Numerical simulation of hard errors induced by heavy ions in 4T high density SRAM cells

2D numerical simulation of local dose deposition effects in N channel MOS transistors are presented in order to explain experimental observation of stuck bits in 4 T resistor loaded cells of high density SRAMs irradiated by heavy ions. The ion impact location in the channel is shown to strongly modulate the observed threshold voltage shift. This shift variation versus the inverse channel length is super linear, so more important effects are expected for 4T cells as transistor dimensions are reduced