JP2013228243A - Capacitance sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a capacitance sensor capable of suppressing the deterioration of device characteristics.SOLUTION: A capacitance sensor 1 is equipped with a semiconductor substrate 4, and a first fixing plate 2 is joined to one surface 4a of the semiconductor substrate 4. At moving electrodes 5a, 6a, which are the electrodes of at least either one side of the moving electrodes 5a, 6a and fixed electrodes 21a, 21b, 22a, 22b, stoppers 51, 61 are provided. The stoppers 51, 61 are equipped with flexible abutting portions 51b, 61b having abutting surfaces 51c, 61c abutting on the electrodes 21a, 21b, 22a, 22b on the other side when moving bodies 5, 6 are relatively displaced. On the opposite sides of the abutting surfaces 51c, 61c of the abutting portions 51b, 61b, spaces S1 for accepting the warping of the abutting portions 51b, 61b are formed.

Description

  The present invention relates to a capacitive sensor.

  2. Description of the Related Art Conventionally, as a capacitive sensor, an upper fixed plate in which fixed electrodes are formed on a surface of a semiconductor substrate including a movable body having a movable electrode and a frame portion so as to be opposed to the movable electrode of the movable body Is known (see, for example, Patent Document 1).

  In this patent document 1, when a movable body is displaced by the action of an excessive external force or the like by providing a protruding stopper at a portion of the fixed electrode facing the movable electrode, the movable electrode is placed on the fixed electrode or the upper fixed plate. This prevents the movable body from sticking to the upper fixed plate due to direct collision.

JP 2011-047664 A

  However, in the above conventional technique, when the movable body is displaced by the action of an excessive external force and the movable electrode comes into contact with the protruding stopper, the movable electrode and the stopper are rubbed against each other to destroy the stopper or the like. There was a fear. As described above, when the stopper or the like is broken, a foreign matter is generated, and the displacement of the movable body is hindered by the foreign matter, so that the function as a sensor may be impaired. That is, in the above conventional technique, there is a possibility that the device characteristics are deteriorated.

  Then, an object of this invention is to obtain the electrostatic capacitance type sensor which can suppress that a device characteristic falls.

  A first feature of the present invention is that a fixed electrode is formed on one surface of a semiconductor substrate on which a movable body having a movable electrode is formed so as to be capable of relative displacement, and is opposed to the movable electrode with a gap therebetween. A capacitance type sensor in which a first fixed plate is joined, and at least one of the movable electrode and the fixed electrode is provided with a stopper, and the movable body is relatively displaced by the stopper. A flexible abutting portion having an abutting surface that abuts against the other electrode side, and the abutting portion is allowed to bend on the opposite side of the abutting surface. The gist is that a space is formed.

  The gist of the second feature of the present invention is that the stopper is formed in a substantially L shape or a T shape.

  The gist of the third feature of the present invention is that the stopper is made of an insulating material.

  According to the present invention, the stopper includes a flexible contact portion having a contact surface that contacts the other electrode side when the movable body is relatively displaced. On the opposite side, a space that allows the contact portion to bend is formed. Therefore, when the movable body is relatively displaced by the action of an excessive external force and the contact portion of the stopper contacts the other electrode side, the contact portion of the stopper may be bent in the relative displacement direction of the movable body. it can. Therefore, it is possible to suppress the occurrence of rubbing between the contact portion of the stopper and the other electrode side. As a result, the generation of foreign matter due to the destruction of the stopper or the like is suppressed, and inhibition of displacement of the movable body due to the foreign matter can be suppressed.

  As described above, according to the present invention, it is possible to obtain a capacitance type sensor that can suppress deterioration of device characteristics.

It is a disassembled perspective view which shows the electrostatic capacitance type sensor concerning 1st Embodiment of this invention. 1 is a plan view showing a semiconductor substrate according to a first embodiment of the present invention. It is a back view which shows the semiconductor substrate concerning 1st Embodiment of this invention. It is AA sectional drawing of FIG. It is operation | movement explanatory drawing of an electrostatic capacitance type sensor. It is a system block diagram of an electrostatic capacitance type sensor. It is explanatory drawing which shows typically the detection principle of the acceleration applied to the X direction. It is explanatory drawing which shows typically the detection principle of the acceleration applied to the Z direction. It is explanatory drawing which shows the output calculating type | formula of an electrostatic capacitance type sensor in a table format. It is a figure which shows the stopper part of the capacitance-type sensor concerning 1st Embodiment of this invention, Comprising: (a) is sectional drawing which expands and shows the state before a stopper contact | abuts the other electrode side, b) is an enlarged sectional view showing a state in which the stopper is in contact with the other electrode side. It is sectional drawing which expands and shows the stopper part of the electrostatic capacitance type sensor concerning the modification of 1st Embodiment of this invention. It is a figure which shows the stopper part of the capacitance-type sensor concerning 2nd Embodiment of this invention, Comprising: (a) is sectional drawing which expands and shows the state before a stopper contact | abuts the other electrode side, b) is an enlarged sectional view showing a state in which the stopper is in contact with the other electrode side. It is sectional drawing which expands and shows the state which the stopper of the capacitance-type sensor concerning 3rd Embodiment of this invention contact | abutted to the other electrode side. It is sectional drawing which expands and shows the state before the stopper of the electrostatic capacitance type sensor concerning 4th Embodiment of this invention contact | abuts the other electrode side.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Below, an acceleration sensor is illustrated as an electrostatic capacitance type sensor. Further, the side of the weight portion on which the movable electrode is formed is defined as the surface side of the semiconductor substrate. Then, the short direction of the semiconductor substrate will be described as the X direction, the longitudinal direction of the semiconductor substrate as the Y direction, and the thickness direction of the semiconductor substrate as the Z direction.

