JPH0552120B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an ultrasonic transducer, and in particular to a high performance, small and lightweight electrostatic ultrasonic transducer that can be used for detecting proximity sense in industrial robots. The present invention relates to a structure of a transducer or an array thereof, and a method of manufacturing the transducer.

(Prior Art) Conventionally, in the field of industrial robots, solid-state image sensors such as CCDs that use visible light have been widely used to recognize the distance, size, shape, etc. of a target object. However, sensors that use visible light have the disadvantage that they cannot be used when the target object is transparent or when the medium between the sensor and the target object is dirty with dust or the like. Therefore, in recent years, a technology has appeared that attempts to use ultrasonic waves instead of visible light to recognize target objects. In an ultrasonic transducer, ultrasonic waves are transmitted and received by one or more devices, so there are mechanical elements that transmit and receive ultrasonic waves, and supporting oscillation circuits, receiving circuits, etc. It is necessary to combine electrical elements in a suitable manner. In particular, when trying to emit ultrasonic waves into the air by vibrating a certain surface, the response (acoustic impedance) of the air to that surface is very small compared to liquids or solids, so ultrasonic waves with high intensity are emitted. is difficult. Therefore, in addition to designing the mechanical elements mentioned above so that ultrasonic waves are emitted efficiently, it is also necessary to devise measures such as using an amplification compensation circuit to compensate for small signals and receive them in the electrical elements. be. Moreover, the ultrasonic transducers currently in general use have considerably large variations in the characteristics of these mechanical elements between devices, and cannot necessarily be said to be optimally designed. Furthermore, since the mechanical and electrical elements are not integrated, it is difficult to reduce the size and weight of the device. Hereinafter, a conventional example will be explained with reference to figures, and at the same time, its drawbacks will be discussed.

FIG. 4 is a diagram showing a cross section of a configuration example of a conventional ultrasonic transducer. In the figure, reference numeral 47 denotes a circular aluminum alloy plate, and a plurality of holes 101 having a depth of several to several tens of μm are formed on the surface by machining. On the upper surface of this hole 101, a polyester film 48 having a thickness of approximately 12 μm is sandwiched and fixed between the metal case 41 and the aluminum alloy plate 47. The surface of the polyester film 48 is covered with the aluminum alloy plate 4.
An electrode 49 made of gold foil or the like is deposited on the surface opposite to the surface in contact with the electrode 7 . A protective screen 43 in the figure is fixed to the metal case 41 to prevent the polyester film 48 from being damaged from the outside. On the other hand, a plate spring 46 made of metal is attached to the back surface of the aluminum alloy plate 47, and presses the aluminum alloy plate 47 against the metal case 41. Further, the leaf spring 46 is fixed to the plastic case 42. 44 and 45 are electrode terminals, 44 is constructed integrally with the leaf spring 46, and 45 is constructed integrally with the metal case 41. Therefore, the potential of the electrode terminal 44 is equal to that of the aluminum alloy plate 47 via the plate spring 46, and the potential of the electrode terminal 45 is equal to that of the electrode 49 via the metal case 41.

FIG. 5 is a diagram showing the principle of the electrostatic ultrasonic transducer described in FIG. The mechanical element 51 is a diaphragm 51a
and a fixed plate 51b, for example, a fourth
It has the structure shown in the figure. On the other hand, the electrical element 52 is
In the case of ultrasonic wave transmission, it is composed of a bias voltage 53, a resistor 54, and an oscillation circuit 55. Now, when no signal is generated from the oscillation circuit 55, the diaphragm 51a is pulled by the fixed plate 51b by the bias voltage 53 and is bent. Subsequently, when an AC voltage having a smaller amplitude than the bias voltage 53 is applied to the oscillation circuit 55, the polarity of the voltage across the oscillation circuit 55 changes as follows. That is, when the polarity of the voltage applied to both ends of the oscillation circuit 55 is the same as the bias voltage 53, a potential difference equal to the sum of these voltages is applied to the diaphragm 51a and the fixed plate 51b, so that the flexure of the diaphragm 51a increases. . On the other hand, the polarity of the voltage of the oscillation circuit 55 is set to the bias voltage 5.
In the case opposite to 3, a potential difference equal to the difference between these voltages is applied to the diaphragm 51a and the fixed plate 51b, so that the flexure of the diaphragm 51a becomes small. Therefore,
When the oscillation circuit 55 periodically changes the voltage across the oscillation circuit, the diaphragm 51a vibrates and ultrasonic waves are emitted to the front. Note that the resistor 54 has a function of protecting the circuit so that a large current does not flow through the circuit in the event that discharge or the like occurs between the diaphragm 51a and the fixed plate 51b. Although the case of ultrasonic wave transmission has been described above, in the case of wave reception, 55 in FIG. 5 may be a receiving circuit that performs amplification compensation, etc. At this time, due to the ultrasonic waves that entered from the outside,
The diaphragm 51a vibrates, and the capacitance between the diaphragm 51a and the fixed plate 51b changes. Therefore, an alternating current flows through the receiving circuit 55, and by amplifying and compensating this current, it becomes possible to receive ultrasonic waves.

