Controlled Cross‐Linking for Water Developable Hf‐Based Dry Resist Prepared via Molecular Layer Deposition

Metal‐containing hybrid resists have attracted considerable attention for advanced lithography owing to their superior performance in resolution, sensitivity, and etch resistance.Beyond these benefits, vapor‐deposited dry hybrid resists offer distinct advantages in film‐component uniformity and process compatibility.However, such vapor‐deposited dry resists typically form highly cross‐linked covalent networks, which require aggressive development conditions for patterning and may not effectively establish a significant solubility switch upon exposure.This paper describes the design and fabrication of a molecular layer deposition (MLD)‐based dry resist featuring a restricted covalent network, enabled by the unique reactivity of ε ‐caprolactone (CL). During deposition, nonring‐opening reactions and double reaction pathways of some ε ‐caprolactone precursors systematically disrupt the long‐range network integrity, thereby significantly enhancing the solubility of the film in deionized water. E‐beam exposure tests confirmed that this resist is developable in deionized water, exhibiting a critical exposure dose of approximately 200 μC·cm −2 , which is lower than many other MLD resists. Infrared spectroscopy (IR) and X‐ray photoelectron spectroscopy (XPS) analyses reveal that the exposure mechanism primarily involves the cleavage of CO, HfO, and HfN bonds, inducing the detachment of main chain ε ‐caprolactone molecules from the film matrix.