JP2010281789A - Electrostatic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent bonding of a movable part and a glass substrate during bonding of a positive electrode. <P>SOLUTION: A silicon substrate 4 having the movable part 6 displaceable in the thickness direction is sandwiched between the first and second glass substrates 2 and 3. The inside of a cavity 3A of the second glass substrate 3 includes a fixed electrode 9 facing the movable part 6, and the same-potential electrode 10 that is electrically connected to the movable part 6 and surrounds the fixed electrode 9. The bottom surface of the cavity 3A includes a substrate electrode 12 facing the fixed electrode 9 and same-potential electrode 10 with respect to an interlayer dielectric 11. The substrate electrode 12 includes a first electrode 12A connected to the fixed electrode 9, and a second electrode 12B connected to the same-potential electrode 10. The second electrode 12B covers the gap G between the fixed electrode 9 and the same-potential electrode 10, and a section facing the gap G forms a shield 13. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrostatic device suitably used for an acceleration sensor, an angular velocity sensor and the like, for example.

  In general, as an electrostatic device, a silicon substrate is provided on the surface of a glass substrate, a movable part that can be displaced in the thickness direction is formed on the silicon substrate, and a fixed electrode facing the movable part is provided on the glass substrate. An acceleration sensor is known (see, for example, Patent Document 1). This acceleration sensor is configured to detect the acceleration acting on the sensor by detecting the capacitance between the movable part and the fixed electrode.

  In the acceleration sensor according to Patent Document 1, the glass substrate is provided with the same potential electrode that is located around the fixed electrode and has the same potential as the movable portion. This prevents the movable part from being bonded to the glass substrate when anodically bonding the glass substrate and the silicon substrate.

JP-A-5-172846

  By the way, in the acceleration sensor described in Patent Document 1 described above, the electrostatic force generated between the movable part and the glass substrate at the time of anodic bonding is cut off using the same potential electrode. However, since the fixed electrode and the same potential electrode need to be insulated from each other, a gap is formed between the fixed electrode and the same potential electrode, and the glass substrate is exposed in the gap. For this reason, since an electrostatic force acts between the exposed part of the glass substrate and the movable part, the movable part comes into contact with the exposed part of the glass substrate during anodic bonding, and the movable part and the glass substrate And may be joined.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide an electrostatic device capable of preventing the movable portion and the glass substrate from being joined at the time of anodic bonding. is there.

  In order to solve the above-described problems, the present invention provides a glass substrate, a silicon substrate having a movable portion provided on the glass substrate and displaceable in a thickness direction, and provided on the glass substrate and facing the movable portion. The present invention is applied to an electrostatic device including a fixed electrode arranged at a position and an equipotential electrode that is insulated from the fixed electrode and provided on the glass substrate and has the same potential as the movable portion.

  A feature of the configuration adopted by the invention of claim 1 is that a horizontal gap is formed between the fixed electrode and the same potential electrode, and the thickness direction of the fixed electrode and the same potential electrode is relative to the thickness direction. A base electrode opposite to the fixed electrode and the same potential electrode is provided at a position opposite to the movable portion with an interlayer insulating film interposed therebetween, and the base electrode has a gap between the fixed electrode and the same potential electrode. And having a shield part electrically connected to one of the fixed electrode and the same potential electrode.

  In the invention of claim 2, the base electrode comprises a first electrode portion electrically connected to the fixed electrode and a second electrode portion connected to the same potential electrode, and the shield portion is , Using the first electrode portion.

  According to a third aspect of the present invention, the entire base electrode including the shield portion is connected to the same potential electrode.

  According to a fourth aspect of the present invention, the fixed electrode has a configuration in which at least a peripheral portion thereof overlaps with the same potential electrode in a thickness direction with an insulating film interposed therebetween.

  According to the first aspect of the present invention, the base electrode opposed to the movable portion in the thickness direction is provided between the fixed electrode and the same potential electrode with the interlayer insulating film interposed therebetween, and the base electrode The shield part which covers the clearance gap between a fixed electrode and an equipotential electrode was formed. For this reason, the electrostatic force generated in the gap between the fixed electrode and the same potential electrode at the time of anodic bonding using the shield portion by electrically connecting the shield portion to one of the fixed electrode and the same potential electrode. It can be reliably shut off. Thereby, joining of a movable part and a glass substrate can be prevented, and the yield at the time of manufacture can be improved.

  According to the invention of claim 2, since the shield part is formed using the first electrode part electrically connected to the fixed electrode, the area of the fixed electrode can be substantially increased. Thereby, the electrostatic capacitance between a fixed electrode and a shield part, and a movable part can be enlarged, and the detection sensitivity of the displacement of a movable part can be improved.

  According to the invention of claim 3, since the entire base electrode including the shield portion is connected to the same potential electrode, noise from the outside can be blocked by the entire base electrode, and the noise resistance performance is improved. Can be increased.

  According to the invention of claim 4, since the fixed electrode has a configuration in which at least a peripheral portion thereof overlaps with the same potential electrode in the thickness direction with an insulating film interposed therebetween, the glass substrate is not spaced between the fixed electrode and the same potential electrode. Can be covered. For this reason, the electric field generated between the glass substrate and the movable part at the time of anodic bonding can be reliably blocked by the fixed electrode and the same potential electrode, and the bonding between the movable part and the glass substrate can be prevented. Yield can be improved.

1 is an exploded perspective view showing an acceleration sensor according to a first embodiment of the present invention. It is a longitudinal cross-sectional view which shows the acceleration sensor in FIG. It is sectional drawing which looked at the acceleration sensor from the arrow III-III direction in FIG. It is sectional drawing which looked at the fixed electrode, the same potential electrode, etc. from the arrow IV-IV direction in FIG. It is a longitudinal cross-sectional view which shows the state which joined the silicon substrate to the 1st glass substrate by the 1st glass substrate joining process. It is a longitudinal cross-sectional view which shows the state which grind | polished the surface of the silicon substrate by the surface grinding | polishing process. It is a longitudinal cross-sectional view which shows the state which formed the support part, the movable part, the support beam, etc. in the silicon substrate by the movable part formation process. It is a longitudinal cross-sectional view which shows the state which formed the fixed electrode, the same potential electrode, the base electrode, etc. in the 2nd glass substrate by the 2nd glass substrate formation process. It is a longitudinal cross-sectional view which shows the state which joins a 2nd glass substrate to a silicon substrate by a 2nd glass substrate joining process. It is a longitudinal cross-sectional view of the same position as FIG. 2 which shows the acceleration sensor by the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view of the same position as FIG. 2 which shows the acceleration sensor by the 3rd Embodiment of this invention. It is a top view which shows the angular velocity sensor by 4th Embodiment in the state which remove | excluded the 2nd glass substrate. It is a top view which expands and shows the principal part of the angular velocity sensor in FIG. It is sectional drawing which looked at the angular velocity sensor from the arrow XIV-XIV direction in FIG. It is sectional drawing of the same position as FIG. 14 which shows an angular velocity sensor in the state which the detection mass part vibrated to Z-axis direction. It is sectional drawing which looked at the 2nd glass substrate from the arrow XVI-XVI direction in FIG. It is sectional drawing of the same position as FIG. 16 which shows a 2nd glass substrate in the state which excluded the fixed side detection electrode and the interlayer insulation film. It is typical explanatory drawing which shows an angular velocity sensor. It is typical explanatory drawing which shows an angular velocity sensor in the state which the drive mass part vibrated. It is a circuit block diagram which shows the vibration control circuit and angular velocity detection circuit of an angular velocity sensor. It is a longitudinal cross-sectional view of the same position as FIG. 2 which shows the acceleration sensor by the 5th Embodiment of this invention. It is a longitudinal cross-sectional view of the same position as FIG. 2 which shows the acceleration sensor by a modification.

  Hereinafter, an electrostatic device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  First, FIGS. 1 to 9 show a first embodiment. In this embodiment, an acceleration sensor will be described as an example of an electrostatic device.

  In the figure, the acceleration sensor 1 is formed by first and second glass substrates 2 and 3 and a silicon substrate 4 sandwiched between the glass substrates 2 and 3. Here, the glass substrates 2 and 3 are made of, for example, an insulating glass material, and are formed in a square shape having a size of about several millimeters.

  Further, on the back surface (facing surface) facing the silicon substrate 4 in the second glass substrate 3, a rectangular cavity 3A is formed that is located in the center portion and is recessed in the thickness direction. And between the glass substrates 2 and 3, the accommodation space S which accommodates the below-mentioned movable part 6 in the position corresponding to the cavity 3A is defined. At this time, the second glass substrate 3 constitutes a lid that covers the accommodation space S. Further, the glass substrates 2 and 3 and the silicon substrate 4 spread in the horizontal direction along the X axis and the Y axis, for example, when the three axis directions orthogonal to each other are taken as the X axis, the Y axis, and the Z axis.

  On the other hand, the silicon substrate 4 is formed using, for example, a low-resistance silicon material having conductivity. The silicon substrate 4 is provided with a support part 5, a movable part 6, a support beam 7, and an electrode support part 8 which will be described later.