  Moreover, the same component is contained in the following several embodiment. Therefore, in the following, common reference numerals are given to those similar components, and redundant description is omitted.

(First embodiment)
As shown in FIG. 1, an acceleration sensor (capacitance sensor) 1 according to this embodiment includes a silicon substrate (semiconductor substrate) 4 on which a semiconductor element device is formed. The first insulating substrate (first fixing plate) 2 and the second insulating substrate (first fixing plate) 2 made of glass bonded to the front surface (one surface) 4a and the back surface (other surface) 4b of the silicon substrate 4, respectively. 2 fixing plates) 3. In this embodiment, the silicon substrate 4 is bonded to the first insulating substrate 2 and the second insulating substrate 3 by anodic bonding.

  Then, on the lower surface (inner surface) 2a of the first insulating substrate 2, rectangular fixed electrodes 21a, 21b and 22a, 22b corresponding to the installation areas of the rectangular weight portions (movable bodies) 5, 6 are respectively provided. Is provided.

  In addition, on the upper surface (inner surface) 3 a of the second insulating substrate 3, rectangular adhesion preventing films 31 and 32 are formed in regions corresponding to the installation regions of the weight portions 5 and 6, respectively. The adhesion preventing films 31 and 32 can be formed of the same material as the fixed electrodes 21a and 21b and 22a and 22b, for example.

  The silicon substrate 4 has a gap 43 with respect to the frame portion 40 in which two frame portions 40a and 40b are arranged in parallel in the Y direction (longitudinal direction of the silicon substrate 4) and the inner peripheral surface of the frame portions 40a and 40b. The weight portions 5 and 6 disposed in the frame portions 40a and 40b in a state and a pair of beam portions 7a and 7b and 8a and 8b that rotatably support the weight portions 5 and 6 with respect to the frame portion 40, respectively. And movable electrodes 5a and 6a formed on the surfaces (one surface) of the weight portions 5 and 6.

In this embodiment, a rectangular SOI substrate in which a buried insulating layer 112 made of SiO ₂ is interposed between a silicon active layer 111 made of Si and a support substrate 113 made of Si is used as the silicon substrate 4. . The longitudinal side of the silicon substrate 4 is about 2 to 4 mm, the thickness is about 0.4 to 0.6 mm, the thickness of the silicon active layer 111 is about 10 to 20 μm, and the thickness of the buried insulating layer 112 The thickness is about 0.5 μm.

  In this embodiment, the frame portion 40 extends in a substantially rectangular outer frame portion 41 as viewed from the Z direction (thickness direction of the silicon substrate 4) and the X direction (short direction of the silicon substrate 4). And a central frame portion 42 that connects substantially the central portion of the outer frame portion 41 in the Y direction (longitudinal direction of the silicon substrate 4).

  As shown in FIGS. 3 and 4, the weight portions 5, 6 are integrally formed with recesses 55, 65 opening on one surface (back surface) and solid portions 53, 63 excluding the recesses 55, 65. That is, by forming concave portions 55 and 65 opened on one surface (rear surface) on the weight portions 5 and 6, the thick portions 53 and 63 and the thin thin portions 54 and 64 are formed on the weight portions 5 and 6. Forming.

  As shown in FIG. 4, the solid portions 53 and 63 are formed in a rectangular shape as viewed from the back side, and in the solid portions 53 and 63, diagonal groove portions 56 and 66 are formed on the movable electrode 5 a. , 6a.

  Further, the recesses 55 and 65 are formed in a rectangle having side walls on four sides, and reinforcing walls 57 and 67 are provided in the interior perpendicular to the movable electrodes 5a and 6a.

  In the present embodiment, the recess 55 is formed on one side in the X direction (the back side in FIG. 1) with respect to the rotation axis A1 described later, and the recess 65 is on the other side in the X direction with respect to the rotation axis A2 described later. It is formed on the front side of FIG.

  In this embodiment, the functions of the movable electrodes 5a and 6a are provided on the surfaces of the weight portions 5 and 6, but the surfaces of the weight portions 5 and 6 are movable on the surfaces facing the fixed electrodes 21a and 21b and 22a and 22b. An electrode may be formed separately.

  The beam portions 7a, 7b and 8a, 8b are formed in the silicon active layer 111 of the SOI substrate (silicon substrate 4), deep etching is performed using the embedded insulating layer 112 of the SOI substrate as an etching stop, and further the embedded insulating layer It is formed by selectively removing 112.

  The beam portions 7a and 7b are respectively positioned on two opposite sides of the surface of the weight portion 5 (movable electrode 5a). When the beam portions 7a and 7b are twisted, the movable electrode 5a causes the beam portions 7a and 7b to be mutually connected. The connecting straight line swings as a rotation axis (axis) A1. Similarly, the beam portions 8a and 8b are respectively located on two opposite sides of the surface of the weight portion 6 (movable electrode 6a), and the movable electrode 6a has a rotation axis (axis) connecting the beam portions 8a and 8b to each other. ) Swings as A2.

