Scanning Probe Lithography Technique Research Articles

Формирование наноструктур из поликристаллических пленок диоксида ванадия с помощью сканирующей зондовой литографии

Vanadium dioxide (VO2) undergoes a reversible first-order metal-insulator phase transition near room temperature, accompanied by a structural phase transition. This causes a significant change in its electrical and optical properties, making it useful for practical applications. VO2-based nanostructures exhibit notable mechanical resistance to structural transition caused by their small size and demonstrate vivid properties during the phase transition. Obtaining VO2 nanostructures is an extremely demanded objective. This research study presents the use of scanning probe lithography techniques to fabricate nanostructures on polycrystalline VO2 films. The present study focuses on the modification of VO2 films when a positive bias is applied to the sample. The effect of the value and duration of the applied voltage, relative humidity on the quality of the formed nanolithographic pattern was analyzed. The oxidation mechanism was determined. It was found that as a result of local anodic oxidation the formed oxide structures consisting of vanadium penta-oxide (V2O5) completely dissolve in water. This process leads to the separation of the continuous polycrystalline VO2 film into individual nanostructures with precise dimensions. The presented method of forming nanostructures from crystalline VO2 films is promising for nanophotonics and nanoelectronics.

Nanolayer Laser Absorber for Femtoliter Chemistry in Polymer Reactors.

Laser-induced forward transfer (LIFT) has the potential to be an alternative approach to atomic force microscopy based scanning probe lithography techniques, which have limitations in high-speed and large-scale patterning. However, traditional donor slides limit the resolution and chemical flexibility of LIFT. Here, a hematite nanolayer absorber for donor slides to achieve high-resolution transfers down to sub-femtoliters is proposed. Being wettable by both aqueous and organic solvents, this new donor significantly increases the chemical scope for the LIFT process. For parallel amino acid coupling reactions, the patterning resolution can now be increased more than five times (>111000 spotscm- 2 for hematite donor vs 20000 spotscm- 2 for standard polyimide donor) with even faster scanning (2vs 6ms per spot). Due to the increased chemical flexibility, other types of reactions inside ultrasmall polymer reactors: copper (I) catalyzed click chemistry and laser-driven oxidation of a tetrahydroisoquinoline derivative, suggesting the potential of LIFT for both deposition of chemicals, and laser-driven photochemical synthesis in femtoliters within milliseconds can be explored. Since the hematite shows no damage after typical laser transfer, donors can be regenerated by heat treatment. These findings will transform the LIFT process into an automatable, precise, and highly efficient technology for high-throughput femtoliter chemistry.

Dip‐Pen Nanolithography Enabled Functional Nanomaterials and Their Applications

AbstractDip‐pen nanolithography (DPN) is a scanning probe lithography technique that can write “inks” directly on a surface with high resolution. The “pen” was initially started from an atomic force microscopy (AFM) tip and later developed to a polydimethylsiloxane (PDMS) tip array to allow for high‐throughput nanofabrication. Over the past two decades, DPN has enabled a wide range of applications from printing arrays of small molecules to fabricating complicated hybrid structures and even integrated systems. In this review, the uses of DPN are focused upon for the synthesis of nanomaterials (NMs) divided by different postprocessing steps after the patterning. The applications of the obtained NMs are also summarized.

Writing Behavior of Phospholipids in Polymer Pen Lithography (PPL) for Bioactive Micropatterns.

Lipid-based membranes play crucial roles in regulating the interface between cells and their external environment, the communication within cells, and cellular sensing. To study these important processes, various lipid-based artificial membrane models have been developed in recent years and, indeed, large-area arrays of supported lipid bilayers suit the needs of many of these studies remarkably well. Here, the direct-write scanning probe lithography technique called polymer pen lithography (PPL) was used as a tool for the creation of lipid micropatterns over large areas via polymer-stamp-mediated transfer of lipid-containing inks onto glass substrates. In order to better understand and control the lipid transfer in PPL, we conducted a systematic study of the influence of dwell time (i.e., duration of contact between tip and sample), humidity, and printing pressure on the outcome of PPL with phospholipids and discuss results in comparison to the more often studied dip-pen nanolithography with phospholipids. This is the first systematic study in phospholipid printing with PPL. Biocompatibility of the obtained substrates with up to two different ink compositions was demonstrated. The patterns are suitable to serve as a platform for mast cell activation experiments.

