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DESCRIPTION JP2018093380

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DESCRIPTION JP2018093380
Method of manufacturing an ultrasonic device capable of improving resolution of an image
generated based on ultrasonic waves by reducing variation in thickness of an acoustic matching
layer, method of manufacturing an ultrasonic probe, electron A method of manufacturing an
apparatus and a method of manufacturing an ultrasonic imaging apparatus are provided. A
piezoelectric element (17) including a first electrode (14), a piezoelectric layer (15) and a second
electrode (16) is formed on a vibrating plate (50) of a substrate (11). And an acoustic matching
layer 30 for propagating an ultrasonic wave generated by driving the piezoelectric element 17 on
any of the surface of the substrate 11 on which the piezoelectric layer 15 is provided and the
surface on which the opening 18 is provided. A lens member 31 for refracting light to provide an
ultrasonic device, wherein a wall is provided around either surface of the substrate 11 and a fluid
material is injected into the wall to flow The material is hardened to form an acoustic matching
layer 30 having a flat surface, and the acoustic matching layer 30 and the lens member 31 are
joined. [Selected figure] Figure 7
Method of manufacturing ultrasonic device, method of manufacturing ultrasonic probe, method
of manufacturing electronic device, and method of manufacturing ultrasonic imaging apparatus
[0001]
The present invention relates to a method of manufacturing an ultrasonic device, a method of
manufacturing an ultrasonic probe, a method of manufacturing an electronic device, and a
method of manufacturing an ultrasonic imaging apparatus.
[0002]
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1
Conventionally, there is known an electronic device which emits ultrasonic waves from the tip of
an ultrasonic device such as a probe toward an object and detects the ultrasonic wave reflected
from the object, and this electronic device is, for example, It is used as an ultrasonic imaging
device etc. which visualizes a patient's inside and is used for a diagnosis.
For example, a piezoelectric element is used as an ultrasonic element mounted on the ultrasonic
imaging apparatus and emitting an ultrasonic wave.
[0003]
For example, in a probe having an ultrasonic sensor described in Patent Document 1, the
piezoelectric element is protected by an acoustic matching layer formed by pouring a fluid resin
into a recess in which the element array including the element is incorporated. It is done. Then,
the formed acoustic matching layer and the lens are joined to form an ultrasonic sensor.
[0004]
JP, 2013-258624, A
[0005]
However, if the lens is attached to the acoustic matching layer in a fluid state, the thickness of
the acoustic matching layer tends to vary.
Then, if the variation in thickness of the acoustic matching layer becomes large, there is a
problem that the resolution of the image generated based on the ultrasonic wave is lowered.
[0006]
The present invention is proposed in view of such circumstances, and can reduce the variation in
thickness of the acoustic matching layer to improve the resolution of the image generated based
on the ultrasonic waves. It is an object of the present invention to provide a method of
manufacturing an ultrasonic device, a method of manufacturing an ultrasonic probe, a method of
manufacturing an electronic device, and a method of manufacturing an ultrasonic imaging
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apparatus.
[0007]
The aspect of the present invention for solving the above problems provides a substrate, forming
a diaphragm on the substrate, and forming a piezoelectric element including the first electrode,
the piezoelectric layer, and the second electrode on the diaphragm. An opening is formed at a
position facing the piezoelectric element of the substrate, and the piezoelectric element is driven
on one of the surface of the substrate on which the piezoelectric layer is provided and the surface
on which the opening is provided. And a refractive member for refracting the ultrasonic wave to
propagate the ultrasonic wave generated thereby, thereby forming an ultrasonic device as an
ultrasonic device, comprising: A wall is provided, a fluid material is injected into the wall, the
fluid material is cured to form the flat surface acoustic matching layer, and the acoustic matching
layer and the refractive member are joined. Method of manufacturing an ultrasonic device.
According to this aspect, it is possible to provide an ultrasonic device capable of reducing the
variation in thickness of the acoustic matching layer and improving the resolution of an image
generated based on ultrasonic waves.
[0008]
In the method of manufacturing the ultrasonic device, at least one of the bonding surface of the
acoustic matching layer and the bonding surface of the refractive member may be subjected to
an activation treatment to bond the acoustic matching layer and the refractive member.
preferable. According to this, since it is not necessary to interpose an adhesive or the like at the
bonding interface between the acoustic matching layer and the refractive member, the variation
in the thickness of the acoustic matching layer due to the adhesive or the like is reduced, and
generation is performed based on ultrasonic waves. It is possible to provide an ultrasonic device
capable of improving the resolution of a captured image.
[0009]
Further, in the method of manufacturing an ultrasonic device, the activation treatment is
preferably either plasma treatment or ultraviolet radiation treatment. According to this, since
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only the bonding surface of the acoustic matching layer and the bonding surface of the refracting
member can be activated with certainty, the above-described effects can be obtained, and at the
same time, the components of the ultrasonic device associated with the activation process can be
obtained. Degradation can be minimized.
[0010]
Further, in the method of manufacturing the ultrasonic device, annealing may be performed after
the acoustic matching layer and the refracting member are joined. According to this, the
activation bonding at the bonding interface between the acoustic matching layer and the
refractive member can be promoted, so that the processing time can be shortened and the
manufacturing cost can be reduced.
[0011]
In the method of manufacturing the ultrasonic device, an adhesive may be applied to at least one
of the bonding surface of the acoustic matching layer and the bonding surface of the refractive
member to bond the acoustic matching layer and the refractive member. Good. According to this,
since the acoustic matching layer and the refracting member can be bonded by a simple method
without requiring a large-scale device, the processing time can be shortened and the
manufacturing cost can be reduced.
[0012]
In the method of manufacturing the ultrasonic device, the adhesive is applied onto the transfer
film, and applied to the transfer film on at least one of the bonding surface of the acoustic
matching layer and the bonding surface of the refracting member. The adhesive may be
transferred to bond the acoustic matching layer and the refractive member. According to this, it
is possible to bond the acoustic matching layer and the refraction member by a simple method.
[0013]
Further, in the method of manufacturing the ultrasonic device, after applying the adhesive having
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a first viscosity onto the transfer film, the viscosity of the adhesive having the first viscosity is set
to the first viscosity according to the first viscosity. The adjustment adhesive is adjusted to a high
second viscosity to be a adjusting adhesive, and the adjusting adhesive on the transfer film is
transferred to at least one of the joint surface of the acoustic matching layer and the joint surface
of the refracting member. The acoustic matching layer and the refracting member may be
bonded. According to this, the adhesive applied uniformly on the transfer film by using the
adhesive having the low viscosity first viscosity is transferred after being adjusted to the second
viscosity higher than the first viscosity. For this reason, since the transfer can be performed while
suppressing the variation in the thickness of the adhesive, the variation in the thickness of the
acoustic matching layer can be further reduced to improve the resolution of the image generated
based on the ultrasonic wave. It is possible to provide an ultrasonic device capable of
[0014]
Further, in the method of manufacturing an ultrasonic device, the acoustic matching layer is
preferably made of a silicone-based material. According to this, since it is possible to cure while
maintaining appropriate fluidity, it is possible to prevent the reduction of the ultrasonic wave
propagation efficiency.
[0015]
Further, in the method of manufacturing the ultrasonic device, the refractive member is
preferably made of a silicone-based material. According to this, since the same material as the
acoustic matching layer can be used, the acoustic matching layer and the refraction member can
be easily joined.
[0016]
Another aspect of the present invention for solving the above-mentioned problems lies in a
method of manufacturing an ultrasonic probe including the method of manufacturing any one of
the above-mentioned ultrasonic devices. According to this, it is possible to provide an ultrasonic
probe capable of reducing the variation in thickness of the acoustic matching layer and
improving the resolution of the image generated based on the ultrasonic wave.
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[0017]
Another aspect of the present invention for solving the above-mentioned problems lies in a
method of manufacturing an electronic device including the method of manufacturing an
ultrasonic device according to any of the above. According to this, it is possible to provide an
electronic device capable of reducing the variation in thickness of the acoustic matching layer
and improving the resolution of the image generated based on the ultrasonic wave.
[0018]
Another aspect of the present invention for solving the above-mentioned problems lies in a
method of manufacturing an ultrasonic imaging apparatus including the method of
manufacturing any one of the ultrasonic devices described above. According to this, it is possible
to provide an ultrasonic imaging apparatus capable of improving the resolution of an image
generated based on ultrasonic waves by reducing variation in thickness of the acoustic matching
layer.
[0019]
FIG. 2 is a cross-sectional view showing a configuration example of the ultrasonic device of the
first embodiment. FIG. 2 is an exploded perspective view showing a configuration example of the
ultrasonic sensor of the first embodiment. FIG. 2 is a plan view showing a configuration example
of the ultrasonic sensor of the first embodiment. AA 'line sectional drawing of FIG. The BB
'sectional view taken on the line of FIG. FIG. 7 is a cross-sectional view showing a configuration
example of an ultrasound device of Embodiment 2. FIG. 7 is a cross-sectional view along the line
B-B ′ showing an example of manufacturing the ultrasonic sensor of the second embodiment.
FIG. 7 is a cross-sectional view along the line B-B ′ showing an example of manufacturing the
ultrasonic sensor of the second embodiment. FIG. 1 is a perspective view showing an example of
an ultrasonic imaging apparatus. The front view which shows an example of an ultrasonic device.
[0020]
Hereinafter, embodiments of the present invention will be described with reference to the
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drawings. The following description shows one aspect of the present invention, and can be
arbitrarily changed without departing from the scope of the present invention. The same
reference numerals in the drawings indicate the same members, and the description will be
omitted as appropriate. Also, X, Y and Z represent three spatial axes orthogonal to one another.
In this specification, the directions along these axes are the first direction X (X direction), the
second direction Y (Y direction) and the third direction Z (Z direction) respectively, The direction
of the arrow is described as the positive (+) direction, and the direction opposite to the arrow is
described as the negative (-) direction. The X direction and the Y direction represent the in-plane
directions of the plate, layer and film, and the Z direction represents the thickness direction or
lamination direction of the plate, layer and film.
[0021]
Further, the constituent elements shown in each drawing, that is, the shape and size of each part,
the thickness of layers, relative positional relationship, repeating unit and the like may be
exaggerated when explaining the present invention. is there. Furthermore, the term "above" in
this specification does not limit that the positional relationship between components is "directly
on". For example, the expressions “the first electrode on the substrate” and “the piezoelectric
layer on the first electrode” may be used to form the second electrode between the substrate
and the first electrode or between the first electrode and the piezoelectric layer. Do not exclude
those that contain components.
[0022]
Embodiment 1 Ultrasonic Device FIG. 1 is a cross-sectional view showing an example of a
configuration of an ultrasonic device equipped with an ultrasonic sensor according to
Embodiment 1 of the present invention. In the present embodiment, an ultrasonic probe (probe)
is described as an example of an ultrasonic device. As shown, the ultrasonic probe (probe I) is
pulled out from a CAV plane type ultrasonic sensor 1, a flexible printed circuit board (FPC board
2) connected to the ultrasonic sensor 1, and a device terminal (not shown). Between the cable 3,
the relay substrate 4 connecting the FPC substrate 2 and the cable 3, the housing 5 for
protecting the ultrasonic sensor 1, the FPC substrate 2 and the relay substrate 4, the housing 5
and the ultrasonic sensor 1 It is configured to be filled with the water resistant resin 6. Although
details will be described later, the ultrasonic sensor 1 includes an ultrasonic element 10, an
acoustic matching layer 30 for propagating ultrasonic waves generated by driving the
piezoelectric element 17, and a lens member 31 which is a refractive member for bending
ultrasonic waves. And a surrounding plate 40. The probe I is not limited to the above
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configuration, and may be configured to include other elements as needed.
[0023]
The ultrasonic sensor 1 mounted on the probe I is configured to be integrated with transmission
and reception. In the ultrasonic sensor 1, transmission ultrasonic waves are transmitted through
the acoustic matching layer 30 and the lens member 31 in accordance with the repetitive
transmission cycle of the ultrasonic sensor 1. Reflected ultrasonic waves reflected from the object
to be measured are received through the acoustic matching layer 30 and the lens member 31
while the transmitted ultrasonic waves are transmitted at predetermined intervals. Information
(position, shape, etc.) on the object to be measured is detected at the device terminal of the probe
I based on the waveform signals of the transmission ultrasonic waves and the reflected ultrasonic
waves.
[0024]
According to such an ultrasonic sensor 1, as described later, it is possible to suppress variations
in the transmission and reception sensitivity and to improve the reception sensitivity. Therefore,
by mounting the ultrasonic sensor 1 on the probe I, an ultrasonic device excellent in detection
sensitivity is obtained. The ultrasonic sensor 1 is not limited to the transmission / reception
integrated type, and can be applied to a transmission only type or a reception only type. The
ultrasonic device capable of mounting the ultrasonic sensor 1 is not limited to the probe I.
[0025]
Further, the ultrasonic sensor 1 will be described later in detail, but is not limited to a type (CAV
surface type) in which the opposite side of the diaphragm 50 to the piezoelectric element 17 is
an ultrasonic wave passing region. The present invention can also be applied to a type (ACT
surface type) in which the 17 side is an ultrasonic wave passing area. The ultrasonic sensor 1 of
the CAV surface type is at a position at which the piezoelectric element 17 constituting the
ultrasonic element 10 is separated from the object to be measured as compared with the
ultrasonic sensor on the ACT surface side. Therefore, it becomes a structure which the water |
moisture content from the outside hardly reaches the piezoelectric element 17 extremely, and it
becomes the ultrasonic sensor 1 which is excellent in the electrical safety at the time of use. In
addition, when the piezoelectric element 17 is a thin film, the handling property at the time of
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manufacture can be improved, so that the ultrasonic sensor 1 can be handled easily. The details
of the ACT planar ultrasonic sensor 1 B (see FIG. 6) will be described later.
[0026]
(Ultrasonic Sensor) FIG. 2 is an exploded perspective view of the ultrasonic sensor. As shown in
FIGS. 1 and 2, the ultrasonic sensor 1 is configured to include an ultrasonic element 10, an
acoustic matching layer 30, a lens member 31 and a surrounding plate 40. Although the
enclosure plate 40 and the support member 41 are separately shown in FIG. 2, in fact, as shown
in FIG. 1, both are integrally configured. In addition, the ultrasonic sensor 1 is not limited to said
structure, You may be comprised including another element.
