Experimental Study Of Interface & Bulk Defectivity In Ultra-Thin BEOL Dielectrics By Using Low Frequency Noise Spectroscopy

Time-Dependent Dielectric Breakdown (TDDB) is used to assess dielectric failures. A limitation of TDDB is the lack of physical insight. In this paper, we therefore conduct a study, employing Low Frequency Noise (LFN), on the reliability of Back End Of Line (BEOL) dielectrics (SiCN and Al2O3). We carry out a stress experiment, in which the dielectric is sensed before and after stress. For SiCN, we find that deterioration is dominated by dielectric bulk defectivity. For Al2O3, however, metal-dielectric interface defectivity is the dominant contributor to deterioration. Our findings provide a physical explanation for peculiarities observed in TDDB.