Fabrication of metal/ferroelectric/insulator/semiconductor field effect transistor using Mo/Pb(Zr,Ti)O3/ZrTiO4/poly Si thin film structure

In this work, metal/ferroelectric/insulator/semiconductor field effect transistors (MFISFET) using Mo/Pb(Zr,Ti)O-3 (PZT)/ZrTiO4 (ZT)/polycrystalline Si (poly-Si) thin film structures were fabricated and characterized for nonvolatile nondestructive read-out (NDRO) memory devices. The 300 nm-thick PZT films were deposited by reactive RF magnetron sputtering method on ZrTiO4 (50 nm)/Si substrates. After annealing process at 600 (square) for crystallization of PZT thin films, there was no inter-diffusion of Pb and Si. C-V hysteresis was observed in Pt/PZT/ZrTiO4/Si (MFIS) structures. For fabricating memory device, we used thin film transistor (TFT) with poly-Si thin film. The amorphous Si thin films on SiO2 substrates were crystallized by MILC (Metal Induced Lateral Crystallization) method at low temperature as 550 (square). The drain current-gate voltage (I-D-V-G) characteristics of MFISFET using the Mo/PZT/ZrTiO4/poly-Si thin film structures showed threshold hysteresis due to the ferroelectric property of the PZT thin films. The threshold hysteresis value, i.e. memory window was about 0.6 V in the applied gate voltage range of 5 V, and almost same as C-V hysteresis value in MFIS structure.