(Problems to be Solved by the Invention) The conventional electrostatic ultrasonic transducer has been described above using examples. Among these, when machining the hole 101 shown in FIG. 4, the conventional machining method could not avoid slight variations in the size and shape of the hole. This hole 101 is the fifth
This corresponds to the gap between the diaphragm 51a and the fixed plate 51b shown in the figure, and when the dimensions and outer shape vary, the force driving the diaphragm 51a varies,
In the end, there was a drawback that the transmission and reception characteristics of ultrasonic waves were not constant. In addition, the polyester film 48
(Figure 4) The thinner the thickness, the higher the sensitivity. They are the upper electrode 49 and the aluminum alloy plate 4 which is the lower electrode.
This is because the distance of 7 becomes smaller. However, as the polyester film 48 is made thinner, micro holes are generated in the film during manufacturing, so a high bias voltage 53 is required.
(Fig. 5), the electrode 49 and the aluminum alloy plate 4
7, which often caused discharge to occur, deteriorating the characteristics of the device. For this reason,
There was a difficulty in that the thickness of the polyester film 48 was limited and the degree of freedom in design was restricted. Furthermore, as mentioned earlier, the combination of mechanical and electrical elements is inevitable in ultrasonic transducers, and conventional structures can be used to
When trying to realize even higher performance devices,
There has been a tendency for the area occupied by these electrical elements to become larger and larger, and for devices to become larger. In fact, it is known that the wiring connecting the electrodes of arrayed transducers becomes quite large. As described above, the conventional technology has the disadvantage that even if a device with higher performance is manufactured, it is not possible to reduce the size and weight of the device.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above, and to provide an ultrasonic transducer with uniform characteristics, high sensitivity, small size and light weight, and a method for manufacturing the same.

(Means for Solving Problems) According to the present invention, the first electrode is provided on the surface of a semiconductor substrate having a hole in the surface, and the first electrode is made of a conductive thin film. An ultrasonic transducer in which a thin insulating film is provided between one electrode and the second electrode, and the second electrode and the semiconductor substrate are electrically insulated by the thin insulating film. The second electrode is provided in a region including at least a side surface of the hole provided on the surface of the semiconductor substrate, and the first electrode is provided on a semiconductor or glass substrate different from the semiconductor substrate. There is obtained an ultrasonic transducer characterized in that the substrate is formed so as to cover the opening hole, and the substrate and the semiconductor substrate are bonded to each other.

Further, according to the present invention, the first electrode is made of a conductive thin film and the second electrode is provided on the surface of a semiconductor substrate having a hole in the surface, and the first electrode and the second electrode are connected to each other. In an ultrasonic transducer in which an insulating film is provided between the first electrode and the semiconductor substrate, the first electrode is formed to cover an opening provided on a substrate other than the semiconductor substrate, and this substrate and the semiconductor substrate are connected to each other. A plurality of bonded ultrasonic transducers are arranged in an array, and mutually independent electric signals are input to the electrodes on at least one side of the first and second electrodes of each ultrasonic transducer. An ultrasonic transducer is obtained which is characterized in that it can output.

Furthermore, according to the present invention, a second electrode is formed on the surface of a semiconductor substrate having holes on the surface, while a conductive thin film serving as a first electrode is formed on another substrate, and both substrates are bonded. There is obtained a method of manufacturing an ultrasonic transducer, which comprises a step of forming an open hole in the other substrate at a portion facing the hole before or after bonding the substrates.

