Highly selective etching for polysilicon and etch-induced damage to gate oxide with halogen-bearing electron-cyclotron-resonance plasma
Highly selective etching for polysilicon and etch-induced damage to gate oxide with halogen-bearing electron-cyclotron-resonance plasma
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DOI：
10.1063/1.363164
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发表时间：
1996-09-01
影响因子：
3.2
通讯作者：
Lin, HC
中科院分区：
文献类型：
--
作者：
Chang, KM;Yeh, TH;Lin, HC
本文研究了在电子回旋共振反应器中用三种含卤素等离子体（SF_6、Cl~-_2和HBr）刻蚀多晶硅的情况。通过对F、Cl和Br自由基的化学和电学性质的讨论，研究了刻蚀速率、各向异性和选择性等刻蚀特性。发现各向异性的程度强烈地依赖于侧壁上的卤化硅膜的沉积和三种卤素等离子体混合物的自发刻蚀特性。对氧化物的选择性与蚀刻多晶硅期间产生的卤化硅的量以及这些产物吸附在氧化物表面上时的电极化水平有关。我们发现，对氧化物的选择性是近似无限的HBr系统和Cl-2系统超过90。此外，还研究了氧气添加、微波功率和射频功率的影响。结果发现，SF6，Cl-2，和HBr等离子体的最大蚀刻速率和选择性发生在添加的氧气浓度在约7.5%，5%，和3%的总流量，分别。微波功率的适宜范围为250~300 CV，射频功率的适宜值为35 W。同时，研究了腐蚀过程中引起栅氧化层损伤的局部表面充电。观察到器件的低成品率、大的平带电压V-fb漂移和高的界面态密度D-it与器件的较长的双折射和高天线比结构相关。在SF_6气体体系中，其降解效果比在Cl-_2和HBr气体体系中更为明显。最后，还讨论了电磁线圈电流对器件损伤的影响。(C)1996年美国物理学会。
The investigations of polysilicon etching with three halogen-bearing plasmas (SF6, Cl-2, and HBr) in an electron-cyclotron-resonance reactor have been made. We examine the etching characteristics which include etching rate, anisotropy, and selectivity based on the discussions of the chemical and electrical properties of the F, Cl, and Br radicals, It was found that the degree of anisotropy strongly depends on the deposition of a silicon halide film on sidewall and on the spontaneous etching properties of three halogen plasma mixtures. The selectivity to oxide is related to the amount of silicon halides that are produced during etching poly-Si and the electrically polarized level of these products when they adsorb on the oxide surface. We find that the selectivity on oxide is approximately infinite for the HBr system and over 90 for the Cl-2 system. In addition, the effects of oxygen addition, microwave power, and rf power are also investigated. It was found that the maximum etching rate and selectivity of SF6, Cl-2, and HBr plasmas occurred at concentrations of added oxygen at about 7.5%, 5%, and 3% total flow rates, respectively. The suitable range for the microwave power applied is from 250 to 300 CV and the most respectable value of applied rf power is about 35 W. Concurrently, the local surface charging causing damage to the gate oxide during the overetching period is studied. It is observed that low device yield, large flatband voltage V-fb shift, and high interface-state density D-it are correlated with longer overetch and high antenna ratio structure of the device. A more obvious degradation is observed in the SF6 gaseous system than in Cl-2 and HBr ones. Finally, the influence of magnetic coil current on device damage is also addressed. (C) 1996 American Institute of Physics.