JP2010210423A - Acceleration sensor - Google Patents

Acceleration sensor Download PDF

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JP2010210423A
JP2010210423A JP2009056948A JP2009056948A JP2010210423A JP 2010210423 A JP2010210423 A JP 2010210423A JP 2009056948 A JP2009056948 A JP 2009056948A JP 2009056948 A JP2009056948 A JP 2009056948A JP 2010210423 A JP2010210423 A JP 2010210423A
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electrode
acceleration
weight
portions
fixed
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Hideki Ueda
英喜 上田
Nobuyuki Ibara
伸行 茨
Hitoshi Yoshida
仁 吉田
Masafumi Okada
全史 岡田
Takashi Mori
岳志 森
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Panasonic Electric Works Co Ltd
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Panasonic Electric Works Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily-miniaturizable acceleration sensor. <P>SOLUTION: An electrode block 8 made of a silicon substrate is bonded onto the under surface of an upper cover 2a. The electrode block 8 includes a frame part 80 bonded to a frame part 3 of a sensor chip 1, and first and second fixed electrodes 81a, 81b, 82a, 82b. The first and second fixed electrodes 81a, 81b, 82a, 82b exposed to the upper surface side of the upper cover 2a through a through-hole 20 are used as electrode parts 83a, 83b, 84a, 84b for taking out a detection voltage. Resultantly, an exclusive space for providing the electrode parts which has been necessary for a conventional example becomes unnecessary, to thereby achieve miniaturization easily. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、静電容量型の加速度センサに関するものである。   The present invention relates to a capacitance type acceleration sensor.

従来、図３に示すように可動電極を有する直方体形状の重り部１００と、重り部１００の長手方向における略中央において重り部１００を回動自在に支持する一対のビーム部１０１と、一対のビーム部１０１を結ぶ直線（ビーム軸）を境界線とした重り部１００の表面のそれぞれ一方側及び他方側に対し所定距離をあけて対向配置された第１及び第２の固定電極１０２，１０３とを備える加速度センサが知られている。この加速度センサは、ビーム軸を回動軸とした重り部１００の回動に伴う可動電極（重り部１００の固定電極１０２，１０３との対向部位）と第１および第２の固定電極１０２，１０３間の静電容量の変化を差動検出することにより、重り部１００に印加された加速度を検出する。このような加速度センサでは、加速度が印加された際にビーム軸を回動軸としたモーメントが重り部１００に発生するように、重り部１００の裏面のビーム軸を境界線とした一方側（図３における右側）に凹部１０４を形成することにより、ビーム軸を境界線とした重り部１００の一方側（右側）と他方側（左側）とで重量が異なるようにしている（例えば、特許文献１参照）。   Conventionally, as shown in FIG. 3, a rectangular parallelepiped weight portion 100 having a movable electrode, a pair of beam portions 101 that rotatably supports the weight portion 100 at a substantially center in the longitudinal direction of the weight portion 100, and a pair of beams First and second fixed electrodes 102 and 103 arranged to face each other on the one side and the other side of the weight part 100 with a straight line (beam axis) connecting the parts 101 as a boundary line. An acceleration sensor provided is known. This acceleration sensor includes a movable electrode (a portion facing the fixed electrodes 102 and 103 of the weight portion 100) and the first and second fixed electrodes 102 and 103 that accompany the rotation of the weight portion 100 about the beam axis. The acceleration applied to the weight part 100 is detected by differentially detecting the change in capacitance between the two. In such an acceleration sensor, when the acceleration is applied, a moment with the beam axis as the rotation axis is generated in the weight portion 100, so that the beam axis on the back surface of the weight portion 100 is used as one boundary (see FIG. 3 is formed on the one side (right side) and the other side (left side) of the weight part 100 with the beam axis as a boundary line (for example, Patent Document 1). reference).

尚、この種の静電容量型の加速度センサでは、固定電極から検出電圧を取り出すために、固定電極と電気的に接続された検出電極がビーム部を支持する枠部に設けられている（例えば、特許文献２参照）。   In this type of capacitance type acceleration sensor, in order to extract a detection voltage from the fixed electrode, a detection electrode electrically connected to the fixed electrode is provided on a frame portion that supports the beam portion (for example, , See Patent Document 2).

