close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JP2015193222

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2015193222
The present invention provides a piezoelectric film utilization apparatus capable of reducing the
resistance value of a lower electrode and increasing the displacement of a vibrating film. The ink
jet print head 1 includes a pressure chamber 5, a vibrating film forming layer 10 including a
vibrating film 10A defining the pressure chamber 5, and a piezoelectric element 6 disposed on
the vibrating film 10A. The piezoelectric element 6 includes a lower electrode 7 formed on the
vibrating film forming layer 10, a piezoelectric film 8 formed on the lower electrode 7, and an
upper electrode 9 formed on the piezoelectric film 8. The lower electrode 7 includes, in a plan
view, a straddle region 7C straddling the periphery of the top surface portion of the pressure
chamber 5. In the lower electrode 7, the thickness of the bridging region 7C and the portion of
the inner electrode region inside the periphery of the top surface of the pressure chamber 5 in
plan view excluding the bridging region 7C is the other portion of the lower electrode 7 It is
formed thinner than the thickness of. [Selected figure] Figure 3
Piezoelectric film utilization device
[0001]
The present invention relates to a piezoelectric film utilizing apparatus such as an actuator or
sensor using a piezoelectric film.
[0002]
An ink jet print head is known as an actuator using a piezoelectric film.
14-04-2019
1
An example of such an ink jet print head is disclosed in US Pat. The inkjet print head disclosed in
Patent Document 1 includes a nozzle substrate, a pressure chamber substrate, a vibrating film,
and a piezoelectric element bonded to the vibrating film. In the pressure chamber substrate, a
pressure chamber into which the ink is introduced is formed, and a diaphragm faces this
pressure chamber. The piezoelectric element is configured by laminating a lower electrode, a
piezoelectric film and an upper electrode from the vibrating film side.
[0003]
Lead zirconate titanate (PZT: PbZr x Ti 1-x O 3) is a velovskite-type ferroelectric substance, and
sensors and actuators utilizing its excellent piezoelectric properties have been proposed. The
piezoelectric film using PZT is formed by a sputtering method or a sol-gel method. The formation
of a PZT film by the sol-gel method is described, for example, in Patent Document 2. In the sol-gel
method, a coating step of applying a precursor solution containing PZT to form a coating film, a
drying step of drying the coating film, and heating the coating film after the drying step cause
gelation of the coating film. A firing step and a main firing step of heat-treating and sintering the
gelled coating film are included. Usually, the PZT film is formed by repeatedly performing the
process including the application process, the drying process, and the pre-baking process a
plurality of times and then performing the main baking process. Then, a piezoelectric film having
a target film thickness is formed by repeatedly performing such a series of steps. Therefore, the
piezoelectric film includes a plurality of stacked PZT layers.
[0004]
JP, 2013-215930, A JP, 6-40727, A
[0005]
In the configuration described in Patent Document 1, the lower electrode is formed to have a
uniform thickness.
In order to increase the displacement of the vibrating film, it is preferable that the thickness of
the lower electrode is thin. However, if the thickness of the lower electrode is reduced, the
resistance value of the lower electrode is increased. An object of the present invention is to
provide a piezoelectric film utilization apparatus capable of reducing the resistance value of the
14-04-2019
2
lower electrode and increasing the displacement of the vibrating film.
[0006]
The piezoelectric film utilization apparatus according to the present invention comprises a cavity,
a diaphragm forming layer including a diaphragm disposed above the cavity and defining a top
surface of the cavity, and a surface of the diaphragm opposite to the cavity. And a piezoelectric
element having a peripheral edge receding inward of the cavity than the vibrating membrane in a
plan view, wherein the piezoelectric element is a surface of the vibrating membrane forming
layer opposite to the cavity A lower electrode formed on the lower electrode, an upper electrode
disposed on the opposite side of the lower electrode with respect to the vibration film forming
layer, and a piezoelectric film provided between the upper electrode and the lower electrode; And
the lower electrode is drawn from the main electrode portion constituting the piezoelectric
element, and from the main electrode portion in a direction along the surface of the vibrating
film forming layer, with respect to the main surface of the vibrating film. From the normal
direction And the extended portion extending outward of the cavity across the top surface
portion peripheral edge of the cavity, and in the plan view, the main electrode portion is closer
than the top surface portion peripheral edge of the cavity in the lower electrode The extension
portion includes an outer electrode region connected to the inner electrode region and outside
the periphery of a top surface portion of the cavity in the lower electrode; The electrode has a
thin portion which is thinly formed across the boundary between the inner electrode region and
the outer electrode region.
[0007]
The region between the peripheral edge of the vibrating film and the peripheral edge of the
piezoelectric element in the vibrating film, that is, the peripheral edge of the vibrating film is a
region not constrained by the peripheral wall of the piezoelectric element or the cavity, and is a
region where large deformation occurs .
Therefore, when the piezoelectric element is driven, the peripheral portion of the vibrating film is
bent so that the inner peripheral side of the peripheral portion of the vibrating film is displaced
in the thickness direction of the cavity, thereby surrounding the peripheral portion of the
vibrating film. The entire central portion is displaced in the thickness direction of the cavity.
[0008]
14-04-2019
3
Of the region straddling the boundary between the inner electrode region and the outer electrode
region in the lower electrode in plan view, the portion inside the periphery of the top surface
portion of the cavity is formed on the peripheral portion of the vibrating membrane . For this
reason, there is a possibility that the region straddling the boundary between the inner electrode
region and the outer electrode region in the lower electrode may prevent the deformation of the
vibrating membrane. In the present invention, the lower electrode has a thin portion formed thin
across the boundary between the inner electrode region and the outer electrode region. As a
result, the deformation of the vibrating membrane is less likely to be impeded compared to when
the entire lower electrode is thick.
[0009]
Further, in the present invention, in the lower electrode, since the thickness of the region other
than the thin portion can be formed thicker than the thin portion, compared to the case where
the entire thickness of the lower electrode is thin, The resistance value can be reduced. That is,
according to the present invention, it is possible to provide a piezoelectric film utilization
apparatus capable of reducing the resistance value of the lower electrode and increasing the
displacement of the vibrating film.
[0010]
In one embodiment of the present invention, the thin portion is formed on the entire area of the
boundary between the inner electrode area and the outer electrode area in the lower electrode
(claim 2). In this configuration, the displacement of the diaphragm can be made larger than in the
case where the thin portion is formed only in part of the boundary between the inner electrode
region and the outer electrode region in the lower electrode. In one embodiment of the present
invention, the main electrode portion is also formed in a thin portion having a small thickness
(claim 3). In this configuration, the displacement of the diaphragm can be further increased.
[0011]
In one embodiment of the present invention, a thickness of a region including the main electrode
portion in the lower electrode is thicker than a thickness of the thin portion (claim 4). In this
configuration, the resistance value of the lower electrode can be further reduced. In one
14-04-2019
4
embodiment of the present invention, the thickness of the entire area of the main electrode
portion is larger than the thickness of the thin portion, and the thickness of the region other than
the main electrode portion in the inner electrode region is thin. ). In this configuration, the
resistance value of the lower electrode can be further reduced, and the displacement of the
diaphragm can be further increased.
[0012]
In one embodiment of the present invention, the thin portion is formed at a part of a boundary
between the inner electrode region and the outer electrode region in the lower electrode (claim
6). In this configuration, the resistance value of the lower electrode can be reduced as compared
to the case where the thin portion is formed in the entire boundary line between the inner
electrode region and the outer electrode region in the lower electrode. In one embodiment of the
present invention, the thin portion includes a plurality of thin portions formed at intervals along
a boundary between the inner electrode region and the outer electrode region in the lower
electrode. Item 7).
[0013]
In one embodiment of the present invention, the plurality of thin portions have a rectangular
shape elongated in a direction along a boundary between the inner electrode region and the
outer electrode region in the lower electrode (claim 8). In one embodiment of the present
invention, the thickness of the region including the main electrode portion in the lower electrode
is thicker than the thickness of the thin portion (claim 9). In this configuration, the resistance
value of the lower electrode can be further reduced.
