Anionic surfactants for defect suppression in 193-nm lithography—Study of the adsorption process by ellipsometry and streaming potential measurements

In the present work we developed a strategy to reduce polymer aggregates on a polymer surface formed during the development process in 193-nm microlithography. These polymer aggregates, called “satellite spot defects” or “blob defects”, can generate serious problems with decreasing feature size leading to bridging between lines and/or blocking vias. They are caused by insoluble agglomerated resist components that adsorb on developed surfaces. By adding an anionic surfactant to the developer solution the defects could be considerably reduced. It was found that the polymer aggregate reduction in the photolithographic development process coincides with the amount of adsorbed anionic surfactant on the BARC (Bottom Anti-Reflecting Coating) surface and a more negative surface charge. The adsorption process of the anionic surfactant has been studied by null-ellipsometry and streaming potential measurements. The wettability and topography of the surfaces were characterized by contact angle measurements and scanning force microscopy.