JP2009164851A - Mems transducer and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect an electrode of a MEMS transducer without hindering mechanical functions of the MEMS transducer. <P>SOLUTION: The MEMS transducer includes: a conductive diaphragm; a conductive plate; a support part which supports the diaphragm and the plate via an air gap layer and has an inner wall surrounding the gap layer; a conductive electrode film which covers a contact hole formed in the support part; and a protection film which is formed on the support part on the outside of the inner wall to cover the side of the electrode film. An electric signal corresponding to electrostatic capacity formed by the diaphragm and the plate is output through the electrode film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a MEMS (Micro Electro Mechanical Systems) transducer, and more particularly to a vibration transducer such as a minute condenser microphone as a MEMS sensor, a pressure sensor, an acceleration sensor, and the like.

  Conventionally, a minute condenser microphone manufactured by applying a manufacturing process of a semiconductor device is known (see Non-Patent Document 1, Patent Documents 1, 2, and 3). Such a condenser microphone is called a MEMS microphone, and the diaphragm and the plate constituting the counter electrode are made of a thin film and are supported on the substrate in a state of being separated from each other. When the diaphragm vibrates with respect to the plate by the sound wave, the capacitance of the capacitor changes due to the displacement, and the capacitance change is converted into an electric signal. The surface of a MEMS transducer such as a condenser microphone is covered with a protective film, and electrodes are exposed from through holes formed in the protective film. The protective film is insulative and protects the MEMS transducer from chemical corrosion and physical damage caused by water, oxygen, and sodium.

The Institute of Electrical Engineers of Japan MSS-01-34 JP 9-508777 A US Patent No. 4776019 Special table 2004-506394

  However, a large stress is generated in the deposited film made of nitride, nitrogen oxide or the like deposited on the silicon substrate or silicon oxide film due to the difference in thermal expansion coefficient. Therefore, when nitride, nitrogen oxide, or the like is used for the protective film, there is a problem in that the MEMS transducer which is a mechanical structure is distorted and the mechanical function of the MEMS transducer is hindered.

  The present invention was created to solve this problem, and an object of the present invention is to protect the electrodes of the MEMS transducer without hindering the mechanical function of the MEMS transducer.

(1) A MEMS transducer for achieving the above object supports a diaphragm and a plate with a conductive diaphragm, a conductive plate, and a gap layer sandwiched between the diaphragm and the plate. A support portion having an inner wall surrounding the support portion, a conductive electrode film covering a contact hole formed in the support portion, and a protective film formed on the support portion outside the inner wall and covering a side surface of the electrode film. An electrical signal corresponding to the capacitance formed by the diaphragm and the plate is output through the electrode film.
According to the present invention, since the protective film is formed outside the inner wall of the support portion, the plate or the diaphragm is not distorted by the film stress of the protective film acting directly. Therefore, the protective film can be formed of a material that increases the film stress. On the other hand, the side surface constituting the contour of the electrode film is activated by processing such as etching, or chemical species such as chlorine and fluorine remain, resulting in low chemical stability. According to the present invention, the side surface of the electrode film having low chemical stability can be covered with a material having high performance as a protective film regardless of the magnitude of the film stress. Therefore, according to the present invention, the electrode film can be protected without hindering the mechanical function of the MEMS transducer.

  (2) In the MEMS transducer for achieving the above object, silicon nitride or silicon nitride oxide can be used as a material for the protective film.

(3) In the MEMS transducer for achieving the above object, the support portion has a multilayer structure including a silicon substrate and a silicon oxide film bonded to a region excluding the outer edge portion of the silicon substrate. The region spanning the outer edge of the silicon substrate and the outer edge of the silicon oxide film may be covered.
By covering the region spanning the outer edge of the silicon substrate and the outer edge of the silicon oxide film with a protective film made of silicon nitride or silicon nitride oxide, mobile ions enter from the edge of the joint surface between the silicon substrate and the silicon oxide film. Can be prevented.

