Analysis of Ferroelectric Microcapacitors at Low and High Temperatures Using a Scanning Probe Microscope

概要

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It is widely recognized that, in ferroelectric bulk or thin films, the coercive voltage ($V_{\text{c}}$) increases at low temperatures and the remnant polarization ($P_{\text{r}}$) decreases at high temperatures. With the ongoing integration of ferroelectric random-access memory (FeRAM), the size of these capacitors has fallen to about 1.5 μm2, making it necessary to know whether such ferroelectric microcapacitors have the same nature and behave in the same manner as bulk or thin films at low and high temperatures, or if they do not behave as expected owing to so-called size effects or for some other reason. To further evaluate the impact of temperature on ferroelectrics, we have devised a new evaluation system, based on a scanning probe microscope, which can measure the electrical characteristics of a single-bit cell capacitor at temperatures between $-60$ and 120 °C. The electrical properties are measured using a sample with an IrOx/Pb(Zr,Ti)O3/Pt structure. It has been shown that both $V_{\text{c}}$ and $P_{\text{r}}$ actually increase at low temperatures in FeRAM single-bit cell capacitors.
2006-11-15