  The support portion 5 is formed on the silicon substrate 4 and is bonded and fixed to the first and second glass substrates 2 and 3. The support portion 5 includes, for example, a support frame portion 5A formed in a rectangular frame shape extending along the periphery of the glass substrates 2 and 3, and a connection fixing portion 5B protruding from the support frame portion 5A toward the center side. And is composed of.

  Here, the support frame portion 5A surrounds the movable portion 6, the support beam 7, and the like. The support frame 5A has a thickness dimension of about several tens of μm and is bonded to the glass substrates 2 and 3. Thus, the support frame portion 5A holds an airtight accommodation space S for accommodating the movable portion 6 and the like between the glass substrates 2 and 3. On the other hand, the connection fixing portion 5B is disposed on one side in the X-axis direction, for example, and is connected to the support frame portion 5A.

  The movable portion 6 is formed on the silicon substrate 4 and is supported by the connecting and fixing portion 5B using a support beam 7 described later. The movable portion 6 is disposed on the center side of the glass substrates 2 and 3 and can be displaced in the thickness direction (Z-axis direction). Here, the movable part 6 is formed in, for example, a rectangular flat plate shape and has a thickness dimension smaller than that of the support part 5.

  The movable part 6 faces the glass substrates 2 and 3 with a gap, and a gap is formed between the movable part 6 and the glass substrates 2 and 3. Thereby, the movable part 6 is displaced in the thickness direction according to the inertial force due to the acceleration. The movable portion 6 is formed using a low-resistance silicon material together with the support portion 5 and the like, and is electrically connected to the connecting and fixing portion 5B through a support beam 7 described later. Thereby, the movable part 6 constitutes a movable detection electrode in which the capacitance between the movable part 6 and the fixed electrode 9 described later changes according to the position in the thickness direction. Further, the movable portion 6 is formed with a plurality of through holes 6A penetrating in the thickness direction.

  For example, two support beams 7 are provided between the movable portion 6 and the support portion 5, and support the movable portion 6 in a cantilever state so as to be displaceable in the thickness direction. These support beams 7 are formed, for example, as beams bent in a crank shape, are positioned between the glass substrates 2 and 3 and extend in the horizontal direction, and are perpendicular to the glass substrates 2 and 3 (thickness direction). Are separated.

  Each support beam 7 has a proximal end connected to the connection fixing portion 5 </ b> B and a distal end connected to the movable portion 6. The support beam 7 is twisted or bent in the vertical direction when the movable part 6 is displaced toward the glass substrates 2 and 3. Further, the support beam 7 has, for example, the same thickness as the movable part 6. As a result, the support beam 7 can be easily deformed in the vertical direction.

  The electrode support portion 8 is formed on the silicon substrate 4 and is bonded and fixed to the glass substrates 2 and 3 similarly to the support portion 5. However, the electrode support portion 8 is separated from the support portion 5 and insulated from the support portion 5. Moreover, the electrode support part 8 is formed in, for example, a rectangular island shape, and is disposed on the other side in the X-axis direction. The electrode support portion 8 is electrically connected to a fixed electrode 9 described later.

  The fixed electrode 9 is provided on the back side of the second glass substrate 3 at a position facing the movable portion 6. The fixed electrode 9 is disposed in the cavity 3A of the glass substrate 3 and faces the bottom surface of the cavity 3A of the glass substrate 3 with a base electrode 12 and an interlayer insulating film 11 described later interposed therebetween. The fixed electrode 9 is formed of a conductive metal thin film such as platinum / chromium (Pt / Cr), gold / chromium (Au / Cr), or platinum / titanium (Pt / Ti).

  On the other hand, the fixed electrode 9 includes a wiring portion 9A that faces the movable portion 6 over substantially the entire surface and extends toward the other side in the X-axis direction. The tip of the wiring portion 9A is in contact with the electrode support portion 8. Thereby, the fixed electrode 9 is connected to the fixed extraction electrode 16 to be described later through the electrode support portion 8. The fixed electrode 9 constitutes a fixed detection electrode that detects the displacement of the movable portion 6 with respect to the thickness direction.

  The equipotential electrode 10 is provided on the back surface side of the second glass substrate 3, and is provided on the back surface of the interlayer insulating film 11 in the same manner as the fixed electrode 9. The equipotential electrode 10 is formed using, for example, the same conductive metal thin film as the fixed electrode 9, and faces the bottom surface of the cavity 3A of the glass substrate 3 with a base electrode 12 and an interlayer insulating film 11 described later interposed therebetween. . The equipotential electrode 10 is formed in a C shape surrounding the fixed electrode 9, and a horizontal gap G is formed between the same electrode 10 and the fixed electrode 9. For this reason, the equipotential electrode 10 and the fixed electrode 9 are insulated from each other.

  On the other hand, the equipotential electrode 10 includes a wiring portion 10A extending toward one side in the X-axis direction. The leading end of the wiring portion 10 </ b> A is in contact with the connection fixing portion 5 </ b> B of the support portion 5. That is, the equipotential electrode 10 is electrically connected to the movable portion 6 through the support portion 5 and the support beam 7 and has the same potential as the movable portion 6. Thereby, the equipotential electrode 10 prevents an electrostatic force from acting between the movable part 6 and the glass substrate 3 during anodic bonding, and prevents the movable part 6 from adhering to the glass substrate 3 and being fixed. An anti-sticking electrode is formed. The equipotential electrode 10 is disposed at the same position in the thickness direction as the fixed electrode 9, and forms the outermost surface electrode layer exposed to the movable part 6 side together with the fixed electrode 9.

The interlayer insulating film 11 is formed of, for example, an insulating material such as silicon oxide (SiO ₂ ) or silicon nitride (SiN). The outermost layer electrode layer including the fixed electrode 9 and the same potential electrode 10 and a base electrode 12 (base electrode) described later. Layer). Here, the interlayer insulating film 11 is provided in the cavity 3A of the glass substrate 3 and covers the base electrode 12 over the entire surface. In the interlayer insulating film 11, a first through hole 11 </ b> A is formed at a position facing the fixed electrode 9, and a second through hole 11 </ b> B is formed at a position facing the same potential electrode 10.

  The base electrode 12 is provided on the bottom surface of the cavity 3 </ b> A of the glass substrate 3 and is covered with the interlayer insulating film 11. The base electrode 12 forms a base electrode layer by the first and second electrode portions 12A and 12B that are insulated from each other. Here, the first electrode portion 12 </ b> A is disposed at a position facing the fixed electrode 9, and is formed with an area smaller than that of the fixed electrode 9, for example. The first electrode portion 12A is electrically connected to the fixed electrode 9 through the first through hole 11A.

  On the other hand, the second electrode portion 12 </ b> B is disposed at a position facing the same potential electrode 10, and is formed in a C shape like the same potential electrode 10. The second electrode portion 12B is electrically connected to the same potential electrode 10 through the second through hole 11B.

  The second electrode portion 12 </ b> B covers the gap G between the fixed electrode 9 and the same potential electrode 10. As a result, the portion of the second electrode portion 12B facing the gap G constitutes the shield portion 13, and the shield portion 13 generates the electrostatic force generated between the glass substrate 3 and the movable portion 6 during anodic bonding. The movable part 6 is attracted to the glass substrate 3 side and is prevented from adhering to the glass substrate 3 side.

  The stoppers 14 are formed of an insulating material such as silicon oxide or silicon nitride, and a plurality of stoppers 14 are provided on the back surfaces (exposed surfaces) of the fixed electrode 9 and the same potential electrode 10. And the stopper 14 protrudes toward the movable part 6, prevents the movable part 6, the fixed electrode 9, and the same potential electrode 10 from contacting each other, and prevents them from being electrically short-circuited.

  The movable-side extraction electrode 15 is disposed at a position corresponding to the connection fixing portion 5B in the second glass substrate 3, and is electrically connected to the movable portion 6 through the connection fixing portion 5B and the support beam 7. The movable part extraction electrode 15 is formed by forming a signal via hole (through hole) penetrating in the thickness direction in the glass substrate 3 by using, for example, laser processing, sandblasting, microblasting, or the like. It is formed by providing a conductive metal film such as copper (Cu) or aluminum (Al) in the hole.

  The fixed-side extraction electrode 16 is disposed at a position corresponding to the electrode support portion 8 in the second glass substrate 3, and is electrically connected to the fixed electrode 9 through the electrode support portion 8. The fixed-side extraction electrode 16 is formed by providing a conductive metal film such as copper (Cu) in a through hole penetrating the substrates 2 and 3, similarly to the movable-side extraction electrode 15.

  The extraction electrodes 15 and 16 are connected to an external detection circuit or the like. The detection circuit detects a signal corresponding to the capacitance between the extraction electrodes 15 and 16. Since the output of this detection signal changes according to the displacement of the movable part 6, the detection circuit can detect the acceleration acting on the acceleration sensor 1 using the output of this detection signal.

  The acceleration sensor 1 according to the present embodiment is configured as described above, and the operation thereof will be described next.

  First, when acceleration acts on the acceleration sensor 1, the movable part 6 is displaced in the thickness direction of the glass substrates 2 and 3 by inertial force. At this time, the capacitance C1 between the movable part 6 and the fixed electrode 9 increases or decreases. For this reason, the external detection circuit detects a signal corresponding to the capacitance C1 between the movable portion 6 and the fixed electrode 9 using the extraction electrodes 15 and 16, and uses this detection signal to detect the acceleration sensor 1. Acceleration acting on the is detected.

