JP2016015434A - Ultrasonic probe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic probe having a piezoelectric element which is excellent in adhesion between a vibrating plate and platinum and high in voltage resistance.SOLUTION: An ultrasonic probe includes: an element chip 17 and a housing for supporting the element chip 17. The element chip 17 includes a vibrating film 43, a bottom electrode 24, and a piezoelectric film 26 formed on the bottom electrode 24. The bottom electrode 24 is laminated on the vibrating film 43 via an adhesion film 24b. The bottom electrode 24 is made of platinum or an alloy containing platinum and the adhesion film 24b is made of titanium whose film thickness is 80Å or less.

Description

  The present invention relates to an ultrasonic probe.

  2. Description of the Related Art Ultrasonic diagnostic apparatuses that irradiate a living body with ultrasonic waves from an ultrasonic transducer element chip installed on an ultrasonic probe and analyze reflected waves are widely used. A piezoelectric element is often used for the ultrasonic transducer element chip. A piezoelectric element generally has a structure including a piezoelectric thin film made of a polycrystalline body, and an upper electrode and a lower electrode disposed with the piezoelectric thin film interposed therebetween.

A platinum film is directly formed on SiO ₂ as the lower electrode of the piezoelectric thin film. However, it is a well-known fact that with such a configuration, there is a problem in the adhesion between SiO ₂ and platinum. Peeling occurs between silicon oxide and platinum during the PZT film formation, the subsequent heat treatment, or the operation after completion. Patent Document 1 discloses a method for solving the above problems. According to this, titanium is inserted between platinum and the insulating material in order to improve the adhesion between the insulating material such as SiO ₂ and platinum.

Japanese Patent Publication No. 4-43435

  In the method described in Patent Document 1, protrusions are formed on the platinum surface during the formation of the piezoelectric thin film or during the subsequent heat treatment. This protrusion lowered the withstand voltage of the piezoelectric element. Therefore, an ultrasonic probe provided with a piezoelectric element having good adhesion between the diaphragm and platinum and high withstand voltage has been desired.

  The present invention has been made to solve the above-described problems, and can be realized as the following forms or application examples.

[Application Example 1]
An ultrasonic probe according to this application example, comprising: an ultrasonic transducer element chip; and a casing that supports the ultrasonic transducer element chip, wherein the ultrasonic transducer element chip is formed on a vibration film. And a piezoelectric thin film formed on the metal film, wherein the metal film is laminated on the vibration film via an adhesion film, and the metal film is platinum or an alloy containing platinum. The adhesion film is titanium having a thickness of 80 mm or less.

  According to this application example, in the ultrasonic probe, the casing supports the ultrasonic transducer element chip. The ultrasonic transducer element chip includes a vibration film, and a metal film is formed on the vibration film. A piezoelectric thin film is formed on the metal film. The metal film is platinum or an alloy containing platinum, and the adhesion film is titanium having a thickness of 80 mm or less. Thereby, the metal film can improve the adhesiveness with the vibration film, and the withstand voltage of the PZT film can be improved.

1 is a schematic perspective view of a configuration of an ultrasonic diagnostic apparatus according to a first embodiment. The structure | tissue side view which shows the structure of an ultrasonic probe. The schematic plan view which shows the structure of an element chip. The schematic side sectional view which shows the structure of an element chip. The schematic plan view which shows a reinforcement board. The principal part model enlarged view which shows a reinforcement board. The circuit diagram of an apparatus terminal and an ultrasonic probe. The schematic diagram for demonstrating the manufacturing method of an ultrasonic transducer element chip | tip. (A) is a model exploded view which shows the structure of a protection jig, (b) is a model sectional side view which shows the structure of a protection jig. FIG. 3 is a schematic side cross-sectional view showing a configuration of an element chip having a diaphragm having a laminated structure. FIG. 3 is a schematic side cross-sectional view showing a configuration of an element chip having a diaphragm having a laminated structure. The schematic diagram for demonstrating the manufacturing method of the ultrasonic transducer element chip | tip concerning 2nd Embodiment. The schematic diagram for demonstrating the manufacturing method of an ultrasonic transducer element chip | tip. The schematic plan view which shows the structure of the element chip | tip concerning 3rd Embodiment. FIG. 4A is a schematic plan view showing a structure of an ultrasonic transducer element, and FIG. 4B is a schematic side sectional view showing an essential part of the structure of the ultrasonic transducer element. The schematic plan view which shows the structure of an ultrasonic transducer element. The schematic diagram for demonstrating the manufacturing method of a piezoelectric element. The schematic diagram for demonstrating the manufacturing method of a piezoelectric element. The schematic diagram for demonstrating the manufacturing method of a piezoelectric element. The principal part schematic cross section which shows the structure of the piezoelectric element concerning a modification. The principal part schematic cross section which shows the structure of a piezoelectric element. The principal part schematic top view which shows the structure of a piezoelectric element. The principal part schematic top view which shows the structure of a piezoelectric element. The principal part schematic top view which shows the structure of a piezoelectric element. The principal part schematic top view which shows the structure of a piezoelectric element. (A) is a principal part schematic top view which shows the structure of a piezoelectric element, (b) is a principal part schematic side sectional view which shows the structure of a piezoelectric element. (A) is a principal part schematic top view which shows the structure of a piezoelectric element, (b) is a principal part schematic side sectional view which shows the structure of a piezoelectric element. The schematic diagram for demonstrating the manufacturing method of a piezoelectric element. The principal part schematic top view which shows the structure of a piezoelectric element. The principal part schematic top view which shows the structure of a piezoelectric element. (A) is a principal part schematic top view which shows the structure of a piezoelectric element, (b) is a principal part schematic side sectional view which shows the structure of a piezoelectric element. (A) is a principal part schematic top view which shows the structure of a piezoelectric element, (b) And (c) is a principal part schematic side sectional view which shows the structure of a piezoelectric element. The principal part schematic top view which shows the structure of a piezoelectric element. (A) is a principal part schematic top view which shows the structure of a piezoelectric element, (b) is a principal part schematic side sectional view which shows the structure of a piezoelectric element. The principal part schematic top view which shows the structure of a piezoelectric element. (A) And (b) is a principal part schematic top view which shows the structure of a piezoelectric element. The principal part schematic top view which shows the structure of a piezoelectric element. The principal part schematic top view which shows the structure of a piezoelectric element. (A) is a principal part schematic top view which shows the structure of a piezoelectric element, (b) And (c) is a principal part schematic side sectional view which shows the structure of a piezoelectric element. The principal part schematic top view which shows the structure of a piezoelectric element. (A) is a principal part schematic top view which shows the structure of a piezoelectric element, (b) is a principal part schematic side sectional view which shows the structure of a piezoelectric element. (A) And (b) is a principal part schematic sectional side view which shows the structure of a piezoelectric element. (A) is a principal part schematic top view which shows the structure of a piezoelectric element, (b) is a principal part schematic side sectional view which shows the structure of a piezoelectric element. (A) is a principal part schematic top view which shows the structure of a piezoelectric element, (b) is a principal part schematic side sectional view which shows the structure of a piezoelectric element. (A) is a principal part schematic top view which shows the structure of a piezoelectric element, (b) is a principal part schematic side sectional view which shows the structure of a piezoelectric element.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that this 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 as means for solving the present invention. It is not always essential.
(First embodiment)
In the present embodiment, a characteristic example of an ultrasonic diagnostic apparatus will be described with reference to FIGS.

(1) Overall Configuration of Ultrasonic Diagnostic Device FIG. 1 is a schematic perspective view showing the configuration of the ultrasonic diagnostic device. As shown in FIG. 1, the ultrasonic diagnostic apparatus 11 includes an apparatus terminal 12 and an ultrasonic probe 13 (probe). 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 15 (display device) 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, as will be described later, an image is generated based on the ultrasonic waves detected by the ultrasonic probe 13. The imaged detection result is displayed on the screen of the display panel 15.

  FIG. 2 is a tissue side view showing the configuration of the ultrasonic probe. As shown in FIG. 2, the ultrasonic probe 13 has a housing 16. An element chip 17 as an ultrasonic transducer element chip is accommodated 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 13b that is detachably connected to the probe body 13a. At this time, the element chip 17 can be incorporated into the housing 16 of the probe head 13b.

  FIG. 3 is a schematic plan view showing the configuration of the element chip. As shown in FIG. 3, the element chip 17 includes a substrate 21. An element array 22 is formed on the substrate 21. The element array 22 is composed of an array of piezoelectric elements 23 as ultrasonic transducer elements. The array is formed of a matrix having a plurality of rows and a plurality of columns. Each piezoelectric element 23 includes a piezoelectric element portion. The piezoelectric element portion includes a lower electrode 24 as a metal film, an upper electrode 25, and a piezoelectric film 26 as a piezoelectric thin film. A piezoelectric film 26 is sandwiched between the lower electrode 24 and the upper electrode 25 for each piezoelectric element 23.

  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 24a is assigned to each row of piezoelectric elements 23. One first conductor 24a is disposed in common on the piezoelectric film 26 of the piezoelectric elements 23 arranged in the row direction of the array. Both ends of the first conductor 24a are connected to a pair of lead wires 27, respectively. The lead wires 27 extend parallel to each other in the column direction of the array. Accordingly, all the first conductors 24a have the same length. Thus, the lower electrode 24 is commonly connected to the piezoelectric elements 23 of the entire matrix.

  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 piezoelectric elements 23. One second conductor 25a is disposed in common on the piezoelectric film 26 of the piezoelectric elements 23 arranged in the column direction of the array. Energization of the piezoelectric element 23 is switched for each column. Line scan and sector scan are realized according to such switching of energization. Since the piezoelectric elements 23 in one column output ultrasonic waves simultaneously, 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. In addition, a staggered arrangement may be established in the array. In the staggered arrangement, the even-numbered piezoelectric element 23 groups need only be shifted by half the row pitch with respect to the odd-numbered piezoelectric element 23 groups. The number of elements in one of the odd and even columns may be one less than the number of the other element. Furthermore, the roles of the lower electrode 24 and the upper electrode 25 may be interchanged. That is, while the upper electrode is commonly connected to the piezoelectric elements 23 of the entire matrix, the lower electrode may be commonly connected to the piezoelectric elements 23 for each column of the array.

  The outline of the substrate 21 has a first side 21 a and a second side 21 b that are separated by a pair of parallel straight lines 29 and face each other. In the peripheral region 31 extending between the contour of the element array 22 and the outer edge of the substrate 21, a first line array 32a of one line is disposed between the first side 21a and the contour of the element array 22, and the second side One line of the second terminal array 32 b is arranged between the edge 21 b and the outline 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 includes 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 wiring 27, respectively. The lead wiring 27 and the lower electrode terminals 33 and 35 may be formed symmetrically on a vertical plane that bisects the element array 22. Upper electrode terminals 34 and 36 are respectively connected to both ends of one second conductor 25a. The second conductor 25a and the upper electrode terminals 34 and 36 may be formed in plane symmetry on a vertical plane that bisects the element array 22. Here, the outline of the substrate 21 is formed in a rectangular shape. The outline of the substrate 21 may be square or trapezoidal.

  A first flexible board 37 as a first flexible printed board is connected to the board 21. The first flexible board 37 covers the first terminal array 32a. Conductive lines, that is, first signal lines 38 are formed at one end of the first flex 37 corresponding to the lower electrode terminal 33 and the upper electrode terminal 34, respectively. The first signal lines 38 are individually faced and joined to the lower electrode terminal 33 and the upper electrode terminal 34, respectively. Similarly, the substrate 21 is covered with a second flexible printed circuit 41 as a second flexible printed circuit board. The second flexible board 41 covers the second terminal array 32b. A conductive line, that is, a second signal line 42 is formed at one end of the second flex 41 corresponding to the lower electrode terminal 35 and the upper electrode terminal 36 individually. The second signal lines 42 are individually faced and joined to the lower electrode terminal 35 and the upper electrode terminal 36, respectively.

