JP2016036071A - Ultrasonic probe and ultrasonic flaw probe system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic probe and an ultrasonic flaw probe system that can enhance the attenuation amount per unit time of ultrasonic waves and the height of the frequencies of the ultrasonic waves.SOLUTION: A piezoelectric material 11, and an upper electrode 12 and a lower electrode 13 which are provided at the upper and lower sides of the piezoelectric material 11 and has electrical conductivity. A sound wave propagation speed in the up-and-down direction has a dispersion characteristic, and the piezoelectric material 11 is formed such that the lattice constant in the up-and-down direction has a continuously varying concentration gradient so that the lattice constant approaches to the lattice constant of the upper electrode 12 or the lower electrode 13 as it is closer to at least one of the upper electrode 12 side and the lower electrode 13 side.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ultrasonic probe used for ultrasonic flaw detection and an ultrasonic flaw detection system using the same.

  As an inspection method for inspecting various structural materials or the like, for example, an ultrasonic wave is irradiated on the inspection object, an ultrasonic signal reflected by a defect or the like inside the inspection object is detected, and the propagation time of the ultrasonic signal is detected. An ultrasonic flaw detection method that detects a defect based on the position of the ultrasonic probe and the ultrasonic probe is known. In the ultrasonic flaw detection method, for example, an ultrasonic probe consisting of a single element is used for transmission and reception of ultrasonic waves, and the ultrasonic probe is moved to scan the inspection object, so that it is reflected from the defect. The position where the ultrasonic wave is obtained is identified and the defect is detected.

  As a technique related to such an ultrasonic probe, for example, Patent Document 1 (Japanese Patent No. 3357227) discloses a piezoelectric element having a sensitivity necessary for internal flaw detection of a material on a substrate. In the piezoelectric element having the formed lower electrode, the zinc oxide thin film formed on the lower electrode film, and the upper electrode formed on the zinc oxide thin film, sapphire is used as a substrate, and the zinc oxide thin film is obtained by X-ray A technique relating to a piezoelectric element in which the standard deviation σ of the rocking curve is limited is disclosed.

Japanese Patent No. 3357227

  By the way, when the ultrasonic flaw detection method is used with a structure having a fine structure such as a semiconductor chip as an inspection target, it is necessary to consider the attenuation characteristics and frequency of the ultrasonic wave transmitted to the inspection target. That is, considering separation of reflected waves from defects and reflected waves from other structures, attenuation per unit time needs to be high, and considering the detection of defects on the order of microns, the wavelength of ultrasonic waves Need to be short (high frequency).

  However, in the ultrasonic probe in the above prior art, the amount of attenuation and frequency of ultrasonic waves per unit time are insufficient, and a structure having a fine structure such as a semiconductor chip is to be inspected. The inspection was difficult.

  The present invention has been made in view of the above, and provides an ultrasonic probe capable of improving the attenuation amount and frequency height of ultrasonic waves per unit time and an ultrasonic flaw detection system using the same. For the purpose.

  In order to achieve the above object, the present invention comprises a piezoelectric material and conductive upper and lower conductors provided above and below the piezoelectric material, wherein the piezoelectric material has an acoustic wave propagation in the vertical direction. The lattice constant in the vertical direction has a dispersion characteristic, and the lattice constant becomes closer to the lattice constant of the upper conductor or the lower conductor as it approaches at least one of the upper conductor side or the lower conductor side. Have a concentration gradient that varies continuously.

  The amount of attenuation per ultrasonic wave and the height of the frequency can be improved.

It is a side view showing typically the composition of the ultrasonic probe concerning a 1st embodiment. 1 is a diagram schematically showing an overall configuration of an ultrasonic flaw detection system according to a first embodiment. It is a figure which shows typically an example of the frequency characteristic of the insertion loss of the ultrasonic probe in 1st Embodiment. It is a figure which shows typically an example of the attenuation | damping characteristic of the pulse wave transmitted by the ultrasonic probe in 1st Embodiment. It is a figure which shows typically an example of the frequency characteristic of the insertion loss of the ultrasonic probe in a prior art. It is a figure which shows typically an example of the attenuation characteristic of the pulse wave transmitted with the ultrasonic probe in a prior art. It is a side view which shows typically the structure of the ultrasonic probe which concerns on 2nd Embodiment. It is a side view which shows typically the structure of the ultrasonic probe which concerns on 3rd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
A first embodiment of the present invention will be described with reference to FIGS.

