Characterization of Low-k SiOCH Layers in fine-pitch Cu-damascene interconnects by monoenergetic positron beams

Pore characteristics of SiOCH layers in fine-pitch Cu-damascene interconnects were studied using monoenergetic positron beams. Doppler broadening spectra of the annihilation radiation and lifetime spectra of positrons were measured for the samples fabricated with the line/space widths of 0.27/0.27 and 1.08/1.08 mum, respectively. From measurements of the positronium (Ps) lifetimes, the mean pore size was estimated. The Ps intensity in SiOCH was found to be decreased by the scaling, which was attributed to the damage introduced during the damascene process.