FIG. 4 is a schematic side sectional view showing the configuration of the element chip. As shown in FIG. 4, each piezoelectric element 23 has a vibration film 43. In constructing the vibration film 43, an opening 45 is formed in the base 44 of the substrate 21 for each piezoelectric element 23. The openings 45 are arranged in an array with respect to the base body 44. A flexible film 46 is formed on the entire surface of the substrate 44. The flexible film 46 includes a silicon oxide layer 47 (SiO ₂ ) stacked on the surface of the base 44 and an upper surface layer 48 stacked on the surface of the silicon oxide layer 47. For the upper surface layer 48, a silicon nitride film or zirconium oxide (ZrO ₂ ) can be used. In the present embodiment, for example, silicon nitride is used for the upper surface layer 48. Even if the upper surface layer 48 is not provided, the upper surface layer 48 may be omitted when elasticity is obtained in the vibration film 43. The flexible film 46 is in contact with the opening 45. Thus, a part of the flexible film 46 functions as the vibrating film 43 corresponding to the outline of the opening 45. The film thickness of the silicon oxide layer 47 is determined based on the resonance frequency.

  On the surface of the vibration film 43, the lower electrode 24, the piezoelectric film 26, and the upper electrode 25 are sequentially stacked. For the lower electrode 24, for example, a laminated film of titanium (Ti), iridium (Ir), platinum (Pt) and titanium (Ti) or a platinum film can be used. In the present embodiment, for example, a platinum film is used for the lower electrode 24, and the adhesion film 24 b is installed between the lower electrode 24 and the upper surface layer 48. A titanium film is used for the adhesion film 24b. Therefore, a laminated film of the adhesion film 24 b and the lower electrode 24 is provided on the upper surface layer 48. The lower electrode 24 is platinum or an alloy containing platinum, and the adhesion film 24b is titanium having a thickness of 80 mm or less. Titanium is a metal with good bonding properties to various metals including platinum. As a result, the lower electrode 24 can improve the adhesion with the flexible film 46.

  The piezoelectric film 26 can be formed of, for example, lead zirconate titanate (PZT). As the upper electrode 25, for example, iridium (Ir), platinum (Pt), titanium, gold, or a film in which these are combined can be used. In the present embodiment, for example, a laminated film of titanium and gold is used for the upper electrode 25. 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 between the upper electrode 25 and the lower electrode 24 can be avoided by the action of the piezoelectric film 26.

  A protective film 49 is laminated on the surface of the substrate 21. For example, the protective film 49 covers the entire surface of the substrate 21 over the entire surface. As a result, the element array 22, the first terminal array 32 a and the second terminal array 32 b, the first flex 37 and the second flex 41 are covered with the protective film 49. For example, a silicone resin film can be used as the protective film 49. The protective film 49 protects the structure of the element array 22, the junction between the first terminal array 32 a and the first flexible 37, and the junction between the second terminal array 32 b and the second flexible 41.

  A partition wall 51 is defined between the adjacent openings 45. The openings 45 are partitioned by a 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 each other. 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 sandwiched between the wall surfaces perpendicular to 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 base body 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 body 44. Since the base body 44 has a uniform thickness, the partition wall 51 can have a constant wall height H over its entire length. If the wall thickness t of the partition wall 51 is reduced, the arrangement density of the vibration film 43 is increased, which 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 increased. Thus, the interval between the openings 45 is set smaller than the depth of the openings 45.

  A reinforcing plate 52 (reinforcing member) is fixed to the back surface of the base 44. The back surface of the base 44 is overlaid on the surface of the reinforcing plate 52. The reinforcing plate 52 closes the opening 45 on the back surface of the element chip 17. The reinforcing plate 52 can include a rigid base material. The reinforcing plate 52 can be formed from, for example, a silicon substrate. The thickness of the base 44 is set to about 100 μm, for example, and the thickness of the reinforcing plate 52 is set to about 100 to 150 μm, for example. Here, the partition wall 51 is coupled to the reinforcing plate 52. The reinforcing plate 52 is joined to each partition wall 51 at at least one joining region. An adhesive may be used for bonding.

  A straight groove 53 (straight groove portion) is formed on the surface of the reinforcing plate 52. The groove 53 divides the surface of the reinforcing plate 52 into a plurality of flat surfaces 54. The plurality of planes 54 extend within one virtual plane HP. The back surface of the base body 44 spreads within 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 a square, a triangle, a semicircular shape, or other shapes.

  FIG. 5 is a schematic plan view showing a reinforcing plate. As shown in FIG. 5, the openings 45 form a row in the first direction D1. Concentric centroids 45b of the openings 45 are arranged at equal pitch on one straight line 56 in the first direction D1. Since the outline 45a of the opening 45 is formed by copying one shape, the openings 45 having the same shape are repeatedly arranged at a constant pitch. An outline 45a of the opening 45 is defined as a quadrangle, for example. 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 its entire length. At this time, the junction area of the partition wall 51 may be an area including the center position of the long side. In particular, the joining 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-bonded to the reinforcing plate 52 over the entire length between the openings 45 over the entire length of the long side. Furthermore, at least one junction region of the partition wall 51 can be arranged on each side of the quadrangle. The junction area of the partition wall 51 can surround the quadrangle without interruption. The partition wall 51 can be surface-bonded to the reinforcing plate 52 on the entire surface between the openings 45 over the entire circumference of the quadrilateral.

  The grooves 53 are arranged in the first direction D1 parallel to each other at a constant interval L. The groove 53 extends in a second direction D2 that intersects the first direction D1. Both ends of the groove 53 are opened at the end face 57a and the end face 57b of the reinforcing plate 52. One groove 53 crosses the outline 45a of the opening 45 in one column (here, one row) in order. 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 outline 45a of the opening 45 in the short side direction of the rectangle.

  FIG. 6 is a schematic enlarged view of an essential part showing a reinforcing plate. As shown in FIG. 6, the groove 53 forms a passage 58 a and a passage 58 b between the base body 44 and the reinforcing plate 52 between the flat surfaces 54. Thus, the space in the groove 53 communicates with the internal space of the opening 45. The passage 58 a and the passage 58 b ensure ventilation between the internal space of the opening 45 and the external space of the substrate 21. Since one groove 53 crosses the outline 45a of the openings 45 in one column (here, one row) in order in a direction perpendicular to the surface of the substrate 21, that is, in the thickness direction of the substrate 21, one after another. The openings 45 are connected by a passage 58a. Both ends of the groove 53 are opened at the end face 57a and the end face 57b of the reinforcing plate 52. Thus, the passage 58b is opened from the opening 45 at the row end to the outside of the outline of the substrate 21.

  The interval 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 maximum length of the line segments that cross the opening 45 in the direction in which the grooves 53 are arranged, that is, in the first direction D1. In other words, the opening width S corresponds to the interval between the parallel lines 59 circumscribing the outline 45 a of the opening 45. For each opening 45, a parallel line 59 circumscribing the outline 45a of the opening 45 is specified. The parallel line 59 extends in the second direction D2. If the opening widths S of the openings 45 are different from each other, the grooves 53 may be arranged at intervals L smaller than the minimum value of the opening width S. Here, the interval L between the grooves 53 is set to be one third or more of the opening width S of the opening 45 and smaller than one half.

(2) Circuit Configuration of Ultrasonic Diagnostic Device FIG. 7 is a circuit diagram of the device terminal and the ultrasonic probe. As shown in FIG. 7, the ultrasonic probe 13 is provided with an integrated circuit chip 55 connected to the element chip 17. The integrated circuit chip 55 includes a multiplexer 61 and a transmission / reception circuit 62. The multiplexer 61 includes a port group 61a on the element chip 17 side and a port group 61b on the transmission / reception 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 60. In this way, the port group 61a is connected to the element array 22. Here, a prescribed 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 piezoelectric elements 23 that are simultaneously output during scanning. The multiplexer 61 manages the interconnection between the port on the cable 14 side and the port on the element chip 17 side.

  The transmission / reception circuit 62 includes a specified number of changeover switches 64. Each changeover switch 64 is connected to a signal line 63. The transmission / reception circuit 62 includes a transmission path 65 and a reception path 66 for each changeover switch 64. A transmission path 65 and a 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 pulsar 67 is incorporated in the transmission path 65. The pulsar 67 outputs a pulse signal at a frequency corresponding to the resonance frequency of the vibration film 43. An amplifier 68, a low-pass filter 69 (LPF), and an analog-digital converter 71 (ADC) are incorporated in the reception path 66. The detection signals of the individual piezoelectric elements 23 are amplified and converted into digital signals.

  The transmission / reception circuit 62 includes a drive / reception circuit 72. The transmission path 65 and the reception path 66 are connected to the drive / reception circuit 72. The driving / receiving circuit 72 controls the pulsar 67 simultaneously according to the scanning mode. The driving / receiving circuit 72 receives a digital signal of the detection signal in accordance with the scanning mode. The driving / receiving circuit 72 is connected to the multiplexer 61 by a control line 73. The multiplexer 61 manages the interconnection based on the control signal supplied from the driving / receiving circuit 72.

  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 overall operation of the ultrasonic diagnostic apparatus 11 is controlled according to the processing of the processing circuit 74. The processing circuit 74 controls the driving / receiving circuit 72 in accordance with an instruction input from the user. The processing circuit 74 generates an image according to the detection signal of the piezoelectric element 23. An image is specified by drawing data.

  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 according to 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.

(3) Operation of Ultrasonic Diagnostic Device Next, the operation of the ultrasonic diagnostic device 11 will be briefly described. The processing circuit 74 instructs the driving / receiving circuit 72 to transmit and receive ultrasonic waves. The driving / receiving circuit 72 supplies a control signal to the multiplexer 61 and also supplies a driving signal to each pulsar 67. The pulsar 67 outputs a pulse signal in response to the supply of the drive signal. The multiplexer 61 connects the port of the port group 61a to the port of the port group 61b according to the instruction of the control signal. A pulse signal is supplied to the piezoelectric element 23 for each column through the lower electrode terminal 33, the lower electrode terminal 35, the upper electrode terminal 34, and the upper electrode terminal 36 according to the selection of the port. The vibration film 43 vibrates in response to the supply of the pulse signal. As a result, desired ultrasonic waves are emitted toward an object (for example, the inside of a human body).

  After transmission of the ultrasonic wave, the changeover switch 64 is switched. The multiplexer 61 maintains the port connection relationship. The changeover switch 64 establishes a connection between the reception path 66 and the signal line 63 instead of the connection between the transmission path 65 and the signal line 63. The ultrasonic reflected wave vibrates the vibration film 43. As a result, a detection signal is output from the piezoelectric element 23. The detection signal is converted into a digital signal and sent to the driving / receiving circuit 72.

  Transmission and reception of ultrasonic waves are repeated. In the repetition, the multiplexer 61 changes the connection relation of the ports. As a result, line scan and sector scan are realized. When the scan is completed, 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.

(4) Manufacturing Method of Ultrasonic Transducer Element Chip FIG. 8 is a schematic diagram for explaining a manufacturing method of the ultrasonic transducer element chip. As shown in FIG. 8A, the base 44 is thermally oxidized at 1200 ° C. with single crystal silicon having a plane orientation (110), and a silicon oxide layer 47 having a thickness of 5000 mm is formed on both sides of the base 44. Then, the upper surface layer 48 is formed on one surface of the base body 44. The upper surface layer 48 is formed, for example, by forming silicon nitride with a thickness of 1 μm by PECVD (plasma chemical vapor deposition) and performing heat treatment at 800 ° C. in a nitrogen atmosphere. Further, a photoresist is formed on both surfaces of the substrate 44, an opening is provided on the surface opposite to the side on which the upper surface layer 48 is provided, and the silicon oxide layer 47 is patterned with an aqueous solution of hydrofluoric acid and ammonium fluoride. 77 is formed. At this time, the depth direction of the opening 77, that is, the direction perpendicular to the paper surface is set as the <1-1 2> or <-1 1 2> direction.

  As shown in FIG. 8B, the adhesion film 24 b and the lower electrode 24 are formed on the upper surface layer 48. Sputtering is used to form titanium with a thickness of 50 mm and platinum with a thickness of 2000 mm in this order, and patterning is performed with an aqueous solution of aqua regia. Next, PZT is sputtered to a thickness of 3 μm as the piezoelectric film 26 and patterned with an aqueous hydrochloric acid solution. Next, the piezoelectric film 26 is formed. Using a sintered compact target in which lead oxide was added excessively to modified PZT mixed with niobium, high-frequency sputtering was performed without heating the substrate in an argon atmosphere to form a PZT film. Next, after patterning the PZT film, a heat treatment is performed at 700 ° C. in an oxygen atmosphere to form the piezoelectric film 26. Subsequently, the upper electrode 25 is formed by sputtering in a thickness of 50 mm of titanium and 2000 mm of gold in this order, and patterned with an aqueous solution of iodine and potassium iodide.

