Arnaud Yves Lepert

Impact of the polysilicon doping level on the properties of the silicon/oxide interface in polysilicon/oxide/silicon capacitor structures

Abstract In this work, new observations noted in the capacitance-voltage (CV) behaviour of polysilicon/oxide/silicon capacitor structures are reported. As the doping concentration in the polysilicon layer is reduced, anomalous CV characteristics are observed, which are not related to depletion into the polysilicon layer. By examination of the temperature and frequency dependence of the CV characteristics, in conjunction with analysis and simulation, it is demonstrated that the anomalous CV behaviour is a result of a high density of near monoenergetic interface states located at the silicon/oxide interface. Furthermore, by an examination of the temperature and time of the final anneal (H 2 + N 2 ), a mechanism by which the polysilicon doping level can influence the silicon/oxide interface properties is proposed.

Dopants (P, As, and B) in the polycrystalline silicon/titanium silicide system : Redistribution and activation

In this work we report, for the first time, a comparative experimental study of dopant loss from heavily doped polycrystalline silicon (polysilicon) into overlying titanium silicide due to postsilicidation heat-treatments. The experimental study examines the impact of furnace annealing (750 to 1050°C) and rapid thermal processing for the dopant types phosphorus, arsenic, and boron. The effect of wafer thermal history on percentage activation of dopants in polysilicon is also presented. These results provide a more detailed understanding of polysilicon depletion effects in metal oxide semiconductor field effect transistors and of contact phenomena related to dopant loss and dopant deactivation at the polysilicon/silicide contact.