JPH07198745A - Acceleration sensor - Google Patents

Acceleration sensor

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Publication number
JPH07198745A
JPH07198745A JP35374793A JP35374793A JPH07198745A JP H07198745 A JPH07198745 A JP H07198745A JP 35374793 A JP35374793 A JP 35374793A JP 35374793 A JP35374793 A JP 35374793A JP H07198745 A JPH07198745 A JP H07198745A
Authority
JP
Japan
Prior art keywords
voltage
weight portion
semiconductor substrate
conductivity type
voltage source
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP35374793A
Other languages
Japanese (ja)
Other versions
JP2936990B2 (en
Inventor
Hideo Muro
英夫 室
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nissan Motor Co Ltd
Original Assignee
Nissan Motor Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nissan Motor Co Ltd filed Critical Nissan Motor Co Ltd
Priority to JP35374793A priority Critical patent/JP2936990B2/en
Publication of JPH07198745A publication Critical patent/JPH07198745A/en
Application granted granted Critical
Publication of JP2936990B2 publication Critical patent/JP2936990B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Abstract

PURPOSE:To simplify the constitution of a voltage source so as to reduce the cost of the voltage source by electrically separating an overlapping section and beam section from each other by a P-N junction and applying an electrostatic driving voltage across the overlapping section and an electrode for self- diagnosis from an independent voltage source. CONSTITUTION:A P-type overlapping section 3 is electrically separated from a beam section 2 which is grounded and composed of an N-type epitaxial layer 8 by a P-N junction. Consequently, the electrostatic driving voltage applied across metallic electrodes 11 on a pedestal 5 from a voltage source 13 is applied across an air gap between the base of the section 3 and the electrodes 11 as it is and utilized as an electrostatic force generating voltage. When the minimum voltage value of a primary power source is 9 V and the voltage applied across the air gap required for electrostatic self-diagnosis is 15V, the voltage source 13 from which the voltage is applied across the electrodes 11 on the pedestal 5 can be obtained when the voltage of the primary power source is boosted double. Therefore, the constitution of the voltage source 13 can be simplified.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【産業上の利用分野】本発明は、加速度センサに関し、
特に靜電式自己診断用電圧印加構造の改良に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor,
In particular, it relates to improvement of a voltage applying structure for electric self-diagnosis.

【0002】[0002]

【従来の技術】従来の加速度センサとしては、例えば図
3及び図4に示すようなものがある(特願平5−278
032号)。これらの図において21はセンサチップで
あり、シリコン基板に裏面側から異方性エッチングを施
すことにより肉薄の梁部22が形成されていて、これが
中央の重り部23を両側から支持するいわゆる両持ち梁
構造となっている。梁部22の表面側には不純物拡散層
によりピエゾ抵抗26が形成されており、加速度印加に
より重り部23が変位し、梁部22の表面側に応力が生
じるとその抵抗値が変化して加速度が検出されるように
なっている。図の例ではピエゾ抵抗26が梁部22の固
定側と重り部23側に形成されていて、ブリッジ回路
(図示せず)を構成することにより、梁部22上の応力
を電圧に変換して出力するようになっている。27はシ
リコン酸化膜である。センサチップ21の下部にはシリ
コンと熱膨張係数が比較的近いパイレックスガラス製の
台座25が陽極接合されている。台座25は所定の領域
(図の右側)においてセンサチップ21の端部よりも外
側まで延びている。台座25の表面には重り部23に対
向する領域とそこから延長部までの領域に深さ数μmの
凹部28が形成され、凹部28の底面には金属電極30
が形成されており、その上にSiO2 等の絶縁膜34が
形成されている。センサチップ21の接続端子はボンデ
ィングパッド29からボンディングワイヤ31を介して
外部に電気的に接続されるようになっている。台座25
上の金属電極30も延長部においてボンディングワイヤ
31を介して自己診断のための外部の靜電駆動用電圧源
33に接続されている。
2. Description of the Related Art Conventional acceleration sensors include those shown in FIGS. 3 and 4, for example (Japanese Patent Application No. 5-278).
032). In these drawings, reference numeral 21 denotes a sensor chip, in which a thin beam portion 22 is formed by anisotropically etching a silicon substrate from the back surface side, and this is a so-called both-sided support for supporting a central weight portion 23 from both sides. It has a beam structure. A piezoresistor 26 is formed on the surface side of the beam portion 22 by an impurity diffusion layer, and when the weight portion 23 is displaced by the application of acceleration and stress is generated on the surface side of the beam portion 22, the resistance value changes to accelerate the acceleration. Is detected. In the illustrated example, the piezoresistor 26 is formed on the fixed side of the beam portion 22 and on the weight portion 23 side, and by configuring a bridge circuit (not shown), the stress on the beam portion 22 is converted into a voltage. It is designed to output. 27 is a silicon oxide film. A pedestal 25 made of Pyrex glass having a thermal expansion coefficient relatively close to that of silicon is anodically bonded to the lower portion of the sensor chip 21. The pedestal 25 extends outside the end of the sensor chip 21 in a predetermined area (right side in the drawing). On the surface of the pedestal 25, a recess 28 having a depth of several μm is formed in a region facing the weight portion 23 and a region from the weight portion 23 to the extension portion.
Is formed, and an insulating film 34 of SiO 2 or the like is formed thereon. The connection terminal of the sensor chip 21 is electrically connected to the outside from the bonding pad 29 via the bonding wire 31. Pedestal 25
The upper metal electrode 30 is also connected to an external electrostatic drive voltage source 33 for self-diagnosis through a bonding wire 31 at the extension.

