▎ 摘　　要

NOVELTY - A large-area hexagonal boron nitride thin film comprises boron nitride crystal planes and having an average surface roughness (RMS) of less than 10 nm. USE - Large-area hexagonal boron nitride thin film used for forming gas/moisture barrier (claimed). ADVANTAGE - The large-area hexagonal boron nitride thin film has excellent uniformity, sufficient thickness and large area. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for production of large-area hexagonal boron nitride, which involves improving the average surface roughness of the crystal plane of the metal substrate by performing a first heat treatment on the metal substrate, and forming a hexagonal boron nitride thin film on the metal substrate.