As critical dimensions shrink, line edge and width roughness (LER and LWR) become of increasing concern. Traditionally LER is viewed as a resist-limited effect; however, as critical dimensions shrink and LER requirements become proportionally more stringent, system-level effects begin to play an important role. Recent advanced EUV resist testing results have demonstrated lower bounds on achievable LER at the level of approximately 2 to 3 nm. Here we use modeling to demonstrate that a significant portion of this low bound may in fact be do to system-level effects and in particular the mask. Of concern are both LER on the mask as well as roughness of the multilayer reflector. Modeling also shows roughness (flare) in the projection optics not to be of concern.
Microfield exposure tools (METs) continue to play a dominant role in the development of extreme ultraviolet resists. One of these tools is the 0.3 numerical aperture SEMATECH Berkeley MET operating as a resist and mask test center. Here the authors present an update on this tool, summarizing the latest test and characterization results. They provide an update on the long-term aberration stability of the tool and present line-space imaging in chemically amplified photoresist down to the 20nm half-pitch level. Although resist development has shown substantial progress in the area of resolution, line edge roughness (LER) remains a significant concern. In this manuscript the authors further present a summary of recent LER performance results and consider the effect of mask contributors to the LER observed from the SEMATECH Berkeley MET.
The influence of partial fluorination on the lithographic performance of photoresists based on (meth)acrylate terpolymers containing polyhedral oligomeric silsesquioxane (POSS) pendant groups is investigated in bilayer schemes for 193 nm lithography. For the first time the capability of POSS-functionalized resists for standard lithographic processing, including use of standard developer (0.26 N tetramethylammonium hydroxide) and industrial processing equipment is demonstrated. The optimized resists formulated exhibited high sensitivity (<10 mJ/cm 2 ) and potential for resolution performance comparable to mature 193 nm materials. The role of the fluorinated acid as a component in the terpolymer composition was crucial to the homogeneity of the resist material and its lithographic performance. Also, a photoacid generator (PAG) study revealed that the use of a highly hydrophobic PAG containing organic anion with a long fluorinated chain in the resist formulation improved further the homogeneity of the material and its lithographic performance. The adhesion of the highly fluorinated materials to the substrate is influenced by the type of polymeric underlayer used, whereas best results were obtained on a hard baked novolac polymer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.