High-Fidelity and Large-Area Transfer of Metal Thin Films for Precision Nanofabrication and Integration

Metal electrodes are indispensable in modern electronic and optoelectronic devices, but conventional deposition methods often introduce interface defects, Fermi-level pinning, and thermal or chemical incompatibilities-especially when integrating with 2D semiconductors or unconventional substrates. Transfer printing offers a promising alternative by forming clean, damage-free interfaces and supporting diverse substrate types. However, existing methods face limitations depending on the material system used: sacrificial layers (e.g., polymethyl methacrylate, PMMA; polyvinyl alcohol, PVA) can introduce contamination risks, while soft stamps like polydimethylsiloxane (PDMS) suffer from poor registration accuracy and limited scalability. In this paper, a fully dry, wafer-scale metal thin film transfer method enabled by a shape memory polymer (SMP) with sharply tunable adhesion is presented. By utilizing its sharp thermomechanical transition, the SMP allows precise control of interfacial adhesion, enabling clean and reliable pick-up and release of metal films. High-fidelity transfer of various metals (Cu, Ag, Au, Al) onto flexible and rigid substrates with alignment error as low as ≈0.2 µm over 27 mm (≈0.001%) is demonstrated. Further, a systematic study of adhesion behavior and interfacial mechanics is conducted, providing insights to guide process optimization. This record-level registration, along with dry processing and broad material compatibility, establishes a scalable, contamination-free platform for advanced device integration and heterogeneous systems.