JPH0536737B2 - - Google Patents
Info
- Publication number
- JPH0536737B2 JPH0536737B2 JP59235824A JP23582484A JPH0536737B2 JP H0536737 B2 JPH0536737 B2 JP H0536737B2 JP 59235824 A JP59235824 A JP 59235824A JP 23582484 A JP23582484 A JP 23582484A JP H0536737 B2 JPH0536737 B2 JP H0536737B2
- Authority
- JP
- Japan
- Prior art keywords
- diaphragm
- hole
- differential pressure
- vibrating
- pressure 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.)
- Expired - Lifetime
Links
- 239000000463 material Substances 0.000 claims description 5
- 238000005530 etching Methods 0.000 claims description 4
- 239000004065 semiconductor Substances 0.000 claims description 2
- 239000000758 substrate Substances 0.000 description 8
- 238000009792 diffusion process Methods 0.000 description 6
- 229910052710 silicon Inorganic materials 0.000 description 6
- 239000010703 silicon Substances 0.000 description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
- 238000001514 detection method Methods 0.000 description 3
- 230000007935 neutral effect Effects 0.000 description 3
- 230000035945 sensitivity Effects 0.000 description 3
- 239000012535 impurity Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 239000007767 bonding agent Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 150000003376 silicon Chemical class 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/0001—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means
- G01L9/0008—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means using vibrations
- G01L9/0019—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means using vibrations of a semiconductive element
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Fluid Pressure (AREA)
Description
【発明の詳細な説明】
＜産業上の利用分野＞
本発明はダイアフラムに生ずる差圧に対応した
力を、周波数信号として出力する差圧センサに関
し、シリコンのような半導体基板を使用し、この
基板上に振動梁を形成させた構造の差圧センサに
関するものである。[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a differential pressure sensor that outputs a force corresponding to a differential pressure generated in a diaphragm as a frequency signal. The present invention relates to a differential pressure sensor having a structure on which a vibrating beam is formed.
＜従来例＞
測定圧力をダイアフラムで受け、ダイアフラム
に生ずる力をダイアフラム上に設けたストレンゲ
ージで検出し、電気信号に変換する差圧センサは
公知で、既に広く実用化されている。<Conventional Example> A differential pressure sensor that receives measured pressure with a diaphragm, detects the force generated on the diaphragm with a strain gauge provided on the diaphragm, and converts it into an electrical signal is well known and has already been widely put into practical use.
このような差圧センサにおいて、ストレンゲー
ジは測定すべき力に応じたアナログ的な抵抗値変
化を示し、出力値も小さい。この為に、出力信号
をコンピユータ等で信号処理する場合、増幅した
りＡ／Ｄ変換しなければならない。 In such a differential pressure sensor, the strain gauge exhibits an analog resistance value change according to the force to be measured, and its output value is also small. For this reason, when the output signal is processed by a computer or the like, it must be amplified or A/D converted.
差圧に対応した周波数信号を得る方式の差圧セ
ンサも、例えば特開昭54−56880号公報に見られ
るように公知である。この装置はダイアフラムに
生ずる力を、ダイアフラムに結合した振動線に与
え、振動線の張力に関連した固有振動数の変化を
周波数信号出力として得るものである。 A differential pressure sensor that obtains a frequency signal corresponding to the differential pressure is also known, as seen in, for example, Japanese Patent Laid-Open No. 54-56880. This device applies a force generated on a diaphragm to a vibrating wire coupled to the diaphragm, and obtains a change in natural frequency related to the tension of the vibrating wire as a frequency signal output.
この装置においては、ダイアフラムに生ずる力
を正確に振動線に伝えられるように両者間を結合
する必要があること、振動線周囲の環境変化が振
動線の固有振動数の変化とならない構成を工夫す
る必要がある等構成が複雑になるという問題があ
つた。 In this device, it is necessary to connect the two so that the force generated in the diaphragm can be accurately transmitted to the vibration line, and a configuration must be devised so that changes in the environment around the vibration line will not cause changes in the natural frequency of the vibration line. There was a problem that the configuration was complicated.
＜発明の目的＞
本発明は上記従来技術の問題点に鑑みてなされ
たもので、差圧に対応した周波数信号を出力する
構成の簡単な差圧センサを提供することを目的と
する。<Object of the Invention> The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to provide a differential pressure sensor with a simple configuration that outputs a frequency signal corresponding to a differential pressure.
