Photochemical reactivity of bis-carbamate photobase generators

Tran, Hoang V.; Jackson, Edward A.; Eldo, Joby; Kanjolia, Ravi; Rananavare, Shankar B.

doi:10.1109/nano.2011.6144469

Cited by 2 publications

(2 citation statements)

References 11 publications

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“…These effects are more pronounced with exposure to high-energy EUV light and E-beams, systems that need orders of magnitude fewer photons/particles compared to normal optical lithography 8 . Supersensitive chemically amplified (with a quantum efficiency >1) photoresists also introduce a chemical SN caused by a variation in the number of photoreactive molecules in exposed nanoregions 9,10 . Lower sensitivity photoresists that need longer exposures suppress these effects, but they also reduce throughput.…”

Section: Introductionmentioning

confidence: 99%

Use of Sacrificial Nanoparticles to Remove the Effects of Shot-noise in Contact Holes Fabricated by E-beam Lithography

Rananavare

Morakinyo

2017

JoVE

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Section: Introductionmentioning

confidence: 99%

Use of Sacrificial Nanoparticles to Remove the Effects of Shot-noise in Contact Holes Fabricated by E-beam Lithography

Rananavare

Morakinyo

2017

JoVE

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“…Over the last fifty years, the lithographic resolution has improved through the use of (a) light sources, including excimer lasers, with progressively smaller UV wavelengths; (b) clever optical designs employing phase-shift masks . Supersensitive chemically amplified (with a quantum efficiency >1) photoresists also introduce a chemical SN caused by a variation in the number of photoreactive molecules in exposed nanoregions 9,10 . Lower sensitivity photoresists that need longer exposures suppress these effects, but they also reduce throughput.…”

Section: Introductionmentioning

confidence: 99%

Use of Sacrificial Nanoparticles to Remove the Effects of Shot-noise in Contact Holes Fabricated by E-beam Lithography

Rananavare

Morakinyo

2017

JoVE

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Nano-patterns fabricated with extreme ultraviolet (EUV) or electron-beam (E-beam) lithography exhibit unexpected variations in size. This variation has been attributed to statistical fluctuations in the number of photons/electrons arriving at a given nano-region arising from shot-noise (SN). The SN varies inversely to the square root of a number of photons/electrons. For a fixed dosage, the SN is larger in EUV and E-beam lithographies than for traditional (193 nm) optical lithography. Bottom-up and top-down patterning approaches are combined to minimize the effects of shot noise in nano-hole patterning. Specifically, an amino-silane surfactant self-assembles on a silicon wafer that is subsequently spin-coated with a 100 nm film of a PMMA-based E-beam photoresist. Exposure to the E-beam and the subsequent development uncover the underlying surfactant film at the bottoms of the holes. Dipping the wafer in a suspension of negatively charged, citrate-capped, 20 nm gold nanoparticles (GNP) deposits one particle per hole. The exposed positively charged surfactant film in the hole electrostatically funnels the negatively charged nanoparticle to the center of an exposed hole, which permanently fixes the positional registry. Next, by heating near the glass transition temperature of the photoresist polymer, the photoresist film reflows and engulfs the nanoparticles. This process erases the holes affected by SN but leaves the deposited GNPs locked in place by strong electrostatic binding. Treatment with oxygen plasma exposes the GNPs by etching a thin layer of the photoresist. Wet-etching the exposed GNPs with a solution of I 2 /KI yields uniform holes located at the center of indentations patterned by E-beam lithography. The experiments presented show that the approach reduces the variation in the size of the holes caused by SN from 35% to below 10%. The method extends the patterning limits of transistor contact holes to below 20 nm. Video LinkThe video component of this article can be found at https://www.jove.com/video/54551/ 4 ; and (c) higher NA. For exposure in air (η = 1), NA is always less than unity, but by introducing a liquid with η >1, such as water 5 , between the lens and the wafer, NA can be elevated above 1, thereby improving the resolution of immersion lithography. Currently viable paths to a 20-nm node and beyond include extreme UV sources (λ = 13 nm) or patterning techniques using complex double and quadruple processing of a multilayered photoresist 6,7 .At nanometer-length scales, statistical fluctuations, caused by shot-noise (SN), in the number of photons arriving within a nano-region cause variation in the dimensions of lithographic patterns. These effects are more pronounced with exposure to high-energy EUV light and E-beams, systems that need orders of magnitude fewer photons/particles compared to normal optical lithography 8

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Photochemical reactivity of bis-carbamate photobase generators

Cited by 2 publications

References 11 publications

Use of Sacrificial Nanoparticles to Remove the Effects of Shot-noise in Contact Holes Fabricated by E-beam Lithography

Use of Sacrificial Nanoparticles to Remove the Effects of Shot-noise in Contact Holes Fabricated by E-beam Lithography

Use of Sacrificial Nanoparticles to Remove the Effects of Shot-noise in Contact Holes Fabricated by E-beam Lithography

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