Single Event Upsets Simulation in Scaled Down SRAM Elements

The presented work displays the research of critical charge Qcrit that leads to current impulse occurring in the semiconductor structure of static random access memory (SRAM) elements and becoming the cause of their single event upset (SEU) caused by heavy ion incident on the most sensitive drain-gate region of memory cell. The aim of research work is to simulate the impact of heavy ion strike into a semiconductor structure, to obtain the current impulse profile and calculate the critical charge Qcrit leading to SEU in the varying range of design standards of SRAM cells. The research methods are modeling the impact of a heavy particle and obtaining a current surge by SPICE simulation methods in LTspice CAD, as well as modeling the physical process of impact of an incident heavy ion onto semiconductor structure with certain dimensions and predetermined doping concentrations in TCAD. According to the results it was found that with an increase of technological process of 65 nm. by 38.4% (for 90 nm.), the sensitivity to the critical charge fell by 23.5%. With a further increase of technological process (for 130 nm.) by 38.4%, sensitivity to critical charge fell by 28.5%. On this topic, there were collected data on the research methods patents for assessing the sensitivity of memory cells to a critical charge and it was found that this method relevant nowadays since it allows one to take into account significant parameters for a given physical process occurring in a semiconductor upon impact of the heavy ion strike. The work contains 57 figures, 10 tables and 15 formulas. The results can be used in the aerospace industry during the manufacturing process of SRAM elements.