Time Dependent Dielectric Breakdown Characteristics of Low-k Dielectric (SiOC) Over a Wide Range of Test Areas and Electric Fields

Abstract

Time-dependent dielectric breakdown (TDDB) of low-k dielectrics is reported for fully integrated carbon-doped silica dielectric (SiOC, k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> =2.9) at wafer level over a wide range of area and electric-field test conditions at 105degC. In addition, long-term package level TDDB data were taken at 105degC for over 2 years on integrated comb-serpent test structures. The field acceleration parameter (gamma=4.5 plusmn 0.5 cm/MV) was found to be approximately independent of area (over 4 decades of area) and over a wide range of field (1.5-6.0 MV/cm), respectively. TDDB data, taken over long periods, agree well with predictions based on more rapid wafer-level TDDB testing. The low-k TDDB data suggest that, while the time-to-failure is a strong function of area and field, the time-to-failure physics does not vary greatly for fully integrated SiOC films as both the area and field are scaled. Furthermore, the fact that gamma is approximately constant (independent of area and applied E-field) indicates that silica-based low-k dielectric TDDB follows closely a thermochemical E-model for all areas and fields examined.