JPH07191056A - Acceleration sensor - Google Patents
Acceleration sensorInfo
- Publication number
- JPH07191056A JPH07191056A JP5328548A JP32854893A JPH07191056A JP H07191056 A JPH07191056 A JP H07191056A JP 5328548 A JP5328548 A JP 5328548A JP 32854893 A JP32854893 A JP 32854893A JP H07191056 A JPH07191056 A JP H07191056A
- Authority
- JP
- Japan
- Prior art keywords
- self
- electrodes
- electrode
- holes
- sensor
- 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.)
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
- G01P2015/0805—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration
- G01P2015/0822—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining out-of-plane movement of the mass
- G01P2015/0825—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining out-of-plane movement of the mass for one single degree of freedom of movement of the mass
- G01P2015/0828—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values being provided with a particular type of spring-mass-system for defining the displacement of a seismic mass due to an external acceleration for defining out-of-plane movement of the mass for one single degree of freedom of movement of the mass the mass being of the paddle type being suspended at one of its longitudinal ends
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- Pressure Sensors (AREA)
- ing And Chemical Polishing (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、加速度センサに関し、
特にセンサ機能の自己診断部の改良に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor,
In particular, it relates to improvement of the self-diagnosis unit of the sensor function.
【０００２】[0002]
【従来の技術】加速度センサの第１の従来例として、例
えば図４に示すようなものがある（Stephen C.Terry,Di
ederik W.de Bruin,Henry V.Allen,"Self-testable Acc
elerometer Microsystem",Micro System Technologies
,90,Berlin,Germany,pp.611〜616(1990))。この従来例
は、両持ち梁式半導体加速度センサであり、靜電駆動型
自己診断機能を有している。図１において、１はシリコ
ンセンサチップであり、裏面からの異方性エッチングに
より肉薄の梁２が形成されていて、これが中央の重り部
３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。センサチップ１の上面には凹部１３を有するシリコ
ンのキャップ１２、下面には凹部６を有するシリコンの
台座５がそれぞれ合金接合等により接合されていて、被
検出加速度に応じて重り部３が上下に変位でき、且つそ
の変位が凹部６，１３中の突起部１４，１５により制限
され、過大加速度が加わった時の梁２の破損が防止され
るような構成となっている。梁２の表面部にはピエゾ抵
抗４が形成されており、加速度印加により重り部３が変
位し、梁２の表面部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４が梁２の支持部側と重り部３側に形成され
ていて、この両側で応力が逆極性となることを利用して
クルブリッジ（図示せず）を構成し、他軸感度の低減が
可能となっている。キャップ１２及び台座５により重り
部３との間に形成された狭いエアギャップは前述のよう
に重り部３のストッパとして機能するばかりでなく、梁
２の共振を抑制するエアダンピングを可能としている。
ここでエアダンピングとは、重り部３が変位しようとす
ると、狭いエアギャップに存在する粘性を有する気体が
エアギャップの外部に押し出されるか或いは内部に流れ
込む時に起きる気体同士或いは気体と半導体面又は金属
電極面との摩擦により重り部３の変位方向とは逆方向に
生じる抵抗力である。2. Description of the Related Art As a first conventional example of an acceleration sensor, there is one as shown in FIG. 4 (Stephen C. Terry, Di.
ederik W.de Bruin, Henry V.Allen, "Self-testable Acc
elerometer Microsystem ", Micro System Technologies
, 90, Berlin, Germany, pp.611-616 (1990)). This conventional example is a double-supported beam type semiconductor acceleration sensor, which has an electrostatic drive type self-diagnosis function. In FIG. 1, reference numeral 1 is a silicon sensor chip, and a thin beam 2 is formed by anisotropic etching from the back surface, and this has a so-called double-supported beam structure that supports a central weight portion 3 from both sides. . A silicon cap 12 having a recess 13 is bonded to the upper surface of the sensor chip 1, and a silicon pedestal 5 having a recess 6 is bonded to the lower surface of the sensor chip 1 by alloy bonding or the like, and the weight portion 3 is vertically moved according to the acceleration to be detected. The beam 2 can be displaced, and the displacement is limited by the protrusions 14 and 15 in the recesses 6 and 13, so that the beam 2 is prevented from being damaged when excessive acceleration is applied. A piezoresistor 4 is formed on the surface of the beam 2 so that the weight 3 is displaced by application of acceleration, and when stress is generated on the surface of the beam 2, the resistance value changes and acceleration is detected. Has become. In the example shown in the figure, the piezoresistors 4 are formed on the support portion side and the weight portion 3 side of the beam 2, and the stress is opposite in polarity on both sides, so that a Kull bridge (not shown) is formed. It is possible to reduce the sensitivity of other axes. The narrow air gap formed between the weight portion 3 by the cap 12 and the pedestal 5 not only functions as a stopper for the weight portion 3 as described above, but also enables air damping for suppressing the resonance of the beam 2.
