JPWO2007020925A1 - Electroacoustic transducer - Google Patents

Abstract

A diaphragm (2) is supported on a substrate (1) having an opening. One side of the diaphragm (2) faces the opening. The thin film coil (3) is a spiral coil whose planar shape circulates around one axis. A yoke (5) is formed on the cover (4), and a permanent magnet (6) is provided at the center of the yoke (5). A gap (7) is formed between the diaphragm (2) and the yoke (5). By forming the thin film coil (3) on the diaphragm (2), the thickness can be reduced. Since the gap (7) between the permanent magnet (6) and the thin film coil (3) is small, a sufficient driving force of the diaphragm (2) can be obtained even with a small magnetic force. The electroacoustic transducer can be reduced in thickness, reduced in size, and consumes less power.

Description

  The present invention relates to an electroacoustic transducer having a thin film coil, a permanent magnet, and a diaphragm, and more particularly to an electroacoustic transducer formed by using MEMS (Micro Electro Mechanical Systems) technology.

  FIG. 23 shows a dynamic speaker that is an example of a conventional electroacoustic transducer. As shown in FIG. 23, a concentric cylindrical coil 3 connected and fixed to the diaphragm 2 is inserted into a magnetic field formed by a permanent magnet 6 and yokes 51 and 52. The coil 3 is disposed so as to protrude from the diaphragm 2 (see Patent Document 1).

  In recent years, with the development of MEMS technology, silicon-based piezo-type and capacitor-type compact electroacoustic transducers have also been proposed. A piezo-type small electroacoustic transducer is disclosed in Non-Patent Document 1, for example. A capacitor-type small electroacoustic transducer is disclosed in Patent Document 2.

  A conventional dynamic speaker or microphone as described in Patent Document 1 has a structure in which a cylindrical coil protrudes from a diaphragm. With such a structure, there was a limit to thinning. In addition, the actuator section in the speaker and the sensor section in the microphone are usually separated from the amplifier section. Therefore, there was a problem of picking up noise on the connection cable.

  On the other hand, the piezoelectric type and capacitor type electroacoustic transducers utilizing the MEMS technology as described in Patent Document 2 and Non-Patent Document 1 can be miniaturized, but the piezoelectric type can generate large sound waves. There has been a problem that the voltage applied to the element increases. Further, the capacitor type has a problem that a large bias voltage is required. Furthermore, although the electroacoustic transducer described in Patent Document 3 is intended to achieve a reduction in thickness, it is originally a magnetic buzzer, and its structure is such that the sounding portion is not open to the outside, and a speaker or It is not suitable for use as a microphone.

  In view of the above problems, an object of the present invention is to provide an electroacoustic transducer that can be thinned, is small, consumes less power, and can be applied as a high-quality speaker or microphone.

JP 2003-169390 A Special table 2003-509984 gazette JP 2003-305409 A S. H. Yi and E. S. Kim, "Piezoelectric Micro speaker with Compressive Nitride Diaphragm" International MEMS Conference. January 20-24. 2002. Las Vegas

  To achieve the above object, according to one aspect of the present invention, a substrate having an opening, a diaphragm supported on the substrate so that one surface faces the opening, and the other surface of the diaphragm An electroacoustic transducer having a thin film coil formed on the cover and a cover portion provided with a permanent magnet, wherein the thin film coil circulates around one axis, and the permanent magnet is located on the axis. In addition, an electroacoustic transducer is provided in which the direction of the polarity is the same as the direction of the axis.

  Here, the cover portion is made of a non-magnetic material, and a ferromagnetic material can be plated on the inner surface thereof.

  Furthermore, the cover part may be made of a ferromagnetic material.

  Furthermore, a yoke can be provided between the permanent magnet and the cover part.

  Furthermore, the yoke can be made of a ferromagnetic material.

  Furthermore, a core made of a soft magnetic material formed on the diaphragm so as to face the permanent magnet can be provided.

  According to another aspect of the present invention, a substrate having an opening, a diaphragm supported so that one surface faces the opening of the substrate, and a permanent provided on the other surface of the diaphragm An electroacoustic transducer having a magnet and a thin film coil formed on the substrate so as to circulate around the diaphragm, wherein the thin film coil circulates around the center of the permanent magnet as the permanent magnet. An electroacoustic transducer is provided in which the magnet has the same polarity as the axis.

  Here, the material of the diaphragm may be different from that of the substrate.

