Advanced Encapsulating Barrier Layer Technology for 0.25 μm 1T1C 32Mbit FRAM

As the capacitor size greatly decreases from 1.44 in 4Mb to 0.44 w m 2 in 32Mb FRAM, the hydrogen-damage is severely increased, thus giving rise to the difficulty in protecting the ferroelectric capacitor from the hydrogen attack by using conventional encapsulating barrier layers (EBL). Therefore, it is strongly required to reduce the hydrogen-induced degradation of very small ferroelectric capacitor during the backend integration process. In this paper, we developed double EBL technology by covering whole ferroelectric capacitors again after the Cap-EBL process. The Al 2 O 3 ILD-EBL layer was prepared again after depositing inter-layer dielectrics (ILD) layer, thus eliminating further hydrogen damage during inter-metal dielectrics (IMD) process. Using the double EBL technology, the fully integrated ferroelectric capacitor for 32Mb FRAM exhibits excellent ferroelectric properties such as remnent polarization of 15 w C/cm 2 at 3V. As a result, novel hydrogen-damage free 0.25 w m 15F 2 32Mb FRAM was success...