The rapidly evolving world of technology demands the creation of incredibly small and precise electronic components. One of the biggest challenges in this area is developing materials that can efficiently produce high-resolution patterns with minimal energy consumption. What if there were a way to create these intricate designs with far less energy, making the entire process cheaper and more efficient? Recent advances in a specific type of material, highly hydroxylated hafnium clusters, have shown great promise in achieving this goal. These new materials not only reduce the energy required but also enhance the precision of the patterns, paving the way for the next generation of electronic devices.

A team of researchers from the National Tsing Hua University in Taiwan has made significant strides in the field of extreme ultraviolet (EUV) lithography, a critical technology for advancing semiconductor manufacturing. Led by Jui-Hsiung Liu along with Yu-Fang Tseng, Pin-Chia Liao, Po-Hsiung Chen, Professor Tsai-Sheng Gau, Dr. Burn-Jeng Lin, and Po-Wen Chiu, the team has successfully synthesized highly hydroxylated hafnium clusters that demonstrate exceptional performance as negative-tone EUV photoresists. This work is published in the peer-reviewed journal Nanoscale Advances.

The primary focus of the research was to develop photoresists that could achieve high-resolution patterns while requiring significantly lower energy doses. Traditional EUV photoresists often necessitate high doses of EUV light, making the process both expensive and energy-intensive. However, the new hafnium clusters developed by this team can create high-resolution patterns with a half-pitch of a few nanometers under an energy dose that is only a fraction of what was previously required. This is a remarkable improvement over previous photoresists, which typically required much higher doses.

Liu explained, “Our new photoresist design increases the hydroxide substitutions of carboxylate ligands in the Hf6O4(OH)4(RCO2)12 clusters, which not only improves EUV resolution but also greatly reduces the required EUV doses.” The study describes the synthesis of a highly hydroxylated Hf6O4(OH)8 (RCO2)8 cluster, highlighting its potential to revolutionize the EUV lithography process by reducing energy consumption and improving efficiency.

The research team utilized a combination of advanced techniques to verify their findings. Thin films of the hafnium clusters were prepared and analyzed using optical microscopy (OM) and atomic force microscopy (AFM), revealing no visible defects and a very smooth surface with minimal roughness. Furthermore, e-beam studies demonstrated the photoresist’s superior sensitivity and resolution capabilities, with patterns achieving high precision under small e-beam doses.

The mechanism behind the improved performance of these photoresists involves two EUV-activated aggregations: Hf-OH dehydration and photolytic decarboxylation. These processes contribute to the formation of highly stable and precise patterns, making the new hafnium clusters an ideal candidate for next-generation semiconductor manufacturing.

Liu emphasized the broader implications of this research, stating, “Our findings open up new possibilities for the development of metal carboxylate clusters as potential EUV photoresists. By enhancing the photolytic decarboxylation and dehydration processes, we can achieve high-resolution patterns with significantly lower energy consumption.” The successful application of these clusters in EUV lithography marks a significant step forward in the quest for more efficient and cost-effective semiconductor fabrication technologies.

In conclusion, the work of Jui-Hsiung Liu and his colleagues represents a major advancement in the field of EUV lithography. Their innovative approach to designing highly hydroxylated hafnium clusters has the potential to transform the semiconductor industry by enabling high-resolution patterning at low energy doses. As the demand for smaller and more powerful electronic devices continues to grow, such breakthroughs will play a crucial role in meeting the technological challenges of the future.

Journal Reference

Tseng, Yu-Fang, Pin-Chia Liao, Po-Hsiung Chen, Tsai-Sheng Gau, Burn-Jeng Lin, Po-Wen Chiu, and Jui-Hsiung Liu. “Highly hydroxylated hafnium clusters are accessible to high resolution EUV photoresists under small energy doses.” Nanoscale Advances, 2023. DOI: