Spin-on deposition of amorphous zeolitic imidazolate framework films for lithography applications

Abstract

Amorphous zeolitic imidazolate framework (aZIF) films have been recently introduced as resists for electron beam and extreme ultraviolet lithography. aZIFs are also being considered for separation applications, including thin film membranes. However, the reported methods for aZIF deposition are currently based on highly empirical trial-and-error approaches that hinder control of film composition, thickness and uniformity as well as scale-up and transferability to different coating geometries. This work presents a method for depositing aZIF films with controllable thickness using dilute precursors mixed immediately before encountering the substrate. Importantly, the method is amenable to quantitative analysis by computational fluid dynamics to extract intrinsic deposition rates and limiting reactant transport diffusivities, enabling predictive physics-based modeling of the deposition process. This allows the deposition method to be adapted for spin coating on silicon wafers to prepare high-quality aZIF films with consistently controlled thickness. Using this approach, high-resolution resist performance and wafer-scale use for beyond extreme-ultraviolet lithography of aZIF films is demonstrated. The lack of reliable coating methods for amorphous zeolitic imidazolate framework (aZIF) materials hinders their development for applications such as photolithography and separation membranes. Supported by computational fluid dynamics modeling, the authors develop a spin-coating technique to deposit aZIF films from dilute precursors and demonstrate their wafer-scale use in advanced lithographic processes.