NanoXCT - A high-resolution technique for TSV characterization

Lab-based Transmission X-ray Microscopy and X-ray Computed Tomography (TXM/XCT) with sub-100nm resolution are evaluated for their application in process and quality control in microelectronics, particularly for TSV characterization. These are the techniques of choice to localize defects in copper TSVs for 3D IC integration. In contrast to other techniques like Focused Ion Beam cross-sectioning and subsequent Scanning Electron Microscopy imaging, the region of interest, i.e. the TSV, is imaged nondestructively and three dimensionally. For flat samples like thinned wafers, the tilted rotational axis tomography is proposed instead of the limited angle tomography since the better in-plane resolution increases the quality of the resulting tomogram. Yield- and reliability-limiting processes in 3D TSV technology like voids and incomplete filled vias can be made visible for an array of adjacent TSVs during one measurement without affecting the TSV.