Processing of integrated gas sensor devices

The integration of gas sensor components into wearable electronics will provide individuals the ability to detect harmful chemicals and pollutants in the environment. The key to this integration is the development of processing techniques for the fabrication of sensor components which can be incorporated into the conventional CMOS fabrication sequence. This includes the etching required for the formation of a suspended membrane on top of which the microheater and sensing layer are placed and the deposition of the metal oxide sensing layer itself. Recently, spray pyrolysis has been investigated as a possible metal oxide deposition approach which is economical, easy to implement, and provides good step coverage for trench geometries. This work investigates wet chemical etching and plasma etching techniques for the generation of a suspended membrane and the spray pyrolysis and sputtering techniques for the deposition of a tin oxide gas sensing layer.