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WO1997030356A1 - Dispositif de detection d'une rupture de la masse inertielle dans un accelerometre - Google Patents

Dispositif de detection d'une rupture de la masse inertielle dans un accelerometre Download PDF

Info

Publication number
WO1997030356A1
WO1997030356A1 PCT/US1996/001915 US9601915W WO9730356A1 WO 1997030356 A1 WO1997030356 A1 WO 1997030356A1 US 9601915 W US9601915 W US 9601915W WO 9730356 A1 WO9730356 A1 WO 9730356A1
Authority
WO
WIPO (PCT)
Prior art keywords
inner plate
hinge
sensor device
plate
semiconductor sensor
Prior art date
Application number
PCT/US1996/001915
Other languages
English (en)
Inventor
Douglas W. Wilda
Max C. Glenn
Original Assignee
Honeywell Inc.
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 Honeywell Inc. filed Critical Honeywell Inc.
Priority to PCT/US1996/001915 priority Critical patent/WO1997030356A1/fr
Publication of WO1997030356A1 publication Critical patent/WO1997030356A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P21/00—Testing or calibrating of apparatus or devices covered by the preceding groups

Definitions

  • the present invention relates to the field of instruments for measuring linear acceleration, and more particularly, to semiconductor accelerometers having a beam subject to stress as a result of the acceleration forces acting thereon and using piezoresistive elements for sensing changes in the stress.
  • Silicon accelerometers of the forementioned type have a failure mode which is difficult to detect.
  • the hinge or beam
  • the present invention provides a positive indication of the failure and failure mode of the silicon accelerometer.
  • a conductor is disposed across the hinge of the silicon chip (the potential rupture site), such that a circuit utilizing the conductor changes its operating characteristic dramatically in the case of a beam rupture thereby providing a positive indication of the failure mode, i.e., the rupture.
  • an apparatus for detecting a rupture of a beam of a semiconductor accelerometer measures a force along a sensitive axis, the force being exerted thereon as a result of an acceleration of the semiconductor sensor device along the sensitive axis.
  • the semiconductor sensor device comprises a flexure member having an inner plate and an outer plate.
  • the inner plate is separated from the outer plate by a groove around the periphery of the inner plate, except by at least one hinge for connecting the inner plate to the outer plate.
  • the hinges are at predetermined locations around the periphery of the inner plate.
  • the sensitive axis of the semiconductor sensor device is perpendicular to the inner plate.
  • Stain sensitive elements are disposed on at least one of the hinges for providing an output signal deviation in accordance with the deviation of the inner plate as a result of the force acting on the inner plate along the sensitive axis.
  • a diagnostic conductor is disposed on the semiconductor sensor device from a first predetermined point of the outer plate across the hinge to the inner plate and back across the hinge to a second predetermined point of the outer plate whereby the conductivity of the diagnostic conductor is measured between the first and second predetermined points of the outer plate to indicate a rupture of the hinge. Accordingly, it is an object of the present invention to provide an apparatus for detecting a rupture of a beam of a semiconductor accelerometer.
  • Figure 1 shows a flexure member of a silicon accelerometer
  • Figure 2 shows an isometric view of the flexure member of Figure 1
  • Figure 3 shows a circuit diagram of micro circuitry disposed on the semiconductor material of the silicon accelerometer of the preferred embodiment of the present invention, including a strain bridge;
  • Figure 4 shows a cross-sectional view of the flexures (or hinges) of Figure 1 ;
  • Figure 5 shows an expanded top view of the flexures of the preferred embodiment of the present invention of the flexures of Figure 1; and
  • Figure 6 shows a configuration of an alternative embodiment for a diagnostic conductor.
  • a flexure member 63 of a semiconductor accelerometer (not shown).
  • the flexure member 63 is a thin semiconductor material having an inner plate or pendulum 68 connected to an outer supporting or mounting plate 88 at flexures 69.
  • an isometric view of the flexure member 63 is shown in Figure 2.
  • the flexure member 63 is a sheet or substrate of single crystal p-silicon of the desired diameter and is cut and polished to a desired thickness, for example 15 mils. From one face of this substrate is epitiaxially grown an etch-stop layer n-silicon about 1 mil in thickness.
