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 TiN_xF_y 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。