Nanofabrication of photonic crystal slabs with sealed airholes for optofluidic applications

Suspended 2D Si photonic crystal (PhC) slabs with a 260 nm triangular lattice and 160 nm-diameter airholes were fabricated on a silicon-on-oxide (SOI) substrate using optimized nanolithography and etching processes. Precise PhC pattern transfer from a negative e-beam resist to Ni by liftoff and to Si by plasma etching was achieved. Subsequent wet etch of the underlying SiO2 led to the formation of suspended PhC slabs. The PhC slab was further capped with a SiO2 layer deposited by a two-step glancing angle deposition (GLAD) process. Inverted nanotips were formed during GLAD with an exponentially varying flux angle, and coalesced into a continuous film at a thickness of similar to 260 nm, completely sealing the PhC airholes. The fabricated PhC slabs may be used as the building block for various integrated optofluidics and photonics with enhanced capability for light detection or emission. (C) 2013 Elsevier B.V. All rights reserved.