Investigation of Ge2Te2Sb5 Chalcogenide Films for Use as an Analog Memory

This work investigates the feasibility of using Ge2Te2Sbs chalcogenide films for analog memory. Thick film chalcogenide memory devices provided by Ovonyx, Inc. are characterized to determine how well the devices meet the repeatability, stability and predictability criteria needed to accurately store analog data values. Chalcogenide memory devices take advantage of the phase-shifting nature of chalcogenide materials to store the analog data as a resistance level. An automated test system was developed to characterize the material and the prototype devices with the goal to determine the 1) non-destructive readability of the device at different resistance values; 2) repeatability of programming the device; 3) stability the resistance value has over time; 4) parametric variations between devices; and 5) maximum and reliably achievable analog resolution. The results of these characterizations demonstrate that thick film chalcogenide devices possess the necessary repeatability, stability and predictability properties needed in an analog memory, with at least a 4-bit analog resolution. However, the prototype devices, as produced for this research, do not demonstrate these properties consistently. A full scale, commercial fabrication process is likely to improve the device design and manufacture so it can be used as an analog memory.