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Ken NUMATA Yukio FUKUDA Katsuhiro AOKI Yasutoshi OKUNO Akitoshi NISHIMURA
This paper describes influence of the relaxation current in BaxSr(1-x)TiO3 (BST) thin films on dynamic random access memory (DRAM) operation. The relaxation current is a transient content of dielectric leakage currents. In BST thin films (expected to be a cell capacitor dielectric in 256 Mb DRAM and beyond), the relaxation current often displays the power law behavior I(t)t-1. This leads to the singularity near the time zero. When one attempts to evaluate precisely the influence of this leakage on DRAM operation, the behavior should be estimated on a time-dependent bias. However, such a singular behavior makes analysis based on a linear response difficult. In this analysis, we start by assuming that the behavior of the relaxation current can be modeled as a linear equivalent circuit. We also assume that the relaxation current follows the power law, I(t)t-1 for 1 ns