The Challenges of Highly Sensitive EUV Photoresists

Abstract

A prerequisite for good photoresists is high sensitivity, but unfortunately highly sensitive resists are usually accompanied by line roughness. Even if understanding what is causing roughness in resists were not completely in its infancy, we still have not achieved complete answers and effective solutions to these issues. Our group has been working with Zr-based and Hf-based resists almost one decade now and has shown that these resists have incredibly high sensitivity. At the same time, we have shown that these resists after development possess scumming issues and increased roughness. And while we have managed to deal with these scumming issues by employing a variety of strategies, we did not succeed in improving roughness; we have changed our processing method and decreased our size distribution to get a material with more well-defined structure compared to the starting material, but roughness remains. What we are investigating now, is whether a well-defined Zr-monocrystal cluster could be the answer to our problem.

Enhanced Solubility of Zirconium Oxo Clusters from Diacetoxyzirconium(IV) Oxide Aqueous Solution as Inorganic Extreme‐Ultraviolet Photoresists

“…More importantly, the Zr oxo cluster size is markedly smaller than those of reported Zr nanoparticles ( ca . 3.4 nm) [23a] . Compared to some reported metal photoresists, the Zr oxo cluster size is sufficiently small for the current applications ( i. e ., photoresists for achieving high‐resolution patterns).…”

Metal Organic Cluster Photoresists for EUV Lithography

“…These results indicated metal oxide resists with lower molecular weight and narrower molecular weight distribution have the potential to produce patterns without scumming. This hypothesis persuaded us to develop zirconium organic cluster with controlled molecular size and distribution [11]. Direct light scattering (DLS) results of zirconium oxide nanoparticle resist and zirconium organic cluster resist are summarized in Fig.…”

Resolution capability of resist patterns and throughput using alkaline treatment under ultrasonic irradiation

“…So far, several improvements have been attained in terms of resist-materials, photomasks, and exposure machines. These include the development of photoresist materials with high resolution and high sensitivity, [2][3][4][5][6][7] the designing of optical phase-shifting masks, 8) and the optimization of electron beam (EB) conditions such as resolution and accelerating voltage. 9,10) In addition, the higher throughput is also crucial in the semiconductor manufacturing process.…”