The goal of this Workshop was: (i) to review recent progress on the "atomic-scale" physical, chemical, and electrical understanding of ultrathin dielectric films on silicon-based materials, (ii) identify priority directions for future basic research in the field, and (iii) promote interdisciplinary scientific exchange between participants. Over 50 scientists from leading academic, governmental, and industrial laboratories in 18 countries and 15 scientists (poster presenters and observers) from local (St. Petersburg) Institutes and Universities were participating in the Workshop.
The first day of the Workshop begun by reviewing recent advances in experimental studies of the SiO2/Si system in the ultrathin regime with emphasis on (i) microscopic understanding of the growth mechanism (as revealed by high depth resolution and isotopic labeling techniques), and (ii) atomic-scale configuration of the SiO2/Si interface studied by photoemission. The afternoon session was devoted to the current status of the theory of the SiO2/Si and SiOxNy/Si systems. In particular, phenomenological approaches of modeling oxidation kinetics and more sophisticated state-of-the art ab-initio schemes to calculate interfacial microstructure were discussed.
The "hot" topic of silicon oxynitridation was disputed on the second day. Specifically, the participants discussed growth mechanism, various processing issues, analysis and applications of (oxy)nitridation. A significant part of the discussion was devoted to the ideal nitrogen profile in the film (the current thinking is nitrogen should be placed near both dielectric/Si and poly-Si gate/dielectric interfaces) and reaction/processing pathways which can be used to achieve the ideal profile. Seventeen papers were presented at the evening poster session, which was followed by a panel discussion reviewing results of the first two days. Also discussed were: mobile species and elemental processes during oxidation, oxide microstructure, thermodynamics and dynamics of nitrogen in ultrathin films, and electronic band structure.
Surface science approaches certainly needed for sub-5 nm films (using STM, photoemission, optical and other techniques) were reviewed in the morning session on the third day. This was followed by a session on electrical properties and microscopic models of defects which determine ULSI device performance and are, therefore, of particular concern for the semiconductor industry.
The forth day of the Workshop brought a discussion of novel techniques for ultrathin dielectric characterization (including positron annihilation, free electron laser, photoelectric and nonlinear optical techniques) and new substrates (SiC, SiGe) and technologies (SOI). It was clear that these materials and methods represent new and relatively unexplored, but very exciting topics in the field of Si-based science and technology. In the evening, the second panel discussion took place where the following issues were brought up: electrical defects at the interface and their identification, interface structure and the ways it can be understood and optimized; new techniques complementary to conventional tools and their further development; new materials and priority areas of their studies as well as a search for alternative dielectrics, and other issues.
The final day of the Workshop was devoted to hydrogen/deuterium issues and the role of H/D in device reliability. Recent progress in EPR and NRA studies was reviewed.
In summary, the Workshop's conclusion was that despite more than 30 years of intense research, some basic issues of the SiO2/Si system still remain unclear, especially at the atomic scale. An "atomic-scale" understanding of growth mechanisms, microstructure, and defects in both "traditional" (SiO2) and novel dielectrics (oxynitrides in the short term) and substrates is of high demand and will be the focus of near-future research. Novel nanometer resolution techniques and traditional surface science tools, on one hand, and state-of-the art calculational methods, on the other, form a powerful base to address many unresolved issues. Many participants suggested that a similar meeting/workshop to be held in 2-3 years to review results of new experiments that result in part from the ideas generated at this Workshop.