Material-dependent near-field enhancement in alternative photomask platform for nanoscale lithography

Abstract

As optical nanofabrication moves toward ever smaller feature sizes, new approaches are required to overcome diffraction limits and achieve precise control of light at subwavelength scales. High-resolution patterning is critical for applications in advanced electronics, photonics, and nanodevices, where even small variations in feature size can strongly impact performance. Near-field photolithography provides a promising method for nanoscale patterning by concentrating electromagnetic fields at the photomask surface, enabling features smaller than the diffraction limit. In these systems, the optical performance is highly sensitive to the material properties of the photomask, including refractive index, absorption, and interaction with deep-ultraviolet illumination. These properties directly influence light distribution, confinement, and image quality, making careful material selection essential for high-resolution lithography. In this work, an alternative photomask material is investigated to evaluate its effect on near-field energy confinement and imaging performance at the nanoscale. Finite-difference time-domain (FDTD) simulations are employed to study electromagnetic field distributions, intensity enhancement, and spatial resolution within the imaging region. The results show that optimized material platforms can significantly enhance near-field confinement and contrast compared to conventional mask designs. These findings highlight the critical role of photomask material properties in advanced lithographic systems and provide practical guidance for selecting materials capable of supporting next-generation high-resolution optical nanofabrication.