Optical inspection of complex patterns of microelectronics products

Low-coherence interferometry is exploited for the high-speed 3D inspection of microelectronics products comprised of composite features of different surface characteristics. Emphasis is on configuring an optimum optical hardware design to deal with large rough objects measuring up to a few hundreds micrometers in height. The inspection speed is improved by extending the lateral field-of-view of a single measurement to cover extensive ranges up to a few tens millimetres. Thin films are also gauged by analyzing the spectrally nonlinear variation of interference signals. The overall performance is demonstrated by measuring metal bumps fabricated on film-coated substrates.