Advancing the ion beam thin film planarization process for the smoothing of substrate particles

For a number of technologies small substrate contaminants are undesirable, and for one technology in particular, extreme ultraviolet lithography (EUVL), they can be a very serious issue. We have demonstrated that the Ion Beam Thin Film Planarization Process, a coating process designed to planarize substrate asperities, can be extended to smooth ∼70 and ∼80 nm diameter particles on EUVL reticle substrates to a height of ∼0.5 nm, which will render them noncritical in an EUVL printing process. We demonstrate this smoothing process using controlled nanoscale substrate particles and lines fabricated with an e-beam lithography process. The above smoothing process was also modified to yield an excellent reflectance/wavelength uniformity and a good EUV reflectivity for the multilayer, which is required for EUVL reticles. XTEM on a smoothed substrate line defect shows excellent agreement with results obtained from our multilayer growth model.