Long-Term Stability Improvement of Micro-Hotplate Methane Sensor Product

This paper reports the improvement for long-term stability of gas sensor product that works at 300-450°C. The commercially available micro-hotplate faces the problem of heater resistance continuous increasing during operation, which leads to temperature decreasing under preset voltage supply, sensitivity drop and even device failure. For current micro-hotplate based metal-oxide-semiconductor (MOS) gas sensor product, long-term stability is bottleneck for commercialization. In this work, a novel design of optimized tantalum/platinum (Ta/Pt) thin film heater is developed, optimized and used in a micro-hotplate sensor. With this approach, the heater resistance drift in 40 days decreases from 6.1% to 0.3%. This technology has just been applied in a commercial methane sensor, and the sensitivity features good stability at 420°C within 92 days. The control experiments with poly-Si heater gas sensor shows that the novel sensor exhibits better stability at high temperature. The results indicate this technique improves the long-term stability of micro-hotplate sensor effectively and offers promise of different kinds of high-temperature sensors application.