Studies on leaching of photoresist components by water

Immersion lithography has drawn tons of interests as a potential solution for sub-65nm patterning. High refractive index liquid, which is filled in the gap between exposure lens and a photoresist, can improve a resolution through increased effective numerical aperture (NA) of the exposure system. Most attractive liquid for this purpose is water. Our works were conducted as a part of the basic study for immersion lithography and aimed for the verification of leached resist components by water. It was observed that leaching relies largely on the free volume of a polymer and anion size of photoacid generator (PAG). The larger free volume and the smaller anion, the larger T-top resist profile was generated. Additionally, effects of solvents, quenchers and polarity of the polymer were investigated. Detailed results will be reported in this paper.