Toshiba currently bonds several traditional flash chips into a multi-chip stacked package. The Apple iPhone 3GS is an example of one manufacturer using this seemingly cutting edge technology. In one chip Toshiba has achieved 32GBytes of storage. But size is always a consideration for portable devices like cell phones. So how do you continue increasing the storage without making the chip too thick?
Enter the nirvana of 3D CMOS manufacturing. SanDisk and Toshiba both have aquired companies who dabbled in the 3D chip area. And I’m not talking multi-chip modules, stacked on on top of another in a really thin profile. These would be laid down one metallic layer at a time in the manufacture process, achieving the thinnest profile theoretically possible. So if you are like me and amazed that 32GBytes of Flash can fit in one chip, just wait. The densities are going to improve even more. But it’s going to be a few years into the future. Three years of development and research is going to be needed to make the 3D Flash chip a manufacturable product.
The basic idea is to stack layers of flash memory atop one another to build a higher capacity chip more cheaply than by integrating the same number of cells into a single layer chip. The stacked chip would also occupy a smaller area than a single layer chip with the same capacity.