Ultrasonic transducer, ultrasonic probe, and ultrasonic examination device

An ultrasonic transducer includes a substrate, a supporting film, and a piezoelectric element. The substrate includes an opening. The supporting film is configured on the substrate to cover the opening. The piezoelectric element is configured at a part of the supporting film. The part overlaps with the opening in a planar view in a thickness direction of the substrate. A thickness of the part of at a center of gravity in the planar view is smaller than a thickness of an outer edge portion of the part. The outer edge portion is closer to the substrate than the center to the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2012-115320 filed on May 21, 2012. The entire disclosure of Japanese Patent Application No. 2012-115320 is hereby incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to an ultrasonic transducer, an ultrasonic probe, and an ultrasonic examination device.

2. Background Technology

An ultrasonic transducer in which a plurality of ultrasonic elements are arranged in a matrix pattern has been known. This ultrasonic transducer includes a substrate that has a plurality of openings, a supporting film that is provided on the substrate so as to cover each of the openings, and a piezoelectric element that is provided on a part of the supporting film corresponding to each of the openings. A diaphragm is constructed by the part of the supporting film corresponding to the opening which is a part coinciding with the opening of the supporting film in a planar view. The ultrasonic element is constructed by the diaphragm and the piezoelectric element provided on the diaphragm. The thickness of the supporting film of the ultrasonic transducer, that is, the thickness of the part of the supporting film corresponding to the opening which coincides with the opening of the supporting film in a planar view is set to be uniform (for example, see Patent Document 1). In the ultrasonic transducer, the diaphragm is greatly deflected when ultrasonic waves are transmitted, and the diaphragm is slightly deflected when ultrasonic waves are received.

The well-known ultrasonic transducer, however, has a problem that the diaphragm is greatly deflected especially when ultrasonic waves are transmitted, which causes the stress to concentrate in the vicinity of an outer edge portion of the diaphragm and causes damage such as cracking or chipping. On the other hand, if the thickness of the diaphragm is increased to improve the strength of the diaphragm, the diaphragm will become hard to deflect. Then, especially when ultrasonic waves are received with the ultrasonic element, the deflection amount of the diaphragm will become smaller, which makes the stress generated in the piezoelectric element very small. Consequently, the level of a reception signal output from the piezoelectric element will be deteriorated. In other words, the characteristics of transmission and reception of ultrasonic waves, in particular, the sensitivity in reception will be deteriorated.

Japanese Laid-open Patent Publication No. 2000-23296 (Patent Document 1) is an example of the related art.

SUMMARY

Problems to be Solved by the Invention

The advantage of the invention is to provide an ultrasonic transducer, an ultrasonic probe, and an ultrasonic examination device which have good characteristics of transmission and reception of ultrasonic waves, and can prevent the part of the supporting film corresponding to the opening from being damaged.

Means Used to Solve the Above-Mentioned Problems

This advantage is achieved by the invention described below. According to one aspect of the invention, an ultrasonic transducer includes a substrate, a supporting film, and a piezoelectric element. The substrate includes an opening. The supporting film is configured on the substrate to cover the opening. The piezoelectric element is configured at a part (an opening-overlapping part) of the supporting film. The part overlaps with the opening in a planar view in a thickness direction of the substrate. A thickness of the part at a center of gravity in the planar view is smaller than a thickness of an outer edge portion of the part. The outer edge portion is closer to the substrate than the center to the substrate.

According to another aspect of the invention, an ultrasonic transducer includes a substrate, a support film, and a piezoelectric element. The substrate includes an opening. The supporting film is configured on the substrate to cover the opening. The piezoelectric element is configured at a part of the supporting film. The part overlaps with the opening in a planar view in a thickness direction of the substrate. A surface of the part on an opening side having a curved concave surface.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the ultrasonic transducer, the ultrasonic probe, and the ultrasonic examination device of the invention will be explained in detail based on a preferred embodiment shown in the attached drawings.

Embodiment of Ultrasonic Transducer and Ultrasonic Probe

FIG. 1is a perspective view showing an embodiment of an ultrasonic probe according to the invention.FIG. 2is a plan view showing an ultrasonic transducer of the ultrasonic probe shown inFIG. 1.FIG. 3is a plan view enlarging a part of the ultrasonic transducer shown inFIG. 2.FIG. 4is a sectional view along line A-A ofFIG. 3.FIG. 5is a sectional view enlarging a part of the ultrasonic transducer shown inFIG. 4.FIG. 6-FIG.8are sectional views explaining a method for manufacturing the ultrasonic transducer of the ultrasonic probe shown inFIG. 1. Hereinafter, explanations will be made by describing the upper side inFIG. 3-FIG.7as “upper”, the lower side as “lower”, the right side as “right”, and the left side as “left”.

