CVD copper thin film deposition using (alpha-methylstyrene)Cu(I)(hfac)

A new volatile liquid copper precursor, (alpha -methylstyrene)Cu(I)(hfac), has been synthesized. A green liquid solution of (alpha -methylstyrene)Cu(I )(hfac), stabilized with Cu(hfac)(2) and alpha -methyl styrene, can be used for CVD copper thin film deposition. In contrast, pure yellow (alpha -meth ylstyrene)Cu(I)(hfac) failed in CVD processing because of poor stability in the delivery system. The structure of solid crystalline [(alpha -methylsty rene)Cu(I)(hfac)](2)[Cu(hfac)(2)], collected from the concentrated green li quid precursor solution, was obtained by x-ray crystallography. In copper t hin film deposition using the green liquid precursor, a two-step water intr oduction process has been proposed for the purposes of obtaining good adhes ion on metal nitride coated substrates and low bulk resistivity. The film p urity was analyzed by SM. The effects of various process conditions have be en studied, from which the film deposition activation energy was calculated as 12.82 Kcal/mol for deposition temperatures lower than 180 degreesC. The resistivity of the copper thin films was measured as 1.92 mu Omega -cm whe n deposited at 190-200 degreesC. Good film conformality and gap filling has also been demonstrated using this new copper precursor.