(4) In the MEMS transducer manufacturing method for achieving the above object, a contact hole is formed in a support portion having an inner wall surrounding the gap layer while supporting the diaphragm and the plate with the gap layer sandwiched between the diaphragm and the plate. Forming a conductive electrode film covering the contact hole, and forming a protective film covering the side surface of the electrode film outside the inner wall of the support portion.
According to the present invention, since the protective film is formed outside the inner wall of the support portion, the plate or the diaphragm is not distorted by the film stress of the protective film acting directly. Therefore, the protective film can be formed of a material having a large film stress. On the other hand, the side surface constituting the contour of the electrode film is activated by processing such as etching, or chemical species such as chlorine and fluorine remain, resulting in low chemical stability. According to the present invention, the side surface of the electrode film having low chemical stability can be covered with a material having high performance as a protective film regardless of the magnitude of the film stress. Therefore, according to the present invention, the electrode film can be protected without hindering the mechanical function of the MEMS transducer.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the corresponding component in each figure, and the overlapping description is abbreviate | omitted.
(1) First embodiment Configuration FIG. 1 shows a sensor die 1 of a condenser microphone which is a first embodiment of a MEMS transducer of the present invention. FIG. 2 shows a schematic cross section of the sensor die 1 and corresponds to the line AA ′ shown in FIG. FIG. 3 shows a laminated structure of the sensor die 1. In FIGS. 1 and 3, the layer above the upper conductive film 160 shown in FIG. 2 is not shown. The condenser microphone includes a sensor die 1, a circuit die (not shown) provided with a power supply circuit and an amplifier circuit, and a package (not shown) that accommodates these.

  The sensor die 1 includes a substrate 100, a lower insulating film 110, a lower conductive film 120, an upper insulating film 130, an upper conductive film 160, a pad conductive film 180, a bump film 210, a bump protective film 220, a pad protective film 190, and a plating protective film 200. Is a movable element having a laminated structure.

  The substrate 100 is made of P-type single crystal silicon. The material of the substrate 100 is not limited to this, and it is only necessary to have rigidity, thickness, and toughness as a base substrate for depositing a thin film and a support substrate for supporting a structure formed of the thin film.

The lower insulating film 110 is formed on the substrate 100 and is made of silicon oxide (SiO _x ). The lower insulating film 110 constitutes an annular part 101, a plurality of guard insulating parts 103 located inside the annular part 101, and a plurality of diaphragm spacers 102 located inside the annular part 101.

  The lower conductive film 120 is formed on the lower insulating film 110 and is made of polycrystalline silicon doped with impurities such as P as a whole. The lower conductive film 120 constitutes a guard part 127 and a diaphragm 123.

  The upper insulating film 130 is formed on the lower conductive film 120 and the lower insulating film 110 and is made of silicon oxide. The upper insulating film 130 constitutes an annular portion 132 and a plurality of plate spacers 131 positioned inside the annular portion 132.

  The upper conductive film 160 is formed on the upper insulating film 130 and is made of polycrystalline silicon doped with impurities such as P as a whole. The upper conductive film 160 constitutes a plate 162 and an etch stopper ring 161.

The surface insulating film 170 is formed on the upper conductive film 160 and the upper insulating film 130 and is made of silicon oxide.
The plating protective film 200 exposed on the surface of the sensor die 1 is made of silicon oxide.
The sensor die 1 includes a diaphragm 123, a plate 162, a support portion having a multilayer structure, and four terminals 125e, 162e, 123e, and 100b. Hereinafter, these elements constituting the sensor die 1 will be described.

  The diaphragm 123 is supported by a plurality of diaphragm spacers 102 in parallel with the substrate 100 so that the central portion 123a covers the opening 100a of the back cavity C1, and the diaphragm 123 includes a lower conductive film 120. A plurality of arm portions 123c extending radially outward from 123a and a diaphragm lead 123d are provided. Since the diaphragm 123 is notched between the arm part 123c and the arm part 123c, the rigidity is lower than that of the form without the notch. Furthermore, since a plurality of diaphragm holes 123b, which are through holes, are formed in each arm portion 123c, the rigidity of the arm portion 123c itself is low. A gap C <b> 2 corresponding to the thickness of the diaphragm spacer 102 is formed between the substrate 100 and the diaphragm 123. The air gap C2 balances the pressure of the back cavity C1 with the atmospheric pressure. From one end of the plurality of arm portions 123c, the diaphragm lead 123d extends to the diaphragm terminal 123e through a region where the guard ring 125c is divided. Since the diaphragm terminal 123e and the substrate terminal 100b are short-circuited in a circuit die (not shown), the diaphragm 123 and the substrate 100 are at the same potential. A plurality of diaphragm bumps 123 f are formed on the surface of the diaphragm 123 that faces the substrate 100. The diaphragm bump 123f prevents the diaphragm 123 from sticking (sticking) to the substrate 100.