【0003】そして外部からチップ面と垂直方向に加速
度が加わると、重り部23が変位して梁部22の表面に
は固定側と重り部23側で極性が反対で絶対値がほぼ等
しい応力が発生する。この応力によりピエゾ抵抗26の
抵抗値が変化し、この変化がブリッジ回路、増幅回路等
を経て電圧に変換され、電気信号として取り出される。
When an acceleration is applied from the outside in the direction perpendicular to the chip surface, the weight portion 23 is displaced, and the surface of the beam portion 22 receives a stress whose polarities are opposite on the fixed side and the weight portion 23 side and whose absolute values are substantially equal. Occur. Due to this stress, the resistance value of the piezoresistor 26 changes, and this change is converted into a voltage through a bridge circuit, an amplifier circuit, etc., and taken out as an electric signal.

【0004】通常、ピエゾ抵抗26にはP型拡散層が用
いられ、センサチップとなるN型シリコン基板にP型不
純物を拡散して形成されるので、N型の梁部22及び重
り部23にはピエゾ抵抗26素子を電気的に分離するた
め、ブリッジ印加電圧以上の電圧を有する正電圧源32
が接続され、その電圧値Vccに正バイアスされている。
したがって自己診断用の金属電極30に靜電駆動用電圧
源33からVd の電圧を印加すると金属電極30と重り
部23底面間のギャップにはVb =Vd −Vccの電圧が
加わる。いま、重り部23と金属電極30の間に所定電
圧Vb を印加すると、両者の間に靜電引力Fが働き、下
方向への加速度が加わった場合と同様の応力を梁部22
に発生させることができるので、センサ機能の診断或い
はその感度の較正を行うことができる。ここで靜電力F
e は次式で表わされる。
Usually, a P-type diffusion layer is used for the piezoresistor 26 and is formed by diffusing P-type impurities in an N-type silicon substrate which will be a sensor chip, so that the N-type beam portion 22 and the weight portion 23 are formed. Is a positive voltage source 32 having a voltage higher than the bridge applied voltage in order to electrically isolate the piezoresistive 26 element.
Are connected and are positively biased to the voltage value Vcc .
Therefore, when a voltage of V d is applied from the electrostatic drive voltage source 33 to the metal electrode 30 for self-diagnosis, a voltage of V b = V d −V cc is applied to the gap between the metal electrode 30 and the bottom surface of the weight portion 23. Now, when a predetermined voltage Vb is applied between the weight portion 23 and the metal electrode 30, the electromotive force F acts between them and the beam portion 22 receives the same stress as when downward acceleration is applied.
The sensor function can be diagnosed or its sensitivity can be calibrated. Where the electric power F
e is expressed by the following equation.

【0005】 Fe =(1/2)ε・S(Vb /d)2 …(1) ここで、ε:ギャップ部の誘電率、S:重り部の底面
積、d:ギャップ長である。Vccの値として5Vの安定
化電圧を用いると、ギャップにVb =15Vの靜電駆動
用電圧を加えるためにはVd として20Vが必要とな
る。
F e = (1/2) ε · S (V b / d) 2 (1) where ε is the dielectric constant of the gap portion, S is the bottom area of the weight portion, and d is the gap length. . If a stabilizing voltage of 5 V is used as the value of V cc , 20 V is required as V d in order to apply a static driving voltage of V b = 15V to the gap.

【0006】[0006]

【発明が解決しようとする課題】従来の加速度センサで
は、N型シリコン基板をエッチング加工して梁部/重り
部構造を作り、そこにP型拡散層からなるピエゾ抵抗素
子分離のための正電圧Vccを印加して重り部を正バイア
スし、重り部と対向する金属電極に電圧を印加して自己
診断用の靜電力を発生させるような構成となっていたた
め、所要の靜電力を発生させるために必要な金属電極へ
の印加電圧がVccだけ高くなり、昇圧回路が必要とな
る、もしくは昇圧係数が大きくなって昇圧のためのコス
トが増すという問題があった。
In the conventional acceleration sensor, a beam / weight structure is formed by etching an N-type silicon substrate, and a positive voltage for separating a piezoresistive element composed of a P-type diffusion layer is formed therein. Vcc is applied to positively bias the weighted portion, and a voltage is applied to the metal electrode facing the weighted portion to generate the nematic power for self-diagnosis, so that the required nematic power is generated. Therefore, there is a problem that the voltage applied to the metal electrode is increased by V cc and a booster circuit is required, or the boosting coefficient becomes large and the cost for boosting increases.

【0007】本発明は、このような従来の問題に着目し
てなされたもので、電圧源からの靜電駆動用電圧をその
まま靜電力発生用の電圧とすることができて電圧源の構
成を簡易化しコスト低減を図ることのできる加速度セン
サを提供することを目的とする。
The present invention has been made by paying attention to such a conventional problem, and it is possible to use the voltage for driving the static electricity from the voltage source as it is as the voltage for generating the static electric power, thereby simplifying the configuration of the voltage source. It is an object of the present invention to provide an acceleration sensor that can be realized at a reduced cost.

【0008】[0008]

【課題を解決するための手段】上記課題を解決するため
に、本発明は、第1に、半導体基板のエッチング加工に
より形成され、固定部に梁部で支持されて被検出加速度
に応じて変位する重り部を有し、前記梁部の表面部には
ピエゾ抵抗が形成されたセンサチップと、該センサチッ
プの下部に前記重り部と所要のエアギャップを有するよ
うに接合され、前記重り部との対向面に電極が形成され
た台座とを備え、前記重り部と前記電極間への印加電圧
で生じる靜電力によりセンサ機能を自己診断するように
した加速度センサにおいて、前記重り部と梁部とをPN
接合で電気的に分離し、前記重り部と前記電極間には独
立の電圧源から靜電駆動用電圧を印加するように構成し
てなることを要旨とする。
In order to solve the above-mentioned problems, the present invention is, firstly, the present invention, which is formed by etching a semiconductor substrate, is supported by a beam portion on a fixed portion, and is displaced in accordance with a detected acceleration. A sensor chip having a piezoresistor formed on the surface portion of the beam portion, and the weight portion is joined to the lower portion of the sensor chip so as to have a required air gap. A pedestal having electrodes formed on the opposite surfaces thereof, and an acceleration sensor configured to self-diagnose the sensor function by the whiskers generated by the voltage applied between the weight portion and the electrodes, wherein the weight portion and the beam portion are provided. PN
The gist is that the electrodes are electrically separated by joining, and a voltage for driving electricity is applied between the weight portion and the electrode from an independent voltage source.

【0009】第2に、上記第1の構成において、前記半
導体基板は、一導電型半導体基板の一主面上に他導電型
層状領域を形成したものであり、前記梁部は該層状領域
により形成され、前記重り部は主に前記一導電型半導体
基板から成り、該重り部の一主面側には前記層状領域を
貫通して前記一導電型半導体基板へ達する一導電型不純
物拡散領域が形成され、前記電圧源は該拡散領域を介し
て前記重り部へ接続してなることを要旨とする。
Secondly, in the above-mentioned first structure, the semiconductor substrate is formed by forming another conductivity type layered region on one main surface of one conductivity type semiconductor substrate, and the beam portion is formed by the layered region. The weight portion is mainly formed of the one conductivity type semiconductor substrate, and one conductivity type impurity diffusion region penetrating the layered region and reaching the one conductivity type semiconductor substrate is formed on one main surface side of the weight portion. The gist is that the voltage source is formed and is connected to the weight portion through the diffusion region.

