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Along with other Next Generation Lithography (NGL) methods, imprint lithography has been included on the International Roadmap for Semiconductors (ITRS) for the 32 nm node, predicted to be production-ready by 20131. Step and Flash Imprint Lithography (S-FIL) is one of the imprinting technologies being pursued due to its impressive imprinting capabilities, where imprinted features of less than 30 nm have been demonstrated. Unlike optical-based lithography, S-FIL uses techniques similar to that of contact printing, and thereby does not require complex and expensive optics and light sources to create images. Couple this with a reliable pattern transfer, and S-FIL could become a contender as a viable NGL technology. Similar to other imprint lithography systems, S-FIL printed features possess a residual layer several hundred angstroms thick, which requires a breakthrough etch prior to etching a subsequent layer. Of a greater concern, however, is the etch barrier used as the imaging layer for S-FIL. The present silicon content is limited to approximately nine percent, and the formulation is optimized for dispensing and achieving mechanical properties for the imprinting process. As a result, oxygen-based plasmas typically used for pattern transferring more conventional bi-layer structures are not compatible with the current S-FIL resist stack, and therefore pose a challenge from an etch perspective. The development of a recent etch process incorporating an ammonia-based plasma was a key enabler for pattern transfer, and ongoing development is being done to improve critical dimensions (CD). In this study, we examined a lift-off process using S-FIL. The material stacks with and without a "glue" layer will be discussed, and the challenges from imprinting to etch will be shared. Finally, the lift-off process will be used to demonstrate fabrication of a surface acoustic wave (SAW) device in addition to demonstrating patterning of a non-reactive metallization scheme such as Ti/Au.
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