  Thereafter, the protective film 49 is formed with photosensitive polyimide to a thickness of 2 μm, the protective film in the electrode lead-out portion (not shown) is removed by development, and heat treatment is performed at 400 ° C. Next, the surface on the piezoelectric element side on which the protective film 49 is formed is protected with a jig. Subsequently, the base 44 is immersed in an aqueous potassium hydroxide solution, and a part of the base 44 which is a single crystal silicon substrate is removed from the opening 77 of the silicon oxide layer 47, and anisotropic etching is performed.

  As a result, an opening 45 is formed as shown in FIG. At this time, the plane orientation of the substrate 44 which is a single crystal silicon substrate is (110). The direction perpendicular to the paper surface is the depth direction of the opening 45. Since the depth direction of the opening 45 is the <1-1 2> or <-1 1 2> direction, the surface of the side wall forming the side in the depth direction of the opening 45 can be the (111) plane. When the potassium hydroxide aqueous solution is used, the ratio of the etching rate between the (110) plane and the (111) plane of single crystal silicon is about 300: 1. Therefore, a groove having a depth of 300 μm can be formed while suppressing side etching to about 1 μm, and the opening 45 is formed.

  In addition, after forming the opening 45 in a state where the protective film 49 is not attached, heat treatment may be performed again at 700 ° C. in an oxygen atmosphere, and a protective film may be further formed. This is because the piezoelectric characteristics can be further improved by performing heat treatment twice on the piezoelectric film 26 (PZT film). Although the detailed reason for this effect is not clear, it is presumed that the sintering of PZT constituting the piezoelectric film proceeds and its crystal grain size increases, and as a result, the piezoelectric strain constant increases.

  FIG. 9A is a schematic exploded view showing the configuration of the protective jig, and FIG. 9B is a schematic side sectional view showing the configuration of the protective jig. The protective jig 78 is a jig for protecting the surface on the piezoelectric element 23 side when the base 44 is anisotropically etched.

  As shown in FIG. 9, the protective jig 78 has an opening on one side, a bottomed cylindrical fixing frame 79 whose inner wall surface is threaded, and an O-ring 80, a base 44, and an O-ring 80. And a fixing ring 81 having a thread cut on the outer wall surface thereof is screwed into the inner wall of the fixing frame 79 to be fixed. At this time, the surface of the base 44 on which etching is performed is set to the opening side of the fixed frame 79. In the state shown in FIG. 9B, the substrate is immersed in an etching solution such as an aqueous potassium hydroxide solution. At this time, since the sealing ring 81, the O-ring 80, and the surface of the substrate 44 to be etched are sealed, the etching solution can be prevented from entering the piezoelectric element side of the substrate 44. As a material for the jig, for example, polypropylene can be used.

  After forming the piezoelectric element, by providing means for protecting the surface on this side and forming the opening 45 from the opposite surface, the element chip has a good yield even when using a thin diaphragm and PZT. 17 can be formed. In this embodiment, the means for protecting the surface on the piezoelectric element side is a jig, but the means is not limited to this, and other means such as a thick coating of photoresist may be used. good.

(Example 1)
Next, the relationship between the dimensions of the opening / electrode, the thickness / size of the piezoelectric film, the thickness of the diaphragm, etc. will be described.
The inventors first set the planar positional relationship between the opening 45, the lower electrode 24, the piezoelectric film 26 formed by PZT, and the upper electrode 25.

  First, the lower electrode 24, the piezoelectric film 26, and the upper electrode 25 were evaluated by performing the upper electrode forming process according to the manufacturing process.

  When comparing the case where the upper electrode 25 is larger than the lower electrode 24 and the case where the lower electrode 24 is larger than the upper electrode 25, the former has a leakage current between the upper and lower electrodes of about two orders of magnitude higher than the latter. I understood it. This is considered to be due to the large leakage current of the PZT film at the lower electrode end.

  Further, when the lower electrode 24 is larger than the upper electrode 25, the piezoelectric film 26 is larger than the lower electrode 24 and the piezoelectric film 26 is smaller than the lower electrode 24. While the film was turned up from the underlying vibration film 43, the latter could be formed without film peeling. This is considered to be because the adhesion between the piezoelectric film 26 and the vibration film 43 is insufficient. Therefore, from the above results, the magnitude relationship of upper electrode 25 ≦ piezoelectric film 26 <lower electrode 24 is established.

  That is, when the length of the upper electrode 25 in the first direction D1 is Lu, the length of the piezoelectric film 26 is Lp, and the length of the lower electrode 24 is L1, the magnitude relationship is Lu ≦ Lp <L1. When the length of the upper electrode 25 in the second direction D2 is Wu, the length of the piezoelectric film 26 is Wp, and the length of the lower electrode 24 is W1, the magnitude relationship is Wu ≦ Wp <W1. As a result, it was possible to configure the piezoelectric element 23 having no problem in the manufacturing process and suppressing the leakage current.

  Next, under the condition of Lu ≦ Lp <L1, the relationship with the length L of the opening 45 in the first direction D1 is optimized by examining the deformation amount of the vibration film 43 at the center of the opening 45. The experiment was conducted. The materials and thicknesses of the vibration film 43, the lower electrode 24, the piezoelectric film 26, and the upper electrode 25 are the same as those described above. The center of the piezoelectric element 23 is arranged at the center of the side in the first direction D1 so as to be symmetrical. The applied voltage between the lower electrode 24 and the upper electrode 25 was 30V. The results when L = 100 μm is fixed and Lu, Lp, and L1 are changed are shown in Table 1 below.

  As shown in Table 1 above, the size relationship between the opening 45 and the piezoelectric film 26 and the lower electrode 24 in the arrangement direction does not significantly affect the deformation amount of the vibration film 43. However, the magnitude relationship between the opening 45 and the upper electrode 25 affects the amount of deformation of the vibration film 43.

  As shown in the upper part of Table 1, when the length Lu of the upper electrode 25 is larger than the length L of the opening 45, the deformation amount of the vibration film 43 is small. As shown in the second to fourth stages of Table 1, when the length Lu of the upper electrode 25 is smaller than the length L of the opening 45, the deformation amount of the vibration film 43 is increased. From this result, it is considered that the vibration film 43 can be efficiently deformed if the deformed portion of the piezoelectric element 23 is accommodated in the opening 45. The planar positional relationship in such a state is that the length L of the opening 45> the length Lu of the upper electrode 25 in the first direction D1.

(Example 2)
In order to obtain knowledge about the material of the vibration film 43, in the structure of FIG. 8C, the material of the vibration film 43 was changed, and the deformation amount of the vibration film 43 at the center of the opening 45 was examined. The lower electrode 24 was not patterned at all, and was present on the entire surface of the substrate 44. As the conditions, the length L of the opening 45 in the first direction D1 is 100 μm, the length of the piezoelectric film 26 is Lp = 94 μm, the length of the upper electrode 25 is Lu = 88 μm, and the length of the opening 45 in the second direction D2 The thickness was W = 15 mm, the thickness of the piezoelectric film 26 was tp = 3 μm, the thickness tv = 1 μm of the vibration film 43, and the applied voltage between the upper and lower electrodes was 30V.

As a material of the vibration film 43, in addition to silicon silicon used in the above-described first embodiment, silicon oxide formed by a thermal oxidation method, silicon obtained by thermally diffusing boron by 10 ²¹ cm ⁻³ , and zirconium oxide formed by a sputtering method And five types of aluminum oxide were used. The results are shown in Table 2 below.

  From the following results, the deformation amount of the vibration film 43 increases as the Young's modulus of the vibration film 43 increases. This indicates that when the vibration film 43 has a small Young's modulus, when the vibration film 43 is deformed in the horizontal direction, the vibration film 43 is greatly expanded in the horizontal direction and the deformation in the vertical direction is not so large. . In order to efficiently deform the vibration film 43 and transmit ultrasonic waves, it is necessary to use the vibration film 43 having a large Young's modulus.

The above results indicate that zirconium oxide, nitrogen silicon, and aluminum oxide having a large Young's modulus are desirable as the diaphragm material. In addition, titanium nitride, aluminum nitride, boron nitride, tantalum nitride, tungsten nitride, zirconium nitride, silicon carbide, titanium carbide, tungsten carbide, and tantalum carbide have Young's modulus of 2 × 10 ¹¹ N / m ² or more, It can be said that this is a desirable material for the vibration film 43.

  Furthermore, other components may be added with the material as a main component, or a material containing two or more types of the material may be used. For example, a cemented carbide containing tungsten carbide as a main component and adding a small amount of titanium carbide, tartar, and cobalt, or using titanium carbide or titanium carbonitride as a main component, adding a small amount of impurities, and using cermet for the vibration film 43. good.

(Example 3)
FIG. 10 is a schematic side cross-sectional view showing a configuration of an element chip having a diaphragm having a laminated structure. As shown in FIG. 10, a silicon oxide layer 47, a silicon nitride layer 82, and a silicon oxide layer 83 are stacked on the base 44. The silicon nitride layer 82 is a material layer having a Young's modulus of 1 × 10 ¹¹ N / m ² or more, preferably 2 × 10 ¹¹ N / m ² or more, and is a silicon nitride layer similar to that of the first embodiment. The silicon oxide layer 83 was continuously formed after the silicon nitride layer 82 was formed in the PECVD apparatus in which the silicon nitride layer 82 was formed. Other elements are the same as those in the first embodiment. The vibration film 84 is constituted by the silicon oxide layer 47, the silicon nitride layer 82, and the silicon oxide layer 83.

  By providing the silicon oxide layer 83, the adhesion between the lower electrode 24 and the vibration film 84 was enhanced. In addition, since the stress applied to the piezoelectric film 26 that occurs during the heat treatment during the manufacturing process can be relaxed, the manufacturing yield can be improved. The vibration characteristics of the vibration film 84 when the silicon nitride layer 82 is 1 μm and the silicon oxide layer 83 is 1000 mm are the same as in the first embodiment, and the vibration characteristics of the vibration film 84 are not deteriorated by providing the silicon oxide layer 83. It was.

  In the present embodiment, it is desirable to apply the processing temperature at or after the formation of the piezoelectric film 26 at 710 ° C. or lower. This is because lead in the piezoelectric film 26 diffuses into the silicon oxide layer 83 of the vibration film 84 through the lower electrode 24. Usually, silicon oxide is in a solid state in this temperature range, but silicon oxide in which lead is diffused becomes liquid at 714 ° C. or more, and this is ejected to the outside to destroy the element chip 17. .

Example 4
FIG. 11 is a schematic cross-sectional side view showing a configuration of an element chip having a diaphragm having a laminated structure. This embodiment is different from the third embodiment in that an aluminum oxide layer 85 is inserted between the silicon oxide layer 83 and the lower electrode 24.

  As shown in FIG. 11, an aluminum oxide layer 85 is formed with a thickness of 1000 mm on the silicon nitride layer 82 and the silicon oxide layer 83 by a sputtering method, and the lower electrode 24 is formed from the upper part thereof. Other than that is the same as Example 3. The vibration film 86 is constituted by the silicon oxide layer 47, the silicon nitride layer 82, the silicon oxide layer 83, and the aluminum oxide layer 85.

  By forming the aluminum oxide layer 85, diffusion of lead in the PZT described in the third embodiment to the diaphragm is suppressed. As a result, even if a high temperature heat treatment at 710 ° C. or higher is performed, the element chip 17 can be prevented from being destroyed by the external ejection of the silicon oxide layer 83, and the manufacturing yield of the element chip 17 can be improved. Furthermore, since heat treatment can be performed efficiently at a high temperature of 710 ° C. or higher, the piezoelectric characteristics of the piezoelectric film 26 can be further improved, and the vibration characteristics of the piezoelectric element 23 can be improved.

  It has been found that the effect obtained by providing the aluminum oxide layer 85 can be obtained even when other materials are used. As a result of the experiment, effects other than the above-described aluminum oxide were confirmed in the same manner even when zirconium oxide, tin oxide, zinc oxide, and titanium oxide were used. Further, materials having these as the main components and added with additives, and materials having as a main component those containing two or more of these materials are also applicable. Furthermore, this effect was confirmed not only in the structure of the vibration film provided with the silicon oxide layer on the surface but also in the single crystal silicon vibration film mixed with boron.

