Mechanism of Corrosion Selectivity of NSb₂Te Thin Films in the H₃PO₄/HNO₃ Developer for Direct Laser Writing Nanolithography

Abstract

The SbTe thin film is a promising heat-mode resist for direct laser writing nanolithography owing to the simple fabrication procedure and clear phase change thermal threshold. However, the lower corrosion selectivity and still unclear developing mechanism restrain the further development of SbTe thin films in the lithography fields. This work reports the NSb 2 Te thin film as a promising heat-mode resist with a high corrosion selectivity of 500 in the H 3 PO 4 /HNO 3 developer. Moreover, nanoscale structures are successfully obtained with a linewidth of 150 nm and resolution of 50 nm. The microstructural evolution and electrochemical corrosion behavior of the NSb 2 Te thin film are investigated in detail, and the corrosion selectivity mechanism is further elucidated. Results reveal that the exposed NSb 2 Te thin film possesses Sb and Te hexagonal phases with a lower corrosion potential and charge transfer resistance, which is readily oxidized and corroded in HNO 3 /H 3 PO 4 solution. On the other hand, the as-deposited NSb 2 Te thin film will form N−Sb and N−Te bonds, possessing higher corrosion potential and charge transfer resistance. This results in the lower corrosion rate in HNO 3 /H 3 PO 4 solution. Therefore, the giant difference of microstructures and electrochemical behavior leads to the high corrosion selectivity of the NSb 2 Te thin film. The NSb 2 Te-based nanohole array is further fabricated to achieve tunable perfect absorption, and the maximum absorbance can reach 1.0 in the wavelength range of 400−800 nm. This work may provide a helpful reference for the investigation of the direct laser writing nanolithography mechanism and nanoscale functional devices.