InFIG. 2, illustrations of parts and the like of an acoustic matching section, an upper electrode, a lower electrode, a conducting wire for an upper electrode, and a conducting wire for a lower electrode are omitted, and the ultrasonic transducer is schematically illustrated. InFIG. 3, an illustration of the acoustic matching section is omitted. Further, inFIG. 6-FIG.8, a piezoelectric element is schematically illustrated. Also, as shown in each drawing, an X axis and a Y axis orthogonal to each other are assumed. An X axis direction corresponds to an azimuth direction, and a Y axis direction corresponds to a slice direction.

As shown inFIG. 1, an ultrasonic probe10has a case200, and an ultrasonic transducer1that is accommodated in the case200. The ultrasonic transducer1is disposed in a tip end portion of the case200. The ultrasonic probe10can be used as an ultrasonic probe for various kinds of ultrasonic examination devices such as an ultrasonic examination device100described below. In the present embodiment, a surface of the ultrasonic transducer1, that is, a surface of an acoustic matching section6described below is exposed outside. The acoustic matching section6serves as a protective layer of the ultrasonic probe10and the ultrasonic transducer1. Although the constituent material of the acoustic matching section6is not limited to a specific one, a material that is substantially similar to a living body with respect to the acoustic impedance, such as silicone rubber, is used. Here, it can be configured such that the surface of the acoustic matching section6is not exposed outside.

In conducting a test, the ultrasonic probe10is used by applying the surface of the acoustic matching section6to a living body as a test target. In such a case, when ultrasonic waves are sent out from the ultrasonic transducer1toward the acoustic matching section6, the ultrasonic waves pass through the acoustic matching section6and propagate through the living body. Then, the ultrasonic waves reflected on a predetermined part inside the living body pass through the acoustic matching section6and are input to the ultrasonic transducer1. Also, the ultrasonic probe10is electrically connected with a device main body300(seeFIG. 9), described below, of the ultrasonic examination device100through a cable210.

As shown inFIG. 2-FIG.5, the ultrasonic transducer1has a substrate2, a plurality of (twelve in the configuration shown in the drawing) ultrasonic elements (ultrasonic vibrators)8that are provided on the substrate2so as to transmit and receive ultrasonic waves, and the acoustic matching section6that is provided on the substrate2on the side of the ultrasonic elements8so as to cover each of the ultrasonic elements8. Although the shape of the substrate2is not limited to a specific one, it forms a quadrangle in a planar view in the configuration shown in the drawing. Also, as another shape of the substrate2in a planar view, another polygon such as a pentagon or a hexagon, a circle, or an ellipse can be listed, for example. Although the constituent material of the substrate2is not limited to a specific one, a material for forming a semiconductor such as silicon (Si) is used, for example. Consequently, it can be processed easily by etching or the like.

The ultrasonic element8is constructed of a diaphragm51and a piezoelectric body (piezoelectric element)7, and each of the ultrasonic elements8is arranged on the substrate2in a matrix pattern. In other words, the plurality of (four in the configuration shown in the drawing) ultrasonic elements8are arranged in parallel along the X axis direction, and the plurality of (three in the configuration shown in the drawing) ultrasonic elements8are arranged in parallel along the Y axis direction. Although the shape of the piezoelectric body7is not limited to a specific one, it forms a circle in a planar view in the configuration shown in the drawing. Also, as another shape of the piezoelectric body7in a planar view, a quadrangle (square, rectangle), a polygon such as a pentagon or a hexagon, or an ellipse can be listed, for example. Incidentally, the piezoelectric body7and the wiring thereof will be described below.

An opening21for forming the diaphragm51of the ultrasonic element8is formed in a part of the substrate2corresponding to each of the ultrasonic elements8. Although the shape of the opening21is not limited to a specific one, it forms a circle in a planar view in the configuration shown in the drawing. Also, as another shape of the opening21in a planar view, a quadrangle (square, rectangle), a polygon such as a pentagon or a hexagon, or an ellipse can be listed, for example.

