Metallization of Polymers Using Plasma‐Enhanced Chemical Vapor Deposited Titanium Nitride as Interlayer

A low-temperature process for titanium nitride (TiN) deposition by means of an electron cyclotron resonance plasma chemical vapor deposition process was applied to poly(tetrafluoroethylene), polyimide, benzocyclobutene, and poly(butyleneterephthalate). The organometallic compounds tetrakis(dimethylamido)titanium or titanium(IV)isopropoxide introduced into the downstream region of a nitrogen electron cyclotron resonance plasma were used as precursors for TiN deposition at 100°C. The thin TiN film (thickness 15 to 30 nm) acts as a conductive interlayer for the electroplating process or as adhesion promoter for sputtered titanium films. 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 for polymer activation as well as a electroless metal deposition. The maximum adhesion of the electroplated copper on poly(tetrafluoroethylene) and poly(butyleneterephthalate) was established to be 13 and 21 N mm -2 , respectively. For sputtered Ti films on polyimide and benzocyclobutene, maximum adhesion was 16 and 21 N mm -2 , respectively. As shown by atomic force microscopy, TiN grains were formed on the polymer surface. Film composition was investigated by secondary ion mass spectrometry.