Effects of molecular properties on nanolithography in polymethyl methacrylate

Dobisz, Elizabeth A.; Brandow, Susan L.; Bass, R.; Mitterender, Jeffrey

doi:10.1116/1.591242

Cited by 76 publications

(66 citation statements)

References 17 publications

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“…Gray-scale EBL patterning can also be obtained by using a fixed accelerating voltage and by locally changing the exposure dose. Given that the molecular weight M of the resist changes during the e-beam irradiation [58], modulating the lateral distribution of M by controlling the deposited dose is now possible. During development, the resist is immersed into a solution with etching selectivity depending on M; thus, variation of M is revealed as resist height modulation [59][60][61].…”

Section: Focused Electron Beams: Towards 3d Nanostructuresmentioning

confidence: 99%

Tipping solutions: emerging 3D nano-fabrication/ -imaging technologies

et al. 2017

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The evolution of optical microscopy from an imaging technique into a tool for materials modification and fabrication is now being repeated with other characterization techniques, including scanning electron microscopy (SEM), focused ion beam (FIB) milling/imaging, and atomic force microscopy (AFM). Fabrication and in situ imaging of materials undergoing a three-dimensional (3D) nano-structuring within a 1−100 nm resolution window is required for future manufacturing of devices. This level of precision is critically in enabling the cross-over between different device platforms (e.g. from electronics to micro-/ nano-fluidics and/or photonics) within future devices that will be interfacing with biological and molecular systems in a 3D fashion. Prospective trends in electron, ion, and nano-tip based fabrication techniques are presented.

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Section: Focused Electron Beams: Towards 3d Nanostructuresmentioning

confidence: 99%

Tipping solutions: emerging 3D nano-fabrication/ -imaging technologies

et al. 2017

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“…1). For even smaller D, irregularities in PMMA (∼5 nm [23]) became comparable in size with the designed features and, unavoidably on this scale, we could only estimate the device geometry. The measurements discussed below were carried out by using the standard lock-in technique with dc bias over a T range from 0.3 to 300K.…”

mentioning

confidence: 99%

Chaotic Dirac Billiard in Graphene Quantum Dots

Пономаренко

Schedin

Katsnelson

et al. 2008

Science

2,184

1,590

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The exceptional electronic properties of graphene and its formidable potential in various applications have ensured a rapid growth of interest in this new material [1,2]. One of the most discussed and tantalizing directions in research on graphene is its use as the base material for electronic circuitry that is envisaged to consist of nanometer-sized elements. Most attention has so far been focused on graphene nanoribbons (see [3][4][5][6][7][8][9] and references therein). In this Letter, we report quantum dot (QD) devices made entirely from graphene, including their central islands (CI), quantum barriers, source and drain contacts and side-gate electrodes. We have found three basic operational regimes for such devices, depending on their size. For relatively large (submicron) CIs, size quantization plays an insignificant role, and our devices were found to operate as orthodox singleelectron transistors (SET) exhibiting periodic Coulomb blockade (CB) oscillations. The CB regime has been extensively studied previously using metallic and semiconducting materials [10,11] and, more recently, the first SET devices made from graphite [12] and graphene [1,13,14] were also demonstrated. The all-graphene SETs reported here are technologically simple, reliable and robust and can operate above liquid-helium temperatures T, which makes them attractive candidates for use in various charge-detector schemes [10]. For intermediate CI sizes (less than ∼100nm), we enter into the quantum regime, in which the confinement energy δE >10meV exceeds the charging energy E c . Such a strong quantization for relatively modest confinement is unique to massless fermions [1,2] and related to the fact that their typical level spacing δE ≈v F h/2D in a quantum box of size D is much larger than the corresponding energy scale ≈h 2 /8mD 2 for massive carriers in other materials (v F ≈10 6 m/s is the Fermi velocity in graphene, h the Planck constant and m the effective mass). This means that level splitting in graphene-based 100-nm devices should be tens and hundreds times larger than in typical semiconducting and metal QDs, respectively. This regime is probably most interesting from the fundamental physics point of view, allowing studies of relativistic-like quantum effects in confined geometries [15][16][17][18][19][20][21]. In particular, we have observed a strong level repulsion in QDs, which is a clear signature of quantum chaos (so-called "neutrino billiards" [15]). Conductance of our smallest devices is dominated by individual constrictions with sizes down to ∼1nm, which exhibit δE ∼0.5eV and a good-quality transistor action at room T. It is remarkable that these molecular-scale structures survive microfabrication procedures, remain mechanically and chemically stable and highly conductive under ambient conditions and sustain large (nA) currents. Our devices were made from graphene crystallites prepared by micromechanical cleavage on top of an oxidized Si wafer (300nm of SiO 2 ) [22]. By using high-resolution electron-beam lithography, we de...

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“…The reflow temperature is usually set to be close to the highest T g within these polymer regions. In the variation of TASTE used in this work, the simultaneous change of the molecular weight M w [13,7] and the T g [7] due to electron beam exposure of thermoplastic resists is exploited. Doses required for certain step heights are extracted from the resist contrast curve.…”

Section: Taste Processmentioning

confidence: 99%