Polyimide memory: a pithy guideline for future applications

Polymeric materials for use in memory devices have attracted significant scientific interest due to their several advantages, such as low cost, solution processability, high mechanical strength, and possible development of three-dimensional stacking devices. Taking into account the heat resistance for the device fabrication process, polyimides (PIs) are one of the most attractive polymers for memory applications due to their high thermal stability and mechanical strength. In recent years, a large number of studies have revealed that almost all kinds of memory properties from volatile to non-volatile memory can be produced by optimizing the chemical structure of the PIs. Several mechanisms have been discussed in order to explain the switching properties. Among them, two major theories, field induced charge transfer (CT) and filament formation, are thought to explain the phenomena in the PI system. In this article, recent studies of functional polyimides (PIs) for memory applications are reviewed, mostly focusing on the mechanism underlying the switching phenomena. In addition, some progress in the fabrication process for developing high density storage will also be reviewed.