Plasma-induced charging damage of a ferroelectric capacitor during interconnect metal etch

Plasma-induced charging damage of a SrBi₂Ta₂O₉ (SBT) ferroelectric capacitor has been investigated during interconnect metal etch in fabrication of ferroelectric random access memory (FeRAM). Pattern dependency and the effect of etch parameters such as RF bias power, microwave source power, and pressure on the ferroelectric capacitor were evaluated with a 256 cell array. The etch parameters affected strongly the voltage shift of hysteresis loops so that the degradation could be suppressed by optimized etch process conditions. To evaluate the mechanism of the voltage shift, effects of top and bottom electrode area of the capacitor were also studied