Development of novel resistance random access memory (ReRAM) capacitor based on new compositions, nb-doping and combinatorial chemistry

Abstract

The recent semiconductor industry has investigated a high speed, low power consumption, high density memory devices which can retain its information without the power supply. ReRAM is one of the most attractive candidates to alternate conventional flash memory devices because of simple metal-insulator-metal structure which can guarantee the convenient fabrication and good scalability. Therefore, we focused on the development of novel capacitor for ReRAM application based on new compositions, Nb-doping and Combinatorial method. The reversible resistance switching behavior of the BaTiO3 thin film with Pt electrodes was investigated. Pt/BaTiO3/Pt device showed the typical bipolar resistance switching behavior with the narrow distribution of SET voltages. The resistance differences between HRS and LRS were clearly identified by the HRS/LRS resistance ratio and the HRS/LRS resistance ratio was over 1000 at early cycle. It was confirmed that the reversible process of creation/elimination for the conductive paths occurred during ReRAM operation. Nb-doped Ba0.7Sr0.3TiO3 thin film was synthesized by RF-magnetron sputtering and was characterized to ob-serve Nb doping effect for ReRAM properties. The reversible bipolar resistance switching behaviors were observed in both undoped Ba0.7Sr0.3TiO3 and Nb-doped Ba0.7Sr0.3TiO3 and the degree of hysteretic window change of I-V curve was reduced by Nb doping. Nb-doped Ba0.7Sr0.3TiO3 showed the excellent ReRAM prop-erties such as narrow SET voltage distribution, fast operation speed, stable endurance properties comparing with undoped Ba0.7Sr0.3TiO3. The oxygen migration induced by external electrical stress was evidently in-creased by Nb doping and it was verified by the increase of the non-lattice oxygen inside Ba0.7Sr0.3TiO3 layer by Nb doping. Resistive switching characteristics of ZnO were investigated with Al doping and the various annealing temperatures. The increasing trends for the operation voltage and the resistances o...