JP4587126B2 - Condenser microphone and method of manufacturing condenser microphone - Google Patents

Description

  The present invention relates to a condenser microphone and a manufacturing method thereof, and more particularly to a condenser microphone using a semiconductor film and a manufacturing method thereof.

  Conventionally, a condenser microphone that can be manufactured by applying a manufacturing process of a semiconductor device is known. The condenser microphone has an electrode on each of the plate and the diaphragm that is vibrated by sound waves, and the plate and the diaphragm are supported in a state of being separated from each other by an insulating spacer. The condenser microphone converts the capacitance change due to the displacement of the diaphragm into an electric signal and outputs it. The sensitivity of the condenser microphone is improved by increasing the displacement of the diaphragm, reducing the leakage current of the spacer, and reducing the parasitic capacitance.

Non-Patent Document 1 discloses a condenser microphone in which each of a plate and a diaphragm that is vibrated by sound waves is formed of a conductive thin film. However, even if the sound wave propagates to the diaphragm, the end fixed to the spacer hardly displaces, so each end of the diaphragm and the plate made of a conductive thin film fixed to the spacer is The sensitivity of the condenser microphone is reduced by forming a parasitic capacitance.
Patent Document 1 discloses a condenser microphone including a diaphragm having a structure in which an electrode made of a conductive material is fixed to a central portion of an insulating film. In this structure, although the parasitic capacitance is reduced, the manufacturing process is complicated, so that there is a problem in that the manufacturing yield decreases and the manufacturing cost increases. In addition, in the process of removing the sacrificial layer for forming a gap between the diaphragm and the plate by etching, the insulating film to which the electrode is fixed is also etched, so it is necessary to incorporate this measure into the process. Even boosts manufacturing costs.

The Institute of Electrical Engineers of Japan MSS-01-34 (NHK) JP-T-2004-506394

  An object of the present invention is to provide a condenser microphone with high sensitivity and low manufacturing cost, and a manufacturing method thereof.

(1) A condenser microphone for achieving the above object includes a plate having a fixed electrode, a diaphragm having a movable electrode and vibrating by sound waves, supporting the plate and the diaphragm while insulating them, and A spacer that forms a gap between the movable electrodes, and at least one of the plate and the diaphragm has a specific resistance at a near end close to the spacer compared to a specific resistance at a center far from the spacer. It is a high monolayer film of semiconductor or metal.
By making the specific resistance of at least a part of the near end near the spacer of at least one of the plate and the diaphragm higher than that of the remaining part, the capacitance with small capacitance change, that is, the parasitic capacitance can be reduced, and the sensitivity of the condenser microphone is increased. . By forming the plate or the diaphragm with a single layer film of semiconductor or metal whose specific resistance varies depending on the region, the manufacturing process of the condenser microphone is simplified, and a highly sensitive condenser microphone can be manufactured at low cost.

  (2) Impurities may be diffused in the near end portion.

  (3) The central portion may be formed of silicon, and the proximal end portion may be formed of silicon nitride.

  (4) The central portion may be formed of silicon, and the proximal end portion may be formed of silicon oxynitride.

  (5) The film thickness of the near end part may be larger than the film thickness of the central part.

(6) A method of manufacturing a condenser microphone for achieving the above object includes a plate having a fixed electrode, a diaphragm having a movable electrode and vibrating by sound waves, and supporting the plate and the diaphragm while insulating them, A method of manufacturing a condenser microphone comprising a fixed electrode and a spacer forming a gap between the movable electrode, wherein a semiconductor single layer film or a metal single layer film constituting at least one of the plate and the diaphragm is formed. And modifying the near end portion of the semiconductor single layer film or the metal single layer film near the spacer so that the specific resistance of the near end portion is higher than the specific resistance of the central portion far from the spacer. .
By setting the specific resistance of the near end near the spacer of at least one of the plate and the diaphragm to be higher than that of the central portion, it is possible to reduce a capacitance with a small capacitance change, that is, a parasitic capacitance. By modifying the single layer film of semiconductor or metal to form limited areas with high specific resistance, the manufacturing process of condenser microphones is simplified, and the specific resistance near the plate or diaphragm spacer is reduced. Since it can be higher than the rest, the manufacturing cost of a highly sensitive condenser microphone can be reduced.

