Zirconium- and hafnium-based nanoparticles demonstrated good patterning behavior in deep-ultra-violet (DUV), electron-beam (E-beam) and extreme ultra-violet (EUV) lithography. Among these Zr- and Hf-based hybrid nanoparticles, the methacrylic acid (MAA) modified zirconium oxide nanoparticles<sup>1</sup> (ZrO<sub>2</sub>-MAA-NP) give out the best over-all-performance: 26 nm lines are obtained at 4.2 mJ/cm<sup>2</sup>. However, both Zr and Hf are relatively low EUV absorbing metals<sup>2</sup>, and integration of high EUV absorption elements, such as Zn, is considered to be a more promising route to further improve lithographic performance under EUV radiation. Zinc-based nanoparticle photoresists, possessing ultra-small size, have exhibited promising sensitivities and better resolution. Here, we combined methacrylate ligand and high EUV absorption element Zn, to demonstrate a novel zinc oxide-based nanoparticle photoresist using a photo-radical generator (PRG). Compared with conventional photo-acid initiated nanoparticle-based photoresists, a better resolution and sensitivity has been found with the addition of photo-radical generator (PRG). This unique behavior is promising to provide new possibilities for rapid three-dimensional (3D) -printing.
Extreme ultraviolet (EUV) lithography, using 13.5 nm radiation, is considered one of the most prominent candidates for next generation lithography. The main challenge for EUV resists is to simultaneously satisfy resolution, LWR (line-width roughness) and sensitivity requirements according to the ITRS roadmap<sup>1</sup>. Over the past few years, our main effort has been to focus on ZrO<sub>2</sub> and HfO<sub>2</sub> nanoparticle-based photoresists. However, both Zr and Hf are relatively low EUV absorbing metals<sup>2</sup>, and integration of high EUV absorption elements is considered to be a more promising route to further improve lithographic performance under EUV radiation. Here, we demonstrate novel zinc oxide-based nanoparticle photoresists, possessing small particle size, good solubility in spin-coating solvents, good film-forming abilitie and patterning by incorporating a photo-acid generator or photo-radical generator.