Patent ID: 7009715

Claim:
A method of measuring an etch quantity of a material being processed, comprising: a) setting standard patterns (P S ) of time differential values of values relating to an interference light from a first material to be processed that respectively correspond to a plurality of predetermined etch quantities of the first material including a mask layer, the standard patterns using the wavelength as a parameter; b) measuring values relating to an interference light of multiple wavelengths from a second material being processed of same structure as the first material and determining actual patterns of differential values of the measured values relating to the interference light, the actual patterns using the wavelength as a parameter; c) determining an etch quantity of the second material based on the standard patterns of the first material and the actual patterns; and d) obtaining a time change value of the etch quantity of the second material based on the etch quantity of the second material at a first time point and the etch quantity of the second material at a second time point obtained in the c) operation.