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DESCRIPTION JP2016106500

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DESCRIPTION JP2016106500
PROBLEM TO BE SOLVED: To provide an ultrasonic transducer element chip which is thin and
has a strength to withstand pressing in the thickness direction of a substrate. SOLUTION:
Openings are arranged in an array on a substrate. Ultrasonic transducer elements are provided at
the individual openings on the first side of the substrate. A reinforcing member 52 is fixed to the
second surface of the substrate opposite to the first surface. Grooves 53 are formed on the
surface of the reinforcing member 52. The grooves 53 are arranged at an interval L smaller than
the opening width S. [Selected figure] Figure 5
Ultrasonic transducer element tip and probe, electronic device and ultrasonic diagnostic
apparatus
[0001]
The present invention relates to an ultrasonic transducer element chip, a probe using the same,
an electronic device and an ultrasonic diagnostic apparatus using such a probe, and the like.
[0002]
For example, as disclosed in Patent Document 1, the ultrasonic transducer element chip includes
a substrate.
A plurality of openings are formed in the substrate. Ultrasonic transducer elements are provided
in the individual openings. The ultrasound transducer element comprises a vibrating membrane.
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The vibrating film blocks the opening from the surface of the substrate.
[0003]
JP, 2011-82624, A JP, 2011-77918, A
[0004]
When the opening is formed in the substrate, the strength of the substrate is reduced.
The strength is insufficient against the force in the thickness direction of the substrate. When the
ultrasonic transducer element chip is pressed against the subject, the ultrasonic transducer
element may be broken.
[0005]
According to at least one aspect of the present invention, it is possible to provide an ultrasonic
transducer element chip that is thin and has a strength that can withstand pressure in the
thickness direction of the substrate.
[0006]
(1) One aspect of the present invention is a substrate having openings arranged in an array, an
ultrasonic transducer element provided in each of the openings on the first surface of the
substrate, and the first surface of the substrate And a reinforcing member fixed to the second
surface of the opposite substrate to reinforce the substrate, wherein the reinforcing member is
fixed to the second surface of the substrate within the surface of the substrate. In the first
direction of the second surface of the substrate and arranged at an interval smaller than the
opening width of the first direction of the opening, and the internal space of the opening and the
external space of the substrate communicate with each other The present invention relates to an
ultrasonic transducer element chip having linear grooves.
[0007]
In such ultrasonic transducer element chips, the ultrasonic transducer elements can be formed
thin.
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The ultrasonic transducer element can be formed on a thin substrate.
Even if the reinforcing member is fixed to the substrate, the ultrasonic transducer element chip
can be formed thin. In addition, since the reinforcing member is fixed to the second surface of
the substrate, the strength of the substrate can be reinforced in the thickness direction of the
substrate. The internal space of the opening is surrounded by the substrate, the ultrasonic
transducer element and the reinforcing member. The linear groove interconnects the internal
space of the opening and the external space of the substrate. Thus, ventilation can be ensured
between the interior space of the individual openings and the outside of the interior space. If the
linear grooves are arranged at intervals smaller than the opening width in the first direction, at
least one linear groove may be formed in the opening even if a relative displacement occurs
between the substrate and the reinforcing member. It can be connected. The individual openings
can always ensure ventilation between them and the outside of the openings. The internal space
of the opening is not sealed. The internal space of the opening can easily follow ambient pressure
fluctuations. Thus, breakage of the ultrasound transducer element can be reliably avoided. If the
internal space of the opening is hermetically sealed, there is a concern that the ultrasonic
transducer element may be damaged due to pressure fluctuation.
[0008]
(2) The reinforcing member may be bonded to the partition wall of the substrate between the
openings arranged in an array at at least one bonding area. When the partition wall is joined to
the reinforcing member, the movement of the partition wall is restrained by the reinforcing
member. Therefore, vibration of the partition wall can be prevented. As a result, crosstalk
between ultrasound transducer elements can be prevented. Moreover, when the movement of the
partition wall is restrained in this way, the action of the vibration of the partition wall can be
avoided with respect to the ultrasonic vibration of the ultrasonic transducer element. The
ultrasonic transducer element provides ultrasonic vibration in a clear vibration mode. Thus, when
the vibration of the partition wall is avoided, the reduction in the amplitude of the ultrasonic
vibration can also be suppressed.
[0009]
(3) The ultrasonic transducer element chip sequentially connects the openings in one row
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sequentially through the openings in each row for each linear groove portion in plan view from
the thickness direction of the substrate, The opening at the row end can communicate with the
space outside the outline of the substrate. In this way, all the ventilation can be secured in one
row of openings.
[0010]
(4) The ultrasonic transducer element chip is replaced with one linear groove portion, and a
combination of a plurality of linear groove portions is used to form one row of the openings in
plan view from the thickness direction of the substrate. The openings can be communicated with
each other one after another sequentially, and the openings at the row end can be communicated
with the space outside the outline of the substrate. In this way, all the ventilation can be secured
in one row of openings.
[0011]
(5) The spacing of the linear groove portions in the first direction may be one third or more and
smaller than one half of the opening width of the openings in the first direction. If the linear
grooves are arranged at such intervals, two linear grooves can cross the contour of the opening.
Therefore, in the opening, even if clogging occurs in one linear groove, ventilation can be secured
between the other linear groove and the outside of the opening.