  Further, the substrate may be made of a semiconductor, and may include an electric circuit formed directly on the substrate and connected to the thin film coil.

  Furthermore, an electric circuit provided on the substrate via an insulating film and connected to the thin film coil can be provided.

  Furthermore, the package of the electroacoustic transducer can be shared with the cover portion.

  Furthermore, by detecting a sound wave incident from the outside through the opening and vibrating the diaphragm and the thin film coil in a magnetic field generated by the permanent magnet, an acoustic signal corresponding to the sound wave can be obtained from the thin film coil. .

  Furthermore, the diaphragm can vibrate by an electromagnetic force of a magnetic field generated by the permanent magnet and a current based on an acoustic signal flowing through the thin film coil, thereby generating a sound wave.

  According to the present invention, a thin film coil formed on a diaphragm supported by a substrate having an opening and a permanent magnet disposed so as to face the thin film coil can be made thin, and can be reduced in size and consumed. An electroacoustic transducer with low power can be provided.

  Further, according to the present invention, a permanent magnet is provided on a diaphragm supported by a substrate, and a thin film coil is formed on the substrate around the diaphragm, so that the film can be further thinned, and is small in size and consumes less power. An electroacoustic transducer can be provided.

  Furthermore, according to the present invention, by arranging an electrical circuit such as a CMOS on the substrate, the connection between the thin film coil and the electrical circuit can be shortened as much as possible, and the influence of noise incident from the outside can be minimized. Therefore, a high-quality electroacoustic transducer can be provided.

  Furthermore, according to the present invention, the cover part having the permanent magnet is made common with the package, so that the film can be further thinned and a small electroacoustic transducer can be provided.

FIG. 1 is a cross-sectional view of a first embodiment of an electroacoustic transducer according to the present invention. FIG. 2 is a sectional view of the electroacoustic transducer according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view of the first embodiment of the electroacoustic transducer including the package of the present invention. FIG. 4 is a cross-sectional view of the first embodiment of the electroacoustic transducer including the package of the present invention. FIG. 5 is a cross-sectional view of the electroacoustic transducer according to the first embodiment of the present invention. FIG. 6 is a cross-sectional view of the first embodiment of the electroacoustic transducer including the package of the present invention. FIG. 7 is a cross-sectional view of the first embodiment of the electroacoustic transducer including the package of the present invention. FIG. 8 is a sectional view of a second embodiment of the electroacoustic transducer of the present invention. FIG. 9 is a sectional view of a second embodiment of the electroacoustic transducer including the package of the present invention. FIG. 10 is a sectional view of a second embodiment of the electroacoustic transducer including the package of the present invention. FIG. 11 is a sectional view of a second embodiment of the electroacoustic transducer of the present invention. FIG. 12 is a sectional view of a second embodiment of the electroacoustic transducer including the package of the present invention. FIG. 13 is a sectional view of a second embodiment of the electroacoustic transducer including the package of the present invention. FIG. 14 is a cross-sectional view of a third embodiment of the electroacoustic transducer of the present invention. FIG. 15 is a sectional view of a third embodiment of the electroacoustic transducer of the present invention. FIG. 16A is a cross-sectional view of the electroacoustic transducer according to the first embodiment of the present invention. FIG. 16B is a plan view of the electroacoustic transducer according to the first embodiment of the present invention. FIG. 17A is sectional drawing which shows the process in the manufacturing method of the electroacoustic transducer of the 1st Example of this invention. FIG. 17B is sectional drawing which shows another process in the manufacturing method of the electroacoustic transducer of the 1st Example of this invention. FIG. 17C is a cross-sectional view showing still another process in the method for manufacturing the electroacoustic transducer according to the first embodiment of the present invention. FIG. 18A is a cross-sectional view showing still another process in the method for manufacturing the electroacoustic transducer according to the first embodiment of the present invention. FIG. 18B is a cross-sectional view showing still another process in the method for manufacturing the electroacoustic transducer according to the first embodiment of the present invention. FIG. 19A is a cross-sectional view of the electroacoustic transducer according to the second embodiment of the present invention. FIG. 19B is a plan view of the electroacoustic transducer according to the second embodiment of the present invention. FIG. 20A is a cross-sectional view showing the steps in the method of manufacturing the electroacoustic transducer according to the second embodiment of the present invention. FIG. 20B is sectional drawing which shows another process in the manufacturing method of the electroacoustic transducer of the 2nd Example of this invention. FIG. 20C is a cross-sectional view showing still another process in the method of manufacturing the electroacoustic transducer according to the second embodiment of the present invention. FIG. 20D is a cross-sectional view showing still another process in the method for manufacturing the electroacoustic transducer according to the second embodiment of the present invention. FIG. 21A is sectional drawing which shows another process in the manufacturing method of the electroacoustic transducer of the 2nd Example of this invention. FIG. 21B is sectional drawing which shows another process in the manufacturing method of the electroacoustic transducer of the 2nd Example of this invention. FIG. 21C is sectional drawing which shows another process in the manufacturing method of the electroacoustic transducer of the 2nd Example of this invention. FIG. 22A is a sectional view of an electroacoustic transducer according to a third embodiment of the present invention. FIG. 22B is a plan view of the electroacoustic transducer according to the third embodiment of the present invention. FIG. 23 is a cross-sectional view of a conventional dynamic electroacoustic transducer.