A supporting film5is formed on the substrate2, and each of the openings21is covered with the supporting film5. The diaphragm51is constructed by a part of the supporting film5corresponding to the opening which is a part (region) covering the opening21, that is, a part coinciding with (part overlapping with) the opening21of the supporting film5in a planar view. The piezoelectric body7is provided on the diaphragm51.

Although the constituent material of the supporting film5is not limited to a specific one, the supporting film5is constructed by a layered body (two-layer structure) of an SiO2film and a ZrO2layer, or an SiO2film, for example. In a case where the substrate2is an Si substrate, the SiO2layer can be formed by conducting a thermal oxidation treatment to the surface of the substrate2. The ZrO2layer can be formed on the SiO2layer, for example, by a technique such as sputtering. Here, the ZrO2layer is a layer for preventing Pb that constitutes PZT from diffusing into the SiO2layer when PZT is used as a piezoelectric film72of the piezoelectric body7, for example. The piezoelectric film72of the piezoelectric body7will be described below. The ZrO2layer also has an effect such as an effect of improving deflection efficiency with respect to deformation of the piezoelectric film72.

As shown inFIG. 5, the piezoelectric body7has a lower electrode71formed on the diaphragm51(the supporting film5), the piezoelectric film72formed on the lower electrode71, and an upper electrode73formed on the piezoelectric film72. Also, a conducting wire for a lower electrode71ais connected with the lower electrode71, and the conducting wire for a lower electrode71aextends along the Y axis direction on the supporting film5as shown inFIG. 3, for example. The conducting wire for a lower electrode71aserves as a common conducting wire of each ultrasonic element8arranged in the Y axis direction. More specifically, as shown inFIG. 3andFIG. 4, the conducting wire for a lower electrode71ais connected with the lower electrodes71of two adjacent ultrasonic elements8arranged in the Y axis direction. With this configuration, the assembly of the ultrasonic elements8arranged in the Y axis direction can be driven independently.

A conducting wire for an upper electrode73ais connected with the upper electrode73, and the conducting wire for an upper electrode73aextends along the X axis direction on the supporting film5as shown inFIG. 3, for example. The conducting wire for an upper electrode73aserves as a common conducting wire of each ultrasonic element8arranged in the X axis direction. More specifically, as shown inFIG. 3, the conducting wire for an upper electrode73ais connected with the upper electrodes73of two adjacent ultrasonic elements8arranged in the X axis direction, and is connected to the GND, for example, at the end portion thereof. In this manner, the upper electrode73of each ultrasonic element8is earthed. Alternatively, contrary to the above, the conducting wire for a lower electrode71acan be connected to the GND.

The constituent materials of the lower electrode71, the upper electrode73, the conducting wire for a lower electrode71a, and the conducting wire for an upper electrode73aare not limited to specific ones as long as they have conductive properties, respectively. For example, various kinds of metal materials can be used. Also, the lower electrode71, the upper electrode73, the conducting wire for a lower electrode71a, and the conducting wire for an upper electrode73acan be single layers, respectively, or can be layered bodies in which a plurality of layers are laminated, respectively. As specific examples, for example, a Ti/Ir/Pt/Ti layered film can be used as the lower electrode71and the conducting wire for a lower electrode71a, respectively, and an Ir film can be used as the upper electrode73and the conducting wire for an upper electrode73a, respectively.

The piezoelectric film72is made by forming PZT (lead zirconate titanate) into a film shape, for example. In the present embodiment, PZT is used as the piezoelectric film72. However, any material can be used as long as it is a material that can contract (expand or contract) in an in-plane direction by applying a voltage thereto. For example, lead titanate (PbTiO3), lead zirconate (PbZrO3), lead lanthanum titanate ((Pb, La) TiO3), or the like can be used as well as PZT.

In the ultrasonic element8, for example, when a voltage is applied between the lower electrode71and the upper electrode73by the device main body300(seeFIG. 9) through the cable210, the piezoelectric film72expands or contracts in the in-plane direction. In this instance, a surface of the piezoelectric film72is attached to the supporting film5through the lower electrode71, and the upper electrode73is formed on the other surface thereof. Here, since any other layer is not formed on the upper electrode73, the supporting film5side of the piezoelectric film72does not easily expand or contract, while the upper electrode73side of the piezoelectric film72easily expands or contracts. Therefore, when a voltage is applied to the piezoelectric film72, deflection that causes projection occurs on the opening21side, which results in deflection of the first diaphragm51. Consequently, when an alternating voltage is applied to the piezoelectric film72, the diaphragm51vibrates with respect to the film thickness direction, and this vibration of the diaphragm51transmits (sends) ultrasonic waves. In transmission of such ultrasonic waves, an alternating voltage, whose frequency is equal to the resonance frequency of the ultrasonic element8, or is close to the resonance frequency and is smaller than the resonance frequency, is applied to the piezoelectric film72, and the ultrasonic element8is resonantly driven. With this, the diaphragm51is greatly deflected, so that ultrasonic waves can be transmitted with high output.

