JP2011049211A - Capacitive sensor and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a capacitive sensor wherein damage on a weight can be controlled, and to obtain a method of manufacturing a capacitive sensor wherein a process of forming a protrusion can be simplified. <P>SOLUTION: In the capacitive sensor 1, including an insulating substrate 2 and a silicon substrate 4 bonded to the insulating substrate 2 wherein a weight 5 and a support 16 for supporting the weight 5 via a spring 6 are formed on the silicon substrate 4 and a gap 7 is formed between the weight 5 and the insulating substrate 2, a pyramid-like protrusion 12, having a tapered leading end and facing the insulating substrate 2, is provided at least at the periphery of the surface 5a of the weight 5 facing the insulating substrate 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a capacitive sensor and a method for manufacturing the same.

  Conventionally, as a micromechanism device that can be used as a capacitive sensor, a device including a substrate and a weight portion disposed with a gap (gap) provided on one surface of the substrate is known (for example, , See Patent Document 1).

  In Patent Document 1, in order to prevent sticking when the deflection of the weight portion is large, a protrusion (spike) is provided on the surface of the substrate facing the weight portion.

Japanese National Patent Publication No. 10-512675

  However, in such a conventional technique, the protrusion provided on the substrate is provided with an auxiliary layer between the substrate and the weight portion, and etching openings are provided in the lattice portion in a lattice shape, and the four etching openings provided in the lattice shape are provided. The auxiliary layer is etched so that a residual layer portion remains in the center.

  As described above, there is a problem that an extra auxiliary layer is required to provide the protrusion, and the manufacturing process becomes complicated.

  Further, in the conventional technique, a protrusion is formed at the center of the four etching openings provided in a lattice shape, and when the weight is largely deflected toward the substrate, the protrusion is arranged at the periphery of the weight. Since the weight portion is inclined and interferes with the substrate, the weight portion may be damaged.

  Accordingly, an object of the present invention is to obtain a capacitive sensor capable of suppressing damage to the weight portion and to obtain a manufacturing method of the capacitive sensor capable of simplifying the process of forming the protrusion. And

  In the first aspect of the invention, an insulating substrate and a silicon substrate bonded to the insulating substrate are provided, and a weight portion and a support portion for supporting the weight portion via a spring portion are formed on the silicon substrate. In addition, in the capacitive sensor in which a gap is formed between the weight portion and the insulating substrate, at least the peripheral portion of the surface of the weight portion facing the insulating substrate faces the insulating substrate. A pyramid-shaped protrusion having a tapered tip is provided.

  According to a second aspect of the present invention, in the capacitive sensor according to the first aspect, the gap and the protrusion are formed by removing a part of the silicon substrate by silicon anisotropic etching. It is characterized by that.

  In the invention of claim 3, the weight portion and the support portion for supporting the weight portion via the spring portion are formed on the silicon substrate bonded to the insulating substrate, and the silicon substrate faces the insulating substrate. In the method of manufacturing a capacitive sensor in which a gap is formed between the weight portion and the insulating substrate by recessing the surface, masking is performed on the surface of the silicon substrate except for the gap formation scheduled portion. In a state where the projection formation planned portion in the gap formation planned portion is masked in advance, a part of the silicon substrate is removed by silicon anisotropic etching, so that the surface of the gap and the weight portion facing the insulating substrate is removed. A pyramid-shaped protrusion having a tapered tip end facing the insulating substrate is provided at least in the periphery of the facing surface.

  According to the first aspect of the present invention, the pyramid-shaped protrusion whose tip is opposed to the insulating substrate is provided at least in the peripheral portion of the surface of the weight portion facing the insulating substrate. It becomes possible to suppress the tilting of the weight part when it comes into contact, and damage to the weight part can be suppressed.

  According to the second and third aspects of the present invention, since the protrusion is simultaneously formed when the gap is recessed in the weight portion, the process of forming the protrusion can be simplified.

FIG. 1 is a plan view showing an acceleration sensor according to a first embodiment of the present invention together with an enlarged view of a main part. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is a cross-sectional view schematically showing a process of forming a protrusion on the weight of the acceleration sensor according to the first embodiment of the present invention. FIG. 4 is a plan view of the acceleration sensor according to the second embodiment of the present invention. 5 is a cross-sectional view taken along line BB in FIG. 6 is a cross-sectional view taken along the line CC of FIG. 7A and 7B are enlarged cross-sectional views of main parts taken along line DD in FIG. 4 and line EE in FIG. 4B, respectively. FIG. 8 is a view showing a spring portion of the acceleration sensor according to the second embodiment of the present invention.