  The best mode for carrying out the present invention will be described below. The first to third embodiments show the basic structure of the electroacoustic transducer according to the present invention. Specific examples of the present invention and the manufacturing method thereof will be described later.

  FIG. 1 is a sectional view showing an example of an electroacoustic transducer in the first embodiment of the present invention.

  As shown in FIG. 1, a diaphragm 2 is supported on a substrate 1 having an opening 1A, and one surface of the diaphragm 2 faces the opening 1A. Such a basic structure is common to other embodiments and examples of the present invention. A thin film coil 3 is formed on the other surface of the diaphragm 2. The thin film coil 3 is a spiral coil whose planar shape circulates around one axis. Examples of the spiral shape include a spiral shape having no straight portion or a spiral shape having a straight portion and a corner portion. The basic structure of such a thin film coil 3 is common to the second embodiment and the second example of the present invention.

  On the other hand, a dish-shaped yoke 5 is made of a metal plate on a cover portion 4 made of a semiconductor, a glass substrate, a resin, or the like, and a permanent magnet 6 is provided at the central portion of the yoke 5 by adhesion or vapor deposition and patterning. The permanent magnet 6 is preferably thin and cylindrical or polygonal. The direction of the polarity of the permanent magnet 6 is set to be the same as the direction of the central axis of the thin film coil 3. The cover part 4 is fixed to the substrate 1 by adhesion or the like so that the central axis of the thin film coil 3 and the central axis of the permanent magnet 6 coincide. Accordingly, the permanent magnet 6 faces the inner portion of the thin film coil 3. The peripheral part of the cover part 4 is in close contact with the substrate 1 except for the opening part 8. A gap 7 is formed between the diaphragm 2 (and the thin film coil 3) and the yoke 5.

  Here, it is also possible to replace the yoke 5 by forming a ferromagnetic material such as Ni or ferrite inside the cover portion 4 by plating. Further, the entire cover portion 4 can be made of a ferromagnetic material such as Ni or ferrite so that the entire cover portion 4 can be used in place of the yoke 5.

  As the substrate 1, a semiconductor substrate can be used, and the diaphragm 2 can be formed by thinning a part of the semiconductor substrate.

The diaphragm 2 may be made of a material different from that of the substrate 1, and may be a thin film made of a semiconductor, an insulating film such as SiN or SiO ₂ , a metal film such as Al, or a polymer material film such as polyimide. Also good. Further, a single film or a composite film of these materials may be used. In this case, the film can be formed by selectively removing the substrate 1 from the surface opposite to the surface on which the film 2 is formed after the film to be the diaphragm 2 is formed on the substrate 1 using the MEMS technology. Moreover, what was formed by the other method can also be supported by adhesion | attachment etc.

The thin film coil 3 is made of a metal film and can be formed on the diaphragm 2 by plating, sputtering, vapor deposition, or the like. Further, an antioxidant film may be formed on the surface of the thin film coil 3 as necessary. The thin film coil 3 may be laminated via an insulating film such as SiN or SiO ₂ or a polymer material film such as polyimide.

  The electroacoustic apparatus having such a configuration can be operated as a speaker as follows. That is, the magnetic field formed by the yoke 5 and the permanent magnet 6 extends radially from the central axis of the thin film coil 3. Therefore, when a current based on an acoustic signal is applied to the thin film coil 3, the diaphragm 2 vibrates due to the electromagnetic force acting between the magnetic field and the current based on the acoustic signal applied to the thin film coil 3, and the current based on the acoustic signal. Can generate sound waves corresponding to. Further, the electroacoustic apparatus having such a configuration can be operated as a microphone as follows. That is, when the diaphragm 2 vibrates due to the sound wave that has reached the back surface (surface opposite to the coil 3) of the diaphragm 2, the thin film coil 3 moves relatively in the magnetic field, and current flows through the thin film coil 3. An acoustic signal corresponding to the sound wave can be obtained.