  The beam portions 7a and 7b and the beam portions 8a and 8b are located at the midpoints of the two sides of the surfaces of the weight portions 5 and 6, respectively.

  Further, in the present embodiment, the weight portion 5 and the weight portion 6, the beam portion 7a and the beam portion 8a, and the beam portion 7b and the beam portion 8b are respectively connected to one point of the silicon substrate 4 (a line connecting the beam portion 7b and the beam portion 8b). It is arranged so as to be point symmetric with respect to the midpoint of the minute).

  By the way, in this embodiment, as shown in FIG. 4, the recessed part 55 is formed in the one side of rotating shaft (axis | shaft) A1 in the back side of the weight part 5, and it is made for the gravity center of the weight part 5 to shift to the other side. ing. Similarly, a recess 65 is formed on the other side (the other side of the rotation axis (axis) A2) opposite to the one side where the recess 55 is provided on one weight 5 on the back side of the weight 6, The center of gravity of the weight portion 6 is shifted to one side. When acceleration is applied in the X direction or the Z direction, the operation is performed as shown in FIG. 5 so that the acceleration a applied in the X direction and the Z direction can be detected (see FIGS. 7 and 8). .

  At this time, for example, referring to FIG. 4 as an example of one of the weight parts 5, both the weight parts 5 and 6 are perpendicular to the surface (movable electrode 5a) from the center of gravity G on the side where the recess 55 is not formed. The angle θ formed by the straight line connecting the center of gravity G and the rotation axis (axis) A1 is set to be approximately 45 degrees. The same applies to the other weight portion 6, but in this case, as described above, the position of the center of gravity exists on the opposite side of the center of gravity G of the weight portion 5 across the rotation axis (axis) A 2. Become. If the center of gravity G is arranged in this way, the detection sensitivities in the X direction and the Z direction are equivalent, so that the detection sensitivities in the respective directions can be made substantially the same.

  In addition, relatively shallow gaps G1 and G2 are formed on the bonding surface between the silicon substrate 4 and the first insulating substrate 2 and the second insulating substrate 3, respectively. The operability of the parts (movable electrodes 5a, 6a) 5, 6 is ensured. That is, the first insulating substrate (first fixing plate) 2 is bonded to the surface (one surface) 4 a of the silicon substrate 4, and the second insulating substrate (second surface) 4 b is bonded to the back surface (other surface) 4 b of the silicon substrate 4. The fixing plate 3) is joined to form the space S. By forming this space portion S, the operability of the weight portions (movable electrodes 5a, 6a) 5, 6 is secured.

  The gap G2 on the back side of the silicon substrate 4 is formed by anisotropic etching using an alkaline wet anisotropic etching solution (for example, KOH (potassium hydroxide aqueous solution), TMAH (tetramethyl ammonium hydroxide aqueous solution), etc.). Thus, the silicon substrate 4 can be formed by removing a part thereof. At this time, it is preferable to form the concave portions 55 and 65 described above at the same time.

  In addition, the gap 43 and the gap 44 are formed by performing a vertical etching process by reactive ion etching (RIE) or the like. As reactive ion etching, for example, ICP processing by an etching apparatus provided with inductively coupled plasma (ICP) can be used.

  Further, the weight parts 5 and 6 (movable electrodes 5a and 6a) are provided at the four corners of the surface of the weight parts 5 and 6 (movable electrodes 5a and 6a) and the beam parts 7a and 7b and the beam parts 8a and 8b. Protrusions (stoppers) 51 and 61 for preventing direct collision with the fixed electrodes 21a, 21b, 22a, and 22b of one insulating substrate 2 are provided. That is, eight projecting portions (stoppers) 51 and 61 are projected from the movable electrodes 5a and 6a, respectively.

  Similarly, the weight portions 5 and 6 are attached to the second corners of the back surface of the weight portions 5 and 6, near the beam portions 7 a and 7 b and the beam portions 8 a and 8 b. Protrusions (stoppers) 52 and 62 are provided so as to prevent direct collision with the projections.

  Further, in the present embodiment, the outer frame portion 41 is formed with a wide X-direction one end (the lower side in FIG. 2), and the weight portions 5, 6 are disposed on the X-direction one end of the outer frame portion 41. Clearances 44, 44 are formed so as to be continuous with the clearances 43, 43 where the In addition, two electrode bases 9 are arranged with two gaps 44 therebetween.

  Detection electrodes 10a, 10b, 11a, and 11b made of metal films are provided on the surface of the electrode table 9, respectively.

  The electrode table 9 is disposed separately from the frame portion 40 and the weight portions 5 and 6, and the upper and lower surfaces are fixed by the first insulating substrate 2 and the second insulating substrate 3. Further, a common electrode 12 wired outside the acceleration sensor 1 is provided at the center in the Y direction on the surface of the outer frame portion 41, and the frame portion 40 takes a common potential by the common electrode 12.

  As described above, the fixed electrodes 21a, 21b and 22a, 22b corresponding to the installation areas of the weight portions 5, 6 are provided on the lower surface of the first insulating substrate 2, respectively. These fixed electrodes 21a, 21b and 22a, 22b are formed to have substantially the same shape and the same area.

