Electromigration Model for Platinum Hotplates

Microheaters are frequently applied in the design of semiconductor metal oxide gas sensors in order to heat the sensing layer and induce the surface chemical reactions which promote molecular adsorption. One of the most common materials used for the microheater layer is platinum. In this manuscript, a model for electro-migration is developed and implemented to study vacancy dynamics and the thereby-induced stress in platinum-based microheaters for gas sensor applications. The model is then applied to study the impact of the individual components which contribute to vacancy transport, including electro-migration, thermo-migration, and stress-migration. We find that these structures have very high thermal gradients, making the impact of thermo-migration component higher than the electro-migration component in the early stages of vacancy transport, unlike in copper-based interconnects. Therefore, improving the temperature uniformity of the microheater design should lead to a longer operating time before failure.