Results on the reliability of silicon micromachined structures for semiconductor gas sensors

Thin film semiconductor gas sensors fabricated on thermally isolated silicon substrates have been proposed as good alternative to thick film devices that are on the market as they show low power consumption. However, for their industrial success, it is necessary to assess good yield and high reliability for maintaining the functionality of the device during a long period of time. In this paper, a set of thermo-mechanical tests has been applied to gas sensors based on silicon micromachined structures with dielectric membranes. The aim of the tests is to determine the survivability of the devices under aggressive conditions of use. The tests have been carried out on two specific structures, a single Si₃N₄ membrane; and the same device that also includes a silicon plug below the sensor active area. Results are compared as a tool for improving the structure in the future.