Laboratoire de Physique de la Matière Condensée, Ecole Polytechnique, CNRS, Université Paris-Saclay , 91128 Palaiseau, France.
Saint-Gobain Recherche , 39 quai Lucien Lefranc, 93303 Aubervilliers, France.
ACS Appl Mater Interfaces. 2017 Jan 25;9(3):3075-3084. doi: 10.1021/acsami.6b12880. Epub 2017 Jan 11.
Silicon nitride is used for many technological applications, but a quantitative knowledge of its surface chemistry is still lacking. Native oxynitride at the surface is generally removed using fluorinated etchants, but the chemical composition of surfaces still needs to be determined. In this work, the thinning (etching efficiency) of the layers after treatments in HF and NHF solutions has been followed by using spectroscopic ellipsometry. A quantitative estimation of the chemical bonds found on the surface is obtained by a combination of infrared absorption spectroscopy in ATR mode, X-ray photoelectron spectroscopy, and colorimetry. Si-F bonds are the majority species present at the surface after silicon nitride etching; some Si-OH and a few Si-NH bonds are also present. No Si-H bonds are present, an unfavorable feature for surface functionalization in view of the interest of such mildly reactive groups for achieving stable covalent grafting. Mechanisms are described to support the experimental results, and two methods are proposed for generating surface SiH species: enriching the material in silicon, or submitting the etched surface to a H plasma treatment.
氮化硅被用于许多技术应用，但对其表面化学的定量了解仍然缺乏。通常使用含氟蚀刻剂去除表面的本征氮氧化物，但仍需要确定表面的化学组成。在这项工作中，使用光谱椭圆光度法跟踪 HF 和 NHF 溶液处理后层的减薄（蚀刻效率）。通过 ATR 模式红外吸收光谱、X 射线光电子能谱和比色法的组合，获得了表面存在化学键的定量估计。在氮化硅蚀刻后，表面存在的主要物种是 Si-F 键；也存在一些 Si-OH 和少量 Si-NH 键。不存在 Si-H 键，这对于表面功能化来说是不利的，因为这种低反应性基团对于实现稳定的共价接枝很有意义。描述了支持实验结果的机制，并提出了两种生成表面 SiH 物种的方法：在材料中富集硅，或对蚀刻表面进行 H 等离子体处理。
