Gas-sensing semiconductor devices
First Claim
1. A gas-sensing semiconductor device comprising a semiconductor substrate (2), a thin insulating layer (3) on one side of the substrate, and a thin semiconductor layer (4) on top of the thin insulating layer, wherein the device includes at least one sensing area in which the material of the substrate has been removed to leave a membrane (20) formed by the thin insulating layer and the thin semiconductor layer, and wherein the at least one sensing area is provided with a gas-sensitive layer (18, 43) and a heater (6, 42, 52, 62, 73, 83) for heating the gas-sensitive layer to promote gas reaction with the gas-sensitive layer, and a sensor (16, 42, 72, 82) for providing an electrical output indicative of gas reaction with the gas-sensitive layer, characterised in that the at least one sensing area incorporates a MOSFET formed in the thin semiconductor layer (4) and forming part of the heater and/or sensor.
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Accused Products
Abstract
A gas-sensing semiconductor device 1 is fabricated on a silicon substrate 2 having a thin silicon oxide insulating layer 3 on one side and a thin silicon layer 4 on top of the insulating layer 3 using CMOS SOI technology. The silicon layer 4 may be in the form of an island surrounded by a silicon oxide insulating barrier layer 4 formed by the known LOCOS oxidation technique, although other lateral isolation techniques may also be used. The device 1 includes at least one sensing area provided with a gas-sensitive layer 18, a MOSFET heater 6 for heating the gas-sensitive layer 18 to promote gas reaction with the gas-sensitive layer 18 and a sensor 16, which may be in the form of a chemoresistor, for providing an electrical output indicative of gas reaction with the gas-sensitive layer 18. As one of the final fabrication steps, the substrate 2 is back-etched so as to form a thin membrane 20 in the sensing area. Such a device can be produced at low cost using conventional CMOS SOI technology.
154 Citations
20 Claims
- 1. A gas-sensing semiconductor device comprising a semiconductor substrate (2), a thin insulating layer (3) on one side of the substrate, and a thin semiconductor layer (4) on top of the thin insulating layer, wherein the device includes at least one sensing area in which the material of the substrate has been removed to leave a membrane (20) formed by the thin insulating layer and the thin semiconductor layer, and wherein the at least one sensing area is provided with a gas-sensitive layer (18, 43) and a heater (6, 42, 52, 62, 73, 83) for heating the gas-sensitive layer to promote gas reaction with the gas-sensitive layer, and a sensor (16, 42, 72, 82) for providing an electrical output indicative of gas reaction with the gas-sensitive layer, characterised in that the at least one sensing area incorporates a MOSFET formed in the thin semiconductor layer (4) and forming part of the heater and/or sensor.
Specification