JP2007064920A - Electrostatic capacity type mechanical quantity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic capacity type mechanical quantity sensor having a small number of electrodes and capable of simplifying wiring parts. <P>SOLUTION: A fixed electrode 14a for a pressure sensor and a fixed electrode 14b for an acceleration sensor are formed on a principal surface 11a of a first glass substrate 11. A silicon substrate 16 is joined onto the first glass substrate 11 in such a way that a pressure-sensitive diaphragm 16a may be arranged above the fixed electrode 14b and that a rocking member 16b may be arranged above the fixed electrode 14b. A second glass substrate 18 is joined onto the silicon substrate 16 in such a way as to envelop the rocking member 16b. An electrode 13 serves as both an electrode for an electrically conductive movable part of the pressure sensor and an electrode for an electrically conductive movable part of the acceleration sensor and is a common electrode of the pressure sensor and the acceleration sensor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a capacitance-type mechanical quantity sensor that detects a mechanical quantity such as pressure or acceleration using an electrostatic capacity.

  Examples of the mechanical quantity sensor include a pressure sensor and an acceleration sensor. Such a mechanical quantity sensor includes a capacitive mechanical quantity sensor that detects an electrostatic capacity between a movable electrode and a fixed electrode.

  The capacitance type pressure sensor is configured by joining a substrate having a pressure-sensitive diaphragm, which is a movable electrode, and a substrate having a fixed electrode so as to have a predetermined interval between the pressure-sensitive diaphragm and the fixed electrode. Has been. In this capacitance-type pressure sensor, when pressure is applied to the pressure-sensitive diaphragm, the pressure-sensitive diaphragm is deformed, thereby changing the distance between the pressure-sensitive diaphragm and the fixed electrode. The capacitance between the pressure-sensitive diaphragm and the fixed electrode changes due to the change in the interval, and the change in pressure is detected using the change in capacitance.

  On the other hand, in a capacitance type acceleration sensor, a substrate having a swing member that is a movable electrode and a substrate having a fixed electrode are joined so as to have a predetermined interval between the swing member and the fixed electrode. It is comprised by. In this capacitance type acceleration sensor, when acceleration is applied to the swing member, the swing member swings, thereby changing the interval between the swing member and the fixed electrode. The capacitance between the oscillating member and the fixed electrode changes due to the change in the interval, and the change in acceleration is detected using the change in capacitance.

A capacitance type mechanical quantity sensor in which such a capacitance type pressure sensor and a capacitance type acceleration sensor are integrated has been developed (Patent Documents 1 and 2).
JP-A-8-160072 JP 2004-191128 A

  However, in the above-described integrated capacitance type mechanical quantity sensor, the pressure sensor and the acceleration sensor each require a fixed electrode and a lead portion for the fixed electrode, and a movable electrode and a lead portion for the same, and the number of electrodes is large. As a result, there is a problem that the wiring portion becomes complicated.

  The present invention has been made in view of the above points, and an object thereof is to provide an integrated capacitance type mechanical quantity sensor that can reduce the number of electrodes and simplify a wiring portion.

  The capacitance-type mechanical quantity sensor of the present invention is a first mechanical quantity sensor that detects a first mechanical quantity by a capacitance between a first fixed electrode and a first movable electrode forming a pair of opposed electrodes. And a second mechanical quantity sensor for detecting the second mechanical quantity by the capacitance between the second fixed electrode and the second movable electrode forming the other pair of opposing electrodes, A first capacitive electrode having a pair of principal surfaces facing each other and having the first fixed electrode and the second fixed electrode formed on one principal surface. A substrate, a first conductive movable portion serving as the first movable electrode disposed to face the first fixed electrode with a predetermined distance, and a second conductive electrode to face the first fixed electrode. And a second substrate having a second conductive movable part to be the second movable electrode disposed in a row. It said the electrode second movable electrode are electrically connected, characterized in that it is connected to an outside end portion extraction common electrode.

  According to this configuration, since the first movable electrode and the second movable electrode are electrically connected and connected to the outside at the common electrode extraction end portion, the number of electrodes can be reduced, whereby the wiring portion Can be simplified. Moreover, since the dimension of the width direction can be made small by setting it as such a structure, size reduction of a sensor can be achieved.

  The capacitance-type mechanical quantity sensor of the present invention is a first mechanical quantity sensor that detects a first mechanical quantity by a capacitance between a first fixed electrode and a first movable electrode forming a pair of opposed electrodes. And a second mechanical quantity sensor that detects the second mechanical quantity by the capacitance between the second fixed electrode and the second movable electrode forming another pair of opposing electrodes, A first fixed electrode for the pressure sensor formed on one main surface of the pair of main surfaces facing each other and the other main surface of the pair of main surfaces. A second fixed electrode for the acceleration sensor formed on a surface, a first substrate having a conductive member embedded so as to be substantially flush with the pair of main surfaces, and the first fixed electrode and a predetermined Having a first conductive movable part which becomes the first movable electrode disposed to face each other with an interval of A second substrate, and a third substrate having a second conductive movable portion that becomes the second movable electrode disposed to face the second fixed electrode at a predetermined interval, and One fixed electrode and the second fixed electrode are electrically connected through the conductive member, and are connected to the outside at a common electrode extraction end.

  According to this configuration, the first fixed electrode and the second fixed electrode are electrically connected via the conductive member, and are connected to the outside at the common electrode lead-out end portion, so that the number of electrodes can be reduced. As a result, the wiring portion can be simplified. In addition, since no electrode or the like is present on the bonding surface between the first substrate and the second substrate, it is possible to maintain a high degree of sealing of the sensor cavity.

