Time dependent dielectric breakdown of paraelectric barium-strontium-titanate thin film capacitors for memory device applications

Barium-strontium-titanate (BST) is an important material for dynamic random access memory capacitor applications. In this work, BST thin films are prepared by the sol-gel method and metal-BST-metal capacitors are fabricated. The time dependent dielectric breakdown (TDDB) of the BST capacitors is measured and analyzed. A new extrapolation method is developed to obtain the TDDB lifetime from the time to breakdown (tBD) data. The leakage current is found to depend on the applied electric field in a power law relationship. The exponent in the power law relation is close to 1 in the low field region (lower than 16 MV/m) and is about 16.5 in the high field region (larger than 16 MV/m). A correlation between the leakage current and the TDDB lifetime is established. The extrapolated lifetime is about 1012 s at 3.3 V for 330-nm-thick films.