Bi-directional released-beam sensor

A sensor, comprising:

• 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;
• means for increasing a bi-directional sensitivity of the cantilever to acceleration of the substrate along a first axis;
• and
• means for detecting response of the beam to acceleration bi-directionally along the one axis.

A method, comprising:

• forming a first layer on a surface of a semiconductor wafer;
• forming a first 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 first plug in the aperture;
• forming a fourth layer over the third layer and in contact with the first plug;
• patterning the fourth layer to form a beam;
• forming a fifth layer over the fourth layer;
• forming an aperture in the fifth layer having a shape substantially mirroring the shape of the first plug;
• filling the aperture in the fifth layer to form a second plug in contact with the beam;
• removing the fifth layer such that the second plug remains on the beam;
• forming a sixth layer over the second plug and beam having a thickness substantially equal to a thickness of the second layer;
• forming a seventh layer over the sixth layer;
• and
• etching the second and sixth layers to form a cantilever of the beam with one end suspended above the first aperture, the first plug coupled to the beam and suspended at least partially within the first aperture, the second plug coupled to the beam and at least partially suspended within a second aperture formed in the seventh layer by the second plug and the sixth layer.

A system, comprising:

• 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 first and second bosses coupled to upper and lower surfaces, respectively, of the second end of the beam and suspended over the substrate.

A method, comprising:

• subjecting a semiconductor substrate to an acceleration;
• moving a first and second bosses 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 an absolute value of the acceleration exceeds a selected threshold along a selected vector.