Improved reliability of Al2O3/InGaAs/InP MOS structures through in-situ forming gas annealing

In this paper we report on the leakage currents and time dependent dielectric breakdown characteristics of Al₂O₃/InGaAs/InP MOS structures where the Al₂O₃ dielectric is formed by atomic layer deposition (ALD) and the structures were annealed in-situ in the ALD reactor after Al₂O₃ growth. The effect of an in-situ forming gas (H₂/N₂) anneals and an in-situ H₂/Ar plasma anneals was examined. The in-situ forming gas anneal was found to improve the time dependent dielectric breakdown characteristics without significant degradation of the gate stack capacitance. We also show that the H₂/Ar plasma treatment results in a marked reliability improvement but also causes a significant degradation of the gate stack capacitance which is confirmed by TEM to be a result on an increased physical thickness of the gate dielectric.