  In the capacitance-type mechanical quantity sensor of the present invention, the electrode extraction end portions of the first and second fixed electrodes and the electrode extraction end portion common to the first and second movable electrodes are the first substrate. Is preferably formed on the other main surface of the pair of main surfaces. In the capacitance type mechanical quantity sensor of the present invention, the common electrode extraction end of the first and second fixed electrodes and the electrode extraction end of the first and second movable electrodes are on the same plane. It is preferable to arrange in the inside.

  According to these structures, since the electrode used as the taking-out part to the exterior can be formed on one surface, it can be set as the device suitable for surface mounting.

  In the capacitance-type mechanical quantity sensor of the present invention, the first substrate is a glass substrate and the second substrate is a silicon substrate, or the first substrate is a glass substrate, and the second and The third substrate is preferably a silicon substrate. In the capacitance type mechanical quantity sensor of the present invention, it is preferable that the conductive member is a silicon member embedded in the glass substrate.

  In the capacitance-type mechanical quantity sensor of the present invention, it is preferable that the interface between the glass substrate and the silicon member has a Si—Si bond or a Si—O bond. According to this configuration, since the Si-Si bond or the Si-O bond is present at the interface between the glass substrate and the silicon member, the glass substrate and the silicon member are firmly bonded, and the adhesion between the two is improved. To do.

  In the capacitance-type mechanical quantity sensor of the present invention, the first conductive movable part is a pressure-sensitive diaphragm that is displaced by a pressure to be measured, the pressure is detected using the pressure-sensitive diaphragm, and the second conductive Preferably, the movable part is a rocking member that rocks according to the acceleration to be measured, and the acceleration is detected using the rocking member.

  According to the capacitance type mechanical quantity sensor of the present invention, the first movable electrode and the second movable electrode are electrically connected, and are connected to the outside at the common electrode extraction end, or the first fixed electrode. And the second fixed electrode are electrically connected via the conductive member, and are connected to the outside at the common electrode lead-out end portion, so that the number of electrodes is small and the wiring portion can be simplified.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
(Embodiment 1)
In the present embodiment, the capacitance type mechanical quantity sensor includes a capacitance type dynamic quantity sensor in which a pressure sensor that detects pressure by capacitance and an acceleration sensor that detects acceleration by capacitance are arranged in parallel. A case of a sensor (horizontal type) will be described. FIG. 1 is a cross-sectional view showing a schematic configuration of a capacitive mechanical quantity sensor according to Embodiment 1 of the present invention.

  In the figure, 11 indicates a first glass substrate. The first glass substrate 11 has a pair of main surfaces 11a and 11b facing each other. A pressure sensor and an acceleration sensor are arranged in parallel on the first glass substrate 11. In the first glass substrate 11, islands (silicon members) 12a to 12c made of silicon are embedded. The islands 12a to 12c are conductive members that electrically connect the electrode formed on the main surface 11a and the electrode formed on the main surface 11b. The islands 12a and 12b are conductive members on the pressure sensor side, and the islands 12b and 12c are conductive members on the acceleration sensor side. That is, the island-shaped body 12b serves as both a pressure sensor side conductive member and an acceleration sensor side conductive member. The islands 12 a to 12 c are exposed on both main surfaces of the first glass substrate 11. The formation of the islands 12a to 12c will be described later.

  In the pressure sensor region A on the main surface 11a of the first glass substrate 11, a fixed electrode 14a is formed so as to be electrically connected to one exposed portion of the island-shaped body 12a. This fixed electrode 14a is a fixed electrode for a pressure sensor. A fixed electrode 14b is formed in the acceleration sensor region B on the main surface 11a of the first glass substrate 11 so as to be electrically connected to one exposed portion of the island-shaped body 12c. This fixed electrode 14b is a fixed electrode for an acceleration sensor. An electrode 13 is formed between the fixed electrode 14a and the fixed electrode 14b so as to be electrically connected to one exposed portion of the island 12b. The electrode 13 serves as both an electrode for the conductive movable part (movable electrode) of the pressure sensor and an electrode for the conductive movable part (movable electrode) of the acceleration sensor, and is a common electrode for the pressure sensor and the acceleration sensor. .

  In the pressure sensor region A on the main surface 11b of the first glass substrate 11, an electrode 15a is formed so as to be electrically connected to the other exposed portion of the island-shaped body 12a. In the acceleration sensor region B on the main surface 11b, an electrode 15c is formed so as to be electrically connected to the other exposed portion of the island 12c. An electrode 15b is formed between the electrode 15a and the electrode 15c so as to be electrically connected to the other exposed portion of the island 12b. That is, the electrodes 15 a to 15 c electrically connected to the fixed electrodes 14 a and 14 b and the conductive movable part electrode (common electrode 13) are formed on the main surface 11 b of the first glass substrate 11. Accordingly, the respective electrode extraction end portions of the fixed electrodes 14 a and 14 b and the electrode extraction end portion of the conductive movable portion electrode are formed on the main surface 11 b of the first glass substrate 11. Since the electrodes 15a to 15c are thus provided on the same main surface 11b, connection to an external device is facilitated.

