High density and long retention non-destructive readout FeRAM using a linked cell architecture

A 64 Kbit non-destructive readout (NDRO) ferroelectric random access memory (FeRAM) using a 0.6-μm technology is described. The NDRO FeRAM uses a novel linked cell architecture, which minimizes the circuit overhead accepted in Flash memories. This test device has shown 10-year retention and unlimited read operation. An 120-ns NDRO operation is performed at a read voltage of 2.2V. Circuit techniques used in the NDRO FeRAM include: (1) direct programming of ferroelectric capacitors, (2) automatic restoring of read data, and (3) data storing under zero bias conditions. The unique linked cell architecture allows for scaling a cell size down to 6F2, where F is the minimum feature size available.