Low-temperature PZT thin-film ferroelectric memories fabricated on SiO2/Si and glass substrates

In a ferroelectric-gate thin film transistor memory (FGT) type structure, the gate-insulator layer is extremely important for inducing the charge when accumulating or depleting. We concentrated on the application of low-temperature PZT films crystallized at 450, 500 and 550 °C, instead of at conventional high temperatures (≥600 °C). Investigation of the crystalline structure and electrical properties indicated that the PZT film, crystallized at 500 °C, was suitable for FGT fabrication because of a high (111) orientation, large remnant polarization of 38 μC/cm2 on SiO2/Si substrate and 17.8 μC/cm2 on glass, and low leakage current of 10−6 A/cm2. In sequence, we successfully fabricated FGT with all processes below 500 °C on a glass substrate, whose operation exhibits a memory window of 4 V, ON/OFF current ratio of 105, field-effect mobility of 0.092 cm2 V−1 s−1, and retention time of 1 h.