Ultrasonic transducer element chip, probe, electronic instrument, and ultrasonic diagnostic device

An ultrasonic transducer element chip includes a substrate, a plurality of ultrasonic transducer elements and a plate-shaped member. The substrate includes a partition wall section defining a plurality of openings arranged in an array pattern. A wall thickness of the partition wall section is smaller than a wall height of partition wall section. Each of the ultrasonic transducer elements is provided in each of the openings. The plate-shaped member is fixed on a surface of the substrate opposite to a surface of the substrate on which the ultrasonic transducer elements are provided. The plate-shaped member covers at least one of the openings in a plan view seen along a thickness direction of the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2012-038402 filed on Feb. 24, 2012. The entire disclosure of Japanese Patent Application No. 2012-038402 is hereby incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to an ultrasonic transducer element chip, a probe that uses the ultrasonic transducer element chip, and an electronic instrument and an ultrasonic diagnostic device that use the probe.

2. Related Art

As described in Japanese Laid-Open Patent Publication No. 2011-82624, for example, an ultrasonic transducer element chip is provided with a substrate. A plurality of openings are formed in the substrate. An ultrasonic transducer element is provided in each of the openings. The ultrasonic transducer element chip is provided with a vibrating film. The vibrating film covers the openings from a surface of the substrate.

SUMMARY

When the openings are formed in the substrate, the strength of the substrate is deteriorated. The strength is insufficient with respect to force in a thickness direction of the substrate. Therefore, when the ultrasonic transducer element chip is pressed against a target to be tested, the ultrasonic transducer element chip will often be damaged.

According to at least one embodiment of the present invention, an ultrasonic transducer element chip that is thin and has sufficient strength in a thickness direction of a substrate can be provided.

An ultrasonic transducer element chip according to one aspect of the present invention includes a substrate, a plurality of ultrasonic transducer elements and a plate-shaped member. The substrate includes a partition wall section defining a plurality of openings arranged in an array pattern. A wall thickness of the partition wall section is smaller than a wall height of partition wall section. Each of the ultrasonic transducer elements is provided in each of the openings. The plate-shaped member is fixed on a surface of the substrate opposite to a surface of the substrate on which the ultrasonic transducer elements are provided. The plate-shaped member covers at least one of the openings in a plan view seen along a thickness direction of the substrate.

In this ultrasonic transducer element chip, the ultrasonic transducer element can be formed to be thin. The ultrasonic transducer element can be formed in a thin substrate. Even in a case where the plate-shaped member is fixed to a substrate, the ultrasonic transducer element chip can be formed to be thin. At the same time, the plate-shaped member reinforces the strength of the substrate. In particular, since the wall thickness of the partition wall section between the openings is smaller than the wall height of the partition wall section between the openings, the sufficient rigidity of the partition wall section can be obtained in the thickness direction of the substrate due to the section modulus. Force in the thickness direction of the substrate is transmitted through the partition wall section and supported by the plate-shaped member. In this manner, the ultrasonic transducer element chip has sufficient strength in the thickness direction of the substrate. Here, the partition wall section corresponds to parts of the substrate sandwiched between spaces of the adjacent openings. The wall thickness refers to the thickness of the partition wall section, that is, the distance between the openings. When the wall surface of the partition wall section is a flat surface, the wall thickness can be defined as the length of the perpendicular line that is orthogonal to the wall surface. The wall height can be defined as the length of the wall surface defined in the thickness direction of the substrate.

In the ultrasonic transducer element chip, the plate-shaped member is preferably bonded to at least one bonding region of the partition wall section. When the partition wall section is bonded to the plate-shaped member, the movement of the partition wall section is restricted by the plate-shaped member. Thus, vibration of the partition wall section can be prevented. As a result, cross talk between the ultrasonic transducer elements can be prevented. Further, when the movement of the partition wall section is restricted, vibration of the partition wall section can be prevented from acting on ultrasonic vibration of the ultrasonic transducer elements. Then, ultrasonic vibration in a clear vibration mode can be obtained in the ultrasonic transducer elements. Consequently, when vibration of the partition wall section is avoided, the amplitude of ultrasonic vibration can be prevented from being decreased.

