Invited Paper EM+NS+TF-FrM4
From High-k Dielectrics to Functional Oxides on Silicon: Find More than Moore in More Moore

Friday, November 1, 2013, 9:20 am, Room 102 A

Research on oxide materials is a field of intense investigations, in particular for Information and Communication Technologies. This research has been driven since many years from a scientific and a technological perspective.

25 years ago, a scientific community did nucleate around high-Tc superconductivity, and expanded its research interest towards other materials. The motivation remained to understand the fundamentals of the properties of oxides thin films. To reach such an ambitious goal, physical phenomena had to be studied in clean systems, because of the strong coupling between properties and microstructure in oxide thin films. Rather then focusing on obtaining “bulk like” properties, it is more important to control their microstructural characteristics. To that respect, molecular beam epitaxy (MBE) is a well suited technique, although requiring specific design and components.

In a second recent phase, the quest for a replacement gate dielectric in transistors has been a powerful driver to investigate high quality oxide thin films. Replacing SiO₂ with HfO₂ in MOSFETs was a breakthrough for the microelectronic industry. This research is not over, since the replacement of silicon with compound semiconductors could take place within the next years. It will require changes on the materials structure and sequence to be used in dielectric stacks. Nevertheless, because of its ability to control interfaces and to easily combine analytical capabilities with deposition reactors, MBE is also a powerful learning tool to understand the chemistry of interfaces between oxide and semiconductors [2].

The motivation to understand or to exploit the physical properties of oxide thin films is quite different, but there is clearly cross-fertilization between the various communities. The best example one can give is the development of single crystalline oxides grown directly on semiconductor surfaces. Initially stimulated by the quest for a new gate dielectric, researchers are now able to grow high quality epi-oxide films onto silicon, that can be used as nucleation layers for other “functional” oxides. As expected, the combination of silicon microfabrication techniques with the capability to grow crystalline directly on silicon opens up perspectives for devices exploiting oxide properties with an improved efficiency [3].

The goal of my presentation is to review selected examples of the three phases mentioned, and to highlight exciting research directions in this domain.

[1] J.-P. Locquet et al, Nature394, 453 (1998)

[2] M. El Kazzi et al, Appl. Phys. Lett.99(5), 052102 (2011)

[3] S. Abel et al, accepted for Nature Communications (2013)