Sacrificial polyvinyl alcohol substrates to transfer atomic layer deposition grown dielectric thin films

In this work, we demonstrate the exfoliation and transfer of metal oxide thin films from sacrificial polyvinyl alcohol (PVA) substrates to target surfaces. The films were deposited directly onto PVA using a standard amorphous Al₂O₃ (alumina) atomic layer deposition (ALD) process and subsequently transferred to SiO₂ or Au. The resulting transferred films are 32 nm-thick and continuous over millimeter-scale lateral dimensions. They exhibit angstrom-scale surface roughness and are structurally robust, remaining physically intact after multiple exfoliations. Our results address not only the transferred films but also the sacrificial PVA substrates–specifically their interaction with chemical vapor deposition processing at elevated temperatures. Most practically relevant, thermal analysis of the PVA reveals a well-defined melting temperature and no observable glass transition, motivating a recommended maximum processing temperature of 226 ^C. Additional thermal factors affecting ALD growth and final film quality, such as the mismatch in thermal coefficient of expansion between PVA and the metal oxide layer, are also discussed. Finally, at the interface between the transferred films and target substrates, we identify residual PVA-derived carbon contamination despite extensive O₂ plasma processing. This finding is consistent with the observed degradation of the transferred films’ dielectric properties, likely due to conductive pathways formed by residual carbon. Addressing this carbon contamination is therefore a critical direction for future work.