特表２００８−５４４２４３号公報Special table 2008-544243 gazette 特開２００４−２８９１２号公報JP 2004-28912 A

しかしながら、上述した従来例においては検出電極を設けるためのスペースが枠部に必要であるから、小型化が困難になるという問題があった。   However, in the above-described conventional example, there is a problem that it is difficult to reduce the size because a space for providing the detection electrode is required in the frame portion.

本発明は上記事情に鑑みて為されたものであり、その目的は、小型化が容易な加速度センサを提供することにある。   The present invention has been made in view of the above circumstances, and an object thereof is to provide an acceleration sensor that can be easily downsized.

請求項１の発明は、上記目的を達成するために、一面に可動電極が設けられた重り部並びに重り部を回動軸の回りに回動自在に支持するビーム部が半導体基板を加工して形成されたセンサチップと、半導体基板からなる固定電極が一面に設けられ当該固定電極を可動電極に対向させる向きでセンサチップの一面側に接合される絶縁性のカバーと、カバーを貫通する貫通孔と、貫通孔を通してカバーの外に露出する固定電極からなる電極部とを備えたことを特徴とする。   In order to achieve the above object, the invention according to claim 1 is characterized in that a weight part provided with a movable electrode on one surface and a beam part for rotatably supporting the weight part around a rotation axis are formed on a semiconductor substrate. A formed sensor chip, an insulating cover that is provided on one surface with a fixed electrode made of a semiconductor substrate and is bonded to the one surface side of the sensor chip in a direction facing the movable electrode, and a through-hole that penetrates the cover And an electrode portion formed of a fixed electrode exposed to the outside of the cover through the through hole.

請求項１の発明によれば、検出電圧を取り出すための電極部を固定電極で兼用しているので、従来例のように電極部を設けるための専用のスペースが不要となって容易に小型化が図れる。   According to the first aspect of the present invention, since the electrode part for taking out the detection voltage is also used as the fixed electrode, a dedicated space for providing the electrode part as in the conventional example is not required, and the size can be easily reduced. Can be planned.

請求項１の発明によれば、小型化が容易となる。   According to the invention of claim 1, miniaturization is facilitated.

本発明の実施形態を示し、（ａ）は平面図、（ｂ）は断面図である。The embodiment of the present invention is shown, (a) is a top view and (b) is a sectional view. （ａ）〜（ｄ）は同上の製造方法を説明するための断面図である。(A)-(d) is sectional drawing for demonstrating the manufacturing method same as the above. 従来例を示し、（ａ）は断面図、（ｂ）は平面図である。A prior art example is shown, (a) is a sectional view and (b) is a plan view.

以下、図面を参照して本発明の実施形態を詳細に説明する。但し、以下の説明では図１におけるｘ軸方向を縦方向、ｙ軸方向を横方向、ｚ軸方向を上下方向と定める。   Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, in the following description, the x-axis direction in FIG. 1 is defined as the vertical direction, the y-axis direction is defined as the horizontal direction, and the z-axis direction is defined as the vertical direction.

本実施形態は、図１に示すように外形が矩形平板状であるセンサチップ１と、センサチップ１の上面側に固定される上カバー２ａと、センサチップ１の下面側に固定される下カバー２ｂとを備えている。センサチップ１は、上下方向から見て矩形の２つの枠部３ａ，３ｂが長手方向（横方向）に並設されたフレーム部３と、枠部３ａ，３ｂの内周面に対して隙間を空けた状態で枠部３ａ，３ｂ内に配置された直方体形状の重り部４，５と、枠部３ａ，３ｂの内周面と重り部４，５の側面を連結してフレーム部３に対して重り部４，５を回動軸の回りに回動自在に支持する各一対のビーム部６ａ，６ｂ及び７ａ，７ｂと、重り部４，５の上面に形成される可動電極４ａ，５ａとを備えている。   In the present embodiment, as shown in FIG. 1, the sensor chip 1 whose outer shape is a rectangular flat plate, the upper cover 2 a fixed to the upper surface side of the sensor chip 1, and the lower cover fixed to the lower surface side of the sensor chip 1 2b. The sensor chip 1 has a gap with respect to the frame part 3 in which two rectangular frame parts 3a and 3b viewed in the vertical direction are arranged in the longitudinal direction (lateral direction) and the inner peripheral surface of the frame parts 3a and 3b. The rectangular parallelepiped weight parts 4 and 5 arranged in the frame parts 3a and 3b in the opened state, the inner peripheral surface of the frame parts 3a and 3b and the side surfaces of the weight parts 4 and 5 are connected to the frame part 3 And a pair of beam portions 6a, 6b and 7a, 7b that support the weight portions 4, 5 so as to be rotatable about a rotation axis, and movable electrodes 4a, 5a formed on the upper surfaces of the weight portions 4, 5. It has.

