Amorphous zinc-imidazolate all-dry resists

Abstract

With the adoption of extreme ultraviolet lithography (EUVL) to decrease microelectronic device dimensions, recent photoresist research has focused on the development of next generation metal-organic resist materials. To enhance lithographic capabilities and mitigate common drawbacks seen from traditional solvent based processes like spin coating and solution phase development, interest has shifted towards solvent-free "dry" deposition and development. These dry techniques can obviate extra processing steps, significantly reduce the amount of solvent waste generated, and even allow for reduced defect density and higher resolution. The process described herein avoids the use of solvents, and ultimately many issues associated with solvents, by depositing metal-organic resists using atomic/molecular layer deposition (ALD/MLD) and developing them using a selective thermal dry etching process. The low temperature (e.g., 100-120 o C) thermal development conditions used in this study are notable in the context of lithography processes, as the high temperatures required in other dry etching processes can be difficult to implement in nanofabrication processes. Our previous work has focused on using amorphous zinc-imidazolate (aZnMIm) films in an all-dry resist technology, achieving resolution down to 22 nm. Here, we explore the role of temperature and time on dry development and examine pattern transfer into silicon substrates. Preliminary pattern transfer experiments suggest that an etch selectivity of at least 7:1 exists for electron-beam treated aZnMIm over silicon using a pseudo-Bosch plasma etch. Our findings demonstrate the feasibility of dry development at lower temperatures and times and suggest potential for aZnMIm as a high-resolution resist for nextgeneration lithography.