Resistance Change Memory With The Preparation Of Nio Films And Performance Study

With the arrival of digital era, the standard of the density, operational speed and power consume of nonvolatile memory (NVM) has becoming more strict in semiconductor industry. As a typical nonvolatile memory, Flash technology is the mainstream. However, Flash memory, which is based on the floating gate structure that can trapping electrons, has the inevitable drawbacks, such as slow operational speed, low density, high operational voltage and so on. In addition, with the sustaining scaling down of semi-conductive feature size, the safety of information which stores in the Flash is decreasing gradually. Researchers have done lots of works about the next generation new NVMs in consideration of the problems of Flash memory. Currently, next generation new NVMs, including magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change random access memory (PRAM) and resistance change random access memory (RRAM), are widely studied, among which RRAM that is based on the different resistance states to store information has draw a special attention.Comparing with the other three next generation new nonvolatile memories, RRAM which is based on transition metal oxides is regarded as the most promising candidate due to its simplicity in structure, fast operational speed, good endurance and good compatibility with the traditional complementary metal oxide semiconductor technology (CMOS). In addition, RRAM technology can fulfill3-dimensional stack structures because of its low processing temperature, which is the main difficult point to increase storage density for Flash memory. However, there are still several problems, such as the exact switching mechanism, wide distribution of operational voltage etc., which need to be overcome before RRAM can be commercialized.This work focuses on the NiO thin films deposited on the Pt/Ti/SiO2/Si substrate by pulse laser deposition (PLD) at room temperature. We study the influence of oxygen partial pressure, film thickness and post-deposition anneal temperature in oxygen atmosphere on the resistance switching properties of the NiO films. We find that the as-deposition NiO films which fabricate at1Pa oxygen partial pressure and with180nm thickness have the optimal electrical properties. The results of our test show that NiO films can endure more than100series Ⅰ-Ⅴ sweep and each of the resistance state can remain10seconds at least. Pulse test shows that the operational voltages of set/reset process are1.6V/0.8V and the operational speed of set/reset process are500ns/100us, respectively. In order to investigate the conduction mechanism, we analyze the Ⅰ-Ⅴ relationships gained from our NiO thin films. We have found the multilevel resistance switching phenomenon and the linear relation between compliance current and the reset current. We establish the conductor filaments model related to the native defect states and explain the resistance switching mechanism qualitatively.