ST opts for phase-change memory on 28nm FDSOI
Jean-Marc Chery, chief operating officer of ST, revealed the development during a presentation at ST’s Capital Markets Day held in London, May 11.
ST offers an embedded flash memory option at 40nm and has been working on alternative embedded NVM at 28nm.
Phase-change memory exploits the behaviour of chalcogenide glass that is can be moved reversibly between amorphous and crystalline states with different electrical resisitance. Chery, who has been named as deputy CEO with effect from July 1, said in his presentation that ST is working on PCM-above-IC as its embedded NVM for 28nm. He also said the embedded PCM would meet the most stringent requirements of the automotive industry.
This is significant because previous attempts to introduce PCM have been thwarted by problems with thermal performance and thermal cross-talk in the memory array.
Chery also said that ST has developed an alternative NVM at 40nm that it calls embedded shallow trench memory (eSTM) that has the same functionality as split-gate flash but with a smaller memory cell area.
The choice of PCM by ST contrasts with the choices made by Globalfoundries and Samung, who are both opting to deploy MRAM as the embedded NVM on the FDSOI process which they have developed under licensing deals with ST (see Report: Samsung signs NXP as MRAM-on-FDSOI customer and Globalfoundries offers embedded MRAM on 22nm FDSOI).
Chery did not indicate in his presentation whether ST would wish to license its embedded PCM technology to Samsung and Globalfoundries. Although ST does perform manufacturing of 28nm FDSOI at its 300mm wafer fab in Crolles, the use of foundry suppliers for its digital chips is a key part of its business strategy at 28nm and finer geometries.
Next: A surprise choice
The choice of PCM may surprise some as the technology has been in development for 50 years and failed to make it to market on several occasions. Nonetheless ST has many years R&D experience in PCM having been a joint venture partner with Intel in a company called Numonyx that manufactured NOR flash memories but also researched PCM. Numonyx was acquired by Micron Technology Inc. in February 2010.
Micron brought a stand-alone PCM memory to market with the introduction of a couple of 128-Mbit memories in a 90-nm process in December 2008 before launching a 45-nm 1-Gbit PCM in July 2012. However, the memory struggled to find traction with customers and at the beginning of 2014 Micron pulled PCM from its product line.
Since then Intel has introduced solid-state drives (SSDs) based on a non-volatile memory technology developed with Micron called 3D-XPoint. Neither Intel nor Micron have shared many technical details about 3D-XPoint but some observers have concluded that it is likely to be a new GST formulation of PCM.
Related links and articles:
News articles:
Report: Samsung signs NXP as MRAM-on-FDSOI customer
Globalfoundries offers embedded MRAM on 22nm FDSOI
MRAM is leading embedded NVM race, says IMEC researcher
Intel launches SSD based on 3D XPoint memory
Is 3D XPoint based on phase-change memory?
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