Novel Damage Curing Technology on One-Mask Etched Ferroelectric Capacitor for Beyond 0.25 μm FRAM

Abstract

In order to manufacture high-density ferroelectric random access memory (FRAM) device, it is required to develop one mask capacitor etching technology, because it can provide greatly reduced cell size. However, as the capacitor size shrinks further, the influence of etching damage on the ferroelectric properties becomes much serious due to the high ratio of perimeter/area for patterned capacitor. Since undesired polymeric etch byproducts were formed on sidewall of the edge cell capacitors in 32 Mb FRAM with 0.25 μm design rule, we developed novel post-etch curing technology using O2 plasma treatment with wet cleaning process. After the post-etch curing treatment, the hysteresis loops of block edge cells were almost identical to those of block center cells, which results in improving the relative 2Pr value as ratio of edge cells/center cells from 33% to 98%. In conclusion, novel curing technology was successfully developed for one mask etching damaged ferroelectric capacitor using O2 plasma treatment with wet cleaning process, resulting in high wafer yield.