Volatile and Nonvolatile Memory Devices for Neuromorphic and Processing-in-memory Applications

—The motivation for driving semiconductor devices can be found in the development of advanced computers which can contribute to the betterment in our daily lives. The contribution has been largely made by semiconductor logic devices traveling the pavements identified as technology nodes for device shrinkage that enables high-speed and low-power operations. Lighter and faster processors are the everlasting goals in electronics and computer science, and have been concerned with logic technologies. However, the vast amount of data that should be dealt are consistently requiring an innovative way out of the conventional serial data communication and processing. Data need to be processed in a shorter time but the irreducibilities in logic switching time, data propagation time in metallic interconnection accompanying RC delay, and the time amount spent in the serial communication between logic and memory units should be quenched. It is quite hard to control the former two factors which are largely determined by physical limits and fabrication technology ones in recent days but the latter still has room for reduction by novel devices and architectures specifically designed for maximizing the parallelism in data processing and communication. The semiconductor memories let aside the advancements in processor technologies now is being moved to the center of renovation toward the future computers in the ultimate architecture. In this review, the roles and requirements of semiconductor memories for memory-oriented processors are investigated in the highlights of applications in the neuromorphic system and processing-in-memory (PIM) architectures.