Influence of hydrogen in silicon nitride films on the surface reactions during hydrofluorocarbon plasma etching
Influence of hydrogen in silicon nitride films on the surface reactions during hydrofluorocarbon plasma etching
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DOI：
10.1116/1.5001034
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发表时间：
2017-11-01
影响因子：
2.9
通讯作者：
Kawamura, Takahiro
中科院分区：
文献类型：
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作者：
Kuboi, Nobuyuki;Tatsumi, Tetsuya;Kawamura, Takahiro
对于氢氟碳等离子体蚀刻，氢化氮化硅膜（SixNy:Hz）中的氢（H）含量对蚀刻性能和蚀刻机制的影响尚不清楚。因此，作者通过实验和数值模拟技术研究了SixNy:H-z薄膜中的H对CH2F2/Ar/O-2等离子体刻蚀过程中表面反应的影响。不同 H 浓度 2.6%（低 SiN）、16.8%（mod-SiN）和 21.9%（高 SiN）的 SixNy:H-z 薄膜的实验蚀刻产率 (EY) 和聚合物层厚度 (TC-F) 值随 CH2F2/(CH2F2 + O-2) 流量比显示出不同的趋势。为了了解不同蚀刻特性的机制，作者利用第一原理计算和傅里叶变换红外光谱的结果估计了 F、O、N、C 和 Si 悬键之间 H 流出的化学反应概率。基于估计的反应概率，作者假设 H 流出主要清除入射的 F 自由基（主要蚀刻剂种类），对 SixNy:H-z 薄膜的表面反应进行了建模。作者还认为，流出物中的 H 和 N 之间的反应减少了 C2N2 和 HCN 的解吸反应，导致 TC-F 值更大。将整个流量比范围内的趋势以及EY和TC-F的绝对值的模拟结果与实验数据进行比较，表面模型可以成功地解释这一机理。此外，作者利用三维体素板模型和上述表面反应，演示了鳍式场效应晶体管 SixNy:H-z 侧壁蚀刻的时间相关蚀刻轮廓和损伤分布，以获得有关 H 对蚀刻轮廓和损伤分布影响的知识。结果表明，低 SiN 和高 SiN 的 Si 鳍片结构的蚀刻轮廓和损伤分布非常不同，因为不同的 H 流出量引起不同的 EY 和 TC-F 值。这些结果表明，仔细控制刻蚀工艺和 SixNy:H-z 薄膜中 H 的含量对于实现高性能先进互补金属氧化物半导体器件非常重要。 (C) 2017 年美国真空协会。
The influence of the amount of hydrogen (H) in hydrogenated silicon nitride films (SixNy:Hz) on the etching properties and etching mechanism are unclear for hydrofluorocarbon plasma etching. Therefore, the authors have investigated the effect of H in SixNy:H-z films on the surface reactions during CH2F2/Ar/O-2 plasma etching by experimental and numerical simulation techniques. The experimental etch yield (EY) and polymer layer thickness (TC-F) values for SixNy:H-z films with different H concentrations of 2.6% (low-SiN), 16.8% (mod-SiN), and 21.9% (high-SiN) show different trends with the CH2F2/(CH2F2 + O-2) flow rate ratio. To understand the mechanism of the different etching properties, the authors estimated the chemical reaction probabilities of the H outflux between F, O, N, C, and Si dangling bonds using first principles calculations and the results of Fourier transform infrared spectroscopy. Based on the estimated reaction probabilities, the authors modeled the surface reactions of SixNy:H-z films under the assumption that the H outflux mainly scavenges incident F radicals (the main etchant species). The authors also consider that the reaction between H and N from outfluxes decreases the desorption reactions of C2N2 and HCN, resulting in a larger TC-F value. Comparing the simulation results of the trends in the whole flow rate ratio range and the absolute values of EY and TC-F with experimental data, the surface model can successfully explain the mechanism. Furthermore, the authors demonstrated time-dependent etched profile and damage distribution for fin-type field-effect transistor SixNy:H-z side-wall etching using the three-dimensional voxel-slab model with the above surface reactions to obtain knowledge about the effect of H on the etched profile and damage distribution. The results show that the etched profile and damage distribution on the Si fin structure are very different for low-SiN and high-SiN because of the different EY and TC-F values induced by different H outfluxes. These results indicate that it is important to carefully control both the etching process and amount of H in the SixNy:H-z film to achieve high-performance advanced complementary metal oxide semiconductor devices. (C) 2017 American Vacuum Society.