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

摘要

We have employed molecular beam epitaxy (MBE) to grow high κ dielectric nano-thick films of Al_2O_3 and HfO_2 on Si (100) 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 x 10~(11) cm~(-2) eV~(-1) as deduced from the conductance method, with the leakage current density being 2.4 x 10~(-2) A/cm~2 at V_(fb) - 1 V. The second bi-layer of ALD Al_2O_3 3.0nm/MBE HfO_2 2.0nm showed a dielectric constant of 11.5 and an EOT of 1.7nm. The D_(it) was estimated to be 2 x 10~(11) cm~(-2) eV~(-1) with the leakage being 1.1 x 10~(-4) A/cm~2 at V_(fb) + 1 V.