Nanofabrication Using Electron Beam Lithography: Novel Resist and Applications

Abstract

This thesis addresses nanostructure fabrication techniques based on electron beam lithography, which is the most widely employed nanofabrication techniques for R&D and for the prototyping or production of photo-mask or imprint mold. The focus is on the study of novel resist and development process, as well as pattern transfer procedure after lithography. Specifically, this thesis investigates the following topics that are related to either electron beam resists, their development, or pattern transfer process after electron beam lithography: (1) The dry thermal development (contrary to conventional solvent development) of negative electron beam resists polystyrene (PS) to achieve reasonably high contrast and resolution. (2) The solvent development for polycarbonate electron beam resist, which is more desirable than the usual hot aqueous solution of NaOH developer, to achieve a low contrast that is ideal for grayscale lithography. (3) The fabrication of metal nanostructure by electron beam lithography and dry liftoff (contrary to the conventional liftoff using a strong solvent or aqueous solution), to achieved down to ~50 nm resolution. (4) The study a novel electron beam resist poly(sodium 4-styrenesulfonate) (sodium PSS) that is water soluble and water developable, to fabricate the feature size down to ~ 40 nm. And finally, (5) The fabrication of gold nanostructure on a thin membrane, which will be used as an object for novel x-ray imaging, where we developed the fabrication process for silicon nitride membrane, electroplating of gold, and pattern transfer after electron beam lithography using single layer resist and tri-layer resist stack.