Two-photon Lithography

Lithography & Patterning Installation 1
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This technique is encased in the direct laser writing family. Many UV photosensitive materials can similarly polymerize by the simultaneous absorption of two near IR photons (TPP: two photon polymerization). The chance of occurrence of this non-linear optical process is increased when an ultrashort pulse laser is focused tightly in a small given area. The size of this area depends on the laser spot and power, and on the properties of the material itself. Features in the vicinity of 100 nm are possible. By precisely scanning the laser focus throughout the material (or by moving the resist relatively to the fixed laser spot) a 3D extended volume can be affected, within the spatial limitations of the moving stage. As in any photolithographic process the chemical difference between unexposed and exposed volumes leads to selective material removal inside a developer bath. 3D arbitrary patterns can be defined in this way. As a particular case the laser can be constrained to a 2D pattern.

Examples of these materials are IPx photoresists, AZ resists family or SU-8. The photopolymers used can be commercially available, but also custom-developed materials by FORTH (such as ultra-high-resolution organic-inorganic hybrids, metal-binding materials, fluorescent and nonlinear materials.)

In many cases, polymers can be already the structural material required. If other materials, such as metals, silica, etc. are needed, the 3D patterns can be transferred from polymeric templates using inversion and casting techniques.

          provided at NFFA-Europe laboratories by:

Nanoscribe Photonic Professional GT @ Laboratory for Micro and Nanotechnology

Two-photon lithography

 NIR femtosecondd laser for two-photon polymerization

3D lateral feature size <200 nm, 2D lateral resolution <500 nm, finest vertical resolution 1.5 nm

Beam scanning speed 10 mm/s; piezo scanning speed 100 μm/s

Accessible print area 100x100 mm2; maximum object height fine: 300 μm, coarse 3 mm


Nanoscribe Photonic Professional

2D & 3D patterning by polymerization of photosensitive materials by pulsed laser

Near-IR source, 780 nm

Pulse length < 120 fs

120 mW power and acoustic-optic modulator (MAO)

Oil immersion objective 100x, with NA=1,4 and resolution up to 150 nm

Motorized positioning up to 100 mm  x100 mm (1 mm repeatability)

Piezoelectric positioner up to 300 mm  x 300 mm with 5nm repeatability

Sample holders for diameters of 30mm, 50mm and 100mm and 5”x5” square samples

Clean room ambient

Resist coater/developer