Resistive Switching Change Memory Properties Of Nc-Si Film And Its Fabrication

With the announcement of the22nanometer chip manufacturing process from the Intel Corporation, the feature size of device is gradually reduced and the traditional memory which is based on charge storage mechanism has encountered great challenges. In this context, many new type memories have been proposed. One of the most promising candidates is the resistance switching memory. And the research of resistive switching mechanism has become a hot topic. Recently, the report on the resistive switching characteristic of SiOx film caused by "nc-Si filament" has aroused widely concern. Meanwhile, this report provided clues for us to explore the resistive switching from nc-Si film. As one of important silicon-based thin functional materials, the nc-Si film has important application prospect in silicon-based optoelectronic integration. And the research of resistive switching characteristic from nc-Si film will have a great significance to the application of new memories in future.In this thesis, the nc-Si film with nc-Si embedded in SiO2matrix was studied. The SiO film was deposited by electron beam evaporation. Then to investigate the influence of different annealing conditions to the nc-Si film structure, the microstructure was studied by HR-TEM, while the component and structure of the nc-Si film was investigated by XPS analysis. On this basis, the "top electrode/nc-Si thin film/substrate" sandwich structure samples were prepared to study the resistive switching properties of nc-Si film prepared under different conditions, and then analyze the source of resistive switching. Based on the HR-TEM of the device after several P/E operations, we proposed the "nc-Si filament pathway" model, and explain the switching mechanism of nc-Si film by the atomic bond structure. Finally, we studied the dielectric functions of the nc-Si film and proposed the core-shell structure with nc-Si as the core and SiOx as the shell, which is the basic unit for the formation of nc-Si filament pathway. This provides strong evidence to clarify the mechanism of resistive switching. The main achievements and innovation points are as follows:(1) SiO film was deposited by electron beam evaporation, and then the nc-Si film was formed by annealing methods. HR-TEM shows rapid-thermal-annealing followed by furnace-annealing could lead to nc-Si film with better uniformity of nc-Si dots. According to XPS, the RB_RM mixed model was established for SiO film and nc-Si film to clarify the SiO film structure and also the formation of the nc-Si film. At the same time, we observed the drift of Si2p XPS peaks, which was caused by "the charge storage effect" in nc-Si film.(2) The comparison of the Ⅰ-Ⅴ characteristics between SiO film and nc-Si film showed that nc-Si is the key to generate the resistive switching. After ruling out the influence of top electrode materials, we proved that the nc-Si film is the sole source of the resistive switching. By HR-TEM, we put forward the "nc-Si filament" model to explain the mechanism of resistive switching from nc-Si film. The Si, O atomic-bond-structure was set up to clarify the redox reaction of SiOx(?) Si and the "off" and "connection" of the "nc-Si filament pathway". In addition, we use the lithography process to reduce the area of the top electrode, and successfully improved the resistive switching characteristics of the device.(3) We selected the appropriate model for dielectric function according to the structure model of SiO film and nc-Si film. The relation between the dielectric function peaks and the structure of nc-Si film was studied. Based on the fact that the dielectric function peaks in our nc-Si film is different from that of the nc-Si embedded in SiOx matrix, we proposed the core-shell structure with nc-Si as the core and SiOx as the shell, which is good for the formation of the "nc-Si silicon-bridge". And we explained the relationship between the resistive switching and nc-Si core-shell structure from the nc-Si size, spacing and the thickness of the SiOx shell, which provides strong evidence to clarify the mechanism of resistive switching.