Title :
Reliability of laser-induced metallic vertical links
Author :
Zhang, Wei ; Lee, Joo-Han ; Chen, Yuan ; Bernstein, Joseph B. ; Suehle, John S.
Author_Institution :
Dept. of Reliability Eng., Maryland Univ., College Park, MD, USA
fDate :
11/1/1999 12:00:00 AM
Abstract :
A new method has been proposed to form electrical connections vertically between two levels of metallization by using a commercial pulsed IR laser system. Samples were stressed at accelerated current densities and temperatures. The failure activation energy has been found to be about 0.66 eV, from which electromigration is identified as a main failure mode. The extrapolated mean time to failure (MTTF) at room temperature and accelerated current density of 3 MA/cm2 is about 38 years. The dependence of MTTF on laser energy has also been obtained, showing agreement with the resistance dependence on laser energy. Focused ion beam (FIB) cross sections suggest that the laser process-induced voids in the lower line limit the lifetime of links. Furthermore, a modified structure is proposed to improve the electromigration reliability. From the reliability point of view, this study shows that the laser-induced vertical link has sufficient reliability for practical implementation
Keywords :
current density; electromigration; failure analysis; focused ion beam technology; integrated circuit metallisation; integrated circuit yield; laser materials processing; 0.66 eV; 38 yr; accelerated current densities; accelerated current density; electromigration; extrapolated mean time to failure; failure activation energy; focused ion beam cross sections; laser process-induced voids; laser-induced metallic vertical links; metallization levels; pulsed IR laser system; Acceleration; Current density; Dielectrics; Electromigration; Integrated circuit reliability; Laser beam cutting; Laser modes; Metallization; Optical pulses; Temperature;
Journal_Title :
Advanced Packaging, IEEE Transactions on
DOI :
10.1109/6040.803453
