Trimethylaluminum (TMA) is often used as a source gas for composite semiconductor or gate insulator films containing aluminum. However, TMA readily reacts with O2 and this reaction causes film performance to degrade. Film formation is affected by the decomposition properties of the source gas, so it is important to investigate the influence of O2 on the decomposition behavior of TMA. The starting decomposition temperature of TMA was 332°C in an Al2 O3 tube filled with Ar gas, and the decomposition rate increased rapidly above 380°C. However, when TMA was heated in an atmosphere containing more than 1 ppm O2, the temperature at which TMA began to decompose increased. It is assumed that this phenomenon resulted from the formation of methoxy groups through reaction between TMA and O2. Thus, the presence of O2 in TMA not only caused the films to be contaminated with oxygen atoms but also altered the decomposition behavior of TMA. This means that fluctuations in the deposition rate and film performance are caused by the presence of O2 in TMA when deposition conditions are otherwise kept constant. As a result, it is desirable that the O2 concentration present in TMA is maintained below 0.1 ppm during deposition.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry