Patterned deposition of copper on poly(tetrafluoroethylene)

This paper reports on a three step process that has been developed for patterned deposition of Cu onto poly(tetrafluoroethylene) (PTFE). The first step involves patterned irradiation with low doses of x-rays of electrons which cross-link the PTFE surface; step tow involves chemical etching with the result that only the nonirradiated, noncross-linked areas are etched; and step three involves selective chemical vapor deposition (CVD) of Cu onto the etched surface at 200 degrees C using (hexafluoroacetylacetonato) Cu(l) trimethylphosphine (hfac) Cu(PMe3). The nonirradiated surface is a activated for selective Cu CVD by the chemical etching step, while the irradiated portions remain unactivated due to cross-linking. Continuous Cu films with resistivities of 4 μohm-cm are formed on the nonirradiated areas. X-ray photoelectron spectra show the nonirradiated areas of the surface to be covered by pure Cu with only surface impurities resulting from air transfer of the samples, while the irradiated areas show the presence of only C and F, characteristic of PTFE