Investigation Between 2- Terminal and 4- Terminal Kelvin Structure in Terms Of WLR ISOEM And PLR EM for Metal Interconnection

Abstract

Electromigration performance is a key index for BEOL process reliability, in this paper, 2-terminal and 4-terminal kelvin structure EM tests are performed in both WLR IsoEM and PLR EM method, it's found 2-terminal WLR IsoEM test time is faster than that of 4 terminal kelvin structure under the same desired temperature stress condition, the TTF ratio is about 0.6 and 0.5 times for narrow metal (MxN) and wide metal (MxW) respectively. Besides, Iso-EM TTF increases with the rising of the chuck temperature and lower layer metal shows worse than the upper. While on the contrary, 2 terminal PLR EM TTF is bigger than that of 4 terminal. This distinct observation is investigated and its mechanism is discussed in the paper.