JP2008010961A - Sound response device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound response device having a small capacitor of stabilized performance and exhibiting good consistency with the manufacturing process of semiconductor device. <P>SOLUTION: A capacitor comprises a fixed electrode film 12 formed on a substrate 11, a vibration electrode film 14 formed through a first interlayer insulating film 13 deposited on the fixed electrode film 12, and a hollow section 15 formed between the fixed electrode film 12 and the vibration electrode film 14 in the first interlayer insulating film 13. A second interlayer insulating film 16 covering the vibration electrode film 14 is formed on the first interlayer insulating film 13, and the hollow section 15 is formed by etching a sacrifice layer buried in the first interlayer insulating film 13. A through hole 17 communicating with the peripheral edge portion of the sacrifice layer is made through the first and second interlayer insulating films 13 and 16, and a tensile stress film 18 having the peripheral edge formed to extend near an etching material introduction hole 17 is arranged in the second interlayer insulating film 16. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an acoustic device including a capacitor having an air gap structure formed integrally with a semiconductor substrate.

  A structure as shown in FIG. 10 is known as an acoustic device including a capacitor (for example, a condenser microphone) having an air gap structure formed on a conventional semiconductor substrate (see, for example, Patent Document 1).

  As shown in FIG. 10, a vibrating electrode film 102 made of a part of a polycrystalline silicon film formed on a silicon substrate 101 and a spacer 104 made of a silicon oxide film are formed on the vibrating electrode film 102 via a spacer 104. The fixed electrode film 103 made of the polycrystalline silicon film constitutes a capacitor. The function of the microphone is achieved by electrically taking out the change in the capacitance of the capacitor when the vibrating electrode film 102 vibrates in response to the sound pressure.

  Note that a hollow portion (air gap) 108 formed between the vibrating electrode film 102 and the fixed electrode film 103 is a sacrificial layer made of the silicon oxide film 104 formed on the vibrating electrode film 102. It is formed by supplying an etching solution through a plurality of through holes 105 formed in the etching process and etching. The back surface of the vibrating electrode film 102 is exposed by selectively etching the silicon substrate 101 from the back surface side to form the opening 109.

  However, in the capacitor having the structure shown in FIG. 10, it is necessary to deep-etch the silicon substrate 101 from the back side in order to form the opening 109, and it is difficult to align with the hollow portion 108, and the vibrating electrode film Etching control is required so that film thickness reduction of 102 does not occur. In addition, since deep etching from the back side is required, the width of the opening 109 becomes large, which is not suitable for downsizing of the capacitor.

  Patent Document 2 describes a capacitor (capacitance sensor) having an air gap structure that does not require deep etching from the back side.

  11A to 11D are process cross-sectional views illustrating a method for manufacturing a capacitor described in Patent Document 2. FIG. Note that the drawings and reference numerals are modified from those described in Patent Document 2 for convenience of explanation.

  First, as shown in FIG. 11A, impurities are diffused on the surface of the silicon substrate 201 to form a fixed electrode 202 made of a diffusion layer.

  Next, as shown in FIG. 11B, after a silicon oxide film is formed on the fixed electrode 202, patterning is performed to form a sacrificial layer 203 that defines a hollow portion. Subsequently, a first interlayer insulating film 204 made of a silicon nitride film is deposited on the silicon substrate 201 so as to cover the sacrificial layer 203.

  Next, as shown in FIG. 11C, after a polycrystalline silicon film is formed on the first interlayer insulating film 204, patterning is performed to form a vibrating electrode film 205 made of the polycrystalline silicon film. Subsequently, a second interlayer insulating film 206 made of a silicon nitride film is deposited on the first interlayer insulating film 204 so as to cover the vibrating electrode film 205, and then the second interlayer insulating film 206, The vibration electrode film 205 and a part of the first interlayer insulating film 204 are etched to form a through hole 207 that communicates with the sacrificial layer 203.

Next, as shown in FIG. 11D, an etching solution capable of selectively etching the silicon oxide film constituting the sacrificial layer 203 is supplied from the through hole 207 to remove the sacrificial layer 203 by etching. A portion 208 is formed. Thereby, a capacitor having an air gap structure can be obtained without deep etching from the back side of the silicon substrate 201.
JP 2004-356708 A JP 2002-250665 A Special Table 2002-518913

  The capacitor described in Patent Document 2 is useful in that a smaller capacitor can be manufactured at a low cost because deep etching from the back side of the silicon substrate is not necessary. There is a problem like this.

