Abstract
The porosity in thin (∼1 μm) mesoporous low dielectric constant (low-k) films is investigated by different beam-based positron annihilation spectroscopy (PAS) techniques. Examples are given for mesoporous methyl-silsesquioxane films deposited with a sacrificial polymer (porogen, from 0 to 90 wt % load) and subsequently annealed to drive out the volatile porogen, resulting in films with nanometer size voids. The important features of positronium (Ps; an electron−positron atom-like bound state) interaction with porous materials (formation, confinement, diffusion, thermalization, and annihilation) are highlighted. Ps was identified as an especially suitable probe for identifying open porosity, manifested by Ps escape in a vacuum. Three-photon (3γ) PAS was utilized to derive the length-scale for pore interconnectivity prior to total percolation, and open porosity fraction as a function of the porogen load. Lifetime spectroscopy (PALS) was used to obtain the pore size distribution, and the Ps energy is assessed using the momentum-sensitive PAS techniques. For the mesoporous low-k films, these two complementary techniques yield the vast majority of the porosity properties assessable by PAS. The necessity for future improvements in the PAS analysis, as well as a broad-scale comparison with other diagnostic techniques is discussed.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