一対のビーム部６ａ，６ｂは、横方向に対向する枠部３ａの内周面における縦方向の中央部に一端が連結され、重り部４の側面における凹部１１と充実部１２の境界付近に他端が連結されている。同じく一対のビーム部７ａ，７ｂは、横方向に対向する枠部３ｂの内周面における縦方向の中央部に一端が連結され、重り部５の側面における凹部１３と充実部１４の境界付近に他端が連結されている。つまり、一対のビーム部６ａと６ｂ、７ａと７ｂをそれぞれ結ぶ直線が回動軸となり、回動軸の回りに各重り部４，５が回動することになる。   One end of the pair of beam portions 6a and 6b is connected to the central portion in the vertical direction on the inner peripheral surface of the frame portion 3a facing in the horizontal direction, and the other is near the boundary between the concave portion 11 and the solid portion 12 on the side surface of the weight portion 4. The ends are connected. Similarly, one pair of beam portions 7a and 7b is connected at one end to the longitudinal center portion of the inner peripheral surface of the frame portion 3b facing in the lateral direction, and near the boundary between the concave portion 13 and the solid portion 14 on the side surface of the weight portion 5. The other end is connected. That is, a straight line connecting the pair of beam portions 6a and 6b and 7a and 7b serves as a rotation shaft, and the weight portions 4 and 5 rotate around the rotation shaft.

重り部４，５は、図１（ｂ）に示すように回動軸を境界とする一方側（重り部４では図１における右側、重り部５では図１における左側）に、一面（下面）に開口した凹部１１，１３が設けられ、他方側（重り部４では図１における左側、重り部５では図１における右側）に、充実部１２，１４が形成されている。尚、凹部１１，１３は開口面の法線方向（上下方向）から見て平面視四角形に形成されている。また、センサチップ１は、後述するように半導体の微細加工技術によりシリコン基板（シリコンＳＯＩ基板）を加工して形成されるものであり、重り部４，５の上面を含む部分が可動電極４ａ，５ａとなる。さらに、重り部４，５の上面及び下面における四隅には、重り部４，５が上カバー２ａ及び下カバー２ｂに直接衝突することを防止するために複数の突起部１５が突設されている。   As shown in FIG. 1B, the weight portions 4 and 5 are arranged on one side (the lower surface) on one side (the right side in FIG. 1 for the weight portion 4 and the left side in FIG. 1 for the weight portion 5) with the rotation axis as a boundary. On the other side (the weight portion 4 on the left side in FIG. 1 and the weight portion 5 on the right side in FIG. 1), the solid portions 12 and 14 are formed. In addition, the recessed parts 11 and 13 are formed in the planar view square shape seeing from the normal line direction (up-down direction) of the opening surface. The sensor chip 1 is formed by processing a silicon substrate (silicon SOI substrate) by a semiconductor microfabrication technique as will be described later, and the portions including the upper surfaces of the weight portions 4 and 5 are movable electrodes 4a, 5a. Further, at the four corners on the upper surface and the lower surface of the weight portions 4 and 5, a plurality of protrusions 15 are provided so as to prevent the weight portions 4 and 5 from directly colliding with the upper cover 2a and the lower cover 2b. .

