1.3.3  Via First, Via Middle, and Via Last

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].