Gate-Induced Drain-Leakage (GIDL) Programming Method for Soft-Programming-Free Operation in Unified RAM (URAM)

Abstract

A soft-programming-free operation method in unified RAM (URAM) is presented. An oxide/nitride/oxide (O/N/O) layer and a floating-body are integrated in a FinFET, thereby providing the versatile functions of a high-speed capacitorless 1T-DRAM, as well as nonvolatile memory, and the mode of the memory cell can be selected and independently utilized according to the designer's demand. With the utilization of the impact ionization method for IT-DRAM programming, undesired soft charge trapping into O/N/O gradually shifts the threshold voltage, resulting in an unstable operation in the URAM. In order to avoid such problems associated with soft programming, a gate-induced drain-leakage (GIDL) program method is proposed for improved immunity to disturbance. It is found that the GIDL method effectively suppresses soft programming without sacrificing the sensing current window.