Development of hafnium oxynitride dielectrics for radio-frequency-microelectromechanical system capacitive switches

This paper presents the development of π-type radio-frequency-microelectromechanical system (RF-MEMS) capacitive shunt switches using 50 nm thick amorphous hafnium oxynitride (HfOxNy) dielectric film as insulator layer. The 50 nm-thick amorphous HfOxNy film was prepared by reactive sputtering. The electrical properties of the HfOxNy film were investigated with a capacitance-voltage, current-electric field and constant bias stressing measurement. The HfOxNy film had a dielectric constant of 19 at 1 MHz and a dielectric strength of 9.5 MV/cm. The HfOxNy dielectric film exhibited excellent reliability during constant bias stressing. The insertion loss of the RF-MEMS capacitive switch at the up-state was lower than 0.35 dB in frequencies up to 10 GHz, 0.5 dB at 10 to 15 GHz and 0.8 dB at 26 GHz. The switch at down-state had isolation performance better than −30 dB in the frequency range of 10 to 20 GHz, and −27 dB in the frequency range of 20 to 30 GHz.