  On the main surface 11a of the first glass substrate 11, a pressure-sensitive diaphragm 16a (movable electrode) that is a conductive movable part on the pressure sensor side and a swing member 16b that is a conductive movable part on the acceleration sensor side are provided. A silicon substrate 16 is bonded. In this silicon substrate 16, a pressure sensitive diaphragm 16 a that is movable by a measured pressure as a conductive movable portion is provided in the pressure sensor region A, and a vibration is measured by a measured acceleration as a conductive movable portion in the acceleration sensor region B. A swinging member 16b that moves and a cantilever 16c that supports the swinging member 16b are provided. Further, between the pressure sensor region A and the acceleration sensor region B on one main surface (upper main surface) of the silicon substrate 16, the end of the pressure sensor region A (left end as viewed in the drawing), and the acceleration sensor region B A first joining portion 16d that joins a second glass substrate, which will be described later, is provided at the end portion (right end as viewed in the drawing). Further, between the pressure sensor region A and the acceleration sensor region B on the other main surface (lower main surface) of the silicon substrate 16, the end of the pressure sensor region A of the silicon substrate 16 (left end as viewed in the drawing), and A second joint portion 16e that joins the main surface 11a of the first glass substrate 11 is provided at the end portion of the acceleration sensor region B (the right end as viewed in the drawing). Further, in the silicon substrate 16, a recess 16f is formed above the lead-out portions (islands 12b, 12c) of the fixed electrodes 14a, 14b. By forming the recess 16f in this manner, parasitic capacitance in a region other than the sensing region can be reduced.

  The first glass substrate 11 and the silicon substrate 16 are arranged such that the pressure sensitive diaphragm 16a is disposed at a predetermined interval from the fixed electrode 14a, and the swing member 16b is disposed at a predetermined interval from the fixed electrode 14b. In the state of being aligned with each other, the second joint 16e is joined. Further, the first glass substrate 11 and the silicon substrate 16 are joined so that cavities 17a and 17b are formed on the fixed electrodes 14a and 14b. That is, the cavity 17a is provided on the fixed electrode 14a in the pressure sensor region A, and the cavity 17b is provided on the fixed electrode 14b in the acceleration sensor region B.

  A second glass substrate 18 is disposed on the silicon substrate 16. The second glass substrate 18 is bonded at the first bonding portion 16 d of the silicon substrate 16. The second glass substrate 18 is provided with a hole 18a through which outside air enters. The pressure-sensitive diaphragm 16a is moved by the pressure of the outside air that has entered through the hole 18a. As a method of forming the hole 18a in the second glass substrate 18, a sandblasting process or the like can be used. The acceleration sensor region B is configured such that the swing member 16b swings in a space formed by the first and second glass substrates 11 and 18 and the silicon substrate 16.

  The pressure-sensitive diaphragm 16a and the swing member 16b in the silicon substrate 16 are provided by forming recesses from both sides of the silicon substrate 16 by etching or the like. Further, when the cantilever 16c and the swing member 16b are formed on the silicon substrate 16, for example, etching is performed by applying a micromachining machine technique. The concave portion on the glass substrate bonding surface side of the silicon substrate 16 has a size that can accommodate at least the fixed electrodes 14a and 14b. By bonding the silicon substrate 16 to the first glass substrate 11, the cavity 17a, 17b is constituted. Thereby, an electrostatic capacity is generated between the pressure-sensitive diaphragm 16a and the fixed electrode 14a, and an electrostatic capacity is generated between the swinging member 16b and the fixed electrode 14b.

  The interface between the first glass substrate 11 and the islands 12a to 12c preferably has high adhesion. As will be described later, these interfaces are formed by pushing the islands 12a to 12c into the first glass substrate 11 under heating. Although high adhesion can be exhibited even at the interface obtained by such a method, the adhesion is further enhanced by applying anodic bonding treatment after the islands 12a to 12c are pushed into the first glass substrate 11. be able to. Anodic bonding treatment is applied at a predetermined temperature (for example, 400 ° C. or lower) at a predetermined voltage (for example, 300 V to 1 kV), thereby generating a large electrostatic attraction between silicon and glass and sharing at the interface. A process that causes a bond to occur. The covalent bond at this interface is a Si—Si bond or a Si—O bond between the Si atom of silicon and the Si atom contained in the glass. Therefore, silicon and glass are firmly bonded by this Si—Si bond or Si—O bond, and very high adhesion is exhibited at the interface between the two. In order to perform such anodic bonding efficiently, the glass material of the first glass substrate 11 is preferably a glass material containing an alkali metal such as sodium (for example, Pyrex (registered trademark) glass).

  The same applies to the interface between the main surface 11 a of the first glass substrate 11 and the silicon substrate 16 and the interface between the silicon substrate and the second glass substrate 18. That is, the adhesion can be enhanced by mounting the silicon substrate 16 on the main surface 11a of the first glass substrate 11 and performing an anodic bonding process. Thus, the interface between the first glass substrate 11 and the islands 12a to 12c, the interface between the first glass substrate 11 and the silicon substrate 16, and the interface between the second glass substrate 18 and the silicon substrate 16 By exhibiting high adhesion, the cavity 17a and the swinging member 16b formed between the pressure-sensitive diaphragm 16a and the main surface 11a of the first glass substrate 11 and the main surface 11a of the first glass substrate 11 It is possible to keep the air tightness in the cavity 17b formed between the two.

  In the pressure sensor region A of the capacitive mechanical quantity sensor having such a configuration, a predetermined capacitance is provided between the pressure-sensitive diaphragm 16 a and the fixed electrode 14 a on the first glass substrate 11. When pressure is applied to the pressure sensor, the pressure-sensitive diaphragm 16a moves according to the pressure. As a result, the pressure sensitive diaphragm 16a is displaced. At this time, the electrostatic capacitance between the pressure-sensitive diaphragm 16a and the fixed electrode 14a on the first glass substrate 11 changes. Therefore, the change can be a pressure change using the capacitance as a parameter.

  On the other hand, in the acceleration sensor region B of the capacitance type mechanical quantity sensor, the swing member 16b is measured acceleration in a space formed by the first and second glass substrates 11 and 18 and the silicon substrate 16. Oscillates. Since the oscillating member 16b is a conductor, the capacitance between the oscillating member 16b and the fixed electrode 14b changes when the oscillating member 16b oscillates. By detecting this change, acceleration can be measured.

