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
Received: 30 September 2016
Received in final form: 18 January 2017
Published online: 25 May 2017
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 SiCHxFy surface groups distributions inside the porous films are calculated as a function of F atoms dose. F atoms quasi-chemisorption on surface SiOx 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 OxSiFy 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 SiOx surfaces.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2017