Abstract Absorption of moisture by thin dielectric materials alters their properties and can cause several reliability issues. Even at standard room temperature and low humidity level, some dielectric materials are sensitive to moisture. In this study, moisture diffusion in two plasma-enhanced chemical vapor deposition (PECVD) films is investigated with three measurement methods to determine diffusion coefficients and saturated moisture concentrations: mass measurements, bending radius of curvature measurements and infrared spectroscopy. The two PECVD silicon dioxides are deposited at 200 °C and 400 °C. They were exposed to moisture in clean room environment (21 °C and 40% relative humidity) for about 800 h. The present results confirm that mass measurements, bending radius of curvature measurements and infrared spectroscopy can be used to monitor thin dielectric films in these environmental conditions. They lead to similar values for the diffusion coefficient. These values are in the range of [1.5–4.2] × 10−15 cm² s−1 for the 200 °C film and [2.3–3.6] × 10−15 cm² s−1 for the 400 °C one. Saturated moisture concentrations confirm that the two dielectrics are sensitive to moisture even at 21 °C, 40% relative humidity. Besides, the results show that standard fickean behavior does not provide the best fit to model water diffusion for some dielectric films. A dual stage model that appears to be more adapted is finally introduced.

中文翻译：

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在洁净室条件下用三种技术表征的等离子体增强化学气相沉积电介质中的水分扩散

摘要 薄介电材料吸收水分会改变其特性，并可能导致若干可靠性问题。即使在标准室温和低湿度水平下，一些介电材料对湿气也很敏感。在这项研究中，使用三种测量方法研究了两种等离子体增强化学气相沉积 (PECVD) 薄膜中的水分扩散，以确定扩散系数和饱和水分浓度：质量测量、弯曲曲率半径测量和红外光谱。两种 PECVD 二氧化硅在 200 °C 和 400 °C 下沉积。它们在洁净室环境（21°C 和 40% 相对湿度）中暴露于潮湿环境中约 800 小时。目前的结果证实，质量测量，弯曲曲率半径测量和红外光谱可用于监测这些环境条件下的介电薄膜。它们导致扩散系数的相似值。对于 200 °C 薄膜，这些值在 [1.5–4.2] × 10−15 cm² s−1 范围内，对于 400 °C 薄膜，这些值在 [2.3–3.6] × 10−15 cm² s−1 范围内。饱和水分浓度证实，即使在 21 °C、40% 的相对湿度下，两种电介质也对水分敏感。此外，结果表明，对于某些介电薄膜，标准菲克行为并不能为模拟水扩散提供最佳拟合。最后介绍了一个看起来更适应的双阶段模型。2] × 10−15 cm² s−1 对于 200 °C 薄膜和 [2.3–3.6] × 10−15 cm² s−1 对于 400 °C 薄膜。饱和水分浓度证实，即使在 21 °C、40% 的相对湿度下，两种电介质也对水分敏感。此外，结果表明，对于某些介电薄膜，标准菲克行为并不能为模拟水扩散提供最佳拟合。最后介绍了一个看起来更适应的双阶段模型。2] × 10−15 cm² s−1 对于 200 °C 薄膜和 [2.3–3.6] × 10−15 cm² s−1 对于 400 °C 薄膜。饱和水分浓度证实，即使在 21 °C、40% 的相对湿度下，两种电介质也对水分敏感。此外，结果表明，对于某些介电薄膜，标准菲克行为并不能为模拟水扩散提供最佳拟合。最后介绍了一个看起来更适应的双阶段模型。