Negative-Tone Molecular Resists Based on Cationic Polymerization

摘要

There is increasing demand for higher performance resists with superior resolution, sensitivity, and line edge roughnessfor both electron beam and extreme ultraviolet lithography applications. A new class of negative tone chemicallyamplified molecular resists has been developed based on epoxide cross-linking that combines high sensitivity with lowline edge roughness and excellent resolution. Three different resists from this class have been made that all showsuperior performance compared to SU-8 in high resolution dense patterns. The functionality and size of the resistmolecules were systematically changed to investigate these effects on imaging performance under e-beam lithography.The di-functional epoxy resist, 2-Ep, had < 25 nm half-pitch resolution in dense 1:1 line-space patterns, sensitivity of 38μC/cm~2, and low 3σ LER of 2.9 nm for 30 half-pitch. The tri-functional epoxy resist, 3-Ep, showed 30 nm resolutionin dense features, 36 LER of 2.3 nm, and a sensitivity of 20 μC/cm~2. The tetra-functional epoxy resist, 4-Ep, likewiseshowed good resolution of 35 nm half-pitch in dense features, sensitivity of 22 μC/cm~2, and a low 3σ LER of 2.3 nm.This class of negative tone resist compounds are able to obtain an excellent combination of resolution, LER, andsensitivity, and show promise as high performance resists for next generation lithography.