[0014]
In one embodiment of the present invention, the thickness of the entire area of the main
electrode portion is larger than the thickness of the thin portion, and the thickness of the region
other than the main electrode portion in the inner electrode region is thin (claim 10) ). In this
configuration, the resistance value of the lower electrode can be further reduced, and the
displacement of the diaphragm can be further increased. In one embodiment of the present
invention, the top surface portion of the cavity has a rectangular shape longer in one direction in
the plan view, and the main electrode portion has a width in the lateral direction of the top
14-04-2019
5
surface portion of the cavity in the plan view The rectangular shape having a short width and a
length shorter than the longitudinal length of the top surface of the cavity is longer in the one
direction, and both end edges and both side edges thereof are greater than both end edges and
both edges of the top surface of the cavity The extension portion is respectively retracted from
the side edge of the main electrode portion to the middle portion of the corresponding side edge
of the top surface portion of the cavity, and the extension portion is outside the edge of the top
surface portion. The boundary lines between the inner electrode area and the outer electrode
area extend in two directions including two boundary lines corresponding to the middle part of
each side edge of the top face of the cavity (claim 11).
[0015]
In one embodiment of the present invention, a plurality of the cavities are provided, and the
plurality of cavities are arranged side by side in the lateral direction of the cavities (claim 12). In
this configuration, it is possible to provide, for example, a piezoelectric film utilizing apparatus
suitable for an inkjet print head. In an embodiment of the present invention, opposing side edges
of two main electrodes disposed respectively on two adjacent cavities are connected by the
extensions drawn therefrom, and the extensions The piezoelectric film utilization apparatus
according to claim 12, wherein a thickness of a substantially entire region of a region between
two adjacent cavities in the portion is thicker than a thickness of the thin portion (claim 13). In
this configuration, it is possible to provide a piezoelectric film utilizing apparatus suitable for an
ink jet print head and having a lower resistance value of the lower electrode.
[0016]
In one embodiment of the present invention, in the planar view, the extension portions drawn
from the plurality of main electrode portions disposed on the plurality of cavities are the
respective cavities rather than one end in the longitudinal direction of the respective cavities in
the plan view. It connects in the position of the outside of (claim 14). In this configuration, the
lower electrode can be connected to the outside at a position outside each cavity than one
longitudinal end of each cavity.
[0017]
In one embodiment of the present invention, the lower electrode is provided with a plurality of
14-04-2019
6
cut-out portions in a region including each of the end portions on the one end side in the
longitudinal direction of the respective cavities in the plan view. ). In this configuration, the
displacement of the piezoelectric film of each piezoelectric element can be further increased.
[0018]
FIG. 1 is a schematic plan view of an ink jet print head to which a piezoelectric film utilization
apparatus according to an embodiment of the present invention is applied. FIG. 2 is a schematic
enlarged cross-sectional view along the line II-II in FIG. FIG. 3 is a schematic enlarged crosssectional view along the line III-III in FIG. FIG. 2 is a schematic perspective view of the inkjet print
head. FIG. 5 is a partially enlarged plan view of FIG. FIG. 6 is a process diagram showing an
example of a manufacturing process of the ink jet print head. FIG. 7 is a plan view for explaining
the configuration of an ink jet print head according to another embodiment of the present
invention. FIG. 8 is a cross-sectional view for explaining the configuration of the inkjet print head
of FIG. FIG. 9 is a plan view for explaining the configuration of an ink jet print head according to
still another embodiment of the present invention. FIG. 10 is a schematic cross-sectional view of
a piezoelectric film.
[0019]
Hereinafter, embodiments of the present invention will be described in detail with reference to
the attached drawings. FIG. 1 is a schematic plan view of an ink jet print head to which a
piezoelectric film utilization apparatus according to an embodiment of the present invention is
applied. FIG. 2 is a schematic enlarged cross-sectional view along the line II-II in FIG. FIG. 3 is a
schematic enlarged cross-sectional view along the line III-III in FIG. FIG. 4 is a schematic
perspective view of an ink jet print head. However, in FIG. 1 and FIG. 4, the hydrogen barrier film
indicated by reference numeral 13 in FIGS. 2 and 3 and the insulating film indicated by reference
numeral 14 are omitted.
[0020]
Referring to FIG. 2, the inkjet print head 1 includes a silicon substrate 2 and a nozzle substrate 3
having a discharge port 3 a for discharging ink. The vibrating film forming layer 10 is stacked on
the silicon substrate 2. A pressure chamber (cavity) 5 as an ink flow path (ink reservoir) is
formed in a laminate of the silicon substrate 2 and the vibrating membrane forming layer 10.
14-04-2019
7
The pressure chamber 5 is formed in the silicon substrate 2 and is formed in the space 5A
penetrating the silicon substrate 2 in the thickness direction, and on the back surface (surface on
the silicon substrate 2 side) of the vibrating membrane forming layer 10 and in the space 5A. It is
comprised from the continuous recessed part 5B.
[0021]
The nozzle substrate 3 is formed of, for example, a silicon plate, is bonded to the back surface of
the silicon substrate 2, and defines the pressure chamber 5 together with the silicon substrate 2
and the vibrating film forming layer 10. The nozzle substrate 3 has a recess 3 b facing the
pressure chamber 5, and the ink discharge passage 3 c is formed on the bottom of the recess 3 b.
The ink discharge passage 3 c penetrates the nozzle substrate 3 and has a discharge port 3 a on
the opposite side to the pressure chamber 5. Therefore, when the volume change of the pressure
chamber 5 occurs, the ink stored in the pressure chamber 5 passes through the ink discharge
passage 3c and is discharged from the discharge port 3a.
[0022]
The pressure chamber 5 is formed by digging the silicon substrate 2 and the vibrating film
forming layer 10 from the back surface side of the silicon substrate 2. In the silicon substrate 2
and the vibrating membrane forming layer 10, an ink supply path 4 (see FIG. 1 and FIG. 3
together) communicating with the pressure chamber 5 is further formed. The ink supply path 4
is in communication with the pressure chamber 5 and is formed to guide the ink from the ink
tank (for example, an ink cartridge) which is an ink supply source to the pressure chamber 5.
[0023]
The pressure chamber 5 is formed to elongate along the ink flow direction 21 which is the left
and right direction in FIG. The top wall portion of the pressure chamber 5 in the vibrating film
forming layer 10 constitutes a vibrating film 10A. The vibrating film 10A (the vibrating film
forming layer 10) is made of, for example, a silicon oxide (SiO 2) film formed on the silicon
substrate 2. The vibrating film 10A (the vibrating film forming layer 10) is formed, for example,
on a silicon (Si) layer formed on the silicon substrate 2, a silicon oxide (SiO 2) layer formed on
the silicon layer, and a silicon oxide layer It may be composed of a laminated body with a silicon
nitride (SiN) layer. In this specification, the vibrating membrane 10A means a top wall portion
14-04-2019
8
which divides the pressure chamber 5 in the vibrating membrane forming layer 10. Therefore, in
the vibrating membrane forming layer 10, the portion other than the top wall portion of the
pressure chamber 5 does not constitute the vibrating membrane 10A.
[0024]
The thickness of the vibrating membrane 10A is, for example, 0.4 μm to 2 μm. When the
vibrating film 10A is formed of a silicon oxide film, the thickness of the silicon oxide film may be
about 1.2 μm. When the vibrating film 10A is formed of a laminate of a silicon layer, a silicon
oxide layer and a silicon nitride layer, the thicknesses of the silicon layer, the silicon oxide layer
and the silicon nitride layer are each about 0.4 μm It is also good.
[0025]
The pressure chamber 5 is divided by the vibrating film 10A, the silicon substrate 2, and the
nozzle substrate 3. In this embodiment, the pressure chamber 5 is formed in a substantially
rectangular parallelepiped shape. The length of the pressure chamber 5 may be, for example,
about 800 μm, and the width thereof may be about 55 μm. The ink supply path 4 is formed to
communicate with one end in the longitudinal direction of the pressure chamber 5 (in this
embodiment, the end located on the opposite side to the discharge port 3 a). The discharge port
3 a of the nozzle substrate 3 is disposed in the vicinity of the other end in the longitudinal
direction of the pressure chamber 5 in this embodiment.