  The fixed electrodes 21a and 21b are spaced apart from each other with a straight line (rotation axis A1) connecting the beam portions 7a and 7b as a boundary line. Similarly, the fixed electrodes 22a and 22b are spaced apart from each other with a straight line (rotation axis A2) connecting the beam portions 8a and 8b as a boundary line. In this embodiment, each fixed electrode 21a, 21b and 22a, 22b is formed by vapor-depositing aluminum (Al) on the first insulating substrate 2 by a sputtering method, a CVD method or the like.

  The fixed electrodes 21a and 21b are electrically connected to the detection electrodes 10a and 10b, respectively, and the fixed electrodes 22a and 22b are electrically connected to the detection electrodes 11a and 11b, respectively.

  Specifically, the fixed electrodes 21a, 21b and 22a, 22b are led out toward the fixed electrode base 9 on which the detection electrodes 10a, 10b and 11a, 11b to which the fixed electrodes 21a, 21b, 22b are respectively connected are formed. Part) 25 is provided.

  Each fixed electrode base 9 is formed with an aluminum conductive layer (semiconductor substrate side metal contact portion) 13 with which a lead wire (fixed electrode side metal contact portion) 25 contacts. In this embodiment liquid, a step 9a is provided on the other end side in the X direction of each fixed electrode base 9 (upper side in FIG. 2: weight side), and the lower surface of the step 9a, that is, the detection electrodes 10a, 10b and 11a. , 11b is formed at a position lower than the surface on which the semiconductor layer 11b is formed (refer to FIG. 3).

  The lead wire (fixed electrode side metal contact portion) 25 and the conductive layer (semiconductor substrate side metal contact portion) 13 are crushed together when the silicon substrate 4 and the first insulating substrate 2 are anodic bonded. Being touched.

  Thus, the fixed electrodes 21a, 21b and 22a, 22b are electrically connected to the detection electrodes 10a, 10b and 11a, 11b.

  The detection electrodes 10a, 10b and 11a, 11b are separated from each other and are separated from the frame portion 40 and the weight portions 5, 6, respectively. Therefore, the detection electrodes are insulated from each other, and the parasitic capacitance of each detection electrode, Crosstalk between the detection electrodes can be reduced, and highly accurate capacitance detection can be performed.

  In addition, through holes 23 are respectively formed by sandblasting or the like in portions corresponding to the electrode base 9 of the first insulating substrate 2, and in portions corresponding to the common electrode 12 of the first insulating substrate 2. The through holes 24 are respectively formed by sandblasting or the like. The detection electrodes 10a, 10b, 11a, and 11b are exposed and wired to the outside through the through holes 23, respectively, and the common electrode 12 is exposed and wired to the outside through the through holes 24, respectively. Thus, the potentials of the fixed electrodes 21a, 21b, 22a, 22b and the movable electrodes 5a, 6a can be extracted to the outside.

  In the acceleration sensor 1 configured as described above, when the acceleration indicated by the arrow a in FIG. 5 is applied, both the weight portions 5 and 6 swing, and both ends of the weight portions 5 and 6 and the fixed electrode are moved. The gap d between 21a, 21b and 22a, 22b changes, and the capacitances C1, C2, C3, C4 between these gaps d change. In addition, in FIG. 5, one weight part 5 is illustrated.

  The capacitance C at this time is known to be C = ε × S / d (ε: dielectric constant, S: electrode area, d: gap), and the electrostatic capacity increases as the gap d increases from this equation. The capacitance C decreases, and the capacitance C increases as the gap d decreases.

  Then, as shown in the system configuration of FIG. 6, the acceleration sensor 1 sends the detected electrostatic capacitances C1, C2, C3, and C4 to an arithmetic circuit 100 configured by, for example, an ASIC, and accelerates in the X direction. Further, acceleration in the Z direction is obtained, and data indicating the acceleration is output. At this time, an arithmetic expression executed by the arithmetic circuit 100 is shown in FIG. 9, and C1 obtained by applying the acceleration a in the X direction shown in FIG. 7 and applying the acceleration a in the Z direction shown in FIG. , C2, C3, and C4 determine the direction of acceleration a. Note that a parameter C0 in the following expression indicates the capacitance between the weights 5 and 6 and the fixed electrodes 21a and 21b and 22a and 22b in a state where the acceleration a is not applied.

  When acceleration a is applied in the + X direction (see FIG. 7), both the weight portions 5 and 6 swing in the same direction, so C1 = C0 + ΔC, C2 = C0−ΔC, C3 = C0 + ΔC, C4 = C0−ΔC. When the acceleration a is applied in the −X direction, the swinging directions of the weight portions 5 and 6 are opposite to the + direction, so that C1 = C0−ΔC, C2 = C0 + ΔC, and C3 = C0−. ΔC, C4 = C0 + ΔC.

  On the other hand, when acceleration a is applied in the + Z direction (see FIG. 8), both weight portions 5 and 6 swing in opposite directions, so that C1 = C0−ΔC, C2 = C0 + ΔC, C3 = C0 + ΔC, C4 = C0−ΔC. When the acceleration a is applied in the −Z direction, the swinging directions of the weights 5 and 6 are opposite to the + direction, so C1 = C0 + ΔC, C2 = C0−ΔC, and C3 = C0−. ΔC, C4 = C0 + ΔC.