(7) The near end portion may be modified by ion implantation into the near end portion while the central portion of the semiconductor single layer film or the metal single layer film is masked.
Since the ion-implanted region becomes amorphous, the specific resistance increases. Accordingly, the specific resistance near the plate or diaphragm spacer can be made higher than that of the remainder without performing an annealing step for activating ions by modification by ion implantation.

(8) By implanting ions into the semiconductor single layer film or the metal single layer film while masking the central portion of the semiconductor single layer film or the metal single layer film, and activating the ions by annealing The near end may be modified.
For example, the near end portion of the semiconductor single layer film or the metal single layer film can be insulated by annealing after implantation of oxygen ions or nitrogen ions. .

(9) The near end portion may be modified by thermally oxidizing the near end portion in a state where the central portion of the silicon film as the semiconductor single layer film is masked.
By thermal oxidation, the near end portion of the semiconductor single layer film or the metal single layer film can be insulated, and the film thickness of the near end portion of the semiconductor single layer film or the metal single layer film can be increased.

  (10) The near end portion may be modified by performing plasma treatment on the near end portion in a state where the central portion of the semiconductor single layer film or the metal single layer film is masked.

Embodiments of the present invention will be described below based on a plurality of examples.
(First Example)
FIG. 1B is a schematic diagram showing the configuration of the condenser microphone 1 according to the first embodiment. The condenser microphone 1 includes a sound sensing part drawn as a cross-sectional view in FIG. 1B and a detection part drawn as a circuit diagram in FIG.

(Configuration of sound sensor)
The end of the back plate 10 and the end of the diaphragm 30 are fixed to the spacer 44. That is, the back plate 10 and the diaphragm 30 are supported in parallel with each other with the pressure chamber 46 formed between them by the spacer 44. FIG. 1A shows only the back plate 10 and its peripheral portion and the pad portion 13 of the back plate 10. The shape of the back plate 10 in plan view is not particularly limited, and may be a circular shape or other shapes. The back plate 10 has a plurality of acoustic holes 18 that penetrate the back plate 10. The sound wave that has passed through the acoustic hole 18 of the back plate 10 vibrates the diaphragm 30. The shape of the acoustic hole 18 in plan view is not particularly limited, and may be circular as shown in FIG. 1 (A) or other shapes.

  The back plate 10 and its pad portion 13 are composed of a semiconductor film such as polycrystalline Si or a metal film 22 such as Ti. The back plate 10 is formed of a circular portion that is not fixed to the insulating film 45 of the semiconductor or metal film 22. The semiconductor or metal film 22 is a single layer film having different specific resistance depending on the region, and the specific resistance at the near end of the back plate 10 is higher than the specific resistance at the center of the back plate 10. The near end 20 near the end fixed to the spacer 44 of the back plate 10 is formed by a high resistance region of a semiconductor or metal film 22. The disc-shaped central portion 14 of the back plate 10, the linear connection portion 16 extending from the central portion 14 to the pad portion 13, and the pad portion 13 are formed by a low resistance region of a semiconductor or metal film 22. The larger the difference in specific resistance between the near end portion 20 and the central portion 14 of the back plate 10, the better. The area of the central portion 14 of the back plate 10 is, for example, a value obtained by dividing the volume of a trajectory in which the diaphragm 30 vibrates when a certain sound wave is propagated by the amplitude of the center of the diaphragm 30. Specifically, for example, the area of the central portion 14 is set to one third to one half of the area of the diaphragm 30. The shape of the central portion 14 of the diaphragm 30 that lowers the specific resistance is, for example, a circular shape similar to the entire diaphragm 30.

  In order to divide the semiconductor or metal film 22 into a high resistance region and a low resistance region, the high resistance region is composed of an amorphous semiconductor or metal, and the low resistance region is composed of a crystalline semiconductor or metal. Alternatively, the high resistance region of the semiconductor or metal film 22 is made of a semiconductor or metal oxide or nitride, and the low resistance region is made of a semiconductor or metal. When the semiconductor or metal film 22 constituting the back plate 10 and its pad portion 13 is a semiconductor film, it is desirable to use a semiconductor film in which impurities serving as donors or acceptors are diffused at a high concentration. By forming the central portion 14 of the back plate 10 with a crystalline semiconductor film in which impurities serving as donors or acceptors are diffused at a high concentration, a near portion made of an amorphous semiconductor, an amorphous metal, a semiconductor oxide, or a semiconductor nitride is formed. Compared to the end 20, the specific resistance of the central portion 14 of the back plate 10 can be further reduced.

  The diaphragm 30 and its pad portion 31 are constituted by a semiconductor such as polycrystalline Si or a metal film 32 such as Ti. The diaphragm 30 is formed of a circular portion that is not fixed to the insulating films 43 and 45 of the semiconductor or metal film 32. When the semiconductor 30 or the metal film 32 constituting the diaphragm 30 and its pad portion 31 is a semiconductor film, the specific resistance of the diaphragm 30 is further reduced by using a semiconductor film in which impurities serving as donors or acceptors are diffused at a high concentration. It is desirable to make it. As in the case of the back plate 10, the semiconductor or metal film 32 constituting the diaphragm 30 is a film having different specific resistance depending on the region, so that the specific resistance at the near end of the diaphragm 30 can be made higher than that at the center. Good. However, if the specific resistance of one of the diaphragm 30 and the back plate 10 is higher than the central portion, the sensitivity of the condenser microphone 1 is improved even if the other specific resistance is uniform. That is, the same effect can be obtained even if the semiconductor or metal film 32 constituting the diaphragm 30 is a film having a different specific resistance depending on the region and the specific resistance of the entire back plate 10 is made uniform. Further, by using only one of the diaphragm 30 and the back plate 10 as a semiconductor or metal film having a higher specific resistance at the near end than that at the center, a lithography process, an ion that is necessary for limiting the high resistance region Since the implantation step, the annealing step, and the like are not necessary, the manufacturing process of the condenser microphone 1 can be simplified.

The spacer 44 includes an insulating film 45 constituting the side wall surface 47 of the pressure chamber 46 and a portion of the semiconductor or metal film 22, 32 outside the side wall surface 47 of the pressure chamber 46.
The base 40 includes a pressure buffer chamber 33 corresponding to the diaphragm 30, and is configured by an insulating film 43 and a base film 51 to which a semiconductor or metal film 32 constituting the diaphragm 30 is fixed. By increasing the volume of the pressure buffer chamber 33, when the sound wave propagates to the diaphragm 30 with the pressure buffer chamber 33 sealed, the vibration of the diaphragm 30 is hardly suppressed by the internal pressure of the pressure buffer chamber 33.

  Note that the diaphragm 30 may be positioned closer to the sound source than the back plate 10, and the sound wave may propagate directly to the diaphragm 30. In this case, the acoustic hole 18 functions as an air passage that connects the pressure chamber 46 formed between the back plate 10 and the diaphragm 30 and the external space thereof.

(Configuration of detector)
A lead wire 104 connected to one end of the resistor 100 is connected to the pad portion 31 of the diaphragm 30. A lead wire 106 connected to the ground of the substrate on which the condenser microphone 1 is mounted is connected to the pad portion 13 of the back plate 10. The other end of the resistor 100 is connected to a lead wire 108 connected to the output end of the bias power supply circuit 102. A resistor 100 having a large resistance value is used. Specifically, the resistor 100 preferably has an electrical resistance on the order of GΩ. A lead wire 114 connected to one end of the capacitor 112 is connected to the input end of the preamplifier 110. The lead wire 104 connecting the diaphragm 30 and the resistor 100 is also connected to the other end of the capacitor 112.

(Condenser microphone operation)
When the sound wave passes through the acoustic hole 18 of the back plate 10 and propagates to the diaphragm 30, the diaphragm 30 is vibrated by the sound wave. When diaphragm 30 vibrates, the distance between back plate 10 and diaphragm 30 changes due to the vibration, and the capacitance of the capacitor constituted by diaphragm 30 and back plate 10 changes.

  Since the diaphragm 30 is connected to the resistor 100 having a large resistance value via the pad portion 31, even if the capacitance of the capacitor is changed by the vibration of the diaphragm 30 as described above, it is accumulated in the capacitor. Charge hardly flows through the resistor 100. That is, the charge accumulated in the capacitor formed by the diaphragm 30 and the back plate 10 can be regarded as not changing. Therefore, a change in the capacitance of the capacitor can be taken out as a change in the voltage between the diaphragm 30 and the back plate 10.

