Atomic force microscopy (AFM) based nanopatterning and nanocharacterization

Chapter Introduction 1.1 Nanofabrication for miniaturized devices Nanotechnology is vital for the continued miniaturization of components such as integrated circuits, memory devices, display units, biochips and biosensors. The advancement of nanotechnology involves the control of matter and fabrication of meaningful structures at the nanometer scale. One of the key processes in nanofabrication is the construction of functional units in the size regime less than 100 nm. Top-down and bottom-up approaches have been used to generate nanostructures. The former involves the application of various lithographical techniques to create nanoscale patterns starting from a featureless bulk material, while the latter uses the interactions of molecules and colloidal particles to assemble two- and three-dimensional structures. The conventional techniques for nanofabrication are based on various lithographical methods in the topdown approach, including photolithography,[1,2] electron beam lithography[3,4] and focused ion beam lithography.[5,6] However, the applicability of these techniques is often limited by their high capital and operating cost, multiple-step processes, and poor accessibility. In recent years, novel methods such as nano-imprint lithography (NIL),[7-9] soft lithography,[10-11] and atomic force microscopy (AFM) nanolithography[12,13] have emerged as flexible alternatives for nanoscale patterning and fabrication. These novel methods have the potential to be future low-cost techniques for nanoscale pattern formation and replication. Among these newer techniques, AFM nanolithography has shown itself to be a unique tool for materials structuring and patterning with nanometer precision. In this technique, the probe can be used to: (i) transfer chemicals to a surface; (ii) induce localized reactions by applying a bias on the tip; (iii) mechanically scratch a surface; and (iv) manipulate molecules, nanotubes via pushing, sliding and rotating. The working principle of AFM nanolithography is based on the interaction between the probe and substrate. The typical radius of curvature of the probe is 20–60 nm, and the probe–substrate separation in close contact condition is [...]... and G Dietler, Surf Sci Rep 34, 1 (1999) 31 Chapter 2 Experimental 2.1 Atomic Force Microscopy The nanopatterning and nanocharacterization work in this thesis is mainly performed using a NanoMan AFM system (Nanoscope IV, Veeco Instruments and Process Metrology) The NanoMan (a software and hardware configuration) system allows us to perform high-resolution imaging, high-definition nanolithography, and. .. meniscus -based and bulk solution -based operations We show the formation of acidic thin layers by microscale droplet and AFM probe scanning, and the unique features of Si nanostructuring by performing AFM patterning in thin layers 20 1.4 Strategies and approaches of this work Based on the objectives and motivations explained in 1.3, we further describe various approaches that we use for our patterning and. .. hardness, Hamaker constant, adhesion and surface charge densities.[191] In chapter 7, we study the force curve to further understand the tip-surface interaction, particularly the probe-induced adhesive forces in liquid layers for nanocluster collection and assembly Force curves were collected during the approach and withdrawal of the tip from the liquid layer The force measurements provide vital information... 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These novel methods. state between local meniscus -based and bulk solution -based operations. We show the formation of acidic thin layers by microscale droplet and AFM probe scanning, and the unique features of Si. 20–60 nm, and the probe–substrate separation in close contact condition is <1 nm. When suitable forces are exerted, and/ or external fields applied, the probe can induce various physical and chemical