In the ultrasonic transducer element chip, the partition wall section is preferably arranged so that an outline of each the openings is defined as a quadrangle. When the openings having a quadrangular outline are adjacent to each other, the partition wall section has a uniform wall thickness. In particular, as the density of the ultrasonic transducer elements increases, the wall thickness of the partition wall section uniformly decreases. Therefore, the rigidity of the partition wall section is significantly deteriorated. In such an instance, by bonding the partition wall section to the plate-shaped member, vibration of the partition wall section can be effectively prevented.

In the ultrasonic transducer element chip, the quadrangle preferably has two opposed long sides, and the bonding region of the partition wall section is preferably a region including a center position of each of the long sides. Therefore, a part of the partition wall section in which the amplitude of vibration is large is bonded to the plate-shaped member. As a result, vibration of the partition wall section can be effectively prevented.

In the ultrasonic transducer element chip, the bonding region of the partition wall section is preferably a region including an entire length of each of the long sides. When the partition wall section is bonded to the plate-shaped member over the entire length of the long side, vibration of the partition wall section can be securely prevented.

In the ultrasonic transducer element chip, the partition wall section is preferably surface-bonded to the plate-shaped member over an entire surface corresponding to each of the long sides disposed between the openings. When the partition wall section is surface-bonded to the plate-shaped member with respect to the entire surface between the openings over the entire length of the long side, vibration of the partition wall section can be securely prevented.

In the ultrasonic transducer element chip, the partition wall section corresponding to each side of the quadrangle preferably includes the bonding region. When the partition wall section is bonded to the plate-shaped member in each side of the quadrangle, vibration of the partition wall section can be securely prevented.

In the ultrasonic transducer element chip, the bonding region of the partition wall section preferably continuously surrounds the quadrangle. When the partition wall section is bonded to the plate-shaped member with respect to the entire region of the quadrangle, vibration of the partition wall section can be securely prevented.

In the ultrasonic transducer element chip, the partition wall section is preferably surface-bonded to the plate-shaped member over an entire surface corresponding to an entire periphery of the quadrangle. When the partition wall section is surface-bonded to the plate-shaped member with respect to the entire surface between the openings over the entire periphery of the quadrangle, vibration of the partition wall section can be securely prevented.

A probe according to another aspect of the present invention includes the ultrasonic transducer element chip as described above, and a case member supporting the ultrasonic transducer element chip.

An electronic instrument according to another aspect of the present invention includes the probe as described above, and a processing circuit connected to the probe and configured to process an output signal from the ultrasonic transducer element.

An ultrasonic diagnostic according to another aspect of the present invention includes the probe as described above, a processing circuit connected to the probe and configured to process an output signal from the ultrasonic transducer element to generate an image, and a display device configured to display the image.

A probe head according to another aspect of the present invention includes the ultrasonic transducer element chip as described above, and a case member supporting the ultrasonic transducer element chip, and configured to be coupled to a probe main body.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Next, embodiments of the present invention will be explained with reference to the attached drawings. The embodiments explained below shall not be construed as unreasonably limiting the subject matter of the present invention described in the claims, and all the elements explained in the embodiments are not necessarily essential to the solving means of the present invention.

(1) Overall Configuration of Ultrasonic Diagnostic Device

FIG. 1schematically shows a configuration of an ultrasonic diagnostic device11as an example of an electronic instrument according to an embodiment of the present invention. The ultrasonic diagnostic device11is provided with a device terminal12and an ultrasonic probe13(one example of a probe). The device terminal12and the ultrasonic probe13are connected to each other through a cable14. The device terminal12and the ultrasonic probe13communicate an electric signal through the cable14. A display panel15(one example of a display device) is incorporated in the device terminal12. A screen of the display panel15is exposed on a surface of the device terminal12. As described later, in the device terminal12, an image is generated based on ultrasonic waves detected with the ultrasonic probe13. Imaged detection results are displayed on the screen of the display panel15.

As shown inFIG. 2, the ultrasonic probe13has a case16(one example of a case member). An ultrasonic transducer element chip (hereinafter referred to as “element chip”)17is accommodated in the case16. A surface of the element chip17may be exposed on a surface of the case16. The element chip17outputs ultrasonic waves from the surface thereof, and receives reflected waves of ultrasonic waves. Also, the ultrasonic probe13may be provided with a probe head13bremovably coupled with a probe main body13a. In such an instance, the element chip17may be incorporated in the case16of the probe head13b, and the case16of the probe head13bis configured to be coupled to the probe main body13a.