[0027]
The acoustic matching layer 30 is provided in the space 20 because the ultrasonic sensor 1 is
configured in the CAV plane type. By forming the acoustic matching layer 30 by filling the space
20 of the substrate 11 with a resin or the like having acoustic matching ability, it is possible that
the acoustic impedance changes rapidly between the ultrasonic element 10 and the object to be
measured. As a result, it is possible to prevent the reduction of the ultrasonic wave propagation
efficiency. As a material applicable to such an acoustic matching layer 30, for example, a fluid
material (fluid material) such as silicone oil, silicone resin, silicone-based material such as silicone
rubber, etc. may be mentioned. However, the material applicable to the acoustic matching layer
30 is not limited to the above-mentioned example, and a material according to the application of
the ultrasonic sensor 1 can be appropriately selected and used. The details of the substrate 11
and the space 20 will be described later.
[0028]
The lens member 31 is provided on the side opposite to the diaphragm 50 on the substrate 11.
The lens member 31 has a role of focusing ultrasonic waves. The lens member 31 can be
omitted, for example, in the case where the ultrasonic waves are converged by the electronic
focusing method. In addition, the lens member 31 can be replaced by a protective plate or the
like that does not have the ultrasonic wave focusing function. In the present embodiment, the
acoustic matching layer 30 also has a bonding function or a bonding function between the lens
member 31 and the substrate 11. The acoustic matching layer 30 is interposed between the lens
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member 31 and the substrate 11 to constitute the ultrasonic sensor 1. The lens member 31 can
be made of the same material as the silicone-based material of the acoustic matching layer 30
described above. However, the material applicable to the lens member 31 is not limited to the
above-mentioned example, and a material according to the application of the ultrasonic sensor 1
can be appropriately selected and used. By using the same material as the acoustic matching
layer 30, bonding or bonding between the acoustic matching layer 30 and the lens member 31
can be easily performed. The details of the diaphragm 50 will be described later.
[0029]
The surrounding plate 40 is provided on the second surface 50 b side of the diaphragm 50. A
recess (piezoelectric element holding portion 32) is formed at the center of the surrounding plate
40, and the periphery of the piezoelectric element holding portion 32 is surrounded by the edge
40a and the surface 40b of the surrounding plate 40. The piezoelectric element holding portion
32 covers an area around the ultrasonic element 10 (an area including the upper surface and the
side surface of the ultrasonic element 10). Accordingly, the upper surface of the ultrasonic
element 10 is covered with the surface 40b of the enclosure plate 40, and the side surface is
covered with the edge 40a.
[0030]
Although the length in the Z direction of the piezoelectric element holding portion 32 is 80 μm,
the length is not limited to the above value. The length of the piezoelectric element holding
portion 32 may be a value that secures a space that does not hinder the driving of the ultrasonic
element 10. Further, the piezoelectric element holding portion 32 may be filled with air or may
be filled with resin.
[0031]
The surrounding plate 40 is bonded or joined to the diaphragm 50 via the edge 40 a and a
support member 41 described later. An adhesive or the like can be used to bond or bond the
enclosure plate 40, but the invention is not limited to the above example. The thickness of the
surrounding plate 40 is 400 μm, but is not limited to the above value.
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[0032]
In the ultrasonic sensor 1, a support member 41 is provided between the surface 40 b of the
enclosure plate 40 and the second surface 50 b of the diaphragm 50 and at a position not
overlapping the ultrasonic element 10. The vibrating plate 50 can be supported by the member
41. Therefore, for example, when the lens member 31 is mounted on the ultrasonic element 10
or when the adhesion between the ultrasonic element 10 and the lens member 31 is secured, the
lens member 31 may be pressed to the acoustic matching layer 30 side. is there. Even when the
lens member 31 is not provided or when another member is provided instead of the lens member
31, the pressure on the diaphragm 50 from the side of the acoustic matching layer 30 is pressed
to secure the adhesiveness of each member. It may be attached. The ultrasonic sensor 1 is
configured to include the support member 41. Therefore, as described above, even if a
predetermined external pressure is applied to the diaphragm 50, the generation of structural
distortion can be suppressed, and high reliability can be achieved. Can be secured.
[0033]
In addition, since the support member 41 is provided at a position not overlapping the ultrasonic
element 10, excessive restraint of the piezoelectric element 17 by the support member 41 is
avoided. Therefore, the ultrasonic wave transmission efficiency and the reception efficiency are
prevented from being excessively reduced as compared with the case where the support member
41 is not provided.
[0034]
Here, when the ultrasonic element 10 is viewed from the Z direction, a position not overlapping
with the ultrasonic element 10 is sandwiched between an active portion (a first electrode 14 and
a second electrode 16 constituting the ultrasonic element 10 described later). (See Fig. 5 etc.))).
In particular, in the ultrasonic sensor 1, a support member 41 having a width narrower than a
partition wall 19 described later is provided between the ultrasonic elements 10 aligned along
the X direction. That is, in the ultrasonic sensor 1, when the ultrasonic element 10 is viewed from
the Z direction, the support member 41 is on the movable portion (the portion corresponding to
the space 20 on the second surface 50 b side of the diaphragm 50) described later. Not even
overlapping. For this reason, as compared with the case where the support member 41 is not
provided, the ultrasonic wave transmission efficiency and the reception efficiency can be reliably
prevented from being excessively reduced. The support member 41 is bonded or bonded to the
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ultrasonic element 10 by an adhesive or the like, but this method is not limited to the above
example.
[0035]
The support member 41 has a beam shape extending along the Y direction. According to this, the
diaphragm 50 can be supported in a wide range extending in the Y direction. The beam-shaped
support member 41 may extend along the X 1 direction instead of the Y direction. The beamshaped support member 41 may have one extending end separated from the edge 40 a of the
surrounding plate 40. If at least one end in the extending direction is in contact with the edge 40
a of the surrounding plate 40, it is included in the beam-shaped supporting member 41 of the
present invention.
[0036]
Of course, the support member 41 may not have a beam shape. The support member 41 may not
be linear in the extending direction. Depending on the method of manufacturing the support
member 41, the cross-sectional area of the XY plane of the support member 41 may differ
depending on the Z direction, but this aspect also supports the diaphragm 50 as long as it can
support the diaphragm 50. Included in 41.
[0037]
The central portion of the piezoelectric element holding portion 32 is relatively distant from the
edge 40 a of the surrounding plate 40. Accordingly, in the central portion C corresponding to the
central portion of the piezoelectric element holding portion 32 in the diaphragm 50, the rigidity
tends to be low when the support member 41 is not provided. Therefore, the support member 41
is provided at the central portion of the piezoelectric element holding portion 32 so as to support
the central portion C of such a diaphragm 50. This can ensure higher reliability.
[0038]
In the ultrasonic sensor 1, the number, the arrangement, the shape, and the like of the support
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members 41 can be selected variously. For example, the support member 41 may be plural. In
that case, the support members 41 are preferably provided at equal intervals in the piezoelectric
element holding portion 32. According to this, the diaphragm 50 can be supported uniformly.
Therefore, the number of diaphragms 50 is preferably an odd number of three or more. This is
because when the support members 41 are provided at equal intervals in the piezoelectric
element holding portion 32, the support member 41 at the center can be located in the vicinity of
the central place C of the diaphragm 50. For example, the number of support members 41 is well
balanced when being about three. Of course, the support member 41 may be provided only at a
portion deviated from the center C of the diaphragm 50.
[0039]
The beam-shaped support member 41 is manufactured by wet etching the surrounding plate 40.