  • a circular groove 91 separates outer plate or ring 88 from inner plate or disk 68.
  • Groove 91 is etched until the groove 91 becomes a slot passing entirely through the material thereby separating pendulum 68 from plate 88, the slot being enlarged at 96 to provide a passage way through member 63 for the positive and negative current leads 97 and 98, a ground lead 99, and an output conductor 100, all shown in Figure 3.
  • circle 102 shows the outer diameter of the other elements and circle 103 shows the inner diameter of damping rings (not shown).
  • the surface of pendulum 68 readily outward from line 101 is available for applications of large scale integrated circuitry making up components 77-79, 89 and 90 of Figure 3 which will be described below.
  • the pendulum 68 is supported by the outer ring 88 at flexures 69.
  • a portion of a strain bridge is applied to flexures 69 is shown greatly enlarged in Figure 4.
  • the heavily doped substrate is shown at 110, the epitaxially grown layer at 111 and the groove at 112.
  • a first layer 120 and the second layer 121 of impurity boron are implanted to the opposite surfaces of the flexure 69 to form strain sensitive resistance elements.
  • FIG. 3 there is shown a circuit diagram of the micro circuitry mentioned above, which includes a strain bridge 76, a preamplifier 77, a summing amplifier 78, a driving amplifier 79, and a readout resistor 80.
  • Bridge 76 includes four strain sensitive resistors 81, 82, 83, and 84, connected in a bridge circuit and having input terminals 85 and 86, energized with direct current, and output terminals 87 and 88, giving a direct current bridge signal representative of the deviation of the pendulum at its flexures from its mechanical null.
  • the bridge signal is amplified in preamplifier 77.
  • the deviation of the pendulum measured at its flexures 69 is related to the forces acting on the pendulum 68 as a result of acceleration measured in the direction of the axis 22.
  • FIG. 5 there is shown view A of Figure 1 , which is an enlarged diagram of the flexure 69.
  • the topside of the flexure 69 includes a piezo resistor Rl 81.
  • This resistor 81 is disposed on the surface 121 of the flexure 69 in a manner well know to those skilled in the art.
  • the resistor 81 is connected to bonding pads 85, 87 via conductors 201.
  • resistor 82 is disposed on the underside of flexure 69 on surface 120, and also in a like fashion resistors R3 and R4 83, 84 are disposed on the other flexure 69.
  • resistive element R5 25 is placed on the outer ring 88 to measure temperature of the substrate 63 thereby providing inputs to permit temperature compensation of the resistor elements R1-R4 81-84 with respect to temperature.
  • Resistor R5 is one resistor out of four of an external Wheatstone bridge i.e., a Wheatstone bridge having the three other resistive elements external to the flexure element 63 and thus insensitive to the flexure temperature.
  • an external Wheatstone bridge i.e., a Wheatstone bridge having the three other resistive elements external to the flexure element 63 and thus insensitive to the flexure temperature.
  • This positive indication is an effective diagnostic indication.
  • the diagnostic conductor 45 associated with resistor R5 which crosses the beam can be utilized to connect that external element and the conductivity of the diagnostic conductor 45 measured in many ways well known to those skilled in the art.
  • the semiconductor accelerometer can have various configurations including single or multiple (more than two) beams.
  • the diagnostic conductor 45 can be configured such that it crossed a first hinge 69 once from the outer plate 88 to the pendulum 68 and has a return path across a second hinge 69 to the outer plate.
  • Bonding posts on the outer plate 88 can then be utilized to connect the diagnostic conductor 45 to a temperature compensation resistor 25, and can be connected to external circuitry (not shown) to measure the conductivity of the diagnostic conductor 45 for an indication of hinge rupture.
  • the diagnostic conductor 45 can have many configurations depending on a number of factors, including the number of hinges,.... While there has been shown what is considered the preferred embodiment of the present invention, it will be manifest that any changes and modifications can be made therein without departing from the essential spirit and scope of the invention. It is intended, therefore, in the annexed claims to cover all such changes and modifications which fall within the true scope of the invention.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Pressure Sensors (AREA)