In receiving ultrasonic waves with the ultrasonic element8, when ultrasonic waves are input to the diaphragm51, the diaphragm51vibrates with respect to the film thickness direction. In the ultrasonic element8, this vibration of the diaphragm51causes a potential difference between the surface of the piezoelectric film72on the lower electrode71side and the surface of the piezoelectric film72on the upper electrode73, and a reception signal (detection signal) (current) is output from the upper electrode73and the lower electrode71in response to the displacement amount of the piezoelectric film72. This signal is transmitted to the device main body300(seeFIG. 9) through the cable210, and predetermined signal processing or the like is conducted based on the signal. Then, in the device main body300, an ultrasonic image (electronic image) is formed and displayed. In the ultrasonic probe10, planar waves of ultrasonic waves can be transmitted in a desired direction by delaying and differentiating the timing of transmission of ultrasonic waves from each ultrasonic element8arranged in parallel along the X axis direction.

As shown inFIG. 5, in the ultrasonic transducer1, a thickness of the part of the supporting film corresponding to the opening which coincides with the opening21of the supporting film5in a planar view, that is, a thickness of a central portion of the diaphragm51is smaller than a thickness of an outer edge portion of the diaphragm51. Here, the outer edge portion of the part of the supporting film corresponding to the opening is an annular region X having a predetermined width from an outer circumferential end of the part of the supporting film corresponding to the opening toward the inside of the part of the supporting film corresponding to the opening, that is, toward the center of gravity in a planar view. The central portion of the part of the supporting film corresponding to the opening is a region Y having a predetermined area that includes the position of the center of gravity of the part of the supporting film corresponding to the opening except the region X (outer edge portion).

In the present embodiment, the diaphragm51has a uniform thickness portion511whose thickness is uniform in the outer edge portion thereof. The uniform thickness portion511is provided along the circumference of the diaphragm51. In other words, the uniform thickness portion511has an annular shape in a planar view. The diaphragm51also has a gradually increasing thickness portion512whose thickness gradually increases from the center of gravity (the central portion) of the diaphragm51toward the outer edge portion thereof. A concave portion52having a curved surface curved in a bowl shape (curved concave surface) is formed in a lower surface of the diaphragm51. With this configuration, the strength of the outer edge portion of the diaphragm51, that is, the strength of the uniform thickness portion511is increased, and the gradually increasing thickness portion512of the diaphragm51, in particular, the central portion side of the gradually increasing thickness portion512becomes easy to deflect. Consequently, damage such as cracking or chipping of the diaphragm51can be prevented from occurring while having good characteristics of transmission and reception of ultrasonic waves.

More specifically, even if the diaphragm51is greatly deflected in transmission and reception of ultrasonic waves, especially, in transmission of ultrasonic waves due to the resonant drive of the ultrasonic element8, damage such as cracking or chipping can be prevented from occurring in the vicinity of the outer edge portion of the diaphragm51. Further, since the central portion of the diaphragm51becomes easy to deflect locally, the deflection amount of the piezoelectric body7can be increased in transmission and reception of ultrasonic waves, especially, in reception of ultrasonic waves in which the deflection amount of the diaphragm51is small. Consequently, large stress is generated in the piezoelectric body7, and the level of a reception signal output from the piezoelectric body7can be improved. In other words, the sensitivity in reception of ultrasonic waves can be improved. Further, the piezoelectric body7is provided closer to the central portion compared to the uniform thickness portion511on the diaphragm51. Consequently, the sensitivity in reception of ultrasonic waves can be improved more securely.

Here, the size of the diaphragm51(the supporting film5) is not limited to a specific one, and is determined based on various conditions. However, when the thickness of the uniform thickness portion511(outer edge) of the diaphragm51is D1 and the thickness of the position of the center of gravity (center) of the diaphragm51in a planar view is D2, D2/D1 is preferably within the range of 0.1 to 0.9. With this configuration, damage such as cracking or chipping can be prevented from occurring in the vicinity of the outer edge portion of the diaphragm51more securely, and the sensitivity in reception of ultrasonic waves can be improved more securely.

Preferably, the thickness D1 of the uniform thickness portion511(outer edge) of the diaphragm51is within the range of 0.4 μm to 1.5 μm. With this configuration, damage such as cracking or chipping can be prevented from occurring in the vicinity of the outer edge portion of the diaphragm51more securely. Preferably, the thickness D2 of the position of the center of gravity of the diaphragm51is within the range of 0.15 μm to 1.35 μm. With this configuration, the sensitivity in reception of ultrasonic waves can be improved more securely.

Further, when the area of the uniform thickness portion511of the diaphragm51is S1 and the area of the gradually increasing thickness portion512is S2 in a planar view, S1/S2 is preferably within the range of 0.02 to 0.25. With this configuration, damage such as cracking or chipping can be prevented from occurring in the vicinity of the outer edge portion of the diaphragm51more securely, and the sensitivity in reception of ultrasonic waves can be improved more securely. In the present embodiment, the diaphragm51has the uniform thickness portion511. However, the uniform thickness portion511can be omitted.

Next, explanations will be made on an example of a method for processing the substrate2and the supporting film5in a method for manufacturing the ultrasonic transducer1, that is, a method for forming each opening21of the substrate2and each concave portion52of the supporting film5(the diaphragm51). Here, as one example, a case where the substrate2is composed of Si and the supporting film5is composed of SiO2will be described. First, as shown inFIG. 6(a), a structure including the substrate2with unformed opening21, the supporting film5with unformed concave portion52above the substrate2, and the piezoelectric body7above the supporting film5is manufactured. As a method for manufacturing this structure, since a conventionally known method or the like can be used, the explanations thereof will be omitted.

Next, each opening21is formed in the substrate2and each concave portion52is formed in the supporting film5by conducting processing to parts of the substrate2and the supporting film5corresponding to the piezoelectric body7, respectively, so as to form each diaphragm51. Since a method for forming each opening21is similar and a method for forming each concave portion52is similar, a method for forming one of the openings21and a method for forming one of the concave portions52will be explained hereinafter as representatives.

First, as shown inFIG. 6(b), a resist film91is formed on the upper surface of the substrate2except the part in which the opening21of the substrate2is formed. Next, as shown inFIGS. 6(c)-6(d),FIGS. 7(a)-7(c), andFIG. 8, the opening21is formed by the Bosch process (cycle etching) in which an etching process and formation of a protective film92are repeated alternately a plurality of times with respect to the substrate2using the resist film91as a mask. For this Bosch process, an inductively coupled (ICP) reactive ion etching apparatus is used. More specifically, inductively coupled reactive ion etching is conducted to the substrate2using an inductively coupled reactive ion etching apparatus in the etching process, and subsequently, the protective film92is formed in the substrate2using the inductively coupled reactive ion etching apparatus. InFIG. 6andFIG. 7, a case where the etching process is conducted three times and the formation of the protective film92is conducted twice is illustrated. However, the numbers of times of the etching process and the formation of the protective film92are not limited to these numbers, respectively, and the actual numbers of times are larger than these numbers.

Here, in the etching process, mixed gas of SF6and O2is used as processing gas, for example. The flow rate of the processing gas in the etching process is not limited to a specific one, and is set as appropriate based on various conditions. However, for example, it is preferable to set within the range of 100 sccm to 1000 sccm, and it is more preferable to set within the range of 200 sccm to 700 sccm.

The processing time of the etching process is not limited to specific one, and is set as appropriate based on various conditions. However, for example, it is preferable to set within the range of 1 second to 20 seconds. The coil power of the inductively coupled plasma in the etching process is not limited to specific one, and is set as appropriate based on various conditions. However, for example, it is preferable to set within the range of 300 W to 3000 W.

Also, in forming the protective film92, mixed gas of C4F8and O2is used as processing gas, for example. The flow rate of the processing gas in forming the protective film92is not limited to a specific one, and is set as appropriate based on various conditions. However, for example, it is preferable to set within the range of 50 sccm to 600 sccm.

