JP3378197B2 - Semiconductor electret condenser microphone - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor electret condenser microphone to which a technique for forming a semiconductor element is applied.

[0002]

2. Description of the Related Art A conventional electret condenser microphone will be described with reference to FIG. This conventional electret condenser microphone mainly includes a microphone unit 500 that outputs an input sound as an electric signal.
And a case part 60 for accommodating the microphone part 500.
It is composed of 0 and 0.

The microphone section 500 has a fixed electrode 510 having an electret layer 511 formed on the surface thereof, a vibrating membrane 530 facing the fixed electrode 510 with a spacer 520 at a fixed interval, and a gate terminal 5.
41 has the fixed electrode 510, and the source terminal 542 has the FET 540 as an impedance conversion element connected to the electrode layer (not shown) of the vibrating film 530.

The fixed electrode 510 and the electret layer 511 formed on the surface of the fixed electrode 510 have a space 550 between the fixed electrode 510 and the vibrating membrane 530 in the back chamber 6.
A through hole 512 for communicating with 50 is provided.

On the other hand, the case part 600 is made of a conductive material and has a substantially bottomed cylindrical shape.
Between the board portion 620 on which the FET 540 is mounted and the holder portion 630 for holding the microphone portion 500, the vibrating membrane 530, and the case body portion 610. And an intervening conductive ring 640.

In this type of electret condenser microphone, sound is transmitted to the vibrating membrane 530 through the sound hole 611 formed in the case main body 610, and the electret layer 511 of the fixed electrode 510 is accompanied by the vibration of the vibrating membrane 530. The change in the voltage due to the change in the electrostatic capacity of the capacitor configured by is output as an electric signal.

There is also a semiconductor electret condenser microphone aimed at further miniaturization. As shown in FIG. 10, this semiconductor electret condenser microphone is configured by applying a technique for forming a semiconductor element to a microphone section 700. That is, the microphone part 700 includes a wafer part 710 on which an integrated circuit including an impedance conversion element and an amplification element is formed, an electret layer 720 formed on the surface of the wafer part 710, and a spacer formed on the electret layer 720. 730
And the vibrating film 740 attached to the spacer 730.
And a through hole 711 is opened in the wafer portion 710 and the electret layer 720.

On the other hand, the case portion 800 is made of a conductive material and has a substantially bottomed cylindrical shape.
And the ground plate portion 82 that closes the open side of the case body portion 810 and is electrically connected to the case body portion 810.
0, and a holder part 8 for holding the microphone part 700.
30 and 30.

The through hole 711 formed in the microphone part 700 is a holder part 83 which constitutes the case part 800.
It communicates with the back chamber 840 that is recessed in 0.

The manufacturing process of the microphone part 700 of such a semiconductor electret condenser microphone is as follows. First, a large number of integrated circuits are formed on the wafer unit 710. A silicon oxide film is formed on the side where the integrated circuit is formed. The silicon oxide film is electretized by an appropriate method such as heating / cooling or electron beam irradiation to form an electret layer 720.

Next, a through hole 711 is formed in the electret layer 720 and the wafer portion 710. This through hole 711
Is performed by laser processing or ultrasonic processing. Further, the spacer 730 is formed.

A vibration film 740 is attached to the spacer 730. Then, the electret layer 720 and the vibrating film 74
The space 7 corresponding to the thickness of the spacer 730
50 is formed. An electrode film 741 is previously formed on the upper surface of the vibrating film 740.

A large number of microphone parts 700 formed on the wafer are divided by a dicing saw. The terminal 760 is attached to the back side of the wafer part 710 of the divided microphone part 700, and the microphone part 700 is completed.

The microphone portion 70 formed in this way
0 is held by the holder portion 830 of the case portion 800 made of ceramics or the like, and is also attached to the case body portion 810 together with the ground plate 820 attached to the back side of the holder portion 830. At this time, the vibrating film 740
Faces the sound hole 811 of the case body 810. In addition, the space 750 is provided in the back chamber 84 via the through hole 711.
It is communicated with 0.

