Super-resolution interference lithography enabled by non-equilibrium kinetics of photochromic monolayers

Vijayamohanan, Harikrishnan; Kenath, Gopal S.; Palermo, Edmund F.; Ullal, Chaitanya K.

doi:10.1039/c9ra05864h

Cited by 10 publications

(13 citation statements)

References 36 publications

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“…This reaction system is summarized in Figure with the overall kinetics given by where C α ( r , t ) and Ċ α ( r , t ) are the concentrations and time derivatives of various species α = MC, SP, MAP, and Atto discussed below, I 1,2 ( r , t ) are the intensity profiles, e 1,2 α are the extinction coefficients of each species at each wavelength, and ϕ r , ϕ f , k 3 , and κ are rate constants. Note that the intensities and concentrations depend on space and time (omitted above for clarity), while all other parameters are constants specific to the photoresist that have been experimentally measured and tabulated in ref .…”

Section: Methodsmentioning

confidence: 99%

“…Two-color photoresists with inhibition intensity thresholds that are several orders of magnitude lower , can be used in interference lithography configurations that involve the exposure of a photosensitive medium to two or more coherent beams of light. Interference lithography is inherently configured to support large-area coverage, albeit at the cost of being restricted to periodic patterns. − Feature sizes on the order of tens of nanometers have been demonstrated in thin films and monolayers while using visible light in super-resolution inspired interference lithography configurations. − …”

Section: Introductionmentioning

confidence: 99%

“…We then incorporate the intensity from this EM approach applied to two wavelengths in a self-consistent solution of the time-dependent chemical kinetics in the resist. We apply this technique over 2D simulation domains to gain insight into the fabrication of subwavelength lines using a spirothiopyran-based resist chemistry that is designed for super-resolution interference lithography. ,, Specifically, we investigate the deleterious effects of absorption and diffraction, the impact of varying intensity ratios and exposure times, the performance of standing waves in both colors compared to standing wave in only the inhibition beam, and different approaches to writing lines with subdiffraction spacing using multiple exposures.…”

Section: Introductionmentioning

confidence: 99%

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Coupled Electromagnetic and Reaction Kinetics Simulation of Super-Resolution Interference Lithography

et al. 2020

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Inspired by the ability of super-resolved fluorescence microscopy to circumvent the diffraction barrier, two-color super-resolution interference lithography exploits nonequilibrium kinetics in materials to achieve large-area nanopatterning while using visible light. Periodic patterns with super-resolved features down to tens of nanometers have been demonstrated in thin films and monolayers. Extending these advances to the bulk nanopatterning of thick films requires a quantitative understanding of the time-dependent interactions of optical dynamics, including absorption, diffraction, and intensity modulation at two wavelengths, with the photoactivated and inhibited reaction kinetics. Here, we develop an efficient electromagnetic (EM) perturbation theory approach that facilitates for the first time fully coupled simulations of EM and chemical kinetics in two-color interference lithography. Applied to a spirothiopyranfunctionalized photoresist system, these simulations show that diffraction and absorption effects are negligible (<0.1%) for depths up to 10 μm, and that tuning exposure time and intensities can lead to concentration contrast up to 80%. We investigate multiple exposure strategies to reduce the pitch of the line pattern including sequential exposures with different times to achieve uniform lines and multiplexed exposures with equal periods. This capability to rapidly and accurately predict the coupled optical and chemical dynamics facilitates the computational design of high-precision patterns in two-color interference lithography.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Coupled Electromagnetic and Reaction Kinetics Simulation of Super-Resolution Interference Lithography

et al. 2020

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“…Another irradiation scheme reduces the difficulty of the alignment, which consists of a collimated plane wave of the excitation light and a standing wave of the inhibition light. [133,134] Additionally, the interference patterns can be extended from fringes to lattices by superimposing multiple crossing standing waves. The apparatus and methods have been proposed to realize large-area PIL by superimposing excitation and inhibition lattice patterns.…”

Section: Interference Lithographic Pilmentioning

confidence: 99%

3D Sub‐Diffraction Printing by Multicolor Photoinhibition Lithography: From Optics to Chemistry

Zhang

Cao

et al. 2021

Laser & Photonics Reviews

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Photoinhibition lithography (PIL) is a nanoscale fabrication technique that uses multicolor visible light to enable the printing of arbitrary 3D structures beyond the diffraction limit. Photoinhibition allows the control and confinement of the exposed region for photoinitiation during the photolithographic process, thus improving the resolution of existing lithographic techniques, such as direct laser writing. Because PIL enables super-resolution 3D printing, it has a multitude of applications. In this review, practical applications of PIL in the areas of photonics, data storage, and biotechnology are highlighted; in addition, its unique features are revealed. The theory and recent advances in PIL for sub-diffraction printing and high-throughput fabrication are also discussed. Besides, challenges and tentative solutions are discussed with the hope of providing a preliminary roadmap for technological breakthroughs in PIL to enable developments of resolution and throughput.

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“…[ 14 ] As the field evolved, more work was conducted on improving photochromic response and performance. These involve structural and morphological control of preparation, [ 15,16 ] employing advanced micro/nanofabrication techniques, [ 17,18 ] compositing oxides with organic materials, [ 19 ] compositing of several oxides, [ 20 ] elemental doping, [ 21 ] and embedding chromic oxide materials into polymer matrices. [ 22,23 ] These techniques have enhanced the performance of photochromic oxides in terms of sensitivity, [ 24 ] responsivity, [ 25 ] flexibility, [ 26 ] and dynamic range.…”

Section: Introductionmentioning

confidence: 99%

UV Photochromism in Transition Metal Oxides and Hybrid Materials

Kayani

Kuriakose

Monshipouri

et al. 2021

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Limited levels of UV exposure can be beneficial to the human body. However, the UV radiation present in the atmosphere can be damaging if levels of exposure exceed safe limits which depend on the individual the skin color. Hence, UV photochromic materials that respond to UV light by changing their color are powerful tools to sense radiation safety limits. Photochromic materials comprise either organic materials, inorganic transition metal oxides, or a hybrid combination of both. The photochromic behavior largely relies on charge transfer mechanisms and electronic band structures. These factors can be influenced by the structure and morphology, fabrication, composition, hybridization, and preparation of the photochromic materials, among others. Significant challenges are involved in realizing rapid photochromic change, which is repeatable, reversible with low fatigue, and behaving according to the desired application requirements. These challenges also relate to finding the right synergy between the photochromic materials used, the environment it is being used for, and the objectives that need to be achieved. In this review, the principles and applications of photochromic processes for transition metal oxides and hybrid materials, photocatalytic applications, and the outlook in the context of commercialized sensors in this field are presented.

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Super-resolution interference lithography enabled by non-equilibrium kinetics of photochromic monolayers

Abstract: The non-equilibrium kinetics of spirothiopyran monolayers are studied to enable large area interference lithography with feature dimensions that circumvent the diffraction barrier.

Cited by 10 publications

References 36 publications

Coupled Electromagnetic and Reaction Kinetics Simulation of Super-Resolution Interference Lithography

Coupled Electromagnetic and Reaction Kinetics Simulation of Super-Resolution Interference Lithography

3D Sub‐Diffraction Printing by Multicolor Photoinhibition Lithography: From Optics to Chemistry

UV Photochromism in Transition Metal Oxides and Hybrid Materials

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