JP2006349478A - Capacitance type dynamic quantity sensor, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitance type dynamic quantity sensor that has a suitable space (cavity) between counter electrodes without requiring a multiple lamination structure and reduces the number of manufacturing processes, and also to provide its manufacturing method. <P>SOLUTION: Comb tooth-like movable electrodes ME1-ME4 and fixed electrodes FE1-FE4 are oppositely arranged in the direction (lateral direction) parallel to the surface of a substrate 1 with certain intervals. The capacity value between the opposite electrodes varies according to the impressed pressure accompanying displacement of a pressure receiving film 2 varying according to the pressure to be applied. At this time, a semiconductor substrate (silicon substrate) is adopted as the substrate 1, the movable electrodes ME1-ME4 and fixed electrodes FE1-FE4 are formed by introducing a conductive impurity to a part of the partially processed substrate 1 according to a desired electrode shape. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a capacitance for detecting a mechanical quantity such as pressure based on a change in capacitance value between electrodes due to displacement of a pressure-receiving film by applying a mechanical quantity from a direction perpendicular to the substrate surface (longitudinal direction). The present invention relates to a type mechanical quantity sensor and a manufacturing method thereof.

  Conventionally, as this type of capacitance-type mechanical quantity sensor, for example, there is a semiconductor pressure sensor described in Patent Document 1. FIG. 18 schematically shows a schematic structure of the sensor described in Patent Document 1. FIG. 18 is an enlarged cross-sectional view showing a part of the cross-sectional structure of the sensor. In the drawing, the white arrow indicates the application mode of pressure to be detected.

  As shown in FIG. 18, this sensor is roughly composed of a substrate 11 made of single crystal silicon, a substrate protection film 12 having etching resistance to protect the surface of the substrate 11, and a movable electrode between the films. Insulating diaphragm films 13 and 14 formed by stacking with ME 10 and thermal stress relaxation film 15 covering all of them are sequentially stacked. Then, a conductive impurity having a desired concentration is introduced into a predetermined position on the surface of the substrate 11 to form fixed electrodes FE11 and FE12 that face the movable electrode ME10.

Further, here, a space (cavity) CB is formed between the substrate protective film 12 and the diaphragm film 13 formed on the surface of the substrate 11 by etching of a sacrificial layer, for example. That is, in such a sensor, when pressure is applied from a direction perpendicular to the surface of the substrate 11 (longitudinal direction), the diaphragm films 13 and 14 are deformed, and the space CB can be swung in the longitudinal direction (up and down in the drawing). Along with this, the distance (vertical gap) between the movable electrode ME10 sandwiched between the diaphragm films 13 and 14 and the fixed electrodes FE11 and FE12 formed on the surface of the substrate 11 also depends on the applied pressure. Variable. In this sensor, such a change in the distance between the electrodes is detected as a change in the capacitance between these electrodes, and this is taken out as a voltage value through a signal processing circuit such as a switched capacitor circuit. Yes. The magnitude of the applied pressure is detected based on the voltage value taken out through the processing circuit.
Japanese Patent Laid-Open No. 2000-214035

  As described above, according to the semiconductor pressure sensor illustrated in FIG. 18, it is possible to detect the application of pressure (mechanical quantity) from the direction (vertical direction) perpendicular to the substrate surface. However, as shown in FIG. 18, the conventional sensor has a multi-layered structure, and a space (cavity) is formed between the movable electrode and the fixed electrode constituting the layered structure. Since it is necessary to form the sensor, many processes (a film forming process, a lithography process, etc.) are required when the sensor is actually manufactured. And in manufacturing this type of sensor, such an increase in the number of processes leads to a decrease in productivity and, in turn, may lead to a decrease in yield and an increase in cost. For this reason, a sensor that can be manufactured with a smaller number of processes is still desired.

  The present invention has been made in view of such circumstances, and an electrostatic space that can reduce the number of manufacturing steps by forming an appropriate space (cavity) between opposing electrodes without using a multi-layered structure. It is an object of the present invention to provide a capacitive mechanical quantity sensor and a manufacturing method thereof.

  In order to achieve such an object, in the invention described in claim 1, a pressure receiving film that is displaced in response to application of a mechanical quantity from a vertical direction that is a direction perpendicular to the substrate surface, and the pressure receiving film that is supported by the substrate. First and second electrodes that change the relative positional relationship with each other in accordance with the displacement of the first and second electrodes, and the applied dynamics based on the change in capacitance value between the first and second electrodes. As a capacitance-type mechanical quantity sensor for detecting a quantity, the first and second electrodes are arranged to face each other at a predetermined interval in a lateral direction that is a direction perpendicular to the longitudinal direction, and the pressure receiving film With this displacement, the capacitance value between the opposed electrodes is changed according to the applied mechanical quantity.

  Thus, by arranging the first and second electrodes in the horizontal direction at a predetermined interval (cavity), it is possible to form these two types of electrodes on the same layer along the substrate surface. Become. That is, if such a structure is adopted, an appropriate space (cavity) is formed between the counter electrodes without using the multi-layered structure as shown in FIG. It is no longer necessary to repeat the film forming process many times. Specifically, for example, an appropriate space (cavity) can be easily formed between the counter electrodes by partially processing (for example, etching) an appropriate electrode material. For this reason, according to such a structure, the number of manufacturing steps can be reduced, and the number of photomasks necessary for manufacturing can be saved.

  In this case, as in the second aspect of the present invention, a semiconductor substrate is employed as the substrate, and the first and second electrodes are partially processed according to a desired electrode shape. By forming the conductive impurity in part, it is not necessary to form an electrode film (for example, a metal film), and the sensor can be manufactured more easily.

In addition, it is possible to adopt various modes as the pressure receiving membrane, for example, according to the invention of claim 3,
A structure in which the pressure receiving film is formed by a film material provided on the surface of the substrate.
Alternatively, as in the invention according to claim 4,
A structure in which the pressure receiving film is formed of a film material provided on the back surface or inside of the substrate.
When the substrate is a semiconductor substrate, as in the invention according to claim 8,
A structure in which the pressure receiving film is formed as a selectively thinned portion of the substrate.
Such a structure can be adopted, and the sensor according to claim 1 or 2 is preferably realized by any structure.

  Further, according to the invention described in claim 5, in the capacitance type mechanical quantity sensor described in claim 4, a sensor that functions as an etch stopper film for the substrate is used as the pressure receiving film. In this case, when the substrate is etched, it is possible to use the etching suppression action of the pressure receiving film, and thus the sensor can be manufactured more easily.

  Further, in this case, as in the invention described in claim 6, an SOI substrate in which a silicon film is formed on a silicon oxide film is adopted as the substrate, and the first and second electrodes are formed by the silicon film. If the pressure receiving film is formed of the silicon oxide film, the sensor can be manufactured more easily using a well-known SOI substrate as a semiconductor device substrate.

  In addition, with respect to the capacitance type mechanical quantity sensor according to any one of claims 1 to 5 including these sensors, silicon is used as the substrate as in the invention according to claim 7. In addition, it is very beneficial to employ silicon oxide as the pressure-receiving film from the viewpoint of performance as a mechanical quantity sensor and from the viewpoint of processing when manufacturing it. More specifically, when silicon, which is a well-known semiconductor, is used as a substrate, for example, as described in claim 2, an electrode can be formed by introducing (doping) a conductive impurity, or the substrate can be formed by etching. Partial processing is also facilitated. On the other hand, since silicon oxide has good compatibility with silicon as the substrate material and is excellent in insulation, even if it is formed so as to be in contact with both the first and second electrodes, these electrodes are used. Will not be conducted. Furthermore, since it has moderate elasticity and flexibility, it can be detected with good response and accuracy even when applying a mechanical quantity as a detection target by adopting it as the pressure receiving film. become able to.

