The First 0.5 NA Projection Optic for Extreme Ultraviolet Lithography (EUVL) Microfield Exposure Tool ('MET5')

摘要

Multilayer mirror effects - Film stress: 1. Stress in the EUV ML coating will change the shape of the mirrors at the sub-nanometer level: - Magnitude of bending is predicted based on samples and FEA; - Verification of the model is performed on a set of test mirrors. 2. Also the EUV ML coating stress relaxes after deposition: - Stress also varies from run-to-run. 3. The effect of the stress on POB WFE is evaluated: - Stress level at 40 days chosen as baseline condition; - Stress relaxation system effect evaluated at 250 and 615 days. (1) Stress data exists for 250 day case; (2) 615 day case based on linear extrapolation of relaxation curve. - Considered a worst case; relaxation curve is expected to approach an asymptote rather than continue linearly.