  In this capacitance type mechanical quantity sensor, the movable electrode on the pressure sensor side and the movable electrode on the acceleration sensor side are electrically connected and connected to the outside at a common electrode take-out end, that is, the pressure sensor Since the electrode for the movable electrode (first conductive movable part) on the side and the electrode for the movable electrode (second conductive movable part) on the acceleration sensor side are common, the number of electrodes can be reduced, Thereby, a wiring part can be simplified. Moreover, since the electrode for the first conductive movable part on the pressure sensor side and the electrode for the second conductive movable part on the acceleration sensor side are made common, the dimension in the width direction can be reduced. The size of the sensor can be reduced.

  Next, a manufacturing method of the capacitive pressure sensor of the present embodiment will be described. 2 (a) to (c), FIGS. 3 (a) to (c), and FIGS. 4 (a) to 4 (e) are diagrams illustrating a method of manufacturing a capacitive mechanical quantity sensor according to Embodiment 1 of the present invention. It is sectional drawing for demonstrating.

  First, a silicon substrate 16 having a low resistance by doping impurities is prepared. The impurity may be an n-type impurity or a p-type impurity. The concentration is, for example, about 0.01 Ω · cm. One main surface of the silicon substrate 16 is etched, and as shown in FIG. 2A, a cavity 17a, a swing member 16b, and a fixed electrode for controlling the distance between the pressure-sensitive diaphragm 16a and the fixed electrode 14a. A recess 16g is formed for the cavity 17b for controlling the distance to the space 14b. In this case, the silicon substrate 16 is thermally oxidized to form a silicon oxide film. Then, a resist film is formed on the silicon oxide film, and the resist film is patterned (photolithography) so that the resist film remains outside the region where the recess 16g is formed, and the silicon oxide film is etched using the resist film as a mask, Thereafter, the remaining resist film is removed. The silicon substrate 16 is etched using the silicon oxide film having the opening formed in this way as a mask to provide a recess 16g. Etching may be dry etching or wet etching. However, in the case of wet etching, it is preferable to perform anisotropic etching by defining the crystal plane of the surface of the silicon substrate 16 so that the etching rate is different.

  Next, as shown in FIG. 2B, in the recess 16g, a recess 16f is formed in a region corresponding to the upper part of the lead electrodes (islands 12a, 12c) of the fixed electrodes 14a, 14b. The recess 16f is formed by the same method as that for forming the recess 16g. Next, the other main surface of the silicon substrate 16 is etched to form a pressure sensitive diaphragm 16a and a swing member 16b as shown in FIG. The pressure-sensitive diaphragm 16a and the swing member 16b are formed by the same method as the method of forming the recess 16g.

  Next, as shown in FIG. 3A, the first glass substrate 11 in which the islands 12a to 12c are embedded is produced. The first glass substrate 11 can be manufactured by the steps shown in FIGS. 4A to 4E, the islands 12a and 12b are shown for the sake of clarity. That is, first, a silicon substrate 12 having a low resistance by doping impurities is prepared. The silicon substrate 12 is etched to form islands 12a to 12c as shown in FIG.

  Next, as shown in FIG. 4B, the first glass substrate 11 is placed on the silicon substrate 12 on which the islands 12a and 12b are formed. Further, the silicon substrate 12 and the first glass substrate 11 are heated under vacuum, and the silicon substrate 12 is pressed against the first glass substrate 11 as shown in FIG. 12b is pushed into the main surface 11b of the first glass substrate 11 to bond the silicon substrate 12 and the first glass substrate 11 together. The temperature at this time is not higher than the melting point of silicon and is preferably a temperature at which the glass can be deformed (for example, not higher than the softening point temperature of the glass). For example, the heating temperature is about 600 ° C.

  Further, in order to further improve the adhesion at the interface 11c between the islands 12a, 12b of the silicon substrate 12 and the first glass substrate 11, it is preferable to perform an anodic bonding treatment. In this case, an electrode is attached to each of the silicon substrate 12 and the first glass substrate 11 and a voltage of about 300 V to 1 kV is applied under heating at about 400 ° C. or lower. Thereby, the adhesiveness at the interface 11c becomes higher, and the airtightness of the cavities 17a and 17b of the capacitance type mechanical quantity sensor can be improved.

  Next, as shown in FIG. 4D, the islands 12a and 12b are partially exposed at the main surface 11a by polishing the main surface 11a side of the first glass substrate 11. As a result, the islands 12a and 12b are embedded in the first glass substrate 11. Further, as shown in FIG. 4E, the islands 12 a and 12 b are partially exposed from both surfaces of the first glass substrate 11 by polishing the silicon substrate 12. In this way, the first glass substrate 11 in which the silicon member is embedded is manufactured.

  Next, as illustrated in FIG. 3B, electrodes 15 a to 15 c are formed on the main surface 11 b of the first glass substrate 11 so as to be electrically connected to the islands 12 a to 12 c, respectively. In this case, first, an electrode material is deposited on the main surface 11b of the first glass substrate 11, a resist film is formed thereon, and the resist film is patterned so that the resist film remains in the electrode formation region ( Photolithography), the electrode material is etched using the resist film as a mask, and then the remaining resist film is removed.

  Next, as shown in FIG. 3C, an electrode 13 (common electrode) is formed on the main surface 11a of the first glass substrate 11 so as to be electrically connected to the island 12b. Fixed electrodes 14a and 14b are formed so as to be electrically connected to 12a and 12c, respectively. In this case, first, an electrode material is deposited on the main surface 11a of the first glass substrate 11, a resist film is formed thereon, and the resist film is left so that the resist film remains in the electrode and fixed electrode formation region. Is patterned (photolithography), the electrode material is etched using the resist film as a mask, and then the remaining resist film is removed.

