Ultrananocrystalline diamond films with optimized dielectric properties for advanced RF MEMS capacitive switches

A process for fabricating a radio frequency (RF) microelectromechanical switch (MEMS) capacitive switch, comprising the steps of:

• providing a substrate;
• placing a bottom electrode on the substrate;
• depositing layers of ultrananocrystalline diamond (UNCD) thin film on the bottom electrode by microwave chemical vapor deposition (CVD) with a microwave CVD plasma gas comprising argon (Ar), methane (CH4) and hydrogen (H2) to form multilayered UNCD dielectric films including
• depositing a bottom UNCD layer on the bottom electron with H2 flow for rapid nucleation of the UNCD and forming a substantially continuous dielectric film;
• depositing an intermediate UNCD layer on the bottom UNCD layer with a higher H2 flow and forming a higher resistivity film with a hydrogen enriched grain boundary;
• depositing an upper UNCD layer on the intermediate UNCD layer with a lower H2 flow than for the intermediate UNCD layer for dense nucleation of the UNCD to fill in the gaps or pinholes between grains and forming a substantially continuous layer;
• positioning a moveable metallic membrane above the multilayered UNCD dielectric film;
• positioning a top electrode above the membrane;
• and
• forming a long life RF MEMS capacitive switch with the multilayered UNCD dielectric film, membrane, electrodes and substrate so that the RF MEMS capacitive switch is operable for more than 100 billion cycles.