Nano-Ablation of Inorganic Materials Using Laser Plasma Soft X-rays at around 10 nm

Abstract

We have investigated the direct nanomachining of inorganic materials using laser plasma soft X-rays (LPSXs). LPSXs were generated by the irradiation of Ta targets with Q-switched 532 nm Nd:YAG laser light at an energy density of ∼104 J/cm2. Under this condition, Ta plasma emits soft X-rays at around 10 nm. The LPSXs were focused on the surfaces of inorganic materials, using an ellipsoidal mirror that we desined so as to focus LPSXs at around 10 nm efficiently. We found that synthetic quartz glass, fused silica, Pyrex, LiF, CaF2, Al2O3, and LiNbO3 can be machined. Typically, silica glass is ablated at 47 nm/shot, and it has a surface roughness less than 10 nm after 10 shots. To demonstrate lateral resolution, we fabricated a WSi contact mask with 200-nm-pitch line-and-space patterns on quartz glass. After soft X-ray irradiation, trench structures with a width of 70 nm were clearly observed.