  That is, the hollow portion 208 is formed by etching away the sacrificial layer 203 with an etching solution supplied through the through hole 207. At this time, the first interlayer insulating film 204 in contact with the through hole 207, the vibration electrode It is necessary that the film 205 and the second interlayer insulating film 206 are not etched. That is, for these films 204, 205, and 206, a material having a large etching selectivity with respect to the sacrificial layer 203 must be selected.

  In the manufacturing method described in Patent Document 2, the sacrificial layer 203 is made of a silicon oxide film, and the vibrating electrode film 205 and the first and second interlayer insulating films 204 and 206 are a polycrystalline silicon film and a silicon nitride film. Therefore, when an etchant such as hydrofluoric acid is used, there is no problem because the etching selectivity can be sufficiently high.

  However, when wet etching is used for etching removal of the sacrificial layer 203, stress is applied to the inside of the etching solution so as to make the surface as small as possible due to the surface tension of the etching solution. Therefore, when the etching solution is in a state where the minute gap is straddled, there arises a problem that the gap of the hollow portion 208 becomes narrow.

  On the other hand, when a capacitor is formed on the silicon substrate 201, if a detection circuit for detecting the output signal of the capacitor can be simultaneously formed on the silicon substrate 201, it is very useful for realizing a small acoustic device. is there. In this case, it is preferable that the manufacturing process of the capacitor has good consistency with the manufacturing process of the detection circuit, that is, the manufacturing process of the semiconductor device. For this purpose, a technique for etching and removing the sacrificial layer 203 by dry etching is required. In addition, since the silicon nitride film has a large internal stress, it is not suitable for use as an interlayer insulating film in a semiconductor device. Therefore, it is required to use a silicon oxide film as an interlayer insulating film in a capacitor.

  From this point of view, when a silicon oxide film is used as the sacrificial layer 203 in order to obtain consistency with the manufacturing process of the semiconductor device, first, the silicon oxide film cannot be used as the interlayer insulating film, and the second In addition, the etching selectivity between the silicon oxide film as the sacrificial layer 203, the polycrystalline silicon film (vibrating electrode film 205), and the silicon nitride films (interlayer insulating films 204 and 206) cannot be sufficiently increased. Occurs.

  The present invention has been made in view of the above points, and a main object of the present invention is to provide an acoustic response device including a small capacitor having a stable performance, which is consistent with a manufacturing process of a semiconductor device. .

  In order to achieve the above object, the present inventors have examined the use of a polycrystalline silicon film as a sacrificial layer. In this case, since a polycrystalline silicon film is also used for the vibrating electrode film, a method of forming a through hole in the vibrating electrode film and removing the sacrificial layer by etching as shown in FIG. This is because when the sacrificial layer is etched, the vibrating electrode film in contact with the through hole is also etched.

  Therefore, a method was considered in which a through-hole leading to the sacrificial layer was formed at a position away from the vibrating electrode film without providing a through-hole in the vibrating electrode film. The method will be described below with reference to FIGS. 1 (a) and 1 (b).

  FIG. 1A is a cross-sectional view taken along a line Ia-Ia in the plan view of the capacitor shown in FIG. A fixed electrode 12 made of a diffusion layer is formed on the surface of the silicon substrate 11, and a sacrificial layer 19 made of a polycrystalline silicon film is formed thereon. The sacrificial layer 19 is covered with the first interlayer insulating film 13, and the vibration electrode film 14 made of a polycrystalline silicon film is formed thereon. The vibrating electrode film 14 is covered with the second interlayer insulating film 16, and a through hole 17 that communicates with the sacrificial layer 19 is formed in the first and second interlayer insulating films 13 and 16 at a position away from the vibrating electrode film 14. Is formed. Since the sacrificial layer 19 is composed of a polycrystalline silicon film, silicon oxide films can be used for the first and second interlayer insulating films 13 and 16. Then, the hollow portion is formed by supplying the etching gas from the through-hole 17 and dry-etching the sacrificial layer 19.

