Evaluation of Pore Structure in Pure Silica Zeolite MFI Low-kappa Thin Films Using positronium Annihilation Lifetime Spectroscopy

摘要

The pore size and pore structure in pure silica zeolite MFI in-situ and spin-on low dielectric constant(low-kappa)zeolite films were characterized by positronium annihilation lifetime Spectroscopy(PALS).For the micropores in the in-situ and spin-on films,the pore size obtained from the on-wafer PALS method is 0.55(+-)0.03 nm,and this is in excellent agreement with the known crystallographically determined zeolitic pore size(0.55 nm).To our knowledge this is the first comparison of a PALS thin film pore size measurement with a crystallographically defined zeolite pore size.For mesopores in the spin-on film,PALS results show that they are open/interconnected and give a pore size of 2.3-2.6 nm.