JP2009089098A - Vibrating transducer and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase sensitivity in a vibrating transducer. <P>SOLUTION: The vibrating transducer has: a conductive diaphragm including a deposited film; a conductive plate including the deposited film; and a plurality of first columnar spacers that includes the deposited film joined to the plate, have insulation properties, and support the plate with a gap to the diaphragm. In the vibrating transducer, electrostatic capacity, which is formed by the diaphragm and the plate, is changed by vibrating the diaphragm to the plate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vibration transducer and a method for manufacturing the vibration transducer, and more particularly to a wave transducer such as a minute condenser microphone as a MEMS sensor.

  Conventionally, a minute condenser microphone manufactured by applying a semiconductor device manufacturing process is known. Such a condenser microphone is called a MEMS microphone, and the diaphragm and the plate constituting the counter electrode are formed of a thin film deposited on the substrate 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. In a conventional vibration transducer such as a condenser microphone, a plate is bonded to an insulating film in the vicinity of the outer edge thereof.

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

  However, in the structure in which the plate is bonded to the insulating film, in the region near the outer edge of the plate, the parasitic capacitance between the plate having the insulating film as a dielectric layer and the diaphragm or the substrate causes a decrease in sensitivity. .

  The present invention was created to solve this problem, and aims to increase the sensitivity of a vibration transducer.

(1) A vibration transducer for achieving the above object is composed of a deposited film made of a conductive diaphragm, a deposited film made of a conductive plate, and a deposited film joined to the plate. And a plurality of columnar first spacers that support the plate with a gap between the diaphragm and the diaphragm, and the capacitance formed by the diaphragm and the plate when the diaphragm vibrates with respect to the plate Changes.
The area where the diaphragm is fixed does not vibrate with respect to the plate. Therefore, when the diaphragm and the plate are opposed to each other in the region, and the diaphragm and the plate are conductive, the diaphragm and the plate form a parasitic capacitance in the region. Therefore, it is desirable that the area of the first spacer, which has a higher dielectric constant than air, be smaller. Therefore, in the present invention, the first spacer that supports the plate is formed in a columnar shape instead of an annular shape, and the plate is supported by a plurality of columnar first spacers. Thereby, the parasitic capacitance formed by the diaphragm and the plate can be reduced, and as a result, the sensitivity is improved. The first spacer is not limited to a geometrical pillar, and may be flat as long as the plate can be supported as a plurality of structures instead of structurally closed walls. Although the parasitic capacitance formed by the diaphragm and the plate can be reduced by configuring the plate or the diaphragm with an insulator in the region facing the diaphragm and the plate, the film structure of at least one of the diaphragm and the plate can be reduced. Becomes complicated.

(2) The vibration transducer according to the present invention forms a plate having a plurality of through holes, and removes a part of the deposited film serving as the first spacer by isotropic etching using the plate as a mask, whereby the plate and the diaphragm are removed. And forming a first spacer composed of the remaining portion.
According to this method, since the first spacer can be formed using the plate as an etching mask, the number of masks can be reduced and the manufacturing cost can be reduced.

  (3) That is, in the vibration transducer according to the present invention, the plate is formed with a plurality of through-holes through which an etchant for simultaneously forming the gap between the plate and the diaphragm and the first spacer by isotropic etching of the deposited film. It is desirable that

(4) A vibration transducer for achieving the above object is bonded to a substrate, a conductive diaphragm made of a deposited film on the substrate, a conductive plate made of a deposited film on the substrate, and the substrate and the plate. A plurality of columnar second spacers that are made of a deposited film and have insulating properties and support the plate with a gap between the substrate and the diaphragm vibrates with respect to the plate The capacitance formed by the diaphragm and the plate changes.
When the plate and the substrate form a parasitic capacitance in a region facing each other with the second spacer interposed therebetween, it is desirable that the area of the second spacer that has a higher non-permittivity than air is as small as possible. Therefore, in the present invention, the second spacer is not in an annular shape but in a columnar shape, and the plate is supported by a plurality of columnar second spacers. Thereby, the parasitic capacitance formed by the substrate and the plate can be reduced, and as a result, the sensitivity is improved. The second spacer is not limited to a geometrical pillar, and may be flat as long as the plate can be supported as a plurality of structures instead of structurally closed walls. In addition, even if the region joined to the second spacer of the plate is made of an insulator, it is possible to reduce the parasitic capacitance formed by the substrate and the plate in the region facing the second spacer. Yes, but the membrane structure of the plate is complicated.

