Extended Data Fig. 8: Environmental stability test under high-humidity conditions.

a, Degradation of Cu-based EXIM films after annealing at 85 °C and 85% relative humidity (RH) for 12 h. Without the Cr-Al capping layer, severe oxidation occurs, as evidenced by visible discoloration and a highly resistive film surface, which disables reliable resistivity measurement using the four-point probe method. In contrast, the Cr-Al capping layer effectively suppresses oxidation under high-humidity conditions. b, Resistance mapping of films with and without the Cr-Al capping layer. A 5 × 5 two-terminal resistor array was fabricated using the same shadow mask (thickness: 200 μm) employed in Supplementary Figs. 5d and 16. Photographic images of the samples were also obtained after the experiment. The resistance mapping clearly visualizes the impact of high humidity on the stability of EXIM shields. While Cr-Al capping layer substantially enhances stability, non-negligible resistance degradation is still observed over time under high-humidity exposure. Notably, the degradation is more pronounced at the edges, suggesting lateral oxidation from unprotected side regions.