Determination of the sensitive volume and critical charge for induction of SEU in nanometer SRAMs

In this paper, the sensitive volume and critical charge of a 65-nm CMOS SRAM as two important quantities in Single Event Upset (SEU) calculations have been determined. SEU is the most common event in space investigations. To this purpose, a memory cell which is consisted of NMOS and PMOS was simulated using Silvaco TCAD tool. Then, the variations in output voltages were studied after striking incident particles with different values of Linear Energy Transfer (LET) at different regions of the transistors. The Qcritical was obtained by integrating the output current when the output voltages were inverted. To determine the sensitive volume, the minimum amount of LET in which the output logic state of the memory cell flips, was considered as a criteria of sensitivity. The results showed the value of 0.054 µm3 and 1.48 fC for sensitive volume and critical charge, respectively which are in good agreement with the references.