  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. Note that similar components are included in the following embodiments. Therefore, in the following, common reference numerals are given to those similar components, and redundant description is omitted.

(First embodiment)
As shown in FIGS. 1 and 2, the acceleration sensor 1 according to the present embodiment includes a silicon substrate 4 on which a semiconductor element device is formed, and a first insulating glass member bonded to both upper and lower surfaces of the silicon substrate 4. An insulating substrate (insulating substrate) 2 and a second insulating substrate 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. The first insulating substrate 2 is provided with a fixed electrode 21 corresponding to the installation area of the weight portion 5 on the lower surface of the first insulating substrate 2. In the present embodiment, the fixed electrode 21 is formed in a region facing a gap 7 described later formed on the silicon substrate 4 of the first insulating substrate 2.

  The silicon substrate 4 is formed in a substantially rectangular shape, and the silicon substrate 4 is provided with a weight portion 5 that can be displaced in the thickness direction of the first insulating substrate 2 (vertical direction in FIG. 2). Furthermore, in this embodiment, the weight part 5 comprises the movable electrode. The weight portion (movable electrode) 5 is supported by a substantially frame-shaped support portion 16 disposed so as to surround the weight portion (movable electrode) 5 via two beams 61 as the spring portion 6. . Each beam 61 has a thickness dimension set sufficiently smaller than the thicknesses of the weight part (movable electrode) 5 and the support part 16 so as to have flexibility in the thickness direction. That is, the beam 61 functions as a spring element that elastically moves and supports the weight portion (movable electrode) 5 with respect to the support portion 16.

  Thus, in this embodiment, the weight part (movable electrode) 5 is provided with a function as a mass element that is movably supported by the beam 61 as a spring element, and a spring-mass system is formed by these spring elements and mass elements. The acceleration and angular acceleration can be obtained from the displacement of the weight part (movable electrode) 5 as a mass element.

  A relatively shallow gap 7 and recess 31 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 weight part (movable electrode) 5 is ensured.

  Specifically, the upper surface 4a of the silicon substrate 4 is recessed including the formation part of the weight part (movable electrode) 5 and the beam 61 and the peripheral part thereof, so that the upper part of the weight part (movable electrode) 5 is raised. The gap 7 that allows displacement is formed, and the upper surface 3a of the second insulating substrate 3 is recessed including the formation region of the weight portion (movable electrode) 5 and the peripheral portion thereof, whereby the weight portion (movable) A recess 31 that allows downward displacement of the electrode 5 is formed. Thus, the gap 7 is formed between the fixed electrode 21 and the weight part (movable electrode) 5, and the fixed electrode 21 and the weight part (movable electrode) facing each other through the gap 7 with the gap 7 as a detection gap. The electrostatic capacity between 5 is detected. In this embodiment, the gap 7 is formed by removing a part of the silicon substrate 4 by silicon anisotropic etching using an alkaline wet anisotropic etching solution (for example, KOH, TMAH, EDP aqueous solution, etc.). ing.

  In the present embodiment, the weight part (movable electrode) 5 has a substantially rectangular shape as shown in FIG. 1, and each beam 61 extends along the outer peripheral edge of the weight part (movable electrode) 5. It is formed in the shape. Then, all the beams 61 are formed in a shape that surrounds substantially the entire outer peripheral edge of the weight portion (movable electrode) 5.

  Specifically, each beam 61 is formed in an L shape along two adjacent sides of the outer peripheral edge of the weight portion (movable electrode) 5, and the weight portion (movable electrode) of both ends of each beam 61. ) The end portion on the 5 side (the end portion on the side connected to the weight portion) is connected to each of the two corner portions at diagonal positions on the rectangular outer periphery of the weight portion (movable electrode) 5. That is, one end of the right beam 61 in FIG. 1 is continuously connected to the lower left corner of the weight (movable electrode) 5 and the other end connected to the support 16 is connected to the weight ( One end of the left beam 61 is connected to the upper right corner of the weight (movable electrode) 5 continuously and integrally connected to the support portion 16. The other end part connected integrally is located in the vicinity of the lower left corner of the weight part (movable electrode) 5. Further, two slits 17 penetrating in the thickness direction of the beam 61 are formed around the weight portion (movable electrode) 5, and the width dimension of each beam 61 is defined by these two slits 17.

