Acceleration sensor and method for manufacturing same
First Claim
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1. An acceleration sensor comprising:
- a silicon-on-insulator substrate having a monocrystalline silicon layer and an insulator layer;
a proof mass consisting of silicon doped so as to be electrically conductive and at least one resilient element formed in said silicon layer, said at least one resilient element extending between and electrically connecting said proof mass and a remainder of said silicon layer;
said insulator layer having an opening therein in which said proof mass and said at least one resilient element are disposed, said proof mass and said at least one resilient element being freely movable within said opening; and
said substrate having a plurality of regions disposed opposite said proof mass which are doped so as to be electrically conductive, said proof mass and said regions of said substrate forming, in combination, a plurality of capacitors with each capacitor having a first electrode and a second electrode, said proof mass forming each first electrode and said regions of said substrate respectively forming the second electrodes, said capacitors comprising means for generating an electrical signal corresponding to movement of said proof mass from a quiescent position due to inertial forces acting on said proof mass resulting from acceleration of said substrate for determining the magnitude of said acceleration.
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Abstract
An acceleration sensor has a proof mass attached by resilient elements, in the form of micromechanical components, in a monocrystalline silicon layer of an SOI (silicon-on-insulator) substrate, the insulator layer of the substrate being removed under the structure which is susceptible to acceleration, in order to enable free mobility of the micromechanical components. Piezoresistors are provided for detecting movement of the proof mass, the piezoresistors supplying electrical signals to an evaluation circuit.
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Citations
7 Claims
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1. An acceleration sensor comprising:
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a silicon-on-insulator substrate having a monocrystalline silicon layer and an insulator layer; a proof mass consisting of silicon doped so as to be electrically conductive and at least one resilient element formed in said silicon layer, said at least one resilient element extending between and electrically connecting said proof mass and a remainder of said silicon layer; said insulator layer having an opening therein in which said proof mass and said at least one resilient element are disposed, said proof mass and said at least one resilient element being freely movable within said opening; and said substrate having a plurality of regions disposed opposite said proof mass which are doped so as to be electrically conductive, said proof mass and said regions of said substrate forming, in combination, a plurality of capacitors with each capacitor having a first electrode and a second electrode, said proof mass forming each first electrode and said regions of said substrate respectively forming the second electrodes, said capacitors comprising means for generating an electrical signal corresponding to movement of said proof mass from a quiescent position due to inertial forces acting on said proof mass resulting from acceleration of said substrate for determining the magnitude of said acceleration.
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2. An acceleration sensor comprising:
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a silicon-on-insulator substrate having a monocrystalline silicon layer and an insulator layer; a proof mass consisting Of silicon doped so as to be electrically conductive and at least one resilient element formed in said silicon layer, said at least one resilient element extending between and electrically connecting said proof mass and a remainder of said silicon layer; said insulator layer having an opening therein in which said proof mass and said at least one resilient element are disposed, said proof mass and said at least one resilient element being freely movable within said opening, said silicon layer being disposed in a plane and said acceleration mass being movable in said plane of said silicon layer; and said substrate having a plurality of regions disposed opposite said proof mass which are doped so as to be electrically conductive, said proof mass and said regions of said substrate forming, in combination, a plurality of capacitors, each capacitor having first and second electrodes, said first electrodes comprising a plurality of finger-shaped electrodes extending from said proof mass and said second electrodes comprising a plurality of cooperating finger-shaped electrodes extending from said remainder of said silicon layer, said plurality of capacitors comprising means for generating an electrical signal corresponding to movement of said proof mass from a quiescent position due to internal forces acting on said proof mass resulting from acceleration of said substrate for determining the magnitude of said acceleration. - View Dependent Claims (3, 4)
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5. A method for manufacturing an acceleration sensor comprising the steps of:
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providing a silicon-on-insulator substrate having a monocrystalline silicon layer and an insulating layer; forming a structure including a proof mass and at least one resilient element in said silicon layer of said SOI substrate, said at least one resilient element extending between said proof mass and a remainder of said silicon layer; removing a region of said insulator layer beneath said proof mass and said at least one resilient element to permit free mobility of said proof mass and said at least one resilient element in said region from a quiescent position due to a force of inertia acting on said proof mass resulting from acceleration of said substrate; and forming a plurality of capacitors each having a first capacitor electrode movable with said proof mass and a second capacitor electrode attached to said remainder of said silicon layer. - View Dependent Claims (6, 7)
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Specification