Quantitative analysis of the bit size dependence on the pulse width and pulse voltage in ferroelectric memory devices using atomic force microscopy

The Bit formation using atomic force microscopy (AFM) was studied on 270-nm -thick < 111 > preferentially oriented Pb(Zr0.4Ti0.6)O-3 (PZT) films prepar ed by the sol-gel process. To minimize the cantilever-sample capacitive far ce interaction, the experiment was carried out at or near the sample edge. Bit formation was investigated by calculating the electric field in AFM-tip /PZT film/bottom electrode configuration. It was found both experimentally and theoretically that:the bit size is linearly dependent on the pulse volt age-and the logarithmic value of the pulse width, The linear dependence of the bit size on the logarithmic value of pulse width was explained from the relationship between the switching time and electric field. It was found t hat the minimum bit size of a fully penetrating domain equals the film thic kness. (C) 2001 American Vacuum Society.