Spatial phase-locked combination lithography for photonic crystal devices

Abstract

A new fabrication scheme for two-dimensional photonic crystal devices is presented, based on the combination of interference and electron beam lithography in a spatial phase-locked approach. Here, a photonic crystal grid is defined with high lithography speed and precision by interference lithography and the characteristic device features are introduced by electron beam lithography that is locked by Sparse Sampling Spatial Phase-Locking electron beam lithography to the holographic grid. Both the optical and electron beam exposures are made in the same resist fulfilling a unique threefold purpose with decisive advantage: (i) It serves as optical recording medium to form the photonic crystal grid, (ii) as a fiducial grid for the alignment of the e-beam exposure and (iii) as an e-beam resist to record the exposures. Thereby the precision of interference lithography is combined with the flexibility of e-beam using a single-layer resist system with a particular enhancement of the overall lithography throughput.