Thus, the support member 41 is manufactured utilizing the constituent material of the
surrounding plate 40, and has the same configuration as the surrounding plate 40. Although wet
etching is inferior in processing accuracy to dry etching, for example, many regions can be cut in
a short time, and thus it is a suitable method for producing a beam-shaped support member 41.
[0040]
The ultrasonic element 10 is configured to include a substrate 11, a diaphragm 50 and a
piezoelectric element 17. The ultrasonic element 10 is not limited to the above configuration, and
may be configured to include other elements.
[0041]
A plurality of partition walls 19 are formed on the substrate 11. A plurality of spaces 20 (cavity)
are partitioned along the X direction and the Y direction by the plurality of partition walls 19.
The space 20 is formed to penetrate the substrate 11 in the Z direction. That is, the substrate 11
is formed with the opening 18 opened on the side of the diaphragm 50. The openings 18 (spaces
20) are formed in a two-dimensional shape, that is, a plurality in the X direction and a plurality in
the Y direction. The arrangement and shape of the openings 18 (spaces 20) can be variously
modified. For example, a plurality of openings 18 (spaces 20) may be formed in a onedimensional shape, that is, along one of the X direction and the Y direction. In addition, the
opening 18 (space 20) may be formed in a square shape (the ratio of the length between the X
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direction and the Y direction is 1: 1) when the ultrasonic element 10 is viewed from the Z
direction. Or rectangular (the ratio of the length in the X direction to the Y direction is other than
1: 1).
[0042]
The substrate 11 may be, for example, a silicon (Si) single crystal substrate, but is not limited
thereto. For example, an SOI substrate, a glass substrate, or the like may be used.
[0043]
The diaphragm 50 is provided on the substrate 11 so as to close the opening 18 (the space 20),
and the elastic film 12 formed on the substrate 11 and the insulator film 13 formed on the
elastic film 12. It is composed of and. Hereinafter, the surface on the substrate 11 side of the
diaphragm 50 is referred to as a first surface 50 a, and the surface facing the first surface 50 a is
referred to as a second surface 50 b. In this case, in the diaphragm 50, the elastic film 12
constitutes a first surface 50a, and the insulator film 13 constitutes a second surface 50b.
[0044]
In the present embodiment, the diaphragm 50 is formed of the elastic film 12 made of silicon
dioxide (SiO 2) or the like and the insulator film 13 made of zirconium oxide (ZrO 2) or the like,
but the present invention is not limited to this. For example, either one of the elastic film 12 and
the insulator film 13 may be used, or another film may be used. Alternatively, without providing
the diaphragm 50, only the first electrode 14 described later may function as a diaphragm. When
the first electrode 14 is provided directly on the substrate 11, it is preferable to protect the first
electrode 14 with an insulating protective film or the like. The elastic film 12 may not be a
separate member from the substrate 11. A portion of the substrate 11 may be processed to be
thin and used as the elastic film 12.
[0045]
Here, on the second surface 50b side of the diaphragm 50, a portion corresponding to the space
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20 is referred to as a movable portion. The movable portion is a portion where vibration occurs
due to displacement of the piezoelectric element 17. For example, when a voltage is applied to
the piezoelectric element 17, vibration occurs in the movable portion. Due to this vibration,
pressure fluctuation occurs in the acoustic matching layer 30 which is the medium in the space
20, and in response to this pressure fluctuation, the ultrasonic sensor 1 transmits the
transmission ultrasonic wave or receives the reception ultrasonic wave.
[0046]
The diaphragm 50 has a deflection in which a region (movable portion) corresponding to the
space 20 is convex (that is, upward convex) on the opposite side to the space 20 when no voltage
is applied to the piezoelectric element 17. There is. The piezoelectric element 17 is configured to
be the diaphragm 50 having such a deflection. In the present specification, being convex on the
opposite side (the + Z direction side) to the space 20 is expressed by “upper convex”.
Moreover, being convex on the space 20 side (−Z direction side) is represented by “down
convex”. The configuration in the vicinity of the piezoelectric element 17 differs depending on
the type of the ultrasonic sensor 1, but any type of ultrasonic sensor 1 may be provided as long
as the piezoelectric element 17 is provided on the side of the diaphragm 50 facing the space 20.
However, as mentioned above, it is interpreted as "upper convex" and "lower convex".
[0047]
3 is a plan view showing a configuration example of the ultrasonic sensor, FIG. 4 is a crosssectional view taken along the line AA 'in FIG. 3, and FIG. 5 is a cross-sectional view taken along
the line BB'. In each of these drawings, the ultrasonic waves formed in a rectangular shape (the
ratio of the length between the X direction and the Y direction is 1: 2) when the opening 18
(space 20) is viewed from the Z direction The sensor 1 is illustrated. The ultrasonic sensor 1 of
the same shape is also applied to FIGS. 6 and 7 to be described later.
[0048]
As illustrated, the piezoelectric element 17 is provided on the diaphragm 50 made of the elastic
film 12 and the insulator film 13, and is provided at a position facing the opening 18 (space 20)
of the diaphragm 50. . The piezoelectric element 17 includes the first electrode 14, the
piezoelectric layer 15, and the second electrode 16. An opening 18 (space 20) is formed in a
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region corresponding to the piezoelectric element 17, and is separated by the partition wall 19. A
portion of the piezoelectric element 17 where the first electrode 14 and the second electrode 16
overlap in the Z direction is referred to as an active portion. The active portion is a region driven
by application of a voltage by the selected first electrode 14 and second electrode 16 and is
present in the above-described movable portion.
[0049]
The piezoelectric element 17 is a portion including the first electrode 14, the piezoelectric layer
15, and the second electrode 16, and is in the region inside the opening 18 when the
piezoelectric element 17 is viewed from the Z direction. That is, both the X and Y directions of
the piezoelectric element 17 are shorter than the opening 18. However, the present invention
also includes the case where the X direction of the piezoelectric element 17 is longer than the
opening 18 or the case where the Y direction of the piezoelectric element 17 is longer than the
opening 18.
[0050]
Although not shown, another layer may be provided between the piezoelectric element 17 and
the diaphragm 50. For example, an adhesion layer may be provided between the piezoelectric
element 17 and the diaphragm 50 to improve the adhesion. Such an adhesion layer can be
formed of, for example, a titanium oxide (TIOx) layer, a titanium (Ti) layer, a silicon nitride (SiN)
layer, or the like.
[0051]
Here, in the present embodiment, the piezoelectric element 17 and the vibration plate 50
including the elastic film 12 and the insulator film 13 are collectively referred to as an actuator
device. In this actuator device, the first electrode 14 and the second electrode 16 constituting the
piezoelectric element 17 are electrically connected to a drive circuit (not shown), and from the
drive circuit to the first electrode 14 and the second electrode 16. When an electrical signal
(drive signal) is input, a voltage is applied to the piezoelectric element 17, polarization occurs in
the piezoelectric layer 15, and the piezoelectric element 17 and the diaphragm 50 are displaced.
In addition, when the piezoelectric element 17 is displaced, polarization occurs in the
piezoelectric layer 15 to generate surface charge. The surface charge is detected as a voltage by
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the drive circuit.
[0052]
The ultrasonic sensor 1 is configured to be integrated with transmission and reception, but the
piezoelectric element 17 can be applied to any type such as a transmission only type, a reception
only type, an integrated transmission and reception type, a CAV type, an ACT type, and a
transmission only type. It can be designed to have high detection sensitivity depending on the
type, reception only type, transmission / reception integrated type, etc.
