Weighted released-beam sensor
First Claim
1. A sensor, comprising:
- a semiconductor substrate;
a first layer formed on a surface of the substrate;
an aperture within the first layer;
a beam having first and second ends, the beam being mechanically coupled at the first end to the first layer and suspended above the first layer for at least a portion of the length thereof and the second end having a region above the aperture; and
a boss coupled to the second end of the beam and suspended at least partially within the aperture.
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Accused Products
Abstract
A released-beam sensor includes a semiconductor substrate having a layer formed thereon, and an aperture formed in the layer. A beam is mechanically coupled at a first end to the layer and suspended above the layer such that a second end forms a cantilever above the aperture. A boss is coupled to a second end of the beam and suspended at least partially within the aperture. The beam is configured to flex in response to acceleration of the substrate along a vector substantially perpendicular to a surface of the substrate. Parameters of the sensor, such as the dimensions of the beam, the mass of the boss, and the distance between the boss and a contact surface within the aperture, are selected to establish an acceleration threshold at which the boss will make contact with the contact surface. The sensor may be employed to deploy an airbag in a vehicle.
27 Citations
25 Claims
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1. A sensor, comprising:
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a semiconductor substrate;
a first layer formed on a surface of the substrate;
an aperture within the first layer;
a beam having first and second ends, the beam being mechanically coupled at the first end to the first layer and suspended above the first layer for at least a portion of the length thereof and the second end having a region above the aperture; and
a boss coupled to the second end of the beam and suspended at least partially within the aperture. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A sensor, comprising:
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a semiconductor substrate;
a first layer of material formed on a surface of the substrate;
a beam having first and second ends, the beam being mechanically coupled at the first end to the first layer and suspended above the first layer such that the second end forms a cantilever above the first layer; and
means for increasing a sensitivity of the cantilever to acceleration in at least one axis. - View Dependent Claims (15, 16)
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17. A method, comprising:
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forming a first layer on a surface of a semiconductor wafer;
forming an aperture in the first layer;
forming a second layer over the first layer and within the aperture;
forming a third layer of semiconductor material over the second layer and in the aperture, to form a plug in the aperture;
forming a fourth layer of semiconductor material over the third layer and in electrical contact with the plug;
patterning the fourth layer to form a beam; and
etching the second layer from beneath the plug and from beneath at least a portion of the beam to form a cantilever of the beam with one end suspended above the aperture and the plug coupled to the beam and suspended at least partially within the aperture. - View Dependent Claims (18, 19, 20)
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21. A system, comprising:
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a vehicle having a motor, a drive train coupled to the motor, an axle coupled to the drive train, and wheels coupled to the axle for causing movement of the vehicle powered by the motor;
a passenger seat within said vehicle;
an airbag positioned adjacent to the passenger seat;
a sensor coupled to the airbag configured to cause inflation of the airbag, the sensor including a semiconductor material substrate, a first layer above the semiconductor substrate, a beam having first and second ends, the beam being mechanically coupled at the first end to the substrate and positioned above the first layer for a portion thereof to form a cantilever in a plane that is substantially parallel to an upper surface of the substrate, and a boss of semiconductor material coupled to the second end of the beam and suspended over the substrate. - View Dependent Claims (22)
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23. A method, comprising:
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subjecting a semiconductor substrate to an acceleration;
moving a boss coupled to an outer end of a cantilevered beam coupled at an inner end to the substrate, in response to the acceleration; and
sending a signal from the cantilevered beam to a sensing circuit if the acceleration exceeds a selected threshold along a selected vector. - View Dependent Claims (24, 25)
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Specification