Development of Microwave-Excited Plasma-Enhanced Metal-Organic Chemical Vapor Deposition System for Forming Ferroelectric Sr_2(Ta_(1-x),Nb_x)_2O_7 Thin Film on Amorphous SiO_2

摘要

Sr_2(Ta_(1-x),Nb_x)_2O_7 (STN; x = 0.3) is suitable for use as ferroelectric gate field-effect transistors (FETs) for one-transistor-type ferroelectric memory devices, because it has a low dielectric constant. For applications using metal-ferroelectric-insulator-semiconductor (MFIS) FETs, crystallization of ferroelectric film on insulator is necessary. Perovskite STN can be successfully obtained on amorphous SiO_2 by ferroelectric-multilayer-stack (FMLS) deposition, which uses alternating steps of STN sputtering deposition and oxygen radical treatment. In this study, we report on a newly developed microwave-excited plasma- enhanced metal-organic chemical vapor deposition (MOCVD) system, in which STN can be deposited in radical oxygen atmosphere. We succeeded in the fabrication of STN on amorphous SiO_2 in a single process. The IrO_2/STN (200 nm)/SiO_2 (10 nm)/p-type Si device shows capacitance-voltage (C-V) hysteresis curves and a memory window of 1.2 V with a 5 V writing operation.