  In this method, since the through hole 17 is formed at a position away from the vibrating electrode film 14, the sacrificial layer 19 must be formed larger than the vibrating electrode film 14. However, in reality, since the region required as the hollow portion is only the region located below the vibrating electrode film 14, the sacrificial layer 19 has a planar shape as shown in FIG. Preferably, the region 15 is a region 15 and the region 20 is a communication hole that communicates with the region 15. Here, the region 20 serving as the communication hole extends in a cross shape from each side of the region 15 serving as the hollow portion, and is connected to the through hole 17 at the end portion.

  FIG. 2 shows a cross-sectional view of the capacitor after the sacrificial layer 19 has been etched away. The through-hole 17 formed in the first and second interlayer insulating films 13 and 16 communicates with the hollow portion 15 through the communication hole region 20.

  Here, when the gap of the hollow portion becomes narrow, the following problem occurs. That is, if the first interlayer insulating film 13 above the region 20 is loosened as the region 20 serving as the communication hole of the sacrificial layer 19 is etched, a part of the communication hole 20 may be blocked.

  Further, in order to adjust the tension of the vibrating electrode film 14, a silicon nitride film or the like is laminated on the vibrating electrode film 14 (see, for example, Patent Document 3), but the silicon nitride film has a tensile stress. Therefore, the effect of preventing the slack of the first interlayer insulating film 13 is also achieved. However, as shown in FIG. 2, the through-hole 17 is formed at a position separated from the vibrating electrode film 14, and thus effectively prevents the first interlayer insulating film 13 located above the communication hole 20 from loosening. It is not possible.

  Therefore, in the step of removing the sacrificial layer 19 by etching, if the first interlayer insulating film 13 is loosened and a part of the communication hole 20 is blocked, it becomes difficult to introduce the etching gas. As a result, the sacrificial layer The etching time of 19 will become long, and the problem that the etching of the hollow part 15 becomes incomplete will be caused.

  In order to solve the above problem, the present invention employs a configuration in which a tensile stress film having a peripheral edge extending to the vicinity of the through hole 17 is embedded in the second interlayer insulating film 16 above the hollow portion 15. did. That is, by forming the tensile stress film not only in the hollow portion 15 but also above the first interlayer insulating film 13 on the region including the communication hole 20, the tensile stress film is positioned above the hollow portion 15 and the communication hole 20. A tensile stress can be exerted on the first interlayer insulating film 13, thereby preventing loosening of the first interlayer insulating film 13.

  An acoustic device according to the present invention includes a fixed electrode film formed on a semiconductor substrate, a vibration electrode film formed via a first interlayer insulating film deposited on the fixed electrode film, and a first interlayer A second interlayer that covers a vibrating electrode film on a first interlayer insulating film, comprising a capacitor comprising a hollow portion formed in a portion located between the fixed electrode film and the vibrating electrode film of the insulating film An insulating film is formed, and the hollow portion is formed by etching away a sacrificial layer embedded in the first interlayer insulating film. An etching material introduction hole leading to the peripheral portion of the sacrificial layer is formed in the first interlayer insulating film and the second interlayer insulating film, and is located above the hollow portion in the second interlayer insulating film. A tensile stress film having a peripheral edge extending to the vicinity of the etching material introduction hole is provided.

  With such a configuration, it is possible to form a capacitor with no geometric distortion in the hollow part, and realize an acoustic device with a small capacitor with stable performance that is consistent with the manufacturing process of the semiconductor device. can do.

  In the above configuration, the tensile stress film is preferably formed in contact with the upper surface of the first interlayer insulating film. Thereby, a tensile stress can be directly applied to the first interlayer insulating film, and loosening of the first interlayer insulating film can be effectively prevented.

  The tensile stress film is preferably formed in contact with the lower surface of the vibrating electrode film. Thereby, the tension strength of the vibrating electrode film can also be increased.

  The following configuration is preferable as an embodiment that further exhibits the effects of the present invention.

  The area of the tensile stress film is larger than the area of the vibrating electrode film, and the tensile stress film is made of a silicon nitride film.

  The sacrificial layer is made of the same material as the vibrating electrode film, and the sacrificial layer and the vibrating electrode film are made of polycrystalline silicon.

