Simultaneous tomography and topography of silicon integrated circuits using full-field swept-source optical coherence tomography

We demonstrate simultaneous tomography and topography of micro-electro-mechanical systems based on silicon integrated circuits using full-field swept-source optical coherence tomography. The optical set-up consists of a swept-source system, a compact Michelson interferometer, and an area detector. The swept-source system comprises a superluminescent diode as a broadband light source in conjunction with an acousto-optic tunable filter as a fast frequency tuning device. By means of sweeping the frequency of the light source, multiple interferograms were recorded and both the amplitude and the phase map of the interference fringe signal were reconstructed. Optically sectioned images of the silicon integrated circuits were obtained by selective Fourier filtering and the topography was retrieved from the phase map. The main advantages of the proposed system are completely non-mechanical scanning, ease of alignment, high stability because of its nearly common-path geometry, and compactness.