The condenser microphone 1 amplifies a change in voltage with respect to the ground of the diaphragm 30 by the preamplifier 110, and outputs a very slight change in the capacitance of the capacitor as an electric signal. That is, the condenser microphone 1 correlates with a change in sound pressure by converting a change in sound pressure applied to the diaphragm 30 into a change in capacitance of the capacitor and converting a change in capacitance of the capacitor into a change in voltage. Output electrical signals.
The diaphragm 30 vibrates with its end portion as a fixed end. Therefore, the center farthest from the end of the diaphragm vibrates with the largest amplitude. In contrast, the amplitude of the near end 20 near the end fixed to the spacer 44 of the diaphragm 30 is small.

  By the way, the equivalent circuit shown in FIG. 2A of a condenser microphone provided with a thin film electrode having uniform conductivity has a capacitance Cs formed by the near end portion of the diaphragm and the back plate, which is assumed to not vibrate at all. The center part of the diaphragm assumed to vibrate while maintaining a flat shape with a certain amplitude and the capacitor Cb formed by the back plate are connected in parallel. When it is considered that the diaphragm 30 is composed of a central portion that vibrates while maintaining a flat shape with a certain amplitude, and a near end portion that does not vibrate at all, the diaphragm 30 is vibrated between the near end portion and the central portion as the diaphragm 30 vibrates. When the movement of charge occurs, the potential of the near end of the diaphragm 30 with respect to the near end of the back plate 10 fluctuates, and the potential fluctuation width of the center of the diaphragm with respect to the center of the back plate 10 becomes small. The potential fluctuation at the near end of the diaphragm 30 with respect to the near end of the back plate 10 is a noise component of the output signal of the condenser microphone 1, and the potential fluctuation at the center of the diaphragm with respect to the center of the back plate 10 is the output of the condenser microphone 1. The true signal component of the signal.

  In the condenser microphone 1 according to this embodiment, the specific resistance of the near end portion 20 near the end portion fixed to the spacer 44 of the back plate 10 is higher than that of the central portion 14. Therefore, as shown in FIG. 2B, the equivalent circuit of the condenser microphone 1 according to the present embodiment has a capacitance Cs formed by the near end portion of the diaphragm 30 and the back plate 10 that is assumed not to vibrate at all, and a certain amplitude. A large internal resistance R is connected between the center portion of the diaphragm 30 that is assumed to vibrate while maintaining a flat shape, and the capacitor Cb formed by the back plate. Since the internal resistance R prevents the movement of charges between the capacitance Cs and the capacitance Cb due to the vibration of the diaphragm 30, the potential variation of the near end portion of the diaphragm 30 with respect to the near end portion 20 of the back plate 10 is suppressed. Therefore, the condenser microphone 1 according to the present embodiment has higher sensitivity than the condenser microphone provided with the thin film electrode having uniform conductivity.

(Production method)
3 to 5 are cross-sectional views showing a method of manufacturing the condenser microphone 1 according to the first embodiment.
First, as shown in FIG. 3A, a base film 51 and an insulating film 43 are formed. Specifically, for example, SiO ₂ is deposited on the surface of the single crystal silicon substrate which is the base film 51 by the CVD method. The insulating film 43 may be formed by thermal oxidation of a single crystal silicon substrate. However, in order to make the etching rate of an insulating film 45 made of SiO ₂ and an insulating film 43 made of SiO ₂ to be described later identical, Preferably ₂ is deposited.

  Next, as shown in FIG. 3B, a semiconductor or metal film 32 constituting the diaphragm 30 and its pad portion 31 is formed on the insulating film 43. When the semiconductor film 32 is formed, Si is deposited on the insulating film 43 by, for example, LPCVD. Note that the Si film may be activated by annealing after the deposited Si film is doped with an impurity serving as a donor or acceptor by high-concentration ion implantation. Further, when Si is deposited on the insulating film 43 by the LPCVD method, impurities serving as donors or acceptors may be doped into Si in situ. When the metal film 32 is formed, Ti is deposited on the insulating film 43 by sputtering, for example.

Next, as shown in FIG. 3C, the semiconductor or metal film 32 is patterned into a desired shape. Specifically, a mask is first formed on the film 32 by lithography, and then the film 32 is etched using a mixed solution of HNO ₃ and HF or HF to remove the mask.
Next, as shown in FIG. 3D, an insulating film 45 constituting the spacer 44 is formed on the semiconductor or metal film 32. Specifically, for example, SiO ₂ is deposited on the film 32 by the CVD method.

