Direct laser writing technology for microrelief metal structures on thin chromium films

• Datum: 2026
• Автори та афіліації: Ю. І. Чегіль — Інститут проблем реєстрації інформації НАН України; О. М. Буток — Інститут проблем реєстрації інформації НАН України; Є. В. Беляк — Інститут проблем реєстрації інформації НАНУ; А. А. Крючин — Інститут проблем реєстрації інформації НАН України
• Ключові слова: keywords
• Hauptverfasser: Чегіль, Ю. І., Буток, О. М., Беляк, Є. В., Крючин, А. А.
• Format: Artikel
• Sprache: Ukrainisch
• Veröffentlicht: Інститут проблем реєстрації інформації НАН України 2026
• Schlagworte: direct laser writing; laser ablation; microrelief structures; thin chromium films; diffraction optical elements; pulsed laser radiation; laser micromachining
• Online Zugang: https://drsp.ipri.kiev.ua/article/view/363130
• Назва журналу: Data Recording, Storage & Processing

Direct laser writing is increasingly considered a promising maskless alternative to conventional photolithography for the fabrication of microrelief structures required in photonics, micro-optics, and information-optical systems. The present study investigates the formation of micro-structured relief on thin chromium films and analyzes the physical mechanisms governing pulsed laser interaction with metallic layers, with particular emphasis on achieving high spatial resolution and reproducibility while preventing thermal damage to the substrate. Chromium films with a thickness of 180–200 nm and optical density of 2,3–2,5 at a wavelength of 1,06 μm were processed using pulsed laser irradiation to selectively remove the metal layer and form functional microstructures. Experimental processing was carried out using a pulsed infrared laser system operating at a scanning speed of 300 mm/s, an average power of 3 W, and a pulse repetition rate of 40 kHz, which ensured stable energy delivery and high-contrast pattern formation. The interaction of pulsed laser radiation with metallic thin films is governed by nonlinear absorption, avalanche ionization, thermal diffusion, melting, evaporation, and plasma shielding processes, whose relative contribution depends on pulse duration, energy density, repetition rate, and scanning conditions. Ultrafast regimes promote localized energy deposition with minimal heat-affected zones, whereas longer pulses enhance thermal diffusion and may cause substrate heating and plasma shielding. The experimental results confirmed that direct laser writing enables controlled formation of microrelief structures with micron-scale precision, sharp contours, uniform ablation depth, and minimal surface roughness under optimized exposure conditions. Exceeding the ablation threshold energy density results in substrate overheating, microcracking, and degradation of structural morphology, highlighting the necessity of precise parameter optimization. Additional experiments using ultraviolet laser irradiation demonstrated selective removal of chromium films with minimal thermal impact on the glass substrate, confirming the feasibility of localized patterning and substrate preservation. It was also established that increasing pulse repetition rate improves productivity but may induce cumulative heating and plasma shielding, influencing ablation efficiency and surface morphology. The obtained results demonstrate stable geometric fidelity and reproducibility of microstructures, confirming the effectiveness of direct laser writing for fabricating both simple geometric elements and complex functional patterns. The proposed approach eliminates photolithographic and chemical processing steps, simplifies the technological cycle, and improves reproducibility, making it suitable for manufacturing diffraction optical elements, coding disks, optical encoders, sensor structures, and microelectromechanical components. The study confirms that optimized pulsed laser processing provides a flexible and efficient technological basis for precision micro-structuring of metallic thin films and supports the integration of direct laser writing into advanced photonic and microfabrication applications. Fig.: 7. Refs: 15 titles.