[0053]
The piezoelectric layer 15 constituting the piezoelectric element 17 is formed by patterning for
each space 20 (opening 18).
The piezoelectric layer 15 has an electromechanical conversion ability, and is a thin film having a
thickness of 3 μm or less, preferably 0.3 μm or more and 1.5 μm or less. However, it is not
limited to this film thickness. Another layer may be provided between the first electrode 14 and
the piezoelectric layer 15. For example, an orientation control layer (seed layer) for controlling
the piezoelectric layer 15 to a predetermined orientation may be provided between the first
electrode 14 and the piezoelectric layer 15. For such an orientation control layer, for example,
the same material as that of the piezoelectric layer 15 described later can be appropriately
selected.
[0054]
The piezoelectric layer 15 only needs to have an electromechanical conversion ability, and the
constituent material can be appropriately selected as needed. The piezoelectric layer 15 can
typically use a complex oxide (perovskite complex oxide) having a perovskite structure of lead
zirconate titanate (PZT). According to this, the displacement amount of the piezoelectric element
17 can be easily secured. In addition to this, a PMN-PT-based or PMN-PZT-based multicomponent complex oxide containing lead (Pb), magnesium (Mg), niobium (Nb) and Ti can be
applied.
[0055]
14-04-2019
17
The piezoelectric layer 15 may be made of a lead-free material containing no lead, such as a BFObased composite oxide containing bismuth (Bi) and iron (Fe), BF containing Bi, barium (Ba), Fe
and Ti. -BT-based complex oxide, Bi, Fe (iron), manganese (Mn), Ba and Ti-containing BFM-BTbased complex oxide, potassium (K), sodium (Na) and Nb-containing KNN system Perovskite type
complex oxides such as complex oxides of the above can also be used. According to this, it is
possible to realize the ultrasonic element 10 using a non-lead material having a small load on the
environment.
[0056]
The piezoelectric layer 15 is not limited to the above-described example, and may include other
elements (additional elements). For example, Mn, lithium (Li), Ba, calcium (Ca), strontium (Sr),
zirconium (Zr), titanium (Ti), tantalum (Ta), antimony (Sb), Fe, cobalt (Co), silver (Ag), Mg, zinc
(Zn), copper (Cu), lanthanum It may contain (La), samarium (Sm), cesium (Ce), aluminum (Al) or
the like. Among these additive elements, it is preferable to further include Mn. According to this,
the leak current can be easily suppressed, and for example, the highly reliable ultrasound
element 10 can be realized as a lead-free material. Also in the case of the piezoelectric layer 15
containing such an additive element, it is preferable that the complex oxide be configured to have
a perovskite structure.
[0057]
The perovskite type complex oxide is represented, for example, by a general formula ABO3. In
this case, the A site has 12 coordinated oxygen (O) atoms, and the B site has 6 coordinated O
atoms to form an octahedron (octahedron). In addition, as long as the perovskite type complex
oxide can have a perovskite structure, not only inevitable compositional deviation of
stoichiometry due to lattice mismatch, oxygen deficiency or excess, etc. but also partial
substitution of elements, etc. are permitted. These are included in the perovskite-type composite
oxide of the present embodiment.
[0058]
For example, the composition formula of the BF-BT-based composite oxide is represented as (Bi,
14-04-2019
18
Ba) (Fe, Ti) O3, and Bi and Ba are located at the A site, and Fe and Ti are located at the B site.
There is. A typical composition is expressed as a mixed crystal of bismuth ferrate and barium
titanate. Such mixed crystal refers to an X-ray diffraction pattern in which bismuth ferrate or
barium titanate can not be detected alone. However, unless otherwise noted, the BF-BT composite
oxide also includes a composition out of the mixed crystal composition.
[0059]
In addition, in the BF-BT complex oxide, Bi at the A site may be replaced with an additive element
such as Li, Sm, or Ce, and Fe at the B site may be replaced by an additive element such as Al or
Co. You may do it. According to this, it becomes easy to diversify the configuration and functions
by improving various characteristics.
[0060]
Usually, in the ultrasonic sensor, the ultrasonic elements are two-dimensionally arranged in the X
direction and in the Y direction orthogonal thereto, and the X direction is a scanning direction
and the Y direction is a slicing direction. In the configuration example of the present
embodiment, sixteen ultrasonic elements 10 are arranged in parallel in the Y direction which is a
slice direction, and 64 ultrasonic elements 10 are arranged in parallel in an X direction which is
a scanning direction. However, FIGS. 3 and 4 show only a part of each. In such an ultrasonic
sensor 1, while scanning in the scan direction (X direction), driving in each row extending in the
slice direction (Y direction), that is, transmission and reception of ultrasonic waves, sensing in the
slice direction Information can be acquired continuously in the scan direction.
[0061]
Also, in general, when driving a piezoelectric element, one of the electrodes is used as a common
electrode, and the other electrode is used as an individual electrode. For example, in the case
where the Y direction is one column, the ultrasonic elements 10 arranged in a plurality of
columns in the X direction are grouped, and the scanning is performed in the X direction by
driving each group. The distinction that one is a common electrode and the other is an individual
electrode is not realistic. In any case, when the ultrasonic elements are arranged twodimensionally in parallel, the first electrode constituting the piezoelectric element is provided so
as to extend in one direction, and the second electrode is made orthogonal to the one direction.
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In general, driving of the piezoelectric element is performed group by group by providing a
direction and applying a voltage between the common electrode and the common signal
electrode.
[0062]
In the present embodiment, the arrangement of the electrodes of the ultrasonic sensor 1 is not
particularly limited. For example, with respect to the first electrode 14, the rows extending in the
Y direction may be bundled and shared for each of a plurality of rows, or this may be temporarily
set as one channel, and a plurality of the channels may be provided along the X direction. In this
case, the first electrodes 14 are made common to each of a plurality of columns, and can be
driven per channel of a plurality of columns. Generally, a common electrode is called a common
electrode (also called common electrode (COM)), and a common electrode for each group is
called a signal electrode (also called signal electrode (SIG)). .
[0063]
For example, the second electrodes 16 may be provided continuously in a line along the X
direction, and may be provided in a plurality of lines along the Y direction. In such a
configuration, if the second electrodes 16 are made common for each column to simultaneously
drive all the piezoelectric elements 17 in one channel and drive each channel sequentially, onedimensional data along the X direction You can get In addition, if the second electrode 16 is
made common to each row or each row, and the piezoelectric elements 17 in one channel are
sequentially driven for each group and each channel is driven sequentially, two-dimensional data
in the XY directions can be obtained. .
[0064]
The ultrasonic sensor 1 is provided with an external connection terminal (not shown) at one end
or both ends in the X direction or the Y direction. In the present embodiment, the first electrode
14 is a signal electrode, and the second electrode 16 is a common electrode. However, in order
for the second electrode 16 to be a signal electrode and the first electrode 14 to be a common
electrode, The ultrasonic sensors 1 may be configured to be respectively disposed.