[0026]
The piezoelectric element 6 is disposed on the surface of the vibrating membrane 10A. The
piezoelectric element 6 includes a lower electrode 7 formed on the vibrating film forming layer
10, a piezoelectric film 8 formed on the lower electrode 7, and an upper electrode 9 formed on
the piezoelectric film 8. There is. In other words, the piezoelectric element 6 is configured by
sandwiching the piezoelectric film 8 between the upper electrode 9 and the lower electrode 7
from above and below. The lower electrode 7 has, for example, a two-layer structure in which a
Ti (titanium) layer and a Pt (platinum) layer are sequentially stacked from the vibrating film 10A
side. Besides, the lower electrode 7 can be formed of a single film such as an Au (gold) film, a Cr
(chromium) layer, or a Ni (nickel) layer. The lower electrode 7 has a main electrode portion 7A in
contact with the lower surface of the piezoelectric film 8 and an extension 7B extending to an
14-04-2019
9
outer region of the piezoelectric film 8 (see also FIGS. 1 and 4). .
[0027]
For example, a PZT (PbZrxTi1-xO3: lead zirconate titanate) film formed by a sol-gel method or a
sputtering method can be applied as the piezoelectric film 8. Such a piezoelectric film 8 is made
of a sintered body of metal oxide crystal. The thickness of the piezoelectric film 8 is preferably 1
μm to 5 μm. The total thickness of the vibrating film 10A is preferably about the same as the
thickness of the piezoelectric film 8 or about 2/3 of the thickness of the piezoelectric film.
[0028]
The upper electrode 9 is formed in substantially the same shape as the piezoelectric film 8 in a
plan view. The upper electrode 9 has a three-layer structure in which, for example, an IrO 2
(iridium oxide) layer and an Ir (iridium) layer are sequentially stacked from the piezoelectric film
8 side, and a Pt layer or an Au layer is further stacked. The hydrogen barrier film 13 covers the
surface of the vibrating film forming layer 10, the surface of the piezoelectric element 6, and the
surface of the extension of the lower electrode 7. The hydrogen barrier film 13 is covered with,
for example, Al 2 O 3 (alumina). Thereby, the characteristic deterioration of the piezoelectric film
8 due to hydrogen reduction can be prevented. An insulating film 14 is stacked on the hydrogen
barrier film 13. Insulating film 14 is made of, for example, SiO 2. Wirings 15 are formed on the
insulating film 14. The wiring 15 is made of a metal material containing Al (aluminum).
[0029]
One end of the wiring 15 is disposed above one end of the upper electrode 9. A through hole 16
which penetrates the hydrogen barrier film 13 and the insulating film 14 continuously is formed
between the wiring 15 and the upper electrode 9. One end of the wiring 15 enters the through
hole 16 and is connected to the upper electrode 9 in the through hole 16. In addition, the
hydrogen barrier film 13 and the insulating film 14 have a cutting portion 17 at a position
corresponding to a region surrounded by the peripheral portion on the surface of the upper
electrode 9. The cut portion 17 is a portion where the hydrogen barrier film 13 and the
insulating film 14 are cut.
14-04-2019
10
[0030]
In addition, an opening 18 which penetrates the hydrogen barrier film 13 and the insulating film
14 continuously is formed at a position corresponding to a predetermined region on the
extension of the lower electrode 7, and the surface of the lower electrode 7 is an opening.
Exposed through 18 o'clock. The exposed portion constitutes a pad portion 7 d for connecting
the lower electrode 7 to the outside. On the surface of the vibrating film forming layer 10, on the
upstream side of the upstream end of the ink flow direction 21 of the piezoelectric element 6,
viewed from the direction orthogonal to the ink flow direction 21 (direction along the surface of
the silicon substrate 2) The hydrogen barrier film 13 and the insulating film 14 are formed only
in the region near the upstream end of the piezoelectric element 6, and the hydrogen barrier film
13 and the insulating film 14 are not formed on the upstream side thereof.
[0031]
The piezoelectric element 6 is formed at a position facing the pressure chamber 5 with the
vibrating film 10A interposed therebetween. That is, the piezoelectric element 6 is formed to be
in contact with the surface of the vibrating film 10A opposite to the pressure chamber 5. The
pressure chamber 5 is filled with ink supplied from an ink tank (not shown) through the ink
supply path 4. The vibrating membrane 10 </ b> A defines the top surface of the pressure
chamber 5 and faces the pressure chamber 5. The vibrating membrane 10A is supported by the
portion around the pressure chamber 5 in the laminated body of the vibrating membrane
forming layer 10 and the silicon substrate 2, and in the direction facing the pressure chamber 5
(in other words, the thickness direction of the vibrating membrane 10A) ) Is flexible.
[0032]
The wiring 15 and the pad portion 7 d of the lower electrode 7 are connected to the drive circuit
20. The drive circuit 20 may be formed in a region different from the pressure chamber 5 of the
silicon substrate 2 or may be formed outside the silicon substrate 2. When a drive voltage is
applied from the drive circuit 20 to the piezoelectric element 6, the piezoelectric film 8 is
deformed by the reverse piezoelectric effect. As a result, the vibrating film 10A is deformed
together with the piezoelectric element 6, whereby the volume change of the pressure chamber 5
is brought about, and the ink in the pressure chamber 5 is pressurized. The pressurized ink
passes through the ink discharge passage 3c, and is discharged as fine droplets from the
discharge port 3a.
14-04-2019
11
[0033]
Referring to FIGS. 1 to 4, in the laminate of the silicon substrate 2 and the vibrating membrane
forming layer 10, a plurality of pressure chambers 5 extend in parallel with each other and are
formed in a stripe shape. The plurality of pressure chambers 5 are formed at equal intervals at
small intervals (for example, about 30 μm to 350 μm) in their width direction. Each pressure
chamber 5 has a rectangular shape elongated in the ink flow direction 21 from the ink supply
passage 4 to the discharge passage 3 c in a plan view. That is, the top surface portion of the
pressure chamber 5 has two side edges 5 c and 5 d along the ink flow direction 21 and two edge
5 a and 5 b along the direction orthogonal to the ink flow direction 21. The ink supply passage 4
is divided into two passages at one end of the pressure chamber 5 and is in communication with
the common ink passage 19. The common ink passage 19 is in communication with the ink
supply passage 4 corresponding to the plurality of pressure chambers 5 and is formed to supply
the ink from the ink tank to the ink supply passage 4.
[0034]
The piezoelectric element 6 is formed so that the length in the ink flow direction 21 (the same
direction as the longitudinal direction of the vibrating membrane 10A) is shorter than the length
in the longitudinal direction of the vibrating membrane 10A, and has a rectangular shape in plan
view . Then, as shown in FIG. 1, both end edges 6a and 6b along the lateral direction of the
piezoelectric element 6 open a predetermined distance d1 (for example, 5 μm) with respect to
the corresponding end edges 10Aa and 10Ab of the vibrating membrane 10A. Is located inside.
Further, the piezoelectric element 6 has a width in the short side direction (a direction parallel to
the main surface of the silicon substrate 2) orthogonal to the longitudinal direction of the
vibrating membrane 10A is the short side of the vibrating membrane 10A (the top surface
portion of the pressure chamber 5). It is formed narrower than the width of the direction. The
both side edges 6c and 6d along the longitudinal direction of the piezoelectric element 6 are
disposed inside the corresponding side edges 10Ac and 10Ad of the vibrating membrane 10A at
predetermined intervals d2 (for example, 5 μm).
