Highly Conductive Cu Thin Film Deposition on Polyimide by RF-Driven Atmospheric Pressure Plasma Jets under Nitrogen Atmosphere

The use of Ar/H-2 atmospheric pressure plasma jets driven by a 13.56 MHz RF wave source with a Cu inner conductor was investigated for the deposition of highly conductive Cu thin films on polyimide substrates. It was found that the intensities of the Cu atom emission line were significantly increased by the addition of H-2 gas to the Ar plasmas. Secondary emission microscopy analysis indicated that the Cu films exhibited agglomerated structures with grains of several microns, which were larger than those produced using Ar plasma jets. It was found that the conductivity of Cu thin films prepared in nitrogen was 10 6 times higher than that of films produced using Ar/H-2 plasma jets with 10 sccm H-2, and 4 times higher than that for films produced using identical Ar/H-2 plasma jets in air.