Evaluation of self-organized diffusion barrier continuity on a nano-architectural silica thin film with two-dimensionally connected cage-like pores using positronium time of flight spectroscopy

Positronium time of flight (Ps-TOF) was measured by implanting slow positron pulses at variable energies into a nano-architectural silica thin film with two-dimensionally connected cage-like pores to investigate a continuity of the self-organized extremely thin diffusion barrier between the pores. By comparing a capped and open-pored low-k film, we found a Ps-TOF spectrum with positron implantation energy of 0.2 keV that reflects the sample structure is consistent with an open pore fraction η < 1.7 · × 10−6 of the diffusion barrier.