JP2012220376A - Acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the service life and yield of an acceleration sensor.SOLUTION: A main body 1 includes a box-like frame part 1a, one side of which is opened, and a movable part 1b located inside a side wall portion 1a1 thereof. The movable part 1b is mounted rotatably on a pair of beams 1c as a rotation shaft which connects between the both sides of the movable part 1b and insides of the side face of the frame part 1a. The movable part 1b is provided with a movable electrode 6 at a first fixed board 2 side thereof. The first fixed board 2 is provided, at both sides of the rotation shaft in plan view, with first and second fixed electrodes 4A and 4B facing the movable electrode 6. Defining an area of the first fixed board 2, which is located between the first fixed electrode 4A and the second fixed electrode 4B in plan view, as a space portion 7A; and an area of the movable part 1b, which faces the space portion 7A, as a space-facing portion 7B, at least one of the space portion 7A and the space-facing portion 7B has a concave portion 8 formed therein.

Description

  The present invention relates to an acceleration sensor.

  Conventionally, an acceleration sensor chip in which a movable electrode and a fixed electrode are formed using a micromachining technique has been proposed.

  For example, an acceleration sensor described in JP 2010-272696 A (Patent Document 1).

  This acceleration sensor is a capacitance-type acceleration sensor, and as shown in FIG. 13, formed using a sensor body 1 ′ formed using an SOI substrate, which is a semiconductor substrate, and a first glass substrate. The first fixed substrate 2 ′ fixed to one surface side (upper surface side in FIG. 13) of the sensor body 1 ′ and the second glass substrate are formed and fixed to the other surface side of the sensor body 1 ′. And a second fixed substrate 3 ′.

  The sensor body 1 ′ includes a frame portion 11 ′ in which two opening windows having a rectangular shape in plan view are arranged along the one surface, and the fixed substrates 2 ′ and 3 inside the opening windows of the frame portion 11 ′. The two weight parts 13 ′ having a rectangular shape when viewed from above and the weight parts 13 ′ are disposed inside the respective opening windows of the frame part 11 ′, and the frame part 11 is disposed on the one surface side. A pair of support spring portions 14 ′ connecting the “and the weight portions 13” are provided, and the frame portion 11 ′ is joined to the fixed substrates 2 ′ and 3 ′.

  In the first fixed substrate 2 ′, two fixed electrodes 25 ′ made of a metal thin film (for example, an Al—Si film) are arranged in parallel for each portion facing each weight 13 ′, and each weight 13 'Is provided with a movable electrode 15', and the weights 13 of the sensor body 1 are different in mass from each other in spite of having the same planar size at both sides of the support spring part 14 '.

  It should be noted that the sensor body 1 ′ has one weight portion 13 ′ that rotates the other weight portion 13 ′ by 180 ° in plan view with respect to the two weight portions 13 ′ disposed in the adjacent opening windows. When these weight portions 13 'vibrate, the opposing area of the paired fixed electrode 25' and movable electrode 15 'changes, and the capacitance of the variable capacitor changes. . By detecting the change in the capacitance, acceleration in the x-axis direction and the z-axis direction in FIG. 13 can be detected.

JP 2010-272696 A

  By the way, as shown in FIG. 13, in the conventional acceleration sensor, the area of the first fixed substrate 2 ′ sandwiched between the two fixed electrodes 2 ′ in the plan view is defined as an interval portion 7A ′ and is opposed to the interval portion 7A ′. When the region on the weight portion 13 ′ to be used is the interval facing portion 7B ′, the distance between the interval portion 7A ′ and the interval facing portion 7B is close.

  As a result, when the first fixed substrate 2 ′ and the weight portion 13 ′ are charged, there is a possibility that the weight portion 13 ′ is displaced due to an electrostatic force between them and comes into contact with the first fixed substrate 2 ′. . For example, when the first fixed substrate 2 ′ and the frame portion 11 ′ are directly bonded by anodic bonding, a large electrostatic force is applied so that the first fixed substrate 2 ′ and the weight portion 13 ′ come into contact with each other with a strong force, and both are fixed. As a result, characteristic abnormalities occur.

  This invention is made | formed in view of the said situation, The objective is to provide the acceleration sensor in which the movable part of an acceleration sensor is hard to contact an opposing part.

