Freescale Develops 24-Mbit Nanocrystal Memory in CMOS

In what it termed a major step toward replacing conventional floating gate-based flash memories, Freescale Semiconductor announced the first production of 24-megabit (Mbit) memory array based on silicon nanocrystals. Silicon nanocrystal memories are part of an advanced class of memory technologies called thin-film storage. Freescale said they are more scaleable than conventional floating gate-based flash technology, as their tunnel oxide thickness can be reduced without impacting data retention. The charge is stored on isolated nanocrystals and is lost only from those few nanocrystals that align with defects in the tunnel oxide -- while the same defects would result in significant charge loss from a conventional floating gate. A thinner tunnel oxide permits lower-voltage operation, substantially reducing the memory module area needed to generate the bit-cell programming voltages, and allowing for significant wafer processing simplifications and manufacturing cost reductions. The combination of higher bit density and reduced cost translates to lower cost per bit to embed silicon nanocrystal memories. Freescale expects significant reductions in cost per bit of silicon nanocrystal thin-film storage memories.


The 24-Mbit memory array technology was manufactured at Freescale's Austin Technology & Manufacturing Center using 90-nanometer (nm) CMOS bulk technology.


"The industry anticipates that conventional embedded flash memory technology will reach its scaling limit within the next four years due to high-operating voltage, fabrication process complexity and cost," said Freescale Chief Technology Officer Dr. Claudine Simson. "A viable alternative is crucial for key suppliers to automotive, wireless and consumer markets to continue to scale their products and add new functionality. Silicon nanocrystal technology offers lower operating voltages, reduced memory module size, simpler process flow and lower manufacturing costs. Additionally, it requires no new materials or wafer fabrication equipment, allowing for immediate compatibility with existing production wafer fabs."http://www.freescale.com