下カバー２ｂは、石英ガラスなどの絶縁材料により縦横の寸法がフレーム部３の縦横の寸法と略同一である矩形平板状に形成され、フレーム部３の下面に接合される。   The lower cover 2 b is formed in a rectangular flat plate shape whose vertical and horizontal dimensions are substantially the same as the vertical and horizontal dimensions of the frame portion 3 by an insulating material such as quartz glass, and is joined to the lower surface of the frame portion 3.

上カバー２ａは、石英ガラスなどの絶縁材料製であって、上下方向に沿って重り部４，５の凹部１１，１３並びに充実部１２，１４と対向する位置に各々貫通孔２０が貫設されている。また、上カバー２ａの下面には、半導体基板（シリコン基板）からなる電極ブロック８が接合されている。   The upper cover 2a is made of an insulating material such as quartz glass, and through-holes 20 are respectively provided at positions facing the concave portions 11 and 13 and the solid portions 12 and 14 of the weight portions 4 and 5 along the vertical direction. ing. An electrode block 8 made of a semiconductor substrate (silicon substrate) is bonded to the lower surface of the upper cover 2a.

電極ブロック８は、センサチップ１のフレーム部３と同寸法及び同形状に形成された枠部８０と、一方の可動電極４ａ（重り部４）の凹部１１側と対向する第１の固定電極８１ａ及び充実部１２側と対向する第２の固定電極８１ｂと、他方の可動電極５ａ（重り部５）の凹部１１側と対向する第２の固定電極８２ａ及び充実部１２側と対向する第２の固定電極８２ｂとを有している。尚、電極ブロック８の第１及び第２の固定電極８１ａ，８１ｂ、８２ａ，８２ｂによって上カバー２ａの４つの貫通孔２０がそれぞれ閉塞されている。つまり、貫通孔２０を通して上カバー２ａの上面側に露出する第１及び第２の固定電極８１ａ，８１ｂ、８２ａ，８２ｂが検出電圧を取り出すための電極部８３ａ，８３ｂ、８４ａ，８４ｂとなる。尚、上カバー２ａの横方向の寸法はセンサチップ１並びに電極ブロック８と略同一であるが、縦方向の寸法はセンサチップ１並びに電極ブロック８よりも若干短くなっており、横方向に沿った一方の側面（図１における左側の側面）に揃えてフレーム部３の上面に接合される。そして、電極ブロック８上面の上カバー２ａで覆われない端部（図１における右端部）が可動電極４ａ，５ａと導通した接地用の電極部８５となる。   The electrode block 8 includes a frame portion 80 formed in the same size and shape as the frame portion 3 of the sensor chip 1 and a first fixed electrode 81a facing the concave portion 11 side of one movable electrode 4a (weight portion 4). And the second fixed electrode 81b facing the solid portion 12 side and the second fixed electrode 82a facing the concave portion 11 side of the other movable electrode 5a (weight portion 5) and the second fixed electrode facing the solid portion 12 side. And a fixed electrode 82b. The four through holes 20 of the upper cover 2a are respectively closed by the first and second fixed electrodes 81a, 81b, 82a, 82b of the electrode block 8. That is, the first and second fixed electrodes 81a, 81b, 82a, 82b exposed to the upper surface side of the upper cover 2a through the through holes 20 serve as electrode portions 83a, 83b, 84a, 84b for taking out the detection voltage. The horizontal dimension of the upper cover 2a is substantially the same as that of the sensor chip 1 and the electrode block 8, but the vertical dimension is slightly shorter than that of the sensor chip 1 and the electrode block 8 and is aligned along the horizontal direction. It is joined to the upper surface of the frame portion 3 so as to align with one side surface (the left side surface in FIG. 1). The end portion (the right end portion in FIG. 1) that is not covered by the upper cover 2a on the upper surface of the electrode block 8 becomes the ground electrode portion 85 that is electrically connected to the movable electrodes 4a and 5a.

ここで、本実施形態では、枠部３ａ、重り部４、ビーム部６ａ，６ｂ、可動電極４ａ、電極ブロック８と、枠部３ｂ、重り部５、ビーム部７ａ，７ｂ、可動電極５ａ、電極ブロック８とで各々加速度センサが構成され、重り部４，５の向き（凹部１１，１３と充実部１２，１４の配置）を１８０度反転させた状態で２つの加速度センサが一体に形成されている（図１（ａ）参照）。   Here, in this embodiment, the frame part 3a, the weight part 4, the beam parts 6a and 6b, the movable electrode 4a, the electrode block 8, the frame part 3b, the weight part 5, the beam parts 7a and 7b, the movable electrode 5a, and the electrode Each of the blocks 8 constitutes an acceleration sensor, and the two acceleration sensors are integrally formed with the directions of the weights 4 and 5 (arrangement of the recesses 11 and 13 and the enhancement parts 12 and 14) reversed 180 degrees. (See FIG. 1A).

次に、本実施形態の検出動作について説明する。   Next, the detection operation of this embodiment will be described.

まず、一方の重り部４にｘ軸方向の加速度が印加された場合を考える。ｘ軸方向に加速度が印加されると重り部４が回動軸の回りに回動して可動電極４ａと第１の固定電極８１ａ並びに第２の固定電極８１ｂとの間の距離が変化し、その結果、可動電極４ａと各固定電極８１ａ，８１ｂとの間の静電容量Ｃ１，Ｃ２も変化する。ここで、ｘ軸方向の加速度が印加されていないときの可動電極４ａと各固定電極８１ａ，８１ｂとの間の静電容量をＣ０とし、加速度の印加によって生じる静電容量の変化分をΔＣとすれば、ｘ軸方向の加速度が印加されたときの静電容量Ｃ１，Ｃ２は、
Ｃ１＝Ｃ０−ΔＣ …（１）
Ｃ２＝Ｃ０＋ΔＣ …（２）
と表すことができる。 First, consider a case where an acceleration in the x-axis direction is applied to one weight portion 4. When acceleration is applied in the x-axis direction, the weight portion 4 rotates around the rotation axis, and the distance between the movable electrode 4a and the first fixed electrode 81a and the second fixed electrode 81b changes. As a result, the capacitances C1 and C2 between the movable electrode 4a and the fixed electrodes 81a and 81b also change. Here, the capacitance between the movable electrode 4a and each of the fixed electrodes 81a and 81b when no acceleration in the x-axis direction is applied is C0, and the change in capacitance caused by the application of acceleration is ΔC. Then, the capacitances C1 and C2 when the acceleration in the x-axis direction is applied are
C1 = C0−ΔC (1)
C2 = C0 + ΔC (2)
It can be expressed as.

同様に、他方の重り部５にｘ軸方向の加速度が印加された場合、可動電極５ａと各固定電極８２ａ，８２ｂとの間の静電容量Ｃ３，Ｃ４は、
Ｃ３＝Ｃ０−ΔＣ …（３）
Ｃ４＝Ｃ０＋ΔＣ …（４）
と表すことができる。 Similarly, when acceleration in the x-axis direction is applied to the other weight portion 5, the capacitances C3 and C4 between the movable electrode 5a and the fixed electrodes 82a and 82b are:
C3 = C0−ΔC (3)
C4 = C0 + ΔC (4)
It can be expressed as.

ここで、静電容量Ｃ１〜Ｃ４の値は、電極部８０ａ，８０ｂ及び８１ａ，８１ｂから取り出す電圧信号を演算処理することで検出することができる。そして、一方の加速度センサから得られる静電容量Ｃ１，Ｃ２の差分値ＣＡ（＝Ｃ１−Ｃ２）と、他方の加速度センサから得られる静電容量Ｃ３，Ｃ４の差分値ＣＢ（＝Ｃ３−Ｃ４）との和（±４ΔＣ）を算出すれば、この差分値ＣＡ，ＣＢの和に基づいてｘ軸方向に印加された加速度の向きと大きさを演算することができる。   Here, the values of the electrostatic capacitances C1 to C4 can be detected by calculating voltage signals taken out from the electrode portions 80a and 80b and 81a and 81b. Then, the difference value CA (= C1-C2) between the capacitances C1, C2 obtained from one acceleration sensor and the difference value CB (= C3-C4) between the capacitances C3, C4 obtained from the other acceleration sensor. Is calculated (± 4ΔC), the direction and magnitude of the acceleration applied in the x-axis direction can be calculated based on the sum of the difference values CA and CB.

