Ultrathin high-k layers such as hafnium oxide ͑HfO 2 ͒ in combination with a subnanometer SiO 2 or Hf silicate have emerged as Si compatible gate dielectric materials. Medium energy ion scattering ͑MEIS͒ analysis has been carried out on a range of such metal oxide chemical vapor deposition grown HfO 2 / SiO 2 and HfSiO x ͑60% Hf͒ / SiO 2 gate oxide films of thickness between 1 and 2 nm on Si͑100͒, before and after decoupled plasma nitridation ͑DPN͒. The ability of MEIS in combination with energy spectrum simulation to provide quantitative layer information with subnanometer resolution is illustrated and the effect of the DPN process is shown. Excellent agreement on the deduced layer structures and atomic composition with the as grown layer parameters, as well as with those obtained from cross section electron microscopy and other studies, is demonstrated. MEIS analysis of a high-k, metal gate TiN / Al 2 O 3 / HfO 2 / SiO 2 / Si stack shows the interdiffusion, after thermal treatment, of Hf and Al from the caplayer, inserted to modify the metal gate workfunction.

Ultra-thin high-k layers based on HfO

The continuous dimensional reduction drives the development of metrology, analysis and characterization for nano and micro electronics. An enormous worldwide R&D effort focuses on the understanding and controlling materials properties and dimensions at atomic level. Crucial for groundbreaking new developments is the availability of appropriate analytical infrastructures providing techniques with information depths well adapted to the nanoscaled objects of interest. This requires widely accessible, independent complementary metrology, analytical techniques, and characterization. For example new materials and the demand of improved detection sensitivities for contaminants provide huge challenges for the capabilities of current analysis equipment and expertise. At the same time, the availability of complementary competences is crucial for advancement of analytical methodologies through cross-comparison, round-robin, and benchmarking of results. This paper describes the formation of an independent analytical infrastructure within Europe having the expertise and competence to solve metrology problems for development of nanotechnologies. Furthermore, a strategy is shown to establish independently operating ‘Golden Laboratories’ for complementary and reliable metrology, analysis, and characterization adapted to the requirements of industrial partners.

The authors combined electrical and structural characterizations with analytical and spectroscopic measurements in order to fully analyze oxynitride nanofilms on Si that were produced in a minibatch type plasma nitridation reactor. The authors demonstrate that for the investigated samples the result of nitridation is different in the 2-nm-thick SiO 2 films compared to the 5-nm-thick films. In the first case, nitridation results in an increase of the oxide film thickness compared to the non-nitrided film, with a consequent decrease in leakage current and an increase in the electrically measured equivalent oxide thickness ͑EOT͒. In contrast, nitridation of the 5-nm-thick SiO 2 films leads to a reduction of both the leakage current and EOT. Finally, the authors demonstrate that the applied nitridation process results in the desired nitrogen profile with high nitrogen concentration near the top surface or the middle of the SiON film and low nitrogen concentration near the SiON/Si interface, which leads to a relatively low density of interface states at the SiON/Si interface ͑ϳ10 11 states/ cm 2 ͒ for nonannealed films.

No abstract