# A Short Review of Through-Silicon via (TSV) Interconnects: Metrology and Analysis
## 2 TSV Metrology
### Metal Fill
The rise and fall times are converted into pulse widths, which are digitized using the pulse shrinkage technique to obtain a digital code. This code is then compared with the expected value of a fault-free TSV to detect any faults. [PERSON] et al. [16] have used a focused ion beam (FIB) cutting technique to analyze Cu atom migration in TSVs. They acquired TOF-SIMS (time-of-flight secondary ion mass spectrometry) images to observe voids in the TSV and identify defects in the barrier layer. To achieve depth profiling of the TSV, a precise wafer dicing method was performed, followed by non-in situ plasma FIB cutting, so that only a thin SiO\({}_{2}\) layer covered the sidewalls of the TSV. Dual-beam depth profiling was then used to examine the cut and FIB-polished side of the sample. The effectiveness of the barrier layer in Cu-TSV samples was evaluated, and a comparison between TSVs without potential barriers and those with \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{3}{*}{**hTSV (nm)**} & \multicolumn{6}{c}{**\%Change in Vrosstalk Delay of Defected Conditions**_w.r.t Defect Free Condition_} \\ \cline{2-9}  & \multicolumn{3}{c}{**Air Crack with Connector**} & \multicolumn{3}{c}{**Spherical AIR Void**} \\ \cline{2-9}  & \(\mathbf{R_{con}}\) = 1.05 & \(\mathbf{R_{con}}\) = 2.10 & \(\mathbf{R_{con}}\) = 4.20 & \(\mathbf{R_{con}}\) = 5.04 & \(\mathbf{R_{hole}}\) = 1.05 & \(\mathbf{R_{hole}}\) = 2.10 & \(\mathbf{R_{hole}}\) = 4.20 & \(\mathbf{R_{hole}}\) = 5.04 \\  & \(\mathbf{nm}\) & \(\mathbf{nm}\) & \(\mathbf{nm}\) & \(\mathbf{nm}\) & \(\mathbf{nm}\) & \(\mathbf{nm}\) & \(\mathbf{nm}\) & \(\mathbf{nm}\) \\ \hline
30 & \(-1.3\) & \(-0.2\) & \(-0.14\) & \(-0.12\) & \(1.0\) & \(0.6\) & \(-1.6\) & \(-3.9\) \\ \hline
60 & \(-1.7\) & \(-1.3\) & \(-0.37\) & \(-0.16\) & \(1.1\) & \(0.7\) & \(-1.3\) & \(-2.9\) \\ \hline
90 & \(-1.6\) & \(-0.7\) & \(-0.28\) & \(-0.09\) & \(1.2\) & \(0.8\) & \(-0.9\) & \(-1.7\) \\ \hline
120 & \(-1.5\) & \(-0.5\) & \(-0.16\) & \(-0.03\) & \(1.3\) & \(0.9\) & \(-0.2\) & \(-0.6\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Percentage difference in crosstalk delay of a defective TSV compared to a defect-free case [33]. Figure 5: Physical defects of TSVs, (**A**) [PERSON] et al., used a focused ion beam (FIB) to cut the TSV to analyze Cu atom migration (adapted from [16]). Secondary ion images during the FIB slicing of a TSV with a 50 nm TiN barrier. (**B**) Physical defects of TSVs (adapted from [21]). (**C**) Relying on TSV for electrical interconnection. (**D**) Numerical simulation flow: residual stress analysis based on element birth and death technique and migration analysis based on multi-physics analysis. (adapted from [35]). a 50 nm thick TiN barrier was performed. This method not only characterizes the degree of TSV filling, but also enables the observation of any inhomogeneities in the thickness of the Cu and potential barriers that make up the TSV. Additionally, modern TOF-SIMS instruments equipped with FIB and other sputtering sources (Cs, O, etc.) provide versatility and allow for the analysis of the same sample using several different methods to obtain more comprehensive information. This approach can aid in the identification of TSV defects and help to optimize the manufacturing process to achieve more reliable and efficient 3D integrated circuits (Figure 5). [PERSON] et al. [36] concluded that there is a significant difference in the temperature distribution between intact TSV and defective TSV with some typical defects. The good agreement between experimental validation and simulation results shows that the method is feasible for TSV internal defect detection applications (Figure 6). The intact TSV and the defective TSV exhibit different external characteristics under thermoelectric coupling excitation. In the experiment, the test sample is placed on a heating rod. After a period, the temperature is conducted to the 3D packed sample of the TSV. At the same time, the temperature information is captured by the thermal imaging camera.