Here, air damping means that when the weight portion 3 is displaced, the gases existing in a narrow air gap are extruded to the outside of the air gap or flow into the inside, or the gases and the semiconductor surface or metal. It is a resistance force generated in a direction opposite to the displacement direction of the weight portion 3 due to friction with the electrode surface.
【０００３】また、重り部３の上には自己診断用の金属
電極１６が形成されていてキャップ１２と狭いエアギャ
ップを介して対向している。キャップ１２の凹部１３に
も自己診断用の金属電極（図示せず）が形成されてお
り、この金属電極はセンサチップ１とキャップ１２との
接合部においてセンサチップ１上の金属配線（図示せ
ず）に電気的に接続されてボンディングパッド１７に引
き出されている。このキャップ１２側の金属電極と重り
部３上の金属電極１６との間に電圧を印加すると靜電力
により重り部３は上側に変位し、被検出加速度が加わっ
た時と同様な応力を梁２に発生させることができる。こ
の時のセンサ出力をチェックすることによりセンサの検
出機能を確認するいわゆる自己診断が可能となる。A metal electrode 16 for self-diagnosis is formed on the weight portion 3 and faces the cap 12 via a narrow air gap. A metal electrode (not shown) for self-diagnosis is also formed in the recess 13 of the cap 12, and this metal electrode is a metal wiring (not shown) on the sensor chip 1 at the joint between the sensor chip 1 and the cap 12. ) And is led out to the bonding pad 17. When a voltage is applied between the metal electrode on the side of the cap 12 and the metal electrode 16 on the weight portion 3, the weight portion 3 is displaced upward due to the whipping power, and the same stress as when the acceleration to be detected is applied is applied to the beam 2. Can be generated. By checking the sensor output at this time, so-called self-diagnosis for confirming the detection function of the sensor becomes possible.
【０００４】ところで、靜電駆動型自己診断の出力は大
きい程理想的であり、そのためには、重り部３上の金属
電極１６とキャップ１２側の金属電極との間のエアギャ
ップは１〜２μｍ程度と狭くしなければならない。しか
しエアギャップが狭くなるとエアダンピングが効き過ぎ
て加速度センサの応答性が劣化するという問題がある。By the way, the larger the output of the electrostatic drive type self-diagnosis is, the more ideal it is. Therefore, the air gap between the metal electrode 16 on the weight portion 3 and the metal electrode on the cap 12 side is about 1 to 2 μm. I have to narrow it. However, when the air gap becomes narrow, there is a problem that the air damping becomes too effective and the response of the acceleration sensor deteriorates.
【０００５】図５には、加速度センサの第２の従来例を
示す（特開平２−１１６７５５号公報）。加速度センサ
としての基本構成は第１の従来例と同じであるが、靜電
駆動型自己診断部の構成が異なっている。この従来例で
は上側のキャップが無く、台座１８の表面に形成された
凹部６内の面と重り部３の底面にそれぞれ自己診断用の
金属電極７，８が対向して形成されていて靜電アクチュ
エータが構成されている。通常、このような構成は台座
１８をパイレックスガラスを用いて加工し、最後にシリ
コンのセンサチップ１と陽極接合することにより作製さ
れる。しかし、この従来例においても前記第１の従来例
と同様に両金属電極７，８間のエアギャップが狭くなる
とエアダンピングが効き過ぎて加速度センサの応答性が
劣化するという問題があった。FIG. 5 shows a second conventional example of the acceleration sensor (Japanese Patent Laid-Open No. 2-116755). The basic configuration of the acceleration sensor is the same as that of the first conventional example, but the configuration of the electric drive type self-diagnosis unit is different. In this conventional example, there is no upper cap, and metal electrodes 7 and 8 for self-diagnosis are formed opposite to each other on the surface inside the recess 6 formed on the surface of the pedestal 18 and the bottom surface of the weight portion 3, respectively. Is configured. Usually, such a structure is manufactured by processing the pedestal 18 using Pyrex glass, and finally by anodic bonding with the silicon sensor chip 1. However, in this conventional example, as in the first conventional example, when the air gap between the metal electrodes 7 and 8 is narrowed, the air damping becomes too effective and the responsiveness of the acceleration sensor deteriorates.