Further, there are roughly two principles of the mechanical quantity sensing of the capacitive mechanical quantity sensor according to any one of claims 1 to 8. That is, one is as in the invention according to claim 9.
The first and second electrodes are arranged opposite to each other on one surface of the pressure receiving film, and the change in capacitance value between the electrodes arranged opposite to each other is due to the bending of the pressure receiving film. A sensor configured to be based on a change in the distance between the first and second electrodes.
And the other is according to the invention of claim 11,
The first and second electrodes are made up of a fixed electrode fixed to the substrate and a movable electrode that is displaced relative to the fixed electrode, and is further arranged oppositely. A sensor configured such that a change in capacitance value between electrodes is based on a change in an opposing area between the fixed electrode and the movable electrode.
It is. In any structure, the sensor according to any one of claims 1 to 8 is preferably realized.

  Further, as described in the ninth aspect, in the case where the mechanical quantity is detected based on the deflection of the pressure receiving film, as in the tenth aspect, both the first and second electrodes are connected. A structure that is formed integrally with the pressure receiving membrane is effective. As a result, the bending of the pressure receiving film is more directly transmitted to the first and second electrodes, and the mechanical quantity applied to the pressure receiving film is the distance between the first and second electrodes. As a change, it becomes more prominent. That is, according to such a structure, the application of the mechanical quantity that is the detection target can be detected more accurately and accurately. In order to realize such a structure, it is particularly effective to use the invention according to claim 8 together with the invention according to claim 10.

  On the other hand, when the mechanical quantity is detected based on the change in the facing area between the fixed and movable electrodes as described in claim 11, the movable electrode is It is effective to make the structure in contact with the pressure receiving film or integrally formed with the pressure receiving film. In this way, in a steady state (when no mechanical quantity is applied), a structure is formed in which no gap is formed between the movable electrode and the pressure receiving film, so that when a mechanical quantity to be detected is applied. The movable electrode is directly pressed by the pressure receiving film under the displacement of the pressure receiving film or is interlocked with the pressure receiving film. For this reason, according to such a structure, it becomes possible to more reliably and responsively detect the application of a mechanical quantity as a detection target.

  Further, in this case, the fixed electrode is formed with a predetermined gap between the fixed electrode and the pressure receiving film as in the invention described in claim 13, so that the pressure receiving film is displaced. This makes it possible to selectively displace only the movable electrode among the counter electrodes. As a result, when a mechanical quantity to be detected is applied, the relative displacement of the fixed electrode and the movable electrode according to the application is more accurately determined as a change in the facing area between the fixed and movable electrodes. In addition, the detection can be performed with high accuracy. It is to be noted that, in order to realize such a structure, it is effective to use the invention described in claim 5 and claim 6 together with the invention described in claim 13.

  Specifically, in the sensor according to any one of claims 11 to 13, for example, as in the invention according to claim 14, the fixed electrode is formed in a comb-like shape integrally with a frame formed by the substrate. In addition, the movable electrode is integrally formed with a mass supported so as to be relatively displaceable with respect to the substrate through a beam in an inner space of the frame penetrated through the substrate. By using a structure having alternating comb teeth, the structure as a mechanical quantity sensor is kept simple and the manufacture thereof is facilitated.

  In addition, the capacitive mechanical quantity sensor according to any one of claims 1 to 14 is a pressure sensor that detects pressure as the applied mechanical quantity, as in the invention according to claim 15. Adopting is especially effective.

On the other hand, the pressure receiving film that is displaced in response to the application of a mechanical quantity from the vertical direction, which is a direction perpendicular to the surface of the semiconductor substrate, and the relative positional relationship with each other according to the displacement of the pressure receiving film while being supported by the substrate A capacitance type mechanical quantity sensor that detects the applied mechanical quantity based on a change in capacitance value between the first and second electrodes. As a manufacturing method, for example, according to the invention of claim 16,
-Etching the surface of the substrate according to the electrode shape of the first and second electrodes, and so that the first and second electrodes are supported only at predetermined locations on the substrate, The step of selectively thinning portions corresponding to these electrodes on the back surface of the substrate and the step of forming a film material that becomes the pressure receiving film are performed in random order, thereby The pressure-receiving film is formed in a form disposed on the surface, and the first and second electrodes are formed in a form opposed to each other at a predetermined interval in a lateral direction that is orthogonal to the vertical direction. how to.
Alternatively, as in the invention according to claim 17,
In order to process the surface of the substrate according to the electrode shape of the first and second electrodes, an etch stopper film is formed on the back surface side of the substrate, and the etching suppression action of the etch stopper film is used. While etching the substrate from the surface side to the etch stopper film, the etch stopper film functions as the pressure-receiving film, and the first and second electrodes are perpendicular to the vertical direction. The method of forming so that it may oppose and arrange | position at predetermined intervals in the horizontal direction.
Alternatively, as in the invention according to claim 19,
An SOI substrate in which a silicon film is formed on a silicon oxide film is prepared as the semiconductor substrate, and the silicon film is used as an electrode of the first and second electrodes while utilizing an etching inhibiting action of the silicon oxide film. Etching is performed according to the shape, and the silicon oxide film is also inhibited from being etched on the surface of the SOI substrate opposite to the silicon film, corresponding to the first and second electrodes. The silicon oxide film functions as the pressure-receiving film by performing an etching process up to the same silicon oxide film while using the first and second electrodes by the silicon film. A method of forming the electrodes so as to be opposed to each other at a predetermined interval in a lateral direction that is an orthogonal direction.
Alternatively, or according to the invention of claim 21,
Etching the surface of the substrate according to the electrode shape of the first and second electrodes, and selectively etching portions corresponding to the first and second electrodes on the back surface of the substrate Forming the first and second electrodes so as to be opposed to each other at a predetermined interval in a lateral direction that is a direction perpendicular to the longitudinal direction, and the pressure-receiving film, Forming as a selectively thinned portion of the substrate.
It is effective to adopt such a method.

Specifically, for example, according to the method described in claim 16, the sensor described in claim 3 can be easily realized.
Moreover, according to the method of the said Claim 17, realization | achievement of the sensor of the said Claim 5 etc. becomes easy. Moreover, in this case, as in the invention described in claim 18, in the method described in claim 17, prior to the step of forming the etch stopper film on the back surface side of the substrate, the first surface on the back surface of the substrate is formed. If the step corresponding to the second electrode and the step of selectively thinning the portion corresponding to the second electrode are further provided, it is possible to easily form an electrode having an arbitrary thickness regardless of the thickness of the substrate. It becomes like this.

On the other hand, according to the method of the nineteenth aspect, the sensor according to the sixth aspect can be easily realized.
On the other hand, according to the method described in claim 20, it is easier to realize the sensor described in claim 8.

  Moreover, according to the invention of claim 21, in the method of manufacturing a capacitive mechanical quantity sensor according to any one of claims 16 to 20, the first and second electrodes are the It consists of a fixed electrode fixed to the substrate and a movable electrode that is displaced relative to the fixed electrode, and only the fixed electrode is selected while keeping the movable electrode in contact with the pressure receiving film. In particular, if the method further includes the step of releasing (separating from) the pressure receiving film, this can be achieved more easily for the sensor of the above-described claim 13.

  In addition, according to the manufacturing method of the capacitive mechanical quantity sensor according to any one of claims 16 to 21, the pressure is detected as the applied mechanical quantity as in the invention according to claim 22. It is particularly effective when used in a pressure sensor.

