Patent No. 6,545,906
INVENTION: A technique for more accurately writing data on magnetic memory chips
BENEFIT: Makes a new kind of nonvolatile semiconductor memory commercially viable
Magnetic random-access memory, or MRAM, has long been held out as a potential next-generation, universal memory technology. It is faster and more durable than the flash memory used in handheld devices, and unlike the dynamic random-access memory used in PCs, it doesn’t lose data when its power is turned off. These attributes make MRAM attractive for everything from digital cameras to instant-on laptops.
But scientists have struggled for years to make it work. MRAM stores data in an array of small magnetic devices, or cells; electrical pulses write data by flipping the cells’ magnetic orientation. The problem: flipping one cell often flips neighboring ones, too. These errors become more and more an issue as the cells become smaller and their shapes less precise. Leonid Savtchenko, a scientist with Motorola in Chandler, AZ, devised a solution-a two-step method of applying the electrical pulses such that only the targeted cell is flipped. It makes MRAM reliable even when the inevitable manufacturing imperfections create irregular-shaped magnetic cells that are particularly prone to accidental flipping. The new approach, awarded a patent last year, “solves the manufacturing uniformity problem,” says MRAM pioneer James Daughton, chief technical officer at Eden Prairie, MN-based NVE, which is also developing MRAM and makes sensors using similar technology.
Savtchenko didn’t live to see his technology proven, but after his 2001 death his colleagues finished its development and named it in his honor. Savtchenko switching made possible the company’s first commercial MRAM chips, which will reach the market later this year. While these early chips will be too expensive for consumer electronics-initial applications will include memory in military systems-Motorola is working on MRAM for wireless devices and is licensing the technology to other chip makers. The combined efforts of Motorola and its licensees mean Savtchenko’s clever solution to a lingering problem won’t be forgotten. -Russ Arensman