【０００６】このエアダンピングによるセンサ応答性を
改善するようにした第３の従来例として、図６に示すよ
うな構成がある（特開平５−２６９０３号公報）。この
従来例ではシリコン台座５の凹部６内の面にエアダンピ
ング低減用の溝１９を形成し、この溝１９に沿って金属
電極７が形成されている。そして重り部３の変位時にエ
アギャップ内の気体を溝１９に逃すことにより通気抵抗
を低減させ、エアダンピングの低減効果を確保してい
る。しかし、この従来例では、溝１９に沿って金属電極
７が形成されているため、自己診断時の靜電力印加に寄
与する金属電極７の有効面積７は、溝１９部分以外の平
面部分が支配的となるために小さくなり、自己診断出力
が低下（即ち靜電力が低下）する。靜電力Ｆは次式で表
わされる。As a third conventional example for improving the sensor responsiveness by the air damping, there is a configuration as shown in FIG. 6 (Japanese Patent Laid-Open No. 5-26903). In this conventional example, a groove 19 for reducing air damping is formed on the surface inside the recess 6 of the silicon pedestal 5, and the metal electrode 7 is formed along the groove 19. Then, when the weight portion 3 is displaced, the gas in the air gap is released into the groove 19 to reduce the ventilation resistance, thereby ensuring the effect of reducing the air damping. However, in this conventional example, since the metal electrode 7 is formed along the groove 19, the effective area 7 of the metal electrode 7 that contributes to the application of the whistle power at the time of self-diagnosis is dominated by the planar portion other than the groove 19 portion. Therefore, the self-diagnosis output decreases (that is, the power consumption decreases). The static electric power F is expressed by the following equation.
【０００７】 Ｆ＝（１／２）ε・Ｓ・（Ｖ／ｄ）2 …（１） ここでεはエアギャップ部の誘電率、Ｓは金属電極の対
向面積、ｄはギャップ長、Ｖは印加電圧である。従っ
て、上記（１）式よりＳが減り、ｄが長くなるため靜電
力Ｆが低下することになる。F = (1/2) ε · S · (V / d) 2 (1) where ε is the permittivity of the air gap, S is the facing area of the metal electrode, d is the gap length, and V is The applied voltage. Therefore, since S is reduced and d is increased from the equation (1), the static electric power F is reduced.
【０００８】図７は、第３の従来例の製造工程を示して
いる。センサチップ１となるシリコンウェーハ上にＩＣ
製造プロセスを用いてピエゾ抵抗４及びその他必要な回
路デバイスを作り込む。ウェーハ裏面には耐エッチング
膜１１を形成し、パターニングすることにより、次工程
の異方性エッチングのマスクとする（ａ）。ウェーハ裏
面からのアルカリ性溶液を用いた異方性エッチングによ
り重り部３及び梁部２が形成される（ｂ）。シリコン台
座５の表面部にエッチングを施して凹部６を形成し、そ
の凹部６内に異方性エッチング等によりエアダンピング
低減用の溝１９を形成する（ｃ，ｄ）。凹部６内の溝１
９を含む部分に金属膜の蒸着、パターニングにより金属
電極７が形成される（ｅ）。センサチップ１とシリコン
台座５を接合して加速度センサが完成する（ｆ）。FIG. 7 shows a manufacturing process of the third conventional example. IC on the silicon wafer that becomes the sensor chip 1
The piezoresistor 4 and other necessary circuit devices are built using the manufacturing process. An etching resistant film 11 is formed on the back surface of the wafer and patterned to form a mask for anisotropic etching in the next step (a). The weight portion 3 and the beam portion 2 are formed by anisotropic etching from the back surface of the wafer using an alkaline solution (b). Etching is performed on the surface portion of the silicon pedestal 5 to form a recess 6, and a groove 19 for reducing air damping is formed in the recess 6 by anisotropic etching or the like (c, d). Groove 1 in recess 6
The metal electrode 7 is formed on the portion including 9 by vapor deposition and patterning of the metal film (e). The acceleration sensor is completed by joining the sensor chip 1 and the silicon pedestal 5 (f).
【０００９】[0009]
【発明が解決しようとする課題】第１、第２の従来例で
は、自己診断出力を大にするため自己診断用の両金属電
極間のエアギャップを狭くするとエアダンピングが効き
過ぎてセンサ応答性が劣化するという問題があった。ま
た、センサ応答性を改善するようにした第３の従来例で
は、自己診断用金属電極の形成領域にエアダンピング低
減用の溝を形成し、その溝に沿って金属電極を形成した
構成となっていたため、自己診断時の靜電力印加に寄与
する実効電極面積が減り、自己診断出力が低下するとい
う問題があった。そして自己診断出力を確保するために
は金属電極領域を広くする必要があるため、センサチッ
プが大型化してコスト高を招くという問題があった。In the first and second prior art examples, if the air gap between both metal electrodes for self-diagnosis is narrowed in order to increase the self-diagnosis output, the air damping becomes too effective and the sensor responsiveness is increased. There was a problem of deterioration. Further, in the third conventional example in which the sensor responsiveness is improved, a groove for reducing air damping is formed in the formation region of the self-diagnosis metal electrode, and the metal electrode is formed along the groove. Therefore, there is a problem that the effective electrode area that contributes to the application of the blue power during the self-diagnosis is reduced and the self-diagnosis output is reduced. Since it is necessary to widen the metal electrode area in order to secure the self-diagnosis output, there is a problem that the sensor chip becomes large and the cost increases.
