Damage characterization of low-k layers through Cu damascene process using monoenergetic positron beams

Pore in low-k SiOCH and vacancies in electroplated Cu buried in damascene structures were studied using monoenergetic positron beams. Doppler broadening spectra of the annihilation radiation and lifetime spectra of positrons were measured for the samples through Cu/low-k damascene processes. The mean pore size in SiOCH decreased after contact etching, but kept constant during Cu metallization. The metallizaton process, however, introduced a certain amount of electron/hole-traps into SiOCH. The presence of vacancy clusters in the Cu damascene lines was confirmed.