[0035]
The lower electrode 7 is a flat plate having a predetermined width in a direction along the ink
14-04-2019
12
circulation direction 21 in plan view and extending across the plurality of pressure chambers 5
in a direction orthogonal to the ink circulation direction 21. It is a common electrode shared by
the piezoelectric elements 6. The first side 7 a of the lower electrode 7 along the direction
orthogonal to the ink flow direction 21 is aligned with a line connecting one edge 6 a of the
plurality of piezoelectric elements 6 in plan view. The second side 7b opposite to the first side 7a
of the lower electrode 7 is outside the edge 10Ab of the vibrating membrane 10A corresponding
to the other edge 6b of the plurality of piezoelectric elements 6 (downstream of the ink flow
direction 21 Side).
[0036]
In the lower electrode 7, on the downstream side of the ink flow direction 21 of each
piezoelectric element 6, a cutout 7 c having a rectangular shape in a plan view and penetrating
the lower electrode 7 is formed. Each cutout 7 c has two side edges (short sides) along the ink
circulation direction 21 and two edges (long sides) along the direction orthogonal to the ink
circulation direction 21 in plan view. . One edge of the cut-out portion 7c is disposed at a
position aligned with the edge 6b of the piezoelectric element 6 with respect to the ink flow
direction 21, and the other edge is outside the edge 10Ab of the vibrating membrane 10A (in the
ink flow direction 21 Located downstream). One side edge of the excising part 7c is disposed
outside the one side edge 10Ac of the vibrating membrane 10A, and the other side edge of the
excising part 7c is disposed outside the other side edge 10Ad of the vibrating membrane 10A.
There is. Therefore, in plan view, the end on the edge 10Ab side of the vibrating membrane 10A
is disposed inside the cutout 7c. In a region between the second side 7 b of the lower electrode 7
and the plurality of cut-out portions 7 c, a rectangular pad portion 7 d elongated in the direction
perpendicular to the ink flow direction 21 is formed.
[0037]
Lower electrode 7 is drawn from main electrode portion 7A constituting piezoelectric element 6
and in a direction along the surface of vibrating membrane forming layer 10 from main electrode
portion 7A, and the peripheral edge of the top surface portion (vibration membrane 10A) of
pressure chamber 5 And an outwardly extending extension 7B of the peripheral edge of the top
surface of the pressure chamber 5 in a straddling manner. The main electrode portion 7A is
formed shorter than the vibrating membrane 10A along the longitudinal direction of the
vibrating membrane 10A, and the both end edges thereof are predetermined as described above
with respect to the corresponding both end edges 10Aa and 10Ab of the vibrating membrane
10A. It is arranged inside with an interval d1. Further, the width of the main electrode portion 7A
14-04-2019
13
along the widthwise direction of the vibrating membrane 10A is formed narrower than the width
in the widthwise direction of the vibrating membrane 10A, and both side edges thereof
correspond to corresponding both sides of the vibrating membrane 10A. With respect to the
edges 10Ac and 10Ad, the gap d2 is opened and disposed inside.
[0038]
The extension 7B straddles the corresponding side edges 5c and 5d of the top surface of the
pressure chamber 5 from the side edges of the main electrode 7A in plan view, and the outside of
the side edges 5c and 5d of the top surface of the pressure chamber 5 It extends to the side. The
extension 7B is a region excluding the main electrode portion 7A in the entire region of the lower
electrode 7. Referring to FIG. 5, in the extension 7B, a portion straddling the peripheral edge (in
this embodiment, the side edges 5c and 5d in this embodiment) of the top surface portion of the
pressure chamber 5 may be referred to as "crossing region 7C" in plan view. . Further, in the
lower electrode 7, a region inside the peripheral edges 5 a to 5 d of the top surface portion of the
pressure chamber 5 in plan view is referred to as “inner electrode region” and outside the
peripheral edges 5 a to 5 d of the top surface portion of the pressure chamber 5. A region may
be referred to as an "outer electrode region".
[0039]
The main electrode portion 7A in the lower electrode 7 is included in the inner electrode region.
The extension 7B of the lower electrode 7 is composed of an area other than the main electrode
portion 7A in the inner electrode area and an external electrode area. A region in the vicinity of
the boundary between the inner electrode region and the outer electrode region is a crossing
region 7C. In this embodiment, the boundary between the inner electrode region and the outer
electrode region has two boundary lines corresponding to the middle portions of the side edges 5
c and 5 d of the top surface of the pressure chamber 5. Therefore, in this embodiment, the lower
electrode 7 has two straddle regions 7C straddling the middle portions of the side edges 5c and
5d of the top surface portion of the pressure chamber 5 in plan view.
[0040]
In this embodiment, the thickness of the bridging region 7C of the lower electrode 7 and the
portion of the inner electrode region excluding the bridging region 7C is thinner than the
14-04-2019
14
thickness of the other regions. That is, in this embodiment, the lower electrode 7 corresponds to
the thin portion corresponding to the crossing region 7C, the thin portion corresponding to the
region excluding the crossing region 7C in the inner electrode region, and the regions other than
these regions. And a thick portion. The thin portion of the lower electrode 7 is shown in FIG. 5 by
a dot area. In this embodiment, the width of the region belonging to the inner electrode region in
each crossing region 7C is between the corresponding side edge of the inner electrode region in
the inner electrode region and the corresponding side edge of the main electrode portion 7A. It is
set to the same width as the area width. Therefore, in this embodiment, lower electrode 7 has a
thin portion corresponding to straddle region 7C, a thin portion corresponding to main electrode
portion 7A, and a thick portion corresponding to regions other than these regions. There is. The
width of the region belonging to the inner electrode region in each crossing region 7C is greater
than the width of the region between the corresponding side edge of the inner electrode region
in the inner electrode region and the corresponding side edge of the main electrode portion 7A.
It may be set to a short width.
[0041]
Referring to FIGS. 1 to 4, upper electrode 9 is formed shorter than vibrating membrane 10A
along the longitudinal direction of vibrating membrane 10A, and both end edges thereof
correspond to corresponding both end edges 10Aa of vibrating membrane 10A. , 10Ab, with the
predetermined spacing d1 open. The upper electrode 9 is formed such that the width along the
width direction of the vibrating membrane 10A is narrower than the width in the width direction
of the vibrating membrane 10A, and the side edges thereof correspond to the corresponding side
edges of the vibrating membrane 10A. The interval d2 is opened with respect to 10Ac and 10Ad,
and they are arranged inside.
[0042]
The piezoelectric film 8 is formed in the same pattern as the upper electrode 9. That is, the
piezoelectric film 8 is formed shorter than the vibrating film 10A in the longitudinal direction of
the vibrating film 10A, and both end edges thereof are predetermined with respect to
corresponding both end edges 10Aa and 10Ab of the vibrating film 10A. The interval d1 between
the The piezoelectric film 8 is formed such that the width along the width direction of the
vibrating film 10A is narrower than the width in the width direction of the vibrating film 10A,
and both side edges thereof correspond to corresponding both sides of the vibration film 10A.
With respect to the edges 10Ac and 10Ad, the gap d2 is opened and disposed inside. The lower
surface of the piezoelectric film 8 is in contact with the upper surface of the portion constituting
14-04-2019
15
the piezoelectric element 6 in the lower electrode 7, and the upper surface of the piezoelectric
film 8 is in contact with the lower surface of the upper electrode 9.
[0043]
The wiring 15 is connected at one end to one end of the upper electrode 9 (an end on the one
end 6a side of the piezoelectric element 6) and extends in the direction opposite to the ink flow
direction 21 in plan view. The pad portion 15B is integrated with the lead-out portion 15A, and is
connected to the tip of the lead-out portion 15A. The lead-out portion 15A is one end portion of
the upper surface of the piezoelectric element 6 (an end portion on one edge 6a side of the
piezoelectric element 6) and an end surface of the piezoelectric element 6 connected thereto
except for a portion connected to the upper electrode 9. It is formed on the surface of the
insulating film 14 covering the surface of the vibrating film forming layer 10. The pad portion
15B is formed on the surface of the vibrating film forming layer 10 where the hydrogen barrier
film 13 and the insulating film 14 are not formed.