＜発明の構成＞
この目的を達成する本発明の構成は、弾性を有
する半導体材料で構成した第１のダイアフラムの
表面に、エツチングおよびアンダエツチングの手
法により、一方が閉塞し他方が開放した穴と、こ
の穴の縁部より下方に両端が固定された振動梁を
設け、前記第１のダイアフラムの穴を有する側
に、前記第１のダイアフラムと同等の材質で、か
つ、略同一の厚さを有する第２のダイアフラムを
接合するとともに前記穴を真空にし、前記第１の
ダイアフラムに設けた振動梁の励振手段と振動検
出手段を具備したことを構成上の特徴とするもの
である。<Structure of the Invention> The structure of the present invention that achieves this object is to form holes, one of which is closed and the other of which is open, on the surface of the first diaphragm made of an elastic semiconductor material by etching and under-etching techniques. A vibrating beam fixed at both ends is provided below the edge of the hole, and a vibrating beam made of the same material and having approximately the same thickness as the first diaphragm is provided on the side of the first diaphragm having the hole. The second diaphragm is joined to the second diaphragm, the hole is evacuated, and the vibration beam excitation means and vibration detection means provided on the first diaphragm are provided.
＜実施例＞
第１図は本発明に係る差圧センサの全体構成を
示す斜視図、第２図は第１図に示す差圧センサの
要部（一点鎖線で囲つたＡ部分）を示す断面拡大
斜視図である。これらの図において、１は第１の
ダイアフラムであり、例えば不純物濃度1015／cm3
以下のｐ形のシリコン基板である。このシリコン
基板１の表面には部分的に不純物濃度1018／cm3程
度のn+拡散層２ａ，２ｂ，２ｃを形成し、この
拡散層を所定の厚さに部分的にエツチングして第
１の穴３を形成する。次に第１の穴３のなかの
n+拡散層２ｂの部分を棒状にエツチングすると
ともに基板であるｐ層をアンダエツチングして第
２の穴５を形成し、n+層からなる振動梁４を形
成する。６は振動梁４の振動を最も感じる部分
（図では梁のの両端）に拡散やエピタキシヤル成
長により形成したp+層である。このp+層６は図
示しないリード線等により基板であるｐ層１とは
絶縁して外部に取り出され、n+拡散層である振
動梁４上でpn接合を形成する。７は第１のダイ
アフラムと同等の材質を有する第２のダイアフラ
ムで、この第２のダイアフラムと第１のダイアフ
ラムは真空中において陽極接合することにより、
第１の穴と第２の穴は真空状態となる。８は接合
剤および絶縁剤として機能する例えばSiO2膜で
ある。<Example> Fig. 1 is a perspective view showing the overall configuration of the differential pressure sensor according to the present invention, and Fig. 2 is a cross section showing the main part of the differential pressure sensor shown in Fig. 1 (portion A surrounded by a chain line). It is an enlarged perspective view. In these figures, 1 is the first diaphragm, for example, with an impurity concentration of 10 15 /cm 3
The following p-type silicon substrate is used. On the surface of this silicon substrate 1, n + diffusion layers 2a, 2b, 2c with an impurity concentration of about 10 18 /cm 3 are formed, and these diffusion layers are partially etched to a predetermined thickness to form a first layer. hole 3 is formed. Next, in the first hole 3
The n + diffusion layer 2b is etched into a rod shape and the p layer serving as the substrate is underetched to form a second hole 5, thereby forming the vibrating beam 4 made of the n + layer. Reference numeral 6 denotes a p + layer formed by diffusion or epitaxial growth at the part where the vibration of the vibrating beam 4 is most felt (in the figure, at both ends of the beam). This p + layer 6 is insulated from the p layer 1 which is a substrate and taken out to the outside by a lead wire (not shown) or the like, and forms a pn junction on the vibrating beam 4 which is an n + diffusion layer. A second diaphragm 7 is made of the same material as the first diaphragm, and the second diaphragm and the first diaphragm are anodically bonded in a vacuum.
The first hole and the second hole are in a vacuum state. 8 is, for example, a SiO 2 film that functions as a bonding agent and an insulating agent.
上記構成において第１のダイアフラム１と第２
のダイアフラム７の厚さを略等しくすれば、接合
面が中立面となるので、ダイアフラムに発生する
応力は中立面で最小となり、接合によつて発生す
る応力の影響をほとんど零にすることができる。
また、振動梁４が形成された部分の静圧に対する
耐圧は、第３図に示す穴の幅2l3と、ダイアフラ
ム膜の厚さl4との比l4／l3を十分大きくすること
によつて解決することができる。例えば、l3＝
3μm、l4＝3μmとし、シリコンの最大応力を10Kg
ｆ／mm2とすると、耐圧P0は
P0＝（l4／l3）2・σmax＝1000Kgｆ／cm2となる。 In the above configuration, the first diaphragm 1 and the second diaphragm
If the thicknesses of the diaphragms 7 are made approximately equal, the bonding surface becomes the neutral plane, so the stress generated in the diaphragm is minimized at the neutral plane, and the influence of stress generated by bonding can be reduced to almost zero. I can do it.