  As described above, by forming the thin film coil 3 on the diaphragm 2, the thickness can be reduced. Further, by utilizing the MEMS technology, the gap 7 between the permanent magnet 6 and the thin film coil 3 can be made small and stable, and a sufficient driving force of the diaphragm 2 can be obtained even with a small magnetic force.

  Accordingly, it is possible to realize an electroacoustic transducer that can be thinned, reduced in size, and consumes less power.

  FIG. 2 is a cross-sectional view showing another example of the electroacoustic transducer according to the first embodiment of the present invention.

  The electroacoustic transducer in this example is characterized in that the yoke 5 in the electroacoustic transducer shown in FIG. 1 is not formed, and is otherwise the same as that in FIG. By not forming the yoke 5 in this way, it is possible to reduce the number of manufacturing process steps, leading to cost reduction.

  FIG. 3 is a cross-sectional view of the electroacoustic transducer including the package according to the first embodiment of the present invention.

  This electroacoustic transducer is obtained by bonding the electroacoustic transducer shown in FIG. 1 to the package body 11 by bonding or the like, and bonding the lid 12 to the package body 11 by bonding or the like.

  The package body 11 is made of resin, glass, metal, a composite material thereof, and the like, and has an opening 13 through which sound waves enter and exit on the lower side of the diaphragm 2 of the electroacoustic transducer. The lid 12 is made of resin, glass, metal, and a composite material thereof.

  FIG. 4 is a cross-sectional view showing another example of the electroacoustic transducer including the package according to the first embodiment of the present invention.

  This electroacoustic transducer is characterized in that the cover 4 is joined to the package body 11, and this cover 4 has the same function as the lid 12 of the package shown in FIG. By adopting such a configuration, it can be made thinner and contribute to size reduction and cost reduction as compared with the embodiment of FIG.

  FIG. 5 is a cross-sectional view showing still another example of the electroacoustic transducer according to the first embodiment of the present invention.

  This electroacoustic transducer is provided with an electric circuit 9 such as a CMOS on the substrate 1 of the electroacoustic transducer shown in FIG. The electric circuit 9 includes an amplifier circuit, a DA conversion circuit, an AD conversion circuit, an impedance circuit, and the like. The electric circuit 9 is formed on the substrate 1 made of a semiconductor, or is separately formed and disposed on the substrate 1 via an insulating film. .

  FIG. 6 is a cross-sectional view showing still another example of the electroacoustic transducer including the package according to the first embodiment of the present invention.

  In this electroacoustic transducer, the electroacoustic transducer shown in FIG. 5 is joined to the package body 11 and the lid 12 is joined to the package body 11. The package body 11 is made of resin, glass, metal, a composite material thereof, and the like, and has an opening 13 through which sound waves enter and exit the lower part of the diaphragm of the electro-acoustic transducer. The lid 12 is made of resin, glass, metal, and a composite material thereof.

  FIG. 7 is a sectional view showing still another example of the electroacoustic transducer including the package according to the first embodiment of the present invention.

  This electroacoustic transducer is characterized in that the cover portion 4 is joined to the package body 11, and this cover portion 4 has the same function as the lid 12 of the package shown in FIG. By adopting such a configuration, compared with the embodiment of FIG. 6, it can be made thinner and contribute to size reduction and cost reduction.

  FIG. 8 is a cross-sectional view showing an example of an electroacoustic transducer according to the second embodiment of the present invention.

  This electroacoustic transducer is obtained by adding a core 21 made of a soft magnetic material to the electroacoustic transducer shown in FIG. 2 at a position facing the permanent magnet 6 on the diaphragm 2. The core 21 may be formed of a soft magnetic material such as ferrite, permalloy, or silicon copper.

