Silicon surface processing techniques for micro-systems fabrication

Micromachining of silicon surface and near-surface regions by electron-beam lithography (EBL) and reactive ion dry-etching (RIE), as well as by laser microfabrication techniques is described. Combination of EBL and RIE techniques is used to fabricate quasi two-dimensional (2D) photonic crystal (PhC) structures with aspect ratios at approximately 15. Structural and optical properties of PhC samples with 2D honeycomb lattice are reported, and a complete photonic band gap at wavelengths approximately 2.16 μm is identified from the optical transmission data. Next, laser microfabrication of silicon by femtosecond laser pulses is reported. Processing of silicon under low air pressure conditions (≃5 Torr) is demonstrated to be essentially debris-free process, highly suitable for cutting and scribing of wafers as well for hole drilling. Removal of thin films from the silicon surface by a single-shot laser ablation using mask projection is also demonstrated.