An overview of ion beam lithography for nanofabrication

The technology of Ion Beam Lithography (IBL)-a term often meant to include the entire range of process steps possible by harnessing the ion beams such as patterning, etching, implantation and deposition-has been under development at various institutions for about two decades. The success of optical lithography for patterns as fine as 0.75 micron and non-availability of high brightness ion sources have been responsible for the delay in the development of IBL systems. This review describes the development, limitation and applicability of different types of ion sources, viz. liquid metal ion source, gas filled ion source and duoplasmatron. Various organic and inorganic resists used in IBL and their sensitivity to protons and electrons are discussed too. Different building blocks, such as mass separators, beam blankers and deflectors, sample stage and ion optics etc. constituting serial writing systems as well as parallel writing systems have been described. The technology for the development of different types of masks for the IBL system has also been explained. Novel applications of some commercial and R and D systems used for ion beam processing and results obtained therefrom are presented. (author)