  Next, a method for manufacturing the acceleration sensor 1 will be described with reference to FIGS.

  First, in the first glass substrate bonding step shown in FIG. 5, a silicon substrate 21 before processing is prepared. Then, an etching process or the like is performed on the back surface side of the silicon substrate 21 to form the recessed portion 21A. At this time, a thin metal film made of, for example, aluminum may be provided as a protective film on the exposed surface of the recessed portion 21A. In this state, the back side of the silicon substrate 21 is bonded to the first glass substrate 2 by using, for example, an anodic bonding method or the like.

  Next, in the surface polishing step shown in FIG. 6, for example, the surface of the silicon substrate 21 is ground and polished to the position indicated by the two-dot chain line in FIG. Thereby, for example, a silicon substrate 22 having a thickness of about several tens of μm is formed. Thereafter, a contact portion 23 made of a conductive metal thin film is formed on the surface of the silicon substrate 22 at positions where the connection fixing portion 5B and the electrode support portion 8 are to be formed. Specifically, the contact portion 23 is formed of, for example, a platinum / chrome metal thin film in which platinum having a thickness of 80 nm and chromium having a thickness of 20 nm are stacked. And the contact part 23 forms the contact | adherence layer closely_contact | adhered to the fixed electrode 9 and the connection fixing | fixed part 5B, and raises the electrical connection of the same potential electrode 10 and the electrode support part 8. FIG.

  Next, in the movable part forming step shown in FIG. 7, a photoresist or the like is applied to the surface of the silicon substrate 22, and predetermined patterning is performed, so that the position corresponding to the support part 5, the movable part 6, the support beam 7, etc. A mask is formed. In this state, etching is performed from the surface of the silicon substrate 22 until the silicon substrate 22 penetrates, and unnecessary portions of the silicon substrate 22 are removed. Thereby, the silicon substrate 4 provided with the support part 5, the movable part 6, and the support beam 7 is formed. When a protective film is formed on the recessed portion 21A of the silicon substrate 22, another etching process for removing the protective film is performed after the etching process of the silicon substrate 22. And when a movable part formation process is complete | finished, the movable part 6 will be in the state which can be displaced to thickness direction.

  On the other hand, in the second glass substrate forming step shown in FIG. 8, an insulating glass substrate 24 that becomes the second glass substrate 3 of the acceleration sensor 1 is prepared. Then, the back surface of the glass substrate 24 is subjected to an etching process using buffered hydrofluoric acid (BHF) through a metal mask such as chromium (Cr) or gold (Au). As a result, a cavity 3 </ b> A is formed on the back surface of the glass substrate 24. Next, a conductive metal thin film such as chromium or titanium is formed on the bottom surface of the cavity 3A by using, for example, sputtering or vapor deposition, and the base electrode 12 is formed by patterning the metal thin film.

  Thereafter, an interlayer insulating film 11 made of an insulating material such as silicon oxide or silicon nitride is formed so as to cover the base electrode 12. At this time, the interlayer insulating film 11 is also patterned to form through holes 11A and 11B at positions corresponding to the first and second electrode portions 12A and 12B of the base electrode 12, respectively. Further, a conductive metal thin film such as platinum / chrome is formed on the back surface of the interlayer insulating film 11, and the fixed electrode 9 and the equipotential electrode 10 are formed by patterning the metal thin film. At this time, the fixed electrode 9 is electrically connected to the first electrode portion 12A through the through hole 11A, and the equipotential electrode 10 is electrically connected to the second electrode portion 12B through the through hole 11B. Through the above steps, the second glass substrate 3 including the fixed electrode 9, the same potential electrode 10, the base electrode 12, and the like is formed.

  Next, in the second glass substrate bonding step shown in FIG. 9, with the second glass substrate 3 stacked on the silicon substrate 4, these are bonded using an anodic bonding method. Specifically, the first and second glass substrates 2 and 3 and the silicon substrate 4 are made of, for example, a conductive metal material in a state where the back surface side of the second glass substrate 3 is in contact with the surface of the silicon substrate 4. Is sandwiched between a pair of electrode jigs 25A and 25B.

  At this time, since the positive voltage V + is applied from the voltage source 26 to the back surface of the first glass substrate 2 by the electrode jig 25A, the voltage V + is applied to the silicon substrate through the resistance R in the first glass substrate 2. 4 is supplied. For this reason, although the potential of the silicon substrate 4 is lowered by the resistance R, it is a positive potential and the same potential over the entire silicon (Si). On the other hand, since a negative voltage V− (for example, ground voltage) is applied from the voltage source 26 to the surface of the second glass substrate 3 by the electrode jig 25B, the silicon substrate 4 and the second glass substrate are thereby obtained. 3 and the electrostatic force acts between the two glass substrates 3 and strongly attracts each other, and the support portion 5 and the electrode support portion 8 are bonded to the second glass substrate 3.

  As a result, an airtight storage space S is defined between the first and second glass substrates 2 and 3, and the movable portion 6 is disposed in the storage space S. And the movable part 6 is arrange | positioned in the position facing the fixed electrode 9 of the glass substrates 2 and 3 in the state which can be displaced to thickness direction. In addition, the fixed electrode 9, the equipotential electrode 10, and the contact portion 23 come into contact with each other, for example, by strongly pressing each other's platinum by an electrostatic force during anodic bonding. Thereby, the fixed electrode 9 is electrically connected to the electrode support portion 8, and the same potential electrode 10 is electrically connected to the connection fixing portion 5B.

  Finally, a through hole is formed in the second glass substrate 2 at a position corresponding to the connection fixing portion 5B and the electrode support portion 8, and conductive such as copper (Cu) or aluminum (Al) is formed in the through hole. A metal film is provided. Thereby, the movable-side extraction electrode 15 connected to the movable portion 6 and the fixed-side extraction electrode 16 connected to the fixed electrode 9 are formed, and the acceleration sensor 1 is completed (see FIG. 2).

  However, the fixed electrode 9 is connected to the electrode support portion 8 of the silicon substrate 4, and the same potential electrode 10 is connected to the connection fixing portion 5 </ b> B of the silicon substrate 4. For this reason, even when a potential difference occurs between the silicon substrate 4 and the second glass substrate 3 during anodic bonding (second glass substrate bonding step) in which the second glass substrate 3 is bonded to the silicon substrate 4, The fixed electrode 9 and the same potential electrode 10 have the same potential as the movable part 6. As a result, an electrostatic force does not act on the electrostatic capacitance C1 between the movable portion 6 and the fixed electrode 9, and an electrostatic force is applied to the electrostatic capacitance C2 between the movable portion 6 and the same potential electrode 10. Does not work.

  On the other hand, when the base electrode 12 is not provided as in the prior art, the glass substrate 3 is exposed in the gap G between the fixed electrode 9 and the same potential electrode 10, so that the gap G portion and An electrostatic force acts on the capacitance C3 between the movable portion 6 and the movable portion 6. At this time, since the movable part 6 is formed to be displaceable in the thickness direction, it tends to be easily deformed even when a slight force is applied. Furthermore, anodic bonding may be performed in a state where the electrode jig 25B is arranged on the lower side, that is, in a state where the second glass substrate 3 is turned over. In this case, the movable portion 6 is moved to the glass substrate 3 side by its weight. Get closer to. For this reason, in the prior art, the movable part 6 may be displaced to the glass substrate 3 side and may be joined to the glass substrate 3 at the gap G.

  On the other hand, in the present embodiment, the base electrode 12 facing the fixed electrode 9 and the equipotential electrode 10 via the interlayer insulating film 11 is provided, and the gap G is covered by the base electrode 12. At this time, since the base electrode 12 is electrically connected to either the fixed electrode 9 or the same potential electrode 10, the base electrode 12 is also at the same potential as the movable portion 6. For this reason, since the electric field at the time of anodic bonding in the gap G can be blocked by the base electrode 12, the bonding between the movable portion 6 and the glass substrate 3 can be prevented.

  Thus, in the present embodiment, the second glass substrate 3 is provided with the fixed electrode 9 and the base electrode 12 opposed to the same potential electrode 10 with the interlayer insulating film 11 interposed therebetween, and the base electrode 12 has a fixed electrode. The shield part 13 which covers the clearance gap G between 9 and the same potential electrode 10 was formed. For this reason, by electrically connecting the shield part 13 to the equipotential electrode 10, the electrostatic force generated in the gap G between the fixed electrode 9 and the equipotential electrode 10 during the anodic bonding can be ensured using the shield part 13. Can be blocked. Thereby, joining with the movable part 6 and the glass substrate 3 can be prevented, and the yield at the time of manufacture can be improved.

  Next, FIG. 10 shows a second embodiment according to the present invention. The feature of this embodiment is that the shield portion is formed by using the first electrode portion electrically connected to the fixed electrode among the base electrodes. It is in forming. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The acceleration sensor 31 according to the second embodiment is sandwiched between the first and second glass substrates 2 and 3 and the glass substrates 2 and 3 in substantially the same manner as the acceleration sensor 1 according to the first embodiment. The silicon substrate 4 is formed. The silicon substrate 4 is provided with a support portion 5, a movable portion 6, a support beam 7 and the like, and the second glass substrate 3 is provided with a fixed electrode 9 and an equipotential electrode 10.