(First embodiment)
A first embodiment that embodies a capacitance type mechanical quantity sensor and a method for manufacturing the same according to the present invention will be described below with reference to FIGS. As the sensor according to this embodiment, a semiconductor pressure sensor that detects application of pressure (mechanical quantity) from a direction (longitudinal direction) perpendicular to the substrate surface is assumed as in the sensor illustrated in FIG. is doing. However, in this embodiment, as shown in FIG. 1, by forming an appropriate space (cavity) between the counter electrodes regardless of the multi-layered structure, the number of steps in manufacturing the sensor can be reduced. Reduction has been realized.

  First, with reference to FIG. 1, the schematic structure of the capacitance type mechanical quantity sensor according to this embodiment, and particularly the electrode structure thereof will be described in detail. In FIG. 1, FIG. 1A is a plan view of the sensor element, and FIG. 1B is a cross-sectional view taken along line BB in FIG. 1A.

  As shown in FIGS. 1 (a) and 1 (b), this sensor mainly includes a substrate 1 made of, for example, single crystal silicon, and a pressure receiving film (diaphragm) made of silicon oxide formed on the substrate 1. ) 2. Of these, the substrate 1 is processed by a known lithography technique or the like, and a conductive impurity is selectively introduced into a predetermined portion of the substrate 1 to form a weight portion. A mass M, a counter electrode for detecting the applied pressure as a capacitance value, or the like, that is, movable electrodes ME1 to ME4, fixed electrodes FE1 to FE4, and the like are formed.

  More specifically, the substrate 1 serving as a base is rolled up to form a frame by the substrate 1. The fixed electrodes FE1 to FE4 are formed in a comb-like shape integrally with the frame of the substrate 1, and the mass M passes through beams B1 to B4 in the inner space of the frame penetrated by the substrate 1. The substrate 1 is supported so as to be relatively displaceable. On the other hand, the movable electrodes ME <b> 1 to ME <b> 4 are formed integrally with the mass M so as to have an alternating comb tooth shape with the fixed electrodes FE <b> 1 to FE <b> 4. Thus, the pressure receiving film 2 is provided so as to cover all of the fixed electrodes FE1 to FE4, the mass M, the movable electrodes ME1 to ME4, and the inner space of the frame through which the substrate 1 is penetrated.

  As described above, in this embodiment, the movable electrodes ME1 to ME4 and the fixed electrodes FE1 to FE4 are arranged to face each other at a constant interval in the direction parallel to the surface of the substrate 1 (lateral direction).

  As shown in FIG. 1B, the movable electrodes ME1 to ME4 and the fixed electrodes FE1 to FE4 are all in contact with the pressure receiving membrane 2 in a steady state (when no mechanical quantity is applied). It is in the state. Thereby, when a pressure is applied from a direction (longitudinal direction) perpendicular to the surface of the substrate 1, the movable electrodes ME1 to ME4 are pressed directly and accurately against the pressure receiving film 2, and as a result, these movable electrodes A displacement corresponding to the displacement (vertical displacement) of the pressure-receiving film 2 accompanying the application of the pressure can be generated more reliably with respect to ME1 to ME4.

  Next, the detection principle of this sensor will be described with reference to FIGS. 2 and 3 are cross-sectional views corresponding to FIG. 1B, and in each of these drawings, the same or corresponding elements as those shown in FIG. For convenience, the same or corresponding reference numerals are given.

As shown in each of these figures, this sensor detects pressure applied from the direction (longitudinal direction) perpendicular to the surface of the substrate 1 mainly by the following two principles.
That is, as shown in FIGS. 2A and 2B, one changes the capacitance value between these counter electrodes based on the change in the counter area between the movable electrode ME and the fixed electrode FE. The applied pressure is detected based on a change in capacitance value. Specifically, in the steady state (when no mechanical quantity is applied), as shown in FIG. 2A, both the movable electrode ME and the fixed electrode FE are in contact with the pressure receiving film 2 on the same plane. Is in a state. However, when a pressure in the vertical direction is applied to the pressure receiving film 2, the movable electrode ME that is allowed to be displaced in the vertical direction via the beam is a substrate as shown in FIG. Displacement is greater in the direction in which the pressure is applied than the fixed electrode FE fixed to the electrode. That is, the facing area between the movable electrode ME and the fixed electrode FE is reduced by the amount of displacement of the movable electrode ME relative to the fixed electrode FE (the relative displacement amount DW in FIG. 2B). Will do. In addition, at this time, the relative displacement amount DW corresponds to the magnitude of the applied pressure. For this reason, such a change in the facing area between the opposing electrodes is detected as a change in electrostatic capacity between these electrodes (the larger the facing area, the larger the electrostatic capacity), for example, a switched capacitor circuit or the like. By extracting this as a voltage value through the signal processing circuit, the magnitude of the applied pressure can be obtained.

  That is, although illustration is omitted in FIG. 1 for convenience, in more detail, the sensor according to this embodiment has such a signal processing circuit as a peripheral circuit. Then, for example, a required number of pads (also not shown) for drawing out the potentials of the movable electrodes ME1 to ME4 and the fixed electrodes FE1 to FE4 are provided on the frame portion of the substrate 1 or on the mass M, for example. The capacitance value between the electrodes is output from these pads to the signal processing circuit.

  On the other hand, another principle is that, as shown in FIG. 3, the capacitance value between the counter electrodes is changed based on the change in the distance between the movable electrode ME and the fixed electrode FE due to the bending of the pressure receiving film 2. The applied pressure is detected based on the change in the capacitance value. That is, when a vertical pressure is applied to the pressure receiving film 2, the pressure receiving film 2 bends as shown in FIG. The bending of the pressure receiving film 2 is transmitted to the electrodes ME and FE via the contact surface (friction force), and these electrodes are also displaced with the same tendency. Specifically, according to the magnitude of the applied pressure, the distance between the movable electrode ME and the fixed electrode FE arranged opposite to each other changes. For this reason, such a change in the distance between the counter electrodes is also detected as a change in the capacitance between these electrodes.

  Thus, the above two principles mainly act as the detection principle of the sensor. However, in the sensor according to this embodiment, the influence of the principle shown in FIG. 2 (change in the facing area between the electrodes) is particularly strong, and basically pressure is detected based on this principle. . However, depending on the film thickness, material, or arrangement state of the pressure receiving film 2, the influence of the principle shown in FIG. 3 (change in the distance between the electrodes) appears, so in the signal processing, Various calculations are performed in consideration of the influence of this principle.

  As shown in FIG. 1A, the beams B1 to B4 are formed in such a manner that displacement in two directions (X-axis and Y-axis directions) orthogonal to the Z-axis (longitudinal direction) is restricted. , It is possible to selectively detect the application of pressure from the Z-axis (longitudinal direction). Further, if the pressure receiving film 2 is provided in such a manner that the displacement in the X-axis and Y-axis directions is regulated (for example, this is regulated by frictional force or adhesive force) without being regulated by the beam structure, Similarly, it is possible to selectively detect the application of pressure from the Z axis (vertical direction).

  In this sensor, the range (detection range) of the pressure to be detected can be changed and adjusted as appropriate by changing the film thickness and material of the pressure receiving film 2 or the width of the beams B1 to B4. . Further, in order to more reliably prevent the comb-like counter electrode from being damaged, the portion of the pressure receiving film 2 that receives the pressure is limited to the region A indicated by the one-dot chain line in FIG. Is more effective.

  Next, with reference to FIG. 4, the manufacturing method of the capacitance-type mechanical quantity sensor according to this embodiment will be described in detail. 4A to 4D are cross-sectional views corresponding to FIG. 1B.

