Plasma-Assisted Dry Etching of Ferroelectric Capacitor Modules and Application to a 32M Ferroelectric Random Access Memory Devices with Submicron Feature Sizes

Authors report the ferroelectric property of patterned submicron capacitor modules with a stack height of 380 nm, where the 100 nm-thick Pb(Zr, Ti)O3 (PZT) films were prepared by the sol-gel method. After patterning, overall sidewall slope was approximately 70 degrees and cell-to-cell node separation was made to be 80 nm to prevent possible twin-bit failure in the device. Finally, several heat treatment conditions were investigated to retain the ferroelectric property of the patterned capacitor. It was found that rapid thermal processing treatment yields better properties than conventional furnace annealing. This result is directly related to the near-surface chemistry of the PZT films, as confirmed by XPS analysis. The resultant switching polarization value of the submicron capacitor was approximately 30 mu C/cm2 measured at 3 V. 10 refs.