Patterning of self-assembled pentacene nanolayers by extreme ultraviolet-induced three-dimensional polymerization

Most researchers expect extreme ultraviolet lithography (EUVL) to be used to create patterns below 32 nm in semiconductor devices. An ultrathin EUV photoresist (PR) layer a few nanometers thick is required to further reduce the minimum feature size. Here, we show for the first time that pentacene molecular layers can be employed as a new EUV resist. Nanometer-scale dots and lines have been successfully realized using the new molecular resist. We clearly show the mechanism that forms the nanopatterns using a scanning photoemission microscope, EUV interference lithography, an atomic force microscope, and photoemission spectroscopy. The molecular PR has several advantages over traditional polymer EUV PRs. For example, it has high thermal/chemical stability, negligible outgassing, the ability to control the height and width on the nanometer scale, fewer residuals, no need for a chemical development process and thus a reduction of chemical waste when making nanopatterns. Besides, it can be applied to any substrate to which pentacene bonds chemically, such as SiO₂, SiN, and SiON, which are important films in the semiconductor device industry.