  Next, the silicon substrate 16 having the pressure-sensitive diaphragm 16a that is displaced by the measured pressure and the swinging member 16b that is swung by the measured acceleration is positioned so that the pressure-sensitive diaphragm 16a is positioned at a predetermined interval from the fixed electrode 14a. In addition, the swing member 16b is joined to the main surface 11a of the first glass substrate 11 so as to be positioned at a predetermined distance from the fixed electrode 14b. That is, the main surface 11a of the first glass substrate 11 and the second bonding portion 16e of the silicon substrate 16 are bonded. At this time, an anodic bonding process is performed by applying a voltage of about 500 V to the silicon substrate 16 and the first glass substrate 11 under heating at about 400 ° C. or lower. Thereby, the adhesiveness in the interface between the silicon substrate 16 and the 1st glass substrate 11 becomes higher, and the airtightness of the cavities 17a and 17b can be improved.

  Next, the second glass substrate 18 is subjected to sand blasting to form holes 18a. The second glass substrate 18 is bonded to the silicon substrate 16. That is, the second glass substrate 18 and the first bonding portion 16d of the silicon substrate 16 are bonded. At this time, an anodic bonding process is performed by applying a voltage of about 500 V to the silicon substrate 16 and the second glass substrate 18 under heating at about 400 ° C. or lower. Thereby, the adhesiveness in the interface between the silicon substrate 16 and the 2nd glass substrate 18 becomes higher, and the airtightness by the side of an acceleration sensor can be improved.

  In the capacitive mechanical quantity sensor thus obtained, on the pressure sensor side, the fixed electrode 14a is electrically connected to the electrode 15a via the island 12a, and the electrode 13 via the island 12b. Are electrically connected to the electrode 15b. Therefore, the capacitance change signal detected between the pressure-sensitive diaphragm 16a and the fixed electrode 14a can be acquired from the electrodes 15a and 15b via the islands 12a and 12b. The measured pressure can be calculated based on this signal. On the acceleration sensor side, the fixed electrode 14b is electrically connected to the electrode 15c via the island-shaped body 12c, and the electrode 13 is electrically connected to the electrode 15b via the island-shaped body 12b. Therefore, the capacitance change signal detected between the swing member 16b and the fixed electrode 14b can be acquired from the electrodes 15b and 15c via the islands 12b and 12c. The measured acceleration can be calculated based on this signal.

  According to the capacitance-type mechanical quantity sensor according to the present embodiment, the electrode 13 for the pressure-sensitive diaphragm 16a on the pressure sensor side and the electrode 13 for the swing member 16b on the acceleration sensor side are common. The number of electrodes can be reduced, whereby the wiring portion can be simplified. Further, since the electrode for the pressure-sensitive diaphragm 16a on the pressure sensor side and the electrode for the oscillating member 16b on the acceleration sensor side are made common, the size in the width direction can be reduced. Can be achieved.

(Embodiment 2)
In the present embodiment, the capacitance type mechanical quantity sensor is formed by stacking a pressure sensor that detects pressure by capacitance and an acceleration sensor that detects acceleration by capacitance. The case of (vertical) will be described. FIG. 5 is a cross-sectional view showing a schematic configuration of the capacitive mechanical quantity sensor according to the second embodiment of the present invention.

  In the figure, reference numeral 21 denotes a first glass substrate. The first glass substrate 21 has a pair of main surfaces 21a and 21b facing each other. A pressure sensor is provided on the main surface 21a side of the first glass substrate 21, and an acceleration sensor is provided on the main surface 21b side. Further, an island-like body (silicon member) 22 made of silicon is embedded in the first glass substrate 21. The island 22 is a conductive member that electrically connects the electrode formed on the main surface 21a and the electrode formed on the main surface 21b. The islands 22 are exposed on both main surfaces of the first glass substrate 11. That is, the island-like body 22 is formed so as to be substantially flush with both main surfaces of the first glass substrate 11. The formation of the islands 22 is the same as in the first embodiment.

  A fixed electrode 23 is formed in the pressure sensor region A on the main surface 11 a side of the first glass substrate 11 so as to be electrically connected to one exposed portion of the island-shaped body 22. This fixed electrode 23 is a fixed electrode for a pressure sensor. Further, a fixed electrode 24 is formed in the acceleration sensor region B on the main surface 11b side of the first glass substrate 11 so as to be electrically connected to the other exposed portion of the island-like body 22. The fixed electrode 24 is a fixed electrode for the acceleration sensor. The fixed electrode 24 includes an electrode 24 a that extends to the side surface of the first glass substrate 11 and serves as a lead-out end portion for the fixed electrode. The fixed electrode 23 on the pressure sensor side and the fixed electrode 24 on the acceleration sensor side are electrically connected through an island 22. That is, the fixed electrode 23 on the pressure sensor side and the fixed electrode 24 on the acceleration sensor side are shared.

  On the main surface 21a of the first glass substrate 21, a first silicon substrate 25 having a pressure-sensitive diaphragm 25a (movable electrode) which is a conductive movable portion on the pressure sensor side is bonded. This pressure-sensitive diaphragm 25a is movable as a conductive movable part by a pressure to be measured. On the main surface 21b of the first glass substrate 21, a second silicon substrate 26 having a swing member 26a that is a conductive movable part on the acceleration sensor side and a cantilever 26b that supports the swing member 26a is joined. Has been. The swing member 26a swings at a measured acceleration as a conductive movable part. The first silicon substrate 25 is bonded to the main surface 21a of the first glass substrate 21 by the first bonding portion 25b. The second silicon substrate 26 is bonded to the main surface 21b of the first glass substrate 21 by the second bonding portion 26c.

