Monday, February 8, 2016

Cubic High-k HfO2 by ALD on high mobility Germanium channels

High mobility Germanium is one of the most promising channel materials for future Logic, perhaps even at 7nm. Here is an open source paper (see abstract below) on using TEMAHf/H2O process for growing high symmetry cubic HfO2 on high mobility Germanium channel. It´s a joint work by University of Tokyo, Japan, and Zhejiang University, China. Until now all silicon based channel gate dielectrics are typically performed by using the HfCl4/H2O process. However, now moving too alternate high mobility channel materials like Germanium, InGaAsand other III/Vs it seem that the gate stack people will revisit the MO-precursors again - interesting!

 
The Takagi-Takenaka group researches the post-scaling semiconductor devices for low-power LSI and on-chip optical interconnection for: Ge/III-V MOSFETs, Tunnel FETs, Si photonics, III-V CMOS photonics, Graphene photonics and 2D material electronics (from Takagi and Takenaka Group)

For those of you interested in additional information from the Takagi and Takenaka Group check out there excellent web pages here: http://www.mosfet.k.u-tokyo.ac.jp/index-e.html

Low temperature formation of higher- cubic phase HfO by atomic layer deposition on GeO/Ge structures fabricated by thermal oxidation  

R. Zhang, P.-C. Huang, N. Taoka, M. Yokoyama, M. Takenaka and S. Takagi
Appl. Phys. Lett. 108, 052903 (2016); http://dx.doi.org/10.1063/1.4941538

We have demonstrated a low temperature formation (300 °C) of higher- HfO using atomic layer deposition(ALD) on an thermal oxidation GeO interfacial layer. It is found that the cubic phase is dominant in the HfOfilm with an epitaxial-like growth behavior. The maximum permittivity of 42 is obtained for an ALD HfOfilm on a 1-nm-thick GeO form by the thermal oxidation. It is suggested from physical analyses that the crystallization of cubic phase HfO can be induced by the formation of six-fold crystalline GeOstructures in the underlying GeO interfacial layer.