JP6221679B2 - Ultrasonic device and probe, electronic apparatus and ultrasonic imaging apparatus - Google Patents

Description

  The present invention relates to an ultrasonic device, and a probe, an electronic apparatus, an ultrasonic imaging apparatus, and the like using the ultrasonic device.

  For example, as disclosed in Patent Document 1, a capacitive micromachine ultrasonic transducer is generally known. Vibrating membranes are arranged in an array on the substrate. A space layer is defined between the substrate and the vibration film. An electrostatic force is generated by the electrode on the substrate and the electrode on the vibrating membrane, and the vibrating membrane vibrates ultrasonically in accordance with a change in the electrostatic force.

International Patent Publication No. 2011/033887

  Patent Document 1 discloses a rectangular diaphragm. The aspect ratio of the rectangle can be set to various values. The vibrating membranes can be formed with different sizes. For example, semiconductor process technology can be used in forming the vibration film. If the vibrating membranes are formed with different sizes, the layout pattern of the vibrating membranes is sparse and dense. As a result, a dimensional error of the diaphragm is likely to occur.

  An ultrasonic device that can reduce the dimensional error of the vibration film as much as possible has been desired.

  (1) According to one embodiment of the present invention, a substrate in which a plurality of first openings and a plurality of second openings are arranged in an array is formed corresponding to each of the first openings and the second openings. And a vibration film that closes the first opening or the second opening, and a piezoelectric element formed corresponding to each of the vibration films, wherein the first opening is formed from the thickness direction of the substrate. In the plan view, the aspect ratio obtained by dividing the length in the second direction intersecting the first direction by the length in the first direction has a first aspect ratio greater than 1, and the second opening includes the first opening The present invention relates to an ultrasonic device having the same length as the first opening in the first direction in a plan view and a second aspect ratio smaller than the first aspect ratio in the aspect ratio.

  In such an ultrasonic device, for example, a semiconductor process technique can be used for forming the first opening and the second opening. Since the first opening and the second opening have the same length in the first direction, the occurrence of density in the array pattern of the first opening and the second opening is avoided, and thus the first opening and the second opening The dimensional error of the two openings can be reduced. As a result, the dimensional error of the diaphragm that closes the first opening and the dimensional error of the diaphragm that closes the second opening can be reduced.

  (2) The first opening and the second opening may be arranged in the second direction. According to this aspect, the electrodes can be shared by the first piezoelectric element and the second piezoelectric element for each column. Electric power can be commonly supplied to the first piezoelectric element and the second piezoelectric element for each column. Therefore, the diaphragm can operate for each column.

  (3) The first opening and the second opening may be arranged in the first direction. According to this aspect, the electrodes can be shared by the first piezoelectric element and the second piezoelectric element for each column. Electric power can be commonly supplied to the first piezoelectric element and the second piezoelectric element for each column. Therefore, the diaphragm can operate for each column.

  (4) The first openings may be arranged at an equal pitch in the first direction. In this way, the density of the layout pattern can be reliably avoided.

  (5) The second openings may be arranged at an equal pitch in the first direction. In this way, the density of the layout pattern can be reliably avoided.

  (6) In the ultrasonic device, the aspect ratio of the second opening may be 1. In this way, the sensitivity of the vibrating membrane that closes the second opening can be increased.

  (7) The diaphragm formed corresponding to the second opening has a resonance frequency at a frequency corresponding to a harmonic of the resonance frequency of the diaphragm formed corresponding to the first opening. May be. When an ultrasonic wave having a specific frequency is transmitted toward the subject, the reflected ultrasonic wave includes an ultrasonic component of its harmonics in addition to the ultrasonic component of the specific frequency. Therefore, if the ultrasonic wave of the higher harmonic is received in addition to the ultrasonic wave of the specific frequency, the sensitivity of the ultrasonic device is enhanced.

  (8) The ultrasonic device can be used by being incorporated in a probe. At this time, the probe may include an ultrasonic device and a casing that supports the ultrasonic device.

  (9) The ultrasonic device can be used by being incorporated in an electronic apparatus. At this time, the electronic apparatus may include an ultrasonic device and a processing apparatus that is connected to the ultrasonic device and processes the output of the ultrasonic device.

  (10) The ultrasonic device can be used by being incorporated in an ultrasonic imaging apparatus. At this time, the ultrasonic imaging apparatus may include an ultrasonic device and a display device that displays an image generated from the output of the ultrasonic device.

1 is an external view schematically showing a specific example of an electronic apparatus, that is, an ultrasonic diagnostic apparatus. It is an enlarged front view of an ultrasonic probe. 1 is an enlarged plan view of an ultrasonic device according to a first embodiment. It is sectional drawing along the AA line of FIG. It is a conceptual diagram which shows the layout pattern of a 1st opening part and a 2nd opening part. It is a manufacturing method of an ultrasonic device, and is an enlarged partial sectional view showing a photoresist on a substrate roughly. It is a manufacturing method of an ultrasonic device, and is an expanded partial sectional view showing roughly the formation process of the upper stage surface and the lower stage surface. It is a manufacturing method of an ultrasonic device, and is an expanded partial sectional view showing a formation process of a silicon oxide layer roughly. It is a manufacturing method of an ultrasonic device, and is an expanded partial sectional view showing a formation process of a zirconium oxide layer roughly. It is a manufacturing method of an ultrasonic device, and is an enlarged partial sectional view showing roughly the formation process of the 1st piezoelectric element and the 2nd piezoelectric element. It is a manufacturing method of an ultrasonic device, and is an expanded partial sectional view showing roughly the formation process of the 1st opening and the 2nd opening. FIG. 5 is an enlarged partial plan view of an ultrasonic device according to a second embodiment. It is a conceptual diagram which shows the layout pattern of a 1st opening part and a 2nd opening part. FIG. 6 is an enlarged partial plan view of an ultrasonic device according to a third embodiment. It is a conceptual diagram which shows the layout pattern of a 1st opening part and a 2nd opening part. It is an enlarged partial sectional view of an ultrasonic device concerning a 3rd embodiment. It is an enlarged partial sectional view of an ultrasonic device concerning a modification of a 3rd embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are essential as means for solving the present invention. Not necessarily.

