ST opts for phase-change memory on 28nm FDSOI

May 19, 2017 // By Peter Clarke
STMicroelectronics NV (Geneva, Switzerland) has opted to use phase-change memory as an embedded non-volatile memory option for its 28nm fully-depleted silicon-on-insulator (FDSOI) manufacturing process.

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.

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