Dry thermal development of negative electron beam resist polystyrene

Con, Celal; Abbas, Arwa Saud; Yavuz, Mustafa; Cui, Bo

doi:10.12989/anr.2013.1.2.105

Cited by 4 publications

(5 citation statements)

References 11 publications

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“…In this paper we will report a simple liftoff process with a single layer negative resist by low energy exposure, which resulted in an undercut profile, with an un-cross-linked or a) Electronic mail: bcui@uwaterloo.ca only partly cross-linked bottom layer soluble in common solvents. We chose polystyrene to demonstrate the process since it is a very versatile resist, for which the exposure property can be tuned simply by varying the molecular weight, and it can be thermally developed 15 as well as coated by thermal evaporation for nanolithography on nonplanar surfaces. 16,17 The key advantage of our liftoff process is obviously its simplicity; however, we were not able to achieve sub-500 nm resolution with low energy exposure.…”

Section: Introductionmentioning

confidence: 99%

Lift-off with solvent for negative resist using low energy electron beam exposure

Dey

Cui

2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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Lift-off and direct etch are the two most popular pattern transfer methods for electron beam lithography. For some applications negative resist would offer significantly less exposure time than positive one. Unfortunately, lift-off using negative resist is very challenging because the resist profile is typically positively tapered due to electron forward scattering, and upon exposure, negative resist is cross-linked and thus insoluble in solvents. Here, the authors will show that low energy exposure can circumvent both issues simultaneously, and the authors achieved liftoff of Cr with polystyrene resist using a solvent xylene. Moreover, low energy exposure offers proportionally higher resist sensitivity. Lastly, since low energy electrons are mostly stopped inside the resist layer, radiation damage to the sublayer is greatly reduced. Thus, the current method may be employed to fabricate metal nanostructures on top of an organic conducting layer.

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Section: Introductionmentioning

confidence: 99%

Lift-off with solvent for negative resist using low energy electron beam exposure

Dey

Cui

2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…Figure shows the SEM images of the pattern obtained by using the PS brush as a negative resist with thermal development. We have previously precisely demonstrated thermal development of thick polystyrene resist . EBL was carried out with 5 keV at a line dose range of 2.2–3.8 nC/cm.…”

Section: Resultsmentioning

confidence: 99%

“…We have previously precisely demonstrated thermal development of thick polystyrene resist. 34 EBL was carried out with 5 keV at a line dose range of 2.2−3.8 nC/cm. Here low electron energy was selected to minimize proximity effect to achieve better resolution, and the optimum dose was determined experimentally where a range of line arrays with pitches from 50 nm to 1 μm and doses from 1 to 15 nC/cm were exposed.…”

Section: Resultsmentioning

confidence: 99%

Grafted Polystyrene Monolayer Brush as Both Negative and Positive Tone Electron Beam Resist

et al. 2017

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Although spin coating is the most widely used electron-beam resist coating technique in nanolithography, it cannot typically be applied for nonflat or irregular surfaces. Here, we demonstrate that monolayer polystyrene brush can be grafted on substrates and used as both positive and negative electron-beam resist, which can be applied for such unconventional surfaces. Polystyrene is a popular negative resist when using solvent developer but solvent cannot be used for grafted polystyrene brush that is firmly bonded to the substrate. Instead, we employed two unconventional development methods to lead polystyrene brush to positive or negative tone behavior. Negative tone was achieved by thermal development at 300 °C because exposed thus cross-linked polystyrene brush is more thermally stable against vaporization than unexposed linear one. Surprisingly, positive tone behavior occurred when the brush was grafted onto an aluminum (Al) layer and the film stack was developed using diluted hydrofluoric acid (HF) that etched the underlying Al layer. By transferring the patterns into the silicon (Si) substrates using the thin Al layer as a sacrificial hard mask for dry etch, well-defined structures in Si were obtained in two different electron-beam resist tones as well as in nonflat surfaces.

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“…We have chosen PS because it is a very versatile and a popular negative resist, offering ultrahigh resolution for low molecular weight, 2 and ultrahigh sensitivity for high molecular weight. 11 As well, it can be thermally developed, 12 coated by thermal evaporation to allow nanofabrication on irregular surfaces such as AFM cantilever and optical fiber, 13 or doped with metal Cr to greatly enhance its etching resistance. 14 Yet its adhesion to the silicon substrate is weak, and a cross-linked polymer sublayer has been previously employed to promote its adhesion.…”

Section: Methodsmentioning

confidence: 99%

Enhanced adhesion of electron beam resist by grafted monolayer poly(methylmethacrylate-co-methacrylic acid) brush

Viscomi

Dey

Caputo

et al. 2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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In electron beam lithography, poor resist adhesion to a substrate may lead to resist structure detachment upon development. One popular method to promote resist adhesion is to modify the substrate surface. In this study, the authors will show that a poly(methylmethacrylate-co-methacrylic acid) [P(MMA-co-MAA)] monolayer "brush" can be grafted onto a silicon substrate using thermal annealing that leads to chemical bonding of the P(MMA-co-MAA) copolymer to the hydroxyl group-terminated substrate, followed by acetic acid wash to remove the bulk, unbonded copolymer. The monolayer brush has a thickness of 12 nm. The authors will show that it can greatly improve the adhesion of positive resist, the ZEP-520A, and negative resist polystyrene to bare silicon surfaces, which led to high resolution patterning without resist detachment upon development. The improvement was more dramatic when patterning dense sub-100 nm period grating structures. But the improvement was negligible for an aluminum substrate, because, even without the brush layer, resist adhesion to aluminum is found already to be strong enough to prevent resist structure peeling off. The current simple and low cost method could be very useful when resist adhesion to the substrate for a given developer is weak. V

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Dry thermal development of negative electron beam resist polystyrene

Cited by 4 publications

References 11 publications

Lift-off with solvent for negative resist using low energy electron beam exposure

Lift-off with solvent for negative resist using low energy electron beam exposure

Grafted Polystyrene Monolayer Brush as Both Negative and Positive Tone Electron Beam Resist

Enhanced adhesion of electron beam resist by grafted monolayer poly(methylmethacrylate-co-methacrylic acid) brush

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