(1) Overall Configuration of Ultrasonic Diagnostic Device FIG. 1 schematically shows a configuration of an example of an electronic apparatus, that is, an ultrasonic diagnostic device (ultrasonic imaging device) 11. The ultrasonic diagnostic apparatus 11 includes an apparatus terminal (processing apparatus) 12 and an ultrasonic probe (probe) 13. The apparatus terminal 12 and the ultrasonic probe 13 are connected to each other by a cable 14. The apparatus terminal 12 and the ultrasonic probe 13 exchange electric 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. In the device terminal 12, an image is generated based on the ultrasonic wave detected by the ultrasonic probe 13. The imaged detection result is displayed on the screen of the display panel 15.

  As shown in FIG. 2, the ultrasonic probe 13 has a housing 16. An ultrasonic device 17 is accommodated in the housing 16. The surface of the ultrasonic device 17 can be exposed on the surface of the housing 16. The ultrasonic device 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 13b that is detachably connected to the probe main body 13a. At this time, the ultrasonic device 17 can be incorporated into the housing 16 of the probe head 13b.

(2) Configuration of Ultrasonic Device According to First Embodiment FIG. 3 schematically shows a plan view of the ultrasonic device 17 according to the first embodiment. The ultrasonic device 17 includes a base 21. An element array 22 is formed on the base 21. The element array 22 includes an array of first ultrasonic transducer elements (hereinafter referred to as “first elements”) 23 and second ultrasonic transducer elements (hereinafter referred to as “second elements”) 24. The array is formed of a matrix having a plurality of rows and a plurality of columns. Here, one column of first elements 23 and one column of second elements 24 are alternately arranged in the row direction. One row of the first elements 23 and one row of the second elements 24 form one segment. A plurality of first elements 23 and second elements 24 perform transmission or reception at the same time for each segment. As will be described later, an upper step surface 26 and a lower step surface 27 having a step 25 are formed on the surface of the base 21, the first element 23 is disposed on the lower step surface 27, and the second element 24 is disposed on the upper step surface 26. Be placed. The plane including the upper step surface 26 and the plane including the lower step surface 27 spread in parallel to each other. The upper surface 26 is further away from the back surface of the base 21 than the lower surface 27. The lower step surface 27 is continuous around the upper step surface 26. The ultrasonic device 17 is configured as a single ultrasonic transducer element chip.

  Each first element 23 includes a first vibration film 31. Details of the first vibration film 31 will be described later. In FIG. 3, the outline of the first vibration film 31 is drawn with a dotted line in a plan view in a direction orthogonal to the film surface of the first vibration film 31 (a plan view in the thickness direction of the base 21). A first piezoelectric element 32 is formed on the first vibration film 31. In the first piezoelectric element 32, as will be described later, a piezoelectric film 35 is sandwiched between the upper electrode 33 and the lower electrode 34. These are stacked in order. The first vibration film 31 has a resonance frequency at the first frequency.

  Each second element 24 includes a second vibration film 36. Details of the second vibration film 36 will be described later. In FIG. 3, the outline of the second vibration film 36 is drawn with a dotted line in a plan view in a direction orthogonal to the film surface of the second vibration film 36 (a plan view in the thickness direction of the base 21). A second piezoelectric element 37 is formed on the second vibration film 36. In the second piezoelectric element 37, as will be described later, the piezoelectric film 41 is sandwiched between the upper electrode 38 and the lower electrode 39. These are stacked in order. As described above, since the first element 23 is disposed on the lower surface 27 and the second element 24 is disposed on the upper surface 26, the film surface of the second vibration film 36 is the film surface of the first vibration film 31. It arrange | positions in the position higher than the plane containing. The second vibration film 36 has a resonance frequency at the second peripheral edge number. The second frequency corresponds to a harmonic of the first frequency that is the resonance frequency of the first vibrating membrane 31. Therefore, the second vibration film 36 is smaller than the first vibration film 31. The size is compared by the area of the film surface of the first vibration film 31 and the second vibration film 36.

  A plurality of first conductors 42 are formed on the surface of the base 21. The first conductors 42 extend parallel to each other in the column direction of the array. One first conductor 42 is assigned to each row of the first elements 23. One first conductor 42 is disposed in common to the first elements 23 arranged in the column direction of the array. The first conductor 42 forms a lower electrode 34 for each first element 23. For the first conductor 42, for example, a laminated film of titanium (Ti), iridium (Ir), platinum (Pt), and titanium (Ti) can be used. However, other conductive materials may be used for the first conductor 42.

