Capacitance pressure sensor
AssigneeSandia Corporation
InventorsWilliam P. Eaton, Bevan D. Staple, James H. Smith
Life of this patent
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Abstract
A microelectromechanical (MEM) capacitance pressure sensor integrated with electronic circuitry on a common substrate and a method for forming such a device are disclosed. The MEM capacitance pressure sensor includes a capacitance pressure sensor formed at least partially in a cavity etched below the surface of a silicon substrate and adjacent circuitry (CMOS, BiCMOS, or bipolar circuitry) formed on the substrate. By forming the capacitance pressure sensor in the cavity, the substrate can be planarized (e.g. by chemical-mechanical polishing) so that a standard set of integrated circuit processing steps can be used to form the electronic circuitry (e.g. using an aluminum or aluminum-alloy interconnect metallization).
Claims70
A microelectromechanical (MEM) capacitance pressure sensor, comprising:
- (a) a silicon substrate having an upper surface;
- (b) a cavity formed below the upper surface of the silicon substrate;
- (c) a first capacitor plate formed in the substrate below the cavity with a dopant type opposite that of the substrate, and forming in combination with the substrate a reverse-biased semiconductor p-n junction;
- (d) a substantially planar diaphragm covering the cavity;
- (e) a second capacitor plate formed on a surface of the diaphragm;
- and
- (f) electronic circuitry, comprising a plurality of transistors, formed on the substrate proximate to the cavity and connected to the first and second capacitor plates for sensing a change in pressure from a deflection in the diaphragm.
A microelectromechanical (MEM) capacitance pressure sensor, comprising:
- (a) a silicon substrate having a cavity formed below an upper surface thereof;
- (b) a capacitance pressure sensor formed within the cavity below the upper surface of the substrate and further comprising a lower capacitor plate and an upper capacitor plate spaced apart from each other, with one of the capacitor plates being moveable in response to applied pressure;
- and
- (c) electronic circuitry, comprising a plurality of transistors, formed on the upper surface of the substrate proximate to the cavity and connected to the capacitor plates for sensing the applied pressure.
A method for forming a microelectromechanical (MEM) capacitance pressure sensor, comprising steps for:
- (a) providing a doped silicon substrate;
- (b) forming a cavity below an upper surface of the substrate;
- (c) forming a first capacitor plate in a portion of the substrate below the cavity by doping the portion of the substrate with a dopant type opposite from the dopant type of the substrate;
- (d) depositing a sacrificial material within the cavity and overfilling the cavity;
- (e) planarizing the substrate;
- (f) forming a diaphragm covering the cavity;
- (g) forming a second capacitor plate on a surface of the diaphragm;
- (h) fabricating electronic circuitry comprising a plurality of transistors on the upper surface of the substrate, with the electronic circuitry being electrically connected to the first and second capacitor plates;
- and
- (i) removing the sacrificial material, at least in part, from within the cavity.
A method for forming a microelectromechanical (MEM) capacitance pressure sensor on a silicon substrate, comprising steps for:
- (a) forming a cavity below an upper surface of the substrate;
- (b) forming a first capacitor plate by depositing a layer of an electrically conductive material within the cavity;
- (c) forming a second capacitor plate above the first capacitor plate;
- (d) depositing a sacrificial material within the cavity and overfilling the cavity;
- (e) planarizing the substrate;
- (f) fabricating electronic circuitry comprising a plurality of transistors on the upper surface of the substrate, with the electronic circuitry being electrically connected to the first and second capacitor plates;
- and
- (g) removing the sacrificial material, at least in part, from within the cavity.
Dependencies are inferred from the claim text.