【0010】第3に、前記第1の構成において、前記一
導電型半導体基板はP型であり、前記他導電型層状領域
はN型エピタキシャル層であり、前記梁部及び重り部は
該N型エピタキシャル層を正電圧にバイアスしながらエ
レクトロ・ケミカル・エッチングにより形成したもので
あることを要旨とする。
Thirdly, in the first structure, the one conductivity type semiconductor substrate is P type, the other conductivity type layered region is an N type epitaxial layer, and the beam portion and the weight portion are the N type. The gist is that the epitaxial layer is formed by electro-chemical etching while biasing it to a positive voltage.

【0011】[0011]

【作用】上記構成において、第1に、重り部と梁部とは
PN接合で電気的に分離されているので、電圧源から重
り部と電極間に印加される靜電駆動用電圧がそのまま重
り部の底面と電極層のエアギャップに印加され、靜電力
発生用の電圧として利用される。したがって電圧源の構
成を簡易化することが可能となる。
In the above structure, firstly, since the weight portion and the beam portion are electrically separated by the PN junction, the electrostatic driving voltage applied between the weight portion and the electrode from the voltage source is directly applied to the weight portion. It is applied to the air gap between the bottom surface of the electrode and the electrode layer, and is used as a voltage for generating static electricity. Therefore, the configuration of the voltage source can be simplified.

【0012】第2に、重り部と梁部とのPN接合分離
は、梁部を形成している他導電型層状領域を貫通して、
重り部を形成している一導電型半導体基板部に達する一
導電型不純物拡散領域を形成することにより、通常の半
導体処理技術を用いて容易、確実に実現される。
Secondly, in the PN junction separation between the weight portion and the beam portion, the other conductive type layered region forming the beam portion is penetrated,
By forming the one-conductivity-type impurity diffusion region that reaches the one-conductivity-type semiconductor substrate portion forming the weight portion, it is easily and surely realized by using a normal semiconductor processing technique.

【0013】第3に、上記PN接合分離のため、具体的
には、半導体基板は、P型基板上にN型エピタキシャル
層を形成したものが用いられているので、梁部及び重り
部はN型エピタキシャル層を正電圧にバイアスしながら
エレクトロ・ケミカル・エッチングで形成することによ
り、容易且つ精度のよいセンサチップを形成することが
可能となる。
Thirdly, because of the PN junction isolation, specifically, since the semiconductor substrate is a P-type substrate on which an N-type epitaxial layer is formed, the beam portion and the weight portion are N-shaped. By forming the epitaxial layer by electro-chemical etching while biasing it to a positive voltage, it becomes possible to form a sensor chip easily and accurately.

【0014】[0014]