  The base electrode 32 is provided on the bottom surface of the cavity 3 </ b> A of the glass substrate 3 and is covered with the interlayer insulating film 11. The base electrode 32 constitutes a base electrode layer by the first and second electrode portions 32A and 32B that are insulated from each other. Here, the first electrode portion 32 </ b> A is disposed at a position facing the fixed electrode 9, and is formed to have a larger area than the fixed electrode 9, for example. The first electrode portion 32A is electrically connected to the fixed electrode 9 through the first through hole 11A.

  On the other hand, the second electrode portion 32 </ b> B is disposed at a position facing the same potential electrode 10, and is formed in a C shape like the same potential electrode 10. The second electrode portion 32B is electrically connected to the same potential electrode 10 through the second through hole 11B.

  The first electrode portion 32 </ b> A covers the gap G between the fixed electrode 9 and the same potential electrode 10. As a result, the portion of the first electrode portion 32 </ b> A that faces the gap G constitutes a shield portion 33 that blocks the electric field between the glass substrate 3 and the movable portion 6 at the position of the gap G.

  Thus, in the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment. In particular, in the present embodiment, since the shield part 33 is formed using the first electrode part 32A electrically connected to the fixed electrode 9, the area of the fixed electrode 9 can be substantially increased. Thereby, the electrostatic capacitance between the fixed electrode 9 and the shield part 33 and the movable part 6 can be increased, and the detection sensitivity of the displacement of the movable part 6 can be increased.

  Next, FIG. 11 shows a third embodiment according to the present invention. The feature of this embodiment is that the base electrode is configured to be connected to the same potential electrode as a whole including the shield portion. . In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The acceleration sensor 41 according to the third embodiment is sandwiched between the first and second glass substrates 2 and 3 and these glass substrates 2 and 3 in substantially the same manner as the acceleration sensor 1 according to the first embodiment. The silicon substrate 4 is formed. The silicon substrate 4 is provided with a support portion 5, a movable portion 6, a support beam 7 and the like, and the second glass substrate 3 is provided with a fixed electrode 9 and an equipotential electrode 10.

  The interlayer insulating film 42 is formed in substantially the same manner as the interlayer insulating film 11 according to the first embodiment, and is provided in the cavity 3A of the glass substrate 3 so as to cover a base electrode 43 described later. The interlayer insulating film 42 is located between the fixed electrode 9, the same potential electrode 10, and the base electrode 43, and the interlayer insulating film 42 has a through hole 42 </ b> A formed at a position corresponding to the same potential electrode 10. Yes.

  The base electrode 43 is provided on the bottom surface of the cavity 3 </ b> A of the glass substrate 3 and is covered with the interlayer insulating film 11. The base electrode 43 is formed of, for example, a single metal thin film that covers the entire bottom surface of the cavity 3A. The base electrode 43 is formed with a larger area than the fixed electrode 9 and faces the fixed electrode 9 and the same potential electrode 10. Further, the entire base electrode 43 is electrically connected to the same potential electrode 10 through the through hole 42A. The base electrode 43 covers the gap G between the fixed electrode 9 and the same potential electrode 10. As a result, the portion of the base electrode 43 that faces the gap G constitutes a shield portion 44.

  Thus, in the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment. In particular, in the present embodiment, since the entire base electrode 43 including the shield portion 44 is connected to the same potential electrode 10, external noise can be blocked by the entire base electrode 43 and fixed. It is possible to prevent noise from entering the electrode 9 and improve noise resistance.

  Next, FIGS. 12 to 20 show a fourth embodiment according to the present invention, and the features of this embodiment are applied to an angular velocity sensor capable of detecting angular velocities around two axes as an electrostatic device. It is in the configuration.

  In the figure, an angular velocity sensor 51 is formed by first and second glass substrates 52 and 53 and a silicon substrate 54 sandwiched between these glass substrates 52 and 53. The angular velocity sensor 51 includes drive mass units 56 to 59, connection beams 60, connection units 61 to 64, drive beams 65 to 68, vibration generation units 69 to 72, detection mass units 74 to 77, and detection beams 78 to 77, which will be described later. 81, displacement detectors 82 to 85, vibration monitor units 91 to 94, and the like.

  The first glass substrate 52 constitutes a base portion of the angular velocity sensor 51. The glass substrate 52 is formed into a rectangular flat plate shape using a glass material, and extends horizontally, for example, along the X-axis and Y-axis directions among the X-axis, Y-axis, and Z-axis directions orthogonal to each other. .

  The second glass substrate 53 is formed in a square plate shape using a glass material, and is bonded to the silicon substrate 54 by anodic bonding. The glass substrate 53 constitutes a lid that covers the driving mass portions 56 to 59, the connecting beam 60, the connection portions 61 to 64, the driving beams 65 to 68, and the like. Further, the glass substrate 53 is formed with a cavity 53 </ b> A that is recessed in a substantially circular shape on the side (back surface) facing the detection mass units 74 to 77. The cavity 53A includes a driving mass unit 56 to 59, a connecting beam 60, a connection unit 61 to 64, a driving beam 65 to 68, a detection mass unit 74 to 77, a detection beam 78 to 81, a vibration generating unit 69 to 72, and a vibration. It is provided at a position facing the monitor units 91-94. Thereby, the drive mass units 56 to 59 and the detection mass units 74 to 77 can be displaced by vibration without contacting the glass substrate 53.

  The silicon substrate 54 is formed using, for example, a low-resistance silicon material having conductivity. Further, by etching the silicon substrate 54, the support portion 55, the drive mass portions 56 to 59, the connection beam 60, the connection portions 61 to 64, the drive beams 65 to 68, the drive land 73, and the detection mass portion. 74 to 77, detection beams 78 to 81, detection lands 86, vibration monitor portions 91 to 94, monitor lands 95, shield lands 96, and the like are formed. The silicon substrate 54 is bonded to the first and second glass substrates 52 and 53 by, for example, anodic bonding.

  A sealing frame that surrounds the entire angular velocity sensor 51 is formed on the silicon substrate 54, and using the sealing frame, a support portion 55 that becomes a movable portion, drive mass portions 56 to 59, a connecting beam 60, and connection portions 61 to 61 are provided. 64, driving beams 65 to 68, and the like may be sealed in a reduced-pressure atmosphere.

  The support part 55 is provided on the surface of the glass substrate 52. Further, the support portions 55 are arranged at four positions on the corner side of the glass substrate 52, respectively. In addition, driving mass units 56 to 59, detection mass units 74 to 77, and the like are provided in a state of being floated from the first glass substrate 52 at a central side portion of the glass substrate 52 surrounded by the four support units 55. ing. In addition, movable drive electrodes 69A to 72A of vibration generating sections 69 to 72, which will be described later, detection mass sections 74 to 77 serving as movable detection electrodes of the displacement detection sections 82 to 85, and the like are connected to the ground via the support section 55. Has been.

  The driving mass units 56 to 59 are opposed to the surface of the glass substrate 52 with a gap, and are disposed at positions that are point-symmetric with respect to the center (center point O). The drive mass units 56 to 59 are arranged at equal intervals from each other every 90 ° with respect to the circumferential direction surrounding the center point O. For this reason, the X-axis side drive mass units 56 and 57 are disposed along the X-axis and face each other with the center point O interposed therebetween. On the other hand, the Y-axis side drive mass units 58 and 59 are disposed along the Y axis orthogonal to the X axis, and face each other with the center point O interposed therebetween.

  Moreover, the drive mass parts 56-59 are formed in the substantially pentagonal frame shape, for example. Here, the X-axis-side drive mass units 56 and 57 have inner portions protruding in the X-axis direction toward the center point O, and the width dimension (Y-axis direction dimension) gradually decreases as the center point O approaches. . Similarly, in the Y-axis side driving mass portions 58 and 59, the inner part in the Y-axis direction protrudes toward the center point O, and the width dimension (X-axis direction dimension) gradually decreases as the center point O approaches. . In addition, connecting arm portions 56 </ b> A to 59 </ b> A that protrude toward the center point O are provided at protruding portions (vertex portions) on the inner diameter side of the driving mass portions 56 to 59. At this time, the connecting arm portions 56A to 59A have high rigidity so as not to bend and deform in any of the X-axis, Y-axis, and Z-axis directions. And the tip part of connecting arm parts 56A-59A serves as a fulcrum when drive mass parts 56-59 vibrate on an XY plane, for example.

  The connection beam 60 is formed in an annular shape that surrounds the center point O, and connects the drive mass portions 56 to 59 to each other. Specifically, the connecting beam 60 is formed in, for example, a substantially circular elongated frame shape, and both end portions in the X-axis direction and both end portions in the Y-axis direction are connected to the ends of the connecting arm portions 56A to 59A, respectively. ing. When the driving mass units 56 to 59 drive and vibrate in the circumferential direction surrounding the center point O in a state of being horizontal with the glass substrate 52, the entire connecting beam 60 is bent and deformed so as to have an elliptical shape (see FIG. 19). ). Thereby, the connection beam 60 is adjusted so that the drive amplitude and phase of each drive mass part 56-59 may correspond. The connecting beam 60 is not limited to a circle, and may be formed in a polygonal shape such as a quadrangle or an octagon.