【００１０】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、自己診断信号の高出力化及びセンサ
応答性の向上を図ることができるとともにチップサイズ
の大型化を招くことのない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. It is possible to increase the output of the self-diagnosis signal and improve the sensor responsiveness, and to increase the chip size. It is intended to provide a non-acceleration sensor.
【００１１】[0011]
【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、梁部及び該梁部で支持され被検
出加速度に応じて変位する重り部を有し、前記梁部の表
面部にピエゾ抵抗が形成された半導体チップと、該半導
体チップの下部に前記重り部と所要間隔のエアギャップ
を有するように接合された半導体製の台座とを備え、前
記エアギャップを挟んで対向する前記重り部及び台座の
対向両面にはそれぞれ電極が形成され、該両電極間への
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、前記両電極の少な
くとも一方に貫通孔を形成し、該電極に接する半導体部
には前記貫通孔を通してエッチング形成されたエアダン
ピング低減用の凹部を有することを要旨とする。In order to solve the above-mentioned problems, the present invention firstly comprises a beam portion and a weight portion supported by the beam portion and displaced according to a detected acceleration. A semiconductor chip having a piezoresistor formed on the surface of the portion, and a semiconductor pedestal joined to the weight portion at a lower portion of the semiconductor chip so as to have an air gap of a required distance, and sandwiching the air gap. An electrode is formed on each of the opposing surfaces of the weight portion and the pedestal that face each other, and an acceleration sensor configured to self-diagnose the sensor function by the whiskers generated by the voltage applied between the electrodes. A gist is that a through hole is formed in one side, and a semiconductor portion in contact with the electrode has a recess for reducing air damping, which is formed by etching through the through hole.
【００１２】第２に、梁部及び該梁部で支持され被検出
加速度に応じて変位する重り部を有し、前記梁部の表面
部にピエゾ抵抗が形成された半導体チップと、該半導体
チップの下部に前記重り部と所要間隔のエアギャップを
有するように接合された半導体製の台座とを備え、前記
エアギャップを挟んで対向する前記重り部及び台座の対
向両面にはそれぞれ電極が形成され、該両電極間への印
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、前記両電極の少なく
とも一方に複数個の貫通孔を所要間隔をおいて連設し、
該電極に接する半導体部には前記各貫通孔を通してエッ
チング形成された複数の凹部の連通により端部が当該電
極の端縁外に開口したエアダンピング低減用の溝を有す
ることを要旨とする。Secondly, a semiconductor chip having a beam portion and a weight portion supported by the beam portion and displaced according to a detected acceleration, and a piezoresistor is formed on a surface portion of the beam portion, and the semiconductor chip. A lower portion of the weight portion and a semiconductor pedestal joined so as to have an air gap of a required distance, and electrodes are formed on both facing surfaces of the weight portion and the pedestal that face each other with the air gap interposed therebetween. In the acceleration sensor configured to self-diagnose the sensor function by the static electricity generated by the applied voltage between the electrodes, a plurality of through holes are continuously provided at least one of the electrodes at a predetermined interval,
The gist of the present invention is that the semiconductor portion in contact with the electrode has a groove for reducing air damping, the end portion of which is open to the outside of the end edge of the electrode due to communication of a plurality of recesses formed by etching through the through holes.
【００１３】第３に、上記第２の構成において、前記エ
アダンピング低減用の溝は、複数個形成してなることを
要旨とする。Thirdly, the gist of the second structure is that a plurality of the air damping reducing grooves are formed.
【００１４】[0014]
【作用】上記構成において、第１に、電極に接する半導
体部には、貫通孔を通したサイドエッチが生じる程度の
エッチングにより貫通孔の径よりも十分に大きな径を有
する凹部空隙が形成される。加速度の検出時に重り部が
変位するとエアギャップ内の一部の気体が貫通孔を通し
て凹部内に出入りし、エアダンピングが緩和されてセン
サ応答性が向上する。自己診断時の靜電力印加に寄与す
る電極の有効面積は貫通孔部分は無効であるが、貫通孔
の穿設面積は両電極の対向全体面積に比べると無視でき
る程度なので自己診断信号は高出力に維持される。In the above structure, firstly, in the semiconductor portion in contact with the electrode, a recess void having a diameter sufficiently larger than the diameter of the through hole is formed by etching to the extent that side etching occurs through the through hole. . If the weight portion is displaced during the detection of acceleration, a part of the gas in the air gap enters and leaves the recess through the through hole, air damping is alleviated, and the sensor response is improved. The effective area of the electrode that contributes to the application of blue power during self-diagnosis is ineffective in the through-hole portion, but the drilled area of the through-hole is negligible compared to the total area of both electrodes facing each other, so the self-diagnosis signal has a high output. Maintained at.
