February 6, 2003 12:50 PM PST
Motorola to outline new flash technology
At this month's 2003 IEEE Non-Volatile Semiconductor Memory Workshop, the computing giant will present four papers detailing its work to create new kinds of flash memory. The technical conference starts Feb. 16 in Monterey, Calif.
Flash is used to store data inside devices ranging from consumer-electronics gadgets and cell phones to cars and communications gear. Because flash is a nonvolatile memory, it stores data even when power is turned off. Flash chips are also found in the removable cards used to transfer data between devices--moving pictures from a digital camera to a PC, for example.
Motorola's papers will focus on two methods of dealing with potential future problems while extending the capacity and performance of the company's current flash memory with small tweaks to its existing manufacturing process.
Motorola is creating the two methods because design limitations threaten to hamper today's most widely used silicon-based flash technology manufacturing technique--called floating gate--as the average size of memory cells in a chip grows smaller.
Manufacturers shrink the size of the cells inside each chip and its associated transistors in order to increase the chip's density, or its ability to store data. But many believe floating gate will start to break down once cells become smaller than 90 nanometers, or, as others have it, 65 nanometers. Eventually, all agree, shrinking the size of cells will be impossible to do without increasing their voltage consumption or decreasing their performance or reliability.
Motorola's new methods, dubbed SONOS (silicon-oxide-nitride-oxide-silicon) and Silicon nanocrystals, use different materials to circumvent the voltage effects.
"The papers all deal with the ability to get voltage (use) down to 6 volts from the 9 volt to 12 volts" of today, said Ko-Min Chang, manager of memory devices in the Motorola Semiconductor Product Sector's embedded memory center.
SONOS uses silicon nitrite to replace the silicon used to build a memory cell's floating gate structure. This lets the company reduce the thickness of that gate from about 1000 angstroms to as little as 100 angstroms--thus allowing it to reduce the size and voltage requirements of flash cells without taking a hit in performance and reliability, Chang said.
SONOS flash can be manufactured with the same equipment currently used, but the newer technology will result in cells that are about half the size of a current flash cell. This would let Motorola double the density of its flash chips, or deliver smaller, less-expensive flash memory chips, Chang said.
Silicon nanocrystals, another alternative, accomplish the same feat, but by using a different material.
"We would like to settle on the one that has the most potential, and really drive it," Chang said.Motorola isn't the only chipmaker pushing the limits of floating gate flash. Advanced Micro Devices is working on similar approaches as part of a technology it calls Quantum Well.
Meanwhile, AMD, Motorola, Intel and Texas Instruments are also working on creating new technologies that could replace today's flash memory altogether with higher-performance, lower-power alternatives.
One of the more promising technologies being explored by AMD and Motorola is called MRAM (magnetic random access memory).
Motorola has promised to deliver sample MRAM chips by the end of this year. Meanwhile, the company is aiming to deliver SONOS or Silicon nanocrystal chips at some point in 2004, Chang said.