Numerical investigation of flow and particles contamination in reticle mini environment for extreme ultraviolet lithography

Particle-caused reticle defects contribute to a profound effect on the final integrated circuit (IC) yield, posing a significant technological challenge in extreme ultraviolet (EUV) lithography. This study employs the direct simulation Monte Carlo method to simulate the rarefied flow field within the EUV scanner reticle mini environment, investigating the influence of the rarefied flow field on particle behavior based on a bidirectional coupled gas-solid two-phase model. Simulation results demonstrate that the flow field induces the formation of a "particle inhibition zone" at high flow rates. Consequently, the "stopping distance" of particles released from the reticle masking blade surface remains consistently around 4 mm, and the residual rate of small particles (100 nm) is only 1.4%. The flow field control within the EUV scanner reticle mini environment can effectively mitigates the risk of particle-caused damage to the reticle surface while maintaining internal cleanliness.