23 October 2013 Hayden Taylor* and Niswan Dhakal Nanyang - - PowerPoint PPT Presentation

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23 october 2013 hayden taylor and niswan dhakal nanyang
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23 October 2013 Hayden Taylor* and Niswan Dhakal Nanyang - - PowerPoint PPT Presentation

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A chip-scale imprinter with integrated optical interference for calibrating models of NIL resists and resist-stamp boundary conditions 23 October 2013 Hayden Taylor* and Niswan Dhakal Nanyang Technological University, Singapore Joel Yang and

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SLIDE 1

A chip-scale imprinter with integrated optical interference for calibrating models of NIL resists and resist-stamp boundary conditions

23 October 2013 Hayden Taylor* and Niswan Dhakal Nanyang Technological University, Singapore Joel Yang and Zhu Di Institute for Materials Research and Engineering, Singapore * hkt@ntu.edu.sg

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SLIDE 2

Outline

2

  • Resist model calibration by fitting

simulations to imprint experiments

  • The need for new tools to characterise

resist–stamp material combinations

  • Real-time optical monitoring of imprint
  • Potential RLT sensing enhancements:
  • Plasmonic
  • Ellipsometric
  • Potential applications of real-time
  • ptical imprint monitoring:
  • Endpoint detection
  • Process control
  • Defect detection (including non-fill)
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SLIDE 3

1 Taylor NNT 2009, 2011; 2 Taylor SPIE 7641 2010; 3 Boning et al. NNT 2010

0.5 1 Pattern abstraction Density Stamp Resist Wafer Stamp deflections

  • Residual thickness

(RLT) nonuniformity

  • Incomplete cavity filling
  • Lateral resist flow
  • RLT homogenization

Stamp’s load response (bending, indentation) Resist Stamp Resist surface’s impulse response Resist Substrate Example questions: Does changing stamp material affect residual layer uniformity? 1,2 Can ‘dummy fill’ accelerate stamp cavity filling? 3

92 99 10 165 Elastomer Silicon

(nm)

Simulations need to be highly scalable

  • At least 103 times

faster than FEM

  • Can trade off spatial

resolution and speed

101 102 103 104 102 103 104 Simulation size, N ~O(N2logN) 101 N Time (s)

1 2 3 4

3

Our existing simulation technique quickly finds RLT and cavity-filling distributions

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SLIDE 4

A B C D E F G H

The NIL simulation technique has been experimentally validated

1 mm Silicon test stamp: Cavities (~500 nm deep) Protrusions C A E G D B F H

5

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SLIDE 5

The technique has been validated for five thermoplastic materials

8 8

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SLIDE 6

Nanoscale experiments may involve substantial slip between resist and stamp

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Assuming no slip between resist and stamp or substrate

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SLIDE 7

The imprinting rate will depend strongly on any slip between resist and stamp/substrate

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d𝑠 d𝑢 = − 𝑠3𝑞0 4𝑙𝜃0𝑏0

2

1 − 2𝜀 + 𝑠 𝑏0

2

1 + 2𝜀

−1

Laun, J. Non-Newtonian Fluid Mechanics 81 (1999) 1-15

10

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SLIDE 8

Real-time observation of evolving RLT could accelerate material/stamp characterisation

100 µm

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SLIDE 9

Real-time observation of evolving RLT could accelerate material/stamp characterisation

Simulations

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SLIDE 10

RLT–colour relationships are calibrated using a known stamp topography

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Radius = 3.1 mm Silicon 150 µm Resist Stamp

Intensity gradient > 1/nm

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SLIDE 11

Videos of the imprinting process allow the temporal response of resist to be extracted

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  • Material:

MRT mr-UVCur-21

  • Stamp-average

pressure 20 kPa

  • Consistent with

viscosity ~ 7 Pa.s

100 µm

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SLIDE 12

If features are sub-wavelength, plasmonic effects could enhance RLT detection

Large features 25 nm-pitch dot array

D h g h RLT

h = D = 16 nm g = 9 nm Silicon Resist, n = 1.52 Quartz, n = 1.45 10 nm gold Simulated reflectivity spectra

RLT

E-field intensity (Joel Yang + Zhu Di)

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SLIDE 13

An anti-reflective stamp coating and light polarisation could enhance RLT contrast

16

DLC: diamond-like carbon (n ~ 2.09). “Polarised” means with crossed polarisers Contrast: relative change in intensity for a 1 nm change in RLT about a given RLT Substrate-enhanced ellipsometric contrast: Ausserré, Optics Express, 15 8329 (2007)

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SLIDE 14

Potential applications include endpoint detection and cavity filling monitoring

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  • Endpoint detection
  • Feedback control in R2R processing
  • Cavity filling
  • Stamp inspection/defect detection
  • Probing of complex fluids (e.g. biological samples)

100 µm Partially filled cavity 100 µm Resist residue

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SLIDE 15

Conclusions and outlook

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  • Resist rheological behaviour can be extracted

from nanoscale imprint experiments

  • Resist-stamp boundary conditions are critical

and require characterising

  • Real-time measurement of RLT can be

accomplished interferometrically using simple white light microscopy

  • Optical RLT measurement sensitivity can be

tuned using plasmonic or ellipsometric approaches

  • Real-time RLT measurement could be applied to

improve NIL yield and throughput

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SLIDE 16

Collaborators and acknowledgements

19

  • AMO, Germany
  • Christian Moormann
  • Ulrich Plachetka
  • Microresist Technology, Germany
  • Arne Schleunitz
  • Marko Vogler
  • Freimut Reuther
  • IMRE, Singapore
  • Goh Wei Peng
  • NTU, Singapore
  • Tan Boon Hwee
  • IBN, Singapore
  • Ciprian Iliescu
  • Trinity College Dublin
  • Graham Cross