Atomic layer deposited protective coatings for integrated MEMS flow sensor

This paper investigates the Atomic layer deposited (ALD) coatings on an integrated Microelectromechanical (MEMS) flow sensor to resist ironic contamination of on-chip CMOS circuits. 2 5nm Al₂O₃/TiO₂ multilayer thin film was deposited on the integrated flow sensor. To assess the ability of ALD coatings to resist K⁺ and Na⁺ contamination, the flow sensor was immersed into NaCl and KCl solutions for 1 week, respectively. The CMOS transistors fabricated on the same chip were tested after long time immersion and results showed that the performance of the CMOS circuits were not degraded, which implied this integrated flow sensor with ALD protective coatings could be used under K⁺ and Na⁺ environment.