Uv curved nano imprint lithography
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UV-Curved Nano Imprint Lithography. Lithography Imprint-To produce (a mark or pattern) on a surface by pressure . Nanoscale Uv - Method. Introduction. This was first invented by Prof. Stephen Chou and his students in 1995. This is a method of fabricating nanometer scale patterns.

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Uv curved nano imprint lithography

UV-Curved Nano Imprint Lithography

  • Lithography

  • Imprint-To produce (a mark or pattern) on a surface by pressure.

  • Nanoscale

  • Uv- Method


  • This was first invented by Prof. Stephen Chou and his students in 1995.

  • This is a method of fabricating nanometer scale patterns.

  • It creates patterns by mechanical deformation of imprint resist and subsequent processes.

  • This is the road map for the 32-nm semiconductor technology


  • The materials required for the Imprint technique is

    • (i) a mold with predefined surface relief nanostructures, and

    • (ii) a suitable resist material that can be deformed and hardened to preserve the shape of the impression.

Mold fabrication
Mold Fabrication

  • Thermal expansion co-efficient is an important factor to be considered.

  • Si, SiO2, SiC, silicon nitride, metals,sapphire, and diamond film.

  • Steps in fabrication:-

    • A resist material is spin-coated onto the mold surface.

    • Followed by lithography to define the desired mold pattern.

    • A hard masking layer, such as a metal can be deposited over the patterned resist template.

    • Followed by a lift-off process that removes the resist template and the material on top, leaving a patterned mask layer on the Si substrate.

    • An anisotropic RIE process is used to selectively etch away the Si material in the unmasked region, producing the surface relief structures required for NIL


  • Thermoplastic Nanoimprint lithography

  • Uv-curved NanoImprintLithographhy

  • Roll imprint process,

  • Laser-assisted direct imprint,

  • Reverse imprint lithography,

  • Substrate conformalimprintlithography,

  • Ultrasonic NIL, etc.

Uv curved method
Uv-Curved Method

  • The UV curved Nanoimprint Lithography is normally carried out in room temperature and at low pressure.

  • The mold material used is of transparent type fused with silica.

  • Here we do use the soft UVfor the lithographic process.

  • The resist material used is the liquid polymer but in thermal method they use thermal plastic.


  • The transparent mold is pressed over the resist material.

  • Now the cavities are fully filled by the resist.

  • Now the resist is curved by the UV-rays so that the resist will become solid and it is etched till the base.

  • After demolding, a similar pattern transfer process can be used to transfer the pattern in resist onto the underneath material

Crucial process issues for nil
Crucial process issues for NIL

  • Thickness and uniformity of residual layer..

  • Pattern fidelity(Precision)

  • Defect control

  • Filling process

Key concern for nil templates
Key concern for NIL templates

  • Template surface treatment

  • Defect inspection.

  • Lifetime.


  • Nanoimprint lithography has experimentally been shown to achieve 25nm feature size .

  • The promise of repeatability and durability consequently leads this to low costs and ease of fabrication.


  • The surface sticking problem has not been perfected .

  • The molding conditions haven’t been optimized .

  • The effect of thermal expansion through the process is not fully understood.


  • Nanoimprint lithography has been used to fabricate devices for electrical, optical, photonic and biological application.

  • For electronics devices, NIL has been used to fabricate MOSFET, O-TFT, single electron memory. For optics and photonics, intensive study has been conducted in fabrication of subwavelength resonant grating filter, polarizers, waveplate, anti-reflective structures, integrated photonics circuit and plasmontic devices by NIL.

The future of nanoimprint
The future of nanoimprint

  • Nanoimprint lithography is a simple pattern transfer process that is neither limited by diffraction nor scattering effects nor secondary electrons, and does not require any sophisticated radiation chemistry. It is also a potentially simple and inexpensive technique.

  • However, a lingering barrier to nanometer-scale patterning is the current reliance on other lithography techniques to generate the template.

  • As of October 2007, Toshiba is the only company to have validated nanoimprint lithography for 22 nm and beyond.


  • S. Chou, P. Krauss, P. Renstrom, 1996, “Nanoimprint lithography,” J. Vac. Sci. Technol. B, Volume 14(6), pp. 4129-4133.

  • S. Chou, P. Krauss, P. Renstrom, 1996, “Imprint Lithography with 25-Nanometer Resolution,” SCIENCE, Volume 272, pp. 85-87.

  • www.wikipedeia.org