  As shown in FIGS. 12 and 13, the connecting portions 61 to 64 extend radially from the center point O and are connected to the connecting beam 60. In addition, the connection parts 61 to 64 are respectively positioned between two drive mass parts 56 to 59 adjacent in the circumferential direction, and are arranged at point-symmetrical positions with respect to the center point O. For this reason, the connecting portion 61 is disposed between the driving mass portions 56 and 58, and the connecting portion 62 is disposed between the driving mass portions 57 and 59. These connecting portions 61 and 62 are connected to the X axis. Are positioned on an axis inclined by 45 ° and face each other. Similarly, the connecting portion 63 is disposed between the driving mass portions 56 and 59, and the connecting portion 64 is disposed between the driving mass portions 57 and 58. These connecting portions 63 and 64 are connected to the X axis. Are positioned on an axis inclined by −45 ° and face each other. Thereby, the connection parts 61 and 62 and the connection parts 63 and 64 are orthogonal to each other. And the connection parts 61-64 have high rigidity so that it may not bend in any direction of an X-axis, a Y-axis, and a Z-axis.

  The driving beams 65 to 68 are provided at the distal ends of the connection portions 61 to 64, respectively, and connect between the connection portions 61 to 64 and the support portion 55. Here, the driving beams 65 to 68 are configured by, for example, arranging two folded beams facing each other, and are formed in an elongated frame shape extending in a direction orthogonal to the connection portions 61 to 64. And when the connection parts 61-64 are displaced to a length direction, the drive beams 65-68 bend and deform | transform so that the space in a frame may expand and contract. Thereby, the drive beams 65-68 support each connection part 61-64 so that a displacement in a length direction is possible, when the connection beam 60 bends and deforms.

  The vibration generating units 69 to 72 constitute driving means for driving and vibrating the driving mass units 56 to 59, respectively. The vibration generators 69 to 72 include movable drive electrodes 69A to 72A attached to the outer diameter side of the drive mass units 56 to 59 and fixed drive electrodes attached to the drive lands 73 on the glass substrate 52. 69B to 72B.

  Here, the movable-side drive electrode 69A is composed of, for example, three comb-like electrodes extending radially outward from the drive mass unit 56 around the center point O, and the comb-like electrodes include A plurality of electrode plates are arranged at intervals in the length direction. The movable drive electrode 69A is disposed on one side of the drive mass unit 56 in the Y-axis direction.

  Similarly to the movable side drive electrode 69A, the movable side drive electrode 70A is also composed of, for example, three comb-like electrodes extending radially outward from the drive mass unit 57 around the center point O in the radial direction. ing. However, the movable drive electrode 70A is arranged on the other side of the drive mass unit 57 in the Y-axis direction. As a result, the movable drive electrode 69A and the movable drive electrode 70A are disposed at point symmetry with respect to the center point O.

  On the other hand, the movable drive electrode 71A is constituted by, for example, two comb-like electrodes extending radially outward from the drive mass unit 58 around the center point O, and the comb-like electrode has a long length. A plurality of electrode plates are arranged at intervals in the vertical direction. The movable drive electrode 71A is arranged on one side of the drive mass unit 58 in the X-axis direction.

  Similarly to the movable drive electrode 71A, the movable drive electrode 72A is composed of, for example, two comb-like electrodes that extend radially from the drive mass unit 59 toward the radially outer side centered on the center point O. ing. However, the movable drive electrode 72A is disposed on the other side of the drive mass unit 59 in the X-axis direction. As a result, the movable drive electrode 71A and the movable drive electrode 72A are disposed at point symmetry with respect to the center point O.

  The fixed drive electrodes 69B to 72B are configured by comb-like electrodes extending outward in the radial direction in a state parallel to the movable drive electrodes 69A to 72A. The electrode plates of the movable drive electrodes 69A to 72A and the electrode plates of the fixed drive electrodes 69B to 72B are engaged with each other with a gap.

  The fixed drive electrodes 69B to 72B are respectively attached to and electrically connected to four drive lands 73 fixed to the glass substrate 52. At this time, the four drive lands 73 are provided, for example, at positions sandwiching the support portion 55 connected to the drive beams 67 and 68, and are disposed on both sides in the width direction (circumferential direction) of the support portion 55. Thereby, the fixed side drive electrodes 69B to 72B and the drive land 73 are also arranged at point-symmetrical positions with respect to the center point O, similarly to the movable side drive electrodes 69A to 72A.

  When the same drive signal (voltage signal or the like) is applied to the fixed drive electrodes 69B and 70B, the movable drive electrodes 69A and 70A and the fixed drive electrodes 69B and 70B are opposite to each other along the Y axis. Directional driving force F1, F2 (electrostatic force) is generated. As a result, the drive mass units 56 and 57 vibrate in the Y-axis direction in opposite phases.

  On the other hand, when the same drive signal (voltage signal or the like) is applied to the fixed drive electrodes 71B and 72B, the movable drive electrodes 71A and 72A and the fixed drive electrodes 71B and 72B are opposite to each other along the X axis. Directional driving force F3, F4 (electrostatic force) is generated. As a result, the drive mass units 58 and 59 vibrate in the X-axis direction with phases opposite to each other.

  Furthermore, the vibration generating units 69 to 72 vibrate the four driving mass units 56 to 59 in the circumferential direction surrounding the central portion in a state where the driving mass units 56 to 59 adjacent in the circumferential direction are in opposite phases. . Therefore, when the drive mass units 56 and 58 approach each other, the remaining drive mass units 57 and 59 approach each other, and the drive mass units 56 and 58 and the drive mass units 57 and 59 move away from each other. On the other hand, when the drive mass units 56 and 59 approach each other, the remaining drive mass units 57 and 58 approach each other, and the drive mass units 56 and 59 and the drive mass units 57 and 58 move away from each other.

  The detection mass units 74 to 77 are located inside the drive mass units 56 to 59 and provided in the drive mass units 56 to 59, respectively. The detection mass units 74 to 77 are formed in a substantially pentagonal plate shape similar to the drive mass units 56 to 59. Furthermore, the detection mass units 74 to 77 include connection protrusions 74A to 77A that protrude outward in the radial direction. And the detection mass parts 74-77 are connected to the drive mass parts 56-59 via the connection protrusion parts 74A-77A and the detection beams 78-81 described later, and face the surface of the glass substrate 52 with a gap. . And the detection mass parts 74-77 comprise the movable part which can be displaced to thickness direction.

  The detection beams 78 to 81 are located radially outside the detection mass units 74 to 77 and are provided between the detection mass units 74 to 77 and the drive mass units 56 to 59. The detection mass units 74 to 77 are made of glass. The substrate 52 is supported so as to be displaceable in the thickness direction. Further, the detection beams 78 to 81 extend in the circumferential direction surrounding the center point O, and use the torsion support beams that are torsionally deformed when the detection mass portions 74 to 77 are displaced in the thickness direction of the glass substrate 52. Is formed. Specifically, the detection beams 78 to 81 are formed by elongated plate-like beams bent in a U shape in a folded state.

  The detection beams 78 and 79 are positioned in the drive mass portions 56 and 57 and extend in the Y-axis direction, and connecting projections 74A and 75A for the detection mass portions 74 and 75 are attached to the center portion in the length direction. ing. The detection beams 80 and 81 are positioned in the drive mass portions 58 and 59 and extend in the X-axis direction, and connecting projections 76A and 77A for the detection mass portions 76 and 77 are attached to the central portion in the length direction. ing. Thereby, since the detection mass parts 74 to 77 have a radially inner portion near the center point O as a free end, the detection beams 78 to 81 support the detection mass parts 74 to 77 in a cantilever state.

  When the angular velocity Ω1 around the X-axis acts, the driving mass units 56 and 57 that vibrate in the Y-axis direction have a Coriolis force Fx directed in the Z-axis direction (the thickness direction of the glass substrate 52) according to the angular velocity Ω1. Will occur. At this time, since the detection beams 78 and 79 support the detection mass portions 74 and 75 so as to be displaceable in the Z-axis direction, the detection mass portions 74 and 75 vibrate in the Z-axis direction according to the angular velocity Ω1.

  On the other hand, when the angular velocity Ω2 around the Y-axis is applied, the Coriolis force Fy in the Z-axis direction (the substrate thickness direction) is generated in the drive mass units 58 and 59 that vibrate in the X-axis direction according to the angular velocity Ω2. To do. At this time, since the detection beams 80 and 81 support the detection mass units 76 and 77 so as to be displaceable in the Z-axis direction, the detection mass units 76 and 77 vibrate in the Z-axis direction according to the angular velocity Ω2.

  The displacement detection units 82 to 85 constitute displacement detection means for detecting that the detection mass units 74 to 77 are displaced in the thickness direction of the second glass substrate 53. Moreover, the displacement detection parts 82-85 are comprised by the detection mass parts 74-77 as a movable side detection electrode, and the fixed side detection electrodes 82A-85A which consist of the conductor thin film provided in the 2nd glass substrate 53, for example. ing. Here, the detection mass units 74 to 77 and the fixed-side detection electrodes 82A to 85A face each other in the Z-axis direction.