Abstract

L'invention porte sur un capteur à semi-conducteur mesurant la force s'exerçant sur lui du fait de son accélération le long d'un axe sensible. Ledit capteur comprend un élément élastique comportant une plaque extérieure (88) et une plaque intérieure (68) séparées l'une de l'autre par une rainure (91) pratiquée à la périphérie de la plaque intérieure sauf au niveau d'au moins l'une des charnières reliant la plaque intérieur à la plaque extérieure. Les charnières (69) sont placées en des points prédéterminés de la périphérie de la plaque extérieure. Des éléments dynamométriques (81) placés sur l'un au moins des charnières fournissent un signal de déviation fonction de la déviation de la plaque intérieure sous l'effet d'une force agissant sur elle. Un conducteur (45) servant au diagnostic, intégré au capteur, relie un premier point donné de la plaque extérieure à la plaque intérieure en traversant la charnière puis à un second point donné de la plaque extérieure, en retraversant la charnière. La mesure de la conductivité entre les deux points de la plaque extérieure permet de déceler une rupture de la charnière.
PCT/US1996/001915 1996-02-15 1996-02-15 Dispositif de detection d'une rupture de la masse inertielle dans un accelerometre WO1997030356A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/US1996/001915 WO1997030356A1 (fr) 1996-02-15 1996-02-15 Dispositif de detection d'une rupture de la masse inertielle dans un accelerometre

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1996/001915 WO1997030356A1 (fr) 1996-02-15 1996-02-15 Dispositif de detection d'une rupture de la masse inertielle dans un accelerometre

Publications (1)

Publication Number Publication Date
WO1997030356A1 true WO1997030356A1 (fr) 1997-08-21

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1996/001915 WO1997030356A1 (fr) 1996-02-15 1996-02-15 Dispositif de detection d'une rupture de la masse inertielle dans un accelerometre

Country Status (1)

Country Link
WO (1) WO1997030356A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2775072A1 (fr) * 1998-02-18 1999-08-20 Telefunken Microelectron Capteur a parties mobile et fixe reliees par une barrette
US7350424B2 (en) * 2002-02-12 2008-04-01 Nokia Corporation Acceleration sensor

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4498342A (en) * 1983-04-18 1985-02-12 Honeywell Inc. Integrated silicon accelerometer with stress-free rebalancing
EP0171056A2 (fr) * 1984-08-08 1986-02-12 Texas Instruments Deutschland Gmbh Capteur répondant à l'effet dynamique
DE3814949C1 (fr) * 1988-05-03 1989-08-03 Robert Bosch Gmbh, 7000 Stuttgart, De
DE4344284A1 (de) * 1992-12-25 1994-06-30 Mitsubishi Electric Corp Halbleiter-Beschleunigungsmeßvorrichtung
DE4324692A1 (de) * 1993-07-23 1995-01-26 Bosch Gmbh Robert Piezoelektrischer Kraftsensor

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4498342A (en) * 1983-04-18 1985-02-12 Honeywell Inc. Integrated silicon accelerometer with stress-free rebalancing
EP0171056A2 (fr) * 1984-08-08 1986-02-12 Texas Instruments Deutschland Gmbh Capteur répondant à l'effet dynamique
DE3814949C1 (fr) * 1988-05-03 1989-08-03 Robert Bosch Gmbh, 7000 Stuttgart, De
DE4344284A1 (de) * 1992-12-25 1994-06-30 Mitsubishi Electric Corp Halbleiter-Beschleunigungsmeßvorrichtung
DE4324692A1 (de) * 1993-07-23 1995-01-26 Bosch Gmbh Robert Piezoelektrischer Kraftsensor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2775072A1 (fr) * 1998-02-18 1999-08-20 Telefunken Microelectron Capteur a parties mobile et fixe reliees par une barrette
US7350424B2 (en) * 2002-02-12 2008-04-01 Nokia Corporation Acceleration sensor

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