[0044]
An annular region (peripheral annular region elongated in the ink flow direction 21 in this
embodiment) between the peripheral edge 10Aa to 10Ad of the diaphragm 10A and the
peripheral edge 6a to 6d of the piezoelectric element 6 in the diaphragm 10A is the piezoelectric
element 6 or It is an area which is not constrained by the peripheral wall of the pressure
chamber 5 and is an area where large deformation occurs. That is, the peripheral portion of the
vibrating membrane 10A is a region where large deformation occurs. Therefore, when the
piezoelectric element 6 is driven, the peripheral edge of the vibrating membrane 10A is bent so
that the inner peripheral side of the peripheral edge of the vibrating membrane 10A is displaced
in the thickness direction of the pressure chamber 5 (downward in this embodiment). As a result,
the entire central portion surrounded by the peripheral portion of the vibrating membrane 10A
is displaced in the thickness direction of the pressure chamber 5 (downward in this embodiment).
[0045]
Portions inside the top surface portion peripheral edges 5a to 5d of the pressure chamber 5 in
the straddle region 7C of the lower electrode 7 (in this embodiment, the side edges 5c and 5d of
14-04-2019
16
the top surface portion) are formed on the peripheral portion of the diaphragm 10A. It is done.
Therefore, the straddle region 7C of the lower electrode 7 may prevent the deformation of the
vibrating membrane 10A. In this embodiment, since the lower electrode 7 has a thin portion
corresponding to the straddle region 7C, the deformation of the vibrating membrane 10A is less
likely to be impeded compared to the case where the entire lower electrode 7 is thick. Further, in
this embodiment, the lower electrode 7 has a thin portion corresponding to the area (in this
embodiment, the main electrode portion 7A in the present embodiment) other than the thinwalled portion corresponding to the straddle region 7C, of the inner electrode region. Because of
the presence of the parts, the deformation of the vibrating membrane 10A is less likely to be
impeded.
[0046]
Further, in this embodiment, the lower electrode 7 is a thick portion corresponding to a region
excluding the crossing region 7C and a region (the main electrode portion 7A in this
embodiment) excluding the crossing region 7C in the inner electrode region. The resistance value
of the lower electrode 7 can be reduced as compared with the case where the entire thickness of
the lower electrode 7 is thin. That is, according to this embodiment, the resistance value of the
lower electrode 7 can be reduced, and the displacement of the diaphragm 10A can be increased.
[0047]
FIG. 6 is a process diagram showing an example of a manufacturing process of the ink jet print
head 1. First, the vibrating film forming layer 10 is formed on the surface of the silicon substrate
2 (S1). Specifically, a silicon oxide layer (for example, 1.2 μm thick) is formed on the surface of
silicon substrate 2. When the vibrating film forming layer 10 is formed of a laminate of a silicon
layer, a silicon oxide layer and a silicon nitride layer, a silicon layer (for example, 0.4 μm thick)
is formed on the surface of the silicon substrate 2 A silicon oxide layer (for example, 0.4 μm
thick) is formed thereon, and a silicon nitride layer (for example, 0.4 μm thick) is formed on the
silicon oxide layer. For example, an underlying oxide film such as Al 2 O 3, MgO, or ZrO 2 may be
formed on the surface of the vibrating film forming layer 10. These base oxide films prevent the
metal atoms from coming out of the piezoelectric film 8 to be formed later. If the metal electrons
come out, the piezoelectric characteristics of the piezoelectric film 8 may be deteriorated. In
addition, if the removed metal atoms are mixed into the silicon layer constituting the vibrating
film 10A, the durability of the vibrating film 10A may be deteriorated.
14-04-2019
17
[0048]
Next, a lower electrode film which is a material layer of the lower electrode 7 is formed on the
vibrating film forming layer 10 (on the base oxide film when the base oxide film is formed) (S2) .
The lower electrode film is made of, for example, a Pt / Ti laminated film having a Ti film (for
example, 100 Å to 400 Å thick) as a lower layer and a Pt film (eg, 100 Å to 4000 Å thick) as an
upper layer. Such lower electrode film may be formed by sputtering.
[0049]
Next, a thin portion of the lower electrode film is formed (S3). That is, a resist mask is formed to
cover the region other than the region to be the thin portion of the lower electrode 7 (the region
excluding the crossover region 7C of the crossover region 7C of the lower electrode 7 and the
inside electrode region) by photography. By using the mask as a mask, the lower electrode film is
etched to form a thin portion of the lower electrode 7. The thickness of the thin portion is, for
example, about 1000 Å, and the thickness of the portion (thick portion) other than the thin
portion is, for example, about 2000 Å.
[0050]
Next, a material film (piezoelectric material film) of the piezoelectric film 8 is formed on the
entire surface of the lower electrode film (S4). Specifically, for example, a PZT film having a
thickness of 1 μm to 5 μm is formed by a sol-gel method. Such a PZT film is made of a sintered
body of metal oxide crystal grains. Next, an upper electrode film which is a material of the upper
electrode 9 is formed on the entire surface of the piezoelectric material film (step S5). The upper
electrode film is made of, for example, an Ir / IrO 2 laminated film having an IrO 2 film (for
example, 400 Å to 1600 Å thick) as a lower layer and an Ir film (eg, 500 Å to 2000 Å thick) as an
upper layer. Such upper electrode film may be formed by sputtering.
[0051]
Next, patterning of the upper electrode film, the piezoelectric material film, and the lower
electrode film is performed (S6-S12). First, a resist mask of the pattern of the lower electrode 7 is
formed by photography (S6), and the upper electrode film, the piezoelectric material film and the
14-04-2019
18
lower electrode film are etched in the same pattern using the resist mask as a mask. A lower
electrode film of a predetermined pattern is formed (steps S6-S9). More specifically, the upper
electrode film is patterned by dry etching (step S7), the piezoelectric material film is patterned by
wet etching (S8), and the lower electrode film is patterned by dry etching (step S9). Thus, the
lower electrode 7 is formed. The etchant used for the wet etching of the piezoelectric material
film may be acids mainly composed of hydrochloric acid.
[0052]
Next, after peeling off the resist mask, a resist mask of the pattern of the piezoelectric film 8 is
formed by photolithography (S10), and the upper electrode film and the piezoelectric material
film are etched to the same pattern using this resist pattern (S11-S12). More specifically, the
upper electrode film is patterned by dry etching (S11), and the piezoelectric material film is
patterned by wet etching (S12). Thus, the piezoelectric film 8 and the upper electrode 9 are
formed.
[0053]
Thereafter, the resist mask is peeled off, and a hydrogen barrier film 13 covering the entire
surface is formed (S13). The hydrogen barrier film 13 may be an Al 2 O 3 film formed by a
sputtering method, and its film thickness may be 400 Å to 1600 Å. Further, the insulating film
14 covering the hydrogen barrier film 13 is formed (S14). The insulating film 14 may be a SiO 2
film, and its film thickness may be 2500 Å to 10000 Å.
[0054]
Next, back surface grinding is performed to thin the silicon substrate 2 (S15). For example, the
silicon substrate 2 having a thickness of about 670 μm in the initial state may be thinned to a
thickness of about 300 μm. Then, the pressure chamber 5 is formed by performing etching (dry
etching or wet etching) from the back surface of the silicon substrate 2 on the laminated body of
the silicon substrate 2 and the vibrating film forming layer 10, and at the same time, the
vibrating film 10A is formed. It is formed. The underlying oxide film formed on the surfaces of
the hydrogen barrier film 13 and the vibrating film forming layer 10 prevents the metallic
element (Pb, Zr, Ti in the case of PZT) from coming off from the piezoelectric film 8 during this
etching. The piezoelectric characteristics of the piezoelectric film 8 are kept good. Further, as
14-04-2019
19
described above, the base oxide film formed on the surface of the vibrating film forming layer 10
contributes to the maintenance of the durability of the silicon layer forming the vibrating film
10A.