(5) The vibration transducer according to the present invention forms a plate having a plurality of through holes, and removes a part of the deposited film serving as the second spacer by isotropic etching using the plate as a mask. And forming a second spacer including the remainder and forming a gap between the first and second spacers.
According to this method, since the second spacer can be formed using the plate as an etching mask, the number of masks can be reduced and the manufacturing cost can be reduced.

  (6) That is, in the vibration transducer according to the present invention, the plate is formed with a plurality of through-holes through which an etchant for simultaneously forming the gap between the plate and the substrate and the second spacer by isotropic etching of the deposited film. It is desirable that

  (7) A vibration transducer for achieving the above object includes a diaphragm made of a deposited film and having conductivity, and a plate made of the deposited film, having conductivity and facing the diaphragm. The distance from the center to the outer edge is shorter than the distance from the center to the outer edge of the diaphragm, and the capacitance formed by the diaphragm and the plate changes as the diaphragm vibrates with respect to the plate.

  In a region where the diaphragm amplitude is small or the diaphragm does not vibrate, the capacitance formed by the diaphragm and the plate does not change or changes little. In a structure in which a region near the outer edge of the diaphragm is fixed to the upper or lower film, the amplitude of the diaphragm is reduced in a region near the outer edge of the diaphragm. Therefore, in the present invention, the distance from the center of the plate to the outer edge is made shorter than the distance from the center of the diaphragm to the outer edge so that the diaphragm and the plate do not face each other in a region near the outer edge of the diaphragm. When the plate and the diaphragm have a circular shape or a shape having no recess in the outline, the outer edge of the plate may be inside the outer edge of the diaphragm. If the diaphragm has a circular or contoured shape and the plate has a concave shape, the shortest distance from the center of the plate to the outer edge must be shorter than the shortest distance from the center of the diaphragm to the outer edge. is there. If the plate has a circular or contoured shape and the diaphragm has a concave shape, the shortest distance from the center of the plate to the outer edge must be shorter than the shortest distance from the center of the diaphragm to the outer edge. is there. When the plate and the diaphragm have a shape with a concave portion in the contour, it is desirable that the shortest distance from the center of the plate to the outer edge is shorter than the shortest distance from the center of the diaphragm to the outer edge. According to the present invention, the parasitic capacitance of the diaphragm and the plate in the region near the outer edge of the diaphragm can be reduced, and as a result, the sensitivity is increased. In addition, it is possible to reduce the parasitic capacitance formed by the diaphragm and the plate by configuring the region near the outer edge of the diaphragm with an insulator, or by configuring the plate region facing the outer edge of the diaphragm with an insulator. Although it is possible, the film structure of at least one of the diaphragm and the plate is complicated.

(8) A vibration transducer for achieving the above object includes a substrate, a deposited film on the substrate, and a conductive diaphragm, a deposited film on the substrate, and a conductive plate, the substrate and the diaphragm. And a plurality of pillar-shaped third spacers that support the diaphragm with an air gap between the substrate and the diaphragm, and the diaphragm vibrates with respect to the plate. As a result, the capacitance formed by the diaphragm and the plate changes.
When the diaphragm and the substrate form a parasitic capacitance in a region facing each other with the third spacer interposed therebetween, it is desirable that the area of the third spacer, which has a higher dielectric constant than air, is smaller. Therefore, in the present invention, the third spacer is formed in a column shape instead of an annular shape, and the diaphragm is supported by a plurality of columnar third spacers. Thereby, the parasitic capacitance formed by the substrate and the diaphragm can be reduced, and as a result, the sensitivity is improved. The third spacer is not limited to a geometrical column body, and may be flat, and may be structurally capable of supporting the diaphragm as a plurality of structures instead of a closed wall. In addition, even if the region bonded to the third spacer of the diaphragm is formed of an insulator, it is possible to reduce the parasitic capacitance formed by the substrate and the diaphragm in the region facing each other with the third spacer interposed therebetween. Yes, but the diaphragm membrane structure is complicated.