次に、一方の重り部４にｚ軸方向の加速度が印加された場合を考える。ｚ軸方向に加速度が印加されると重り部４が回動軸の回りに回動して可動電極４ａと第１の固定電極８１ａ並びに第２の固定電極８１ｂとの間の距離が変化し、その結果、可動電極４ａと各固定電極８１ａ，８１ｂとの間の静電容量Ｃ１，Ｃ２も変化する。ここで、ｚ軸方向の加速度が印加されていないときの可動電極４ａと各固定電極８１ａ，８１ｂとの間の静電容量をＣ０とし、加速度の印加によって生じる静電容量の変化分をΔＣとすれば、ｚ軸方向の加速度が印加されたときの静電容量Ｃ１，Ｃ２は、
Ｃ１＝Ｃ０＋ΔＣ …（５）
Ｃ２＝Ｃ０−ΔＣ …（６）
と表すことができる。 Next, consider a case where acceleration in the z-axis direction is applied to one weight portion 4. When acceleration is applied in the z-axis direction, the weight portion 4 rotates around the rotation axis, and the distance between the movable electrode 4a and the first fixed electrode 81a and the second fixed electrode 81b changes. As a result, the capacitances C1 and C2 between the movable electrode 4a and the fixed electrodes 81a and 81b also change. Here, the capacitance between the movable electrode 4a and the fixed electrodes 81a and 81b when no acceleration in the z-axis direction is applied is C0, and the change in capacitance caused by the application of acceleration is ΔC. Then, the capacitances C1 and C2 when the acceleration in the z-axis direction is applied are
C1 = C0 + ΔC (5)
C2 = C0−ΔC (6)
It can be expressed as.

同様に、他方の重り部５にｚ軸方向の加速度が印加された場合、可動電極５ａと各固定電極８２ａ，８２ｂとの間の静電容量Ｃ３，Ｃ４は、
Ｃ３＝Ｃ０−ΔＣ …（７）
Ｃ４＝Ｃ０＋ΔＣ …（８）
と表すことができる。 Similarly, when acceleration in the z-axis direction is applied to the other weight portion 5, the capacitances C3 and C4 between the movable electrode 5a and the fixed electrodes 82a and 82b are:
C3 = C0−ΔC (7)
C4 = C0 + ΔC (8)
It can be expressed as.

そして、一方の加速度センサから得られる静電容量Ｃ１，Ｃ２の差分値ＣＡ（＝Ｃ１−Ｃ２）と、他方の加速度センサから得られる静電容量Ｃ３，Ｃ４の差分値ＣＢ（＝Ｃ３−Ｃ４）との差（±４ΔＣ）を算出すれば、この差分値ＣＡ，ＣＢの差に基づいてｚ軸方向に印加された加速度の向きと大きさを演算することができる。尚、差分値ＣＡ，ＣＢの和と差に基づいてｘ軸方向及びｚ軸方向の加速度の向き及び大きさを求める演算処理については従来周知であるから詳細な説明を省略する。   Then, the difference value CA (= C1-C2) between the capacitances C1, C2 obtained from one acceleration sensor and the difference value CB (= C3-C4) between the capacitances C3, C4 obtained from the other acceleration sensor. Is calculated (± 4ΔC), the direction and magnitude of the acceleration applied in the z-axis direction can be calculated based on the difference between the difference values CA and CB. Since the calculation processing for obtaining the direction and magnitude of acceleration in the x-axis direction and the z-axis direction based on the sum and difference of the difference values CA and CB is well known in the art, detailed description thereof will be omitted.

次に、図２を参照して本実施形態の製造方法を説明する。   Next, the manufacturing method of this embodiment will be described with reference to FIG.