  FIG. 2 is a diagram schematically showing the overall configuration of the ultrasonic flaw detection system according to the present embodiment. FIG. 1 is a side view schematically showing the configuration of the ultrasonic probe.

  In FIG. 2, the ultrasonic flaw detection system schematically includes an ultrasonic probe 100, a scanning unit 101, a transmission / reception unit 102, a control unit 103, and a display unit 104.

  The control unit 103 controls the entire operation of the ultrasonic flaw detection system, and is connected to the ultrasonic probe 100, the scanning unit 101, the transmission / reception unit 102, and the display unit 104 via signal lines.

  The scanning unit 101 moves the ultrasonic probe 100 in a three-dimensional direction based on a control signal from the control unit 103. The ultrasonic probe 100 has a driving mechanism (not shown). Is mechanically attached to.

  Based on the control signal from the control unit 103, the transmission / reception unit 102 applies a voltage signal for driving the ultrasonic probe 100 to the ultrasonic probe 100 as a drive signal. The test object is irradiated with ultrasonic waves. In addition, a voltage signal generated in the ultrasonic probe 100 due to a reflected wave from the ultrasonic inspection object irradiated from the ultrasonic probe 100 is received as a reception signal and sent to the control unit 102.

  In addition to various setting screens, the display unit 104 displays information such as images and graphs generated based on received signals from the ultrasound probe 100.

  As shown in FIG. 1, the ultrasonic probe 100 includes a piezoelectric material 11, and conductive upper electrodes 12 (upper conductors) and lower electrodes 13 (lower conductors) provided above and below the piezoelectric material 11. And a rod substrate 14 provided below the lower electrode 13. Hereinafter, the direction of the upper electrode 12 will be described as being upward, and the direction of the lower electrode 13 will be described as being downward.

  The upper electrode 12 is connected to the transmission / reception unit 102 by a signal line, and the lower electrode 13 is grounded by the signal line. Examples of the material of the upper electrode 12 and the lower electrode 13 include gold (Au), silver (Ag), copper (Cu), silver (Ag), platinum (Pt), aluminum (Al), and titanium (Ti). The film is formed by sputtering or electron beam evaporation. Since the upper electrode 12 and the lower electrode 13 become a factor that lowers the resonance frequency of the ultrasonic probe 100 as the thickness increases, the film is formed at a thickness of 300 μm or less, for example. Note that the materials of the upper electrode 12 and the lower electrode 13 are not necessarily the same. As will be described later, a material having a higher matching rate in the lattice constant of the piezoelectric material 11 (in other words, a material having a closer lattice constant). Select and use each.

  The rod substrate 14 is formed to have a cylindrical cross-sectional shape, and the lower electrode 13 is connected to the upper surface of the rod substrate 14. The rod substrate 14 has a role of propagating an ultrasonic wave generated in the piezoelectric material 11 and transmitting the ultrasonic wave from the lower end surface to the inspection target, and propagating a reflected wave from the inspection target side to send it to the piezoelectric material 11. . That is, the rod substrate 14 has a role of an acoustic lens in the ultrasonic probe 100, and the end surface on the inspection target side is not limited to a planar shape, and transmits and receives ultrasonic waves with a focused or unfocused parallel beam. Furthermore, if it is formed in a spherical shape such as a concave shape or a convex shape, the performance as an acoustic lens can be enhanced.

  The material of the rod substrate 14 is a single crystal that has a small propagation attenuation when ultrasonic waves propagate through the rod substrate 14 in consideration of the propagation characteristics of ultrasonic waves in a high frequency band. As a material of the rod substrate 14, for example, a single crystal such as sapphire (Al2O3), quartz glass (SiO2), magnesium oxide (MgO), strontium titanate (SrTiO3) is used.

  The piezoelectric material 11 is formed so that the acoustic propagation velocity in the vertical direction has dispersion characteristics and has a concentration gradient in which the vertical lattice constant continuously changes.