【実施例】以下、本発明の実施例を図面に基づいて説明
する。図1は本発明の一実施例を示す図である。まず加
速度センサの構成を説明すると、1はP型シリコン基
板、8はP型シリコン基板1の一主面上に堆積された薄
いN型エピタキシャル層である。2はN型エピタキシャ
ル層8部分からなる梁部、3,4はそれぞれ主にP型シ
リコン基板1部からなる重り部及び固定部であり、これ
らはN型エピタキシャル層8を正電位にバイアスしなが
らP型シリコン基板1を裏面からアルカリ性異方性エッ
チング液を用いたエレクトロ・ケミカル・エッチングを
行うことにより形成されている。重り部3は両側から梁
部2により、それらを取り囲む固定部4にけん架支持さ
れており、いわゆる両持ち梁構造となっている。重り部
3の一主面側には、当該重り部3と梁部2とをPN接合
で電気的に分離するため、N型エピタキシャル層8を貫
通して重り部3を形成しているP型シリコン基板1に達
するP型拡散領域15が形成されている。また梁部2の
表面にはP型拡散層により複数のピエゾ抵抗6が形成さ
れており、それらはブリッジ接続(図示せず)されて、
重り部3への加速度印加で梁部2の表面に生じる応力に
よるピエゾ抵抗6の抵抗値変化が電圧に変換され、加速
度に対応した電圧信号が出力されるようになっている。
7はSiO2 等の表面保護膜、9はP型拡散領域15を
電気的に外部に取り出すための電極部である。このよう
にしてセンサチップ10が形成されている。
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention. First, the structure of the acceleration sensor will be described. 1 is a P-type silicon substrate, and 8 is a thin N-type epitaxial layer deposited on one main surface of the P-type silicon substrate 1. Reference numeral 2 denotes a beam portion composed of the N-type epitaxial layer 8 portion, and 3 and 4 are respectively a weight portion and a fixed portion mainly composed of the P-type silicon substrate 1 portion, which are biasing the N-type epitaxial layer 8 to a positive potential. The P-type silicon substrate 1 is formed by performing electro-chemical etching from the back surface using an alkaline anisotropic etching solution. The weight portion 3 is suspended and supported by the beam portion 2 from both sides on a fixed portion 4 surrounding the beam portion 2, and has a so-called double-supported beam structure. In order to electrically separate the weight portion 3 and the beam portion 2 by a PN junction on one main surface side of the weight portion 3, the P-type which forms the weight portion 3 through the N-type epitaxial layer 8 is formed. A P-type diffusion region 15 reaching the silicon substrate 1 is formed. Further, a plurality of piezoresistors 6 are formed on the surface of the beam portion 2 by a P-type diffusion layer, which are bridge-connected (not shown),
A change in the resistance value of the piezoresistor 6 due to the stress generated on the surface of the beam portion 2 when the acceleration is applied to the weight portion 3 is converted into a voltage, and a voltage signal corresponding to the acceleration is output.
Reference numeral 7 is a surface protective film such as SiO 2 , and 9 is an electrode portion for electrically taking out the P-type diffusion region 15 to the outside. In this way, the sensor chip 10 is formed.

【0015】センサチップ10の下部には、重り部3に
対向してそれより広い領域に凹部18を有するパイレッ
クスガラス製の台座5が陽極接合されている。凹部18
内には靜電式自己診断用の金属電極11が形成されてお
り、その上に保護膜14が形成されている。台座5及び
その上の金属電極11は外部への電気接続のため、セン
サチップ10の端部よりも外側まで延びており、そこで
ワイヤ(図示せず)に接続され、外部の靜電駆動用電圧
源13に接続されている。19は電極取出しのための横
穴部である。N型エピタキシャル層8は、ピエゾ抵抗6
素子を電気的に分離するため、電圧源12により正電位
にバイアスされているが、重り部3はP型拡散領域15
及び電極部9を介して接地されており、N型エピタキシ
ャル層8からなる梁部2とはPN接合で電気的に分離さ
れている。
A pedestal 5 made of Pyrex glass is anodically bonded to the lower portion of the sensor chip 10 so as to face the weight portion 3 and have a recess 18 in a region wider than the weight portion 3. Recess 18
A metal electrode 11 for electric self-diagnosis is formed therein, and a protective film 14 is formed thereon. The pedestal 5 and the metal electrode 11 on the pedestal 5 extend to the outside of the end of the sensor chip 10 for electrical connection to the outside, and are connected to a wire (not shown) there to connect to an external voltage source for driving electricity. It is connected to 13. Reference numeral 19 is a lateral hole for taking out the electrode. The N-type epitaxial layer 8 has a piezoresistor 6
In order to electrically isolate the elements, the voltage source 12 biases them to a positive potential.
It is also grounded via the electrode portion 9 and is electrically separated from the beam portion 2 formed of the N-type epitaxial layer 8 by a PN junction.

【0016】次に、上述のように構成された加速度セン
サの作用を説明する。P型の重り部3は接地されてN型
エピタキシャル層8からなる梁部2とはPN接合で電気
的に分離されているので、台座5上の金属電極11へ印
加される電圧源13からの靜電駆動用電圧はそのまま重
り部3の底面と金属電極11間のエアギャップに印加さ
れ、靜電力発生用の電圧として利用さる。いま元の電源
の最小電圧値を9V、靜電式自己診断のために必要なエ
アギャップへの印加電圧を15V以上とすると、台座5
上の金属電極11に電圧を印加する電圧源13は本実施
例では2倍昇圧で実現できる。これに対し前述の従来例
では3倍昇圧が必要となるので大きなコストアップとな
る。
Next, the operation of the acceleration sensor configured as described above will be described. Since the P-type weight portion 3 is grounded and electrically separated from the beam portion 2 formed of the N-type epitaxial layer 8 by the PN junction, the voltage source 13 applied to the metal electrode 11 on the pedestal 5 The electrostatic driving voltage is applied as it is to the air gap between the bottom surface of the weight portion 3 and the metal electrode 11, and is used as a voltage for generating electrostatic power. Assuming that the minimum voltage value of the original power supply is 9V and the voltage applied to the air gap required for the electrostatic self-diagnosis is 15V or more, the base 5
The voltage source 13 for applying a voltage to the upper metal electrode 11 can be realized by double boosting in this embodiment. On the other hand, in the above-mentioned conventional example, triple boosting is required, resulting in a large cost increase.

