Charged‐Particle Lithography

Although, today, the main method for pattering almost all integrated circuits (ICs) is photolithography, charged-particle lithography – where charged particles (electrons, ions) are used for patterning – already has a wide range of applications. Electron beam lithography (EBL) is currently utilized for fabricating the photomasks essential for photolithography, as a time- and cost-effective technique for early device and technology development, and also for fabricating the imprint templates necessary for the emerging technique of nanoimprint lithography (NIL). All of these applications are enabled by single-beam writing techniques, which are undergoing continuous improvement. However, as photomask costs have increased, and continue to increase, it has become almost untenable to produce high-end ICs in low volume. Hence, today the use of field-programmable gate arrays (FPGAs) has surpassed that of the faster and more highly integrated application-specific integrated circuits (ASICs). Consequently, promising new multiple-beam writing techniques are currently under development, known as maskless lithography (ML2), for the volume production of ICs. Ion beam lithography (IBL) represents an alternative approach for the fabrication of imprint templates for NIL, with the advantage of not requiring resist processing. Currently, both EBL and IBL are the only viable methods for fabricating nano-electromechanical systems and nanotechnology devices, and therefore are essential tools for the emerging nanotechnology. Keywords: electron beam lithography; chemically amplified resist (CAR); photomask fabrication; direct-write; maskless lithography (ML2); nanoimprint template fabrication; ion beam lithography; direct-structuring