  As shown in FIG. 4A, when manufacturing this sensor, the substrate 1 is first etched from the surface side, and the surface of the substrate 1 is moved to the mass M, beams B1 to B4, and further movable. While processing into the structure corresponding to the electrode shape of electrode ME1-ME4 and fixed electrode FE1-FE4, an appropriate conductivity type impurity is selectively introduce | transduced with respect to the predetermined location of the board | substrate 1. FIG. As a result, the surface of the substrate 1 has a shape corresponding to the shape of each of the comb-shaped electrodes, and conductivity is imparted to a desired portion of the substrate 1. At this time, in order to prevent sticking between the counter electrodes (movable / fixed electrodes), it is particularly effective to employ dry etching (such as RIE) as an etching method.

  Next, as shown in FIG. 4B, the portion corresponding to each of the electrodes on the back surface of the substrate 1 is selectively removed by, for example, wet etching to form a thin film. As a result, the movable electrodes ME1 to ME4 and the fixed electrodes FE1 to FE4 are supported only at predetermined locations on the substrate 1 (see FIG. 1A).

  Next, as shown in FIG. 4C, the pressure receiving film 2, that is, a silicon oxide film is formed on the surface of the substrate 1. At this time, the pressure receiving film 2 may be formed by well-known CVD (chemical vapor deposition) or by attaching a film material (silicon oxide film).

If necessary, the glass pedestal 3 is bonded to the back surface of the substrate 1 by, for example, anodic bonding, as shown in FIG.
In this embodiment, the sensor shown in FIG. 1 is completed through the above steps. However, the step of etching the surface of the substrate 1 according to the electrode shape of the counter electrode (FIG. 4A), the step of introducing (doping) conductive impurities into a predetermined portion of the substrate 1, and the back surface of the substrate 1 The step of thinning (FIG. 4B) and the step of forming the pressure receiving film 2 (FIG. 4C) can be performed in any order. That is, for example, as shown in FIGS. 5A to 5D, even when the back surface of the substrate 1 is thinned after the pressure-receiving film 2 is formed, the manufacture of FIGS. The sensor shown in FIG. 1 can be manufactured in a manner similar to or equivalent to the method. Alternatively, as shown in FIGS. 6A to 6D, when the back surface of the substrate 1 is thinned, the surface of the substrate 1 is etched according to the electrode shape of the counter electrode. The sensor shown in FIG. 1 can be manufactured in a manner similar to or equivalent to the manufacturing method of (a) to (d). It should be noted that the introduction (doping) of the conductive impurities can be performed at a desired location on the substrate 1 by penetrating the pressure receiving film 2 by ion implantation, for example, even after the pressure receiving film 2 is formed.

According to the capacitance type mechanical quantity sensor and the manufacturing method thereof according to this embodiment as described above, the following excellent effects can be obtained.
(1) As shown in FIG. 1, the movable electrodes ME1 to ME4 and the fixed electrodes FE1 to FE4 are arranged to face each other at a certain interval in a direction parallel to the surface of the substrate 1 (lateral direction). In accordance with the displacement of the pressure receiving film 2 that is displaced according to the application of pressure, the capacitance value between the electrodes arranged opposite to each other is changed according to the applied pressure. In this way, the movable electrodes ME1 to ME4 and the fixed electrodes FE1 to FE4, which are the counter electrodes, are arranged in the horizontal direction at a predetermined interval (cavity), so that these two types of electrodes are aligned along the substrate surface. It becomes possible to form on one layer. That is, in the multi-layered structure as shown in FIG. 18 described above, it is possible to greatly reduce the film forming process of electrodes and the like that had to be repeated many times. Specifically, as shown in FIG. 4 and the like, the substrate 1 is partially processed and a predetermined conductivity type impurity is introduced (doping) into the substrate 1 so that an appropriate gap between the counter electrodes can be easily obtained. A space (cavity) is formed. For this reason, according to such a structure, the number of manufacturing steps can be reduced, and the number of photomasks necessary for manufacturing can be saved.

  (2) Further, a semiconductor substrate (silicon substrate) is adopted as the substrate 1, and a part of the substrate 1 in which the movable electrodes ME1 to ME4 and the fixed electrodes FE1 to FE4 are partially processed according to a desired electrode shape. By forming a conductive impurity by introducing a conductive impurity, it is not necessary to form an electrode film (for example, a metal film). That is, the sensor can be manufactured more easily.

  (3) Furthermore, by adopting insulating silicon oxide as the pressure-receiving film 2, these electrodes are formed in contact with both the movable electrodes ME1 to ME4 and the fixed electrodes FE1 to FE4. There is no conduction. Furthermore, since this silicon oxide has moderate elasticity and flexibility, it has been adopted as the pressure-receiving film 2, so that it can be applied to the pressure to be detected in a responsive and accurate manner. Can be detected.

  (4) As shown in FIGS. 2 and 3, the capacitance value between the opposing electrodes is changed based on the change in the opposing area between the electrodes and the change in the distance between the electrodes, and based on the change in the capacitance value. The applied pressure was detected. By these principles, the pressure that is the detection target is detected with high accuracy.

  (5) The movable electrodes ME1 to ME4 are formed in contact with the pressure receiving film 2 together with the fixed electrodes FE1 to FE4. In this way, in a steady state (when no pressure is applied), a structure is formed in which no gap is formed between the movable electrodes ME1 to ME4 and the pressure receiving film 2, so that the pressure to be detected is applied. The movable electrodes ME1 to ME4 are directly pressed by the pressure receiving film 2 together with the displacement of the pressure receiving film 2. For this reason, according to such a structure, it becomes possible to more reliably and responsively detect the application of pressure as a detection target.

  (6) Further, as shown in detail in FIG. 1, the fixed electrodes FE1 to FE4 are formed in a comb-teeth shape integrally with the frame of the substrate 1, and the movable electrodes ME1 to ME4 are further formed on the substrate 1. It was set as the structure formed in the inner space of the said frame penetrated through integrally with the mass M, and having the said fixed electrodes FE1-FE4 and alternate comb-tooth shape. Thereby, the structure as the pressure sensor is kept simple and the manufacture thereof is facilitated.

  (7) With respect to the movable electrodes ME1 to ME4 and the fixed electrodes FE1 to FE4, displacement in two axial directions (two horizontal directions) orthogonal to the vertical direction is regulated (for example, frictional force of the pressure receiving film 2 or beams B1 to B1). It is possible to selectively detect the application of pressure from the vertical direction.

  (8) By applying the present invention to the pressure sensor, a pressure sensor that can be manufactured with a smaller number of processes and having a completely different structure from that of the conventional sensor is preferably realized.

  (9) Further, as a method for manufacturing such a capacitance type mechanical quantity sensor, a process of etching the surface of the substrate 1 in accordance with the electrode shape of each electrode (FIG. 4A), each electrode on the back surface of the substrate 1 It was decided to adopt a method of sequentially performing the step of thinning the portion corresponding to (FIG. 4B) and the step of forming the pressure-receiving film 2 (FIG. 4C). According to such a method, it is easy to realize a sensor having the above structure.

(Second Embodiment)
Next, with reference to FIG. 7 and FIG. 8, a second embodiment that embodies the capacitance-type mechanical quantity sensor and the method for manufacturing the same according to the present invention will be described. However, as shown in FIG. 7, the sensor according to this embodiment also basically has a structure similar to the sensor of the first embodiment (FIG. 1). Only the differences from the sensor of the first embodiment will be mainly described.

  First, with reference to FIG. 7, the schematic structure of the capacitance type mechanical quantity sensor according to this embodiment, and particularly the electrode structure thereof will be described in detail. FIG. 7 is a cross-sectional view corresponding to FIG. Further, regarding the planar structure, only the planar structure shown in FIG. 1 is changed according to the change in the cross-sectional structure shown in FIG. 7, and therefore illustration and description thereof are omitted here for convenience.

