Integrated CMOS porous sensor
A single chip wireless sensor comprises a microcontroller connected to a transmit/receive interface, which is coupled to a wireless antenna by an L-C matching circuit. The sensor senses gas or humidity and temperature. The device is an integrated chip manufactured in a single process in which both the electronics and sensor components are manufactured using standard CMOS processing techniques, applied to achieve both electronic and sensing components in an integrated process. A Low-K material with an organic polymer component is spun onto the wafer to form a top layer incorporating also sensing electrodes. This material is cured at 300° C., which is much lower than CVD temperatures. The polyimide when cured becomes thermoset, and the lower mass-to-volume ratio resulting in K, its dielectric constant, reducing to 2.9. The thermoset dielectric, while not regarded as porous in the conventional sense, has sufficient free space volume to admit enough gas or humidity for sensing.
1. An integrated gas sensor device comprising:
a semiconductor integrated circuit formed on a single substrate, the semiconductor integrated circuit comprising:
MOS circuits formed in the substrate;
a plurality of interconnect levels comprised of interconnect conductors and insulating materials above the MOS circuits, the interconnect levels provided as routing interconnect levels for the semiconductor integrated circuit;
a resistive sensor layer and a capacitive sensor layer, both the resistive sensor layer and the capacitive sensor layer being formed above the plurality of interconnect levels and being exposed to an ambient atmosphere within which a gas to be sensed may be present;
a microcontroller coupled to the resistive sensor layer and capacitive sensor layer, the microcontroller utilizing together resistance measurements from the resistive sensor layer and capacitance measurements from the capacitive sensor layer to provide a measurement indicative of gas concentration levels; and
a humidity sensor, the microcontroller utilizing humidity readings from the humidity sensor to adjust the measurement indicative of gas concentration levels.
2. The integrated gas sensor device of claim 1 , the semiconductor integrated circuit further comprising a temperature sensor, the microcontroller utilizing temperature readings from the temperature sensor to adjust the measurement indicative of gas concentration levels.
3. An integrated gas sensor device comprising:
a semiconductor integrated circuit formed on a single substrate, the semiconductor integrated circuit comprising:
MOS circuits formed in the substrate;
a plurality of interconnect levels comprised of interconnect conductors and insulating materials above the MOS circuits, the interconnect levels provided as routing interconnect levels for the semiconductor integrated circuit;
a resistive sensor layer and a capacitive sensor layer, both the resistive sensor layer and the capacitive sensor layer being formed above the plurality of interconnect levels and being exposed to an ambient atmosphere within which a gas to be sensed may be present;
a microcontroller coupled to the resistive sensor layer and capacitive sensor layer, the microcontroller utilizing together resistance measurements from the resistive sensor layer and capacitance measurements from the capacitive sensor layer to provide a measurement indicative of gas concentration levels; and
a temperature sensor, the microcontroller utilizing temperature readings from the temperature sensor to adjust the measurement indicative of gas concentration levels.
4. An integrated gas sensor device comprising:
a semiconductor integrated circuit formed on a single substrate, the semiconductor integrated circuit comprising:
MOS circuits formed in the substrate;
a plurality of interconnect levels comprised of interconnect conductors and insulating materials above the MOS circuits, the interconnect levels provided as routing interconnect levels for the semiconductor integrated circuit;
a resistive sensor layer and a capacitive sensor layer, both the resistive sensor layer and the capacitive sensor layer being formed above the plurality of interconnect levels and being exposed to an ambient atmosphere within which a gas to be sensed may be present; and
a microcontroller coupled to the resistive sensor layer and capacitive sensor layer, the microcontroller utilizing together resistance measurements from the resistive sensor layer and capacitance measurements from the capacitive sensor layer to provide a measurement indicative of gas concentration levels,
wherein the capacitive sensor layer provides a variable fringe capacitance component in a capacitor structure.
5. An integrated gas sensor device comprising:
a semiconductor integrated circuit formed on a single substrate, the semiconductor integrated circuit comprising:
MOS circuits formed in the substrate;
a plurality of interconnect levels comprised of interconnect conductors and insulating materials above the MOS circuits, the interconnect levels provided as routing interconnect levels for the semiconductor integrated circuit;
a resistive sensor layer and a capacitive sensor layer, both the resistive sensor layer and the capacitive sensor layer being formed above the plurality of interconnect levels and being exposed to an ambient atmosphere within which a gas to be sensed may be present; and
a microcontroller coupled to the resistive sensor layer and capacitive sensor layer, the microcontroller utilizing together resistance measurements from the resistive sensor layer and capacitance measurements from the capacitive sensor layer to provide a measurement indicative of gas concentration levels,
wherein the resistive sensor layer forms a resistor connected to at least one of the plurality of interconnect levels.
6. The integrated gas sensor device of claim 5 , the semiconductor integrated circuit further comprising an analog to digital converter coupled between the microcontroller and both of the resistive sensor layer and capacitive sensor layer.
7. The integrated gas sensor device of claim 5 , the semiconductor integrated circuit further comprising a memory element coupled to the microcontroller.
