Abstract: A method of determining an overlay reference wavelength, the method comprising: forming a pattern structure including a wafer and overlay keys on the wafer; obtaining first setup values of the pattern structure for first measurement wavelengths, respectively; selecting second measurement wavelengths among the first measurement wavelengths by filtering the first measurement wavelengths based on the first setup values; obtaining second setup values of the pattern structure for the second measurement wavelengths, respectively; and selecting a reference wavelength among the second measurement wavelengths based on the second setup values, wherein each of the first setup values is proportional to a deviation value of target sigma values of the overlay keys at a respective first measurement wavelength, and wherein each of the second setup values is inversely proportional to a deviation value of stack sensitivity values of the overlay keys at a respective second measurement wavelength.

Abstract: A method of optimizing an overlay measurement condition includes measuring, for each overlay measurement condition of multiple overlay measurement conditions, an overlay at multiple positions on a substrate; calculating, for each of the multiple overlay measurement conditions, key parameter indexes (KPIs) based on the measured overlay; converting, for each of the multiple overlay measurement conditions, the KPIs into key parameter function (KPF) values based on a KPF, where each of the KPFs has a same dimensional representation; integrating, for each of the multiple overlay measurement conditions, the KPF values to generate an integrated KPF value; and selecting an optimized overlay measurement condition from among the multiple overlay measurement conditions based on the integrated KPF values associated with each of the multiple overlay measurement conditions.

Abstract: Provided are a method of selecting multi-wavelengths for overlay measurement, for accurately measuring overlay, and an overlay measurement method and a semiconductor device manufacturing method using the multi-wavelengths. The method of selecting multi-wavelengths for overlay measurement includes measuring an overlay at multiple positions on a wafer at each of a plurality of wavelengths within a set first wavelength range, selecting representative wavelengths that simulate the overlay of the plurality of wavelengths, from among the plurality of wavelengths, and allocating weights to the representative wavelengths, respectively.