Characteristics of OUM Phase Change Materials and Devices for High Density Nonvolatile Commodity and Embedded Memory Applications

Autor: Stephen J. Hudgens, Sergey A. Kostylev, Tyler Lowrey, Charles H. Dennison, Guy C. Wicker, Wally Czubatyj
Rok vydání: 2003
Předmět:
Zdroj: MRS Proceedings. 803
ISSN: 1946-4274
0272-9172
Popis: Phase change memory devices were originally reported by S. R. Ovshinsky [1] in 1968. A 256-bit phase-change memory array based on chalcogenide materials was reported in 1970 [2], Recent advances in phase change materials, memory device designs, and process technology have resulted in significant advances in phase change device performance, and a new memory device, called Ovonic Unified Memory (OUM), has been developed. This paper will discuss various device and materials characteristics of OUM phase change memory materials of interest in applications for nonvolatile high-density memories. These materials are generally Te chalcogenide based, exploiting the congruent crystallization of the FCC phase and the associated reduction in resistivity that results from crystallization from the quenched amorphous state. Data storage is a thermally initiated, rapid, reversible structural phase change in the film. While rewriteable DVD disks employ laser heat to induce the phase change and modulate reflectivity, OUM technology uses a short electrical current pulse to modulate resistivity. The device geometry and thermal environment dictate the power and energy required for memory state programming. We will review the device structure, characterization data, device performance, and reliability as well as device modeling results. Characteristics of key material and device performance metrics such as crystallization and amorphization programming speed will be presented. Programming algorithms will be discussed for optimizing operating margin for high-density applications. Data retention characteristics will be reviewed along with means for accelerated statistical evaluation. Potential high-density memory array data disturb issues will be identified, and their impact on scalability will be assessed. Scaling attributes and issues will be reviewed.
Databáze: OpenAIRE
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