Faster, Denser Memory Chips

In the quest for scalable and reliable high capacity memory, a new approach known as resistive random access memory (RRAM) has been making big waves. Now a technology called Crossbar has been developed which will enable RRAM to be integrated with CMOS and standard manufacturing processes to create memory chips with storage densities up to 40 times that of currently available devices like DRAM and flash.

The new design provides a boost in storage capacity and speed because it’s not dependent on moving electrons.  Crossbar uses a nanoscale structure of evenly spaced electrodes stacked on top of one another and oriented at 90 degrees to the underlying layer. Data bits are stored at the junction points using an amorphous silicon spacer, which switches between allowing current to flow between the layers and blocking that current. When a positive voltage is applied to a particular junction, silver nanoparticles form a filament between the silver upper layer and the non-metallic lower layer. When a negative voltage is applied, the process is reversed. Data is then read by testing the conductivity at each junction. And because the spacer retains its state without power, the memory is non-volatile.

In its current version, Crossbar technology can store a terabyte (1,000 gigabytes) of data on a 200 square millimeter chip. In comparison, the densest flash memory currently on the market stores 16 gigabytes in an area of 144 square millimeters.