like, having a thickness of, for example,
0.01 to 1 mm and a linear expansion coefficient of, for example,
2.5 to 4.5 [.times.10.sup.-6/degrees C.] at 300 degrees C. or
less.
[0057] Meanwhile, as described above, an elastic film 50 made of
silicon dioxide (SiO.sub.2) and having a thickness of about 1.0
.mu.m, for example, is formed on a side opposite to the opening
surface of the passage-forming substrate 10. An insulation film 55
made of zirconium oxide (ZrO.sub.2), that is, monoclinic zirconium
oxide in this embodiment, for example, is formed on this elastic
film 50. Moreover, as described in detail in, aforementioned
insulation film 55 is formed by subjecting a zirconium layer having
a degrees of orientation to a (002) plane equal to 80% or more to
thermal oxidation. The crystals of the insulation film 55 formed as
described above according to this embodiment are subjected to
priority orientation to a (-111) plane and formed into
column-shaped crystals.
[0058] In such a configuration as described above, adhesion
properties between the insulation film 55 and the elastic film 50
are increased to a large extent. Accordingly, the delamination of
the vibration plate or the like can be prevented from occurring.
Moreover, quality of the respective layers formed on this
insulation film 55 can be stabilized. Accordingly, an inkjet
recording head having increased the durability and reliability
thereof can be achieved.
[0059] Note that the priority orientation means a state where the
orientation of the crystals is not unregulated but a specific
crystal plane is orientated to a predetermined direction
substantially. In this embodiment, for example, the plane (-111) of
the crystals of zirconium oxide is orientated to a front side of
the insulation film 55. A film in which crystals are column-shaped
means a state where substantially circular column-shaped crystals
gather along the plane direction with their central axes
approximately corresponding to the thickness direction to form a
film.
[0060] Moreover, the insulation film 55 as described above is
preferably formed with the thickness of at least 200 nm or more. In
this embodiment, for example, the insulation film 55 is formed with
the thickness of about 400 nm. Note that the insulation film 55
plays a role in preventing the diffusion of lead components in the
elastic film 50 when the piezoelectric layer is formed. If the
insulation film 55 is formed with the thickness of 200 nm or more,
the diffusion of lead components in the elastic film 50 can be
surely prevented.
[0061] Furthermore, the grain size of the insulation film 55
(zirconium oxide) is preferably controlled as appropriate depending
on the thickness of the insulation film 55, specifically, in a
range of 20 nm to 100 nm, for example. Accordingly, the adhesion
properties between the insulation film 55 and the elastic film 50
are further increased. Additionally, the stress of the insulation
film 55 is preferably in a range of -150 to -300 [MPa], that is,
the stress in a tensile direction is preferably in a range of 150
to 300 [MPa]. By setting the stress to the above-described extent,
a crack or the like does not occur in the insulation film 55, thus
improving yield to a large extent.
[0062] Moreover, on the insulation film 55, a lower electrode film
60 having a thickness of about 0.2 .mu.m, for example, a
piezoelectric layer 70 having a thickness of about 1.0 .mu.m, for
example, and an upper electrode film 80 having a thickness of about
0.05 .mu.m, for example, are formed and laminated in a process to
be described later. Accordingly, these constituents collectively
constitute a piezoelectric element 300. Here, the piezoelectric
element 300 means a portion including the lower electrode film 60,
the piezoelectric layer 70, and the upper electrode film 80. In
general, one of the electrodes in the piezoelectric element 300 is
defined as a common electrode, and the other electrode and the
piezoelectric layer 70 are patterned for the respective pressure
generating chambers 12. Moreover, the portion including one of the
electrodes which has been patterned and piezoelectric layer 70, and
exhibiting piezoelectric strain by application of a voltage to the
both electrodes, is herein referred to as a piezoelectric active
portion. In this embodiment, the lower electrode film 60 is used as
the common electrode of the piezoelectric element 300, and the
upper electrode film 80 is used as an individual electrode of the
piezoelectric element 300. However, it is possible to invert the
functions of these electrode films due to convenience for designing
driving circuits or wiring. In any case, the piezoelectric active
portion is formed for each of the pressure generating chambers.
