Optimization of dose parameters for square lattice photonic crystals fabricated via non-dedicated EBL and capacitive coupled RIE for integrated photonic sensors

Top-down fabrication of photonic crystals (PhCs) for integrated photonic sensor applications demands high-resolution patterning techniques such as electron beam lithography (EBL) and reactive ion etching (RIE). Achieving precise and repeatable structures on non-dedicated EBL systems remains a significant challenge, particularly for complex 2D periodic lattices. In this work, we present an optimized fabrication process for square lattice photonic crystals—both holes-in-slab and rods-in-air configurations—on silicon substrates using a non-dedicated EBL platform. A systematic dose-factor matrix and proximity-effect–corrected exposure strategy were implemented using a Raith Elphy Quantum system integrated with FESEM. Quantitative SEM and AFM analysis demonstrates controlled feature size, etch depth, surface roughness, and dimensional fidelity as a function of dose factor. The results establish a reproducible fabrication window for square-lattice PhCs and provide a scalable methodology for laboratories without access to dedicated EBL systems. The demonstrated process enables reliable fabrication of photonic crystal structures suitable for integrated photonic sensor applications using standard nanofabrication tools.