Effects of Plasma Processing Parameters on the Surface Reactivity of OH(X²Π) in Tetraethoxysilane/O₂ Plasmas during Deposition of SiO₂

The OH(X 2 Π) radical in a 20:80 tetraethoxysilane (TEOS)/O 2 plasmas has been characterized during deposition of SiO 2 using the imaging of radicals interacting with surfaces (IRIS) method. The reactivity of OH at the surface of a growing SiO 2 film has been determined as a function of the applied radio-frequency (rf) plasma power ( P ) and the substrate temperature ( T S ). The reactivity ( R ) of OH during deposition of SiO 2 on a 300 K Si substrate is 0.41 ± 0.04. R decreases as substrate temperature increases but is unaffected by increasing rf power. Translational and rotational temperatures (ϑ T and ϑ R, respectively) of the OH radical are also determined. For a 20:80 TEOS/O 2 plasma ( P = 85 W), ϑ T = 912 ± 20 K and ϑ R = 450 ± 20 K. ϑ T is significantly higher than ϑ R and increases with increasing rf power. Using isotopically labeled 18 O 2 as a precursor, the source of the oxygen in OH is identified as the O 2 gas, not oxygen from the ethoxy groups on TEOS. With these data, the role of OH in deposition of SiO 2 from TEOS-based plasmas and the effects of plasma deposition parameters on film formation are discussed.