Etching of silicon native oxide using ultraslow multicharged Ar^q+ ions

Etching of native silicon oxide on the silicon surface using ultraslow multicharged Ar^q+ (q > 1) ions is investigated. As opposed to "kinetic sputtering" using singly charged argon ions (Ar¹⁺), oxide removal using multicharged ions is accomplished primarily by a "potential sputtering" mechanism. The ion dose needed to obtain complete oxide removal for different ion charge states is determined. It is demonstrated that by using ultraslow multicharged Ar^q+ ions instead of singly charged ions with higher kinetic energy the native oxide can be physically removed, i.e., without any chemical interactions, essentially with no damage to the Si surface and subsurface region.