[0015]

However, the above-mentioned conventional semiconductor electret condenser microphone has the following problems. That is, it is technically difficult to perform laser processing or ultrasonic processing of the through hole formed in the wafer portion of the microphone portion, which causes a cost increase. Further, it is necessary to provide a recess serving as a back chamber on the back side of the wafer portion, but this recess has also been an obstacle to making the semiconductor electret condenser microphone thinner.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a semiconductor electret condenser microphone in which it is not necessary to form a through hole in a wafer portion which causes a cost increase. Another object of the present invention is to provide a semiconductor electret condenser microphone that can be formed thinner than conventional ones.

[0017]

A semiconductor electret condenser microphone according to the present invention comprises a microphone section for outputting an input sound as an electric signal and a case section for accommodating the microphone section. Is a wafer portion on which an integrated circuit is formed, an electret layer laminated on the integrated circuit, and a vibrating film attached to a spacer and provided with a predetermined space between the electret layer and the electret layer. The case portion has a back chamber, the spacer is composed of a plurality of spacer pieces, and the space between the adjacent spacer pieces communicates with the space and the back chamber. It is a division.

Further, another semiconductor electret condenser microphone according to the present invention comprises a microphone section for outputting the input sound as an electric signal and a case section for accommodating the microphone section. A wafer part on which an integrated circuit is formed; an electret layer laminated on the integrated circuit; and a vibrating film attached to a spacer and having a predetermined space between the electret layer and the vibrating film. The case portion has a back chamber, and the wafer portion is formed with a communication groove for communicating the space with the back chamber.

[0019]

1 is a schematic sectional view of a semiconductor electret condenser microphone according to a first embodiment of the present invention, and FIG. 2 is a semiconductor electret condenser microphone according to the first embodiment of the present invention. FIG. 3 is a schematic explanatory view showing a manufacturing process of a microphone part used, FIG. 3 is a schematic perspective view of a case main body part of a case part used in the semiconductor electret condenser microphone according to the first embodiment of the present invention, and FIG. FIG. 5 is a schematic perspective view of a cap portion of a case portion used in the semiconductor electret condenser microphone according to the first embodiment of the present invention, and FIG. 5 shows a spacer of the semiconductor electret condenser microphone according to the first embodiment of the present invention. It is a schematic plan view.

FIG. 6 is a schematic sectional view of a semiconductor electret condenser microphone according to the second embodiment of the present invention, and FIG. 7 is used for the semiconductor electret condenser microphone according to the second embodiment of the present invention. FIG. 8 is a schematic perspective view of the case body of the case part, and FIG. 8 is a view of a wafer part that constitutes a microphone part used in the semiconductor electret condenser microphone according to the third embodiment of the present invention. ) Is a schematic plan view with spacers formed, FIG. 6B is a schematic side view without spacers, and FIG. 6C is a schematic view of part A of FIG. FIG.

A semiconductor electret condenser microphone according to the first embodiment of the present invention includes a microphone section 100 which outputs an input sound as an electric signal,
The microphone section 100 is provided with a case section 200 for accommodating the microphone section 100. The microphone section 100 includes a wafer section 110 on which an integrated circuit 120 is formed, and the integrated circuit 1
20 and the electret layer 131 laminated on the spacer 140 and attached to the spacer 140.
1 and the vibrating membrane 150 provided with a predetermined space 160 between the case portion 200 and the back chamber 21.
1 and the spacer 140 is composed of a plurality of spacer pieces 141.
Between 41, there is a communication part 142 that connects the space 160 and the back chamber 211, and the back chamber 211 is located below the microphone part 100 housed in the case part 200.

The manufacturing process of the microphone section 100 used in this semiconductor electret condenser microphone will be described with reference to FIG. In FIG. 2, the dimensions of each part are exaggerated for the sake of explanation. First, the wafer unit 110
Then, a large number of integrated circuits 120 including impedance conversion elements, amplification elements and the like are formed by using a photolithography technique or the like (see FIG. 2A). A silicon oxide film 130 is formed on the front surface side of the wafer portion 110, that is, on the side where the integrated circuit 120 is formed (see FIG. 2B). That is, the silicon oxide film 130 is laminated on the integrated circuit 120. Further, the silicon oxide film 130 is electretized by a method such as corona polarization or electron beam irradiation (EB polarization) to form an electret layer 131 (see FIG. 2C).

