The execution order of the TSV fabrication steps depends on the chip fabrication stage at which the via is formed. There are three approaches available [32]: before the devices fabrication (Via first), before metal lines fabrication (Via middle) and after metal lines fabrication (Via last), as sketched in Fig. 1.7.
Figure 1.7.: | The three main approaches for TSV fabrication: Via First, Via Middle and Via Last. Image based on [32]. |