  When the electroacoustic transducer having such a configuration is used as a speaker, when a current based on an acoustic signal is applied to the thin film coil 3, the electromagnetic field formed by the thin film coil 3 to which the current is applied and the core 21 is applied to the permanent magnet 6. The diaphragm 2 vibrates by acting with a magnetic field, and the speaker which generates the sound wave corresponding to the electric current based on an acoustic signal is comprised. By using the core 21, the electromagnetic field formed by the coil 3 can be concentrated at the center of the apparatus, and the magnetic field of the permanent magnet 6 can be efficiently operated, so that the efficiency as a speaker is further improved. Also, the electroacoustic transducer having such a configuration can be used as a microphone. That is, the diaphragm 2 is vibrated by the sound wave, and the current flows through the thin film coil 3 formed around the core 4 by the movement of the core 21 in the magnetic field generated by the permanent magnet 6. Therefore, an acoustic signal corresponding to the sound wave is generated. And can be used as a microphone.

  According to the configuration of FIG. 8, since the thin film coil 3 and the core 21 are formed on the diaphragm 2, the thickness can be reduced.

  FIG. 9 is a sectional view showing another example of the electroacoustic transducer in the second embodiment of the present invention.

  In this electroacoustic transducer, the electroacoustic transducer shown in FIG. 8 is joined to the package body 11 and the lid 12 is joined to the package body 11. The package body 11 is made of resin, glass, metal, a composite material thereof, and the like, and has an opening 13 through which sound waves enter and exit at the lower part of the diaphragm 2 of the electro-acoustic transducer. The lid 12 is made of resin, glass, metal, and a composite material thereof.

  FIG. 10 is a cross-sectional view showing an example of an electroacoustic transducer including a package according to the second embodiment of the present invention.

  This electroacoustic transducer is characterized in that the cover portion 4 is joined to the package body 11, and this cover portion 4 has the same function as the lid 12 of the package shown in FIG. By adopting such a configuration, the thickness can be reduced compared with the embodiment of FIG. 9, which can contribute to downsizing and cost reduction.

  FIG. 11 is a cross-sectional view showing still another example of the electroacoustic transducer according to the second embodiment of the present invention.

  This electroacoustic transducer is provided with an electric circuit 9 such as a CMOS on the substrate 1 of the electroacoustic transducer shown in FIG. The electric circuit 9 includes an amplifier circuit, a DA conversion circuit, an AD conversion circuit, an impedance circuit, and the like. The electric circuit 9 is formed on a substrate 1 made of a semiconductor, or is separately formed and disposed on the substrate 1 via an insulating film. . The distance between the thin film coil 3 and the electric circuit 9 can be reduced, and the influence of noise can be minimized.

  FIG. 12 is a cross-sectional view showing another example of the electroacoustic transducer including the package according to the second embodiment of the present invention.

  In this electroacoustic transducer, the electroacoustic transducer shown in FIG. 11 is joined to the package body 11 and the lid 12 is joined to the package body 11. The package body 11 is made of resin, glass, metal, a composite material thereof, and the like, and has an opening 13 through which sound waves enter and exit below the diaphragm of the electro-acoustic transducer. The lid 12 is made of resin, glass, metal, and a composite material thereof.

  FIG. 13: is sectional drawing which shows another example of the electroacoustic transducer including the package in the 2nd Embodiment of this invention.

  This electroacoustic transducer is characterized in that the cover part 4 is joined to the package body 11, and this cover part 4 has the same function as the lid 12 of the package shown in FIG. By adopting such a configuration, the thickness can be reduced compared to the embodiment shown in FIG. 12, which can contribute to downsizing and cost reduction.

  FIG. 14 is a cross-sectional view showing an example of an electroacoustic device according to the third embodiment of the present invention.

  As shown in FIG. 14, a diaphragm 2 is formed on a substrate 1, a permanent magnet 6 is provided at the center of the diaphragm 2 by adhesion, vapor deposition, and patterning, and a thin film coil 3 is formed on the substrate 1 around the diaphragm 2. Yes. The thin film coil 3 is a spiral coil whose planar shape circulates around one axis. Examples of the spiral shape include a spiral shape having no straight portion or a spiral shape having a straight portion and a corner portion.

  The permanent magnet 6 is preferably thin and cylindrical or polygonal. The direction of the polarity of the permanent magnet 6 is set to be the same as the direction of the central axis of the thin film coil 3.

  A semiconductor substrate can be used as the substrate 1, and the diaphragm 2 can be formed by thinning a part of the semiconductor substrate.

The diaphragm 2 may be made of a material different from that of the substrate 1, or may be a thin film made of a semiconductor, an insulating film such as SiN or SiO ₂ , a metal film such as Al, or a polymer material film such as polyimide. Good. Further, a single film or a composite film of these materials may be used.

