Dielectric thinning model applied to metal insulator metal capacitors with Al_2O_3 dielectric

摘要

The extrinsic fails of metal insulator metal capacitors (MIMCAPs) with Al_2O_3 dielectric are modeled by a thinning model that is based on the intrinsic reliability model and the assumption that the extrinsic fails behave like an intrinsic dielectric with a reduced thickness. The intrinsic reliability model is developed from voltage acceleration experiments at four temperatures and four dielectric thicknesses. Voltage and thickness dependence of the logarithm of the intrinsic lifetime scales with the electric field and the temperature dependence is described by an Arrhenius factor. The voltage acceleration is not temperature dependent. The thinning model is shown to consistently describe acceleration experiments with random extrinsic fails of unknown root cause at low defect density (0.1 cm~(-2)) as well as a systematic extrinsic failure mechanism caused by process induced plasma damage. It is also shown that the random extrinsic fails that were investigated on large area teststructures can be extrapolated to much smaller product typical capacitors. A criteria based on the stored energy is derived that allows to decide, whether an extrinsic fail will cause product failure. These results allow a quantitative prediction of early product fails due to the MIMCAP.