  The plate 162 is supported in parallel with the diaphragm 123 by a plurality of plate spacers 131 so that the center thereof overlaps the center of the diaphragm 123. The plate 162 is made of an upper conductive film 160, and includes a central portion 162b, arm portions 162a extending radially outward from the central portion 162b, and a plate lead 162d. A plurality of plate holes 162 c that are through holes are formed in the plate 162. The plate hole 162c functions as a hole through which an etchant for isotropically etching the upper insulating film 130 is passed. The portion remaining after the upper insulating film 130 is etched becomes the plate spacer 131 and the annular portion 132, and the portion removed by the etching becomes the gap layer C3 between the diaphragm 123 and the plate 162. The plate hole 162c is arranged according to the height of the gap layer C3, the shape of the plate spacer 131, and the etching rate. A plate lead 162d thinner than the arm 162a extends from the tip of the arm 162a of the plate 162 to the plate terminal 162e. The wiring path of the plate lead 162d overlaps the wiring path of the guard lead 125d. For this reason, the parasitic capacitance between the plate lead 162d and the substrate 100 is reduced. A plurality of protrusions (plate bumps) 162 f are provided on the surface of the plate 162 that faces the diaphragm 123. The plate bump 162f includes a silicon nitride (SiN) film bonded to the upper conductive film 160 constituting the plate 162, and a polycrystalline silicon film bonded to the silicon nitride film. The plate bump 162f prevents the diaphragm 123 from sticking (sticking) to the plate 162.

  Next, a support portion that supports the diaphragm 123 and the plate 162 will be described. The support portion includes a substrate 100, a lower insulating film 110, an upper insulating film 130, a surface insulating film 170, and a plating protective film 200.

A through hole is formed in the substrate 100, and an opening 100a of the through hole forms an opening of the back cavity C1 whose one end is closed by a package substrate (not shown).
A plurality of diaphragm spacers 102 made of the lower insulating film 110 are arranged at equal intervals in the circumferential direction of the opening 100a around the opening 100a of the back cavity C1. The diaphragm spacer 102 supports the diaphragm 123 with the gap C <b> 2 between itself and the substrate 100, and insulates the diaphragm 123 from the plate 162.

The plurality of plate spacers 131 made of the upper insulating film 130 are joined to the guard electrode 125a made of the lower conductive film 120, respectively. The plate spacer 131 supports the plate 162 with the gap layer C3 sandwiched between it and the diaphragm 123. Each plate spacer 131 is located in a notch region between the arm portion 123 c and the arm portion 123 c of the diaphragm 123. The plurality of guard electrodes 125a are supported on the substrate 100 by the guard insulating portions 103 made of the lower insulating film 110, respectively. That is, the plate 162 is supported on the substrate 100 by the guard insulating portion 103, the guard electrode 125a, and the plate spacer 131.
The gap layer C3 between the diaphragm 123 and the plate 162 is surrounded by the inner wall 132a of the annular portion 132 of the upper insulating film 130.

  Next, the terminal structure of the sensor die 1 of the condenser microphone will be described. The sensor die 1 is provided with four terminals 125e, 162e, 123e, and 100b. As shown in FIGS. 4A, 4B, 4C, and 4D, each of the terminals 125e, 162e, 123e, and 100b includes a pad conductive film 180, a bump film 210, and a bump protection film 220.

  The pad conductive film 180 is mainly made of aluminum. The pad conductive film 180 contains about 1% silicon to prevent diffusion of silicon from the upper conductive film 160 and the like into the pad conductive film 180. As shown in FIG. 4A, the pad conductive film 180 covering the contact hole CH3 is bonded to the guard lead 125d. As shown in FIG. 4B, the pad conductive film 180 covering the contact hole CH2 is bonded to the plate lead 162d. As shown in FIG. 4C, the pad conductive film 180 covering the contact hole CH4 is bonded to the substrate 100. As shown in FIG. 4D, the pad conductive film 180 covering the contact hole CH1 is joined to the diaphragm lead 123d.

