Reliable fabrication of nanoscale Cr patterns with dry lift-off process for hard mask applications in microelectronics

The fabrication of high-resolution and high-dense Cr masks is critical for precise pattern transfer in reactive etching processes. Lift-off based on electron-beam lithography is a commonly used and simple method for fabricating Cr nanostructures below 100-nm scale. However, conventional wet lift-off method suffers from issues such as fragment residues and low yield. In this work, we propose a dry lift-off method leveraging the weak adhesion between sputtered materials and PMMA resist to achieve high-yield (∼100 %) fabrication of high-resolution (line width<100 nm) and high-dense (gap<100 nm) Cr nanostructures that wet lift-off can hardly achieve. We demonstrate the application capability of our method by fabricating silicon infrared metalens using Cr nanostructures as etching hard masks, showing its potential for nanodevices fabrication with high-resolution and high-dense requirements.