THE FORMATION MECHANISM AND STEP COVERAGE QUALITY OF TETRAETHYLORTHOSILICATE-SIO2 FILMS STUDIED BY THE MICRO MACROCAVITY METHOD

The formation mechanism and step-coverage quality of SiO2 films formed by the pyrolysis of tetraethylorthosilicate (TEOS) were studied, usin g a novel experimental technique called the ''multi-layered micro/macr ocavity method.'' The growth rate profiles at millimeter (macrocavity) and submicron (microtrench) sales deposited under a total pressure ra nging from 2 to 760 Torr were simultaneously analyzed. The step covera ge approaches conformal deposition either with decreasing volume-to-su rface 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 partic ipate in deposition. One is a high-activity species with a surface sti cking 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 comprehensiv e model of the deposition kinetics is presented to correlate the step coverage quality and the growth rate uniformity with the operating con ditions.