Impact of mask variations on CD and placement in resist: local versus global effects

Edge placement error (EPE) is a critical indicator for the imaging performance of semiconductor technology nodes, and is among others influenced by writing errors on the reticle. The impact of global mask variations is generally well understood and local variations are often considered to have a similar behavior. In this contribution we highlight the differences between the local and global mask variations and their impact on CD and placement in resist. We discuss the concept of local Mask Error Enhancement Factor (MEEF) and the impact of mask perturbation on neighboring structures within a certain interaction length. We show that local mask variations have a significantly smaller effect than global effects, which can have an influence on mask requirements. We show results of HyperLith simulations for a DUV use case of staggered contact holes arrays. We explore the prediction of the impact in resist of random mask fingerprints using impulse responses from single contact hole perturbation. We show that such prediction can be used to calculate the global MEEF from the local effects. The simulation results are compared to experimental data, measured in resist with CDSEM.