  (9) In any of the above-described vibration transducers, when the plate includes a central portion and a plurality of arm portions extending radially outward from the central portion, the diaphragm has at least a notch between the arm portion and the arm portion. In the region of, do not face the plate. Therefore, the parasitic capacitance formed by the diaphragm and the plate can be reduced by making the plate radially extend from the central portion to the outside. In the structure in which the substrate and the plate form a parasitic capacitance, the parasitic capacitance formed by the diaphragm and the plate can be reduced by making the plate radially extend from the center to the outside.

  In the claims, “to the top” means both “without an intermediate on the top” and “with an intermediate on the top” unless there is a technical impediment. To do. Further, the order of the operations described in the claims is not limited to the order of description as long as there is no technical obstruction factor, and may be executed at the same time, may be executed in the reverse order of the description order, or may be continuous. It does not have to be executed in order.

  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. Configuration FIG. 1 shows a sensor chip which is a MEMS structure part of a condenser microphone 1 according to an embodiment of the present invention, FIG. 2 shows a schematic cross section thereof, and FIG. 3 shows a laminated structure of the film. 18 and 19 show a detailed cross section of a part thereof. The condenser microphone 1 includes a sensor chip, a circuit chip (not shown) provided with a power supply circuit and an amplifier circuit, and a package (not shown) that accommodates these.

  The sensor chip of the capacitor microphone 1 is a chip composed of a substrate 100 and a deposited film such as a lower insulating film 110, a lower conductive film 120, an upper insulating film 130, an upper conductive film 160, and a surface insulating film 170 stacked thereon. It is. First, the laminated structure of the film of the MEMS structure portion of the condenser microphone 1 will be described.

  The substrate 100 is made of P-type single crystal silicon. The material of the substrate 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 made of the thin film. A through hole is formed in the substrate 100, and the opening 100a of the through hole forms an opening of the back cavity C1.

The lower insulating film 110 bonded to the substrate 100, the lower conductive film 120, and the upper insulating film 130 is a deposited film made of silicon oxide (SiO _x ). The lower insulating film 110 includes a plurality of third spacers 102 arranged at equal intervals on the circumference, a plurality of guard spacers 103 arranged at equal intervals on the circumference inside the third spacer 102, and a guard ring. 125c and the guard lead 125d are formed with an annular portion 101 that insulates the substrate 100 from the substrate 100.

  The lower conductive film 120 joined to the lower insulating film 110 and the upper insulating film 130 is a deposited film made of polycrystalline silicon doped with impurities such as P as a whole. The lower conductive film 120 forms a guard part 127 including a guard electrode 125a, a guard connector 125b, a guard ring 125c, and a guard lead 125d, and a diaphragm 123.

  The upper insulating film 130 bonded to the lower conductive film 120, the upper conductive film 160, and the lower insulating film 110 is a deposited film made of silicon oxide. The upper insulating film 130 is located on the outer circumference of the plurality of first spacers 131 and an annular annular portion that supports the etch stopper ring 161 and insulates the plate lead 162d and the guard lead 125d from each other. 132.

  The upper conductive film 160 bonded to the upper insulating film 130 is a deposited film made of polycrystalline silicon doped with impurities such as P as a whole. The upper conductive film 160 constitutes a plate 162, a plate lead 162d, and an etch stopper ring 161.

  A surface insulating film 170 bonded to the upper conductive film 160 and the upper insulating film 130 is an insulating deposited film made of a silicon oxide film.

