Focused ion beam milling of photonic crystals in bulk silicon

Abstract

Focused ion beam (FIB) direct milling was used to fabricate photonic crystals in bulk silicon. The milling requires the sidewalls as nearly perpendicular to the slab as possible and the top profile of the holes to be smooth. The re-deposition of milled material exaggerates the hole profiles. The effects on the sidewall profile and the top periphery due to the beam current, dwell time, and the extra boundary milling have been researched. It turns out that a combination of beam current, dwell time, and milling depth has optimized the sidewalls and top periphery of the holes.