Theoretical analyses of in-process depth measurements of fine microgrooves based on near-field optical response

Abstract

We propose a novel optical measurement method, allowing an in-process depth evaluation of microgrooves, width of which is less than the half of wavelength, with aspect ratio larger than 1, based on near-field optical phase response form the surface with a microgroove. Not only validation of the measurement principle but also a feasibility study for its practical applicability was demonstrated. The results suggest the proposed method provides nondestructive depth measurement of 100-nm-width microgroove with aspect ratio of 2 with an expanded uncertainty of less than 10% using the optical system with the wavelength of 488nm.