14-04-2019
20
[0065]
The material of the first electrode 14 and the second electrode 16 constituting the piezoelectric
element 17 may be any electrode material which can maintain conductivity without being
oxidized when the piezoelectric element 17 is formed. Such materials include, for example,
platinum (Pt), iridium (Ir), gold (Au), Al, Cu, Ti, Ag, metallic materials such as stainless steel,
indium tin oxide (ITO), fluorine-doped oxide Tin oxide-based conductive materials such as tin (FT
O), zinc oxide-based conductive materials, oxide conductive materials such as strontium
ruthenate (Sr RuO3), lanthanum nickelate (LaNiO3), element-doped strontium titanate,
conductive polymers, etc. Can be used. However, the material is not limited to the above. As the
electrode material, any of the above materials may be used alone, or a laminate obtained by
layering a plurality of materials may be used. The material of the first electrode 14 and the
material of the second electrode 16 may be the same or different.
[0066]
Second Embodiment Ultrasonic Device FIG. 6 is a cross-sectional view showing a configuration
example of an ultrasonic device equipped with an ultrasonic sensor according to a second
embodiment of the present invention. In the present embodiment, an ultrasonic probe (probe) is
described as an example of an ultrasonic device. As illustrated, the configuration is the same as
that of the ultrasonic sensor 1 of the first embodiment except that the ACT planar ultrasonic
sensor 1B is provided and the probe IB is configured. Therefore, the description of the same
components as those of the ultrasonic sensor 1 will be appropriately omitted.
[0067]
In the ACT planar ultrasonic sensor 1 B, the acoustic matching layer 30 is provided around the
piezoelectric element 17. According to this, the piezoelectric element 17 is protected by the
acoustic matching layer 30. In addition, since the resin or the like having acoustic matching
ability such as the above-mentioned silicone-based material (hereinafter simply referred to as
“resin”), which constitutes the acoustic matching layer 30, is a soft material, the vibration
characteristic of the ultrasonic sensor 1B is deteriorated. Can be suppressed. Then, the
diaphragm 50 has a deflection in which the region corresponding to the space 20 is convex
upward on the acoustic matching layer 30 side in a state where a voltage is not applied to the
piezoelectric element 17. In the ACT surface type ultrasonic sensor 1B, the space 20 is an air
layer.
14-04-2019
21
[0068]
By applying a voltage to the piezoelectric element 17 and displacing the piezoelectric element 17
and the diaphragm 50, pressure fluctuation occurs in the medium (air layer) in the space 20,
whereby transmission ultrasonic waves are transmitted. In addition, when pressure fluctuation
occurs in the medium in the space by receiving the reflected ultrasonic waves, the piezoelectric
element 17 and the diaphragm 50 are displaced, whereby a voltage is obtained from the
piezoelectric element 17.
[0069]
(Method of Manufacturing Ultrasonic Device) Next, a method of manufacturing the ultrasonic
sensor 1B will be described with reference to FIGS. 6 and 7 are cross-sectional views along the
line B-B 'showing an example of a method of manufacturing an ultrasonic sensor.
[0070]
First, as shown in FIG. 4 and FIG. 5, a silicon substrate is prepared as the substrate 11. Next, the
substrate 11 is thermally oxidized to form an elastic film 12 made of silicon dioxide (SiO 2) on its
surface. Further, a zirconium film is formed on the elastic film 12 by a sputtering method, a
vapor deposition method or the like, and the zirconium film is thermally oxidized to obtain an
insulator film 13 made of zirconium oxide (ZrO 2). Thus, on the substrate 11, the diaphragm 50
composed of the elastic film 12 and the insulator film 13 is formed.
[0071]
Next, the first electrode 14 is formed on the insulator film 13 of the diaphragm 50. The first
electrode 14 can be formed, for example, by a vapor phase method such as sputtering, vacuum
evaporation (PVD), laser ablation, a liquid phase method such as spin coating, or the like. Next,
the first electrode 14 is patterned. The patterning of the first electrode 14 can be performed by,
for example, dry etching such as reactive ion etching (RIE) or ion milling, or wet etching using an
etching solution. The shape in the patterning of the first electrode 14 is not particularly limited.
14-04-2019
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[0072]
Next, the piezoelectric layer 15 is formed. The method of forming the piezoelectric layer 15 is
not limited. For example, a solution (precursor solution) containing a metal complex is applied
and dried, and then fired at a high temperature to obtain a metal oxide, such as a MOD (MetalOrganic Decomposition) method or a chemical solution method such as a sol-gel method. (Wet
method) can be used. In addition, laser ablation, sputtering, pulsed laser deposition (PLD),
chemical vapor deposition (CVD), aerosol deposition, etc., vapor phase method, liquid phase
method, or solid phase method. The piezoelectric layer 15 can be manufactured.
[0073]
For example, the piezoelectric layer 15 formed by a wet method will be described in detail later,
but a step of applying a precursor solution to form a precursor film (coating step), a step of
drying a precursor film (drying step) A piezoelectric film (not shown) formed by a series of steps
up to the step of heating and degreasing the dried precursor film (degreasing step) and the step
of firing the degreased precursor film (baking step) There is more than one. That is, the
piezoelectric layer 15 is formed by repeating a series of processes from the coating process to
the baking process a plurality of times. In the above-described series of steps, the firing step may
be performed after repeating the steps from the application step to the degreasing step a
plurality of times.
[0074]
The layer or film formed by the wet method has an interface. The layer or film formed by the wet
method has a trace of coating or baking, and such a trace may be used to observe the cross
section or analyze the concentration distribution of elements in the layer (or in the film). It
becomes an “interface” that can be confirmed by “Interfacial” means strictly the boundary
between layers or films, but here means near the boundary of layers or films. When a cross
section of a layer or film formed by a wet method is observed, such an interface is a portion
having a darker color or a lighter color than the other, in the vicinity of the boundary with the
adjacent layer or film. It is confirmed. In addition, when analyzing the concentration distribution
of elements, such an interface is identified as a part where the concentration of elements is
higher than the other or a part where the concentration of the elements is lower than the other in
14-04-2019
23
the vicinity of the boundary with the next layer or film. Be done. The piezoelectric layer 15 is
formed by repeating the series of processes from the coating process to the baking process a
plurality of times, or repeating the processes from the coating process to the degreasing process
a plurality of times and then performing the baking process (a plurality of piezoelectric films
Therefore, it has a plurality of interfaces corresponding to each piezoelectric film.
[0075]
The example of the specific procedure in the case of forming the piezoelectric material layer 15
by a wet method is as follows. First, a precursor solution for forming the piezoelectric layer 15 is
prepared, which is made of a MOD solution containing a metal complex or a sol (adjustment
step). Then, the precursor solution is applied onto the patterned first electrode 14 using a spin
coating method or the like to form a precursor film (coating step). Next, the precursor film is
heated to a predetermined temperature, for example, about 130 ° C. to 250 ° C. and dried for a
predetermined time (drying step), and the dried precursor film is further heated to a
predetermined temperature, eg, 300 ° C. to 450 ° C. Degreasing is performed by heating to
about C and holding for a certain period of time (a degreasing step). Furthermore, the degreased
precursor film is heated to a higher temperature, for example, about 650 ° C. to 800 ° C., and
crystallized by being held at this temperature for a certain period of time to form a piezoelectric
film (baking step). Then, the application step, the drying step, the degreasing step and the firing
step are repeated a plurality of times to form a piezoelectric layer 15 composed of a plurality of
piezoelectric films.
