High-temperature-capable ALD-based inorganic lift-off process

Lift-off is a useful method to pattern metals or other materials in semiconductor device fabrication. Polymer photoresists are commonly used for lift-off; however, these resists cannot be used when the device fabrication requires high temperature with the lift-off materials in place. Here, we have used bilayer stacks of metal oxides deposited by plasma-enhanced atomic layer deposition (PEALD) to provide a lift-off process compatible with high temperatures (>500 °C). By using selective wet-etching techniques, we successfully created reentrant or undercut structures and achieved lift-off for micro- and nano-scale devices. We also demonstrated that the metal-oxide based inorganic lift-off process allows high-temperature material deposition and/or annealing as a part of the fabrication process. The inorganic lift-off technique overcomes temperature limits of polymer resists and provides a photoresist-residue-free and high-temperature capable process.