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.
As the critical dimension of devices is approaching the resolution limit of 193nm photo lithography, multiple patterning processes have been developed to print smaller CD and pitch. Multiple patterning and other advanced lithographic processes often require the formation of isolated features such as lines or posts by direct lithographic printing. The formation of isolated features with an acceptable process window, however, can pose a challenge as a result of poor aerial image contrast at defocus. Herein we report a novel Chemical Trimming Overcoat (CTO) as an extra step after lithography that allows us to achieve smaller feature size and better process window.
In this paper we report on our studies of the dynamic process of resist development in real time. Using High Speed – Atomic Force Microscopy (HS-AFM) in dilute developer solution, changes in morphology and nanomechanical properties of patterned resist were monitored. The Bruker Dimension FastScan AFMTM was applied to analyze 193 nm acrylic-based immersion resists in developer. HS-AFM operated in Peak Force mapping mode allowed for concurrent measurements of image topography resist stiffness, adhesion to AFM probe and deformation during development. In our studies we 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.
In this paper, we summarize our development efforts for a top-coatless 193nm immersion positive tone development (PTD) contact hole (C/H) resist with improved litho and defect performances for logic application specifically with an advance node. The ultimate performance goal was to improve the depth of focus (DoF) margin, mask error enhancement factor (MEEF), critical dimension uniformity (CDU), contact edge roughness (CER), and defect performance. Also, the through pitch CD difference was supposed to be comparable to the previous control resist. Effects of polymer and PAG properties have been evaluated for this purpose. The material properties focused in the evaluation study were polymer activation energy (Ea), polymer solubility differentiated by polymerization process types, and diffusion length (DL) and acidity (pKa) of photoacid generator (PAG). Additionally, the impact of post exposure bake (PEB) temperature was investigated for process condition optimization. As a result of this study, a new resist formulation to satisfy all litho and defect performance was developed and production yield was further improved.