State space model and numerical simulation of overlay error for multilayer overlay lithography processes

Considering multiple error sources that affect overlay deviation in multilayer overlay lithography processes, according to the error source is applied to exposure field or wafer, the deviation sources can be divided into two aspects: intrafield error and interfiled error. And based on the concept of virtual location point, these error forms can be expressed uniformly. Then, the state space model of overlay deviation for multilayer overlay lithography processes are established based on stream of variation. The propagation characteristics of multilayer overlay deviation is analyzed by applying state space model, and compared with the result from Monte Carlo simulation to the physical overlay deviation model with completely parameter set, the relative error between two methods is less than 2%, so the feasibility of the proposed method is verified.