  The pad protection film 190 is formed on the surface insulating film 170 and the pad conductive film 180 and covers the side surfaces (end surfaces formed by etching) of the pad conductive film 180. The pad protection film 190 is made of silicon nitride or silicon nitride oxide. The pad protection film 190 is formed only around the pad conductive film 180 on the surface of the surface insulating film 170 constituting the support portion, as shown in FIG. 13B. That is, the pad protection film 190 is limited to a region excluding a part of the surface of the pad conductive film 180 outside the inner wall 132a of the annular portion 132 constituting the support portion and the periphery of the pad conductive film 180 on the surface of the insulating portion 171. It is formed and covers the side surface of the pad conductive film 180. The pad protective film 190 is formed away from each other for each of the terminals 125e, 162e, 123e, and 100b. The range in which the pad protective film 190 covers the sensor die 1 is limited, and the pad protective film 190 covers the plate 162. Absent. Therefore, even if the pad protective film 190 is formed of silicon nitride having a large film stress, the function of the sensor die 1 is not impaired. On the other hand, when the pad protection film 190 is formed to the inside of the inner wall 132a of the annular portion 132 constituting the support portion, the pad protection film 190 and the plate 162 are joined, so that the plate 162 is distorted. . In this case, since the height of the gap C2 between the plate 162 and the diaphragm 123 changes, the function of the sensor die 1 is impaired, or the characteristics of the sensor die 1 vary.

  A bump film 210 is formed on the surface of the pad conductive film 180 that is not covered with the pad protective film 190. In other words, the pad protection film 190 is formed at least on the surface of the pad conductive film 180 except for the bump formation region. The bump film 210 is made of nickel.

  The surface of the bump film 210 is covered with a bump protective film 220. The bump protective film 220 is exposed on the surface of the sensor die 1. The bump protective film 220 is made of a metal having excellent corrosion resistance such as Au.

  The guard part 127 includes a guard electrode 125a, a guard connector 125b, a guard ring 125c, and a guard lead 125d. The guard part 127 reduces the parasitic capacitance formed by the diaphragm 123 and the plate 162.

2. Action A stable bias voltage is applied to the diaphragm 123 by a charge pump provided in the circuit die. A sound wave transmitted from a through hole of the package (not shown) is transmitted to the diaphragm 123 through the plate hole 162c and a notch region between the arms of the plate 162. Since the sound wave having the same phase is transmitted from both surfaces to the plate 162, the plate 162 does not substantially vibrate. The sound waves transmitted to the diaphragm 123 cause the diaphragm 123 to vibrate with respect to the plate 162. When the diaphragm 123 vibrates, the capacitance of the parallel plate capacitor having the plate 162 and the diaphragm 123 as the counter electrodes varies. An electric signal corresponding to this capacitance formed by the plate 162 and the diaphragm 123 is output from the sensor die 1 as a potential difference between the diaphragm terminal 123e and the plate terminal 162e. This electrical signal is input to the amplifier of the circuit die as a voltage signal and amplified. That is, an electrical signal corresponding to the electrostatic capacitance formed by the plate 162 and the diaphragm 123 is output through the pad conductive film 180 that constitutes the diaphragm terminal 123e and the plate terminal 162e. Note that a charge pump, an amplifier, and the like can be provided in the sensor die 1.

3. Manufacturing Method Next, a method for manufacturing a condenser microphone will be described with reference to FIGS.
In the step shown in FIG. 5, first, a lower insulating film 110 that is a silicon oxide deposition film is formed on the entire surface of the substrate 100. Next, dimples 110a for forming the diaphragm bumps 123f are formed on the lower insulating film 110 by etching using a photoresist mask. Next, a lower conductive film 120 that is a deposited film of polycrystalline silicon is formed on the surface of the lower insulating film 110 using a CVD method or the like. Then, the diaphragm bump 123f is formed on the dimple 110a. Further, by etching the lower conductive film 120 using a photoresist mask, the diaphragm 123 and the guard portion 127 made of the lower conductive film 120 are formed.

  Subsequently, in the step shown in FIG. 6, an upper insulating film 130 that is a deposited film of silicon oxide is formed on the entire surface of the lower insulating film 110 and the lower conductive film 120. Further, a dimple 130a for forming the plate bump 162f is formed on the upper insulating film 130 by etching using a photoresist mask.

  In the subsequent step shown in FIG. 7, a plate bump 162 f made of a polycrystalline silicon film 135 and a silicon nitride film 136 is formed on the surface of the upper insulating film 130. The silicon nitride film 136 prevents the diaphragm 123 and the plate 162 from being short-circuited by contact.

