Design optimization of embedded micro-heater for reliable gas sensing and on-chip annealing

초록

Embedded micro-heaters are essential in metal oxide-based gas sensors, enabling thermal activation and localized tuning of film properties via on-chip annealing. As gas sensors move into mobile and edge devices, demand has grown for reliable, energy-efficient micro-heaters. However, achieving both low power consumption and long-term reliability at elevated temperatures remains challenging. Here, we analyze nine micro-heater designs with varied micro-bridge configurations and terminal geometries to identify structural factors that govern embedded micro-heater performance. Through electrical measurements and thermal analyses, we establish key trade-offs among power efficiency, temperature uniformity, and reliability. We show that removing microbridges near the sensing layer significantly reduces thermal loss, while increasing the length of the positively biased terminal compensates for thermoelectric effects and significantly improves the durability of the contact area. Gas-sensing performance is evaluated using a FET-type sensor with a 15 nm-thick In2O3 layer. The optimized design, featuring localized bridging near the contacts and increased length of biasing terminal, demonstrates stable operation during repeated on-chip annealing cycles.

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