The formation mechanism and step‐coverage quality of SiO2 films formed by the pyrolysis of tetraethylorthosilicate (TEOS) were studied, using a novel experimental technique called the “multi‐layered micro/macrocavity method.” The growth rate profiles at millimeter (macrocavity) and submicron (microtrench) sales deposited under a total pressure ranging from 2 to 760 Torr were simultaneously analyzed. The step coverage approaches conformal deposition either with decreasing volume‐to‐surface ratio (V/S) of the macrocavity reaction zone or with increasing total pressure. Combining these results with the growth‐rate profiles of the macrocavity shows that two kinds of intermediate species participate in deposition. One is a high‐activity species with a surface sticking probability near 1, and the other is a low‐activity. A nonlinear increase of the growth rate with the macrocavity V/S ratio indicates that a polymerization reaction occurs in the gas phase. A comprehensive model of the deposition kinetics is presented to correlate the step coverage quality and the growth rate uniformity with the operating conditions.

The thermal decomposition process of tetraethoxysilane (TEOS) in the gas phase has been studied using a gas-chromatograph mass spectrometer (GC-MS) connected to an electric furnace. TEOS decomposed over 500°C to give a TEOS dimer and trimer. It has been confirmed that formation of TEOS oligomers occurs in the gas phase. Ethylene, acetaldehyde and ethanol were also detected, which are low-molecular-weight products formed by thermal decomposition of TEOS. Ethylene was the principal product among the low-molecular-weight products. This indicates that triethoxysilanol is an intermediate in the formation of TEOS oligomers.

The deposition mechanism of Si3N4 films from dichlorosilane (DCS) and ammonia, formed by a conventional low‐pressure chemical vapor deposition system, was studied, combining mass spectrometric analysis and the “macrocavity method.” The dominant neutral species in the gas phase are NH3 and aminochlorosilane (ACS), which was produced by the gas‐phase reaction of DCS, in a high NH3 (a large NH3/DCS ratio) condition, while DCS dominantly exists in a low NH3 condition. Contrary to the mass spectrometric results, there is not a major dependence of the kinetic constants of the deposition precursors on the gas‐mixture ratio. By fitting the growth‐rate profiles to an optimal theoretical profile, both of the two kinds of precursor are estimated to have low activity. The conformal step coverage quality agrees with the small sticking probabilities estimated as 10−4 and 10−6. Those precursors can be assigned to DCS and ACS, so that the mass spectrometric data would be consistent with the growth profiles. The conversion to ACS is calculated based on an assumed simple kinetic form and leads to a qualitative interpretation for gas‐mixture ratio‐dependence of conversion. A kinetic model including precursor molecules is presented to correlate the mass spectrometric results, the growth‐rate profiles, and the step coverage quality.

A novel on-line monitoring method for the early detection of overheating in turbine generators has been developed. This paper deals with the gas sampling procedure, the gas-phase concentration changes of the organic species in the turbine generator, and theoretical discussion about overheating-detection.The concentration of the gas-phase organic species in an operating generator has been monitored over a period of 1 year. The results revealed that the background concentration increased for ahout 100 days at the beginning of the operation and then slowly decreased. Bisphenol-A and some molecules were recognized as characteristic decomposition indicators from epoxy. It was theoretically predicted that the slope of rapid concentration increase is corresponding to the overheating temperature and the volume. Detecting the overheating problem is considered feasible by tracing relative concentration gradient of the decomposition species from the materials.

The model of silicon nitride film deposition in a batch furnace from dichlorosilane ( SiH2Cl2; DCS) and ammonia ( NH3) is presented. The gas-phase and surface reaction rates of DCS are estimated from thickness profiles along the gas stream direction, and surface reaction and DCS decomposition are found to be of Langmuir and Lindemann types, respectively. It means that at a normal deposition temperature ( ∼1000 K), some DCS molecules adsorb directly on the Si surface while others decompose into a more reactive intermediate, SiCl2. At higher temperatures, the reverse reaction of DCS decomposition and the subsequent reaction of SiCl2 with NH3 may play significant roles. Using the present reaction rates, we estimate the film thickness profiles across a 12-inch wafer.