Advanced memories still struggle in mobiles

Memory research managers themselves have scaled back their rhetoric in the past, avoiding the term universal memory altogether. After a period of exaggerated claims, companies became so quiet about any progress that analysts speculated efforts had been severely scaled back in ferroelectric (FRAM), magnetoresistive (MRAM) and phase-change (PRAM) development.

But managers at Freescale Semiconductor Inc., Intel Corp. and Texas Instruments insist that those programs are alive and kicking, even as they acknowledge that the road is long and uphill for any new memory type.

Saied Tehrani, director of MRAM technology, said Freescale demonstrated a 90nm MRAM with an aluminum oxide tunneling layer. The demo showed that the 180nm cell could be shrunk to 2.9^2 in a 90nm logic process, which includes low-k dielectrics. Now, the Freescale MRAM group is replacing aluminum oxide with magnesium, which will reportedly improve the bit resistance and allow the tunneling layer to be thinned slightly.

With aluminum oxide in the magnetic tunnel junction, MRAMs undergo a 30 percent resistance change as the bit changes from zero to one. With magnesium oxide, that resistance change can be 90 percent to 100 percent, with huge implications for MRAM technology.

"Some companies came in with huge expectations that didn't materialize fast enough for them," Tehrani said. "I believe MRAM technology still has a lot of promise, and we are seeing that at Freescale. It still is a challenge getting the cost structure and the volumes to the point where it can have a huge impact on giant markets. That is the challenge with any new memory technology."

Hiroaki Yoda, a manager at Toshiba Corp.'s advanced-memory technology department, said the main challenge still facing MRAM is the large programming current. But Yoda said MRAM technology is making rapid progress, citing "great advances" with the introduction of magnesium oxide barriers and spin momentum transfer technologies.

As a result, "nanosecond read speeds are possible and the objective of reducing programming current has become a little more realistic. This is completely different from other emerging memory technology development efforts, in which no big innovations have been made," Yoda said.

Posted: May 16,2006 by Ron Mertens