Eur. Phys. J. D (2017) 71: 126
https://doi.org/10.1140/epjd/e2017-70619-7

Regular Article

Fluorine atoms interaction with the nanoporous materials: experiment and DFT simulation^*

¹ Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, 119991 Moscow, Russia
² Faculty of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia

^a e-mail: voroninaen@nsrd.sinp.msu.ru

Received: 30 September 2016
Received in final form: 18 January 2017
Published online: 25 May 2017

Abstract

Fluorine atoms interactions with organosilicate glass (OSG)-based low-κ dielectric films are experimentally and theoretically studied. One-dimensional 1-D Monte Carlo & gas-surface kinetics (MC&GSK) model and density functional theory (DFT) simulations used for the development of the multi-step mechanism of OSG films damage and etching are further verified on FTIR spectroscopy data. DFT method is applied to calculate vibrational mode frequencies and their shifts under F atoms flux. In the frame of 1-D model, evolutions of the SiCH₃ and appeared SiCH_xF_y surface groups distributions inside the porous films are calculated as a function of F atoms dose. F atoms quasi-chemisorption on surface SiO_x groups accompanied by fourth-coordinated Si atoms transition to pentavalent Si states is related with the experimentally observed fast fluorination stage and vibrational frequency shifts. In addition, quasi-chemisorbed F atoms induce the weakening of the adjacent Si–O bonds in O_xSiF_y surface complexes promoting breaks of these Si–O bonds under further F atoms attacks. Quasi-chemisorbed F atoms could be also responsible for F atoms recombination on SiO_x surfaces.