The film thickness-dependent imprinting behavior (voltage shift) of (Pb, La
)(Zr, Ti)O-3 capacitors was evaluated by a thermal stress process under a r
emanence bias. The remanent polarization (P-r) was found to be almost indep
endent of the film thickness whereas in the 50-300 nm range the relative di
electric constant (epsilon (r)) increased linearly with the square root of
the film thickness. It was found that the voltage shift, which was attribut
ed to the accumulation of charged defects near the electrode interface, als
o increased linearly with increasing film thickness. In addition, the charg
e accumulated thickness varied with the square root of the film thickness.
This was established from a simple assumption that the level of charge accu
mulation is determined by the product of the total amount of charged defect
s (total film thicknessxcharged defect density) and the internal field that
is generated by the P-r. Therefore, the imprint is much more a bulk-relate
d degradation phenomenon compared to the fatigue. (C) 2001 American Institu
te of Physics.