[0076]
The above-mentioned precursor solution is obtained by dissolving or dispersing the metal
complex that can form the above-mentioned perovskite type complex oxide by firing in an
organic solvent. That is, the precursor solution contains, as a central metal of the metal complex,
each element capable of forming the above-mentioned perovskite complex oxide. At this time,
metal complexes containing elements other than the above elements in the precursor solution,
for example, Mn, Li, Ba, Ca, Sr, Zr, Ti, Ta, Sb, Fe, Co, Ag, Mg, Zn Metal complexes containing
additives such as Cu, La, Sm, Ce, Al, etc. may be further mixed.
[0077]
14-04-2019
24
As a metal complex containing each said element, an alkoxide, an organic acid salt, (beta) diketone complex etc. can be used, for example. In the precursor solution, the mixing ratio of
these metal complexes may be mixed so that each metal element contained in the perovskite-type
composite oxide has a desired molar ratio.
[0078]
Examples of the organic solvent used for preparation of the precursor solution include propanol,
butanol, pentanol, hexanol, octanol, ethylene glycol, propylene glycol, octane, decane,
cyclohexane, xylene, toluene, tetrahydrofuran, acetic acid, octylic acid And 2-n-butoxyethanol, noctane or the like, or a mixed solvent of these, and the like. The precursor solution may contain
an additive that stabilizes the dispersion of each metal complex. Examples of such additives
include 2-ethylhexanoic acid and the like.
[0079]
As a heating device used in the drying step, the degreasing step and the firing step, for example,
an RTA (Rapid Thermal Annealing) apparatus heated by irradiation of an infrared lamp, a hot
plate, etc. may be mentioned.
[0080]
Next, the piezoelectric layer 15 formed of a plurality of piezoelectric films is patterned.
The patterning can be performed by so-called dry etching such as reactive ion etching or ion
milling, or wet etching using an etching solution. The shape of the piezoelectric layer 15 in
patterning is not particularly limited.
[0081]
Next, the second electrode 16 is formed on the patterned piezoelectric layer 15. The second
electrode 16 can be formed by the same method as the first electrode 14. The shape of the
second electrode 16 in the patterning is not particularly limited. In the present embodiment,
before or after the second electrode 16 is formed on the piezoelectric layer 15, reheating
14-04-2019
25
treatment (post annealing) may be performed in a temperature range of about 600 ° C. to 800
° C. as necessary. . Thus, by performing post annealing, a good interface between the
piezoelectric layer 15 and the first electrode 14 or the second electrode 16 can be formed, and
the crystallinity of the piezoelectric layer 15 can be improved. it can.
[0082]
The piezoelectric element 17 provided with the first electrode 14, the piezoelectric layer 15, and
the second electrode 16 is completed by the above steps.
[0083]
Next, as shown in FIG. 7, a mask film (not shown) is formed on the surface of the substrate 11
opposite to the piezoelectric element 17 and is patterned into a predetermined shape.
Then, anisotropic etching (wet etching) using an alkaline solution such as KOH is performed on
the substrate 11 through the mask film, and the substrate 11 is partitioned by the plurality of
partition walls 19 to form a space 20. Form The space 20 is an air layer.
[0084]
Next, a wall is provided around the surface of the substrate 11 on which the piezoelectric
element 17 is formed, and a flowable material described later is injected into the wall, and the
flowable material is cured to have a thickness of 80 μm to 100 μm. The surface forms a flat
acoustic matching layer 30, and the prepared lens member 31 is attached thereto. The lens
member 31 has a thickness of 200 μm, but in order to form an ultrasonic beam, the portion
(lens portion) corresponding to the piezoelectric element 17 is formed in a curved shape, and the
thickness of the largest thickness portion is 600 μm. It has become. However, it is not limited to
these thicknesses. In the CAV planar ultrasonic sensor 1 according to the first embodiment, a
wall is provided around the opening 18 (space 20) forming surface of the substrate 11 and the
flow material is injected into the wall. In the same manner as the ultrasonic sensor 1 B, the
acoustic matching layer 30 is formed, and the lens member 31 is attached thereto.
[0085]
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Hereinafter, a method of attaching the lens member 31 to the acoustic matching layer 30 will be
described. As a mounting method, for example, a method of directly bonding the bonding surface
(the surface on the + Z direction side) of the acoustic matching layer 30 and the bonding surface
(the surface on the -Z direction side) of the lens member 31 can be mentioned. In this direct
bonding, when both bonding surfaces of the acoustic matching layer 30 and the lens member 31
are flat surfaces (smooth surfaces), in particular, when the acoustic matching layer 30 and the
lens member 31 are made of the same material. Can be done. Preferred materials include fluid
materials such as silicone-based materials such as silicone oil, silicone resin, and silicone rubber.
[0086]
Here, as a preferable attachment method, the bonding surface (surface on the + Z direction side)
of the acoustic matching layer 30 and the bonding surface (surface on the −Z direction side) of
the lens member 31 are activated (surface modification), There is a method of directly bonding
these. According to this, it is not necessary to interpose an adhesive or the like on the bonding
interface between the acoustic matching layer 30 and the lens member 31. Therefore, the
thickness variation of the acoustic matching layer 30 due to the adhesive or the like is reduced.
The resolution of the image generated based on the sound wave can be improved. Further, by not
interposing any other member such as an adhesive on these bonding interfaces, it is possible to
reduce the design error of the entire ultrasonic sensor 1B. Note that one or both of the bonding
surfaces of the acoustic matching layer 30 and the lens member 31 may be subjected to an
activation process to bond the two.
[0087]
When activating both bonding surfaces of the acoustic matching layer 30 and the lens member
31, for example, it is preferable to perform plasma (plasma) treatment and ultraviolet (UV)
irradiation treatment. However, as long as each bonding surface can be activated and both can be
bonded directly, it is not limited to these. Further, since only the bonding surfaces of the acoustic
matching layer 30 and the lens member 31 can be reliably activated, the deterioration of the
components of the ultrasonic device accompanying the activation process can be minimized.
Furthermore, the influence of the change in the layer thickness of the acoustic matching layer 30
due to curing shrinkage, coating variation, bonding variation, etc. can be reduced, and the
manufacturing cost can be reduced.
14-04-2019
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[0088]
After direct bonding of the acoustic matching layer 30 and the lens member 31, annealing may
be performed at a predetermined temperature. The temperature of the annealing treatment is not
particularly limited as long as it can promote activated bonding at these bonding interfaces, but it
should be performed at 80 ° C. to 150 ° C. in consideration of the influence on the
components of the ultrasonic device. Is preferred. According to this, activation bonding at these
bonding interfaces can be further promoted, processing time can be shortened, and
manufacturing cost can be reduced.
[0089]
Alternatively, after the bonding surfaces of the acoustic matching layer 30 and the lens member
31 are activated, an adhesive may be applied to directly bond the two. By using an adhesive, the
adhesion between the acoustic matching layer 30 and the lens member 31 can be further
strengthened. In the case of this method, in order to reduce the influence of the layer thickness
change of the acoustic matching layer 30 due to the coating variation, the bonding variation, etc.,
it is preferable to apply the adhesive to a film thickness of 1 μm to 2 μm. As the adhesive, it is
preferable to use an adhesive made of the same material as the silicone-based material and the
like constituting the acoustic matching layer 30 in consideration of the influence on the sound.
