Detection and localization of subsurface defects in DLC films by acoustic microscopy

A high frequency scanning acoustic microscopy (SAM) operating at 1-1.3 GHz was used to investigate subsurface defects in diamond-like carbon (DLC) films that were 2-3 µm thick. Because the wavelength of the longitudinal wave in the film was comparable to the film thickness, the acoustical images obtained were near-field images. to inerpret the features in the acoustical images, a multidisciplinary approach was utilized through the combination of SAM with atomic force microscopy (AFM), focused ion beam (FIB) technique, surface Brillouin spectroscopy (SBS), and optical microscopy.