Meanwhile, the piezoelectric element 300 and a vibration plate
undergoing displacement by a drive of the piezoelectric element 300
are herein collectively referred to as a piezoelectric actuator.
Note that, in this embodiment, the elastic film, the insulation
film and the lower electrode film function as the vibration plate.
However, as a matter of course, it may be configured so that only
the elastic film and the insulation film function as the vibration
plate.
[0063] Moreover, lead electrodes 90 made of gold (Au) or the like,
for example, are respectively connected to the upper electrode
films 80 of the respective piezoelectric elements 300 as described
above, and voltages are to be selectively applied to the respective
piezoelectric elements 300 through the lead electrodes 90.
[0064] Meanwhile, a protective plate 30 having a piezoelectric
element holding portion 31 capable of securing a sufficient space
in a region facing the piezoelectric elements 300 so as not to
inhibit actions thereof is joined onto a surface of the
passage-forming substrate 10 on the piezoelectric element 300 side.
The piezoelectric elements 300 are formed inside this piezoelectric
element holding portion 31, and thus are protected in a state where
the piezoelectric elements 300 are not substantially susceptible to
influences from external environments. Moreover, a reservoir
portion 32 is provided for the protective plate 30 in a region
corresponding to the communicating portion 13 of the
passage-forming substrate 10. In this embodiment, the reservoir
portion 32 is provided along the direction of arrangement of the
pressure generating chambers 12 while penetrating the protective
plate 30 in the thickness direction, and is communicated with the
communicating portion 13 of the passage-forming substrate 10 as
described above. In this way, the communicating portion 13 and the
reservoir portion 32 collectively constitute a reservoir 100 to be
the common ink chamber for the respective pressure generating
chambers 12.
[0065] Meanwhile, a through-hole 33 is provided in a region between
the piezoelectric element holding portion 31 and reservoir portion
32 of the protective plate 30 so as to penetrate the protective
plate 30 in its thickness direction. Parts of the lower electrode
film 60 and heads of the lead electrodes 90 are exposed inside this
through-hole 33. Although not illustrated in the drawing, ends of
connection wiring extending from a driving IC are connected to the
lower electrode film 60 and to the lead electrodes 90.
[0066] Here, the material for the protective plate 30 may be, for
example, glass, a ceramic material, metal, resin, or the like.
However, it is preferable to form the protective plate 30 by use of
a material having substantially the same coefficient of thermal
expansion as that of the passage-forming substrate 10. In this
embodiment, the protective plate 30 is formed by use of a single
crystal silicon substrate which is the same material as that of the
passage-forming substrate 10.
[0067] Meanwhile, a compliance plate 40 including a sealing film 41
and a fixing plate 42 is joined onto the protective plate 30. The
sealing film 41 is made of a material having low stiffness and
sufficient flexibility (a polyphenylene sulfide (PPS) film having a
thickness of 6 .mu.m, for example). One side of the reservoir
portion 32 is sealed by this sealing film 41. Meanwhile, the fixing
plate 42 is made of a hard material such as metal (stainless steel
(SUS) having a thickness of 30 .mu.m or the like, for example). A
region of this fixing plate 42 facing the reservoir 100 is
completely removed in its thickness direction and is thereby formed
into an opening portion 43. Accordingly, one side of the reservoir
100 is sealed only by the flexible sealing film 41.
[0068] In the inkjet recording head of this embodiment described
above, ink is taken in from unillustrated external ink supplying
means, and all the inside from the reservoir 100 to the nozzle
orifices 21 is filled with the ink. Then, voltages are applied
respectively between the lower electrode film 60 and the upper
electrode films 80 corresponding to the pressure generating
chambers 12 in accordance with recording signals from unillustrated
driving IC, whereby the elastic film 50, the insulation film 55,
the lower electrode film 60, and the piezoelectric layers 70 are
subjected to flexural deformation. Accordingly, pressure in each of
the pressure generating chambers 12 is increased and ink droplets
are ejected from the nozzle orifices 21.