  The MEMS structure portion of the condenser microphone 1 is provided with four terminals 125e, 162e, 123e, and 100b. These terminals 125e, 162e, 123e, and 100b are a conductive conductive film such as AlSi, a pad conductive film 180, a bump film 210 that is a conductive deposited film such as Ni, and a conductive material having excellent corrosion resistance such as Au. A bump protective film 220 which is a conductive deposited film. The side walls of the terminals 125e, 162e, 123e, and 100b are protected by a pad protective film 190 that is an insulating deposited film such as SiN and a surface protective film 200 that is an insulating deposited film such as silicon oxide.

  The laminated structure of the MEMS structure film of the condenser microphone 1 has been described above. Next, the mechanical structure of the MEMS structure part of the condenser microphone 1 will be described.

  The diaphragm 123 is formed of a single-layer thin deposited film having conductivity as a whole, and includes a central portion 123a and a plurality of arm portions 123c extending radially outward from the central portion 123a. The diaphragm 123 is supported by being insulated from the plate 162 with a gap between the plate 162 and the substrate 100 by a plurality of columnar third spacers 102 joined to a plurality of locations near the outer edge of the diaphragm 123. Are stretched parallel to the substrate 100. The third spacer 102 is joined to the vicinity of the distal end portion of each arm portion 123 c of the diaphragm 123. 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. In the vicinity of the central portion 123a, the arm portion 123c of the diaphragm 123 becomes longer in the circumferential direction of the diaphragm 123 as it approaches the central portion 123a. Thereby, the stress concentration at the boundary between the arm portion 123c and the central portion 123a can be relaxed. Moreover, stress concentration can be prevented from occurring in the bent portion by not forming the bent portion in the outline of the arm portion 123c in the vicinity of the boundary between the arm portion 123c and the central portion 123a.

  The plurality of third spacers 102 are arranged at equal intervals in the circumferential direction of the opening 100a around the opening 100a of the back cavity C1. Each third spacer 102 is made of an insulating deposited film and has a column shape. The diaphragm 123 is supported on the substrate 100 by these third spacers 102 so that the central portion 123a covers the opening 100a of the back cavity C1. A gap C <b> 2 corresponding to the thickness of the third spacer 102 is formed between the substrate 100 and the diaphragm 123. The air gap C2 is necessary to balance the atmospheric pressure of the back cavity C1 with the atmospheric pressure. The gap C2 is low and the radial length of the diaphragm 123 is long so that the acoustic wave that vibrates the diaphragm 123 forms the maximum acoustic resistance in the path to the back cavity opening 100a.

  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 is a protrusion for preventing the diaphragm 123 from adhering (sticking) to the substrate 100, and is formed by the undulation of the lower conductive film 120 constituting the diaphragm 123. That is, dimples (dents) are formed on the back side of the diaphragm bump 123f.

The diaphragm 123 is connected to the diaphragm terminal 123e by a diaphragm lead 123d extending from one end of the plurality of arm portions 123c. Diaphragm lead 123d is narrower than arm portion 123c and is formed of lower conductive film 120 that is the same as diaphragm 123. The diaphragm lead 123d extends to the diaphragm terminal 123e through a region where the annular guard ring 125c is divided. Since the diaphragm terminal 123e and the substrate terminal 100b are short-circuited in a circuit chip (not shown) (see FIG. 4), the diaphragm 123 and the substrate 100 are at the same potential.
When the potentials of the diaphragm 123 and the substrate 100 are different, the diaphragm 123 and the substrate 100 form a parasitic capacitance. Even in this case, the diaphragm 123 is supported by the plurality of third spacers 102. Since an air layer exists between the adjacent third spacers 102, the parasitic capacitance is reduced as compared with a structure in which the diaphragm 123 is supported by a spacer having an annular wall structure.