(Example 5)
The present inventors conducted the following experiment in order to determine the configuration of the lower electrode 24.

  On the single crystal silicon substrate provided with the silicon oxide layer, titanium and platinum were successively formed as the lower electrode 24 in this order by the sputtering method. The thickness of platinum was changed to 2000 mm, and the thickness of titanium was changed from 50 mm to 1000 mm. Titanium is necessary for improving the adhesion between platinum as an electrode material and a silicon oxide layer as a diaphragm material.

  Then, PZT is formed to a thickness of 1 μm by the method shown in Example 1, heat treatment is performed at 600 ° C. for 4 hours in an oxygen atmosphere, and aluminum is mask-deposited to a size of 3 mm square as an upper electrode. Formed.

  In this sample, a voltage was applied between the upper and lower electrodes, and the withstand voltage characteristics of the piezoelectric film 26 were evaluated. Here, the definition of the withstand voltage of the piezoelectric film 26 is an applied voltage when a leak current flows 100 nA. The results are shown in Table 3.

The above results show that there is a correlation between the titanium film thickness and the withstand voltage of the piezoelectric film 26, and the withstand voltage increases as the titanium film thickness decreases. In addition, according to observations by the inventors, fine protrusions are formed on the platinum surface, and the density of the protrusions is increased as the titanium film thickness is increased. For example, it was observed that what was about 20000 pieces / mm ^{2 in} 50% titanium was about 210,000 pieces / mm ^{2 in} 200% titanium. From this, it is considered that the minute protrusions on the platinum surface formed by the heat treatment lower the withstand voltage of the piezoelectric film 26.

  By reducing the titanium film thickness from 100 to 80 mm, the withstand voltage of the PZT film was greatly improved from 18V to 30V. If the withstand voltage of the piezoelectric film 26 is improved, the applied voltage can be increased, and the vibration characteristics in the piezoelectric element 23 can be improved. In addition, the vibration film 43 can be vibrated even when the piezoelectric film 26 is thinned, and the productivity in manufacturing can be improved.

  As this withstand voltage value, if it is 10 V or less, it cannot be practically used, and even about 20 V is still insufficient, but if it greatly exceeds 20 V, it can be regarded as a practical region. According to the above experimental results, it can be seen that the withstand voltage of the PZT film is remarkably improved when the titanium film thickness is 80 mm or less. Therefore, it is desirable that the titanium film thickness is 80 mm or less, and the present inventors set the titanium film thickness to 50 mm in the above-described embodiments.

  In the above embodiment, platinum is used as the material for the lower electrode 24 provided on titanium having a thickness of 80 mm or less. However, this may be an alloy containing platinum. The inventors continuously formed an alloy of 50% titanium and 70at% platinum-30at% platinum on a single crystal silicon substrate provided with a silicon oxide layer by a sputtering method, and performed a heat treatment at 600 ° C. for 4 hours in an oxygen atmosphere. When the surface of the alloy after the heat treatment was observed with a microscope at a magnification of 800, no microprojections on the surface were observed. When a withstand voltage was measured by forming a PZT film in the same manner as in the above example, a result of 70 V was obtained, and further improvement in characteristics was observed.

  Further, the material of the vibration film 43 is not limited to single crystal silicon provided with a silicon oxide layer, and any material can be used as long as it is the material mentioned in the above-described embodiment.

(Effect of the invention)
As described above, in the element chip 17, titanium having a thickness of 80 mm or less is used as the adhesion film. Thereby, the lower electrode 24 can improve the adhesiveness with the vibration film 43, and the withstand voltage of the piezoelectric film 26 can be improved. Therefore, the element chip 17 is suitably used for the ultrasonic probe 13 that transmits ultrasonic waves.

(Second Embodiment)
Next, an embodiment of a piezoelectric element will be described with reference to FIG. This embodiment is different from the first embodiment in that a titanium layer is provided between the lower electrode 24 and the piezoelectric film 26. Note that description of the same points as in the first embodiment is omitted. Hereinafter, the piezoelectric element will be described in detail according to the manufacturing process.

  FIG. 12 is a schematic diagram for explaining a method of manufacturing the ultrasonic transducer element chip. In this schematic diagram, the direction perpendicular to the paper surface is the depth direction of the opening.

As shown in FIG. 12A, a base 44 made of single crystal silicon having a plane orientation of (110) is thermally oxidized at 1200 ° C. to form a silicon oxide layer 47 having a thickness of 5000 mm on both sides of the base 44. Then, boron is diffused from one side of the substrate 44 at 1000 ° C. to the substrate 44 located below the silicon oxide layer 47. As a result, a vibrating film 89 in which boron is diffused is formed in the base 44 made of single crystal silicon. The thickness of the vibration film 89 was 1 μm, and the concentration of boron was 10 ²⁰ cm ⁻³ (the number of boron atoms was 10 ²⁰ per cm ³ ). Further, a photoresist is formed on both surfaces of the substrate 44, and a mask is formed by patterning the photoresist on the side opposite to the side on which the vibration film 89 is provided. Then, the silicon oxide layer 47 is patterned with an aqueous solution of hydrofluoric acid and ammonium fluoride to form an opening 77. Next, the photoresist is peeled off. The depth direction of the opening 77, that is, the direction perpendicular to the paper surface is set as the <1 -1 2> or <-1 1 2> direction. Subsequently, the tantalum layer 93 containing oxygen, the lower electrode 90, the titanium layer 94 containing oxygen, and the piezoelectric film 91 are laminated in this order on the vibration film 89 side of the base 44. 600 tantalum metal tantalum is laminated on the silicon oxide layer 47 on the vibration film 89 side to form a tantalum layer 93. Next, as the lower electrode 90, 50% titanium and 2000% platinum are laminated on the adhesion layer. Subsequently, a titanium layer 94 having a thickness of 50 mm is formed by a sputtering method.

Next, as shown in FIG. 12B, the lower electrode 90 and the titanium layer 94 are patterned into a predetermined shape using a photolithography method and an etching method. Further, the piezoelectric film 91 is heated to a substrate in an argon atmosphere using a sintered body target having a thickness of 3 μm and a composition Pb _0.95 Sr _0.05 Zr _0.28 Ti _0.35 Mg _0.123 Nb _0.247 O ₃ (90 mol%) + PbO (10 mol%). High frequency sputtering film formation is performed without. Next, annealing is performed in an oxygen atmosphere at 650 ° C. for 1 hour + 900 ° C. for 1 hour. Through the above steps, the tantalum layer 93 containing oxygen, the lower electrode 90, the titanium layer 94 containing oxygen, and the piezoelectric film 91 were formed. Actually, after annealing at 650 ° C. for 1 hour + 900 ° C. for 1 hour in an oxygen atmosphere, the portion where the piezoelectric film 91 does not exist on the lower electrode 90 was analyzed by X-ray diffraction. Diffraction lines were observed, confirming the presence of a titanium layer 94 containing titanium dioxide.

  The piezoelectric film 91 is patterned with a borofluoric acid aqueous solution, and the lower electrode 90 is patterned with an aqua regia aqueous solution. Next, the upper electrode 92 is installed on the piezoelectric film 91. A titanium film having a thickness of 50 mm and a gold film having a thickness of 2000 mm are formed in this order by sputtering and patterned with an aqueous solution of iodine and potassium iodide. Subsequently, the protective film 49 is formed with a photosensitive polyimide to a thickness of 2 μm, the protective film in the electrode lead-out portion (not shown) is removed by development, and heat treatment is performed at 400 ° C.

  As shown in FIG. 12C, the surface on the piezoelectric element side on which the protective film 49 is formed is protected with a jig and immersed in an aqueous potassium hydroxide solution. An opening 45 is formed by anisotropically etching the single crystal silicon substrate 44 from the opening 77 of the silicon oxide layer 47. At this time, the plane orientation of the single crystal silicon substrate 44 is (110), and the depth direction of the opening 77 is the <1 -1 2> or <-1 1 2> direction. The side wall surface forming the side in the depth direction can be a (111) plane. When the potassium hydroxide aqueous solution is used, the ratio of the etching rate between the (110) plane and the (111) plane of single crystal silicon is about 300: 1, and the groove having a depth of 300 μm is formed with the side etching being suppressed to about 1 μm. And an opening 45 is formed. The piezoelectric element 95 is formed by the above process.

  In the element chip of the above example, the thickness of the metal titanium formed on the lower electrode 90 by sputtering was changed. In the manufacturing process, annealing was performed in an oxygen atmosphere at 650 ° C. for 1 hour + 900 ° C. for 1 hour, and observation was performed visually, with a metal microscope, and with a scanning electron microscope (SEM). The results are shown in Table 4.

  From the above results, it can be seen that by forming the titanium layer 94 containing titanium dioxide on the lower electrode 90, the adhesion between the piezoelectric film 91 and the lower electrode 90 is improved and the peeling phenomenon is eliminated. Further, when the thickness of the metal titanium is 200 mm, a cavity is formed in the lower part of the PZT. This is because the titanium layer 94 containing lead oxide and oxygen in the piezoelectric film 91 reacts and liquefies during annealing. It is thought to be caused. Therefore, it is desirable that the thickness of the titanium layer 94 containing titanium dioxide is not so thick. When titanium metal is annealed in an oxygen atmosphere at 650 ° C. for 1 hour + 900 ° C. for 1 hour, it has been confirmed by SEM observation by the present inventors that the film thickness is about twice that before annealing. The thickness of the titanium layer 94 contained is desirably 200 mm or less.

  The oxygen-containing titanium layer 94 may be a titanium alloy containing oxygen, such as a titanium-tantalum alloy, a titanium-nickel alloy, a titanium-platinum alloy, or the like.

  In addition, the constituent elements and materials of the piezoelectric element 95 are not limited to those in the above embodiment. For example, it is possible to further increase the thickness of the piezoelectric film 91, and the material is not limited to PZT having a specific composition, and the composition ratio and the type of additive may be changed. A multilayer structure may be used, and not only PZT but also a lead-containing material such as lead titanate may be used. Further, other methods such as a sol-gel method may be used as the production method. The lower electrode 90 may also use chromium, nickel, tungsten or the like for the adhesion layer, and the platinum layer may use a platinum-rhodium alloy, a platinum-iridium alloy, a platinum-titanium alloy, or the like. Further, the tantalum layer 93 containing oxygen may be formed suddenly by a chemical vapor deposition (CVD) method or a sputtering method using an oxide target. Further, the layer may contain a low-valent oxide such as a tantalum dioxide layer.

  The piezoelectric strain constant d31 is 150 pC / N for the piezoelectric film 91 when the titanium layer 94 containing titanium dioxide is not present on the lower electrode 90, whereas the piezoelectric strain constant d31 contains titanium dioxide on the lower electrode 90. When the titanium layer 94 is provided, the piezoelectric film 91 is as large as 170 pC / N, and the vibration characteristics of the vibration film 89 when the latter is used are also improved. The piezoelectric film 91 is made of PZT having the above composition after annealing at 650 ° C. for 1 hour + 900 ° C. for 1 hour in an oxygen atmosphere. Therefore, by providing the titanium layer 94 containing titanium dioxide, the piezoelectric strain constant d31 is increased, and the vibration characteristics of the vibration film 89 are improved.

(Modification 1)
Next, a modification of the piezoelectric element will be described with reference to FIG. This modification is different from the second embodiment in that zirconium oxide is used for the vibration film 89. Note that the description of the same points as in the second embodiment will be omitted. Hereinafter, the piezoelectric element will be described in detail according to the manufacturing process.

  FIG. 13 is a schematic diagram for explaining a method of manufacturing the ultrasonic transducer element chip. As shown in FIG. 13A, silicon oxide layers 47 are formed on both surfaces of a base 44 made of single crystal silicon having a plane orientation (110). Thereafter, the silicon oxide layer 47 on one side is patterned to form an opening 77 for forming the opening 45. Simultaneously with this step, the silicon oxide layer 47 on the surface opposite to the opening 77 is removed.

  As shown in FIG. 13B, a metal zirconium film is formed on the entire surface from which the silicon oxide layer 47 has been removed, and is thermally oxidized. Thereby, the vibration film 96 made of zirconium oxide is formed. The vibration film 96 made of zirconium oxide has a larger Young's modulus than the vibration film 89 made of silicon. Therefore, when the same voltage is applied to the piezoelectric film 91, the deformation amount and generated pressure of the vibration film 96 on the opening 45 are larger than those of the vibration film 89 when zirconium oxide is used. Therefore, the vibration characteristics of the vibration film 96 are also good.

  As a material of the vibration film 96, not only normal zirconium oxide (zirconia) but also stabilized zirconia to which yttrium or the like is added, alumina, aluminum nitride, zirconium nitride, or the like may be used, and a laminated structure thereof. Alternatively, the vibration film 96 may be formed.

  As shown in FIG. 13C, the lower electrode 90, the titanium layer 94, the piezoelectric film 91, the upper electrode 92, and the protective film 49 are provided on the vibration film 96 to form the piezoelectric element 97.

(Effect of the invention)
As described above, in the element chip according to the present invention, the titanium layer 94 that is titanium containing titanium dioxide or an alloy layer containing titanium is provided on the lower electrode 90. Desirably, the adhesiveness between the lower electrode 90 and the piezoelectric film 91 could be improved by setting the thickness of the titanium layer 94 to 200 mm or less.

(Third embodiment)
Next, an embodiment of an element chip will be described with reference to FIGS. The present embodiment is different from the first embodiment in that the piezoelectric film 26 of the piezoelectric element 23 includes a piezoelectric active portion where distortion occurs and a piezoelectric inactive portion where distortion does not occur. Note that description of the same points as in the first embodiment is omitted. Hereinafter, the piezoelectric element will be described in detail according to the manufacturing process.

  FIG. 14 is a schematic plan view showing the structure of the element chip. As shown in FIG. 14, the element chip 100 includes a rectangular base 101. One side of the outer periphery of the base 101 extends in the first direction D1, and the other side extends in the second direction D2. On the base 101, a lower electrode 102 and a lower electrode film 103 for wiring extending in the second direction D2 are provided. And the piezoelectric element 104 is installed across the lower electrode 102 and the lower electrode film 103 for wiring. Seven piezoelectric elements 104 are arranged in the second direction D2 along the lower electrode 102. The piezoelectric elements 104 are arranged in three rows in the first direction D1. Accordingly, 21 piezoelectric elements 104 are installed in the element chip 100. The number of piezoelectric elements 104 installed in one element chip 100 is not particularly limited.

  FIG. 15A is a schematic plan view showing the structure of the ultrasonic transducer element, and FIG. 15B is a schematic side sectional view showing the main part of the structure of the ultrasonic transducer element. FIG. 16 is a schematic plan view showing the structure of an ultrasonic transducer element.

  As shown in FIG. 15, an opening 105 is formed in the base 101 for each piezoelectric element 104. An elastic film 108 is installed on the base 101. The elastic film 108 is a film having a thickness of 1 to 2 μm made of silicon dioxide formed by thermal oxidation. A lower electrode 102 and a wiring lower electrode film 103 are provided on the elastic film 108. The thickness of the lower electrode 102 is about 0.5 μm, for example. The lower electrode 102 constituting the piezoelectric element 104 is continuously provided in a region facing the plurality of openings 105 arranged in parallel. The lower electrode 102 is patterned in the vicinity of one end of the opening 105 in the longitudinal direction. An end portion of the lower electrode 102 is an end portion of the piezoelectric active portion 106. Further, a lower electrode film 103 for wiring is provided for each opening 105 in a region facing the vicinity of the end of the other end in the longitudinal direction of the opening 105. The wiring lower electrode film 103 is disposed from the region facing the opening 105 to the peripheral wall, and is discontinuous with the lower electrode 102. The wiring lower electrode film 103 is used as a wiring of the piezoelectric element 104.

  It is preferable that the distance between the lower electrode 102 and the lower electrode film 103 for wiring and the distance between the lower electrode films 103 for wiring are formed with a narrow width so that at least the insulation strength can be maintained.

  A piezoelectric film 107 is disposed on the lower electrode 102 and the lower electrode film 103 for wiring, and an upper electrode 109 is disposed on the piezoelectric film 107. The thickness of the piezoelectric film 107 is about 1 μm, for example. The thickness of the upper electrode 109 is about 0.1 μm, for example.

  The piezoelectric element 104 refers to a portion including the lower electrode 102, the piezoelectric film 107, and the upper electrode 109. In general, one electrode of the piezoelectric element 104 is used as a common electrode, and the other electrode and the piezoelectric film 107 are patterned for each opening 105. In addition, here, a portion that is configured by any one of the patterned electrodes and the piezoelectric film 107 and in which piezoelectric distortion is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion 106. In this embodiment, the lower electrode 102 is a common electrode of the piezoelectric element 104, and the upper electrode 109 is an individual electrode of the piezoelectric element 104. However, there is no problem even if this is reversed for the convenience of the drive circuit and wiring. In any case, a piezoelectric active part is formed for each opening 105. Further, here, the piezoelectric element 104 and a vibration plate that is displaced by driving the piezoelectric element 104 are collectively referred to as a piezoelectric actuator.

  The piezoelectric film 107 and the upper electrode 109 are provided in a region facing the opening 105. One end portion of the upper electrode 109 extends to the lower electrode film 103 for wiring. The upper electrode 109 and the wiring lower electrode film 103 are connected by the lead electrode 110. Further, the shape of the lower electrode film 103 for wiring is not particularly limited, but is preferably formed so as to cover at least the edge of the opening 105 as shown in FIG. Thereby, the rigidity of the elastic film 108 is kept high, and the occurrence of cracks in the elastic film 108 can be prevented.

  Returning to FIG. 15, in such a configuration, the piezoelectric film 107 and the upper electrode 109 existing on the lower electrode 102 and the lower electrode 102 constitute the piezoelectric active portion 106. The piezoelectric element 104 where the lower electrode 102 is not installed is a piezoelectric inactive portion 111 that is not substantially driven. Therefore, the piezoelectric non-active part 111 includes a place which is continuously provided from the longitudinal end of the opening 105 and faces the lower electrode film 103 for wiring.

  Therefore, a portion of the piezoelectric element 104 located at a part of the boundary between the opening 105 and the peripheral wall is a piezoelectric inactive portion 111 that is not driven by voltage application to the piezoelectric active portion 106. . For this reason, there is no possibility of peeling of the piezoelectric film 107 and the like at the longitudinal end portion of the opening 105 and generation of cracks due to repeated displacement. Further, since the piezoelectric film 107 and the upper electrode 109 are extended to the lower electrode film 103 for wiring, it is not necessary to form a contact hole. That is, it is not necessary to form an insulator film for providing a contact hole on the upper electrode 109. Therefore, the displacement reduction due to the thickness of the insulator film of the piezoelectric active portion 106 is eliminated. Further, the manufacturing process can be reduced, and the cost can be reduced.

  Next, a process for forming a piezoelectric film or the like on the substrate 101 made of a silicon single crystal substrate will be described with reference to FIGS. 17 to 19 are schematic views for explaining a method for manufacturing a piezoelectric element. 17 and 19 are schematic cross-sectional views in the second direction D2, and FIG. 18 is a schematic cross-sectional view in the first direction D1.

  First, as shown in FIG. 17A, an elastic film 108 made of silicon dioxide is formed by thermally oxidizing a silicon single crystal substrate wafer to be the base 101 in a diffusion furnace at about 1100 ° C.

  Next, as shown in FIG. 17B, the lower electrode 102 is formed by sputtering. As a material of the lower electrode 102, platinum or the like is suitable. This is because the piezoelectric film 107 formed by the sputtering method or the sol-gel method needs to be crystallized by baking at a temperature of about 600 to 1000 ° C. in an air atmosphere or an oxygen atmosphere after the film formation. is there. That is, the material of the lower electrode 102 must be able to maintain conductivity under such a high temperature and oxidizing atmosphere. In particular, when lead zirconate titanate (PZT) is used as the piezoelectric film 107, it is desirable that there is little change in conductivity due to diffusion of lead oxide, and platinum is preferable for these reasons.

  Next, as shown in FIGS. 17C and 18, the lower electrode 102 is patterned to form the entire pattern, and the openings 105 are respectively formed in regions corresponding to the vicinity of one end in the longitudinal direction for each opening 105. A wiring lower electrode film 103 extending from the opposing region to the peripheral wall is formed.

  Next, as shown in FIG. 17D, a piezoelectric film 107 is formed. The piezoelectric film 107 is preferably crystal-oriented. For example, in the present embodiment, a so-called sol-gel method in which a so-called sol in which a metal organic material is dissolved and dispersed in a catalyst is applied, dried, gelled, and further fired at a high temperature to obtain a piezoelectric film 107 made of a metal oxide. Thus, the piezoelectric film 107 in which the crystals are oriented is obtained.

  In either the step of heating and crystallizing the amorphous thin film in the step of forming the piezoelectric film 107 or the heat treatment step provided after this step, the temperature is 700 ° C. in an atmosphere of 100% water. It is preferable to include a processing step of processing under a pressure of 200 atm or less.

  In the PZT thin film formed by the sol-gel method, the amount of oxygen in the PZT thin film can be controlled by including water in the degreasing atmosphere. Then, an oxide PZT thin film with few oxygen vacancies can be formed. Moreover, it is thought that the stress concerning the PZT thin film at the time of degreasing and after that can be relieved by including water in the atmosphere at the time of degreasing. For this reason, generation | occurrence | production of a crack can be suppressed. Further, since the oxide ceramic thin film is crystallized by hydrothermal treatment in water, the thin film and other materials are not affected. Therefore, a wide range of material selection can be performed, and a manufacturing method that does not affect the environment at low cost can be provided.

  As the material of the piezoelectric film 107, a lead zirconate titanate-based material is suitable. The method for forming the piezoelectric film 107 is not particularly limited. For example, the piezoelectric film 107 may be formed by a sputtering method.

  Further, after forming a lead zirconate titanate precursor film by a sol-gel method or a sputtering method, a method of crystal growth at a low temperature by a high pressure treatment method in an alkaline aqueous solution may be used.

  In any case, the piezoelectric film 107 formed in this way has crystals preferentially oriented unlike a bulk piezoelectric body, and in this embodiment, the piezoelectric film 107 is formed in a columnar shape. Has been. Note that the preferential orientation refers to a state in which the orientation direction of the crystal is not disordered and a specific crystal plane is oriented in a substantially constant direction. A columnar thin film refers to a state in which substantially cylindrical crystals are aggregated over the surface direction with the central axis substantially coincided with the thickness direction to form a thin film. Of course, it may be a thin film formed of preferentially oriented granular crystals. In addition, the thickness of the piezoelectric film manufactured by the thin film process is generally 0.5 to 5 μm.

  Next, as shown in FIG. 17E, the upper electrode 109 is formed. The upper electrode 109 only needs to be a highly conductive material, and many metals such as aluminum, gold, nickel, and platinum, conductive oxides, and the like can be used. In this embodiment, the platinum film is formed by sputtering.

  Thereafter, as shown in FIG. 19A, only the piezoelectric film 107 and the upper electrode 109 are etched to pattern the piezoelectric active portion 106. The above is the film forming process. After film formation is performed in this manner, as shown in FIG. 19B, the silicon single crystal substrate is anisotropically etched with an alkaline solution to form openings 105 and the like. Through the above steps, the piezoelectric element 104 shown in FIG. 15 is formed.

  In the present embodiment, the piezoelectric film 107 and the upper electrode 109 are formed in a region facing the opening 105, but the present invention is not limited to this. For example, the piezoelectric film 107 and the upper electrode 109 are extended to a region facing the peripheral wall. May be. In the above-described example, the piezoelectric inactive portion 111 is formed by removing the lower electrode 102. However, the present invention is not limited to this. For example, a low dielectric insulating layer is provided between the piezoelectric film 107 and the upper electrode 109. Alternatively, the piezoelectric film 107 may be partially inactivated by doping or the like.

  As described above, according to the present embodiment, the contact hole is formed by providing the piezoelectric inactive portion 111 that has the piezoelectric film 107 but does not substantially drive, continuously from the piezoelectric active portion 106. Therefore, a voltage can be applied to the piezoelectric active portion 106 without being provided, and the piezoelectric active portion 106 can be provided in a region facing the opening 105, so that the displacement characteristics and reliability can be improved.