[0069] Now, a method of manufacturing the inkjet recording head as
described above will be described with reference to FIG. 3A to FIG.
5B. FIG. 3A to FIG. 5B are cross-sectional views of the pressure
generating chamber 12 in the longitudinal direction. First, as
shown in FIG. 3A, a passage-forming substrate wafer 110 which is a
silicon wafer is subjected to thermal oxidation in a diffusion
furnace set to a temperature of about 1100 degrees C., and a
silicon dioxide film 51 constituting the elastic film 50 is formed
on a surface thereof. Note that, in this embodiment, a relatively
thick and stiff silicon wafer having a film thickness of about 625
.mu.m is used as the passage-forming substrate wafer 110.
[0070] Subsequently, as shown in FIG. 3B, the insulation film 55
made of zirconium oxide is formed on the elastic film 50 (the
silicon dioxide film 51). To be more precise, a zirconium layer is
firstly formed on the elastic film 50 by use of a sputtering
method, that is, in this embodiment, a DC sputtering method, for
example. At this time, the zirconium layer is formed by use of
predetermined sputtering conditions, and the degrees of orientation
to the (002) plane of the surface of the zirconium layer is set to
80% or more, or preferably to 90% or more.
[0071] Here, the "degrees of orientation" means a ratio of
diffraction intensity generated when the zirconium layer is
measured by use of a wide angle X-ray diffraction method.
Specifically, when the zirconium layer is measured by use of the
wide angle X-ray diffraction method, peaks of diffraction intensity
corresponding to the (100) plane, the (002) plane, and the (101)
plane are observed. For example, the X-ray diffraction measurement
result of the zirconium layer having a degrees of orientation to
the (002) plane equal to approximately 70% is shown in FIG. 6. It
is understood that the peaks of intensity are observed at the
portion corresponding to the (100) and (101) planes as well as the
portion corresponding to the (002) plane. The "degrees of
orientation to the (002) plane" means a ratio of the peak intensity
corresponding to the (002) plane relative to the sum of the peak
intensities corresponding to the respective planes.
[0072] Furthermore, in order to obtain the zirconium layer having a
degrees of orientation to the (002) plane equal to 80% or more as
described above, the output in forming the zirconium layer by use
of the DC sputtering method is preferably set to 500 W or below.
Additionally, a heating temperature in sputtering is preferably set
to 100 degrees C. or higher. However, if the heating temperature is
too high, the passage-forming substrate 10 may produce cracks or
the like therein, and therefore the heating temperature is
preferably set to 100 to 300 degrees C. Moreover, sputtering
pressure is preferably set to 0.5 Pa or below. By selecting
deposition conditions as appropriate and forming the zirconium
layer by use of the DC sputtering method as described above, the
zirconium layer having a degrees of orientation to the (002) plane
of the surface equal to 80% or more can be surely formed.
[0073] Then, by subjecting the zirconium layer having a degrees of
orientation to the (002) plane equal to 80% or more to thermal
oxidation as described above, the insulation film 55 made of
zirconium oxide is formed. Specifically, in a diffusion furnace
heated to a temperature of about 85% to 1000 degrees C., for
example, the passage-forming substrate wafer 110 is inserted at the
speed (load speed) of 300 mm/min or more, or preferably 500 mm/min
or more, and the zirconium layer is subjected to thermal oxidation.
Thereby, the insulation film 55, which is subjected to priority
orientation to the (-111) plane and in which crystalline state is
favorable, can be obtained. Additionally, the crystals of zirconium
oxide constituting the insulation film 55 formed as described above
are formed into column-shaped ones continuously from the
undersurface to the top surface.
