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An Anti‐Reflection Coating for Use with PMMA at 193 nm
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1992
Year
Optical MaterialsEngineeringElectron-beam LithographyOptical CoatingsLaser ApplicationsOrthogonal Standing WaveBeam LithographyOptical PropertiesNanolithography MethodNanophotonicsProtective CoatingMaterials EngineeringMaterials ScienceAnti‐reflection CoatingSurface TreatmentLaser-assisted DepositionAnti-reflective CoatingsDepth-graded Multilayer CoatingExcimer Laser LithographySurface ScienceApplied PhysicsProtective CoatingsSurface Processing
We have formulated an anti‐reflection coating (ARC) for use with poly(methyl methacrylate) (PMMA) resist for excimer laser lithography (193 nm). It consists of PMMA and a bis‐azide, 4,4'‐diazidodiphenyl sulfone (DDS) which crosslinks the film after deep UV (260 nm) irradiation and subsequent annealing. The reacted DDS then serves as the absorber for the 193 nm radiation and also prevents mixing of the ARC and PMMA during PMMA spin‐coating and development. We have demonstrated the effectiveness of the ARC by exposing, in PMMA, using achromatic holographic lithography, gratings of 100 nm period (∼50 nm linewidth) that are almost entirely free of an orthogonal standing wave.