(2) Configuration of Ultrasonic Transducer Element Chip

FIG. 3schematically shows a plan view of the element chip17according to an embodiment of the present invention. The element chip17is provided with a substrate21. An element array22is formed on a surface of the substrate21. The element array22is constructed with an arrangement of an ultrasonic transducer element (hereinafter referred to as “element”)23. The arrangement is formed in a matrix having a plurality of columns and a plurality of rows. Each element23has a piezoelectric element section. The piezoelectric element section is constructed of a lower electrode24, an upper electrode25, and a piezoelectric film26. The piezoelectric film26is sandwiched between the lower electrode24and the upper electrode25in each element23.

The lower electrode24has a plurality of first conductive bodies24a. The first conductive bodies24aextend in a row direction of the arrangement in parallel to each other. One first conductive body24ais assigned to each row of the elements23. One first conductive body24ais provided in common with respect to the piezoelectric films26of the elements23lined up in the row direction of the arrangement. Both ends of the first conductive body24aare connected to a pair of extraction wirings27, respectively. The extraction wirings27extend in a column direction of the arrangement in parallel to each other. All the first conductive bodies24ahave the same length. In this manner, the lower electrode24is provided in common with respect to the elements23of the entire matrix.

The upper electrode25has a plurality of second conductive bodies25a. The second conductive bodies25aextend in a column direction of the arrangement in parallel to each other. One second conductive body25ais assigned to each column of the elements23. One second conductive body25ais provided in common with respect to the piezoelectric films26of the elements23lined up in the column direction of the arrangement. Power distribution to the elements23is switched per column. Line scanning or sector scanning is achieved corresponding to such switching of power distribution. Since the elements23in one column output ultrasonic waves at the same time, the number of the elements23in one column, that is, the row number of the arrangement can be determined based on the output level of ultrasonic waves. For example, the row number may be set to be around 10-15. In the drawing, five rows are illustrated for simplicity. The column number of the arrangement can be determined based on the extent of an area to be scanned. For example, the column number may be set to be 128 or 256. In the drawing, eight columns are illustrated for simplicity. Regarding the arrangement, a zigzag pattern may be used. In the zigzag pattern, a group of the elements23in an even column may be displaced with respect to a group of the elements23in an odd column by one-half of the row pitch. The number of the elements in one of an odd column and an even column may be smaller than the number of the elements in the other of an odd column and an even column by one. Further, the role of the lower electrode24and the role of the upper electrode25may be switched. Specifically, the upper electrode may be connected in common to the elements23of the entire matrix, and the lower electrode may be connected in common to the elements23in each column of the arrangement.

The outer edge of the substrate21has a first side21aand a second side21bthat are opposed and partitioned by a pair of straight lines29parallel to each other. A peripheral region31extends between the outline of the element array22and the outer edge of the substrate21. In the peripheral region31, a first terminal array32aof one line is arranged between the first side21aand the outline of the element array22, and a second terminal array32bof one line is arranged between the second side21band the outline of the element array22. The line of the first terminal array32acan be made parallel to the first side21a. The line of the second terminal array32bcan be made parallel to the second side21b. The first terminal array32ais constructed of a pair of lower electrode terminals33and a plurality of upper electrode terminals34. Similarly, the second terminal array32bis constructed of a pair of lower electrode terminals35and a plurality of upper electrode terminals36. The lower electrode terminal33and the lower electrode terminal35are connected to both ends of each of the extraction wiring27, respectively. It is sufficient for the extraction wirings27, the lower electrode terminals33and the lower electrode terminals35to be formed plane-symmetrically with respect to a vertical plane that bisects the element array22. The upper electrode terminal34and the upper electrode terminal36are connected to both ends of each of the second conductive bodies25a, respectively. It is sufficient for the second conductive bodies25a, the upper electrode terminals34and the upper electrode terminals36to be formed plane-symmetrically with respect to the vertical plane that bisects the element array22.