【００１５】第２に、電極に接する半導体部には、連設
された複数の貫通孔を通してエッチング形成された各凹
部の連通によりその端部が電極の端縁外に開口した溝が
形成される。加速度の検出時に重り部が変位したとき、
エアギャップ内の気体は、各貫通孔を通して溝内に入り
両電極間の空隙外にぬける経路が形成されてエアダンピ
ングが緩和され、一層のセンサ応答性の改善が得られ
る。自己診断に際し、各貫通孔の全穿設面積は両電極の
対向全体面積に比べると、前記と同様に無視できる程度
なので自己診断信号は高出力に維持される。Secondly, in the semiconductor portion in contact with the electrode, a groove whose end is opened outside the edge of the electrode is formed by communicating the recesses formed by etching through a plurality of through holes provided in series. . When the weight is displaced during acceleration detection,
The gas in the air gap enters the groove through each through hole, and a path is formed through the air gap between the electrodes to alleviate the air damping, thereby further improving the sensor responsiveness. At the time of self-diagnosis, the total drilled area of each through hole is negligible in the same manner as described above as compared with the entire facing area of both electrodes, so the self-diagnosis signal is maintained at a high output.
【００１６】第３に、エアダンピング低減用の溝は、適
宜複数個が形成されることにより所望のエアダンピング
特性に応じることが可能となる。Thirdly, by appropriately forming a plurality of grooves for reducing air damping, it is possible to meet desired air damping characteristics.
【００１７】[0017]
【実施例】以下、本発明の実施例を図１乃至図３に基づ
いて説明する。なお、図１乃至図３において、前記図４
乃至図７における部材及び部位と同一ないし均等のもの
は、前記と同一符号を以って示し、重複した説明を省略
する。Embodiments of the present invention will be described below with reference to FIGS. In addition, in FIG. 1 to FIG.
The same or equivalent members and parts as those in FIG. 7 are designated by the same reference numerals as those used above, and a duplicate description will be omitted.
【００１８】まず図１、図２を用いて加速度センサの構
成を説明する。本実施例では、自己診断用の両金属電極
７，８のうち、シリコン台座５側の金属電極７に複数の
貫通孔９が複数列に、且つ各列においては所要間隔をお
いて連設されている。貫通孔９は金属電極７のパターニ
ング時に容易に形成することができ、従来に比べて工程
の増加や特殊技術の必要はない。そして各貫通孔９を通
したウェットエッチング法により、金属電極７に接する
半導体部に、その端部が当該金属電極７の端縁外に開口
１０ａとしたエアダンピング低減用の溝１０が形成され
ている。溝１０の形状寸法及び形成個数等は、エアダン
ピング特性によって任意に設定することができる。溝１
０の形成は、貫通孔９を有する金属電極７をシリコン台
座５の表面部に形成した後、貫通孔９以外をレジストで
マスキングし、ウェットエッチング法によって行われ
る。即ち、エッチング液が各貫通孔９を通して台座５の
シリコン部に達し、貫通孔９を中心に下方及び側方にエ
ッチングが進行して各貫通孔９の部分に凹部が形成さ
れ、さらにエッチングの進行により各凹部が連通してエ
アダンピング用の溝１０ができる。溝１０の深さや幅は
エッチング時間によって制御可能であり、５〜１０μｍ
程度の深さで十分である。貫通孔９の寸法はエッチング
液が入り込む程度でよく、直径２〜５μｍ程度である。
また、エアギャップ寸法ｄに対するこの貫通孔９の直径
φは、φ≧ｄ、溝１０の幅Ｗは、Ｗ≧２φが効果的な条
件である。First, the structure of the acceleration sensor will be described with reference to FIGS. In this embodiment, of the two metal electrodes 7 and 8 for self-diagnosis, the metal electrode 7 on the silicon pedestal 5 side is provided with a plurality of through-holes 9 in a plurality of rows and in each row at a required interval. ing. The through holes 9 can be easily formed at the time of patterning the metal electrode 7, and there is no need for an increase in the number of steps or a special technique as compared with the related art. Then, by a wet etching method through each through hole 9, a groove 10 for reducing air damping is formed in the semiconductor portion in contact with the metal electrode 7, the end portion of which is an opening 10a outside the end edge of the metal electrode 7. There is. The shape and the number of the grooves 10 to be formed can be arbitrarily set according to the air damping characteristics. Groove 1
The formation of 0 is performed by a wet etching method after forming the metal electrode 7 having the through hole 9 on the surface portion of the silicon pedestal 5 and masking the portions other than the through hole 9 with a resist. That is, the etching solution reaches the silicon portion of the pedestal 5 through each through hole 9, and the etching progresses downward and laterally around the through hole 9 to form a recess in each through hole 9, and the etching progresses further. Thus, the recesses communicate with each other to form the groove 10 for air damping. The depth and width of the groove 10 can be controlled by the etching time and is 5 to 10 μm.
