Mask critical dimension error on optical lithography

Optical lithography at resolution limit is a non-linear pattern transfer. One of the important issue is a mask critical dimension control because of nonlinear amplification of mask critical dimension error during image transferring on wafer. This amplification of mask error is called the MEF. This mask error factor has been widely used as an important parameter for indicating tighter CD control for the photomask for low-kl lithography generation.