Semiconductor mechanical sensor
First Claim
1. A semiconductor mechanical quantity sensor comprising:
- a silicon substrate having an insulation layer on a first surface;
a silicon layer formed on the silicon substrate;
a weight disposed on the silicon layer and movable in a predetermined direction parallel with the first surface of the silicon substrate due to an effect of a mechanical quantity, said weight being provided with a plurality of movable electrodes which are in parallel with each other, each of said plurality of movable electrodes being provided with a surface perpendicular to the first surface of the silicon substrate;
a plurality of fixed electrodes secured to the insulation layer and being opposed to the surfaces of the plurality of movable electrodes to form capacitors with the plurality of movable electrodes; and
a peripheral portion surrounding the plurality of movable electrodes and the plurality of fixed electrodes, whereinmajor surfaces of the plurality of movable electrodes, the plurality of fixed electrodes, and the peripheral portion being formed to be substantially on the same plane with each other,the plurality of movable electrodes, the plurality of fixed electrodes, and the peripheral portion being insulated and separated from one another to detect the mechanical quantity based on a change of the capacitance of the capacitors,all electrode contacting portions being formed on a major surface of the silicon layer.
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Accused Products
Abstract
A semiconductor mechanical sensor having a new structure in which a S/N ratio is improved. In the central portion of a silicon substrate 1, a recess portion 2 is formed which includes a beam structure. A weight is formed at the tip of the beam, and in the bottom surface of the weight in the bottom surface of the recess portion 2 facing the same, an electrode 5 is formed. An alternating current electric power is applied between the weight portion 4 and the electrode 5 so that static electricity is created and the weight is excited by the static electricity. In an axial direction which is perpendicular to the direction of the excitation of the weight, an electrode 6 is disposed to face one surface of the weight and a wall surface of the substrate which faces the same. A change in a capacitance between the facing electrodes is electrically detected, and therefore, a change in a physical force acting in the same direction is detected.
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Citations
12 Claims
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1. A semiconductor mechanical quantity sensor comprising:
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a silicon substrate having an insulation layer on a first surface; a silicon layer formed on the silicon substrate; a weight disposed on the silicon layer and movable in a predetermined direction parallel with the first surface of the silicon substrate due to an effect of a mechanical quantity, said weight being provided with a plurality of movable electrodes which are in parallel with each other, each of said plurality of movable electrodes being provided with a surface perpendicular to the first surface of the silicon substrate; a plurality of fixed electrodes secured to the insulation layer and being opposed to the surfaces of the plurality of movable electrodes to form capacitors with the plurality of movable electrodes; and a peripheral portion surrounding the plurality of movable electrodes and the plurality of fixed electrodes, wherein major surfaces of the plurality of movable electrodes, the plurality of fixed electrodes, and the peripheral portion being formed to be substantially on the same plane with each other, the plurality of movable electrodes, the plurality of fixed electrodes, and the peripheral portion being insulated and separated from one another to detect the mechanical quantity based on a change of the capacitance of the capacitors, all electrode contacting portions being formed on a major surface of the silicon layer. - View Dependent Claims (2, 3, 4)
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5. A semiconductor mechanical quantity sensor having a first layer comprising a silicon substrate, a second layer comprising an insulation layer disposed on the first layer, a third layer comprising a silicon layer disposed on the second layer, a fourth layer comprising an insulation film partially disposed on the third layer, and a fifth layer comprising a silicon layer disposed on the fourth layer and partly connected to the third layer through a portion where the fourth layer is not disposed, wherein the sensor comprises:
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a plurality of movable electrodes formed by the fifth layer, and arranged in parallel with each other, said plurality of movable electrodes being movable in a predetermined direction parallel with a surface of the first layer due to an effect of a mechanical quantity; and a plurality of fixed electrodes formed by the fifth layer and secured to the first layer through at least the second layer, said fixed electrodes being opposed to the surfaces of the plurality of movable electrodes to form capacitors together with the plurality of movable electrodes, so that the mechanical quantity is detected based on a change in the capacitance of the capacitors. - View Dependent Claims (7, 8)
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6. A semiconductor mechanical quantity sensor as set forth in clam 5, further comprising a wiring layer for electrically interconnecting the plurality of fixed electrodes.
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9. A semiconductor mechanical quantity sensor having a first layer comprising a silicon substrate, a second layer comprising an insulation layer disposed on the first layer, a third layer comprising a silicon layer disposed on the second layer, a fourth layer comprising an insulation layer disposed on the third layer, and a fifth layer comprising a silicon layer disposed on the fourth layer, wherein
said fifth layer is provided with a weight movable due to an effect of a mechanical quantity, a plurality of movable electrodes formed on the weight, and a plurality of fixed electrodes opposed to the plurality of movable electrode, said third layer is made of a polysilicon layer containing high density impurities, which is formed in parallel with the first layer and under the weight, a predetermined area of the fifth layer is electrically connected to the polysilicon layer through a bottom contact for an electric connection, formed on a predetermined area of the polysilicon layer and a major surface of said fifth layer is provided with electrode contacting portions made of at least one metal layer and arranged on substantially the same plane with each other.
Specification