[0055]
Thereafter, the hydrogen barrier film 13 and the insulating film 14 are patterned, the wiring 15
is formed, and the like, whereby the ink jet print head 1 shown in FIGS. 1 to 4 is obtained. In the
embodiment described above, the thickness of the bridging region 7C of the lower electrode 7
and the region of the inner electrode region excluding the bridging region 7C (the main electrode
portion 7A in this embodiment) is greater than the thicknesses of the other regions. It is thinly
formed. However, as shown in FIGS. 7 and 8, even if the thickness of the area (main electrode
portion 7A in this embodiment) excluding the crossing area 7C in the inner electrode area is
formed to be thicker than the thickness of the crossing area 7C. Good. In other words, only the
straddle region 7C of the lower electrode 7 may be thinner than the other regions. That is, the
lower electrode 7 may have a thin portion corresponding to the crossing region 7C and a thick
portion corresponding to a region other than the crossing region 7C. The thin-walled portion of
the lower electrode 7 in this case is shown by a dot area in FIG.
[0056]
Also in such a configuration, the resistance value of the lower electrode 7 can be reduced, and
the displacement of the diaphragm 10A can be increased. Moreover, in such a configuration, the
thickness of the main electrode portion 7A is formed thicker than the thickness of the thin
portion corresponding to the straddle region 7C, so the resistance value of the lower electrode 7
can be further reduced. Also in the configuration as shown in FIGS. 7 and 8, the width of the
region belonging to the inner electrode region in each crossover region 7C corresponds to the
correspondence between the corresponding side edge of the inner electrode region in the inner
electrode region and the main electrode portion 7A. The width may be set shorter than the width
of the area between the side edges. In such a case, the thickness of the region between the main
electrode portion 7A and the straddle region 7C in the inner electrode region may be formed as
thin as the straddle region 7C or the thickness of the main electrode portion 7A. It may be
formed thick.
[0057]
14-04-2019
20
In the above-described embodiment, the entire crossing region 7C is formed to be thin. However,
it is not necessary that the entire crossing region 7C is formed thin, and only a part of the
crossing region 7C in the longitudinal direction (direction along the side edges 5c and 5d of the
top surface portion of the pressure chamber 5) It may be formed. In other words, the thickness of
only a part of the bridging region 7C in the lower electrode 7 may be formed thinner than the
thickness of the other regions. For example, as shown in FIG. 9, in the straddle region 7C, a
rectangular thin portion and a thick portion alternately having a longitudinal direction along the
side edges 5c and 5d of the top surface portion of the pressure chamber 5 along the longitudinal
direction. It may be configured to be formed. In FIG. 9, a rectangular thin portion in the straddle
region 7C is shown as a halftone dot region.
[0058]
Furthermore, the lower electrode 7 is referred to as a straddle region (hereinafter, referred to as
“first straddle region 7C”) that straddles the side edges 5c and 5d of the top surface portion of
the pressure chamber 5 in plan view. In addition to or instead of the above, a straddle region
straddling the edges 5a and 5b of the top surface portion of the pressure chamber 5 (hereinafter
referred to as "second straddle region 7C"). ) May be included. When the lower electrode 7 has
the second straddle region in addition to the first straddle region, the peripheral edges 5a to 5d
of the top surface portion of the pressure chamber 5 in the first straddle region and the second
straddle region The thickness of at least a part in the direction along is formed thin. When lower
electrode 7 has a second straddle region instead of the first straddle region, at least the direction
along edges 5a and 5b of the top surface portion of pressure chamber 5 in the second straddle
region A part of the thickness is formed thin. Also in these cases, the thickness of the region
excluding the straddle region 7C in the portion (inner electrode region) of the lower electrode 7
arranged inside the top surface peripheral edge 5a to 5d of the pressure chamber 5 in plan view
is thin You may form.
[0059]
Next, a configuration example of the piezoelectric film 8 used in the ink jet print head 1 will be
described. FIG. 10 is a schematic cross-sectional view of the piezoelectric film 8. The piezoelectric
film 8 is formed in contact with the surface of the lower electrode (metal film) 7 formed on the
silicon substrate 2. More specifically, the vibrating film forming layer 10 is formed on the surface
of the silicon substrate 2, the lower electrode 7 is formed on the surface of the vibrating film
forming layer 10, and the piezoelectric film is formed on the surface of the lower electrode 7. 8
14-04-2019
21
are formed. In this embodiment, the lower electrode 7 is a Pt / Ti laminated film having a Ti film
as a lower layer and a Pt film as an upper layer. An upper electrode 9 is formed on the upper
surface of the piezoelectric film 8. In this embodiment, the upper electrode 9 is made of an Ir /
IrO 2 laminated film having an IrO 2 film as a lower layer and an Ir film as an upper layer.
[0060]
The piezoelectric film 8 includes an adhesion layer 101 formed on the surface of the lower
electrode 7, a first seed layer 102 formed on the adhesion layer 101, and a plurality of main
layers stacked on the first seed layer 102. The PZT layers 103 to 106 of the firing unit, the
second seed layer 107 formed on the surface of the PZT 106 of the main firing unit, and the
PZTs of a plurality of main firing units formed on the surface of the second seed layer 107 And
layers 108-112.
[0061]
The “PZT layer of the main firing unit” is a coating step of applying a precursor solution
containing PZT, a drying step of drying the coating film, and a pre-baking step of heating the
coating film after the drying step to gelate The PZT layer is formed by performing the main
baking step of subjecting the gelled coating film to heat treatment and sintering after the gelled
film formation step consisting of the above is performed one or more times.
That is, the PZT layer of the present fired unit is formed by the sol-gel method.
[0062]
The precursor solution contains a solvent in addition to PZT. In the application step, for example,
a precursor solution is spin-coated. The drying step is performed, for example, in a temperature
environment of 140 ° C. The drying step may be natural drying. In the pre-baking step, heat
treatment at a temperature (eg, 400 ° C.) higher than the melting point (327.5 ° C.) of lead is
performed on the coated film after the drying step. In the pre-baking step, heat treatment may be
performed at a temperature (eg, 300 ° C.) less than the melting point of lead. In this firing step,
a heat treatment at, for example, 700 ° C. is performed on the gelled coating film. The firing
process may be performed by rapid thermal annealing (RTA).
14-04-2019
22
[0063]
In the following, a PZT layer corresponding to each of one or a plurality of coating films
simultaneously sintered in the main firing step may be referred to as a “pre-baked unit PZT
layer”. The adhesion layer 101 is a layer provided to enhance the adhesion between the
piezoelectric film 8 and the lower electrode 7. In this embodiment, the adhesion layer 101 is
formed of a TiO layer. The TiO layer can be formed by, for example, a sol-gel method, a
sputtering method, or the like.
[0064]
The seed layers 102 and 107 are layers provided to improve the crystallinity and adhesion of
PZT, and are formed of, for example, a PZT seed layer made of PZT or a TiO seed layer made of
TiO. The first seed layer 102 and the second seed layer 107 may be made of the same material,
or may be made of different materials. The PZT seed layer is a gelled film comprising a coating
step of coating a precursor solution containing PZT, a drying step of drying the coating film, and
a pre-baking step of heating and gelling the coating film after the drying step. After the formation
step is performed once, the formed coating film is heat-treated and sintered to form a main
baking step. The TiO seed layer can be formed, for example, by a sol-gel method, a sputtering
method or the like.
[0065]
In the configuration example of FIG. 10, PZT layers 103 to 106 of the main firing unit of four
layers are stacked between the first seed layer 102 and the second seed layer 107, and the
second seed layer 107 is formed. The PZT layers 108 to 112 of the main firing unit of five layers
are stacked. Among the PZT layers 103 to 106 and 108 to 112 of the main baking unit, the PZT
layers 103 to 106 and 108 to 111 of the main baking units other than the PZT layer 112 of the
main baking unit of the uppermost layer In this embodiment, the gelled film forming process is
performed a plurality of times, including a coating process of coating, a drying process of drying
the coated film, and a pre-baking process of heating and gelling the coated film after the drying
process. It is formed by performing the main baking process which heat-processes and bakes the
gelatinized coating film, after being performed repeatedly. Therefore, the PZT layers 103 to 106
and 108 to 111 of the main firing units other than the PZT layer 112 of the uppermost main
firing unit include the PZT layer 100 of the temporary firing units of three layers. The thickness
of the PZT layer 100 of one temporary firing unit is 0.08 μm in this embodiment.