  Next, as shown in FIG. 4A, a semiconductor or metal film 22 constituting the back plate 10 and its pad portion 13 is formed on the insulating film 45. When the semiconductor film 22 is formed, Si is deposited on the insulating film 45 by, for example, LPCVD. Note that the Si film may be activated by annealing after the deposited Si film is doped with an impurity serving as a donor or acceptor by high-concentration ion implantation. Further, when Si is deposited on the insulating film 45 by LPCVD, impurities serving as donors or acceptors may be doped into Si in situ. When the metal film 22 is formed, Ti is deposited on the insulating film 45 by sputtering, for example.

Next, as shown in FIG. 4B, a mask 60 having a predetermined pattern made of a resist or the like is formed on the film 22 by lithography. The mask 60 is a mask for ion implantation, and has an opening 62 corresponding to the near end portion 20 of the back plate 10 and the near end portion 15 of the pad portion 13. By doping impurities by ion implantation, the amount, depth, and distribution of impurities inside the semiconductor or metal film 22 can be accurately controlled, and the process can proceed at a low temperature. The impurity may be doped into the film 22 by diffusion using a Si ₃ N ₄ film or the like as the mask 60. The semiconductor or metal film 22 may be doped with O or N by plasma treatment using oxygen plasma or nitrogen plasma.

  Next, as shown in FIG. 4C, impurities are ion-implanted into the semiconductor or metal film 22, and the mask 60 is removed. Examples of the impurity include Ar, O, N, and P. By ion-implanting impurities into a part of the semiconductor or metal film 22, the region of the film 22 doped with impurities can be made amorphous to increase its specific resistance. In the case where O or N is ion-implanted into a part of the semiconductor or metal film 22, the ion-implanted film 22 may be annealed. By annealing the film 22 partially ion-implanted with O or N, the doped O or N and the semiconductor or metal constituting the film 22 are chemically activated to react with each other. Alternatively, an insulating oxide region or a nitride region can be formed in the film 22.

Next, as shown in FIG. 5A, the semiconductor or metal film 22 is patterned into a desired shape, and an acoustic hole 18 is formed in the film 22. Specifically, a mask is first formed on the film 22 by lithography, and then the film 22 is etched using a mixed solution of HNO ₃ and HF or HF to remove the mask.
Next, as shown in FIG. 5B, a mask 64 having a predetermined pattern is formed on the surface of the base film 51 by lithography. The mask 64 is an etching mask for forming a part of the pressure buffer chamber 33 of the base 40, and has an opening 66 at a portion corresponding to the pressure buffer chamber 33.

Next, as shown in FIG. 5C, after the portion exposed in the opening 66 of the base film 51 is removed by DeepRIE, the side wall surface 52 of the pressure buffer chamber 33 is formed on the base film 51, and then the mask 64 Remove.
Next, when the insulating film 43 and the insulating film 45 are etched using BHF or the like using the base film 51 and the semiconductor or metal film 22 as a mask, the sound sensing part of the capacitor microphone 1 shown in FIG. 1 is obtained. The etching solution reaches the insulating film 43 and the insulating film 45 from the pressure buffer chamber 33 formed in the base film 51 and the acoustic hole 18 formed in the film 22, and etches the insulating film 43 and the insulating film 45. The remainder of the buffer chamber 33 and the pressure chamber 46 are formed.

  As described above, general-purpose semiconductor devices in which impurities are ion-implanted into a part of the semiconductor or metal film 22 or impurities are ion-implanted into a part of the semiconductor or metal film 22 and then the film 22 is annealed. By using a typical manufacturing process, the back plate 10 can be formed of a semiconductor or metal film 22 having a specific resistance different depending on a region. Therefore, a condenser microphone with a simple structure and high sensitivity can be manufactured at low cost. In particular, according to the method of forming the back plate 10 with the semiconductor or metal film 22 partially amorphousized by ion implantation of impurities into a part of the semiconductor or metal film 22, the heat treatment process is reduced. Therefore, thermal damage to the thin film constituting the condenser microphone 1 and diffusion of unnecessary impurities can be suppressed. Therefore, the manufacturing cost of the condenser microphone 1 can be further reduced.

