Carbon nanotube memory coming
- — 17 November, 2007 05:05
Startup Nantero has built a carbon nanotube-based memory wafer using standard semiconductor fabrication processes. This removes a significant hurdle in commercializing the seemingly exotic NRAM (non-volatile RAM) that could replace DRAM, SRAM and flash memory with a universal memory design.
A carbon nanotube has a wall just one atom wide and a diameter on one billionth of a meter. It is the building block for NRAM chips.
Production of NRAM has faced obstacles in the past, including an inability to position the nanotubes reliably across entire silicon wafers, and contamination of supplied nanotubes that made the material incompatible with hyper-clean CMOS semiconductor fabs.
Nantero has solved these problems and has demonstrated the precise alignment of 10 billion nanotubes on a single wafer manufactured in a standard semiconductor fabrication plant. The process treated the nanotube material as a fabric and used standard semiconductor fab techniques such as spincoating, lithography and etching.
It was started with OEM-sourced carbon nanotubes. These were cleansed of impurities, stray particles for example, and then layered onto a wafer with a foundation of flat tubes parallel to one another in a silicon glue, and a second upright tube layer above it, also with parallel tubes and also in silicon. The tubes can be individually bent by putting an electrical charge through them. A bent tube touching another completes a circuit by lowering electrical resistance and signals a binary one. Straighten the bent tube and you have a zero.
The aim is for Natero to licence its intellectual property to semiconductor fabrication suppliers which would then sell NRAM chips to server, PC, notebook and mobile intelligent device manufacturers.
Nantero has been doing NRAM manufacturing research work with LSI Logic, and this was switched to On Semiconductor in May this year when that firm bought the Gresham, Oregon-based fab from LSI.
In July Nantero and HP announced they were working together on a printable memory application.
Greg Schmergel, CEO and cofounder of Nantero, said at the time: "A printable NRAM memory could be deposited on flexible substrates to enable very low cost RFID tags."
We might see the introduction of devices using NRAM chips in 2010, possibly earlier.