  The semiconductor substrate further includes a detection circuit that detects an output signal of the capacitor that has fluctuated due to vibration of the vibrating electrode film.

  According to the acoustic device according to the present invention, it is possible to prevent the geometric distortion of the hollow portion formed by etching away the sacrificial layer, and to have a stable performance that is consistent with the manufacturing process of the semiconductor device. It is possible to realize an acoustic sensing device including a small capacitor having

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, components having substantially the same function are denoted by the same reference numerals for the sake of simplicity. In addition, this invention is not limited to the following embodiment.

(First embodiment)
FIG. 3 is a cross-sectional view schematically showing a configuration of the acoustic sensing device 10 including a capacitor (for example, a condenser microphone) according to the first embodiment of the present invention.

  As shown in FIG. 3, the capacitor according to the present invention is formed through a fixed electrode film 12 formed on the semiconductor substrate 11 and a first interlayer insulating film 13 deposited on the fixed electrode film 12. The vibrating electrode film 14 and a hollow portion 15 formed in a portion located between the fixed electrode film 12 and the vibrating electrode film 14 of the first interlayer insulating film 13 are configured.

  A second interlayer insulating film 16 that covers the vibrating electrode film 14 is formed on the first interlayer insulating film 13, and the hollow portion 15 is a sacrificial layer embedded in the first interlayer insulating film 13. (Not shown) is formed by etching away. Further, in the first interlayer insulating film 13 and the second interlayer insulating film 16, a through hole (etching material introduction hole) 17 leading to the peripheral edge of the sacrificial layer is formed, and the second interlayer insulating film 16 is formed. Inside, a tensile stress film 18 is disposed above the hollow portion 15 and has a peripheral edge extending to the vicinity of the etching material introduction hole 17.

  As shown in FIG. 3, the periphery of the vibrating electrode film 14 is formed sufficiently away from the through hole 17 so that the vibrating electrode film 14 is not etched when the sacrificial layer is etched away. The tensile stress film 18 formed above the hollow portion 15 is formed such that its peripheral edge extends to the vicinity of the through hole 17.

  That is, the tensile stress film 18 also extends above the portion of the first interlayer insulating film 13 (region A surrounded by a circle in the drawing) on the communication hole 20 that connects the through hole 17 and the hollow portion 15. Is formed. Thereby, not only the hollow portion 15 but also the first interlayer insulating film 13 positioned above the communication hole 20 is subjected to a tensile stress by the tensile stress film 18, so that the communication hole is removed when the sacrificial layer is removed by etching. A phenomenon that a part of the communication hole 20 is blocked by the loosening of the first interlayer insulating film 13 on 20 can be prevented. As a result, it is possible to prevent the shape distortion of the hollow portion 15 due to incomplete etching removal of the hollow portion 15.

  Hereinafter, a specific configuration of the present embodiment will be described in detail with reference to FIG.

  FIG. 3 is a cross-sectional view showing the basic configuration of the capacitor according to the present invention. An insulating film (for example, a silicon oxide film) 21 is formed on a semiconductor substrate (for example, a silicon substrate) 11, and a fixed electrode film 12 made of, for example, a polycrystalline silicon film is formed thereon. A hollow portion 15 is formed on the fixed electrode film 12 via an insulating film (for example, a silicon oxide film) 22. The hollow portion 15 is etched together with the communication hole 20 connected thereto, and a sacrificial layer (not shown) formed on the fixed electrode film 12 and embedded in the first interlayer insulating film 13 made of, for example, a silicon oxide film is etched. It is formed by removing. Here, the height of the gap of the hollow portion is set to about 500 nm to 1000 nm. The communication hole 20 is formed to extend in a cross shape from each side of the hollow portion 15 as shown in FIG.

  A vibrating electrode film 14 made of, for example, a polycrystalline silicon film is formed on the first interlayer insulating film 13, and the vibrating electrode film 14 is covered with a second interlayer insulating film 16 made of, for example, a silicon oxide film. ing. A through-hole 17 is formed in the first interlayer insulating film 13 and the second interlayer insulating film 16 so as to communicate with the terminal portion of the communication hole 20. In the second interlayer insulating film 16, for example, silicon A tensile stress film 18 made of a nitride film is formed. Here, the film thickness of the tensile stress film 18 is formed to about 50 nm to 100 nm.

  In the present embodiment, the tensile stress film 18 is formed in contact with the upper surface of the first interlayer insulating film 13 and is further formed in contact with the lower surface of the vibrating electrode film 14. Further, the tensile stress film 18 is formed to have a larger area than the vibrating electrode film 14, and its peripheral edge extends to the vicinity of the through hole 17.

  Thereby, since the tensile stress by the tensile stress film 18 is directly applied to the first interlayer insulating film 13 located above the communication hole 20, the first interlayer insulating film 13 is effectively loosened. Can be prevented. In addition, since the tensile stress by the tensile stress film 18 is applied to the vibrating electrode film 14, the tensile strength of the vibrating electrode film 14 can be increased.

  By the way, the arrangement of the tensile stress film 18 is not limited to the place as shown in FIG. 3, but can be arranged at various places within the range where the effects of the present invention can be achieved. Hereinafter, these modifications will be described with reference to FIGS.

  FIG. 4 is a cross-sectional view showing a first modification of the present embodiment, which is different in that the peripheral edge of the tensile stress film 18 is further extended beyond the through hole 17. By forming the tensile stress film 18 in this way, the tensile stress by the tensile stress film 18 can be applied to the entire region of the first interlayer insulating film 13 located above the communication hole 20. The slack of one interlayer insulating film 13 can be prevented more effectively. In this case, the through-hole 17 needs to be formed so as to penetrate the tensile stress film 18 as well, but the tensile stress film 18 has a film thickness of the first interlayer insulating film 13 and the second interlayer insulating film 16. Since it is sufficiently thin as compared with the film thickness, the formation of the through-hole 17 is not hindered.

  In this modification, since the tensile stress film 18 is in contact with the through-hole 17, in the step of etching away a sacrificial layer, which will be described later, the etching is performed under an etching condition with a high etching selectivity between the tensile stress film 18 and the sacrificial layer. It is preferable.

  FIG. 5 is a cross-sectional view showing a second modification of the present embodiment, which differs in that the vibrating electrode film 14 is formed at a position separated from the tensile stress film 18. As described above, the tensile stress film 18 also acts to increase the tensile strength of the vibration electrode film 14, but the optimum film thickness and area of the tensile stress film 18 are determined regardless of the vibration electrode film 14. However, the desired tension strength is not necessarily given to the vibrating electrode film 14. Therefore, the vibrating electrode film 14 is formed separately from the tensile stress film 18, and a tensile stress film (not shown) that gives the vibrating electrode film 14 a desired tension height is separately formed on the vibrating electrode film 14. It is.

  FIG. 6 is a cross-sectional view showing a third modification of the present embodiment, which differs in that a tensile stress film 18 is formed in contact with the upper surface of the vibrating electrode film 14. In the present invention, the tensile stress film 18 does not necessarily have to be formed in contact with the upper surface of the first interlayer insulating film 13, and the tensile stress of the tensile stress film 18 may be transmitted through the second interlayer insulating film 16. The first interlayer insulating film 13 can be affected. On the other hand, in order to increase the capacitance of the capacitor, there is a request to make the distance between the fixed electrode film 12 and the vibrating electrode film 14 as small as possible, and this modification satisfies the request.

  FIG. 7 is a cross-sectional view showing a fourth modification of the present embodiment, which differs in that tensile stress films (for example, silicon nitride films) 23 and 24 are further formed on the upper surface and side surfaces of the vibrating electrode film 14. With this configuration, the tensile strength of the vibrating electrode film 14 can be increased, and all surfaces of the vibrating electrode film 14 are covered with the tensile stress films 18, 23, and 24, so that the sacrificial layer is etched. At the time of removal, part of the second interlayer insulating film 16 that protects the vibrating electrode film 14 is etched, thereby preventing the vibrating electrode film 14 from being etched.

(Second Embodiment)
A method for manufacturing an acoustic device having a capacitor according to the present invention will be described with reference to process cross-sectional views shown in FIGS. 8 (a) to 9 (b). In this embodiment, in addition to the capacitor according to the present invention, an acoustic sensing device in which a detection circuit (configured by a MOSFET) for detecting the output signal of the capacitor that has fluctuated due to vibration of the vibrating electrode film is integrated on a semiconductor substrate is taken as an example. Explained.

  First, as shown in FIG. 8A, a silicon oxide film is selectively formed on the surface of the silicon substrate 11 to form an element isolation region 21. Subsequently, after forming a gate insulating film on the silicon substrate 11, a polycrystalline silicon film is deposited, and the gate electrode film 30 and the element isolation region 21 are formed on the gate insulating film by using a lithography method and a dry etching method. The fixed electrode film 12 is formed. Subsequently, ion implantation is performed on the surface of the silicon substrate 11 using the gate electrode film 30 as a mask to form source / drain diffusion layers 31a and 31b. Thereafter, a silicon oxide film 22 is deposited on the silicon substrate 11 by using a plasma CVD method, and a sacrificial layer for forming the hollow portion 15 is further formed thereon by using the CVD method, for example, a polycrystalline silicon film 19. Form.

  Next, as shown in FIG. 8B, the sacrificial layer 19 is processed into a shape corresponding to the hollow portion 15 and the communication hole 20 by using a lithography method and a dry etching method. Subsequently, after a silicon oxide film (first interlayer insulating film) 13 is formed so as to completely cover the sacrificial layer 19 by using the CVD method, an etch back method or a chemical mechanical polishing (CMP) method is used. Then, the surface of the silicon oxide film 13 is planarized. Thereafter, a tensile stress film 18 made of a silicon nitride film is formed on the silicon oxide film 13 by using the CVD method. Subsequently, the vibrating electrode film 14 and the silicon nitride film 23 made of a polycrystalline silicon film are laminated on the tensile stress film 18 by using the CVD method. At this time, the area of the tensile stress film 18 is formed larger than the area of the vibrating electrode film 14.

  Next, as shown in FIG. 8C, a silicon oxide film 16 (second interlayer insulating film) is formed on the silicon oxide film 13 so as to cover the vibrating electrode film 14 by using the CVD method. Thereafter, the surface of the silicon oxide film 16 is planarized using an etch back method or a CMP method. Subsequently, contact holes are formed in the silicon oxide films 13 and 16 by using a lithography method and a dry etching method. Then, after depositing a conductor film made of titanium and tungsten including the inside of the contact hole using a sputtering method or a CVD method, the conductor film is embedded in the contact hole using an etch back method or a CMP method, Vias 40, 41, and 42 connected to the fixed electrode film 12, the vibrating electrode film 14, the gate electrode 30 of the MOSFET, and the like are formed.

  Next, as shown in FIG. 9A, after depositing a laminated film made of titanium, titanium nitride, and aluminum on the silicon oxide film 16 by using a sputtering method, using a lithography method and a dry etching method, Electrode wiring 43 is formed. Subsequently, after depositing a protective film 44 made of a silicon nitride film on the electrode wiring 43 by using the CVD method, the surface of the predetermined electrode pad is exposed by using the lithography method and the dry etching method. A part of the film 44 is removed.

  Next, as shown in FIG. 9B, a through hole 17 that communicates with the sacrificial layer 19 is formed in the silicon oxide films 13 and 16 and the protective film 44 by using a lithography method and a dry etching method. Subsequently, fluorine trichloride or xenon fluoride gas is introduced from the through hole 17 to remove the polycrystalline silicon film constituting the sacrificial layer 19, thereby forming the hollow portion 15 and the communication hole 20. The provided acoustic sensing device 10 is completed.

  As mentioned above, although this invention was demonstrated by suitable embodiment, such description is not a limitation matter and of course various modifications are possible.

  For example, in the present invention, when the sacrificial layer and the vibrating electrode film are made of the same material (for example, a polycrystalline silicon film), the through-hole leading to the sacrificial layer is necessarily positioned away from the vibrating electrode film. However, the present invention is not necessarily limited to such a case. Even if the sacrificial layer and the vibrating electrode film are made of different materials and there are no restrictions on forming a through hole in the vibrating electrode film, the vibration characteristics of the vibrating electrode film are degraded by providing the through hole in the vibrating electrode film. In order to avoid such a problem as described above, the present invention can also be applied to the case where the through hole is not provided in the vibrating electrode film and the through hole is formed at a position away from the moving electrode film.

