Water-Soluble Barrier Material for Three-Layer Resist Systems

Water-soluble films for use as intermediate barrier material in three-layer resist systems are proposed. A water-soluble film containing MoO 3 , which is formed at a high rate, is found to be suitable for use as the bottom layer etch mask because of its high resistance to O 2 RIE. By dipping the substrate in water after etching the bottom layer, the water-soluble film can be easily removed, without damaging the bottom layer or the substrate. The water-soluble film is successfully applied to a three-layer resist system for both e-beam and optical lithography.