Interference Lithography Gratings
Interference lithography is an optical nanolithography technology for the fabrication of extensive periodic nanostructures. Critical dimensions of less than 50 nm can be realized. At AMO two interference lithography tools are installed. One setup for extensive, high quality gratings with fixed periods, the other more flexible tool allows quick prototyping. We offer grating fabrication on silicon, silicon dioxide and other substrates with tailored pitch, etch depth and size.
Large area holographic gratings and diffractive optical elements
The exposure of wafers with a diameter up to 8″ (200 mm) requires a large optical table (2,5m x 4m), robust optical components and active fringe stabilization to compensate unavoidable vibration and noise causing phase modulation in the interferometer. AMO solved these problems and operates a 266 nm beam line with a fringe stabilization system based on a digital PID controller from AMOtronics.
Long lasting experience
For more than 15 years AMO has therefore developed and increased their product portfolio and successfully established several standard structures which are commercially available. Furthermore AMO offers prototyping solutions, e.g. for high efficient pulse compression gratings.
More details to every single above mentioned point can be found in the corresponding FactSheets “Interference Lithography” and “Nanogratings” in the sidebar on the right-hand side. The gratings available from stock are listed as well.
AMO’s product portfolio in interference lithography comprises the following:
Standard silicon gratings
- large-area, coherent and stitching free gratings
- high period fidelity as well as little phase distortion
- rectangular edge profile due to the use of chemically reinforced DUV photoresists in combination with anisotropic RIE etching processes
- in-house developed phase stabilization system enables the fabrication of high-contrast gratings
- high flexibility for realizing any possible pattern is achieved by process optimized positive and negative resists
- the use of an adapted BARC (bottom antireflective coating) minimizes the appearance of standing waves and hence enhances the structures’ dimensional accuracy
| Substrate material | Silicon (100) |
| Substrate thickness | (500µm – 650µm) ± 50µm |
| Substrate dimensions | 4”, 6”, 8” and every rectangular shape within |
| Type of grating | lines, pillars, holes, moiré pattern |
| Period | 150nm – 180nm, 250nm- 2500nm |
| Etch depth | Up to 1000nm (depending on period and type of grating) |
| Active area | depending on period and type of grating |
 Fully covered 4”, 6” and 8” wafer |
 250nm period, linear grating |
 450nm period, 2-D pillar-grating |
 550nm period, 2-D pseudohex holes |
Nanoimprint Masters + Templates
IL Master for Soft UV-NIL
- Master for fabrication of PDMS- or polymer stamps
- Stamps are compatible with Imprint tools MA8 by Suess as well as EV 620 by EV Group
- Upon customer request the master can be modified by a teflon like anti sticking layer
| Substrate material | Silicon (100) |
| Substrate thickness | (500µm – 650µm) ± 50µm |
| Substrate dimensions | 4”, 6”, 8” and every rectangular shape within |
| Type of grating | lines, pillars, holes, moiré pattern |
| Period | 150nm – 180nm, 250nm- 2500nm |
| Etch depth | up to 1000nm (depending on period and type of grating) |
| Active area | depending on period and type of grating |
 Master for plasmonic structures with 2 resonance frequencies |
 Master for plasmonic structures with 2 resonance frequencies |
 Master with pillar structures |
 Master with photonic crystal structures |
IL Templates for Hard UV-NIL
| Substrate material | Fused silica |
| Substrate thickness | 500µm – 6,35mm |
| Substrate dimensions | up to 6“ @ 500µm thickness, 1-1.5“ @ 6,35mm thickness |
| Type of grating | lines, pillars, holes, moiré pattern |
| Period | 250nm- 2500nm |
| Etch depth | up to 500nm (depending on period and type of grating) |
| Active area | depending on period and type of grating |
 800nm pillar grid, 4“ SiO2 wafer |
 200nm linear grating, 1” SiO2 sample |
 600nm linear grating, 1,5“ SiO2 |
Customer specific gratings
| Different dielectrics (SiO2, HfO2, Ta2O5) on silicon or fused silica with grating structure |  Ta2O5 top layer with 580nm grating |
| Coating on top of grating for diffraction efficiency enhancement |  300nm grating fused silica coated with 80nm Al |
| Antireflection structures for electroforming |  Moth eye structure |
| High aspect ratio gratings |  500nm pitch grating |
| Mix and match Interference lithography and electron beam lithography |  Waveguides in 500nm pillar grid |
| SiN spacer process for sub 10nm IL structures |  |
Services
- Patterned wafer defect inspection KLA 2139
- SEM und AFM inspection
- Characterization of absolute period by means of diffraction measurement