Simultaneous Measurement of Film Thickness and Surface Profile of Film-covered Objects by Monochromatic Light Interferometry

Abstract

In semiconductor and LCD manufacturing processes, film thickness and surface profiles of film-covered objects need to be measured simultaneously. We extend phase-shifting interferometry and propose an algorithm named the SOR (Separation of Object and Reference beams) method that enables such simultaneous measurement. The SOR method can be applied not only to thick films but also to thin films, which is an advantage over existing methods. We apply the SOR method to silicon substrates covered with SiO₂ films and demonstrate its usefulness.