Positronium annihilation in mesoporous thin films

SEMATECH, Austin, Texas 78741~Received 17 June 1999!Depth-profiled positronium lifetime spectroscopy is used to probe the pore characteristics~size, distribution,and interconnectivity! in porous, low-dielectric silica films. The technique is sensitive to the entire voidvolume, both interconnected and isolated, even if the film is buried beneath a metal or oxide layer. Ourextension of a simple quantum mechanical model of Ps annihilation in a pore adequately accounts for thetemperature and pore size dependence of the Ps lifetime for pore sizes in the range from 0.1 nm to 600 nm. Itis applicable to any porous media. @S0163-1829~99!51932-2#