  A plurality of second conductors 43 are formed on the surface of the base 21. The second conductors 43 extend parallel to each other in the column direction of the array. One second conductor 43 is assigned to each row of the second elements 24. One second conductor 43 is disposed in common to the second elements 24 arranged in the column direction of the array. The second conductor 43 forms a lower electrode 39 for each second element 24. For the second conductor 43, for example, a laminated film of titanium (Ti), iridium (Ir), platinum (Pt), and titanium (Ti) can be used. However, other conductive materials may be used for the second conductor 43.

  A plurality of third conductors 44 are further formed on the surface of the base 21. The third conductors 44 extend parallel to each other in the row direction of the array. One third conductor 44 is assigned to the first element 23 and the second element 24 in one row. One third conductor 44 is commonly connected to the first element 23 and the second element 24 arranged in the row direction of the array. The third conductor 44 forms the upper electrodes 33 and 38 for each of the first elements 23 or the second elements 24. Both ends of the third conductor 44 are connected to a pair of lead wires 45, respectively. The lead wires 45 extend in parallel to each other in the column direction of the array. Accordingly, all the third conductors 44 have the same length. Thus, the upper electrodes 33 and 38 are connected in common to the first element 23 and the second element 24 of the entire matrix. The third conductor 44 can be formed of, for example, iridium (Ir). However, other conductive materials may be used for the third conductor 44.

  Energization of the elements 23 and 24 is switched for each segment. Linear scan and sector scan are realized according to such switching of energization. Since the first elements 23 in one column simultaneously output ultrasonic waves, the number of columns, that is, the number of rows in the array, can be determined according to the output level of the ultrasonic waves. For example, the number of lines may be set to about 10 to 15 lines. In the figure, five lines are drawn without illustration. The number of columns in the array can be determined according to the spread of the scanning range. The number of columns may be set to 128 columns or 256 columns, for example. In the figure, there are omitted and 8 columns are drawn. The roles of the upper electrodes 33 and 38 and the lower electrodes 34 and 39 may be interchanged. That is, while the lower electrode is commonly connected to the elements 23 and 24 of the entire matrix, the upper electrode may be commonly connected to each column of the array.

  The outline of the base body 21 has a first side 21a and a second side 21b that are partitioned by a pair of parallel lines and face each other. One line of the first terminal array 46 a is arranged between the first side 21 a and the outline of the element array 22. One line of the second terminal array 46 b is arranged between the second side 21 b and the outline of the element array 22. The first terminal array 46a can form one line parallel to the first side 21a. The second terminal array 46b can form one line parallel to the second side 21b. The first terminal array 46 a includes a pair of upper electrode terminals 47 and a plurality of lower electrode terminals 48. The upper electrode terminal 47 and the lower electrode terminal 48 are formed on the same plane of the lower step surface 27. Similarly, the second terminal array 46 b includes a pair of upper electrode terminals 49 and a plurality of lower electrode terminals 51. The upper electrode terminal 49 and the lower electrode terminal 51 are formed on the same plane of the lower step surface 27. Upper electrode terminals 47 and 49 are connected to both ends of one lead wire 45, respectively. The lead wiring 45 and the upper electrode terminals 47 and 49 may be formed symmetrically with respect to a vertical plane that bisects the element array 22. Lower electrode terminals 48 and 51 are connected to both ends of the first conductor 42 and the second conductor 43, respectively. The first conductor 42, the second conductor 43, and the lower electrode terminals 48, 51 may be formed in plane symmetry on a vertical plane that bisects the element array 22. Here, the outline of the base 21 is formed in a rectangular shape. The outline of the base 21 may be square or trapezoidal.

  A first flexible printed wiring board (hereinafter referred to as “first wiring board”) 52 a is connected to the base body 21. The first wiring board 52a covers the first terminal array 46a. Conductive lines, that is, first signal lines 53 are formed at one end of the first wiring board 52a corresponding to the upper electrode terminal 47 and the lower electrode terminal 48, respectively. The first signal lines 53 are individually faced and joined to the upper electrode terminal 47 and the lower electrode terminal 48, respectively. Similarly, the base 21 is covered with a second flexible printed wiring board (hereinafter referred to as “second wiring board”) 52b. The second wiring board 52b covers the second terminal array 46b. Conductive lines, that is, second signal lines 54 are formed at one end of the second wiring board 52 b corresponding to the upper electrode terminal 49 and the lower electrode terminal 51 individually. The second signal line 54 is individually faced and joined to the upper electrode terminal 49 and the lower electrode terminal 51.

  As shown in FIG. 4, the base 21 includes a substrate 55 and a continuous film 56. The substrate 55 is made of, for example, silicon (Si). An upper step surface 57 and a lower step surface 58 having steps are formed on the surface of the substrate 55. In the substrate 55, a first opening 59 a is formed for each individual first element 23, and a second opening 59 b is formed for each individual second element 24. The first opening 59 a and the second opening 59 b are arranged in an array with respect to the substrate 55. The outline of the region where the first opening 59 a and the second opening 59 b are arranged corresponds to the outline of the element array 22.

A continuous film 56 is formed on the entire surface of the substrate 55. The continuous film 56 is continuous with each other on the upper surface 57 and the lower surface 58. The continuous film 56 includes a silicon oxide (SiO ₂ ) layer 56 a stacked on the surface of the substrate 55 and a zirconium oxide (ZrO ₂ ) layer 56 b stacked on the surface of the silicon oxide layer 56 a. The continuous film 56 is in contact with the first opening 59a and the second opening 59b. In this way, a part of the continuous film 56 forms the first vibration film 31 and the second vibration film 36 corresponding to the contours of the first opening 59a and the second opening 59b, respectively. The first vibration film 31 and the second vibration film 36 are portions of the continuous film 56 that can undergo film vibration in the thickness direction of the substrate 55 because they face the first opening 59a and the second opening 59b.

