High-speed atomic force microscopy studies of 193-nm immersion photoresists during tetramethylammonium hydroxide development

This paper reports on our studies of the dynamic process of positive tone photoresist development in real time. Using high-speed atomic force microscopy (HS-AFM) in dilute alkaline developer solution, changes in morphology and nanomechanical properties of patterned resist were monitored. The Bruker Dimension FastScan AFM was used to analyze 193-nm acrylic-based immersion resists in tetramethylammonium hydroxide developer solution. HS-AFM operated in PeakForce Tapping® (Registered Trademark of Bruker, Inc.) mode can allow for concurrent measurements of resist topography, stiffness, adhesion, and deformation during development. These studies focused on HS-AFM topography data as it readily revealed detailed information about initial resist morphology, followed by a resist swelling process, and eventual dissolution of the exposed resist areas. HS-AFM showed potential for tracking and understanding development of patterned resist films and can be useful in evaluating the dissolution properties of different resist designs. Also discussed are the roles of AFM tip shape and resist feature geometry on the measured line edge roughness using a simulation procedure.