  The fixed-side detection electrodes 82A to 85A constitute a fixed electrode fixed to the glass substrate 53 and face the bottom surface of the cavity 53A of the glass substrate 53 with a base electrode 89 and an interlayer insulating film 88 described later interposed therebetween. Yes. The fixed detection electrodes 82A to 85A are arranged at positions facing the detection mass units 74 to 77, and are electrically connected to the four detection lands 86 fixed to the glass substrates 52 and 53. Yes. At this time, the four detection lands 86 are arranged on the radially outer side of the drive mass units 56 to 59. Accordingly, the fixed detection electrodes 82A to 85A and the detection land 86 are also arranged at point-symmetric positions with respect to the center point O, similarly to the detection mass units 74 to 77.

  When the detection mass units 74 to 77 vibrate in the Z-axis direction, the distance between the detection mass units 74 to 77 and the fixed-side detection electrodes 82A to 85A changes. As a result, the capacitances Cs1 to Cs4 between the detection mass units 74 to 77 and the fixed-side detection electrodes 82A to 85A also change. For this reason, the displacement detectors 82 to 85 detect the amount of displacement of the detection mass units 74 to 77 in the Z-axis direction by the capacitances Cs1 to Cs4 between the detection mass units 74 to 77 and the fixed detection electrodes 82A to 85A. Detect by change.

  The equipotential electrode 87 is provided on the back surface side of the second glass substrate 53 and is provided on the back surface of the interlayer insulating film 88 in the same manner as the fixed-side detection electrodes 82A to 85A. The equipotential electrode 87 is formed using the same conductive thin film as the fixed-side detection electrodes 82A to 85A, for example, and faces the bottom surface of the cavity 53A of the glass substrate 53 with a base electrode 89 and an interlayer insulating film 88 described later interposed therebetween. Yes. The equipotential electrode 87 is formed in a substantially cross shape surrounding the fixed-side detection electrodes 82A to 85A, and a gap G is formed between the fixed-side detection electrodes 82A to 85A. For this reason, the equipotential electrode 87 and the stationary detection electrodes 82A to 85A are insulated from each other.

  On the other hand, the equipotential electrode 87 includes a wiring portion 87A that is located on the outer side in the radial direction and extends in the circumferential direction. The tip of the wiring portion 87A is in contact with the support portion 55. That is, the equipotential electrode 87 is electrically connected to the detection mass units 74 to 77 through the support unit 55, the drive beams 65 to 68, the connection beam 60, the drive mass units 56 to 59, the detection beams 78 to 81, and the like. It has the same potential as the mass parts 74 to 77. Accordingly, the equipotential electrode 87 prevents an electrostatic force from acting between the detection mass units 74 to 77 and the glass substrate 53 during anodic bonding, and the detection mass units 74 to 77 are fixed to the glass substrate 53. An anti-sticking electrode for preventing the above is formed. The equipotential electrode 87 is disposed at the same position in the thickness direction as the fixed detection electrodes 82A to 85A, and is exposed on the detection mass portions 74 to 77 side together with the fixed detection electrodes 82A to 85A. Is forming.

  The interlayer insulating film 88 is formed using an insulating material, and is provided between the fixed-side detection electrodes 82A to 85A and the same potential electrode 87 and a base electrode 89 described later. Here, the interlayer insulating film 88 is provided in the cavity 53 </ b> A of the glass substrate 53 and covers the base electrode 89 over the entire surface. In the interlayer insulating film 88, a first through hole 88A is formed at a position facing the fixed detection electrodes 82A to 85A, and a second through hole 88B is formed at a position facing the same potential electrode 87. Has been.

  The base electrode 89 is provided on the bottom surface of the cavity 53 </ b> A of the glass substrate 53 and is covered with an interlayer insulating film 88. The base electrode 89 forms a base electrode layer by the first and second electrode portions 89A and 89B that are insulated from each other. Here, the first electrode portion 89A is disposed at a position facing the fixed detection electrodes 82A to 85A, and has a smaller area than, for example, the fixed detection electrodes 82A to 85A. The first electrode portion 89A is electrically connected to the fixed detection electrodes 82A to 85A through the first through hole 88A.

  On the other hand, the second electrode portion 89 </ b> B is disposed at a position facing the same potential electrode 87, and is formed in a substantially cross shape like the same potential electrode 87. The second electrode portion 89B is electrically connected to the same potential electrode 87 through the second through hole 88B.

  The second electrode portion 89B covers the gap G between the fixed side detection electrodes 82A to 85A and the same potential electrode 87. Thereby, the part facing the gap G in the second electrode part 89B constitutes the shield part 90, and the shield part 90 is located between the glass substrate 53 and the detection mass parts 74 to 77 at the position of the gap G. The electric field is interrupted.

  The vibration monitoring units 91 to 94 constitute monitoring means for detecting displacement in the vibration direction of the drive mass units 56 to 59. The vibration monitor units 91 to 94 include movable monitor electrodes 91 </ b> A to 94 </ b> A attached to the outer diameter side of the drive mass units 56 to 59 and fixed monitor electrodes attached to the monitor lands 95 on the glass substrate 52. 91B to 94B.

  Here, the movable monitor electrodes 91A to 94A have three combs extending radially outward from the drive mass portions 56 to 59 in substantially the same manner as the movable drive electrodes 69A to 72A of the vibration generating portions 69 to 72. It is comprised by the tooth-shaped electrode. However, the movable monitor electrodes 91A and 92A are arranged on the opposite side in the Y-axis direction from the movable drive electrodes 69A and 70A with the drive mass portions 56 and 57 interposed therebetween. Similarly, the movable monitor electrodes 93A and 94A are disposed on the opposite side in the X-axis direction from the movable drive electrodes 71A and 72A with the drive mass portions 58 and 59 interposed therebetween.

  The fixed monitor electrodes 91B to 94B are configured by comb-like electrodes extending outward in the radial direction in parallel with the movable monitor electrodes 91A to 94A. The electrode plates of the movable monitor electrodes 91A to 94A and the electrode plates of the fixed monitor electrodes 91B to 94B are engaged with each other with a gap.

  Further, the fixed monitor electrodes 91B to 94B are attached to and electrically connected to four monitor lands 95 fixed to the glass substrate 52, respectively. At this time, the four monitoring lands 95 are provided, for example, at positions sandwiching the support portion 55 connected to the drive beams 65 and 66, and are disposed on both sides in the width direction (circumferential direction) of the support portion 55. The movable monitor electrodes 91 </ b> A to 94 </ b> A, the fixed monitor electrodes 91 </ b> B to 94 </ b> B, and the monitor land 95 are arranged at point-symmetrical positions with respect to the center point O.

  Here, when the drive mass units 56 and 57 are displaced in the Y-axis direction, the capacitances Cm1 and Cm2 between the movable monitor electrodes 91A and 92A and the fixed monitor electrodes 91B and 92B change. Further, when the drive mass units 58 and 59 are displaced in the X-axis direction, the capacitances Cm3 and Cm4 between the movable monitor electrodes 93A and 94A and the fixed monitor electrodes 93B and 94B change. For this reason, the vibration monitoring units 91 to 94 monitor the vibration states of the drive mass units 56 to 59 based on the changes in the capacitances Cm1 to Cm4.

  When the four drive mass units 56 to 59 vibrate with the drive mass units 56 to 59 adjacent in the circumferential direction in reverse phase, the capacitances Cm1 to Cm4 of the vibration monitor units 91 to 94 are synchronized. The structure is changing.

  A total of eight shield lands 96 are provided on the glass substrate 52 at both sides of the four detection lands 86 in the circumferential direction. Here, each shield land 96 is disposed between the drive land 73 and the detection land 86, and is disposed between the monitor land 95 and the detection land 86. Further, the eight shield lands 96 are arranged at point-symmetrical positions with respect to the center point O.

  The shield land 96 is provided in a state of being electrically insulated from the lands 73, 86, and 95, and is connected to, for example, the ground. Accordingly, the shield land 96 electrically shields (blocks) the periphery of the detection land 86, and the drive signal on the drive land 73 side and the monitor land 95 monitor the displacement detection signal of the detection land 86. The signal is prevented from interfering.

  The extraction electrode 97 is formed with a signal via hole (through hole) penetrating in the thickness direction in the glass substrate 53 by using, for example, laser processing, sand blasting, micro blasting, or the like, and conductive in the through hole. The metal film is provided. The extraction electrode 97 is formed at a position corresponding to the support portion 55 and each land 73, 86, 95, 96. Thereby, the vibration generating units 69 to 72, the displacement detecting units 82 to 85, and the vibration monitoring units 91 to 94 are connected to the vibration control circuit 101 and the angular velocity detecting circuit 111, which will be described later, through the extraction electrode 97.

  Next, the vibration control circuit 101 that controls the vibration state of the drive mass units 56 to 59 will be described with reference to FIG. The vibration control circuit 101 controls the drive signal Vd output to the vibration generators 69 to 72 using the monitor signal Vm from the vibration monitor units 91 to 94. The vibration control circuit 101 includes a CV conversion circuit 102, an amplifier 103, an AGC circuit 104, a drive signal generation circuit 105, and the like.