  The acceleration sensor according to the present invention includes a main body and a first fixed substrate formed on one surface of the main body, and the main body is a box-shaped frame body having an opening on the one surface and a movable body positioned inside the frame body. The movable body portion is provided so as to be rotatable about a pair of beams that connect both sides of the movable body portion and the inside of the frame body portion. A movable electrode is provided on the first fixed substrate side, and the first and second fixed electrodes are disposed on both sides of the first fixed substrate on both sides of the rotation shaft in plan view. An area of the first fixed substrate sandwiched between the first fixed electrode and the second fixed electrode in the plan view is provided as an interval portion, and is opposed to the interval portion in plan view. In the case where the region of the movable body portion to be used is the interval facing portion, the interval portion and the interval Wherein the provision of the recess in at least one countercurrent part.

  Moreover, it is preferable to form the said recessed part of this acceleration sensor in the said space | interval part by making said 1st fixed board | substrate thin.

  Moreover, it is preferable to form the said recessed part of this acceleration sensor in the said space | interval part by penetrating said 1st fixed board | substrate.

  Moreover, it is preferable to form the said recessed part of this acceleration sensor in the said space | interval part by thickening said 1st and 2nd fixed electrode.

  Moreover, it is preferable to form the said recessed part of this acceleration sensor in the said space | interval opposing part by depositing the movable thick layer which consists of an electroconductive member in the area | region on the said movable electrode other than the said space | interval opposing part in the said movable body part. .

  Moreover, it is preferable to form the said recessed part of this acceleration sensor in the said space | interval opposing part by making the said movable body part thin.

  The frame body portion of the acceleration sensor has a side wall portion and a bottom plate portion, and the bottom plate portion is formed of a second fixed substrate, and a dummy electrode is provided on the surface of the movable body portion on the second fixed substrate. It is preferable that the first fixed substrate and the second fixed substrate are provided directly on the side wall portion by anodic bonding, respectively.

  In the acceleration sensor of the present invention, the concave portion is provided in at least one of the interval portion and the interval opposing portion, so that the movable body portion is opposed to the fixed substrate even when the first fixed substrate and the movable body portion are charged. It is possible to make it difficult to make contact, and it is possible to realize a longer life and an improved yield.

The semiconductor microdevice of this-application Embodiment 1 is shown, (a) is a schematic exploded perspective view, (b) is a schematic sectional drawing. It is a general | schematic disassembled perspective view of a semiconductor microdevice same as the above. It is a description exploded perspective view of the acceleration sensor in the semiconductor microdevice same as the above. It is a general | schematic disassembled perspective view of the acceleration sensor in a semiconductor microdevice same as the above. The main part of the acceleration sensor in a semiconductor microdevice same as the above is shown, (a) is a schematic plan view, (b) is a schematic bottom view. FIG. 6 is a schematic cross-sectional view taken along line D-D ′ of FIG. 5A, showing an acceleration sensor in the semiconductor microdevice same as above. It is principal part explanatory drawing of a semiconductor microdevice same as the above. It is the schematic of the acceleration sensor in a semiconductor microdevice same as the above. It is the schematic of the acceleration sensor in the semiconductor microdevice of this-application Embodiment 2. FIG. It is the schematic of the acceleration sensor in the semiconductor microdevice of this-application Embodiment 3. FIG. It is the schematic of the acceleration sensor in the semiconductor microdevice of this-application Embodiment 4. It is the schematic of the acceleration sensor in the semiconductor microdevice of this-application Embodiment 5. FIG. 10 is a schematic exploded perspective view of an acceleration sensor in a semiconductor microdevice of Patent Document 1. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
1 to 8 show a semiconductor microdevice and an acceleration sensor according to the first embodiment.

  This semiconductor microdevice includes an acceleration sensor A having a main body 1 and a first fixed substrate 2 formed on one surface of the main body 1, and the main body 1 has a box-shaped frame portion 1a having an opening on the one surface and its side wall. The movable body 1b is rotatable about a pair of beams 1c that connect both sides of the movable body 1b and the inside of the side surface 1a of the frame. A movable electrode 6 is provided on the first fixed substrate 2 side of the movable body portion 1b, and the first fixed substrate 2 is on both sides of the rotation shaft in plan view. The first and second fixed electrodes 4A and 4B are provided in the portion so as to face the movable electrode 6, and the first fixed electrode 4A and the second fixed electrode 4B sandwiched between the first fixed electrode 4B and the first fixed electrode 4B in a plan view. The region of the fixed substrate 2 is the interval portion 7A, and the movable body is opposed to the interval portion 7A. In the case where the region of 1b was intervals facing portion 7B, recesses 8 are provided in the (interval facing portion 7B in this embodiment) at either one of the pitch area 7A and spacing opposed portion 7B.

