Boffins improve memory capacity

Stack chips on top of one another for a capacity boost - and it's cheaper!

Boffins at Arizona State University have emerged from their smoke filled labs with a new way to improve the capacity of memory chips.

The technique involves stacking memory layers on top of one another inside a single chip and saving on manufacturing costs.

Michael Kozicki, an electrical engineering professor at Arizona State University and director of the Center for Applied Nanoionics said in a statement that his research will mean that devices will become more portable and less dependent on power charging.

His goal has always been to replace NAND Flash memory with another material that is common to the semiconductor industry. He has done this by adding silicon to the memory cell. Realising that the limits of current technology are due to the physical attributes of semiconductors, he thought it would be clever to stack the memory cells rather than spread them out.

Kozicki said that the problem was that if you joined several memory cells together you wouldn't be able to access one without accessing all of the others too, because they were all wired together. He needed a way to isolate each cell so that it has a storage element and an access device.

Instead of using one layer of silicon, Kozicki uses several to allow a three-dimensional memory fabrication process. He found that by adding a diode in the memory cell, the diode would also isolate them.

He did this with layers of different types of silicon, without needing the substrate for controlling the memory cells. Access devices could then be installed in the layers of memory above the silicon substrate.