  Therefore, the capacitance difference CA (= C1-C2) between the one weight portion 5 and the fixed electrodes 21a and 21b is + 2ΔC in the + X direction, −2ΔC in the −X direction, −2ΔC in the + Z direction, − + 2ΔC in the Z direction. Further, the difference in capacitance CB (= C3−C4) between the other weight portion 6 and the fixed electrodes 22a and 22b is + 2ΔC in the + X direction, −2ΔC in the −X direction, + 2ΔC and −Z in the + Z direction. -2ΔC in the direction.

  Here, the output in the X direction can be obtained as the sum of both differences CA and CB, and the output in the Z direction can be obtained as the difference between both differences CA and CB. As a result, the output in the X direction becomes + 4ΔC when the acceleration a in the + X direction is applied, and becomes −4ΔC when the acceleration a in the −X direction is applied. The output in the Z direction is −4ΔC when the acceleration a in the + Z direction is applied, and is + 4ΔC when the acceleration a in the −Z direction is applied.

  By the way, as shown in FIG. 1, the acceleration sensor 1 of the present embodiment includes a first acceleration sensor unit having one weight part 5 and a second acceleration sensor unit having the other weight part 6. Arranged in the same chip plane, each acceleration sensor unit is arranged in a state of being relatively rotated by 180 degrees. Thus, the gravity center positions of one weight part 5 in the first acceleration sensor alone and the other weight part 6 in the second acceleration sensor alone are opposite to each other with respect to the rotation axes (axis) A1 and A2. The acceleration a in the X direction and the Z direction can be detected.

  As described above, the movable electrodes 5a and 6a, which are at least one of the movable electrodes 5a and 6a and the fixed electrodes 21a and 21b and 22a and 22b, are provided with protrusions (stoppers) 51 and 61. Yes.

  Here, the protrusions (stoppers) 51 and 61 provided on the movable electrodes 5a and 6a are provided with springiness. In the present embodiment, the protrusions (stoppers) 51 and 61 provided at the four corners of the rectangular movable electrodes 5a and 6a are provided with a spring property. The protrusions (stoppers) 51 and 61 provided in the vicinity of the beam portions 7a and 7b and the beam portions 8a and 8b may be provided with springiness.

  Specifically, the protrusions (stoppers) 51 and 61 provided at the four corners are connected to the support portions 51a and 61a extending substantially vertically from the surfaces of the movable electrodes 5a and 6a, and the support portions 51a and 61a. The contact portions 51b and 61b are provided and are substantially L-shaped and substantially parallel to the surfaces of the movable electrodes 5a and 6a and extending toward the outer peripheral side of the movable electrodes 5a and 6a. At this time, the contact portions 51b and 61b are formed so as not to exceed the regions of the movable electrodes 5a and 6a in plan view.

  The contact portions 51b and 61b are fixed electrodes 21a, which are the other electrodes, when an excessive physical quantity (acceleration) is applied and the weight portions (movable bodies) 5 and 6 are relatively displaced (oscillating or the like). , 21b and 22a, 22b side abutting surfaces 51c, 61c. The fixed electrodes 21a, 21b and 22a, 22b are opposed to the contact surfaces 51c, 61c of the first insulating substrate (first fixed plate) 2 and the fixed electrodes 21a, 21b, 22a, 22b. It refers to the part that performs. That is, in this embodiment, as shown in FIG. 10, since the fixed electrodes 21a, 21b and 22a, 22b are opposed to the contact surfaces 51c, 61c, the fixed electrodes 21a, 21b and 22a, 22b side is This refers to a portion facing the contact surfaces 51c and 61c of the fixed electrodes 21a and 21b and 22a and 22b.

  Further, in the present embodiment, the contact portions 51b and 61b are flexible, and are opposite to the contact surfaces 51c and 61c of the contact portions 51b and 61b (in FIG. 10, the contact portions 51b and 61b). A space S1 that allows the abutment portions 51b and 61b to bend is formed in the lower part of FIG.

  This space S1 is the surface of the movable electrodes 5a and 6a, which is one of the electrodes, and the surface opposite to the contact surfaces 51c and 61c of the contact portions 51b and 61b, and faces the surfaces of the movable electrodes 5a and 6a. Formed between the opposing surfaces 51d and 61d.

  Therefore, when an excessive physical quantity (acceleration) is applied and the weights (movable bodies) 5 and 6 are relatively displaced (swinging etc.), as shown in FIG. The contact surfaces 51c and 61c of 61b contact the fixed electrodes 21a and 21b and 22a and 22b, and the contact portions 51b and 61b bend in the direction of narrowing the space S1 (movable electrode side as one electrode: lower side). It will be.

  The protrusions (stoppers) 51 and 61 are made of an insulating material and prevent the movable electrodes 5a and 6a and the fixed electrodes 21a, 21b, 22a, and 22b from being short-circuited. The protrusions (stoppers) 51 and 61 may be formed integrally with the movable electrodes 5a and 6a (weight portions 5 and 6) or may be formed separately.

  In the present embodiment, the protrusions (stoppers) 51 and 61 are formed to be substantially L-shaped with polyimide, SU-8 (trade name), or the like.