[0012]
(6) The outline of the opening is formed in a rectangular shape in plan view from the thickness
direction of the substrate, and the linear groove can cross the opening in the direction of the
short side of the rectangle. Thus, when the distance between the linear grooves in the long side
direction of the rectangle is set, a large distance can be secured between the parallel lines as
compared to the case where the distance between the linear grooves is set in the short side
direction of the rectangle. Can. Therefore, it is sufficient if the linear grooves are formed with a
small number. Processing efficiencies can be achieved.
[0013]
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(7) In plan view from the thickness direction of the substrate, the outline of the opening is
formed in a rectangular shape, and the linear groove can cross the opening in the long side
direction of the rectangular. At the short side of the rectangle, the wall of the contour of the
opening is difficult to deform due to the aspect ratio. The walls can maintain relatively high
stiffness even though the extent of overlap is narrowed due to the formation of the linear
grooves. Thus, wall vibrations can be suppressed.
[0014]
(8) The openings may be arranged at a constant pitch in the first direction and the linear grooves
may be arranged at an equal pitch in the first direction in a plan view from the thickness
direction of the substrate. In forming the linear grooves, the relative position between the linear
grooves and the reinforcing member can be freely set as long as an equal pitch is ensured. The
positioning accuracy of the reinforcing member can be relaxed when processing the reinforcing
member. The processing of the reinforcement member can be simplified.
[0015]
(9) The ultrasonic transducer element tip can be incorporated into a probe for use. The probe
may include an ultrasonic transducer element chip and a housing supporting the ultrasonic
transducer element chip.
[0016]
(10) The probe can be incorporated into an electronic device and used. Electronic equipment may
comprise a probe and processing circuitry connected to the probe for processing the output of
the ultrasound transducer element.
[0017]
(11) Similarly, the probe can be incorporated into an ultrasonic diagnostic apparatus and used.
The ultrasound diagnostic device may comprise a probe, processing circuitry connected to the
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probe to process the output of the ultrasound transducer element to generate an image, and a
display device to display the image.
[0018]
(12) The ultrasonic transducer element tip can be incorporated into a probe head and used. The
probe head may include an ultrasonic transducer element chip and a housing for supporting the
ultrasonic transducer element chip.
[0019]
(13) A specific manufacturing method can be provided for manufacturing an ultrasonic
transducer element chip. Here, the method of manufacturing an ultrasonic transducer element
chip includes reinforcing the surface having linear grooves arranged at intervals smaller than the
opening width in the first direction of the openings arranged in an array on the substrate.
Holding the member, and superposing the second surface of the substrate opposite to the first
surface of the substrate on which the ultrasonic transducer elements are provided in the
individual openings and the surface of the reinforcing member be able to.
[0020]
Thus, when the distance between the linear grooves is set, at least one of the linear grooves can
communicate with the opening even if the relative displacement between the substrate and the
reinforcing member occurs. In addition, even if the substrate and the reinforcing member are
superimposed on each other in air or other gaseous atmosphere, the superposition can be
realized relatively easily. On the other hand, when the second surface of the substrate is
superimposed on the uniform plane, the gas is pressed into the individual openings in the plane
of the reinforcing member. At atmospheric pressure, a volume of gas larger than the volume of
the space in the opening tends to stay in the opening. Bonding of the substrate and the
reinforcing member can not be realized unless excess gas escapes from the gap between the
substrate and the reinforcing member simultaneously with closing the opening.
[0021]
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FIG. 1 is an external view schematically showing an ultrasonic diagnostic apparatus according to
a specific example of an electronic device according to an embodiment. It is an enlarged front
view of an ultrasonic probe. It is an enlarged plan view of an ultrasonic transducer element chip.
It is sectional drawing along line 4-4 in FIG. It is a top view of the reinforcement board which
shows a groove. FIG. 6 is an enlarged partial plan view of FIG. 5; FIG. 1 is a block diagram
schematically showing a circuit configuration of an ultrasonic diagnostic apparatus. FIG. 5 is a
partially enlarged vertical sectional view schematically showing a flexible film and a lower
electrode formed on a silicon wafer. FIG. 5 is a partially enlarged vertical sectional view
schematically showing a piezoelectric film and an upper electrode formed on a lower electrode.
FIG. 5 is a partially enlarged vertical sectional view schematically showing a conductive film
covering a silicon wafer. FIG. 2 is a partially enlarged vertical sectional view schematically
showing a wafer for an opening and a reinforcing plate formed in a silicon wafer. FIG. 7 is a
partial enlarged plan view schematically showing the positional relationship between an opening
and a groove when superposing a silicon wafer and a wafer for a reinforcing plate. FIG. 10 is a
partial enlarged plan view schematically showing an ultrasonic transducer element chip
according to another embodiment. FIG. 16 is a partial enlarged plan view schematically showing
an ultrasonic transducer element chip according to still another embodiment.
[0022]
Hereinafter, an embodiment of the present invention will be described with reference to the
attached drawings. Note that the present embodiment described below does not unduly limit the
contents of the present invention described in the claims, and all of the configurations described
in the present embodiment are essential as means for solving the present invention. Not
necessarily.
[0023]
(1) Overall Configuration of Ultrasonic Diagnostic Apparatus FIG. 1 schematically shows a
specific example of an electronic apparatus according to an embodiment of the present invention,
that is, a configuration of an ultrasonic diagnostic apparatus 11. The ultrasonic diagnostic
apparatus 11 includes an apparatus terminal 12 and an ultrasonic probe (probe) 13. The device
terminal 12 and the ultrasonic probe 13 are connected to each other by a cable 14. The device
terminal 12 and the ultrasonic probe 13 exchange electrical signals through the cable 14. A
display panel (display device) 15 is incorporated in the device terminal 12. The screen of the
display panel 15 is exposed on the surface of the device terminal 12. At the device terminal 12,
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an image is generated based on the ultrasonic waves detected by the ultrasonic probe 13, as
described later. The imaged detection result is displayed on the screen of the display panel 15.
