Effects of annealing and interlayers on the adhesion energy of copper thinfilms to SiO2/Si substrates

The adhesion of sputtered copper thin films was measured with a quantitativ e indentation technique utilizing refractory superlayers to trigger and pro mote delamination. Adhesion energies of the indentation-induced delaminatio ns were analyzed in terms of the critical strain energy release rate. Two g roups of films were investigated. Group I ranged in thickness from 225 to 1 000 nm in both the as-deposited and annealed condition. Adhesion enemies ra nged from 2 to 15 J/m(2), with higher adhesion for the annealed condition. Group II films had nominal thicknesses of 430 and 1100 nm, some with 7-10 n m interlayers of either titanium or chromium. Adhesion energies of these fi lms ranged from 4 to 30 J/m(2), increasing by a factor from 1.3 to 7.5, as a function of the interlayer presence and type with the increase in energy due to a chromium interlayer exceeding that of titanium. Adhesion energies increased with film thickness for all films, with interlayers and annealing producing a larger increase. These quantitative results were compared to p revious semi-quantitative and quantitative results, and shown to have compa rable magnitudes and trends. (C) 1998 Acta Metallurgica Inc. Published by E lsevier Science Ltd. All rights reserved.