  The first glass substrate 21 and the first silicon substrate 25 are bonded at the first bonding portion 25b in a state where the pressure-sensitive diaphragm 25a is aligned with the fixed electrode 23 so as to be disposed at a predetermined interval. The The first glass substrate 21 and the second silicon substrate 26 are joined by the second joining portion 26c in a state where the swing member 26a is aligned with the fixed electrode 24 so as to be arranged at a predetermined interval. The Further, the first glass substrate 21 and the first silicon substrate 25 are joined so that a cavity 27 a is formed on the fixed electrode 23. The first glass substrate 21 and the second silicon substrate 26 are joined so that a cavity 27 b is formed on the fixed electrode 24.

  The pressure-sensitive diaphragm 25a in the first silicon substrate 25 and the swing member 26a in the second silicon substrate 26 are provided by forming recesses from both sides of the first and second silicon substrates 25 and 26 by etching or the like. It has been. Further, when the cantilever 26b and the swing member 26a are formed on the second silicon substrate 26, for example, etching is performed by applying a micromachining machine technique. The recesses on the first glass substrate bonding surface side of the first and second silicon substrates 25 and 26 have a size that can accommodate at least the fixed electrodes 23 and 24, respectively. The cavity 27 a is configured by bonding to one glass substrate 21, and the cavity 27 b is configured by bonding the second silicon substrate 26 to the first glass substrate 21. As a result, a capacitance is generated between the pressure-sensitive diaphragm 25 a and the fixed electrode 23, and a capacitance is generated between the swing member 26 a and the fixed electrode 24.

  The interface between the first glass substrate 21 and the island 22, the interface between the main surface 21 a of the first glass substrate 21 and the first bonding portion 25 b of the first silicon substrate 25, and the main of the first glass substrate 21 The interface between the surface 21b and the second bonding portion 26c of the second silicon substrate 26 preferably has high adhesion. The adhesiveness of these interfaces can be further increased by performing anodic bonding treatment in the same manner as in the first embodiment. Thereby, the airtightness of the cavity 27a comprised between the pressure sensitive diaphragm 25a and the main surface 21a of the 1st glass substrate 21 can be kept high.

  An electrode 28a which is a lead-out end portion for the pressure-sensitive diaphragm 25a is formed on the side surface (right side surface as viewed in the drawing) of the first silicon substrate 25. In addition, an electrode 28b, which is a lead-out end for the swing member 26a, is formed on the side surface (right side as viewed in the drawing) of the second silicon substrate 26. Therefore, the electrode 24a that is the lead-out end for the fixed electrode 24, the electrode 28a that is the lead-out end for the pressure-sensitive diaphragm 25a, and the electrode 28b that is the lead-out end for the swing member 26a are in the same plane. Is arranged. Therefore, the electrodes 24a and 28b are connected to the outside at the common electrode extraction end. Thereby, this sensor can be easily surface-mounted on an external device. These electrodes 24a, 28a, and 28b do not have to be in the same plane.

  In the pressure sensor region A of the capacitance type mechanical quantity sensor having such a configuration, a predetermined capacitance is provided between the pressure sensitive diaphragm 25 a and the fixed electrode 23 on the first glass substrate 21. When pressure is applied to the pressure sensor, the pressure-sensitive diaphragm 25a moves according to the pressure. Thereby, the pressure sensitive diaphragm 25a is displaced. At this time, the electrostatic capacitance between the pressure sensitive diaphragm 25a and the fixed electrode 23 on the first glass substrate 21 changes. Therefore, the change can be a pressure change using the capacitance as a parameter.

  On the other hand, in the acceleration sensor region B of the capacitance type mechanical quantity sensor, the swinging member 26a is swung by the measured acceleration in the space formed by the first glass substrate 21 and the second silicon substrate 26. Move. Since the oscillating member 26a is a conductor, the capacitance with the fixed electrode 24 changes when the oscillating member 26a oscillates. By detecting this change, acceleration can be measured.

  In this capacitance type mechanical quantity sensor, the first fixed electrode on the pressure sensor side and the second fixed electrode on the acceleration sensor side are electrically connected via an island (conductive member). The number can be reduced, whereby the wiring portion can be simplified. In addition, there is no electrode or the like on the bonding surface between the first silicon substrate 25 and the first glass substrate 21 on the pressure sensor side (the movable electrode 28a is formed on the side surface of the first silicon substrate 25). Therefore, the sealing degree of the pressure sensor cavity 27a can be kept high.

  Next, a manufacturing method of the capacitive pressure sensor of the present embodiment will be described. 6 (a), 6 (b), 7 (a) to 7 (c), and 8 (a) to 8 (c) show a method of manufacturing a capacitive mechanical quantity sensor according to Embodiment 2 of the present invention. It is sectional drawing for demonstrating.

  First, a first silicon substrate 25 doped with impurities to reduce resistance is prepared. The impurity may be an n-type impurity or a p-type impurity. The concentration is, for example, about 0.01 Ω · cm. One main surface of the first silicon substrate 25 is etched to form a recess 25c for the cavity 27a for controlling the distance between the pressure sensitive diaphragm 25a and the fixed electrode 23 as shown in FIG. Form. In this case, the first silicon substrate 25 is thermally oxidized to form a silicon oxide film. Then, a resist film is formed on the silicon oxide film, and the resist film is patterned (photolithography) so that the resist film remains outside the region where the recess 25c is formed, and the silicon oxide film is etched using the resist film as a mask, Thereafter, the remaining resist film is removed. The first silicon substrate 25 is etched using the silicon oxide film having the opening formed in this way as a mask to provide a recess 25c. Etching may be dry etching or wet etching. However, in the case of wet etching, it is preferable to perform anisotropic etching by defining the crystal plane of the surface of the first silicon substrate 25 so that the etching rate differs.