  The plate 162 is composed of a single layer thin deposited film having conductivity as a whole, and includes a central portion 162b and arm portions 162a extending radially outward from the central portion 162b. The plate 162 is supported by a plurality of columnar first spacers 131 joined to a plurality of locations near the outer edge thereof. Further, the plate 162 is stretched in parallel with the diaphragm 123 so that the center thereof overlaps the center of the diaphragm 123. The distance from the center of the plate 162 (center of the center portion 162b) to the outer edge of the center portion 162b, that is, the shortest distance from the center of the plate 162 to the outer edge is the outer edge of the center portion 123a from the center of the diaphragm 123 (center of the center portion 123a). Is shorter than the shortest distance from the center of the diaphragm 123 to the outer edge. Therefore, the plate 162 does not face the diaphragm 123 in the region near the outer edge of the diaphragm 123 having a small amplitude. In addition, since a notch is formed between the arm 162a and the arm 162a of the plate 162, the plate 162 and the diaphragm 123 face each other even in the notch region of the plate 162 corresponding to the vicinity of the outer edge of the diaphragm 123. do not do. The arm portion 123 c of the diaphragm 123 extends in the notch region of the plate 162. For this reason, the distance between both ends of the vibration of the diaphragm 123, that is, the distance over which the diaphragm 123 is stretched can be increased without increasing the parasitic capacitance.

  A plurality of plate holes 162 c that are through holes are formed in the plate 162. The plate hole 162c functions as a passage for propagating sound waves to the diaphragm 123, and also functions as a hole through which an etchant for isotropically etching the upper insulating film 130 is passed. The portion that remains after the upper insulating film 130 is etched becomes the first spacer 131 and the annular portion 132, and the portion that is removed by etching becomes the gap C <b> 3 between the diaphragm 123 and the plate 162. That is, the plate hole 162c is a through hole for allowing the etchant to reach the upper insulating film 130 so that the gap C3 and the first spacer 131 can be formed simultaneously. Therefore, the plate hole 162c is arranged according to the height of the gap C3, the shape of the first spacer 131, and the etching rate. Specifically, the plate holes 162c are arranged at substantially equal intervals over almost the entire region of the central portion 162b and the arm portion 162a except for the bonding region with the first spacer 131 and the periphery thereof. As the interval between the adjacent plate holes 162c is narrowed, the width of the annular portion 132 of the upper insulating film 130 can be narrowed to reduce the chip area. On the other hand, the rigidity of the plate 162 becomes lower as the interval between the adjacent plate holes 162c is reduced.

  The first spacer 131 is joined to a guard electrode 125a located in the same layer as the diaphragm 123 (the guard electrode 125a is made of the same lower conductive film 120 as the diaphragm 123). The first spacer 131 includes an upper insulating film 130 that is an insulating deposited film bonded to the plate 162. The plurality of first spacers 131 are arranged at equal intervals around the opening 100a of the back cavity C1. Since each first spacer 131 is located in a notch region between the arm portion 123c and the arm portion 123c of the diaphragm 123, the maximum diameter of the plate 162 can be made smaller than the maximum diameter of the diaphragm 123. This increases the rigidity of the plate 162 and reduces the parasitic capacitance between the plate 162 and the substrate 100.

  The plate 162 is supported on the substrate 100 by a plurality of columnar second spacers 129 each formed by the guard spacer 103, the guard electrode 125 a, and the first spacer 131. That is, in the present embodiment, the second spacer 129 has a structure composed of a multilayer deposited film. Due to the second spacer 129, a gap C <b> 3 is formed between the plate 162 and the diaphragm 123, and a gap C <b> 3 and a gap C <b> 2 are formed between the plate 162 and the substrate 100. Since the guard spacer 103 and the first spacer 131 are insulative, the plate 162 is insulated from the substrate 100.