  The piezoelectric material 11 shown in FIG. 1 is formed with a concentration gradient such that the lattice constant of the piezoelectric material 11 approaches the lattice constant of the lower electrode 13 as it approaches the lower electrode 13. That is, the concentration of inclusions in the upper part 11a, the middle part 11b, and the lower part 11c of the piezoelectric material 11 is higher than the matching ratio (closeness to the lattice constant) of the lattice constant of the upper part 11a and the lattice constant of the lower electrode 13. The matching rate between the lattice constant of the lower electrode 13 and the lattice constant of the lower electrode 13 is higher, and the gradient (concentration gradient) is such that the matching rate of the lattice constant of the lower electrode 11 and the lower electrode 13 is higher. The piezoelectric material 11 is formed.

  For the upper electrode 12, a material that is closer to the lattice constant of the upper electrode 12 is selected and used as the lattice constant of the piezoelectric material 11 approaches the upper electrode 12. That is, in other words, the concentration of inclusions in the upper part 11a, the middle part 11b, and the lower part 11c of the piezoelectric material 11 is more than the matching rate (closeness of the lattice constant) between the lattice constant of the lower part 11c and the lattice constant of the upper electrode 12. The gradient (concentration gradient) is such that the matching ratio between the lattice constant of the middle portion 11b and the lattice constant of the upper electrode 12 is higher and the matching ratio between the lattice constant of the upper portion 11a and the lattice constant of the upper electrode 12 is higher. It can be said that the piezoelectric material 11 is formed so as to have.

  The lattice constant of the piezoelectric material 11 changes depending on the concentration of the inclusion, and the piezoelectric material 11 is formed to have a gradient of the lattice constant by having a concentration gradient of the inclusion in the thickness direction (vertical direction). Has been. Moreover, the strength of the piezoelectric material 11 is improved as the lattice constant matching rate with the upper electrode 12 and the lower electrode 13 is higher (as the lattice constant is closer). Therefore, as in the present embodiment, the lattice constant matching ratio between the piezoelectric material 11 and the upper electrode 12 or the lower electrode 13 is increased while maintaining a high lattice constant matching ratio in the piezoelectric material 11. By constituting, the structural strength can be improved and the film thickness can be increased.

  Moreover, since the density, elastic constant, piezoelectric constant, and dielectric constant of the piezoelectric material 11 change according to the concentration change of the inclusion, the velocity (sound speed) of the elastic wave transmitted in the thickness direction changes. For example, in an ultrasonic probe using a piezoelectric material that does not have a speed change (concentration change in content) in the thickness direction, the resonance frequency is expressed by the following (Expression 1) or (Expression 2).

F = V / 2L (Formula 1)
F = V / 4L (Formula 2)
In the above (Expression 1) and (Expression 2), F indicates the resonance frequency, V indicates the speed of sound transmitted in the thickness direction of the piezoelectric material, and L indicates the thickness of the piezoelectric material.

  Which one of the above (Formula 1) and (Formula 2) is applied is determined by the ratio of the acoustic impedance of the piezoelectric material 11 and the acoustic impedance of the rod substrate 14. In any formula, when the thickness of the piezoelectric material 11 is constant in the plane direction (vertical direction), the resonance frequency F is determined by the speed of sound V transmitted in the thickness direction of the piezoelectric material 11.

  The material used for the piezoelectric material 11 is an oxide or nitride such as zinc oxide (ZnO), lead titanate (PbTiO3), bismuth titanate (Bi4Ti3O12), aluminum nitride (AlN), and gallium nitride (GaN). Among these, zinc oxide, aluminum nitride, lead titanate, and the like are characterized by being easy to manufacture and inexpensive. In addition, as materials (inclusions) to be included in these materials, materials such as magnesium (Mg), vanadium (V), scandium (Sc), sodium (Na), and zirconium (Zr) are used.