  As described above, in the present embodiment, the movable electrodes 5a and 6a, which are at least one of the movable electrodes 5a and 6a and the fixed electrodes 21a and 21b and 22a and 22b, are provided with the protrusions (stoppers) 51, 61 is formed. The protrusions (stoppers) 51 and 61 have contact surfaces that contact the fixed electrodes 21a and 21b and the 22a and 22b sides (the other electrode side) when the weight portions (movable bodies) 5 and 6 are relatively displaced. Flexible contact portions 51b and 61b having 51c and 61c are provided. Furthermore, a space S1 that allows the contact portions 51b and 61b to be bent is formed on the opposite side of the contact surfaces 51c and 61c of the contact portions 51b and 61b.

  Therefore, when an excessive external force is applied by applying an excessive acceleration (physical quantity) or the like, the weight parts (movable bodies) 5 and 6 are relatively displaced (swinging or parallelly moving upward), and the protruding part (stopper) ) The contact portions 51b and 61b of 51 and 61 are in contact with the other electrode side. When the contact portions 51b and 61b of the protrusions (stoppers) 51 and 61 contact the other electrode side, the contact portions 51b and 61b of the protrusions (stoppers) 51 and 61 narrow the space S1 (one side) It will bend to the movable electrode side (lower side). That is, the contact portions 51b and 61b can be bent in the relative displacement direction (upward) of the movable body. Therefore, when the contact portions 51b and 61b are in contact with the fixed electrodes 21a and 21b and 22a and 22b, it is possible to suppress the lateral component force from acting on the contact portions. Therefore, the contact portions 51b and 61b of the protrusions (stoppers) 51 and 61 are laterally displaced with respect to the fixed electrodes 21a and 21b and the 22a and 22b sides (between the contact portions 51b and 61b and the other electrode side). Can be suppressed). As a result, the generation of foreign matters due to the destruction of the protrusions (stoppers) 51 and 61 and the weight portions (movable bodies) 5 and 6 is suppressed, and the inhibition of the relative displacement of the weight portions (movable bodies) 5 and 6 due to the foreign matters is suppressed. can do.

  Thus, according to the present invention, it is possible to obtain the capacitance type sensor 1 that can suppress the deterioration of the device characteristics.

  In the present embodiment, the protrusions (stoppers) 51 and 61 are formed in a substantially L shape. Furthermore, the contact portions 51b and 61b are formed so as not to exceed the region of the movable electrodes 5a and 6a in plan view. Therefore, it is possible to suppress the occurrence of a dead space that does not face the fixed electrodes 21a, 21b and 22a, 22b in the regions of the movable electrodes 5a, 6a, and the capacitance detection amount can be increased.

  In the present embodiment, the protrusions (stoppers) 51 and 61 are made of an insulating material. Therefore, it is possible to prevent the movable electrodes 5a, 6a and the fixed electrodes 21a, 21b, 22a, 22b from being short-circuited.

  Note that projections (stoppers) 51A and 61A having a substantially T-shape as shown in FIG. 11 may be used as the stoppers.

  The protrusions (stoppers) 51A and 61A can also be formed of an insulating material such as polyimide or SU-8 (trade name).

  The protrusions (stoppers) 51A and 61A are connected to the support portions 51Aa and 61Aa extending substantially vertically from the surfaces of the movable electrodes 5a and 6a, and the support portions 51Aa and 61Aa, and the surfaces of the movable electrodes 5a and 6a. The contact portions 51Ab and 61Ab that are substantially parallel to and extend toward the outer peripheral side and inner peripheral side of the movable electrodes 5a and 6a (the direction opposite to the extending direction of the outer peripheral side). It is formed in a shape. At this time, the contact portions 51Ab and 61Ab are formed so as not to exceed the region of the movable electrodes 5a and 6a in plan view.

  The contact portions 51Ab and 61Ab are fixed electrodes 21a, which are the other electrodes, when an excessive physical quantity (acceleration) is applied and the weight portions (movable bodies) 5 and 6 are relatively displaced (swings). , 21b and 22a, 22b, contact surfaces 51Ac, 61Ac.

  Further, the contact portions 51Ab and 61Ab are flexible, and are on the opposite side of the contact surfaces 51Ac and 61Ac of the contact portions 51Ab and 61Ab (below the contact portions 51Ab and 61Ab in FIG. 11). The spaces S2 that allow the contact portions 51Ab and 61Ab to bend are formed on both sides of the support portions 51Aa and 61Aa.

  The provision of the projections (stoppers) 51A and 61A having such a configuration can also provide the above-described functions and effects.

(Second Embodiment)
The acceleration sensor 1B according to the present embodiment has basically the same configuration as the acceleration sensor 1 of the first embodiment.

  That is, in the acceleration sensor 1B, the first insulating substrate (first fixing plate) 2 is bonded to the surface (one surface) 4a of the silicon substrate 4, and the second insulating material is connected to the back surface (other surface) 4b of the silicon substrate 4. The space portion S is formed by bonding the conductive substrate (second fixing plate) 3.

  Also in the present embodiment, the protrusions (stoppers) 51 and 61 are connected to the support portions 51a and 61a extending substantially vertically from the surfaces of the movable electrodes 5a and 6a, and the support portions 51a and 61a. The contact portions 51b and 61b that are substantially parallel to the surfaces of the movable electrodes 5a and 6a and extend toward the outer periphery of the movable electrodes 5a and 6a are formed in a substantially L shape. At this time, the contact portions 51b and 61b are formed so as not to exceed the regions of the movable electrodes 5a and 6a in plan view.

