Evaluation procedures for wafer bonding and thinning of interconnect test structures for 3D ICs

Adhesive wafer bonding

“…82,83,96,120,176,188 Aligned wafer-to-wafer bonding with dielectric polymer layers such as BCB is one of the promising approaches for the fabrication of 3D-ICs. 13,14,70,71,76,82,96,116,120,145,176,198,200,205 Figure 11 shows a schematic of a typical process flow, where the fully processed wafers ͑with active devices and multilevel on-chip interconnects͒ are aligned and bonded using BCB as the intermediate adhesive layer, followed by a top wafer thinning and interwafer interconnection. 71,83,105,145 Initially, two processed wafers are aligned to the required tolerances ͑typi-cally within 1 -2 m͒ and bonded using a dielectric adhesive layer under back-end-of-the-line ͑BEOL͒ compatible conditions.…”

Void-free BCB adhesive wafer bonding with high alignment accuracy

“…among the commonly-used bonding adhesives like SU-8 (Iliescu et al 2006), polyimide (Bayrashev andZiaie 2003), and photoresist (Su et al 2001), benzocyclobutene (BcB) has emerging as a widely-used bonding adhesive in the applications of three-dimensional (3-D) integration (Kwon et al 2008;Zhang et al 2006;Kim et al 2013;Ohba et al 2010;lu et al 2003) and MeMS/microsensors (Dragoi et al 2008;Seok et al 2012;Zhou et al 2009;McMahon et al 2008). In MeMS/microsensor applications, BcB has been used as a permanent or temporary bonding material for wafer transfer or heterogeneous integration of MeMS/microsensors and integrated circuits (Brault et al 2010;lapisa et al 2011).…”

Recent progress in 3D integration technology

“…Various kinds of 3D devices or 3D LSIs have been proposed so far [3,4,5,6,7,8,9,10,11,12,13,14,15,16]. The first 3D LSI test chip having three device layers was fabricated using the poly-Si film which is re-crystallized by laser annealing [3].…”