  The slit 17 is formed so that the side wall surface of the slit 17 is perpendicular to the surface of the silicon substrate 4 by performing vertical etching processing such as reactive ion etching (RIE). In this way, the side wall surfaces of the slits 17 formed by the vertical etching process face each other substantially in parallel. As reactive ion etching, for example, ICP processing by an etching apparatus provided with inductively coupled plasma (ICP) can be used.

  In addition, it is also possible to provide arcuate portions that smoothly continue to the support portion 16 and the weight portion (movable electrode) 5 at both ends of each beam 61 so as to increase the mechanical strength of both ends of each beam 61. Good.

  Thus, by forming each beam 61 in a shape extending along the outer peripheral edge of the weight portion (movable electrode) 5, the chip size can be increased as compared with the conventional case, or the outer shape of the weight portion (movable electrode) 5. It is possible to significantly increase the length of the beam 61 without reducing the height of the beam 61, and it is possible to achieve high sensitivity without increasing the chip size as compared with the prior art. In addition, the outer peripheral shape of the weight part (movable electrode) 5 is rectangular, and each beam 61 is formed in an L shape along two adjacent sides of the outer peripheral edge of the weight part (movable electrode) 5, so that the beam 61 is formed. While the length of the beam 61 is increased by two, the facing surface 5a of the weight portion (movable electrode) 5 facing the fixed electrode 21 is made difficult to tilt with respect to the fixed electrode 21.

  In this embodiment, the weight portion (movable electrode) 5, each beam 61, and the support portion 16 are formed by performing a known etching process on a single crystal silicon substrate (Si substrate). The weight portion 5 constitutes a movable electrode, and acceleration or angular acceleration (physical quantity) is detected as a change in capacitance value between the movable electrode and the fixed electrode 21 according to the displacement of the weight portion 5. ing. At this time, the weight part 5 is formed in a substantially square frustum shape, and the facing surface 5a facing the fixed electrode 21 is substantially flat. In the present embodiment, the weight portion 5 constitutes a movable electrode. However, the movable electrode may be separately formed on the surface 5 a of the weight portion 5 facing the fixed electrode 21.

  In addition, the first conductive thin film 11 is formed on the surface 2a of the first insulating substrate 2 and used as a wiring pattern for acquiring the potential of the fixed electrode 21, and the second conductive thin film ( (Not shown) is used as a wiring pattern for acquiring the potential of the weight 5.

  In the present embodiment, as shown in FIG. 1, the gap 7 of the first insulating substrate 2 has an arm shape extending from a substantially frame-like part where the weight part 5 is formed to a part of the support part 16. The first through-hole 22 is formed by sandblasting or the like in a portion corresponding to the extended portion 7a of the first insulating substrate 2 and the first insulating substrate 2 is formed. 2, the second through holes 23 are respectively formed in portions of the first insulating substrate 2 where the fixed electrode 21 is not formed in a plan view. A part of the first through-hole 22 and the second through-hole 23 are exposed to the back of the first through-hole 22 and the second through-hole 23, and the first through-hole 22 and the second through-hole 23 are exposed from the surface 2 a of the first insulating substrate 2. On the inner peripheral surface and the first insulating group A series of first conductive thin film 11 and a second conductive thin film (not shown) electrically connected over the surface 2a of the second film are formed, and the first conductive thin film 11 and The potentials of the fixed electrode 21 and the weight portion 5 can be detected from a second conductive thin film (not shown). The first conductive thin film 11 and the second conductive thin film (not shown) are formed so as not to contact each other.

  In FIG. 2, reference numeral 9 denotes a conductive layer connected to each conductive thin film, and reference numeral 10 denotes an insulating layer that insulates the conductive layer 9 from the silicon substrate 4. As shown in FIG. 1, a recess 42 is formed in a portion corresponding to the second through hole 23 of the silicon substrate 4, and the conductive layer 9 is formed in the recess 42. The conductive layer 9 corresponding to the first through hole 22 is short-circuited to the fixed electrode 21, and the conductive layer 9 corresponding to the second through hole 23 is short-circuited to the support portion 16 of the silicon substrate 4. By the way, in the present embodiment, as described above, the gap 7 is formed in the silicon substrate 4 and the two slits 17 penetrating in the thickness direction of the silicon substrate 4 are formed. The weight part 5, the beam 61, and the support part 16 are integrally formed. Therefore, the potentials of the weight portion 5, the beam 61, and the support portion 16 can be regarded as almost equipotential. The surface 2a of the first insulating substrate 2 is preferably covered (molded) with a resin layer (not shown).

