SOFTWARE EVALUATION EXPEDITES INCREDIBLE SHRINKING OF TRANSISTORS.

Somehow, a name like Silicon Dioxide Valley simply would not have the same catchiness as Silicon Valley. But people who work on semiconductors know that silicon alone is not enough to keep the computer revolution going.

Chip makers grow or deposit ultrathin films of silicon dioxide on silicon surfaces to give the electronic chips their desired functionality. Many semiconductor companies have developed their own methodology and modeling software to measure the thickness of these films. This is an important step in the race to make ever smaller microcircuits, because the oxide layer thickness must be reduced proportionately. In a modern manufacturing facility, the oxide may be only 2 nanometers thick--about the space of six atoms stacked end to end.

Engineers have learned that standard techniques of thickness measurement do not work reliably for such extremely thin layers. So, they are developing computer models to help identify where the current methodologies fail. Most of the difficulty occurs because films prepared at atomic dimensions become entangled in quantum phenomena, which must be taken into account to understand the way electrons behave in tiny circuits.

NIST scientists are championing a comprehensive study to compare quantum mechanical simulators and software suites designed to predict the properties of ultrathin silicon dioxide and alternate gate dielectric films. Despite the importance of such models and software, no comparative investigations of the differences between them have been reported. NIST's effort marks the first attempt at an objective evaluation.

Based on software suites available from a variety of university and corporate research groups, NIST researchers identified the relevant strengths and weaknesses of each model. These were presented to the SEMATECH Gate Stack Engineering Working Group and the International Metrology Council during the past year.

The demonstrations drew strong interest from the audience and ultimately prompted the developer of one simulator to modify its software. Since then, a private company has supplied ultrathin films for laboratory measurements at NIST and an evaluation for the second phase of benchmarking, which is now under way. Additional researchers have requested that their simulators be included in this expanded evaluation.