Processing and characterization of fluorinated amorphous carbon low-dielectric-constant films

Continuous fluorinated amorphous carbon (a-C:F) films with low dielectric constants (low-k), relatively low surface roughness, and low refractive indices were deposited by plasma-enhanced chemical vapor deposition using CF4 and C2H2 gases as precursors. A uniform composition was obtained except surface fluorination with an F-rich layer. The deposition rates, fluorine contents, and refractive indices of these films varied with the deposition parameters, including CF4 feed gas concentration, processing pressure, plasma power, and substrate temperature. The a-C:F films with higher fluorine contents had lower refractive indices but possessed smaller hardnesses and elastic moduli. During thermal annealing, fluorine was released from these films, but the interface adhesion to the substrates was improved. Plasma post-treatment altered the surface compositions of the films, while the interior compositions, refractive indices, and mechanical characteristics remained unchanged. (C) 2004 The Electrochemical Society.