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  • 學位論文

低能量雷射熱處理改善金奈米晶粒記憶體持續時間暨主電子束微影降低鄰近效應之研究

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

指導教授 : 管傑雄

摘要


第一部分:低能量雷射熱處理改善金奈米晶粒記憶體。提出結合紫外光修復與雷射快速加熱優點的低能量複發準分子雷射,對內嵌有金奈米晶粒的二氧化矽薄膜進行熱退火,避免造成原子擴散與傷害金奈米晶粒。由傅里葉轉換紅外光譜的結果得知與水相關的雜質被移除,並且重新建構了理想的網狀二氧化矽鍵結,因此改善了氧化層品質。此內嵌金奈米晶粒的二氧化矽薄膜亦製作成金氧半電容元件加以電性分析。經低能量雷射熱處理後,電荷持續時間改善,在3×108秒後仍可保留10%的儲存電荷。為更進一步研究低能量雷射熱處理對於電荷儲存的影響,發展了利用雙機制的電荷鬆弛分析法,可分析儲存於金奈米晶粒中的電荷與儲存於氧化層陷阱中的電荷兩者不同的效應,並探討電荷持續時間與記憶窗口中兩者各自的影響。結果更加確定經由低能量雷射熱處理,可有效減少氧化層陷阱並且避免傷害內嵌的金奈米晶粒,造成原子擴散。 第二部分:主電子束降低電子束微影鄰近效應。為了降低電子束微影中的鄰近效應,提出接地金屬緩衝層基板結構。利用緩衝層減緩電子與基板重原子的碰撞,因而降低背向散射電子強度與範圍。並利用接地金屬結構幫助排除累積電荷,降低積店效應使得正向散射分布更加集中。然而由於接地金屬緩衝層基板結構製程複雜,以及金屬層與氧化層的相互影響而限制此技術的效果。因此更進一步提出利用主電子束微影,可直接濾除背向散射與正向散射的影響,因而降低鄰近效應。為了將隱藏於正向散射分布中的主電子束範圍分離,以單點曝光實驗建立顯影率模型,並可計算得到高能量主電子束範圍,再應用於決定主電子束微影參數。可在200奈米厚的電子阻劑上,得到週期100奈米線陣列的線寬17奈米,與週期5微米線陣列的線寬11奈米的高深寬比圖形。再者,此主電子束微影技術以50千至125千電子伏特的微影系統加以驗證並比較,於此間可觀測到鄰近主電子束曝光範圍的相互影響,並由五點接近實驗可得到此交互作用的特徵。

並列摘要


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.

參考文獻


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