Experimental and Computational Analyses of the Oxidation Mechanism of the Poly(arylsilane) Family as the Side Reaction during the Baking Process

• Published in: Journal of physical chemistry. C Vol. 124; no. 29; pp. 16149 - 16158
• Main Authors: Kobayashi, Osamu, Noda, Kunihiro, Ikuma, Naohiko, Shiota, Dai, Ishimoto, Takayoshi, Tachikawa, Masanori
• Format: Journal Article
• Language: English
• Published: American Chemical Society 23.07.2020
• Subjects: C: Physical Processes in Nanomaterials and Nanostructures
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.0c02416

Polysilanes are important materials for photoresist masks used in semiconductor chipmaking processes. As the oxidation of a polyalkylsilane can lead to the failure of the chipmaking process, it is important that the oxidation reaction mechanism is understood to suppress undesired reactions. In this paper, the oxidation mechanism of polysilanes is elucidated both experimentally and computationally. X-ray photoelectron spectroscopy was used to show that polysilanes with phenyl groups tend to become more oxidized than those with methyl groups. Furthermore, thermal desorption spectroscopy also revealed that the phenyl groups are lost from the polysilanes. Our computational study revealed that the oxidation mechanism proceeds by dearylation initiated by the addition of 3O2 to the phenyl or methyl group and the oxidation of the polysilane backbone by phenylperoxyl radicals that depart from the backbone, which was found to involve a two-step reaction involving the cleavage of the O–O bond of the phenylperoxyl radical followed by the formation of the Si–O–Si structure. Therefore, the mechanism for the oxidation of the polysilane involves the phenyl group.