An integrated gas sensor technology using surface micro-machining

We report the first silicon based integrated gas sensor technology using surface micro-machined micro-hotplate (MHP). In this work, the thermally isolated hotplate was fabricated using surface silicon micro-machining technique. Various etching window designs for the polysilicon sacrificial etch were also explored to optimize the surface micro-machining process yield. The front-side surface micro-machined MHP provide excellent manufacturing yield compared to the bulk micro-machined counterpart and at the same time retains all the desirable thermal characteristics that are essential to the integrated gas sensor application. Integrated gas sensors with sensitivity down to 1 ppm of carbon monoxide were demonstrated using this technology. This approach has been extended to integrated gas sensor array.