  In the present embodiment, the fixed electrode film is formed of a polycrystalline polysilicon film formed on the semiconductor substrate. However, the present invention is not limited to this, for example, a diffusion layer formed on the surface of the semiconductor substrate. You may make it comprise.

  In this embodiment, the hollow portion is formed by removing the sacrificial layer by dry etching. However, the hollow portion may be formed by removing the sacrificial layer by wet etching.

  Furthermore, in the present embodiment, the condenser microphone is exemplified as the condenser. However, the present invention is not limited to this, and can be applied to devices such as a pressure sensor and an acceleration sensor.

  According to the sound sensitive device according to the present invention, it is possible to provide a sound sensitive device including a small capacitor having a stable performance that is consistent with the manufacturing process of the semiconductor device.

BRIEF DESCRIPTION OF THE DRAWINGS It is the figure which showed the general structure of the capacitor | condenser in this invention, (a) is sectional drawing of a capacitor | condenser, (b) is a top view of a capacitor | condenser. It is a figure explaining the subject of the capacitor in the present invention. It is sectional drawing which showed typically the structure of the acoustic response apparatus in the 1st Embodiment of this invention. It is sectional drawing which showed the 1st modification in the 1st Embodiment of this invention. It is sectional drawing which showed the 2nd modification in the 1st Embodiment of this invention. It is sectional drawing which showed the 3rd modification in the 1st Embodiment of this invention. It is sectional drawing which showed the 4th modification in the 1st Embodiment of this invention. (A)-(c) is process sectional drawing which showed the manufacturing method of the acoustic response apparatus in the 2nd Embodiment of this invention. (A)-(b) is process sectional drawing which showed the manufacturing method of the acoustic response apparatus in the 2nd Embodiment of this invention. It is sectional drawing which showed the structure of the capacitor | condenser with the conventional air gap structure. (A)-(d) is process sectional drawing which showed the manufacturing method of the capacitor | condenser with the conventional air gap structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Acoustic sensitive apparatus 11 Semiconductor substrate 12 Fixed electrode film 13 1st interlayer insulation film 14 Vibrating electrode film 15 Hollow part 16 2nd interlayer insulation film 17 Through-hole (etching material introduction hole)
18 Tensile stress film (silicon nitride film)
19 Sacrificial layer (polycrystalline silicon film)
20 communication hole 21 element isolation region 23, 24 tensile stress film (silicon nitride film)
31a, 31b Drain diffusion layer 40, 41, 42 Via 43 Electrode wiring 44 Protective film

Claims (9)

A fixed electrode film formed on a semiconductor substrate;
A vibrating electrode film formed through a first interlayer insulating film deposited on the fixed electrode film;
An acoustic sensing device including a capacitor including a hollow portion formed in a portion located between the fixed electrode film and the vibrating electrode film in the first interlayer insulating film,
A second interlayer insulating film covering the vibrating electrode film is formed on the first interlayer insulating film;
The hollow portion is formed by etching away a sacrificial layer embedded in the first interlayer insulating film,
In the first interlayer insulating film and the second interlayer insulating film, an etching material introduction hole leading to a peripheral portion of the sacrificial layer is formed,
The second interlayer insulating film is provided with a tensile stress film formed above the hollow portion and having a peripheral edge extending to the vicinity of the etching material introduction hole. , Sound sensitive device.   The acoustic sensitive device according to claim 1, wherein the tensile stress film is formed in contact with an upper surface of the first interlayer insulating film.   The acoustic sensing device according to claim 1, wherein the tensile stress film is formed in contact with a lower surface of the vibrating electrode film.   The acoustic device according to claim 3, wherein an area of the tensile stress film is larger than an area of the vibrating electrode film.   The acoustic device according to claim 1, wherein the tensile stress film is made of a silicon nitride film.   The acoustic device according to claim 1, wherein the sacrificial layer is made of the same material as the vibrating electrode film.   The acoustic sensing device according to claim 6, wherein the sacrificial layer and the vibrating electrode film are made of a polycrystalline silicon film.   The acoustic sensing apparatus according to claim 1, wherein a detection circuit that detects an output signal of the capacitor that is fluctuated due to vibration of the vibrating electrode film is further formed on the semiconductor substrate.   The sound sensitive device according to claim 1 or 8, wherein the sound sensitive device is a condenser microphone.

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