14-04-2019
23
[0066]
On the other hand, the PZT layer 112 of the uppermost baking unit of the main baking unit heats
and gelates the coating film after the coating step of coating the precursor solution containing
PZT, the drying step of drying the coating film, and the drying step. After the gelled film forming
process including the pre-baking process is performed once, the gelled coating film is formed by
performing a main baking process of heat treatment and sintering. Therefore, the PZT layer of
the uppermost main firing unit includes the PZT layer 100 of one temporary firing unit.
[0067]
As the number of layers of the coating film simultaneously sintered by the main baking step
increases, that is, as the number of layers of the PZT layer of the temporary baking unit
contained in the PZT layer of the main baking unit increases, the total number of main baking
steps decreases. So, the production efficiency will be high. However, as the number of layers of
the coating film to be sintered simultaneously in the main baking step increases, the thickness of
the entire coating film to be sintered in the main baking step becomes thicker. Irregularities on
the surface (upper surface) of the PZT layer become large.
[0068]
In the configuration example of FIG. 10, while the PZT layers 103 to 106 and 108 to 111 of the
main firing units other than the PZT layer 112 of the main firing unit of the uppermost layer are
three PZT layers of temporary firing units. The PZT layer of the temporary firing unit contained
in the PZT layer 112 of the main firing unit of the uppermost layer is one layer. Therefore, the
unevenness of the surface of the PZT layer 112 of the uppermost main baking unit is smaller
than the unevenness of the surface of the PZT layer 112 of the other main baking unit. As a
result, the unevenness of the surface of the PZT layer 112 of the uppermost main baking unit is
higher than the unevenness of the interface between the PZT layer 112 of the main baking unit
and the PZT layer 112 of the second main baking unit adjacent thereto. small. Thereby, the
piezoelectric film 8 having a smooth top surface is obtained. Thereby, the adhesion between the
piezoelectric film 8 and the upper electrode 9 can be improved. Moreover, since the parallelism
between the lower electrode 7 and the upper electrode 9 can be improved, the piezoelectric
performance of the piezoelectric film can be improved.
14-04-2019
24
[0069]
Further, in the configuration example of FIG. 10, the piezoelectric film 8 has the PZT layer 103 of
the lowermost main firing unit in addition to the first seed layer 102 existing on the lower
surface side of the lowermost PZT layer 103 of the main baking unit. And a second seed layer
107 interposed between the PZT layers 106 and 108 of adjacent main firing units at an
intermediate position of the PZT layer 112 of the main firing unit of the top layer. Therefore, as
compared with the case where the seed layer is provided only on the lower surface side of the
bottom main firing unit PZT layer 103, the crystal orientations of the PZT layers 103 to 106 and
108 to 112 can be easily aligned. Become. Thereby, the piezoelectric film 8 having stable
piezoelectric characteristics is obtained.
[0070]
Such a piezoelectric film 8 is formed as follows. First, the adhesion layer 101 is formed on the
lower electrode 7, and the first seed layer 102 is formed on the adhesion layer 101. Next, the
PZT layer 103 of the lowermost main firing unit is formed on the first seed layer 102, and the
PZT layers 104 to 106 of the second to fourth main firing units are sequentially formed thereon.
Form. Next, a second seed layer 107 is formed on the fourth main firing unit PZT layer 106.
Next, the PZT layer 108 of the fifth main firing unit is formed on the second seed layer 107, and
the PZT layers 109 to 111 of the sixth to eighth main firing units are formed thereon. Are formed
sequentially. Finally, the PZT layer 112 of the uppermost firing unit (ninth layer) of the main
firing unit is formed on the PZT layer 111 of the eighth main firing unit.
[0071]
An embodiment of the piezoelectric film 8 will be described. First Embodiment In the first
embodiment, the first seed layer 102 and the second seed layer 107 are composed of a PZT seed
layer made of PZT. In the first embodiment, since the first seed layer 102 and the second seed
layer 107 are made of the same material, the manufacturing efficiency can be improved. Second
Embodiment In the second embodiment, the first seed layer 102 and the second seed layer 107
are composed of a TiO seed layer made of TiO. In the second embodiment, since the first seed
layer 102 and the second seed layer 107 are made of the same material, the manufacturing
efficiency can be improved. Third Embodiment In the third embodiment, the first seed layer 102
14-04-2019
25
is composed of a TiO seed layer composed of TiO, and the second seed layer 107 is composed of
a PZT seed layer composed of PZT. Fourth Embodiment In the fourth embodiment, the first seed
layer 102 is made of a PZT seed layer made of PZT, and the second seed layer 107 is made of a
TiO seed layer made of TiO.
[0072]
In the configuration example of FIG. 10, the PZT layers of temporary firing units included in the
PZT layers 103 to 106 and 108 to 111 of main firing units other than the PZT layer 112 of main
firing unit of the uppermost layer are three layers. However, it is only necessary that the number
of PZT layers of the temporary firing unit contained in the PZT layer 112 of the second main
firing unit from the top adjacent to the PZT layer 111 of the uppermost main firing unit be two
or more layers. The number of PZT layers of the temporary firing unit contained in the PZT
layers 103 to 106 and 108 to 111 of the firing unit may be one or a plurality of layers other
than three.
[0073]
Further, the number of PZT layers of the main firing unit contained in the piezoelectric film 8 is
not limited to the number of layers in the configuration example of FIG. 10, and may be set
arbitrarily as long as it is two or more. Moreover, the thickness of the PZT layer of the temporary
firing unit is not limited to the thickness of the configuration example of FIG. Further, in the
configuration example of FIG. 10, the second seed layer 107 is provided only at one
predetermined intermediate position between the PZT layer 103 of the lower main firing unit
and the PZT layer 112 of the upper main firing unit. Although provided, the second seed layer
may be provided at a plurality of different intermediate positions.
[0074]
In the above embodiments, the present invention is applied to an ink jet print head, but the
present invention relates to a microphone using a piezoelectric film, a pressure sensor, an
acceleration sensor, an angular velocity sensor, an ultrasonic sensor, a speaker, an IR sensor
(Thermal sensor) etc. can be applied. In addition, various design changes can be made within the
scope of matters described in the claims.
14-04-2019
26
[0075]
The following features can be further extracted from this specification. A1. A piezoelectric
film including PZT layers of a plurality of main firing units stacked, wherein the first seed layer
present on the lower surface side of the PZT layer of the lower main firing unit and the PZT of
the lower main firing unit A piezoelectric film comprising a second seed layer interposed
between PZT layers of two adjacent main firing units at an intermediate position between the
layer and the PZT layer of the uppermost main firing unit.
[0076]
The “PZT layer of the main firing unit” is a coating step of applying a precursor solution
containing PZT, a drying step of drying the coating film, and a pre-baking step of heating the
coating film after the drying step to gelate The PZT layer is formed by performing the main
baking step of subjecting the gelled coating film to heat treatment and sintering after the gelled
film formation step consisting of the above is performed one or more times. In this configuration,
the seed layer is provided not only on the lower surface side of the bottom main firing unit PZT
layer but also at an intermediate position between the bottom main firing unit PZT layer and the
top main firing unit PZT layer. Exists. For this reason, as compared with the piezoelectric film in
which the seed layer is formed only on the lower surface side of the bottom main PZT unit of the
main firing unit, the crystal direction of the PZT layer of each main firing unit is easily aligned.
Thus, a piezoelectric film having stable piezoelectric characteristics can be obtained.
[0077]
A2. The first seed layer and the second seed layer are made of the same material, “A1. The
piezoelectric film as described in "". In this configuration, the manufacturing efficiency of the
piezoelectric film can be improved. A3. The first seed layer and the second seed layer are
composed of a PZT seed layer made of PZT, "A2. The piezoelectric film as described in "". A4.
The first seed layer and the second seed layer are composed of a TiO seed layer made of titanium
oxide, "A2. The piezoelectric film as described in "".
