High-NA EUV defectivity inspection: overview and challenges

2024 will be recorded as the year where the first 0.55 High Numerical Aperture (HNA) wafer was first exposed using an Extreme Ultraviolet (EUV) scanner. In this presentation, we will dive into the initial findings from our dedicated defectivity wafers using the High NA scanner. Firstly, we will look at the printability and evolution of the programmed defects (PD) from mask to wafer through the two main patterning steps: after lithography (ADI) and after etching (AEI) into the TiN hard mask. The objective is to study the evolution of the defect surface and its progression through various sizes and shapes. Subsequently, we will discuss the potential surge of specific defect types, including microbridges, stochastic defects, and line edge roughness variations, which arise from higher resolution and tighter failure-free latitude. Additionally, the asymmetry on mask in horizontal features (with an 8x magnification in Y compared to 4x in X) might introduce different defect mechanisms. To characterize those, we use a combination of multiples tool and techniques such as optical inspection for large areas and ebeam tools for failure free latitude determination.