Contributions of CF and CF2 Species to Fluorocarbon Film Composition and Properties for CxFy Plasma-Enhanced Chemical Vapor Deposition

Inductively-coupled C-x.F-y (y/x = 2.0-4.0) plasma systems were investigated to determine relationships between precursor chemistry, CFn radical-surface reactivities, and surface properties of deposited films. The contributions of CFn (n = 1, 2) radicals to film properties were probed via gas-phase diagnostics and the imaging of radicals interacting with surfaces (IRIS) technique. Time-resolved radical emission data elucidate CF(g) and CF2(g) production kinetics from the CxFy source gases and demonstrate that CF4 plasmas inherently lag in efficacy of film formation when compared to C2F6, C3F8, and C3F6 systems. IRIS data show that as the precursor y/x ratio decreases, the propensity for CFn scatter concomitantly declines. Analyses of the composition and characteristics of fluorocarbon films deposited on Si wafers demonstrate that surface energies of the films decrease markedly with increasing film fluorine content. In turn, increased surface energies correspond with significant decreases in the observed scatter coefficients for both CF and CF2. These data improve our molecular-level understanding of CFn contributions to fluorocarbon film deposition, which promises advancements in the ability to tailor FC films to specific applications.