Effects of Postdeposition Annealing on the Characteristics of HfO[sub x]N[sub y] Dielectrics on Germanium and Silicon Substrates

Abstract

We have systematically investigated the impact that postdeposition annealing (PDA) has on the physical and electrical properties of thin films sputtered on Ge and Si substrates. These two substrates display contrasting metal-oxide-semiconductor characteristics that we attribute to the different compositions of their interface layers (ILs). We observed an increased incorporation into the dielectric and severe volatilization of the IL on Ge after higher PDA processing. These undesired phenomena in the gate stacks may be responsible for their different electrical properties with respect to those of the gate stacks, i.e., a further scaling of the capacitance-equivalent thickness, a significant presence of fixed positive charges and electron-trapping sites, and a degradation of dielectric reliability. In addition, the anomalous low-frequency-like behavior of the high-frequency capacitance–voltage curves in inversion for the Ge capacitors was predicted from theoretical calculations.