  When the guard electrode 125a is not provided and the potential of the plate 162 and the potential of the substrate 100 are different, a parasitic capacitance is generated in the region where the plate 162 and the substrate 100 are opposed to each other, and particularly when there is an insulator between them. Increases the parasitic capacitance (see FIG. 4A). In the present embodiment, the second spacer 129 in which the guard spacer 103, the guard electrode 125a, and the first spacer 131 that support the plate 162 on the substrate 100 are regarded as one structure is columnar, and a plurality of structures separated from each other. Since the structure is such that the plate 162 is supported on the substrate 100 by a body, even if the guard electrode 125a is not provided, the parasitic capacitance is small compared to the structure in which the plate 162 is supported on the substrate 100 by an insulator having an annular wall structure. Become.

  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.

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 plate lead 162 d is made of the same upper conductive film 160 as the plate 162. 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.
The mechanical structure of the MEMS structure part of the condenser microphone 1 has been described above.

2. FIG. 4 shows a circuit configured by connecting a circuit chip and a sensor chip. A stable bias voltage is applied to the diaphragm 123 by a charge pump CP provided in the circuit chip. The higher the bias voltage, the higher the sensitivity, but the stiffness of the plate 162 is important because stiction between the diaphragm 123 and the plate 162 tends to occur.

  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. This variation in capacitance is input to the amplifier A of the circuit chip as a voltage signal and amplified. Since the output of the sensor chip is high impedance, an amplifier A is required in the package.

  Since the substrate 100 and the diaphragm 123 are short-circuited, as shown in FIG. 3A, parasitic capacitance is formed by the plate 162 and the substrate 100 that do not vibrate relatively unless the guard electrode 125a of the guard portion 127 is present. As shown in FIG. 3B, the output terminal of the amplifier A is connected to the guard unit 127, and a voltage follower circuit is configured by the amplifier A, so that no parasitic capacitance is formed by the plate 162 and the substrate 100. That is, by providing the guard electrode 125a between the arm portion 162a and the substrate 100 in a region where the arm portion 162a of the plate 162 and the substrate 100 face each other, the parasitic in the region where the arm portion 162a of the plate 162 and the substrate 100 face each other. Capacity can be reduced. Further, since a guard lead 125d extending from the guard ring 125c connecting the guard electrodes to the guard terminal 125e is wired in a region facing the plate lead 162d extending from the plate 162, the plate lead 162d and the substrate 100 also serve as the wiring. Parasitic capacitance is not formed. The annular guard ring 125 c connects the plurality of guard electrodes 125 a with a substantially shortest path around the diaphragm 123. Further, by forming the guard electrode 125a longer than the arm portion 162a of the plate 162 in the circumferential direction of the plate 162, the parasitic capacitance is further reduced.

  Note that it is also possible to configure the one-chip capacitor microphone 1 by providing elements provided in the circuit chip such as the charge pump CP and the amplifier A in the sensor chip.

3. Manufacturing Method Next, a manufacturing method of the condenser microphone 1 will be described with reference to FIGS.

  In the process shown in FIG. 5, first, a lower insulating film 110 made of silicon oxide 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 made 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. Finally, the lower layer conductive film 120 is etched using a photoresist mask to form the diaphragm 123 and the guard portion 127 made of the lower layer conductive film 120.

  Subsequently, in the process shown in FIG. 6, an upper insulating film 130 made of silicon oxide is formed on the entire surface of the lower insulating film 110 and the lower conductive film 120. Next, 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. Since the silicon nitride film 136 is formed after the polycrystalline silicon film 135 is patterned by a known method, the entire exposed surface of the polycrystalline silicon film 135 protruding from the dimple 130a is covered with the silicon nitride film 136. The silicon nitride film 136 is an insulating film that prevents the diaphragm 123 and the plate 162 from being short-circuited during sticking.

  Subsequently, in the step shown in FIG. 8, an upper conductive film 160 made of polycrystalline silicon is formed on the exposed 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 plate 162, the plate lead 162d, and the etch stopper ring 161 are formed by etching the upper conductive film 160 using a photoresist mask. In this step, the plate hole 162c is not formed.

