A Novel Encapsulation Technology for Mass-Productive 150 nm, 64-Mb, 1T1C FRAM

In order to realize a cost-effective high density FRAM product over 64-Mb, it is inevitable to develop technologies for a small cell and large wafer size without degradation during full integration. We have successfully demonstrated a fully functional 0.16 μm
²
capacitor size, 64-Mb, 1T1C FRAM on an 8-inch wafer by introducing new integration technologies at 150 nm technology node. One of the key technologies is the use of novel capping layer, i.e. Al
₂
O
₃
, which prevents the capacitor from the degradation caused by following integration process. It was found that novel capping Al
₂
O
₃
layer was very effective to block chronic hydrogen diffusion, and depending on the wafer size, the effective capping layer condition is changed. By introducing a novel capping layer of Al
₂
O
₃
and optimizing its process conditions, the fully integrated ferroelectric capacitor for the 150nm, 64-Mb, 1T1C FRAM on the 8-inch Si-substrate shows good ferroelectric properties such as a polarization value of 33 μC/cm
²
with an uniform distribution of σ = 1.27, and the sensing window of 300mV at 85°C.