  Further, in the present embodiment, a pyramid-like shape in which the tip portion facing the lower surface of the first insulating substrate 2 is tapered at least in the peripheral portion of the facing surface 5a of the weight portion 5 with respect to the first insulating substrate 2. A protrusion 12 is formed. In the present embodiment, the pyramidal projections 12 are formed so as to be uniformly distributed over almost the entire area of the facing surface 5a. At this time, it is preferable that the pyramid-shaped protrusion 12 is provided so as to be point-symmetric with respect to the center of the weight portion 5 so as not to shift the position of the center of gravity of the weight portion 5.

  By the way, in this embodiment, as described above, the gap 7 is formed by removing a part of the silicon substrate 4 by silicon anisotropic etching, but alkaline wet anisotropic etching at a predetermined concentration and a predetermined temperature. When silicon anisotropic etching is performed using a liquid, a difference in chemical etching rate occurs due to a difference in atomic arrangement inside the silicon crystal, and a quadrangular pyramid having an almost accurate angle (54.74 °) on the inclined surface. It is known that a micropyramid of is formed.

  That is, the (111) plane is less likely to be etched than the (100) plane due to its crystal structure, and the silicon crystal is anisotropic by wet etching using a silicon single crystal substrate having the (100) plane as the principal plane. It is known that when etching is performed, a quadrangular pyramid-shaped micropyramid composed of a (111) plane is obtained on the etched surface of a silicon single crystal substrate.

  Therefore, in this embodiment, when forming the gap 7 by removing a part of the silicon substrate 4 by silicon anisotropic etching, the etching surface of the silicon substrate 4, that is, the first insulating property of the weight portion 5 is formed. A pyramidal projection 12 is formed on the facing surface 5a by forming a quadrangular pyramid-shaped micropyramid on the facing surface 5a of the substrate 2.

Specifically, first, the upper surface 4a of the silicon substrate 4 is oxidized to form the SiO ₂ film 13, and the gap formation scheduled portion 40 is exposed by patterning. At this time, the protrusion formation scheduled portion 41 of the gap formation planned portion 40 is excluded and exposed. In this way, the portion of the upper surface 4a of the silicon substrate 4 except for the gap formation scheduled portion 40 is masked with the SiO ₂ film 13, and the projection formation scheduled portion 41 in the gap formation scheduled portion 40 is previously formed in the SiO ₂ film 13. In the masked state, a part of the silicon substrate 4 is removed by silicon anisotropic etching, whereby the facing surface 5a of the gap 7 and the weight portion 5 is formed, and the first insulating property is formed on the facing surface 5a. A micro pyramid (pyramid projection) 12 is formed in which a tip portion facing the lower surface of the substrate 2 is tapered.

  By the way, in the actual acceleration sensor 1, the gap 7 is about 5 μm and the height of the protrusion 12 is about 0.5 μm. Moreover, the mass (thickness) of the weight part 5 is determined according to the magnitude of the acceleration to be detected, and is, for example, about 300 μm to 500 μm.

  According to the present embodiment described above, since the micro pyramid (pyramid protrusion) 12 is provided on the surface 5a of the weight portion 5 facing the first insulating substrate 2, the weight portion is caused by excessive acceleration input. When 5 comes into contact with the first insulating substrate 2, the contact area between the weight portion 5 and the first insulating substrate 2 can be reduced, and sticking of the weight portion 5 can be suppressed. Further, since the protrusion 12 has a pyramid shape with the tip end facing the first insulating substrate 2 being tapered, the protrusion 12 makes point contact with the first insulating substrate 2. The suppression effect can be further improved.

  In addition, according to the present embodiment, the micro pyramid (pyramid protrusion) 12 is provided on at least the peripheral portion of the facing surface 5a of the weight portion 5 with respect to the first insulating substrate 2, so that the weight portion 5 and the first It is possible to prevent the weight portion 5 from being inclined when the insulating substrate 2 comes into contact with the insulating substrate 2, and damage to the weight portion 5 can be suppressed.