本実施形態では、支持基板及び中間酸化膜、活性層からなるシリコンＳＯＩ基板を半導体の微細加工技術を利用して加工することによりセンサチップ１が形成される。まず、シリコンＳＯＩ基板の両面にシリコン酸化膜やフォトレジスト膜などのマスク材料を形成し、重り部４，５に対応する位置のマスク材料を除去した後、ＴＭＡＨ（テトラメチル水酸化アンモニウム溶液）やＫＯＨ（水酸化カリウム溶液）などを利用した湿式エッチング、あるいは反応性イオンエッチング（ＲＩＥ）などの乾式エッチングを行うことにより、シリコンＳＯＩ基板の上面及び下面に重り部４，５が変位するための空間（凹所）を形成する。そして、凹所底面の所定位置にシリコン酸化膜又はカーボンナノチューブからなる突起部１５を形成する。続いて、支持基板及び中間酸化膜の順にシリコンＳＯＩ基板の下面をエッチングすることで重り部４，５（凹部１１，１３並びに充実部１２，１４）を形成する。   In this embodiment, the sensor chip 1 is formed by processing a silicon SOI substrate composed of a support substrate, an intermediate oxide film, and an active layer using a semiconductor microfabrication technique. First, a mask material such as a silicon oxide film or a photoresist film is formed on both surfaces of a silicon SOI substrate, and after removing the mask material at a position corresponding to the weights 4 and 5, TMAH (tetramethyl ammonium hydroxide solution) or Space for displacing the weight portions 4 and 5 on the upper and lower surfaces of the silicon SOI substrate by performing wet etching using KOH (potassium hydroxide solution) or dry etching such as reactive ion etching (RIE). (Recess) is formed. And the projection part 15 which consists of a silicon oxide film or a carbon nanotube is formed in the predetermined position of a recess bottom face. Subsequently, the weight portions 4 and 5 (recess portions 11 and 13 and the solid portions 12 and 14) are formed by etching the lower surface of the silicon SOI substrate in the order of the support substrate and the intermediate oxide film.

一方、ガラス基板からなる上カバー２ａにサンドブラストなどの加工方法で貫通孔２０を貫設し（図２（ａ）参照）、上カバー２ａの下面にシリコン基板１００を接合する（図２（ｂ）参照）。次に、エッチングあるいはダイシングによって枠部８０と、第１及び第２の固定電極８１ａ，８１ｂと８２ａ，８２ｂとを形成する（図２（ｃ）参照）。   On the other hand, a through hole 20 is formed in the upper cover 2a made of a glass substrate by a processing method such as sandblasting (see FIG. 2A), and the silicon substrate 100 is joined to the lower surface of the upper cover 2a (FIG. 2B). reference). Next, the frame portion 80 and the first and second fixed electrodes 81a and 81b and 82a and 82b are formed by etching or dicing (see FIG. 2C).

そして、センサチップ１の下面及び上面にそれぞれ下カバー２ｂと上カバー２ａ（電極ブロック８）を陽極接合することにより、本実施形態の製造工程は完了する（図２（ｄ）参照）。   Then, the lower cover 2b and the upper cover 2a (electrode block 8) are anodically bonded to the lower surface and the upper surface of the sensor chip 1, respectively, thereby completing the manufacturing process of this embodiment (see FIG. 2D).

而して本実施形態では、検出電圧を取り出すための電極部８３ａ，８３ｂ、８４ａ，８４ｂを固定電極８１ａ，８１ｂ、８２ａ，８２ｂで兼用しているので、従来例のように電極部を設けるための専用のスペースが不要となって容易に小型化が図れる。また、固定電極８１ａ，８１ｂ、８２ａ，８２ｂをバルクシリコン（単結晶シリコンウェハ）で形成しているため、成膜などで形成した固定電極と比較して表面の平滑度が高くなり、可動電極４ａ，５ａとの間の電極間距離のばらつきが少ないために静電容量のばらつきも少なくなるという利点がある。しかも、電極ブロック８における枠部８０と固定電極８１ａ，８１ｂ、８２ａ，８２ｂとは、同一のシリコン基板から形成されているので、固定電極８１ａ，８１ｂ、８２ａ，８２ｂと可動電極４ａ，５ａとの間の電極間距離の精度が高く、その結果、静電容量のばらつきも少なくなるという利点がある。   Thus, in the present embodiment, the electrode portions 83a, 83b, 84a, and 84b for extracting the detection voltage are also used as the fixed electrodes 81a, 81b, 82a, and 82b, so that the electrode portions are provided as in the conventional example. Therefore, it is possible to reduce the size easily. Further, since the fixed electrodes 81a, 81b, 82a, and 82b are formed of bulk silicon (single crystal silicon wafer), the surface smoothness is higher than that of the fixed electrode formed by film formation or the like, and the movable electrode 4a. , 5a has a small variation in the distance between the electrodes, and therefore has an advantage that the variation in capacitance is also small. Moreover, since the frame portion 80 and the fixed electrodes 81a, 81b, 82a, 82b in the electrode block 8 are formed from the same silicon substrate, the fixed electrodes 81a, 81b, 82a, 82b and the movable electrodes 4a, 5a There is an advantage that the accuracy of the distance between the electrodes is high, and as a result, the variation in capacitance is reduced.

