STT-MRAM -- from Seagate???

On June 12, 1989, I flew to Minnesota from Denver, Colorado, picked up a rental car, and drove from Minneapolis to Bloomington to attend a special disk drive conference being held by the leading vendor of cutting-edge 5.25-inch hard disk drives--Imprimis--which was the disk-drive spinout subsidiary of Control Data Corporation (CDC). I had an ulterior motive on this trip: to get two of Imprimis’ 330Mbyte SCSI disk drives for my EDN “All Star PC Project.” The Imprimis drives were the biggest, baddest hard drives available at the time and Imprimis had a world-class lead in high-speed drive design attributable to CDC’s world-class magnetics research center in Bloomington. Unfortunately, June 12, 1989 was also the day that CDC announced Seagate’s purchase of Imprimis and the addition of Imprimis' magnetics research facility to Seagate’s growing technology arsenal. So I arrived at Imprimis to find the conference cancelled and no one to speak with. I left the Imprimis lobby to fly back to Colorado within an hour of my arrival at Imprimis, without the drives. (I did eventually get a pair of those drives for the All Star PC project, but that’s a story for another time.)

Fast forward to 2010--this week in fact. I’m at the 8th International SoC Conference in Newport Beach, California and I’ve just heard a presentation from Seagate’s VP of the Memory Products Group R& D team Pat Ryan. His topic: spin-transfer-torque magnetic RAM (STT-MRAM). This R& D group is part of the Minnesota magnetics research group that Seagate bought 21 years ago and that facility is just celebrating its 50th year of existence.

Despite having written several detailed articles about MRAM and STT-MRAM, I had no idea that Seagate had a team working on the technology, but it makes sense. The fundamental memory cell in an MRAM, STT or otherwise, is the magnetic tunnel junction (MTJ) and it turns out that MTJs are very familiar to disk drive vendors. “We make millions per day,” said Ryan, “to serve as read/write heads in disk drives.” The company has devoted some resources to investigating the use of MTJs in STT-MRAM.

It turns out that Seagate knows a lot about STT-MRAM and MTJs.

Researchers at the company know how to make thin anisotropic magnetic films that allow magnetic polarization that’s perpendicular to the junction, which improves storage stability. They also know how geometric scaling affects read and write currents for STT MTJs. They have put lots of read/write cycles on STT MTJ memory cells and know that the MTJ’s storage abilities do not degrade with extended cycling. They also know that the memory retention is well hardened against external fields and radiation.

Finally, they know that STT MRAM will be giving embedded SRAM, DRAM, and NOR Flash a run for the money starting around the year 2013.

But don’t look for Seagate to be a player in the STT MRAM IC competition. Ryan gave the clear impression that Seagate is currently only interested in enhancing hard-disk drive performance. It will leave the IC race to others.