  In addition, according to the present embodiment, the micro pyramid (pyramid protrusion) 12 is formed at the same time when the gap 7 is recessed in the weight portion 5, so that the micro pyramid (pyramid protrusion) 12 is formed. The process can be simplified. As a result, an increase in product cost can be suppressed, and an opening for forming the micro pyramid (pyramid protrusion) 12 is not formed in the weight 5, so that the mass of the weight 5 can be easily secured. It is possible to suppress the increase in size of the apparatus.

Note that the micropyramid is formed even if silicon anisotropic etching is performed using an alkaline wet anisotropic etching solution having a predetermined concentration and a predetermined temperature without masking the projected formation portion 41 with the SiO ₂ film 13 in advance. However, there is a problem that it is difficult to form at a desired position on the facing surface 5a of the weight portion 5. However, as in the present embodiment, a part of the silicon substrate 4 is removed by silicon anisotropic etching in a state in which the projection forming portion 41 in the gap forming scheduled portion 40 is previously masked with the SiO ₂ film 13. By doing so, the difference between the etching rate of the masked part and the etching rate of the unmasked part in the gap formation scheduled portion 40 can be increased, and the micropyramid can be reliably formed in the masked part. It becomes like this. That is, a part of the silicon substrate 4 is removed by silicon anisotropic etching in a state where the projection formation planned portion 41 in the gap formation planned portion 40 is masked by the SiO ₂ film 13 in advance. It becomes possible to form a micropyramid at the site.

(Second Embodiment)
4 to 8 show a second embodiment of the present invention. The acceleration sensor 1 shown in the first embodiment detects the acceleration by the vertical displacement of the weight portion, whereas the acceleration of the present embodiment. The sensor 100 detects acceleration by the horizontal displacement of the weight portion.

  Similar to the first embodiment, the acceleration sensor 100 according to the present embodiment includes a silicon substrate 400 on which a semiconductor element device is formed, and a first glass substrate bonded to upper and lower surfaces 400a and 400b of the silicon substrate 400, respectively. The insulating substrate (insulating substrate) 200 and the second insulating substrate 300 are provided, and the silicon substrate 400 and the first insulating substrate 200 and the second insulating substrate 300 are bonded by anodic bonding. is doing.

  The silicon substrate 400 is formed by forming a gap 500 in the silicon substrate 400 by a known semiconductor process, so that a substantially rectangular frame portion 410 formed at the peripheral portion, a fixed electrode body 420, a weight portion 430 serving as a movable electrode body, A spring portion 440 and a support portion 450 that supports the weight portion 430 via the spring portion 440 are formed.

  The gap 500 is formed so that the side wall surface of the gap 500 is perpendicular to the surface of the silicon substrate 400 by performing vertical etching processing such as reactive ion etching, as in the first embodiment. In this way, the side wall surfaces of the gap 500 formed by the vertical etching process face each other substantially in parallel. As the reactive ion etching, for example, ICP processing using an etching apparatus equipped with inductively coupled plasma can be used.

  The fixed electrode body 420 is provided at two positions on the left and right sides of the center line Y of the silicon substrate 400, and the outer portions of the plurality of comb-shaped fixed electrodes 422 are connected by the trunk portion 421. That is, the plurality of comb-like fixed electrodes 422 are projected in parallel from the trunk 421 at a predetermined interval.

  The weight portion 430 is disposed between the fixed electrode bodies 420 disposed on the left and right sides, and a stem portion 431 disposed along the center line Y, and comb-shaped fixed electrodes from both ends of the trunk portion 431 in the center line Y direction. A plurality of extending portions 432 that extend toward the trunk portion 421 of each fixed electrode body 420 in parallel with the extending direction of 422 and form a substantially H shape with the trunk portion 431, and a plurality of portions that extend from the trunk portion 431 in the left-right direction. Comb-shaped movable electrode 433.

  The plurality of comb-like movable electrodes 433 are projected in parallel from the trunk portion 431 at a predetermined interval so as to be inserted between two adjacent comb-like fixed electrodes 422. That is, the comb-like fixed electrode 422 and the comb-like movable electrode 433 are alternately arranged as shown in FIGS. 7A and 7B.

