Pattern formation on silicon by laser-initiated liquid-assisted colloidal lithography

Ulmeanu, M.; Petkov, Petko Vladev; Ursescu, D.; Maraloiu, Valentin-Adrian; Jipa, Florin; Brousseau, Emmanuel Bruno Jean Paul; Ashfold, Michael N. R.

doi:10.1088/0957-4484/26/45/455303

Cited by 6 publications

(10 citation statements)

References 24 publications

(41 reference statements)

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“…by tuning n with the LILAC lithography method) rather than simply irradiating in air, but is not able to predict diffraction effects due to the presence of the sphere boundary. The |E 2 | vs X profiles clearly illustrate how the colloidal particle acts as a convergent (n > 0) or divergent (n < 0) lens [6], and how immersing the particle in different liquid media provides a route to extending the focal length of the NF-F region [11]. Compared with NF-LA in air, where ablation is localised to the region of contact between the particle and the substrate (i.e.…”

Section: Resultsmentioning

confidence: 99%

“…Thus n < 0 in these examples and the NF-F patterns will appear as an ablation ring rather than the localized ablation crater seen in the case of NF-LA in air. The radius of this ablation ring (relative to the centre of the colloidal particle) can be tuned by changing the size of the colloidal particle or the magnitude of n [6]. The NF-S rings are again confined to areas outside the radius of the colloidal particle but, as we show below, the topographies can be very different from those formed in air.…”

Section: Surface Patterning Under a Liquidmentioning

confidence: 87%

“…The present work expands and generalizes such analyses by considering NF effects induced by light interacting with individual colloidal particles (or small arrays of such particles) on a substrate surface immersed in a liquidrather than in air. Our preliminary demonstration of the single pulse, laser induced liquid assisted colloidal (LILAC) lithography technique [6] revealed complex patterning of silicon substrates. The patterning was regarded as an imprint of the spatial intensity modulation formed by diffraction of the laser pulse by the colloidal particle(s).…”

Section: Introductionmentioning

confidence: 99%

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Substrate surface patterning by optical near field modulation around colloidal particles immersed in a liquid

Ulmeanu¹,

Petkov

Ursescu

et al. 2016

Opt. Express

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Optical near field enhancements in the vicinity of particles illuminated by laser light are increasingly recognized as a powerful tool for nanopatterning applications, but achieving sub-wavelength details from the near-field distribution remains a challenge. Here we present a quantitative analysis of the spatial modulation of the near optical fields generated using single 8 ps, 355 nm (and 532 nm) laser pulses around individual colloidal particles and small close packed arrays of such particles on silicon substrates. The analysis is presented for particles in air and, for the first time, when immersed in a range of liquid media. Immersion in a liquid allows detailed exploration of the effects on the near field of changing not just the magnitude but also the sign of the refractive index difference between the particle and the host medium. The level of agreement between the results of ray tracing and Mie scattering simulations, and the experimentally observed patterns on solid surfaces, should encourage further modelling, predictions and demonstrations of the rich palette of sub-wavelength surface profiles that can be achieved using colloidal particles immersed in liquids.

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Section: Resultsmentioning

confidence: 99%

Section: Surface Patterning Under a Liquidmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

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Substrate surface patterning by optical near field modulation around colloidal particles immersed in a liquid

Ulmeanu¹,

Petkov

Ursescu

et al. 2016

Opt. Express

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show abstract

“…Albeit a slowdown in process speed, a straightforward method to overcome diffraction limit was seen in processing using optical evanescent fields from the tip of an optical fiber [12] or microscope probes [13,14] in a scanning near-field microscopy approach. The possibility to work in the near-field was extrapolated to the use of microspheres self-organized on surfaces [15,16], a way to equally parallelize the interaction.…”

Section: Introductionmentioning

confidence: 99%

High-resolution material structuring using ultrafast laser non-diffractive beams

Stoian

Bhuyan

Rudenko

et al. 2019

Advances in Physics: X

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Scales in the 100 nm range represent a generic cornerstone for laser material processing, enabling novel size-dependent functions on surfaces and in the bulk and thus a new range of technological applications. On these scales, the processed material acquires optical, transport or contact properties that do not only rely on local effects on singular topographic features but involve increasingly collective behaviors. Rapid access to sub-100 nm features with intense coherent light represents nevertheless a challenge in laser structuring in view of the optical diffraction limit. Ultrafast non-diffractive beams with controllable time envelopes can overcome this limit and achieve super-resolved processing, a prerequisite for the next generation of flexible and precise material processing tools. They show a remarkable capacity of structuring transparent materials with high degree of accuracy and exceptional aspect ratio. This capacity relies on triggering fast hydrodynamic and material fracture effects with characteristic spatial scales in the nm range. Reviewing the present achievements and technical potential, we discuss from a dynamic viewpoint the physical mechanisms enabling structural features beyond diffraction limit achieved using ultrafast Bessel beams and indicate applications of high technical relevance. ARTICLE HISTORY

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“…Our recently demonstrated Laser Induced Liquid Assisted Colloidal (LILAC) lithography technique [ 14 , 15 ] allows complex patterning of substrates using single laser pulses and isolated, or small arrays of, colloidal particles immersed in a liquid. Two distinct contributions to the patterning were identified: (a) near-field laser ablation (NF-LA) rings, caused by near-field intensity enhancement effects, and (b) near field scattering (NF-S) ring structures with characteristic minima and maxima that arise as a result of interference between the incident laser beam, light reflected at the substrate surface, and light scattered by the particle.…”

Section: Introductionmentioning

confidence: 99%

Modifying the Morphology of Silicon Surfaces by Laser Induced Liquid Assisted Colloidal Lithography

et al. 2017

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Single, or isolated small arrays of, spherical silica colloidal particles (with refractive index ncolloid = 1.47 and radius R = 350 nm or 1.5 μm) were placed on a silicon substrate and immersed in carbon tetrachloride (nliquid = 1.48) or toluene (nliquid = 1.52). Areas of the sample were then exposed to a single laser pulse (8 ps duration, wavelength λ = 355 nm), and the spatial intensity modulation of the near field in the vicinity of the particles revealed via the resulting patterning of the substrate surface. In this regime, ncolloid < nliquid and the near-field optical intensification is concentrated at and beyond the edge of the particle. Detailed experimental characterization of the irradiated Si surface using atomic force microscopy reveals contrasting topographies. The same optical behavior is observed with both liquids, i.e., the incident laser light diverges on interaction with the colloidal particle, but the resulting interaction with the substrate is liquid dependent. Topographic analysis indicates localized ablation and patterning of the Si substrate when using toluene, whereas the patterning induced under carbon tetrachloride is on a larger scale and extends well below the original substrate surface—hinting at a laser induced photochemical contribution to the surface patterning.

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Pattern formation on silicon by laser-initiated liquid-assisted colloidal lithography

Cited by 6 publications

References 24 publications

Substrate surface patterning by optical near field modulation around colloidal particles immersed in a liquid

Substrate surface patterning by optical near field modulation around colloidal particles immersed in a liquid

High-resolution material structuring using ultrafast laser non-diffractive beams

Modifying the Morphology of Silicon Surfaces by Laser Induced Liquid Assisted Colloidal Lithography

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