  Further, the concave portion 8 of the acceleration sensor A is formed in the interval facing portion 7B by making the movable body portion 1b thin.

  The frame portion 1a of the acceleration sensor A has a side wall portion 1a1 and a bottom plate portion 1a2. The bottom plate portion 1a2 is formed of a second fixed substrate 3, and a dummy electrode 5 is formed on the second fixed substrate 3. Provided on the surface of the movable body 1a side, the first fixed substrate 2 and the second fixed substrate 3 are directly bonded to the side wall 1a1 by anodic bonding, respectively.

  Hereinafter, a more specific description of the first embodiment will be given.

  As shown in FIGS. 1 and 2, the semiconductor microdevice of this embodiment includes an acceleration sensor A composed of an acceleration sensor chip which is a kind of MEMS chip, and a surface-mount package 101 in which the acceleration sensor A is housed. I have.

  The package 101 is formed in a box shape in which one surface (the upper surface in FIG. 1B) is opened, and the outer leads 112b of a plurality of leads 112 that are electrically connected to the acceleration sensor A are hollow from the outer surface. The plastic package main body 102 and a package lid (lid) 103 that is airtightly bonded to the plastic package main body 102 so as to close the one surface of the plastic package main body 102. Note that a notation 113 indicating a product name, a manufacturing date and the like is formed at an appropriate portion of the package lid 103 by a laser marking technique.

  The acceleration sensor A is a capacitance type acceleration sensor chip, and as shown in FIGS. 3 to 6, is formed using a main body 1 formed using an SOI substrate which is a semiconductor substrate and a glass substrate. A first fixed substrate 2 fixed to the opening surface side (upper surface side in FIG. 6) of the frame body portion 1a and a bottom plate portion 1a2 of the frame body portion 1a using a glass substrate, and the surface opposite to the opening surface side. And a second fixed substrate 3 fixed to the side. Here, the outer peripheral shape of the main body 1 and each fixed substrate 2, 3 is rectangular, and each fixed substrate 2, 3 is formed to have the same outer dimensions as the main body 1. In this embodiment, an SOI substrate having an n-type silicon layer (active layer) on an insulating layer (buried oxide film) made of a silicon oxide film on a support substrate made of a silicon substrate is used as the semiconductor substrate. However, it is not limited to the SOI substrate, and for example, a silicon substrate may be used. Further, the frame portion 1a can be easily manufactured because the side wall portion 1a1 and the bottom plate portion 1a2 are separate members. For example, even if a single silicon substrate is hollowed out and formed integrally. Good.

  The main body 1 includes a side wall portion 1a1 in which two rectangular opening windows 14 in a plan view are arranged side by side along the one surface, and 2 μm from each fixed substrate 2 and 3 inside each opening window 14 of the side wall portion 1a1. Two movable bodies 1b having a rectangular shape in plan view, which are spaced apart from each other, and movable bodies 1b are arranged inside each opening window 14 of the side wall 1a1, and movable with the side walls 1a1 on the one surface side. Each pair of beams 1c connected to the body portion 1b is provided, and the side wall portions 1a1 are joined to the fixed substrates 2 and 3, respectively. In the acceleration sensor A, the peripheral portion of the side wall portion 1a1 is joined to the peripheral portions of the fixed substrates 2 and 3 over the entire periphery, and the side wall portion 1a1 and the fixed substrates 2 and 3 are connected to the chip size package. Is configured.

  By the way, in the side wall 1a1 of the main body 1, a rectangular window hole 15 in plan view communicating with each of the respective opening windows 14 is juxtaposed in the same direction as the two opening windows 14. Each of the two stators 16 is disposed along the parallel direction of the pair of beams 1c.

  A gap is formed between each stator 16 and the inner peripheral surface of the window hole 15, between the outer peripheral surface of the movable body portion 1 b, and between the adjacent stators 16. It is electrically insulated and is also electrically insulated from the side wall 1a1. Here, each stator 16 is joined to both fixed substrates 2 and 3. In addition, on the one surface side of the main body 1, each stator 16 is formed with a circular pad 18 made of a metal thin film (for example, an Al—Si film), and between the adjacent window holes 15 in the side wall 1 a 1. A circular pad 18 made of a metal thin film (for example, an Al—Si film) is also formed in this part.

