Preparation And Characterization Of Nitride Based Resistive Switching Random Access Memory (RRAM) Materials

Modern integrated circuits (ICs) technologies have been developed innovatively and quickly in the past few decades since the advent of Moore’s Law in the late 20th century. And under the requirements and encouragements of the Moore Law, ICs of Ultra Large Scale Integration (ULSI) have been manufactured and improved in one generation after another. Thus, new problems and research issues such as interconnect technologies, critical dimension of transistors, developments in integration of ICs, have been aroused and revealed to coordinate the developments of industry.As far as we all know, data storage technologies is one of the most important and critical parts of the ULSI industry. As the quick increase of the integration of ICs, more and more issues in this field have become obvious and need to be solved. As a result, innovative concepts, structures and materials for data storage technologies have sprouted in front of the public smoothly in the past 10 years. Currently it comes to be more critical to require the memory cells achieve higher storage density, less destroyable voltage operation processes, less power consumption, longer signal keeping duration and electrical endurance. Compared with other concepts, resistive switching memory gains more and more concentration and attention from the IC industry for its simple structure, outstanding electrical properties.Up till now, Oxygen based binary semiconducting materials have a longer history in the study in resistive random access memory (RRAM), however, the study and application in RRAM field of Nitrogen based binary materials have been rarely published. The mechanism and practical properties are still unclear for research and need further study.This essay, which focuses on the preparation and characterization including physical and electrical ones of binary metal nitride films applied into the RRAM structure, contains four parts as followed:1. Copper nitride (CuxN) films were prepared by both conventional DC reactive magnetron sputtering (RMS) and plasma immersion ion implantation (PⅢ) methods. Structural and chemistry binding differences have been observed and analyzed by X-ray diffraction (XRD) and X-ray photoelectron spectrum (XPS). Electrical properties have also been tested for both films, and the influences of preparation methods on the bipolar resistive switching properties of the CuxN films have been discussed.2. Annealing process and oxygen plasma surface treatment were employed for the CuxN film prepared by PⅢ method. Characterization methods mentioned above have also been utilized to observe the films in order to gain the systematically parametric study of the film such as topography, chemistry states and chemical constituents. Electrical properties such as operation voltage, high/low resistive states, cycling endurance have also been carried out. Effects of different annealing temperature and oxygen plasma treatment parameters on voltage distribution and electrical states have been discussed. Also, thermal treatments have been applied onto the CuxN:O films to test the reliability of the RRAM cells.3. Pulse laser deposition (PLD) technology has been employed to synthesis aluminum nitride (AlN) films. Different preparation parameters such as fabrication duration, working gas pressure and substrate temperature have been used to cause the physical changing of the formation of AlN films. The film physical properties have been carried out by scanning electron microscopy (SEM), XRD and atomic force microscopy (AFM) methods. All characterization mentioned above for the AlN films aim to enable the films optimized for the RRAM applications.4. AlN films prepared by PLD method are applied into metal/AlN/metal structure RRAM cell. Different top electrodes (Mo, Ni, Pt) have been deposited on the film, several resistive switching mechanisms observed in the AlN based RRAM cells have been discussed. Meanwhile, general electrical properties of AlN based RRAM cells have been characterized for the future prospective and industrial utility. Besides, special failure I-V curve has been observed in Ni/AIN/Al RRAM cell, its mechanism has been discussed for a better understanding of resistive switching properties in normal Ni/AlN/Al RRAM cells...