A memory cell that has both a DRAM cell and a non-volatile memory cell.
The non-volatile memory cell might include a flash memory or an NROM
cell. The memory cell is comprised of a vertical floating body transistor
with dual gates, one on either side of a vertical pillar of a substrate.
One gate is a polysilicon gate and gate insulator that is adjacent to the
floating body of the transistor and acts as a DRAM cell. The non-volatile
memory cell is constructed on the other side of the pillar with a
floating gate or NROM structure. The DRAM and non-volatile cells are
linked by a drain region coupling the two cells to a memory array
bitline. The bottom of trenches on either side of the pillar have source
regions that are linked to respective source lines of the memory array.