In addition, the withstand pressure against static pressure in the part where the vibrating beam 4 is formed is determined by making the ratio l 4 /l 3 of the width of the hole 2l 3 and the thickness of the diaphragm membrane l 4 sufficiently large as shown in Fig. 3 . This can be solved. For example, l 3 =
3μm, l 4 = 3μm, and the maximum stress of silicon is 10Kg.
f/mm 2 , the breakdown voltage P 0 is P 0 =(l 4 /l 3 ) 2 ·σmax=1000Kgf/cm 2 .
一方、梁の軸方向への静圧による歪みはl3／Ｒ
（Ｒはダイアフラムの半径…第１図参照）を十分
小さくすることにより無視することができる。な
お、これらの加工はフオトリソグラフイの技術を
用いることにより可能である。 On the other hand, the strain due to static pressure in the axial direction of the beam is l 3 /R
(R is the radius of the diaphragm...see FIG. 1) can be ignored by making it sufficiently small. Note that these processes are possible by using photolithography technology.
上記構成の差圧センサを、図示しない固定手段
により固定し、ダイアフラムの両側から圧力を加
える。そして、第１のダイアフラムであるｐ層に
負のバイアスを印加しておき、振動梁の端部に形
成されたpn接合部からダイアフラムの歪みによ
る振動歪み信号を検出する。この歪信号を増幅し
て第１のダイアフラム１に正帰還させると、振動
梁は静電力によりその固有振動数で励振する。こ
の振動はダイアフラムに加わつた差圧に応じて変
化し、その歪み感度Ｓ＝Δf／f0は次式で与えられ
る。 The differential pressure sensor configured as described above is fixed by a fixing means (not shown), and pressure is applied from both sides of the diaphragm. Then, a negative bias is applied to the p-layer, which is the first diaphragm, and a vibration distortion signal due to distortion of the diaphragm is detected from the pn junction formed at the end of the vibrating beam. When this strain signal is amplified and fed back positively to the first diaphragm 1, the vibrating beam is excited at its natural frequency due to electrostatic force. This vibration changes according to the differential pressure applied to the diaphragm, and its strain sensitivity S=Δf/f 0 is given by the following equation.
Ｓ＝Δf／f0
＝0.118・（l1／l2）2・ε…
ここで、
式はシリコンの物理定数から理論および実験
により求めた式、εは歪みである。 S=Δf/f 0 =0.118·(l 1 /l 2 ) 2 ·ε… Here, the expression is an expression obtained by theory and experiment from the physical constants of silicon, and ε is the strain.
この、歪による振動梁４の振動周波数の変化は
図示しない公知の振動検出手段により検出され
る。 This change in the vibration frequency of the vibrating beam 4 due to strain is detected by a known vibration detection means (not shown).
このように構成した装置によれば、受圧ダイア
フラム中に真空状態で振動梁を形成したので、理
想的な弾性特性を得ることができ、Ｑが高く安定
したモノリシツクセンサを実現することができ
る。 According to the device configured in this way, since the vibrating beam is formed in the pressure receiving diaphragm in a vacuum state, ideal elastic characteristics can be obtained, and a stable monolithic sensor with a high Q can be realized.
なお、上記実施例においては第１のダイアフラ
ムをｐ形のシリコン基板としたが、この基板をｎ
形とし、このｎ形基板の上にｐ層を拡散してｐ形
の梁を形成しその上に振動検出のためのダイオー
トを形成してもよい。また、振動梁は１つに限る
ものではなく、例えばダイアフラムの中央部にも
う１つの振動梁を形成しその差を演算する様にす
れば感度を２倍にすることができるとともに、温
度変化による熱歪みをキヤンセルすることができ
る。 In the above embodiment, the first diaphragm was made of a p-type silicon substrate, but this substrate was replaced with an n-type silicon substrate.
A p-layer may be diffused onto this n-type substrate to form a p-type beam, and a diode for vibration detection may be formed on the beam. Also, the number of vibrating beams is not limited to one; for example, if another vibrating beam is formed in the center of the diaphragm and the difference is calculated, the sensitivity can be doubled, and the sensitivity Thermal distortion can be canceled.
さらに、ダイアフラムの形状は円形以外の他の
形状にすることも可能である。 Furthermore, the shape of the diaphragm can be other than circular.
