CSAR 62 is routinely used to produce innovative quantum devices at the TU Delft (Mr. Toivo Hensgens, TU-Delft, the Netherlands). For the structures shown below, a 72 nm layer of CSAR 62 was exposed to 100 kV and then developed with amyl acetate.
To evaluate the suitability of various developers for CSAR 62, Dr. Lothar Hahn (Karlsruhe Institute of Technology (KIT), Institute of Microstructure Technology) kindly provided various substrates which had previously been exposed to 100 kV e-beam irradiation (dose variations).
The copolymer composed of methyl methacrylate and methacrylic acid is, in contrast to the pure PMMAs, able to form a 6-membered ring during thermal loading.
In addition to the use in e-beam lithography, the highly sensitive e-beam resist CSAR 62 can also be structured by exposure to UV radiation since the resist strongly absorbs UV radiation in the wavelength range of 190 – 240 nm.
Mr. Y. Nori from Lancaster University (Department of Physics, UK) could very successful generate structures for the production of photonic crystals with CSAR 62.
Even the highly sensitive e-beam resist CSAR 62 can be used as mask for an etching process with HF (BOE, 10:1).
These nanostructures may e.g. serve as optical antennas for the detection of single molecules. To avoid the undesirable charges on the quartz substrate, Electra 92 was used successfully.
CSAR 62 layers can also be patterned by intensive exposure to UV light. Irradiated films were in this experiment developed with different solvents and the observed sensitivities were compared with each other.
The sensitivity of CSAR 62 is strongly influenced by the choice of the developer. In comparison to the standard developer AR 600-546, the sensitivity can be increased almost tenfold if AR 600-548 is used instead.
The use of a combination of CSAR 62 and the conductive coating Electra 92 in e-beam lithography allows the manufacture of highly complex structures on insulating glass or semi-insulating substrates such as e.g. gallium arsenide.