Non-traditional resist designs using molecular resists: positive tone cross-linked and non-chemically amplified molecular resists

Two different types of non-traditional molecular resists were synthesized and characterized. A positive-tone cross-linked molecular resist was made that functions by first forming an etch resistant film via thermal cross-linking of vinyl ether functionalized small molecules followed by patterning of the film via acid catalyzed cleavage of the resulting acetal bonds. DPA-2VE, a single multi-functional molecular resist of this type, showed DUV sensitivity of 7 mJ/cm2 and a contrast of 5.2 for development in either organic solvent or aqueous base. Using high resolution patterning with a 100 keV e-beam, it was possible to demonstrate feature resolutions down to 40 nm. When 0.26N TMAH was used as a developer, the dose-to-size was 84 μC/cm2 with a 3σ LER of 14.2 nm. Using MIBK as a developer, the dose-to-size was 104 μC/cm2 and the 3σ LER was 7.4 nm. A series of non-chemically amplified molecular resists based on using 2- nitrobenzyl ethers as photosensitive protecting groups were also made. One formulation showed a DUV sensitivity of 1 mJ/cm2, while another formulation which showed the best contrast of 8.3 obtained at a sensitivity of 10 mJ/cm2. However, under 100 keV e-beam patterning, the 2-nitrobenzyl ether protected materials showed little to no response even up to 3000 μC/cm2.