(Function) The ultrasonic transducer of the present invention is an electrostatic ultrasonic transducer that enables the manufacturing method compatible with IC process technology such as silicon and the integration of peripheral circuits, as shown in Fig. 2. Ultrasonic waves are generated by a metal film (generally a thin conductor), which is an elastic vibrating body, moving up and down according to changes in the potential difference applied to the upper and lower electrodes of an insulating film provided on a semiconductor substrate. is transmitted. On the other hand, when this device is used to receive ultrasonic waves, the above-mentioned metal film vibrates due to the pressure of external ultrasonic waves, and as a result, the electrostatic capacitance between the upper and lower electrodes of the above-mentioned insulating film changes. As a result, it is possible to detect the pressure of external ultrasonic waves as a change in the value of the current flowing through the electric circuit (to which a bias voltage is applied). At this time, in order to increase the sensitivity of the wave transmission and reception characteristics of the transducer, it is necessary to reduce the distance between the upper electrode and the lower electrode provided on the semiconductor substrate. In the present invention, as shown in FIG. 2 as an example, by covering the surface of the lower electrode with an insulating film, good insulation is maintained between the upper electrode and the lower electrode, and a metal film that serves as the upper electrode is provided. By bonding the glass substrate and the semiconductor substrate, it was possible to reduce the distance between them. Furthermore, since the ultrasonic transducer of the present invention uses a semiconductor substrate, (1)
Using semiconductor micro-etching processing technology, it is possible to drill holes on the substrate with high precision, and it is possible to suppress variations in device characteristics caused by the manufacturing process (in the case of arrays, variations between each element).
(2) The oscillator circuit and the receiver circuit can be integrated using semiconductor IC process technology, and it has therefore become possible to manufacture a high-performance ultrasonic transducer in a small size and light weight.

(Example) Hereinafter, an example of the first invention of the present application will be described with reference to the drawings.

1a, b and 2a, b show the components of an embodiment of the present invention, and FIG.
and FIG. 2a, FIG. 1b, and FIG. 2b correspond to a plan view and a sectional view of the same component, respectively.
The transducer of the present invention has the configuration shown in FIG. 2, that is, the metal plate 10 and the lower electrode 6 face each other, and the lead hole and the lead electrode face each other, and the components shown in FIGS. After finally gluing them together, they are loaded into a package cage. The metal film 10 shown in this embodiment is bonded to a glass substrate 20, and transmits and receives ultrasonic waves through the opening hole 22, and at the same time functions as an electrical upper electrode. . Although a thin film of gold, aluminum, or the like can be used as the material for the metal film 10, a thin film of titanium is particularly desirable because of its low specific gravity. This metal film 10 vibrates up and down above a non-penetrating etched hole 12 made in the silicon substrate 1 to transmit and receive ultrasonic waves. The metal film 1
A metal film 10 as an upper electrode and a lower electrode 6 are arranged on both sides of the oxide film 36 provided on the lower surface of the 0. Lead electrode 25
An alternating current voltage is applied to and 26 to vibrate the metal film 10. On the other hand, when receiving waves, the vibration of the metal film 10 generates an alternating current voltage in the lead electrodes 25 and 26, which is utilized. The lead electrodes 25 and 26 are not in contact with the oxide film 36 and are exposed, so they are not in contact with the lead holes 11 and 21, respectively.
It can be connected to an external circuit by soldering or other methods. As shown in FIG. 2, SiO ₂ is formed on one main surface of the silicon substrate 1 between the lower electrode 6 and the metal film 10 serving as the upper electrode.
An oxide film 36 such as the like is provided. This helps maintain electrical insulation between the metal film 10 and the lower electrode 6. Furthermore, the thickness of the oxide film 36 is set to 1 μm.
The spatial distance between the metal film 10 and the lower electrode 6 is also about 1 μm, and conventionally, as shown in FIG. This has the advantage that the distance between the electrodes can be significantly reduced compared to the conventional method (about 12 μm). metal film 10
Since the electrostatic force acting on the electrodes 10 and 6 is approximately inversely proportional to the square of the distance between the two electrodes 10 and 6, the configuration according to the invention allows the distance between the electrodes to be reduced, and as a result, the device The sensitivity of the wave transmission and reception characteristics can be increased. Note that an oxide film 3 is also inserted between the lower electrode 6 and the silicon substrate 1 to prevent current from leaking between the electrode 6 and the substrate 1. The lower electrode 6 is electrically connected to an integrated circuit (not shown) for driving and receiving fabricated on the silicon substrate 1 via aluminum wiring (not shown) also placed on the oxide film 3. Connected. Further, the etching hole 12 is manufactured by applying, for example, silicon anisotropic etching technology in order to finish the etching hole 12 with high accuracy in size and shape. this is,
For example, a plurality of square SiO ₂ film patterns with one side aligned in the <110> direction are formed using photolithography on one side of a silicon substrate 1 whose main surface is oriented in the (100) direction. After that, the sample is immersed in an anisotropic etching solution such as hydrazine. This case has the advantage that silicon etching is automatically stopped when the pyramid-shaped etching hole 12 is formed. Furthermore, as mentioned earlier, in order to create the shape of the etched hole 12 using photolithography technology, it is possible to form a minute shape with high precision, and furthermore, the sample is immersed in a liquid and etched. This method has the advantage that a large amount of samples can be processed at once.

