Optical coherence tomography for non-destructive investigation of silicon integrated-circuits

The development of an ultra-high-resolution high-dynamic-range infrared optical coherence tomography (OCT) imaging system is reported for the novel purpose of sub-surface inspection of silicon integrated-circuits. This approach utilises an almost octave-spanning supercontinuum source and a balanced-detection scheme in a time-domain OCT configuration to achieve an axial resolution of 2.5 μm in air, corresponding to ∼700 nm in silicon. Examples of substrate thickness profiling and device feature inspection capabilities for additional circuit navigation and characterisation are presented.