Resist of the Month of October: Medusa 82 – alternative to HSQ

According to Greek mythology, one look at the Greek goddess Medusa 82 turned everyone to stone. E-beam resist Medusa 82 has quite similar properties; upon electron beam irradiation of the Medusa 82 polymer silsesquioxane, structures of SiO2 (sandstone) are formed, which offers many promising applications.

The long-established HSQ resists show excellent resolution and etch stability, but these advantageous properties come along with a low sensitivity and high process instability. In addition, HSQ must be processed very quickly to obtain reproducible results.

Allresist now developed Medusa 82 as an alternative to HSQ resists. Due to a modification of the polymer, resist Medusa 82 can be handled very easily. A time span of a few days between coating, irradiation and development is now possible without any losses in quality. Sensitivity, etching behaviour and resolution otherwise corresponds to the properties of HSQ resists.

11 nm lines with Medusa 82 at a dose of 1250 µC/cm², 30 kV, Raith GmbH

For a new variant of this resist, the sensitivity could even be increased by a factor of 20. Due to the addition of a photoacid generator, now only 60 μC/cm² are required to achieve complete cross-linking. It is a small sensation that particularly highly etch-resistant masks can now be written about 20 times faster than before. Our research project is almost finished; all results will be presented by Allresist at the MNE in Copenhagen on 24 September 2018.

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