| AVS 63rd International Symposium & Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS-WeA |
| Session: | Atomic Layer Etching and Low Damage Processing |
| Presenter: | Ahmed Soliman, Kyoto University, Japan |
| Authors: | A.I.A. Soliman, Kyoto University, Japan T. Utsunomiya, Kyoto University, Japan T. Ichii, Kyoto University, Japan H. Sugimura, Kyoto University, Japan |
| Correspondent: | Click to Email |
Vacuum ultraviolet (VUV) light of 172 nm is widely used for modifying the surfaces of polymers and self-assembled monolayers (SAMs) to be applicable in microfluidics, lithography and microelectromechanical systems (MEMS) devices. The influences of VUV light on the surface modifications are dependent on the irradiation environment. In an atmospheric environment, the VUV light generates active oxygen species (O), which can functionalize and etch the organics at the irradiated surface.1 While in high vacuum condition (HV), the rate of oxidation process at the VUV-irradiated surface decreased,2 and other photochemical reactions, such as photo-cleavage can proceed apparently.
In this work, we examined the influence of HV-VUV treatment on the surface oxygenated groups of SAMs. We used VUV/(O)-modified hexadecyl (HD-) SAMs in this study, because of their highly-dense and well-defined structure. Furthermore, these modified-SAMs were homogenously terminated with different oxygenated groups.1 These modified-SAMs were HV-VUV irradiated for different periods. The changes of the chemical constituents after HV-VUV treatment were characterized by X-ray photoelectron spectroscopy (XPS) and chemical derivatization using different fluorinated reagents.
After VUV/(O) treatment, the XPS results showed that the oxygenated groups at the surface of SAM contained both derivatizable (such as OH, CHO and COOH) and nonderivatizable (C-O-C, C-CO-C and C-COO-C) groups.1 The HV-VUV affected the surface components; the decrease of COO and C-O moieties, while the slight increase of C=O moieties. The C-C components were slightly influenced by the HV-VUV irradiation. Considering the changes of the chemical constituents, wettability and morphology, the routes and mechanisms of the chemical conversions at the HV-VUV irradiated surface were discussed.
We concluded that the HV-VUV treatment to the surface oxygenated groups could only dissociate the components containing C-O bonds without significant influence on the C-C skeleton. The HV-VUV can be considered as a selective-trimming modification technique with less degradation, as the components containing C-O bonds were only dissociated.
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