Next, the spacer 140 is formed on the electret layer 131 (see FIG. 2C). This spacer 140 is different from the conventional semiconductor electret condenser microphone. That is, the spacer 140 in the semiconductor electret condenser microphone according to the first embodiment of the present invention is composed of a plurality of spacer pieces 141.

The spacer piece 141 is, for example, as shown in FIG.
As shown in (A), the spacer 1 is formed in a substantially 1/4 circular arc shape, and four spacer pieces 141 are arranged in a circle to form the spacer 1.
40 make up. Therefore, adjacent spacer pieces 14
Between 1 and 1, there is a portion without the spacer piece 141, and this portion serves as the communication portion 142. Therefore, the four communicating portions 142 are formed on the spacer 140 at 90 ° intervals.

The communicating portion 142 is composed of the vibrating membrane 150 attached to the spacer 140 and the electret layer 1.
The space 160 between the space 31 and the outside is communicated with the outside. This communication part 142 is a through hole 711 (see FIG. 10) of the conventional semiconductor electret condenser microphone.
This is a part that performs an action substantially equivalent to.

The spacer 140 is formed of polyimide or the like having a thickness of 5 μm to 25 μm by printing or photolithography.

Further, the vibrating film 150 is attached to the spacer 140 (see FIG. 2D). An electrode film (not shown) is previously formed on the upper surface of the vibrating film 150. Then, a space 160 corresponding to the thickness of the spacer 140 is formed between the electret layer 131 and the vibrating film 150. A PPS film or the like is used as the vibrating film 150.

The wafer thus formed is divided by a dicing saw into a plurality of microphone parts 100 (see FIG. 2E).

On the other hand, the case section 200 has a case body section 210 made of ceramics and a cap section 220 attached to the case body section 210.

The case body 210 is made of ceramics, and a back chamber 211 is recessed in the center. A groove 212 that connects the back chamber 211 and the space 160 of the microphone unit 100 communicates with the back chamber 211.

Further, the case main body 210 is preliminarily formed by printing with an electrode portion 214 which comes into contact with an electrode portion (not shown) of the microphone portion 100. The electrode portion 214 is extended to the side surface portion of the case body 210.

Further, a substantially frame-shaped wall portion 213 made of ceramics is attached to the peripheral portion of the case main body 210. The height dimension of the wall portion 213 is set to be larger than the thickness dimension of the microphone portion 100 housed in the case body portion 210.

The case body 210 is set to be larger than the microphone unit 100. Therefore, when the microphone part 100 is placed on the case main body part 210, a gap is formed between the microphone part 100 and the wall part 213.

The cap portion 220 has a thin plate shape, and a sound hole 221 is formed in the center thereof. On the back surface side of the cap portion 220, a circular ridge portion 222 that contacts the spacer 140 of the microphone portion 100 with the sound hole 221 inside is formed.

A procedure for attaching the microphone section 100 to the case section 200 thus constructed will be described. First, the microphone unit 100 with the vibrating membrane 150 facing upward is placed on the case body 210. At that time, the electrode of the microphone unit 100 is brought into contact with the electrode unit 214 of the case body 210. Also, the microphone unit 1
00 to cover the back chamber 211. However, the back room 21
Since the groove portion 212 communicates with the back portion 1, the back chamber 211 is not sealed by the microphone portion 100.

When the cap portion 220 is attached to the case main body portion 210 to which the microphone portion 100 is attached in this manner, the ridge portion 222 becomes the vibrating membrane 150 and the spacer 14.
The space 230 between the vibrating membrane 150 and the cap portion 220 is sandwiched by the sound hole 221 and communicates with the outside through the sound hole 221. Further, the vibrating film 150 and the electret layer 13
1 is a space 240 between the cap portion 220 and the case body 210 via the communicating portion 142 formed between the spacer pieces 141 forming the spacer 140.
Communicate with.

Next, the operation of the semiconductor electret condenser microphone thus constructed will be described. A sound wave penetrates the space 230 between the rib 222 of the case 200 and the vibrating membrane 150 through the sound hole 221 (see arrow A in FIG. 1) to vibrate the vibrating membrane 150. Due to the vibration of the vibrating film 150, the volume of the space 160 between the vibrating film 150 and the electret layer 131 changes,
With this change, the vibration film 150 and the electret film 13
The capacitance between 1 and 1 changes. Then, the change in capacitance is output from the electrode unit 214 as a change in voltage.