  The CV conversion circuit 102 is connected to the output side of the vibration monitoring units 91 to 94. The CV conversion circuit 102 converts changes in the capacitances Cm1 to Cm4 of the vibration monitoring units 91 to 94 into voltage changes, and outputs these voltage changes as monitor signals Vm. The monitor signal Vm is amplified by the amplifier 103 connected to the output side of the CV conversion circuit 102 and output to the AGC circuit 104.

  The output side of the AGC circuit 104 is connected to a drive signal generation circuit 105 that outputs a drive signal Vd. Then, the AGC circuit 104 adjusts the gain so that the monitor signal Vm becomes constant. The drive signal generation circuit 105 is connected to the vibration generation units 69 to 72 via the amplifier 106. As a result, the drive signal generation circuit 105 inputs the drive signal Vd to the vibration generators 69 to 72, and the vibration generators 69 to 72 have the drive mass units 56 to 59 adjacent to each other in the circumferential direction in opposite phases. In such a state, the drive mass units 56 to 59 are vibrated.

  Next, an angular velocity detection circuit 111 (angular velocity detection means) that detects angular velocities Ω1, Ω2 around two axes (around the X axis and the Y axis) will be described. The angular velocity detection circuit 111 synchronously detects the displacement detection signals Vx and Vy from the displacement detection units 82 to 85 using the monitor signals Vm from the vibration monitoring units 91 to 94, and the angular velocities Ω1, Ω2 acting on the drive mass units 56-59. Is detected. The angular velocity detection circuit 111 includes, for example, CV conversion circuits 112 to 115, differential amplifiers 116 and 120, synchronous detection circuits 117 and 121, and the like.

  The CV conversion circuits 112 to 115 convert changes in the capacitances Cs1, Cs2, Cs3, and Cs4 of the displacement detectors 82 to 85 into voltage changes, and these voltage changes are converted into preliminary displacement detection signals Vs1 and Vs2. , Vs3, and Vs4, respectively.

  Here, when the angular velocity Ω1 around the X axis acts while the adjacent drive mass units 56 to 59 vibrate in mutually opposite phases, the detected mass units 74 and 75 are displaced in the Z axis direction in mutually opposite phases. To do. At this time, the preliminary displacement detection signal Vs1 and the displacement detection signal Vs2 are in opposite phases.

  Therefore, the differential amplifier 116 is connected to the output side of the CV conversion circuits 112 and 113, and calculates a final displacement detection signal Vx from the difference between these preliminary displacement detection signals Vs1 and Vs2.

  The input side of the synchronous detection circuit 117 is connected to the differential amplifier 116 and to the AGC circuit 104 via the phase shift circuit 107. A low-pass filter (LPF) 118 for extracting an angular velocity signal is connected to the output side of the synchronous detection circuit 117, and an adjustment circuit 119 for adjusting gain and offset is connected to the output side of the LPF 118. It is connected. Here, the phase shift circuit 107 outputs a phase shift signal Vm ′ obtained by shifting the phase of the monitor signal Vm output via the AGC circuit 104 by 90 °. Thus, the synchronous detection circuit 117 performs synchronous detection using the phase shift signal Vm ′ from the displacement detection signal Vx, and outputs an angular velocity signal corresponding to the angular velocity Ω1 around the X axis via the LPF 118 and the adjustment circuit 119.

  On the other hand, when the adjacent driving mass units 56 to 59 vibrate in mutually opposite phases and the angular velocity Ω2 around the Y axis acts, the detection mass units 76 and 77 are displaced in the Z axis direction in mutually opposite phases. . At this time, the preliminary displacement detection signal Vs3 and the displacement detection signal Vs4 are in opposite phases.

  Therefore, the differential amplifier 120 is connected to the output side of the CV conversion circuits 114 and 115, and calculates a final displacement detection signal Vy from the difference between these preliminary displacement detection signals Vs3 and Vs4. As a result, the synchronous detection circuit 121 performs synchronous detection from the displacement detection signal Vy using the phase shift signal Vm ′ in the same manner as the synchronous detection circuit 117, and responds to the angular velocity Ω 2 around the Y axis via the LPF 122 and the adjustment circuit 123. Outputs an angular velocity signal.

  The angular velocity sensor 51 according to the fourth embodiment has the above-described configuration, and the operation thereof will be described next.

  First, the case where the angular velocity Ω1 around the X axis is detected will be described. When the drive signal Vd is input from the external vibration control circuit 101 to the drive land 73, the drive signal Vd is applied to the fixed drive electrodes 69B to 72B of the vibration generators 69 to 72. As a result, electrostatic attraction in the Y-axis direction acts on the drive mass units 56 and 57, and the drive mass units 56 and 57 vibrate in the Y-axis direction. On the other hand, electrostatic attraction in the X-axis direction acts on the drive mass units 58 and 59, and the drive mass units 58 and 59 vibrate in the X-axis direction. And the drive mass parts 56-59 adjacent in the circumferential direction vibrate in mutually opposite phases.

  When the angular velocity Ω1 around the X-axis acts when the driving mass units 56 to 59 are oscillating, the driving mass units 56 and 57 that vibrate in the Y-axis direction are shown in the following formula 1 according to the angular velocity Ω1. Coriolis force Fx acts. On the other hand, Coriolis force does not act on the driving mass portions 58 and 59 that vibrate in the X-axis direction. Thereby, the detection mass units 74 and 75 are displaced in the Z-axis direction by the Coriolis force Fx, and vibrate according to the angular velocity Ω1.

  For this reason, the displacement detectors 82 and 83 have capacitances Cs1 and Cs2 between the detection masses 74 and 75 and the fixed detection electrodes 82A and 83A according to the displacement of the detection masses 74 and 75 in the Z-axis direction. Changes. At this time, the CV conversion circuits 112 and 113 of the angular velocity detection circuit 111 convert changes in the capacitances Cs1 and Cs2 into preliminary displacement detection signals Vs1 and Vs2. Then, the differential amplifier 116 outputs a final displacement detection signal Vx corresponding to the angular velocity Ω1 around the X axis based on the difference between the displacement detection signals Vs1 and Vs2. The synchronous detection circuit 117 detects a signal synchronized with the phase shift signal Vm ′ from the displacement detection signal Vx. Thereby, the angular velocity detection circuit 111 outputs an angular velocity signal corresponding to the angular velocity Ω1 around the X axis.

  Next, the case where the angular velocity Ω2 around the Y axis is detected will be described. The drive signal Vd is input from the external vibration control circuit 101 to the drive land 73, and the drive mass units 56 to 59 are vibrated. When the angular velocity Ω2 around the Y axis acts in this vibration state, the Coriolis force Fy shown in the following equation 2 acts on the drive mass portions 58 and 59 that vibrate in the X-axis direction according to the angular velocity Ω2. On the other hand, Coriolis force does not act on the drive mass units 56 and 57 that vibrate in the Y-axis direction. Thereby, the detection mass units 76 and 77 are displaced in the Z-axis direction by the Coriolis force Fy, and vibrate according to the angular velocity Ω2.

  For this reason, the displacement detectors 84 and 85 have capacitances Cs3 and Cs4 between the detection mass units 76 and 77 and the fixed detection electrodes 84A and 85A according to the displacement of the detection mass units 76 and 77 in the Z-axis direction. Changes. At this time, the CV conversion circuits 114 and 115 of the angular velocity detection circuit 111 convert changes in the capacitances Cs3 and Cs4 into displacement detection signals Vs3 and Vs4. Then, the differential amplifier 120 outputs a displacement detection signal Vy corresponding to the angular velocity Ω2 around the Y axis based on the difference between the displacement detection signals Vs3 and Vs4. The synchronous detection circuit 121 detects a signal synchronized with the phase shift signal Vm ′ from the displacement detection signal Vy. Accordingly, the angular velocity detection circuit 111 outputs an angular velocity signal corresponding to the angular velocity Ω2 around the Y axis.

  Thus, in the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment. In particular, in the present embodiment, since the four driving mass portions 56 to 59 are arranged at positions that are point-symmetric with respect to the center point O, the two driving mass portions 56 and 57 are arranged with the center point O in between. The two drive mass parts 58 and 59 can be arranged on both sides in the Y-axis direction with the center point O interposed therebetween. Further, the drive mass units 56 to 59 adjacent in the circumferential direction vibrate in mutually opposite phases.

  Thereby, when the angular velocity Ω1 around the X axis acts, the Coriolis force Fx in the Z-axis direction can be generated in the drive mass units 56 and 57 that vibrate in the Y-axis direction. For this reason, when the angular velocity Ω1 acts, the detection mass units 74 and 75 are displaced in the Z-axis direction and vibrate. Therefore, by detecting this vibration using the displacement detectors 82 and 83, the angular velocity Ω1 around the X axis can be detected.

  On the other hand, when the angular velocity Ω2 around the Y axis acts, the driving mass portions 58 and 59 that vibrate in the X axis direction can generate a Coriolis force Fy in the Z axis direction. Therefore, when the angular velocity Ω2 is applied, the detection mass units 76 and 77 are displaced in the Z-axis direction and vibrate. Therefore, the angular velocity Ω2 around the Y axis can be detected by detecting this vibration using the displacement detectors 84 and 85. Thus, the angular velocities Ω1 and Ω2 acting around the glass substrate 52 and the two horizontal axes (X axis and Y axis) can be detected using the single angular velocity sensor 51.