  The thin film coil 3 is made of a metal film and can be formed on the diaphragm 2 by plating, sputtering, vapor deposition, or the like. Further, an antioxidant film may be formed on the surface of the thin film coil 3 as necessary. The thin film coil 3 may be laminated via an insulating film such as SiN or SiO2 or a polymer material film such as polyimide.

  The electromagnetic field formed by the thin film coil 3 to which the current based on the acoustic signal is applied and the magnetic field by the permanent magnet 6 act to vibrate the diaphragm 2 and generate a sound wave corresponding to the current based on the acoustic signal. Can be used as Moreover, since the diaphragm 2 and the permanent magnet 6 are vibrated by the sound wave, and the permanent magnet 6 moves up and down inside the thin film coil 3, a current flows through the thin film coil 3, thereby obtaining an acoustic signal corresponding to the sound wave. Can be used as a microphone.

  FIG. 15: is sectional drawing which shows another example of the electroacoustic transducer in the 3rd Embodiment of this invention.

  This electroacoustic transducer includes an electrical circuit 9 such as a CMOS on the substrate 1 of the electroacoustic transducer shown in FIG. The electric circuit 9 includes an amplifier circuit, a DA conversion circuit, an AD conversion circuit, an impedance circuit, etc., and is formed on the substrate 1 made of a semiconductor, or formed separately and an insulating film is formed on the substrate 1 as necessary. Through. The distance between the thin film coil 3 and the electric circuit 9 can be reduced, and the influence of noise can be minimized.

  Embodiments of the present invention will be described below with reference to the drawings.

  16A is a cross-sectional view of the electroacoustic transducer according to the first embodiment of the present invention, and is a cross-sectional view taken along line XVIA-XVIA of FIG. 16B. FIG. 16B is a plan view, and illustration of the cover portion 4 on which the yoke 5 and the permanent magnet 6 of FIG. 16A are formed is omitted. This example corresponds to the example of FIG. 5 in the first embodiment.

  An oxide film 22 is formed on a substrate 1 made of silicon, and a lead layer 23 made of copper connected to one end of the thin film coil 3 is formed on the oxide film 22, and made of polyimide that becomes the diaphragm 2 so as to cover the lead layer 23. An insulating film 24 is formed, and a thin film coil 3 made of copper, a pad portion 25 made of copper, and an electric circuit 9 are formed on the insulating film 24. The lead-out layer 23 is connected to the thin film coil 3 and the pad portion 25 by a contact layer 26 made of copper. The pad portion 25 and the electric circuit 9 are electrically connected by a bonding wire (not shown).

  A yoke 5 in which ferrite is plated is formed in a recess formed in a cover portion 4 made of a glass substrate, and a permanent magnet 6 is formed on the yoke 5 by adhesion.

  17A, B and C and FIGS. 18A and 18B are cross-sectional views showing respective steps in the method of manufacturing the electroacoustic transducer according to the first embodiment of the present invention.

  As shown in FIG. 17A, an oxide film 22 is formed on the surface of the silicon substrate 1 by thermal oxidation or the like.

  Thereafter, as shown in FIG. 17B, copper is deposited and patterned on the oxide film 22 to form a lead layer 23. An insulating layer 24 is formed by applying and patterning polyimide so as to cover the extraction layer 23. The insulating layer 24 is patterned to form a contact hole 27.

  Thereafter, as shown in FIG. 17C, copper is deposited and patterned to form the contact layer 26. Further, copper is deposited and patterned to form the thin film coil 3 and the pad portion 25. When the depth of the contact hole 27 is shallow, the contact layer 26, the thin film coil 3 and the pad portion 25 can be formed simultaneously. Although not shown, thereafter, the electric circuit 9 is bonded onto the insulating film 24, and the electric circuit 9 and the pad portion 25 are connected by wire bonding. The electric circuit 9, the pad portion 25, and the bonding wire are sealed with resin as necessary. When the electric circuit 9 is formed on the silicon substrate, the process of FIG. 17 is performed after the electric circuit 9 is formed, and the electric circuit 9 is connected when the lead layer 23 and the thin film coil 3 are formed. In this case, the pad portion 25 need not be formed.

  Thereafter, as shown in FIG. 18A, the silicon substrate 1 is etched using the photoresist 28 as a mask to expose the oxide film 22.

