Chromatic differential arrayed-confocal 3D microscopy for rapid sub-micron profiling of IC packaging substrates

Abstract

Advanced semiconductor packaging and heterogeneous integration demand 3D surface metrology that combines submicron precision with industrial-scale throughput. However, traditional optical methods are inherently limited by the slow speed of mechanical scanning. To overcome this, we propose a chromatic differential arrayed-confocal three-dimensional microscopic imaging (CDAC-3DMI) method. By integrating a digital micromirror device for high-speed programmable pinhole generation with a chromatic differential detection principle, the proposed system enables scanless online 3D topography reconstruction without lateral or axial mechanical scanning. Experiments on packaging substrates validate the measurement fidelity, yielding step-height and Sa relative deviations of less than 3% and 1%, respectively, compared with a commercial laser scanning confocal microscope (Olympus OLS5100), within the measurement uncertainties reported in the validation table. CDAC-3DMI reduces the end-to-end full-resolution 3D acquisition time from 20 s to 65 ms under equivalent measurement conditions, corresponding to a 308-fold improvement in throughput. CDAC-3DMI thus provides a robust, high-throughput, and non-destructive solution for submicron characterization of complex microstructures in high-volume microelectronics packaging production lines.