Fundamental understanding of the interplay between target and sensor brings diffraction based overlay to the next level of accuracy

In this contribution we will dive into the fundamentals of diffraction based overlay, where we explore the physics of the signal formation in diffraction based overlay in the presence of asymmetric target deformation. We will show that a better understanding of the signal formation helps to develop methods that advance diffraction based overlay metrology to the next level of accuracy, which is needed to fulfill the increasing demand for a better on-product overlay control.