July 13, 2009: EV Group has unveiled a next-generation UV-nanoimprint lithography (NIL) step and repeat system eyeing use for microelectronics applications including optics/image sensors, lens arrays, and certain R&D nanoelectronics processes.

The EFG 770 Gen II NIL stepper offers vacuum imprinting (<50 mbar) on a spun-on polymer layer to eliminate defect issues caused by trapped air bubbles, which results in better pattern fidelity. Optical sensors align the stamp and wafer into parallelism for contact-free wedge compensation. A noncontact bearing system reduces particle contamination associated with chuck movement. System accuracy is within ±500nm, with <35nm overlay accuracy demonstrated on a test setup system. Load-cell measurement of embossing/de-embossing force improves imprint uniformity and process reliability, allowing for real-time in-situ characterization of resists (it can handle viscosities from 1 to several 1000mPas) and anti-sticking layers. Substrate loading/ unloading is fully automated from FOUP or SMIF pods; automated template loading is standard on all systems.

A main market for UV-NIL is micro-optics, e.g., full-wafer lens micromolding of CMOS image sensors for wafer-level cameras. Using UV-NIL, a master can be replicated across the substrate to produce a full-wafer lens micromold, which offers significant yield and cost advantages vs. other mastering processes like micromachining, photoresist reflow, LIGA, and e-beam writing, the company explained. Other markets also show potential, micro-lens arrays, waveguides, ring resonators, and R&D nanoelectronics processes for dual damascene and contact holes.

High-resolution features (70nm lines and 130nm space) imprinted on an EVG 770 (images from LETI/LTM) (Source: EV Group