Understanding the interaction of resist materials with the underlayers is important for the development of highly resolving resist materials. In this study, the effect of the surface free energy of the organic underlayer on the dissolution kinetics of poly(4-hydroxystyrene) (PHS) film in a tetramethylammonium hydroxide (TMAH) aqueous developer was investigated by the quartz crystal microbalance (QCM) method. By using 0.95 wt% TMAH standard developer, we observed the correlation between the polar component of the surface free energy of the underlayer and the interaction area of the QCM chart (impedance) near the end of PHS dissolution. The interaction area was defined by the product of impedance change and time. The interaction of the hydroxyl groups of PHS with the underlayer increased with the polar component of the surface free energy of the underlayer. The analytical method developed in this study is useful for the investigation of the resist-underlayer interaction during development.

Metal oxide nanocluster resists have recently attracted considerable attention for use in extreme ultraviolet (EUV) lithography. To obtain sophisticated guidelines for material design, it is necessary to understand well the radiation-induced chemical reaction scheme including the insolubilization mechanism. In this study, the production of CO2, which is considered to be one of the end products of treatment with an ionizing radiation, was investigated for eight types of carboxylic acid under various conditions using -rays (60Co) as a radiation source. The amount of CO2 produced was measured by gas chromatography (GC). GCO2 (/100 eV), which indicates decarboxylation efficiency, was evaluated. CO2 was generated through electron addition, hole transfer, and hydroxyl radical addition to the molecular and ionic forms of carboxylic acids. The dependences of GCO2 on reaction partners were clarified. The dependences of GCO2 on the molecular structure and dissociative state of carboxylic acids were also clarified.

Metal oxide nanocluster resists are a promising candidate for enabling the high-volume production of semiconductor devices with high-numerical-aperture (NA) extreme ultraviolet (EUV) exposure tools. In this study, the sensitization mechanism of metal oxide nanocluster resists was investigated by focusing on the radiation-induced reactions of carboxylic acid ligands. Radiolytic products in various solutions of unsaturated carboxylic acids, aromatic carboxylic acids, and saturated carboxylic acids were analyzed by electrospray ionization mass spectrometry, high-performance liquid chromatography, and dynamic light scattering. The conditions of the solutions were selected to control reaction paths of intermediates. The major reaction paths induced by an ionizing radiation were clarified. The obtained results suggest that the generation of bridging ligands is essential to the sensitization of metal oxide nanocluster resists. Both low-energy electrons and radical cations can trigger dimerization. The diffusion of small radicals should be suppressed to prevent dimerization at undesired places.

Understanding the interaction of resist materials with the underlayers is important for the development of highly resolving resist materials. The effect of the surface free energy of the organic underlayer on the dissolution kinetics of poly(4-hydroxystyrene) (PHS) film in a tetramethylammonium hydroxide (TMAH) aqueous developer was investigated by the quartz crystal microbalance (QCM) method. By using 0.95 wt% TMAH standard developer, we observed the correlation between the polar component of the surface free energy of the underlayer and the interaction area of the QCM chart (impedance) near the end of PHS dissolution. The interaction area was defined by the product of impedance change and time. The interaction of the hydroxyl groups of PHS with the underlayer increased with the polar component of the surface free energy of the underlayer. The analytical method developed in this study is useful for the investigation of the resist-underlayer interaction during development.