Characteristics of ArF Immersion Lithography Using Topcoat

Advances in Patterning Materials for 193 nm Immersion Lithography

“…Despite the inability of the topcoats to prevent water penetration into the resist film, they are an effective means by which to prevent PAG leaching into the immersion fluid. Typically, greater than 90% reduction in the amount of PAG leaching is observed with the use of a topcoat. ,,,,, Interestingly, topcoats are unable to reduce PAG leaching levels in direct proportion to their thickness. ,, In general, PAG leaching with a topcoat is predominantly from the topcoat surface with little PAG diffusion through the topcoat film itself. ,, Analysis of topcoat−resist film stacks reveals that PAG and other resist components can migrate into the topcoat film during casting. ,,,− For certain topcoat−resist pairs, this intermixing layer is substantial (see Figure ) . The intermixing of resist components with the topcoat is strongly dependent on the polarity of the topcoat casting solvent, with alcoholic solvents causing increased intermixing relative to less polar ethereal or hydrocarbon solvents. ,, In addition, the presence of a strong intermixing layer generally results in a region with slower dissolution rate during development, increased surface roughness after development, and T-top formation in the final resist profiles. , …”

“…115,117,122 Analysis of topcoat-resist film stacks reveals that PAG and other resist components can migrate into the topcoat film during casting. 102,112,122,[127][128][129] For certain topcoat-resist pairs, this intermixing layer is substantial (see Figure 14). 102 The intermixing of resist components with the topcoat is strongly dependent on the polarity of the topcoat casting solvent, with alcoholic solvents causing increased intermixing relative to less polar ethereal or hydrocarbon solvents.…”

“…In general, defectivity has found to decrease with increasing SRCA. 98,99,118,127,152 For example, Nikon showed that defectivity was markedly reduced with topcoats having receding water contact angles near 70°(Figure 34). 152c This transition from high to low defectivity occurs above the critical velocity for film pulling (∼50°-60°) discussed previously.…”

Synthesis and Evaluation of Adamantane-Containing Fluorinated Block Copolymers for Resist Modifers in Immersion Lithography

“…One of the most typical solutions for these problems is that top-coat, a highly hydrophobic film is coated onto the resist surface [5]. However, process cost increases because additional coating and the removal process is required.…”