Alternative Strategy Based on Scanning Probe Lithography for Patterning Complex Metallic Nanostrutures on Rigid or Flexible Substrates

AbstractAn efficient methodology based on scanning probe lithography technique to design complex metallic nanostructures on rigid or flexible substrates is reported. This maskless method is based on an atomic force microscopy nanoindentation technique for engraving predetermined patterns on a polymer film and creating inverted patterns on the metal surface. The present work then demonstrates that this methodology opens up new possibilities of applications for which an individual control of the height, shape, and periodicity of each printed nano(micro)structure is necessary. The possibilities of the presented method are defined in terms of resolution, height, and shape of the metallic nanostructures and speed of writing. The ability to reproduce 3D arrangement of gold nanostructures allows to create nanostructured substrates for surface‐enhanced Raman scattering (SERS) applications. The potential of the substrate for biosensing and the effect in particular of the periodicity of the nanostructures are explored by the SERS measurement after immersion of the substrate in a solution of 10−6m thiophenol.

"Multipoint Force Feedback" Leveling of Massively Parallel Tip Arrays in Scanning Probe Lithography.

Nanoscale patterning with massively parallel 2D array tips is of significant interest in scanning probe lithography. A challenging task for tip-based large area nanolithography is maintaining parallel tip arrays at the same contact point with a sample substrate in order to pattern a uniform array. Here, polymer pen lithography is demonstrated with a novel leveling method to account for the magnitude and direction of the total applied force of tip arrays by a multipoint force sensing structure integrated into the tip holder. This high-precision approach results in a 0.001° slope of feature edge length variation over 1 cm wide tip arrays. The position sensitive leveling operates in a fully automated manner and is applicable to recently developed scanning probe lithography techniques of various kinds which can enable "desktop nanofabrication."

Line Patterning using a Scanning Probe Lithography Technique based on Convolution Method#

In this article, we report the development of a fabrication process for predictable line patterns. The proposed process uses two control parameters: the tip speed and step size, with the convolution method. From the oxidation curves, we choose the two oxidation parameters: bias voltage and oxidation time. Given a desired line pattern, these oxidation parameters are then used for calculating the control parameters. The step size is determined by the width of the nanodot profile, and the tip speed is calculated using the step size and the oxidation time. As the overlapping of exposure area happens because of the nanodots located densely, the electrochemical reaction is continuously activated during the line lithography process in the overlapped area so that the amount of overlap can be estimated with the convolution method. From experimental results with a commercial atomic force microscope, we verified that our method is effective in fabricating nanoline patterns.

Direct patterning of nanoparticles and biomolecules by liquid nanodispensing.

We report on the localized deposition of nanoparticles and proteins, nano-objects commonly used in many nanodevices, by the liquid nanodispensing (NADIS) technique which consists in depositing droplets of a solution through a nanochannel drilled at the apex of an AFM tip. We demonstrate that the size of spots can be adjusted from microns down to sub-50 nm by tuning the channel diameter, independently of the chemical nature of the solute. In the case of nanoparticles, we demonstrated the ultimate limit of the method and showed that large arrays of single (or pairs of) nanoparticles can be reproducibly deposited. We further explored the possibility to deposit different visible fluorescent proteins using NADIS without loss of protein function. The intrinsic fluorescence of these proteins is characteristic of their structural integrity; the retention of fluorescence after NADIS deposition demonstrates that the proteins are intact and functional. This study demonstrates that NADIS can be a viable alternative to other scanning probe lithography techniques since it combines high resolution direct writing of nanoparticles or biomolecules with the versatility of liquid lithography techniques.

Multifunctional cantilever-free scanning probe arrays coated with multilayer graphene

Scanning probe instruments have expanded beyond their traditional role as imaging or "reading" tools and are now routinely used for "writing." Although a variety of scanning probe lithography techniques are available, each one imposes different requirements on the types of probes that must be used. Additionally, throughput is a major concern for serial writing techniques, so for a scanning probe lithography technique to become widely applied, there needs to be a reasonable path toward a scalable architecture. Here, we use a multilayer graphene coating method to create multifunctional massively parallel probe arrays that have wear-resistant tips of uncompromised sharpness and high electrical and thermal conductivities. The optical transparency and mechanical flexibility of graphene allow this procedure to be used for coating exceptionally large, cantilever-free arrays that can pattern with electrochemical desorption and thermal, in addition to conventional, dip-pen nanolithography.

