C-C4F8 plasmas for the deposition of fluorinated carbon films

Abstract

Highly fluorinated polymeric (CFX), fluorine containing diamond-like carbon (F-DLC) and, for comparison, diamond-like carbon (DLC) films have been plasma deposited in a RF parallel plate reactor by using c-C 4F8 as fluorine precursor and different mixtures of argon, C2H2, and H2. Plasmas have been characterized by optical emission spectroscopy, mass spectrometry, and Langmuir probe measurements. Differences in the film composition and structure have been related with the type of species formed in the plasma and with the self-bias potential developed at the deposition electrode. Additional experiments using CF4 have confirmed that the formation in the plasmas of neutral or ionized CxFy species with x > 2 is a critical factor for the synthesis of fluorine rich films. This work addresses the use of c-C4F8 as plasma precursor for the synthesis of fluorinated carbon films, from fluorinated DLC to polymeric-like CFx, with different compositions and properties. A clue for their tailored synthesis in a RF parallel plate reactor is the plasma formation of CxFy (x > 2) fragments and their dependence on the self-bias potential and plasma gas composition. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.