EUVL contamination control studies for high volume manufacturing

This paper describes the research done at center for plasma material interactions (CPMI) to address the EUVL (extreme ultra- violet lithography) contamination control to achieve the HVM (high volume manufacturing) requirements in industry. Energetic atom and macro-particle emission are unavoidable when plasmas are used to generate photons in both DPP and LPP based EUV sources. These emitted particles interact first with the collection optics for the EUV radiation. Then some of the low energy sputtered collector material and some of the condensable Sn fuel exit at the intermediate focus (IF). This is undesirable. A critical requirement of stepper manufactures is to have only clean photons at the IF of EUV source-collector module. The very EUV photons that the system is designed to create can have an effect on the projection and illumination optics causing a reduction of mirror reflectivity. Even with advanced mitigation techniques, stepper optics can be damaged due to energetic and thermal neutrals. Particle contamination is problematic at the mask, and resist issues on the wafers themselves have an effect on the masks and optic elements. The efficiency of mitigation schemes is discussed. We present progress on our recent experiments on the measurement of ionic and neutral debris at Intermediate Focus (IF) in the DPP source. We also present progress on cleaning Sn deposition off of a multi-shell collector mock-up using reactive ion etching plasma, particle contamination removal from the mask blanks, and line edge roughness reduction in photoresisit.