Modification of Diazoquinone–Novolac Photoresist Films beyond the Region of Implantation of B+ Ions

Diazoquinone–novolac photoresist FP9120 films of 1.0–2.5 μm in thickness with boron ions, implanted at an incident ion energy of 60 keV and a fluence of 5 × 1014–1 × 1016 cm−2, have been studied using attenuated total reflection (ATR) FTIR spectroscopy. It has been shown that ion implantation leads to the appearance in the layer beyond the range of ions of intense ATR bands with maxima at 2151 and 2115 cm−1 due to stretching vibrations of C=C=O cumulative double bonds formed as a result of denitrogenation of o‑naphthoquinone diazide. During implantation, a redistribution of intensities was observed between the maxima of the ATR bands due to the terminal methyl groups and methylene groups in favor of the latter. This may indicate radiation crosslinking of novolac resin molecules, involving radicals with the unpaired electron localized at the terminal methyl groups.