  Thereafter, as shown in FIG. 18B, the oxide film 22 is etched using the silicon substrate 1 as a mask to expose the insulating film 24 and the extraction layer 23. The insulating film 24 exposed by etching acts as the diaphragm 2.

  Although not shown, ferrite is vapor-deposited and patterned on the cover portion 4 formed of a glass substrate to form the yoke 5, the permanent magnet 6 is bonded onto the yoke 5, and the cover portion 4 is bonded onto FIG. 18B. Thus, the electroacoustic transducer shown in FIG. 16 is obtained.

  In this embodiment, the step of etching part of the oxide film 22 is performed in FIG. 18B, but the step of etching the oxide film 22 is not performed, and the oxide film 22 and the insulating film 24 may be used as the diaphragm 2. Further, in FIG. 18A, when the silicon substrate 1 is etched, the silicon film 1 is thinned without exposing the oxide film 22, and the portion where the silicon substrate is thinned, the oxide film 22 and the insulating film 24 are connected to the diaphragm 2. The diaphragm 2 configured in this way can be supported on another substrate having a structure such as the substrate 1 of FIG. 1 by bonding or the like.

  19A is a cross-sectional view of the electroacoustic transducer according to the second embodiment of the present invention, and is a cross-sectional view taken along line XIXA-XIXA in FIG. 19B. FIG. 19B is a plan view, and illustration of the cover portion 4 on which the permanent magnet 6 of FIG. 19A is formed is omitted. This example corresponds to the example of FIG. 11 in the second embodiment.

  An oxide film 22 is formed on a substrate 1 made of silicon, and a lead layer 23 made of copper connected to one end of the thin film coil 3 is formed on the oxide film 22, and made of polyimide that becomes the diaphragm 2 so as to cover the lead layer 23. An insulating film 24 is formed, and a thin film coil 3 made of copper, a pad portion 25 made of copper, a core 21 made of ferrite, and an electric circuit 9 are formed on the insulating film 24. The lead-out layer 23 is connected to the thin film coil 3 and the pad portion 25 by a contact layer 26 made of copper. The pad portion 25 and the electric circuit 9 are electrically connected by a bonding wire (not shown).

  20A, B, C, D and FIGS. 21A, B, C are cross-sectional views showing respective steps in the method of manufacturing the electroacoustic transducer of the second embodiment of the present invention.

  As shown in FIG. 20A, an oxide film 22 is formed on the surface of the silicon substrate 1 by thermal oxidation or the like.

  Thereafter, as shown in FIG. 20B, aluminum is deposited and patterned on the oxide film 22 to form the stop layer 29. Copper is vapor-deposited and patterned on the stop layer 29 and the oxide film 22 to form the extraction layer 23.

  Thereafter, as shown in FIG. 20C, polyimide is applied so as to cover the lead layer 23 to form an insulating layer 24. The insulating layer 24 is patterned to form a contact hole 27.

  Thereafter, as shown in FIG. 20D, copper is deposited and patterned to form the contact layer 26. Further, copper is deposited and patterned to form the thin film coil 3 and the pad 25. Ferrite is deposited using a photoresist as a mask, and patterning and etching are performed to form the core 21. Although not shown, when the depth of the contact hole 27 is shallow, the contact layer 26, the thin film coil 3, and the pad portion 25 can be formed simultaneously. Thereafter, the electric circuit 9 is bonded onto the insulating film 24, and the electric circuit 9 and the pad portion 25 are connected by wire bonding. If necessary, the electrical circuit 9 pad portion 25 and the bonding wire are sealed with resin. When the electric circuit 9 is formed on the silicon substrate, the process shown in FIG. 20 is performed after the electric circuit 9 is formed, and the electric circuit 9 is connected when the lead layer 23 and the thin film coil 3 are formed. In this case, the pad portion 25 need not be formed.

  Thereafter, as shown in FIG. 21A, the silicon substrate 1 is etched using the photoresist 28 as a mask to expose the oxide film 22.

  Thereafter, as shown in FIG. 21B, the oxide film 22 is etched using the silicon substrate 1 as a mask to expose the stop layer 29.

  Thereafter, as shown in FIG. 21C, the stop layer 29 is removed by etching to expose the insulating film 24 and the extraction layer 23.

  Although not illustrated, the electroacoustic transducer shown in FIG. 19 is obtained by bonding the permanent magnet 6 to the cover portion 4 formed of a glass substrate and bonding the cover portion 4 on FIG. 21C.