  The combination of the material and the inclusion of the piezoelectric material 11 is preferably one in which the change in sound speed due to the influence of the inclusion is large. For example, a combination of zinc oxide (ZnO: sound speed 6300 m / s) and magnesium (Mg) (Mg—ZnO: Sound velocity 4900 m / s), a combination of aluminum nitride (AlN: sound velocity: 11000 m / s) and scandium (Sc) (Sc—AlN: sound velocity 8000 m / s), lead titanate (PbTiO3: sound velocity 4400 m / s) and zirconium (Zr) ) (Pb (Zr, Ti) O3: speed of sound 4000 m / s).

  One of the materials for judging the performance of an ultrasonic probe is a frequency characteristic of insertion loss indicating the relationship between the conversion efficiency (electromechanical conversion efficiency) of an ultrasonic wave and an electric signal at each frequency. The insertion loss is the ratio of the energy of the voltage signal (drive signal) given to the piezoelectric material 11 and the energy of the voltage signal (received signal) generated when the piezoelectric material 11 receives ultrasonic waves.

  3 and 5 are diagrams schematically showing an example of the frequency characteristic of the insertion loss of the ultrasonic probe. FIG. 3 shows the frequency characteristic in the present embodiment, and FIG. 5 shows the frequency characteristic in the prior art. Each is shown. 3 and 5, the horizontal axis represents frequency and the vertical axis represents insertion loss. 4 and 6 are diagrams schematically showing an example of the attenuation characteristic of the pulse wave transmitted by the ultrasonic probe. FIG. 4 shows the characteristic in the present embodiment, and FIG. 6 shows the prior art. The characteristics in are shown respectively. 4 and 6, the vertical axis represents the amplitude value of the pulse wave, and the horizontal axis represents time.

  As shown in FIG. 5, in the frequency characteristics of the insertion loss in the prior art, the insertion loss becomes the smallest at the resonance frequency F0, but the insertion loss suddenly increases as the distance from the resonance frequency F0 increases. On the other hand, in the present embodiment, the piezoelectric material 11 is formed so as to have a concentration gradient of inclusions in the vibration direction (vertical direction), so that the insertion loss of the present embodiment is reduced as shown in FIG. The frequency characteristic has a characteristic that the insertion loss is the smallest at the resonance frequency F0, and the frequency band with a small insertion loss is a wide band as compared with the frequency characteristic of the insertion loss in the prior art (see FIG. 5). Therefore, the pulse wave in the prior art has a small time ratio of the amplitude attenuation amount (see FIG. 6), but in the present embodiment, the amplitude attenuation amount per unit time is large as shown in FIG. A pulse wave (having good attenuation characteristics) can be transmitted.

  The piezoelectric material 11 needs to be a micron-order thin film for the operation of the ultrasonic probe at a high frequency. Therefore, as a method for manufacturing a piezoelectric material, for example, there are a physical deposition method (PVD method), a chemical deposition method (CVD method), and the like, which are manufactured using a sputtering method, a PLD method (pulse laser deposition method), a sol-gel method, and the like. To do.

  In the sputtering method and the PLD method, a method of forming a film by mixing inclusions with the bulk target of the piezoelectric material 11, a method of forming a film by separately setting the bulk target and the inclusions, and supplying the contents in a gas atmosphere. There is a method of forming a film. In addition, the sol-gel method includes a method in which the raw material and contents of the piezoelectric material 11 are dissolved in a solvent, and a film is formed while changing the concentration of the contents.

  The effect of the present embodiment configured as described above will be described.

  When an ultrasonic flaw detection method is used with a structure having a fine structure such as a semiconductor chip as an inspection target, it is necessary to consider the attenuation characteristics and frequency of the ultrasonic wave transmitted to the inspection target. That is, considering separation of reflected waves from defects and reflected waves from other structures, attenuation per unit time needs to be high, and considering the detection of defects on the order of microns, the wavelength of ultrasonic waves Need to be short (high frequency). However, in the ultrasonic probe in the above prior art, the amount of attenuation and frequency of ultrasonic waves per unit time are insufficient, and a structure having a fine structure such as a semiconductor chip is to be inspected. The inspection was difficult.