The time for forming the protective film92is not limited to specific one, and is set as appropriate based on various conditions. However, for example, it is preferable to set within the range of 0.5 second to 10 seconds. The coil power of the inductively coupled plasma in forming the protective film92is not limited to specific one, and is set as appropriate based on various conditions. However, for example, it is preferable to set within the range of 100 W to 2500 W. Incidentally, by composing the substrate2of Si, the opening21can be formed so as to be perpendicular to the upper surface and the lower surface of the substrate2.

Next, as shown inFIG. 8, the concave portion52is formed by the Bosch process in which an etching process and formation of the protective film92are repeated alternately a plurality of times with respect to the supporting film5using the resist film91as a mask. For this Bosch process, an inductively coupled (ICP) reactive ion etching apparatus is used. More specifically, inductively coupled reactive ion etching is conducted to the supporting film5using an inductively coupled reactive ion etching apparatus in the etching process, and subsequently, a protective film which is not shown in the drawing is formed in the supporting film5using the inductively coupled reactive ion etching apparatus.

Here, in the etching process, mixed gas of SF6and O2is used as processing gas, for example. The flow rate of the processing gas in the etching process is not limited to a specific one, and is set as appropriate based on various conditions. However, for example, it is preferable to set within the range of 100 sccm to 1000 sccm, and it is more preferable to set within the range of 200 sccm to 700 sccm.

The processing time of the etching process is not limited to specific one, and is set as appropriate based on various conditions. However, for example, it is preferable to set within the range of 1 second to 20 seconds. The coil power of the inductively coupled plasma in the etching process is not limited to specific one, and is set as appropriate based on various conditions. However, for example, it is preferable to set within the range of 300 W to 3000 W.

Also, in forming the above-described protective film, mixed gas of C4F8and O2is used as processing gas, for example. The flow rate of the processing gas in forming the protective film is not limited to a specific one, and is set as appropriate based on various conditions. However, for example, it is preferable to set within the range of 50 sccm to 600 sccm.

The time for forming the protective film is not limited to specific one, and is set as appropriate based on various conditions. However, for example, it is preferable to set within the range of 0.5 second to 10 seconds. The coil power of the inductively coupled plasma in forming the protective film is not limited to specific one, and is set as appropriate based on various conditions. However, for example, it is preferable to set within the range of 100 W to 2500 W. Incidentally, by composing the supporting film5of SiO2, the concave portion52having a curved surface curved in a bowl shape is formed.

Next, the resist film91is removed. As described above, the ultrasonic transducer1is manufactured. Incidentally, the shape of the concave portion52such as the degree of curving of the concave portion52can be set as appropriate by adjusting the selected ratio of Si/SiO2or the like. Further, formation or non-formation of the uniform thickness portion511, and the size of the uniform thickness portion511and the like in a case of forming the uniform thickness portion511can be set as appropriate by adjusting the flow rate of the processing gas in the etching process, the processing time of the etching process, the coil power of the inductively coupled plasma in the etching process, the flow rate of the processing gas in forming the protective film, the time for forming the protective film, the coil power of the inductively coupled plasma in forming the protective film, or the like. The ultrasonic probe10described above can be applied to an ultrasonic examination device in a preferred manner.

Next, an example of the conditions of each process in a case where the uniform thickness portion511is formed in the supporting film5, and an example of the conditions of each process in a case where the uniform thickness portion511is not formed in the supporting film5will be described. These conditions are ones in a case where the thickness of the substrate2is 200 μm, Si is used as the constituent material of the substrate2, and SiO2is used as the constituent material of the supporting film5, respectively.

(1) The Case where the Uniform Thickness Portion511is Formed in the Supporting Film5

First, in the etching process to the substrate2, mixed gas of SF6and O2is used as the processing gas, the flow rate of the processing gas is 450 sccm, and the coil power is 2500 W. Also, in forming the protective film92in the substrate2, mixed gas of C4F8and O2is used as the processing gas, the flow rate of the processing gas is 150 sccm, and the coil power is 1500 W. The processing time of the etching process is 10 seconds, and the time for forming the protective film92is 6 seconds. The etching process and the formation of the protective film92are conducted alternately for 36 minutes in total.

Next, in the etching process to the supporting film5, mixed gas of SF6and O2is used as the processing gas, the flow rate of the processing gas is 450 sccm, and the coil power is 2500 W. Also, in forming the protective film92in the supporting film5, mixed gas of C4F8and O2is used as the processing gas, the flow rate of the processing gas is 150 sccm, and the coil power is 1500 W. The processing time of the etching process is 10 seconds, and the time for forming the protective film92is 6 seconds. The etching process and the formation of the protective film92are conducted alternately for 14 minutes 24 seconds in total. With that, the process is finished.

