Reliability of laser-induced metallic vertical links

A new method has been proposed to form electrical connections vertically be tween two levels of metallization by using a commercial pulsed TR laser sys tem. Samples were stressed at accelerated current densities and temperature s. The failure activation energy has been found about 0.66 eV, from which e lectromigration is identified as a main failure mode. The extrapolated mean time to failure (MTTF) at room temperature and accelerated current density of 3 MA/cm(2) is about 38 years, The dependence of MTTF on laser energy ha s also been obtained, showing agreement with the resistance dependence on l aser energy. Focused ion beam (PTB) cross sections suggest that the laser p rocess-induced voids in the lower Line limit the lifetime of links, Further more, a modified structure is proposed to improve the electromigration reli ability, From the reliability point of view, this study shows that the lase r-induced vertical link has sufficient reliability fur practical implementa tion.