Automated Nanomanipulation for Repairing Defects on Nanoimprint Lithography Masters

The fabrication of Nanoimprint Lithography (NIL) masters serves as the initial process in the manufacturing of devices such as silicon photonic chips using NIL. Repairing defects and modifying structures on an NIL master accurately is critical for NIL manufacturing. This study proposes an innovative scanning electron microscope (SEM)-based in-situ nanomanipulation technique to address the macro-micro-nano cross-scale nanopositioning issues necessary for repair functions. A macro/micro closed-loop control system was designed, which includes a frequency/voltage (f/u) proportional controller, a real-time direct inverse hysteresis compensation feedforward controller, a grating displacement sensor, and a cross-scale nanopositioning platform. The performance testing of the nano-manipulation approach resulted in a repair range of $22.18\times 20.92 \times 10.06$ mm3, meeting the repair requirements for most silicon photo chip NIL masters in terms of size. The system achieved a repair accuracy at 4.946 nm (X-axis), 4.663 nm (Y-axis), and 4.679 nm (Z-axis). As a demonstrate, the repair functionality testing confirmed the ability of the system to remove target structures such as cantilever beams and detach adhered particles from a master surface. Note to Practitioners—Although nanomanipulation systems theoretically show significant potential for repairing defects in micro-nanostructured NIL masters, there are still numerous challenges in terms of size, actuation methods, and other aspects for nanomanipulation systems suitable for master defect repair. To overcome these challenges, an in-situ nanomanipulation system suitable for the SEM environment is proposed, along with the design of a corresponding macro/micro closed-loop control system to achieve macro-micro-nano cross-scale motion positioning, meeting the requirements for master defect repair functions. The developed nanomanipulation system can provide a new technical means for the defect repair of micro-nanostructured NIL masters, thereby promoting the development of NIL in various important fields.