UV Radiation-assisted Electron Beam Lithography with in situ Singlet Oxygen Resist Development for Patterning sub-5 nm Features

This grant supports research aimed at advancing patterning technology at the nanometer scale by augmenting the widely used technique of electron beam lithography. The central aspect of this project is to use a super-fine electron beam as a patterning tool to fabricate ultra-small structures for any application that needs exceedingly small custom features. The research aims to develop new enhancements that enable electron beam lithography to carve out structures that approach the size of individual molecules. Due to the widespread need of nanopatterning capability in many fields, academic researchers, government labs and industrial establishments all stand to benefit from this development. This new technology will be of particular benefit to the semiconductor industry where patterning device and circuit features at sub-5 nm length scale is now increasingly common. Its benefits will also be felt in many other areas of science and technology, such as photonics, bioengineering, and nanomaterials by enabling easy fabrication of very small geometric features. Because nanotechnology has assumed such strategic importance in all spheres of human activity, this research project will be instrumental in ensuring the continued scientific and technical leadership of the country well into the future. The scientific knowledge and technical expertise developed in this project will enable the manufacture of items ranging from reticles for semiconductor lithography to nanostructured surfaces in medical implants. Such objects require tailor-made nanostructures where electron beam lithography is the only viable patterning technique. This project seeks to go beyond the traditional capabilities by utilizing deep UV radiation exposure as an additional energy source during electron beam lithography. This combination allows a low current electron beam with a very small diameter to pattern a resist polymer by scissioning long polymer chains into shorter fragments. Concomitantly, an energetic form of oxygen, called singlet oxygen, will combine with and remove the polymer fragments, creating openings in the resist layer in a single step process. The use of small diameter electron beam together with in situ gas phase resist development makes it possible to fabricate structures in resist that measure only a few nanometers across. The technology only requires the addition of UV exposure and singlet oxygen generation capability to any standard scanning electron microscope. This research aims to develop these accessories, demonstrate sub-5 nm patterning for use in physics research and biomedical applications, and explore new science in polymer-electron beam interactions. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.