High-fidelity fabrication of sub-millimeter thickness silica glass optical components via a synergistic suppression strategy in UV imprint lithography

Ultraviolet imprinting technology offers significant advantages in fabricating silica glass optical devices due to the high precision, high efficiency, and excellent reproducibility. However, when fabricating components with sub-millimeter thickness and high aspect ratios, the stress accumulation of multi-scale and multi-physical fields throughout the entire manufacturing process easily induces macroscopic warpage and geometric distortion in the components. To address the above issue, this paper systematically elucidates the multi-field coupled deformation-instability mechanism of the “liquid glass” system across the complete ultraviolet nanoimprint lithography (UV-NIL) chain. Furthermore, a synergistic deformation suppression strategy integrating interface engineering, chemical modification, and thermal-field reconstruction is innovatively proposed. First, local shear stresses can be eliminated by introducing a rigid metal mold-release interface. Second, camphor is added to the precursor to in-situ construct stress relief channels. Finally, a powder embedded debinding and stepped cooling process is developed to achieve thermal field homogenization. Thereby the stepwise amplification pathways of internal stresses have been effectively blocked. The experimental results show that this strategy successfully controls the overall deformation of sub-millimeter ultra-thin samples to below 45 μm, and significantly reduces the peak-to-valley distortion of 0.3 mm thick samples from 35.05 μm to 17.25 μm. Moreover, the fabricated samples maintain an exceptional visible transmittance of over 90 %. They also exhibit ultra-high microhardness (up to 1112.53 HV), and highly isotropic shrinkage characteristics. Based on this optimized process, typical complex sub-millimeter-thick components, including microwell plates, random microlens arrays, and one-/two-dimensional diffraction gratings, have been successfully fabricated with high-fidelity and superior optical performance. This study provides a systematic theoretical mechanism and a highly promising processing pathway to control deformation and achieve the high-fidelity, high-stability manufacturing of sub-millimeter ultra-thin silica glass optical components with high aspect ratios.