  The first fixed substrate 2 is formed with a plurality of (here, five) tapered through holes 17 that expose the pads 18 separately. Here, in the first fixed substrate 2, each through hole 17 is formed in a tapered shape in which the opening area gradually increases as the distance from the main body 1 increases, and the first fixed substrate 2 is separated from the outer peripheral edge of each pad 18 in the main body 1. The opening area is set so that the peripheral part of each through-hole 17 is joined to each part. The acceleration sensor A in this embodiment is a capacitance type acceleration sensor chip, and each pad 18 formed on each stator 16 is electrically connected to each fixed electrode 4 described later and formed on the side wall 1a1. The pad 18 is electrically connected to each movable electrode 6 described later. The plurality of pads 18 described above are arranged along one side of the rectangular outer peripheral shape of the acceleration sensor A. In the acceleration sensor A, each pad 18 is arranged along one side of the outer peripheral shape of the rectangular shape of the acceleration sensor A on the surface of the first fixed substrate 2 opposite to the main body 1 side. You may make it electrically connect with each fixed electrode 4 and each movable electrode 6 by wiring. Here, as shown in FIG. 3, the region of the first fixed substrate 2 sandwiched between the fixed electrodes 4A and 4B in plan view is defined as a spacing portion 7A, and the region of the movable body portion 1b facing this is defined as a spacing facing portion 7B. It is as.

  Hereinafter, as in the orthogonal coordinate system shown on the left side of FIG. 3, the direction in which the movable body portions 1 b are arranged is the y-axis direction, and the direction orthogonal to the y-axis direction in the plane along the one surface of the main body 1 is the x-axis direction. The direction orthogonal to the x-axis direction and the y-axis direction (that is, the thickness direction of the main body 1) will be described as the z-axis direction.

  Each beam 1c in the acceleration sensor A serves as a torsion spring (torsion bar) capable of torsional deformation, and is formed thinner than the side wall portion 1a1 and the movable body portion 1b. It can be displaced around the pair of beams 1c with respect to the portion 1a1 (can be rotated around an axis in the y-axis direction). In other words, the pair of beams 1c connect the side wall 1a1 and the movable body 1b so that the movable body 1b can swing with respect to the side wall 1a1. In other words, the movable body portion 1b disposed inside the opening window 14 of the side wall portion 1a1 is swingable to the side wall portion 1a1 via two beams 1c extending in two opposite directions from the movable body portion 1b. It is supported by. Here, the side wall portion 1a1 is formed using a support substrate, an insulating layer, and a silicon layer of an SOI substrate. On the other hand, the beam 1c is formed using a silicon layer in the SOI substrate and is thinner than the side wall 1a1. In addition, the movable body portion 1b is formed using a support substrate 1ba, an insulating layer 1bb, and a silicon layer 1bc, which are SOI substrates. The main body 1 of the acceleration sensor A is formed using a bulk micromachining technique or the like. Further, the silicon layer 1bc constitutes the movable electrode 6. Each stator 16 is separated from the side wall 1a1 after appropriately processing the SOI substrate and bonding the SOI substrate to the second fixed substrate 3 by anodic bonding.

The movable body portion 1b and the first fixed substrate 2 are provided with a stopper portion 11 that restricts excessive displacement of the movable body portion 1b by SiO ₂ that is an insulating material (see FIG. 6). Thereby, it is possible to prevent the beam 1c from being damaged or the fixed substrates 2 and 3 from being damaged due to excessive displacement of the movable body 1b.

Moreover, in order to ensure the space for the movable body part 1b to displace to the 1st fixed board | substrate 2 side joined to the said one surface side of the main body 1, the movable body part 1b is composed of the support substrate 1ba, the silicon layer. Each 1bc surface is formed thin by etching by a depth of 2.2 μm. The first and second fixed substrates 2 and 3 may be etched thinly without reducing the thickness of each of these parts, and a process that facilitates formation of the recesses 8 is adopted as will be described later. It is preferable.
In the present embodiment, since the acceleration sensor A is formed using an SOI substrate, the accuracy of the thickness dimension of each beam 1c can be increased as compared with the case where the acceleration sensor A is formed using a silicon substrate.

  Here, the structure of the recess 8 will be described in detail with reference to FIGS.

The concave portion 8 is formed by making the interval facing portion 7B in the movable body portion 1b thin on the entire surface. In the present embodiment, a region of 800 × 40 μm ² is removed by etching by a depth of 11 μm from the interval facing portion 7B (area 1000 × 40 μm ² ) on the surface of the movable body 1b on the first fixed substrate 2 side. Note that, when the insulating layer 1bb of the SOI substrate is used as an etching stopper, manufacturing can be facilitated. Therefore, it is preferable to set the thickness of the silicon layer 1bc in advance according to the depth of the recess 8.