Figures 3a-f illustrate an example of a procedure for manufacturing an ultrasonic transducer having an embodiment of the present invention. Figures a to d show the components of Figure 2b, and Figures e to f illustrate a method of manufacturing the components of Figure 2a, respectively. In the figures, the same reference numerals as in FIGS. 1 and 2, which were previously shown as an embodiment of the present invention, indicate the same components. Figure a is
Oxide film 3 on the front and back sides of silicon substrate 1 with (100) plane
An opening 30 having the same shape as the etching hole 12 shown in FIG. 2 and an opening 31 for the lead hole 11 are formed using photolithography technology. When forming the openings 30 and 31, it is necessary to arrange them so that the sides of the etched holes 12 in FIG. 2 face in the <100> direction. This sample
Silicon is anisotropically etched by immersing it in an aqueous solution such as EDP (ethylenediamine pyrocatechol) or hydrazine (Figure 3b). Aqueous solutions such as EDP and hydrazine have a property that the etching rate for the (100) plane of silicon is significantly higher than that for the (111) plane (anisotropy).
It has Therefore, by immersing the sample shown in FIG. 3a in the aqueous solution, the etching holes 12 and lead holes 11 shown in FIG. 3b can be made. Next, etching hole 12 and lead hole 1
The sample is placed in the oxidation furnace again to form an oxide film 3 on the sample 1, and then an integrated circuit 8 for transmitting and receiving is formed using normal silicon IC process technology (FIG. 3(c)). Subsequently, the oxide film 3 on the integrated circuit 8 is removed. Thereafter, aluminum wiring (not shown) connected to the lower electrode 6 and the integrated circuit 8 is formed by vapor deposition or the like. After that, an oxide film 36 for insulation is formed on the lower electrode 6 and the integrated circuit 8, and the silicon substrate 1 on the side where the lower electrode 6 is provided is then bonded to the glass substrate 20. The oxide film 3 around the area is removed (d in the figure).

On the other hand, in Figure e, an opening 35 is formed using photolithography technology on a glass substrate 20 made of Corning #7740 or the like, which has the same coefficient of thermal expansion as silicon, with protective films 15 and 16 made of Au or the like on the front and back sides. This is what I did. By immersing this sample in an aqueous solution of HF, the opening hole 22 and lead hole 21 shown in FIG. Thereafter, a portion of the protective film 16 is removed using photolithography to expose the periphery of the glass substrate 20. The remaining protective film 16 is then used as the metal film 1 as an upper electrode.
0 (f in the same figure). In other words, the metal film 10 has both the role of a protective film and the role of an upper electrode. The present invention also includes a structure in which the metal film 10 and the lower electrode 6 have a Cr base layer and an Au layer on top in order to improve bonding with the glass substrate 20 and the oxide film 3, respectively.

After this, the two components having the structure of FIGS. 3d and 3f are glued together according to the arrangement shown in FIG. By doing so, the distance between the metal film 10, which is the upper electrode, and the lower electrode 6 can be made smaller than before. After this, the device is mounted in the package. When bonding the two components shown in FIG. 3 d and f, the present invention also includes a method of bonding the silicon substrate 3 and the glass substrate 20 using a technique generally known as electrostatic bonding. . Alternatively, the opening hole 22 may be formed after bonding the two pieces shown in FIG. 3 d and e.

In addition, in order to input and output independent electrical signals for each element constituting the array, the metal film 1 of the upper electrode
0 in common and the lower electrode 6 is insulated for each element, or a structure in which the lower electrode 6 is common and the metal film 10 is insulated for each element, or both the metal film 10 and the lower electrode 6 are insulated for each element. A structure in which each element is insulated can also be easily manufactured using the photolithography technique described above.

