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Fabrications and Characterization of Nonvolatile Memory Devices with Zn nano Thin Film Embedded in MIS StructureChen, Chao-yu 14 June 2010 (has links)
Non-volatile memory is slower than DRAM (Dynamic Random Access Memory) but faster than HDD (Hard Disk Drive). In addition, compared to volatile memory, the non-volatile memory can retain stored information without power, and consume only low power. These characteristics show its popularity of flash memory built in portable devices. Currently the non-volatile memory applies the polysilicon and SONOS structure as floating gate, however, the new technologies of nanocrystal non-volatile memory are processed at high temperature. The manufacturing cost is rather high, so the process at lower temperature is very necessary. In this work, mixed zinc and silica amorphous layers are applied as floating gate to construct nano thin film non-volatile memory devices. The process does not need high temperature to form crystalline, and the defects in zinc oxide can be applied for charge storage. Supercritical carbon dioxide (SCCO2) treatment has been studied for the passivation of dielectric and reducing the activation energy. Using this low-temperature SCCD process ZnO nanocrystal can be formed, and the feasibility of fabricating nanocrystal NVMs device with low temperature SCCO2 is possible. The nonvolatile memory devices with Zn nano thin film embedded in MIS structure are performed. From C-V measurement, it is found that defects in SiO2 are repaired after 500¢J annealing. Because of the thermal diffusion, the storage layer SiO2/Zn-SiO2/SiO2 in device cannot be observed and the memory window disappears when the annealing temperature is higher than 700¢J. Therefore, the annealing process should be performed between 500¢J - 700¢J in making memory device. From DLTS analysis, a species with energy level of 0.6 eV is found in the as deposited Zn-SiO2 layer. After annealing in Ar, a new energy level 0.47 eV is found, and which shifts to energy level 0.85 eV after annealing in O2. In comparison to XPS results, traps of Zn-SiO2 exist before annealing, and after annealing in Ar, Zn-SiO2 transforms into Zn-O-Si. Traps of ZnO-SiO2 have been found after annealing in O2, which increases the memory effect with a 2 Volt memory window, so that more charges can be stored in the deep level traps of ZnO-SiO2 in the storage layer.
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Study of the Interface Mechanical Properties between Thin-Film Au and Poly(Methyl Methacrylate)Lin, Chia-Yuan 24 July 2007 (has links)
The existing researches on interface properties between heterology materials mainly focus on semiconductor-metal and dielectric materials, but little on organic-inorganic ones. In recent years, the nanometer scale phenomena of interfaces between organic-inorganic is gaining a lot of attentions and becoming new frontier regions of nano-related research. Since gold exhibits excellent optical, electrical and mechanical properties, which can be applied to nano-optics, mechanics and electronics. Therefore this study aims to investigate the deformation behavior of nanaoindentation using molecular dynamics simulation and nanoindentation experiments. The nano-effect of mechanical properties between the interface of gold and heterologous Polymethyl Methacrylate (PMMA) with different side groups; i.e., Isotactic-PMMA, Syndiotactic-PMMA and Atactic-PMMA, are explored, respectively. The molecular structures of those side groups of the different PMMAs are identified and characterized. Those PMMA isomer thin films are prepared using spin-coater to deposit the different side groups of PMMA upon Au thin film. Sputter technique is used to form gold thin film with different thickness. The morphology on the surface of samples is characterized by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The indenter equipment is applied to realize the interface mechanical properties. The time-dependent properties of viscoelastic materials in nanoscale are measured using continuous stiffness measurement (CSM) nanoindentation technique. The effects of displacement rates on the hardness and modulus behavior of PMMA-based are investigated by nanoindentation. The mechanical properties are correlated with the side groups of the PMMA. The hardness of the PMMA-based increases with the raising displacement rate of the Berkovich tip. On the other hand, the modulus of the variation PMMA-based with the varied displacement rate of the Berkovich tip is not significant. The nanoindentation test shows different constituents in nanocomposite systems with a stronger material properties of the interface region than the matrix in each material.
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