A Sunnyvale, Calif.-based start-up has set out to create non-volatile memory (NVM) products featuring the smallest die-size and the lowest manufacturing cost per bit. Unity Semiconductor Corp plans to achieve its objective using innovative, multi-layer memory array architectures and a new technology called CMOx, which is based on the use of materials called conductive metal oxides. Unity Semiconductor, founded in 2002, has been processing 64-kbit devices for two years, a 64-Mbit device for one year, and is in design of a 64-Gb device that is now close to tape-out and slated for pilot production in the second half of 2010.
CMOx will yield products with 4x the density and 5-10x the write speed of today’s NAND flash memory. The technology is based upon a Unity-proprietary switching effect that occurs in certain metal oxide combinations, different from that used in today’s flash technology. The memory effect of CMOx technology is based upon the movement of ionic charge carriers. CMOx can be utilized to form a passive cross-point multi-layer memory array, as it does not require a transistor per cell. Other memory technologies, such as phase-change memory (PCM) and magneto-resistive random access memory (MRAM), use a transistor per cell and are not amenable to the cross-point multi-layer chip architecture.
Unity Semiconductor’s multi-layer cross-point array utilizes a resistance change element (although it’s not a Resistive RAM (RRAM) memory cell such as is being developed by a few other companies). Rather, in the CMOx technology, conduction is uniform across the device instead of being filamentary. The cross-point memory array architecture allows for the densest memory devices of all the next-generation NVM technologies. Further, it enables the physical stacking of multiple layers of memory. Unity Semiconductor’s CMOx-based designs use 4 physical layers of multi-level cell (MLC) memory, and is the key to increasing the density of its storage-class memory products.
The initial CMOx 64 Gb-device is expected to clock up to 100 MHz and to have a maximum data rate of 200 MB/sec. Sustained write speeds of 60 MB/s are expected, with sustained read speeds of 100 MB/s.