  The silicon oxide layer 56 a has a uniform film thickness on the upper step surface 57 and the lower step surface 58. Similarly, the zirconium oxide layer 56 b has a uniform film thickness on the upper step surface 57 and the lower step surface 58. As a result, the upper step surface 26 and the lower step surface 27 appear on the surface of the continuous film 56, that is, the surface of the substrate 21, following the upper step surface 57 and the lower step surface 58 of the substrate 55. The film thickness of the silicon oxide layer 56a is about 0.1 to 3.0 μm. The thickness of the zirconium oxide layer 56b is about 0.1 to 1.0 μm.

  A first conductor 42, a piezoelectric film 35, and a third conductor 44 are sequentially stacked on the surface of the first vibration film 31. The piezoelectric film 35 can be formed of, for example, lead zirconate titanate (PZT). Other piezoelectric materials may be used for the piezoelectric film 35. The piezoelectric film 35 covers at least a part of the lower electrode 34 and a part of the first vibration film 31. The upper electrode 33 covers at least a part of the piezoelectric film 35. Here, the piezoelectric film 35 completely covers the surface of the first conductor 42 under the third conductor 44. A short circuit between the first conductor 42 and the third conductor 44 can be avoided by the action of the piezoelectric film 35.

  Similarly, the second conductor 43, the piezoelectric film 41, and the third conductor 44 are sequentially stacked on the surface of the second vibration film 36. The piezoelectric film 41 can be formed of, for example, lead zirconate titanate (PZT). Other piezoelectric materials may be used for the piezoelectric film 41. The piezoelectric film 41 covers at least part of the lower electrode 39 and part of the second vibration film 36. The upper electrode 38 covers at least a part of the piezoelectric film 41. Here, the upper step surface 57 completely covers the surface of the second conductor 43 under the third conductor 44. A short circuit between the second conductor 43 and the third conductor 44 can be avoided by the action of the piezoelectric film 35.

Here, the lower electrode 34 of the first piezoelectric element 32 and the lower electrode 39 of the second piezoelectric element 37 are formed of the same material. Moreover, the thickness t _L1 of the lower electrode 34 of the first piezoelectric element 32 is equal to the thickness t _L2 of the lower electrode 39 of the second piezoelectric element 37. The thicknesses t _L1 and t _L2 are, for example, about 0.1 to 1.0 μm. The piezoelectric film 35 of the first piezoelectric element 32 and the piezoelectric film 41 of the second piezoelectric element 37 are formed from the same material. The thickness t _P1 of the piezoelectric film 35 of the first piezoelectric element 32 and the thickness t _P2 of the piezoelectric film 41 of the second piezoelectric element 37 are equal. The thicknesses t _P1 and t _P2 are on the order of several μm, for example. Further, since the upper electrode 33 of the first piezoelectric element 32 and the upper electrode 38 of the second piezoelectric element 37 are formed in common by the third conductor 44, the upper electrode 33 and the upper electrode 38 are made of the same material. Have the same film thickness. The film thickness of the upper electrodes 33 and 38 is on the order of several tens of nm.

  An acoustic matching layer 61 is laminated on the surface of the base 21. For example, the acoustic matching layer 61 covers the entire surface of the base 21 over the entire surface. As a result, the element array 22, the first terminal array 46a, the second terminal array 46b, the first wiring board 52a, and the second wiring board 52b are covered with the acoustic matching layer 61. The acoustic matching layer 61 covers the first element 23 and the second element 24. The first vibration film 31, the first piezoelectric element 32, the second vibration film 36, and the second piezoelectric element 37 are in close contact with the acoustic matching layer 61 without a gap. For example, a silicone resin film can be used for the acoustic matching layer 61. The acoustic matching layer 61 protects the structure of the element array 22, the bonding between the first terminal array 46a and the first wiring board 52a, and the bonding between the second terminal array 46b and the second wiring board 52b.

  The acoustic matching layer 61 has a flat upper surface. The first upper surface of the first vibration film 31 is separated from the upper surface 61a of the acoustic matching layer 61 by a first distance D1. The first distance D1 corresponds to the film thickness of the acoustic matching layer 61 on the first vibration film 31. Therefore, the first distance D1 is determined according to the first frequency that is the resonance frequency of the first vibrating membrane 31. Here, the first distance D1 is set to an integral multiple of a quarter of the wavelength of the first frequency. The second upper surface of the second vibration film 36 is separated from the upper surface of the acoustic matching layer 61 by a second distance D2. The second distance D2 corresponds to the film thickness of the acoustic matching layer 61 on the second vibration film 36. The second distance D2 is determined according to the second frequency that is the resonance frequency of the second vibrating membrane 36. Here, the second distance D2 is set to an integral multiple of a quarter of the wavelength of the second frequency. The second distance D2 is smaller than the first distance D1. Since the resonance frequency of the second vibration film 36 corresponds to a harmonic of the resonance frequency of the first vibration film 31, the difference between the first distance D1 and the second distance D2 is a quarter of the wavelength of the second frequency. Matches an integer multiple.

  An acoustic lens 62 is laminated on the acoustic matching layer 61. The acoustic lens 62 is in close contact with the surface of the acoustic matching layer 61. The outer surface of the acoustic lens 62 is formed as a partial cylindrical surface. The partial cylindrical surface has a bus parallel to the first conductor 42 and the second conductor 43. The curvature of the partial cylindrical surface is determined according to the focal position of the ultrasonic wave transmitted from one row of the elements 23 and 24 connected to the first conductor 42 or the second conductor 43 of one line. The acoustic lens 62 is made of, for example, a silicone resin.