[0024]
As shown in FIG. 2, the ultrasonic probe 13 has a housing 16. An ultrasonic transducer element
chip (hereinafter referred to as “element chip”) 17 is housed in the housing 16. The surface of
the element chip 17 can be exposed on the surface of the housing 16. The element chip 17
outputs an ultrasonic wave from the surface and receives a reflected wave of the ultrasonic wave.
In addition, the ultrasonic probe 13 can include a probe head 13 b detachably connected to the
probe body 13 a. At this time, the element chip 17 can be incorporated into the housing 16 of
the probe head 13b.
[0025]
FIG. 3 schematically shows a plan view of the element chip 17. The element chip 17 comprises a
substrate 21. An element array 22 is formed on the substrate 21. The element array 22
comprises an array of ultrasonic transducer elements (hereinafter referred to as “elements”)
23. The array is formed of a matrix of rows and columns. Each element 23 comprises a
piezoelectric element part. The piezoelectric element portion is composed of the lower electrode
24, the upper electrode 25 and the piezoelectric film 26. The piezoelectric film 26 is sandwiched
between the lower electrode 24 and the upper electrode 25 for each element 23.
[0026]
The lower electrode 24 has a plurality of first conductors 24a. The first conductors 24a extend
parallel to each other in the row direction of the array. One first conductor 24 a is assigned to
each row of elements 23. One first conductor 24 a is commonly disposed to the piezoelectric
films 26 of the elements 23 aligned in the row direction of the array. Both ends of the first
conductor 24 a are connected to the pair of lead wires 27 respectively. The lead wires 27 extend
parallel to each other in the column direction of the array. Therefore, all the first conductors 24a
have the same length. Thus, the lower electrode 24 is connected in common to the elements 23
of the entire matrix.
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[0027]
The upper electrode 25 has a plurality of second conductors 25a. The second conductors 25a
extend parallel to each other in the column direction of the array. One second conductor 25 a is
assigned to each row of elements 23. One second conductor 25a is disposed in common to the
piezoelectric films 26 of the elements 23 arranged in the column direction of the array. The
energization of the elements 23 is switched for each row. Line scan and sector scan are realized
according to such switching of energization. Since the elements 23 in one column simultaneously
output ultrasonic waves, the number of one columns, that is, the number of rows in the array can
be determined according to the output level of the ultrasonic waves. The number of rows may be
set to, for example, about 10 to 15 rows. Five lines are drawn, omitted in the figure. The number
of columns of the array can be determined according to the spread of the scan range. The
number of columns may be set to 128 or 256, for example. It is omitted in the figure and eight
columns are drawn. Alternatively, a staggered arrangement may be established in the
arrangement. In the case of the staggered arrangement, the elements 23 in the even columns
may be shifted by half the row pitch with respect to the elements 23 in the odd columns. The
number of elements in one of the odd and even columns may be one less than the number of
elements in the other. Furthermore, the roles of the lower electrode 24 and the upper electrode
25 may be switched. That is, while the upper electrode is commonly connected to the elements
23 of the entire matrix, the lower electrode may be commonly connected to the elements 23 in
each array column.
[0028]
The outline of the substrate 21 has a first side 21 a and a second side 21 b which are separated
by a pair of straight lines 29 which are parallel to each other. A first terminal array 32a of one
line is disposed between the first side 21a and the outline of the element array 22 in the
peripheral area 31 extending between the outline of the element array 22 and the outer edge of
the substrate 21. The second terminal array 32 b of one line is disposed between 21 b and the
contour of the element array 22. The first terminal array 32a can form one line parallel to the
first side 21a. The second terminal array 32b can form one line parallel to the second side 21b.
The first terminal array 32 a is configured of a pair of lower electrode terminals 33 and a
plurality of upper electrode terminals 34. Similarly, the second terminal array 32 b includes a
pair of lower electrode terminals 35 and a plurality of upper electrode terminals 36. Lower
electrode terminals 33 and 35 are connected to both ends of one lead wire 27 respectively. The
lead wire 27 and the lower electrode terminals 33 and 35 may be formed plane-symmetrically in
the vertical plane which bisects the element array 22. The upper electrode terminals 34 and 36
are connected to both ends of one second conductor 25a. The second conductor 25 a and the
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upper electrode terminals 34 and 36 may be formed plane-symmetrically in a vertical plane that
bisects the element array 22. Here, the outline of the substrate 21 is formed in a rectangular
shape. The contour of the substrate 21 may be square or trapezoidal.
[0029]
A first flexible printed circuit board (hereinafter referred to as “first flexible board”) 37 is
connected to the substrate 21. The first flexible member 37 covers the first terminal array 32a.
At one end of the first flexible member 37, conductive lines, ie, first signal lines 38 are formed
corresponding to the lower electrode terminal 33 and the upper electrode terminal 34
respectively. The first signal lines 38 individually face the individual lower electrode terminals 33
and the upper electrode terminals 34 and are joined separately. Similarly, a second flexible
printed circuit board (hereinafter referred to as "second flexible") 41 covers the substrate 21. The
second flexible cable 41 covers the second terminal array 32b. At the first end 41 a of the second
flexible cable 41, conductive lines, ie, second signal lines 42 are formed corresponding to the
lower electrode terminal 35 and the upper electrode terminal 36 individually. The second signal
lines 42 individually face the individual lower electrode terminals 35 and the upper electrode
terminals 36 and are joined separately.
