Plasmas containing hydrofluorocarbon gases (CHF₂CF₃, CF₃CH₃, and CHF₂CH₃) are used for the selective removal of SiN, SiO₂, and poly-Si films when manufacturing large-scale integrated circuits. Understanding the plasma chemistry of hydrofluorocarbons is important for gaining insight into the mechanisms of these selective-etching processes. The fragmental reactants produced by the reactive plasma are essential for evaluating and controlling highly accurate selective etching. This study examined such fragments using a primary dissociation ionization threshold quadrupole mass spectrometer at an electron energy of 20 eV. Their primary dissociative ionization thresholds were identified using photoelectron-photoion coincidence spectroscopy, with photon energies ranging from 10 to 28 eV. The results showed the following: (i) the CHF₂CF₃ molecule dissociated into ions such as CHF₂⁺ and C₂HF₄⁺, which formed secondary ions, such as CF₃⁺ and CF₂⁺. The F-rich reactants effectively enhanced the etching of both SiO₂ and SiN; (ii) the CF₃CH₃ molecule dissociated into ions such as C₂H₂F⁺ and C₂H₂F₂⁺, while the dominant CF₃⁺ remained as a crucial fragment for the primary etching of SiO₂; (iii) the CHF₂CH₃ molecule predominantly yielded ions such as CHF₂⁺, CF₂CH₃⁺ and C_xH_y⁺, promoting polymer film deposition on the surfaces of SiO₂ and poly-Si.

中文翻译：

---

用 CHF2CF3、CF3CH3 和 CHF2CH3 对 SiN、SiO2 和多晶硅薄膜进行氢氟乙烷等离子体蚀刻


在制造大规模集成电路时，含有氢氟烃气体（CHF₂CF₃、CF₃CH₃ 和 CHF₂CH₃）的等离子体用于选择性去除 SiN、SiO₂ 和多晶硅薄膜。了解氢氟碳化物的等离子体化学性质对于深入了解这些选择性刻蚀工艺的机制非常重要。反应性等离子体产生的碎片反应物对于评估和控制高精度选择性刻蚀至关重要。本研究使用电子能量为 20 eV 的初级解离电离阈值四极杆质谱仪检查了此类碎片。它们的主要解离电离阈值是使用光电-光离子符合光谱确定的，光子能量范围为 10 至 28 eV。结果显示如下：（i） CHF₂CF₃ 分子解离成 CHF₂⁺ 和 C₂HF₄⁺ 等离子，形成二次离子，如 CF₃⁺ 和 CF₂⁺。富 F 反应物有效地增强了 SiO₂ 和 SiN 的刻蚀;（ii） CF₃CH₃ 分子解离成离子，如 C₂H₂F⁺ 和 C₂H₂F₂⁺，而占主导地位的 CF₃⁺ 仍然是 SiO₂ 初级刻蚀的关键片段;（iii） CHF₂CH₃ 分子主要产生 CHF₂⁺、CF₂CH₃⁺ 和 C_xH_y⁺ 等离子，促进聚合物膜沉积在 SiO₂ 和多晶硅表面。