  A reinforcing plate 63 is fixed to the back surface of the base 21. The back surface of the base 21 is overlaid on the surface of the reinforcing plate 63. The reinforcing plate 63 closes the first opening 59 a and the second opening 59 n on the back surface of the ultrasonic device 17. The reinforcing plate 63 can include a rigid base material. The reinforcing plate 63 can be formed from, for example, a silicon substrate. The plate thickness of the base 21 is set to about 100 to 300 μm, for example, and the plate thickness of the reinforcing plate 63 is set to about 100 to 150 μm, for example. An adhesive can be used for bonding.

  As shown in FIG. 5, the first opening 59a has a length L1 that is larger in the column direction (second direction) DR2 than the length W1 in the row direction (first direction) DR1. That is, the first opening 59a is partitioned into a rectangle that is long in the column direction DR2. Accordingly, the first opening 59a has the first aspect ratio (= L1 / W1). The first aspect ratio is greater than 1.

  The second opening 59b has a length L2 in the column direction DR2 that is greater than or equal to the length W2 in the row direction DR1. Here, the length W2 in the row direction DR1 is equal to the length L2 in the column direction DR2. That is, the second opening 59b is partitioned into a square. The second opening 59b has a second aspect ratio (= L2 / W2) that is smaller than the first aspect ratio. Here, the second aspect ratio is set to 1. However, the second aspect ratio may be other than 1. In the row direction DR1, the length W2 of the second opening 59b is set equal to the length W1 of the first opening 59a.

  The first opening 59a and the second opening 59b form a column in the row direction DR1. In the column, the first openings 59a and the second openings 59b are alternately arranged in the row direction DR1. The first openings 59a are arranged at an equal pitch with a first pitch P1 in the row direction DR1. Similarly, the second openings 59b are arranged at an equal pitch with the second pitch P2 in the row direction DR1. The first pitch P1 and the second pitch P2 are equal to each other. The first openings 59a are arranged at an equal pitch with a pitch EP1 in the row direction DR2, and the second openings 59b are similarly arranged at an equal pitch with a pitch EP2 in the row direction DR2. The pitch EP1 and the pitch EP2 are equal to each other.

(3) Operation of Ultrasonic Diagnostic Device Next, the operation of the ultrasonic diagnostic device 11 will be briefly described. When transmitting ultrasonic waves, the first piezoelectric element 32 is supplied with a pulse signal having a first frequency. The pulse signal is supplied to the first element 23 for each column through the lower electrode terminals 48 and 51 connected to the first conductor 42 and the upper electrode terminals 47 and 49 connected to the third conductor 44. In each of the first elements 23, an electric field acts on the piezoelectric film 35 between the lower electrode 34 and the upper electrode 33. The piezoelectric film 35 vibrates with ultrasonic waves having the first frequency. The vibration of the piezoelectric film 35 is transmitted to the first vibration film 31. The first vibrating membrane 31 resonates with the first frequency ultrasonic wave. Vibration is enhanced. Thus, the first vibration film 31 vibrates ultrasonically. As a result, a desired ultrasonic beam is emitted toward the subject (for example, inside the human body).

  The reflected ultrasonic wave is transmitted through the acoustic matching layer 61 to vibrate the first vibration film 31 and the second vibration film 36. The first vibration film 31 vibrates ultrasonically at a resonance frequency of the first frequency. The second vibration film 36 vibrates ultrasonically at the resonance frequency of the second frequency. The piezoelectric effect is exhibited by the first piezoelectric element 32 and the second piezoelectric element 37 in accordance with the vibration of the first vibration film 31 and the second vibration film 36. In each of the first element 23 and the second element 24, a potential is generated between the upper electrodes 33 and 38 and the lower electrodes 34 and 39. The electromotive voltages are taken out as electrical signals by the first piezoelectric element 32 and the second piezoelectric element 37, respectively. Thus, the first vibrating membrane 31 and the second vibrating membrane 36 receive ultrasonic waves having different frequencies. Since the film thickness of the acoustic matching layer 61 is set for each resonance frequency of the vibration film, acoustic coupling can be realized with high accuracy for each frequency of the ultrasonic wave. In this way, when the first frequency ultrasonic wave is transmitted toward the subject, the reflected ultrasonic wave includes the harmonic component (second frequency) in addition to the first frequency ultrasonic component. Therefore, if the second frequency ultrasonic wave is received in addition to the first frequency ultrasonic wave, the sensitivity of the ultrasonic device 17 is increased.

  Transmission and reception of ultrasonic waves are repeated. As a result, linear scan and sector scan are realized. When the scan is completed, an image is formed based on the digital signal of the output signal. The formed image is displayed on the screen of the display panel 15.

  In the ultrasonic device 17, the frequency of ultrasonic waves transmitted to the first vibration film 31 and the second vibration film 36 is adjusted according to the film thickness of the acoustic matching layer 61 (= first distance D 1 and second distance D 2). Thus, the first vibrating membrane 31 and the second vibrating membrane 36 receive ultrasonic waves having different frequencies. Since the surface of the continuous film 56 can be processed with high accuracy on the surface of the substrate 55, the first distance D1 and the second distance D2 can be ensured with high precision in the first vibration film 31 and the second vibration film 36. it can. Acoustic coupling can be realized with high accuracy for each ultrasonic frequency.

