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以HBr作为刻蚀气体,采用ICP金属刻蚀系统对气体流量、刻蚀压力、离子源功率、偏压功率等工艺参数与刻蚀速率、刻蚀选择比和侧壁垂直度的对应关系进行了大量工艺实验。借助理论分析和工艺条件的优化,开发出一套可满足制备侧壁垂直度的纳米尺度多晶硅密排线结构的优化刻蚀工艺技术。实验结果表明:当采用900 W的离子源功率、11 W的偏压功率、25 cm3/min流量的HBr气体和3 mTorr(1 mTorr=0.133 3 Pa)刻蚀压力的工艺条件时,多晶硅与二氧化硅的刻蚀选择比大于100∶1;在保持离子源功率、偏压功率、气体流量不变的条件下,单纯提高反应腔工艺压力则会大幅提高上述选择比值,同时损失多晶硅和二氧化硅的刻蚀均匀性;HBr气体流量的变化在上述功率及反应腔工艺压力的工艺范围内,对多晶硅与二氧化硅的刻蚀选择比和多晶硅刻蚀的形貌特征均无显著影响。采用上述优化的刻蚀工艺条件,配合纳米电子束光刻技术成功得到多晶硅纳米尺度微结构,其最小线宽为40 nm。
Using HBr as etching gas, the relationship between gas flow rate, etching pressure, ion source power, bias power and etching process parameters such as gas flow rate, etching selectivity and sidewall perpendicularity was carried out using ICP metal etching system A large number of process experiments. With the help of theoretical analysis and optimization of process conditions, a set of optimized etching technology for nanosize polycrystalline silicon dense-line structure is developed to meet the requirement of verticality of sidewalls. The experimental results show that when 900 W ion source power, 11 W bias power, 25 cm3 / min HBr gas and 3 mTorr (1 mTorr = 0.133 3 Pa) etching pressure are used, Silicon oxide etch selectivity ratio greater than 100: 1; maintaining the ion source power, bias power, gas flow conditions, simply increasing the reaction chamber pressure will significantly increase the selectivity ratio, while loss of polysilicon and dioxide Etch uniformity of silicon; HBr gas flow rate within the process of the above-mentioned power and process pressure of the reaction chamber have no significant effect on the etching selectivity ratio of polycrystalline silicon and silicon dioxide and the morphology of polysilicon etching. Using the optimized etching process conditions, with the nano-electron beam lithography successfully obtained polysilicon nanoscale microstructures, the minimum line width of 40 nm.