Precision 3D profile in-line measurement of through-silicon via (TSV) based on high-frequency spectrum signals in the pupil plane

As a deep and fine vertical via, through-silicon via (TSV) is a key factor in three-dimensional (3D) integrated circuit stack, which can pass through a silicon wafer or chip for 3D integration. TSV's 3D profile metrology is one of the key issues in process control. In this work, we propose and demonstrate a non-destructive in situ measurement technology that can be used to measure the 3D geometric profiles of TSV with an aspect ratio of 10. The optical system designed by us can collect high-frequency signals, which contain the whole geometry information of the TSV in the pupil plane. This measurement is proven effective by analysing the high-frequency spectrum of the pupil plane. Our 3D measurement technology can measure TSV profile diameters as small as 5 μm with an aspect ratio of 10:1. The measurement accuracy is ±0.5% comparable with that of SEM measurements using the same sample.