[0074] Here, the X-ray diffraction measurement result of the
zirconium layer formed on a predetermined plate under the
sputtering conditions shown in Table 1 is shown in FIG. 7. In
addition, the X-ray diffraction measurement result of the zirconium
oxide layer formed by subjecting the above-described zirconium
layer to thermal oxidation is shown in FIG. 8. Cross-sectional
scanning electron microscopic (SEM) images of zirconium oxide
layers are shown in FIGS. 9A to 9C. The zirconium oxide layers are
formed by subjecting respective zirconium layers, each of which has
a degrees of orientation to a (002) plane equal to 80%, 90%, and
99.7% respectively, to thermal oxidation under the thermal
oxidation conditions shown in Table 1. Note that in FIGS. 9B and 9C
the right sides of the figures correspond to top surfaces of
zirconium oxide layers. TABLE-US-00001 TABLE 1 Sputtering
Conditions Temperature RT Sputtering output [W] 500 Sputtering
pressure 0.5 [Pa] Ar flow rate [sccm] 30 Thermal Oxidation
Temperature [degrees C.] 900 Conditions Time [Hour] 1 Load speed
[mm/min] 500
[0075] As shown in FIG. 7, while a peak of diffraction intensity
corresponding to the (002) plane is extremely high on the zirconium
layer according to this embodiment formed under the aforementioned
sputtering conditions shown in Table 1, peaks of diffraction
intensity corresponding to the (100) plane and the (101) plane are
extremely low and substantially approximately equal to zero.
Namely, a peak of diffraction intensity is observed substantially
only in a portion corresponding to the (002) plane. From this
result, it is confirmed that the zirconium layer according to this
embodiment has extremely high degrees of orientation to the (002)
plane. Note that the degrees of orientation to the (002) plane of
this zirconium layer is specifically approximately 99.7%.
[0076] Moreover, as shown in FIG. 8, on the zirconium oxide layer
formed by subjecting the zirconium layer of this embodiment to
thermal oxidation, a peak of diffraction intensity is observed
substantially only in a portion corresponding to the (-111) plane.
Accordingly, it is confirmed that crystals of this zirconium oxide
layer are subjected to priority orientation to a (-111) plane.
[0077] Furthermore, as shown in FIG. 9A, in the case of the
zirconium oxide layer formed by subjecting the zirconium layer
having a degrees of orientation to the (002) plane equal to 80% to
thermal oxidation, ball-shaped crystals are observed, but basically
crystals are formed into column-shaped ones. Additionally, as shown
in FIG. 9B, in the case of the zirconium oxide layer formed by
subjecting the zirconium layer having a degrees of orientation to
the (002) plane equal to 90% to thermal oxidation, a certain amount
of ball-shaped crystals are observed, for example, in a portion on
the undersurface side and the like, but most crystals are formed
into column-shaped ones. Moreover, as shown in FIG. 9C, in the case
of the zirconium oxide layer formed by subjecting the zirconium
layer having a degrees of orientation to the (002) plane equal to
99.7% to thermal oxidation, ball-shaped crystals are not observed,
and crystals are formed into column-shaped ones substantially
completely.
[0078] As obvious from these results, by subjecting the zirconium
layer having a relatively high degrees of orientation to the (002)
plane to thermal oxidation, the insulation film 55 (zirconium oxide
layer) which is subjected to priority orientation to a (-111) plane
can be formed. In addition, by subjecting the zirconium layer
having a degrees of orientation to the (002) plane equal to 80% or
more to thermal oxidation to form the insulation film 55, the
insulation film 55 having crystals which are formed into
column-shaped ones continuously from the undersurface to the top
surface can be formed. Moreover, by setting the degrees of
orientation to the (002) plane of the zirconium layer to be higher,
preferably to 90% or more, the preferable insulation film 55 in
which the rate of existence of column-shaped crystals is high can
be formed.
[0079] Since the adhesion properties between the insulation film 55
and the elastic film 50 as described above are extremely high, the
delamination of the vibration plate or the like can be prevented
from occurring. Accordingly, an actuator device having increased
the durability and reliability thereof and an inkjet recording head
provided with the actuator device can be achieved.
