Novel Bc Plug Technology For Highly Reliable Mass Productive 0.18 Mu M 1t1c Cob Embedded Fram

We developed a novel BC plug technology for highly reliable mass-productive FRAM embedded smartcard. Despite good retention characteristics of bulk PZT, single bit failures occur after accelerated retention bake test. These failures can be related to a local recess of the BC W-plug which increases the roughness of the electrode and PZT. The resulting poor interface between top electrode and PZT creates diffusion paths for adverse chemicals causing degradation of the ferroelectric capacitors. The recess of the W-plug was removed by implementing a novel double TiN/W plug technology. As a result, we succeeded in completely eliminating single bit failures.