【0017】次いで、図2には、本発明の他の実施例を
示す。本実施例は、センサチップ10の構造は、前記図
1の実施例のものと同じであるが、台座5上の金属電極
11の接続法が異なっている。金属電極11は図の右側
の固定部4まで延びてきて、そこでP型シリコン基板1
からなる固定部4へ台座5により押え付けられるように
して電気接続されている。P型シリコン基板1は接地さ
れているので、金属電極11も接地されることになる。
一方、P型の重り部3は電極部9を介して負の電圧源1
6に接続されており、この電圧源16からの靜電駆動用
電圧がそのまま靜電力発生用の電圧として利用される。
本実施例は、上述のような構成とすることにより、台座
5における電極取出し部が不要となるのでセンササイズ
を小型化することができ、さらに図1に示した電極取り
出し用の横穴部からのダイシング時の水の浸入がなくな
るのでより信頼性を向上させることが可能となる。
Next, FIG. 2 shows another embodiment of the present invention. In this embodiment, the structure of the sensor chip 10 is the same as that of the embodiment shown in FIG. 1, but the connection method of the metal electrode 11 on the pedestal 5 is different. The metal electrode 11 extends to the fixed portion 4 on the right side of the figure, where the P-type silicon substrate 1
Is electrically connected to the fixed portion 4 composed of a pedestal 5 so as to be pressed. Since the P-type silicon substrate 1 is grounded, the metal electrode 11 is also grounded.
On the other hand, the P-type weight portion 3 is connected to the negative voltage source 1 via the electrode portion 9.
6 is used, and the static electricity driving voltage from the voltage source 16 is directly used as the static electricity generating voltage.
According to the present embodiment, by adopting the above-described configuration, the electrode lead-out portion on the pedestal 5 is not required, so that the sensor size can be reduced, and further, the electrode lead-out lateral hole portion shown in FIG. Since water does not enter during dicing, reliability can be further improved.

【0018】なお、上述の実施例では両持ち梁構造の加
速度センサについて説明したが、片持ち梁構造やダイヤ
フラム構造の加速度センサへ適用できるのは勿論であ
る。また梁形式ではN型エピタキシャル層をエレクトロ
・ケミカル・エッチングで残す方法を説明したが、N型
エピタキシャル層の代りに拡散層を用いたり、時間制御
のエッチング法を用いることもできる。
Although the acceleration sensor having the double-supported beam structure has been described in the above embodiment, it is needless to say that the present invention can be applied to the acceleration sensor having the cantilever structure or the diaphragm structure. In the beam type, the method of leaving the N-type epitaxial layer by electro-chemical etching has been described, but a diffusion layer may be used instead of the N-type epitaxial layer, or a time-controlled etching method may be used.

【0019】[0019]

【発明の効果】以上説明したように、本発明によれば、
第1に、重り部と梁部とをPN接合で電気的に分離し、
重り部と自己診断用の電極間には独立の電圧源から靜電
駆動用電圧を印加するように構成したため、電圧源から
の靜電駆動用電圧をそのまま靜電力発生用の電圧とする
ことができて電圧源の構成を簡易化することができ、コ
スト低減を図ることができる。
As described above, according to the present invention,
First, the weight portion and the beam portion are electrically separated by a PN junction,
Since the voltage for driving electric power is applied from an independent voltage source between the weight and the electrode for self-diagnosis, the voltage for driving electric power from the voltage source can be directly used as the voltage for generating electric power. The configuration of the voltage source can be simplified, and the cost can be reduced.