  Next, the other main surface of the first silicon substrate 25 is etched to form a pressure-sensitive diaphragm 25a as shown in FIG. 6B. The pressure-sensitive diaphragm 25a is formed by the same method as the method of forming the recess 25c.

  Next, a second silicon substrate 26 having a low resistance by doping impurities is prepared in the same manner as described above. One main surface of the second silicon substrate 26 is etched, and as shown in FIG. 7A, a step portion 26e for the cavity 27b for controlling the distance between the swing member 26a and the fixed electrode 24. Form. In this case, the second silicon substrate 26 is thermally oxidized to form a silicon oxide film. Then, a resist film is formed on the silicon oxide film, and the resist film is patterned (photolithography) so that the resist film remains outside the stepped portion 26e formation region, and the silicon oxide film is etched using the resist film as a mask. Thereafter, the remaining resist film is removed. The second silicon substrate 26 is etched using the silicon oxide film having the opening thus formed as a mask to provide a stepped portion 26e. Etching may be dry etching or wet etching. However, in the case of wet etching, it is preferable to perform anisotropic etching by defining the crystal plane of the surface of the second silicon substrate 26 so that the etching rate differs.

  Next, the other main surface of the second silicon substrate 26 is etched to form a recess 26f for controlling the thickness interval of the swing member 26a, as shown in FIG. 7B. Further, the other main surface of the second silicon substrate 26 is etched to form a recess 26g for forming the cantilever 26b in the recess 26f, as shown in FIG. 7C. The recesses 26f and 26g are formed by a method similar to the method of forming the recess 26e.

  Subsequently, the 1st glass substrate 21 which embedded the island-shaped body 22 is produced. The method of embedding the islands 22 in the first glass substrate 21 is the same as the process shown in FIG. 4 in the first embodiment. Next, the fixed electrode 23 is formed on the main surface 21 a of the first glass substrate 21 so as to be electrically connected to the island-like body 22. In this case, first, an electrode material is deposited on the main surface 21a of the first glass substrate 21, a resist film is formed thereon, and the resist film is patterned so that the resist film remains in the fixed electrode formation region. (Photolithography), the electrode material is etched using the resist film as a mask, and then the remaining resist film is removed.

  Next, as shown in FIG. 8B, the fixed electrode 24 is formed on the main surface 21 b of the first glass substrate 21 so as to be electrically connected to the island-like body 2. In this case, first, an electrode material is deposited on the main surface 21b of the first glass substrate 21, a resist film is formed thereon, and the resist film is patterned so that the resist film remains in the fixed electrode formation region. (Photolithography), the electrode material is etched using the resist film as a mask, and then the remaining resist film is removed.

  Next, the main surface 21a of the first glass substrate 21 is placed on the first silicon substrate 25 having the pressure-sensitive diaphragm 25a that is displaced by the pressure to be measured so that the pressure-sensitive diaphragm 25a is positioned at a predetermined distance from the fixed electrode 23. Join on top. Further, the swinging member 26 a that swings due to the acceleration to be measured is joined to the main surface 21 b of the first glass substrate 21 so as to be positioned at a predetermined distance from the fixed electrode 24. That is, the main surface 21 a of the first glass substrate 21 and the first bonding portion 25 b of the first silicon substrate 25 are bonded, and the main surface 21 b of the first glass substrate 21 and the second of the second silicon substrate 26 are second. The joint portion 26c is joined. At this time, an anodic bonding process is performed by applying a voltage of about 500 V to the first and second silicon substrates 25 and 26 and the first glass substrate 21 under heating at about 400 ° C. or less. Thereby, the adhesiveness in the interface between the 1st and 2nd silicon substrates 25 and 26 and the 1st glass substrate 21 becomes higher, and the airtightness of the cavities 27a and 27b can be improved.

  Further, the electrode 28 a is formed on the side surface of the first silicon substrate 25, the electrode 24 a is formed on the side surface of the first glass substrate 21, and the electrode 28 b is formed on the side surface of the second silicon substrate 26. In this case, these electrodes 24a and 28b are formed by depositing an electrode material using a stencil mask or the like.

  In the capacitance type mechanical quantity sensor thus obtained, the fixed electrode 23 is electrically connected to the electrode 24a through the island 22 on the pressure sensor side. Therefore, the capacitance change signal detected between the pressure-sensitive diaphragm 25 a and the fixed electrode 23 can be acquired from the electrodes 24 a and 28 a via the island 22. The measured pressure can be calculated based on this signal. On the acceleration sensor side, the fixed electrode 24 extends to form an electrode 24a. Therefore, the capacitance change signal detected between the swing member 26a and the fixed electrode 24 can be acquired from the electrodes 24a and 28b. The measured acceleration can be calculated based on this signal.

  According to the capacitance type mechanical quantity sensor according to the present embodiment, the fixed electrode 23 on the pressure sensor side and the fixed electrode 24 on the acceleration sensor side are electrically connected via the island-shaped body 22. The number of electrodes can be reduced, whereby the wiring portion can be simplified. In addition, there is no electrode or the like on the bonding surface between the first silicon substrate 25 and the first glass substrate 21 on the pressure sensor side (the movable electrode 28a is formed on the side surface of the first silicon substrate 25). Therefore, the sealing degree of the pressure sensor cavity 27a can be kept high.

