Effect of ZnO Film Thicknesses on the Adhesive Strength of Electroless Cu TDeposits

The effect of ZnO film thickness on the adhesive strength of electroless Cu deposited on ZnO-coated glass substrates was examined. An increase of adhesive strength of the Cu deposits with increasing ZnO film thickness was observed. Excellent adhesion was obtained on ZnO films thicker than 0.6 microm, which is considered to be associated with the formation of rougher, more porous structures. XPS data combined with SEM and AFM measurements showed that in addition to the surface area effect, the mechanical anchoring effect caused by Cu depositing deeply within the ZnO film may also play an important role in obtaining the excellent adhesion of the Cu deposits on thicker ZnO films.