New opportunities in the field of MEMS/NEMS development by using modern E-Beam Lithography have been created. This was successfully demonstrated for Fabry-Pérot-interferometer device product by patterning aluminium ring resonator structures with critical dimensions down to 100 nm. In future times this interferometer can be used as high-resolution infrared spectrometer.

For transferring the resist pattern into the wafer stack, new hardmask and etching processes have been developed because standard processes were not suitable for these nanostructures.

E-Beam Lithography made it possible to investigate different optical designs of the ring resonator arrays on the wafers. A detailed characterization of the optical functionality will be carried out in follow-up projects in 2010.

Summary of the E-Beam Litho at Fraunhofer CNT for MEMS/NEMS:
• Pattern: arrays of ring structures with different size and shape
• Critical dimensions: 100 nm to 650 nm
• Stack: 100 nm aluminium / Si3N4 / SiO2
• Resist: thickness ~600 nm, tonality negative, chemically amplified

Caption:

a) SEM picture detail of an 800 µm x 800 µm ring array after aluminium etch step.

b) X-Section picture of resist structures after E-Beam Litho step

c) SEM picture of the aluminium rings after etching and stripping of the resist mask

Different 100nm gates with artificial line edge roughness (LER)
-> Test impact of line edge roughness on device performance