  At this time, predetermined gaps δ1 and δ2 (δ1 <δ2) are provided between the respective comb-like fixed electrodes 422 and the comb-like movable electrodes 433. In the present embodiment, the gaps δ1 and δ2 between the electrodes 422 and 433 are different between the left and right fixed electrode bodies 420 shown in FIG. 4, and as shown in FIGS. 7A and 7B, the left fixed electrodes The body 420 has a gap δ1 on one side and the gap δ2 on the other side, whereas the fixed electrode body 420 on the right side has a gap δ2 and the other side has a gap δ1.

  The extension portions 432 at both ends are connected to the spring portions 440 described above, and the support portion 450 that supports the weight portion 430 via the spring portions 440 is more in the center line Y direction than the extension portion 432. It is provided outside. In the present embodiment, the support portion 450 is provided at one location on the upper side and two locations on the lower side in FIG. 4, each of which is formed in a substantially rectangular shape and fixed to the first insulating substrate 200 by anodic bonding or the like. Yes.

  As shown in FIG. 8, each spring portion 440 is formed by two spring single bodies 441 arranged symmetrically. Each spring single body 441 has a shape in which one continuous elongated linear spring 441a is bent into a plurality of stages. One end portion 441b of the linear spring 441a is provided at a substantially central portion of the spring single body 441 extending in the width direction, and is connected to the inner corner of the support portion 450, respectively. Further, the other end portion 441c of the linear spring 441a is provided at a substantially central portion of the single spring 441, and is connected to the extending portion 432, respectively.

  Thus, by connecting the spring part 440 to the weight part 430 and the support part 450, the spring part 440 functions as a spring element that elastically moves and supports the weight part 430 with respect to the support part 450.

  Thereby, in the acceleration sensor 100 according to the present embodiment, a function as a mass element (mass) supported by the spring portion 440 as a spring element and the support portion 450 connected to the spring portion 440 with respect to the weight portion 430. The spring-mass system is constituted by these spring elements and mass elements. Then, a change in the capacitance value between the weight portion 430 and the fixed electrode body 420 due to the displacement of the weight portion 430 as a mass element is detected, and applied to the acceleration sensor 100 based on the detected change in the capacitance value. Acceleration and angular acceleration (physical quantity) are detected.

  Specifically, the change in the capacitance value is detected by the detection units 490 and 491 including the comb-shaped movable electrode 433 and the comb-shaped fixed electrode 422 formed on the weight portion 430 and the fixed electrode body 420, respectively. Detected.

  For example, when acceleration is applied in the center line Y direction shown in FIG. 4, the comb-like movable electrode 433 is displaced in the center line Y direction, and the comb-like movable electrode 433 and the comb-like fixed electrode 422 of the detection unit 490 are displaced. There is a difference between the detected capacitance value and the capacitance values detected by the comb-like movable electrode 433 and the comb-like fixed electrode 422 of the detection unit 491. The acceleration in the centerline Y direction can be detected from the difference between the capacitance values.

  In FIG. 4, reference numeral 461 denotes a first conductive layer electrically connected to the comb-like movable electrode 433 of the weight part 430 via the spring part 440, and 462 denotes a comb tooth of the left fixed electrode body 420. The second conductive layer is electrically connected to the fixed electrode 422, and the third conductive layer 463 is electrically connected to the comb-like fixed electrode 422 of the right fixed electrode body 420. Reference numeral 464 denotes a fourth conductive layer that is electrically connected to the frame portion 410.

  Further, through holes 210 (through holes corresponding to the fourth conductive layer 464 are not shown) in portions corresponding to the first to fourth conductive layers 461 to 464 of the first insulating substrate 200 by sandblasting or the like. ), And the first to fourth conductive layers 461 to 464 provided on the silicon substrate 4 are exposed to the back of each through-hole 210, and each through-hole is formed on the surface 200a of the first insulating substrate 200. A series of electrically conductive thin films (not shown) that are electrically connected over the inner peripheral surface of the hole 210 and the surface 200a of the first insulating substrate 200 are formed to form each electrically conductive thin film (FIG. The potentials of the fixed electrode body 420, the weight portion 430, and the frame portion 410 can be detected from (not shown).

  Each conductive thin film (not shown) is formed on the surface 200a of the first insulating substrate 200 so as not to contact each other. Moreover, it is preferable that the surface 200a of the first insulating substrate 200 is covered (molded) with a resin layer (not shown).