  The present invention is not limited to Embodiments 1 and 2 above, and can be implemented with various modifications. For example, the numerical values and materials described in the first and second embodiments are not particularly limited. Further, the processes described in the first and second embodiments are not limited to this, and the order between the processes may be changed as appropriate. Other modifications may be made as appropriate without departing from the scope of the object of the present invention.

  The present invention can be applied to, for example, a capacitive mechanical quantity sensor that monitors pressure only when a tire rotates in a TPMS (Tire Pressure Monitoring System) with a battery.

It is sectional drawing which shows schematic structure of the electrostatic capacitance type mechanical quantity sensor which concerns on Embodiment 1 of this invention. (A)-(c) is sectional drawing for demonstrating the manufacturing method of the electrostatic capacitance type mechanical quantity sensor which concerns on Embodiment 1 of this invention. (A)-(c) is sectional drawing for demonstrating the manufacturing method of the electrostatic capacitance type mechanical quantity sensor which concerns on Embodiment 1 of this invention. (A)-(e) is sectional drawing for demonstrating the manufacturing method of the electrostatic capacitance type mechanical quantity sensor which concerns on Embodiment 1 of this invention. It is sectional drawing which shows schematic structure of the electrostatic capacitance type mechanical quantity sensor which concerns on Embodiment 2 of this invention. (A), (b) is sectional drawing for demonstrating the manufacturing method of the electrostatic capacitance type mechanical quantity sensor which concerns on Embodiment 2 of this invention. (A)-(c) is sectional drawing for demonstrating the manufacturing method of the electrostatic capacitance type mechanical quantity sensor which concerns on Embodiment 2 of this invention. (A)-(c) is sectional drawing for demonstrating the manufacturing method of the electrostatic capacitance type mechanical quantity sensor which concerns on Embodiment 2 of this invention.

Explanation of symbols

A Pressure sensor area B Acceleration sensor area 11, 18, 21 Glass substrate 11a, 11b, 21a, 21b Main surface 12, 16, 25, 26 Silicon substrate 12a-12c, 22 Island-like body 13, 15a-15c Electrode 14a, 14b , 23, 24 Fixed electrode 16a, 25a Pressure sensitive diaphragm 16b, 26a Oscillating member 16c, 26b Cantilever 16d, 16e, 25b, 26c, 26d

Claims (9)

  A first mechanical quantity sensor that detects a first mechanical quantity by a capacitance between a first fixed electrode that forms a pair of opposed electrodes and a first movable electrode, and a first dynamic quantity sensor that forms another pair of opposed electrodes 2. A capacitance type mechanical quantity sensor formed by juxtaposing and integrating a second mechanical quantity sensor for detecting a second mechanical quantity by a capacitance between a fixed electrode and a second movable electrode. A first substrate having a pair of main surfaces facing each other and having the first fixed electrode and the second fixed electrode formed on one main surface; and a predetermined distance from the first fixed electrode The first conductive movable part that becomes the first movable electrode arranged opposite to each other, and the second conductive electrode that becomes the second movable electrode arranged opposite to the second fixed electrode with a predetermined interval. A second substrate having two conductive movable parts, wherein the first movable electrode and the second movable electrode are electrically Connected, capacitive dynamic quantity sensor, characterized in that it is connected to an outside end portion extraction common electrode.   A first mechanical quantity sensor that detects a first mechanical quantity by a capacitance between a first fixed electrode that forms a pair of opposed electrodes and a first movable electrode, and a first dynamic quantity sensor that forms another pair of opposed electrodes A capacitive mechanical quantity sensor formed by laminating and integrating a second mechanical quantity sensor for detecting a second mechanical quantity by electrostatic capacitance between two fixed electrodes and a second movable electrode, A first fixed electrode for the pressure sensor formed on one main surface of the pair of main surfaces facing away from each other, and a first for the acceleration sensor formed on the other main surface of the pair of main surfaces. Two fixed electrodes, and a first substrate having a conductive member embedded so as to be substantially flush with the pair of main surfaces, respectively, and the first fixed electrode disposed opposite to the first fixed electrode. A second substrate having a first conductive movable part to be a first movable electrode, and the second fixed electrode; A third substrate having a second conductive movable portion that is the second movable electrode disposed to face each other at a predetermined interval, and the first fixed electrode and the second fixed electrode are A capacitance type mechanical quantity sensor which is electrically connected through a conductive member and is connected to the outside at a common electrode lead-out end.   An electrode extraction end portion of each of the first and second fixed electrodes and an electrode extraction end portion common to the first and second movable electrodes are on the other main surface of the pair of main surfaces of the first substrate. The capacitance type mechanical quantity sensor according to claim 1, wherein the capacitance type mechanical quantity sensor is formed.   The electrode extraction end portion common to the first and second fixed electrodes and the electrode extraction end portion of the first and second movable electrodes are disposed in the same plane. Capacitive mechanical sensor.   4. The capacitive mechanical quantity sensor according to claim 1, wherein the first substrate is a glass substrate, and the second substrate is a silicon substrate.   5. The capacitive mechanical quantity sensor according to claim 2, wherein the first substrate is a glass substrate, and the second and third substrates are silicon substrates.   The capacitive mechanical quantity sensor according to claim 6, wherein the conductive member is a silicon member embedded in the glass substrate.   The capacitive mechanical quantity sensor according to claim 7, wherein the sensor has an Si—Si bond or an Si—O bond at an interface between the glass substrate and the silicon member.   The first conductive movable part is a pressure-sensitive diaphragm that is displaced by a measured pressure, and a swing member that detects pressure using the pressure-sensitive diaphragm and swings the second conductive movable part by a measured acceleration. The capacitance type mechanical quantity sensor according to claim 1, wherein acceleration is detected using the swing member.

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