Enthalpy-Driven Self-Healing in Thin Metallic Films on Flexible Substrates

Self-healing microelectronics are needed for costly applications with limited or without access. They are needed in fields such as space exploration to increase lifetime and decrease both costs and the environmental impact. While advanced self-healing mechanisms for polymers are numerous, practical ways for self-healing in metal films have yet to be found. A concept for an autonomous intrinsic self-healing metallic film system is developed, allowing the healing of cracks in metallic films on flexible substrates. The concept relies on stabilizing metastable thin films with high mixing enthalpy via segregation barriers. This allows the films to possess autonomous intrinsic self-healing capabilities triggered by cracking at temperatures not detrimental to flexible microelectronics. The effect will be shown on metastable Mo1-xAgx thin films, stabilized via a Mo segregation barrier. Without a segregation barrier, the system is known to exhibit spontaneous Ag particle formation on the surface. This property is controlled and directed to heal cracks and partially restore the electro-mechanical properties of the multilayer system. This mechanism opens up the field of self-healing thin metallic films that could profoundly impact the design of future microelectronics. Metastable thin Mo1-xAgx films exhibit self-healing properties. The system can be stabilized by a segregation barrier. Upon cracking, the barrier directs Ag segregations into the cracks instead of to the surface. The effect is autonomously intrinsic, occurs at room temperature, and it is enhanced with increasing temperature. Cracking of thin metal films causes damage to the flexible polymer substrate. image