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Contact (User Office)

 

Karlsruhe Nano Micro Facility
KIT-Campus North

Building 440

H.-von-Helmholtz-Platz 1

76344 Eggenstein-Leopoldshafen, Germany

 

phone: +49(721)608-23123

fax: +49(721)608-26273

knmf-userofficeMfi9∂kit edu

User Office

KNMF Profile

3D Direct Laser Writing (3D-DLW)

KNMF Laboratory for Micro- and Nanostructuring

3D Direct Laser Writing is a tool to fabricate 3D freeform structures down sub µm. It is based on Two-Photon Lithography but beyond that 2D and 2.5D structures with nano dimensions are also possible. This system uses a nonlinear two-photon absorption process to modify, e.g. polymerize, a photosensitive medium at a specific point in the resist. By scanning the photoresist with a stage over this point a 3D-structure with dimensions in the submicron scale or greater can be written.

Download technology description (PDF)

Contacts (3D-DLW)
Name Phone E-mail
stefan hengsbachVdh9∂kit edu
klaus badeFis5∂kit edu

Details (3D-DLW)

Equipment

  • Nanoscribe Photonic Professional GT
    - Several sample holders
    - Galvoscan unit
    - Hybrid stage for large accurate travel distances
  • Critical point dryer (supercritical CO2)
  • Coming soon: UV flood exposure (shell writing mode for large structures)

Features

  • Resolution:
    3D:200 nm lateral, 750 nm normal
    2D: 180 nm
  • Feature Structure size: max. 600 x 600 x 3700 µm³ depending on filling factor
  • Writing modes: piezo (100x DIP), galvoscan (63x GT, 25x GT)
  • Corresponding writing fields: 300 x 300 x 300 µm³; 140 x 140 µm²; 280 x 280 µm²
  • Writing times: piezo slow, galvoscan fast
  • Larger areas have to be stitched
  • Accessible writing area: 100 x 100 mm² where structures could be placed

Limitations/constraints

  • The realizable structure size depends on the structural stability of the design
  • The best results can be reached by using the IP-resists

Materials

Resists

  • Negative Resists: IP-L, IP-G, IP-Dip, IP-S, and similar resists that are photosensitive at a wavelength of 380nm
  • Positive Resist: AZ9260 (in preparation)
  • Experimental Resists are possible, but only the Air mode objective or oil-immersion Objective are applied. Dip-in techniques can only be used with proven compatibility.

Substrates

  • 25 x 25 x 0.7 mm Glass, glass covered with ITO, cover slides 22 x 22 x 0.17 mm
  • Si-wafer 4’’ (100 mm)
  • Si/SiO2-wafer 4’’ (100 mm
  • Metallized Si-Wafer (Cr/Au)
  • Other substrates have to be provided by the user.

Sample structures

3D-DLW sample structures...

Writing principle

3D-DLW writing principle

Sketch of the writing of a line in 3D-space inside a resist layer. The inset shows the modification in the voxel (blue) at the focal position. Only in the voxel two-photon absorption occurs.

Writing modes

3D-DLW writing modes

Data

  • Stl-format
  • CAD data can be exported in stl-format:
  • Sometimes CAD programs export erroneous stl-files. Solid works and similar programs used in mechanical engineering produce correct stl.files.
  • To avoid errors within stl-files the following rules can help:
    - Use correct units during contruction (µm), otherwise resolution could be bad
    - Use volumes, no areas, these objects have to be closed
    - Avoid Boolean operations
    - Avoid duplexes (use snaps)
    - Think about plane orientation. Normals are used to define interior or exterior.  Therefore contruct plane consistently.
    - Avoid additional structures not necessary (not written) to your part. Correction of the stl-file is nearly impossible
    - In case of periodic structures a single unit cell is sufficient.