8. An integrated gas sensor device comprising:
a semiconductor integrated circuit formed on a single substrate, the semiconductor integrated circuit comprising:
MOS circuits formed in the substrate;
a plurality of interconnect levels comprised of interconnect conductors and insulating materials above the MOS circuits, the interconnect levels provided as routing interconnect levels for the semiconductor integrated circuit;
a resistive sensor layer and a capacitive sensor layer, both the resistive sensor layer and the capacitive sensor layer being formed above the plurality of interconnect levels and being exposed to an ambient atmosphere within which a gas to be sensed may be present; and
a microcontroller coupled to the resistive sensor layer and capacitive sensor layer, the microcontroller utilizing together resistance measurements from the resistive sensor layer and capacitance measurements from the capacitive sensor layer to provide a measurement indicative of gas concentration levels,
wherein at least one of the resistive sensor layer and the capacitive sensor layer comprises zinc oxide and ferric oxide.
9. A method of sensing a gas concentration, comprising:
providing a semiconductor integrated circuit formed on a single substrate, semiconductor integrated circuit comprising MOS circuits;
providing a plurality of interconnect levels comprised of interconnect conductors and insulating materials above the MOS circuits, the interconnect levels provided as routing interconnect levels for the semiconductor integrated circuit;
providing a resistive sensor layer and a capacitive sensor layer, as part of semiconductor integrated circuit, above the plurality of interconnect levels and being exposed to an ambient atmosphere within which a gas to be sensed may be present;
providing a microcontroller as part of the semiconductor integrated circuit and coupled to the resistive sensor layer and capacitive sensor layer;
configuring the semiconductor integrated circuit such that resistance measurements from the resistive sensor layer and capacitance measurements from the capacitive sensor layer may be utilized together by the microcontroller to provide a measurement indicative of gas concentration levels in the ambient atmosphere; and
adjusting the measurement indicative of gas concentration levels based upon humidity readings.
10. The method of claim 9 , further comprising adjusting the measurement indicative of gas concentration levels based upon temperature readings.
11. A method of sensing a gas concentration, comprising:
providing a semiconductor integrated circuit formed on a single substrate, semiconductor integrated circuit comprising MOS circuits;
providing a plurality of interconnect levels comprised of interconnect conductors and insulating materials above the MOS circuits, the interconnect levels provided as routing interconnect levels for the semiconductor integrated circuit;
providing a resistive sensor layer and a capacitive sensor layer, as part of semiconductor integrated circuit, above the plurality of interconnect levels and being exposed to an ambient atmosphere within which a gas to be sensed may be present;
providing a microcontroller as part of the semiconductor integrated circuit and coupled to the resistive sensor layer and capacitive sensor layer;
configuring the semiconductor integrated circuit such that resistance measurements from the resistive sensor layer and capacitance measurements from the capacitive sensor layer may be utilized together by the microcontroller to provide a measurement indicative of gas concentration levels in the ambient atmosphere; and
adjusting the measurement indicative of gas concentration levels based upon temperature readings.
12. A method of sensing a gas concentration, comprising:
providing a semiconductor integrated circuit formed on a single substrate, semiconductor integrated circuit comprising MOS circuits;
providing a plurality of interconnect levels comprised of interconnect conductors and insulating materials above the MOS circuits, the interconnect levels provided as routing interconnect levels for the semiconductor integrated circuit;
providing a resistive sensor layer and a capacitive sensor layer, as part of semiconductor integrated circuit, above the plurality of interconnect levels and being exposed to an ambient atmosphere within which a gas to be sensed may be present;
providing a microcontroller as part of the semiconductor integrated circuit and coupled to the resistive sensor layer and capacitive sensor layer; and
configuring the semiconductor integrated circuit such that resistance measurements from the resistive sensor layer and capacitance measurements from the capacitive sensor layer may be utilized together by the microcontroller to provide a measurement indicative of gas concentration levels in the ambient atmosphere;
wherein the capacitive sensor layer provides a variable fringe capacitance for a capacitor sensor.
13. A method of sensing a gas concentration, comprising:
providing a semiconductor integrated circuit formed on a single substrate, semiconductor integrated circuit comprising MOS circuits;
providing a plurality of interconnect levels comprised of interconnect conductors and insulating materials above the MOS circuits, the interconnect levels provided as routing interconnect levels for the semiconductor integrated circuit;
providing a resistive sensor layer and a capacitive sensor layer, as part of semiconductor integrated circuit, above the plurality of interconnect levels and being exposed to an ambient atmosphere within which a gas to be sensed may be present;
providing a microcontroller as part of the semiconductor integrated circuit and coupled to the resistive sensor layer and capacitive sensor layer; and
configuring the semiconductor integrated circuit such that resistance measurements from the resistive sensor layer and capacitance measurements from the capacitive sensor layer may be utilized together by the microcontroller to provide a measurement indicative of gas concentration levels in the ambient atmosphere,
wherein the resistive sensor layer provides a variable resistance for a resistor sensor.
14. The method of claim 13 , further comprising calibrating the measurement indicative of gas concentration levels in the ambient atmosphere.