(Modification 1)
20 and 21 are schematic cross-sectional views of the main part showing the structure of the piezoelectric element, and FIG. 22 is a schematic plan view of the main part showing the structure of the piezoelectric element. This modification is another example of the wiring method of the piezoelectric active portion 106. As shown in FIG. 20, the lower electrode film 103 for wiring is not provided in the region facing the opening 105 but is provided on the peripheral wall. Except as described above, the third embodiment is the same as the third embodiment. Of course, even in such a configuration, the same effect as that of the third embodiment can be obtained.

  In the third embodiment, the lower electrode film 103 for wiring is provided on the outer side of the lower electrode 102. However, the present invention is not limited to this. For example, as shown in FIG. A lead electrode 112 that is connected to the upper electrode 109 of the piezoelectric inactive portion 111 and extends to the end of the substrate may be separately provided. That is, the lead electrode 112 may be an electrode having the functions of the lead electrode 110 and the lower electrode film 103 for wiring.

  Further, the piezoelectric film 107 and the upper electrode 109 constituting the piezoelectric inactive portion 111 extending on the peripheral wall from the end portion of the opening 105 are not particularly limited. For example, as shown in FIG. It is preferable that the wide portion 113 is wider than the opening 105 in the vicinity of the end portion of the opening 105 to cover the end portion of the opening 105. Thereby, the rigidity of the diaphragm in the vicinity of the end of the opening 105 is kept high, and the occurrence of cracks in the diaphragm can be prevented.

(Modification 2)
23 and 24 are schematic plan views of the main part showing the structure of the piezoelectric element. As shown in FIG. 23, in this modification, a discontinuous lower electrode discontinuous with the lower electrode 102 is provided below the piezoelectric inactive portion 111 in a region facing the boundary between the end of the opening 105 and the peripheral wall. This is an example in which a film 114 is provided. That is, in the vicinity of the end of the opening 105 on the side where the piezoelectric film 107 and the upper electrode 109 are extended, the lower electrode film removing portion 115 from which the lower electrode 102 has been removed is arranged along the shape of the opening 105. It is provided in the direction of a narrow groove. The third embodiment is the same as the third embodiment except that the lower electrode 102 of the piezoelectric active portion 106 is a discontinuous lower electrode film 114 at the boundary portion between the end portion of the opening 105 and the peripheral wall.

  Here, the width of the lower electrode film removal portion 115 that separates the lower electrode 102 and the discontinuous lower electrode film 114 should be at least a width that can maintain the insulation strength between the lower electrode 102 and the discontinuous lower electrode film 114. However, it is preferable to keep the rigidity of the elastic film 108 as narrow as possible.

  Further, in such a configuration, the discontinuous lower electrode film 114 becomes a floating electrode that is not electrically connected to any other. The piezoelectric film 107 and the upper electrode 109 existing on the lower electrode 102 constitute a piezoelectric active part 106 that is a substantial driving unit, and the piezoelectric film 107 and the upper electrode 109 on the discontinuous lower electrode film 114 are strong. It is not driven.

  Therefore, the boundary portion between the opening 105 and the peripheral wall is not driven strongly by voltage application to the piezoelectric active portion 106. For this reason, the elastic film 108 has a high rigidity at the end portion in the longitudinal direction of the opening 105, and the elastic film 108 can be prevented from being broken or the piezoelectric film 107 can be prevented from being broken at this portion.

  In the present modification, the discontinuous lower electrode film 114 is formed across the parallel direction of the plurality of openings 105, but the present invention is not limited to this. For example, as shown in FIG. 24, each piezoelectric active part 106 may be separated. As a result, the piezoelectric film 107 and the upper electrode 109 on the discontinuous lower electrode film 114 are not completely driven, and the piezoelectric inactive part 111 is obtained, and the elastic film 108 or the piezoelectric film 107 is more reliably destroyed. Can be prevented.

  In this modification, the discontinuous lower electrode film 114 is a floating electrode that is not electrically connected to other parts. However, the present invention is not limited to this. For example, the time constant to be charged is piezoelectric. You may make it connect with an electrode layer via resistance of a predetermined | prescribed resistance value so that it may become larger than the drive pulse of the body active part 106. FIG.

(Modification 3)
FIG. 25 is a schematic plan view of an essential part showing the structure of the piezoelectric element. FIG. 26A is a main part schematic plan view showing the structure of the piezoelectric element, and FIG. 26B is a main part schematic side sectional view showing the structure of the piezoelectric element.

  In this modification, as shown in FIG. 25, an intermediate electrode film 116 that is separated by the lower electrode film removing unit 115 and is not connected to any other is provided between the lower electrode films 103 for wiring. The configuration is the same as that of the third embodiment.

  With such a configuration, the width of the lower electrode film removal portion 115 that separates the lower electrode films 103 for wiring can be reduced. That is, the intermediate electrode film 116 is provided between the lower electrode films 103 for wiring. For this reason, even if the width of the lower electrode film removal portion 115 is narrowed, these insulation strengths can be reliably maintained. As a result, the rigidity of the elastic film 108 is further increased, and the breakage of the elastic film 108 or the breakage of the piezoelectric film 107 can be prevented at the boundary between the opening 105 and the peripheral wall, as in the above-described embodiment.

  In the above-described modification, the lower electrode film removing portion 115 between the lower electrode 102 and the wiring lower electrode film 103 can maintain the insulation strength between the lower electrode 102 and the wiring lower electrode film 103. The width is formed. For example, as shown in FIG. 26, the upper electrode 109 in a portion where dielectric breakdown is likely to occur, such as both sides in the width direction of the piezoelectric active portion 106, may be removed. Then, an inactive portion 117 in which the piezoelectric film 107 that is not substantially driven is left may be provided. As a result, the insulation strength can be more reliably maintained. Of course, it is needless to say that the upper electrode 109 may not be removed if the piezoelectric film 107 is not driven.

(Modification 4)
Fig.27 (a) is a principal part schematic plan view which shows the structure of a piezoelectric element. FIG. 27B is a schematic side cross-sectional view showing a main part of the structure of the piezoelectric element. FIG. 28 is a schematic diagram for explaining a method of manufacturing a piezoelectric element.

  In this modified example, as shown in FIG. 27, instead of providing the lower electrode film 103 for wiring, the piezoelectric film 107 and the upper electrode 109 that become the piezoelectric inactive part 111 are moved from the region facing the opening 105 to the peripheral wall. It is extended. Although not shown, in the vicinity of the end portion, for example, an external wiring such as a flexible cable and the upper electrode 109 are directly connected. The lower electrode 102 is basically provided in a region facing the opening 105. The lower electrode 102 extends from the end opposite to the piezoelectric inactive portion 111 to the peripheral wall of the opening 105 and serves as a common electrode for each piezoelectric element 104. The rest is the same as the third embodiment.

  Even with this configuration, of course, the same effects as those of the third embodiment can be obtained. Further, the lower electrode 102 and the upper electrode 109 are extended from the longitudinal end portion of the opening 105 in the opposite direction to the peripheral wall. With this structure, the wiring can be easily drawn without short-circuiting the lower electrode 102 and the upper electrode 109.

  When the piezoelectric film 107 is continuously formed from the opening 105 to the peripheral wall as in this modification, the crystal structure of the piezoelectric film 107 is the same on the lower electrode 102 and the elastic film 108. Preferably there is. Therefore, it is preferable to form the piezoelectric film 107 as follows.

  That is, as shown in FIG. 28A, before the piezoelectric film 107 is formed, a crystal seed 118 made of titanium or titanium oxide is formed in an island shape on the lower electrode 102 and the elastic film 108 by sputtering. . Thereafter, as shown in FIG. 28B, a piezoelectric precursor layer 121 is formed in a non-crystalline state. Thereafter, as shown in FIG. 28C, the piezoelectric precursor layer 121 is crystallized by firing to form the piezoelectric film 107.

  Further, when the method for forming the crystal seed 118 is used, the elastic film 108 is made of a material having good adhesion to the piezoelectric film 107, for example, at least one selected from the constituent elements of the piezoelectric film 107. It is preferably formed of an element oxide or nitride, such as zirconium oxide.

  Here, in the case of forming the piezoelectric film 107 on the lower electrode 102 of platinum or the like, a technique for forming a crystal seed and orienting the crystal in approximately one direction has been filed earlier. However, in the special structure in which the piezoelectric film 107 is formed after patterning the lower electrode 102 as in this modification, even if a crystal seed is formed on the lower electrode 102 in advance, the elastic film 108 is used. Above, there was a problem that the crystal structure was different and cracks were likely to occur. Therefore, in this modification, the crystal seed 118 is also formed on the elastic film 108 so that the crystal structure of the piezoelectric film 107 is substantially the same on the lower electrode 102 and the elastic film 108, thereby generating cracks and abnormalities. Prevent the generation of excessive stress. The crystal seeds on the elastic film 108 may be formed at the same time after the lower electrode 102 is patterned, or after the crystal seeds on the lower electrode 102 are formed and further patterned, only the elastic film 108 is separately provided. You may go. In addition, when performed separately, the crystal seed may be formed in a film shape instead of an island shape.

(Modification 5)
FIG. 29 is a schematic plan view of an essential part showing the structure of the piezoelectric element. As shown in FIG. 29, the present modification is the same as that of the present embodiment except that the piezoelectric inactive portion 111 is provided in a region facing the peripheral wall in the width direction of the opening 105 from the substantially central portion of the piezoelectric active portion 106. It is the same as the form.

  By adopting such a configuration, in addition to the same effects as the present embodiment, current concentration on the piezoelectric film 107 in the vicinity of the connection portion between the piezoelectric active part 106 and the piezoelectric inactive part 111 is suppressed. And the destruction of the piezoelectric film 107 and the like can be prevented.

(Modification 6)
FIG. 30 is a schematic plan view of an essential part showing the structure of the piezoelectric element. This modification is the same as Modification 4 except that a narrow portion 122 is formed on the piezoelectric active portion 106 side of the piezoelectric inactive portion 111 as shown in FIG. The width of the narrow portion 122 is narrower than the width of the piezoelectric active portion 106 located in the region facing the end in the longitudinal direction of the opening 105. In the narrow portion 122, the upper electrode 109 and the piezoelectric film 107 are narrow.

  In such a configuration, the elastic film 108 is easily displaced because the upper electrode 109 and the piezoelectric film 107 are not present around the narrow portion 122 at the end of the opening 105. For this reason, the displacement amount of the elastic film 108 by driving the piezoelectric active portion 106 at this end can be improved.

  In this modification, the upper electrode 109 and the piezoelectric film 107 that are the piezoelectric inactive portion 111 are formed to be narrow. However, the present invention is not limited to this. For example, only the upper electrode 109 is formed to be narrow. You may make it do.

(Modification 7)
FIG. 31A is a schematic plan view of a main part showing the structure of the piezoelectric element. FIG. 31B is a schematic side cross-sectional view showing the structure of the piezoelectric element. In this modification, as shown in FIG. 31, a narrow portion 123 in which a part of the lower electrode 102 protrudes is formed in the vicinity of the end portion of the opening 105. The lower electrode 102 at the boundary between the piezoelectric active part 106 and the piezoelectric inactive part 111 has both sides of the opening 105 in the width direction removed. Thereby, a part of the lower electrode 102 becomes a narrow part 123 which is narrower than the other part. Further, the narrow portion 123 is formed to be narrower than the width of the piezoelectric film 107 in the region facing the opening 105, and the third portion except that both end faces in the width direction are covered with the piezoelectric film 107. This is the same as the embodiment.

  With this configuration, the upper electrode 109 and the side surface of the lower electrode 102 are reliably insulated in the vicinity of the end portion of the lower electrode 102 of the opening 105, that is, at the end portion of the piezoelectric active portion 106. There is no discharge between them. Therefore, dielectric breakdown of the piezoelectric film 107 can be prevented.

(Modification 8)
FIG. 32A is a schematic plan view of an essential part showing the structure of the piezoelectric element. 32 (b) and 32 (c) are schematic cross-sectional side views of the relevant part showing the structure of the piezoelectric element. In this modification, as shown in FIGS. 32A and 32B, the narrow portion 123 of the lower electrode 102 is formed in a region facing the opening 105, and the narrow portion 123 is piezoelectric. It is formed with a width wider than the width of the body film 107. The piezoelectric film 107 and the upper electrode 109 are the same as in the modified example 7 except that the piezoelectric body inactive section 111 is formed by extending over the narrow wall 123 to the peripheral wall.