Depth of a degree is sufficient. The size of the through hole 9 may be such that the etching liquid can enter, and has a diameter of about 2 to 5 μm.
Further, the effective condition is that the diameter φ of the through hole 9 with respect to the air gap dimension d is φ ≧ d and the width W of the groove 10 is W ≧ 2φ.
【００１９】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。自己診断用の金属電極７はシリコ
ン台座５表面に平面的に形成されている。自己診断時の
靜電力印加に寄与する金属電極７の有効面積は、貫通孔
９の部分は無効であるが、貫通孔９の穿設面積は両金属
電極７，８の対向全体面積に比べると無視できる程度な
ので、自己診断信号は高出力に維持される。Next, the operation of the acceleration sensor configured as described above will be described. The metal electrode 7 for self-diagnosis is formed flat on the surface of the silicon pedestal 5. The effective area of the metal electrode 7 that contributes to the application of the blue power at the time of self-diagnosis is ineffective at the portion of the through hole 9, but the drilled area of the through hole 9 is larger than the total area of the two metal electrodes 7 and 8 facing each other. Since it is negligible, the self-diagnosis signal is maintained at a high output.
【００２０】また、加速度検出の際には、重り部３の変
位によりエアギャップにある気体は各貫通孔９を通って
溝１０に入り開口部１０ａから両金属電極７，８間の空
隙外にぬける経路が形成される。したがってエアダンピ
ングが緩和され、センサ応答性を向上させることが可能
となる。When the acceleration is detected, the gas in the air gap due to the displacement of the weight 3 enters the groove 10 through each through hole 9 and enters the groove 10 from the opening 10a to the outside of the space between the metal electrodes 7 and 8. A passage is formed. Therefore, air damping is alleviated, and the sensor response can be improved.
【００２１】図３は、本実施例の製造工程を示してい
る。センサチップ１となるシリコンウェーハ上にＩＣ製
造プロセスを用いてピエゾ抵抗４及びその他必要な回路
デバイスを作り込む。ウェーハ裏面には耐エッチング膜
１１を形成し、パターニングすることにより、次工程の
異方性エッチングのマスクとする（ａ）。ウェーハ裏面
からのアルカリ性溶液を用いた異方性エッチングにより
重り部３及び梁部２を形成する（ｂ）。シリコン台座５
の表面に凹部６を形成し、その凹部６を含む部分に金属
膜を蒸着し、パターニングして金属電極７を形成する。
この時点で貫通孔９も同時に形成される（ｃ，ｄ）。パ
ターニングされた金属電極７をマスクにして貫通孔９か
らシリコン台座５にウェットエッチングを施し、エアダ
ンピング低減用の溝１０を形成する（ｅ）。センサチッ
プ１とシリコン台座５を接合して加速度センサを完成す
る（ｆ）。FIG. 3 shows the manufacturing process of this embodiment. A piezoresistor 4 and other necessary circuit devices are formed on a silicon wafer which will be the sensor chip 1 by using an IC manufacturing process. An etching resistant film 11 is formed on the back surface of the wafer and patterned to form a mask for anisotropic etching in the next step (a). The weight part 3 and the beam part 2 are formed by anisotropic etching from the back surface of the wafer using an alkaline solution (b). Silicon pedestal 5
The concave portion 6 is formed on the surface of the, and a metal film is deposited on the portion including the concave portion 6 and patterned to form the metal electrode 7.
At this point, the through hole 9 is also formed (c, d). Using the patterned metal electrode 7 as a mask, the silicon pedestal 5 is wet-etched through the through hole 9 to form a groove 10 for reducing air damping (e). The sensor chip 1 and the silicon pedestal 5 are joined to complete an acceleration sensor (f).
【００２２】上述の製造法によれば、貫通孔９が形成さ
れた金属電極７をマスクにしてエアダンピング低減用の
溝１０をセルフアライメントにより形成できるため、金
属電極７と溝１０の位置合わせが不要で精度よく形成で
きる。従って、位置合わせ余裕を予め見込む必要がなく
センサチップ１を小型化することが可能となる。According to the manufacturing method described above, the metal electrode 7 having the through hole 9 formed therein can be used as a mask to form the groove 10 for reducing air damping by self-alignment, so that the metal electrode 7 and the groove 10 can be aligned with each other. It is unnecessary and can be formed accurately. Therefore, it is possible to downsize the sensor chip 1 without preliminarily considering the alignment margin.
【００２３】なお、上述の実施例では、エアダンピング
低減用の溝１０を複数個形成したが、溝１０の個数はエ
アダンピング特性によって任意に設定することができ、
単１個でもよく、また溝に限らず単に凹部でもよい。さ
らに溝等はシリコン台座５側のみならず、重り部３側に
形成してもよい。Although a plurality of grooves 10 for reducing air damping are formed in the above-described embodiment, the number of grooves 10 can be arbitrarily set according to the air damping characteristics.
It may be a single piece, or may be a recess instead of a groove. Further, the groove or the like may be formed not only on the silicon pedestal 5 side but also on the weight portion 3 side.
【００２４】[0024]
【発明の効果】以上説明したように、本発明によれば、
第１に、自己診断用の両電極の少なくとも一方に貫通孔
を形成し、その電極に接する半導体部には前記貫通孔を
通してエッチング形成されたエアダンピング低減用の凹
部を設けたため、加速度の検出時に重り部が変位したと
きには、エアギャップ内の一部の気体が貫通孔を通して
凹部に出入りし、エアダンピングが緩和されてセンサ応
答性を向上させることができる。また自己診断時には、
靜電力印加に寄与する電極の有効面積の貫通孔部分は無
効であるが、貫通孔の穿設面積は両電極の対向全体面積
に比べると無視できる程度なので自己診断信号を高出力
に維持することができる。したがって自己診断出力を確
保するために電極領域を広くすることが不要となってチ
ップサイズの大型化を招くことがなく、コスト低減を図
ることができる。As described above, according to the present invention,
First, a through hole is formed in at least one of both electrodes for self-diagnosis, and a recess for reducing air damping formed by etching through the through hole is provided in a semiconductor portion in contact with the electrode. When the weight portion is displaced, a part of the gas in the air gap enters and leaves the recess through the through hole, air damping is alleviated, and the sensor response can be improved. Also, during self-diagnosis,
Although the through-hole part of the effective area of the electrode that contributes to the power application is ineffective, the drilled area of the through-hole is negligible compared to the total area of both electrodes facing each other, so the self-diagnosis signal should be kept at a high output. You can Therefore, it is not necessary to widen the electrode area to secure the self-diagnosis output, the chip size is not increased, and the cost can be reduced.
【００２５】第２に、自己診断用の両電極の少なくとも
一方に複数個の貫通孔を所要間隔をおいて連設し、その
電極に接する半導体部には前記各貫通孔を通してエッチ
ング形成された複数の凹部の連通により端部が当該電極
の端縁外に開口したエアダンピング低減用の溝を設けた
ため、加速度の検出時に重り部が変位したときには、エ
アギャップ内の気体は複数の貫通孔を通して溝内に入り
両電極間の空隙外にぬける経路が形成されてエアダンピ
ングが緩和される。したがって一層のセンサ応答性の改
善を図ることができる。また自己診断に際しては、複数
の貫通孔の全穿設面積は両電極の対向全体面積に比べる
と、前記と同様に無視できる程度なので自己診断信号を
高出力に維持することができる。Secondly, a plurality of through holes are continuously provided at least one of both electrodes for self-diagnosis at a predetermined interval, and a plurality of through holes are formed in the semiconductor portion in contact with the electrodes by etching. Since a groove for reducing air damping is provided whose end opens outside the edge of the electrode due to the communication of the recesses of the electrode, when the weight part is displaced when acceleration is detected, the gas in the air gap passes through a plurality of through holes. A path is formed which penetrates inside and goes out of the gap between the two electrodes, and air damping is alleviated. Therefore, the sensor response can be further improved. Further, in the self-diagnosis, the total area of the plurality of through-holes is negligible in the same manner as described above as compared with the total area of both electrodes facing each other, so that the self-diagnosis signal can be maintained at a high output.
【００２６】第３に、エアダンピング低減用の溝は、複
数個形成するようにしたため、所望のエアダンピング特
性に適切に応じることができる。Thirdly, since a plurality of grooves for reducing air damping are formed, it is possible to properly meet desired air damping characteristics.
【図１】本発明に係る加速度センサの実施例を示す縦断
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】図１におけるシリコン台座部の平面図である。FIG. 2 is a plan view of a silicon pedestal portion in FIG.
【図３】上記実施例の製造方法を示す工程図である。FIG. 3 is a process drawing showing the manufacturing method of the example.
【図４】加速度センサの第１の従来例を示す縦断面図で
ある。FIG. 4 is a vertical sectional view showing a first conventional example of an acceleration sensor.
【図５】第２の従来例を示す縦断面図である。FIG. 5 is a vertical sectional view showing a second conventional example.
【図６】第３の従来例を示す縦断面図である。FIG. 6 is a vertical sectional view showing a third conventional example.
【図７】上記第３の従来例の製造方法を示す工程図であ
る。FIG. 7 is a process drawing showing the manufacturing method of the third conventional example.
