In this study, the effect of various reactive gases, such as SF6, NF3, CF4 and Ar, on the SiO2 etch rate was investigated using a low-angle forward-reflected neutral beam technique, where the neutral beam is formed at the reflector by low-angle reflection of ions extracted from the ion gun. The results showed that most of the ions extracted from the ion gun were neutralized and formed a neutral beam by the low-angle reflection technique, regardless of gas species. When SiO2 was etched using energetic reactive radical beams of SF6, NF3, CF4 and Ar formed by the reflection technique, SF6 showed the highest SiO2 etch rate, while Ar showed the lowest. The highest etch rate by SF6 was related to the high flux of energetic radicals formed by the reflection and chemical reactivity of these radicals, while the lowest etch rate by Ar was due to the lack of chemical reactivity, even though the flux of the energetic neutral is similar to that of SF. The SiO2 etch rate was affected by the random low-energy reactive radicals emitted from the ion source, in addition to the energetic radicals formed by the reflection of the energetic ions. Vertical SiO2 etch profiles could be obtained with the low-angle forward-reflection technique, suggesting the formation of a near-parallel energetic radical beam.