  As shown in FIG. 7, this sensor is formed on an SOI substrate in which a silicon film 1a is formed on a silicon oxide film (pressure receiving film 2). Specifically, for example, a lower layer 1b made of single crystal silicon and The pressure receiving film 2 made of silicon oxide and the silicon film 1a made of single crystal silicon are sequentially stacked. That is, the pressure receiving film 2 is formed not by the surface of the substrate but by a film material (silicon oxide film) provided inside the substrate.

  Also in this embodiment, as in the first embodiment, the substrate 1 is processed as desired by a well-known lithography technique or the like, and is selectively conductive to a predetermined portion of the substrate 1. By introducing the mold impurity, the surface of the substrate 1 is processed into a shape corresponding to the sensor structure. That is, a movable electrode (only ME1 is shown), a fixed electrode (only FE1 is shown), a mass (see FIG. 1A), a beam (only B1 is shown), and the like are formed on the surface of the substrate 1. Further, as shown in FIG. 7, also in this embodiment, in a steady state (when no mechanical quantity is applied), the movable electrode and the fixed electrode are in contact with the pressure receiving film 2. It has been.

  Next, with reference to FIG. 8, the manufacturing method of the capacitive mechanical quantity sensor according to this embodiment will be described in detail. 8A and 8B are cross-sectional views corresponding to FIG.

  As shown in FIG. 8A, when manufacturing this sensor, first, the silicon film 1a on the substrate surface side is etched while utilizing the etching inhibiting action of the silicon oxide film (pressure receiving film 2). Then, the silicon film 1a is processed into a structure corresponding to the shape of the mass, the beam, and the movable electrode and the fixed electrode. Then, appropriate conductivity type impurities are selectively introduced into predetermined portions of the silicon film 1a. As a result, the comb-like movable electrode and the fixed electrode supported only at a predetermined portion (see FIG. 1A) of the substrate are formed, and the conductive portion is electrically connected to a desired portion of the silicon film 1a. Sex will be given.

  Next, as shown in FIG. 8B, the etching inhibiting action of the silicon oxide film (pressure receiving film 2) is also used for the portions corresponding to the electrodes on the back side of the substrate (lower layer 1b). While etching the silicon oxide film. As a result, an appropriate space is formed in the vertical direction (vertical direction in the drawing) of the silicon oxide film, and the silicon oxide film functions properly as the pressure-receiving film 2, so that the sensor shown in FIG. Will be completed.

If necessary, also in this embodiment, the glass pedestal 3 as shown in FIG. 4D is bonded to the back side of the substrate by, for example, anodic bonding.
As described above, according to the capacitance type mechanical quantity sensor and the manufacturing method thereof according to this embodiment, the same effects as the effects (1) to (8) according to the first embodiment, or the same effect. In addition to the similar effects, the following effects can be obtained.

  (10) An SOI substrate in which a silicon film 1a is formed on a silicon oxide film is adopted as the substrate of the sensor, and the movable electrode and the fixed electrode are formed by the silicon film 1a of the SOI substrate, and the pressure receiving The film 2 is formed by the silicon oxide film of the SOI substrate. As a result, the sensor can be more easily manufactured using a well-known SOI substrate as the substrate of the semiconductor device.

  (11) Further, when the substrate is etched, it is possible to use the action of inhibiting the etching of the silicon oxide film (pressure receiving film 2), and thus the sensor can be manufactured more easily. become.

  (12) Further, when manufacturing such a capacitance type mechanical quantity sensor, the silicon film 1a of the SOI substrate is fixed to the movable electrode and the fixed electrode while utilizing the etching inhibiting action of the silicon oxide film of the SOI substrate. Etching is performed according to the electrode shape. Then, the etching process up to the silicon oxide film is also performed on the portion corresponding to each electrode on the surface opposite to the silicon film 1a of the SOI substrate while utilizing the etching inhibiting action of the silicon oxide film. We decided to adopt the method of doing. According to such a method, it is easy to realize a sensor constituted by the above structure.

(Third embodiment)
Next, with reference to FIG. 9 and FIG. 10, a third embodiment that embodies the capacitance-type mechanical quantity sensor and the method for manufacturing the same according to the present invention will be described. However, as shown in FIG. 9, the sensor according to this embodiment also basically has a structure similar to that of the sensor of the second embodiment (FIG. 7). Only differences from the sensor of the second embodiment will be mainly described.

  First, the schematic structure of the capacitance type mechanical quantity sensor according to this embodiment will be described in detail with reference to FIG. FIG. 9 is also a cross-sectional view corresponding to FIG. Further, regarding the planar structure, only the planar structure shown in FIG. 1 is changed in accordance with the change in the cross-sectional structure shown in FIG. 9, and therefore illustration and description thereof are omitted here for convenience.

  As shown in FIG. 9, this sensor is also composed of an SOI substrate in which a silicon film 1a is formed on a silicon oxide film (pressure receiving film 2), as in the sensor of the second embodiment. . However, in this embodiment, only the movable electrode (only ME1 is shown) is brought into contact with the pressure receiving film 2, and the fixed electrode (only FE1 is shown) and the beam (only B is shown) are used as the pressure receiving pressure. It is assumed that a predetermined gap is formed between the film 2 and the film 2. By doing so, only the movable electrode of these counter electrodes is selectively displaced in conjunction with the displacement of the pressure receiving film 2.

  Next, with reference to FIG. 10, the manufacturing method of the capacitive mechanical quantity sensor according to this embodiment will be described in detail. 10A and 10B are cross-sectional views corresponding to FIG.

  As shown in FIG. 10 (a), in manufacturing the sensor, first, the silicon film 1a on the substrate surface side is etched while utilizing the etching inhibiting action of the silicon oxide film (pressure receiving film 2). Then, the silicon film 1a is processed into a structure corresponding to the shape of the mass, the beam, and the movable electrode and the fixed electrode. However, in this embodiment, at this time, the fixed electrode and the beam are selectively released (separated) from the pressure receiving film 2. Specifically, for example, the selective etching is performed by designing the width of the movable electrode to be somewhat larger than the fixed electrode. Subsequently, by selectively introducing appropriate conductivity type impurities into a predetermined portion of the silicon film 1a, the silicon film 1a is supported only at the predetermined portion of the substrate (see FIG. 1A). The comb-shaped movable electrode and fixed electrode are formed, and conductivity is imparted to a desired portion of the silicon film 1a.

  Next, as shown in FIG. 10B, the etching inhibiting action of the silicon oxide film (pressure receiving film 2) is also used for the portions corresponding to the electrodes on the back side of the substrate (lower layer 1b). While etching the silicon oxide film. As a result, an appropriate space is formed in the vertical direction (vertical direction in the drawing) of the silicon oxide film, and the silicon oxide film functions properly as the pressure-receiving film 2, so that the sensor shown in FIG. Will be completed.

If necessary, also in this embodiment, the glass pedestal 3 as shown in FIG. 4D is bonded to the back side of the substrate by, for example, anodic bonding.
As described above, according to the capacitive mechanical quantity sensor and the manufacturing method thereof according to this embodiment, the same effects as the effects (1) to (8) and (10) to (12) or In addition to the similar effects, the following effects can be obtained.

  (13) As shown in FIG. 9, only the movable electrode (only ME 1 is shown) is brought into contact with the pressure receiving film 2, and the fixed electrode (only FE 1 is shown) is connected to the pressure receiving film 2 with a predetermined gap. It was supposed to be formed with a gap. Thereby, when a mechanical quantity as a detection target is applied, only the movable electrode among the counter electrodes is selectively displaced, and the relative displacement of the fixed electrode and the movable electrode according to the application is The change in the facing area between the fixed and movable electrodes can be detected more accurately and accurately.