  In addition, when etching the support substrate 1ba and the silicon layer 1bc, it is possible to provide the recesses 8 together, so that the number of processes is not increased and the manufacturing can be easily performed.

  If the concave portion 8 is not provided, for example, the distance L between the first and second fixed electrodes 4A and 4B formed in the interval portion 7A on the surface of the first fixed substrate 2 as shown in FIG. The width D is 1000 μm, the distance between the spacing portion 7A of the first fixed substrate 2 and the spacing facing portion 7B of the movable body portion 1b is 2.2 μm, and the distance between the fixed electrodes 4A and 4B and the movable electrode 6 is 2.0 μm. In some cases, when the side wall portion 1a1 and the first fixed substrate 2 are anodically bonded at a voltage of 600V, a suction force of about 16 mN is generated in the movable body portion 1b. On the other hand, the width of the beam 1c connecting the side wall 1a1 and the movable body 1b is 12 μm, the thickness is 11 μm, the length is 150 μm, and the height of the stopper formed on the movable body 1b is 1.1 μm. In some cases, the spring reaction force when the side wall 1a1 is sucked by 0.9 μm is 3.6 mN, and the suction force exceeds the spring reaction force and may be fixed.

  On the other hand, by providing the concave portion 8 of the present embodiment, for example, the suction force when the anodic bonding is performed can be reduced to 3.5 mN, the spring reaction force can exceed the suction force, and is movable. It is possible to prevent the body part 1b from sticking or from causing poor bonding.

In addition, since the effect of this invention becomes so remarkable that the value of the area by the planar view of the recessed part 8 and depth is large, you may set the depth of the recessed part 8 to the value which penetrates the movable body part 1b, for example. The recess 8 may be formed by etching away an area larger than the 800 × 40 μm ² region etched away in the present embodiment. On the other hand, as a matter of course, since the mechanical strength of the movable body portion 1b decreases when the concave portion 8 becomes large, the shape of the concave portion 8 should be appropriately set in relation to the spring reaction force.

  Further, here, in the semiconductor microdevice of the present embodiment, the IC chip B including the chip inspection unit 10 including the bias unit 9 that applies an electrostatic field sufficient to bring each stopper unit 11 of the acceleration sensor A into contact is provided. It is housed in the package 101 together with the acceleration sensor A. Note that this embodiment is merely an example, and the chip inspection unit 10 may be configured without using the bias unit 9. Moreover, when performing chip | tip inspection at the time of manufacture, the chip | tip inspection part 10 does not necessarily need to have.

  The IC chip B is an ASIC (Application Specific IC) and is formed using a silicon substrate, and the entire back surface is bonded using a silicone-based resin. The IC chip B is also formed with a signal processing circuit for processing the output signal of the acceleration sensor A. The function of the IC chip B may be designed as appropriate according to the function of the acceleration sensor A, and may be any one that cooperates with the acceleration sensor A. Further, the IC chip B is not necessarily housed in the same package 101 as the acceleration sensor A. In this case, the other end of the bonding wire W whose one end is connected to each pad 18 of the acceleration sensor A is used. What is necessary is just to connect to the inner lead 112a of the lead 112 of the plus package main body 102. However, when the IC chip B is housed in the same package 101 as the acceleration sensor A, the entire semiconductor microdevice can be reduced in size and cost and the acceleration detection accuracy can be improved as compared with the case where the IC chip B is housed in a different package. Can be planned.

  In this embodiment, the IC chip B is formed using a single silicon substrate, whereas the acceleration sensor A is formed using an SOI substrate and two glass substrates. Since the thickness is larger than the thickness of the IC chip B, the mounting surface on which the acceleration sensor A is mounted is recessed from the mounting portion of the IC chip B at the bottom of the plastic package main body 102 (accordingly, acceleration). The part where the sensor A is mounted is thinner at the bottom than the other parts). In this embodiment, the outer shape of the plastic package main body 102 is a rectangular parallelepiped of 10 mm × 7 mm × 3 mm. However, this numerical value is an example, and the external shape of the acceleration sensor A and the IC chip B, the number and the pitch of the leads 112, etc. What is necessary is just to set suitably according to.