FIG. 6, FIG. 7, FIG. 8, and FIG. 9 are plan views and cross-sectional views showing other embodiments of the present invention,
Similar to FIGS. 1 and 2, FIGS. 6a and 7a, 6b and 7b are a plan view and a sectional view of the same components. The same applies to FIGS. 8 and 9. In the figures, the same numbers as in FIGS. 1 and 2 indicate the same parts. The embodiment shown in FIGS. 6 and 7 has a new section 61 in place of the lead holes 21 and 11 shown in the embodiment of FIGS.
and 62 are provided. In other words, a portion of the semiconductor substrate 1 and the glass substrate 20 are cut out, and when they are overlapped, the lead electrodes 25, 2
This is to prevent the other party's board from overlapping 6. Therefore, the structure of this embodiment has the advantage that the lead electrodes 25 and 26 can be directly connected to the external circuit without going through the lead holes 11 and 21, so that the connection can be easily made.

Further, the embodiment shown in FIGS. 8 and 9 is characterized in that a semiconductor substrate 1 made of silicon or the like is used instead of the glass substrate 20 of the embodiment shown in FIGS. 6 and 7. . When a semiconductor substrate 1 made of silicon or the like is used, a new effect is added that it becomes possible to accurately control the dimensions of the opening hole 22 using the anisotropic etching technique described above.

FIGS. 10 and 11 are plan views showing other embodiments of the present invention. In the figures, the same numbers as in FIGS. 1 to 3 indicate the same components. In these examples, the rectangle 70 shown in dashed lines
corresponds to the opening hole 22 shown in FIGS. 1 and 2, and the embodiment of the present invention shows a structure in which a plurality of rectangles 70 are provided on the same lower electrode. Electrodes formed on the upper and lower surfaces of the vibrating body element 70 are connected to a part of the peripheral circuit 8 via aluminum wiring (not shown). When a plurality of the vibrating body elements 70 are arranged in a row as shown in the embodiments of FIGS. 10 and 11, ultrasonic waves can be strongly radiated at a small angle in the front, or ultrasonic waves only at a small angle in the front can be strongly received. This has the effect of reducing distraction from surrounding noise. Furthermore, by using the silicon anisotropic etching technique described above, it is possible to form vibrating body elements 7 with exactly the same shape.
0 can be formed at the same time, so there is no problem in terms of quality and time required for manufacturing. In addition to the embodiment shown here, although not shown, the area of the central vibrating body element 70 is increased, and the area of the vibrating body element 70 is increased toward the periphery.
There is also an embodiment in which the area of 0 is reduced. In this case, the above-described directivity is further improved, and a high-quality device with less noise can be provided.

FIG. 12 is a plan view showing an embodiment of the array according to the second invention of the present application. In the figure, the same numbers as in FIG. 10 indicate the same components. In the embodiment of the present invention, one lower electrode 6 formed in one element 100 of the array is arranged separately from each other between each element, and each is connected to the peripheral circuit 8 via an aluminum wiring. . Therefore, in the ultrasonic transducer having the configuration of this embodiment, it is possible to apply voltages with different intensities and phases to each element 100, and in particular,
By applying voltages with different phases to each element 100, it is possible to change the direction of ultrasonic wave transmission and reception, thus creating a high-performance ultrasonic transducer that performs electrical scanning. It has the characteristic of being able to provide In this example, the electrodes are separated on the lower part of the element 100 for each element, but conversely, the electrode on the lower surface of each element 100 is made common, and the electrode 10 on the upper surface is placed on each element 100 for each element 100. Even if it is separated into two parts, a device with the same effect as above can be realized. Although FIG. 12 shows the ultrasonic transducers arranged in an array of 1 row and 5 columns, there is no need to limit the number of elements 100 in any way. For example, the 11th
In the illustrated embodiment, electrodes on the upper and lower surfaces of the vibrating body element 70 are arranged separately for each vibrating body element 70, and when each electrode is connected to the peripheral circuit 8, electrical scanning is performed in a two-dimensional direction. It is possible to realize a two-dimensional ultrasonic transducer that can perform In addition, in the ultrasonic transducer described in this embodiment, the upper and lower electrodes of each element 100 are
Another major advantage over conventional techniques is that they can be formed simultaneously and easily using IC process technology.

