Ion-beam-etching based lift-off for reliable patterning of dense and inverse metallic nanostructures towards 10-nm scale

Reliable fabrication of metallic patterns at nanoscale is of great interest for various practical applications in nanodevices. Electron-beam-lithography based lift-off is the most often used method to define exquisite metal nanostructures at the 10-nm scale. In a common wet lift-off process, the metal material on top is lifted-off and washed away together with the sacrificial resist layer below. However, the wet lift-off process is sometimes ultrasonic agitation and/or heating-dependent and limited by the probable remained debris problem. In this work, we present an alternative lift-off process to obtain metallic patterns via removing the unwanted parts by using ion beam etching. We demonstrated that this ion-beam-etching based lift-off process is effective for isolated exposed negative-tone resist to fabricate nanoholes and nanoslits array and for dense networked exposed resist to fabricate high-density packed nanostructures. SERS measurements were conducted to demonstrate the molecular detection capability of the nanostructures with tiny gaps fabricated by this ion-beam-etching based lift-off process.