NEW ALPHA-PARTICLE INDUCED SOFT ERROR MECHANISM IN A 3-DIMENSIONAL CAPACITOR CELL

This paper describes the new alpha-particle induced soft error mechani sm, the Minority Carrier Outflow (MCO) effect, which may seriously aff ect the reliability of the scaled DRAMs with three dimensional capacit ors. The MCO charge increases as the device size miniaturizes because of the three dimensional capacitor effect as below. As the device scal es down, the storage node volume decreases which results in the higher minority carrier density in the storage node and larger outflow charg e. Also as the device plan view miniaturizes, the stack capacitor heig ht or trench depth does not scales down or even increases to keep the storage node capacitance, therefore the initially generated minority c arrier becomes larger. A simple analytical MCO model is introduced to evaluate the MCO effect quantitatively. The model agrees well with the three dimensional device simulation. The MCO model predicts that the life time of the minority carrier in the storage node strongly affects the MCO charge, however, even when the life time is as small as the o rder of 100 ps, the MCO effect can be the major soft error mechanism.