1997 Volume 40 Issue 4 Pages 353-359
To understand the chemical vapor deposition (CVD) reaction mechanism of the formation of a thin film in a gas phase, it is important to identify the intermediate chemically active species (radicals) for each reaction. Radicals gener-ally have a very short lifetime, therefore, they are very difficult to detect. Molecular beam sampling (MBS) is a method that can extract radicals in the gas phase using free jet expansion. An MBS system was designed to analyze the CVD reaction mechanism in the gas phase near the surface of the wafer. The system consists of a thermal flow-through CVD reactor and three differential pumping vacuum chambers with a quadrupole mass analyzer (QMA). The system was ap-plied to detect radicals produced in the region near the wafer in a thermal TEOS/O3 (tetra-ethyl-orthosilicate) CVD reaction of SiO2 thin film deposition. It was proved that the radicals, from which ethoxy bases of TEOS are extracted, are formed in the gas phase and play an important role in the CVD reaction.
