Memory and Storage

Exclusive: Micron Drops Phase-Change Memory – for Now

07 January 2014

Micron Technology Inc. (Boise, Idaho) has stopped actively selling phase-change memory (PCM) chip but says it still plans to re-enter the market at some point in the future.

The company has removed the 128-Mbit 90nm serial and parallel NOR pin-out PCM devices from the products listed on its website. The company also developed a 45nm 1-Gbit PCM memory that it supplied to Nokia for inclusion in mobile phones although that is not thought to have been offered as a standard product for general sale.

Micron has been selling PCM as an alternative to flash memory since it acquired memory company Numonyx NV in May 2010 but with little apparent success. With moves to vertical stacking of flash memory and numerous companies prototyping resistive memories based on metal-oxide structures the window of opportunity for PCM appears to be closing.

When asked about the absence of any PCM products on the Micron website a spokesman said in email correspondence: "Micron's previous two generations of PCM process technologies are not available for new designs or technology evaluation, as the company is focused on developing a follow-on process to achieve lower cost per bit, lower power and higher performance."

However, whether that focus will ever produce competitive PCM non-volatile memories remains unclear. In October of 2013 Micron said that the plan was to develop process technology for scaling PCM but also said that the future strategy for PCM was under review.

PCM is a non-volatile memory that has been pioneered commercially by Micron after about 40 years in development at multiple companies. PCM uses a change of material phase, from crystalline to amorphous in a thin layer of chalcogenide material to produce resistance change, which is basis for switching and memory storage.

Micron sold two 128-Mbit memories in a 90-nm process originally introduced in December 2008 before launching a 45-nm 1-Gbit PCM in July 2012. In November 2012 Micron said that for future products it would skip the 3X-node and go straight to a 2X-nm node. While that is consistent with Micron's most recent comments, time would appear to be running out for a successful execution. Flash memory is already being manufactured at minimum dimensions below 20nm, densities of 128-Gbit and in vertical stacks of 24 layers.

It is expected that the major non-volatile memory vendors will migrate to stacked flash memories at slightly relaxed geometries before replacing the flash memory with resistive RAM of equivalent density and superior endurance – if the technology can be developed.

STMicroelectronics NV shared research on PCM with Intel and combined with Intel to form a joint venture Numonyx NV, which was sold to Micron in 2010. ST has said it plans to use PCM as an embedded non-volatile memory within future microcontroller products.

Related links and articles:

News articles:

Micron's Phase-Change Memory Under Review

Micron to Spotlight ReRAM at ISSCC

Micron, Rambus Sign Long-term Memory Deal

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