  Here, as shown by a graph called a Paschen curve, it is generally known that if the distance between the electrodes is equal to or less than a certain value, no discharge occurs between them. For example, in this modification, the distance between the width direction end face of the narrow portion 123 and the width direction end face of the upper electrode 109 may be about 10 μm or less, and in this modification, these distances are about 7 μm. I made it.

  Therefore, even in such a configuration, similarly to the modified example 7, the discharge between the upper electrode 109 and the lower electrode 102 at the longitudinal end portion of the opening 105 is prevented, and the dielectric breakdown of the piezoelectric film 107 is suppressed. It is done.

  In this modification, the narrow portion 123 is provided in the region facing the opening 105, but the present invention is not limited to this. The distance between the width direction end face of the narrow portion 123 and the width direction end face of the upper electrode 109 may be a distance that does not cause discharge between the upper electrode 109 and the lower electrode 102. For example, as shown in FIG. 32 (c), the narrow portion 123 may be extended to the width direction peripheral wall of the opening 105.

(Modification 9)
FIG. 33 is a schematic plan view of an essential part showing the structure of the piezoelectric element. In this modification, as shown in FIG. 33, the narrow portion 123 of the lower electrode 102 has a substantially trapezoidal shape with a width gradually decreasing toward the tip side. In addition, this embodiment is the same as Modification 8 except that at least the tip of the narrow portion 123 is covered with the piezoelectric film 107 in a region facing the opening 105.

  As a result, the piezoelectric film 107 tends to be thin at the end of the lower electrode 102. As a result, electric field concentration is likely to occur, and dielectric breakdown of the piezoelectric film 107 is particularly likely to occur. The tip portion of the narrow portion 123 is covered with the piezoelectric film 107, and the lower electrode 102 and the upper electrode 109 are insulated. For this reason, no discharge occurs between them, and the dielectric breakdown of the piezoelectric film 107 can be prevented.

(Modification 10)
FIG. 34A is a schematic plan view of the main part showing the structure of the piezoelectric element. FIG. 34 (b) is a schematic side sectional view showing the main part of the structure of the piezoelectric element. In this modification, as shown in FIG. 34, the piezoelectric film 107 and the upper electrode 109 continuously extend from one longitudinal end of the opening 105 to a region facing the peripheral wall with a narrower width than the piezoelectric active part 106. The piezoelectric inactive portion 111 is provided. The upper electrode 109 and the external wiring are connected near the end of the opening 105. On the other hand, the lower electrode 102 is basically formed so as to cover a region facing each opening 105. However, the region where the piezoelectric film 107 and the upper electrode 109 are extended, that is, the region where the piezoelectric inactive portion 111 is extended is a lower electrode in which the lower electrode 102 is removed with a width narrower than the width of the opening 105. A film removal unit 115 is formed. Other than this, the third embodiment is the same as the third embodiment.

  Here, in the portion where the piezoelectric film 107 and the upper electrode 109 are extended from the end portion of the opening 105 on the peripheral wall and the lower electrode film removing portion 115, the edge portion of the upper electrode 109 extends from the lower electrode 102 to the lower electrode film. It is preferable that the first direction 109a intersecting the removal portion 115 does not coincide with the second direction 109b in which the upper electrode 109 extends on the peripheral wall. That is, it is preferable that the angle between the direction of the current flowing in the portion where the upper electrode 109 crosses the lower electrode 102 and the direction of the current flowing in the extended upper electrode 109 is large. The angle of the direction of current flowing in these portions is about 90 °.

  Thus, in the present modification, the lower electrode film removing portion 115 is formed by removing the portion of the lower electrode 102 where the piezoelectric film 107 and the upper electrode 109 of the piezoelectric active portion 106 are extended to the peripheral wall. Further, the other region facing the opening 105 is covered with the lower electrode 102. As a result, there is no end portion of the lower electrode 102 around the upper electrode 109 constituting the piezoelectric active portion 106, and it is difficult for discharge to occur. Further, in the extended portion of the piezoelectric film 107 and the upper electrode 109, the direction of the current flowing through the portion where the upper electrode 109 crosses the lower electrode 102 does not match the direction of the current flowing through the extended upper electrode 109. Therefore, the current flowing from the extended upper electrode 109 into the piezoelectric active portion 106 is spread and dispersed at the intersection with the lower electrode 102. Therefore, dielectric breakdown of the piezoelectric film 107 due to electric field concentration or the like can be prevented, and the durability and reliability of the element chip can be improved.

  FIG. 35 is a schematic plan view of an essential part showing the structure of the piezoelectric element. Further, as shown in FIG. 35, a displacement suppression layer 124 for suppressing the displacement of the piezoelectric active portion 106 is provided on the upper electrode 109 at the boundary portion between the piezoelectric active portion 106 and the piezoelectric inactive portion 111. May be. Thereby, vibration at the end of the piezoelectric active part 106 can be suppressed. Furthermore, it is possible to prevent the occurrence of cracks in the elastic film 108 due to the driving of the piezoelectric active portion 106. The displacement suppression layer 124 can be easily formed from the same material as that of the lead electrode 110 described above, for example.

  In the present modification, the lower electrode 102 in the region corresponding to the piezoelectric film 107 and the upper electrode 109 is removed in a substantially rectangular shape to form the lower electrode film removal unit 115, but the present invention is not limited to this. 36 (a) and 36 (b) are schematic plan views of the main part showing the structure of the piezoelectric element. For example, as shown in FIG. 36A, a lower electrode film removing portion 115 having a substantially circular shape or a substantially elliptic shape may be provided in a region facing the opening 105. In this case, the base end portions of the piezoelectric film 107 and the upper electrode 109 extending with a width narrower than that of the piezoelectric active portion 106 may be further removed to the inside of the piezoelectric active portion 106. As a result, the angle between the direction of the current flowing in the portion where the upper electrode 109 crosses the lower electrode 102 and the direction of the current flowing in the extended upper electrode 109 is increased, that is, the piezoelectric from the extended upper electrode 109 is piezoelectric. The direction in which the current flowing into the body active part 106 spreads increases, and the electric field applied between the upper electrode 109 and the lower electrode 102 is further dispersed.

  Further, for example, as shown in FIG. 36B, the shape of the lower electrode film removal portion 115 is made substantially semicircular, and the width of the longitudinal end portion of the piezoelectric active portion 106 is gradually reduced. Furthermore, the lower electrode 102 and the upper electrode 109 may intersect at the arc portion of the lower electrode film removal unit 115. Even with such a configuration, the angle between the direction of the current flowing in the portion where the upper electrode 109 crosses the lower electrode 102 and the direction of the current flowing in the extended upper electrode 109 is increased. Therefore, as described above, the electric field applied between the lower electrode 102 and the upper electrode 109 is dispersed.

  As described above, the shapes of the lower electrode film removing portion 115 and the extended portions of the piezoelectric film 107 and the upper electrode 109 are not particularly limited, but the direction of the current flowing in the extended portion of the upper electrode 109 and the lower portion It is preferable that the angle with respect to the direction of the current flowing in the portion crossing the electrode 102 is 5 ° to 180 °.

(Modification 11)
FIG. 37 is a schematic plan view of an essential part showing the structure of the piezoelectric element. In the present modification, as shown in FIG. 37, the lower electrode 102 is removed at a substantially central portion in the longitudinal direction on the peripheral walls on both sides in the width direction of the opening 105 to form a lower electrode film removal portion 115. The piezoelectric film 107 and the upper electrode 109 are extended from a substantially central portion in the longitudinal direction of the piezoelectric active portion 106 to the peripheral wall through the lower electrode film removing portion 115 to form a piezoelectric inactive portion 111. Further, the upper electrode 109 extending on the peripheral wall is connected to the external wiring through the lead electrode 110. Except this, it is the same as the modification 10.

  As described above, by extending the piezoelectric film 107 and the upper electrode 109 from the central portion in the width direction of the opening 105, the driving loss of the piezoelectric active section 106 can be suppressed and the rise of vibration of the elastic film 108 can be accelerated. Can do. Of course, the same effect as that of the modified example 10 can be obtained.

(Modification 12)
FIG. 38 is a schematic plan view of an essential part showing the structure of the piezoelectric element. As shown in FIG. 38, this modified example is a piezoelectric inactive portion 111 in which the piezoelectric film 107 and the upper electrode 109 of the piezoelectric active portion 106 are extended from both sides in the width direction of the opening 105 to the peripheral wall. Except that, it is the same as the modification 11.

  Even with such a configuration, the same effects as those of Modification 11 can be obtained. In addition, since the piezoelectric film 107 and the upper electrode 109 are extended on the peripheral wall from both sides of the opening 105, the driving loss of the piezoelectric active part 106 can be further suppressed, and the vibration characteristics of the elastic film 108 are improved. Can be made.

(Modification 13)
FIG. 39A is a schematic plan view of the main part showing the structure of the piezoelectric element. FIGS. 39B and 39C are schematic cross-sectional side views of the main part showing the structure of the piezoelectric element. As shown in FIG. 39, the present modification is an example in which a remaining portion 125 made of the same layer as the lower electrode 102 is provided on the partition wall of the opening 105. In this modification, the remaining portion 125 is provided continuously over the longitudinal direction of the opening 105 with the lower electrode 102 of the piezoelectric active portion 106. In other words, the lower electrode film removal portion 115 from which the lower electrode 102 is removed is provided in a region facing the boundary with the partition wall on both sides in the width direction of the opening 105. Thus, the configuration is the same as that of the third embodiment except that the remaining portion 125 is formed in a region facing the partition.

Here, the distance h ₁ between the end surface in the width direction of the lower electrode 102 and the end surface in the width direction of the remaining portion 125, and the side surface of the longitudinal end portion of the piezoelectric film 107 and the peripheral wall are extended. The distance h ₂ until the lower electrode 102 becomes wide is preferably longer than the film thickness of the piezoelectric film 107 and narrower than the width of the lower electrode 102.

  Further, the width of the remaining portion 125 is preferably 50% or more of the width of the partition wall, more preferably 80% or more. Furthermore, it is preferable that the lower electrode 102 or the remaining portion 125 is formed in at least 50% or more of the regions facing the plurality of openings 105 arranged in parallel and the partition walls on both sides in the width direction.

  In this modification, the lower electrode 102 is removed in the form of a narrow groove in the vicinity of the end of the opening 105 on the side where the piezoelectric film 107 and the upper electrode 109 are extended. The lower electrode film removal unit 115 is formed. The lower electrode film on the peripheral wall of the opening 105 is a discontinuous lower electrode film 114 that is discontinuous with the lower electrode 102 constituting the piezoelectric active portion 106. On the discontinuous lower electrode film 114, the piezoelectric film 107 and the upper electrode 109 are extended to form the piezoelectric inactive portion 111. Although not shown, the upper electrode 109 and the external wiring are formed near the end. And are connected.

  Even in such a configuration, the same effect as in the third embodiment can be obtained. Furthermore, in this modification, the remaining portion 125 is preferably provided in the region facing the partition on both sides in the width direction of the opening 105, preferably under the conditions described above. As a result, the area where the lower electrode 102 is removed becomes very small. Therefore, even if the piezoelectric film 107 is formed on the patterned lower electrode 102, the film thickness of the piezoelectric film 107 is substantially uniform as a whole, and the film thickness of the piezoelectric film 107 is locally reduced. Absent.

Further, since the distance h ₂ between the side surface of the longitudinal end portion of the piezoelectric film 107 and the lower electrode 102 extending on the peripheral wall becomes relatively wide, the longitudinal end portion of the opening 105 is reduced. Even in the vicinity, the thickness of the piezoelectric film 107 is uniform. Thus, even when the piezoelectric film 107 near the end of the opening 105 on the side from which the lower electrode 102 is drawn is etched by an etching method having no selectivity such as ion milling, the lower electrode 102 below the piezoelectric film 107 is formed. Are removed together and the film thickness is not reduced. Accordingly, the rigidity of the lower electrode 102 in the vicinity of the end of the opening 105 is not lowered, and the durability is improved. Such an effect is particularly noticeable when the piezoelectric film 107 is formed by a spin coating method such as a sol-gel method. In addition, for example, it is formed by a MOD method (organic metal thermal coating decomposition method) or the like. You may make it do.