A first flexible printed substrate37is coupled with the substrate21. The first flexible printed substrate37covers the first terminal array32a. Conductive line, that is, first signal lines38are formed at one end of the first flexible printed substrate37corresponding to the lower electrode terminals33and the upper electrode terminals34, respectively. The first signal lines38are respectively opposed to the lower electrode terminals33and the upper electrode terminals34, and respectively bonded thereto. Similarly, a second flexible printed substrate41is coupled with the substrate21. The second flexible printed substrate41covers the second terminal array32b. Conductive lines, that is, second signal lines42are formed at a first end41aof the second flexible printed substrate41corresponding to the lower electrode terminals35and the upper electrode terminals36, respectively. The second signal lines42are respectively opposed to the lower electrode terminals35and the upper electrode terminals36, and respectively bonded thereto.

As shown inFIG. 4, each of the elements23has a vibrating film43. In order to achieve the vibrating film43, an opening45is formed in each of the elements23on a substrate base44of the substrate21. The openings45are arranged in an array pattern with respect to the substrate base44. A flexible film46is formed all over a surface of the substrate base44. The flexible film46is constructed of a silicon oxide (SiO2) layer47layered on the surface of the substrate base44, and a zirconium oxide (ZrO2) layer48layered on a surface of the silicon oxide layer47. The flexible film46contacts the openings45. In this manner, a part of the flexible film46serves as the vibrating film43corresponding to the outline of the opening45. The film thickness of the silicon oxide layer47can be determined based on the resonance frequency.

The lower electrode24, the piezoelectric film26, and the upper electrode25are layered on a surface of the vibrating film43in this order. As for the lower electrode24, a layered film of titanium (Ti), iridium (Ir), platinum (Pt), and titanium (Ti) can be used, for example. The piezoelectric film26may be formed of piezoelectric zirconate titanate (PZT), for example. The upper electrode25may be formed of iridium (Ir), for example. Another conductive material may be used for the lower electrode24and the upper electrode25. Another piezoelectric material may be used for the piezoelectric film26. The piezoelectric film26completely covers the lower electrode24under the upper electrode25. The function of the piezoelectric film26prevents short circuit between the upper electrode25and the lower electrode24from occurring.

A protective film49is layered on the surface of the substrate21. The protective film49covers, for example, the entire surface of the substrate21. As a result, the protective film49covers the element array22, the first terminal array32a, the second terminal array32b, a first end37aof the first flexible printed substrate37, and the first end41aof the second flexible printed substrate41. For example, a silicone resin film may be used for the protective film49. The protective film49protects the configuration of the element array22, the bonding of the first terminal array32aand the first flexible printed substrate37, and the bonding of the second terminal array32band the second flexible printed substrate41.

A partition wall51(one example of a partition wall section) is laid out between the openings45adjacent in the row direction and the column direction of the matrix. The openings45are partitioned by the partition wall51. The wall thickness “t” of the partition wall51corresponds to the distance between the hollow spaces of the openings45. The partition wall51has two wall surfaces in planes extending in parallel to each other. The wall thickness “t” of the partition wall51corresponds to the distance between the wall surfaces. Specifically, the wall thickness “t” of the partition wall51corresponds to the length of a perpendicular line that is orthogonal to the wall surfaces and is sandwiched by the wall surfaces. When the wall thickness of the partition wall51varies along the thickness direction of the substrate21(for example, seeFIG. 10), the wall thickness “t” refers to a maximum length between the wall surfaces of the partition wall51. The wall height “H” of the partition wall51corresponds to the depth of the opening45. The depth of the opening45corresponds to the thickness of the substrate base44. Therefore, the wall height “H” of the partition wall51can be defined as the length of the wall surface defined in the thickness direction of the substrate base44. Since the substrate base44has a uniform thickness, the partition wall51can have a uniform wall height “H” over the entire length. When the wall thickness “t” of the partition wall51is decreased, the arrangement density of the vibrating film43can be increased. This can contribute to downsizing of the element chip17. When the wall height “H” of the partition wall51is larger than the wall thickness “t” of the partition wall51, the bending rigidity of the element chip17can be increased. Consequently, the distance between the openings45is set to be smaller than the depth of the opening45.

