This work presents a systematic study of the off-state drain bias time dependent dielectric breakdown (TDDB) mechanism, especially for the short channel transistors in advanced FinFET technologies. The sub-threshold leakage current was found to play a key role in determining the off-state drain bias TDDB degradation. Short channel transistors show higher electric field (E-Field) near the drain side due to increase in sub-threshold leakage current and hence, the breakdown lifetime is seen to scale with decrease in channel length. Moreover, with additional process optimizations, such as source/drain proximity push, the sub-threshold leakage current increases which results in worse off-state TDDB and shorter lifetime during practical circuit stress conditions. Also, impact of body bias on sub-threshold current is also studied in this work.