  Subsequently, in the step shown in FIG. 8, an upper conductive film 160, which is a polycrystalline silicon deposited film, is formed on the surface of the upper insulating film 130 and the surface of the silicon nitride film 136 using a CVD method or the like. Next, the upper conductive film 160 is etched using a photoresist mask to form a plate 162 and an etch stopper ring 161. In this step, the plate hole 162c is not formed.

  Subsequently, in the step shown in FIG. 9, the through holes H1, H3, and H4 that expose the diaphragm 123, the guard portion 127, and the substrate 100 corresponding to the contact holes CH1, CH3, and CH4 are anisotropically etched using a photoresist mask. Thus, the lower insulating film 110 and the upper insulating film 130 are formed.

  Subsequently, in the step shown in FIG. 10, a surface insulating film 170 made of silicon oxide is formed on the entire surface by plasma CVD. Further, contact holes CH1, CH2, CH3, and CH4 are formed in the surface insulating film 170 by etching using a photoresist mask. As a result, the diaphragm 123, the plate 162, the guard part 127, and the substrate 100 are exposed.

  Subsequently, as shown in FIG. 11, a deposited film made of AlSi that covers each of the contact holes CH1, CH2, CH3, and CH4 and is bonded to the diaphragm 123, the plate 162, the guard portion 127, and the substrate 100 is formed on the entire surface by sputtering. Form. Further, when etching using a photoresist mask is performed to partially remove the AlSi deposited film while leaving the portions covering the contact holes CH1, CH2, CH3, and CH4, the pad conductive film 180 made of the AlSi deposited film is formed. It is formed. At this time, the deposited film of AlSi is divided into regions corresponding to the contact holes CH 1, CH 2, CH 3, and CH 4, and the side surfaces of the pad conductive film 180 that form the outline of the pad conductive film 180 are formed. When patterning a deposited film of AlSi by wet etching, for example, a mixed acid (for example, a mixed acid of phosphoric acid, nitric acid, and water) is used as an etchant, and is 60 to 75 ° C. (preferably 65 ° C.), 30 to 120 seconds (preferably 60 seconds) and a spin processor in which conditions of 600 to 1000 rotations (preferably 800 rotations) are set. The side surface of the pad conductive film 180 formed by wet etching exposes the side wall activated by the etching, so that it has low chemical stability and is easily corroded. Since the side surface of the pad conductive film 180 formed by dry etching is exposed to chlorine gas used for etching, it has low chemical stability and is easily corroded.

Then, subsequently, as shown in FIG. 12, a pad protective film 190, which is a silicon nitride deposited film for protecting the side surfaces of the pad conductive film 180, is formed on the surface of the surface insulating film 170 and the pad conductive film 180 by a low stress plasma CVD method. Formed on the surface. For example, low stress under conditions of temperature: 400 ° C., pressure: 2.5 Torr, SiH ₄ flow rate: 0.3 SLM, NH ₃ flow rate: 1.75 SLM, bias power (RF H / F): 0.44 kW / 0.351 kW A pad protective film 190 made of silicon nitride having a thickness of 1.6 μm is formed by plasma CVD.

Subsequently, as shown in FIGS. 13A and 13B, the pad protection film 190 is used as a photoresist mask, leaving only a region on the edge of each pad conductive film 180 and a region around each pad conductive film 180. Partially removed by dry etching. As a result, a pad protective film 190 made of a deposited silicon nitride film that is excellent as a protective film is formed at a distance from the contact holes CH1, CH2, CH3, and CH4. The patterning method of the pad protection film 190 is, for example, CF ₄ + O ₂ mixed gas flow rate: 150 SCCM, pressure: 0.8 to 1.2 Torr (preferably 1.0 Torr), bias power 250 W, heating: 80 ° C./130 seconds. Dry etching using a parallel plate type plasma etcher is performed under certain conditions. The stress after annealing of the pad protective film 190 made of silicon nitride is generally about 100 MPa to 1 GPa. However, in the present embodiment, the pad protection film 190 made of a silicon nitride film is patterned so as to remain only locally, so that distortion of the sensor die 1 due to the stress of the pad protection film 190 is suppressed.