  As can be seen from the above description, the acceleration sensor A in the present embodiment is connected to the side wall portion 1a1 through a pair of beams 1c extending along the y-axis direction, and the first fixed portion. In the substrate 2, two fixed electrodes 4 made of a metal thin film (for example, an Al—Si film) are arranged in parallel along the x-axis direction for each portion facing each movable body portion 1 b, and each movable body portion. A movable electrode 6 made of a silicon layer 1bc is provided on 1b, and a gap is formed between the pair of the movable electrode 6 and the fixed electrode 4 that are opposed to each other in the z-axis direction. Here, each pair of beams 1c is formed on an extension of the center line along the y-axis direction of the movable body portion 1b in plan view.

  Further, the movable body portion 1b of the main body 1 is on both sides in the x-axis direction on the center line in the y-axis direction of the movable body portion 1b on the other surface side (here, coincides with a straight line connecting the pair of beams 1c). Space portions 12 and 13 which are opened in a rectangular shape and have different sizes are formed, and their masses are different from each other even though the planar sizes are the same on both sides. The main body 1 has an X-shaped reinforcing wall 19 along two diagonal lines of the rectangular inner bottom surface of the space portion 13 in the space portion 13 having a large opening size in the movable body portion 1b. The inner bottom surface and the inner side surface are formed in a continuous form. Further, in the main body 1, with respect to the two movable body portions 1 b disposed in the adjacent open windows 14, one movable body portion 1 b is in the plane along the one surface of the main body 1 and the other movable body portion 1 b. Is rotated 180 °.

  As can be seen from the above description, the acceleration sensor A has two structures having a pair of movable electrode 6 and fixed electrode 4. Therefore, there are four pairs of the movable electrode 6 provided on the main body 1 and the fixed electrode 4 provided on the first fixed substrate 2, and a variable capacitance capacitor is provided for each pair of the movable electrode 6 and the fixed electrode 4. Is configured. In short, in the acceleration sensor A, the distance between the fixed electrode 4 and the movable electrode 6 that make a pair and the area of the opposing portion change as the movable body portion 1b swings, and the capacitance of the variable capacitor changes. .

According to the present embodiment, since the recess 8 is provided in at least one of the spacing portion 7A and the spacing facing portion 7B (the spacing facing portion 7B in the present embodiment), the first fixed substrate 2 and the movable body portion are provided. Even if 1b is charged, it becomes difficult to apply electrostatic force, and the movable body portion 1b can hardly contact the opposing first fixed substrate 2, thereby realizing a longer life and an improved yield. it can. Moreover, since the recessed part 8 is formed in the space | interval opposing part 7B by making the movable body part 1b thin, it can be easily manufactured, without causing the increase in the number of processes. Further, since the first fixed substrate 2 and the second fixed substrate 3 are directly bonded to the side wall portion 1a1 by anodic bonding, respectively, they can be manufactured particularly easily.
(Embodiment 2)
FIG. 9 shows an acceleration sensor of a semiconductor microdevice according to the second embodiment.

  In the recess 8 of the semiconductor microdevice and the acceleration sensor, the movable body portion 1b is formed in the interval facing portion 7B by depositing a movable thick layer 6A made of a conductive member in a region on the movable electrode 6 other than the interval facing portion 7B. In this respect, the semiconductor microdevice and the acceleration sensor described in the first embodiment are different from each other, but the other configurations are the same.

  Here, the structure of the recess 8 will be described in detail with reference to FIG.

In the present embodiment, a conductive material (for example, Poly-Si) having a thickness of 2.1 μm is formed on the surface of the movable body portion 1b on the first fixed substrate 2 side, in addition to the centrally opposed portion 7B (area 1000 × 40 μm ² ). A movable thick layer 6A made of a metal such as Al, Cu, or Ni is deposited to form a variable capacitor by the movable thick layer 6A and the fixed electrode 4.

  Thus, the concave portion 8 is formed by using the movable thick layer 6A provided in a region other than the interval facing portion 7B in the movable body portion 1b as a side wall and using the surface of the silicon layer 1bc of the movable body portion 1b as a bottom surface. Is formed at a position relatively far from the first fixed substrate 2 relative to the surface of the surrounding movable body portion 1b, so that the movable body portion 1b having the movable electrode 6 while maintaining the electric capacity of the variable capacitor. Can be separated from the first fixed substrate 2 having the fixed electrode 4 according to the thickness of the movable thick layer 6A.

  In the present embodiment, the distance between the opposed portion 7B between the first fixed substrate 2 and the movable body portion 1b is 4.3 μm, and the concave portion 8 can be provided without using etching on the movable body portion 1b. For example, even when 600 V is applied during anodic bonding as in the first embodiment, the suction force can be reduced to 3.4 mN, and the spring reaction force can exceed the suction force, so that the movable body portion 1b can be fixed. It is possible to prevent defective bonding.

