Accelerated ageing of micro-hotplates for gas sensing applications

We report on the reliability of micro-hotplates used in gas sensing applications. Accelerated ageing of the micro-hotplates was obtained using a burn-in test. Devices with different designs were self-heated at higher temperatures than their typical operating temperature until failure. Results on micro-hotplates with only the heater, the heater and electrodes, and coated with the gas-sensitive coating are presented. Electromigration and breaking of the membrane were two failure modes observed, and for some testing conditions were linked together. The electrodes had a slight effect on the maximum power before failure and on the membrane deformation, but had an influence on the micro-hotplates lifetime. The addition of the gas-sensitive coating provided a longer lifetime.