  Subsequently, in the process shown in FIG. 14, through holes corresponding to the plate holes 162c are formed in the surface insulating film 170 by anisotropic etching using a photoresist mask, and the plate holes 162c are formed in the upper conductive film 160. The This process is continuously performed, and the surface insulating film 170 in which the through holes are formed functions as an etching mask for the upper conductive film 160.

  Subsequently, in the step shown in FIG. 15, a plating protective film 200 made of silicon oxide is formed on the surface of the surface insulating film 170, the surface of the pad conductive film 180, and the surface of the pad protective film 190. Further, the plating protective film 200 is patterned by etching using a photoresist mask to expose the center portion of the surface of the pad conductive film 180 covering the contact holes CH1, CH2, CH3, and CH4.

  Subsequently, in the step shown in FIG. 16, a bump film 210 made of nickel is formed on the surface of the pad conductive film 180 exposed from the through hole of the plating protective film 200 by an electroless plating method. Further, a bump protection film 220 made of gold is formed on the surface of the bump film 210. Further, the back surface of the substrate 100 is ground to make the thickness of the substrate 100 a complete dimension.

  Subsequently, in the step shown in FIG. 17, an annular through hole H5 in which the etch stopper ring 161 is exposed is formed in the plating protective film 200 and the surface insulating film 170 by etching using a photoresist mask.

  Subsequently, in a process shown in FIG. 18, a photoresist mask R <b> 1 having a through hole H <b> 6 for forming a through hole corresponding to the back cavity C <b> 1 in the substrate 100 is formed on the back surface of the substrate 100.

  Subsequently, in a process shown in FIG. 19, a through hole corresponding to the back cavity C1 is formed in the substrate 100 by deep substrate etching (Deep-RIE). At this time, the lower insulating film 110 serves as an etching stopper.

  Subsequently, as shown in FIGS. 20 and 21, the plating protective film 200 exposed from the through hole H6 of the photoresist mask R2 by isotropic etching using the photoresist mask R2 and BHF (dilute hydrofluoric acid) and The surface insulating film 170 is removed, and a part of the upper insulating film 130 is further removed to form the annular portion 132, the plate spacer 131, and the gap layer C3. Further, a part of the lower insulating film 110 is removed from the back cavity C1. The guard insulating portion 103, the diaphragm spacer 102, the annular portion 101, and the gap C2 are formed. At this time, the etchant BHF enters from each of the through hole H6 of the photoresist mask R2 and the opening 100a of the substrate 100. The contour of the upper insulating film 130 is defined by the plate 162. That is, the annular portion 132 and the plate spacer 131 are formed by self-alignment with the plate 162. The contour of the lower insulating film 110 is defined by the opening 100a of the substrate 100, the diaphragm 123, the guard electrode 125a, the guard connector 125b, and the guard ring 125c, and the guard insulating portion 103 and the diaphragm spacer 102 are formed by self-alignment.

Finally, the photoresist mask R2 is removed, and the substrate 100 is diced to complete the capacitor microphone sensor die 1 shown in FIG. A sensor die 1 and a circuit die (not shown) are bonded to a package substrate (not shown), and terminals 125e, 162e, 123e, 100b of the sensor die 1 and terminals (not shown) of the circuit die are electrically connected by wire bonding, and a package cover (not shown) Is placed on the package substrate to complete the condenser microphone. By bonding the sensor die 1 to the package substrate, the back cavity C1 is closed on the back side of the substrate 100.
(2) Second Embodiment FIG. 22 is a schematic cross-sectional view showing a sensor die 2 of a condenser microphone which is a second embodiment of the MEMS transducer of the present invention. As shown in FIG. 22, the pad protection film 190 may cover a region spanning the outer edge portion of the substrate 100 and the outer edge portion of the surface insulating film 170. When the pad protection film 190 covers a region spanning the outer edge portion of the substrate 100 and the outer edge portion of the surface insulating film 170, the edge of the bonding surface between the substrate 100 made of single crystal silicon and the surface insulating film 170 made of silicon oxide is oxidized. It is covered with a pad protective film 190 made of silicon nitride or silicon nitride oxide having a higher protective function than the plating protective film 200 made of silicon. Thereby, it is possible to more reliably prevent mobile ions from entering from the end of the bonding surface between the substrate 100 made of single crystal silicon and the surface insulating film 170 made of silicon oxide.

