Electrical Phase-Change Memory: Fundamentals and State of the Art

Phase-change random access memory (PRAM) technology is reviewed. PRAM uses the phase change between the amorphous state and the crystalline state caused by Joule heating as its memory mechanism. A change in electrical resistance owing to a phase change is detected by a small electric current. The merits of this approach are that the resistance change is more than one order of magnitude, and its simple structure decreases the number of steps in the manufacturing process. Suppression of reset current for the change from the low-resistance crystalline state to the amorphous state and an improvement in durability against set-reset cycles and high-temperature operation will ultimately be achieved. (C) 2009 The Japan Society of Applied Physics