[0078]
14-04-2019
27
A5. The first seed layer and the second seed layer are made of different materials, “A1. The
piezoelectric film as described in "". A6. The first seed layer is composed of a TiO seed layer
composed of titanium oxide, and the second seed layer is composed of a PZT seed layer
composed of PZT, "A5. The piezoelectric film as described in "".
[0079]
A7. The first seed layer is composed of a PZT seed layer composed of PZT, and the second
seed layer is composed of a TiO seed layer composed of titanium oxide, "A5. The piezoelectric
film as described in "". A8. The PZT seed layer is a gelation comprising a coating step of
coating a precursor solution containing PZT, a drying step of drying the coating film, and a prebaking step of heating the gelation of the coating film after the drying step. After the film
forming step is performed once, the gelled coating film is heat-treated and sintered to perform a
main baking step, thereby forming "A3.", "A6. 」または「A7. The piezoelectric film as
described in any one of-.
[0080]
A9. A lower electrode and “A1. Formed on the lower electrode”. 」∼「A8. A
piezoelectric element comprising: the piezoelectric film according to any of the above and an
upper electrode formed on the piezoelectric film. In this configuration, a piezoelectric element
having stable piezoelectric characteristics can be obtained. A10. A cavity, a vibrating
membrane disposed above the cavity and defining a top surface portion of the cavity, and “A9.
Formed on the vibrating membrane. An inkjet print head, comprising: the piezoelectric element
according to claim 1; In this configuration, by using a piezoelectric element having stable
piezoelectric characteristics, it is possible to provide an ink jet print head capable of realizing
stable driving characteristics.
[0081]
Further, the following features can be further extracted from this specification. B1. A
piezoelectric film including PZT layers of a plurality of main firing units stacked, wherein the
unevenness of the surface of the PZT layer of the top main firing unit is adjacent to the PZT layer
of the top main firing unit and the PZT layer of the top layer. The piezoelectric film smaller than
14-04-2019
28
the unevenness of the interface between the second main fired unit and the PZT layer. The “PZT
layer of the main firing unit” is a coating step of applying a precursor solution containing PZT, a
drying step of drying the coating film, and a pre-baking step of heating the coating film after the
drying step to gelate The PZT layer is formed by performing the main baking step of subjecting
the gelled coating film to heat treatment and sintering after the gelled film formation step
consisting of the above is performed one or more times. According to this configuration, a
piezoelectric film having a smooth top surface can be obtained.
[0082]
B2. The thickness of the PZT layer of the top main firing unit is thinner than the thickness of
the PZT layer of the second top main firing unit, “B1. The piezoelectric film as described in "".
According to this configuration, a piezoelectric film having a smooth top surface can be obtained.
B3. The PZT layer of the main baking unit of the uppermost layer applies a coating process of
applying a precursor solution containing PZT, a drying process of drying the coating film, and a
pre-baking of heating the coating film after the drying process. After the gelled film forming step
including the step is performed once, the gelled coated film is heat-treated and sintered to
perform a main baking step, which is formed, "B1. 」または「B2. The piezoelectric film as
described in "".
[0083]
In the PZT layer of the main firing unit formed by performing the main firing step after
performing the gelled film forming step consisting of the application step, the drying step, and
the temporary firing step once, the coating step, the drying step, and the temporary As compared
with the PZT layer of the main firing unit formed by performing the main firing step after the
gelled film forming step including the firing step is performed a plurality of times, the
unevenness on the surface thereof becomes smaller. Therefore, in this configuration, the
unevenness of the surface of the PZT layer of the main firing unit of the uppermost layer is
reduced. Thereby, a piezoelectric film having a smooth top surface is obtained.
[0084]
B4. The PZT layer of the second main firing unit from above is subjected to the main firing
step after the gelled film forming step including the application step, the drying step, and the
14-04-2019
29
temporary firing step is performed a plurality of times. Formed by “B3. The piezoelectric film as
described in "". B5. The PZT layer of each main firing unit other than the PZT layer of the top
main layer main firing unit is subjected to the gelled film formation step including the application
step, the drying step, and the temporary firing step a plurality of times, B3. It is formed by
performing the main firing step. The piezoelectric film as described in "".
[0085]
B6. B1. Including a first seed layer present on the lower surface side of the PZT layer of the
lowermost main firing unit; 」∼「B5. The piezoelectric film as described in any one of-. In
this configuration, the crystal orientations of the PZT layers of the main firing units are easily
aligned. Thus, a piezoelectric film having stable piezoelectric characteristics can be obtained.
B7. An intermediate position between the PZT layer of the lowermost main firing unit and the
PZT layer of the uppermost main layer, including a second seed layer interposed between the
PZT layers of two adjacent main firing units. "B6. The piezoelectric film as described in "". In this
configuration, the crystal orientations of the PZT layers of the main firing units are more easily
aligned. Thereby, a piezoelectric film having more stable piezoelectric characteristics can be
obtained.
[0086]
B8. "B7. The first seed layer and the second seed layer are made of the same material." The
piezoelectric film as described in "". In this configuration, the manufacturing efficiency of the
piezoelectric film can be improved. B9. B8. The first seed layer and the second seed layer are
each composed of a PZT seed layer made of PZT. The piezoelectric film as described in "".
B10. B8. The first seed layer and the second seed layer are composed of a TiO seed layer
made of titanium oxide. The piezoelectric film as described in "".
[0087]
B11. “B7. The first seed layer and the second seed layer are made of different materials.
The piezoelectric film as described in "". B12. The first seed layer is composed of a TiO seed
layer composed of titanium oxide, and the second seed layer is composed of a PZT seed layer
composed of PZT, "B11. The piezoelectric film as described in "".
14-04-2019
30
[0088]
B13. The first seed layer is composed of a PZT seed layer composed of PZT, and the second
seed layer is composed of a TiO seed layer composed of titanium oxide, "B11. The piezoelectric
film as described in "". B14. The PZT seed layer is a gelation comprising a coating step of
coating a precursor solution containing PZT, a drying step of drying the coating film, and a prebaking step of heating the gelation of the coating film after the drying step. After the film
forming step is performed once, the gelled coating film is heat-treated and sintered to perform
the main baking step, thereby forming “B9.”, “B12. 」または「B13. The piezoelectric film
as described in any one of-.
[0089]
B15. A lower electrode and “B1. Formed on the lower electrode”. 」∼「B14. A
piezoelectric element comprising: the piezoelectric film according to any of the above and an
upper electrode formed on the piezoelectric film. In this configuration, since the uppermost
surface of the piezoelectric film is smooth, the adhesion between the piezoelectric film and the
upper electrode can be improved. Moreover, since the parallelism between the lower electrode
and the upper electrode can be improved, the piezoelectric performance of the piezoelectric film
can be improved. Thereby, the piezoelectric element excellent in piezoelectric performance can
be provided.
[0090]
B16. A cavity, a vibrating membrane disposed on the cavity and defining a top surface
portion of the cavity, and “B15. An inkjet print head, comprising: the piezoelectric element
according to claim 1; In this configuration, it is possible to provide an inkjet print head with high
ejection performance by using a piezoelectric element with excellent piezoelectric performance.
[0091]
DESCRIPTION OF SYMBOLS 1 inkjet print head 2 silicon substrate 3a discharge port 4 ink supply
path 5 piezoelectric chamber (cavity) 5a, 5b both ends 5c of top surface of piezoelectric chamber
5d, 5d both edges of top surface of piezoelectric chamber 6 piezoelectric elements 6a, 6b
piezoelectric element Both end edges 6c, 6d Both side edges 7 of the piezoelectric element Lower
14-04-2019
31
electrode 7A Main electrode portion 7B Extension 7C Crossing region 8 Piezoelectric film 9
Upper electrode 10 Vibrating film forming layer 10A Vibrating film 10Aa, 10Ab Adhesion film
103 to 106, 108 to 112 PZT layer 102 of the fired unit first seed layer 107 second seed layer
14-04-2019
32
Документ
Категория
Без категории
Просмотров
0
Размер файла
50 Кб
Теги
description, jp2015193222
1/--страниц
Пожаловаться на содержимое документа