Effect of plasma treatments on a low-k dielectric polymer surface

Abstract

The ongoing transition to lower dimension devices requires the replacement of SiO2 by a lower-k dielectric insulator. Such materials are porous, introducing the need for sealing against penetration of gaseous and/or liquid species during subsequent processing. In this work, we investigate the effect of different plasma treatments on a porous low-k polymer film. Ion bombardment induces the formation of a dense surface layer capable of sealing the polymer. A competing etching reaction by the plasma gases determines the extent of the densified layer. Structural and chemical changes induced by the plasma treatments can extend into the bulk of the film and irreversibly change its properties. Exposing the plasma treated films to chemical precursors during an atomic layer deposition process is used to test sealing. The sealing behavior is discussed in view of the reactivity of the plasma and the post sealing temperature treatment.