[0080] Note that, by controlling the degrees of orientation to the
(002) plane of the zirconium layer, it is also possible to control
the grain size of the insulation film 55 (zirconium oxide layer). A
SEM image of the surface of the zirconium oxide layer formed by
subjecting the zirconium layer having a degrees of orientation to
the (002) plane equal to 99.7% to thermal oxidation is shown in
FIG. 10. A SEM image of the surface of the zirconium oxide layer
formed by subjecting the zirconium layer having a degrees of
orientation to the (002) plane equal to 90% to thermal oxidation is
shown in FIG. 11. As understood from the SEM image shown in FIG.
10, in the case of the zirconium oxide layer formed by subjecting
the zirconium layer having a degrees of orientation to the (002)
plane equal to 99.7% to thermal oxidation, the average grain size
of zirconium oxide is approximately equal to 100 nm. Meanwhile, in
the case of the zirconium oxide layer formed by subjecting the
zirconium layer having a degrees of orientation to the (002) plane
equal to 90% to thermal oxidation, as understood from the SEM image
shown in FIG. 10, the average grain size of zirconium oxide is
approximately equal to 50 nm, and it is smaller than that of the
zirconium oxide in the case of the subjecting of zirconium layer
having a degrees of orientation to the (002) plane equal to 99.7%
to thermal oxidation.
[0081] Namely, the grain size of zirconium oxide varies depending
on the degrees of orientation to the (002) plane of the zirconium
layer before thermal oxidation. As the degrees of orientation to
the (002) plane of the zirconium layer is set to be higher, the
average grain size of zirconium oxide becomes larger. Accordingly,
by controlling the degrees of orientation to the (002) plane of the
zirconium layer, it is possible to control the average grain size
of zirconium oxide constituting the insulation film 55. In
addition, it is possible to control the average grain size of
zirconium oxide surely in a range of about 20 to 100 nm, for
example.
[0082] Note that after forming the insulation film 55 as described
above, as shown in FIG. 3C, for example, platinum and iridium are
laminated on the insulation film 55 to form the lower electrode
film 60, and thereafter the lower electrode film 60 is patterned
into a predetermined shape. Next, as shown in FIG. 3D, for example,
the piezoelectric layer 70 made of lead zirconate titanate (PZT)
and the upper electrode film 80 made of iridium, for example, is
formed on the entire surface of the passage-forming substrate wafer
110. Here, in this embodiment, the piezoelectric layer 70 made of
lead zirconate titanate (PZT) is formed by use of a so-called
sol-gel method, in which so-called sol formed by dissolving and
dispersing a metal-organic material into a solvent is coated and
dried for gelation, and then by baking the material at a high
temperature, the piezoelectric layer 70 made of metal oxide is
obtained. When the piezoelectric layer 70 is formed as described
above, the lead components of the piezoelectric layer 70 may
diffuse in the elastic film 50 in baking. However, the insulation
film 55 made of zirconium oxide is provided under the piezoelectric
layer 70, and therefore the lead components of the piezoelectric
layer 70 does not diffuse in the elastic film 50.
[0083] Subsequently, as shown in FIG. 4A, the piezoelectric layer
70 and the upper electrode film 80 are patterned into a region
corresponding to each of the respective pressure generating
chambers 12 to form the piezoelectric element 300. Next, the lead
electrodes 90 are formed. To be more precise, a metal layer 91 made
of gold (Au) or the like, for example, is formed on the entire
surface of the passage-forming substrate wafer 110 as shown in FIG.
4B. Thereafter, the lead electrodes 90 are formed by patterning the
metal layer 91 for the respective piezoelectric elements 300
through a mask pattern (unillustrated) made of resist or the like,
for example.
[0084] Next, as shown in FIG. 4C, a protective plate wafer 130 made
of a silicon wafer and constituting a plurality of protective
plates 30 is joined to the passage-forming substrate wafer 110 on
the piezoelectric element 300 side. Here, this protective plate
wafer 130 has a thickness of about 400 .mu.m, for example.
Accordingly, the stiffness of the passage-forming substrate wafer
110 is significantly increased by joining the protective plate
wafer 130 thereto.
