Pattern printability for off-axis incident light in EUV lithography

Off-axis incident light produces shadowing and an imbalance in the diffracted light. Shadowing causes a change in the critical dimension (CD) and a shift in the position of patterns due to the swing + bulk effect of the absorber and buffer layers. In addition, the imbalance in the diffracted light influences the optical proximity-effect correction (OPC) of actual patterns with a k1 below 0.6. In this study, the main factors influencing OPC were investigated. These include asymmetric aberrations and optical proximity effects (OPE) in line patterns. OPC was then applied to a T-shaped pattern. It is found that the mask error factor (MEF) in low-contrast regions of a layout is an important consideration in OPC.