Paper PS-TuP24
Size Effect of Hf Liquidous Nano-particles on PEPVD Growth of HfSiON on SiO₂/ Si

Tuesday, October 29, 2013, 6:00 pm, Room Hall B

In the paper, we show the size effect of metal particles on PEPVD of high-k dielectric thin film for MOSFETs.

In the case of a fewer deposition of Hf, high density hafnium metal nano particles with 2-6 nm diameter are formed on SiO₂/Si surface and subsequent nitrogen plasma exposure (~10 min.) leads to the growth of HfSiON high-k dielectric film with a SiN interface layer. The exposure of atomic nitrogen and ions from the non-equiliblium plasma enables the introduction of N into the film and increases the interfacial reaction rate of Hf and SiO. Within the first 1 min., the Hf nano particles are oxynitrided with the N atoms from the plasma and the O atoms supplied from the lower interface judging from the XPS analysis. The nitridation rate is quite high and the quantitative measure shows the sticking of the N atom to the Hf nano particles reaches 1.0, while it is an order lower for thicker Hf layers more than 50 nm . A contact AFM survey of the Hf nano particles indicates the nano particles are liquidous due to Melting-point depresssion [2]. The following plasma exposure (~ 5 min.) enables the diffusion of Si atoms into the higk -k film from the underlying SiO layer. Following N₂ ICP exposure continuously increases the N atom fraction in the film which is relatively slow compared to the initial stage. The XPS spectrum shows the sea incorporated is mostly nitrides in the film. The spectrum also indicates the interfacial SiO layer is nitrided and this leads to the minimized EOT of the high-k stack structure.

[1] H. Watanabe, Appl. Phys. Lett . 85, 449 (2004).

[2] M . J . Stowell, Proc . Roy . Soc . Lond . A., 318, 231 (1970).