(Second embodiment)
FIG. 6 is a cross-sectional view showing the condenser microphone 2 and the manufacturing method thereof according to the second embodiment.
As shown in FIG. 6D, in the condenser microphone 2 according to the second embodiment, there is no insulating film between the film 74 constituting the back plate 70 and the film 32 constituting the diaphragm 30. By the high resistance region of the semiconductor or metal film 74, the diaphragm 30 and the back plate 70 can be supported in an insulating state or a state close thereto. Further, if the high resistance region of the semiconductor or metal film 74 is insulated, the sensitivity of the condenser microphone 2 can be further improved. Incidentally, since there is no insulating film between the film 74 constituting the back plate 70 and the film 32 constituting the diaphragm 30, a conductive film to be wired to the central portion 14 of the back plate 70 is formed on the surface of the film 74. I need it.

In the method of manufacturing the condenser microphone 2, first, the steps shown in FIGS. 3A to 3C are performed.
Next, as shown in FIG. 6A, a sacrificial film 80 is formed on the semiconductor or metal film 32.
Next, as shown in FIG. 6B, the sacrificial film 80 is patterned into a desired shape. Specifically, a mask is first formed on the sacrificial film 80 by lithography, and then the sacrificial film 80 is etched to remove the mask.

Next, as shown in FIG. 6C, a semiconductor or metal film 74 is formed on the semiconductor or metal film 32 so as to cover the sacrificial film 80. A specific method for forming the film 74 is based on the method for forming the film 22 (see FIG. 4A).
Next, a high resistance region is formed in the semiconductor or metal film 74 in accordance with the modification process of the semiconductor or metal film 22 (see FIGS. 4B and 4C).
Next, the semiconductor or metal film 74 is patterned in accordance with the patterning step of the semiconductor or metal film 22 (see FIG. 5A).

Next, the base film 51 is etched to form a part of the pressure buffer chamber 33 in the base film 51 (see FIGS. 5B and 5C).
Next, when the sacrificial film 80 is etched using the semiconductor or metal film 74 as a mask and the insulating film 43 is etched using BHF or the like using the base film 51 as a mask, the capacitor microphone 2 shown in FIG. 6D is obtained.

  As described above, the back plate 70 and a part of the spacer 72 are integrally formed with the semiconductor or metal film 74 having a specific resistance different depending on the region, so that the electrode is fixed to the central portion of the insulating film. The structure and manufacturing process of the condenser microphone 2 can be simplified as compared with the conventional condenser microphone. Therefore, the manufacturing cost of the condenser microphone 2 can be reduced.

(Third embodiment)
FIG. 7 is a cross-sectional view showing a condenser microphone 3 and a method for manufacturing the same according to the third embodiment.
As shown in FIG. 7D, in the condenser microphone 3 according to the third embodiment, the high resistance region of the film 24 constituting the back plate 10 is thicker than the low resistance region. The thick high resistance region constituting the near end 20 of the back plate 10 of the semiconductor or metal film 24 is made of a semiconductor or metal oxide or oxynitride.

In the method of manufacturing the condenser microphone 3, first, a semiconductor or metal film 24 is formed by the steps shown in FIGS. 3 (A) to 4 (A).
Next, as shown in FIG. 7A, a mask 82 having an opening 84 corresponding to the near end 20 of the back plate 10 and the pad 13 is formed on the semiconductor or metal film 24. Specifically, for example, first, Si ₃ N ₄ is deposited on the entire surface of the semiconductor or metal film 24 by a CVD method. Next, a resist film having a predetermined pattern is formed on the deposited Si ₃ N ₄ film by lithography, the Si ₃ N ₄ film is etched using H ₃ PO ₄ or the like, and the resist film is removed. can get.

Next, as shown in FIG. 7B, the portion exposed from the opening 84 of the semiconductor or metal film 24 is selectively oxidized or oxynitrided. Specifically, the film 24 is oxidized by, for example, thermal oxidation. In addition, the film 24 can be oxynitrided by using a gas containing NH ₃ at the time of thermal oxidation. When the film 24 is made of Si, it is preferable to oxynitride the film 24 made of Si in order to suppress the etching of the film 24 in the etching process described later of the insulating films 45 and 43 made of SiO ₂ . The oxidized or oxynitrided region of the semiconductor or metal film 24 expands in volume and becomes thicker than the semiconductor or metal region.

