Electroless plating of glass and silicon substrates through surface pretreatments involving plasma-polymerization and grafting processes

Electroless plating of nickel (or copper) was carried out on glass (or silicon) substrates that were previously surface modified by using plasma-polymerization and grafting processes, and then activated by immersion in a simple acidic PdCl2 solution. Three pretreatments based on the deposition of plasma-polymerized thin films (PACVD process) on O-2 plasma-cleaned substrates were investigated. They include film deposition of (1) amorphous hydrogenated carbon (a-C:H) grown from CH4, whose surface is subsequently plasma-functionalized in NH3 or N-2; (2) amorphous hydrogenated carbon nitride (a-CNx:H) grown from CH4/NH3 or CH4=N-2 mixtures; and (3) amorphous hydrogenated carbon nitride grown from volatile organic precursors (allylamine, acetonitrile). In the three cases, X-ray photoelectron spectroscopy (XPS) results show that chemisorption of the catalyst occurs on the nitrogen-containing functionalities created by plasma polymerization and grafting and thus that the electroless deposition is possible. Differences were observed depending on the nature and thickness of the plasma-polymerized thin films, as well as on the nature and concentration of the nitrogen-containing functionalities present or grafted at the surface. Practical adhesion of Ni films was investigated using a Scotch(R) tape test. Ni films up to 3 or 4 mum in thickness were shown to pass this test successfully, i.e., without causing any metal detachment.