METHOD OF FABRICATING A INTEGRATED PRESSURE SENSOR
First Claim
1. A method of fabricating a pressure sensor for sensing a fluid pressure, the method comprising the steps of:
- providing a first wafer substrate having first and second opposing planar surfaces;
depositing circuitry on the first planar surface;
depositing a layer of passivation material on the circuitry;
etching openings in the passivation layer to expose parts of the circuitry;
etching an aperture into the first wafer from the first planar surface towards the second planar surface;
depositing sacrificial material in the aperture;
depositing a flexible membrane on the sacrificial material and the exposed parts of the circuitry;
plasma cleaning the sacrificial material out of the aperture from the second surface;
providing a second substrate; and
,sealing the second substrate to the second planar surface of the first wafer substrate to define a chamber containing a fluid at a reference pressure;
wherein during use,the flexible membrane deflects due to pressure differentials between the reference pressure and the fluid pressure and the circuitry converts the deflection of the flexible membrane into an output signal indicative of the fluid pressure.
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Accused Products
Abstract
A method of fabricating a pressure sensor (30) for harsh environments such as vehicle tires, formed from a first wafer substrate (32) having first and second opposing planar surfaces. CMOS circuitry (34) is deposited on the first planar surface and a layer of passivation material is deposited on the circuitry. Openings in the passivation layer are etched to expose parts of the circuitry and an aperture is etched into the first wafer from the first planar surface towards the second planar surface. Sacrificial material is deposited in the aperture and then a flexible membrane (50) is deposited on the sacrificial material and the exposed parts of the circuitry. The sacrificial material is subsequently plasma cleaned out of the aperture from the second surface and a second substrate is sealed to the second planar surface of the first wafer substrate to define a chamber (58) containing a fluid at a reference pressure. During use, the flexible membrane deflects due to pressure differentials between the reference pressure and the fluid pressure and the circuitry converts the deflection of the flexible membrane into an output signal indicative of the fluid pressure.
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Citations
18 Claims
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1. A method of fabricating a pressure sensor for sensing a fluid pressure, the method comprising the steps of:
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providing a first wafer substrate having first and second opposing planar surfaces; depositing circuitry on the first planar surface; depositing a layer of passivation material on the circuitry; etching openings in the passivation layer to expose parts of the circuitry; etching an aperture into the first wafer from the first planar surface towards the second planar surface; depositing sacrificial material in the aperture; depositing a flexible membrane on the sacrificial material and the exposed parts of the circuitry; plasma cleaning the sacrificial material out of the aperture from the second surface; providing a second substrate; and
,sealing the second substrate to the second planar surface of the first wafer substrate to define a chamber containing a fluid at a reference pressure;
wherein during use,the flexible membrane deflects due to pressure differentials between the reference pressure and the fluid pressure and the circuitry converts the deflection of the flexible membrane into an output signal indicative of the fluid pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification