A comprehensive breakdown model describing temperature dependent activation energy of low-к/extreme low-к dielectric TDDB

Temperature dependent activation energy (E_a) has been observed for backend low-κ (LK) and extreme LK (ELK) dielectric TDDB. We experimentally demonstrated that the charge transport through the LK/ELK is dominated by the Poole-Frenkel mechanism, even in the low E-field, and Cu-ion diffusion occurs at a later stage of stressing, which is more probable at high temperatures and in sub-65nm (40-28nm) technologies with ELK dielectric. Hence, the TDDB lifetime prediction at nominal operating conditions on the basis of elevated temperature experiments should take the temperature dependent E_a into consideration. Based on the power-law relation between current and stress time at different temperatures, a comprehensive breakdown model of LK/ELK is proposed, which describes LK/ELK temperature dependent TDDB activation energy is associated with both the trap creation and the ion diffusion processes.