Studies of Low-Energy Laser Annealing to Improve the Retention of Au Nanocrystal Memory & Primary Beam Exposure to Reduce the Proximity Effect in eBeam Lithography
Date Issued
2015
Date
2015
Author(s)
Shen, Kuan-Yuan
Abstract
First Part: Study of Low Energy Laser Annealing to Improve Au Nanocrystal Memory. The low-energy multipulse excimer laser annealing (LEM-ELA) is proposed to anneal the nanostructure of Au nanocrystal (NC) embedded in SiO2 thin film without causing atomic diffusion and damaging the NCs, since the LEM-ELA combining the advantages of laser annealing and UV curing features rapid heating and increasing oxide network connectivity. A Fourier transform infrared spectroscopy (FTIR) characterization of SiO2 thin films annealed using LEM-ELA indicated that the quality was improved through the removal of water-related impurities and the reconstruction of the network Si–O–Si bonds. Then, LEM-ELA was applied to SiO2 thin film embedded with Au NCs, which were fabricated as MOS capacitors. The charge retention was greatly improved and the percentage of retained charges was about 10% after 3×108 s. To investigate and differentiate the effects of LEM-ELA on charges stored in both oxide traps and in the Au NCs, a double-mechanism charge relaxation analysis was performed. The results indicated that the oxide traps were removed and the confinement ability of Au NCs was enhanced. The separated memory windows contributed from the charges in Au NCs and those in oxide traps were obtained and further confirmed that the LEM-ELA removed oxide traps without damaging the Au NCs. Second Part: Study of Primary Beam to Reduce Proximity Effect in electron Beam Lithography. The Grounded (GND) Metal-Buffer Substrate is proposed to reduce the proximity effect in electron beam lithography. The buffer layer is to reduce the collision of incident electrons with substrate atoms to suppress the effect of backscattered electron (BSE). The GND metal structure is to help relax accumulated charges to sharpen the forward scattering electron (FSE). Since the buffer-layer induced charging and complicated fabrication process limit the performance of GND Metal-Buffer Substrate method, the Primary Beam Exposure method is further investigated and studied. The high-energy primary beam is applied to ebeam lithography and the influences from BSE and FSE are filtered out. The model to calibrate the primary beam region is developed. The linewidth is 17 nm for a 100 nm-period line array pattern and is 11 nm for a 5 μm-period one on a near 200 nm-thick ZEP520A ebeam resist.
Subjects
Laser Annealing
Nanocrystal Memory
MOS Capacitor
Electron Beam Lithography
Primary Beam Electron
Proximity Effect
Development Rate
Type
thesis
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