A novel low temperature process for titanium nitride (TiN) deposition by means of an electron cyclotron resonance (ECR) plasma CVD process was applied to poly(tetrafluoroethylene) (PTFE). The organometallic compound tetrakis(dimethylamido)titanium (TDMAT) introduced into the downstream region of a nitrogen ECR plasma was used as a precursor for TiN deposition at 100°C.
The thin TiN films (thickness 15-30 nm) act as interlayers to activate the electroless deposition of copper followed by an electroplating process. Prior to the deposition of the interlayer, the samples were treated on a biased susceptor with argon ions to enhance the adhesion of the TiN interlayer. This metallization procedure avoids the use of toxic and pollutive etching agents and yields adherent copper layers on PTFE.
The maximum adhesion of the metal film on PTFE was established to be 13 N/mm2. As shown by atomic force microscopy (AFM), TiN grains were formed on the fluoropolymer surface. Film composition was investigated by secondary ionization mass spectrometry (SIMS).