  As described above, the lower electrode 34 of the first piezoelectric element 32 and the lower electrode 39 of the second piezoelectric element 37 are made of the same material and have the same thickness. Therefore, the lower electrode 34 of the first piezoelectric element 32 and the lower electrode 39 of the second piezoelectric element 37 can be formed in the same manufacturing process. Similarly, the upper electrode 33 of the first piezoelectric element 32 and the upper electrode 38 of the second piezoelectric element 37 are made of the same material and have the same thickness. Therefore, the upper electrode 33 of the first piezoelectric element 32 and the upper electrode 38 of the second piezoelectric element 37 can be formed in the same manufacturing process. Further, the piezoelectric film 35 of the first piezoelectric element 32 and the piezoelectric film 41 of the second piezoelectric element 37 are made of the same material and have the same thickness. The piezoelectric film 35 of the first piezoelectric element 32 and the piezoelectric film 41 of the second piezoelectric element 37 can be formed in the same manufacturing process. In any case, complication of the manufacturing process can be avoided. In addition, the continuous film 56 has a uniform film thickness in the first vibration film 31 and the second vibration film 36. The continuous film 56 can be formed uniformly. The uniform continuous film 56 can be formed with relative ease and accuracy.

  As will be described later, in the ultrasonic device 17, for example, a semiconductor process technique can be used for forming the first opening 59a and the second opening 59b. Since the first opening 59a and the second opening 59b have the same lengths W1 and W2 in the row direction DR1, the occurrence of density in the array pattern of the first opening 59a and the second opening 59b is suppressed as much as possible. be able to. Therefore, a dimensional error of the first opening 59a and the second opening 59b, that is, a dimensional error of the first vibration film 31 and the second vibration film 36 can be avoided. In addition, since the first openings 59a and the second openings 59b are arranged at an equal pitch in the row direction DR1, the density of the layout pattern can be reliably avoided. Since the aspect ratio of the second opening 59b is 1, the sensitivity of the second vibration film 36 is increased.

  In the ultrasonic device 17, the upper electrodes 33 and 38 are commonly connected by the third conductor 44 in the first piezoelectric element 32 and the second piezoelectric element 37 for each column. Electric power is commonly supplied to the first piezoelectric element 32 and the second piezoelectric element 37 for each column. Therefore, the first vibration film 31 and the second vibration film 36 can operate for each column.

(4) Method for Manufacturing Ultrasonic Device Next, a method for manufacturing the ultrasonic device 17 will be briefly described. A substrate 71 is prepared. The substrate 71 is made of, for example, silicon. As shown in FIG. 6, a pattern of a photoresist 72 is formed on the surface (first surface) 71 a of the substrate 71. The pattern is shaped like the upper surface 57. Etching is performed on the surface 71 a of the substrate 71. As shown in FIG. 7, the surface 71 a of the substrate 71 is engraved to form an upper step surface 73 and a lower step surface 74 having steps. According to the photolithography technique, the upper step surface 73 and the lower step surface 74 can be accurately formed in a plane and parallel to each other.

  As shown in FIG. 8, for example, heat treatment is performed on the surface of the substrate 71 to form an oxide film. The silicon of the substrate 71 is oxidized to form silicon oxide. The oxide film has a uniform film thickness. Thus, the substrate 71 to the substrate 55 and the silicon oxide layer 56a are formed. Since the upper step surface 73 and the lower step surface 74 are oxidized as they are, the surface of the silicon oxide layer 56a can maintain a flat surface and parallelism with high accuracy. Thus, the upper step surface 57 and the lower step surface 58 are established on the surface of the substrate 55.

  Thereafter, as shown in FIG. 9, a zirconium oxide layer 56b is formed on the entire surface of the silicon oxide layer 56a. For example, sputtering is used. A zirconium film is formed with a uniform film thickness. The zirconium film is oxidized. Thus, the zirconium oxide layer 56b is formed with a uniform film thickness. The continuous film 56 is established by stacking the silicon oxide layer 56a and the zirconium oxide layer 56b. The surface of the zirconium oxide layer 56b reflects the surface shape of the planar silicon oxide layer 56a. Thus, the surface of the continuous film 56 on the surface of the substrate 55 can be processed with high accuracy.

  Thereafter, as shown in FIG. 10, the first piezoelectric element 32 and the second piezoelectric element 37 are formed on the surface of the continuous film 56. For example, a conductive material layer 75 is formed on the entire surface of the zirconium oxide layer 56b. For example, sputtering is used. The material layer 75 is formed with a uniform film thickness. A pattern of a photoresist 76 is formed on the surface of the material layer 75. The pattern represents the shape of the first conductor 42 and the second conductor 43. Etching is performed from the surface of the material layer 75. As a result, the first conductor 42 and the second conductor 43 are formed from the material layer 75. Since the first conductor 42 and the second conductor 43 are formed of a common material layer, the lower electrode 34 of the first piezoelectric element 32 and the lower electrode 39 of the second piezoelectric element 37 are the same material. Have the same thickness. Thus, the lower electrodes 34 and 39 are formed in the same manufacturing process. The complexity of the manufacturing process is avoided.

  Similarly, piezoelectric films 35 and 41 and upper electrodes 33 and 38 are formed on the surface of the continuous film 56. Both are formed from a common material layer. Etching is performed according to the pattern of the photoresist. Therefore, the piezoelectric film 35 and the upper electrode 33 of the first piezoelectric element 32 and the piezoelectric film 41 and the upper electrode 38 of the second piezoelectric element 37 are made of the same material and have the same thickness. Thus, the piezoelectric films 35 and 41 and the upper electrodes 33 and 38 are formed in the same manufacturing process. The complexity of the manufacturing process is avoided.