  On the other hand, in the present embodiment, the piezoelectric constant of the piezoelectric material 11 has a dispersion characteristic in the vertical direction, and the lattice constant increases as it approaches at least one of the upper electrode 12 side or the lower electrode 13 side. Since it is configured to have a concentration gradient in which the lattice constant in the vertical direction changes continuously so as to be close to the lattice constant of the upper electrode 12 or the lower electrode 13, the attenuation amount and frequency of ultrasonic waves per unit time are increased. Can be improved.

  That is, in the present embodiment, since the piezoelectric material 11 is configured to have a concentration gradient in the vibration direction (vertical direction), the attenuation per unit time is improved by widening the insertion loss of ultrasonic waves. Therefore, the reflected wave from the defect and the reflected wave from other structures can be separated with high accuracy.

  Further, in the prior art, since the piezoelectric material 11 needs to be a micron-order thin film, when the manufacturing method such as the physical deposition method (PVD method) or the chemical deposition method (CVD method) is used, the film thickness is insufficient due to insufficient structural strength. It was not possible to increase the thickness, and only a frequency higher than the desired resonance frequency was obtained. In contrast, in the present embodiment, the piezoelectric material 11 is configured to have a concentration gradient such that the lattice constant becomes closer as it approaches the upper electrode 12 and the lower electrode 13, thereby improving the structural strength. Can be made thicker. Therefore, a desired resonance frequency can be obtained by increasing the thickness of the piezoelectric material 11.

  Further, according to the present embodiment, it is possible to widen the frequency characteristics of ultrasonic waves and increase the frequency, thereby enabling high-resolution flaw detection and imaging.

<Second Embodiment>
A second embodiment of the present invention will be described with reference to FIG.

  In this embodiment, the piezoelectric material in the first embodiment has a different concentration gradient.

  FIG. 7 is a side view schematically showing the configuration of the ultrasonic probe according to the present embodiment. In the figure, the same members as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In FIG. 7, an ultrasonic probe 200 includes a piezoelectric material 21, an upper electrode 22 (upper conductor) and a lower electrode 23 (lower conductor) having conductivity provided above and below the piezoelectric material 21, and a lower portion. And a rod substrate 24 provided below the electrode 23. Hereinafter, the direction of the upper electrode 22 will be described as being upward, and the direction of the lower electrode 23 will be described as being downward.

  The upper electrode 22 is connected to the transmission / reception unit 102 by a signal line, and the lower electrode 23 is grounded by the signal line. Examples of the material of the upper electrode 22 and the lower electrode 23 include gold (Au), silver (Ag), copper (Cu), silver (Ag), platinum (Pt), aluminum (Al), and titanium (Ti). The film is formed by sputtering or electron beam evaporation. Since the upper electrode 22 and the lower electrode 23 cause a decrease in the resonance frequency of the ultrasonic probe 200 as the thickness increases, the upper electrode 22 and the lower electrode 23 are formed with a thickness of 300 μm or less, for example. Note that the materials of the upper electrode 22 and the lower electrode 23 are not necessarily the same. As will be described later, a material having a higher matching rate in the lattice constant of the piezoelectric material 21 (in other words, a material having a closer lattice constant). Select and use each.

  The piezoelectric material 21 is formed so that the acoustic wave velocity in the vertical direction has a dispersion characteristic and has a concentration gradient in which the vertical lattice constant continuously changes.

  7 is closer to the lower electrode 23, the lattice constant of the piezoelectric material 21 is closer to the lattice constant of the lower electrode 23 and closer to the upper electrode 22, the lattice of the piezoelectric material 21 is closer to the lower electrode 23. It is formed with a concentration gradient such that the constant is close to the lattice constant of the upper electrode 22. That is, the concentration of inclusions in the upper part 21a, the middle part 21b, and the lower part 21c of the piezoelectric material 21 is higher than the matching ratio (closeness of the lattice constant) of the lattice constant of the middle part 21b and the lattice constant of the lower electrode 23. It has a gradient (concentration gradient) in which the lattice constant and the lattice constant of the lower electrode 23 have a higher matching ratio (concentration gradient), and further, the matching ratio of the lattice constant of the middle part 21b and the lattice constant of the upper electrode 22 (closeness of the lattice constant). ), The piezoelectric material 21 is formed so as to have a gradient (concentration gradient) in which the matching rate between the lattice constant of the upper portion 21a and the lattice constant of the upper electrode 22 is higher.

