Fabrication of MFIS diodes using BLT (Bi,La)/sub 4/Ti/sub 3/O/sub 12/ and LaAlO/sub 3/ buffer layers

We fabricated MFIS (metal-ferroelectric-insulator-semiconductor) diodes with Bi/sub 3.35/La/sub 0.75/Ti/sub 3/O/sub 12/ (BLT) films and lanthanum aluminate (LaAlO/sub 3/) buffer layers formed on Si(100) substrates. LaAlO/sub 3/ films were prepared by an MBE (molecular beam epitaxy) method. After the film deposition, they were subjected to ex site N/sub 2/ annealing in a rapid thermal annealing (RTA) furnace at 800/spl deg/C for 1 min. BLT films (150 nm) were deposited on these LaAlO/sub 3//Si structures using a sol-gel technique. The memory window of this BLT film annealed in O/sub 2/ ambient at 750/spl deg/C for 10 min was about 2.7 V. It was found that the leakage current density was on the order of 10/sup -6/ A/cm/sup 2/ at an electric field of 500 kV/cm. It was also found from the retention measurement that the capacitance values biased at a voltage in the hysteresis loop did not change for more than 3 hours.