Fundamentals and technology for monolithically integrated RF MEMS switches with ultra-nanocrystalline diamond dielectric/CMOS devices

Most current capacitive RF-MEMS switch technology is based on conventional dielectric materials such as SiO2 and Si3N4. However, they suffer not only from charging problems but also stiction problems leading to premature failure of an RF-MEMS switch. Ultrananocrystalline diamond (UNCD(R) (2-5 nm grains) and nanocrystalline diamond (NCD) (10- 100 nm grains) films exhibit one of the highest Young's modulus (~ 980-1100 GPa) and demonstrated MEMS resonators with the highest quality factor (Q ≥10,000 in air for NCD) today, they also exhibit the lowest force of adhesion among MEMS/NEMS materials (~10 mJ/m2-close to van der Waals' attractive force for UNCD) demonstrated today. Finally, UNCD exhibits dielectric properties (fast discharge) superior to those of Si and SiO2, as shown in this paper. Thus, UNCD and NCD films provide promising platform materials beyond Si for a new generation of important classes of high-performance MEMS/NEMS devices.

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