Optical Observation of Deep Bulk Damage in Amorphous Perfluorocarbon Films Produced by UV Photons Emitted from Low-Pressure Argon Plasma

In plasma processing, UV photons generate damage deep in the bulk of transparent materials such as amorphous polymers and glass. In this article, we propose the use of total internal reflection fluorescence microscopy for the nondestructive and highly sensitive detection of UV-induced deep bulk damage and for the first time demonstrate the three-dimensional profiling of UV penetration and optical damage production inside amorphous perfluorocarbon films. Weak fluorescence from damaged molecules, whose original chemical structure was altered through bond breaking and reconstruction, was detected up to several hundred nanometers below the surface after exposure to argon plasma.