  The contact portions 51b and 61b are fixed electrodes 21a, which are the other electrodes, when an excessive physical quantity (acceleration) is applied and the weight portions (movable bodies) 5 and 6 are relatively displaced (oscillating or the like). , 21b and 22a, 22b side abutting surfaces 51c, 61c.

  Further, also in the present embodiment, the contact portions 51b and 61b are flexible, and are opposite to the contact surfaces 51c and 61c of the contact portions 51b and 61b (the contact portions 51b and 61b in FIG. 12). A space S1 that allows the abutment portions 51b and 61b to bend is formed on the lower side of 61b.

  This space S1 is the surface of the movable electrodes 5a and 6a, which is one of the electrodes, and the surface opposite to the contact surfaces 51c and 61c of the contact portions 51b and 61b, and faces the surfaces of the movable electrodes 5a and 6a. Formed between the opposing surfaces 51d and 61d.

  Here, the acceleration sensor 1B according to the present embodiment is mainly different from the acceleration sensor 1 of the first embodiment in that the contact surfaces 51c and 61c of the contact portions 51b and 61b are fixed electrodes 21a which are the other electrodes. , 21b and 22a, 22b are in contact with projections (stoppers) 26, 27 provided separately.

  That is, in this embodiment, when an excessive external force is applied due to application of excessive acceleration (physical quantity) or the like, the weight parts (movable bodies) 5 and 6 are relatively displaced (oscillated or translated upward). The contact portions 51b and 61b of the protrusions (stoppers) 51 and 61 are in contact with the protrusions (stoppers) 26 and 27 (the other electrode side). When the contact portions 51b and 61b of the protrusions (stoppers) 51 and 61 contact the protrusions (stoppers) 26 and 27 (the other electrode side), the contact of the protrusions (stoppers) 51 and 61 The portions 51b and 61b are bent in the direction of narrowing the space S1 (the movable electrode side as one electrode: the lower side).

  The protrusions (stoppers) 51 and 61 and the protrusions (stoppers) 26 and 27 are only required to prevent the movable electrodes 5a and 6a and the fixed electrodes 21a, 21b, 22a and 22b from being short-circuited. Any one of the projecting portions in contact with each other only needs to be formed of an insulating material. Therefore, when the protrusions (stoppers) 51 and 61 are formed of an insulating material, the protrusions (stoppers) 26 and 27 can be integrally provided on the fixed electrodes 21a and 21b and 22a and 22b. In addition, only one of the support portions 51a and 61a and the contact portions 51b and 61b of the projection portions (stoppers) 51 and 61 can be formed of an insulating material.

  Also according to this embodiment described above, the same operations and effects as those of the first embodiment can be achieved.

  Also in the present embodiment, the shape of the protrusions (stoppers) 51 and 61 can be substantially T-shaped.

(Third embodiment)
The acceleration sensor 1C according to the present embodiment basically has the same configuration as the acceleration sensor 1 of the second embodiment.

  That is, in the acceleration sensor 1C, the first insulating substrate (first fixing plate) 2 is bonded to the surface (one surface) 4a of the silicon substrate 4, and the second insulating material is connected to the back surface (other surface) 4b of the silicon substrate 4. The space portion S is formed by bonding the conductive substrate (second fixing plate) 3.

  Here, the acceleration sensor 1C according to the present embodiment is mainly different from the acceleration sensor 1B according to the second embodiment in that the shapes of the protrusions (stoppers) 51 and 61 and the protrusions (stoppers) 26 and 27 are reversed. (See FIG. 13).

  That is, in this embodiment, the fixed electrodes 21a, 21b and 22a, 22b correspond to one electrode, and the movable electrodes 5a, 6a correspond to the other electrode.

  Protrusions (stoppers) 51 and 61 are formed on the surfaces of the movable electrodes 5a and 6a.

  On the other hand, the protrusions (stoppers) 26, 27 are connected to the support portions 26a, 27a extending substantially perpendicularly from the surfaces of the fixed electrodes 21a, 21b and 22a, 22b, and the support portions 26a, 27a to be fixed. The contact portions 26b and 27b that are substantially parallel to the surfaces of the electrodes 21a and 21b and 22a and 22b and extend toward the inside of the fixed electrodes 21a and 21b and 22a and 22b are formed in a substantially L shape. . At this time, the contact portions 26b and 27b are formed so as not to exceed the regions of the fixed electrodes 21a and 21b and 22a and 22b in plan view.

  The contact portions 26b and 27b are movable electrodes 5a which are the other electrodes when an excessive physical quantity (acceleration) is applied and the weight portions (movable bodies) 5 and 6 are relatively displaced (oscillating or the like). , 6a side contact surfaces 26c, 27c.

  Furthermore, also in this embodiment, the contact portions 26b and 27b have flexibility, and the contact portions 26b and 27b are opposite to the contact surfaces 26c and 27c (in FIG. 13, the contact portions 26b and 27b, A space S3 that allows the abutment portions 26b and 27b to bend is formed on the upper side of 27b.