１ センサチップ
２ａ 上カバー（カバー）
４，５ 重り部
４ａ，５ａ 可動電極
６ａ，６ｂ ビーム部
７ａ，７ｂ ビーム部
８ 電極ブロック
２０ 貫通孔
８１ａ，８２ａ 第１の固定電極
８１ｂ，８２ｂ 第２の固定電極
８３ａ，８３ｂ 電極部
８４ａ，８４ｂ 電極部 1 Sensor chip 2a Upper cover (cover)
4,5 Weight part 4a, 5a Movable electrode 6a, 6b Beam part 7a, 7b Beam part 8 Electrode block 20 Through hole 81a, 82a First fixed electrode 81b, 82b Second fixed electrode 83a, 83b Electrode part 84a, 84b Electrode part

Claims (1)

一面に可動電極が設けられた重り部並びに重り部を回動軸の回りに回動自在に支持するビーム部が半導体基板を加工して形成されたセンサチップと、半導体基板からなる固定電極が一面に設けられ当該固定電極を可動電極に対向させる向きでセンサチップの一面側に接合される絶縁性のカバーと、カバーを貫通する貫通孔と、貫通孔を通してカバーの外に露出する固定電極からなる電極部とを備えたことを特徴とする加速度センサ。   A sensor chip formed by processing a semiconductor substrate with a weight portion provided with a movable electrode on one surface and a beam portion that rotatably supports the weight portion around a rotation axis, and a fixed electrode made of the semiconductor substrate on one surface An insulating cover that is joined to one surface side of the sensor chip in a direction in which the fixed electrode faces the movable electrode, a through hole that penetrates the cover, and a fixed electrode that is exposed to the outside through the through hole. An acceleration sensor comprising an electrode portion.
JP2009056948A 2009-03-10 2009-03-10 Acceleration sensor Ceased JP2010210423A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000028463A (en) * 1998-07-10 2000-01-28 Teijin Seiki Co Ltd Airtight sealing structure and its manufacture
JP2004333133A (en) * 2003-04-30 2004-11-25 Mitsubishi Electric Corp Inertial force sensor
JP2006170893A (en) * 2004-12-17 2006-06-29 Alps Electric Co Ltd Electrostatic capacitive pressure sensor
WO2008093693A1 (en) * 2007-02-02 2008-08-07 Alps Electric Co., Ltd. Electrostatic capacitance type acceleration sensor
JP2008292427A (en) * 2007-05-28 2008-12-04 Panasonic Electric Works Co Ltd Semiconductor sensor

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000028463A (en) * 1998-07-10 2000-01-28 Teijin Seiki Co Ltd Airtight sealing structure and its manufacture
JP2004333133A (en) * 2003-04-30 2004-11-25 Mitsubishi Electric Corp Inertial force sensor
JP2006170893A (en) * 2004-12-17 2006-06-29 Alps Electric Co Ltd Electrostatic capacitive pressure sensor
WO2008093693A1 (en) * 2007-02-02 2008-08-07 Alps Electric Co., Ltd. Electrostatic capacitance type acceleration sensor
JP2008292427A (en) * 2007-05-28 2008-12-04 Panasonic Electric Works Co Ltd Semiconductor sensor

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