Apparatus and methods employing phase control and analysis of evanescent illumination for imaging and metrology of subwavelength lateral surface topography

摘要

Imaging and metrology devices employ controlled phase shifting and analysis of evanescent light to provide enhanced ability to image and/or resolve substantially subwavelength lateral features on a surface illuminated by the evanescent light. The light waves comprising the evanescent electromagnetic field are inhomogeneous in that their planes of equal phase are substantially perpendicular to the direction of propagation and to their planes of constant amplitude. The planes of equal phase are therefore normal to the surface to which the evanescent field is adjacent and to a sample surface illuminated by this field as well. By controlling the phase of the source of illumination and analyzing the output from the surface, either by phase analysis or phase to amplitude decoding, subwavelength lateral surface topography resolution is enhanced without sacrificing vertical resolution. Methods and means for dynamic or static phase shifting of inhomogeneous waves comprising the evanescent field are disclosed, as well as other non- imaging applications.