Low temperature atomic layer deposition of high-k dielectric stacks for scaled metal-oxide-semiconductor devices

Dielectric stacks of aluminium oxide and zirconium oxide grown by atomic layer deposition at low temperatures between 110 °C and 200 °C from trimethylaluminum/water and tetrakis-(diethylamino)zirconium/water, respectively, are investigated regarding their applicability in Metal-Oxide-Semiconductor (MOS) devices. We characterize the dielectric stacks regarding their electrical qualification in MOS devices and their thermodynamical behaviour, and refer these results to layer structure and morphology. As a result, we can show that the deposition of the stacks at low temperatures (110 °C to 150 °C) in combination with reductive/oxidative post-deposition annealing lead to amorphous dielectrics with remarkably high permittivity, with very low leakage currents in the range of 10− 7 A/cm2, and excellent capacitance-voltage characteristics.