Application of IDDT test towards increasing SRAM reliability in nanometer technologies

Abstract

Dynamic supply current test method (IDDT test) in static random access memory (SRAM) cell arrays is addressed in order to unveil weak open defects. Simulations were carried out on a 64-bit SRAM circuit, where several parameters of the IDDT waveform were monitored. The SRAM circuit was designed in a 90 nm CMOS technology. Efficiency of IDDT test in unveiling open defects was evaluated and the achieved results were compared for four SRAM arrays with cells of different cell ratio (CR). Moreover, a solution for transformation of the dynamic current to voltage is presented. After the transformation of the current waveform to a voltage waveform, the parameters of the voltage waveform similar to those of the current waveform are easily monitored and evaluated.