Semiconductor mechanical sensor
First Claim
1. A semiconductor mechanical quantity sensor comprising:
- a first layer formed by a silicon substrate;
a second layer formed by an insulation layer disposed on said first layer;
a third layer formed by a silicon layer disposed on said second layer;
a fourth layer formed by an insulation layer disposed on said third layer; and
a fifth layer formed by a silicon layer disposed on said fourth layer;
whereinthe thickness of the fifth layer is greater than the thickness of the third layer,said fifth layer is provided with a weight being movable due to the effect of the mechanical quantity, movable electrodes included in said weight, a fixed electrode facing said movable electrode, and electric routing paths being separated from said weight and extending in a direction perpendicular to said first layer;
said third layer is formed by a polysilicon layer containing high density impurities and extending in a direction parallel with said first layer,said polysilicon layer and said electric routing paths are electrically connected via a bottom contact for an electric connection, the bottom contact being formed below the electric routing paths and between said third layer and fifth 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
17 Claims
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1. A semiconductor mechanical quantity sensor comprising:
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a first layer formed by a silicon substrate; a second layer formed by an insulation layer disposed on said first layer; a third layer formed by a silicon layer disposed on said second layer; a fourth layer formed by an insulation layer disposed on said third layer; and a fifth layer formed by a silicon layer disposed on said fourth layer;
whereinthe thickness of the fifth layer is greater than the thickness of the third layer, said fifth layer is provided with a weight being movable due to the effect of the mechanical quantity, movable electrodes included in said weight, a fixed electrode facing said movable electrode, and electric routing paths being separated from said weight and extending in a direction perpendicular to said first layer; said third layer is formed by a polysilicon layer containing high density impurities and extending in a direction parallel with said first layer, said polysilicon layer and said electric routing paths are electrically connected via a bottom contact for an electric connection, the bottom contact being formed below the electric routing paths and between said third layer and fifth layer. - View Dependent Claims (2, 3, 4)
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5. A semiconductor mechanical quantity sensor comprising:
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a silicon layer formed on a substrate via an insulation layer; a movable portion formed on said silicon layer and having a first surface and a second surface orthogonal to each other; a first correspondent electrode formed by a polysilicon layer which is insulated and separated from said substrate and is arranged in parallel with the major surface of said silicon layer, said polysilicon layer being opposed to the first surface of said movable portion; and a second correspondent electrode which is insulated and separated from said substrate and which is opposed to the second surface of the movable portion, said silicon layer and said first correspondent electrode formed by a polysilicon layer having the same conductivity type, and second electrode being formed using said silicon layer, said second correspondent electrode being insulated and separated from said substrate, wherein electric routing paths, extending from said first correspondent electrode to an electrode contacting portion electrically connected to the first correspondent electrode and extending in the thickness direction of said silicon layer, are formed using said silicon layer, and the whole of the electrode contacting portion is formed on the surface of the silicon layer and arranged on substantially the same surface. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
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14. A semiconductor mechanical quantity sensor comprising:
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a first layer formed by a silicon substrate; a second layer formed by an insulation layer disposed on said first layer; a third layer formed by a silicon layer disposed on said second layer; a fourth layer formed by an insulation layer disposed on said third layer; and a fifth layer formed by a silicon layer disposed on said fourth layer;
whereinthe thickness of said fifth layer is greater than the thickness of said third layer, said fifth layer and said third layer have the same conductivity type, said fifth layer is provided with a weight being movable due to the effect of the mechanical quantity and movable electrodes included in said weight, said third layer is formed by a polysilicon layer containing high density impurities and extending in a direction parallel with said first layer, said polysilicon layer and a part of said fifth layer are electrically connected via a bottom contact for an electric connection, said bottom contact being formed below the fifth layer, a predetermined aluminum layer is formed on the major surface of said fifth layer and arranged on substantially the same surface. - View Dependent Claims (15, 16, 17)
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Specification