  In this example, the stop layer 29 was formed and manufactured. The reason for forming the stop layer 29 is to reliably etch only the silicon substrate 1 including the oxide film 22 regardless of the etching method. If the stop layer 29 is not provided, the lead layer 23 and the insulating film 24 may be damaged by the etching method.

  In addition, the electroacoustic transducer shown in FIG. 19 can be manufactured by the manufacturing method shown in FIG. 17 and FIG. Conversely, the electroacoustic transducer shown in FIG. 16 can be manufactured by the manufacturing method shown in FIGS.

  22A is a cross-sectional view of the electroacoustic transducer according to the third embodiment of the present invention, and is a cross-sectional view taken along line XXIIA-XXIIA in FIG. 22B. FIG. 22B is a plan view. This example corresponds to the example of FIG. 15 in the third embodiment.

  An oxide film 22 is formed on a substrate 1 made of silicon, and a lead layer 23 made of copper connected to one end of the thin film coil 3 is formed on the oxide film 22, and made of polyimide that becomes the diaphragm 2 so as to cover the lead layer 23. An insulating film 24 is formed, and a thin film coil 3 made of copper and a pad portion 25 electric circuit 9 made of copper are formed on the insulating film 24 and around the diaphragm 2. A permanent magnet 6 is bonded on the center of the diaphragm 2. The lead-out layer 23 is connected to the thin film coil 3 and the pad portion 25 by a contact layer 26 made of copper. The pad portion 25 and the electric circuit 9 are electrically connected by a bonding wire (not shown).

  The electroacoustic transducer of this embodiment can be manufactured by the manufacturing method shown in FIGS. Further, it can be manufactured by the manufacturing method shown in FIGS.

  The manufacturing method described in the embodiments described above is performed using MEMS technology. By using the MEMS technology, it is possible to stably form the interval between the components, and to sufficiently drive the diaphragm even with a small magnetic force.

Claims (14)

A substrate having an opening; a diaphragm supported on the substrate such that one surface faces the opening; a thin film coil formed on the other surface of the diaphragm; and a cover portion provided with a permanent magnet. An electroacoustic transducer comprising: the thin film coil orbiting around one axis, the permanent magnet being located on the axis, and the direction of the polarity being the same as the direction of the axis. A characteristic electroacoustic transducer. 2. The electroacoustic transducer according to claim 1, wherein the cover portion is made of a nonmagnetic material, and a ferromagnetic material is plated on an inner surface thereof. 2. The electroacoustic transducer according to claim 1, wherein the cover is made of a ferromagnetic material. The electroacoustic transducer according to claim 1, further comprising a yoke between the permanent magnet and the cover. The electroacoustic transducer according to claim 4, wherein the yoke is made of a ferromagnetic material. 2. The electroacoustic transducer according to claim 1, further comprising a core made of a soft magnetic material formed on the diaphragm so as to face the permanent magnet. The electroacoustic transducer according to any one of claims 1 to 6, wherein a material of the diaphragm is different from that of the substrate. A substrate having an opening; a diaphragm supported on the substrate so that one surface faces the opening; a permanent magnet provided on the other surface of the diaphragm; and the substrate on the substrate so as to go around the diaphragm. An electroacoustic transducer having a thin-film coil formed on the magnet, wherein the thin-film coil circulates around the center of the permanent magnet, and the polarity of the permanent magnet is the same as the direction of the axis. An electroacoustic transducer characterized by being. The electroacoustic transducer according to claim 8, wherein a material of the diaphragm is different from that of the substrate. 2. The electroacoustic transducer according to claim 1, wherein the substrate is made of a semiconductor, and includes an electric circuit directly formed on the substrate and connected to the thin film coil. 2. The electroacoustic transducer according to claim 1, further comprising an electric circuit provided on the substrate via an insulating film and connected to the thin film coil. 2. The electroacoustic transducer according to claim 1, wherein a package of the electroacoustic transducer is shared with the cover portion. 2. The electroacoustic transducer according to claim 1, wherein the diaphragm and the thin film coil vibrate in a magnetic field generated by the permanent magnet by sensing a sound wave incident from the outside through the opening, thereby generating a sound wave from the thin film coil. An electroacoustic transducer characterized by obtaining an acoustic signal corresponding to the above. 2. The electroacoustic transducer according to claim 1, wherein the diaphragm vibrates by an electromagnetic force of a magnetic field generated by the permanent magnet and an electric current based on an acoustic signal flowing through the thin film coil to generate a sound wave. Conversion device.

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