[0030]
As shown in FIG. 4, each element 23 has a vibrating membrane 43. In order to construct the
vibrating film 43, an opening 45 is formed in the base 44 of the substrate 21 for each of the
individual elements 23. The openings 45 are arranged in an array relative to the substrate 44. A
flexible film 46 is formed on one surface of the substrate 44. The flexible film 46 is composed of
a silicon oxide (SiO 2) layer 47 stacked on the surface of the substrate 44 and a zirconium oxide
(ZrO 2) layer 48 stacked on the surface of the silicon oxide layer 47. The flexible membrane 46 is
in contact with the opening 45. In this way, a part of the flexible film 46 functions as the
vibrating film 43 corresponding to the contour of the opening 45. The film thickness of the
silicon oxide layer 47 can be determined based on the resonant frequency.
[0031]
The lower electrode 24, the piezoelectric film 26 and the upper electrode 25 are sequentially
stacked on the surface of the vibrating film 43. For the lower electrode 24, for example, a
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laminated film of titanium (Ti), iridium (Ir), platinum (Pt) and titanium (Ti) can be used. The
piezoelectric film 26 can be formed of, for example, lead zirconate titanate (PZT). The upper
electrode 25 can be formed of, for example, iridium (Ir). Other conductive materials may be used
for the lower electrode 24 and the upper electrode 25, and other piezoelectric materials may be
used for the piezoelectric film 26. Here, the piezoelectric film 26 completely covers the lower
electrode 24 under the upper electrode 25. A short circuit can be avoided between the upper
electrode 25 and the lower electrode 24 by the action of the piezoelectric film 26.
[0032]
A protective film 49 is stacked on the surface of the substrate 21. The protective film 49 covers
the entire surface, for example, on the surface of the substrate 21. As a result, the element array
22, the first and second terminal arrays 32 a and 32 b, and the first and second flexes 37 and 41
are covered with the protective film 49. For example, a silicone resin film can be used for the
protective film 49. The protective film 49 protects the structure of the element array 22, the
junction of the first terminal array 32 a and the first flex 37, and the junction of the second
terminal array 32 b and the second flex 41.
[0033]
A partition wall 51 is partitioned between the adjacent openings 45. The openings 45 are
separated by the partition wall 51. The wall thickness t of the partition wall 51 corresponds to
the space between the openings 45. The partition wall 51 defines two wall surfaces in a plane
extending parallel to one another. The wall thickness t corresponds to the distance between the
wall surfaces. That is, the wall thickness t can be defined by the length of a perpendicular line
perpendicular to the wall surface and sandwiched between the wall surfaces. The wall height H
of the partition wall 51 corresponds to the depth of the opening 45. The depth of the opening 45
corresponds to the thickness of the substrate 44. Therefore, the wall height H of the partition
wall 51 can be defined by the length of the wall surface defined in the thickness direction of the
base 44. Since the substrate 44 has a uniform thickness, the partition wall 51 can have a
constant wall height H over the entire length. If the wall thickness t of the partition wall 51 is
reduced, the arrangement density of the vibrating membrane 43 can be increased. This can
contribute to the miniaturization of the element chip 17. If the wall height H of the partition wall
51 is larger than the wall thickness t, the bending rigidity of the element chip 17 can be
enhanced. Thus, the distance between the openings 45 is set smaller than the depth of the
openings 45.
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[0034]
A reinforcing plate (reinforcing member) 52 is fixed to the back surface of the base 44. The back
surface of the base 44 is superimposed on the front surface of the reinforcing plate 52. The
reinforcing plate 52 closes the opening 45 at the back surface of the element chip 17. The
reinforcing plate 52 can comprise a rigid substrate. The reinforcing plate 52 can be formed of,
for example, a silicon substrate. The thickness of the base 44 is set to, for example, about 100
μm, and the thickness of the reinforcing plate 52 is set to, for example, about 100 to 150 μm.
Here, the partition wall 51 is coupled to the reinforcing plate 52. The reinforcing plate 52 is
joined to the individual partition walls 51 in at least one joint area. An adhesive can be used for
bonding.
[0035]
A linear groove (linear groove) 53 is formed on the surface of the reinforcing plate 52. The
grooves 53 divide the surface of the reinforcing plate 52 into a plurality of flat surfaces 54. The
plurality of planes 54 extend in one virtual plane HP. The back surface of the base 44 spreads in
the virtual plane HP. The partition wall 51 is joined to the flat surface 54. The groove 53 is
recessed from the virtual plane HP. The cross-sectional shape of the groove 53 may be
rectangular, triangular, semicircular or the like.
[0036]
As shown in FIG. 5, the openings 45 form a row in the first direction D1. The centroids 45c of the
outline shape of the openings 45 are arranged at an equal pitch on one straight line 56 in the
first direction D1. Since the contour 45a of the openings 45 is represented by copying of one
shape, the openings 45 of the same shape are repeatedly arranged at a constant pitch. The
contour 45a of the opening 45 is defined, for example, as a square. Specifically, it is formed in a
rectangular shape. The long side of the rectangle is aligned with the first direction D1. Thus,
since the opening 45 has a rectangular outline 45a, the partition wall 51 can have a constant
wall thickness t over the entire length. At this time, the bonding area of the partition wall 51 may
be an area including the central position of the long side. In particular, the bonding area of the
partition wall 51 may be an area including the entire length of the long side. The partition wall
51 can be surface-joined to the reinforcing plate 52 on the entire surface between the openings
45 over the entire length of the long side. Furthermore, the bonding area of the partition wall 51
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can be disposed at least one place on each side of the square. The junction area of the partition
wall 51 can surround the square without interruption. The partition wall 51 can be surfacebonded to the reinforcing plate 52 on the entire surface between the openings 45 over the entire
circumference of the square.
