Title :
New insight in BEOL TDDB Cu diffusion mechanism: A constant current stress approach
Author :
Tian Shen ; Hao Jiang ; Wenyi Zhang ; Cahyadi, Tommy ; Eng Chye Chua ; Capasso, Cristiano
Author_Institution :
Quality & Reliability Assurance, GLOBALFOUNDRIES, Malta, NY, USA
Abstract :
The Time Dependent Dielectric Breakdown (TDDB) of Ultra-Low-κ (ULK) (κ=2.7) and porous ULK SiCOH (κ=2.55) was systematically investigated using both Constant Current Stress (CCS) and Constant Voltage Stress (CVS) method on our 32nm and 28nm technologies. The invariance of J2t unambiguously suggest that the NBlock-IMD interface Cu diffusion is the dominant failure mechanism. Also, the electric field independent TDDB thermal activation energy was experimentally identified. By comparing the distribution of tBD and J2tBD obtained by CVS, J2tBD gives a better β value closer to intrinsic because die to die spatial variations are automatically compensated. The extracted β is also consistent with that from Poisson area scaling study. At high current stress conditions, J2tBD start to drop, indicating another failure mechanism starts to dominate. In summary, the evaluation of J2tBD provides a new insight in the low-κ TDDB breakdown mechanism.
Keywords :
copper; diffusion; electric breakdown; low-k dielectric thin films; porous materials; silicon compounds; BEOL TDDB Cu diffusion mechanism; CVS method; Cu; NBlock-IMD interface Cu diffusion; Poisson area scaling study; SiCOH; constant current stress approach; constant voltage stress method; die to die spatial variations; dominant failure mechanism; electric field; low-κ TDDB breakdown mechanism; porous ULK SiCOH; size 28 nm; size 32 nm; thermal activation energy; time dependent dielectric breakdown; ultra-Low-κ TDDB; Dielectrics; Electric breakdown; Failure analysis; Leakage currents; Reliability; Stress; Voltage measurement; CCS; Cu diffusion; low-κ TDDB; low-κ reliability;
Conference_Titel :
Reliability Physics Symposium, 2014 IEEE International
Conference_Location :
Waikoloa, HI
DOI :
10.1109/IRPS.2014.6860614