Dielectric reliability of stacked Al2O3-HfO2 MIS capacitors with cylinder type for improving DRAM data retention characteristics

Dielectric reliability in Al2O3(2-3.1nm)-HfO2(3nm) stack capacitor with Metal-Insulator-Si(MIS) structure is investigated in this paper. We propose an optimized capacitor process through the Time-Dependent Dielectric Breakdown (TDDB) data under various process conditions. Furthermore, due to asymmetric current at both negative and positive voltage stress polarities, we show different lifetime extrapolation by a fluence-driven model. As a result, the maximum allowed operating voltage is projected to be 1.7V (failure rate 10ppm during 10year @ 85°C) for Data “0” retention lifetime.