(3) Other Embodiments The technical scope of the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the scope of the present invention. . For example, the pad protection film 190 is desirably formed in a narrow region as long as it covers the side surface of the pad conductive film 180 as an electrode film. However, as shown in FIGS. 22 to 25, adjacent terminals 123e and 100b or adjacent to each other. The pad protection film 190 may be integrated by a combination of the terminals 125e and 162e. Further, the pad protection film 190 of all the terminals 125e, 162e, 123e, 100b may be integrated. Further, as shown in FIG. 23, the pad protective film 190 is spread over the etch stopper ring 161 or in the vicinity thereof, and the pad protective film 190 is formed on almost the entire outside of the inner wall 132a of the annular portion 132 constituting the support portion. Also good. The pad protective film 190 may be circular or polygonal.

  Further, for example, the materials and dimensions shown in the above embodiment are merely examples, and descriptions of addition and deletion of processes and replacement of the process order that are obvious to those skilled in the art are omitted. For example, in the above-described manufacturing process, the film composition, film forming method, film contour forming method, process sequence, etc. are combinations of film materials having physical properties that can constitute a condenser microphone, film thickness, and required contour. It is appropriately selected according to the shape accuracy and the like and is not particularly limited. Furthermore, the present invention can be applied to vibration transducers other than condenser microphones such as ultrasonic sensors, pressure sensors, and acceleration sensors.

The top view concerning embodiment of this invention. The typical sectional view concerning the embodiment of the present invention. The disassembled perspective view concerning embodiment of this invention. 4A, 4B, 4C, and 4D are all cross-sectional views according to the embodiment of the present invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. FIG. 13A is a cross-sectional view according to an embodiment of the present invention. FIG. 13B is a plan view according to the embodiment of the present invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention. Sectional drawing concerning embodiment of this invention.

Explanation of symbols

1: sensor die, 2: sensor die, 3: sensor die, 4: sensor die, 5: sensor die, 100: substrate, 100a: opening, 100b: substrate terminal, 101: annular portion, 102: diaphragm spacer, 103: guard insulating portion, 110 : Lower insulating film, 110a: Dimple, 120: Lower conductive film, 123: Diaphragm, 123a: Center part, 123b: Diaphragm hole, 123c: Arm part, 123d: Diaphragm lead, 123e: Diaphragm terminal, 123f: Diaphragm bump, 125a : Guard electrode, 125b: guard connector, 125c: guard ring, 125d: guard lead, 125e: terminal, 127: guard part, 130: upper insulating film, 130a: dimple, 131: plate spacer, 132: annular part, 132a: Inner wall, 135 Polycrystalline silicon film, 136: silicon nitride film, 160: upper layer conductive film, 161: etch stopper ring, 162: plate, 162a: arm part, 162b: center part, 162c: plate hole, 162d: plate lead, 162e: plate Terminal: 162f: Plate bump, 170: Surface insulating film, 171: Insulating part, 180: Pad conductive film, 190: Pad protective film, 200: Plating protective film, 210: Bump film, 220: Bump protective film, C2: Gap C3: void layer, CH1: contact hole, CH2: contact hole, CH3: contact hole, CH4: contact hole, H1: through hole, H5: through hole, H6: through hole, R1: photoresist mask, R2: photo Resist mask

Claims (4)

A conductive diaphragm;
A conductive plate;
A support part including an inner wall surrounding the gap layer, supporting the diaphragm and the plate with a gap layer interposed between the diaphragm and the plate;
A conductive electrode film covering a contact hole formed in the support;
A protective film that is formed on the support portion outside the inner wall and covers a side surface of the electrode film;
With
An electrical signal corresponding to the capacitance formed by the diaphragm and the plate is output through the electrode film.
MEMS transducer. The protective film is made of silicon nitride or nitrogen silicon oxide,
The MEMS transducer according to claim 1. The support portion has a multilayer structure including a silicon substrate and a silicon oxide film bonded to a region excluding an outer edge portion of the silicon substrate,
The protective film covers a region spanning the outer edge of the silicon substrate and the outer edge of the silicon oxide film,
The MEMS transducer according to claim 2. A contact hole is formed in a support portion including an inner wall surrounding the gap layer while supporting the diaphragm and the plate with a gap layer interposed between the diaphragm and the plate,
Forming a conductive electrode film covering the contact hole;
Forming a protective film covering a side surface of the electrode film outside the inner wall of the support;
A method of manufacturing a MEMS transducer.

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