A reinforcing plate52(one example of a plate-shaped member) is fixed to a rear surface of the substrate base44. The rear surface of the substrate base44is layered on a surface of the reinforcing plate52. The surface of the reinforcing plate52extends in a hypothetical plane HP. Since the rear surface of the substrate base44also extends in the hypothetical plane HP, the rear surface of the substrate base44can contact the surface of the reinforcing plate52with an area as large as possible. The reinforcing plate52closes the openings45in a rear surface of the element chip17. The reinforcing plate52covers the openings45in a plan view along a thickness direction of the substrate base44. The reinforcing plate52may have a rigid base material. For example, the reinforcing plate52may be formed of a silicon base plate. The plate thickness of the substrate base44is set to be around 100 μm, and the plate thickness of the reinforcing plate52is set to be around 100-150 μm. The partition walls51are bonded to the reinforcing plate52. The reinforcing plate52is bonded to each of the partition walls51in at least one bonding region. An adhesive can be used for bonding.

As shown inFIG. 5, the openings45form a line in a first direction D1. The centroids45cof the outlines of the openings45are located on a straight line56in the first direction D1at equal pitches. Since the openings45are formed by copying a single outline shape, the openings45of the same shape are repeatedly arranged at uniform pitches. For example, an outline45aof the opening45is defined as a quadrangle. Specifically, the outline45aof the opening45is formed in a rectangle. The long side of the rectangle is made to coincide with the first direction D1. Since the opening45has the rectangular outline45a, the partition wall51can have a uniform wall thickness “t” over the entire length. In such an instance, the bonding region of the partition walls51may be a region that includes a center position of the long side. In particular, the bonding region of the partition walls51may be a region that includes the entire length of the long side. The partition walls51may be surface-bonded to the reinforcing plate52with respect to the entire surface between the openings45over the entire length of the long side. The bonding region of the partition walls51may be located in at least one position of each side of the quadrangle. The bonding region of the partition walls51may continuously surround the quadrangle. The partition walls51may be surface-bonded to the reinforcing plate52with respect to the entire surface between the openings45over the entire periphery of the quadrangle.

(3) Circuit Configuration of Ultrasonic Diagnostic Device

As shown inFIG. 6, an integrated circuit has a multiplexer61, and a transmitting and receiving circuit62. The multiplexer61has a group of ports61aon the element chip17side, and a group of ports61bon the transmitting and receiving circuit62side. The first signal lines38and the second signal lines42are connected to the group of ports61avia first wirings54. In this manner, the group of ports61aare connected to the element array22. Signal lines63are connected to the group of ports61bon the transmitting and receiving circuit62side, and the number of the signal lines63is a prescribed number in an integrated circuit chip55. The prescribed number corresponds to a column number of the elements23output at the same time as scanning is conducted. The multiplexer61controls interconnection between the ports on the cable14side and the ports on the element chip17side.

The transmitting and receiving circuit62has changing switches64of a prescribed number. The changing switches64are connected to the corresponding signal lines63, respectively. The transmitting and receiving circuit62has a transmission channel65and a reception channel66for each of the changing switches64. The transmission channel65and the reception channel66are connected to the changing switch64in parallel. The changing switch64selectively connects the transmission channel65and the reception channel66to the multiplexer61. A pulser67is incorporated in the transmission channel65. The pulser67outputs a pulse signal at a frequency corresponding to the resonance frequency of the vibrating film43. An amplifier68, a low-pass filter (LPF)69, and an analog-digital converter (ADC)71are incorporated in the reception channel66. A detection signal of each of the elements23is amplified, and converted into a digital signal.

The transmitting and receiving circuit62has a driving/receiving circuit72. The transmission channel65and the reception channel66are connected to the driving/receiving circuit72. The driving/receiving circuit72controls the pulser67simultaneously depending on the state of scanning. The driving/receiving circuit72receives a digital signal of a detection signal depending on the state of scanning. The driving/receiving circuit72is connected to the multiplexer61through a control line73. The multiplexer61conducts control of interconnection based on a control signal supplied from the driving/receiving circuit72.

A processing circuit74is incorporated in the device terminal12. The processing circuit74can be provided with a central processing unit (CPU) and a memory, for example. The entire operation of the ultrasonic diagnostic device11is controlled in accordance with processing of the processing circuit74. The processing circuit74controls the driving/receiving circuit72in accordance with instructions input by a user. The processing circuit74generates an image in accordance with a detection signal of the element23. The image is specified by drawing data.

A drawing circuit75is incorporated in the device terminal12. The drawing circuit75is connected to the processing circuit74. The display panel15is connected to the drawing circuit75. The drawing circuit75generates a driving signal in accordance with drawing data generated in the processing circuit74. The driving signal is sent to the display panel15. As a result, an image is displayed on the display panel15.

