THE ELECTRICAL PROPERTIES AND RETENTION CHARACTERISTICS OF STRAINED PZT THIN FILM CAPACITORS

摘要

We have investigated the effect of externally controlled hi-axial stress on the electrical properties and retention characteristics of Pb(Zr_(0.52),Ti_(0.48))O_3 (PZT) thin films. The PZT thin films exhibited a low residual tensile stress, i.e. 120 MPa. Under external compressive stress, the switching polarization or remanent polarization increased with the compressive stress. Coercive field also increased with the compressive stress. Upon applying a biaxial stress of 240 MPa, the switching polarization increased to 40 mu C/cm~2 while the PZT films with the residual tensile stress had 31 mu C/cm~2. On the other hand, PZT thin films under the tensile stress exhibited slightly decreasing switching polarization and the coercive field with increasing the tensile stress. Retention test revealed that both the external bi-axial stressed and unstressed PZT thin films showed the same polarization decay behavior (15 percent loss) within 1 second, whereas the mechanically stressed PZT thin films showed more suppressed polarization decay than unstressed one for a long period of retention time.