  Further, in the present embodiment, as in the first embodiment, a relatively shallow gap 470 and recess 301 are formed on the bonding surface between the silicon substrate 400 and the first insulating substrate 200 and the second insulating substrate 300. Each is formed, and insulation of each part of the silicon substrate 400 and operability of the weight part 430 are ensured.

  The gap 470 is formed by removing a part of the silicon substrate 400 by silicon anisotropic etching using an alkaline wet anisotropic etching solution (for example, KOH, TMAH, EDP aqueous solution, etc.).

  As described above, when the gap 470 and the concave portion 301 are formed in order to ensure the insulation of each part of the silicon substrate 400 and the operability of the weight part 430, the weight part 430 can be moved in the vertical direction, and is comb-like. When an excessive acceleration having an inclination with respect to the horizontal direction in which the fixed electrode 422 and the comb-like movable electrode 433 are opposed to each other is input, the weight portion 430 is formed by the vertical component of the acceleration in the first insulating substrate 200. It is conceivable that sticking occurs on the ground.

  Therefore, a pyramid-shaped protrusion 480 whose tip end facing the lower surface of the first insulating substrate 200 is tapered is provided at least in the peripheral portion of the surface 430a facing the first insulating substrate 200 of the weight portion 430. .

  In the present embodiment, the pyramidal protrusions 480 are formed so as to be uniformly distributed over substantially the entire area of the facing surface 430a. At this time, it is preferable to provide the pyramid-shaped protrusions 480 so as to be point-symmetric with respect to the center of the weight part 430 so as not to shift the position of the center of gravity of the weight part 430.

  Also in this embodiment, when the gap 470 is formed by removing a part of the silicon substrate 400 by silicon anisotropic etching, the etching surface of the silicon substrate 400, that is, the first insulation of the weight portion 430 is formed. A pyramidal protrusion 480 is formed on the facing surface 430a by forming a quadrangular pyramid-shaped micropyramid on the facing surface 430a to the conductive substrate 200.

  This micropyramid can be formed by the method described in the first embodiment.

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

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and various modifications can be made.

  For example, in each of the above embodiments, the projections are provided on the entire surface of the weight part. However, the present invention is not limited to this, and the outer peripheral parts (near edges) of the four corners of the rectangular weight part, It may be arranged only in a portion that is point-symmetric with respect to the center of the weight portion so as not to shift the position.

  Further, the weight part and other detailed specifications (shape, size, layout, etc.) can be changed as appropriate.

1,100 Acceleration sensor (capacitance sensor)
2,200 First insulating substrate (insulating substrate)
4,400 Silicon substrate 4a, 400a Silicon substrate surface 5, 430 Weight portion 5a, 430a Opposing surface 6, 440 Spring portion 7, 470 Gap 12, 480 Micropyramid (protrusion)
16, 450 Support part 40 Gap formation scheduled part 41 Projection formation scheduled part

Claims (3)

An insulating substrate; and a silicon substrate bonded to the insulating substrate, wherein a weight portion and a support portion for supporting the weight portion via a spring portion are formed on the silicon substrate, and the weight portion and the insulation are formed. In the capacitive sensor in which a gap is formed between the substrate and
A capacitive sensor, wherein a pyramid-shaped protrusion having a tip end facing the insulating substrate is tapered at least in a peripheral portion of a surface of the weight portion facing the insulating substrate.   The capacitive sensor according to claim 1, wherein the gap and the protrusion are formed by removing a part of the silicon substrate by anisotropic etching of silicon. By forming a weight portion and a support portion for supporting the weight portion via a spring portion on a silicon substrate bonded to the insulating substrate, and forming a concave surface on the surface of the silicon substrate facing the insulating substrate, In the method of manufacturing a capacitive sensor in which a gap is formed between the weight portion and the insulating substrate,
By masking the surface of the silicon substrate except for the gap formation planned portion, and removing the portion of the silicon substrate by silicon anisotropic etching in a state where the projection formation planned portion in the gap formation planned portion is masked in advance. The gap and the weight portion form a surface facing the insulating substrate, and at least a peripheral portion of the facing surface is provided with a pyramid-shaped protrusion having a tapered tip end facing the insulating substrate. Manufacturing method of capacitance type sensor.

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