[0085] Subsequently, the passage-forming substrate wafer 110 is
ground to a certain thickness as shown in FIG. 4D. Thereafter, the
passage-forming substrate wafer 110 is further adjusted to a
predetermined thickness by performing wet etching with
hydrofluoric-nitric acid. For example, the passage-forming
substrate wafer 110 is etched to adjust the thickness to about 70
.mu.m in this embodiment. Subsequently, as shown in FIG. 5A, a mask
film 52 made of silicon nitride (SiN), for example, is newly formed
on the passage-forming substrate wafer 110, and the mask film 52 is
patterned into a predetermined shape. Then, the passage-forming
substrate wafer 110 is subjected to anisotropic etching through
this mask film 52, whereby the pressure generating chambers 12, the
communicating portion 13, the ink supply paths 14, and the like are
formed on the passage-forming substrate wafer 110 as shown in FIG.
5B.
[0086] Note that, thereafter, unnecessary portions in the periphery
portions of the passage-forming substrate wafer 110 and of the
protective plate wafer 130 are cut out and removed by dicing or the
like, for example. Then, the nozzle plate 20 having the nozzle
orifices 21 drilled thereon is joined to the passage-forming
substrate wafer 110 on the side opposite to the protective plate
wafer 130. In addition, the compliance plate 40 is joined to the
protective plate wafer 130, and then the passage-forming substrate
wafer 110 and other constituents thereon are divided into the
passage-forming substrates 10 or the like each having one chip size
as shown in FIG. 1. In this way, the inkjet recording head of this
embodiment is formed.
Other Embodiments
[0087] The present invention has been described above based on the
respective embodiments. However, the present invention will not be
limited only to the foregoing embodiments. For example, in the
foregoing embodiments, the insulation film 55 has been formed on
the elastic film 50. However, the insulation film 55 may be
provided on a portion above the elastic film 50 toward the
piezoelectric layer 70 side. For example, another layer may
interpose between the elastic film 50 and the insulation film
55.
[0088] Moreover, the inkjet recording head of the foregoing
embodiment constitutes a part of a recording head unit including an
ink passage communicating with an ink cartridge and the like, and
is applied to an inkjet recording apparatus. FIG. 12 is a schematic
view showing an example of the inkjet recording apparatus.
[0089] As shown in FIG. 12, in recording head units 1A and 1B
having inkjet recording heads, cartridges 2A and 2B constituting
ink supply means are removably provided. A carriage 3 having these
recording head units 1A and 1B mounted thereon is provided movably
in an axial direction on a carriage shaft 5 attached to an
apparatus main body 4. These recording head units 1A and 1B are,
for example, ones which eject a black ink composition and a color
ink composition, respectively. Driving force of a drive motor 6 is
transmitted to the carriage 3 via a plurality of unillustrated
gears and a timing belt 7. Thus, the carriage 3 having the
recording head units 1A and 1B mounted thereon is moved along the
carriage shaft 5. Meanwhile, a platen 8 is provided along the
carriage shaft 5 in the apparatus main body 4, and a recording
sheet S which is a recording medium such as paper fed by an
unillustrated feed roller or the like is to be transferred on the
platen 8.
[0090] Moreover, in the foregoing embodiment, the inkjet recording
heads has been described as an example of the liquid jet head of
the present invention. However, basic configurations of a liquid
jet head will not be limited to the ones described above. The
present invention is aimed widely at general liquid jet heads, and
as a matter of course, can also be applied to ones ejecting liquids
other than ink. As other liquid jet heads, cited are, for example:
various kinds of recording heads used in an image recording
apparatus such as a printer; a coloring material jet head used for
manufacturing color filters of a liquid crystal display and the
like; an electrode material jet head used for forming electrodes of
an organic EL display, a field emission display (FED) and the like;
a living organic material jet head used for manufacturing biochips;
and the like.
[0091] Furthermore, needless to say, the present invention can be
applied not only to an actuator device to be applied to a liquid
jet head (inkjet recording head) but also to an actuator device to
be applied to any apparatus.
* * * * *