[0037]
The grooves 53 are arranged in the first direction D1 parallel to each other at a constant distance
L. The groove 53 extends in a second direction D2 intersecting the first direction D1. Both ends
of the groove 53 open at the end faces 57 a and 57 b of the reinforcing plate 52. One groove 53
sequentially crosses the contour 45 a of the opening 45 in one row (here, one row). At least one
groove 53 is connected to each opening 45. Here, the second direction D2 is orthogonal to the
first direction D1. Therefore, the groove 53 crosses the contour 45 a of the opening 45 in the
direction of the short side of the rectangle.
[0038]
As shown in FIG. 6, between the flats 54, the grooves 53 form passages 58a, 58b between the
base body 44 and the reinforcing plate 52. Thus, the space in the groove 53 communicates with
the internal space of the opening 45. The passages 58 a and 58 b ensure ventilation between the
internal space of the opening 45 and the external space of the substrate 21. In a plan view seen
from the direction orthogonal to the surface of the substrate 21, ie, the thickness direction of the
substrate 21, one groove 53 sequentially traverses the contour 45a of the openings 45 in one
row (here, one row). The openings 45 are connected by a passage 58a. Both ends of the groove
53 open at the end faces 57 a and 57 b of the reinforcing plate 52. Thus, the passage 58b is
opened from the opening 45 of the row end to the outside of the outline of the substrate 21.
[0039]
The distance L between the grooves 53 is set smaller than the opening width S of the opening
45. The opening width S is defined by the largest length of the line segments crossing the
opening 45 in the alignment direction of the grooves 53, ie, the first direction D1. In other words,
the opening width S corresponds to the distance between the parallel lines 59 circumscribing the
contour 45 a of the opening 45. Parallel lines 59 circumscribing the contour 45 a of the opening
45 are identified for each opening 45. The parallel lines 59 extend in the second direction D2. If
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the opening widths S are different from each other for each opening 45, the grooves 53 may be
arranged at an interval L smaller than the minimum value of the opening width S. Here, the
distance L between the grooves 53 is set to one-third or more of the opening width S of the
opening 45 and smaller than one-half.
[0040]
(2) Circuit Configuration of Ultrasonic Diagnostic Apparatus As shown in FIG. 7, the integrated
circuit includes a multiplexer 61 and a transmission / reception circuit 62. The multiplexer 61
includes a port group 61 a on the element chip 17 side and a port group 61 b on the
transmitting and receiving circuit 62 side. The first signal line 38 and the second signal line 42
are connected to the port group 61 a on the element chip 17 side via the first wiring 54. Thus,
the port group 61a is connected to the element array 22. Here, a specified number of signal lines
63 in the integrated circuit chip 55 are connected to the port group 61b on the transmission /
reception circuit 62 side. The specified number corresponds to the number of columns of the
elements 23 simultaneously output in scanning. The multiplexer 61 manages the interconnection
between the port on the cable 14 side and the port on the element chip 17 side.
[0041]
The transmission / reception circuit 62 is provided with a specified number of changeover
switches 64. Each changeover switch 64 is individually connected to the corresponding signal
line 63. The transmission / reception circuit 62 includes a transmission path 65 and a reception
path 66 for each of the changeover switches 64. The transmission path 65 and the reception
path 66 are connected in parallel to the changeover switch 64. The changeover switch 64
selectively connects the transmission path 65 or the reception path 66 to the multiplexer 61. A
pulser 67 is incorporated in the transmission path 65. The pulser 67 outputs a pulse signal at a
frequency corresponding to the resonant frequency of the vibrating membrane 43. An amplifier
68, a low pass filter (LPF) 69 and an analog-to-digital converter (ADC) 71 are incorporated in the
reception path 66. The detection signals of the individual elements 23 are amplified and
converted into digital signals.
[0042]
The transmission / reception circuit 62 includes a drive / reception circuit 72. The transmission
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path 65 and the reception path 66 are connected to the drive / reception circuit 72. The drive /
reception circuit 72 simultaneously controls the pulser 67 in accordance with the form of scan.
The drive / reception circuit 72 receives the digital signal of the detection signal according to the
form of scan. The drive / reception circuit 72 is connected to the multiplexer 61 by a control line
73. The multiplexer 61 carries out the management of interconnection based on the control
signal supplied from the drive / reception circuit 72.
[0043]
A processing circuit 74 is incorporated in the device terminal 12. The processing circuit 74 can
include, for example, a central processing unit (CPU) and a memory. The entire operation of the
ultrasonic diagnostic apparatus 11 is controlled in accordance with the processing of the
processing circuit 74. The processing circuit 74 controls the drive / reception circuit 72 in
accordance with an instruction input from the user. The processing circuit 74 generates an image
in response to the detection signal of the element 23. The image is identified by the drawing
data.
[0044]
A drawing circuit 75 is incorporated in the device terminal 12. The drawing circuit 75 is
connected to the processing circuit 74. The display panel 15 is connected to the drawing circuit
75. The drawing circuit 75 generates a drive signal in accordance with the drawing data
generated by the processing circuit 74. The drive signal is sent to the display panel 15. As a
result, an image is displayed on the display panel 15.
