High quality nanogratings far beyond diffraction limits on silicon efficiently fabricated using femtosecond laser dual-beam interference direct writing

• Published in: Optics and laser technology Vol. 181; p. 111505
• Main Authors: Li, Kang, Han, Ruozhong, Suo, Mengqi, Long, Mingquan, Chen, Long, Cao, Kaiqiang, Zhang, Shian, Feng, Donghai, Jia, Tianqing, Sun, Zhenrong, Xu, Hongxing
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2025
• Subjects: Beyond diffraction limit; Dual-beam interference direct writing; Laser-induced periodic surface structures (LIPSS); Silicon; Laser-induced periodic surface structures (LIPSS); Silicon; Beyond diffraction limit; Dual-beam interference direct writing
• ISSN: 0030-3992
• DOI: 10.1016/j.optlastec.2024.111505

•Developed femtosecond laser dual-beam interference for BDL nanogratings on silicon.•Achieved ultrafine nanogratings with Λ/2, Λ/3, Λ/4 periods, improving fabrication precision.•Produced smooth grating stripes with low line edge roughness (2.23 nm) and minimal DSOA (2.3°).•Enhanced nanoplasma and surface plasmon effects reduce LER, DSOA, and groove widening.•Improved large-area nanolithography efficiency, quality, and reduced overall production costs. This study demonstrated a femtosecond laser dual-beam interference direct writing (DBIDW) method for fabricating high-quality nanogratings on silicon. The nanogratings had Λ/2, Λ/3, and Λ/4 periods, with Λ slightly smaller than the laser wavelength. The grating stripes exhibited extremely smooth and straight edges, with an average line edge roughness (LER) of 2.23 nm and a difference in structural orientation angle (DSOA) of 2.3°. The formation mechanism involves interference enhancement inducing nanoplasma formation in periodic stripes, while local asymmetric enhancement by surface plasmons significantly increases light intensity inside the nanogrooves. This method greatly reduces thermal effects and debris deposition, offering significant advantages for high-efficiency, low-cost, large-area nanolithography.