High Aspect-Ratio Laser Heat-Mode Patterning of Low-Loss Phase Change Material Sb2S3 for Micro/Nanolithography

Abstract Laser heat-mode lithography is an efficient method for micro/nano-patterning of phase change materials (PCMs). However, traditional PCMs exhibit limited exposure depth and insufficient aspect ratio due to their strong light absorption. This paper focuses on the laser heat-mode patterning characteristics of low-loss/low-absorption binary chalcogenide PCM Sb2S3, which has received significant attention in recent years due to its applications in dynamic nanophotonics. By comparing the optical and thermal transmission characteristics of Sb2S3 and classic PCM AgInSbTe through finite element simulation, the advantage of deep exposure brought by the high transmittance of Sb2S3 and the regulation law of film thickness on the photothermal process are demonstrated and analyzed. The heat-mode exposure of Sb2S3 thin films was carried out with a 405 nm laser direct writing system. The optimal developer concentration is obtained, and the physicochemical mechanism of its negative tone patterning is clarified through X-ray photoelectron spectroscopy (XPS). The preparation of micro−nano structures with a minimum line width of 125 nm and an aspect ratio greater than 1 is achieved on Sb2S3 thin films. The pattern transfer to Si substrates through inductively coupled plasma (ICP) etching is completed using Sb2S3 as a mask. This study provides a simple and effective method for the preparation of Sb2S3-based micro−nano optoelectronic devices, and a high-performance heat-mode resist material for micro/nanolithography.