  Subsequently, in the step shown in FIG. 9, contact holes CH1, CH3, and CH4 are formed in the upper insulating film 130, and then a surface insulating film 170 made of silicon oxide is formed on the entire surface. Further, the contact hole CH2 is formed in the surface insulating film 170 by etching using a photoresist mask, and at the same time, the portion formed at the bottom of the contact holes CH1, CH3, and CH4 of the surface insulating film 170 is removed. Next, a pad conductive film 180 made of AlSi that fills each of the contact holes CH1, CH2, CH3, and CH4 is formed, and is patterned by a well-known method leaving a portion that covers the contact holes CH1, CH2, CH3, and CH4. Further, a pad protective film 190 made of silicon nitride is formed on the surface insulating film 170 and the pad conductive film 180 by the CVD method, and the pad conductive film 190 is patterned by a well-known method so as to remain only around the pad conductive film 180. The

  Subsequently, in the step shown in FIG. 10, through holes 170a 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. Is done. This process is performed continuously, and the surface insulating film 170 in which the through holes 170a are formed functions as a resist mask for the upper conductive film 160.

  Subsequently, in the step shown in FIG. 11, a surface protective film 200 made of silicon oxide is formed on the surface of the surface insulating film 170 and the pad protective film 190. At this time, the through holes 170 a and the plate holes 162 c of the surface insulating film 170 are filled with the surface protective film 200.

  Subsequently, in the step shown in FIG. 12, a bump film 210 made of Ni is formed on the surface of the pad conductive film 180 formed in each of the contact holes CH1, CH2, CH3, and CH4, and the surface of the bump film 210 is made of Au. A bump protective film 220 is formed. Further, at this stage, the back surface of the substrate 100 is ground, and the thickness of the substrate 100 is adjusted to a completed dimension.

  Subsequently, in a step shown in FIG. 13, through holes H5 in which the etch stopper ring 161 is exposed are formed in the surface protective film 200 and the surface insulating film 170 by etching using a photoresist mask.

  The film formation process on the surface side of the substrate 100 is completed through the above steps. In the state where all the film formation processes on the surface side of the substrate 100 have been completed, in the step shown in FIG. 14, a photoresist mask R1 having a through hole H6 for forming a through hole corresponding to the back cavity C1 in the substrate 100 is formed on the substrate 100. Formed on the back surface.

  Subsequently, in a step shown in FIG. 15, through holes are 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, in the step shown in FIG. 16, the photoresist mask R1 is removed, and the wall surface 100c of the through hole roughly formed in the substrate 100 is smoothed by the substrate deep etching.

  Subsequently, in the step shown in FIG. 17, the surface protective film 200 and the surface insulating film 170 on the plate 162 and the plate lead 162d are removed by isotropic etching using the photoresist mask R2 and BHF (dilute hydrofluoric acid). Further, a part of the upper insulating film 130 is removed to form the annular part 132, the first spacer 131 and the gap C3, and a part of the lower insulating film 110 is removed to remove the guard spacer 103, the third spacer 102, and the annular part. The part 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 and the plate lead 162d. That is, the annular portion 132 and the first spacer 131 are formed by self-alignment with the plate 162 and the plate lead 162d. As shown in FIG. 18, an undercut is formed on the end surfaces of the annular portion 132 and the first spacer 131 by isotropic etching. The contour of the lower insulating film 110 is defined by the opening 100a of the substrate 100, the diaphragm 123, the diaphragm lead 123d, the guard electrode 125a, the guard connector 125b, and the guard ring 125c. That is, the guard spacer 103 and the third spacer 102 are formed by self-alignment with the diaphragm 123. Undercuts are formed on the end surfaces of the guard spacer 103 and the first spacer 131 by isotropic etching (see FIGS. 18 and 19). Since the guard spacer 103 and the first spacer 131 are formed in this step, the portion excluding the guard electrode 125a of the second spacer 129 that supports the plate 162 on the substrate 100 is formed in this step.

