Tech Shout!

IBM and many other companies in the semiconductor industry are in a race to make faster, yet smaller chips by building silicon transistors from a very rare combination of metals. Today, researchers at IBM announced a further advancement in computer-based simulations that will help to take chip technologies to new levels of function as well as performance. A team of scientists at IBM’s Zurich Research Laboratory used advanced supercomputer-based models to understand the complex behavior of hafnium dioxide, which seems to be a promising new material that could be used in silicon transistors.

Recently, IBM had announced its self-developed “high-k metal gate” technology, which happens to be the first major change to the transistor since the use of silicon semiconductors, and in which Hafnium Dioxide is a key material. This new technology promises enhanced chip performance to benefit computers as well as other electronic systems.

The semiconductor industry has been looking around for a long time now, to find a material for a very important part of the transistor known as the gate dielectric. At present, the materials that are being used tend to limit the semiconductor industry’s ability to keep pace with the progress predicted by Moore’s Law, which is a maxim that predicts a doubling of the number of transistors on a chip, and an associated increase in chip performance every 12 to 18 months.

The scientists at IBM’s Zurich Research Lab have used their skills in computer-based modeling together with the capabilities offered by the IBM Blue Gene supercomputer to determine why Hafnium Dioxide can work better than other high-k materials previously used by the industry.

From this study and many a laboratory experiment, researchers realized that the underlying physics driving the unique electrical behavior of hafnium dioxide when it mixes with silicon was the reason that made this material unique and usable as a gate dielectric.

Alessandro Curioni, supercomputing expert from IBM’s Zurich Lab explained, “Advances in algorithms and their optimal mapping on extremely large and scalable computer hardware such as Blue Gene are empowering us to do accurate and realistic atomic simulations of complex materials. So indeed, today we are able to use supercomputers to investigate materials that will be eventually used in the next generation of supercomputers.”

The approach used by the IBM team is called ab initio molecular dynamics, where the interactions between the particles of the system are derived from the basic laws of physics without employing any empirical data. In the course of their ground-breaking work, the IBM team created more than 50 realistic virtual models of the hafnium silicates with various concentrations of hafnium on the supercomputer. They then simulated the evolution of these structures over a given time period, estimated their dielectric constants and used these results to rationalize experimental findings.

The advantage of computer-based simulations is that, being virtual, they are free of the problems inherent to laboratory experiments, such as the effects of preparation conditions, the purity of the compounds, or the presence of parasitic reactions. Most importantly, with the simulations one can follow what the individual atoms are doing. Computer simulations allow the “intrinsic” and ideal characteristics of a material to be calculated and correlated directly with the structure at an atomic level.

IBM is implementing the technology of using Hafnium Dioxide as a new material in silicon transistors, and will soon apply it to products in 2008.