GAS SENSOR
A gas sensing device comprising a substrate comprising an etched cavity portion and a substrate portion; a dielectric layer disposed on the substrate. The dielectric layer comprises a dielectric membrane. The dielectric membrane is adjacent to the etched cavity portion of the substrate. The dielectric membrane comprises an etched recess portion, a heater located within the dielectric layer, and a material for sensing a gas. The material for sensing a gas is located within the etched recess portion of the dielectric membrane.
1 . A gas sensing device comprising;
a substrate comprising an etched cavity portion and a substrate portion;
a dielectric layer disposed on the substrate, wherein the dielectric layer comprises a dielectric membrane, wherein the dielectric membrane is adjacent to the etched cavity portion of the substrate, and wherein the dielectric membrane comprises an etched recess portion;
a heater located within the dielectric layer; and
a material for sensing a gas, wherein the material for sensing a gas is located within the etched recess portion of the dielectric membrane.
2 . A gas sensing device according to claim 1 , further comprising a plurality of electrodes configured to measure the current and/or resistance of the gas sensing material.
3 . A gas sensing device according to claim 2 , further comprising a plurality of first etch stop layers located on a top surface of the dielectric membrane, each first etch stop layer being located above the plurality of electrodes.
4 . A gas sensing device according to claim 3 , wherein each first etch stop layer is laterally spaced from one another; and/or wherein each first etch stop layer forms a ring or a closed shape.
5 . A gas sensing device according to claim 3 , wherein the etched recess portion is defined by the plurality of first etch stop layers.
6 . A gas sensing device according to claim 2 , further comprising at least one second etch stop layer located within the dielectric layer, each second etch stop layer being located under a plurality of electrodes.
7 . A gas sensing device according to claim 6 , wherein the at least one second etch stop layer below the electrodes extends laterally through an entire width of the dielectric layer.
8 . A gas sensing device according to claim 1 , wherein the device has a flip-chip configuration.
9 . A gas sensing device according to claim 1 , wherein the device is placed above an application specific integration circuit using a flip-chip technique.
10 . A gas sensing device according to claim 1 , wherein the etched recess portion of the dielectric membrane is formed on a front side of the dielectric layer.
11 . A gas sensing device according to claim 1 , wherein the etched recess portion of the dielectric membrane is formed on a back side of the dielectric layer.
12 . A gas sensing device according to claim 11 , wherein the etched recess portion of the dielectric membrane is formed within the etched cavity portion of the substrate.
13 . A gas sensing device according to claim 10 , wherein the etched recess portion of the dielectric membrane is formed over the etched cavity portion of the substrate.
14 . A gas sensing device according to claim 2 , wherein the etched recess portion extends underneath the plurality of electrodes.
15 . A gas sensing device according to claim 14 , wherein the material for sensing a gas extends underneath the plurality of electrodes.
16 . A gas sensing device according to claim 1 , wherein the material for sensing a gas does not extend above an upper surface of the dielectric membrane.
17 . A gas sensing device according to claim 1 , wherein the material for sensing a gas is embedded in the dielectric membrane.
18 . A gas sensing device according to claim 2 , wherein the material for sensing a gas is not formed underneath the plurality of electrodes.
19 . A gas sensor array assembly comprising:
an array of a plurality of gas sensing devices according to claim 1 , wherein said plurality of devices are formed on the same chip.
20 . A gas sensing device according to claim 2 , wherein the electrodes are made of a CMOS material comprising any of polysilicon, silicides, titanium, tungsten, or a metal such as gold, platinum, or a combination of these.
21 . A gas sensor according to claim 3 , wherein the dielectric membrane comprises silicon oxide; and/or wherein at least one of the plurality of first etch stop layers and/or at least one of the plurality of second etch stop layers comprises silicon nitride.
22 . A method of manufacturing a gas sensing device according to any preceding claim, the method comprising:
forming a substrate;
forming a dielectric layer disposed on the substrate;
forming a heater within the dielectric layer;
forming an etched cavity portion within the substrate;
forming an etched recess portion within the dielectric layer; and
forming a material for sensing a gas within the etched recess portion.