AFM nanolithography
From Biohack
- good - [pdf] AFM nanolithography review
- lithography
- AFM
Contents |
Reviews in AFM
- [20-29]
- [25-28] - or generally described AFM nanolithography in the broader context of other techniques including scanning tunneling microscope (STM) lithography and soft lithography [25–28].
- Molecular deposition [22]
- Local chemical reaction [23,24]
- Biological structure manipulations [29]
Main techniques
Force-assisted nanolithography
Mechanical indention and plowing [14]
- Elastic deformations
- Plastic deformations
Indention
Static plowing
Dynamic plowing
Plastic
- patterning of polymers by AFM mechanical nanolithography [14, 30-34]
- Cappella & Sturm
- Dynamic plowing faster than nanoindention
- polymethyl methacrylate (PMMA) film
- polystyrene (PS) film
- AFM tip could induce polymer chain breaking during dynamic plowing
- size-exclusion chromatography (30)
Heyde et al. developed a scan-linearized AFM instrument capable of 250 mm  250 mm scan size for large scale dynamic plowing lithography [34]. The system permits one to operate the microscope in several modes, and allows the addition of desired functions such as force modulation, Kelvin force microscopy, and adhesion mode. Using this set-up, they were able to write straight lines up to 50 mm long by performing dynamic plowing on PMMA film. Fig. 3 shows three straight grooves embossed by the tip, and the accumulation of carved PMMA by the sides of the grooves. The authors discussed the dependence of lithography efficiency on scanning parameters such as the set-point amplitude, scanning directions, and feedback status.
AFM nanoindention w/ metals
[35-41]
- Pyo et al. employed the polymer plowing technique to fabricate bottom-contact pentacene organic thin-film transistors (OTFTs) with a submicrometer channel length [50]. Source and drain electrodes were defined by mechanically scratching the Au layer on SiO2/Si with an AFM probe. The sample was then treated with hexamethyldisilazane (HMDS), and pentacene was evaporated onto the system to complete the OTFTs fabrication.
Thermomechanical writing [15]
Nanomanipulation [16]
Dip-pen nanolithography (DPN) [17] [review:22]
Bias-assisted nanolithography
As for bias-assisted AFM nanolithography, the AFM tip is biased to create a localized electric field in the regime of 10^8 V/m to 10^10 V/m, and the tip acts as a nanoscale electrode for current injection or collection. Under such a high localized field, electrostatic, electrochemical, field emission, dielectric breakdown and explosive gas discharge processes can be initiated to facilitate pattern formation. Depending on the magnitude of tip bias and substrate materials, the application of tip voltage can lead to anodic oxidation [12], electrochemical deposition [18], electrostatic attraction [19], and nanoscale explosion and shock wave propagation [20,21]. In anodic oxidation, the tip is negatively biased, and the local field induces the ionic dissociation of a water meniscus formed between the tip and sample surface. The oxidative OHÀ anions migrate along the field and react with the substrates to form oxide structures. Electrochemical deposition is capable of generating positive structures with distinct physico-chemical properties from the precursor materials through bias-induced local chemical reactions.
- Probe anodic oxidation [12] [review:23, 24]
- Field evaporation
- Electrochemical deposition [18] and modification
- Electrostatic attraction [19]
- Electrical cutting and nicking
- Electrostatic deformation
- Electrohydrodynamic nanofluidic motion
- Nanoexplosion [20]
- Shock wave generation [21]
- Charge deposition and manipulation
To make an STM
- TEM pictures of an STM tip [1]
Nanofabrication
Bottom-up
DNA self-assembly
Chemistry
Top-down
- (nano)lithography
