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Mechanism of highly selective etching of SiCN by using NF3/Ar-based plasma
Journal of Vacuum Science & Technology A ( IF 2.4 ) Pub Date : 2021-06-28 , DOI: 10.1116/6.0000711
Miyako Matsui 1 , Tatehito Usui 1 , Kenichi Kuwahara 2
Affiliation  

As part of the self-aligned processes to fabricate a 3D device, highly selective SiCN etching using NF3/Ar-based gas plasma generated by microwave electron-cyclotron resonance was investigated. The etching rate of SiCN etched by NF3/Ar plasma was higher than that of various other materials, namely, SiO2, Si3N4, poly-Si, TiN, and Al2O3. Extremely highly selective etchings of SiCN with regard to various materials are possible by forming protective layers on nonetched materials by adding gases to the NF3/Ar plasma. The effects of adding gases to the NF3/Ar plasma on various other materials were studied by analysis using optical emission spectroscopy and x-ray photoelectron spectroscopy (XPS). The three key findings of these analyses are summarized as follows. First, highly selective etching of SiCN to poly-Si was achieved by adding oxygen to the NF3/Ar etching plasma. This etching was made possible because poly-Si etching was inhibited by forming a 1.0-nm-thick oxidized layer to protect the poly-Si surface from the etching reaction with fluorine radicals. Second, highly selective etching of SiCN to SiO2 and Si3N4 was achieved by using NF3/Ar-based plasma with added SiCl4. In this etching, silicon-containing deposited layers were formed on the SiO2 and Si3N4 surfaces. The deposited layers protected the surfaces from being etched by reacting with fluorine radicals. Third, highly selective etching over TiN was achieved by using hydrogen-added plasma. The XPS results show that a thin protective layer containing TiNxFy and ammonium fluoride was formed on the TiN surface. The protective layer formed on the TiN surface effectively protects the TiN from being etched by fluorine radicals.

中文翻译:

NF3/Ar基等离子体高选择性刻蚀SiCN的机理

作为制造 3D 器件的自对准工艺的一部分,研究了使用由微波电子回旋共振产生的基于NF 3 /Ar 的气体等离子体的高选择性 SiCN 蚀刻。NF 3 /Ar等离子体蚀刻的SiCN的蚀刻速率高于其他各种材料,即SiO 2、Si 3 N 4、poly-Si、TiN和Al 2 O 3。通过向 NF 3 /Ar 等离子体中添加气体,在未蚀刻的材料上形成保护层,可以对各种材料进行高度选择性的 SiCN 蚀刻。向 NF 3添加气体的影响通过使用光学发射光谱和 X 射线光电子能谱 (XPS) 的分析,研究了各种其他材料上的 /Ar 等离子体。这些分析的三个主要发现总结如下。首先,通过向 NF 3 /Ar 蚀刻等离子体中添加氧,实现了 SiCN 到多晶硅的高选择性蚀刻。由于通过形成 1.0 nm 厚的氧化层来保护多晶硅表面免受氟自由基的蚀刻反应,从而抑制了多晶硅蚀刻,从而使该蚀刻成为可能。其次,通过使用添加了 SiCl 4 的NF 3 /Ar 基等离子体实现了对 SiCN 对 SiO 2和 Si 3 N 4 的高选择性蚀刻. 在该蚀刻中,在SiO 2和Si 3 N 4表面上形成含硅沉积层。沉积层通过与氟自由基反应来保护表面不被蚀刻。第三,通过使用加氢等离子体实现了对 TiN 的高选择性蚀刻。XPS 结果表明,在 TiN 表面形成了含有 TiN x F y和氟化铵的薄保护层。TiN表面形成的保护层有效地保护了TiN不被氟自由基腐蚀。
更新日期:2021-07-02
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