  Further, since the angular velocity sensor 51 detects angular velocities Ω1, Ω2 around two axes, the degree of freedom of the detection mass units 74 to 77 in the horizontal direction (X-axis and Y-axis directions) and the vertical direction (Z-axis direction) is increased. It is large and the entire movable part including the detection mass units 74 to 77 is easily displaced in the thickness direction. For this reason, when the second glass substrate 53 is anodically bonded to the silicon substrate 54, the detection mass portions 74 to 77 and the like tend to adhere to the glass substrate 53 and be bonded easily. On the other hand, in the present embodiment, the glass substrate 53 is provided with the base electrode 89 in addition to the equipotential electrode 87, so that the glass substrate 53 and the detected mass are detected by the equipotential electrode 87, the shield portion 90 of the base electrode 89, and the like. The electric field between the parts 74 to 77 can be reliably cut off, and the joining of the detection mass parts 74 to 77 can be prevented to improve the production yield.

  In the fourth embodiment, similarly to the first embodiment, the shield part 90 is formed by using the second electrode part 89B connected to the same potential electrode 87 in the base electrode 89. However, the present invention is not limited to this, and the shield portion may be formed by using the first electrode portion 89A as in the second embodiment, and the base electrode as in the third embodiment. The whole 89 may be connected to the same potential electrode 87.

  In the fourth embodiment, the case where the present invention is applied to the angular velocity sensor 51 that detects angular velocities Ω1 and Ω2 around two axes has been described. However, the present invention is applied to an angular velocity sensor that detects angular velocities around one axis. May be.

  Next, FIG. 21 shows a fifth embodiment according to the present invention. The feature of this embodiment is that the peripheral portion of the fixed electrode overlaps the same potential electrode with an insulating film interposed therebetween. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The acceleration sensor 131 according to the fifth embodiment is sandwiched between the first and second glass substrates 2 and 3 and these glass substrates 2 and 3 in substantially the same manner as the acceleration sensor 1 according to the first embodiment. The silicon substrate 4 is formed. The silicon substrate 4 is provided with a support portion 5, a movable portion 6, a support beam 7, and the like, and the second glass substrate 3 is provided with a fixed electrode 132 and an equipotential electrode 134 described later. .

  The fixed electrode 132 is configured in substantially the same manner as the fixed electrode 9 according to the first embodiment, is formed in a substantially rectangular shape using a conductive metal thin film, and constitutes a fixed detection electrode. The fixed electrode 132 is disposed in the cavity 3 </ b> A of the second glass substrate 3 at a position facing the movable portion 6. The fixed electrode 132 includes a wiring portion 132A extending toward the other side in the X-axis direction, and is electrically connected to the electrode support portion 8 using the wiring portion 132A.

  Here, the back side of the fixed electrode 132 facing the movable part 6 faces the movable part 6 over almost the entire surface. On the other hand, the surface side of the fixed electrode 132 that faces the second glass substrate 3 faces the bottom surface of the cavity 3A with an insulating film 133 described later interposed therebetween. The peripheral edge of the fixed electrode 132 overlaps the same potential electrode 134 described later with the insulating film 133 interposed therebetween.

  The insulating film 133 is formed of a thin film using an insulating material, like the interlayer insulating film 11 according to the first embodiment, and is provided in the cavity 3 </ b> A of the second glass substrate 3. The insulating film 133 covers the same potential electrode 134 to be described later over the entire surface, and a fixed electrode 132 is provided on the back side thereof.

  The equipotential electrode 134 is provided on the back side of the second glass substrate 3 and is disposed in the cavity 3 </ b> A of the second glass substrate 3. The equipotential electrode 134 includes a wiring part 134A extending toward one side in the X-axis direction, and is electrically connected to the connecting and fixing part 5B using the wiring part 134A. The equipotential electrode 134 is disposed between the bottom surface of the cavity 3A and the insulating film 133 in the thickness direction.

  The equipotential electrode 134 is formed in, for example, a C-shaped or quadrangular frame shape surrounding the fixed electrode 132, and constitutes an overlapping portion 134 </ b> B part of which overlaps with the peripheral portion of the fixed electrode 132. . At this time, since the insulating film 133 is interposed between the equipotential electrode 134 and the fixed electrode 132, the equipotential electrode 134 and the fixed electrode 132 are insulated from each other by the insulating film 133. The equipotential electrode 134 covers the bottom surface of the cavity 3A together with the fixed electrode 132 without a gap. As a result, the equipotential electrode 134 blocks the electric field between the second glass substrate 3 and the movable portion 6.

  Thus, in the present embodiment configured as described above, it is possible to obtain substantially the same operational effects as those of the first embodiment. In particular, in this embodiment, since the fixed electrode 132 and the same potential electrode 134 are overlapped with the insulating film 133 interposed therebetween, the fixed electrode 132 is not provided without providing a base electrode as in the first embodiment. The same potential electrode 134 can cover the entire surface of the glass substrate 3 facing the movable portion 6 without any gap.

  In the fifth embodiment, the equipotential electrode 134 overlaps only the peripheral portion of the fixed electrode 132. However, for example, by providing the equipotential electrode 134 on the entire bottom surface of the cavity 3A, It is good also as a structure which overlaps with respect to the whole. In this case, the same effect as that of the third embodiment can be obtained.

  In the fifth embodiment, the insulating film 133 is configured to cover the same potential electrode 134 over the entire surface. However, like the acceleration sensor 131 ′ according to the modification shown in FIG. An insulating film 133 ′ may be provided only in a portion where the same potential electrode 134 ′ overlaps. In this case, the overlapping part 134B ′ of the same potential electrode 134 ′ may be arranged on the movable part 6 side with respect to the thickness direction with respect to the fixed electrode 132 ′.

  In the fifth embodiment, the case where the device is applied to the acceleration sensor 131 as an electrostatic device has been described as an example. However, for example, the device may be applied to the angular velocity sensor 51 according to the fourth embodiment.

  In each of the above embodiments, the second glass substrate 3, 53 is provided with the fixed electrodes 9, 132, the fixed detection electrodes 82A to 85A, the same potential electrodes 10, 87, 134, etc. The fixed electrodes may be provided on both of the second glass substrates. In each of the above embodiments, the first glass substrates 2 and 52 and the second glass electrodes 3 and 53 are provided on both sides in the thickness direction of the silicon substrates 4 and 54. However, a fixed electrode is provided. The first glass substrates 2 and 52 that are not required do not need to be formed using a glass material, and a substrate made of another material such as silicon may be used.

  In each of the above embodiments, the acceleration sensors 1, 31, 41, 131 and the angular velocity sensor 51 are described as examples of the electrostatic device. However, the present invention is not limited to this, and can be applied to various elements such as an actuator and a switch as long as the structure includes a movable part that can be displaced in the thickness direction and a fixed electrode that faces the movable part. .

1,31,41,131,131 'Acceleration sensor (electrostatic device)
2 1st glass substrate 3 2nd glass substrate 5 Support part 6 Movable part 7 Support beam 9, 132, 132 'Fixed electrode 10, 87, 134, 134' Equipotential electrode 11, 42, 88 Interlayer insulation film 12, 32, 43, 89 Base electrode 12A, 32A, 89A First electrode part 12B, 32B, 89B Second electrode part 13, 33, 44, 90 Shield part 51 Angular velocity sensor (electrostatic device)
74-77 Detection mass part (movable part)
82A to 85A Fixed detection electrode (fixed electrode)
133, 133 'insulating film

Claims (4)

A glass substrate, a silicon substrate having a movable part provided on the glass substrate and displaceable in a thickness direction, a fixed electrode provided on the glass substrate and disposed at a position facing the movable part, and the fixed electrode, In an electrostatic device that is insulated and provided with the same potential electrode that is provided on the glass substrate and has the same potential as the movable part,
A horizontal gap is formed between the fixed electrode and the same potential electrode,
In the fixed electrode and the same potential electrode, a position opposite to the movable portion with respect to the thickness direction is provided with a base electrode facing the fixed electrode and the same potential electrode with an interlayer insulating film interposed therebetween,
The base electrode includes a shield portion that covers a gap between the fixed electrode and the same potential electrode and is electrically connected to either the fixed electrode or the same potential electrode. Electrostatic type device. The base electrode includes a first electrode part electrically connected to the fixed electrode and a second electrode part connected to the same potential electrode,
The electrostatic device according to claim 1, wherein the shield part is formed using the first electrode part.   2. The electrostatic device according to claim 1, wherein the base electrode is configured to be connected to the same potential electrode as a whole including the shield portion. A glass substrate, a silicon substrate having a movable part provided on the glass substrate and displaceable in a thickness direction, a fixed electrode provided on the glass substrate and disposed at a position facing the movable part, and the fixed electrode, In an electrostatic device that is insulated and provided with the same potential electrode that is provided on the glass substrate and has the same potential as the movable part,
The electrostatic device, wherein the fixed electrode has a configuration in which at least a peripheral portion thereof overlaps with the same potential electrode in a thickness direction with an insulating film interposed therebetween.

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