Deeply Penetrating Multi-Modality Imaging for 3DI Overlay Non-Destructive Measurements

In advanced semiconductor manufacturing, die-to-wafer (D2W) and wafer-to-wafer (W2W) hybrid bonding present significant challenges in ensuring precise alignment, especially in three-dimensional integration (3DI), where sub-50 nm placement accuracy is required. Near-infrared (nIR) optical systems, while widely used for overlay measurements, are limited by the penetration depth, field of view (FOV), and the tradeoff between resolution and depth of focus. To address these limitations, we present a novel X-ray Talbot-Lau grating-based interferometry system combined with Moiré-based alignment techniques for high-precision, non-destructive overlay measurements. The modeling was built upon Fourier optics to simulate X-ray propagation through complex multilayer structures, accurately modeling the phase shifts and attenuation effects encountered in a film stack and generating multi-modal images. The simulation results predicted that the system is capable of detecting overlay errors in the sub-50 nm range. The experimental results confirmed that the system achieves a spatial resolution of 2 μm, and the signal-to-noise ratio of the dark-field or full imaging small-angle scatter (FI-SAXS) modality for a programmed defect sample is shot-noise limited. These findings demonstrate that the proposed approach, which provides deep penetration depth and highly accurate alignment detection, has great potential for 3DI overlay error measurement and defect detection in stacking of memory on logic, as well as multi-die advanced memory technologies such as high bandwidth memory (HBM).