Limitations to Silylated Resist Technology

Silylated, dry-developed resists have demonstrated superior resolution performance beyond that of their solution-developed resist counterparts. However, the implementation of plasma-developed resists in the manufacture of integrated circuit devices has only been realized in pilot line fabrication despite the fact that silylated resists additionally avoid other imaging pitfalls including thickness variations over topography, limited depth of focus and reflection-induced exposure variations. This is exemplified most dramatically with deep-UV lithography at 248 nm. Silylated resists have printed 0.2 μm features with a 0.53 NA exposure tool at this wavelength without any benefit from optical "tricks". The implementation of silylation technology is not considered seriously yet because of the conviction that solution-developed resists will meet the specifications for fabricating 0.25 μm design rule devices in the near term. But will the actual yields be high enough and the processing and materials costs be low enough? For silylated resists, on the other hand, the difficulties and challenges revolve around the availability of production worthy equipment, the complex nature of the dry processing, yields which may be adversely affected by particles produced in the plasma development environment and cost.