  (14) Further, when manufacturing such a capacitance type mechanical quantity sensor, only the fixed electrode is selectively selected from the movable electrode and the fixed electrode while keeping the movable electrode in contact with the pressure receiving film 2. It was made to release from the pressure receiving membrane 2. According to such a method, it is easy to realize a sensor having the above structure.

(Fourth embodiment)
Next, with reference to FIG. 11 and FIG. 12, a fourth embodiment in which the capacitance type mechanical quantity sensor and the manufacturing method thereof according to the present invention are embodied will be described. However, as shown in FIG. 11, the sensor according to this embodiment also basically has a structure similar to the sensor of the first embodiment (FIG. 1). Only the differences from the sensor of the first embodiment will be mainly described.

  First, the schematic structure of the capacitance type mechanical quantity sensor according to this embodiment will be described in detail with reference to FIG. FIG. 11 is a cross-sectional view corresponding to FIG. Further, regarding the planar structure, only the planar structure shown in FIG. 1 is changed according to the change of the cross-sectional structure shown in FIG. 11, and therefore, illustration and description thereof are omitted here for convenience.

  As shown in FIG. 11, in this sensor, a pressure receiving film (diaphragm) 2 that is displaced in response to the application of pressure is not a surface of the substrate 1 but a film material (silicon oxide) provided on the back surface of the substrate 1. Film).

  Also in this embodiment, as in the first embodiment, the substrate 1 is processed as desired by a well-known lithography technique or the like, and is selectively conductive to a predetermined portion of the substrate 1. By introducing the mold impurity, the surface of the substrate 1 is processed into a shape corresponding to the sensor structure. That is, a movable electrode (only ME1 is shown), a fixed electrode (only FE1 is shown), a mass (see FIG. 1A), a beam (only B1 is shown), and the like are formed on the surface of the substrate 1. Further, as shown in FIG. 11, also in this embodiment, in a steady state (when no mechanical quantity is applied), the movable electrode and the fixed electrode are in contact with the pressure receiving film 2. It has been.

  Next, with reference to FIG. 12, the manufacturing method of the capacitive mechanical quantity sensor according to this embodiment will be described in detail. 12A to 12C are cross-sectional views corresponding to FIG.

  As shown in FIG. 12 (a), when manufacturing this sensor, first, for example, the portion corresponding to the movable electrode and the fixed electrode on the back surface of the substrate 1 made of single crystal silicon is selectively etched. Thin film. Next, as shown in FIG. 12B, the silicon oxide film (pressure receiving film 2) is formed on the back surface of the substrate 1.

  Then, in this state, next, as shown in FIG. 12C, etching is performed from the substrate surface side to the silicon oxide film while utilizing the etching inhibiting action of the silicon oxide film (pressure receiving film 2). Subsequently, appropriate conductivity type impurities are selectively introduced into a predetermined portion of the substrate 1. As a result, the comb-like movable electrode and the fixed electrode supported only at a predetermined location (see FIG. 1A) of the substrate 1 are formed, and the desired location on the substrate 1 is conductive. Thus, the sensor shown in FIG. 11 is completed.

If necessary, also in this embodiment, the glass pedestal 3 as shown in FIG. 4D is bonded to the back side of the substrate by, for example, anodic bonding.
As described above, according to the capacitance type mechanical quantity sensor and the manufacturing method thereof according to this embodiment, the same effects as the effects of (1) to (8) and (11) or the effects equivalent thereto. In addition, the following effects can be obtained.

  (15) As a method of manufacturing a capacitance type pressure sensor, a silicon oxide film (pressure receiving film 2) serving as an etch stopper film is formed on the back surface side of the substrate 1, and this silicon oxide film is prevented from being etched. A method of etching the substrate 1 from the surface side to the same silicon oxide film is employed while being utilized. According to such a method, it is easy to realize a sensor constituted by the above structure.

  (16) Prior to the formation of the silicon oxide film (pressure receiving film 2) on the back surface side of the substrate 1, the portion corresponding to the movable electrode and the fixed electrode on the back surface of the substrate 1 is selectively etched to reduce the thickness. I did it. Thereby, as the movable electrode and the fixed electrode, an electrode having an arbitrary thickness that does not depend on the thickness of the substrate 1 can be formed more easily and appropriately.

(Fifth embodiment)
Next, with reference to FIG. 13 and FIG. 14, a fifth embodiment that embodies the capacitance-type mechanical quantity sensor and the method for manufacturing the same according to the present invention will be described. However, as shown in FIG. 13, the sensor according to this embodiment basically has a structure similar to that of the sensor of the first embodiment (FIG. 1). Only the differences from the sensor of the first embodiment will be mainly described.

  First, the schematic structure of the capacitance type mechanical quantity sensor according to this embodiment will be described in detail with reference to FIG. FIG. 13 is a cross-sectional view corresponding to FIG. Further, regarding the planar structure, only the planar structure shown in FIG. 1 is changed in accordance with the change in the cross-sectional structure shown in FIG. 13, and therefore illustration and description thereof are omitted here for convenience.

  As shown in FIG. 13, in this sensor, a pressure receiving film (diaphragm) 2 that is displaced in response to application of pressure is formed as a selectively thinned portion of a substrate 1 made of, for example, single crystal silicon. ing. That is, the pressure receiving film 2 formed by a part of the substrate 1 is integrally formed with electrodes and beams that are also formed as a part of the substrate 1.

  As described above, in this embodiment, both the counter electrodes are formed integrally with the pressure-receiving film 2 and both of these electrodes are fixed to the substrate 1, so that the movable electrode and the fixed electrode described above are no longer used. There is no distinction. For this reason, the reference numerals of these two types of electrodes forming the counter electrode are indicated by the same reference numerals as those in FIG. 1, but the names of these electrodes are hereinafter referred to as “movable electrode” and “fixed”. “Electrode” is changed to “first electrode” and “second electrode”, respectively.

  Further, the principle shown in FIG. 2 (change in the facing area between the electrodes) no longer works, and in such a sensor structure, the principle shown in FIG. 3 (change in the distance between the electrodes) is used. Thus, the pressure is detected, and these electrodes are integrated with the pressure-receiving membrane 2 so that the sensor sensitivity is further enhanced.

  Also in this embodiment, as in the first embodiment, the substrate 1 is processed as desired by a well-known lithography technique or the like, and is selectively conductive to a predetermined portion of the substrate 1. By introducing the mold impurity, the surface of the substrate 1 is processed into a shape corresponding to the sensor structure. That is, on the surface of the substrate 1, in addition to the first electrode (only ME1 shown), the second electrode (only FE1 shown), and the beam (only B1 shown), the mass shown in FIG. (Not shown) and the like are formed.

  Next, with reference to FIG. 14, the manufacturing method of the capacitive mechanical quantity sensor according to this embodiment will be described in detail. 14A and 14B are cross-sectional views corresponding to FIG.

  As shown in FIG. 14 (a), when manufacturing this sensor, the substrate 1 is first etched from the surface side, and the surface of the substrate 1 is changed to the above-mentioned mass and beams, and further to the first and second. While processing into the structure corresponding to the electrode shape of an electrode, the appropriate conductivity type impurity is selectively introduce | transduced with respect to the predetermined location of the board | substrate 1. FIG. As a result, the surface of the substrate 1 has a shape corresponding to the shape of each of the comb-shaped electrodes, and conductivity is imparted to a desired portion of the substrate 1.

  Next, as shown in FIG. 14B, the portions corresponding to the respective electrodes on the back surface of the substrate 1 are selectively etched to be thinned. As a result, the selectively thinned portion of the substrate 1 functions as the pressure receiving film 2, and the portion processed into a comb-like shape on the surface of the substrate 1 is integrated with the pressure receiving film 2. In this state, the sensor is formed so as to function as the first and second electrodes, whereby the sensor shown in FIG. 13 is completed.