【0020】第2に、半導体基板は、一導電型半導体基
板の一主面上に他導電型層状領域を形成したものであ
り、梁部は該層状領域により形成し、重り部は主に前記
一導電型半導体基板から成り、該重り部の一主面側には
前記層状領域を貫通して一導電型半導体基板へ達する一
導電型不純物拡散領域を形成し、電圧源は該拡散領域を
介して重り部へ接続するようにしたため、重り部と梁部
とのPN接合分離を通常の半導体処理技術を用いて容
易、確実に実現することができる。
Secondly, the semiconductor substrate is formed by forming another conductive type layered region on one main surface of one conductive type semiconductor substrate, the beam portion is formed by the layered region, and the weight portion is mainly the above-mentioned. A one-conductivity type semiconductor substrate is formed, and a one-conductivity type impurity diffusion region penetrating the layered region and reaching the one-conductivity type semiconductor substrate is formed on one main surface side of the weight portion, and a voltage source is provided through the diffusion region. Since the weight portion and the beam portion are connected to each other, the PN junction separation between the weight portion and the beam portion can be easily and surely realized by using an ordinary semiconductor processing technique.

【0021】第3に、重り部と梁部とのPN接合分離の
ため、半導体基板は、具体的には、P型基板上にN型エ
ピタキシャル層を形成したものを用いているので、梁部
及び重り部はN型エピタキシャル層を正電圧にバイアス
しながらエレクトロ・ケミカル・エッチング法で形成す
ることにより、容易且つ高精度にセンサチップを形成す
ることができる。
Third, in order to separate the PN junction between the weight portion and the beam portion, since the semiconductor substrate is specifically a P-type substrate on which an N-type epitaxial layer is formed, the beam portion is used. By forming the weight portion and the weight portion by the electro-chemical etching method while biasing the N-type epitaxial layer to a positive voltage, the sensor chip can be formed easily and highly accurately.

【図面の簡単な説明】[Brief description of drawings]

【図1】本発明に係る加速度センサの一実施例を示す縦
断面図である。
FIG. 1 is a vertical sectional view showing an embodiment of an acceleration sensor according to the present invention.

【図2】本発明の他の実施例を示す縦断面図である。FIG. 2 is a vertical sectional view showing another embodiment of the present invention.

【図3】従来の加速度センサを示す平面図である。FIG. 3 is a plan view showing a conventional acceleration sensor.

【図4】図3のA−A線断面図である。4 is a cross-sectional view taken along the line AA of FIG.

【符号の説明】[Explanation of symbols]

1 P型シリコン基板 2 梁部 3 重り部 4 固定部 5 台座 6 ピエゾ抵抗 8 N型エピタキシャル層 10 センサチップ 11 自己診断用の金属電極 12 バイアス用電圧源 13,16 靜電駆動用電圧源 15 P型拡散領域 1 P-type silicon substrate 2 Beam part 3 Weight part 4 Fixing part 5 Pedestal 6 Piezoresistor 8 N-type epitaxial layer 10 Sensor chip 11 Metal electrode for self-diagnosis 12 Bias voltage source 13, 16 Electric drive voltage source 15 P type Diffusion area

Claims (3)

