Suddenly, MRAM appears to be gaining steam. MRAM is a memory that uses the magnetism of electron spin to provide non-volatility. The technology is said to have unlimited endurance, but to date, MRAM has proven difficult to manufacture in mass volumes.
STT-RAM is a second-generation magnetic-RAM technology that is said to solve some of the problems posed by conventional MRAM structures. Most MRAMs that are now being developed write data by applying the magnetic field generated by a current running through a wire near a tunneling magnetoresistive (TMR) element to change the magnetization. That enables fast operation, but it gobbles power, according to Grandis.
Grandis is taking a different approach. Founded in 2002, Grandis has received total funding of $15 million from several investors, including Applied Ventures, Sevin Rosen Funds, Matrix Partners, Incubic and Concept Ventures.
Other companies are planning to enter the MRAM market, including Avalanche, Crocus Technology, Hynix, IBM-TDK, Renesas, Samsung, Toshiba and others.
Only one company is actually shipping MRAM. Everspin Technologies Inc. recently said it is sampling its highest density MRAM product to date--a new 16-megabit device.
Everspin (Chandler, Ariz.)--a spin-off of Freescale Semiconductor Inc.--is positioning its 16-Mbit MRAM for the SRAM replacement, data retention and related markets. In industrial and related embedded applications, Everspin hopes to displace battery-backed SRAMs or associated discrete solutions--a move that threatens the likes of Cypress, ISSI, Maxim, STMicroelectronics, TI and others.
For its part, Grandis plans to license and possibility make standalone devices based on STT-RAM. Grandis’ STT method uses a spin-polarized current to switch magnetic bits, a technique that the company says consumes less power and enhances scalability. An STT-RAM writes data by aligning the spin direction of the electrons flowing through the TMR element.
In 2005, Renesas Technology Corp. licensed Grandis’ IP and began developing STT-RAM for embedded applications. Then, in 2008, Hynix Semiconductor Inc. licensed Grandis’ IP and began developing STT-RAM for standalone applications.
Grandis is running wafers for Hynix within its plant in Milpitas. Last year, Grandis announced a 300-mm MTJ fabrication facility. Hynix is also reportedly running STT-RAM wafers within its fabs in Korea.
This year, Grandis achieved a milestone in a DARPA Phase I contract. ''These included demonstrating STT-RAM write energy of less than 0.25 pJ, read and write speeds of 5 nanoseconds and thermal stability greater than 60 kBT, all on the same bits, plus projected endurance of greater than 1016 cycles. In fact, we demonstrated these challenging metrics not just at 5 ns but also over a wide range of write speeds from 1 ns to 20 ns,’’ according to the company.