  The lattice constant of the piezoelectric material 21 varies depending on the concentration of the inclusion, and the piezoelectric material 21 is formed to have a gradient of the lattice constant by having a concentration gradient of the inclusion in the thickness direction (vertical direction). Has been. Moreover, the strength of the piezoelectric material 21 is improved as the lattice constant matching rate with the upper electrode 22 and the lower electrode 23 is higher (as the lattice constant is closer). Therefore, as in the present embodiment, the lattice constant matching ratio between the piezoelectric material 21 and the upper electrode 22 or the lower electrode 23 is increased while maintaining a high lattice constant matching ratio in the piezoelectric material 21. By constituting, the structural strength can be improved and the film thickness can be increased.

  Other configurations are the same as those of the first embodiment.

  Also in the present embodiment configured as described above, the same effects as those of the first embodiment can be obtained.

  In addition, even when the material of the upper electrode and the lower electrode is selected in consideration of the matching rate with the lattice constant of the piezoelectric material, it is possible to select the same material for the upper electrode and the lower electrode. It can be manufactured simply and inexpensively.

<Third Embodiment>
A third embodiment of the present invention will be described with reference to FIG.

  In this embodiment, the lower electrode is not provided in the first embodiment.

  FIG. 8 is a side view schematically showing the configuration of the ultrasonic probe according to the present embodiment. In the figure, the same members as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In FIG. 8, the ultrasonic probe 300 includes a piezoelectric material 31, a conductive upper electrode 32 (upper conductor) provided on the piezoelectric material 31, and a conductive material provided on the lower portion of the piezoelectric material 21. The rod board | substrate 34 which has property. In the following description, the direction of the upper electrode 32 is the upper side and the direction of the rod substrate 34 is the lower side.

  The upper electrode 32 is connected to the transmission / reception unit 102 by a signal line, and the rod substrate 34 is grounded by the signal line. Examples of the material of the upper electrode 32 include gold (Au), silver (Ag), copper (Cu), silver (Ag), platinum (Pt), aluminum (Al), and titanium (Ti). The film is formed by the method or the electron beam evaporation method. Since the upper electrode 32 becomes a factor that lowers the resonance frequency of the ultrasonic probe 200 as the thickness increases, the upper electrode 32 is formed with a thickness of 300 μm or less, for example.

  The material of the rod substrate 34 is a single crystal to which material is added. As a material of the rod substrate 34, for example, strontium titanate (SrTiO3) to which lanthanum (La), nickel (Ni), or the like is added is preferable. In this case, lead titanate is preferably used for the piezoelectric material 31.

  The piezoelectric material 31 is formed such that the acoustic wave velocity in the vertical direction has dispersion characteristics and has a concentration gradient in which the vertical lattice constant continuously changes.

  The piezoelectric material 31 shown in FIG. 8 is formed with a concentration gradient such that the lattice constant of the piezoelectric material 31 approaches the lattice constant of the rod substrate 34 as it approaches the rod substrate 34. That is, the concentration of inclusions in the upper portion 31a, the middle portion 31b, and the lower portion 31c of the piezoelectric material 31 is higher than the matching rate (closeness of the lattice constant) of the lattice constant of the upper portion 31a and the lattice constant of the rod substrate 34. The matching rate between the lattice constant of the rod substrate 34 and the lattice constant of the rod substrate 34 is higher, and the gradient (concentration gradient) is such that the matching rate of the lattice constant of the lower portion 31c and the lattice constant of the rod substrate 34 is higher. The piezoelectric material 31 is formed.

  For the upper electrode 32, a material that is closer to the lattice constant of the upper electrode 32 is selected and used as the lattice constant of the piezoelectric material 31 becomes closer to the upper electrode 32. That is, in other words, the concentration of inclusions in the upper part 31a, the middle part 31b, and the lower part 31c of the piezoelectric material 31 is more than the matching ratio (closeness of the lattice constant) between the lattice constant of the lower part 31c and the lattice constant of the upper electrode 32. The gradient (concentration gradient) is such that the matching ratio between the lattice constant of the middle part 31b and the lattice constant of the upper electrode 32 is higher, and the matching ratio of the lattice constant of the upper part 31a and the upper electrode 32 is higher. It can also be said that the piezoelectric material 31 is formed so as to have.