  Thus, in addition to the first piezoelectric element 32 and the second piezoelectric element 37, the first conductor 42, the second conductor 43, the third conductor 44, the upper electrode terminals 47 and 49, and the lower electrode terminals 48 and 51 are formed. As shown in FIG. 11, the first opening 59 a and the second opening 59 b are formed in the substrate 55 from the back surface (second surface) 71 b of the substrate 71. The first opening 59a is formed from the back side of the lower step surface. The second opening 59b is formed from the back side of the upper surface. In the formation, the substrate 55 is exposed to the etching process from the back surface. A pattern of a photoresist 77 is formed on the back surface 71 b of the substrate 71. The pattern represents the outline of the first opening 59a and the second opening 59b. The back surface 71b of the substrate 71 is engraved outside the photoresist 77 in accordance with the etching process. At this time, the silicon oxide layer 56a functions as an etching stop layer. As a result, the first vibration film 31 and the second vibration film 36 are established on the continuous film 56 by the first opening 59a and the second opening 59b. In carrying out such a semiconductor process technology, the first opening 59a and the second opening 59b have the same lengths W1 and W2 in the row direction DR1 as described above. The generation of density in the array pattern can be suppressed as much as possible. Therefore, a dimensional error of the first opening 59a and the second opening 59b, that is, a dimensional error of the first vibration film 31 and the second vibration film 36 can be avoided. In addition, since the first openings 59a and the second openings 59b are arranged at an equal pitch in the row direction DR1, the density of the layout pattern can be reliably avoided.

  Thereafter, the first wiring board 52 a and the second wiring board 52 b are joined to the substrate 55. When the first wiring board 52 a and the second wiring board 52 b are mounted, the reinforcing plate 63 is joined to the back surface 71 b of the substrate 71. Subsequently, the acoustic lens 62 is bonded to the surface of the continuous film 56. In adhering the acoustic lens 62, the material of the acoustic matching layer 61 is applied to the surface of the continuous film 56. For coating, for example, spin coating is used. The fluid material is cured to form the acoustic matching layer 61. The surface of the acoustic matching layer 61 is easily planarized. The acoustic matching layer 61 covers the first piezoelectric element 32 and the second piezoelectric element 37. In this way, the ultrasonic device 17 is manufactured.

(5) Configuration of Ultrasonic Device According to Second Embodiment FIG. 12 schematically shows an enlarged partial plan view of an ultrasonic device 17a according to the second embodiment. In the ultrasonic device 17a, the first elements 23 and the second elements 24 are arranged in a staggered arrangement. In the zigzag arrangement, the even-numbered second element group 24 may be staggered with respect to the odd-numbered first element group 23. Here, the third conductors 44 a and 44 b can have a width corresponding to the size of the corresponding first element 23 and second element 24. The width of the third conductor 44b connected to the second element 24 is smaller than the width of the third conductor 44a connected to the first element 23. At this time, the insulating film 81 is sandwiched between the first conductor 42 and the third conductor 44a in the first element group 23 in one row. The insulating film 81 separates the third conductor 44 a from the first conductor 42. Similarly, in the second element 24 group in one row, the insulating film 82 is sandwiched between the second conductor 43 and the third conductor 44b. The insulating film 82 separates the third conductor 44b from the second conductor 43. Thus, a short circuit is avoided. Other configurations are the same as those of the first embodiment. As shown in FIG. 13, the lengths L1, W1, L2, and W2 and the pitches P1, P2, EP1, and EP2 of the first opening 59a and the second opening 59b are the same as those in the first embodiment.

(6) Configuration of Ultrasonic Device According to Third Embodiment FIG. 14 schematically shows an enlarged partial plan view of an ultrasonic device 17b according to the third embodiment. In the ultrasonic device 17b, the first element 23 and the second element 24 are collected for each row. The first elements 23 and the second elements 24 are alternately arranged in the column direction. The first element 23 and the second element 24 are connected to a common first conductor 42 for each column. In the device terminal 12, the output components of the first frequency and the second frequency are separated from the output signal based on, for example, Fourier transform. Other configurations are the same as those of the first embodiment or the second embodiment. As shown in FIG. 15, the lengths L1, W1, L2, and W2 and the pitches P1, P2, EP1, and EP2 of the first opening 59a and the second opening 59b are the same as those in the first embodiment. Here, the first opening 59a and the second opening 59b form a column in the column direction DR2.