１ センサチップ（半導体チップ） ２ 梁 ３ 重り部 ４ ピエゾ抵抗 ５ シリコン台座 ７，８ 自己診断用の金属電極 ９ 貫通孔 １０ 溝 １０ａ 開口部 1 Sensor chip (semiconductor chip) 2 Beam 3 Weight part 4 Piezoresistive 5 Silicon pedestal 7,8 Metal electrode for self-diagnosis 9 Through hole 10 Groove 10a Opening
Claims (3)
に応じて変位する重り部を有し、前記梁部の表面部にピ
エゾ抵抗が形成された半導体チップと、該半導体チップ
の下部に前記重り部と所要間隔のエアギャップを有する
ように接合された半導体製の台座とを備え、前記エアギ
ャップを挟んで対向する前記重り部及び台座の対向両面
にはそれぞれ電極が形成され、該両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、前記両電極の少なくとも一
方に貫通孔を形成し、該電極に接する半導体部には前記
貫通孔を通してエッチング形成されたエアダンピング低
減用の凹部を有することを特徴とする加速度センサ。1. A semiconductor chip having a beam portion and a weight portion supported by the beam portion and displaced according to a detected acceleration, and a piezoresistor is formed on a surface portion of the beam portion, and a lower portion of the semiconductor chip. The weight portion and a semiconductor pedestal joined so as to have an air gap of a required distance, and electrodes are formed on both facing surfaces of the weight portion and the pedestal that face each other across the air gap. In an acceleration sensor in which the sensor function is self-diagnosed by the static electricity generated by the applied voltage between both electrodes, a through hole is formed in at least one of the both electrodes, and the through hole is provided in the semiconductor portion in contact with the electrode. An acceleration sensor having a recess for reducing air damping formed by etching.
に応じて変位する重り部を有し、前記梁部の表面部にピ
エゾ抵抗が形成された半導体チップと、該半導体チップ
の下部に前記重り部と所要間隔のエアギャップを有する
ように接合された半導体製の台座とを備え、前記エアギ
ャップを挟んで対向する前記重り部及び台座の対向両面
にはそれぞれ電極が形成され、該両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、前記両電極の少なくとも一
方に複数個の貫通孔を所要間隔をおいて連設し、該電極
に接する半導体部には前記各貫通孔を通してエッチング
形成された複数の凹部の連通により端部が当該電極の端
縁外に開口したエアダンピング低減用の溝を有すること
を特徴とする加速度センサ。2. A semiconductor chip having a beam portion and a weight portion supported by the beam portion and displaced according to a detected acceleration, and a piezoresistor is formed on a surface portion of the beam portion, and a lower portion of the semiconductor chip. The weight portion and a semiconductor pedestal joined so as to have an air gap of a required distance, and electrodes are formed on both facing surfaces of the weight portion and the pedestal that face each other across the air gap. In an acceleration sensor in which the sensor function is self-diagnosed by the static electricity generated by the applied voltage between both electrodes, a plurality of through holes are continuously provided at least one of the electrodes at a predetermined interval, and the electrodes are connected to the electrodes. The contacting semiconductor portion has a groove for reducing air damping, the end portion of which is opened to the outside of the end edge of the electrode due to communication of the plurality of recesses formed by etching through the through holes. Sensor.
個形成してなることを特徴とする請求項２記載の加速度
センサ。3. The acceleration sensor according to claim 2, wherein a plurality of the air damping reducing grooves are formed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5328548A JP3019701B2 (en) | 1993-12-24 | 1993-12-24 | Acceleration sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5328548A JP3019701B2 (en) | 1993-12-24 | 1993-12-24 | Acceleration sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07191056A true JPH07191056A (en) | 1995-07-28 |
| JP3019701B2 JP3019701B2 (en) | 2000-03-13 |
Family
ID=18211514
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5328548A Expired - Fee Related JP3019701B2 (en) | 1993-12-24 | 1993-12-24 | Acceleration sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3019701B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008517786A (en) * | 2004-10-27 | 2008-05-29 | コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ | Reduction of air braking in MEMS devices |
| CN112255090A (en) * | 2020-11-13 | 2021-01-22 | 深圳信息职业技术学院 | Variable-hammer-face digital knocking hammer and composite material detection method |
| US20210132632A1 (en) * | 2019-10-31 | 2021-05-06 | Seiko Epson Corporation | Physical quantity sensor, electronic apparatus, and vehicle |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10403527B2 (en) * | 2013-08-01 | 2019-09-03 | Miraial Co., Ltd. | Packing structure for packing substrate storing container |
-
1993
- 1993-12-24 JP JP5328548A patent/JP3019701B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008517786A (en) * | 2004-10-27 | 2008-05-29 | コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ | Reduction of air braking in MEMS devices |
| US20210132632A1 (en) * | 2019-10-31 | 2021-05-06 | Seiko Epson Corporation | Physical quantity sensor, electronic apparatus, and vehicle |
| CN112255090A (en) * | 2020-11-13 | 2021-01-22 | 深圳信息职业技术学院 | Variable-hammer-face digital knocking hammer and composite material detection method |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3019701B2 (en) | 2000-03-13 |
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