Corrosion‐Resistant Ultrathin Cu Film Deposited on N‐Doped Amorphous Carbon Film Substrate and Its Use for Crumpleable Circuit Board

• Published in: Advanced science Vol. 11; no. 40; pp. e2403587 - n/a
• Main Authors: Shim, Chae‐Eun, Lee, Sangseob, Kong, Minsik, Kim, Ik‐Soo, Kwak, Jaeik, Jang, Woosun, Jeong, Se‐Young, Kim, Dong Wook, Soon, Aloysius, Jeong, Unyong
• Format: Journal Article
• Language: English
• Published: Germany John Wiley & Sons, Inc 01.10.2024; John Wiley and Sons Inc; Wiley
• Subjects: Adsorption; Alloys; amorphous carbon; anti‐corrosion; Carbon; copper electrode; Corrosion; Corrosion inhibitors; Energy; flexible circuit board; Graphene; nitrogen‐doping; Polymer films; Polymers; Spectrum analysis; Thin films; copper electrode; nitrogen‐doping; amorphous carbon; anti‐corrosion; flexible circuit board
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.202403587

Copper (Cu) is widely used as an industrial electrode due to its high electrical conductivity, mechanical properties, and cost‐effectiveness. However, Cu is susceptible to corrosion, which degrades device performance over time. Although various methods (alloying, physical passivation, surface treatment, etc.) are introduced to address the corrosion issue, they can cause decreased conductivity or vertical insulation. Here, using the nitrogen‐doped amorphous carbon (a‐C:N) thin film is proposed as a substrate on which Cu is directly deposited. This simple method significantly inhibits corrosion of ultrathin Cu (<20 nm) films in humid conditions, enabling the fabrication of ultrathin electronic circuit boards without corrosion under ambient conditions. This study investigates the origin of corrosion resistance through comprehensive microscopic/spectroscopic characterizations and density‐functional theory (DFT) calculations: i) diffusion of Cu atoms into the a‐C:N driven by stable C‐Cu‐N bond formation, ii) diffusion of N atoms from the a‐C:N to the Cu layer heading the top surface, which is the thermodynamically preferred location for N, and iii) the doped N atoms in Cu layer suppress the inclusion of O into the Cu lattice. By leveraging the ultrathinness and deformability of the circuit board, a transparent electrode and a crumpleable LED lighting device are demonstrated. Through the synergistic effect of the strong C‐Cu‐N bond formation facilitated by the diffused Cu in the N‐doped amorphous carbon (a‐C:N) and the inhibition of Cu vacancy formation by the diffused N in the Cu layer, ultrathin Cu films deposited on the a‐C:N film substrate are corrosion‐resistant. The Cu/a‐C:N thin film is used as an electronic circuit board for crumpled devices.