【特許請求の範囲】[Claims] 【請求項1】 半導体基板のエッチング加工により形成
され、固定部に梁部で支持されて被検出加速度に応じて
変位する重り部を有し、前記梁部の表面部にはピエゾ抵
抗が形成されたセンサチップと、該センサチップの下部
に前記重り部と所要のエアギャップを有するように接合
され、前記重り部との対向面に電極が形成された台座と
を備え、前記重り部と前記電極間への印加電圧で生じる
靜電力によりセンサ機能を自己診断するようにした加速
度センサにおいて、前記重り部と梁部とをPN接合で電
気的に分離し、前記重り部と前記電極間には独立の電圧
源から靜電駆動用電圧を印加するように構成してなるこ
とを特徴とする加速度センサ。
1. A semiconductor substrate is formed by etching, a fixed portion has a weight portion supported by a beam portion and displaced in accordance with a detected acceleration, and a piezoresistor is formed on a surface portion of the beam portion. A sensor chip and a pedestal that is joined to the lower portion of the sensor chip so as to have a required air gap and has an electrode formed on a surface facing the weight portion. In an acceleration sensor in which the sensor function is self-diagnosed by the static electricity generated by the voltage applied between the electrodes, the weight portion and the beam portion are electrically separated by a PN junction, and the weight portion and the electrode are independent. An acceleration sensor configured to apply a voltage for driving electric power from the voltage source.
【請求項2】 前記半導体基板は、一導電型半導体基板
の一主面上に他導電型層状領域を形成したものであり、
前記梁部は該層状領域により形成され、前記重り部は主
に前記一導電型半導体基板から成り、該重り部の一主面
側には前記層状領域を貫通して前記一導電型半導体基板
へ達する一導電型不純物拡散領域が形成され、前記電圧
源は該拡散領域を介して前記重り部へ接続してなること
を特徴とする請求項1記載の加速度センサ。
2. The semiconductor substrate is a semiconductor substrate in which a layer of another conductivity type is formed on one main surface of a semiconductor substrate of one conductivity type.
The beam portion is formed by the layered region, the weight portion is mainly composed of the one conductivity type semiconductor substrate, and the one major surface side of the weight portion penetrates the layer region to the one conductivity type semiconductor substrate. 2. The acceleration sensor according to claim 1, wherein an impurity diffusion region of one conductivity type that reaches is formed, and the voltage source is connected to the weight portion through the diffusion region.
【請求項3】 前記一導電型半導体基板はP型であり、
前記他導電型層状領域はN型エピタキシャル層であり、
前記梁部及び重り部は該N型エピタキシャル層を正電圧
にバイアスしながらエレクトロ・ケミカル・エッチング
により形成したものであることを特徴とする請求項1記
載の加速度センサ。
3. The one conductivity type semiconductor substrate is P type,
The other conductivity type layered region is an N type epitaxial layer,
The acceleration sensor according to claim 1, wherein the beam portion and the weight portion are formed by electro-chemical etching while biasing the N-type epitaxial layer to a positive voltage.
JP35374793A 1993-12-29 1993-12-29 Acceleration sensor Expired - Fee Related JP2936990B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP35374793A JP2936990B2 (en) 1993-12-29 1993-12-29 Acceleration sensor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP35374793A JP2936990B2 (en) 1993-12-29 1993-12-29 Acceleration sensor

Publications (2)

Publication Number Publication Date
JPH07198745A true JPH07198745A (en) 1995-08-01
JP2936990B2 JP2936990B2 (en) 1999-08-23

Family

ID=18432952

Family Applications (1)

Application Number Title Priority Date Filing Date
JP35374793A Expired - Fee Related JP2936990B2 (en) 1993-12-29 1993-12-29 Acceleration sensor

Country Status (1)

Country Link
JP (1) JP2936990B2 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0997737A1 (en) * 1998-02-19 2000-05-03 Akebono Brake Industry Co., Ltd. Semiconductor acceleration sensor and self-diagnosis thereof
US6332359B1 (en) 1997-04-24 2001-12-25 Fuji Electric Co., Ltd. Semiconductor sensor chip and method for producing the chip, and semiconductor sensor and package for assembling the sensor

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6332359B1 (en) 1997-04-24 2001-12-25 Fuji Electric Co., Ltd. Semiconductor sensor chip and method for producing the chip, and semiconductor sensor and package for assembling the sensor
US6446507B2 (en) 1997-04-24 2002-09-10 Fuji Electric Co., Ltd. Semiconductor sensor chip and method for producing the chip, and semiconductor sensor and package for assembling the sensor
US6494092B2 (en) 1997-04-24 2002-12-17 Fuji Electric Co., Ltd. Semiconductor sensor chip and method for producing the chip, and semiconductor sensor and package for assembling the sensor
US6526827B2 (en) 1997-04-24 2003-03-04 Fuki Electric Co., Ltd. Semiconductor sensor chip and method for producing the chip, and semiconductor sensor and package for assembling the sensor
US6564634B2 (en) 1997-04-24 2003-05-20 Fuji Electric Co., Ltd. Semiconductor sensor chip and method for producing the chip, and semiconductor sensor and package for assembling the sensor
US6632697B2 (en) 1997-04-24 2003-10-14 Fuji Electric Co., Ltd. Semiconductor sensor chip and method for producing the chip, and semiconductor sensor and package for assembling the sensor
EP0997737A1 (en) * 1998-02-19 2000-05-03 Akebono Brake Industry Co., Ltd. Semiconductor acceleration sensor and self-diagnosis thereof
EP0997737A4 (en) * 1998-02-19 2002-04-03 Akebono Brake Ind Semiconductor acceleration sensor and self-diagnosis thereof

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