A Study of the Advantages to the Photolithography Process brought by the High NA EUV Exposure Tool in Advanced Logic Design Rules

A Study of the Advantages to the Photolithography Process brought by the High NA EUV Exposure Tool in Advanced Logic Design Rules—Since the introduction of 0.33 Numerical Aperture (NA) Extreme Ultra-Violet (EUV) exposure tool to the logic 7/5 nm processes, the Moore’s law has continued its extension to smaller dimensions. However, due to the photon-absorption stochastics, the optimum pitch for the line/space is believed to be around 36~40 nm and 48~50 nm for the contact holes and vias. Below the above dimensions, either the increase of exposure energy or improvement of the material roughness or both is needed to keep the same level of defect density. The use of higher NA can improve imaging contrast, or the Exposure Latitude (EL) at smaller pitches, which may extend the lithography resolution. However, the minimum pitch that can be achieved is largely dependent on the photon-absorption stochastics. We will use our internally developed EUV stochastic model to explore the possible improvement of stochastics-resulted defectivity brought by the HiNA exposure tool and will propose the minimum pitch, Tip-to-Tip, and area reductions under the same defect density.