Andrea Redaelli, STMicroelectronics
Embedded Phase Change Memory: From Material Engineering to Technology
Written by Mohamed Atwa
Andrea Redaelli kicked off the tutorial with a short and sweet overview of phase change memory (PCM) from the perspective of both materials engineering as well as device fabrication, validation, and benchmarking. He began by introducing the myriad of nonvolatile memory applications of PCMs in the automotive, consumer electronics, and power electronics industries. The strength of PCMS over other nonvolatile memory technologies (such as NOR, NAND, and DRAM) were highlighted. The value proposition of PCMs, Redaelli emphasized, is that they provide the highest capacity per unit cost when compared to these other nonvolatile memory technologies. Redaelli then weighed the pros and cons of different compositions of the most famous PCM material: germanium antimony telluride (GST). While antimony-rich GSTs have the advantage in terms of read-write speed, germanium-rich tellurides are winning out in terms of long-term data retention. The tutorial then touched on the various materials engineering and device fabrication challenges that are present in GST-based PCMs, such as elemental segregation and resulting device aging problems. Redaelli briefly presented some of the statistical methods and metrics devised to quantify elemental segregation in GST-based PCMs. By carefully tuning the “thermal budget,” the thermal energy and heating rate, supplied during read/write cycles, Redaelli reported on his group’s success in limiting the elemental segregation in GST-based PCMs. Redaelli concluded the talk with a summary of the competitiveness of PCM as a nonvolatile memory technology and a positive outlook for the adoption of the technology to industrial and consumer applications in the near future.