Next, as shown in FIG. 7C, the mask 82 is removed. For example, the mask 82 is etched using H ₃ PO ₄ or the like.
Next, the semiconductor or metal film 24 is patterned into a desired shape, and the acoustic hole 18 is formed in the semiconductor or metal film 24. The film 22 is made of “semiconductor or metal” and “semiconductor or metal oxide or oxynitride”. What is the specific etching method? Can it be etched once?
Next, the base film 51 is etched to form a part of the pressure buffer chamber 33 in the base film 51 (see FIGS. 5B and 5C).
Next, when the insulating film 43 and the insulating film 45 are etched with BHF or the like using the base film 51 and the semiconductor or metal film 24 as a mask, the capacitor microphone 3 shown in FIG. 7D is obtained.

(A) is a top view which shows the diaphragm of the capacitor | condenser microphone by 1st Example of this invention, (B) is a schematic diagram which shows the capacitor | condenser microphone by 1st Example of this invention. The circuit diagram which shows the equivalent circuit of the capacitor | condenser microphone by 1st Example of this invention. Sectional drawing which shows the manufacturing method of the condenser microphone by 1st Example of this invention. Sectional drawing which shows the manufacturing method of the condenser microphone by 1st Example of this invention. Sectional drawing which shows the manufacturing method of the condenser microphone by 1st Example of this invention. Sectional drawing which shows the condenser microphone and its manufacturing method by 2nd Example of this invention. Sectional drawing which shows the condenser microphone by the 3rd Example of this invention, and its manufacturing method.

Explanation of symbols

  1-3 Capacitor microphones 10, 70 Back plate, 13 Pad part, 14 Center part, 16 Connection part, 18 Acoustic hole, 20 Near end part, 22 Semiconductor or metal film, 24 Si film, 30 Diaphragm, 32 Semiconductor or Metal film, 44, 72 spacer, 46 Pressure chamber, 74 Semiconductor or metal film

Claims (4)

A plate having fixed electrodes;
A diaphragm having a movable electrode and vibrating by sound waves;
A spacer that supports the plate and the diaphragm while insulating them, and that forms a gap between the fixed electrode and the movable electrode,
Said plate, at least one of the diaphragm, the specific resistance of the proximal end closer to the spacer is higher than the specific resistance of the distant center portion from said spacer, Ri monolayer der semiconductor or metal,
The near end is amorphized by impurity diffusion,
Condenser microphone. A plate having fixed electrodes;
A diaphragm having a movable electrode and vibrating by sound waves;
A spacer that supports the plate and the diaphragm while insulating them, and that forms a gap between the fixed electrode and the movable electrode,
At least one of the plate and the diaphragm is a single layer film of a semiconductor or a metal whose specific resistance near the spacer is higher than the specific resistance of the central portion far from the spacer,
The near end has an oxidized region or a nitrided region due to impurity diffusion,
Condenser microphone. A plate having a fixed electrode, a diaphragm having a movable electrode and vibrating by sound waves,
A method of manufacturing a condenser microphone that includes a spacer that supports the plate and the diaphragm while insulating them, and includes a spacer that forms a gap between the fixed electrode and the movable electrode,
Forming a single-layer semiconductor film or a metal single-layer film constituting at least one of the plate and the diaphragm;
The near end portion is made amorphous by implanting ions into the near end portion close to the spacer in a state where the central portion of the semiconductor single layer film or the metal single layer film is masked, and the specific resistance of the near end portion Higher than the specific resistance in the center far from the spacer,
A method of manufacturing a condenser microphone. A plate having a fixed electrode, a diaphragm having a movable electrode and vibrating by sound waves,
A method of manufacturing a condenser microphone that includes a spacer that supports the plate and the diaphragm while insulating them, and includes a spacer that forms a gap between the fixed electrode and the movable electrode,
Forming a single-layer semiconductor film or a metal single-layer film constituting at least one of the plate and the diaphragm;
In the state where the central portion of the semiconductor single layer film or the metal single layer film is masked, oxygen or nitrogen is ion-implanted into a near end portion close to the spacer and then annealed to the ion-implanted near end portion. Forming an oxidized region or a nitrided region, and making the specific resistance of the near end portion higher than the specific resistance of the central portion far from the spacer;
A method of manufacturing a condenser microphone.

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