Vacuum ultra violet absorption spectroscopy of 193 nm photoresists

193 nm photoresists which are methacrylate-based polymers are very sensitive to vacuum ultra violet (VUV) light (100 nm<λ<200 nm) generated by plasmas used for pattern transfer technologies. Upon plasma treatment the physical properties of the polymers can be deeply modified. To better understand the chemical changes involved, the absorption coefficient of a commercial 193 nm photoresist has been measured in the 120–280 nm wavelength range using a home built experimental set-up. The different contributions to the absorption were identified by also measuring the spectra of model polymers and simpler polymer chains. This knowledge was then used to identify the chemical changes in the photoresist upon heating up to 240°C.