AlN_xO_y Film Prepared By Atomic Layer Deposition And Its Resistive Switching Property

With the development of semiconductor technology,the nonvolatile Flash memory is confronted by lots of challenges such as gate leakage and cell cross-talk as its size continuously scaled down.On the other hand,Resistive random access memory(RRAM)is expected to be next-generation nonvolatile memory,due to its low operation voltages,fast read-write speed,high memory density,and its compatibility with CMOS technologies.In this thesis,aluminum oxide(Al2O3)and aluminum oxynitride(AlNxOy)thin films were deposited by atomic layer deposition(ALD).The optimum process conditions of AlNxOy thin film growth its resistance switching property are investigated.Nano-silver layer was inserted into the AlNxOy layer to improve the RRAM performance.Mechanism of the resistive switching of the AlNxOy is provided.Main results of the thesis are summarized as followed:1.AlNxOy thin film was prepared by ALD at various temperatures of 200?,300 ?,and 400?.With higher process temperature,the oxygen content in the film gradually reduces,and the nitrogen content increases due to the enhanced activity of the plasma ammonia precursor.The AlNxOy thin film deposited at 300? show s the best property wih the growth rate of 0.098 nm/cycle and the density of 3.1g/cm3.The Pt/AlNxOy(15nm)/Si capacitor structure was tested to give a dielectric constant of 9.1 for the AlNxOy film.2.Al2O3thin film was prepared by ALD at various temperatures of 200?,250?,300?,and 350?.The growth rate was determined between 0.09 nm/cycle and 0.10 nm/cycle.The smooth surface roughnesses of the A1203thin films are all less than 1 nm.3.The resistive switching property of the AlNxOy film was investigated with various conditions.When using Ag as top-electrode,a 20 nm thick AlNxOy film grown at the temperature of 300? showed excellent characteristics.Device yield reached 100%and all devices showed forming-free property.The resistance ratio between high resistance state(HRS)and low resistance state(LRS)was greater than 103.The Set voltages varied between 0.3V and 0.8V and the Reset voltages varied between-0.2V and-1.1V.In order to further improve the performance of the device,a nano-silver thin layer was inserted into the middle of the AlNxOy thin film.The IV endurance test were repeated for 300 cycles without any deterioration.The resistance ratio between HRS and LRS was enhanced to 104.The distribution of the Set voltages and the Set voltage was also improved.Low temperature electrical measurement of the LRS resistance showed a positive resistance-temperature coefficient which indicated metallic filament nature.The resistive switching mechanism of the Ag-electroded AlNxOy RRAM is ascribed to the formation and rupture of the Ag conductive filaments.