THICKNESS MONITORING DEVICE, ETCHING DEPTH MONITORING DEVICE, AND THICKNESS MONITORING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a thickness monitoring device which can perform thickness measurement on a measurement object in real time even when a relatively narrowband light source is used.SOLUTION: An etching monitoring device (thickness monitoring device) 100 includes: a light source 1 generating a measuring beam having a predetermined wavelength width; an array detector 32 detecting interference light of the measuring beam reflected by a mask whose thickness varies with time for each wavelength; and a data processor 4 calculating a thickness of the mask on the basis of a time variation of a plurality of single-wavelength components of the interference light detected by the array detector 32.