INTERFACE STRUCTURE BETWEEN POLYIMIDE FILM SUBSTRATE AND COPPER FILM PREPARED BY ION-BEAM AND VAPOR-DEPOSITION (IVD) METHOD

The effects of improvement of copper film adhesion prepared on polyimi de film substrate were investigated. The copper thin films on polyimid e films were prepared by evaporation of copper metal and simultaneous irradiation of argon gas ions with energies in the range of 0.5 to 10. 0 keV. The structures at the interface between the copper films and po lyimide substrates were analyzed by transmission electron microscopy ( TEM). TEM analysis showed that the ion bombardment formed the mixed la yer which consisted of the polyimide elements and copper atoms at the interface. The thicknesses of the intermixed layers were evaluated by using energy dispersive X-ray spectroscopy (EDXS) analysis, The thickn esses of the mixed layers were increased with an increase of ion dose and ion energy. The adhesion of copper films was evaluated by means of a peel test. The test showed that the film adhesion was dependent on the conditions of the ion bombardment, the adhesion was improved by th e formation of the intermixed layer, but high energy ions, which incre ased the thicknesses of the intermixed layers, decreased the film adhe sion. It is revealed that the high energy ions caused the carbonizatio n at the polyimide surfaces. The improvement of the film adhesion depe nds on the formation of intermixed layer but also on the carbonization at the polyimide surface.