＜発明の効果＞
以上、実施例とともに具体的に説明したように
本発明によれば、振動梁を穴の縁部から下の方に
形成しているのでダイアフラムに生ずる引張り／
圧縮の力を軸力（振動子の軸方向の力）として正
確に伝えることができる。また、穴の蓋となる第
２のダイアフラムを接合する場合に、その第２の
ダイアフラムの形状は単に平板状のもので良いの
で加工が簡単である。また第１、第２のダイアフ
ラムの厚さを略同一にしているので接合面が中立
面となりダイアフラムに発生する応力を最小にす
ることができる。更にダイアフラムの接合に際し
ては真空中で行つて振動梁を真空中に配置してい
るのでＱが高く安定な周波数信号を出力すること
ができ、かつ、構成の簡単なセンサを実現するこ
とができる。<Effects of the Invention> As described above in detail with the embodiments, according to the present invention, the vibration beam is formed downward from the edge of the hole, so that the tension generated in the diaphragm is reduced.
Compression force can be accurately transmitted as axial force (force in the axial direction of the vibrator). Furthermore, when joining the second diaphragm that serves as a cover for the hole, the second diaphragm can be simply shaped like a flat plate, so that processing is easy. Further, since the thicknesses of the first and second diaphragms are made substantially the same, the joint surface becomes a neutral plane, and stress generated in the diaphragm can be minimized. Furthermore, since the diaphragm is bonded in a vacuum and the vibrating beam is placed in a vacuum, a stable frequency signal with a high Q can be output, and a sensor with a simple configuration can be realized.
第１図は本発明に係る差圧センサの全体構成を
示す斜視図、第２図は第１図に示す差圧センサの
要部を示す断面拡大斜視図、第３図は梁形成部に
おけるダイアフラムの厚さと幅の関係を示す図で
ある。
１…第１のダイアフラム、２ａ〜２ｃ…拡散
層、３，５…穴、４…振動梁、７…第２のダイア
フラム。
Fig. 1 is a perspective view showing the overall configuration of a differential pressure sensor according to the present invention, Fig. 2 is an enlarged cross-sectional perspective view showing main parts of the differential pressure sensor shown in Fig. 1, and Fig. 3 is a diaphragm in a beam forming part. It is a figure which shows the relationship between the thickness and width of. DESCRIPTION OF SYMBOLS 1... First diaphragm, 2a-2c... Diffusion layer, 3, 5... Hole, 4... Vibration beam, 7... Second diaphragm.
Claims (1)
イアフラムの表面に、エツチングおよびアンダエ
ツチングの手法により、一方が閉塞し他方が解放
した穴と、この穴の縁部より下方に両端が固定さ
れた振動梁を設け、前記第１のダイアフラムの穴
を有する側に、前記第１のダイアフラムと同等の
材質で、かつ、略同一の厚さを有する第２のダイ
アフラムを接合するとともに前記穴を真空にし、
前記第１のダイアフラムに設けた振動梁の振動手
段と振動検出手段を具備したことを特徴とする差
圧センサ。1 A hole is formed on the surface of the first diaphragm made of an elastic semiconductor material by etching and under-etching, one side of which is closed and the other side is open, and a vibrator whose both ends are fixed below the edge of this hole. providing a beam, joining a second diaphragm made of the same material and having substantially the same thickness as the first diaphragm to the side of the first diaphragm having the hole, and evacuating the hole;
A differential pressure sensor comprising a vibrating means for a vibrating beam provided on the first diaphragm and a vibration detecting means.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23582484A JPS61114139A (en) | 1984-11-08 | 1984-11-08 | Differential pressure sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23582484A JPS61114139A (en) | 1984-11-08 | 1984-11-08 | Differential pressure sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61114139A JPS61114139A (en) | 1986-05-31 |
| JPH0536737B2 true JPH0536737B2 (en) | 1993-05-31 |
Family
ID=16991800
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23582484A Granted JPS61114139A (en) | 1984-11-08 | 1984-11-08 | Differential pressure sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61114139A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2824636B1 (en) * | 2001-05-10 | 2003-09-05 | Schlumberger Services Petrol | MICROELECTRONIC PRESSURE SENSOR WITH RESONATOR SUPPORTING HIGH PRESSURES |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5526487A (en) * | 1978-05-30 | 1980-02-25 | Itt | Pressure converter and producing same |
-
1984
- 1984-11-08 JP JP23582484A patent/JPS61114139A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5526487A (en) * | 1978-05-30 | 1980-02-25 | Itt | Pressure converter and producing same |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61114139A (en) | 1986-05-31 |
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