IR-Fourier Spectroscopy of Attenuated Total Internal Reflection of Polyimide Films on Single-Crystal Silicon Wafers

Attenuated total internal reflection (ATR) spectra of polyimide PI-2610 films deposited on single-crystal silicon wafers by centrifugation were studied after irradiation with 5-MeV electrons in a linear accelerator at doses of 1∙10¹⁴–2∙10¹⁵ cm^–2. The strongest bands in the spectrum of the PI-2610 polyimide films were attributed to vibrations of the imide ring C–N–C_st (1349 cm^–1) and aromatic ring (1517 cm^–1), stretching vibrations of the imide ring C=O_str (1700 cm^–1) and CO–C_st-group C–C bonds (1074 cm^-1), and bending vibrations of C–H bonds with maxima at 734 and 828 cm^–1. The spectral shape and intensities of bands with maxima at 1700 and 1349 cm^–1 due to C=O and C=N–C_str vibrations were observed to change at an initial dose of 1∙10¹⁴ cm^–2. It was assumed that this was due to relaxation of metastable states of these groups. The intensities of bands corresponding to asymmetric and symmetric stretching vibrations of C–H₂ bonds decreased at a dose of 2∙10¹⁵ cm^–2. The intensities of ATR bands due to vibrations of C=O and C–N bonds and aromatic and imide rings practically did not change.