Formation process of graphite film on Ni substrate with improved thickness uniformity through precipitation control

Fabrication of a 100 × 100 mm2 nanometer-thick graphite pellicle for extreme ultraviolet lithography by a peel-off and camphor-supported transfer approach

An extreme ultraviolet (EUV) lithography pellicle is used to physically protect a mask from contaminants during the EUV exposure process and needs to have a high EUV transmittance. The EUV pellicle should be fabricated using a freestanding thin film with several tens of nanometer thickness in an area of 110 × 142 mm², which is a challenging task. Here, we propose a peel-off approach to directly detach the nanometer-thick graphite film (NGF)/Ni film from SiO₂/Si wafer and significantly shorten the etching time of the Ni film. Combined with the residue-damage-free transfer method that used camphor as a supporting layer, we successfully fabricated a large-area (100 × 100 mm²) NGF pellicle with a thickness of ∼20 nm, and an EUV transmittance of ∼87.2%.

Semi-transparent graphite films growth on Ni and their double-sided polymer-free transfer

Nanorange thickness graphite films (NGFs) are robust nanomaterials that can be produced via catalytic chemical vapour deposition but questions remain regarding their facile transfer and how surface topography may affect their application in next-generation devices. Here, we report the growth of NGFs (with an area of 55 cm² and thickness of ~ 100 nm) on both sides of a polycrystalline Ni foil and their polymer-free transfer (front- and back-side, in areas up to 6 cm²). Due to the catalyst foil topography, the two carbon films differed in physical properties and other characteristics such as surface roughness. We demonstrate that the coarser back-side NGF is well-suited for NO₂ sensing, whereas the smoother and more electrically conductive front-side NGF (2000 S/cm, sheet resistance − 50 Ω/sq) could be a viable conducting channel or counter electrode in solar cells (as it transmits 62% of visible light). Overall, the growth and transfer processes described could help realizing NGFs as an alternative carbon material for those technological applications where graphene and micrometer-thick graphite films are not an option.