Etching of Thermal SiO2 in Supercritical CO2
Etching of Thermal SiO2 in Supercritical CO2
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超临界 CO2 中 SiO2 的热蚀刻
DOI：
10.1149/1.2779364
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
P. Granger
中科院分区：
文献类型：
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作者：
S. Malhouitre;J. V. Hoeymissen;C. Case;P. Granger
超临界 CO2 (SCCO2) 处理已被提议用于多种 IC 制造应用，例如低 k 修复、蚀刻后残留物去除、光刻胶剥离或金属沉积 [1]。 SCCO2 具有优异的特性（液体密度、低粘度和可忽略的表面张力），使 SCCO2 成为多个 FEOL 和 BEOL 加工步骤的良好候选者。氢氟酸水溶液广泛应用于半导体加工（蚀刻、聚合物去除、表面处理……）。 SCCO2 中的无水 HF 可用作替代蚀刻工艺，例如蚀刻工艺。用于 MEMS 或 DRAM 制造中的牺牲 SiO2 蚀刻，从而避免图案塌陷问题。特别是，SCCO2/HF/吡啶蚀刻可以为 SiO2 提供对高 k 电介质等其他材料的良好蚀刻选择性。 SCCO2 中的低 HF 浓度也可用于 BEOL 蚀刻后残留物去除 (PERR) [2]。然而，HF/吡啶络合物在 SCCO2 中蚀刻 SiO2 时发生的化学反应机制基本上是未知的。本文对 SCCO2 中使用 HF/吡啶进行热 SiO2 刻蚀进行了详细研究。报告了各种处理参数（处理温度、SCCO2 中的 HF 浓度、蚀刻时间等）对蚀刻速率的影响。还研究了使用 SCCO2/HF/吡啶化学进行 SiO2 蚀刻的化学反应、蚀刻机制和反应产物的形成。
Supercritical CO2 (SCCO2) processing has been proposed for several IC manufacturing applications like low-k repair, post etch residue removal, photo resist stripping or metal deposition [1]. SCCO2 presents excellent properties (liquid-like density, low viscosity and negligible surface tension) that make SCCO2 a good candidate for several FEOL and BEOL processing steps. Aqueous HF is widely used in semiconductor processing (etching, polymer removal, surface preparation ...). Anhydrous HF in SCCO2 can be used as an alternative etching process, e.g. for sacrificial SiO2 etching for MEMS or DRAM manufacturing, thus avoiding pattern collapse issues. In particular, SCCO2/HF/pyridine etching can offer good etch selectivity of SiO2 towards other materials like high-k dielectrics. Low HF concentration in SCCO2 can also be used for BEOL post etch residue removal (PERR) [2]. However, the chemical reaction mechanisms occurring during the etching of SiO2 with HF/pyridine complex in SCCO2 are basically unknown. In this paper, the etching of thermal SiO2 using HF/pyridine in SCCO2 has been studied in detail. The impact of various processing parameters (processing temperature, HF concentration in SCCO2, etching time, ...) on the etch rate is reported. The chemical reactions, etching mechanisms and reaction product formation involved in SiO2 etching using SCCO2/HF/pyridine chemistry are also investigated.