Nanometer-scale patterning and individual current-controlled lithography using multiple scanning probes (original) (raw)
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The Journal of Physical Chemistry, 1996
Here we provide evidence that the principal mechanism responsible for scanning tunneling microscope (STM)induced removal (or deposition) of material from organic thin films in air is electrochemical in nature. In experiments conducted in high-humidity (>∼70% relative humidity) ambients, patterning proceeds at biases above ∼+2.3 V because a thin layer of water adsorbed to the tip and surface establishes an ultra-thin-layer electrochemical cell. The low-energy self-assembled monolayer (SAM) restricts the dimensions of the highly resistive solution in the tip-sample gap and confines the patterning to the immediate vicinity of the tip, passivates unetched regions of the Au(111) substrate, and retards the surface mobility of Au atoms thereby stabilizing the patterns. In the absence of SAMs, patterns in nominally naked Au(111) are irreproducible and rapidly anneal to their pre-etch form. In low-humidity (<∼25% relative humidity) ambients there is insufficient water on the SAM surface to support Faradaic electrochemistry and insignificant patterning is observed at sample biases up to +5.0 V. We observed a bias threshold for patterning that is dependent on the composition of the tip-sample gap, but found that the bias threshold is essentially independent of the tunneling current. Using this scanning tunneling microscope-induced electrochemical patterning, we are able to reproducibly and selectively deposit or remove material from the surface to yield features having critical dimensions of less than 10 nm.
Probe-Based Nanolithography: Self-Amplified Depolymerization Media for Dry Lithography
Macromolecules, 2010
Patterning of resists at the submicrometer scale and the corresponding transfer of patterns onto various underlying substrates is a widespread, versatile method for device production and became the driving technology for micro-and nanofabrication. However, optical lithography is approaching its scaling limits and potential successors are few. 1 One of them, nanoimprint lithography, 2 requires to-scale fabrication of masters and hence does not solve the fundamental lithographic problem. Currently the foremost technology at hand to produce such masters is high-resolution electron beam lithography.
Materials for lithography in the nanoscale
International Journal of Nanotechnology, 2009
Design and development of photoresists aiming at patterning in the nanoscale is reported. Functionalised polycarbocycle-based molecules and Polyhedral Oligomeric Silsesquioxane (POSS) containing (meth)acrylate copolymers are the basic components of the resist materials proposed for 193 nm and EUV lithography. The synthesis of new functionalised polycarbocycles aimed first at the development of etch resistance additives for 193 nm (meth) acrylate resists, since these compounds are characterised by moderate absorbance at 193 nm and by increased etch resistance due to the polyaromatic and cycloaliphatic rings they contain. Recently, additional functionalisation with appropriate imaging and hydrophilic groups advanced compounds of this class to become suitable main components of molecular resist compositions. On the other hand the incorporation of POSS groups in (meth)acrylate copolymers was studied first towards the development of 157 nm double layer resists, and recently, after the renewal of the semiconductor industry interest for 193 nm technology for double layer 193 nm resists. Characterisation methodologies for sub 100 nm thick resist films were also developed based on interferometry and used for the optimisation of the resist materials developed.
Journal of Micromechanics and Microengineering, 2017
The development of new photoresist materials for multi-lithography applications is crucial but a challenging task for semiconductor industries. During the last few decades, given the need for new resists to meet the requirements of semiconductor industries, several research groups have developed different resist materials for specific lithography applications. In this context, we have successfully synthesized a new molecular non-chemically amplified resist (n-CAR) (C3) based on the functionalization of aromatic hydroxyl core (4,4′-(9H-fluorene-9,9-diyl)diphenol) with radiation sensitive sulfonium triflates for various lithography applications. While, micron scale features have been developed using i-line (365 nm) and DUVL (254 nm) exposure tools, electron beam studies on C3 thin films enabled us to pattern 20 nm line features with L/3S (line/space) characteristics on the silicon substrate. The sensitivity and contrast were calculated from the contrast curve analysis as 280 µC cm −2 and 0.025 respectively. Being an important parameter for any newly developed resists, the line edge roughness (LER) of 30 nm (L/5S) features were calculated, using SUMMIT metrology package, to be 3.66 ± 0.3 nm and found to be within the acceptable range. AFM analysis further confirmed 20 nm line width with smooth pattern wall. No deformation of patterned features was observed during AFM analysis which indicated good adhesion property between patterned resists and silicon substrates.
Spm Based Lithography for Nanometer Scale Electrodes Fabrication
MRS Proceedings, 1999
Scanning probe assisted nanolithography is a very attractive technique in terms of low-cost, patterning resolution and positioning accuracy. Our approach makes use of a commercial atomic force microscope and silicon probes to build simple nanostructures, such as metal electrode pairs, for application in novel quantum devices.Sub-100 nm patterning was successfully performed using three different techniques: direct material removal, scanning probe assisted mask patterning and local oxidation.
Sensors & Transducers, 2009
Ultrahigh nanolithography resolution of 31 nm was achieved using thin film layers of naphthoquinones compounds. Dry nanolithography processes, negative and positive were developed, utilizing the thermal and optical properties of these compounds, by using an Atomic Force Microscope with a tapered optical tip. Negative nanolithography was achieved using a specially designed optical fiber tip transmitting 488 nm of light that functions as a near field optical source. Positive nanolithography was achieved by coating the fiber tip with a metal film to serve as a nano-heating source. Sub-wavelength gratings with a variable line width, fabricated using these processes, are demonstrated.
Electrostatic nanolithography in polymers using atomic force microscopy
Nature Materials, 2003
T he past decade has witnessed an explosion of techniques used to pattern polymers on the nano (1-100 nm) and submicrometre (100-1,000 nm) scale, driven by the extensive versatility of polymers for diverse applications, such as molecular electronics 1,2 , data storage 3 , optoelectronics 4 , displays 5 , sacrificial templates 6,7 and all forms of sensors. Conceptually, most of the patterning techniques, including microcontact printing (soft lithography) 8 , photolithography 9,10 , electron-beam lithography 11 , block-copolymer templating 12,13 and dip-pen lithography 14 , are based on the spatially selective removal or formation/deposition of polymer. Here, we demonstrate an alternative and novel lithography techniqueelectrostatic nanolithography using atomic force microscopy-that generates features by mass transport of polymer within an initially uniform, planar film without chemical crosslinking, substantial polymer degradation or ablation. The combination of localized softening of attolitres (10 2 -10 5 nm 3 ) of polymer by Joule heating, extremely non-uniform electric field gradients to polarize and manipulate the soften polymer, and single-step process methodology using conventional atomic force microscopy (AFM) equipment, establishes a new paradigm for polymer nanolithography, allowing rapid (of the order of milliseconds) creation of raised (or depressed) features without external heating of a polymer film or AFM tip-film contact.