592
Y. Li and D. Goyal
Fig. 18.16 CSAM images of TSVs taken by (a) 200 MHz transducer, (b), (c) 1 GHz transducer.
(d) FIB cross section on the TSVs having voids in GHz CSAM (Adapted from Ref. [32])
Fig. 18.17 (a) GHz CSAM image of TSVs without defects. (b) GHz CSAM image of TSVs with
lots of defects showing fringes around the TSVs (Adapted from Ref. [32])
dice stacked on the top, acoustic transducers with higher penetration depth are
desired. As illustrated in Fig. 18.18a, b, acoustic reflection signals in a stacked die
configuration tend to overlap due to multiple reflections from different interface
[33]. As a result, signal from the bottom die (X3) is buried among the overlapped
signals, thus could not be differentiated and form a clear image of the bottom die.
Figure 18.18c shows the schematic of Frequency Domain Imaging (FDI) technique,
Y. Li and D. Goyal
Fig. 18.16 CSAM images of TSVs taken by (a) 200 MHz transducer, (b), (c) 1 GHz transducer.
(d) FIB cross section on the TSVs having voids in GHz CSAM (Adapted from Ref. [32])
Fig. 18.17 (a) GHz CSAM image of TSVs without defects. (b) GHz CSAM image of TSVs with
lots of defects showing fringes around the TSVs (Adapted from Ref. [32])
dice stacked on the top, acoustic transducers with higher penetration depth are
desired. As illustrated in Fig. 18.18a, b, acoustic reflection signals in a stacked die
configuration tend to overlap due to multiple reflections from different interface
[33]. As a result, signal from the bottom die (X3) is buried among the overlapped
signals, thus could not be differentiated and form a clear image of the bottom die.
Figure 18.18c shows the schematic of Frequency Domain Imaging (FDI) technique,