Pore sealing mechanism in OSG low-k films under ion bombardment

Organosilicate glass (OSG) nanoporous films with a low dielectric constant (low-k) are used as interlayer-dielectric insulators for advanced interconnects of ultra-large-scale integration devices. Plasma treatment of these materials can lead to their degradation resulting in increasing k-value and reducing lifetime and reliability. However, for some OSG films, the densification of the uppermost surface layer and pore sealing was observed under ion irradiation. This paper presents the results of a combined experimental and modeling study of mechanisms of low-k film densification by ion bombardment depending on the film-pore size, ion type, and energy. The obtained results reveal that experimentally observed densification and pore sealing of uppermost layers of OSG films occur via collapse of near-surface pores under the impact of energetic ions.