Chemical vapor deposition of fluorocarbon films for low dielectric constant thin film applications

Abstract

Pulsed plasma enhanced and hot filament chemical vapor deposition have produced fluorocarbon films with the potential use as low dielectric constant interconnect materials in microelectronic circuits. Solid-state nuclear magnetic resonance spectroscopy was demonstrated as a valuable film characterization tool to understand structure-property processing fundamentals, quantifying film bonding environments and tracing structural instabilities. Thermal lability in fluorocarbon films was attributed to terminal end groups and low molecular weight molecules. High temperature thermal stability was achieved by minimizing such labile sources through a clean deposition of high molecular weight chains of poly(tetrafluoroethylene). Poly(tetrafluoroethylene) film porosity was introduced and controlled through the competition between nucleation and growth of film. Porous poly(tetrafluoroethylene) films were further integrated into a bridge layer and air gap dielectric interconnect scheme. With fluorocarbon materials deposited through such chemical vapor deposition methods, dielectric constants ranging from 2.1 to below 1.5 were conceivably attainable, thus potentially satisfying dielectric interconnect requirements to beyond the 0.1 [mu]m technology node.