(4) Operation of Ultrasonic Diagnostic Device

Next, the operation of the ultrasonic diagnostic device11will be explained briefly. The processing circuit74gives the driving/receiving circuit72instructions to transmit and receive ultrasonic waves. The driving/receiving circuit72supplies a control signal to the multiplexer61, and supplies a driving signal to each of the pulsers67. The pulser67outputs a pulse signal in response to the supply of the driving signal. The multiplexer61connects the port of the group of ports61ato the port of the group of ports61bin response to the instructions of the control signal. The pulse signal is supplied to the elements23per column through the lower electrode terminals33,35and the upper electrode terminals34,36in response to the selection of the port. The vibrating film43vibrates in response to the supply of the pulse signal. As a result, desired ultrasonic waves are emitted toward a target (for example, the inside of a human body).

After ultrasonic waves are transmitted, the changing switch64is switched. The multiplexer61maintains the connection relation of the ports. The changing switch64establishes a connection between the reception channel66and the signal line63instead of a connection between the transmission channel65and the signal line63. Reflected waves of ultrasonic waves vibrate the vibrating film43. As a result, a detection signal is output from the element23. The detection signal is converted into a digital signal, and sent into the driving/receiving circuit72.

Transmission and reception of ultrasonic waves are repeated. For repeating transmission and reception of ultrasonic waves, the multiplexer61changes the connection relation of the ports. As a result, line scanning or sector scanning is achieved. When scanning is finished, the processing circuit74generates an image based on the digital signal of the detection signal. The generated image is displayed on the screen of the display panel15.

In the element chip17, the element23can be formed to be thin. The element23can be formed on the thin substrate21. Even in a case where the reinforcing plate52is fixed to the substrate21, the element chip17can be formed to be thin. At the same time, the reinforcing plate52reinforces the strength of the substrate21. In particular, since the wall thickness “t” is smaller than the wall height “H” in the partition wall51, the sufficient rigidity of the partition wall51can be obtained in the thickness direction of the substrate21due to the section modulus. Force in the thickness direction of the substrate21is transmitted through the partition wall51and supported by the reinforcing plate52. In this manner, the element chip17has sufficient strength in the thickness direction of the substrate21. Accordingly, even when the plate thickness of the substrate21is set to be around 100 μm, for example, the reinforcing plate52can prevent the substrate21from being damaged. On the other hand, in a case where the element array is constructed of a bulk-type ultrasonic transducer element, the plate thickness of the substrate is set to be around several millimeters. Even when the reinforcing plate52is bonded, the thickness of the element chip17according to the present embodiment can be reduced securely compared to the case where the element array is constructed of a bulk-type ultrasonic transducer element. In addition, since the acoustic impedance of the vibrating film43is close to that of a human body compared to a bulk-type ultrasonic transducer element, an acoustic impedance matching layer can be omitted in the element chip17unlike in the case of a bulk-type ultrasonic transducer element. Omission of the matching layer can further contribute to making the element chip17thinner.

The reinforcing plate52is bonded to each of the partition walls51in at least one bonding region. When the partition walls51are bonded to the reinforcing plate52, the movement of the partition walls51is restricted by the reinforcing plate52. Thus, vibration of the partition walls51can be prevented. As a result, cross talk between the elements23can be prevented. Further, when the movement of the partition walls51is restricted, vibration of the partition walls51can be prevented from acting on ultrasonic vibration of the elements23. Then, ultrasonic vibration in a clear vibration mode can be obtained in the elements23. When vibration of the partition walls51is avoided, the amplitude of ultrasonic vibration can be prevented from being decreased. On the other hand, when the partition wall51moves, a distorted vibration mode having a lower frequency than the vertical vibration mode of the vibrating film43occurs. Furthermore, the kinetic energy of the vibrating film43decreases by the movement of the partition wall51, and the amplitude of the vibration decreases.

When the openings45having a quadrangular outline are adjacent to each other, the partition walls51can be formed to have a uniform wall thickness “t”. Thus, the density of the elements23can be increased. As the density of the elements23increases, the wall thickness “t” of the partition walls51uniformly decreases. Therefore, the rigidity of the partition walls51is significantly deteriorated. In such an instance, by bonding the partition walls51to the reinforcing plate52, vibration of the partition walls51can be effectively prevented.

