Positive and Negative Dual-Type Hafnium-Based Hybrid Dry Photoresist for Nanolithography

Since the development of lithography technology, photoresist has mainly been processed using a solution method. However, with the continuous miniaturization of process nodes, especially in high-NA EUV lithography processes that require photoresist with a thickness of less than 20 nm, the solution method also faces problems such as precise thickness control and pattern collapse due to capillary action during wet development. Therefore, we used tetrakis(dimethylamido)hafnium (TDMAHf) and 2-buten-1,4-diol (BED) to prepare a Hf-based hybrid thin film as a high-resolution dry photoresist using the molecular layer deposition (MLD) method. Based on this hafnium-based photoresist, we developed two development methods, which resulted in positive and negative dual-type photoresists. We employed inductively coupled plasma etching (ICP) for dry development, resulting in a positive photoresist; and 15% tetramethylammonium hydroxide (TMAH) for wet development, resulting in a negative photoresist. We used electron beam exposure for resolution testing. At a voltage of 25 keV, the sensitivity was 2400 μC/cm². At a voltage of 50 keV, the resolution of dry development could reach 20 nm, while that of wet development could reach 7 nm. Our research results indicate that hafnium-based hybrid photoresists have great potential for use and provide reliable support for the development of more advanced dry photoresists.