Further, if necessary, also in this embodiment, the glass pedestal 3 as shown in FIG. 4D is bonded to the back side of the substrate 1 by, for example, anodic bonding.
As described above, according to the capacitance type mechanical quantity sensor and the manufacturing method thereof according to this embodiment, the above (1) and (2) and (6) to (8) according to the first embodiment. In addition to the same effect as or an effect equivalent thereto, the following effect can also be obtained.

  (17) A pressure receiving film (diaphragm) 2 that is displaced in response to the application of pressure is formed as a selectively thinned portion of the substrate 1, and a change in the distance between the electrodes due to the bending of the pressure receiving film 2 (FIG. 3), the capacitance value between the counter electrodes is changed, and the applied pressure is detected based on the change in the capacitance value. According to such a principle, the pressure to be detected is detected with high accuracy.

  (18) Since both the first and second electrodes are formed integrally with the pressure receiving film 2, the bending of the pressure receiving film 2 is more directly applied to the first and second electrodes. Thus, the pressure applied to the pressure-receiving film 2 becomes more prominent as a change in the distance between the first and second electrodes. That is, by adopting such a structure, it is possible to more accurately and accurately detect the application of pressure as a detection target.

(Other embodiments)
Each of the above embodiments may be modified as follows.
In the first to fourth embodiments, the movable electrode is brought into contact with the pressure receiving film. However, the movable electrode may be formed integrally with the pressure receiving film. In addition, in this case, the movable electrode is integrally interlocked with the pressure receiving film, and as a result, the displacement of the pressure receiving film is more reliably transmitted to the movable electrode than in the case of contact. Further, even when a slight gap is formed between the movable electrode and the pressure receiving film, the gap is applied when the movable electrode is pressed by the bending of the pressure receiving film accompanying the application of pressure. If the displacement corresponding to the magnitude of the pressure is within a range that can occur in the same electrode, it is possible to detect the pressure to be detected based on the change in the facing area between the electrodes (see FIG. 2). It is.

  The planar structure as the capacitance type mechanical quantity sensor is not limited to the structure illustrated in FIG. 1A, but, for example, as shown in FIG. A structure in which two types of electrodes ED1 and ED2 arranged to face each other in a form in which a frame made of an electrode material is continuous can be appropriately employed. Further, the shape of such a frame is not limited to the rectangular shape shown in FIG. 15, but is a frame of another polygonal shape (for example, a hexagonal shape or an octagonal shape), or a circular shape as shown in FIG. A (concentric circle) frame or the like can be appropriately employed as the shape of the counter electrode.

Further, as shown in FIG. 17 as an example, the counter electrodes ED1 and ED2 may have a structure in which they are alternately wound (in a spiral shape).
Note that these structures can be appropriately employed even when the counter electrodes ED1 and ED2 function as the movable electrode and the fixed electrode described above or when they do not function. In short, based on the principle of at least one of a change in the opposed area between the electrodes based on the relative displacement of the opposed electrode (see FIG. 2) and a change in the distance between the electrodes due to the deformation of the pressure receiving film (see FIG. 3), It is sufficient if the capacitance value between the electrodes can be changed and the applied pressure can be detected based on the change in the capacitance value.

  -Also, as a method of supporting these counter electrodes, any method can be adopted without being limited to the above-mentioned beam. Further, it is not necessary to directly fix the substrate itself, and these counter electrodes may be fixed to a pressure receiving film, for example.

Further, it is not necessary to form such a counter electrode with the same material as the substrate, and an electrode material (for example, metal) may be formed separately from the substrate.
Furthermore, as wiring methods for these electrodes and the like, aerial wiring (wiring that intersects three-dimensionally through an air gap without an insulating film between wirings) can be used.

  The material of the substrate used for manufacturing the sensor is not limited to the silicon, and a substrate of any material can be adopted. However, in practical use, it is desirable to use a semiconductor material that is excellent in workability. Furthermore, it is beneficial to use a material known as a semiconductor device material in terms of performance and cost.

  Further, as the material of the pressure receiving film, any film can be adopted according to the installation environment. That is, in addition to the single crystal silicon and silicon oxide described above, for example, polycrystalline silicon can also be employed as the material of the pressure receiving film. However, in view of preventing conduction of the counter electrode, it is desirable to provide an insulating property to the pressure receiving film in contact with at least one of these electrodes.

  The intended purpose of reducing the number of manufacturing steps can be achieved only by arranging the counter electrodes at predetermined intervals in the lateral direction without depending on the detection principle. That is, even if a principle other than the detection principle described above (the principle shown in FIGS. 2 and 3) is adopted, this object can be achieved.

1A is a plan view schematically showing a schematic structure of the capacitance type mechanical quantity sensor and its manufacturing method according to the present invention, and FIG. Sectional drawing along line -B. Sectional drawing which shows typically one of the detection principles about the sensor which concerns on the same 1st Embodiment. Sectional drawing which shows typically the detection principle different from the principle of FIG. 2 about the sensor which concerns on the said 1st Embodiment. (A)-(d) is sectional drawing which shows typically the manufacturing process about the manufacturing method of the sensor which concerns on the 1st Embodiment. FIGS. 5A to 5D are cross-sectional views schematically showing a manufacturing process different from the manufacturing process of FIG. 4 in the method for manufacturing the sensor according to the first embodiment. (A)-(d) is sectional drawing which shows typically another manufacturing process about the manufacturing method of the sensor which concerns on the 1st Embodiment. Sectional drawing which shows typically the schematic structure of the sensor about 2nd Embodiment of the capacitance-type mechanical quantity sensor which concerns on this invention, and its manufacturing method. (A) And (b) is sectional drawing which shows the manufacturing process typically about the manufacturing method of the sensor which concerns on the said 2nd Embodiment. Sectional drawing which shows typically the schematic structure of the same about the 3rd Embodiment of the capacitance-type mechanical quantity sensor which concerns on this invention, and its manufacturing method. (A) And (b) is sectional drawing which shows the manufacturing process typically about the manufacturing method of the sensor which concerns on the said 3rd Embodiment. Sectional drawing which shows typically the schematic structure of the sensor about the 4th Embodiment of the capacitance-type mechanical quantity sensor which concerns on this invention, and its manufacturing method. (A)-(c) is sectional drawing which shows typically the manufacturing process about the manufacturing method of the sensor which concerns on the said 4th Embodiment. Sectional drawing which shows typically schematic structure of the same about the electrostatic capacity type mechanical quantity sensor which concerns on this invention, and 5th Embodiment of the manufacturing method. (A) And (b) is sectional drawing which shows typically the manufacturing process about the manufacturing method of the sensor which concerns on the 5th Embodiment. The top view which shows typically the modification of the planar structure of the said sensor. The top view which shows typically another modification of the same planar structure. The top view which shows typically another modification of the same planar structure. Sectional drawing which shows the outline | summary typically about an example of the conventional electrostatic capacitance type pressure sensor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 1a ... Silicon film, 1b ... Lower layer, 2 ... Pressure receiving film, B1-B4 ... Beam, ED1, ED2 ... Counter electrode, FE1-FE4 ... Fixed electrode, M ... Mass, ME1-ME4 ... Movable electrode.

Claims (22)

A pressure receiving film that is displaced in response to application of a mechanical quantity from a vertical direction that is a direction perpendicular to the substrate surface, and a relative positional relationship that changes relative to each other in accordance with the displacement of the pressure receiving film while being supported by the substrate. A capacitance-type mechanical quantity sensor that detects the applied mechanical quantity based on a change in capacitance value between the first and second electrodes;
The first and second electrodes are disposed opposite to each other at a predetermined interval in a lateral direction that is a direction perpendicular to the longitudinal direction, and between the electrodes disposed to face each other as the pressure receiving film is displaced. A capacitance type mechanical quantity sensor characterized by changing a capacitance value according to the applied mechanical quantity. The substrate is a semiconductor substrate, and the first and second electrodes are formed in such a manner that a conductive impurity is introduced into a part of the substrate that is partially processed according to a desired electrode shape. The capacitive mechanical quantity sensor according to claim 1. The capacitance type mechanical quantity sensor according to claim 1, wherein the pressure receiving film is formed by a film material provided on a surface of the substrate. The capacitance type mechanical quantity sensor according to claim 1, wherein the pressure receiving film is formed of a film material provided on a back surface or inside of the substrate. The capacitive mechanical quantity sensor according to claim 4, wherein the pressure receiving film functions as an etch stopper film for the substrate. The substrate is an SOI substrate in which a silicon film is formed on a silicon oxide film, the first and second electrodes are formed by the silicon film, and the pressure receiving film is formed by the silicon oxide film. The capacitive mechanical quantity sensor according to claim 5. The capacitive mechanical quantity sensor according to any one of claims 1 to 5, wherein the substrate is made of silicon, and the pressure-receiving film is made of silicon oxide. The capacitive mechanical quantity sensor according to claim 1, wherein the substrate is a semiconductor substrate, and the pressure-receiving film is formed as a selectively thinned portion of the substrate. The first and second electrodes are arranged to face each other on one surface of the pressure receiving film, and a change in capacitance value between the electrodes arranged to face each other is caused by bending of the pressure receiving film. The capacitive mechanical quantity sensor according to any one of claims 1 to 8, which is based on a change in distance between the second electrodes. The capacitance-type mechanical quantity sensor according to claim 9, wherein both the first and second electrodes are formed integrally with the pressure receiving film. The first and second electrodes include a fixed electrode fixed to the substrate and a movable electrode that is displaced relative to the fixed electrode, and a change in capacitance value between the opposed electrodes is as follows. The capacitive mechanical quantity sensor according to any one of claims 1 to 8, which is based on a change in an opposing area between the fixed electrode and the movable electrode. The capacitive mechanical quantity sensor according to claim 11, wherein the movable electrode is formed in contact with the pressure receiving film or integrally with the pressure receiving film. The capacitance type mechanical quantity sensor according to claim 12, wherein the fixed electrode is formed with a predetermined gap between the fixed electrode and the pressure receiving film. The fixed electrode is formed in a comb-like shape integrally with a frame made of the substrate, and the movable electrode is relatively displaced with respect to the substrate through a beam in an inner space of the frame through which the substrate is penetrated. The capacitance type mechanical quantity sensor according to any one of claims 11 to 13, wherein the capacitance type sensor is formed so as to have a comb shape alternately with the fixed electrode integrally with a mass supported. The capacitive mechanical quantity sensor according to claim 1, wherein the capacitive dynamic quantity sensor is a pressure sensor that detects pressure as the applied mechanical quantity. The pressure receiving film that is displaced in response to the application of a mechanical quantity from the vertical direction, which is a direction perpendicular to the surface of the semiconductor substrate, and the relative positional relationship with each other changes as the pressure receiving film is displaced while being supported by the substrate. And manufacturing a capacitance type mechanical quantity sensor that detects the applied mechanical quantity based on a change in capacitance value between the first and second electrodes. A method,
Etching the surface of the substrate according to the electrode shape of the first and second electrodes;
A step of selectively etching and thinning a portion corresponding to these electrodes on the back surface of the substrate so that the first and second electrodes are supported only at predetermined positions of the substrate;
Forming a film material to be the pressure-receiving film;
Are performed in random order, the pressure-receiving film is arranged in a manner arranged on the surface of the substrate, and is arranged in a manner arranged opposite to each other at a predetermined interval in a lateral direction perpendicular to the longitudinal direction. A method of manufacturing a capacitance type mechanical quantity sensor, wherein the first and second electrodes are respectively formed. The pressure receiving film that is displaced in response to the application of a mechanical quantity from the vertical direction, which is a direction perpendicular to the surface of the semiconductor substrate, and the relative positional relationship with each other changes as the pressure receiving film is displaced while being supported by the substrate. And manufacturing a capacitance type mechanical quantity sensor that detects the applied mechanical quantity based on a change in capacitance value between the first and second electrodes. A method,
In order to process the surface of the substrate according to the electrode shape of the first and second electrodes, an etch stopper film is formed on the back side of the substrate, and the etching suppression action of the etch stopper film is utilized. By performing an etching process from the surface side to the etch stopper film on the substrate, the etch stopper film functions as the pressure receiving film, and the first and second electrodes are arranged in a direction perpendicular to the vertical direction. It forms so that it may oppose and arrange | position with a predetermined space | interval in a certain horizontal direction. The manufacturing method of the capacitance-type mechanical quantity sensor characterized by the above-mentioned. The method of manufacturing a capacitive mechanical quantity sensor according to claim 17,
Prior to the step of forming an etch stopper film on the back side of the substrate, the method further comprises a step of selectively etching and thinning a portion corresponding to the first and second electrodes on the back side of the substrate. A method of manufacturing a capacitance type mechanical quantity sensor characterized by the following. The pressure receiving film that is displaced in response to the application of a mechanical quantity from the vertical direction, which is a direction perpendicular to the surface of the semiconductor substrate, and the relative positional relationship with each other changes as the pressure receiving film is displaced while being supported by the substrate. And manufacturing a capacitance type mechanical quantity sensor that detects the applied mechanical quantity based on a change in capacitance value between the first and second electrodes. A method,
An SOI substrate in which a silicon film is formed on a silicon oxide film is prepared as the semiconductor substrate, and the silicon film is formed into electrode shapes of the first and second electrodes while utilizing the etching inhibiting action of the silicon oxide film. The etching process of the silicon oxide film is similarly applied to the portion of the surface of the SOI substrate opposite to the silicon film corresponding to the first and second electrodes. The silicon oxide film functions as the pressure-receiving film by performing an etching process up to the same silicon oxide film while using the first and second electrodes by the silicon film and orthogonal to the vertical direction. Manufacturing a capacitive mechanical quantity sensor characterized in that it is formed so as to be opposed to each other at a predetermined interval in a horizontal direction that is a direction of Method. The pressure receiving film that is displaced in response to the application of a mechanical quantity from the vertical direction, which is a direction perpendicular to the surface of the semiconductor substrate, and the relative positional relationship with each other changes as the pressure receiving film is displaced while being supported by the substrate. And manufacturing a capacitance type mechanical quantity sensor that detects the applied mechanical quantity based on a change in capacitance value between the first and second electrodes. A method,
Etching the surface of the substrate according to the electrode shape of the first and second electrodes, and selectively etching portions corresponding to the first and second electrodes on the back surface of the substrate By forming the film into a thin film, the first and second electrodes are formed so as to be opposed to each other at a predetermined interval in a horizontal direction that is a direction perpendicular to the vertical direction, and the pressure-receiving film is A method for manufacturing a capacitance type mechanical quantity sensor, comprising forming a thinned portion of a substrate selectively. In the manufacturing method of the capacitance type mechanical quantity sensor according to any one of claims 16 to 20,
The first and second electrodes include a fixed electrode fixed to the substrate and a movable electrode that is displaced relative to the fixed electrode. Of these, the movable electrode is applied to the pressure receiving film. The method of manufacturing a capacitive mechanical quantity sensor, further comprising a step of selectively releasing only the fixed electrode from the pressure receiving film while being in contact with each other. The method of manufacturing a capacitive dynamic quantity sensor according to any one of claims 16 to 21, wherein the capacitive dynamic quantity sensor is a pressure sensor that detects pressure as the applied dynamic quantity.

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