A novel approach of using a MBE template for ALD growth of high- κ dielectrics

Abstract

We have employed molecular beam epitaxy (MBE) to grow high κ dielectric nano-thick films of Al 2O 3 and HfO 2 on Si (1 0 0) as templates to suppress effectively the formation of the oxide/Si interfacial layer during the subsequent atomic layer deposition (ALD) growth for Al 2O 3. We show marked improvements of electrical performance of the ALD+MBE composite oxides. A first bi-layer composite of ALD Al 2O 3 1.9 nm/MBE Al 2O 3 1.4 nm showed a dielectric constant of 9.1 with an equivalent oxide thickness (EOT) of 1.41 nm. The interfacial trap density D it was 2.2×10 11 cm −2 eV −1 as deduced from the conductance method, with the leakage current density being 2.4×10 −2 A/cm 2 at V fb−1 V. The second bi-layer of ALD Al 2O 3 3.0 nm/MBE HfO 2 2.0 nm showed a dielectric constant of 11.5 and an EOT of 1.7 nm. The D it was estimated to be 2×10 11 cm −2 eV −1 with the leakage being 1.1×10 −4 A/cm 2 at V fb+1 V.