Silicon diffusion control in atomic-layer-deposited Al(2)O(3)/La(2)O(3)/Al(2)O(3) gate stacks using an Al(2)O(3) barrier layer

In this study, the physical and electrical characteristics of Al(2)O(3)/La(2)O(3)/Al(2)O(3)/Si stack structures affected by the thickness of an Al(2)O(3) barrier layer between Si substrate and La(2)O(3) layer are investigated after a rapid thermal annealing (RTA) treatment. Time of flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) tests indicate that an Al(2)O(3) barrier layer (15 atomic layer deposition (ALD) cycles, approximately 1.5 nm) plays an important role in suppressing the diffusion of silicon atoms from Si substrate into the La(2)O(3) layer during the annealing process. As a result, some properties of La(2)O(3) dielectric degenerated by the diffusion of Si atoms are improved. Electrical measurements (C-V, J-V) show that the thickness of Al(2)O(3) barrier layer can affect the shift of flat band voltage (V(FB)) and the magnitude of gate leakage current density.