Direct Depth Measurement Tool of High Aspect Ratio Via-Hole for Three-Dimensional Stacked Devices

抄録

  The three-dimensional stacking technology of heterogeneous devices is one of the most effective methods to realize high-performance devices without scaling down. The through-silicon via interconnect process is the most commonly for that purpose. The technology that measures the depth of the high aspect via hole with high accuracy is indispensable for metal contamination-free via-middle processes. Displacement measurements from the surface using interference spectra are more accurate compared with measurement from the back side. However, because such a system is not presently available, we decided to build one for trial purposes. As a result, we successfully build a system that was able to directly measure a high aspect via hole (diameter: 3.3 μm; aspect ratio: 15) by using a spectrum interferometer. We believe that this technology can use in the production of next-generation 3D devices for supercomputer.