Simprint Core v3.3

Developing processes for nanoimprint lithography requires materials and time. Simulating the imprint process with Simprint software helps shorten this development phase by letting you refine crucial process parameters such as temperature, pressure, and duration before entering the lab.

Simprint’s flexibility lets you evaluate alternative stamp and resist materials, or even compare the imprinting performance of alternative pattern layouts before committing to the cost of a physical stamp.

Numerical simulation with Simprint helps build intuition about the physics of the nanoimprint process, and so is invaluable for researchers in the field.

NIL process development without simulation

NIL process development with Simprint simulation

Chip design

Stampproduction

Test lot

•Re-design layout•Re-make stamp•5+ weeks’ delay•Costs $10k+

Experts’ time

Process development

Chip design

Stampproduction

Test lot

Process development

Simprint simulation

Fast, intuitive and comprehensive softwarefor nanoimprint lithography process development

Some questions that can be answered using Simprint Core:

If I change my stamp material from silicon to polyurethane, what effect will this have on the residual layer thickness (RLT) uniformity of the imprinted pattern?

If I want to reduce the imprinting temperature by 10 °C, how much longer must I imprint to ensure complete cavity filling?

How much can I improve residual layer thickness uniformity by redesigning my stamp so that its protrusions are more uniformly arranged?

How thick should I spin on the initial resist layer to ensure that all cavities on my stamp will be filled with resist by the end of the imprinting process?

PMMA 495 kg/mol, imprinted at 165 °C, 40 MPa, 1 min

Simprint Core is based on comprehensive, experimentally validated models

Complete flexibility to specify stamp materials and thicknesses.

Built-in resist material models, including thermal and UV-curing resists.

Simulations can be done at the scale of individual features, or at the chip- or wafer-scale by using sophisticated pattern abstraction tools.

Simprint products are based on five years’ PhD research and the underlying algorithms are licensed from MIT under copyright.

Process parameters Specify process parameters

such as imprinting temperature, pressure and duration.

Time

Temperature

Pressure

Stamp layout designResist model

Physical predictionResidual layer thickness; cavity filling extent

Simprint Core streamlines process development

Choose from a menu of widely used thermal and UV-curing resists, including micro resist mr-I 7000E and mr-I 8000E series materials, whose temperature-viscosity behaviour is modelled.

For custom resists, you can enter viscosity, surface tension and contact angle parameters directly.

Analyse results graphically

View pseudocolour maps of residual layer thickness (RLT), stamp cavity filling extent, and stamp-resist contact pressure

Plot cross-sections through simulated maps of RLT, cavity filling, or pressure

Plot the evolution during imprinting of average RLT and RLT variation across the stamp

Plot the evolution during imprinting of stamp cavity filling

Export AVI videos of the evolution of simulated parameters

Export images of plots for inclusion in reports

Export results to text files for further analysis

RLT cross-sectionRLT map

Section

Cavity filling Cavity filling evolution

Import GDS stamp layout files

Simulation Engine Unlike competing software, Simprint Core does

not require every feature to be represented individually in the simulation, enabling efficient chip- or wafer-scale simulation.

Balances spatial resolution with speed according to simulation needs.

Simulation speeds are at least 1000 times faster than finite-element simulation techniques.

Simulation results can guide improvements in process parameters and stamp design

Stamp: local deformation and bending modelled

Resist: Newtonian viscosity during imprinting

Wafer: Elastic deformations modelled

Resist deformation is described using a Newtonian model, whose viscosity, in the case of thermal NIL resists, falls with process temperature.

Capillary pressures between the stamp and resist are included; these pressures can accelerate stamp filling, especially for low-viscosity UV-NIL resists.

Stamp deformation: local deformations and longer-range stamp bending are both simulated, so Simprint Core can simulate the impact of varying stamp stiffness or thickness.

Simprint Core has been validated both at the feature scale and using more complex test-patterns as shown here. Resist: PMMA 495 kg/mol (200 nm initial thickness), 180 °C, 10 min, 16 MPa, 10 replicates

1 mm

Si stamp

cavityprotrusion

Res

idua

l lay

er th

ickn

ess

(mic

ron)

Lateral position (mm)Cavity proportions filled

A

B

C

D

E

F

G

H

A B

C D

E F

G H

550 nm-deep cavities: Exp’t Simulation

Applied pressure: configurable to be applied hydrostatically or via a solid platen

Simulation capabilities

Wafer nanotopography (random imperfections of the wafer surface) can be included in a Simprint Core simulation. This capability is particularly helpful for simulating NIL on rough substrates such as GaN. You can either import a measured surface topography or use built-in roughness models.

Complex patterns can be abstracted on a square grid, each region of which is modelled using a characteristic feature shape, size and areal density of protrusions.

Before imprint After imprint

Experimental validation

The Simprint Core package

Simprint Core is a standalone program that runs on Windows PCs.

Affordable: an academic Simprint Core licence costs €1500 + 15% annual maintenance fee. Customised Commercial license packages upon request.

Comes with fully documented simulation examples.

One year’s unlimited support by e-mail, phone and web.

Simprint Nanotechnologies will help you build your first simulations from scratch.

Not sure Simprint Core is what you need? We can run a trial simulation free of charge, if you send us your existing stamp design and process. We send you the results so you can see how Simprint Core performs.

Simulation services Simprint Nanotechnologies also offers consultancy on NIL

process development. Simprint Reports are competitively priced, starting at just €500, and give recommendations on optimised process parameters.

Further information Contact our partner, NIL Technology (www.nilt.com), e-mail us

at info@simprintnanotech.com, or visit Simprint’s website: www.simprintnanotech.com.

The Simprint Core graphical user interface

Key publications H.K. Taylor and E.J. Wong, "Fast

simulation of nanoimprint lithography: modeling capillary pressures during resist deformation", NNT 2011.

D.S. Boning, A.B. Kahng, H.K. Taylor, and Y.-K. Wu, "Chip-scale simulation of residual layer thickness uniformity in thermal nanoimprint lithography: evaluating stamp cavity-height and 'dummy-fill' selection strategies," NNT 2010

H.K. Taylor, K. Smistrup, and D.S. Boning, “Modeling the enhancement of nanoimprint stamp bending compliance by backside grooves: mitigating the impact of wafer nanotopgraphy on residual layer thickness,” NNT 2010.

H.K. Taylor and D.S. Boning, “Towards nanoimprint lithography-aware layout design checking,” Proc. SPIE, vol. 7641, 764129, 2010. DOI: 10.1117/12.846499

Abstracts at simprintnanotech.com

Simprint Nanotechnologies is incorporated in England with limited liability. Company number 7321148. VAT registration number GB103252371.