  Finally, the photoresist mask R2 is removed and the substrate 100 is diced to complete the sensor chip of the condenser microphone 1 shown in FIG. When the sensor chip and the circuit chip are bonded to a package substrate (not shown), the terminals are connected by wire bonding, and a package cover (not shown) is placed on the package substrate, the capacitor microphone 1 is completed. By bonding the sensor chip to the package substrate, the back cavity C1 is hermetically closed on the back side of the substrate 100.

4). Other Embodiments The technical scope of the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention. 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.

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. The circuit diagram concerning 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. 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: condenser microphone, 100: substrate, 100a: opening, 100b: substrate terminal, 101: annular portion, 102: third spacer, 103: guard spacer, 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: guard terminal, 127: guard portion, 129: second spacer, 130: upper insulating film, 130a: dimple, 131: first spacer, 132: annular portion, 160: upper conductive film, 161: etch Stopper ring, 162 Plate, 162a: arm portion, 162b: center portion, 162c: plate hole, 162d: plate lead, 162e: plate terminal, 162f: plate bump, 170: surface insulating film, 180: pad conductive film, 190: pad protective film, 200: surface protective film, 210: bump film, 220: bump protective film, A: amplifier, C1: back cavity, C2: air gap, C3: air gap, CP: charge pump

Claims (9)

A conductive diaphragm made of a deposited film;
A conductive plate composed of a deposited film;
A plurality of columnar first spacers comprising a deposited film joined to the plate, having insulating properties, and supporting the plate with a gap between the diaphragm and the diaphragm;
With
The capacitance formed by the diaphragm and the plate changes as the diaphragm vibrates with respect to the plate.
Vibration transducer. A method of manufacturing a vibration transducer according to claim 1, comprising:
Forming the plate having a plurality of through holes;
By removing a part of the deposited film to be the first spacer by isotropic etching using the plate as a mask, a gap is formed between the plate and the diaphragm, and the first spacer consisting of the remaining portion is removed. Form,
A method of manufacturing a vibration transducer. The plate is formed with a plurality of through holes through which an etchant for simultaneously forming a gap between the plate and the diaphragm and the first spacer by isotropic etching of a deposited film,
The vibration transducer according to claim 1. A substrate,
A conductive diaphragm comprising a deposited film on the substrate;
A conductive plate made of a deposited film on the substrate;
A plurality of pillar-shaped second spacers comprising a deposited film bonded to the substrate and the plate, having insulating properties, and supporting the plate with a gap between the substrate and the substrate;
With
The capacitance formed by the diaphragm and the plate changes as the diaphragm vibrates with respect to the plate.
Vibration transducer. A method of manufacturing a vibration transducer according to claim 4, comprising:
Forming the plate having a plurality of through holes;
A part of the deposited film that becomes the second spacer is removed by isotropic etching using the plate as a mask, thereby forming a gap between the plate and the substrate and forming the second spacer including the remainder. To
A method of manufacturing a vibration transducer. The plate has a plurality of through holes through which an etchant for simultaneously forming a gap between the plate and the substrate and the second spacer by isotropic etching of a deposited film,
The vibration transducer according to claim 4. A conductive diaphragm made of a deposited film;
A plate made of a deposited film, having electrical conductivity and facing the diaphragm;
With
The distance from the center of the plate to the outer edge is shorter than the distance from the center of the diaphragm to the outer edge,
The capacitance formed by the diaphragm and the plate changes as the diaphragm vibrates with respect to the plate.
Vibration transducer. A substrate,
A conductive film comprising a deposited film on the substrate;
A plate comprising a deposited film on the substrate and having conductivity;
A plurality of columnar third spacers comprising a deposited film bonded to the substrate and the diaphragm, having insulating properties and supporting the diaphragm with a gap between the substrate and the substrate;
With
The capacitance formed by the diaphragm and the plate changes as the diaphragm vibrates with respect to the plate.
Vibration transducer. The plate includes a central portion and a plurality of arms extending radially outward from the central portion.
The vibration transducer according to any one of claims 1, 3, 4, 6, 7, and 8.

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