(Modification 14)
FIG. 40 is a schematic plan view of an essential part showing the structure of the piezoelectric element. In the present modification, as shown in FIG. 40, the residual portion 125 provided on the partition in the width direction of the opening 105 is continuous with the discontinuous lower electrode film 114 instead of the lower electrode 102 constituting the piezoelectric active portion 106. The third modification is the same as the modification 13 except that the second modification is provided.

  Even with such a configuration, the piezoelectric film 107 is not thinned, and the same effect as that of the modified example 13 can be obtained.

(Modification 15)
FIG. 41A is a schematic plan view of an essential part showing the structure of the piezoelectric element. FIG. 41B is a schematic side sectional view showing the main part of the structure of the piezoelectric element. As shown in FIG. 41, in this modification, the piezoelectric active portion 106 is directed to the wiring lower electrode film 103 at the end portion of the lower electrode 102 that becomes the boundary between the piezoelectric active portion 106 and the piezoelectric inactive portion 111. The third embodiment is the same as the third embodiment except that a gradually decreasing thickness portion 126 in which the thickness of the lower electrode 102 is gradually decreased is provided. The shape of the gradually decreasing film thickness portion 126 is not particularly limited. For example, in this modification, the thickness of the lower electrode 102 is an inclined surface that gradually decreases.

  As described above, in this modification, the film thickness gradually decreasing portion 126 that gradually decreases toward the outside of the piezoelectric active portion 106 is formed at the end of the lower electrode 102 that is the end of the piezoelectric active portion 106. I tried to provide it. Accordingly, the piezoelectric film 107 is formed along the shape on the lower electrode 102 including the gradually decreasing thickness portion 126, and the entire film thickness becomes substantially uniform. That is, the film thickness of the piezoelectric film 107 at the end of the lower electrode 102 is not reduced, and the dielectric breakdown due to electric field concentration of the piezoelectric film 107 near the end of the piezoelectric active part 106 is suppressed. Can do.

  In the present modification, the film thickness gradually decreasing portion 126 is an inclined surface where the film thickness gradually decreases, but the present invention is not limited to this. 42 (a) and 42 (b) are schematic cross-sectional side views showing a main part of the structure of the piezoelectric element. For example, as shown in FIG. 42A, the film thickness gradually decreasing portion 126a may be formed so that the film thickness decreases intermittently and the cross section has a substantially stepped shape. A method for forming such a gradually decreasing portion 126a is not particularly limited. For example, a resist is applied a plurality of times on the lower electrode 102, and a film thickness is formed in a region that becomes the gradually decreasing portion 126a of the lower electrode 102. The lower electrode 102 can be formed by patterning after forming a step-like resist film substantially the same as the gradually decreasing portion 126a.

  Further, for example, as shown in FIG. 42 (b), a film thickness gradually decreasing portion 126b having a cross section of an inclined curved surface may be used. A method for forming such a gradually decreasing thickness portion 126b is also not particularly limited. For example, a region where the lower electrode 102 on the elastic film 108 is not formed and a region where the gradually decreasing thickness portion 126b is formed are covered with a mask, so-called mask deposition. The lower electrode 102 is formed by the above. That is, the lower electrode 102 is also formed in a part of the region covered with the mask so as to wrap around from the gap of the mask, so that the thin film thickness gradually decreasing portion 126b whose section is an inclined curved surface. Of course, as described above, after the resist film having substantially the same shape as the gradually decreasing thickness portion 126b is formed on the lower electrode 102, the lower electrode 102 can be patterned.

(Modification 16)
FIG. 43A is a schematic plan view of an essential part showing the structure of the piezoelectric element. FIG. 43B is a schematic side sectional view showing the main part of the structure of the piezoelectric element.

  In this modification, an insulating film 127 made of an insulating material is provided outside the lower electrode 102 in the longitudinal direction. That is, in this modification, as shown in FIG. 43, the piezoelectric active portion 106 including the lower electrode 102, the piezoelectric film 107, and the upper electrode 109 is formed on the elastic film 108 in the region facing the opening 105. . For example, an insulating film 127 having a film thickness substantially the same as the film thickness of the lower electrode 102 is formed outside the end of the lower electrode 102 at the location that becomes the boundary between the piezoelectric active part 106 and the piezoelectric inactive part 111. did. The material of the insulating film 127 is not particularly limited, and may be an insulating material different from that of the elastic film 108, for example.

  In this modification, after patterning the lower electrode 102, the insulating film 127 is formed outside one end in the longitudinal direction. On top of this, the piezoelectric film 107 and the upper electrode 109 were formed and patterned to form the piezoelectric active part 106 and the piezoelectric inactive part 111. Thereby, the film thickness of the piezoelectric film 107 does not become thin at the end portion of the lower electrode 102, and the dielectric breakdown due to the electric field concentration of the piezoelectric film 107 in this portion can be prevented. Also in such a configuration, it is needless to say that an effect similar to that of the above-described embodiment can be obtained.

(Modification 17)
FIG. 44A is a schematic plan view of a main part showing the structure of the piezoelectric element. FIG. 44B is a schematic side cross-sectional view of the relevant part showing the structure of the piezoelectric element. In this modification, as shown in FIG. 44, a thick film portion 108a is provided in place of the insulating film 127 outside the end portion of the lower electrode 102, which is a boundary portion between the piezoelectric active portion 106 and the piezoelectric inactive portion 111. It is the same as that of the modification 16 except having made it provide. In the thick film portion 108a, the elastic film 108 is thicker than the other portions. For example, in this modification, the thick film portion 108a is formed thicker than the thickness of the lower electrode 102.

  In this modification, the elastic film 108 is patterned to form the thick film portion 108a at a predetermined position, and then the piezoelectric film 107 and the upper electrode 109 are formed and patterned to form the piezoelectric active section 106 and the piezoelectric inactive body. The part 111 was formed. Thereby, the film thickness of the piezoelectric film 107 in the region corresponding to the end portion of the lower electrode 102 does not become thinner than other portions, and the dielectric breakdown due to the electric field concentration of the piezoelectric film 107 in this portion is formed. be able to. Also in such a configuration, the same effect as in the third embodiment can be obtained.

(Modification 18)
FIG. 45A is a schematic plan view of an essential part showing the structure of the piezoelectric element. FIG. 45B is a schematic side cross-sectional view of the relevant part showing the structure of the piezoelectric element. This modification is an example in which the end portion of the upper electrode 109 is formed inside the end portion of the lower electrode 102 as shown in FIG. An end portion of the upper electrode 109 is an end portion of the piezoelectric active portion 106. Further, for example, in this modification, the end portion of the piezoelectric film 107 is substantially at the same position as the end portion of the lower electrode 102, and the piezoelectric film is also formed on the lower electrode 102 protruding outward from the end portion of the upper electrode 109. 107 is formed, and this portion is a piezoelectric non-active portion 111 that is not substantially driven.

  In this modification, the piezoelectric film 107 is not removed in the lower electrode film removal unit 115 from which the lower electrode 102 between the lower electrode 102 and the wiring lower electrode film 103 is removed. It remains in. Since the piezoelectric film 107 of the lower electrode film removing unit 115 functions as an insulating film, the lower electrode 102 and the lead electrode 110 are insulated.

  As described above, in the present modification, the piezoelectric inactive portion 111 is continuously provided by removing, for example, the upper electrode 109 outside the end of the lead active portion 106 of the piezoelectric active portion 106. did. As a result, the distance between the end of the upper electrode 109 and the end of the lower electrode 102 which are the ends of the piezoelectric active portion 106 can be increased. For this reason, even when a voltage is applied to the piezoelectric active portion 106, the electric field strength at the end of the piezoelectric active portion 106 does not increase, and insulation breakdown of the piezoelectric film 107 can be prevented. Further, since the thickness of the piezoelectric film 107 of the piezoelectric active part 106 becomes uniform, the piezoelectric characteristics are improved. Even with such a configuration, the same effects as those of the third embodiment can be obtained.

(Modification 19)
In the first embodiment, after the PZT film is patterned, heat treatment is performed in an oxygen atmosphere at 700 ° C. to form the piezoelectric film 26. You may perform in the following process not only in this. A heat treatment is performed to form the piezoelectric film 26. At this time, the treatment is performed in an oxygen atmosphere and an atmosphere of 100% water at a temperature of 600 ° C. to 700 ° C. and a pressure of 200 atm or less. This heating step may be performed in a step of heating and crystallizing the amorphous thin film, or may be performed in this heat treatment step by providing a heat treatment step after this heating step. When heat treatment is performed under these conditions, the amount of oxygen in the PZT film can be increased. When the heating temperature exceeds 700 ° C., Pb is missing from the PZT film. Further, when the atmospheric pressure exceeds 200 atm, a hysteresis curve peculiar to a ferroelectric substance is not observed. This degrades the performance of the PZT film. Therefore, when heat-treating the crystallized PZT or PZT-based ceramic thin film in an atmosphere containing water, the atmospheric water is 100%, the atmospheric pressure is 200 atm or less, and the temperature is 700 ° C. The following is desirable.

In this modification, heat treatment may be performed in an atmosphere containing water after crystal growth in a PZT thin film formed by a sol-gel method. Of course, the heat treatment may be performed in an atmosphere containing water when the crystal is grown. The thin film material is not limited to lead zirconate titanate (Pb (Zr, Ti) O ₃ : PZT), but other ceramic materials such as lead lanthanum titanate ((Pb, La) TiO ₃ ), lead zirconate Lanthanum ((Pb, La) ZrO ₃ ), lead lanthanum zirconate titanate ((Pb, La) (Zr, Ti) O ₃ : PLZT), lead magnesium niobate zirconate titanate (Pb (Mg, Nb) ( _{Zr, Ti) O 3: PMN} -PZT), strontium titanate, lithium niobate, zirconia, the present invention may be applied to the Y-1, ITO or the like. In addition to the sol-gel method, an amorphous thin film may be formed by a MOD (Metal-Organic Decomposition) method, a sputtering method, or a vapor deposition method.

(Other variations)
Although the embodiment and the modification have been described above, the basic configuration of the ultrasonic transducer element chip is not limited to that described above.

  For example, in the third embodiment, the end portion of the lower electrode 102 is used as the end portion of the piezoelectric active portion 106, and the piezoelectric film 107 and the upper electrode 109 thereon are extended to the outside to extend inactive to the piezoelectric body. A portion 111 is provided to prevent the end of the piezoelectric active portion 106 from being broken. However, at the other end, the piezoelectric film 107 and the upper electrode 109 are patterned in the opening 105 so that the piezoelectric active portion 106 It is an end. Such an end portion may cause the piezoelectric film 107 and the upper electrode 109 to peel off. For example, the end of the piezoelectric active part 106 is protected by fixing the end with an adhesive or the like, or by covering the piezoelectric film 107 of the piezoelectric element 104 with a discontinuous piezoelectric film, etc. You may make it improve durability.

  Of course, it goes without saying that each of the embodiments and the modifications described above can be further combined and implemented to achieve further effects.

  Further, in each of the embodiments and modifications described above, a thin film type ultrasonic transducer element chip that can be manufactured by applying a film formation and a lithography process is taken as an example. Of course, it is not limited to this. For example, a substrate is stacked to form the opening 45. Alternatively, a piezoelectric film is formed by attaching a green sheet or screen printing. Or the structure of various manufacturing methods, such as what forms a piezoelectric film by crystal growth, such as a hydrothermal method, is employable for an ultrasonic transducer element chip.

  As described above, the present embodiment can be applied to ultrasonic transducer element chips having various structures as long as it does not contradict the purpose.

  DESCRIPTION OF SYMBOLS 16 ... Housing | casing, 17 ... Element chip | tip as an ultrasonic transducer element chip | tip, 24 ... Lower electrode as a metal film, 24b ... Adhesion film | membrane, 26 ... Piezoelectric film | membrane as a piezoelectric thin film, 43 ... Vibration film | membrane.

Claims (1)

An ultrasonic transducer element chip;
A housing that supports the ultrasonic transducer element chip,
The ultrasonic transducer element chip is a metal film formed on a vibration film,
A piezoelectric thin film formed on the metal film,
The metal film is laminated on the vibration film via an adhesion film, the metal film is platinum or an alloy containing platinum, and the adhesion film is titanium having a thickness of 80 mm or less. Acoustic probe.

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