Additive-Containing Rinses for Line Edge Roughness and Defectivity Control during High-Resolution Resist Patterning

The addition of a surface conditioning agent to the de-ionized water rinse used to quench the photoresist development process is an attractive methodology to control resist line edge roughness (LER) and defectivity levels during lithographic patterning. The use of additive-containing rinses involves the interfacial adsorption of the surface-active material (e.g. ionic surfactants, neutral polymers, polyelectrolytes) and/or its penetration into the patterned resist structure, which can be held responsible for polymer chain relaxation and reorganization within the resist matrix, resulting in reduced LER. The nonspecific adsorption process can also lead to the creation of repulsive (electrostatic or steric) forces between additive-coated surfaces, thus allowing for particulate stabilization in the rinse liquid and the minimization of printable defects. In this study, LER improvement (8 % to 16 %) induced by an organic salt and defectivity reduction (ca. ×100) created by a polyelectrolyte contained in the rinse liquid are demonstrated in advamced 193 nm resist systems. Also, additive adsorption to a 193 nm resist surface is monitored using a quartz crystal microbalance (QCM), while the repulsive force created between additive-coated surfaces is detected using atomic force microscopy (AFM) and the presence of residual additive is quantified using total x-ray reflection fluorescence (TXRF), near edge x-ray absorption fine structure (NEXAFS) spectroscopy and contact angle measurements. The experimental data provided supports the proposed mechanisms leading to LER and defectivity improvement.