(7) Configuration of Ultrasonic Device According to Fourth Embodiment FIG. 16 schematically shows an enlarged partial sectional view of an ultrasonic device 17c according to the fourth embodiment. The element array of the ultrasonic device 17c includes a first element 84, a second element 85, a third ultrasonic transducer element (hereinafter referred to as “third element”) 86 and a fourth ultrasonic transducer element (hereinafter referred to as “fourth element”). 87. The first to fourth elements 84 to 87 can be sequentially arranged in the column direction DR2 as in the third embodiment. The first element 84 to the fourth element for each column. 87 is connected to the common first conductor 42. In the base 21, a first opening 88a is formed for each first element 84, and a second opening 88b is formed for each second element 85. Thus, a third opening 88c is formed for each of the third elements 86, and a fourth opening 88d is formed for each of the fourth elements 87. Therefore, each continuous first film 56 has an individual first opening. A first vibrating membrane 89a is provided for each opening 88a. The second vibration film 89b is formed for each second opening 88b, the third vibration film 89c is formed for each third opening 88c, and the fourth vibration 88c is formed for each fourth opening 88d. The vibration film 89d is formed, the first opening 88a has a length L1 that is larger in the column direction DR2 than the length W1 in the row direction DR1, and the second opening 88b is longer than the length W1 in the row direction DR1. The column direction DR2 has a large length L2, the third opening 88c has a length L3 larger in the column direction DR2 than the length W1 in the row direction DR1, and the fourth opening 88d has a length in the row direction DR1. The first opening 88a to the fourth opening 88d have the same length W1 in the row direction DR1 in the row direction DR2 and have a length L4 in the column direction DR2. Compared to the length L1 of the portion 88a, the length L2 of the second opening 88b is In addition, the length L3 of the third opening 88c is smaller than the length L2 of the second opening 88b, and the length L4 of the fourth opening 88d is smaller than the length L3 of the third opening 88c. In other words, the aspect ratio (= L2 / W1) of the second opening 88b is smaller than the aspect ratio (= L1 / W1) of the first opening 88a, and the aspect ratio (= L2 / W1) of the second opening 88b. ) Has a smaller aspect ratio (= L3 / W1) of the third opening 88c, and an aspect ratio (= L4 / W4) of the fourth opening 88d than the aspect ratio (= L3 / W1) of the third opening 88c. W1) is small, and thus the first to fourth vibrating membranes 89a to 89d have a specific resonance frequency according to the size of the area, and thus the ultrasonic device 17c can realize a wide band of received ultrasonic signals. Other configuration is first It is the same as that of the embodiment to perform. The structures of the first to fourth elements 84 to 87 may be configured similarly to the first element 23 and the second element 24.

  In addition, as shown in FIG. 17, in setting the lengths L2 and L3 of the second opening 88b and the third opening 88c, the harmonic component of the resonance frequency of the first vibration film 89a may be referred to. In this case, the length L2 of the second opening 88b can be set based on the resonance frequency corresponding to the double harmonic, and the length L3 of the third opening 88c can be set to the triple harmonic. It can be set based on the corresponding resonance frequency. In this way, the ultrasound image can be further sharpened.

  Although the present embodiment has been described in detail as described above, it will be easily understood by those skilled in the art that many modifications can be made without departing 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, a term described with a different term having a broader meaning or the same meaning at least once in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings. Also, the configuration and operation of the wiring structure such as the ultrasonic diagnostic apparatus 11, the apparatus terminal 12, the ultrasonic probe 13, the display panel 15, and the elements 23 and 24 are not limited to those described in this embodiment, and various modifications are possible. Is possible.

DESCRIPTION OF SYMBOLS 11 Ultrasonic imaging device (ultrasonic diagnostic apparatus) as an electronic device, 12 Processing apparatus (apparatus terminal), 13 Probe (ultrasonic probe), 15 Display apparatus (display panel), 16 Case, 17 Ultrasonic device, 17a Ultrasonic device, 17b Ultrasonic device, 17c Ultrasonic device, 31 Vibration membrane (first vibration membrane), 36 Vibration membrane (second vibration membrane), 55 Substrate, 59a First opening, 59b Second opening, 88a First opening, 88b Second opening, 88c Second opening (third opening), 88d Second opening (fourth opening), 89a Vibration film (first vibration film), 89b Vibration film (first 2 vibration film), 89c vibration film (third vibration film), 89d vibration film (fourth vibration film), DR1 first direction (row direction), DR2 second direction (column direction), L1 length, L2 length , W1 It is, W2 length.

Claims (10)

A substrate having a plurality of first openings and a plurality of second openings arranged in an array;
A vibrating membrane formed corresponding to each of the first opening and the second opening, and closing the first opening or the second opening;
A piezoelectric element formed corresponding to each of the vibrating membranes,
The first opening has a first aspect ratio in which the aspect ratio obtained by dividing the length in the second direction intersecting the first direction by the length in the first direction is greater than 1 in plan view from the thickness direction of the substrate. Ratio
The second opening has the same length as the first opening in the first direction in the plan view, and has a second aspect ratio smaller than the first aspect ratio in the aspect ratio. Ultrasonic device featuring.   2. The ultrasonic device according to claim 1, wherein the first opening and the second opening are arranged in the second direction.   The ultrasonic device according to claim 1, wherein the first opening and the second opening are arranged in the first direction.   The ultrasonic device according to claim 1, wherein the first openings are arranged at an equal pitch in the first direction.   5. The ultrasonic device according to claim 1, wherein the second openings are arranged at an equal pitch in the first direction. 6.   The ultrasonic device according to any one of claims 1 to 5, wherein the aspect ratio of the second opening is 1.   The ultrasonic device according to claim 1, wherein the vibration film formed corresponding to the second opening is a vibration film formed corresponding to the first opening. An ultrasonic device having a resonance frequency at a frequency corresponding to a harmonic of the resonance frequency of   A probe comprising: the ultrasonic device according to claim 1; and a housing that supports the ultrasonic device.   An electronic apparatus comprising: the ultrasonic device according to claim 1; and a processing apparatus that is connected to the ultrasonic device and processes an output of the ultrasonic device.   An ultrasonic imaging apparatus comprising: the ultrasonic device according to claim 1; and a display device that displays an image generated from an output of the ultrasonic device.

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