  This space S3 is a surface opposite to the surfaces of the fixed electrodes 21a, 21b and 22a, 22b, which are one of the electrodes, and the contact surfaces 26c, 27c of the contact portions 26b, 27b, and the fixed electrodes 21a, 21b. And the opposing surfaces 26d and 27d facing the surfaces of 22a and 22b.

  Also according to this embodiment described above, the same operations and effects as those of the second embodiment can be achieved.

  Also in this embodiment, the shape of the protrusions (stoppers) 26 and 27 can be substantially T-shaped.

  Further, it is also possible to make the contact surfaces 26c, 27c of the contact portions 26b, 27b directly contact with the surfaces of the movable electrodes 5a, 6a without providing the protruding portions (stoppers) 51, 61.

(Fourth embodiment)
The acceleration sensor 1D according to the present embodiment has basically the same configuration as the acceleration sensor 1C of the third embodiment.

  That is, in the acceleration sensor 1D, the first insulating substrate (first fixing plate) 2 is bonded to the surface (one surface) 4a of the silicon substrate 4, and the second insulating material is connected to the back surface (other surface) 4b of the silicon substrate 4. The space portion S is formed by bonding the conductive substrate (second fixing plate) 3.

  Also in this embodiment, the protrusions (stoppers) 26D and 27D provided on the fixed electrodes 21a and 21b and 22a and 22b are provided with a spring property.

  Here, the acceleration sensor 1D according to the present embodiment is mainly different from the acceleration sensor 1C of the third embodiment in that part of the substantially plate-like protrusions (stoppers) 26D and 27D are fixed electrodes 21a and 21b and The protrusions (stoppers) 26D and 27D are provided so as to protrude from the regions 22a and 22b.

  Specifically, as shown in FIG. 14, a part of the substantially plate-like protrusions (stoppers) 26D and 27D are protruded from the fixed electrodes 21a, 21b and 22a, 22b, and the protruded parts are brought into contact with each other. The parts 26Db and 27Db are used. The contact surfaces 26Dc and 27Dc of the contact portions 26Db and 27Db are directly brought into contact with the surfaces of the movable electrodes 5a and 6a.

  In this way, the first insulating substrate (one electrode side) 2 is formed by protruding a part of the substantially plate-like protrusions (stoppers) 26D, 27D from the regions of the fixed electrodes 21a, 21b and 22a, 22b. On the lower surface (inner surface) 2a of the first insulating substrate (one electrode side) 2 on the opposite side of the contact surfaces 26Dc and 27Dc of the contact portions 26Db and 27Db. A space S4 is formed between the opposing surfaces 26Dd and 27Dd. This space S4 allows the contact portions 26Db and 27Db to bend.

  Also according to the present embodiment described above, the same operations and effects as those of the third embodiment can be achieved.

  The protrusions (stoppers) 51 and 61 are provided on the surfaces of the movable electrodes 5a and 6a so that the contact surfaces 26Dc and 27Dc of the contact portions 26Db and 27Db are brought into contact with the protrusions (stoppers) 51 and 61, respectively. It is also possible.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various modifications can be made.

  For example, in each of the above embodiments, an acceleration sensor that detects acceleration in two directions of the X direction and the Z direction has been illustrated. However, one of the weight portions is arranged by being rotated 90 degrees in the XY plane, and the Y direction is added. Alternatively, an acceleration sensor that detects acceleration in three directions may be used.

  Moreover, in each said embodiment, although the acceleration sensor was illustrated as an electrostatic capacitance type sensor, it is not restricted to this, This invention is applicable also to another electrostatic capacitance type sensor.

  Further, in each of the above embodiments, the semiconductor substrate formed using the SOI substrate is exemplified, but it is also possible to form the movable body and the frame portion using the semiconductor substrate made of Si without using the SOI substrate. .

  Further, the specifications (shape, size, layout, etc.) of the weight portion, fixed electrode, and other details can be changed as appropriate.

1,1A, 1B, 1C Acceleration sensor (capacitance sensor)
2 First insulating substrate (first fixing plate)
4 Silicon substrate (semiconductor substrate)
5,6 Weight (movable body)
5a, 6a Movable electrode 21a, 21b, 22a, 22b Fixed electrode 26 Projection (stopper)
26b, 26Db contact part 26c, 26Dc contact surface 27 protrusion (stopper)
27b, 27Db contact part 27c, 27Dc contact surface 51 protrusion (stopper)
51b, 51Ab Contact part 51c, 51Ac Contact surface 61 Projection part (stopper)
61b, 61Ab contact part 61c, 61Ac contact surface S1, S2, S3, S4 space

Claims (3)

A static plate is formed by bonding a first fixed plate on which a fixed electrode is formed on one surface of a semiconductor substrate on which a movable body having a movable electrode is formed so as to be relatively displaceable. A capacitive sensor,
A stopper is provided on at least one of the movable electrode and the fixed electrode,
The stopper includes a flexible contact portion having a contact surface that contacts the other electrode side when the movable body is relatively displaced, and on the opposite side of the contact surface of the contact portion. Is a capacitance type sensor characterized in that a space allowing the bending of the contact portion is formed.   The capacitive sensor according to claim 1, wherein the stopper is formed in a substantially L shape or a substantially T shape.   The capacitive sensor according to claim 1, wherein the stopper is made of an insulating material.

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