Parallel patterning of nanoparticles via electrodynamic focusing of charged aerosols

Nature Nanotechnology (Impact Factor: 34.05). 11/2006; 1(2):117-21. DOI: 10.1038/nnano.2006.94
Source: PubMed


The development of nanodevices that exploit the unique properties of nanoparticles will require high-speed methods for patterning surfaces with nanoparticles over large areas and with high resolution. Moreover, the technique will need to work with both conducting and non-conducting surfaces. Here we report an ion-induced parallel-focusing approach that satisfies all requirements. Charged monodisperse aerosol nanoparticles are deposited onto a surface patterned with a photoresist while ions of the same polarity are introduced into the deposition chamber in the presence of an applied electric field. The ions accumulate on the photoresist, modifying the applied field to produce nanoscopic electrostatic lenses that focus the nanoparticles onto the exposed parts of the surface. We have demonstrated that the technique could produce high-resolution patterns at high speed on both conducting (p-type silicon) and non-conducting (silica) surfaces. Moreover, the feature sizes in the nanoparticle patterns were significantly smaller than those in the original photoresist pattern.

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Available from: Bangwoo Han, Aug 25, 2014
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    • "The particles were attracted to a desired position due to the electrostatic force of particles and the 'patterned' area. The charged particles could also be deposited onto a surface patterned with a photoresist controlled by the introduction of ions having the same polarity together with the charged aerosol particles (Kim et al., 2006). The ions accumulated on the photoresist modified the applied field, in order to focus the nanoparticles onto the exposed parts of the patterned surface. "
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    ABSTRACT: Highlights - Charged aerosol particles were derived from spraying colloidal droplets. - Substrate with different “levels” of hydrophilicity was used. - Positively charged aerosol particles tended to approach the “more hydrophilic” area. - Association found between hydrophilicity of surface and number of deposited particles. Abstract The effect of chemical treatment of a metallic substrate on the deposition behavior of charged aerosol particles derived from spraying droplets was investigated. A single substrate with areas having different hydrophilic levels was prepared as target surface. The treated (i.e. higher hydrophilic level) area, measured using a surface potential meter, showed a higher negative potential. A numerical simulation predicted that positively charged aerosol particles tended to approach and were subsequently immobilized on the high hydrophilic area. The area with higher hydrophilicity could collect particles with higher number concentration (density) than the other areas. The relationships were demonstrated in (i) the electrostatic surface potential, (ii) the hydrophilicity of surface, and (iii) the enhancement of adhesive force between the deposited particles and the surface.
    Full-text · Article · Dec 2014 · Journal of Aerosol Science
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    • "Metal precursor loaded block copolymer micelles [19], Au(I) thiolate thin films [20] [21], thiolated Au [22], tetraoctylammonium bromide-capped Pd nanocrystal sols [23], and gold cluster compounds [24] have served as negative resists in ion or e-beam lithography to create mesoscale lattices of nanocrystals. Electrodynamic focusing of aerogels containing Ag nanocrystals has been employed to produce nanoparticle patterns on conducting and nonconducting surfaces [25]. Au nanoparticles embedded in micelles have been cast into nanopatterns via nanoimprint lithography [26]. "
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    ABSTRACT: A simple, inexpensive direct micromolding method for patterning Au nanocrystal superlattices using a polydimethylsiloxane (PDMS) stamp has been developed. The method involves in situ synthesis of Au(I) dodecanethiolate and its decomposition leading to Au nanocrystals in the microchannels of the stamp which order themselves to form patterned superlattice stripes, in conformity with the stamp geometry. Owing to its insolubility in common solvents, the dodecanethiolate was made by reacting Au(PPh3)Cl and dodecanethiol in situ inside the microchannels, by injecting first the former solution in toluene at room temperature followed by the thiol solution at 120 °C. Annealing the reaction mixture at 250 °C, resulted in formation of nanocrystals (with a mean diameter of 7.5 nm) and hexagonal ordering. By using an external pressure while molding, parallel stripes with sub-100 nm widths were obtained. The choice of parameters such as injection temperature of the thiol and concentrations is shown to be important if an ordered superlattice is to be obtained. In addition, these parameters can be varied as a means to control the nanocrystal size. Keywordsnanolithography-soft lithography-metal nanocrystal superlattice-micromolding-direct patterning
    Full-text · Article · Aug 2010 · Nano Research
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    • "This method could be a neat method for nano-patterning. Unlike our work, Kim et al. (2006) was not intended to develop a simple and inexpensive method to deposit particles for characterizing the surface inspection tools. "
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    ABSTRACT: It is required to characterize surface inspection tools using particles of known material and size, with controllable deposition spot size for adjusting deposited-particle number density on a mask or a wafer surface. Not all the materials commonly seen in semiconductor manufacturing are available in the form of monodisperse particles. Thus for some materials, it is inevitable to use polydisperse particles for characterizing the surface inspection tools. The differential mobility analyzer (DMA) is widely used to generate monodisperse aerosol. The DMA, however, can classify unwanted larger particles of multiple charges along with singly charged particles of a target size, due to the same electrical mobility. The present study proposed a Tandem-DMA (TDMA) system comprising two DMAs and two radioactive sources to reduce the fraction of multiply charged particles. Using this TDMA system, SiO2 nanoparticles with approximately 98% size-uniformity were fractionated from a broad size distribution. All DMAs utilized in this study were calibrated using Standard Reference Materials (SRM 1963) issued by the National Institute of Standards and Technology (NIST), in order to produce particles with NIST-traceable sizes. An analytic equation was derived to predict the deposition spot size on a surface in case of the electrostatic particle sampling, and agreed well with experimental and numerical data.
    Full-text · Article · Jun 2008 · Journal of Aerosol Science
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