  Moreover, since the mass of the whole movable body part 1b can be increased, the acceleration detection capability is further improved.

According to the present embodiment, since the concave portion 8 is formed in the interval facing portion 7B by depositing the movable thick layer 6A made of a conductive member in a region on the movable electrode 6 other than the interval facing portion 7B, acceleration is performed. The detection ability can be improved.
(Embodiment 3)
FIG. 10 shows a semiconductor microdevice and an acceleration sensor according to the third embodiment.

  The recesses 8 of the semiconductor microdevice and acceleration sensor are different from the semiconductor microdevice and acceleration sensor described in the first embodiment in that the first fixed substrate 2 is thinned and formed in the spacing portion 7A. Other configurations are the same.

  Here, the structure of the recess 8 will be described in detail with reference to FIG.

In the present embodiment, a portion (area) that overlaps the movable body portion 1b in plan view among the spacing portions 7A that are regions on the first fixed substrate 2 sandwiched between the first and second fixed electrodes 4A and 4B. 1000 × 40 μm ² ) is removed by etching at a depth of 2.3 μm.

  Accordingly, the recess 8 is formed in the first fixed substrate 2 and the interval portion 7A is formed thinner than the surrounding first fixed substrate 2 surface, so that the electric capacity of the variable capacitor is maintained, The movable body portion 1 b having the movable electrode 6 can be separated according to the depth removed by etching from the spacing portion 7 A of the first fixed substrate 2 having the fixed electrode 4.

  In the present embodiment, the distance between the facing portion 7A of the first fixed substrate 2 and the movable body portion 1b is separated by 4.3 μm. For example, as in the first embodiment, even if 600 V is applied during anodic bonding, suction force is applied. Can be reduced to 3.4 mN, and the spring reaction force can exceed the suction force, so that it is possible to prevent the movable body portion 1b from being fixed and from being poorly joined.

  In the case of the present embodiment, in order to secure a space for the movable body 1b to be displaced toward the first fixed substrate 2 joined to the one surface side of the main body 1, the movable body 1b When the first and second fixed substrates 2 and 3 are formed to be thin by etching without reducing the thickness of the surfaces of the support substrate 1ba and the silicon layer 1bc, the recesses 8 can be formed together. . This is particularly effective when it is desired to avoid a decrease in acceleration detection capability due to a decrease in the mass of the entire movable body portion 1b due to etching.

According to the present embodiment, since the concave portion 8 is formed in the interval portion 7A by making the first fixed substrate 2 thin, it is possible to avoid a decrease in acceleration detection capability.
(Embodiment 4)
FIG. 11 shows a semiconductor microdevice and an acceleration sensor according to the fourth embodiment.

  The recess 8 of the semiconductor microdevice and the acceleration sensor is different from the semiconductor microdevice and the acceleration sensor described in the first embodiment in that the recess 8 of the semiconductor microdevice and the acceleration sensor is formed in the interval portion 7A by penetrating the first fixed substrate 2. The configuration of is the same.

  Here, the structure of the recess 8 will be described in detail with reference to FIG.

In the present embodiment, a portion (area) that overlaps the movable body portion 1b in plan view among the spacing portions 7A that are regions on the first fixed substrate 2 sandwiched between the first and second fixed electrodes 4A and 4B. 1000 × 40 μm ² ) is removed by etching.

  Accordingly, since the recess 8 is formed so as to penetrate the first fixed substrate 2, the movable body portion 1 b having the movable electrode 6 is replaced with the first electrode having the fixed electrode 4 while maintaining the electric capacity of the variable capacitor. The fixed substrate 2 can be separated from the spacing portion 7A of the fixed substrate 2 almost completely.

  Since the present embodiment has a structure in which almost no suction force is generated, for example, as in Embodiment 1, even when 600 V is applied during anodic bonding, the suction force does not substantially occur, and sticking due to electrostatic force can be substantially prevented. As a result, even when the spring reaction force of the beam 1c is extremely low, it is possible to make it difficult for the movable body portion 1b to be fixed, and to further improve the acceleration detection capability. In addition, it becomes possible to make the inside airtight by sealing the concave portion 8 of the present embodiment with a package or the like.