The bonding region of the partition walls51can be a region that includes a center position of the long side. Therefore, a part of the partition walls51in which the amplitude of vibration is large is bonded to the reinforcing plate52. As a result, vibration of the partition walls51can be effectively prevented. Also, the bonding region of the partition walls51can be a region that includes the entire length of the long side. When the partition walls51are bonded to the reinforcing plate52over the entire length of the long side, vibration of the partition walls51can be securely prevented. Further, the partition walls51can be surface-bonded with respect to the entire surface between the openings45over the entire length of the long side. When the partition walls51are surface-bonded to the reinforcing plate52with respect to the entire surface between the openings45over the entire length of the long side, vibration of the partition walls51can be securely prevented.

It is sufficient that the bonding region of the partition walls51is located in at least one position of each side of the quadrangle. When the partition walls51are bonded to the reinforcing plate52in each side of the quadrangle, vibration of the partition walls51can be securely prevented. Also, the bonding region of the partition walls51can continuously surround the quadrangle. When the partition walls51are bonded to the reinforcing plate52with respect to the entire region of the quadrangle, vibration of the partition walls51can be securely prevented. Further, the partition walls51can be surface-bonded with respect to the entire surface between the openings45over the entire periphery of the quadrangle. When the partition walls51are surface-bonded to the reinforcing plate52with respect to the entire surface between the openings45over the entire periphery of the quadrangle, vibration of the partition walls51can be securely prevented.

(5) Method for Manufacturing Ultrasonic Transducer Element Chip

As shown inFIG. 7, the lower electrode24, the extraction wiring27, and the lower electrode terminals33,35(not shown in the drawings subsequent toFIG. 7) are formed on a surface of a silicon wafer78per each element chip17. Prior to forming the lower electrode24, the extraction wiring27, and the lower electrode terminals33,35, a silicon oxide film79and a zirconium oxide film81are formed on the surface of the silicon wafer78one after another. A conductive film is formed on a surface of the zirconium oxide film81. The conductive film is constructed as a layered film of titanium, iridium, platinum, and titanium. The lower electrode24, the extraction wiring27, and the lower electrode terminals33,35are formed from the conductive film by a photolithographic technique.

As shown inFIG. 8, the piezoelectric film26and the upper electrode25are formed on a surface of the lower electrode24per each element23. Prior to forming the piezoelectric film26and the upper electrode25, a piezoelectric material film and a conductive film are formed on the surface of the silicon wafer78. The piezoelectric material film is constructed of a PZT film. The conductive film is constructed of an iridium film. The piezoelectric film26and the upper electrode25are formed from the piezoelectric material film and the conductive film per each element23by a photolithographic technique.

Next, as shown inFIG. 9, a conductive film82is formed on the surface of the silicon wafer78. The conductive film82connects the upper electrodes25with respect to each other per column in each element chip17. The upper electrode25and the upper electrode terminals34,36are formed from the conductive film82by a photolithographic technique.

Next, as shown inFIG. 10, the openings45of an array pattern are formed from the rear surface of the silicon wafer78. For forming the openings45, an etching treatment is conducted. The silicon oxide film79serves as an etching stop layer. The vibrating film43is divided into the silicon oxide film79and the zirconium oxide film81. After the openings45are formed, a surface of a wafer83for a reinforcing plate is layered on the rear surface of the silicon wafer78. For example, a rigid insulating substrate can be used for the wafer83. A silicon wafer can be used for the insulating substrate. For example, an adhesive can be used for bonding. After bonding, each of the element chip17is cut out of the silicon wafer78.

While the present embodiment has been explained in detail as above, it will be apparent to those skilled in the art that various changes and modifications can be made herein without substantially departing from the subject matter and the effect of the present invention. Therefore, such changes and modifications are included in the scope of the invention. For example, the terms used in the specification or the drawings at least once together with a different term having a broader or similar meaning can be replaced with the different term in any portion of the specification or the drawings. Also, the configurations and the operations of the ultrasonic diagnostic device11, the ultrasonic probe13, the element chip17, the element23and the like are not limited to the present embodiment, and various changes and modifications are possible.

General Interpretation of Terms