High Resolution CT Cross Section Observation Using Vertical Oblique CT Method

With the advent of three-dimensional stacking in semiconductor packages, the role of X-ray CT in non-destructive failure analysis has become increasingly critical. Additionally, as the internal structures of packages, such as bumps and VIAs, become finer, the demand for higher resolution in X-ray CT continues to grow. However, conventional X-ray CT systems require the sample to be rotated perpendicularly to the X-ray optical axis. This necessitates maintaining a certain distance between the sample and the X-ray source, which precludes high magnification imaging. To address this issue, Oblique CT technology was developed in the early 2000s and has since become prevalent in the semiconductor industry. Oblique CT allows for significantly higher CT imaging magnification compared to conventional CT, enabling CT scans with submicron resolution even for large packages. However, Oblique CT has the disadvantage of not being able to obtain accurate vertical slice images. In our efforts to overcome this limitation as an X-ray equipment manufacturer, we have devised a new imaging technique called Vertical Oblique CT. In this paper, we will first clarify the differences between conventional CT and Oblique CT, and then introduce the new imaging technique called Vertical Oblique CT.