[0045]
(3) Operation of Ultrasonic Diagnostic Apparatus Next, the operation of the ultrasonic diagnostic
apparatus 11 will be briefly described. The processing circuit 74 instructs the drive / reception
circuit 72 to transmit and receive ultrasonic waves. The drive / reception circuit 72 supplies a
control signal to the multiplexer 61 and supplies a drive signal to each pulser 67. The pulser 67
outputs a pulse signal in response to the supply of the drive signal. The multiplexer 61 connects
the ports of the port group 61a to the ports of the port group 61b according to the instruction of
the control signal. The pulse signal is supplied to the elements 23 row by row through the lower
electrode terminals 33 and 35 and the upper electrode terminals 34 and 36 according to the
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selection of the port. The vibrating film 43 vibrates in response to the supply of the pulse signal.
As a result, desired ultrasonic waves are emitted toward the object (for example, the inside of the
human body).
[0046]
After transmission of the ultrasonic waves, the changeover switch 64 is switched. The
multiplexer 61 maintains the connection of the ports. The changeover switch 64 establishes the
connection of the reception path 66 and the signal line 63 instead of the connection of the
transmission path 65 and the signal line 63. The reflected wave of the ultrasonic wave vibrates
the vibrating film 43. As a result, the detection signal is output from the element 23. The
detection signal is converted into a digital signal and sent to the drive / reception circuit 72.
[0047]
Transmission and reception of ultrasound waves are repeated. At the time of repetition, the
multiplexer 61 changes the connection of ports. As a result, line scan and sector scan are
realized. When the scan is complete, the processing circuit 74 forms an image based on the
digital signal of the detection signal. The formed image is displayed on the screen of the display
panel 15.
[0048]
The element 23 can be formed thin in the element chip 17. The element 23 can be formed on a
thin substrate 21. Even if the reinforcing plate 52 is fixed to the substrate 21, the element chip
17 can be formed thin. At the same time, the reinforcing plate 52 reinforces the strength of the
substrate 21. In particular, since the wall thickness t is smaller than the wall height H in the
partition wall 51, sufficient rigidity can be secured in the thickness direction of the substrate 21
in the partition wall 51 in relation to the section coefficient. The force in the thickness direction
of the substrate 21 can be supported by the reinforcing plate 52 along the partition wall 51.
Thus, the element chip 17 can have sufficient strength in the thickness direction of the substrate
21. Even if the thickness of the substrate 21 is set to, for example, about 100 μm, the
reinforcing plate 52 can prevent the substrate 21 from being damaged. On the other hand, in the
case where the element array is formed of bulk ultrasonic transducer elements, the thickness of
the substrate is set to about several millimeters. Even if the reinforcing plate 52 is joined, the
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thickness of the element chip 17 can be reliably reduced as compared with the case where the
element array is configured with a bulk ultrasonic transducer element. In addition, since the
acoustic impedance of the vibrating membrane 43 is closer to that of the human body as
compared to the bulk ultrasonic transducer element, the element chip 17 omits the matching
layer of acoustic impedance as compared to the bulk ultrasonic transducer element. It can be
done. The omission of such a matching layer can further contribute to the thinning of the
element chip 17.
[0049]
The reinforcing plate 52 is joined to the individual partition walls 51 in at least one joint area.
When the partition wall 51 is joined to the reinforcing plate 52, the movement of the partition
wall 51 is restrained by the reinforcing plate 52. Therefore, the vibration of the partition wall 51
can be prevented. As a result, crosstalk between the elements 23 can be prevented. Moreover,
when the movement of the partition wall 51 is thus restrained, the action of the vibration of the
partition wall 51 with respect to the ultrasonic vibration of the element 23 can be avoided. In the
element 23, ultrasonic vibration in a clear vibration mode can be obtained. Thus, when the
vibration of the partition wall 51 is avoided, the reduction in the amplitude of the ultrasonic
vibration can be suppressed. On the other hand, when the partition wall 51 moves, a distorted
vibration mode having a frequency lower than that of the vertical vibration mode of the vibrating
membrane 43 appears. In addition, the kinetic energy of the vibrating membrane 43 is reduced
by the amount of movement of the partition wall 51, and the amplitude of vibration is reduced.
[0050]
A space in the opening 45 is surrounded by the substrate 21, the flexible film 46 (the vibrating
film 43) and the reinforcing plate 52. The groove 53 crosses the outline 45 a of the opening 45
in a plan view seen from the thickness direction of the substrate 21. Thus, the internal space of
the individual openings 45 can ensure ventilation between the external space of the substrate 21.
As a result, the internal space of the opening 45 is connected to the atmospheric space. In the
interior space of the opening 45 a pressure buildup can be avoided. Damage to the vibrating
membrane 43 can be prevented. Here, the external space is a space separated from the internal
space by the substrate 21, the flexible film 46 and the reinforcing plate 52, which means a
significantly larger space than the internal space.
[0051]
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17
In the element chip 17, the distance L between the grooves 53 is set smaller than the opening
width S of the opening 45. Therefore, at least one groove 53 can be connected to the contour 45
a of the opening 45 even if relative displacement occurs between the substrate 21 and the
reinforcing plate 52. The individual openings 45 can always ensure ventilation between them
and the outside of the openings 45. In addition, since the distance L between the grooves 53 is
set to one-third or more of the opening width S and smaller than one-half, at least two grooves
53 are provided for each opening 45. It can be connected to the contour 45a. Therefore, in the
individual openings 45, even if clogging occurs in one of the grooves 53, ventilation can be
secured between the other grooves 53 and the outside of the openings 45. In addition, since it is
avoided that the grooves 53 cross the contour 45a beyond four, the decrease in the bonding
strength of the partition wall 51 can be suppressed. Here, it is desirable that the width of the
groove 53 be set smaller than the wall thickness t of the partition wall 51. In this way, even if the
groove 53 is disposed between the openings 45 adjacent to each other in the first direction D1, a
sufficient bonding area can be secured between the partition wall 51 and the reinforcing plate
52. . The decrease in bonding strength of the partition wall 51 can be suppressed.