(2) The Case where the Uniform Thickness Portion511is not Formed in the Supporting Film5

First, in the etching process to the substrate2, mixed gas of SF6and O2is used as the processing gas, the flow rate of the processing gas is 450 sccm, and the coil power is 2500 W. Also, in forming the protective film92in the substrate2, mixed gas of C4F8and O2is used as the processing gas, the flow rate of the processing gas is 150 sccm, and the coil power is 1500 W. The processing time of the etching process is 10 seconds, and the time for forming the protective film92is 6 seconds. The etching process and the formation of the protective film92are conducted alternately for 36 minutes in total.

Next, in the etching process to the supporting film5, mixed gas of SF6and O2is used as the processing gas, the flow rate of the processing gas is 450 sccm, and the coil power is 2000 W. Also, in forming the protective film92in the supporting film5, mixed gas of C4F8and O2is used as the processing gas, the flow rate of the processing gas is 150 sccm, and the coil power is 1500 W. The processing time of the etching process is 5 seconds, and the time for forming the protective film92is 3 seconds. The etching process and the formation of the protective film92are conducted alternately for 20 minutes in total. With that, the process is finished.

Embodiment of Ultrasonic Examination Device

FIG. 9is a block diagram showing the embodiment of the ultrasonic examination device according to the invention. As shown inFIG. 9, the diagnostic device100has the above-described ultrasonic probe10, and the device main body300which is electrically connected with the ultrasonic probe10through the cable210.

The device main body300has a control section (control means)310, a drive signal generating section320, a detection signal processing section330, an image signal processing section340, and an image display section (display means)350. The signal processing section is constructed of the detection signal processing section330and the image signal processing section340. The control section310is constructed of a microcomputer and the like, for example, and controls the entire device main body300such as the drive signal generating section320and the image signal processing section340. The image display section350is constructed of a display device such as a CRT or an LCD, for example.

Next, the operation of the diagnostic device100will be explained. In conducting a test, the surface of the acoustic matching section6of the ultrasonic probe10is applied to a living body as a test target, and the diagnostic device100is activated. First, when the control section310outputs a transmission order to the drive signal generating section320, the drive signal generating section320transmits a drive signal for driving each ultrasonic element8to the ultrasonic element8at a predetermined timing. In this manner, each of the ultrasonic elements8is driven at a predetermined timing. Then, ultrasonic waves are transmitted from the ultrasonic transducer1of the ultrasonic probe10.

The transmitted ultrasonic waves propagate through a living body, and the ultrasonic waves reflected on a predetermined part of the living body are input to the ultrasonic transducer1of the ultrasonic probe10. Then, a detection signal corresponding to the input ultrasonic waves are output from the ultrasonic transducer1. The detection signal is transmitted to the detection signal processing section330of the device main body300through the cable210. The detection signal undergoes predetermined signal processing in the detection signal processing section330, and is converted into a digital signal by an A/D converter included in the detection signal processing section330. The A/D converter is not shown in the drawing.

The digital signal output from the detection signal processing section330is input to the image signal processing section340, and is sequentially stored in a primary storing section included in the image signal processing section340as areal data in synchronization with a frame timing signal. The primary storing section is not shown in the drawing. The image signal processing section340reconstructs two-dimensional or three-dimensional image data based on each areal data, and also conducts image processing such as interpolation, response emphasis processing, or tone processing to the image data. The image data, to which image processing has been conducted, is stored in a secondary storing section included in the image signal processing section340. The secondary storing section is not shown in the drawing. The image data, to which image processing has been conducted, is then read out from the secondary storing section of the image signal processing section340and is input to the image display section350. The image display section350displays an image based on the image data. A medical service worker such as a doctor conducts diagnosis or the like by observing an image displayed on the image display section350.

The invention is not limited to the ultrasonic transducer, the ultrasonic probe, and the ultrasonic examination device of the invention explained in the above based on the embodiment shown in the drawing. The configuration of each section can be replaced with any configuration that has a similar function. Also, another optional element can be added to the invention.

In the above-described embodiment, the number of the ultrasonic element, that is, the numbers of the parts of the piezoelectric element and the supporting film corresponding to the opening are plural, respectively. However, the invention is not limited to this, and they can be single.

GENERAL INTERPRETATION OF TERMS