IT04. High speed micro/nano-machining by indigenously developed ICP-FIB system

Abstract

During the last two decades, focused ion beam (FIB) technology has been used as a tool in highly demanding applications in the field of nanotechnology such as repair of photolithography masks, repair and modification of integrated circuits, TEM sample preparation, selective implantation, resist exposure etc. The technology of using FIBs for nano/micro fabrication is also called direct writing, which transfers patterns by direct impingement of ions into small spoton a substrate. Direct writing is a collection of several processes, such as milling by sputtering, implantation and ion induced deposition. These processes perform material removal, change of property and material addition. The key to the FIB direct write technology is its ability to operate a FIB with a proper beam size, current, and energy to remove or add a required amount of material with or without chemical reactions from a predefined location in a controllable manner. In this way, high precision and complex three dimensional (3D) nano/micro structures can be synthesized. Till recently, the Liquid Metal Ion Source based FIB (LMIS-FIB) system has been most popularand commercially available system. The available current from LMIS-FIB is of the order of few pA to nA and of only metallic species such as Ga, As, Ag, Au etc. These metallic ions would get implanted in the substrate being milled and change their chemical and physical properties which is undesirable. In addition, due to availability of very low current, the milling rates are only about 5 μm3/s and less. This is an excellent system to mill small volume of material in nanoscale ranges only. Due to advent of large number of MEMS devices, these days the LMIS-FIB systems are being used in synthesizing micro and macro patterns where it involves removal of volume of several million μm3 of material taking prohibitively long time.