ALD on High Mobility Channels: Engineering the Proper Gate Stack Passivation

Abstract

High mobility channels are currently being explored to replace the Si channel in future technology nodes. However, until now the promising bulk properties are very difficult to translate into reality due to a bad passivation of the interface between the gate stack and the substrate. In this paper we want to emphasize that gate stack passivation is the result of a complex interplay between the surface treatment and the ALD process. During ALD on GaAs, the removal of surface oxides is observed. However, this effect does not lead to a good passivation. For Ge, the S-passivation of the interface is studied in combination with different high-kappa. It is clear that the Ge/S/Al2O3 interface is superior to the Ge/S/ZrO2 interface.