Effect of pore interconnection on Cu-diffusion-induced failures in porous spin-on low-k dielectrics

Abstract

The porosity dependence of electric reliability in the spin-on low-k dielectric with the same matrix but with various porosities was examined using time-dependent dielectric breakdown and capacitance voltage measurements. Abrupt changes in the time to dielectric breakdown and a flatband voltage shift were observed when the porosity of low-k dielectrics was between 20% and 30%. Such a characteristic agrees with the positronium annihilation lifetime spectroscopy data, which indicates that the interconnectivity of the pores abruptly increased in those materials with a porosity between 20% and 30%, and it causes an increase in Cu-diffusion-induced failures.