According to the present embodiment, since the concave portion 8 is formed in the gap portion 7A by penetrating the first fixed substrate 2, the electrostatic force is almost equal even if the first fixed substrate 2 and the movable body portion 1b are charged. It is possible to make the structure not added, and it is possible to make it difficult for the movable body portion 1b to contact the opposing first fixed substrate 2, and it is possible to particularly improve the yield rate.
(Embodiment 5)
FIG. 12 shows a semiconductor microdevice and an acceleration sensor according to the fifth embodiment.

  The recess 8 of the semiconductor microdevice and acceleration sensor is formed in the spacing portion 7A by making the first and second fixed electrodes 4A and 4B thick, and the semiconductor microdevice described in the first embodiment and Although it is different from the acceleration sensor, other configurations are the same.

  Here, the structure of the recess 8 will be described in detail with reference to FIG.

  In the present embodiment, the thickness of the first and second fixed electrodes 4A and 4B provided on the first fixed substrate 2 is increased to have a thickness of 2.3 μm.

  Groove-shaped recesses having a depth of 2.3 μm and a width of 40 μm are formed using the first and second fixed electrodes 4A and 4B as side walls.

  As a result, the distance facing portion 7B of the movable body portion 1b having the movable electrode 6 is changed from the first fixed substrate 2 having the fixed electrode 4 to the first and second fixed electrodes 4A while maintaining the electric capacity of the variable capacitor. , 4B can be separated according to the thickness.

  In the present embodiment, the distance between the facing portion 7A of the first fixed substrate 2 and the movable body portion 1b is separated by 4.3 μm. For example, as in the first embodiment, even if 600 V is applied at the time of anodic bonding, the suction force is maintained. Since it can be reduced to 3.4 mN and the spring reaction force can exceed the suction force, it is possible to prevent the movable body portion 1b from being fixed and from being poorly joined.

  In the case of the present embodiment, when the first and second fixed electrodes 4A and 4B are provided, the first and second fixed electrodes 4A and 4B can be provided only by controlling the deposition amount of the metal film, so that the number of processes is not increased and manufacturing is easy. In addition, since there is no need to provide a separate member, the number of members can be reduced.

  According to this embodiment, since the recessed part 8 is formed in the space | interval part 7A by making 1st and 2nd fixed electrode 4A, 4B thick, it can be manufactured easily.

A Acceleration sensor 1 Main body 1a Frame part 1a1 Side wall part 1a2 Bottom plate part 1b Movable body part 1c Beam 2 First fixed board 3 Second fixed board 4A First fixed electrode 4B Second fixed electrode 5 Dummy electrode 6 Movable Electrode 6A Movable thick layer 7A Spacing part 7B Spacing facing part 8 Recess 9 Bias unit 10 Chip inspection part B IC chip 101 Package

Claims (7)

The body,
A first fixed substrate formed on one surface of the main body,
The main body has a box-shaped frame body portion whose one surface is open and a movable body portion located inside the frame body portion,
The movable body portion is provided to be rotatable about a pair of beams that connect both sides of the movable body portion and the inside of the frame body portion,
A movable electrode is provided on the first fixed substrate side of the movable body portion,
The first fixed substrate is provided with first and second fixed electrodes so as to face the movable electrode on both sides of the rotating shaft in plan view.
In the plan view, the region of the first fixed substrate sandwiched between the first fixed electrode and the second fixed electrode as an interval portion,
In the case where the region of the movable body portion facing the spacing portion is a spacing facing portion,
An acceleration sensor, wherein a recess is provided in at least one of the spacing portion and the spacing facing portion.   The acceleration sensor according to claim 1, wherein the recess is formed in the space portion by thinning the first fixed substrate.   The acceleration sensor according to claim 1, wherein the concave portion is formed in the gap portion by penetrating the first fixed substrate.   The acceleration sensor according to any one of claims 1 to 3, wherein the recess is formed in the space portion by thickening the first and second fixed electrodes.   The concave portion is formed in the interval facing portion by depositing a movable thick layer made of a conductive member in a region on the movable electrode other than the interval facing portion in the movable body portion. 2. The acceleration sensor according to 1.   The acceleration sensor according to claim 1, wherein the concave portion is formed in the interval facing portion by thinning the movable body portion. The frame body portion has a side wall portion and a bottom plate portion,
The bottom plate portion is formed of a second fixed substrate,
A dummy electrode is provided on the surface of the movable body portion on the second fixed substrate, and the first fixed substrate and the second fixed substrate are directly bonded to the side wall portion by anodic bonding, respectively. The acceleration sensor as described in any one of Claims 1-6.

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