A Simulation Study for Typical Design Rule Patterns and Stochastic Printing Failures in a 5 nm Logic Process with EUV Lithography

We have done a simulation study for typical 5 nm logic design rule patterns with a self-developed aerial image simulator based on the Rigorous Coupled Wave Analysis (RCWA) algorithm and the Abbe imaging routine. Generally speaking, critical structures in a lithography process are semi-dense patterns, the array edge structures, line end to line end structures, line end to perpendicular line structures (under 2D design rules), the minimum area structures, the bi-line, tri-line,. .., etc. Compared to those from the 193 nm immersion process, the behaviors for the above structures are different. For example, the minimum area of the EUV photolithographic process is found to be significantly larger than the minimum area of 193 nm immersion process. In our simulation, we have kept aware of the stochastics impact due to drastically reduced number of photons absorbed compared to the DUV process, the criteria used for various structures of image contrast are tightened. For example, in EUV lithography, the minimum Exposure Latitude (EL) for the gate layer, the metal layer, and the line end pattern have been raised to, respectively, >18%, 18%, and 13%. We have studied the stochastic printing failures of dense patterns and 2D structures, for example, line end to line end structures, line end to perpendicular line structures. Compared to 1D dense patterns, 2D structures may have lower failure probabilities with the same dimension. In contrast to dense line/space patterns, for example, the line end to line end, and the line end to perpendicular line structures have a larger area on both sides of the line ends, which is easier for developer to flow in and out so that they are relatively not easy to form bridge defects. In case of the reverse tone structures, the trench end to trench end, and the trench end to perpendicular trench structures have a large, connected under-exposed area (dark tone area) which is more robust to etch. We have also taken account of the influence of EL on LWR and Critical Dimension (CD) on stochastic printing failures. We will present the results of our work and our explanations.