The present invention has been described in detail by giving examples. The configuration of the present invention is applicable regardless of whether the ultrasonic wave used as a signal changes continuously or changes in a pulsed manner with only one to several wavelengths. This also holds true regardless of whether the ultrasonic wave has a single wavelength or multiple wavelengths. Furthermore, in the embodiment of the present invention, air was trapped in the hole under the vibrating body;
In addition to this configuration, there is also a configuration in which an opening is made at the bottom of the hole to allow air to flow. Furthermore, the present invention also includes a configuration in which the influence of the back side of the device is reduced by placing an absorbing material such as a sponge on the outside of the hole, and a configuration in which a horn is placed in front of the vibrating body to increase sensitivity. It will be done.

In addition, in the above embodiment, the sensitivity of ultrasonic wave transmission and reception can be increased by increasing the area of the vibrating body or decreasing the thickness of the oxide film between the metal film and the lower electrode. I can do it. However, in this case, changes in the frequency characteristics of the device occur at the same time, so when designing an ultrasonic sensor, take the above effects into account and optimize the sensitivity, frequency characteristics, electroacoustic conversion efficiency, etc. The dimensions of the vibrator must be determined so that

(Effects of the Invention) As explained above, according to the present invention, it has become possible to provide a highly sensitive, compact and lightweight integrated ultrasonic transducer with little variation in characteristics. As a result, it has become possible to utilize high-performance ultrasonic transducers for detecting proximity sense and the like in fields such as industrial robots. Further, since the ultrasonic transducer of the present invention can be manufactured in large quantities using a manufacturing method that is compatible with conventional semiconductor IC manufacturing process technology, manufacturing costs can be reduced. These effects are remarkable and the present invention is effective.

[Brief explanation of drawings]

1 and 2 are a plan view and a sectional view of an embodiment of the present invention, respectively, FIGS. 3 a to 3 are conceptual diagrams showing an embodiment of a method for manufacturing the embodiment of the present invention, and FIG. 4 5 is a sectional view of a conventional ultrasonic transducer, FIG. 5 is a principle diagram of a conventional electrostatic transducer, and FIGS. 6 to 9 are diagrams showing other embodiments of the present invention. Figures 6 and 8 are plan views, Figure 7
9 and 9 are sectional views, and FIGS. 10 and 11 are plan views showing other embodiments of the present invention. FIG. 12 is a plan view showing an embodiment of the second invention of the present application. 1... Silicon substrate, 3, 36... Oxide film, 6
... lower electrode, 8 ... integrated circuit, 10 ... metal film, 11, 21 ... lead hole, 15, 16 ... protective film, 12 ... etching hole, 25, 26 ... lead electrode, 20 ... Glass substrate, 22... Opening hole, 30, 31, 35... Opening, 41... Metal case, 42... Plastic case, 43... Protective screen, 44, 45... Electrode terminal, 46...
... Leaf spring, 47 ... Aluminum alloy plate, 48 ... Polyester film, 49 ... Upper electrode, 51 ... Mechanical element, 51a ... Vibration plate, 51b ... Fixing plate, 52 ... Electrical element , 53... Bias voltage, 54... Resistance, 55... Transmission and reception circuit, 61, 62... Intercept, 70... Vibrating body element.

Claims (1)

[Claims] 1. A first electrode made of a conductive thin film and a second electrode provided on the surface of a semiconductor substrate having a hole on the surface, the first electrode and the second electrode an ultrasonic transducer in which a thin insulating film is provided between the second electrode and the semiconductor substrate, and the second electrode and the semiconductor substrate are electrically insulated by the thin insulating film; The second electrode is provided in a region including at least a side surface of the provided hole, and the first electrode is formed to cover the open hole provided on a semiconductor or glass substrate different from the semiconductor substrate. An ultrasonic transducer characterized in that the substrate and the semiconductor substrate are bonded to each other. 2.Equipped with a first electrode made of a conductive thin film and a second electrode provided on the surface of a semiconductor substrate having a hole on the surface, and an insulating film between the first electrode and the second electrode. In an ultrasonic transducer provided with A plurality of sonic transducers are arranged in an array so that mutually independent electrical signals can be input and output to the electrodes on at least one side of the first and second electrodes of each ultrasonic transducer. An ultrasonic transducer characterized by: 3 Forming a second electrode on the surface of a semiconductor substrate having holes on the surface, forming a conductive thin film to become the first electrode on another substrate, and bonding both substrates, A method for manufacturing an ultrasonic transducer, characterized in that an opening hole is formed in the other substrate at a portion facing the hole before or after bonding.