Synchrotron-radiation-stimulated etching of SiO₂ thin films with a tungsten nano-pillar mask

A nano-pattern of SiO₂ on a Si (100) surface has been demonstrated by synchrotron-radiation-stimulated etching with a tungsten nano-pillar mask. The reaction gas was a mixture of SF₆ and O₂. The mask was fabricated using a focused ion beam with W(CO)₆ as the source gas. The width and height of the tungsten nano-pillar were ∼80 nm and 160 nm, respectively. Synchrotron radiation irradiation with flowing SF₆ and O₂ effectively etches the silicon dioxide, and the etching process followed the surface photochemical reaction. The etched surface was very flat, and no undercutting occurred during the etching process.