Radiation-Induced Processes in Electron-Irradiated Films of Negative Phenol-Formaldehyde Photoresist on Silicon

Abstract

It was found that radiation-induced processes in films of negative photoresist NFR 016D at doses up to 2 × 1015 cm–2 occur mainly with the participation of residual solvent molecules or on by-products of the photoresist film synthesis. After irradiation, absorption bands with maxima at 1717 (stretching vibrations of C=O bonds), 1068, and 1009 cm–1 (vibrations of C–O–C bond in methyl-3-methoxypropylate solvent) disap pear in the attenuated total internal reflection spectra of the photoresist. At irradiation doses above 1 × 1016 cm–2, significant changes in the intensity of the bands associated with the main component of the photoresist (phe nol-formaldehyde resin) were observed. A noticeable transformation of the spectrum occurs in the region of 1550–1700 cm–1, in which stretching vibrations of C=O bonds are observed. At irradiation doses above 2 × 1016 cm–2, the intensities of the bands caused by stretching vibrations of CH2 and CH groups decrease (bands with maxima at 2925 and 3012 cm–1, respectively). The experimental results indicate a change in the compo sition of substituents at the carbon ring and the formation of conjugated double C=O bonds when the pho toresistive film is irradiated with electron doses above 2 × 1016 cm–2.