High-κ Dielectrics for Application in Broadband Radio Frequency-Microelectromechanical System Capacitive Shunt Switch

摘要

130 nm-thick lead zirconate titanate(PZT)/45 nm-thick HfO_2 stack and single 45 nm-thick HfO_2 dielectric film were utilized as insulator layer in π-type radio frequency (RF) capacitive shunt switches for achieving high isolation performance in broadband application. Thin PZT film in perovskite structure mainly with (111) orientation was successfully prepared at low temperature (500℃) using sol-gel method. The thin PZT film exhibited excellent ferroelectric properties and high dielectric constant (k ≈ 1185). Thin HfO_2 film was prepared by sputtering method in a gas mixture of O_2 and Ar. The thin HfO_2 film had the dielectric constant of about 17 and the dielectric strength of about 24 MV/cm. The switch of PZT/HfO_2 stack dielectric showed isolation performance better than -20 dB in the frequency range of 1 ～ 35 GHz. The switch of HfO_2 had isolation performance better than -40 dB in the frequency of 5 ～ 35 GHz, suggesting its attractive prospective in practical broadband application.