A review of recent phase change memory developments Guy Wicker Ovshinsky Innovation wicker@ovshinskyinnovation.com

Intel and Micron announce 3D XPoint Technology August 2015 IBM Announces MLC PRAM chip May 2016 OTS OMS

Nerve Impulse Paper June 15, 1955 Stanford Ovshinsky began research into 2 terminal switching devices in 1955 Nerve Impulse Paper June 15, 1955 Ovitron and RRAM development 1956-1963 Ovitron 1959 RRAM Patent 1963

1964 Patent application on Te alloy switching Devices U. S 1964 Patent application on Te alloy switching Devices U.S. Patent 3271591 Ovshinsky, S., “Reversible Electrical Switching Phenomena in Disordered Structures, ” Phys. Rev. Lett, V. 21, no. 20, pp. 1450-1453, Nov. 11, 1968.

OTS isolated OMS memory was first reported at ECD in 1970 D. Nelson, Jan Helbers and Roy Shanks D.L. Nelson, “Ovonic Device Applications”, Journal Non-Crystalline Solids V2 pp528-539, 1970. Prior art to much of 3D-XPoint’s IP

Ovonic Memory Inc. and Intel 256bit Phase Change Memory 1970 1976 ECD Burroughs JV 1024 bits Fully Decoded Ovonic Memory Inc. and Intel 256bit Phase Change Memory 1970 1972 Prototype

128X128X2 integrated OTS isolated OMS array 1987 128X128X2 integrated OTS isolated OMS array

Shortcomings of Memory Speed 2) Reset Current

Optical Disk Development 1984-1992 Rubin and Otah Compound materials for reversible, phase‐change optical data storage M. Chen, K. A. Rubin, and R. W. Barton, Applied Physics Letters 49, 502 (1986)

1991 Inadvertent Polymer film led to sub-2mA devices

1991 Device consistency allowed demonstration of Multilevel Storage

1991 First 225 electrically switched Phase Change Memory

The Ovonic Threshold Switch can be used to implement logic with Higher speeds and more current drive than MOSFETs As an Isolation Element it can work with a wide variety of two terminal memories

Competitive Technologies

STT-MRAM FeRAM Will be employed in 3-8 years Complex and expensive structure High speed and unlimited cycle life FeRAM Will be employed in 3-8 years high performance nonvolatile

ReRAM Unclear what mechanisms are involved Oxide vacancies - Neville Mott Difficult Forming Low Cycle Life CB-RRAM Conductive bridge of metal ions Very low cycle life