Enhanced Cu-Teflon adhesion by presputtering prior to the Cu deposition

Abstract

Adhesion of Cu to Teflon has been studied by depositing Cu to Teflon with and without a presputtering prior to the Cu deposition. Without presputtering, a weak adhesion is observed, with a value of 1 g/mm, which fails the scotch tape test. With a presputtering using 500 eV Ar+ ions, the adhesion rapidly increases, becoming evident after a sputtering of 10 s, and reaches maximal increases of 50 times at longer sputtering times. All the Cu films deposited after presputtering show strong adhesion, and can only be removed by forceful scratching with sharp tools. The presputtering was shown to change both the surface morphology of Teflon, with the deposited Cu following the morphologies created, and the interface chemical bonding between Cu and Teflon as revealed by x-ray photoelectron spectroscopy. Exposure of the presputtered Teflon to air prior to the Cu deposition shows no effect on the strong adhesion obtained. An interface bonding model is suggested for the enhanced adhesion observed.