Selective dry etch process for step and flash imprint lithography

摘要

In order for Step and Flash Imprint Lithography (S-FIL) to be considered a viable printing technology to produce sub-100 nm geometries, a reliable pattern transfer etch process needs to be established. Unlike optical lithography processes, imprinting features via S-FIL creates a residual layer of several hundred angstroms thick, which requires a break-through etch prior to etching the transfer layer. Of greater concern is the etch barrier used as the imaging layer for S-FIL technology. The incorporated silicon content is limited to approximately nine percent, and the formulation is geared toward achieving mechanical properties for the imprinting process. As a result, typical oxygen-based plasmas used for transferring more conventional bi-layer structures are not compatible with the current S-FIL resist stack. A reducing chemistry using ammonia (NH_3) plasma has been developed in providing a selective etch process for pattern transfer using S-FIL technology. The development of this NH_3-based process was a key enabler in the fabrication of the world's first surface acoustic wave filters patterned via S-FIL technology.