Effects of electrical stress parameters on polarization loss in ferroelectric P(L)ZT thin film capacitors

The effects of stress parameters (e,g,, stress magnitude, frequency, and pulse shape) on the loss of DRAM polarization during unipolar pulse stressing in sol-gel P(L)ZT thin film capacitors have been studied. The results indicate that there is a strong correlation between the fatigue rate and the DRAM polarization for the fresh device. It has been found that contrary to what one might expect, the fatigue rate does not increase indefinitely with increasing stress voltage but saturates at the same voltage at which the polarization-voltage loop saturates. Though the effect of the rise time of the stress pulses on the fatigue rate is negligible, the fatigue rate is strongly dependent on the pulse width of the trapezoidal stress pulses.>