  The lattice constant of the piezoelectric material 31 changes depending on the concentration of the inclusion, and the piezoelectric material 31 is formed to have a gradient of the lattice constant by having a concentration gradient of the inclusion in the thickness direction (vertical direction). Has been. In addition, the piezoelectric material 31 has a higher strength as the lattice constant matching rate with the upper electrode 32 and the rod substrate 34 is higher (as the lattice constant is closer). Therefore, as in the present embodiment, the lattice constant matching ratio between the piezoelectric material 31 and the upper electrode 32 or the rod substrate 34 is increased while maintaining a high lattice constant matching ratio in the piezoelectric material 31. By constituting, the structural strength can be improved and the film thickness can be increased.

  Other configurations are the same as those of the first embodiment.

  Also in the present embodiment configured as described above, the same effects as those of the first embodiment can be obtained.

  In addition, since a rod substrate having conductivity is used and the lattice constant matching rate with the piezoelectric material is increased, the lower electrode is not required, and it can be manufactured easily and inexpensively.

11, 21, 31 Piezoelectric material 12, 22, 32 Upper electrode (upper conductor)
13, 23 Lower electrode (lower conductor)
14, 24 Rod substrate 34 Rod substrate (lower conductor)
DESCRIPTION OF SYMBOLS 100 Ultrasonic probe 101 Scan part 102 Transmission / reception part 103 Control part 104 Display part

Claims (9)

A piezoelectric material;
A conductive upper conductor and a lower conductor provided above and below the piezoelectric material;
The piezoelectric material has a dispersion characteristic in the acoustic wave velocity in the vertical direction, and the lattice constant becomes the lattice constant of the upper conductor or the lower conductor as it approaches at least one of the upper conductor side or the lower conductor side. An ultrasonic probe characterized by having a concentration gradient in which the lattice constant in the vertical direction changes continuously so as to be close. The ultrasonic probe according to claim 1,
A substrate provided under the lower conductor;
The ultrasonic probe according to claim 1, wherein the lower conductor is a lower electrode connected to a lower end of the piezoelectric element. The ultrasonic probe according to claim 1,
The ultrasonic probe according to claim 1, wherein the lower conductor is a conductive substrate connected to a lower end of the piezoelectric element. The ultrasonic probe according to any one of claims 1 to 3,
The ultrasonic probe, wherein the piezoelectric material is an oxide or a nitride. The ultrasonic probe according to claim 4,
The ultrasonic probe according to claim 1, wherein the piezoelectric material is formed of any one of zinc oxide (ZnO), aluminum nitride (AlN), and lead titanate (PbTiO3). The ultrasonic probe according to claim 4,
The ultrasonic probe, wherein the piezoelectric material is formed of zinc oxide (ZnO) containing magnesium (Mg). The ultrasonic probe according to claim 4,
The ultrasonic probe, wherein the piezoelectric material is formed of aluminum nitride (AlN) containing scandium (Sc). The ultrasonic probe according to claim 4,
The ultrasonic probe according to claim 1, wherein the piezoelectric material is formed of lead titanate (PbTiO3) containing zirconium (Zr). An ultrasonic probe comprising a piezoelectric material and a conductive upper conductor and a lower conductor provided above and below the piezoelectric material, wherein the piezoelectric material has a dispersion of acoustic propagation velocity in the vertical direction. The lattice constant in the vertical direction is continuous so that the lattice constant becomes closer to the lattice constant of the upper conductor or the lower conductor as it has characteristics and becomes closer to at least one of the upper conductor side or the lower conductor side. An ultrasonic probe having a concentration gradient that changes to
By applying a voltage signal as a drive signal between the upper conductor and the lower conductor, an ultrasonic wave is irradiated from the ultrasonic probe to the inspection object, and the ultrasonic wave is reflected by a reflected wave from the inspection object. An ultrasonic flaw detection system comprising: a transmission / reception unit that receives a voltage signal generated by a probe as a reception signal.

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