Study On Passive And High Density Resistive Random Access Memory Properties Based On HfO_x

With the integrated circuit process technology node shrinking continuously, charge based nonvolatile FLASH memory is no longer showing the advantages in high density and high operation speed. Resistive random access memory(RRAM) is considered as the candidate of next generation nonvolatile memory due to its low operation voltage, fast switching speed, high endurance, high density, good data retention and so on. Although RRAM possesses the high density integration potential, the contemporary research still suffers some challenges, such as sneak path issue in passive crossbar array, difficulties in 3D fabrication, multibit operation, etc. Additionally, Hf O2-based RRAM is the research interest in the semiconductor memory field, but high density storage is still lack in literature. According to above consideration, this dissertation is focused on the investigation of Hf Ox based passive and high density RRAM properties and multilevel resistive switching behaviors. The specific research contents are as follows.(1) W/VOx/Pt selection device and Ti/Hf Ox/Pt RRAM device were fabricated and studied separately. Afterwards, the electrical proprieties of 1S1 R configuration were systematically characterized, which is composed of the serially connected selection and RRAM devices. The results show that the sneak path current can be depressed in passive crossbar array for 4F2 cell size 1S1 R structure, improving the readout margin and array size, and making the 3D fabrication more possible.(2) The complementary resistive switching(CRS) mechanism was analyzed for Ti/Hf Ox/Pt bipolar resistive device. The simulation work was performed based on the experimental results of the bipolar resistive switching memory, including Forming process, I-V property of CRS, individual RRAM I-V properties, read operation, pulse test, and the requirement of set and reset voltage for crossbar array.(3) Cu/Hf Ox/Ti N bipolar resistive switching RRAM were fabricated and characterized, subsequently. In order to investigate the multilevel resistive switching properties, two kinds of methods were performed including adjusting the compliance current in set process and stop voltage in reset process individually. The results show that different compliance current leads to different intensity of Cu filaments in set process, and different stop voltage modulates the Schottky barrier heights in reset process.