Abstract
A new methodology for inspection of through silicon via (TSV) process wafers is developed by utilizing an optical diffraction signal from the wafers. The optical system uses telecentric illumination and has a two-dimensional sensor for capturing the diffracted light from TSV arrays. The diffraction signal modulates the intensity of the wafer image. The optical configuration is optimized for TSV array inspection. The diffraction signal is sensitive to via-shape variations, and an area of deviation from a nominal via is analyzed using the signal. Using test wafers with deep via patterns on silicon wafers, the performance is evaluated and the sensitivities for various pattern profile changes are confirmed. This new methodology is available for high-volume manufacturing of future TSV three-dimensional complementary metal oxide semiconductor devices.
Highlights
As a method to improve the value of semiconductor devices, three-dimensional (3-D) integration technology using through silicon vias (TSVs)[1] is focused on and developed actively along with design-rule shrinkage
Various manufacturing technologies for 3-D integration with TSVs have been reported, and some of them have been shifted to the mass production phase
The main methods of 3-D integration are chip-to-chip (C2C), chip-to-wafer (C2W), and wafer-to-wafer (W2W) methods, but the W2W methodology is expected as the mainstream from the manufacturing cost point of view.[2,3]
Summary
As a method to improve the value of semiconductor devices, three-dimensional (3-D) integration technology using through silicon vias (TSVs)[1] is focused on and developed actively along with design-rule shrinkage. 1.1 3-D Integration with TSVs. Various manufacturing technologies for 3-D integration with TSVs have been reported, and some of them have been shifted to the mass production phase. The main methods of 3-D integration are chip-to-chip (C2C), chip-to-wafer (C2W), and wafer-to-wafer (W2W) methods, but the W2W methodology is expected as the mainstream from the manufacturing cost point of view.[2,3] Various methods used to create TSVs, such as via first, via middle, and via last methods, are categorized by the TSV formation sequence point of view.. To create TSVs, high-aspect-ratio holes (vias) are formed by deep reactive ion etching (D-RIE). It is necessary to correctly form deep holes with a high aspect ratio; higher-level etching technology and appropriate process control are needed. The shape of the holes after etching is crucial for the following process.[6,7]
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