Research on Factors Affecting Resolution in Extreme Ultraviolet Interference Lithography Based on Modulation Transfer Function

[Background]: Extreme ultraviolet interference lithography (EUV-IL) is widely used in the evaluation of the lithographic performance of extreme ultraviolet photoresists and plays an important role in their development. [Purpose]: Achieving high-resolution EUV-IL still faces numerous challenges and limitations, and the development of optical simulation methods capable of quantitatively analyzing the factors affecting lithographic resolution will be a key approach to solving these problems. [Methods]: This study developed a MOI simulation model based on statistical optics to assess the impact of various factors (grating fabrication deviations <1 nm, photon noise at 75 mW/cm², and vibration conditions ranging from 1.5-10 nm RMS) on the MTF of the EUV-IL system. [Results]: The EUV-IL system at SSRF was optimized achieving interference pattern exposure with a resolution of 12.5 nanometers. The mechanical vibration was controlled within 2.5 nm (RMS), and the MTF analysis showed that photon noise reduced the contrast to 0.75 at a power density of 75 mW/cm². [Conclusions]: Experimental results also verify the rationality of the MTF analysis.