Novel materials design for immersion lithography

The technology of 193nm immersion lithography has been progressing rapidly toward half-pitch 45 nm generation device manufacturing. However, some intrinsic issues, the photoacid leaching and the watermark defect have remained in the immersion process. Most of approaches to overcome them were the introduction of cover coating materials (top coat) onto the resist film. Recently, we have established the non-top coat resist using novel two kinds of materials, a low leaching PAG (PhotoAcid Generator) and a surface modifier. The hydrophobic photoacid generated from the low leaching PAG decomposes by heating, and the acid migration changes to reduce the line-width roughness (LWR). The surface modifier behaves as builded-topcoat by the distribution around resist surface and enhances the surface hydrophobicity. Herein we propose the concept of novel PAG and surface modifier for immersion lithography.