Micro-mechanical capacitive inductive sensor for wireless detection of relative or absolute pressure
First Claim
1. A method of forming a micro-mechanical pressure sensor comprising the steps of:
- providing a first substrate,depositing a first masking layer on the first substrate,patterning the first masking layer on a front side of the first substrate,etching a cavity on the front side of the first substrate,removing the first masking layer from the first substrate,forming a bulk layer in the front side of the first substrate,depositing a second masking layer on the bulk layer,patterning the second masking layer on the back side of the first substrate to form an opening,etching a second cavity on the back side of the first substrate, thereby forming a diaphragm in the first substrate,removing the second masking layer from the first substrate,depositing a conductive layer on the front side of the first substrate to provide a highly conductive diaphragm,providing a second substrate formed from a plurality of dielectric layers and a plurality of conductive layers forming an inductive coil,polishing the front side of the second substrate to achieve a smooth surface,depositing a second conductive layer on the front side of the second substrate,patterning the second conductive layer to form a counter electrode and a bonding area, andbonding the first and second substrates together to form an air gap between the conductive diaphragm and the counter electrode.
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Abstract
A micro-mechanical pressure transducer is disclosed in which a capacitive transducer structure is integrated with an inductor coil to form a LC tank circuit, resonance frequency of which may be detected remotely by imposing an electromagnetic field on the transducer. The capacitive transducer structure comprises a conductive movable diaphragm, a fixed counter electrode, and a predetermined air gap between said diaphragm and electrode. The diaphragm deflects in response to an applied pressure differential, leading to a change of capacitance in the structure and hence a shift of resonance frequency of the LC tank circuit. The resonance frequency of the LC circuit can be remotely detected by measuring and determining the corresponding peak in electromagnetic impedance of the transducer.
24 Citations
21 Claims
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1. A method of forming a micro-mechanical pressure sensor comprising the steps of:
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providing a first substrate, depositing a first masking layer on the first substrate, patterning the first masking layer on a front side of the first substrate, etching a cavity on the front side of the first substrate, removing the first masking layer from the first substrate, forming a bulk layer in the front side of the first substrate, depositing a second masking layer on the bulk layer, patterning the second masking layer on the back side of the first substrate to form an opening, etching a second cavity on the back side of the first substrate, thereby forming a diaphragm in the first substrate, removing the second masking layer from the first substrate, depositing a conductive layer on the front side of the first substrate to provide a highly conductive diaphragm, providing a second substrate formed from a plurality of dielectric layers and a plurality of conductive layers forming an inductive coil, polishing the front side of the second substrate to achieve a smooth surface, depositing a second conductive layer on the front side of the second substrate, patterning the second conductive layer to form a counter electrode and a bonding area, and bonding the first and second substrates together to form an air gap between the conductive diaphragm and the counter electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification