The Study Of Resistive Switching Charateristics And ⁶⁰Co?-rays Total Ionizing Dose Effects In HfO₂/Al₂O₃ Bilayer Suructure Devices

The new non-volatile memory meets the performance requirements of next-generation high-density information storage and high-performance computing for general-purpose electronic memory.The new non-volatile memory has the potential to become the next-generation general-purpose memory,The new non-volatile memory mainly includes phase-change random access memory?PRAM?,ferroelectric RAM?FRAM?,magnetic RAM?MRAM?,and resistive RAM?RRAM?.Among them,the RRAM has obvious advantages over other new non-volatile memories,such as memory cell area,energy consumption,number of erasing,cycle rererention,fatigue resistance and data retention time.Among the resistive materials,the first ones studied are binary oxides,most of which exhibit good resistive properties such as TiO_x,HfO_x,AlO_x,TaO_x,ZrO_x,etc.Among them,the HfO_x exhibits stable bipolar switching characteristics,large switching window?>100?,high erasability?>10⁵?,long rerention time at high temperature.and the Al O_y has small Reset current.Research shows,The resistance change mechanism of oxide-based RRAM is generally a conductive filament mechanism.The gamma ray radiation in RRAM does not change the high and low resistance states of its memory cells after a certain dose,which proves that RRAM has strong radiation resistance and has the potential to be used in space.However,the limits of the radiation resistance threshold of RRAM are different in different materials and different structures,and the damage mechanism of the device after high-dose gamma-ray radiation has not been clearly explained.In this paper,the HfO2 and the Al2O3 thin films were selected as the research objects.The atomic layer deposition?ALD?method were used to prepare HfO_x and Al O_y films device.The change law of the resistive properties of the device after 60Co?-ray radiation and the damage mechanism of the device after high-dose irradiation were explored.We Test the device of the semiconductor properties and resistive properties.The main works are as follows:?1?The Pt/HfO2/Ti N and Pt/Al2O3/TiN resistive structure devices were prepared by sol-gel method and ALD method,Both devices exhibited stable bipolar resistive behavior.Among them,the surface of Pt/HfO₂/TiN and Pt/Al₂O₃/TiN devices prepared by ALD were flat.The electrical properties of Pt/HfO2/TiN structure devices show good resistance uniformity,but the resistant to cycling is not good and the device can not maintain the resistive performance for a long time;The resistive characteristics of the Pt/Al₂O₃/TiN structure device have small Reset current that have the potential to achieve low power consumption.?2?The Pt/HfO2/Al2O3/TiN resistive bilayer structure devices were prepared by ALD method,in which the Al₂O₃ acted as a buffer layer,and different thicknesses of HfO₂ film were grown on the same buffer layer.The device exhibits more stable resistance characteristics,better cycle performance,low operating voltage,better retention performance?>104 s?,and good fatigue resistance?>107?.The resistance change mechanism of Pt/HfO2/Al2O3/Ti N double-layer structure device is the oxygen vacancy conductive filament mechanism.?3?The Total ionizing dose of ⁶⁰Co?-ray on the Pt/HfO₂/Al₂O₃/TiN double-layer structure device were investigated.After different TID up to 100 krad?Si?and 200 krad?Si?,the high and low resistance of the device didn't change much,the operating voltage slightly increases,these results show that the Pt/HfO2/Al2O3/TiN double-layer structure device have a good immunity to ionizing radiation.After the TID of 1 Mrad?Si?,the high and low resistance of the Pt/HfO2/Al2O3/Ti N double-layer structure device obvious reduced,the operating voltage significantly increases,the cycles performance and the stablely maintain were reduced.After high TID of 1 Mrad?Si?,the defect of the oxide were increases,the oxygen vacancies of the device were increasing,the conductive filaments of the device were easier to form.