[0090]
As another example of the attachment method, either one of the bonding surface (surface on the
+ Z direction side) of the acoustic matching layer 30 and the bonding surface (surface on the −Z
direction side) of the lens member 31 or both bonding surfaces And apply an adhesive to them to
bond them. The preferable film thickness of the adhesive is as described above, but in the case of
coating on both bonding surfaces, it is preferable to apply the film thickness of 0.5 μm to 1 μm.
[0091]
In addition, the transfer surface of the acoustic matching layer 30 (the surface on the + Z
direction side) and the bonding surface of the lens member 31 (the surface on the −Z direction
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28
side) are transferred by transferring the adhesive applied to the surface of the transfer film. An
adhesive may be applied to any one surface or both bonding surfaces. The transfer film is not
particularly limited as long as the adhesive on the surface of the transfer film can be transferred
onto the acoustic matching layer 30 and / or the lens member 31.
[0092]
For film transfer, a low viscosity (first viscosity) adhesive (low viscosity adhesive) is applied to the
surface of the transfer film. Then, the viscosity of the adhesive is adjusted to a high state (β
state) by the viscosity adjusting step of adjusting the viscosity of the adhesive on the surface of
the transfer film, and the viscosity is increased (the second viscosity). The agent (adjusting
adhesive) may be transferred onto the acoustic matching layer 30 and / or onto the lens member
31. According to this, the thickness of the low-viscosity adhesive applied on the transfer film is
made uniform by the low viscosity, and then the viscosity is increased to obtain the adjusting
adhesive maintaining the uniform thickness as the acoustic matching layer 30 and / or the lens.
It can be transferred onto the member 31. As a result, the thickness variation of the acoustic
matching layer 30 can be further reduced to improve the resolution of the image generated
based on the ultrasound. In the viscosity adjustment step, by semi-curing the low viscosity
adhesive applied to the surface of the transfer film, the adjustment adhesive can be adjusted to a
high viscosity state (β state). Since the adjusting adhesive is adjusted to a viscosity that does not
flow due to its own weight or the like, it is possible to suppress the thickness variation.
[0093]
Next, as shown in FIG. 8, the unnecessary portion is cut and removed by dicing or the like, and
the surrounding plate 40 etc. is provided on the substrate 11 partitioned by the plurality of
partitions 19 by the usual method. Do. In the CAV planar ultrasonic sensor 1 according to the
first embodiment, the surrounding plate 40 and the diaphragm 50 are bonded or joined by the
usual method through the edge 40 a and the support member 41, and the ultrasonic sensor 1
and Do.
[0094]
(Other Embodiments) Although omitted in each of the embodiments described above, for
example, the ultrasonic wave transmitted from the opposite side of the diaphragm to the
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29
measurement object or the ultrasonic wave reflected from the measurement object is omitted. It
can be configured to be a passing area of (echo signal). According to this, the configuration on
the opposite side to the piezoelectric element of the diaphragm can be simplified, and a good
passing area for ultrasonic waves and the like can be secured. In addition, the electrical area such
as the electrode and the wiring and the adhesion fixation area of each member are separated
from the object to be measured, and it becomes easy to prevent the contamination and the
leakage current between them and the object to be measured. Therefore, the present invention
can be suitably applied to medical equipment which particularly dislikes contamination and
leakage current, for example, an ultrasonic diagnostic apparatus (ultrasound imaging apparatus),
a sphygmomanometer and a tonometer.
[0095]
Further, it is preferable to bond a sealing plate for sealing a region including the piezoelectric
element to the substrate. According to this, since the piezoelectric element can be physically
protected and the strength of the ultrasonic sensor is also increased, the structural stability can
be enhanced. Furthermore, when the piezoelectric element is configured as a thin film, the
handling of the ultrasonic sensor including the piezoelectric element can also be improved.
[0096]
In each of the above-described embodiments, the openings are formed for each piezoelectric
element. However, the present invention is not limited to this. The openings may be formed
corresponding to a plurality of piezoelectric elements. For example, an opening common to the
rows of piezoelectric elements arranged in parallel in the scanning direction (X direction) may be
provided, or one opening may be provided in the whole. In the case where a common opening is
provided to such a plurality of piezoelectric elements, the vibration state of the piezoelectric
elements is different, but between the piezoelectric elements from the side opposite to the
substrate of the diaphragm, The same vibration may be performed by providing a member or the
like for holding down and providing an independent opening.
[0097]
The ultrasonic sensor of the present invention can be used as various pressure sensors. For
example, in a liquid ejecting apparatus such as a printer, the present invention can also be
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30
applied as a sensor that detects the pressure of ink. In addition, the configuration of the
ultrasonic sensor of the present invention can be suitably applied to an ultrasonic motor, a
piezoelectric transformer, a vibration type dust removing device, a pressure electric transducer,
an ultrasonic transmitter, an acceleration sensor, and the like. A complete body obtained by using
the configuration of this type of ultrasonic sensor, for example, a robot equipped with the above
ultrasonic sensor, etc. is also included in the ultrasonic device.
[0098]
Here, an example of an electronic device using the above-described ultrasonic sensor will be
described. FIG. 9 is a perspective view showing a schematic configuration of an example of an
ultrasonic imaging apparatus, and FIG. 10 is a plan view showing an ultrasonic device. In the
present embodiment, an ultrasonic imaging apparatus is illustrated and described as an
electronic device, and an ultrasonic probe (probe) is illustrated and described as an ultrasonic
device.
[0099]
As shown in FIG. 9, the ultrasonic imaging apparatus 101 includes an apparatus terminal 102
and an ultrasonic probe (probe 103). The device terminal 102 and the probe 103 are connected
by a cable 104. The device terminal 102 and the probe 103 exchange electrical signals through
the cable 104. The device terminal 102 incorporates a display device (display panel 105). The
screen of the display panel 105 is exposed on the surface of the device terminal 102. At the
device terminal 102, an image is generated based on the detected ultrasonic waves transmitted
from the ultrasonic sensor 1 (see FIG. 10) of the probe 103. The imaged detection result is
displayed on the screen of the display panel 105.
[0100]
As shown in FIG. 10, the probe 103 has a housing 106. The housing 106 accommodates an
ultrasonic sensor 1 in which a plurality of ultrasonic elements 10 (see FIG. 2 and the like) are
arranged in two dimensions in the X direction and the Y direction. The ultrasonic sensor 1 is
provided such that its surface is exposed to the surface of the housing 106. The ultrasonic sensor
1 outputs an ultrasonic wave from the surface and receives a reflected wave of the ultrasonic
wave. Further, the probe 103 can be provided with a probe head 103b which can be attached to
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and detached from the probe main body 103a. At this time, the ultrasonic sensor 1 can be
incorporated into the housing 106 of the probe head 103 b.
[0101]
I, IB, 103: probe, 1, 1 B: ultrasonic sensor, 2: FPC board, 3, 104: cable, 4: relay substrate, 5, 106:
housing, 6: water-resistant resin, 10: ultrasonic wave Element 11 Substrate 12 Elastic film 13
Insulator film 14 First electrode 15 Piezoelectric layer 16 Second electrode 17 Piezoelectric
element 18 Opening 18 19 Partition wall 20 ... Space: 30: acoustic matching layer 31, 31: lens
member, 32: piezoelectric element holding portion, 40: surrounding plate, 40a: edge, 40b:
surface, 41: supporting member, 50: diaphragm, 50a: first Surface 50b: Second surface 101:
Ultrasonic wave imaging device 102: Device terminal 103a: Probe body 103b: Probe head 105:
Display panel
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