[0052]
The bonding area of the partition wall 51 can be an area including the central position of the
long side. A portion of the partition wall 51 where the vibration amplitude is large is joined to the
reinforcing plate 52. As a result, vibration of the partition wall 51 can be effectively prevented.
Moreover, the bonding area of the partition wall 51 can be an area including the entire length of
the long side. Thus, if the partition wall 51 is joined to the reinforcing plate 52 over the entire
length of the long side, the vibration of the partition wall 51 can be reliably prevented.
Furthermore, the partition wall 51 can be surface-bonded on the entire surface between the
openings 45 over the entire length of the long side. Thus, if the partition wall 51 is surfacebonded to the reinforcing plate 52 over the entire length of the long side along the entire length
between the openings 45, the vibration of the partition wall 51 can be reliably prevented.
[0053]
The bonding area of the partition wall 51 may be disposed at least one on each side of the
square. In this way, if the partition wall 51 is joined to the reinforcing plate 52 on each side of
the square, the vibration of the partition wall 51 can be reliably prevented. Moreover, the
bonding area of the partition wall 51 can surround the square without interruption. In this way, if
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18
the partition wall 51 is joined to the reinforcing plate 52 in the entire area of the square, the
vibration of the partition wall 51 can be reliably prevented. Moreover, the partition wall 51 can
be surface-bonded on the entire surface between the openings 45 over the entire circumference
of the square. In this way, if the partition wall 51 is surface-bonded to the reinforcing plate 52 on
the entire surface between the openings 45 over the entire circumference of the square, the
vibration of the partition wall 51 can be reliably prevented.
[0054]
In the element chip 17, in the openings 45 adjacent to each other in the row direction, the spaces
in the openings 45 communicate with each other by the passage 58 a. Then, the passage 58 b is
opened to the outside of the outline of the substrate 21 from the opening 45 at the row end. The
channels 58a and 58b are formed by one groove 53. Thus, the ventilation of all the openings 45
in one row can be secured by the single groove 53.
[0055]
Moreover, the groove 53 crosses the opening 45 in the direction of the short side of the
rectangle in a plan view from the thickness direction of the substrate 21. Thus, when the distance
L between the grooves 53 is set in the long side direction of the rectangle, a large distance is
secured between the parallel lines 56 as compared to the case where the distance between the
grooves 53 is set in the short side direction of the rectangle. Can. Therefore, the grooves 53 may
be formed with a small number. Processing efficiencies can be achieved.
[0056]
In addition, the grooves 53 are arranged at an equal pitch in the first direction D1. In forming the
grooves 53, the relative positions of the grooves 53 and the reinforcing plate 52 can be freely set
as long as an equal pitch is secured. When processing the reinforcing plate 52, the positioning
accuracy of the reinforcing plate 52 can be relaxed. The processing of the reinforcing plate 52
can be simplified.
[0057]
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19
(4) Method of Manufacturing Ultrasonic Transducer Element Chip As shown in FIG. 8, the lower
electrode 24, the lead wire 27 and the lower electrode terminal 33, 35 for each element chip 17
on the surface of the silicon wafer (substrate) 78. Are formed (not shown in FIG. 7 and
thereafter). Prior to the formation of the lower electrode 24, the lead wire 27 and the lower
electrode terminals 33 and 35, a silicon oxide film 79 and a zirconium oxide film 81 are
successively formed on the surface of the silicon wafer 78. A conductive film is formed on the
surface of the zirconium oxide film 81. The conductive film is formed of a laminated film of
titanium, iridium, platinum and titanium. The lower electrode 24, the lead wire 27, and the lower
electrode terminals 33, 35 are formed from the conductive film based on the photolithography
technology.
[0058]
As shown in FIG. 9, the piezoelectric film 26 and the upper electrode 25 are formed on the
surface of the lower electrode 24 for each individual element 23. A piezoelectric material film
and a conductive film are formed on the surface of the silicon wafer 78 in forming the
piezoelectric film 26 and the upper electrode 25. The piezoelectric material film is composed of a
PZT film. The conductive film is composed of an iridium film. The piezoelectric film 26 and the
upper electrode 25 are formed of the piezoelectric material film and the conductive film for each
of the elements 23 based on the photolithography technology.
[0059]
Subsequently, as shown in FIG. 10, a conductive film 82 is formed on the surface of the silicon
wafer 78. The conductive film 82 interconnects the upper electrodes 25 in each column in each
element chip 17. Then, the upper electrode 25 and the upper electrode terminals 34 and 36 are
formed from the conductive film 82 based on the photolithography technology.
[0060]
Thereafter, as shown in FIG. 11, arrayed openings 45 are formed from the back surface of the
silicon wafer 78. An etching process is performed to form the opening 45. The silicon oxide film
79 functions as an etching stop layer. The vibrating film 43 is partitioned by the silicon oxide
film 79 and the zirconium oxide film 81. After the opening 45 is formed, the surface of the wafer
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20
(reinforcement member) 83 for reinforcing plate is superimposed on the back surface of the
silicon wafer 78. Prior to superposition, the wafer 83 is held on a handling mechanism or stage.