Dip Pen Nanolithography: A Desktop Nanofabrication Approach Using High-Throughput Flexible Nanopatterning

Abstract Dip Pen Nanolithography (DPN) is a scanning probe lithography technique where an atomic force microscope tip is used to transfer molecules to a surface via a solvent meniscus. This technique allows surface patterning on scales of under 100 nanometres. DPN is the nanotechnology analog of the dip pen (also called the quill pen), where the tip of an atomic force microscope cantilever acts as a “pen,” which is coated with a chemical compound or mixture acting as an “ink,” and put in contact with a substrate, the “paper.” DPN enables direct deposition of nanoscale materials onto a substrate in a flexible manner. The vehicle for deposition can include pyramidal scanning probe microscope tips, hollow tips, and even tips on thermally actuated cantilevers. Recent advances have demonstrated massively parallel patterning using two-dimensional arrays of 55,000 tips, depicted below. Applications of this technology currently range through chemistry, materials science, and the life sciences, and include such work as ultra high density biological nanoarrays, additive photomask repair, and brand protection for pharmaceuticals.

Scanning Probe Oxidation Lithography on Ta Thin Films

A Semi-Contact Scanning Probe Lithography Technique (SC-SPL) has been applied to create nano-oxide patterns on Ta thin films grown by DC magnetron sputtering method on SiO2/Si substrates. The height and linewidth profiles of nano-oxide lines created by a conductive AFM tip on Ta film surfaces were measured as a function of applied voltage, oxidation time, humidity, and tip apex curvature. The AFM surface measurements show that the height of the oxides increases linearly with increasing voltage; but there was no oxide growth, when less than 4 V was applied even at 85% relative humidity. Electrical measurements were performed and the resistivities of the TaOx layer and Ta film were obtained as 5.76 × 108 and 1.4 × 10−5 Ohm-cm, respectively.

In situ observation of the behavior of superoxide dismutase aggregates on a patterned surface via scanning probe microscopy

The spatially localized immobilization of protein molecules on high-density poly(ethylene glycol) (PEG) modified Si(1 0 0) is demonstrated. Silicon dioxide patterns are formed on the surfaces by scanning probe lithography techniques, and activated with functionalized materials. The well-defined pattern surfaces were used as model substrates to study the behavior of superoxide dismutase aggregates with directly applied local stimuli. Superoxide dismutase molecules are covalently immobilized to activated regions on the PEG/Si surface. Herein, the protein patterning technique introduced is compatible with microelectronics, and may have a variety of biological applications.

Dip-Pen Nanolithography for Templated Assembly with Biomaterials and Organic Films

Dip-Pen Nanolithography (DPN) is a scanning-probe lithography technique that permits the chemical functionalization of surfaces with nanoscale precision. We describe the use of DPN to pattern a variety of soft organic and biological nanostructures that we use to direct the assembly of materials processed from solution. For example, by selectively functionalizing electrodes with nanoscale DNA patterns we are able to capture specific sizes of metal nanoparticles and measure their electrical properties. In another application, by generating high-resolution (sub-100 nm) patterns with different functional self-assembled monolayers on various electrode surfaces, we have the ability to systematically nucleate, as well as guide, the phase separation behavior of polymer films when they are spin-coated onto substrates. We discuss the potential use of these techniques in applications ranging from biological diagnostics to organic electronics.

Scanning thermal lithography: Maskless, submicron thermochemical patterning of photoresist by ultracompliant probes

This article introduces a scanning probe lithography technique in which ultracompliant thermal probes are used in the selective thermochemical patterning of commercially available photoresist. The micromachined single-probe and multiprobe arrays include a thin-film metal resistive heater and sensor sandwiched between two layers of polyimide. The low spring constant (<0.1N∕m) and high thermal isolation provided by the polyimide shank is suitable for contact mode scanning across soft resists without force feedback control. The probes provide what is effectively a spatially localized postexposure bake that crosslinks the photoresist in the desired pattern, rendering it insoluble in developer. For 450-nm–1400-nm-thick AZ5214E (Clariant Corp.), line and dot features with sizes of 450–1800nm can be printed using probe powers of 13.5–18mW, and durations of 1–60s per pixel. Variation of feature sizes with process parameters is described.

Negative Differential Resistance in Patterned Electroactive Self-Assembled Monolayers

The phenomenon of negative differential resistance (NDR) is potentially very useful in molecular electronics device schemes. Here, it is shown that NDR can be observed in self-assembled monolayers composed of electroactive thiols on gold. Furthermore, these monolayers can be patterned using a scanning probe lithography technique described earlier to form a basis for potential molecular electronic device construction.