A Systematic Investigation On High Density And Integration Of Ultra-large R_off/R_onRatio And High Reliability RRAM

Resistive Random Access Memory(RRAM)is regarded as the most promising candidate of the next generation nonvolatile memory.Compared to other nonvolatile memories such as MRAM,FeRAM and PRAM,RRAM consists of a simple metal-oxide-metal structure.Besides,the advantages of low cost,compatible with CMOS process technology,fast read/switching speed,low operation voltage(3 V),high density and so on,making RRAM still be respected as a popular topic in memory research.The application of RRAM in FPGA has also been considered potentially.The traditional FPGA consists of DRAM and Flash Memory,accounting for a great deal of area in a chip.In a 4*4 rFPGA structure,1SRAM1T configuration block structure totally requires 112 transistors,but only 8-16 transistors are needed if 1T1R structure is adopted,meanwhile,the faster speed and lower power will also be achieved.In particular,the high RON/ROFF ratio of RRAM obtains the larger switching state,making it easy for the external circuit to read data.In the FPGA circuit,the high RON/ROFF ratio of RRAM as a configuration block can drive more cells.However,the research and application of RRAM is now facing great challenge,such as unclear switching behavior mechanism,performance improvement,device structure design,system integration and application.In this work,we firstly demonstrate a new structure of Al2O3/HfO2/NiOx forming-free RRAM based on.switching layers engineering,that efficiently improves the resistance ROFF/RON ratio,and achieves high drive current and good reliability.Meanwhile,we also propose an analytical model fitting with the high ROFF/RON ratio RRAM,the application in FPGA and integrated circuits are also discussed.