Cross-sectioning For Internal Structure Of Semiconductor Packages Using Ion Beams

Various cross-sectioning methods are being studied for the failure analysis of internal structure in semiconductor packages, owing to confirm the tiny internal defects that are around 1 µm to several nm existing at a depth of several hundred µm or more from the package surface. Among them, laser and plasma FIB (Focused Ion Beam) instruments have been prevalent these days. Laser and plasma FIB can perform a wide range of milling, with more than 1 mm and about 300 µm, respectively. On the other hand, the initial and running costs of both instruments are expensive. In addition, the laser generates a great amount of heat during laser ablation, and heat-sensitive parts in the package are damaged and the milling rate varies greatly depending on the constituent elements. In order to solve these issues, we combine broad Ar ion beam, Ga-FIB, and microfocus X-ray CT (Computed tomography) instruments, which can confirm internal structures, by using a TEM (Transmission Electron Microscopy) mesh as common coordinates. By using this technique, Ar or Ga ions can be accurately irradiated to the target location. Moreover, a broad Ar ion beam or a Ga-FIB instrument is relatively inexpensive and easy to introduce. The cross-sectioning with broad Ar ion beam allows you to make more than 1 mm wide cross-section which is suitable for SEM (Scanning Electron Microscope) imaging with a positional accuracy of about ±10 µm. Ga-FIB milling area is less than 100 µm, but can perform with a good positional accuracy of less than 100 nm. As a result, after confirming the coordinates of the target location via the TEM mesh in the package with microfocus X-ray CT, the high-quality cross-section of the target location can be made by rough milling with a broad Ar ion beam and final milling with a Ga-FIB.