Effect of ion beam bombardment on the properties of Ni films deposited on polyimide by ion beam assisted deposition

Highly textured Ni films were deposited on pristine and Ar+ ion pre-treated polyimide (PI) by ion beam assisted deposition (IBAD). Effect of Ar+ ion bombardment on the surface roughness of PI and the properties of Ni thin films deposited on pristine and pre-treated PI was investigated. The results showed that the structure, residual stress and temperature coefficient of resistivity (TCR) of the films were significantly sensitive to the energy and the ion flux of concurrent Ar+ ion bombardment. Surface roughness of PI increased after Ar+ ion bombardment. Increase of surface roughness of pre-treated PI improved the growth of Ni films in (111) preferential orientation due to the minimization of surface energy. Rearrangement of atoms due to enhanced surface diffusion caused by the ion bombardment reduced the residual stress of the films, and the pretreatment of PI substrate accelerated the decrease of film stress. The resistivity decreased and the TCR of the Ni films increased with the improvement of crystalline degree and the increase of grain size.