Overlay measurement using angular scatterometer for the capability of integrated metrology.
Angular scatterometry, which has the advantage of good measurement precision, is an optical measurement technology based on the analysis of light scattered from periodic features, such as a linear grating, and is proposed as an alternative solution for overlay metrology. We present overlay measurements using an angular scatterometer and a bright-field microscope. A theoretical library based on rigorous coupled wave theory was created, and the reflected signatures measured by angular scatterometer were matched to the library to obtain structure parameters, including overlay, critical dimension (CD), and sidewall angle at the same time. The results reveal that angular scatterometer has a good precision and low tool-induced shift for overlay measurements, and has the potential for integrated metrology.
Ko
Chun-Hung
CH
Ku
Yi-Sha
YS