For the wafer 83, for example, a rigid insulating substrate can be used. A silicon wafer can be
used as the insulating substrate. For bonding, an adhesive can be used, for example. After
bonding, the individual element chips 17 are cut out of the silicon wafer 78.
[0061]
A straight groove 84 is formed on the surface of the reinforcing plate wafer 83 prior to bonding.
The grooves 84 extend parallel to one another at equal intervals. At least one end of the groove
84 is released at the end face of the wafer 83. The grooves 84 are arranged at an interval L
smaller than the opening width S of the opening 45. In this way, when the distance L between the
grooves 84 is set, at least one of the grooves 84 has the contour 45 a of the opening 45 even if
relative displacement occurs between the silicon wafer 78 and the wafer 83 for reinforcing plate.
It can cross. For example, as shown in FIG. 12, even if the wafer 83 for reinforcing plate is shifted
in the first direction D1 with respect to the silicon wafer 78 and the groove 84a is positioned
between the openings 45, the two openings 45 are respectively At least one groove 84b may be
arranged. The grooves 84 provide the grooves 53 of the reinforcing plate 52 when the individual
element chips 17 are cut out of the silicon wafer 78.
[0062]
Thus, when the grooves 84 are formed, the superposition can be realized relatively easily even if
the silicon wafer 78 and the wafer 83 are superposed on each other in the air or other gas
atmosphere. On the other hand, when the back surface of the silicon wafer 78 is superimposed
on a uniform plane, gas is pressed into the individual openings 45 in the plane of the wafer for
the reinforcing plate. At atmospheric pressure, a gas having a volume larger than that of the
space in the opening 45 tends to stay in the opening 45. At the same time as closing the opening
45, bonding of the silicon wafer 78 and the wafer for the reinforcing plate can not be realized
unless excess gas escapes from the gap between the silicon wafer 78 and the wafer for the
reinforcing plate.
[0063]
(5) Ultrasonic Transducer Element Chip According to Another Embodiment FIG. 13 schematically
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21
shows an ultrasonic transducer element chip 17a according to another embodiment. In the
element chip 17a, the single grooves 85 locally extend in the second direction D2. Such local
grooves 85 form passages 58a, 58b between the several openings 45. The combination of the
plurality of grooves 85 forms a series of passages 58a and 58b which sequentially connect the
openings 45 one after another sequentially crossing the openings 45 in a row in plan view from
the thickness direction of the substrate 21. Thus, the combination of the passages 58a, 58b can
ensure ventilation for all the openings 45 in a row. The grooves 85 can be configured similar to
the grooves 53. The other configuration can be configured in the same manner as the element
chip 17. The same reference numerals as in the element chip 17 denote the same parts or
components in the figure.
[0064]
FIG. 14 schematically shows an ultrasonic transducer element chip 17b according to still another
embodiment. In this element chip 17b, the groove 86 extends in the first direction D1, that is, the
long side direction of the rectangle. Therefore, in a plan view from the thickness direction of the
substrate 21, the groove 86 crosses the outline 45 a of the opening 45 at the short side of the
rectangle. At the short side of the rectangle, the wall of the contour 45a of the opening 45, that
is, the partition wall 51 is difficult to deform due to the cross section coefficient. Even if the
range of bonding is narrowed due to the formation of the groove 86, the partition wall 51 can
maintain relatively high rigidity. Therefore, the vibration (residual vibration) of the partition wall
51 can be suppressed. The other configuration can be configured in the same manner as the
element chip 17. The same reference numerals as in the element chip 17 denote the same parts
or components in the figure.
[0065]
In any other embodiment, a staggered arrangement may be established in the arrangement of the
openings 45. In the case of the staggered arrangement, the elements 23 in the even columns may
be shifted by half the row pitch with respect to the elements 23 in the odd columns. The number
of elements in one of the odd and even columns may be one less than the number of elements in
the other. In addition, the grooves 53, 85, 86 may be inclined at a predetermined inclination
angle with respect to the first direction D1 or the second direction D2.
[0066]
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22
It should be understood by those skilled in the art that although the present embodiment has
been described in detail as described above, many modifications can be made without departing
substantially from the novel matters and effects of the present invention. Therefore, all such
modifications are included in the scope of the present invention. For example, in the specification
or the drawings, the terms described together with the broader or synonymous different terms at
least once can be replaced with the different terms anywhere in the specification or the drawings.
Further, the configurations and operations of the ultrasonic diagnostic apparatus 11, the
ultrasonic probe 13, the probe head 13b, the element chips 17, 17a and 17b, the element 23 and
the like are not limited to those described in this embodiment, and various modifications are
possible. It is.
[0067]
11 electronic device (ultrasound diagnostic apparatus) 13 probe (ultrasonic probe) 13b probe
head 15 display device (display panel) 16 housing 17 ultrasonic transducer element chip 17a
Ultrasonic transducer element chip, 17b: ultrasonic transducer element chip, 21: substrate, 23:
ultrasonic transducer element, 45: opening, 45a: contour, 52: reinforcing member (reinforcement
plate), 53: linear groove (Grooves) 56 parallel lines 58a passages 58b passages 74 processing
circuits 83 reinforcing members (wafers for reinforcing plates) 84 linear grooves (grooves) 85
linear grooves (grooves) 86: linear grooves (grooves) D1: first direction (first direction) D2:
second direction (second direction) L: distance of linear grooves S: opening width
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