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 mum² 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. Al₂O₃, which prevents the capacitor from the degradation caused by following integration process. It was found that novel capping Al₂O₃ 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 Al₂O₃ and optimizing its process conditions, the fully integrated ferroelectric capacitor for the 150 nm, 64-Mb, 1T1C FRAM on the 8-inch Si-substrate shows good ferroelectric properties such as a polarization value of 33 muC/cm² with an uniform distribution of sigma = 1.27, and the sensing window of 300 mV at 85degC.