Near-infrared confocal laser scanning microscope system with InGaAs focal plane array

Abstract Today, more and more silicon-based chips apply new flip-chip packages to accommodate the high density and power consumption requirements of electronic products. In this case, defect detection in the flip-chip package is essential. However, silicon-based materials are opaque to visible wavelengths, making it difficult to identify defects within the chip or wafer. By utilizing the property that near-infrared (NIR) light can pass through silicon, NIR confocal imaging is a promising non-destructive method to detect defects inside silicon chips. In this study, we report an integrated near-infrared confocal scanning microscope system consisting of a near-infrared microscope and a near-infrared confocal scanning system, which uses an InGaAs focal plane array as a detector instead of the conventional combination of a small pinhole and a photo-multiplier tube or an avalanche photodiode. The proposed confocal scanner can detect devices of different sizes in the field of view, obtain high-contrast and three-dimensional images of the internal structure, and can be effectively employed as an in-line inspection system for detecting surface and internal defects during chip manufacturing.