Further, the pressure generated by the change in the capacity of the space 160 due to the vibration of the vibrating membrane 150 is transmitted from the communication part 142 between the spacer pieces 141 to the space 240 between the cap part 220 and the case body 210. (See arrow B in FIG. 1), and further reaches the back chamber 211 via the groove 212 (see arrow C in FIG. 1). As a result, the sound can be corrected.

In the embodiment described above, the spacer 140
Is composed of four spacer pieces 141 each having a substantially 1/4 arc shape, but may be of a type as shown in FIGS. 5 (B) to 5 (F).

That is, as shown in FIG. 5B, the spacer 140B is composed of a larger number of spacer pieces 141B (24 pieces in the drawing), and the space between adjacent spacer pieces 141B serves as a communication portion 142B. Then all communication parts 1
Since the opening area of 42B is large, the acoustic resistance is small.
The effect of becoming .

Further, as shown in FIG. 5C, the ends of four substantially quarter arc-shaped spacer pieces 141C are narrowed to form an elongated crescent moon, and the ends of the adjacent spacer pieces 141C are formed.
The parts are overlapped in the circumferential direction with a gap between the inside and the outside.
It is also possible to configure the spacer 140C as described above.
Is. That is, the spacer 140C is made to have a spiral shape. Then, there is an effect that the acoustic resistance is slightly higher than that shown in FIG.

Further, as shown in FIG. 5 (D), four spacer pieces 141D having an approximately 1/4 arc shape are provided and adjacent to each other.
The ends of the spacer piece 141D are circumferentially aligned with each other inward.
Spacer 140 so that it overlaps with the outside
It is also possible to construct D. In this case,
Unlike in the case of (C), both ends of each spacer piece 141D are not formed thin, but are formed obliquely.

On the other hand, as shown in FIG.
The spacer 140E may be a doubled spacer 140E of the type shown in FIG. In this case, the communication portion 142E1 between the adjacent spacer pieces 141E ₁ of the inner spacer 140E ₁ and the communication portion 142E ₂ between the adjacent spacer pieces 141E ₂ of the outer spacer 140E ₂ should not overlap. To do.

Further, as shown in FIG.
It may be a spacer 140F in which the spacer 140D of the type shown in (D) is doubled. In this case, the spacer piece and the communicating portion 142F ₂ between 141F _1, the communicating portion 142F ₂ between the spacer piece 141F ₂ adjacent the outer spacer 140F ₂ adjacent inner spacer 140F ₁
And do not overlap.

In particular, double spacers 140E and 140F as shown in FIGS. 5E and 5F, and a communicating portion 142 as shown in FIGS. 5C and 5D.
Spacers 140C and 1C in which C and 142D are formed obliquely
In 40D, when attaching the vibrating membrane 150, the vibrating membrane 15
There is an effect that the generation of wrinkles due to the imbalance of the tension applied to 0 can be suppressed.

Next, regarding the semiconductor electret condenser microphone according to the second embodiment of the present invention,
This will be described with reference to FIGS. 6 and 7. The semiconductor electret condenser microphone according to the second embodiment differs from that according to the first embodiment in the position of the back chamber 211. That is, in the first embodiment, the back chamber 211 is located below the microphone unit 100 housed in the case unit 200, whereas in the second embodiment, the back chamber 211 is located below the microphone unit 100. Case part 200
It is located on the side of the microphone unit 100 housed in.

Due to the difference in the configuration, each component is configured as follows. First, the microphone unit 100
It is the same as that used in the first embodiment.

The semiconductor electret condenser microphone according to the second embodiment is different from that according to the first embodiment in the case main body 210 of the case 200. That is, as shown in FIG. 6 and FIG. 7, the microphone unit 10 is used instead of the back chamber 211 in the first embodiment.
A recess 215 into which 0 is fitted is formed. An electrode portion 214 that contacts the electrode of the microphone portion 100 is formed in the recess 215. Further, unlike the back chamber 211 in the first embodiment, this recess 215 does not correspond to the groove 212.

The case main body 210 constructed in this way
The semiconductor electret condenser microphone according to the second embodiment having the above is configured as follows. That is, as shown in FIG.
It is located on the side of the microphone unit 100 housed in 0. That is, the portion that was the space 240 in the first embodiment becomes the back chamber 250 in the second embodiment. The space 160 between the vibrating membrane 150 and the electret layer 131 communicates with the back chamber 250 via the communication portion 142 between the spacer pieces 141.

With this structure, it is possible to make the structure thinner than the structure in which the back chamber 211 is formed below the microphone part 100 housed in the case part 200 (see FIG. 1).

Needless to say, the spacer 140 in the semiconductor electret condenser microphone according to the second embodiment can be selected from the types shown in FIGS. 5 (A) to 5 (F).

Next, a semiconductor electret condenser microphone according to the third embodiment will be described with reference to FIG. The semiconductor electret condenser microphone according to the third embodiment is different from those according to the first and second embodiments in that a space 160 between the electret layer 131 and the vibrating membrane 150 is provided in the back chamber 21.
1 and 250 are in communication with each other.

That is, in the first and second embodiments, the spacer 140 is composed of a plurality of spacer pieces 141, and the communication part 142 provided between the spacer pieces 141 allows the spacer 150 to be connected to the vibrating membrane 150. Electret layer 13
The space 160 between the back chamber 211 and the back chamber 211 communicates with the back chambers 211 and 250.

On the other hand, in the semiconductor electret condenser microphone according to the third embodiment, the spacer 140 is formed in a simple circle, and the portion corresponding to the communicating portion 142 is not formed. Further, it is the wafer unit 11 that connects the space 160 and the back chambers 211 and 250.
It is a communication groove 111 formed in 0.

The communication groove 111 is formed at the time of forming the integrated circuit 120 on the wafer portion 110 or before the formation of the integrated circuit 120. As shown in FIG. 8A, two communication grooves 111 are formed vertically and horizontally so as to be orthogonal to each other at the center of the wafer unit 110. The communication groove 111 is formed up to the edge of the wafer 110. The communication groove 111 is formed in a substantially V-shaped cross section.

The communicating groove 111 does not fill the recessed portion even if the electret layer 131 is formed. That is, the portion of the electret layer 131 is also recessed in a substantially V-shaped cross section.

When forming the circular spacer 140, if the spacer 140 does not fill the communication groove 111,
The inner side and the outer side of the spacer 140 are communicated by the communication groove 111. Particularly, the vibrating film 1 is attached to the spacer 140.
Even if 50 is attached, the inner side and the outer side of the spacer 140 are communicated by the communication groove 111.

The microphone unit 10 thus configured
When 0 is used, the electret layer 131 and the rolling film 150
The space 160 between and is communicated with the back chamber (not shown) through the communication groove 11.

[0059]

The semiconductor electret condenser microphone according to the first aspect of the present invention comprises a microphone section for outputting the input sound as an electric signal and a case section for accommodating the microphone section, and the microphone section is integrated. A wafer portion on which circuits are formed, an electret layer laminated on the integrated circuit, and a vibrating film attached to a spacer and provided with a predetermined space between the electret layer The case portion has a back chamber, the spacer is composed of a plurality of spacer pieces, and a space between the adjacent spacer pieces serves as a communication portion that communicates the space with the back chamber. ing.

Therefore, in this semiconductor electret condenser microphone, in order to connect the space between the electret layer and the vibrating membrane to the back chamber, a through hole is formed in the wafer portion constituting the microphone portion as in the conventional case. Since it is not necessary, the difficult process of forming the through hole is not required, and the cost can be reduced. Further, there is also an effect that a yield is improved because a difficult process is unnecessary.

Further, the spacer piece in the semiconductor electret condenser microphone according to claim 2 is
The spacer pieces are formed so as to partially overlap the adjacent spacer pieces. Therefore, the acoustic resistance is increased.

Further, in the semiconductor electret condenser microphone according to claim 2, the spacers are adjacent to each other.
The ends of the spacer pieces that are in contact with each other are
It is formed so as to be spaced apart from the side and overlap. Therefore, there is an effect that the acoustic resistance is further increased .

On the other hand, the back chamber of the semiconductor electret condenser microphone according to claim 4 is located below the microphone portion housed in the case portion.
Therefore, the back chamber can be formed to have the same size as the conventional one, so that there is a margin in acoustic correction.

The back chamber of the semiconductor electret condenser microphone according to the fifth aspect is located on the side of the microphone portion housed in the case portion.
Therefore, the case portion can be formed thinner than the type in which the back chamber is located below the microphone portion, so that the entire semiconductor electret condenser microphone can be made thin.

Further, a semiconductor electret condenser microphone according to a sixth aspect of the present invention comprises a microphone section for outputting the input sound as an electric signal and a case section for accommodating the microphone section, and the microphone section is integrated. A wafer portion on which circuits are formed, an electret layer laminated on the integrated circuit, and a vibrating film attached to a spacer and provided with a predetermined space between the electret layer The case portion has a back chamber, and the wafer portion is formed with a communication groove for communicating the space with the back chamber.

Therefore, since it is not necessary to divide the spacer into a plurality of spacer pieces, the spacer forming process is the same as the conventional one, and the cost can be reduced without complicating the process.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a semiconductor electret condenser microphone according to a first embodiment of the present invention.

FIG. 2 is a schematic explanatory view showing a manufacturing process of a microphone unit used in the semiconductor electret condenser microphone according to the first embodiment of the present invention.

FIG. 3 is a schematic perspective view of a case body portion of a case portion used in the semiconductor electret condenser microphone according to the first embodiment of the present invention.

FIG. 4 is a schematic perspective view of a cap portion of a case portion used in the semiconductor electret condenser microphone according to the first embodiment of the present invention.

FIG. 5 is a schematic plan view of a spacer of the semiconductor electret condenser microphone according to the first embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view of a semiconductor electret condenser microphone according to a second embodiment of the present invention.

FIG. 7 is a schematic perspective view of a case body portion of a case portion used in the semiconductor electret condenser microphone according to the second embodiment of the present invention.

FIG. 8 is a drawing of a wafer section that constitutes a microphone section used in a semiconductor electret condenser microphone according to a third embodiment of the present invention, and is a drawing of the same figure (A).
Is a schematic plan view with spacers formed, FIG. 6B is a schematic side view with spacers not formed, and FIG. 6C is a schematic enlargement of part A of FIG. It is a figure.

FIG. 9 is a schematic sectional view of a conventional electret condenser microphone.

FIG. 10 is a schematic sectional view of a conventional semiconductor electret condenser microphone.

[Explanation of symbols]

100 microphone section 140 spacer 141 spacer piece 142 Communication part 150 vibrating membrane 200 case 211 back room

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Sugimori 1-3-4 Kitakuhoji Temple, Yao City, Osaka Prefecture Hosiden Co., Ltd. Incorporated (56) References JP-A-48-61127 (JP, A) Jikken-Sho 16-16707 (JP, Y1) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04R 19/01

Claims (6)

(57) [Claims] 1. A microphone section for outputting input sound as an electric signal and a case section for accommodating the microphone section, wherein the microphone section includes a wafer section on which an integrated circuit is formed, and Attached to the electret layer laminated on the integrated circuit and the spacer,
And a vibrating film provided with a predetermined space between the electret layer, the case portion has a back chamber, the spacer is composed of a plurality of spacer pieces. The semiconductor electret condenser microphone is characterized in that a communication portion that communicates the space and the back chamber is provided between the adjacent spacer pieces. 2. The spacer pieces are adjacent spacer pieces.
The ends of the are circumferentially spaced on the inside and outside
It is formed so as to overlap with each other.
1. The semiconductor electret condenser microphone according to 1. 3. The semiconductor electret condenser microphone according to claim 1, wherein the spacer is formed in double or more. 4. The semiconductor electret condenser microphone according to claim 1, wherein the back chamber is located below a microphone section housed in a case section. 5. The semiconductor electret condenser microphone according to claim 1, 2 or 3, wherein the back chamber is located on a side of a microphone portion housed in a case portion. 6. A microphone section for outputting the input sound as an electric signal and a case section for accommodating the microphone section, wherein the microphone section includes a wafer section on which an integrated circuit is formed, and Attached to the electret layer laminated on the integrated circuit and the spacer,
And a vibrating film provided with a predetermined space between the electret layer, the case portion has a back chamber, the wafer portion has the space and the back chamber. A semiconductor electret condenser microphone having a communication groove formed therein.